How to empty the entire liquefied gas desulfurization tower when it is shut down?

This post was last edited by ylb913 on 2016-3-14 at 22:10. First, the liquefied gas feed is cut off; the amine solution is circulated for regeneration over two hours. Then, the amine solution is cooled through circulation, followed by amine removal. After that, water is used to displace the liquefied gas, and water is then drained. Finally, the pressure in the liquefied gas system is reduced, and the system is purged with steam.

It’s amine liquid circulation desulfurization for 2 hours, right? . Isn’t the temperature of liquefied gas also around 40ºC? Why is it necessary to cool it down?

This post was last edited by ylb913 on 2016-3-14 at 22:37. The amine solution cooling in the reboiler and heat exchanger requires a absorption tower to facilitate circulation. In the case of dry gas desulfurization, we carry out recycling for two hours, then cool down while only using devices such as the dry gas tower and sulfur off-gas absorption tower; at the same time, we stop the circulation of the amine solution used for liquefied gas desulfurization, remove the amine from the liquefied gas earlier, and then use water to purge the liquefied gas.

For example, during normal operation I have a circulating hydrogen desulfurization tower, an exhaust gas desulfurization tower, a liquefied gas desulfurization tower, and an amine solution regeneration tower. When it’s time to shut down the system, I first cut off the feed of circulating hydrogen, exhaust gas, and liquefied gas; however, the feed of lean amine solution continues as usual. The steam supply to the reboiler in the amine solution regeneration tower is also cut off, so that tower can no longer perform regeneration functions – it only serves for circulation. The cooler rich amine solution from the other towers passes through a heat exchanger to absorb the residual heat from the rich amine solution in the regeneration tower, after which it enters that tower and is then pumped back to the large tank containing lean amine solution. From there, the lean amine solution is pumped to the first three towers. After two hours of circulation, all the pumps used for transporting the lean amine solution are stopped. The valves for nitrogen purging are opened in the circulating hydrogen desulfurization tower, the exhaust gas desulfurization tower, and the amine solution regeneration tower; meanwhile, the bypass lines of the safety valves are opened to vent all the gas inside these towers into the flare system. Finally, all the amine solution remaining in these towers is drained into the underground tank used for amine solution preparation and recovery. In the case of the liquefied gas desulfurization tower, the amine solution is first drained, water is injected to displace the liquefied gas, water is then removed again, and finally the bypass lines of the safety valves are opened to reduce pressure. Steam is then used to remove any remaining liquefied gas, with the residual water being drained afterward. Is that the process?

More or less. 1. The 2 hours of \"amine solution circulation regeneration\" after stopping the feed are intended, first, to convert all the amine-rich solution in the system into amine-poor solution, and second, to purify (desulfurize) the dry gas, liquefied gas, exhaust gas, and recycled hydrogen inside the tower. During this period, the regeneration steam is supplied continuously, but its usage gradually decreases. 2. Stop the regenerative steam only during cyclic cooling. 3. When recycling the amine solution, it is necessary to consider using nitrogen to pressurize the regeneration tower; pressure must also be maintained during the cooling process. 4. During amine removal, pressure-driven nitrogen is used to ensure that the amine solution flows through the normal process and directly enters the circulation tank. For example, the lean liquid exits from the bottom of the tower and enters various heat exchangers, with flow from high to low; this allows for complete removal of the amine through the normal process. The rich liquid flows in the reverse direction, and the nitrogen coming from the tower also flows from high to low, after which it is sent directly into the amine solution circulation tank via the amine removal lines at the bottom of each unit. What enters the underground tank is mainly the amine liquid remaining in the U-shaped tubes at the entrances and exits of the equipment, or some residual liquid at the bottom of the equipment. 5. Since it takes a long time to displace the liquefied gas with water and to drain the water, the amine solution can be cooled through circulation without undergoing desulfurization or circulation processes involving the liquefied gas, allowing for earlier removal of the amine and drainage of the water.

I basically understand what the guy ahead of me said. For the last point, what serves as the boundary when removing amine and adding water? How many sets of level gauges and boundary detectors have you installed in your liquefied gas desulfurization tower?

When the amine solution needs to be cooled through circulation, the circulation for liquefied gas desulfurization is stopped. There is only one level gauge at the bottom of our liquefied gas desulfurization tower; in the later stages of amine removal, it is by opening a little drain to determine whether liquefied gas is being released.

How many interfaces will be formed inside the tower? How do you usually control this type of tower?

We are a sieve plate tower; there is only one interface at the bottom of the tower, and there is also a glass plate in the settling section at the top, but it has basically never been used.

With a packed tower, wouldn’t there be more interfaces?