Thermal exhaust gas cleaning with waste heat utilisation for steam generation

As general contractor, Birk supplies a ready-to-operate thermal afterburning plant / thermal exhaust air purification plant of a downstream waste heat recovery plant in vertical design to a renowned steel refining company.

The post-combustion plant / exhaust air purification plant was designed for a raw gas volume flow of approx. 160 mn³/h of inert exhaust air with harmful gas components from upstream kiln plants. The firing plant is equipped with the latest burner generation of our self-developed industrial firing plants - for best clean gas values, low energy consumption and high flame stability. In addition, the plant is equipped with a clean gas temperature control system which continuously regulates the temperatures of the clean gases to be discharged at a level of approx. 550°C in order to keep the downstream waste heat recovery system for steam generation in the optimum efficiency range.

The waste heat recovery system is designed for exhaust gas temperatures of approx. 550°C, which makes it possible to recover a steam heat output of 55kW with the entire clean gas volume flow of the post-combustion system and the relatively low pollutant gas volume of the upstream furnace process, and thus to generate steam temperatures of 155°C at 5.5 bar for feeding into the on-site operating steam network, in order to subsequently use it in various production processes. The scope of the heat recovery system also included the entire area of the fully insulated clean gas supply and discharge in the waste gas system of the thermal afterburning system from the outlet at the clean gas blower via the heat exchanger of the waste heat recovery system back into the clean gas pipeline.

A further scope of supply was the entire internal steam piping between the heat recovery system and the steam drum as storage and connection point for on-site removal. The independent exhaust air volume flow control of the heat recovery system is managed and controlled in such a way that there is no influence whatsoever on the upstream afterburning process or on the upstream furnace systems. The overall plant consisting of afterburning and waste heat utilisation has been realised in such a way that the individual plant components have been delivered almost ready for operation, i.e. pre-installed electrically and mechanically. The entire control, regulation and monitoring functions of the entire plant are performed by a common central control system based on Siemens S7, which is equipped with a user-friendly visualization system with touch function.

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