【Q&A Question 220】November 26, 2016
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【Q&A Question 220】November 26, 2016: Why is it necessary to control the outlet temperature of the high-pressure air cooler? A reference ** will be shown after responding; scoring is achieved by answering the key points. 1. The lower the air-cooled outlet temperature, the smaller the linear velocity of the gas within the high-pressure section, and thus it is less likely for liquid to be carried along ； The opposite is true for high outlet temperatures. 2. The solubility of hydrogen increases as the temperature rises; too high a temperature leads to an increased amount of hydrogen dissolved in the oil, resulting in losses. 3. The excessively high temperature at the air-cooling outlet leads to an increase in linear velocity and an increase in the amount of liquid carried, which is not conducive to the safe operation of the cyclohydrogen compressor. The purpose of controlling the high-pressure air cooling outlet temperature at ≤50°C is to prevent excessive linear velocity of the high-velocity gas from entraining liquid and disrupting the cycle. In units designed for circulating hydrogen desulfurization, the excessively high outlet temperature of the high-pressure air cooler causes hydrocarbons to be carried in the circulating hydrogen, leading to foaming of the amine solution and a reduced desulfurization efficiency. In severe cases, liquid is carried in the circulating hydrogen, which affects the safe operation of the circulating hydrogen compressor. Summary post of Q&A from 2016 (updated as of November~~~~) http://bbs.hcbbs.com/thread-1597792-1-1.html Seeking sponsors for the “2016 Haichuan Top 10 Members Selection Contest” http://bbs.hcbbs.com/thread-1628108-1-1.html (Source: Haichuan Chemicals Forum)
1. High air-cooling temperatures can easily cause liquid to be carried in the circulating hydrogen, which has a significant impact on the dry gas seal of the hydrogen circulation pump； 2. The air-cooled outlet temperature is high; circulating hydrogen tends to contain hydrocarbons, resulting in a low recovery rate of hydrogen from the cold fractionator ； 3. The air-cooling outlet temperature is low, resulting in poor oil-water separation in the cold fractionator, and high energy consumption for air cooling.
Dew point corrosion should be taken into account.
1. If the outlet temperature of the cold high-pressure fraction is too high, hydrogen has a higher solubility in the oil, resulting in increased hydrogen loss. Lowering the temperature of the cold high-pressure fraction allows hydrogen to escape from the oil and more light hydrocarbons to condense, which helps improve the purity of the recycled hydrogen； 2. The outlet temperature of the cold high-pressure section is too low, making it difficult to separate oil from water.
Lowering the temperature allows the condensable oil and gas to condense, preventing the amine solution in the high-pressure cyclohydrogen desulfurization tower from foaming due to oil contamination, which in turn would cause failure of the cycle compressor as a result of liquid ingress.
1. The lower the air-cooled outlet temperature, the smaller the linear velocity of the gas within the high-pressure section, and thus it is less likely for liquid to be carried along； The opposite is true for high outlet temperatures. 2. The solubility of hydrogen increases as the temperature rises; too high a temperature leads to an increased amount of hydrogen dissolved in the oil, resulting in losses. 3. The excessively high temperature at the air-cooling outlet leads to an increase in linear velocity and an increase in the amount of liquid carried, which is not conducive to the safe operation of the cyclohydrogen compressor. The purpose of controlling the high-pressure air cooling outlet temperature at ≤50°C is to prevent excessive linear velocity of the high-velocity gas from entraining liquid and disrupting the cycle. In units designed for circulating hydrogen desulfurization, the excessively high outlet temperature of the high-pressure air cooler causes hydrocarbons to be carried in the circulating hydrogen, leading to foaming of the amine solution and a reduced desulfurization efficiency. In severe cases, liquid is carried in the circulating hydrogen, which affects the safe operation of the circulating hydrogen compressor.
1. High air-cooling temperatures can easily cause liquid to be carried in the circulating hydrogen, which has a significant impact on the dry gas seal of the hydrogen circulation pump； 2. The air-cooled outlet temperature is high; circulating hydrogen tends to contain hydrocarbons, resulting in a low recovery rate of hydrogen from the cold fractionator ； 3. The air-cooling outlet temperature is low, resulting in poor oil-water separation in the cold fractionator, and high energy consumption for air cooling.
1. If the outlet temperature of the cold high-pressure fraction is too high, hydrogen has a higher solubility in the oil, resulting in increased hydrogen loss. Lowering the temperature of the cold high-pressure fraction allows hydrogen to escape from the oil and more light hydrocarbons to condense, which helps improve the purity of the recycled hydrogen； 2. The outlet temperature of the cold high-pressure section is too low, making it difficult to separate oil from water.
1. Prevent amine liquid from entering the inlet of the cyclohydrogen compressor； 2. Prevent circulating hydrogen from contacting light hydrocarbons ； 3. Prevent excessively high temperatures after cooling, which can lead to an increase in molecular weight and higher energy consumption of the circulation machine.
1. If the outlet temperature of the cold high-pressure fraction is too high, hydrogen has a higher solubility in the oil, resulting in increased hydrogen loss. Lowering the temperature of the cold high-pressure fraction allows hydrogen to escape from the oil and more light hydrocarbons to condense, which helps improve the purity of the recycled hydrogen； 2. The outlet temperature of the cold high-pressure section is too low, making it difficult to separate oil from water.
1. If the outlet temperature is too high, the solubility of hydrogen in the oil increases, leading to greater hydrogen loss； 2. If the outlet temperature is too high, the amine solution tends to foam, resulting in liquid being carried along with the circulating hydrogen.