Ask for advice: NHD regeneration tower regeneration principle, problems in the regeneration process

Um, I don’t understand NHD. . But I can provide some other ideas. Question 2: It can be considered that pressure has a large determinant of temperature, but these quantities all influence each other. Generally speaking, P is high and T is high. Furthermore, composition also affects temperature.

The poster is talking about NHD desulfurization regeneration?

The solvent is polyethylene glycol dimethyl ether, which is a physical adsorption and desorption process. The impurities are absorbed by the solvent at low temperature, heated and desorbed in the desorption tower, and the solvent is recovered and recycled to the adsorption tower. UOP's process is called Selexol. If there is no English question on the first floor, check online WWW.UOP.COM , there is an introduction to Selexol’s process flow.

The process parameters can only be consulted by experts with engineering experience.

Question one: The regeneration of the NHD regeneration tower is stripping regeneration. I wonder if any expert can teach me how to achieve gas-liquid phase balance in the tower? How does the water in the tower kettle remain when the temperature of the tower kettle is 147 degrees? If the temperature of the tower kettle is high, the pressure should also be increased accordingly, which will increase the boiling point of water, so that the water will not evaporate too quickly, but a small amount of water will still evaporate. This will only increase the pressure of the tower, which is not a good operation. Question 2: Is the temperature of the regeneration tower still and tower top only related to the pressure of the tower still and tower top? I don’t know what the pressure in the general tower kettle and tower top is? Is it normal pressure? Some are normal pressure, and some are not. It depends on the design control method. You can check what your design pressure is? Question three: The temperature at the top of the regeneration tower is generally around 103-110 degrees. Why should it be controlled within this range? Isn't it okay to keep the tower top temperature between 93-100 degrees while ensuring the water content in the tower kettle? What are the consequences? This situation is not impossible. It mainly depends on what substance you want to separate. Is it actually a distillation tower? There is nothing magical about it. It mainly depends on the position of your sensitive plate, the reflux volume, the temperature of the reflux liquid, as well as the gas outlet at the top of the tower and the liquid drainage at the bottom of the tower. You can figure it out by yourself! Since I have never operated NHD, according to the process I have seen, these reasons should be the reasoning. I only make suggestions. I welcome criticisms and corrections to make progress together! I've asked too many questions, I'm just a novice, I hope the experts will give me some advice. Thanks!

It seems that too few people know about NHD decarbonization.

The control of each unit may be different due to different process designs. However, the bottom of your tower needs to be controlled at 147, so the top pressure of your regeneration tower must be controlled relatively high? Moreover, we use variable gas to heat the bottom temperature of the tower. Generally, the bottom temperature of the tower is between 130-135. The top pressure is generally between 20-40KPa due to the sulfur recovery resistance (the top pressure control valve is basically fully open and cannot be controlled manually). The top of the tower is generally controlled at 100-103 degrees by return water. In this way, the regeneration degree can be guaranteed, and the water content can basically be maintained between 3-5%. As for your questions: 1. The maintenance of water mainly depends on your control of the return water volume. If you control the water volume to suppress the temperature at the tower head, the water content at the bottom of the tower will naturally be maintained. 2. The temperature at the bottom of the tower is related to many factors such as the circulation volume, heat load, operation of the thermosiphon of the bottom boiler, liquid level at the bottom of the tower, and water content. Pressure is only one of the factors. The higher the pressure, the higher the boiling point and the less conducive to boiling regeneration. Therefore, production should try to control the lower pressure. Normal pressure is only an ideal state. The pressure is also affected by the resistance of the subsequent cooling system, the resistance of the sulfur recovery device, and the resistance of the vent pipe. It is not just that you want normal pressure. 3. The control temperature of your tower head is between 103-111. I think it is directly related to the temperature and pressure of the tower bottom in your process design. It is probably related to the sulfur recovery process selected later. If you choose a lower tower top temperature under a higher pressure, the amount of reflux water will increase, and the NHD water content will increase, which will ultimately lead to unqualified regeneration and unqualified purification.

Reply 1# 47179117 Of course, I would like to add something to the first question, that is, you cannot increase the heat load at the bottom of the tower without limit, otherwise the design flow rate of the reflux water pump will be exceeded, and the temperature and water content at the top of the tower will be uncontrollable... Moreover, the pressure difference of your regeneration tower will probably exceed the standard. Be careful to turn the tower over. These indicators should still be based on the design process indicators as much as possible. Of course, they can be fine-tuned within a certain range. As for the effect after adjustment, whether it is effective can be judged by analyzing the regeneration degree and water content at the bottom of the tower.