Risk identification for startup and shutdown of methanol cracking hydrogen production units
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What are the safety hazards associated with starting up and shutting down methanol cracking hydrogen production units? In particular, which factors can cause flash explosions during venting at high pressures? I earnestly hope that those with more experience can share their insights. :handshake
Safety concerns: Just be careful not to hold back pressure; how could there be a flash explosion when releasing pressure at higher levels? Unless there’s thunder, and nowadays many companies simply release gas from the pipelines for burning!
When we started up the methanol-to-hydrogen plant here, before introducing the PSA unit, venting at high pressure did result in a flash explosion, with flames shooting out more than ten meters away. The cause has not been found yet.
When we started up the methanol-to-hydrogen plant here, before introducing the PSA unit, venting at high pressure did result in a flash explosion, with flames shooting out more than ten meters away. The cause has not been found yet.
There’s an exhaust point at this high position; my previous factory had one as well, with a flame arrester installed on top. But how can there be a flash explosion without any source of fire? Is the flow rate too fast? If a flash explosion has occurred, the cause must be investigated – safety is of the utmost importance!
Before starting the machine, the pipeline was vented without nitrogen replacement; at that time the test results for the converted gas hadn’t come back yet, and a PSA unit wasn’t in use. The amount of gas vented was relatively large – I wonder if this is related to it?
The hydrogen we use here is supplied by an external factory; the methanol-to-hydrogen production unit is activated only when there is a disruption in the supply of hydrogen from outside. This time, it was shut down for several months before being turned back on.
The flash explosion that occurs during the shutdown of hydrogen production units is caused by the rapid flow rate of hydrogen-containing gases during venting, which generates static electricity at the vent outlet; this electricity then ignites the combustible gases, leading to a flash explosion. Therefore, during the operation of the equipment as well as during start-up and shutdown periods, the discharge of high-pressure hydrogen-containing gases (with a pressure higher than 0.2 MPa) on-site is prohibited, in order to avoid potential safety hazards to the plant area in the event of a flash explosion.
Can purging the pipeline with nitrogen during startup and shutdown solve this problem?
In the PSA system, the replacement is unsatisfactory, the oxygen content is too high, and static electricity during venting can cause a flash explosion