Severe liquid carryover in the catalytic dry gas system
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Our plant’s dry gas system is suffering from severe liquid contamination. It’s winter right now, and condensation occurs at the low points of the high-pressure gas lines, which leads to pressure buildup in the dry gas. How can this be adjusted in terms of operation? There is also a serious problem of oil contamination in the absorption tower; after the dry gas enters the dry gas desulfurization tower, it is sent out after desulfurization, but there is still a lot of liquid present. In the subsequent liquid separation tank, both water and oil are present, which again causes condensation and pressure buildup. Attempts to increase the pressure of the dry gas before sending it out don’t yield very good results. Please give me some advice.:)
Severe liquid carryover in the dry gas system is mainly caused by severe oil carryover in the absorption tower； 1. The liquid level in the reabsorption tower should be controlled at 40–60%; its level is prone to malfunctioning in winter. 2. The gas phase in the absorption tower is too large, causing the absorbent to be carried away or there are issues with the operation of the absorption tower. 3. Slightly heat the high-pressure gas control valve with steam, as sulfur in residual liquids and dry gas tends to crystallize in winter.
Winter production generally involves what you mentioned: first, maintaining stable operations to prevent significant fluctuations； Second, enhance insulation by using steam for heating in key areas ； Third, strengthen inspections to promptly remove residual liquid.
Oil carried in dry gas, that is, the situation where dry gas is not truly dry, occurs due to poor absorption effects. This might be caused by a low pressure at the top of the reabsorption tower and a high temperature there; it could also be due to a small tower diameter, a low porosity, and a high gas phase linear velocity, all of which lead to the presence of oil in the gas. Liquid carried in the dry gas is caused by a high gas phase line speed in the dry gas desulfurization tower, which results in more amine liquid being carried along. In the catalytic unit where I work, there has been no occurrence of oil or liquid being carried in the dry gas.
This phenomenon is operationally referred to as \"dry gas not being dry\"; adjustments can be made from an operational perspective: 1. Increase the absorption dose supplied to the absorption tower, or reduce the temperatures in stages 1 and 2 of the absorption tower, lower the temperature of the crude gasoline obtained through distillation, thereby improving the absorption efficiency； 2. Increase the amount of lean absorption oil in the reabsorption tower. 3. Lower the liquid level at the bottom of the reabsorption tower ； 4. Strengthen the dehydration of the liquid separation tank, but pay attention to safety
Generally, this is caused by the low outdoor temperatures in winter, which lead to the condensation of water vapor in the dry gas. The solution is to control the issue of liquid entrainment in the dry gas separation process, and to provide additional heating in areas where condensation is likely to occur.
The absorption tower has severe oil contamination, and stabilization is required to address this issue. Our catalytic dry gas occasionally contains oil when there are significant fluctuations in operation; after entering the dry gas desulfurization tower, it undergoes desulfurization before being sent out. Liquid contamination is also a problem in our facility. The common causes recently include: 1. Excessive fluctuations in feed volume, 2. Large fluctuations in tower pressure, 3. Deterioration in the quality of the amine solution, 4. Prolonged operation of the tower under overload conditions. The corrective measures are: 1. Stabilize the feed volume, 2. Stabilize the tower pressure, 3. Improve the quality of the amine solution, 4. Reduce the load on the tower as much as possible. We have a large volume of work to handle, and reducing that volume yields significant results. If there are any better solutions, please share them with us
What are some ways to increase volume?
I wonder from where the original poster obtained the liquid. In the case of an absorption stabilization system, the pressure can be increased and the temperature of the absorbent can be reduced to ensure effective absorption; thereafter, the liquid phase load can be appropriately decreased. Of course, it would be even better if it’s possible to reduce the gas phase load as well. Low-level control for the reabsorption tower liquid level. If liquid is present in the desulfurization zone, it can be improved according to the suggestions of the previous speakers.