Charging and depressurization rates of lockboxes and their influencing factors

The pressurization and depressurization of the lock chamber mainly involve drainage and water filling, and the amounts involved are small; therefore, the rate has little impact on the cyclic production process. However, if the stamping and pressure relief times are too long, slag will accumulate in the quench chamber for an extended period, which can have some impact on the quality of the gasified water. From the perspective of the equipment, too fast pressure buildup and release can exert certain forces on the valves and the lock-hopper containers themselves. However, due to the speed at which the valves open and close and the capacity of the lock-hoppers, this impact force can be reduced or even eliminated, so that they are only subjected to alternating pressures. Therefore, the pressurization and depressurization rates for the lock cylinder should be considered from the following aspects: Regarding depressurization, it should be planned in a way that ensures the unobstructed flow in the depressurization lines while also being cost-effective ； (Generally, DN50 pipelines and valves are selected.) When it comes to pressurization, the response time of the measuring instruments and valves is a key factor to consider. If the pressurization occurs too quickly, exceeding the response time of these instruments and valves, the pressure in the holding tank will rise significantly above the pressure in the gasification furnace, which triggers an interlock mechanism (aimed at maintaining pressure balance before and after the opening of the slag inlet valve in the holding tank), resulting in the inability to open that valve. Therefore, there is a certain limit on the pressure-charging rate of the lock cylinder (usually 2 to 3 minutes is chosen)

The pressure charging pipeline is generally designed with this in mind!

I agree with the above statement; the chirping time can be increased, so this period can also be made a bit longer accordingly.

The lockfighting system is equipped with a cycle timeout shutdown feature; most manufacturers do not include this, but it is recommended to add it to avoid unnecessary problems caused by monitoring issues or other factors. If the pressure release time or pressure charging time is long, resulting in a longer cycle time, it may cause the lockhopper to trip.

The long pressurization time is easy to address; most factories now use multi-point pressurization. However, depressurization is more difficult – if there is backpressure in the vent line, it’s hard to reduce the pressure to the required level. Sometimes internal leakage in the pressurization valve also causes such problems

This is not easy to control; actual production is affected by various factors. I’ve only been working with DCS for less than half a year and still lack experience. I’m just sharing what I’ve encountered with everyone else. The pressure relief valves we have often leak internally, and the electrical and instrumentation teams aren’t very skilled either – they can’t fix the problems properly, so the pressure building up is extremely slow; sometimes it takes four or five minutes before any pressure is achieved. In such cases, we have to switch to manual operation and release the pressure manually. This sometimes leads to poor slag collection in the holding tank. I was thinking about adding another pressure-feeding pipeline – I’m not sure if that would work. I’ll ask my supervisor about it when I get to work this afternoon

Add a manual valve in front of the pressure relief valve; it can also be placed behind it. By closing the manual valve, pressurization can be controlled, thereby avoiding unnecessary shutdowns.