Problems when heating the steam superheater
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Hello, colleagues. I have a question regarding heat exchangers. In the exhaust furnace of the plant, there is a steam superheater located behind it; this superheater uses the heat from the flue gases generated by combustion in the exhaust furnace to heat saturated steam. Steam flows through the tubes of the superheater, while the flue gases flow outside those tubes. When the flue gas furnace is ignited and heated, does it not need to be fed with steam for the steam superheater behind it? The exhaust furnace is raised to between 500-600 degrees. Can the steam superheater be operated without steam supply during the heating up of the flue gas furnace? Will it burn out the superheater? Thank you, looking forward to your participation
Hello, regarding the issue of whether steam should be injected into the steam superheater when heating up the flue gas furnace, generally speaking, at the start of heating the furnace, a certain amount of saturated steam is injected for protection, in order to prevent damage to the superheater pipes due to excessive temperatures. This helps to reduce the thermal stress caused by sudden temperature rises, and the flow of saturated steam also facilitates heat transfer, thereby preventing localized overheating in the superheater. If no steam is supplied, when the temperature in the exhaust furnace reaches 500–600 degrees, the empty superheater may deform or get damaged due to the insufficient heat resistance of its metal material. Furthermore, there are safety hazards as well, because if cold saturated steam is suddenly introduced while normal operation is in progress, the expansion and contraction due to temperature changes may cause cracks in the pipes or welding joints. Therefore, it is recommended that during the heating up of the flue gas furnace, an appropriate amount of saturated steam be injected in accordance with the design and material grade requirements of the superheater as well as the operating procedures. Meanwhile, the temperature and pressure of the superheater should be closely monitored to ensure a steady rise in temperature and prevent damage to the superheater. If there are specific operating procedures or manufacturer recommendations, please refer to the relevant documents for implementation. .
The equipment installed in a process usually has a reason for its existence; as for this heat exchange device, its purpose is to recover the preheated flue gas. Some devices are suitable for operating at certain temperatures, while others are not suitable for working in high-temperature conditions like these. It also depends on the process requirements of the equipment to determine whether it is possible to operate without steam. For reference.