What is the best way to calculate Ammonia injection rate in Crude distillation column?
Answers
|
10/09/2009
|
A:
|
Luis Marques, Galpenergia, luis.marques@galpenergia.com
Ammonia is being replaced by neutralizing amines to control overhead CDU ph. The reason is that Ammonia is very difficult to fix the PH and even in very low addictions the ph fluctuates very quickly from acid side to basic side impeaching the stabilization in the 5 to 6 range PH. On line PH control device linked to amine neutralizing dosing pump is the modern way to control Ph. Contact Baker Hughes or Nalco: they have the know-how to give you the best advice on this matter.
|
|
02/08/2009
|
A:
|
sam lordo, Becht Engineering, salordo@comcast.net
if you are wanting to know the required amount of NH3 required then the previous answer is a good approach, if you are asking how to calculate what you are injecting, then you either can do it via inventory change or installing the appropriate rate gauge
|
|
30/07/2009
|
A:
|
keith bowers, B and B Consulting, kebowers47@gmail.com
The prior answer is very comprehensive and, IMHO, quite sound advice. I would suggest you install on-line corrosion probes in the appropriate location to enable more timely adjustment of amine injection rate.
|
|
29/07/2009
|
A:
|
Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita-water.com
During the overhead condensation process the first drops are very acidic and aggressive. This requires the injection of a suitable neutralizing amine. To avoid corrosion the pH should be shifted as soon as possible to a pH between 4.5 and 5.5. As a rule of thumb the pH should be above 4.5 within 0.5-1% of the condensation. A powerful neutralizing amine shifts the pH profile quickly to a higher level.
The injection of ammonia is a very bad example of a neutralization process and an old-fashioned technology. Ammonia is a very cheap amine and easy to dilute, but the adjustment of the correct amine concentration often alters. The addition of ammonia as NH4OH may give a high end-pH, but the NH3 is an extremely volatile gas. It doesn´t give a good corrosion protection, when the first concentrated acidic droplets have to be neutralized. The formed NH4Cl salts are still very corrosive. These salts require good water wash facilities to remove the salts. The risk to deposit NH4Cl salts is higher than the formation of liquid neutralised salts from modern neutralizing amines.
Ideally 1 mole chloride should be neutralized with 1 mole neutralizing amine to get complete neutralization. Present ammonia, hydrogen sulfide or other components may influence the pH. In practice the addition of amine should be controlled by checking the pH of the sour water. In most cases the calculation of required amine differs with the reality. The pressure and the temperature may cause such differences.
|