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I. INTRODUCTION Process Design was developed as a component of Chemical Engineering and it is applied mainly in the chemical process industries. It is based on unit operations, transport phenomena, reaction engineering, process control, and process economics. Process Design uses empirical techniques, based on long experience of operating plants. The recent trend is for application of fundamental physical, chemical, and engineering principles, use of computer modeling, and molecular and process simulations (Edgar, 2000). Process Design has been applied successfully to the design, construction, and operation of continuous large processing plants, handling mostly homogeneous gas and liquid materials, where the required physical property data are available or can be predicted using reliable techniques. Application of process design to solids processing and to heterogeneous systems is more difficult, because of the limited theoretical knowledge of solids and heterogeneous processes, the inadequate data on physical properties, and the empirical nature of most solids processing equipment (Peters and Timmerhaus, 1991). Modern Process Design is part of Process Systems Engineering, and it is extended to heterogeneous, structured, and formulated materials in continuous, batch, and flexible processes. The characteristics of both process and product are considered at the molecular, nano-, micro-, and macroscopic scale. Product quality and safety are emphasized, in addition to the conventional engineering considerations of energy, process cost, and environmental impact. Detailed process modeling and model validation are essential before engineering design and construction of the processing plant. The recent trends in Process Design are directly applicable to the developing field of Food Process Design, which deals mostly with solids, semi-solids, and heterogeneous materials, emphasizing the quality and safety of the processed food products. Process Design is used in the design of entirely new (grass-roots) plants, but mostly in the expansion of existing production facilities, and in plant upgrading and modernization. New and improved processing facilities are necessary to meet the demands for new products, improved quality, process control, energy saving,
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and strict safety and environmental requirements. Economics and profitability must always be taken into account when designing new or upgraded processing plants. Process and Plant Design are the basic parts of a Feasibility Study of an industrial project. The design and construction of an industrial processing plant involve the stages presented in Table 2.1. Process and plant design are based on the following traditional engineering disciplines: Chemical Engineering, which is concerned with the physical and engineering properties of materials, construction of process flowsheets, material and energy balances, equipment sizing, and plant utilities. Mechanical Engineering, which deals with detailed engineering design of process and utility equipment, piping and material transport equipment, installation and maintenance of industrial equipment, and heating / air conditioning of industrial buildings. Electrical Engineering is concerned with electrical power (e.g., motors), industrial lighting, process control, and automation of the processing plant. Industrial Engineering is concerned with efficient plant operation, better utilization of material and labor resources, time-motion studies, and application of the various occupational and public health regulations at the local, state, and federal levels. The design of food processes and food processing plants is based on the same principles of process (chemical) design, with the additional requirements for food safety and food quality. Food processes, processing equipment, and processing plants must comply with strict hygienic (sanitary) regulations. Optimization of food processes is based on maximum preservation effect with minimum quality damage to the food product, and minimum health hazard to the consumers.
Table 2.1 Design and Construction of Industrial Plant 1. Feasibility Study a. Process Design b. Plant Design 2. Engineering Design a. Process Equipment b. Plant Utilities 3. Plant Construction a. Civil Engineering Works b. Installation of Equipment c. Plant Start-up
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The purpose of Process Design is to meet the needs of an industrial plant for economic production of one or more products. Process Design determines the required type and size of equipment, and operating conditions, which will realize the objectives of a particular process. The results of process design are used in the optimization of the particular process and in the detailed engineering design, construction, and operation of processing plants. Process Design involves the following stages (Figure 2.1): (1) Selection of the proper flowsheet to realize the required production; (2) material and energy balances, which are specifying the process requirements of the plant; (3) sizing and rating of the required industrial process equipment; (4) cost estimation; (5) financial and profitability analysis; (6) parametric optimization; and (7) structural optimization of the process. Flowsheets and material balances are discussed with respect to the design of food processes (Section II). Sizing of process equipment is discussed in the various chapters of this book, and in the specialized literature (Perry and Green, 1997; Walas, 1988; Saravacos and Kostaropoulos, 2002). Practical aspects of plant and equipment design are discussed by Bhartia (1979-1983), and Sandier and Luckiewitz (1987). Mathematical modeling and process optimization is discussed in Chapter 3 of this book. The most commonly used food processes are classified and discussed in Section II, while the special requirements of food plants, related to product quality and safety are discussed in the Section III of this chapter. Plant Design involves detailed engineering and construction of process equipment, utilities, buildings, storage facilities, and waste treatment. Some important aspects of Plant Design are discussed briefly in Section IV, while the process economics are presented in Section V of this chapter. Most of the process and plant design procedures were developed in the chemical process industries, where large quantities of gases and/or liquids are processed continuously into a small number of major products. The same principles can be adapted to batch processes and to processing of solids, which characterize most food processing industries (Douglas, 1988). Design projects that are related to laws and regulations, product safety, employee welfare and accidents, natural disasters, and so forth, are not, in general, evaluated only on the basis of financial profits. This is particularly important in food processing operations, where product safety and quality to the consumers are of primary importance.
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Process Specifications
. '
Process Flowsheet Synthesis , ;
Material and Energy Balances
equipment Sizing and Rating
Structural Optimization
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and Utiljties
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Figure 2.1 Information flow diagram of process design.
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1. Introduction The food processing industry has developed through the years from small, specialized food factories to large processing plants, based mostly on empirical experience, and supported, whenever necessary, by the principles of the underlying sciences of Chemistry and Microbiology. The engineering disciplines, mainly Mechanical and Civil Engineering, were utilized in the construction of food processing equipment and plant facilities. During the recent years, Chemical Engineering has entered into the design, operation and control of food processes, through the application of the successful industrial concepts of Unit Operations, Transport Phenomena, Process Design and Process Control. Systematic Process Design is being adopted in the design of food processes, replacing the empirical approaches of the past. In addition to the principles and techniques of Chemical Process Design, the design of food processes must be based on the principles and technology of Food Science and Engineering. Successful and efficient manufacturing technologies, developed in other industries, can be adapted, modified, and implemented in the food industry. Application of the engineering principles and techniques, used extensively in the process industries, must be accompanied by food safety and quality considerations, which have an overriding role in the overall process design and plant operation. While the terms "processes" and "operations" are used interchangeably in the literature, a process may involve some chemical, biochemical or biological reactions in addition to the strictly physical (or mechanical) operation. Food processing involves several physical unit operations and microbiological, biochemical and chemical processes, which aim at preservation and improvement of food quality, or conversion to safe and nutritional food products in large, economic scale. Food preservation and conversion technology has advanced considerably during the recent years (Fellows, 1990; Heldman and Hartel, 1997). Food Engineering has evolved into an interdisciplinary area of Applied Science and Engineering, based primarily on Chemical Engineering and Food Science. The traditional unit operations of Chemical Engineering have been adapted to Food Processing, taking into consideration the complexity of food materials and their sensitivity to processing conditions (Leniger and Beverloo, 1975; Loncin and Merson, 1979; Heldman and Lund, 1992; Valentas et al., 1997; Ibarz and BarbosaCanovas, 2002). The physical operations of food processing can be analyzed by applying the established concepts of unit operations and transport phenomena of Chemical Engineering (Gekas, 1992; Fryer et al., 1997; Welti-Chanes et al., 2002). In addition to the traditional engineering considerations of process cost, energy optimization and process control, demands on food quality and safety should be satisfied. The need for improved product quality in all industries (Product Engineering) should be taken into consideration in all stages of Process Design. In the food industry, advances in the new field of Food Materials Science should be considered, in respect to the effect of food handling, processing and storage on the structure, physical properties, and quality of food products (Aguilera, 2000).
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Process Design involves basically material, energy, and economic balances. Most food engineering data, such as physical and transport properties, biochemical and microbiological kinetics, are not very accurate, and rough models are used. Approximate estimates may be sufficient for a feasibility study of a particular process or for comparing one process over another (Zaror and Pyle, 1997).. Food process design must integrate processing, packaging, and materials handling for conventional and new technologies and products. Food processes and plants must meet the specific requirements of the food industry for hygienic (sanitary) standards, food quality, process control, and maintenance. Food safety is a strict requirement in all aspects of food process design. Potential health hazards should be considered at the design and specifications of processing equipment and food plant. Good manufacturing practices (GMP) and HACCP standards should be considered at the design stage (Chapter 1). Process simulations and computer techniques, discussed in Chapter 3, can be used to explore the effect of engineering and economic parameters, such as temperature, flow rate, and heat transfer coefficients, on the process performance (Fryer et al., 1997; Georgiadis et al., 1997). Process control and automation, adapted from other industries, must take into consideration the requirements of accurate control of safe thermal processing, time-temperature effects on product quality, and desired micro and macrostructural properties of food products. Plant layout of the processing equipment should be based on the requirements of materials flow, hygienic operation, access to equipment, process control, and maintenance. An optimized design layout should combine the equipment needs with the architectural, civil, structural, and environmental requirements. Process and plant design procedures should comply with the relevant national and international standards, e.g., BS 5750, ISO 9000. 2. Unit Operations in Food Processing The basic Unit Operations of Chemical Engineering, i.e., Fluid Flow, Heat Transfer, and Mass Transfer, have been applied to the food processing industry for many years. The theory on these operations was developed originally for gases and liquids (Newtonian fluids), but in food processing (or food manufacturing) non-Newtonian fluids, semi-solid and solid food materials are handled, and adaptation or extension of the theory is necessary. Some food processing operations, dealing with such complex materials are still treated empirically, using rules, practices and equipment developed through experience (Brennan et al., 1991). Generalized models of unit operations were analyzed by Diefes and Okos (1997). Several specialized unit operations were developed in the food processing industry, and more than 150 such food processing operations were listed by Farkas (1977, 1980). For the purposes of this book, the unit operations of food processing are classified on the basis of the processing equipment, with typical examples shown in Table 2.2 (Saravacos and Kostaropoulos, 2002). The mechanical transport operations include pumping of liquids, pneumatic and hydraulic transport, and mechanical conveying. Pumping can be modeled and simulated, based on the principles of Fluid Flow and the Rheology of fluid food
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materials. However, the other mechanical transport operations are based on empirical rules and specialized equipment, developed through experience of manufacturers of equipment and industrial food processors. Mechanical processing operations constitute a very important part of food processing, dealing mostly with solid and semi-solid materials. Modeling and simulation of these operations is difficult, and empirical rules and equations are sometimes used. Size reduction, agglomeration, mixing, and extrusion, developed in the chemical process industries, are adapted and applied to various food processes. Sorting, grading, peeling, slicing, expression, and forming require specialized equipment, which has been developed for the various food products and processes (Saravacos and Kostaropoulos, 2002). General mechanical separations, such as screening, filtration, and centrifugation, have been adapted from the chemical process industries to various food processes. Cleaning and washing are empirical operations, using specialized equipment, developed for specific food materials. Most of the heat and mass transfer processes used in food processing can be modeled and simulated, using established techniques of Chemical Engineering. Novel non-thermal preservation methods, e.g., irradiation and high pressure processing, are still in the development stage, and specialized process design is required. Food packaging operations are highly specialized, they are difficult to model and simulate, and they are based on the selection of appropriate equipment. Food quality considerations are very important in the selection and operation of processes. Food materials can be considered as either living or non-living plant (or animal) tissues. Fresh fruits and vegetables are considered as living tissues. In most food processing operations, the food materials consist mostly of nonliving tissues (Farkas, 1980). A practical description of the unit operations, used in the processing of fruits and vegetables, was presented by Gould (1996). Fruit and vegetable processing is a large industry, consisting of a large number of small to medium-sized processing plants, and producing several diverse food products. These plants utilize several unit operations, since the materials being processed are solid or semi-solids, sensitive to mechanical and thermal processing. On the other hand, the dairy, edible oil, milling, and beer industries deal with large amounts of fewer products, utilizing a smaller number of conventional unit operations. The scale-up methods, used extensively in Chemical Engineering, are difficult to apply, even to continuous food processing operations, due to insufficient physical property data, and the complex physical, chemical and biological changes in the food systems. Pilot plant data, under similar processing conditions, are necessary for scale-up of industrial operations of complex food processes, like extrusion cooking of starch-based foods (Valentas et al., 1991), or processing of new foods. The pilot plant is useful in determining new food processes, and in testing new processing equipment under industrial operating conditions. It is often used for the production of large samples of new food products, used for storage and marketing tests.
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Table 2.2 Classification of Unit Operations of Food Processing Group of Operations Typical Food Processing Operations
Mechanical Transport
Pumping of Fluids Pneumatic Conveying Hydraulic Conveying Mechanical Conveying Peeling, Cutting, Slicing Size Reduction Sorting, Grading Mixing, Emulsification Agglomeration Extrusion, Forming Screening Cleaning, Washing Filtration Mechanical Expression Centrifugation Heating, Blanching Cooking, Frying Pasteurization Sterilization Evaporation Cooling, Freezing, Thawing Drying Extraction, Distillation Absorption, Adsorption Crystallization from Solution Ion Exchange Ultrafiltration Reverse Osmosis Irradiation High Pressure Pulsed Electric Fields Filling, Closing Metallic, Plastic Packages Aseptic Packaging
Mechanical Processing
Mechanical Separations
Heat Transfer Operations
Mass Transfer Operations
Membrane Separations
Non-Thermal Preservation
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3. Food Process Flowsheets In Food Process Design, flowsheets similar to those of Chemical Process Design are used, i.e., process block diagrams (PBD), process flow diagrams (PFD), process control diagrams (PCD), and process instrumentation and piping diagrams (PID). The selection of a process flowsheet in the chemical and petrochemical industries requires extensive computer calculations and simulations, due to the large number of possible process configurations. The selection of most food process flowsheets is confined to a limited number of alternatives, due to the well-defined basic process, e.g., sterilization, evaporation, drying or packaging (Saravacos and Kostaropoulos, 2002). Auxiliary equipment, such as heat exchangers, can increase the number of alternatives, e.g., for energy optimization, in parts of the basic flowsheet. Food processes handling liquid foods, such as milk and vegetable oils, require extensive piping and more complex flowsheets. Two-dimensional (2D) flowsheets are mainly used for various process equipment, and plant representations. In special cases, three-dimensional (3D) diagrams offer a better visualization of complex processing equipment or processing plants (CE, 1999). Process block diagrams (PBD) are widely used for simple representation of the process, and for preliminary calculations of material and energy balances. Each rectangular block represents individual unit operations or group of operations. The process flow diagrams or process flowsheets (PFD) show more details of the process or plant, using specific symbols for equipment, piping, and utilities. Both PBD and PFD flowsheets can show process details, like material flow rates (kg/h), energy flows (kW), temperatures (°C), and pressures (bar), and they can be combined with tables of data. The process control diagrams (PCD) show the position of the control units in the processing lines, and their connection to the sensors. The process instrumentation and piping diagrams (PID) indicate the type and location of instrumentation, and the type and connections of pipes. In addition to the PBD and PFD, layout diagrams, showing the position of the processing equipment in the food plant are used. For illustrative purposes, a block diagram, a process flowsheet, and a layout diagram for the same food processing plant are shown in Figures 2.2, 2.3, and 2.4. The plant chosen is a tomato-processing facility, producing tomato paste, involving several unit operations and processes and a variety of processing equipment, which will be analyzed in detail in the examples of subsequent chapters of this book. Figure 2.5 shows a 3D flowsheet for the same tomato-paste-processing plant for better visualization of the plant and equipment (Saravacos and Kostaropoulos, 2002).
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Steam Sterilization
Product Figure 2.2 Simplified process block diagram for tomato-paste-processing plant.
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11,12. Condenser/Vacuum
14. Sterilizer Product 15.Aseptic packaging
Figure 2.3 Simplified process flow diagram for tomato-paste-processing plant (see Figure 2.2).
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Figure 2.4 Floor plan (layout of equipment) of a tomato-paste plant (see Figure 2.3), Saravacos and Kostaropoulos (2002).
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Figure 2.5 Simplified 3D process flow diagram for a tomato-paste-processing plant (see Figure 2.3), Saravacos and Kostaropoulos (2002).
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4. Material and Energy Balances The material and energy balances used in Chemical Engineering are applicable to most food process calculations. However, food processes require special attention, due to the complexity of food materials, and the importance of minor food components to food quality. Variations in food composition due to variety, growing conditions, and age of the raw materials, may be significant. Required food composition data can be obtained directly by chemical analysis, or taken from the literature, e.g., the USDA food composition data (Watt and Merrill, 1963). Due to the significant variability of some raw food materials, material and energy balances may be required periodically, during the operation of the food processing plants, e.g., in the seasonal processing of fruits and vegetables (Farkas and Farkas, 1997). Overall and component material balances are calculated at the boundaries of a food process, from the mass conservation equations in the system (Saravacos and Kostaropoulos, 2002): (total mass in) - (total mass out) = (total mass accumulated) (component mass in) - (component mass out) = (component mass accumulated) Material balances are simplified in continuous operations, since the accumulated materials (total and component) are equal to zero. The component material balance can be written for one or more food components, which are important in a given processing operation. Typical components, involved in food processing, are water (moisture), total solids (TS), soluble solids (SS), fat, oil, salt, and protein. The soluble solids are usually expressed as °Brix (% sucrose by weight), measured with refractometers, which are used widely in the laboratory and the processing plant. The concentration of components is normally expressed as mass or weight fractions. Volumetric flows should be converted to mass flows using the density of the material. Energy balances are calculated at the boundaries of a food process, from the energy conservation equation (first law of Thermodynamics) in the system: (total energy in) - (total energy out) = (total energy accumulated) For most process design calculations and equipment sizing, the main energy form considered is heat, and only heat balances are calculated. The mechanical and electrical requirements for pumping, transportation, refrigeration, and operation of the various pieces of process and utility equipment are considered in the detailed process, equipment and plant design. Heat balances involve the enthalpy and specific heats of the various process and utility streams. Thermophysical and thermodynamic data for foods are obtained from food engineering and food properties handbooks and databases (Rahman, 1995; Rao and Rizvi, 1995; Saravacos and Maroulis, 2001). Transport properties of foods are of particular importance in food process and equipment design. Typical physical properties of foods are given in the Appendix.
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The material and energy balances are essential in the design of food processes, processing equipment, process utilities, and waste treatment facilities, in process optimization and control, and in cost analysis of the process and the processing plant. Detailed material and heat balance calculations are given in Example 2.1 at the end of this chapter. 5. Mechanical Processes Mechanical processing operations are very important in food processing. They include mechanical transport of food materials, mechanical processing, and mechanical separations. Mechanical transport includes pumping and mechanical conveyors; mechanical processing is concerned with size reduction, agglomeration size reduction, mixing, and forming; and mechanical separations involve filtration, centrifugation, and expression. Mechanical operations are based on equipment, specific for various processes, developed mostly from experience of equipment manufacturers and users in the chemical and food processing industries. Some empirical equations are applied to specific processes and equipment, but exact mathematical modeling and simulation of the mechanical processes is not feasible, except for pumping, which is based on Fluid Flow and Rheology. Description of mechanical processing equipment, in general, is found in Perry and Green (1997), Walas (1988), and Bhatia (1979-1983), while equipment used in food processing is described by Saravacos and Kostaropoulos (2002). Details of mechanical equipment can be found in bulletins and catalogs of manufacturers and suppliers of processing equipment. Lists of directories of equipment suppliers are by Saravacos and Kostaropoulos (2002). The equipment used in mechanical processing of foods must comply with the principles of hygienic design and operation. The equipment surfaces coming into contact with the food should be made of corrosion-resistant stainless steel, and should be cleanable with the cleaning in place (CIP) system (Jowitt, 1980; Trailer, 1993). a. Mechanical Transport Operations Liquid and semi-fluid foods are transported in food processing plants using various types of pumps, while food particles (powders) and grains are transported by pneumatic conveyors. Hydraulic conveying is used for large food pieces, while various types of mechanical conveyors are used for solid foods, food packages and containers. i. Transport of Fluid Foods Rheological data are required for the design of pumping of fluid foods in piping systems. Most fluid foods are non-Newtonian fluids (Saravacos and Maroulis, 2001), and the power-law model yields useful parameters for the estimation of the Reynolds number, the pressure drop, and the energy requirements (Bernoulli equation). Friction losses in pipes and fittings are estimated using empirical equations (Holland and Bragg, 1995; Saravacos and Kostaropoulos, 2002). The design of most food processes is concerned mainly with heat and mass transfer operations, and the equipment required to carry out these basic operations, e.g., sterilizers, evaporators, and dryers. Transport of food materials is considered
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an auxiliary operation, which is carried out with empirically-designed specialized equipment. Table 2.3 shows some important fluid transport equipment used in food processing. ii. Mechanical Conveyors Several types of mechanical conveyors are used in transporting solid foods, food packages, and containers. Typical units are listed in Table 2.4: b. Mechanical Processing Operations Mechanical processing equipment, used in chemical and mineral processing, such as grinders, mills, agglomerators, and mixers, has been adapted to food processing. Specialized equipment, such as homogenizers, paste and dough mixers, and forming/extrusion, has been developed by equipment manufacturers for specific food processes and products. Some typical mechanical processes, used in food processing, are shown in Table 2.5. c. Mechanical Separation Operations A wide range of mechanical separation equipment is used in food processing. Some basic equipment, such as screens, filters, centrifuges, and cyclones, are adapted to the food industries. Specialized equipment, such as sorters, peelers, and juice extractors, has been developed for specific food processes and food products. A list of mechanical separation equipment is shown in Table 2.6.
Table 2.3 Fluid Transport Equipment Equipment Applications Pumps Centrifugal Radial, axial flow Positive Displacement Lobe, gear, piston, progressive cavity Pneumatic Conveyors Hydraulic Conveyors Low viscosity fluids Dilute suspensions Viscous, sensitive fluids and pastes Particles and grains suspended in air Fruits and vegetables suspended in water
Table 2.4 Mechanical Conveyors Equipment Applications Belt Conveyors Roll Conveyors Screw Conveyors Chain Conveyors Bucket Elevators Particles, pieces, packages Packages, heavy products Pastes, grains Containers Particles, grains
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Table 2.5 Mechanical Processing Operations Equipment Applications Cutting Equipment Slicers, dicers Grinders Roll mills, hammer mills disc grinders, pulpers Agglomerators Rotary pan, drum Fluidized-bed, drying Compression, pelletizing Homogenizers Pressure, colloid mills Mixers Agitated tanks mixers of solids Forming/Extrusion Equipment Forming extruders Twin extrusion cookers Fruits / vegetables meat Cereal grains fruits / vegetable, meat Food granules from food powders Milk products food emulsions Liquid/liquid liquid/solid solid/solid Forming of cereal foods extrusion cooked products
Table 2.6 Mechanical Separations Equipment Screens Sieving equipment Sorters Filters Cake filters, frame, vacuum depth filters Centrifuges Centrifugal separators filtering centrifuges, decanters Cyclone Separators
Applications Food particles, flour Sizing of fruits Fruit juices, wine water, air Milk, vegetable oil fruit juices Particles / air
Mechanical Expression Vegetable oil Expression equipment, Screw presses, juice extractors fruit juices Removal of Food Parts Peeling, pitting Skinning equipment Removal of External Parts Wet cleaners, air cleaners Fruit products animal products Fruit/vegetables grain cleaning
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Table 2.7 Food Packaging Equipment Container Preparation Metal, glass, plastic, paper Filling Equipment Dosing, weighing, valves Closing Equipment Metallic containers, glass closures Plastic containers, cartons and cardboard Aseptic Packaging Form-fill-seal equipment Monoblock, combiblock systems Group Packaging Wrapping Palletizing 6. Food Packaging Processes Food Packaging is highly dependent on packaging equipment, and there is little room for mathematical process modeling and simulation. Specialized equipment is used for container preparation, product filling and closing, and aseptic packaging of foods (Kostaropoulos and Saravacos, 2002). Table 2.7 summarizes the main equipment used in Food Packaging. III. FOOD SAFETY AND QUALITY Food safety and quality are very important requirements of food process design and food processing operations. Food safety refers mainly to microbiological hazards from consuming foods, and secondarily to chemical and physical hazards. Food quality refers to the sensory and nutritive value of foods (Chapter 1). Processing and packaging technologies and equipment must be designed to protect and ensure both food safety and quality. Developments in these areas are discussed in national and international conferences and symposia of scientific organizations. The Institute of Food Technology (/FT) organizes special conferences on food safety and quality (IFT, 2002), covering subjects such as predictive microbiology and rapid microbiological testing methods. Food quality is of fundamental importance to any food process design. It distinguishes food process design from the design of other (chemical) processes. All other considerations of process design (principally economics, but also environmental and energy considerations) must be taken into account. In the final analysis, the food product must be wholesome, safe, and organoleptically acceptable to the consumer. Food quality is an indispensable part of any food process design. The kinetics of quality deterioration is combined with the basic equations of heat and mass transfer in all food processes (see Chapter 1).
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1. Plant Safety Safety of personnel, products, and plant facilities should be considered in any process and plant design. Plant safety is particularly important in the chemical and petrochemical industry, where major accidents and emissions of hazardous chemicals can cause serious injuries, loss of lives, and destruction of facilities (Frank and Arendt, 2002). Process safety regulations should be followed in the design and operation of any processing plant. The following federal agencies regulate the safety of personnel and plant facilities in the USA: Occupational Safety and Health Administration, OSHA (Process Safety Management Standards, Hazardous Operations, HAZOP); Environmental Protection Agency (EPA); and National Fire Protection Agency (NFPA). In addition, the Center of Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE) is concerned with process safety. There are specific requirements, recommended by various organizations, for fire hazards, electric motors, dust explosions, etc. Dust explosions are particularly important in processing and storage of food powders. Moisture-proof electric motors must be used in damp environments, such as canning. Explosion-proof electric motors should be used for dusty environments, such as grain mills and powder conveyors. Steam boilers should be located in a separate boiler house to confine any explosion hazard. Plant layout and construction should prevent accidents caused on the personnel, e.g., special floor coatings, and protective rails in silos. The noise level in the processing areas should be not too high to avoid health problems to the operators. Maximum noise levels, according to Directive 86 / 188 of the European Union, should not exceed 90 dB in 8-hour work, and 93 dB for 4-hour work near the noisy equipment. In some processing areas, the noise level may be excessive, for example 90-110 dB in a bottling plant. In such cases, the operators must take protective measures, e.g., using earmuffs. Noise can be reduced by proper selection of equipment, better foundations and seating of equipment with moving parts, gentle conveying, and isolation of noisy equipment in special rooms. In Food Processing, food safety (protection of the consumers' health) is of paramount importance, and it deserves special consideration over the general plant safety, outlined previously (see following sections). 2. Hygienic Food Process Design Hygienic or sanitary design of food processes and food processing equipment is based on proper selection of construction materials and fabrication techniques, which will facilitate food processing and thorough cleaning of the equipment (Saravacos and Kostaropoulos, 2002). Hygienic design of process equipment must be accompanied by a thorough hygienic design of the whole food process and processing plant (Jowitt, 1980; Brennan et al., 1990; Gould, 1994). Engineering implications of hygienic process design should be considered from the outset of the design process, especially for new food processing systems. The principles of food processing sanitation are described by Kutsuyama (1993). A guide to the sanitary design of food plants and
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food processing equipment was published by Imholte (1984). Hygienic aspects of food processing equipment are discussed by Kessler (1981), and Kessler and Lund (1989). In the European Union (EU), hygienic design of food equipment is developed by the European Hygienic Equipment Design Group (EHEDG, 1997). The EU research and development program LINK includes a project on advanced and hygienic food manufacturing, consisting of hygienic processing, and food process simulation and modeling. 3. Hygienic Standards and Regulations The design and operation of food processes and processing equipment should ensure the microbiological safety of the final food products. Design engineers, equipment manufacturers and food processors should follow strict hygienic standards and government regulations. Government regulations of food processing equipment are essential for the manufacture of safe and wholesome foods and the protection of Public Health. In the USA, the following Government Agencies and Private Organizations have published sanitary standards for rood processing equipment (Troller, 1993): 1) USDA (US Dept. of Agriculture), Washington, DC: 1. Publ. MPI-2 "Accepted Meat and Poultry Equipment", 2. Agric. Handbook No. 191 "US Inspected Meat Packing Plants. A Guide to Construction, Equipment, Layout", 3. "Poultry Processing Equipment". 2) US Dept. of Interior, Washington, DC: Bureau of Commercial Fisheries "Fishery Products and Processing Equipment". 3) US Public Health Service, Washington, DC: FDA (Food and Drug Administration). GMPs. 4) IAMFES (International Association of Milk, Food, and Environmental Sanitarians, Inc.), Ames, Iowa: Committee on Sanitary Procedures "3-A Sanitary Standards". 5) ASME (American Society of Mechanical Engineers), New York: ANSI-ASME F2-1: "Food, Drug and Beverage Equipment". 6) BISSC (Baking Industry Sanitation Standards Committee), New York: 'BISSC Sanitation Standards". 7) AFDOUS (Association of Food and Drug Officials of the United States), Littleton. CO: "AFDOUS Frozen Food Code". 8) National Sanitation Foundation, Ann Arbor, MI: 1. "Food Service Equipment Standards" 2. "Food Preparation and Service Equipment". The 3-A sanitary standards were developed originally for the milk industry, but they have been extended to other food products in the USA and other countries. They resulted from the collaboration of equipment manufacturers, the users of food equipment, the International Association of Milk, Food, and Environmental Sanitarians, the Dairy and Food Industries Suppliers Association (DFISA), the Poultry and Egg Institute of America, and representatives of the USPH/FDA and USDA. A list of the 3-A standards and 3-A accepted practices is presented by Rao (1992). The 3-A standards refer mainly to milk processing equipment, including storage tanks, heat exchangers, pasteurizers, freezers, evaporators, drying equipment, and various fittings. The 3-A accepted practices include HTST pasteur-
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izers, and culinary (potable) steam production. Special E-3-A standards apply to processing equipment for egg products (IAMFES, 1988). In addition to the 3-A standards, the following two rules/regulations should be considered in the USA: The Pasteurized Milk Ordinance, and the Good Manufacturing Practices (GMPs) of the FDA. Equipment used in USDA-inspected food plants must previously be approved and listed in the "Compendium of USDA Approved Equipment". In addition to the US Federal Regulations, the Departments of Health of some states have specific requirements for dairy processing equipment (Clark, 1997a). Special caution is needed, when equipment used in a less regulated industry is applied to strictly regulated food industries, such as meat and poultry. In the European Union (EU), certain general rules apply to the hygienic design of food processing equipment, in addition to the regulations of the individual member-countries. A review of the European regulations for hygienic design in food processing, with emphasis on milk, was presented by Grasshoff (1992). The European Hygienic Equipment Design Group (EHEDG) is concerned with the sanitation of food processing equipment (EHEDG, 1997). The design of modern food processing equipment should be based on databases of hygienic requirements and regulatory standards. Special attention should be given to the sealing spots of moving parts, e.g., rotating and reciprocating shafts, where microbial contamination is possible (Hauser, 1992). Developments in hygienic design of food processing equipment and food plants in Europe are presented in the annual meetings of EHEDG. The EU "Machinery Directives" (e.g., 89 / 392, and 91 / 368) specify that food processing machinery must be designed and constructed as to avoid any risk of infection and sickness. EU documents, such as CEN / TC 153 (CEN = European Standardization Committee, TC = technical committee) specify machinery, safety, and hygienic requirements for various food industries. The standard CEN 1672-2 is concerned about food machinery, safety, and hygienic requirements. The European food industry has, in general, adopted the US 3-A standards within the framework of the standards being developed by the EHEDG. New regulations and standards for various food processing equipment are being published with the notation prEN (provisional European standards). Future requirements in the hygienic design of food factories were discussed by Curiel (2001). Other specifications used in the food industry are the International Standardization Organization (ISO), the German Standardization Authority (DIN) requirements for fittings, the bulletins of the International Dairy Foundation (IDF), and the British standards BS 5750. The symbols "CE" (Conformite Europeenne) on equipment is used as evidence of compliance. A number of guidelines have been published by EHEDG, which are voluntary and complementary to the corresponding national and international hygienic standards. The EHEDG guidelines include the following: 1) Microbiologically safe continuous pasteurization of liquid foods. 2) A method for assessing the in-place cleanability of food processing equipment. 3) Microbiologically safe aseptic packing of food products. 4) A method for the assessment of in-line pasteurization of food processing equipment.
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5) A method for the assessment of in-line steam sterilizability of food processing equipment. 6) The microbiologically safe continuous flow thermal sterilization of liquid foods. 7) The EC Machinery Directive and food processing equipment. 8) A method for the assessment of bacteria tightness of food processing equipment. 9) Hygienic equipment design. 10) Welding stainless steel to meet hygienic requirements. 11) Hygienic design of closed equipment for the processing of liquid food. 12) The continuous and semi-continuous flow thermal treatment of particulate foods. 13) Hygienic design of valves for food processing. The need for thorough hygienic design and operation of the entire food processing line is very important in food processing: A weak link in the processing line is sufficient to nullify the whole hygienic operation. 4. Cleaning of Process Equipment The principles of cleaning, rinsing, and sanitizing of food processing equipment are discussed by Loncin and Merson (1979). Cleaning and sanitation should be considered an integral part of food process design and food processing operations (Plett, 1992). The food processing equipment should be designed to facilitate the removal and draining of all the process effluents (steam condensate, waste solids, e.g., peels). All dead ends in tanks, containers, and piping should be eliminated. Fouling is particularly important in heat exchangers and other installations involving fluid flow (evaporators, filters, cyclones, etc.). Empirical models have been suggested to describe heat-induced fouling and its relationship to the overall heat transfer coefficient (U) and the pressure drop (AP), Fryer (1997). The food processing equipment must be cleaned easily either by quick dismantling and cleaning the parts, or by Cleaning In Place (CIP) techniques. The equipment of small food processing plants is usually cleaned by periodic dismantling of the principal units, such as pumps, plate heat exchangers, filters etc. Quick dismantling and re-assembling of process piping is facilitated by various handopening clumps. The design and installation of CIP systems in large food processing plants requires specialized experience in pipe flow, sanitation, processing operations, and process control (Jowitt, 1980; Seiberling, 1997; Saravacos and Kostaropoulos, 2002). The CIP system involves the following sequential operations: 1) Pre-rinsing with cold (soft) water; 2) alkali wash (supplemented with sodium hypochlorite); 3) intermediate water rinse; 4) acid rinse; 5) final water rinse; and 6) rinse with sanitizing solution (sodium hypochlorite) or flushing with hot (90 °C) water. The CIP system is actually a chemical cleaning operation, in which the chemical solution is brought into contact with all soiled surfaces. Addition of surface active substances, reducing substantially the surface tension of water, facilitates the penetration of water and aqueous cleaning solutions into crevices of the equipment. The required tanks, pumps, pipes, valves and heaters (heat exchangers
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or steam injection devices) are used either as single-use or re-use (re-circulation) systems. Air-operated piston or diaphragm-type pumps are used to feed the chemical solutions. For safety reasons, the pumps and the chemical supply containers are enclosed in a separate compartment of the processing plant. Ball spray devices are used to clean process and storage tanks. Cylindrical and rectangular tanks are cleaned using liquid feed rates of 8-12 L/min m2 internal surface, while vertical silos require liquid rates of 25-35 L/min m tank circumference. Adequate inclination (slope) of piping and process vessels is essential for self-draining of process and cleaning liquids. Special C1P systems are applied to dry-food processing equipment, such as conveyors (belt, screw, pneumatic), dryers (spray, rotary etc), and dry food processing lines, e.g., cereals (Seiberling, 1997). Usually, food equipment must be cleaned daily, after a processing period. However, when different products are processed in the same equipment, cleaning depends also on the frequency of product changes. Effective CIP requires automation of the whole system. Microprocessor controllers (PLC) are used in connection with on-line sensors for temperature, level, flow rate, pressure, and valve position (Grasshoff, 1992), The concentration of cleaning agents and organic effluents can be measured with pH meters, redox potential meters, and optical density meters. The degree of surface contamination can be determined by pressure drop measurements in the pipeline. IV. FOOD PLANT DESIGN
1. General Aspects Some aspects of food plant design and food process economics must be considered in order to have a better picture of the whole food processing plant. The food plant consists of the processing equipment, the process utilities, the plant buildings, and the associated storage and office facilities. There are some important differences in food-related plant design and other industrial applications: 1) The raw materials and final products of the food industry are sensitive biological materials, limiting the processing operations. Thus, raw materials in many food industries (e.g., fruits and vegetables), can be stored only for a limited time. 2) Large quantities of sensitive raw materials must be processed in the shortest possible period, and the equipment must be able to withstand sudden extreme processing conditions. 3) Hygienic factors are important not only in the plant, but also in the process-food product-operating personnel interactions. 4) In many cases, such as fruits and vegetables, food processing is seasonal, and a significant part of the employees are unskilled labor. 5) Since most seasonal raw materials are perishable, relatively short-term cash flow must be provided for their purchase. Plant design refers either to the construction of new processing /manufacturing plants or to the improvement or expansion of existing/operating plants. In the latter cases, a detailed evaluation of the existing operation is neces-
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sary, before any commitments are made. The adopted solutions should be introduced into the plant as smooth as possible, without disturbing the existing operation. Most investments (70-75%) for food processing plants in the USA (Young, 2000) and in Germany (BEV, 2000) are related to plant renovation and expansion, and only 25-30% involve construction of new plants. In all types of food plant design, the main goal is the achievement of the best possible results with respect to quality requirements, high productivity, and low cost. Some typical requirements of food processing operations and equipment are the following: 1) Production Rate. Processing should be as fast as possible, in order to reduce the danger of microbial spoilage and infection, and prevent quality degradation, e.g., vitamin loss due to prolonged heat treatment. 2) Heat Application. In most cases heat must be applied at the lowest possible level to prevent quality losses. However, in cold chains (refrigeration storage and transport systems), temperature should be kept at the highest possible level for saving energy. 3) Sanitation. Hygienic (sanitary) conditions must cover the entire manufacturing spectrum, from raw materials lines to final products, including processes, equipment, buildings, and personnel. 2. New Food Plants Continuous operation of food processing plants is desirable, since it is more costeffective, particularly in large plants, and the processes can be controlled more effectively. However, batch processing is still practiced in several food plants, due to the complexity of some processes, and the diversity and low volume of the processed products. The output of a batch food processing plant can be maximized by judicious plant design, which optimizes the use of the available equipment (Cadbury, 1992). Batch processing requires intermediate storage tanks for further processing of the materials (Sinnot, 1996). Optimization of the process cycles should consider the entire plant operation. Time-utilization (Gantt) charts should include both processing and cleaning of the process equipment. Plant layout is particularly important in food processing because of the uniqueness of processes, and the strict requirements for food hygiene and product quality. One-storied (ground level) buildings are generally preferred, while multilevel installations are advantageous, when gravity flow of large-volume materials is important, as in grain milling plants. In planning a new food plant, several factors should be considered, including the following basic requirements: location, product/process, food hygiene (sanitation), plant safety, and flexibility. 3. Plant Improvement Improvement or renovation of existing plants is a continuous task in food manufacturing plants. Even newly designed food plants may need improvement. The difficulties in plant design are manifested especially in seasonal processing, e.g., of fruits and vegetables. In some cases, the same processing facility may be used
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for processing different food products, e.g., thermal processing of fruit juices and milk. Plant improvements may include the following: 1) Production. Food quality and plant productivity may be improved through new and better processing methods and equipment. 2) Conveyance. Increasing the speed of conveyance / transportation of raw material and products will reduce losses through spoilage and mechanical injury. 3) Storage. Better storage facilities and conditions will reduce quality losses and minimize logistic costs. 4) Energy. Reduction e.g., of heat losses by insulation of equipment. 5) Buildings. Better use of building space; insulation of buildings. 6) Environment. Utilization of specific environmental conditions, e.g., low air temperature in potato storage. Elimination or reduction of environmental burden of water effluents, air pollutants, solid waste, thermal and noise pollution. 7) Management. Greater effectiveness in all fields of the enterprise. Improvement of information flow through the various departments, and feed back adjustments, using computer technology. Labor conditions can be improved, and total number of personnel reduced by judicious automation. Plant improvement is based on a thorough analysis of the existing plant and in finding alternative solutions of the identified problems. The consequences of proposed changes must be considered carefully, before any plant alterations are made. Most improvements require "individual" or "custom-made" solutions, in which the expertise and experience of the plant designer is very important. 4. Plant Expansion Expansion of existing plants is necessary to meet increased demand of the company's products or to expand the activities to related new fields. The difference between new plant construction and plant expansion lies in the fact that, in the latter case, the existing substructure of the enterprise is taken into consideration. In planning plant expansion, the following points should be considered: 1) Avoid causing problems to existing installations (e.g., energy and effluent networks), transport systems, or creating production "bottlenecks". Typical examples of the last problem are packaging machines and storage facilities, which are designed to be used also in the plant expansion. 2) Use existing installations and equipment for the purpose of reducing investment and operating cost of the expanded facility. 3) Purchase, if possible, the same type of equipment, if similar products are to be produced, thus reducing maintenance cost. 4) Purchase new equipment, whose combination with existing similar machines will increase plant flexibility. For example, new small compressors, combined with existing larger units, will meet the additional refrigeration load of expanded cold storage facilities. 5. Mobile Food Plants Mobile food plants may be used in special food processing operations, as in the introduction of a new process (pilot plant), or in seasonal food processing of small food operations (Kostaropoulos, 2001). A mobile plant consists of a number of
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small processing units, usually mounted on a trailer-truck, which can be transported to the site of food processing, and connected to process utilities (steam, water, refrigeration). Mobile factories are particularly attractive for processing relatively small quantities of similar raw materials, which are harvested at different seasons and locations, e.g., apricots (summer) and peaches (fall). A special type of mobile food plants are the fish-processing ship-factories, which move to various fishing areas (Kostaropoulos, 1977). 6. Advanced Food Plants New food processing and manufacturing concepts, food structure engineering, process design and control, and hygienic aspects are the elements of advanced modern food plants (SIK, 2001). Progress in food processing can be accelerated by adopting new technologies from other manufacturing industries. Automatic control of food processes can be achieved by interfacing (combining) modern analytical techniques (optical/color, MW, X-rays) with computers. Future plants should be able to adjust their production by taking into consideration the consumers' sensory and texture evaluation of the food products. Total automation of food processing plants, using robotics and computer technology, can prevent microbial contamination, and improve hygienic operation and product safety. 7. Economic Aspects The principles of Process Economics, outlined in section V of this chapter, are applicable, in general, to the design of food processes and food processing plants. In addition, some unique economic aspects should be considered, when analyzing food processes. Capital Cost Cost estimates in food processing plants is empirical and less accurate than in the chemical process industries. There is a large variety of food plants producing several food products in large or small quantities. General estimation techniques, outlined in section V of this chapter can be used for preliminary calculations. Some useful empirical data from the food industry were presented by Clark (1997b). Basic data, required in a food plant project, include materials, manufacturing operations, packaging operations, and warehousing. The cost distribution depends on the size and capacity of the food processing plant, e.g., plant site and buildings 25%, process equipment 40%, equipment installation 15%, engineering 10%, and other 10%. The following procedures can be used in food plant estimations: 1) Firm quotes from equipment suppliers and contractors, which can be accurate within 5%. 2) Factored estimates, used on processing equipment and correlations. Processing equipment represents about 40-60% of the total food plant cost, which is a very rough approximation.
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3) Square meter costs of plant area, based on experience. For example, for large food plants (over 10000m2) the cost may be about 4 k$/m2, out of which 2.5 k$/m2 is for installed equipment and 1.5 k$/m2 for plant buildings (year 2000 prices). 4) Ratio estimates, based on sales or production volumes. The sales to assets (fixed capital) ratio in the food industry may vary from 2-5, depending on the type of industry and the age of the plant. The plant cost per ton capacity may vary from $ 500 (wet products) to $ 2500 (dry products). The plant production capacity can be expressed in kg/h, ton/day, ton/year, cases/day, bottles/min, etc., both as average and range of values. Operating time is specified in hours/day, hours/year, shifts (8h)/day, or days/week. Material and energy balances are in kg/h and kW respectively. Operating Cost The major operating cost in food processing is the cost of raw and packaging materials, which can amount to 60-70% of the total cost. Other significant costs are labor, energy, and depreciation of equipment. Other components of the cash flow are sales and distribution, marketing, administration, taxes, and insurance. Economic analysis (profitability) can be estimated by the return on investment (ROI), the net present value (NPV) or the Cumulated Cash Flow (CCF). The payback period in the food industry is taken usually as 5 years, which is significantly shorter than in the chemical process industries (6-10 years) Preliminary plant cost estimation is based on the cost of the major processing equipment. In the chemical industry the cost of a plant is estimated as 3.5 to 5 times the cost of the major equipment. However, the cost of the major food processing equipment is relatively higher, because smaller units are used, the materials of construction are expensive (stainless steel, hygienic design), and there is less piping and instrumentation. As a result, the estimated plant cost in food processing is about 1.5 to 2.5 times the cost of the processing equipment (Bartholomai, 1987; Pyle, 1997). Mathematical modeling and simulation are used to evaluate and optimize the operation of food processing plants. Thus, modeling and linear programming were applied to an apple juice concentrate plant in Argentina (Bandoni et al, 1988). The plant processed 164 ton/day of apples, producing 20.6 tons/day apple juice concentrate 72 °Brix, 1.2 ton/day of aroma essence, and 54.5 ton/day of pomace. Raw material represented 60-65% of the total cost of apple juice concentrate. Availability of raw material and apple variety has an important effect on process economics. An economic analysis of a citrus processing plant in Italy was presented by Moresi (1984). The plant processed 20 ton/h of oranges and alternatively 10 tons/h lemons, producing frozen citrus juice concentrates, peel oil, and dried pomace. The profitability of the citrus plant depends strongly on the cost of raw material (oranges and lemons), accounting to about 70% of the total product cost. The high cost of some food raw materials, e.g., seasonal fruits and vegetables, is sometimes subsidized by local governments, in order to provide a reasonable income to the growers, keeping the prices of the processed products at competitive levels in international trade.
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1. Financial Analysis and Process Profitability The economic analysis and profitability of general processing plants (with emphasis to chemical processing) is discussed by Perry and Green (1984, 1997), Douglas (1988), Peters and Timmerhaus (1991), Pyle (1997), and specialized economics books. A simplified money flow for project evaluation is presented in Figure 2.6. This diagram is used to describe the economic model for the financial analysis in this book.
Sales Income 5
Working Capital
C w~f
\ Manufacturing Cost 1 / CM =fM Cop
Gross Profit P6=S-CM Taxes
r=(p6 -dcF)t
Fixed Capital Cf=fiC! Profit
Total Capital CT
Net Profit
Capital Recovery
Capital Source and Sink
Figure 2.6 A simplified money flow diagram for financial analysis model.
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a. Investment Cost The total capital investment CT in a processing plant consists of the fixed capital CF or fixed investment, needed to supply the necessary manufacturing and plant facilities, and the working capital Cw, necessary for the operation of the plant: CT=CF+CW (2-1)
The fixed capital Cf consists of the fixed manufacturing investment (equipment, piping, foundations, site preparation) and the fixed non-manufacturing investment which includes the land, processing buildings, utility and waste disposal / treatment, warehouse, shipping and receiving facilities, administrative and other offices, shops, laboratories and other permanent parts of the plant. Construction overhead costs (engineering and supervision expenses, contractor's fees, and contingencies) are also considered non-manufacturing costs. The working capital Cw in an industrial plant consists of the total amount of money invested in raw materials and supplies carried in stock, finished and semifinished products, accounts receivable and payable, and cash kept on hand. It is usually estimated as a fraction of the fixed capital: Cw=fwCF (2-2)
The ratio of working to fixed capital fw varies from 10-20% in most process industries, but it may be as high as 50% in plants processing products of seasonal demand, or seasonal production of raw materials, e.g., fruits and vegetables. The following value is suggested for food industries: A-=0.25 (2-3)
The capital investment in an industrial processing plant can be estimated by a number of methods of varying degree of accuracy, depending on the objective of the process design (Peters and Timmerhaus, 1991). The following five estimates are listed in order of increasing accuracy: 1) Order-of-magnitude or ratio estimate, based on similar previous data; 2) study or fractional estimate, based on knowledge of major items of equipment; 3) preliminary estimate, based on sufficient data to authorize the budgeting of the project; 4) definitive (project control) estimate, based on nearly complete data before completion of drawings and specifications; and 5) detailed (contractor's) estimate, based on complete engineering drawings, specifications, and site surveys. Estimates (1), (2), and (3) are pre-design cost estimates, which are very important for determining if a proposed project should be considered in more detail. Estimates (4) and (5) are considered firm estimates. The cost of making capital investment estimates depends on the type of estimate and the size of the processing plant (project), varying from about $ 3000 (ratio estimate) to nearly $ 1000000 (detailed estimate). The approximate accuracy of the various estimates is given in Table 2.8.
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Table 2.8 Accuracy of Capital Cost Estimates Estimate of Capital Cost Ratio estimate Study estimate Preliminary estimate Definitive estimate Detailed estimate
Approximate Accuracy, % over 30 less than 30 20 15 5
The cost of the various components in a processing plant varies widely, because of the important differences in the processing of gases, liquids, and solids. Thus, the cost of piping is much higher in gases or liquids processing than in solids processing, where size reduction and mechanical separation equipment is more important. Table 2.9 presents an approximate cost breakdown for the important components of a typical processing plant (Peters and Timmerhaus, 1991). The installed utilities or auxiliary services include steam, industrial water, compressed air, and waste treatment. Refrigeration is usually considered within the analysis of the specific process, e.g., freezing of foods. The contingency factor refers to unexpected costs of the installation/construction project. The fixed capital investment in a processing plant can be estimated from empirical rules or approximations, which yield results similar to those of Table 2.9. For example, the Lang factor^ can be used to estimate the fixed capital CF from the process equipment cost Ce</, using the empirical equation: C,,=fLCel, where (2-5) 3.6 for mixed fluids/solids processing The higher^ factor for gases and liquids processing is due to the higher requirements for piping and valves.
4.7 for fluids processing
Table 2.9 Approximate Percentage Cost of Process Plant Components Component Purchased equipment Installation of equipment Installed piping Instruments / Control Electrical installed Utilities installed Buildings and Construction Engineering and supervision Contractor's fee Contingency Total % of Fixed Capital Cost 25 10 8 8 5 15 10 10 3 6 100
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In food processing plants, ihefL factor is much smaller because of the higher cost of equipment (stainless steel) and less piping. Cost data of typical food processing plants are shown in Table 2.10 (Bartholomai, 1987; Clark, 1997b). These data are presented in Figure 2.7, from which the Lang factor/J, is estimated: fi = \ .6 for food processing plants (2-6)
In modern food processing plants, using more instrumentation and process control, the Lang factor varies in the range 1.5 to 2.5.
Table 2.10 Cost Data of Typical Food Plants (Year 2000 Prices) Food plant Capacity ton/h Raw Product Equipment Cost Total cost M$ M$
Orange juice concentrate 20 Tomato paste 15 Apple processing 5 Milk powder 18 Ice cream 2 2 Milk processing 2 Vegetable oil
1.5 2.5 4.0 1.7 2.0 2.0 1.8
1.35 1.30 2.40 3.40 1.80 1.00 1.70
3.80 2.20 3.50 4.80 3.00 1.40 2.80
i Orange juice Milk powder I Apple processing
I4 1' •o
i concentrate I
• Ice cream.,
Vegetable oil Tomato pas^e
t i
Milk processi ng
Equipment Cost (M$)
Figure 2.7 Fixed capital versus equipment cost for the typical food industries in Table 2.10.
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b. Process Profitability Process profitability can be estimated by the following simple economic calculations based on the money flow diagram in Figure 2.6: The gross profit Pn (annual, before taxes) is the sales income S minus the manufacturing cost CM: Pc,=S-CM (2-7)
The manufacturing cost CM consists of the direct production cost Cop and other expenses, which are analyzed in detail in the literature, e.g., Peters and Timmerhaus (1991). For quick estimation the direct production cost Cop is multiplied by a factor fM to obtain the manufacturing cost CM-
CM =/M Cop
For food industries the following value is suggested:
The taxable income R is the annual gross profit PG minus the depreciation allowed by the tax authorities: R = Pa-dC,.(2-10)
where d is annual depreciation allowed by the tax authorities for computing taxable income. Thus the taxes T are calculated by the following equation, considering an income tax rate /: T = Rl (2-11)
Consequently the annual profit after taxes P, alternatively called Annual Cash Flow ACF, is calculated by the equation: Pa-T The net profit is obtained after subtraction of the capital recovery payment: PN=P-eCF where e is the capital recovery factor. (2-13) (2-12)
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Generally, the two depreciation rates d and e are different, d is decided by the tax authorities while e is negotiated by the leaner bank. Usually the following equations are used: d=l/NT (2-14)
That is, a straight line depreciation is accepted by the tax authorities for the expected project life NT.
Equation (2-15) calculates the annual payment for a loan with iL interest rate and NL loaning period. It must be noted that both NT and NL are generally different from the real life of the project N. However, the following approximation is usually made: N=NT = NL =10 years The most important magnitudes in financial analysis are: • the Cumulated Cash Flow CCF, and • the Net Present Value NP V which are defined by the following equations:
where / is the interest rate, expressing the time value of money. It must be noted that NPV (instead of CCF) takes into account the time value of money: NP V = CCF , when ;=0 If/* is constant over the years then it can be proved that: CCF = -CT+N P NPy = -CT+—, where e= ^ .— e (1 +;) -1 (2-20) (2-21) (2-19)
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Figure 2.8 is a graphical representation of Equation (2-21). It represents net present value NP V versus time for the following values of interest rate i: • • • i = 0:NPV=CCF i = 0.5 i = IRR
where the internal rate of return IRR is defined by the following relation: 0 (2-22)
CCF and NPV curves intersect the x-axis at the points SPB and DPB, respectively, which are defined by the following equations: Simple Payback Period SPB: N = SPB => CCF = 0 Discounted Payback Period DPB: N = DPB^NPV = Q It can be proved that: SPB = -!(2-25) (2-24) (2-23)
The inverse of simple payback period SPB is often called the Return on Investment ROI: ROI = — CT (2-27)
Figure 2.9 is a modification of Figure 2.8 taking into account the construction period and the salvage value of the equipment at the end of the project life.
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Time (years)
Fig u re 2.8 Net present value NP V and cumulated cash flow CCF versus time.
Time (years)
Figure 2.9 Net present value NPV versus time. Construction period and equipment salvage value are taken into account.
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c. Individual Processes The previous financial analysis refers to complete industries or to processes with income. But, usually, in process design the processes analyzed have no income, and they just undertake a subtask of a major system. In these cases, process design is based on the total annualized cost TAC, defined by the Equation:
TAC = eCT+CM (2-28)
where CT is the total investment cost and CM the annual manufacturing cost. Thus, the total annualized cost TAC is a weighted sum between the investment cost Cr and the manufacturing cost CM. The weighting factor is the capital recovery factor e, which is calculated from Equation (2-29). e = CRF(i, N) = -^~— Taking into account Equations (2-4) and (2-9), Equation (2-28) is written: TAC = efLCec!+fMCop The reader is reminded that for food industries (Equations 2-6 and 2-9): fi «/M "1-6 (2-31) In individual processes, incorporating one or two operations in an existing or designed processing plant, only the cost of the major process equipment and its operating cost (utilities) are considered. Thus, the following assumptions can be made: A » A/ * 1 Thus, Equation (2-30) is written:
TAC = eCa,+Cop
The total annualized cost of the process TAC in the form of Equation (2-33) is usually selected as the objective function to be optimized in this book. The following equations calculate the equipment cost Ceq, and the annual operating cost Cop, respectively.
(2 35) j which are analyzed in the following sections. The process cost equation for TAC (2-33) is used throughout this book for the economic evaluation and optimization of the various food processes (Chapters 3-10). The complete economic analysis and profitability of food processing plants requires additional cost data on raw materials (foods and packages), labor, and overhead, as shown in Example VI of this chapter. It should be noted that the cost of raw materials in food processing is about 60-70% of the manufacturing cost, which is much higher than in usual chemical processing.
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2. Cost of Equipment and Utilities The most accurate cost estimation for process equipment is to obtain a price quotation from a reliable manufacturer or supplier (vendor) of equipment. Specification sheets for each process unit should be prepared for the equipment, which should contain basic design data, materials of construction, and special information that will help the supplier to provide the appropriate equipment. Standardized equipment is preferred because of lower cost and faster delivery. It should be noted that very strict and detailed specifications could increase substantially the price of the equipment, while an available "off-the-shelf unit at a lower cost might be satisfactory. Second-hand equipment at a lower cost may, in some cases, be satisfactory for the intended application. Suppliers of processing equipment are found in various directories and in international equipment fairs. When approximate cost data are required for preliminary design, empirical methods and rules are used, which will yield fast results within the accepted accuracy (Chilton, 1970). A popular method is to use the Guthrie charts of equipment cost versus capacity (Guthrie, 1969; Peters and Timmerhaus, 1991; Perry and Green, 1984; Douglas, 1988). Plotted on log-log scales, the Guthrie charts show straight lines. These charts are represented by the generalized cost-capacity Guthrie equation: (2-36) where, C and C0 are the equipment costs (e.g., USD=$) at plant capacities Mand A/o (e.g., kg/h), respectively. The scale index (exponent, «) varies with the type of equipment over the range 0.5 to 1.0, and it is often taken approximately as «=2/3. The "2/3" factor is related to the cost of spherical vessels: C=kV213, where V is the vessel volume and k is a constant (Biegler et al, 1997). Exponent values near «=1 are characteristic of complex mechanical or electrical units, such as motors, compressors, homogenizers, and distillation columns. Low values near «=0.5 characterize large processing units, such as evaporators, heat exchangers, and tanks. Table 2.1 1 and Figure 2.10 show typical equipment costs for general process equipment, which is also used in food processing. The plant capacity/cost relationship (Equation 2-36) is normally applied to equipment and utilities of the main industrial processes. Better cost estimates can be obtained by modifying Equation (2-36), considering the cost of all auxiliaries outside the main process, such as environmental installations, and materials handling and storage (Haseltine, 1986). To take into account the effect of inflation, operating pressure and temperature, Equation (2-36) is modified to Equation (2-37) (2-37)
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Table 2.11 Estimated Costs of Equipment and Scale-up Factors (year 2000) Equipment Heat Exchangers Mixers Rotary Dryers Tube Evaporators Vessels
Note: 1 k$ = 1000 USD
Size (Unit) Area (m2) Power (kW) Area (m2) Area (m2) Capacity (m3)
Size Range Unit Cost min max k$ 2.00 10 1000 5 75 3.00 2 50 8.00 500 3.00 50 200 3.00 1
Scale Index
0.65 0.50 0.60 0.65 0.55
Size (see labels) Figure 2.10 Equipment cost for various unit operations (year 2000).
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where the correction factors for inflation fi, temperature fr, and pressure fP are estimated from the following equations:
V noo ;
and the cost indices M&S and CEP are discussed in the next paragraph.
fT = ex]
fp = ex:
F-l ~75~
The correction factors of empirical equation (2-39) for temperatures 1001800 °C and (2-40) for pressures 1-70 bar come from fitting exponential equations to data presented by Biegler et al. (1997). Figure 2.11 shows the effect of pressure on the cost factor fp. Most food processes operate at temperatures lower than 150°C and temperature correction of the equipment cost is not necessary. The pressure correction factor may be used at pressures up to 70 bar, but not at the very high pressures of supercritical fluid extraction (about 300 bar) or the ultrahigh pressures of highpressure food processing (1-8 kbar).
Figure 2.11 Equipment cost correction factors for pressure.
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The cost of processing equipment or processing plants at a given time can be estimated by multiplying the known cost of the equipment/plant at a past time by the ratio of an appropriate index, corresponding to the same time points. Two common engineering indices are used in the process industries: a) The Marshall and Swift Equipment Index (M&S) (formerly Marshal and Stevens Index), published periodically in the journal "Chemical Engineering", is the weighted average of the cost of equipment of 8 chemical process industries (chemicals, petroleum, paper, rubber, paint, glass, cement, and clay products). The M&S all-industry index is the arithmetic average of indices for 47 different industrial, commercial and housing equipment. The M&S all-industry index is about 2% lower than the M&S equipment, and it is used in this book. The base year of both M&S indices is 1926 (= 100). b) The Chemical Engineering Plant Cost Index (CEP) shows construction costs for processing plants. It consists of the weighted average of four major components: equipment, machinery and supports; erection and installation labor; buildings, materials and labor, and engineering and supervision. The major component, equipment, consists of fabricated equipment; process machinery; pipe, valves, and fittings; process instruments and controls; pumps and compressors; electrical equipment and materials, and structural supports, insulation, and paint. The base year of the CEP cost index is 1957-1959 (=100). Both M&S and CEP cost indices are used in process design, giving similar results (CE, 1997). Table 2.12 and Figure 2.12 show the cost indices M&S (allindustry) and CEP during the period 1960-2000. These data can be extrapolated to the near future using linear regression equations fitted to recent years. The following simplified equations are also presented in Figure 2.12. CEP = 400 + 5 (Year-2000) M&S = 1100 + 20 (Kear-2000) (2-41) (2-42)
The increases of the cost indices are caused by inflation and rises in the prices of certain expensive materials, e.g., stainless steel. The sharp increase of the cost indices during the decade 1970-1980 is mainly due to the rising costs of energy (world-wide petroleum crisis).
Table 2.12 M&S (all-industry) and CEP Cost Indices
Year 1960 1965 1970 1975 1980 1985 1990 1995 2000
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Calendar Year Figure 2.12 Marshal and Swift all-industry equipment (M&S) and chemical engineering plant (CEP) cost indices in the period 1960-2000. Concerning the cost of the utilities, Table 2.13 can be used to make preliminary estimates. Generally, the term utilities includes power, steam, compressed air, cooling and process water. The prices differ from company to company. They will depend on the primary energy sources, the technologies applied, and the plant location. The current cost of utilities supplied by the utility companies electricity, gas and water can be obtained from their local area offices. Table 2.13 Typical Costs of Utilities for Process Plants (year 2000) Cost $/ton 450 30
Utility Fuel Steam Power Cooling Water Refrigeration
$/MWh 40 50 100 5 20
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VI. APPLICATION TO TOMATO-PASTE-PROCESSING PLANT Prepare a preliminary design for a tomato processing plant, processing 20 ton/day of tomatoes of 7 % TS, and producing tomato paste of 32 % TS. The block diagram of the plant will be based on the block diagram of Figure 2.2 and the diagrams of Figures 2.3 to 2.5. Tomato processing is discussed by Luh and Woodroof (1988), Gould (1992), andNFPA (1992). The plant will use the "hot break" method of producing tomato juice, which is concentrated in a triple- effect forced-circulation evaporator. The product will be heat-sterilized and packed aseptically in 150 L drums. The solid tomato wastes will be de-watered mechanically in a screw press and dehydrated in an air dryer, to a dried pomace of 8 % moisture content. Estimate the approximate cost of the processing equipment of the food plant, using cost data from the literature, and the suppliers of food processing equipment.
1. Material Balances The material balances, based on a feed of 100 kg/h of tomatoes are shown on the block diagram of Figure 2.13. The raw tomatoes are assumed to contain 7 % TS (total solids) and 93 % water. The tomato solids consist mainly of soluble carbohydrates, which are usually measured with a refractometer as °Brix (% sucrose), and converted to % TS with special tables (NFPA, 1992). The TS include small amounts of skins and seeds, which are separated mechanically from the tomato juice. Consecutive material balances (overall and % 75) around each processing unit show that out of a feed of 100 kg tomatoes (7 % TS), the following products are obtained: Tomato juice (6 % TS) 95 kg, which is concentrated in a 3-effect evaporator to 17.8 kg of tomato paste (32 % TS). Culls (tomatoes unfit for processing) 2 kg, mixed with tomato waste from juice finishing 2 kg to tomato waste (23.5 % TS) 4 kg. The mixed waste is dewatered partially in a screw press to 2 kg of concentrated waste (40 % TS), which is dehydrated in a rotary air dryer to 0.87 kg of dried pomace (92 % 75). The evaporated water in the juice concentration unit is 77.2 kg, and the remaining small amount of tomato solids is lost in the liquid wastes of washing and dewatering steps. The amount of chlorinated water required for tomato receiving and washing depends on the design of the system, and for 20 ton/h of tomatoes, approximately 2 m3/h of water may be needed.
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Tomatoes lOOkg/h 7%TS Waste 21 kg/h 0.3 %TS
2 kg/h
Waste 2 kg/h 7 %TS Water 1.13 kg/h
0.87 kg/h 92 %TS Dried pomace
17.8 kg/h 32 %TS
Product Figure 2.13 Material balances in tomato-paste-processing plant (see Figure 2.2). Basis 100 parts (weight) of raw tomatoes 7%TS (Total solid content).
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2. Energy Balances
The energy requirements in the tomato-paste plant are mainly for heating the evaporator, heating tomatoes during pulping, and heat-sterilization of tomato paste. Cooling water is needed mainly for condensing the water vapors from the evaporation system, and secondarily for cooling the sterilized tomato paste. A relatively small amount of electrical power will be needed for the operation of the electric motors, moving the pumps, conveyor belts, tomato pulpers/finishers, and the dryer. For preliminary calculations the specific heat (Cp) of tomatoes (7 % TS) is taken as 4.0 kJ/kg K and that of tomato paste (32 % TS) 3.40 kJ/kg K. The (Cp) of water is 4.18 kJ/kg K, and the thermodynamic properties (enthalpies) of steam are taken from steam tables (Haar et al., 1984). A triple-effect evaporator will be used to concentrate 19 ton/h of tomato juice from 7 % TS to 3.56 ton/h of tomato paste of 32 % TS, removing 15.44 ton/h of water. Assuming a heat economy of 2.5 (kg of water evaporated per kg of heating steam) the steam requirement will be 15.44/2.5 = 6.2 ton/h. Heating of washed and sorted tomatoes from 25-85 °C for pulping ("hot break") will require a heating energy rate (power) of 20000x0.97x4.0x(85-25) = 4656000 kJ/h = 4656/3600 = 1297 kW. Using direct saturated steam of 120 °C (2 bar) of enthalpy (120 °C - 85 °C) 2350 kJ/kg, the amount of required steam will be 4656000/2350x1000 = 1.98 ton/h. The steam required for sterilization of 3.56 ton/h of tomato at 95 °C from an initial temperature of 45 °C will be 3560x3.40x(95-45) = 605200 kJ/h = 605200 / 2202 = 275 kg/h = 0.275 ton/h. Total steam needed, 6.2 +1.98 + 0.275 = 8.45 ton/h. The rotary dryer will dehydrate 400 kg/h of pressed tomato waste (40 % TS) to 174 kg/h of dried pomace (92 % TS), removing 400-174 = 226 kg/h water. Assuming that the heat capacity of the rotary dryer is 4 MJ/kg evaporated water, the required energy for drying will be 226x4 = 904 MJ/h. If natural gas of 40 MJ/kg is used as a fuel, 904/40 = 22.6 kg/h will be needed. Cooling water (CW) will be needed mainly for the condensation of the water vapors from the 3rd effect of the evaporator. Total water evaporated 20000x77.2/100 = 15440 kg/h, and water vapors to be condensed in the 3rd effect 15440/3 = 5146 kg/h. A mixing condenser can be used, in which the vapors are condensed by direct contact with the cooling water. Assuming a CW temperature of 20 °C and condensation temperature of 60 °C, the CW required will be 5146x2357/40x4.18 = 72542 kg/h, or 72.5 mVh. The CW required for cooling 20000x0.178 =3560 kg/h of sterilized tomato paste from 95 to 45 °C, assuming final water temperature of 35 °C, will be 3560x3.40x(95-45)/4.18x(35-20) = 9652 kg/h or 9.6 m3/h. Total cooling water required 72.5 + 9.6 = 82.1 m3/h.
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Steam T 1.98 ton, rT
Steam 6.20 ton/
Cooling water 72.5 ton/h
Steam 0.275 t
Cooling water 9.6 ton/h
Aseptic Packaging
Natural gas 22.6 kg/h*
Dried pomace Storage
Product Figure 2.14 Energy balances in tomato-paste-processing plant (see Figure 2.2).
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3. Sizing and Cost of Process Equipment The sizing and cost of the major processing equipment, i.e., evaporators, sterilizers, and dryers, is discussed in the corresponding chapters of this book, and by Saravacos and Kostaropoulos (2002). Empirical data on the mechanical processing equipment are provided by manufacturers and suppliers. Cost data are also provided by Bartholomai (1987), and Clark (1997b). Two parallel mechanical preparation lines for tomatoes are used with identical equipment, since the feed rate is relatively large. A large evaporation system is used, since it is more economical, while the size of the aseptic packing system is normal. A rather small dryer will be used, because the amount of waste dehydrated and the water evaporated are relatively small. A triple-effect forcedcirculation evaporator of 15440 kg/h evaporative capacity will be used. The first effect of the evaporator will be heated with saturated steam at 120°C (2 bar), and the last (3rd) effect will operate at 60°C. The overall heat transfer coefficients are assumed to be t//=2.0, {//=!.5 and U3=\.Q kW/m2K. The estimated total heat transfer area of the evaporator will be 330 m2. The detailed design of evaporators is discussed in Chapter 6. The aseptic processing system will sterilize and pack 3560 kg/h tomato paste. Assuming an evaporative capacity of the dryer 30 kg/mzh, a drying surface of 226/30 = 7.5 m2 will be needed. A cylindrical rotary dryer of 1.5 m diameter and 2.0 m length with a drying surface of 3.14x1.5x2.0 = 9.7 m2 can be used. Table 2.14 shows preliminary capacity and cost data of processing equipment for the tomato-paste plant. Assuming a Lang factor_//, = 2 (Equation 2-4), the cost of the fixed capital investment for the tomato-paste plant will be about:
Table 2.14 Preliminary Data of Processing Equipment for a Tomato-Paste Plant Equipment Washing Sorting Heater Pulping Finishing Juice tanks Evaporator Aseptic processing Screw press Dryer Pumps Capacity 2x(10ton/h) 2x( 10 ton/h) 2x( 10 ton/h) 2x(10ton.h) 2x(10ton/h) 2x(25 m3) 1 x(3 3 0 m2 surface) 1 x(4 ton/h) lx(l ton/h) lx(250 kg/h evaporation) 10 (various capacities) Approximate Cost
150 100 100 100 120 20 500 250 50 80 60
Total cost of main processing equipment Fixed capital investment
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4. Plant Profitability The plant under consideration is assumed to process 28 000 ton/yr in order to produce (20000x0.178=) 5000 ton/yr of tomato paste. This corresponds to an annual operating time of about 1400 h (about 3 months for 16 h daily operation). The cost of raw materials (tomatoes) is about 53 $/ton and that of tomato paste 800 $/ton (year 2000 prices). Thus, the sales income will be 5000 ton/yr x 800 $/ton = 4 M$/yr and the annual cost of the raw materials 28000 x 53 = 1.50 M$/yr. The annual cost of utilities is: (82 ton/h C/W x 0.15 $/ton + 8.5 ton/h steam x 30 $/ton + 23 m3/h natural gas x 0.40 $/m3) x 1400 h/yr = 0.40 M$/yr. Thus, the operating cost is estimated as 1.50+0.40=1.90 M$/yr and the total (manufacturing) cost 1.9x1.20 = 2.3 M$/yr. The raw materials account for 1.5 / 2.3 = 65% of the total product cost. The financial model presented in Section V is applied to the present tomato processing plant and the results are presented in Table 2.15 and in Figure 2.15.
Time (years) Figure 2.15 Net present value of a tomato-paste-processing plant.
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Table 2.15 Tomato Plant Profitability Basic data Equipment cost Operating cost Sales income Factors estimates Manufacturing cost factor Working capital factor Lang factor Capital and manifacturine costs Total capital Fixed capital Working capital Manufacturing cost Economic environment Depreciation coefficient Tax rate Interest rate Capital recovery factor Project life Profit analysis Gross Profit Taxes Profit Net profit Financial appraisal Net present value Simple payback period Discounted payback period Return on investment Internal rate of return
Ceq= Cop= S=
1.50 MS 1.90 M$/yr 4.00 M$/yr
fu~ fw =
1.20 0.10 2.00-
Cr = CF =
(~ w~ CM =
3.30 3.00 0.30 2.28
M$ M$ MS M$/yr
d= *— /'= e= N=
0.10 0.40 0.05 0.13 10 yr
1.72 M$/yr 0.56 M$/yr 1.16M$/yr 0.74 M$/yr
5.69 2.84 3.13 0.35 0.33
M$ yr yr -
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Ceq CF C, Cj CM Coi C0p CT Cw d e Fj fi fu fw / Mi M0 N HJ NL NT P P PC PN R S t T T TAC t
Equipment cost Fixed capital Cost of the / equipment Unit cost of they utility Manufacturing cost Unit cost of the i equipment Operating cost Total capital Working capital Depreciation for tax reduction Capital recovery factor Flow rate of they utility Lang factor Manufacturing cost factor Working capital factor Interest rate Size of the / equipment Reference size of the i equipment Real life of the project Scaling index of the / equipment Loan period Project life for tax depreciation Pressure Profit Gross profit Net profit Taxable income Sales income Tax rate Taxes Temperature Total annualized cost Time
Abbreviations 2D Two-dimensional 3D Three-dimensional ACF Annual Cash Flow AFDOUS Association of Food and Drug Officials of the United States AlChE American Institute of Chemical Engineers ASME American Society of Mechanical Engineers BE Break Even Point BISSC Baking Industry Sanitation Standards Committee BS British Standards CCF Cumulated Cash Flow
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Critical Control Point Center of Chemical Process Safety Coformite Europeenne Chemical Engineering Plant Cost Index Cleaning In Place Capital Recovery Factor Customs Service Dairy and Food Industries Suppliers Association German Standardization Authority Discounted Payback Period European Hygienic Equipment Design Group Environmental Protection Agency European Union Food and Drug Administration Food Safety Objectives Federal Trade Commission Good Manufacturing Practice Hazard Analysis Critical Control Point Hazardous Operations High Pressure Processing High Temperature Short Time International Association of Milk, Food, and Environmental Sanitarians International Dairy Foundation Institute of Food Technologists Internal Rate of Return International Standardization Organization Marshal and Swift Equipment Cost Index Modified Atmospheric Packaging Maximum Profit National Fire Protection Agency Net Present Value Non-Thermal Processes Occupational Safety and Health Administration Pipes and Instruments Process Block Diagram Process Control Diagram Process Flow Diagram Research and Development Return on Investment Simple Payback Period Soluble Solids Total Annualized Cost Total Income Total Solids United States of America United States Dollars United States Department of Agriculture
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