| CDQ technology is a major saving energy and reducting emission project. With the implementation of the relevant policy requirements, CDQ technology spreads and applies in China gradually. The technology has three major advantages relative to wet coke quenching:saving energy, improving coke quality and protecting the environment. At present, the common CDQ technology is used by nitrogen, which requires to complex and expensive air separation unit. The paper proposed using coke oven gas as CDQ cooling medium and mainly studied the bed pressure drop and heat transfer. The influence of bed pressure drop was made by qualitative and quantitative analysis. In addition, the paper also developed new CDQ technology and equipment——combined type CDQ technology and segmental CDQ technology. The main conclusions are made as follows:1, The bed pressure drop is 46% smaller with the use of coke oven gas than N2 under 6m3/h.2, The bed pressure drop is mainly related to coke particle size, bed voidage, gas viscosity, gas density and other factors. Under the same kind of gas, the bed pressure drop increases with quantity of gas increasing and decreases with the coke size increasing in the CDQ plant. The bed pressure drop with using different gases is in accordance with their density under 6m3/h, which shows that gas density is a major factor.3, The bed pressure drop mathematical model of CDQ plant with COG is established and simulated based on the experimental data. The equation of bed pressure drop is established for small CDQ plant with coke oven gas: The formula is contrasted with Ergun formula, and it is found more applicative than Ergun.4, The paper has researched heat balance for dry quenching of coke oven gas, which can provide a reliable technical basis to ensure the operation of CDQ system; Coke quenching time is shortened with using coke oven gas, which is about 69.5% of nitrogen quenching.5, A combined type of CDQ technology is developed. Its equipment consists of quenching tank holder (1-5), connecting pipes, receiving and quenching tanks and tankers. It replaces the existing single large coke quenching equipment and eliminates the need for complex input devices such as elevator, thereby reduces investment. The parallel receiving and quenching tanks of combined CDQ equipment can be more or less. It has flexibility to adapt to different production capacities. Through a simple combination, it can meet the coking plant of 60 to 100 tons and can be adapted to 500 to 1,000 tons. In a word, the low-temperature heat transfer medium nitrogen or reductive gas (H2, CO, CH4 or their mixture gas, such as coke oven gas) is input into receiving and quenching tanks. Through controlling the valve of connecting pipe, the coke temperature can be dropped to 250℃, while heat transfer medium is heated to 800-950℃.In all its process is simple and easy to operate.6, The paper has also raised the sectional CDQ technology. Its device has prestoring section, gasification cooling section, transition section, physical cooling section and layouting section from top to bottom. Water gas is fed to the gasification cooling section and coke oven gas is fed to physical cooling section, whose aim is to make majority high-temperature coke heat use for water gas reaction and to produce more water gas. With using of the CDQ technology, when 1t coke is quenched, it needs 1060.2 m3 water vapour and coke oven gas, which is 68.33% of amounts of nitrogen (1551.5 m3), and gas mixing ratio is reduced by 31.7%. It needs 55.2m3 water vapour, consumes 23.8kg carbon and produces 99.6m3 gasification gas. In brief, the sectional CDQ technology can efficiently use high temperature coke heat, turn it into synthetic gas, and have a characteristic of recovering coke heat and improving coke quality. It is a new coke dry quenching technology with producting coal gas and cooling high-temperature coke.
|
PDF Full Text Request