Why is it required that the inlet and outlet of the sulfur recovery fan be fully closed while it is in operation, with the vent opened?

This is to ensure that the fan starts under no-load conditions, which is beneficial for the motor.

What type of fan are you talking about, and what is its power rating? For compressors, the inlet and outlet valves are usually open, while for centrifugal fans the inlet and outlet valves are closed; the valve for air prevention is open. There have been many discussions on this before; please check it out and get actively involved

Are you sure you want to close the import? . . Generally, it involves opening the inlet and outlet valves, and releasing pressure to fully activate the motor

Press the motor heating button to heat the motor, and press the lubricating oil heating button to heat the lubricating oil. 2. Check the level, temperature, and pressure of the lubricating oil, as well as whether the pressure difference before and after the lubricating oil filter is normal. 3. Open the valve for the circulating water used in the lubricating oil system. 4. Start the auxiliary oil pump to make the lubricating oil flow. 5. Adjust the inlet guide vanes of the fan to 10% using manual control; fully open the anti-surge valve and close the outlet valve of the fan. 6. Start the machine to rotate the impeller, gradually increase the inlet guide vanes, and at the same time gradually reduce the anti-surge valve, adjusting the flow rate and pressure until they are within normal ranges. 7. Gradually open the outlet valve and close the anti-surge valve, maintaining the original flow rate and pressure

When starting the sulfur production blower: the inlet valve should be slightly opened (10%~15%), the vent valve should be opened to about 40%, and the outlet valve should be fully closed. If all the inputs are turned off, I believe it is done to stabilize the current and prevent power outages due to overload.