Equipment issues in the cold drum section
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This post was last edited by Yan Xiangsi on 2016-1-5 at 08:40. The raw gas coming out of the coke oven is sprayed with ammonia water at the bridge pipes and gas collection tanks, which results in a temperature drop of 10°C. In the subsequent stages, however, it is only after the raw gas passes through numerous direct-cooling wash towers and cross-tube coolers that another 10°C temperature drop occurs. Why then is such a large investment made in those tall direct-cooling and cross-cooling towers just to achieve a 10°C temperature reduction in the raw gas? Why is this type of cross-cooler used to cool raw gas, rather than something else such as a shell-and-tube heat exchanger? . . . . .
The waste gas cools from 700°C to 80 in the gas collection duct℃； The cross-tube is cooled to just over 20°C ； The cross-tube heat transfer efficiency is high ； Save water ； Direct cooling provides good purification effects ；
The temperature of the raw gas, which is over 80 degrees when it comes out of the gas collection pipe, drops to around 22 degrees after passing through the cross tubes. Moreover, the function of the primary cooler is not only to lower the temperature of the gas, but also to recover the large amounts of naphthalene and tar present in the raw gas using this cooler. The horizontal tube primary cooler can perform well, and its design is also good. For other types of heat exchange equipment, they are likely to become clogged with tar and naphthalene. It actually increases the usual workload.
The horizontal tube primary cooler is also a shell-and-tube heat exchanger; it’s just called a primary cooler. Moreover, the temperature reduction isn’t 10 degrees – it goes from 750 to 82 after spraying, and then further reduced to 22 through primary cooling.
How is it only decreasing by ten degrees? Do you have any basic common sense? First, check whether your home meter is working properly. As for the reason for using horizontal pipes as well, it has been explained very well above.
Maybe what you’re seeing is a broken thermometer； Otherwise, it’s just a misperception.