Influencing Factors of Gas Collector Pipe Cooling
Release date:
Dec 04,2023
The cooling of coke oven gas and its resulting dew point temperature are affected by the following factors: moisture content of coal charge, gas temperature before entering the gas collector pipe, circulating ammonia water volume and inlet temperature, and ammonia water spraying effect, among which the moisture content of coal charge exerts the most significant impact. Under typical production conditions, every 1% reduction in coal moisture can lower the dew point temperature by 0.6 to 0.7°C. Evidently, reducing coal moisture is critical for gas cooling in both gas collector pipes and primary coolers.
The cooling of coke oven gas and its resulting dew point temperature are affected by the following factors: moisture content of coal charge, gas temperature before entering the gas collector pipe, circulating ammonia water volume and inlet temperature, and ammonia water spraying effect, among which the moisture content of coal charge exerts the most significant impact. Under typical production conditions, every 1% reduction in coal moisture can lower the dew point temperature by 0.6 to 0.7°C. Evidently, reducing coal moisture is critical for gas cooling in both gas collector pipes and primary coolers.
Gas cooling mainly relies on the evaporation of ammonia water. Higher atomization degree of sprayed ammonia water and higher temperature of circulating ammonia water contribute to greater ammonia evaporation volume, which delivers superior gas cooling performance; the opposite leads to poor cooling effects.
Cold water spraying is prohibited during normal operation of gas collector pipes. Cold water evaporates poorly and provides weak cooling capacity. Meanwhile, mineral impurities contained in cold water will raise the ash content of tar. In addition, the extremely low temperature of cold water causes intense cooling at the bottom of gas collector pipes, increasing the viscosity of condensed tar and resulting in frequent pipe blockages.
The dew point temperature of gas before entering the collector pipe is correlated with the moisture of charged coal. When the total moisture of charged coal ranges from 8% to 11%, the dew point temperature stands at approximately 65 to 70°C. To maintain sufficient driving force for ammonia water evaporation, the inlet temperature of ammonia water should be 5 to 10°C higher than the gas dew point temperature. Therefore, circulating ammonia water at 72 to 78°C is adopted for gas spraying. This method avoids the drawbacks of cold water spraying. Moreover, alkaline ammonia water neutralizes tar acids to protect gas pipelines. Ammonia water also has lubricating properties that facilitate tar flow and prevent pipeline blockages caused by tar accumulation.
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