Temperature control of the conversion catalyst
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I recently came across relevant information stating that, whether during vehicle operation when the engine is heated up or during normal production, the temperature of the catalyst should experience only minor changes; in fact, the temperature change of the catalyst should not exceed 5 degrees Celsius per year! But it’s so hard to control! In Sections 1 and 2 of our plant, air exchangers are used for indirect cooling, while a sulfur combustion furnace is employed to burn sulfur dioxide directly; any change in the combustion temperature leads to changes in the conversion temperature in Section 1, with these variations sometimes reaching 10–20 degrees Celsius. I was wondering if everyone is facing the same situation? If not, then how do you control it?
Controlling minor temperature fluctuations in the contact coal is actually aimed at extending its service life, thereby reducing costs and ensuring normal production.
For acid production from smelting flue gas, the catalyst temperature experiences even greater fluctuations, as the operating conditions of the smelting furnace are often highly variable. The solution is to establish an appropriate control bypass during conversion and implement interlocking to achieve automatic control. It’s very difficult to do manually.
The conversion temperature for sulfur-based acid production can be controlled quite well; in the past it was maintained within a range of plus or minus one degree. First, the air flow is kept constant, while the flow rate of liquid sulfur is adjusted to an appropriate level using a reflux valve. There is a thermal bypass valve for the gas entering the first stage of the furnace, and it is recommended to use an electric valve for this purpose. It is important to specify during procurement that the valve should have analog input and output capabilities, enabling automatic adjustment based on the temperature at the inlet of stage one. The temperature should first be adjusted manually to the desired level, after which automatic control is activated. The use of an electric valve is necessary because there is a certain temperature difference between day and night; with an electric valve, it is possible to maintain an appropriate temperature at the inlet of stage one. Stages two and three can generally be adjusted manually.