The invention relates to a process for preparing methylenedi(phenyl isocyanate), which comprises (a) the phosgenation of two-ring and/or multiring methylenedi(phenylamine), (b) the fractionation of the crude methylenedi(phenyl isocyanate) obtained to give two-ring and multiring isomers, (c) the purification and/or fractionation of the resulting mixture of two-ring isomers of methylenedi(phenyl isocyanate) and (d) the storage of the mixtures obtained in step (c) or in step (b), wherein part of the stored mixtures is reused by means of recirculation in at least one of steps (b) or (c).

The invention relates to a process for preparing methylenedi(phenyl isocyanate), which comprises (a) the phosgenation of two-ring and/or multiring methylenedi(phenylamine), (b) the fractionation of the crude methylenedi(phenyl isocyanate) obtained to give two-ring and multiring isomers, (c) the purification and/or fractionation of the resulting mixture of two-ring isomers of methylenedi(phenyl isocyanate) and (d) the storage of the mixtures obtained in step (c) or in step (b), wherein part of the stored mixtures is reused by means of recirculation in at least one of steps (b) or (c).
Methylenedi(phenyl isocyanate) (MDI) is an important starting material for the preparation of polyurethanes and related polymers which are used, for example, in foams and coatings.
The acid-catalyzed preparation of methylenedi(phenyl isocyanate) (MDI) from aniline and formaldehyde is known and leads initially to a complex mixture of polyamines which is subsequently reacted with phosgene. Here, a complex mixture of two-ring and multiring MDI is initially obtained; this mixture will hereinafter be referred to as crude methylenedi(phenyl isocyanate) (crude MDI). Crude MDI comprises, in particular, the two-ring isomers 4,4′-MDI, 2,4′-MDI and smaller amounts of 2,2′-MDI (hereinafter referred to altogether as crude two-ring MDI) and also three-ring or multiring MDI, which will hereinafter be referred to as polymeric MDI (PMDI).
In known processes, crude MDI is separated into a PMDI-rich mixture and crude two-ring MDI. 4,4′-MDI and a 2,4′-MDI-rich mixture are then usually separated off from the crude two-ring MDI. Corresponding processes are described, for example, in the first publications DE 1923214, DE 102005004170, DE 102005055189, CN 101003497 and DE 10333929.
Before further processing, the liquid methylenedi(phenyl isocyanate) products prepared in this way have to be temporarily stored.
Methylenedi(phenyl isocyanate), in particular two-ring MDI, forms dimeric subsequent products in the liquid phase after some time, i.e. during storage. Here, the formation of uretdiones by 4-membered ring formation as a result of dimerization of two isocyanate groups and the formation of uretonimines by 4-membered ring formation from a carbodiimide group and an isocyanate group play a particularly important role. The formation of the 4-membered rings is basically an equilibrium reaction which can be shifted to the side of the isocyanates or carbodiimides by increasing the temperature. In the case of aromatic isocyanates, the formation of uretdiones also occurs in the absence of a catalyst. Trimerization to form isocyanurates (1,3,5-triazine-2,4,6-triones) is likewise possible but generally proceeds at an appreciable rate only on addition of a suitable catalyst.
The formation of the dimeric subsequent products which are insoluble in the methylenedi(phenyl isocyanate) leads to disadvantageous turbidity and sedimentation and results in reductions in quality in subsequent further processing, in particular due to blockage of lines, apparatuses and machines. Consequently, it is desirable to provide a process for preparing methylenedi(phenyl isocyanate) which avoids the abovementioned problems.
Processes for the redissociation of sediments in methylenedi(phenyl isocyanate) are known per se. EP 116847 A2 describes the preparation of crude methylenedi(phenyl isocyanate) from storage sediments. The sediment described there comprises dimeric methylenedi(phenyl isocyanate) (uretdione) and polymeric MDI dimers. These sediments are heated at from 180° C. to 250° C. in the presence of crude MDI for from 0.25 to 6 hours and subsequently cooled to a temperature of 60° C. or less in 5 minutes. The sediments which have been redissociated in this way can be used as crude methylenedi(phenyl isocyanate) for the production of polyurethane products. However, such a process carried out subsequent to the preparation of two-ring methylenedi(phenyl isocyanate) is complicated, for example because it requires a separation step and additional apparatuses. A process which reduces the formation of sediments without such separate redissociation processes would therefore be desirable.
It was therefore an object of the invention to discover a process for preparing methylenedi(phenyl isocyanate) which has the abovementioned disadvantages to only a small extent, if at all.
It was an object of the present invention to prepare MDI, in particular mixtures of 2,4′- and 4,4′-MDI and also pure 4,4′-MDI having a low content of uretdiones and uretonimines. The process should be able to be realized with a low outlay in terms of apparatus and employ mild conditions for MDI. The process should be able to be integrated into existing technologies for preparing two-ring MDI with a very small outlay in terms of process engineering. The process should reduce or prevent the formation of sediments and deposits during the storage of MDI and also increase the period of time for which the MDI can be stored without formation of sediments and deposits compared to the prior art.
The abovementioned objects are achieved by the process of the invention. Preferred embodiments may be found in the claims and the following description. Combinations of preferred embodiments of individual process steps do not go outside the scope of the present invention.
The process of the invention for preparing methylenedi(phenyl isocyanate) comprises the following steps:    (a) phosgenation of two-ring and/or multiring methylenedi(phenylamine) to give two-ring and/or multiring methylenedi(phenyl isocyanate),    (b) fractionation of the crude methylenedi(phenyl isocyanate) from step (a) to give at least one mixture M comprising two-ring isomers of methylenedi(phenyl isocyanate) and at least one mixture P comprising oligomeric methylenedi(phenyl isocyanate),    (c) purification and/or fractionation of at least one mixture M to give at least one further mixture F comprising at least one compound selected from among 2,2′-methylenedi(phenyl isocyanate), 2,4′-methylenedi(phenyl isocyanate) and 4,4′-methylenedi(phenyl isocyanate), and    (d) storage of the mixture F or mixtures F obtained in step (c) and also the mixture P obtained in step (b),wherein part of at least one of the stored mixtures F and/or P is reused by means of recirculation in at least one of the steps (b) or (c).
The term "fractionation" refers to the partial or complete separation of a mixture into individual constituents or mixture constituents.
The term "purification" refers to the reduction of the content of secondary components in a mixture and thus an increase in the purity of a mixture in respect of a particular component.
"Storage" is the temporary storage of a material or mixture for the purpose of later use and/or dispensing. Storage is, in particular, the temporary storage of a material or mixture for a period of at least 1 day.
The term "recirculation" refers to the introduction of a particular amount of a material from a storage apparatus into a preceding step of the process for preparing MDI.
The term "distillation" or "distillative" refers to the purification of a mixture by means of a distillative separation process. In distillative separation processes, the separation action is based on the different compositions of the boiling liquid and the gaseous vapor.
For the purposes of the present invention, the content in ppm is basically in parts by weight based on the total weight of a mixture.
A column is an apparatus for the distillative purification of a mixture. For the purposes of the present invention, a column is a rectification column. Columns are known per se to those skilled in the art.
A column comprises a preferably elongated vessel having separation elements. Separation elements are internals which intensify heat transfer and mass transfer. The column additionally comprises a region below the lowermost separation element which can accommodate condensate (the bottom region) and a region above the uppermost separation element, viz. the top region. To vaporize the mixture to be separated, a vaporizer can be arranged below the bottom region of the rectification column. To condense the gas stream leaving the top region, a condenser can be connected downstream of the top of the column.
Depending on the type of separation elements used, a distinction is made between tray columns, columns having random packing and columns having ordered packing. The vaporized mixture of the materials to be separated is fed in through an inlet which is frequently located at the bottom of a column. As the mixture travels toward the top, it becomes enriched in the lower-boiling component and the latter can be taken off at the top, while the higher-boiling component is recirculated. The higher-boiling component accumulates in the bottom region and can be taken off there.
A distinction is usually made between three types of separation elements. In tray columns, sieve trays, bubble cap trays or valve trays are installed, and standing liquid is present on these. The vapor is bubbled into the liquid by means of specific slits or holes, so that a bubbling layer is formed. A new temperature-dependent equilibrium between the liquid phase and the gas phase is established on each of these trays.
Columns having random packing can be filled with various packing elements which bring about good distribution of the liquid and turbulent flow of the gas. As a result of the increase in surface area, heat exchange and mass transfer are optimized the separation power of the column is thus increased. Known examples are the Raschig ring (a hollow cylinder), Pall ring, Hiflow ring, Intalox saddle, Berl saddle and "hedgehog". The packing elements can be ordered, but are also introduced in a random fashion (as a bed) into the column.
Packed columns having ordered packing as separation elements (ordered packing elements) are a further development of the small packing elements arranged in an ordered manner. They have a regularly shaped structure. Ordered packing therefore makes it possible to reduce constrictions for the flow of gas (with a considerable influence on the pressure drop). There are various designs of ordered packing, e.g. mesh packing or metal sheet packing.
The condensation of aniline and formaldehyde to form crude methylenedi(phenylamine) (crude MDA) is adequately known from the prior art. Crude methylenedi(phenylamine) comprises two-ring and/or multiring methylenedi(phenylamine).
The industrial preparation of crude methylenedi(phenylamine) is generally carried out in two stages. In a first stage, an acid-catalyzed condensation of aniline with formaldehyde to produce the corresponding MDA mixture is firstly carried out. Here, a strong mineral acid such as aqueous hydrochloric acid is usually used as acid catalyst. Processes for preparing MDA by acid-catalyzed aniline-formaldehyde condensation are adequately known to those skilled in the art and are described, for example, in WO 99/40059.
The proportions of 4,4′-methylenedi(phenylamine) and the isomers and homologues thereof can be controlled by selection of the ratios of aniline, formaldehyde and mineral acid and also the temperature and residence time conditions. The condensation can be carried out either continuously or batchwise in industry. In a second stage, the reaction solution is preferably, advantageously after neutralization and phase separation, freed of water and aniline by distillation and worked up to give the crude methylenedi(phenylamine).
Step (a)
According to the invention, the phosgenation of two-ring and/or multiring methylenedi(phenylamine) is carried out in step (a) to give two-ring and/or multiring methylenedi(phenyl isocyanate). The phosgenation of MDA is well known to those skilled in the art. The MDA used will also be referred to as crude MDA, and the MDI resulting therefrom will also be referred to as crude MDI.
The reaction can be carried out either batchwise or continuously in the gas phase or in the liquid phase, as described in W. Siefken, Liebig Annalen der Chemie 562, 75 (1949). The continuous preparation of organic isocyanates by reactions of primary organic amines and phosgene has been described many times and is routine on the industrial scale and is described, for example, in Ullmanns Enzyklopadie der technischen Chemie, volume 7, third edition, Carl Hanser Verlag, p. 76 ff. (1993).
Present-day industrial syntheses of isocyanates are carried out virtually exclusively in continuous processes. In general, the continuous embodiment of the process is carried out in a plurality of stages. In the first stage of phosgenation, the amine is reacted with phosgene to form the corresponding carbamoyl chloride and hydrogen chloride and also amine hydrochlorides.
The primary reaction between amines and phosgene is very fast and exothermic. To minimize the formation of by-products and solids, amine and phosgene are mixed quickly, for example optionally dissolved in an organic solvent. The next stage of the phosgenation comprises both the decomposition of the carbamoyl chloride into the desired isocyanate and hydrogen chloride and also the phosgenation of the amine hydrochloride to form the carbamoyl chloride. Liquid-phase phosgenations are described, for example, in the first publications EP 1 616 857, WO 2004/056756, WO 2006/130405 and EP 012 70 544. To avoid the formation of the undesirable intermediate amine hydrochlorides, the phosgenation can also be carried out as a gas-phase phosgenation at high temperatures. Processes are described by way of example in the first publications EP 1 449 826 and WO 2008/006775 (aerosol phosgenation). Phosgenations in the supercritical region have also been described (WO 2008/049783).
In the process of the invention, the phosgenation can, for example, be carried out using a customary, preferably inert solvent. Suitable solvents are, for example, monochlorobenzene, dichlorobenzene or other chlorinated, aromatic hydrocarbons such as toluene or xylene. Temperatures of from 70 to 120° C. and pressures of from 8 to 5 bar are preferably set in the phosgenation. The phosgenation can be carried out in one or more stages. For example, the phosgenation can be carried out as a two-stage reaction in the presence of at least one inert organic solvent, with the first stage of the phosgenation taking place in a static mixer and the second stage of the phosgenation taking place in a residence apparatus.
Corresponding to the MDA used, the corresponding MDI isomers 2,2′-, 2,4′- and/or 4,4′-MDI and also PMDI are obtained by the phosgenation in the process of the invention.
After the phosgenation of the two-ring and/or multiring methylenedi(phenylamine), a work-up of the reaction mixture in which excess phosgene and solvent are separated off preferably takes place. In one possible embodiment, this can be followed by a physical, e.g. thermal, and/or chemical after-treatment to remove interfering by-products. Corresponding processes are likewise adequately known to those skilled in the art and are described, for example, in U.S. Pat. No. 3,912,600, DD 288599, U.S. Pat. No. 5,364,958, EP 0133538, JP 06345707, DD 288598, DD 288593, EP 0524507 and EP 0866057.
Step a) thus preferably gives a mixture of two- and/or multiring MDI comprising from 10 to 90% by weight, preferably from 20 to 75% by weight, particularly preferably from 30 to 60% by weight, of 4,4′-MDI, and also from 1 to 12% by weight, preferably from 2 to 10% by weight, particularly preferably from 4 to 9% by weight of 2,4′- and/or 2,2′-MDI and from 9 to 78% by weight, preferably from 23 to 70% by weight, particularly preferably from 36 to 61% by weight, of PMDI, in each case based on the total weight of the MDI mixture obtained.
Step (b)
According to the invention, the crude methylenedi(phenyl isocyanate) is subsequently fractionated in step (b) to give at least one mixture M comprising two-ring isomers of methylenedi(phenyl isocyanate) and at least one mixture P comprising polymeric methylenedi(phenyl isocyanate).
The mixture M will also be referred to as crude two-ring methylenedi(phenyl isocyanate) (MDI). Crude two-ring MDI is known to those skilled in the art as a mixture comprising 4,4′-methylenedi(phenyl isocyanate) together with at least one of the isomers 2,2′- and 2,4′-methylenedi(phenyl isocyanate). The mixture M preferably comprises from 80 to 100% by weight, in particular from 85 to 100% by weight, of two-ring MDI, with the two-ring MDI preferably comprising from 80 to 100% by weight, in particular from 85 to 95% by weight, of 4,4′-MDI, from 0 to 18% by weight, in particular from 5 to 14% by weight, of 2,4′-MDI and from 0 to 2% by weight, in particular from 0 to 1% by weight, of 2,2′-MDI, in each case based on the total weight of the mixture M.
The mixture P comprising polymeric methylenedi(phenyl isocyanate) (PMDI) preferably comprises from 40 to 80% by weight, in particular from 45 to 75% by weight, of PMDI and from 20 to 60% by weight, in particular from 25 to 55% by weight, of two-ring MDI.
Processes for fractionating crude methylenedi(phenyl isocyanate) are known to those skilled in the art. The fractionation can be carried out by known methods such as distillation, solvent extraction, extraction with supercritical media, e.g. supercritical CO2, or crystallization. Preference is given to distillation and/or crystallization, which are described, for example, in the first publications DE 1938384, DE 2631168, EP 79516 and EP 1475367.
A distillative fractionation of the crude methylenedi(phenyl isocyanate) is preferably carried out in step (b) to give at least one mixture M comprising two-ring isomers of methylenedi(phenyl isocyanate) and at least one mixture P comprising oligomeric methylenedi(phenyl isocyanate). The distillative fractionation can in principle be carried out in various apparatuses. The distillative fractionation is preferably carried out in a convection vaporizer, in particular a falling film evaporator or forced circulation evaporator, or in boilers, in particular those of the kettle type. At a high degree of concentration, the distillative fractionation can also be carried out in thin film evaporators or helical tube evaporators. The fractionation can be carried out in one or more stages. In the case of a multistage embodiment, the abovementioned vaporizers are preferably bottom vaporizers of a distillation column.
In a particularly preferred embodiment, the fractionation is carried out by means of a falling film evaporator in step (b).
Step (c)
According to the invention, the purification and/or fractionation of at least one mixture M is carried out in step (c) to give at least one further mixture F comprising at least one compound selected from among 2,2′-methylenedi(phenyl isocyanate), 2,4′-methylenedi(phenyl isocyanate) and 4,4′-methylenedi(phenyl isocyanate).
The purification and/or fractionation of the mixture or mixtures M comprising two-ring isomers of methylenedi(phenyl isocyanate) is known per se to those skilled in the art. In step (c), the mixture M of the mixtures M is/are preferably fractionated to give at least two mixtures F which differ from the respective mixture M in the proportion of the isomers 4,4′-MDI, 2,4′-MDI and 2,2′-MDI.
In a preferred embodiment, at least one mixture F1 which has a higher content of 4,4′-MDI than the mixture M is obtained. The 4,4′-MDI content of the mixture F1 obtained is preferably at least 95% by weight, particularly preferably at least 97% by weight, in particular at least 98% by weight, based on the total weight of the mixture F1.
In this preferred embodiment, at least one further mixture F2 which has a lower content of 4,4′-MDI than the mixture M is obtained. The 2,4′-MDI content of the mixture F2 obtained is preferably at least 15% by weight, particularly preferably at least 20% by weight, in particular at least 25% by weight, based on the total weight of the mixture F2. At the same time, the content of 4,4′-MDI is preferably at least 15% by weight, particularly preferably at least 25% by weight, in particular at least 35% by weight, based on the total weight of the mixture F2.
The purification and/or fractionation of at least one mixture M to give at least one further mixture F comprising at least one compound selected from among 2,2′-MDI, 2,4′-MDI and 4,4′-MDI is preferably carried out by distillation, in particular by means of a distillation column (hereinafter referred to as column K2); it is optionally possible to use at least one further distillation column.
The mixture M of isomeric two-ring methylenedi(phenyl isocyanates) is preferably fed in (referred to as feed) into the column K2 at the side. The column K2 preferably comprises separation elements, with ordered packing being particularly suitable. It is in principle also possible to use random packing elements or trays. The column K2 is preferably a side column. For the present purposes, a side column is a column which has at least one bottom offtake, at least one side offtake and at least one top offtake.
Depending on the composition of the mixture, the temperature at the top of the column K2 is preferably from 165 to 200° C. The pressure at the bottom is preferably from 11 to 20 mbar at preferred temperatures of from 210 to 225° C. The column K2 preferably operates at a pressure at the bottom of from 0.1 to 50 mbar, more preferably from 1 to 30 mbar, particularly preferably from 2 to 15 mbar, and at a temperature at the bottom of from 150 to 250° C., particularly preferably from 180 to 240° C., in particular from 200 to 225° C. A high separation action combined with low thermal stressing is achieved in this way.
In the distillation of the mixture of isomeric methylenedi(phenyl isocyanates) in the column K2, 4,4′-methylenedi(phenyl isocyanate) having an isomer purity, i.e. a purity based on the three isomers 2,2′-MDI, 2,4′-MDI and 4,4′-MDI, of at least 97% is preferably taken off as a side stream (hereinafter referred to as first side stream or first side offtake stream).
In addition, a mixture of 2,4′-diisocyanatodiphenylmethane and 4,4′-diisocyanatodiphenyl-methane having a weight ratio of from 85:15 to 15:85 is obtained as second side offtake stream from a side offtake above the first side offtake or as overhead stream from the column K2 in the distillation of the mixture of isomeric methylenedi(phenyl isocyanates). The embodiment having a second side offtake above the first side offtake is preferred, since a high purity of the desired two-ring isomers is obtained in this way. The overhead stream from the column K2 additionally comprises the low-boiling components, e.g. monochlorobenzene, introduced with the feed.
The stream obtained at the second side offtake or at the top of the column K2 preferably has a 2,4′-MDI content of from 20 to 95% by weight and a 4,4′-MDI content of from 5 to 80% by weight, in each case based on the total weight of the two-ring isomers of methylenedi(phenyl isocyanate), which adds up to 100% by weight.
The column reflux ratio (ratio of runback stream to stream taken off) at the top of the column K2 is, in particular, set in the range from 10 to 250, but is particularly preferably in the range from 60 to 120, with the distillate stream amounting to from 1 to 5% by weight based on the feed stream. The bottom stream is from 60 to 90% by weight, preferably from 75 to 85% by weight, of the feed stream.
In a first preferred embodiment, the column K2 is a dividing wall column. The structure of such a column K2 is known per se to those skilled in the art and is described, for example, in EP 1475367 A1, the contents of which are fully incorporated by reference. The dividing wall column is preferably operated under conditions indicated above for the column K2. The mixture M of isomeric two-ring methylenedi(phenyl isocyanates) is preferably fed in at the side in the region of the dividing wall in the dividing wall column. The region of the dividing wall is located in the middle region of the column K2. The length of the dividing wall is selected as a function of the process conditions and of the properties of the mass transfer elements used. The dividing wall divides the column into a prefractionation zone and a main fractionation zone. Ordered packings are particularly suitable as separation elements. However, it is in principle also possible to use random packing elements or trays.
As an alternative, the distillative isolation of the two-ring MDI isomers can also be carried out in two stages, with a first distillation stage being carried out in a distillation column without a dividing wall and a second stage being carried out using a dividing wall column or with two dividing wall columns being used. Corresponding processes are described in EP 1475367 A1 in paragraphs [0024] to [0031].
In a second preferred embodiment, the column K2 is a side column without a dividing wall. The preferred parameters of the side column have been described above. Here, 2,2′-MDI and low boilers are preferably separated off by means of the top offtake and 4,4′-MDI and high boilers are preferably separated off by means of the bottom offtake, with the stream taken off at the top and the bottom being able to be reused in step (b) of the process of the invention. As described above, 4,4′-MDI is preferably taken off from the side column in a purity of at least 97% by weight, based on the total weight of the stream, at a first side offtake and the above-described mixture of 4,4′-MDI and 2,4′-MDI is preferably taken off at a second side offtake above the first side offtake.
In a particularly preferred embodiment, the above-described mixture F1 is obtained from a further column K1 located downstream of the column K2. In this particularly preferred embodiment, step (c) is carried out as follows.
A mixture I is taken off from the column K2, preferably as side stream, and fed in gaseous form to the column K1. The mixture I is 4,4′-MDI having a purity of preferably at least 98% by weight, particularly preferably from 98.5 to 99.0% by weight, based on the total weight of the mixture I.
In the column K1, the gas stream comprising the mixture I is preferably brought into contact with at least one liquid compound A which has a boiling point equal to or higher than that of 4,4′-methylenedi(phenyl isocyanate) and preferably has a content of aromatic halogen compounds of not more than 50 ppm.
In principle, possible liquid compounds A are compounds which are either inert toward 4,4′-methylenedi(phenyl isocyanate) or are 4,4′-methylenedi(phenyl isocyanate) itself, with the content of aromatic halogen compounds in each case preferably being not more than 50 ppm, in particular not more than 40 ppm, particularly preferably not more than 30 ppm, in particular not more than 20 ppm, very particularly preferably not more than 10 ppm.
Suitable inert compounds A are, in particular, dibenzyl ether, terphenyl, higher phthalic esters, naphthalene derivatives. It is of course also possible to use mixtures of the abovementioned inert compounds.
However, the compound A is particularly preferably 4,4′-methylenedi(phenyl isocyanate). Particular preference is given to using 4,4′-methylenedi(phenyl isocyanate) having a purity of at least 97% by weight, particularly preferably at least 98% by weight, in particular at least 98.5% by weight, as compound A. However, it is in principle also possible to use a mixture of 4,4′-methylenedi(phenyl isocyanate) of the abovementioned purity with at least one of the abovementioned inert compounds.
The compound A is particularly preferably 4,4′-methylenedi(phenyl isocyanate) which is recirculated as per step (d) according to the invention. In this way, a proportion of 4,4′-methylenedi(phenyl isocyanate) which has already passed through the process of the invention and has to be stored in a suitable way is fed back to the process. Two advantages can at the same time be realized as a result: firstly, 4,4′-MDI which is low in aromatic halogen compounds is made available according to the invention and, secondly, stored 4,4-MDI which was partly degraded to form subsequent products as a result of storage is recycled and goes in high-purity form to storage, as a result of which the quality of the stored 4,4′-MDI can be optimized according to the invention (avoidance of sediments and deposits). Here, the storage recycle ratio (ratio of the amount of 4,4′-MDI recirculated to the amount of 4,4′-MDI freshly added to storage (additional amount obtained)) is preferably from 0.05 to 0.4, in particular from 0.1 to 0.3.
Very particular preference is given to 4,4′-methylenedi(phenyl isocyanate) being recirculated from a facility for the storage of 4,4′-methylenedi(phenyl isocyanate). A facility for storage is in this case any facility which is provided for the temporary accommodation of the material or mixture to be stored, preferably a container, in particular a storage tank.
The introduction of the liquid compound A is preferably effected above the uppermost separation element of the column K1. In a preferred embodiment, the column K1 is a column having ordered packing. The specific surface area of the packing is preferably from 100 to 1000 m2/m3, particularly preferably from 150 to 800 m2/m3, in particular from 200 to 750 m2/m3, very particularly preferably from 250 to 600 m2/m3.
Preference is given in principle to packings which cause a low pressure drop. Suitable packings are, for example, mesh packings, metal sheet packings and structured packings. Mesh packings are particularly preferred. The liquid compound A is in this case preferably introduced above the uppermost packing element of the column K1.
It is in principle possible to use a number of methods of contacting. Preference is given to methods which lead to intensive contact of the gas stream and the liquid compound A. For this purpose, the liquid A has to be distributed in a suitable way. Appropriate methods are known per se to those skilled in the art.
The effectiveness of contacting depends, in particular, on uniform, area-covering introduction of liquid. Liquid distributors ensure a largely homogeneous liquid distribution over the cross section of the column and are known to those skilled in the art. Predistribution of the liquid can be achieved by means of one or more feed tubes or distributor channels having a plurality of outflow openings located on the underside.
An important design parameter is the number of introduction points based on the column cross section (=droplet introduction density). The following types of liquid distributors are possible: distributor trays, channel distributors, tube distributors and nozzle distributors. The following principles of liquid distribution are possible: bank-up height distribution via holes in the bottom of distributors or introduction tubes having drilled holes along the side, overflow distribution, e.g. via lateral slits or overflow spouts and nozzles.
Suitable liquid distributors are, in particular, box channel distributors. It is advantageous for contacting to be carried out in countercurrent to the gas stream I. This gives a particularly low content of aromatic halogen compounds in the resulting mixture.
The absolute pressure at the top of the column K1 is preferably not more than 50 mbar, particularly preferably from 1 to 30 mbar, in particular from 2 to 20 mbar. The pressure difference between top and bottom (pressure drop) of the column K1 is preferably from 0.5 to 30 mbar, preferably from 0.5 to 20 mbar, particularly preferably from 1 to 10 mbar, in particular from 2 to 5 mbar. A low pressure drop brings about lower thermal stress on the product due to relatively low temperatures in the bottom region.
The temperature in the bottom region of the column K1 is from 140 to 270° C., preferably from 150° C. to 240° C., particularly preferably from 170 to 230° C., in particular from 190 to 230° C., very particularly preferably from 200 to 225° C. This minimizes the thermal stress at a given efficiency of purification.
The reflux ratio, here defined as the ratio of scrubbing liquid to vapor S:V [w/w] is S:V=0.01 to 2.0, preferably S:V=0.05 to 0.5, particularly preferably S:V=0.1 to 0.3.
The column K1 can be made of various materials as long as the materials used are inert to the mixtures used at the given temperature. Suitable materials are, in particular, austenitic stainless steels such as 1.4541 or 1.4571. High-alloy materials such as the ferritic/austenitic 1.4462 are also suitable. Preference is given to using the material 1.4541.
A stream O which consists of the purified mixture comprising 4,4′-methylenedi(phenyl isocyanate) and preferably has a content of aromatic halogen compounds of not more than 50 ppm is obtained at the top of the column K1. The stream O is subsequently subjected to cooling by cooling the stream O to a temperature of preferably from 10 to 100° C., in particular from 20 to 80° C., in particular from 20 to 60° C.
Cooling of the stream O is preferably effected in not more than 5 seconds from the temperature at the top of the column K1 to a temperature in the range from 20° C. to 60° C., preferably from 30° C. to 50° C. The rapid cooling further reduces the formation of subsequent products, in particular the formation of dimeric subsequent products.
Step (d)
According to the invention, the mixture F or mixtures F obtained in step (c) and the mixture P obtained in step (b) are stored in step (d), with part of at least one of the stored mixtures F and/or P being reused by means of recirculation in at least one of the steps (b) or (c).
The amount recirculated from storage to the process can in principle vary over a wide range. If only a small amount, based on the total amount of the respective MDI mixture fed to storage, is recirculated, the formation of sediments may not be able to be prevented completely. Recirculation of a high proportion, on the other hand, is often not economical.
The amount of the mixtures F and/or P recirculated from storage, based on the total amount of the mixtures F and/or P fed to storage, is preferably from 1 to 30% by weight, preferably from 5 to 25% by weight, in particular from 10 to 20% by weight.
An advantage of the recirculation is that the compounds which form sediments and/or deposits in MDI, in particular uretonimines and uretdiones, redissociate without establishing an additional process step.
The recirculation of the stored mixtures F or P is accordingly preferably carried out at a point of reintroduction at which the temperature and residence time are such that redissociation of uretdione units into isocyanate units occurs. The recirculation is preferably carried out in such a way that the mixture is reintroduced at a point which is characterized as follows: T>190° C., residence time at this temperature from 5 to 30 minutes.
In addition, the recirculation of the stored mixtures F or P is preferably carried out at a point of reintroduction at which the temperature and residence time are such that redissociation of uretonimine units into isocyanate and carbodiimide units occurs. The recirculation is preferably carried out in such a way that the mixture is reintroduced at a point which is characterized as follows: T>190° C., residence time at this temperature from 5 to 30 minutes.
The recirculation of the stored mixtures F and/or P can be carried out continuously (continual recirculation of a particular proportion of the stored mixture) or discontinuously.
In a first preferred embodiment, the recirculation of the stored mixtures F and/or P is carried out within a continuous process. The amount of the mixtures F and/or P recirculated continuously from storage, based on the total amount of the mixtures F and/or P fed to storage, is preferably from 1 to 30% by weight, preferably from 5 to 25% by weight, in particular from 10 to 20% by weight.
In a second preferred embodiment, the recirculation of the stored mixtures F and/or P is carried out within a batch process, preferably when a content of more than 0.5% by weight of uretdione has been reached, particularly preferably when a content of more than 0.3% by weight of uretdione has been reached, calculated as dimeric methylenedi(phenyl isocyanate) unit based on the total weight of the stored methylenedi(phenyl isocyanate). The amount of the mixtures F and/or P recirculated discontinuously from storage, based on the total amount of the mixtures F and/or P fed to storage, is preferably from 1 to 30% by weight, preferably from 5 to 25% by weight, in particular from 10 to 20% by weight.
The storage temperature controls the kinetics of the formation of uretdiones and uretonimines. The temperature of the stored mixtures F and/or P is preferably from 5 to 60° C., particularly preferably from 10 to 50° C., particularly preferably from 15 to 45° C., in particular from 20 to 45° C.
The duration of storage is with preference at least 1 day, in particular at least 2 days, preferably at least 3 days, particularly preferably at least 5 days. In some cases, the duration of storage is even at least 1 week, in particular at least 2 weeks. The upper limit of storage is determined by the chemical change of the mixture stored, which is not entirely avoidable, and is in particular at most 4 weeks, preferably at most 3 weeks, in particular at most 2 weeks. Those skilled in the art will choose the quantity recirculated from storage in a suitable manner together with the storage temperatures mentioned. The durations of storage mentioned can advantageously be realized in combination with the storage temperatures also mentioned.
The preferred location of reintroduction or the process step in which the recirculated MDI mixture is reused also depends on the composition, i.e. on whether the mixture concerned is the mixture P or a mixture F. Corresponding preferred embodiments are described below.
Of course, the mixtures P and F obtained can be recirculated independently of one another, in particular fed into different facilities or reused in different process steps.
In a first preferred embodiment, at least part of the stored mixture P is reused in step (b) by means of recirculation. Preference is given to recirculating at least part of the stored mixture P to a separation apparatus, preferably a column or a vaporizer, in particular a thin film evaporator or a falling film evaporator, used in step (b).
The recirculated part of the stored mixture P is preferably recirculated to the pump circuit of a falling film evaporator for separation of crude methylenedi(phenyl isocyanate) into the mixtures M and P.
In a further preferred embodiment, at least one mixture F1 comprising at least 95% by weight of 4,4′-methylenedi(phenyl isocyanate), based on the total weight of the mixture F1, is recirculated and reused in step (c). Mixtures F1 have been described in detail above.
The 4,4′-methylenedi(phenyl isocyanate) content of the recirculated mixture F1 is preferably at least 97% by weight, preferably at least 98% by weight, in particular at least 99% by weight, based on the total weight of the recirculated mixture F1.
Particular preference is given to at least one mixture F1 being recirculated to the above-described column K2 for the distillative fractionation of the mixture M and reusing it in step (d). The reintroduction preferably occurs either at the same point as the introduction of the feed or below the point of introduction of the feed.
In a very particularly preferred embodiment, the above-described mixture F1 is recirculated to a column K1 for the distillative purification of 4,4′-methylenedi(phenyl isocyanate), with said distillative purification of 4,4′-methylenedi(phenyl isocyanate) being carried out subsequent to the distillative fractionation of the mixture M by means of the above-described column K2.
The recirculation is preferably effected in liquid form as compound A as described above for step (c) above the uppermost separation element of the column K1.
In a further preferred embodiment, at least one stored mixture F2 comprising 4,4′-methylenedi(phenyl isocyanate) and 2,4′-methylenedi(phenyl isocyanate) is recirculated in a column K2 for the distillative fractionation of a mixture M in step (c). The reintroduction is preferably effected at the same point as the introduction of the feed to the column K2 (inlet stream of two-ring MDI isomers) or above the point at which said feed is introduced. Mixtures F1 have been described in detail above.
A preferred embodiment of the present invention is shown schematically in FIG. 1. FIG. 1 serves to illustrate this preferred embodiment of the present invention and is not to be construed as a limitation. Individual elements of the preferred embodiments described below can advantageously be combined with embodiments described above.
In FIG. 1, the reference numerals have the following meanings:
1—column K2
2—column K1
3a—upper side offtake stream from the column K2
3k—overhead stream from the column K2
3s—bottom stream from the column K2
4—stream of 2-ring MDI isomers (feed to column K2)
5—overhead stream O from the column K1
6a—lower side offtake stream from the column K2
6b—stream of mixture I
6c—vapor of mixture I
7—bottom stream from column K1
8—condenser
9—storage tank for liquid 4,4′-MDI
10—recirculation from storage tank
11—liquid distributor
12—packing elements
13—apparatus for separating off 2-ring MDI and PMDI
14—storage tank for liquid PMDI
15—recirculation of PMDI
16—crude MDI feed
Description of the Preferred Embodiment as per FIG. 1:
The crude MDI feed (16) is firstly fed into an apparatus (13) for separating off the two-ring isomers of MDI and also a mixture comprising PMDI. The apparatus (13) is preferably a falling film evaporator. The liquid PMDI obtained after the separation, optionally after condensation and/or heat exchange, is fed to a storage tank (14). The recirculation (15) according to the invention of the stored PMDI-comprising mixture to the apparatus (13) is preferably effected above the point at which the feed (15) is introduced. A stream (4) comprising a mixture of two-ring isomers of MDI is fed to the column K2 (1). The bottom stream (3s) is obtained at the bottom of the column K2 (1) and the overhead stream (3k) is obtained at the top. A stream (6b) which preferably comprises at least 98% by weight of 4,4′-MDI is taken off from a first stream (6a), and a stream (3a) comprising 4,4′-MDI and 2,4′-MDI is taken off at a point above the point at which the first side stream is taken off. The stream (6b) forms the stream I which is fed in the gaseous state to the column K1 (2) and passes as vapor comprising the mixture I (6c) through the packing elements (12) of the column K1 (2). 4,4′-MDI which has been taken from a storage tank (9) for liquid 4,4′-MDI and is fed via a recirculation line (10) to a liquid distributor (11) at the top of the column K1 travels in countercurrent to the stream (6c). The liquid distributor (11) ensures a high contact area between the ascending gaseous stream (6c) and the liquid stream of 4,4′-MDI travelling in countercurrent. At the bottom of the column K1 (2), the stream (7) is obtained and is recirculated to the column K2 (1). At the top of the column K1, the overhead stream O (5) of purified 4,4′-MDI is obtained. The gaseous stream (5) is fed to a condenser (8) in which the stream (5) is condensed. The high-purity liquid 4,4′-MDI obtained in this way is subsequently fed to a storage tank (9).

Process for preparing methylenedi(phenyl isocyanate)


A hybrid male coupler portion for a front-end loader mates selectively and interchangeably with first, second or third different female coupler portions. The coupler portion includes a frame having first and second arm pin-on locations adapted for connection to associated first and second arms, respectively; at least one tilt member pin-on location adapted for connection to an associated tilt member; and first and second coupler halves including first, second and third hook-engaging mounts, first, second and third rib locking locations aligned with the respective hook-engaging mounts, plunger pin(s) slidably connected to the frame, movable between locked and retracted positions possibly moving toward the center line of the frame when locked or in opposing directions.

Couplers and coupling systems for front-end loaders are well-known and widely used to provide for quick connect/disconnect of attachments, such as buckets, forks or the like, to the arms and tilt control linkage of a front-end loader or like machine. As used herein, the term "front-end loader" is intended to encompass front-end loaders and all other tractors and machines including two laterally spaced-apart arms and one or more tilt control cylinders, links, or the like that control the angular position of a male coupler portion and/or an attachment pivotally secured to the arms. Examples of known couplers and coupling systems of the general type disclosed herein can be found in commonly owned U.S. Pat. Nos. 4,708,579; 5,415,235; 5,529,419; and 5,692,850, the disclosures of which are hereby expressly incorporated by reference herein.
As is widely known in connection with loader coupling systems, a male coupler portion is operatively connected to the arms and control linkage of a front-end loader machine. The female coupler portion is defined by two parallel, spaced-apart ribs that are welded to otherwise fixedly secured to a bucket or other attachment such as forks or the like. Thus, the front-end loader is able to couple with any desired attachment by mating the male coupler portion to the female coupler portion of a desired attachment for use of the attachment.
FIG. 1A illustrates a first type of conventional female rib FR1. As is known in the art and as shown in FIG. 1C, two of the ribs FR1 are welded or otherwise fixedly secured vertically to a bucket or other attachment AT in parallel, spaced-apart relation to define a first type of female coupler portion B. Each rib FR1 comprises a hook portion FH1 and an ear portion FT1 spaced from the hook portion, but lying in the same plane therewith. The ear portion FT1 includes a lock aperture FA1 that extends transversely therethrough. In use, the hook portion FH1 is adapted to receive a mounting pin or other mounting member of a male coupler portion. The hook portion FH1 and mounting member of the male coupler portion typically comprise mating cylindrical surfaces. When the hook portion FH1 is seated on the mounting pin/member of the male coupler portion, the ear portion FT1 of the rib moves into a locking region of the male coupler portion where it is engaged by a lock mechanism to secure the rib FR1 to the male coupler portion in a releasable fashion. Typically, the lock mechanism comprises a plunger pin that is slidably received in the lock aperture FA1 of the ear FT1 so as to prevent withdrawal of the ear from the locking region of the male coupler portion which, in turn, prevents separation of the hook portion FH1 from the mounting pin/member that is seated therein. As noted, in practice, first and second ribs FR1 are used to define a female coupler portion B and, thus, the mating male coupler portion includes respective first and second mounting locations, and first and second lock mechanisms, to secure the ribs to the male coupler portion. The female rib FR1 shown in FIG. 1A is commonly referred to as a JRB-style rib in that two of the ribs FR1 arranged in an appropriate manner define a female coupler portion that is engageable by a male coupler portion available commercially from JRB Company, Inc., Akron, Ohio, U.S.A.
FIG. 1B partially illustrates a second type of conventional female rib FR2. As is known in the art, two vertical ribs FR2 are welded or otherwise fixedly secured to a bucket or other attachment in parallel, spaced-apart relation to define a second type of female coupler portion in the same arrangement as shown for the female coupler portion B in FIG. 1C. The rib FR2 functions similarly to the rib FR1 but is shaped and dimensioned differently, and the ribs FR2 are spaced differently relative to each other laterally to define a female coupler portion as compared to the ribs FR1. Each rib FR2 comprises a hook portion FH2 and an ear portion FT2 spaced from the hook portion but in the same plane therewith. The ear portion FT2 includes a transverse lock aperture FA2 that extends therethrough. In use, the hook portion FH2 is adapted to receive a mounting pin or other mounting member of a male coupler portion. The hook portion FH2 and mounting member of the male coupler portion typically comprise mating cylindrical surfaces. When the hook portion FH2 is seated on the mounting pin/member of the male coupler portion, the ear portion FT2 moves into a locking region of the male coupler portion where it is engaged by a lock mechanism to secure the rib FR2 to the male coupler portion. Here again, the lock mechanism of the male coupler portion typically comprises a plunger pin that is slidably received in the lock aperture FA2 of the tongue FT2 so as to prevent withdrawal of the ear FT2 from the locking region of the male coupler portion which, in turn, prevents separation of the hook portion FH2 from the mounting pin/member that is seated therein. As noted, in practice, first and second ribs FR2 are used to define a female coupler portion and, thus, the mating male coupler portion includes first and second mounting members, and first and second lock mechanisms, to secure the ribs to the male coupler portion. The female rib FR2 shown in FIG. 1B is commonly referred to as a CAT-style rib in that two of the ribs FR2 arranged in an appropriate manner define a female coupler portion that is engageable by a male coupler portion available commercially from Caterpillar, Inc., Peoria, Ill., U.S.A.
FIG. 1D illustrates a third type of conventional female rib FR3. The construction is similar to FR1 and FR2, but is commonly referred to as a Volvo-style rib in that two of the ribs FR3 arranged in an appropriate manner define a female coupler portion that is engageable by a male coupler portion available commercially by the Volvo Company.
The inventor, while working for a different company, developed the technology which eventually became U.S. Pat. No. 7,225,566. This coupler utilizes two cylinders which direct plunger pins into one of two coaligned receivers which held a rib of an implement with a bore therethrough. The pin passes through the receivers and each can hold a set of bores depending upon which of two different types of implants are selected. The implement and its ribs are then secured in one of two positions with the corresponding hub receiving a hook of the rib thereabove. U.S. Pat. No. 7,225,566 is incorporated herein in its entirety by reference.
Other companies such as Attachment Technologies, Inc. owner of U.S. Pat. No. 7,836,616 has also recognized the attractiveness of being able to provide a coupler which receives two attachments of various companies with different rib configurations. The technology shown and described in that reference is also incorporated herein by reference as well. That reference utilizes plunger pins which push separator parallel pins into engagement into one of two sets of bores through selected ribs.
None of the prior art shows three attachments with the ability to selectively connect to one of three different attachments, particularly such as a Cat IT attachment, a JRB 416 attachment and a Volvo attachment with automated locking capability. None of the prior art has a receiver vertically between a set of ribs which also provide a bore for pine on points to a loader. Furthermore, no prior art constructions provide a locking position engaged from a pin moving outwardly (unlocked) to inwardly (locked) or pins moving in outwardly and inwardly directions for the locked configuration.

Motor coupler with multiple pick up locations


A breaker includes a stationary contact, a movable contact, an operation device including a link portion liked to the movable contact and including an output lever rotatably supported, the operation device operating rotation of the output lever in accordance with a first control signal for a command for pulling out the movable contact and a second control signal for a command for inserting the movable contact, and an auxiliary contact to switch between turn-on and turn-off of an input of the first control signal and the second control signal to the operation device in conjunction with operation of the output lever, the auxiliary contact being able to be used in a circuit configuration to monitor a state of the operation device. The output lever rotates so as to operate a first link portion on a side toward a first direction with respect to a rotational center of the output lever.

There are breakers installed in facilities such as a substation or a switching station. Some of the breakers include an operation device that opens/closes a circuit contact by utilizing a spring force of a torsion bar. The circuit contact includes a stationary contact and a movable contact capable of being inserted into the stationary contact and being pulled out from the stationary contact. The operation device includes an output lever linked to the movable contact. The output lever is rotatably supported. The torsion bar is held in a twisted state, and consequently elastic energy is stored in the torsion bar. When the torsion bar is released from the twisted state, the torsion bar releases the elastic energy, thereby generating a spring force. The operation device utilizes the spring force of the torsion bar to rotate the output lever so as to pull out the movable contact from, and insert the movable contact into, the stationary contact. Patent Literature 1 discloses an operation device that performs opening/closing operation by utilizing a spring force of a torsion bar.


In one aspect, a method and apparatus derive channel quality estimates for given subcarriers in an OFDM signal, based on reference signal (RS) or other known-signal measurements made for another set of subcarriers. In at least one embodiment, a wireless communication apparatus implements a method whereby it is configured for receiving reference information on the first set of subcarriers; generating the first channel quality estimates in the frequency domain, based on the received reference information; computing a power delay profile for the first set of subcarriers; and determining the second channel quality estimates either by extrapolating from the first channel quality estimates or as an average of the first channel quality estimates, depending on a delay spread of the power delay profile.

Receiver synchronization and Radio Link Monitoring (RLM) support important functions in the typical wireless communication network. For example, in wireless communication networks operating according to Long Term Evolution (LTE) standards, (primary and secondary) synchronization signals transmitted from eNBs allow mobile terminals or other items of User Equipment (UE) to detect and synchronize with new cells, for signal quality/strength measurements that enable good handover (HO) decisions. Similarly, RLM allows individual terminals to detect radio link failure and other communications problems, and take or otherwise trigger appropriate actions, such as reconnection or link recovery processing.
However, for a number of reasons including energy efficiency on the network side and battery life improvements on the terminal side, the developing wireless communication standards make increasing use of DTX (discontinuous transmission) and/or DRX (discontinuous reception). For example, in LTE the eNBs may DTX to save power, or for other reasons, and, likewise, the UEs may use DRX, both of which complicate channel quality estimations due to limited measurement opportunity. In the LTE standard, the RLM function requires UE to regularly monitor the serving cell quality and based on the estimated quality detect "in sync" and "out of sync" status of the radio link of the serving cell. The reference signals are used to derive the serving cell quality for the purpose of the RLM. The power saving in LTE eNB may lead to reduction in reference signal transmission and would therefore negatively impact the RLM performance.

Method and apparatus for channel quality derivation


A method of treating a hydrocarbon containing formation, comprising (a) providing a composition to at least a portion of the hydrocarbon containing formation, wherein the composition comprises a glycerol sulfonate of a propoxylated primary alcohol having a branched aliphatic group with an average carbon number from 10 to 24 and having an average number of branches per aliphatic group of from 0.7 to 2.5 and having at least 0.5 moles of propylene oxide per mole of primary alcohol; and (b) allowing the composition to interact with hydrocarbons in the hydrocarbon containing formation.

Hydrocarbons may be recovered from hydrocarbon containing formations by penetrating the formation with one or more wells. Hydrocarbons may flow to the surface through the wells. Conditions (e.g., permeability, hydrocarbon concentration, porosity, temperature, pressure) of the hydrocarbon containing formation may affect the economic viability of hydrocarbon production from the hydrocarbon containing formation. A hydrocarbon containing formation may have natural energy (e.g., gas, water) to aid in mobilizing hydrocarbons to the surface of the hydrocarbon containing formation. Natural energy may be in the form of water. Water may exert pressure to mobilize hydrocarbons to one or more production wells. Gas may be present in the hydrocarbon containing formation at sufficient pressures to mobilize hydrocarbons to one or more production wells. The natural energy source may become depleted over time. Supplemental recovery processes may be used to continue recovery of hydrocarbons from the hydrocarbon containing formation. Examples of supplemental processes include waterflooding, polymer flooding, alkali flooding, thermal processes, solution flooding or combinations thereof.
In chemical Enhanced Oil Recovery (EOR) the mobilization of residual oil saturation is achieved through surfactants which generate a sufficiently (ultra) low crude oil/water interfacial tension (IFT) to give a capillary number large enough to overcome capillary forces and allow the oil to flow (I. Chatzis and N. R. Morrows, "Correlation of capillary number relationship for sandstone". SPE Journal, Vol 29, pp 555-562, 1989.) However, reservoirs have different characteristics (crude oil type, temperature and the water composition—salinity, hardness) and it is desirable that the structures of added surfactant(s) be matched to these conditions to achieve a low IFT. In addition, a promising surfactant must fulfill other important criteria including low rock retention, compatibility with polymer, thermal and hydrolytic stability and acceptable cost.
Compositions and methods for enhanced hydrocarbons recovery are described in U.S. Pat. No. 3,943,160 to Farmer et al., entitled "Heat-Stable Calcium-Compatible Waterflood Surfactant;" U.S. Pat. No. 3,946,812 to Gale et al., entitled "Use Of Materials As Waterflood Additives;" U.S. Pat. No. 4,077,471 to Shupe et al., entitled "Surfactant Oil Recovery Process Usable In High Temperature, High Salinity Formations;" U.S. Pat. No. 4,216,079 to Newcombe, entitled "Emulsion Breaking With Surfactant Recovery;" U.S. Pat. No. 5,318,709 to Wuest et al., entitled "Process for the Production of Surfactant Mixtures Based On Ether Sulfonated And Their Use;" U.S. Pat. No. 5,723,423 to Van Slyke, entitled "Solvent Soaps and Methods Employing Same;" U.S. Pat. No. 6,022,834 to Hsu et al., entitled "Alkaline Surfactant Polymer Flooding Composition and Process;" U.S. Pat. No. 6,269,881 to Chou et al., entitled "Oil Recovery Method For Waxy Crude Oil Using Alkylaryl Sulfonate Surfactants Derived From Alpha-Olefins and the Alpha-Olefin Compositions" and by Wellington, et al. in "Low Surfactant Concentration Enhanced Waterflooding," Society of Petroleum Engineers, 1995; all of which are incorporated by reference herein.
U.S. Pat. No. 7,055,602 describes enhanced hydrocarbons recovery compositions containing aliphatic nonionic additives and/or the aliphatic anionic surfactants that have branched structures. These additives and surfactants may be primary alcohols or sulfates thereof having branched aliphatic groups which may have an average carbon number from 10 to 24, less than about 0.5 percent quaternary carbon atoms, an average number of branches per aliphatic group of the aliphatic anionic surfactant may range between about 0.7 and about 2.5, and methyl branches may represent between about 20 percent to about 99 percent of the total number of branches present in the group. Such compositions are shown in Table of that patent to achieve interfacial tensions of from 0.0022 (low range) to 1.9040 (high range) dynes/cm when used alone or in combination with other materials.

Method and composition for enhanced hydrocarbons recovery


A connector for installation between utility transformer secondary leads and service leads. The connector is for location below a pole-mounted transformer and may be opened or closed from the ground with the use of a tool such as a hot stick. The connector includes two switches for releasable electrical connection of the secondary and service leads. Each switch has a rigid immovable member, a movable member and fastener. The movable member may be brought into contact with and fastened in electrical connection with the rigid member for a closed position of the switch. The fastener may be released and the movable member moved out of electrical contact with the rigid member for an open position of the switch. There are two embodiments disclosed. In the disclosed embodiments, the movable member of each switch includes a flexible cable and the connector includes a spacer between the cables to prevent electical connection therebetween when the switches are open. The flexible member of each switch has a rigid portion, such as a Z-bar, having an aperture which registers with an aperture in the flexible member. A bolt fastener is inserted through these apertures and threaded into a threaded hole in the rigid member of the switch for electrical connection of the members.

The primary winding of a transformer is generally disconnected from its power source prior to servicing. For safety's sake or for other reasons, it may be desirable or required that the secondary winding also be disconnected. A possible reason for this is the existence of a consumer power source connected to the transformer through the secondary leads. If power is supplied to the secondary winding from such a source, the power can be stepped up in the transformer and create a hazard for utility workers. In fact, utility workers are known to have been killed by coming into contact with such a stepped up voltage. Such sources may be unknown to utility workers and present a hidden danger. An example of such an unknown power source is backfeed from the generator of a recreational vehicle connected to the wiring of a house included in a transformer's service. There are other known possible sources.
In Australia, the State Electricity Commission of Victoria (SECV) is known to mount single-pole isolator switches underslung on a crossarm supporting a 230/400 volt three-phase, four-wire secondary conductors. This arrangement provides for the disconnection of both the primaries and secondaries for complete transformer isolation. The arrangement is unsatisfactory for North American utilities.
A multiple bushing connector apparatus for a padmount transformer is described in U.S. Pat. No. 4,787,855, issued Nov. 29, 1988. Use of the apparatus has the disadvantage of relying on releasable bushing connections between the transformer and external leads.


Presented herein are methods and systems for generating intermediate code files adjusted to prevent return oriented programming exploitation, comprising receiving compiled intermediate code file(s) comprise a plurality of routines and adjusting them prior to generation of a respective executable file for execution by one or more processor. The adjusting comprising analyzing a symbol table of the intermediate code file(s) to identify a beginning address of each of the routines, analyzing each of the routines to identify indirect branch instructions in the routines, and replacing each detected indirect branch instruction with invocation of a verification code segment configured to verify that the respective indirect branch instruction points to the beginning address of one of the routines. In runtime, the verification code segment causes the processor(s) to initiate one or more predefined actions in case the indirect branch instruction isn't pointing to the beginning address of one of the plurality of routines.

The present invention, in some embodiments thereof, relates to applying protection against stack corruption exploitation, and, more specifically, but not exclusively, to adjusting intermediate code files to apply protection against stack corruption exploitation.
In the constantly advancing and evolving computerized modern environment, cyber threats have become a major concern. Malicious parties may launch cyber-attacks against multiple platforms, applications and/or services in attempt to gain control over them for a plurality of goals and/or objectives ranging from harmless hacking through exploitation for financial gain all the way to malicious interference in critical systems.
These concerns may be dramatically intensified with the rapid deployment of a huge number of devices, typically small low end embedded devices used to support automation in a plurality of fields, areas and markets, for example, autonomous vehicles, smart cities, agriculture, medical care and medical procedures and/or the like. Such low end embedded devices may typically have limited resources which may be insufficient for applying sophisticated mitigation measures to counter such cyber threats.
However, these limited resources embedded devices may be involved in critical applications, services and/or the like and may optionally serve as access points to higher level platforms and systems. Embedded devices may therefore present a major security breach which may be exploited by malicious parties.

Applying security mitigation measures for stack corruption exploitation in intermediate code files


A device for simulating a function of a tissue includes a first structure, a second structure, and a membrane. The first structure defines a first chamber. The first chamber includes a matrix disposed therein and an opened region. The second structure defines a second chamber. The membrane is located at an interface region between the first chamber and the second chamber. The membrane includes a first side facing toward the first chamber and a second side facing toward the second chamber. The membrane separates the first chamber from the second chamber.

In microfluidic devices that are designed for experimentation on cells, there is typically an "active area" at which the desired conditions or environments for cell culturing and experimentation are present. Other areas in the device serve other functions. It is often desirable to constrain the cells to the active area and avoid cells in the other areas. In one exemplary microfluidic device having a membrane that separates two microchannels, it is desirable to have the cells retained in the membrane region of the device, where cells can communicate through the membrane. On the other hand, it is desirable to avoid cells in the various fluid inlet and outlet channels that lead to and from the membrane region.
It is often desirable to limit the presence of cells or other biological elements within microdevices to the active region, for example, where the cell layers are separated by a porous membrane. Additionally, it is often desirable to constrain fluids to specific device areas, even if the device comprises elements that are not bonded. For example, fluidic seals are used when coupling non-bonded materials, such as membrane, to contain fluids and/or cells in the channels and chambers to minimize fluid, reagent or cell escape and growth between membranes and the sealing materials. Such cell escape or growth can cause unclear tissue boundaries, variability in bioassays and growth rates of tissue, or cell escape into the surrounding fluidic channels.
Fluids are typically moved through microfluidic devices for experimentation on cells using inlet and outlet ports accessible at a surface of the microfluidic device. Current microfluidic devices can be problematic for experimentation on topical treatments, the seeding of additional cells type, or for aerosol delivery for certain tissue types.

Open-top microfluidic devices and methods for simulating a function of a tissue

PRESIDENT AND FELLOWS OF HARVARD COLLEGE


A method in which large-volume gas containers, for example, airships having a gas holding capacity of, for example, 400,000 m3, can be filled with a process gas, includes first completely filling the container with an auxiliary gas, the density of which differs from that of the process gas. The process gas is then quiescently introduced into an upper area of the gas container in such a way that no significant mixing with the air occurs and, at the same time, the auxiliary gas is removed by suction from the lower area of the gas container. To purify the contents of the gas container, purified or fresh process gas is quiescently introduced into the upper area of the gas container in such a way that no significant mixing with the contaminated process gas present in the gas container. At the same time, the contaminated process gas is removed by suction from the lower area of the gas container. To empty the gas container, the above-described process is reversed. The process gas is removed by suction from the upper area of the gas container, while air is simultaneously quiescently introduced into the lower area of the gas container in such a way that no significant mixing with the process gas occurs. In order to obtain a rapid exchange of the filling in the gas container, the gas is preferably intermediately stored in several compressed gas storage tanks.

The invention relates to a method for filling large-volume gas containers, especially airships, with a process gas, as well as a method for purifying the process gas contained in such a gas container, and a method for emptying such gas containers.
In recent years, the forgotten field of airship navigation has regained some of its former popularity. Airships filled above all with helium have been proposed for a multitude of possible applications, especially for transporting heavy loads. Naturally, airships of this kind must first be filled with the gas required to lift them, for example, helium. In this patent application, the gas used to fill the gas container will be referred to as process gas. After a certain period of operation, contaminants will appear in the process gas inside the airship, which effect a reduction in uplift. For example, a contamination of the helium filling with a 5% fraction of air corresponds to a 5% reduction in uplift with respect to a filling that contains nearly 100% pure helium. For this reason, the process gas filling in the airship must be periodically purified. Ultimately, the airship will also have to be emptied, for example, for maintenance. For small and medium-sized airships with up to approx. 6,000 m3 gas holding capacity, the filling or refilling is ordinarily implemented from gas cylinder transport vehicles, so-called cylinder trailers. For larger airships with a gas holding capacity of more than 6,000 m3 (for example, 400,000 m3) it has thus far been impossible to supply this quantity of gas within a short enough period of time. Excessively long down times for filling, purifying, and refilling of the airship could hamper the cost effectiveness of this type of transportation system.
It is thus the object of this invention to provide a method of filling, purifying, and emptying gas containers, via which even very large gas containers can be filled, purified, and emptied within a cost-effective period of time.
This object is attained in terms of the filling of the gas container, in that the gas container is first filled with an auxiliary gas, which possesses a higher or lower density than the process gas. The process gas to be used for the actual filling of the container is then introduced in such a way that no significant mixing with the auxiliary gas occurs, wherein, if the density of the process gas is lower than that of the auxiliary gas, the process gas is introduced into the upper area of the gas container while at the same time the auxiliary gas, or a mixture of auxiliary gas and process gas, is removed via suction from the lower area of the gas container. In contrast, if the density of the process gas is higher than that of the auxiliary gas, the process gas is introduced into the lower area of the gas container, and the auxiliary gas, or a mixture of auxiliary gas and process gas, is simultaneously removed via suction from the upper area of the container.
As was mentioned above in the introduction to the description, in this patent application, the gas that is actually used to fill the gas container will be referred to as process gas. Especially for the use in airships, a gas or gas mixture that has a lower density than air, preferably helium, hydrogen, or a mixture of helium-hydrogen is used as process gas.
The auxiliary gas, which serves only to support the filling or emptying process, is to be differentiated from this process gas. Basically, the auxiliary gas that is used possesses a higher or lower density than the process gas, with the difference in densities between the auxiliary gas and the process gas preferably amounting to at least 15%. Especially when filling and emptying airships, a gas or gas mixture having a density that is the same as or higher than air is used as the auxiliary gas. In the simplest case, the auxiliary gas is comprised of air. Expediently, the gas container is completely filled with the auxiliary gas before the process gas is introduced.
Under a quiescent introduction of the process gas it is to be understood that, to the greatest possible extent, no or very slight turbulent gas streams are produced in the gas container, which would cause the process gas being introduced to mix with the gas already present in the gas container. The flow rate, the inflow cross section, and the point of introduction are selected purposely so that a turbulence of the introduced process gas can be excluded. Only the quantity of auxiliary gas that is drawn, for example, from the lower area of the gas container is replaced with the process gas that is introduced, for example, in the upper area of the gas container.
The exchange of gases is preferably implemented as quickly as possible, in order to keep the diffusion of the two media at an insignificant level. Expediently, the exchange of gases takes less than 20 hours.
When the process gas is introduced into the gas container, a mixing zone forms as a result of physical effects (for example, diffusion, convection), in which the process gas and the auxiliary gas become mixed with a concentration drop within the mixing zone. In the case wherein the density of the process gas is lower than that of the auxiliary gas, this mixing zone travels downward as the filling process advances, until the mixing zone ultimately reaches the bottom of the gas container. In the reverse case, the mixing zone travels upward. The process gas/auxiliary gas mixture can be fed to a purification device when it has reached a minimum process gas concentration of 50%.
Because the thermal effects can influence the mixing of the process gas and auxiliary gas, differences in temperature between the process gas and the auxiliary gas should be taken into account. Differences in temperature can be either avoided to exclude additional influences, or intentionally introduced to generate differences in density based upon temperature differences between the process gas and the auxiliary gas.
After the fill process has been completed and the operation of the gas container has begun, a contamination of the helium may develop over time, for example, as a result of the diffusion of air through the walls of the container. In order to purify the process gas in the gas container, purified or fresh process gas that has a higher level of purity than the process gas already contained in the gas container is quiescently introduced into the gas container in such a way that no significant mixing with the contaminated process gas in the container occurs. In this process, if the contamination of the process gas has resulted in an increase in the density of the process gas, then the purified or fresh process gas is introduced into the upper area of the gas container, while at the same time the contaminated process gas is removed via suction from the lower area of the gas container. Inversely, in the case wherein a contamination of the process gas has resulted in a decrease in the density of the process gas, then the purified or fresh process gas is introduced into the lower area of the gas container, while at the same time contaminated process gas is removed via suction from the upper area of the gas container.
Finally, to empty a gas container filled with process gas, the process gas is extracted by suction from the gas container, while auxiliary gas having a lower or higher density than the process gas is quiescently introduced into the gas container in such a way that no significant mixing with the process gas occurs.
In this, if the density of the process gas is lower than that of the auxiliary gas, the process gas is removed by suction from the upper area of the gas container, while the auxiliary gas is simultaneously introduced into the lower area of the gas container. Inversely, if the density of the process gas is higher than that of the auxiliary gas, the process gas is removed by suction from the lower area of the gas container, while the auxiliary gas is simultaneously introduced into the upper area of the gas container.
To enable the quiescent introduction of the process gas into the gas container, it is preferably introduced over the cross section of the gas container or distributed at the upper and lower walls at a low flow rate. To this end, for example, so-called plate aerators or perforated tubes are provided, which extend over a majority of the gas container cross section or along the length of the gas container. The gas inlet device, which is configured expediently round or flat, is preferably positioned inside the container at the highest or lowest point of the gas container. However, gas inlet devices that are not flat are also conceivable. Accordingly, during emptying of the gas container, the auxiliary gas is also preferably distributed over the cross section of the gas container, and is introduced at a low flow rate. Similarly, during removal of the process gas it is ensured that no turbulence of the process gas takes place inside the container.
The invention is provided especially for use in very large gas containers, for example, airships, having a gas volume of more than 6,000 m3, preferably more than 50,000, especially 50,000 to 2,000,000 m3 (for example, 400,000 m3). During the filling of this type of gas container, the process gas is preferably introduced into the gas container over approx. 10 to 100 hours at a volumetric flow rate of at least 500 m3n/h. During the purification of the process gas inside the gas container, the purified process gas is advantageously piped into the gas container and contaminated process gas is removed by suction at a volumetric flow rate of at least 500 m3n/h.
Because with very large gas containers having gas filling capacities of, for example, 400,000 m3 the quantity of gas needed to fill the container cannot be provided directly via gas transport vehicles, for example, cylinder trailers, a further development of the concept of the invention envisions the process gas being intermediately stored in pressurized gas tanks, which can be filled gradually from the gas transport vehicles. In this manner, gas transport vehicles can supply the process gas, which is compressed via high-pressure compressors to, for example, 80 bar and is stored in the pressurized gas tanks, over a longer period of time. As a result, the quantity of gas needed to fill the gas container is available at any time. In this manner, even large-volume gas containers can be filled with large quantities of process gas within the shortest possible time.
When purifying the process gas in the gas container, at least two pressurized gas tanks are preferably used, at least one of which is filled with contaminated process gas from the gas container, while at least one other pressurized gas tank supplies the purified process gas to fill the gas container. In this, the contaminated process gas that is intermediately stored in the pressurized gas tank is expediently purified using a membrane purification device, and is intermediately stored as purified process gas in the pressurized gas tank. The process gas can also be purified, for example, by adsorption or rectification processes.
Overall, by using pressurized gas tanks, the time required to fill, purify, and empty large-volume gas containers, especially airships, is minimized. As a result, the down times needed by the airships can be limited to an economically acceptable duration.
The proposed method is suitable for use with all types of gases. The use in airships, the use of helium or hydrogen or a helium-hydrogen mixture is especially envisioned. The invention can, however, also be used, for example, for balloons filled with hydrogen or for large-capacity tanks, gasometers, etc. filled with helium, hydrogen, or other gases. When used in large-capacity tanks and gasometers, nitrogen is preferably used as the auxiliary gas in place of the otherwise preferred air.
The invention offers a number of advantages. For example, with the process specified in the invention, the gas container, specifically the airship, always remains tightly filled, so that changes in tension in the hull of the gas container are minimized. The principal advantage of the invention, however, consists in that the filling, purification, and emptying of the gas container can be implemented very rapidly. Thus, the cost efficiency of this system of transportation is made possible with large-volume airships, since the necessary down times can be minimized.

Method for filing, cleaning and emptying large volume gas containers, especially airships