GE gasifier lockhopper
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This post was last edited by xuqinger on 2009-10-20 07:45. I would like to ask experienced experts: In the sequential control of the lockhopper in a GE gasification furnace, what is the outlet of the lockhopper (should it be the inlet instead?) ) Why are two shut-off valves installed?
The one above serves a safety purpose; it remains open at all times, and it closes only when the slag lock valve below develops a leakage issue due to poor sealing.
Thank you for your guidance. I basically understand that they are valves for use as backups; the process package mentions that the two valves are used alternately
It can be set to alternate use, changing once per cycle； It can also be used as a backup, with replacement every cycle.
Both valves are put into use when they are functioning properly. If one valve fails, it can be manually opened (kept in the open position, bypassed in the program), while the other valve continues to operate under program control; repairs can be carried out during shutdown
There are two theories: 1. The two are used alternately； 2. One is normally open and serves as a safety valve as a backup; the other is a slag discharge valve, which opens and closes to discharge slag according to established procedures.
Since there are still certain reliability issues with lockout valves at present, it is sufficient to have two of them as backups for each other.
It seems that mutual backup is not allowed; one of these components is a safety valve, whose trigger for closing is a low-low liquid level in the quench chamber of the vaporization furnace. Under normal conditions, this valve remains in its fully open position. Even if the lockhopper inlet valve leaks, the plant must be shut down to address the issue; from a safety perspective, it is not permissible to use this valve as a backup for production purposes. In other words, although this valve is located at the lockhopper inlet valve, it actually serves a function that has nothing to do with the lockhopper.
Once GE’s process package is set to one cycle, the two valves are swapped; few manufacturers actually configure it in this way
The first one is the safety valve, which shuts down automatically when the liquid level in the quenching chamber is very low; the second one is the slag collection valve
GE designs these two valves to be used alternately, with each being used once in successive cycles; in the second cycle, the functions of the safety valve and the slag collection valve are swapped； Currently, manufacturers typically use valves at the top or bottom as safety valves. However, in the event of a failure in the slag collection valve, it is possible to swap their functions by changing the wiring, thereby ensuring the normal operation of the lock hopper.