Control method for overheating in the superheating section during hydrogen production startup and steam grid connection

It is recommended to bring in the high-pressure steam that needs to be connected to the system in advance, so as to avoid overpressure

The OP said the description doesn’t feel right, right? How can there be no flow in the superheating section? The entire gas generation process, including the filling of the boiler with water, is ongoing. Initially, the amount of gas generated may be low; in such cases, it can be vented on-site or connected to the 1.0 MPa pipeline network. If the amount of water added is too large, it becomes difficult to maintain the liquid level in the drum, so it is possible to increase the volume of wastewater discharged either periodically or continuously ； Depending on the pressure conditions in the conversion system, the pressure in the drum should be increased gradually. During this process, if the amount of PSA purge gas entering the conversion furnace is high and causes the temperature in the furnace to rise, part of that purge gas can be vented to the flare!

During grid connection, the vent to the atmosphere is gradually closed, allowing the pressure in the drum to rise slowly (to above 0.8MPA–2.8MPA), until the drum pressure exceeds that of the medium-pressure steam network, at which point the grid connection valve is opened. Therefore, during the grid connection process, the drum is generating steam, but the amount of steam escaping decreases gradually, resulting in over-temperature in the superheating section.

Is this how you connect to the grid?

The owner’s method of connecting to the grid actually does not solve the problem of steam discharge; whether it is by venting or by reversing the steam flow, it simply provides a way for pressure to be released from the superheating section. I agree with this user’s suggestion: in the initial stage, since the pressure in the drum is low, it is possible to simply vent the steam, but reversing the steam flow can cause damage to the drum’s cyclone separator.

I have seen designs from Huaxi that include measures to cool the boiler water using spray.

1. Install a temperature-reducing valve at the inlet of the superheated steam section to reduce the temperature using boiler feed water. 2. When the steam pressure is insufficient, the superheated steam can be fed into the 1.0 MPA steam network

Should the PSA off-gases be fed into the converter before the air bladder pressure reaches 3MPA at the start of operation? When our installation started operation, the temperature was raised using a low-flame burner; only when the production volume was high did we use purge gas as the fuel for the main burner. During the grid connection process, it is inevitable for the gas generation temperature in the overheating section to rise, but this duration is very short; as long as the furnace temperature does not fluctuate too much, that’s fine. In our case, we started sending the gas out when the pressure was around 3.1, and the temperature didn’t seem to increase much

Our device introduces low-pressure steam into the superheating section to protect it!

The start-up of hydrogen production requires that all stages work in coordination with each other. For the hydrogen production unit in my facility, it is necessary to ensure that there is flow of medium in the superheated steam section before the conversion furnace reaches the temperature level at which steam can be generated (this is achieved by venting through the on-site superheated steam silencer). Once the pressure in the steam drum starts to increase, the flow is then directed to the steam distribution network. During this operation, it is important to monitor the temperature increases at various points to prevent sudden rises or drops in temperature.