Boiler over-temperature during the commissioning phase of the catalytic cracking unit
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At the time of plant commissioning, the unit used a backup main fan; the high-temperature flue gas did not pass through the fan for energy recovery and entered the waste heat boiler directly, resulting in over-temperature conditions in the equipment inside the boiler as well as in the medium-pressure steam. Are there any measures or technical improvements that can solve this issue? It would be better if there are specific plans to share. Thank you first
The waste heat boiler bypass system includes a water seal tank for spraying water in the flue gas desulfurization process. It is also possible to set up water spraying in the flue
Some of the flue gas goes through a bypass line first; if it’s possible to increase the steam flow rate
1. Catalytic waste heat boilers need to be designed for multiple operating conditions, including at least the normal condition when the flue gas exhaust fan is in operation and the high-temperature condition when it is not in use. 2. When the exhaust fan is not operating, the temperature of the flue gas entering the waste heat boiler is around 650°C; however, the limited capacity of the catalytic device to generate steam means that the heat from the flue gas cannot be fully absorbed, resulting in a steam temperature that exceeds the design value. This problem becomes even more significant when a denitration module is used to limit the flue gas temperature. 3 Install water spray devices in the boiler system to absorb a large amount of heat from the flue gases by utilizing the energy of water evaporation. 4 While installing the spray device, it is possible to appropriately increase the heat exchange area to prevent excessive pressure drop on the steam side during high-load operation