Transformation heat blowing
Thread Content
In sulfuric acid production, many companies use diesel-based heat storage for heating or direct heating. However, during prolonged shutdowns, after the system is purged with hot air to remove the heat stored in the sulfur combustion furnace, is it still necessary to use heat storage for heating purposes in order to carry out the purification process? Otherwise, how can hot blowing be carried out?
On my 300,000-ton sulfuric acid production plant, I implemented a process that utilized the heat storage capacity of the sulfur combustion furnace for thermal blowing, and the results were excellent. When removing the catalyst, it was evident that the SO2 had been properly dried out, and after maintenance, the catalyst remained well-protected during operation.
Our factory uses direct heat blowing; the temperature increase is achieved through intermittent heating, and the advantage is that there is no need for a preheating furnace for preheating. In our plant, during the feeding process, heat is first stored until the catalyst reaches a certain temperature; after that, the air-to-oil ratio is adjusted, and then the flue gas is used to raise the temperature. For long-term parking, it is effective to adjust the air-to-oil ratio after replacing the oil gun and then perform hot blowing for a period of time.
During hot blowing, diesel smoke is used directly; the chimney should emit smoke. Moreover, a large amount of water vapor is introduced into the system during hot blowing, while the water vapor generated by diesel combustion is only taken into account in the case of cold blowing. Also, has an increase in catalyst resistance after parking been observed? Thank you
I’m not quite sure whether you mean the exhaust outlet behind the waste heat boiler or the chimney after the second suction stage. An important step before raising the temperature directly is to adjust the air-to-fuel ratio. Our approach is to visually check the exhaust outlet to see whether the smoke prior to entering the conversion unit is black; if it is black, further adjustments are needed. Once no black color is visible, the inlet valve can be opened and the exhaust outlet closed, after which the temperature can be raised directly. When drying the furnace, it is well known that the crystalline water, bound water, and deionized water need to be removed in three separate stages, at temperatures of 120 degrees, 400 degrees, and 600 degrees respectively. The issue of flue gas is naturally addressed at these higher temperatures, so there is little or no moisture left. After starting the car, I also noticed an increase in resistance in the catalyst layer while parking, but there are many factors at play, so it can’t be said that it’s caused solely by moisture. What do you think?
What I want to discuss is the thermal blowing process when the system is shut down for an extended period of time; it involves removing any residual sulfur dioxide and sulfur trioxide from the system. It’s not about using high-temperature diesel exhaust gases to raise the temperature immediately upon restarting the system. Since fuel oil is a carbohydrate, will the water vapor generated during its combustion combine with the residual sulfur trioxide in the system, resulting in smoke that appears in the exhaust gases? What are some effective control methods that can be used to eliminate this issue?
When our system is shut down for an extended period, we use the minimal heat generated by the sulfur incinerator for thermal purging. However, each time this process is carried out, white smoke is emitted from the system’s exhaust gases; such smoke does not appear at all when the system is in operation. Could this be related to the gas flow rate? I would appreciate guidance from colleagues.