Problems with the wet flue gas desulfurization pre-cooling tower
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Our process flow involves coke oven gas passing through a washing tower, a pre-cooler, and an electrostatic tar catcher as well as a fan, after which it enters two series-connected desulfurization towers before proceeding to the next stage. The problem is as follows: every afternoon we use steam to flush the pre-cooling tower. During this process, the gas bypass valve is opened while the gas outlet valve is closed. The inlet valve cannot be closed due to its heavy weight. Finally, when operations are stopped, the steam supply is turned off, the outlet valve is opened, and the bypass valve is closed. As a result, the flow rate of the desulfurization liquid entering the first desulfurization tower becomes very unstable, which makes it difficult to control the liquid level in the regeneration tower. We seek expert analysis on this issue
The temperature of the gas after the fan is approximately 50–60 degrees Celsius. The temperature of the gas after the pre-cooling tower is about 30–35 degrees Celsius. The temperature of the desulfurization liquid inside the desulfurization tower is roughly 35–40 degrees Celsius. When bypass valves are opened to feed gas into the pre-cooling tower, the temperature of the gas entering the desulfurization tower is around 60 degrees Celsius; the temperature inside the pre-cooling tower rises to 100 degrees Celsius, while the temperature of the desulfurization liquid can reach over 40 degrees Celsius. Please help analyze this situation.
Previously, this problem did not occur when shutting off the gas inlet after flushing the pre-cooling tower; now, after flushing the pre-cooling tower, the circulating water is turned on first, and after about 10 minutes the outlet is opened – in such cases, instability does not arise. What’s going on? Please help, I need a solution.