Seeking help due to shutdown of water washing tower
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I am equipped with a water wash tower, which uses purified water to come into counter-current contact with liquid-phase C4 in order to wash away propylene and water-soluble impurities from the C4. The wastewater from the bottom of the tower then enters a low-pressure flash tank before being discharged outside the facility, while the C4 at the top of the tower goes into the feed buffer tank of the subsequent system. Before shutting down the operation, I first cut off the C4 feed to raise the level at the top of the tower, and used water to push the C4 out as much as possible. When the level at the top of the tower reached about 80%, I then stopped supplying purified water and closed the outlet for C4 from the top of the tower. However, a small amount of C4 will still remain in the tower. My question is: how can I empty this tower of water, which contains a small amount of C4, from the equipment? The bottom of the tower is equipped with a heat rejection flare line, but the management said that large amounts of water cannot be discharged into the heat flare system. Some have suggested directly reducing the tower pressure, allowing C4 to vaporize first, and then sending the wastewater to the flash tank before removing it from the system; however, this approach raises concerns about equipment damage due to low temperatures. I would appreciate the guidance from all the experts
Isn’t there a flare line at the top of your water scrubber tower? Or the containers in the subsequent process should also have flare lines; you can connect them to the wash tower from behind to relieve the pressure
Fill the water wash tower directly until water enters the C4 tank, then send the water in the water wash tower to the flash tank for treatment before discharging it (be sure to maintain pressure in the C4 tank to prevent the liquid level from dropping and causing the tower to become vacuum, which could result in it being crushed). A small amount of water at the bottom of tank C4 can be removed
There is no need to maintain 80% level; instead, set it to 100%. This allows personnel outside to make an on-site judgment through the exhaust valve at the top of the tower, and the end of material feeding is indicated when water starts to flow out on site. The water inside the tower is directly processed for flashing; it should be noted that the rise of the interface must occur slowly. -QQ: 2790028922
There is a flare valve at the bottom of the water wash tower, but during shutdowns, there is a large amount of water in the tower, which prevents flaring. Also, if pressure is released directly, the temperature will be too low, and there’s a risk of damaging the equipment
The plan we finally settled on was also this: use water to push carbon tetra into the tank until the tank is filled with water. The water inside the tower is then drained to the flash tank. But I overlooked the fact that pressure needs to be applied when draining water from the wash tower; thank you for the reminder
Water is injected to a certain level, and nitrogen is used to blow out the C4 present in the water as well as in the upper part of the tower from the bottom.