Analyze of 4-20mA circuit
The LM317 provides short circuit protection to the circuit, you can assume the voltage at the top end of the pressure sensor is more than 20V unless the pressure sensor tries to deliver more than about 22mA. 

The 100 ohm resistor reduces the dissipation in the pressure sensor (may improve the accuracy a bit) and reduces the compliance range by a couple of volts (not necessarily a good thing, but as we'll see, it is not a problem). Typical bridge pressure sensors are fairly temperature sensitive and reducing the dissipation improves accuracy and stability (they are typically temperature-compensated, of course, but that compensation is generally static and does not correct as well for dynamic changes). 

The 220 ohm resistor is the important one for accuracy. The voltage going into the ADC is 0.88 to 4.4V nominally (ignoring any loading from the ADC). 



The pressure sensor is a loop-powered instrument, meaning that provided it has enough voltage across it to work it will adjust the voltage drop across itself to  supply the required current. You say that voltage is a minimum of 9V.  If you add up the drops I mentioned above 20V- 2V - 4.4V it still has 13.6V. Even if the 24V supply is a bit low there is plenty of voltage for the sensor. 

Note that there should be some protection on the ADC (not shown) because a direct short of the input to +24 could allow almost 200mA to flow (assuming a 5V supply on the ADC), which is more than enough to cause a lot of damage. If there is a clamp on the ADC input, the 100 ohm resistor will limit the current, though it will probably burn up unless it is large (3.6W dissipation).