【Daily Question 20090218】 How to control and replace the solvent in a short-term shutdown of the coupling reaction unit

1. Prepare for parking, contact relevant teams such as those responsible for transformation and refining, and operate according to the parameters applicable when there is no methanol present； Open the fresh gas bypass valve, close the system inlet and outlet valves, as well as all vent valves and sampling valves ； 3. Shut down the furnace and the circulator, close the alcohol release valve, and maintain a static state with insulated conditions and pressure.

A shuts off the inlet and outlet valves. Stop the circulation machine at B. Release valve after starting the C tower (if pressure relief is required). D. Pay attention to the alcohol level.

Short-term shutdown involves stopping the operation at normal reaction temperatures and higher pressures; after cutting off the supply of supplementary gas, it is necessary to first lower the temperature of the catalyst layer slightly before shutting down, in order to prevent a rapid increase in temperature due to the sudden stop of the circulation pump. After some time, the temperature began to drop, and the longer it was parked, the more the temperature decreased. During short-term parking, the system should maintain a high pressure so that normal production can be resumed shortly after starting up. If repairs are required after depressurization, the temperature of the synthesis tower drops rapidly, and heating is often needed when restarting operation. The steps for short-term parking are as follows: ⑴ Notify the relevant processes to stop gas supply. ⑵The cycle compressor is shut down. ⑶Close the inlet and outlet valves of the synthesis tower to maintain the catalyst bed temperature. ⑷Depending on the liquid level in the methanol separator, after draining all the methanol, close the methanol discharge valve.