Pressure control of the absorption stabilization system?
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Why is the pressure control of the absorption stabilization system (except for the separate control of the stabilizer column pressure) located at the top of the reabsorption column? Will such a setting cause lag in pressure control? Why not implement pressure control in the absorption tower, reabsorption tower, and desorption tower separately? Isn’t it more flexible to have separate adjustments like this? The absorption stabilization system has only one pressure control unit in the reabsorption tower; if there’s a problem in that one location, it won’t affect the entire system?
The pressure in the absorption tower can be controlled through the reabsorption tower, as the lean gas coming out of the absorption tower goes directly into the reabsorption tower. This eliminates the need to install pressure control valves at the top of the absorption tower; such a design is intended to simplify operations and avoid complicating things. The pressure of the stabilization system can also be controlled through the reflux tank at the top of the stabilization tower; all such reflux tanks are equipped with flare lines, but that is not the primary method of control. The pressure of the absorption stabilization system is also related to the operating temperature of each tower, and it needs to be checked based on the actual operating conditions.
I agree with the technical answer from above; it’s completely correct. . . :lol
The flare line cannot be used as a pressure regulator; it can only serve as a means of pressure relief in emergency situations. This is my understanding – please correct me if I’m wrong
The stabilizer tower has two pressure-controlled valves; one is used to regulate the temperature of the stabilizer tower through hot and cold bypasses； One is to connect a pressure relief valve to prevent the system from overpressuring; this pressure level needs to be set at a relatively high value
Due to its low processing capacity, our unit combines absorption and separation in a single tower, with the tower top pressure being controlled independently in each case. Still, I agree with the opinion of the first poster. :victory:
I agree with the view from the second floor, but it didn’t explain the situation regarding the desorption tower. In fact, the pressure in the desorption tower is provided by the reboiling at the bottom of the tower, and the pressure of the desorption tower is also controlled through the reabsorption tower. The absorption tower, desorption tower, and reabsorption tower are controlled as a system to regulate pressure, which simplifies operations. However, I have the same doubt as the original poster: with such a setup, won’t there be delays in actual operation?
Indeed, venting is not a method for regulating pressure; it is only a means of adjustment in abnormal situations. Under special circumstances, pressure must be controlled by venting in order to prevent the safety valve at the top of the stabilizer from activating, which could lead to more serious production accidents. The operation of the stabilizer primarily involves controlling the temperatures at the top and bottom of the tower to prevent significant fluctuations, while also minimizing the impact on the reflux temperature in the middle section of the distillation tower. The heat source for the stabilization system is provided by the temperature in that middle section.
The desorbed gas from our plant’s desorption tower does not go directly into the reabsorption tower; instead, it is connected to the cooler at the outlet of the compressor. There, it enters the gas-liquid separator at the compressor outlet together with the rich gas, and then proceeds to the absorption tower. Of course, in the end it also reaches the reabsorption tower.
The situation described on the 9th floor seems to be the standard configuration for the absorption and stabilization systems in catalytic devices. We know that the function of the desorption tower is to separate the C2 components from the rich absorption oil by heating. The reason why the desorbed gas is not sent directly to the reabsorption tower is that it inevitably contains some C3 and C4 components; sending it to the absorption tower first serves to recover as many of these C3 and C4 components as possible, so as to incorporate them into the liquefied gas.
The pressure of the absorption system is generally controlled in the reabsorption tower, which ensures stable pressure throughout the system as well as consistent and normal flow rates, making operation simple and convenient.
Has anyone who is experienced actually used this system? In practice, how is pressure controlled as a system involving the absorption tower, desorption tower, and reabsorption tower? Is there any delay in operation? Please give me some advice!
The absorption tower, desorption tower, and reabsorption tower are controlled as a system, making pressure control simple, flexible, and safe. The design has obvious advantages. The only identified drawback is that when the desorption tower loses its heat source for an extended period, the oil-gas separator at the compressor outlet can flow back into the desorption tower along with the desorbed gas, preventing a three-tower cycle from taking place.
When the desorption tower loses its heat source for an extended period, the oil-gas separator at the compressor outlet can flow back into the desorption tower along with the desorbed gas, preventing a three-tower circulation process. In such cases, a manual valve can be installed between them; the manual valve can be closed first when the desorption tower loses its heat source for an extended time.
The reabsorption tower and the absorption tower form a cascade process; by using back-pressure control to regulate the pressure of the front-stage system, the requirements of the entire system can be met, resulting in stable pressure control without any delays. If pressure control is implemented separately in the absorption tower, the reabsorption tower, and the desorption tower, it will lead to interference between these pressure controls, resulting in unstable pressures throughout the system and making the process more complicated. Pressure control is merely used to regulate the absorption effect and maintain stable system pressure; achieving this goal is sufficient, and there is no need for extra measures.