Do you dare to do this?
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This post was last edited by chuanhengmpq on 2016-3-21 at 11:12. On a day in March 200X, a large sulfuric acid processing unit had to be dealt with because the connector of the power cable for the suction pump motor became hot, with its temperature rising to 60 degrees. Since the main fan was driven by a turbine, it was extremely troublesome to restart the unit after shutting it down (it was necessary to first warm up the sulfuric acid pipes, use the fan to start the unit, and then start the turbine, increase its speed, and warm up the network systems). Do not stop once the preparation is complete. It took 25 minutes to complete the crimping of the wire nose. Start the circulation pump. During this process, the outlet temperature of one absorption tower increased from 63 degrees to 82 degrees. Please discuss the risks involved. What is the maximum time before a suction pump shuts down?
Theoretically, it should work; I heard that other units have tried it before.
Processing without shutting down still carries a high risk
For maintenance work without stopping production, it mainly depends on the attitude of the process engineering team. Typically, the maintenance personnel provide an estimated time for fixing the fault, and the person in charge of process production decides whether this time is acceptable, while also preparing contingency plans； During the maintenance process, the operators also keep a close eye on the important parameters, ready to take emergency measures at any time. None of them are easy.
The risks include: 1. A sudden increase in the gas inlet temperature inside the first absorption tower, which may affect the performance of the acid-resistant bricks lining the tower; when the acid circulation is resumed, this could cause the packing to explode. 2. A decrease in the conversion rate in the fourth (and fifth) conversion stages, an increase in the load on the second absorption tower, and possible excess levels of exhaust gases. 3. An increase in acid mist, which may lead to acid accumulation in the pipelines and equipment after the first absorption stage. 4. A temporary exceedance of the temperature of the circulating acid after resumption of operation. The time required can be calculated based on the time it takes for the acid in the packing to be almost completely drained, depending on the type of tower; for safety reasons, one-third of that time should be taken as a guideline (to leave some extra time in case something goes wrong). Sufficient time buffer must always be provided. I’m just trying to stimulate discussion; please feel free to give me your advice!
1. According to the manufacturers of ceramic rings, the filler will not break even if it undergoes two significant temperature changes between 220 and 20 degrees； 2. The exhaust gas system includes a power wave device and a scrubber tower; it is washed with ammonia water, and the value remains below 150. 3. Acid mist may increase, but no measurements have been taken. 4. There is little change in the acid temperature; the system was shut down for 25 minutes
It cannot exceed ten minutes; otherwise, the exhaust gases cannot be controlled, and even absorption devices are of no use in such cases