Research on thermal characteristics in natural circulation coke drying quenching boiler

Nowadays, as a key energy-saving promotion project, the technology of Coke Dry Quenching (CDQ) is a highlight in the metallurgical industry and coking plants, which has favorable social and economical benefits. The development of metallurgical industry is restricted by some industrial policies, such as energy-saving consumption, reducing the cost, increasing the ability of electricity self-supply, and protecting the environment, and so on. The Chinese government requires recovery more waste heat and generate more electricity during the CDQ process. Medium-pressure CDQ boiler, being an important part of the CDQ system, could not meet the increasing energy demands so far. Thus, the investigation of the high temperature and high pressure waste-heat boiler of natural circulation in the CDQ system becomes one of the vital topics. According to the process characteristics of coke drying quenching (CDQ) system, this paper gives the structure arrangement and heat distribution of the heating surfaces of the natural circulation CDQ waste-heat boiler with high pressure and high temperature, which guarantee the water natural circulation in a secure and reliable way. In addition, thermal parameters are also analyzed referring to the operating experiences in CDQ boiler research. Besides, the calculation manner of the additional heating surface including water wall is presented. Finally, the difficulties and the corresponding measures that should be taken in the boiler design are discussed. Different design schemes are given and compared according to the difficulties, and an optimal scheme is presented in this paper. This study provides a reference for the design and development of the natural circulation CDQ boilers with high pressure and high temperature.