Why is the hydrocarbon separator installed here, and why is the temperature high? Why are the temperature and humidity of hydrocarbons also low?
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Our factory uses the alcohol-hydrocarbonation process developed by Hunan Anchun. The main purpose of this process is to remove carbon monoxide and carbon dioxide. In this process, the hot gas exiting the hydrocarbonation tower is at around 130 degrees Celsius; it then goes to a preheater where its temperature is reduced to 65–75 degrees Celsius. Next, it passes through a hydrocarbon separator to separate the hydrocarbons. After that, it goes to a water cooler where its temperature is lowered to about 25 degrees Celsius. It then enters a vertical ammonia cooler to be cooled further to 6–10 degrees Celsius. Finally, the mixture is separated into water and hydrocarbons, and the hydrocarbons are sent to a compressor for pressurization. My question is why the hydrocarbon separator is installed in front of the water cooler – the temperature during gas separation is around 65 to 75 degrees Celsius. Why isn’t it installed behind the water cooler, or behind the vertical hydrocarbon ammonia cooler, where the temperature is lower and separation can be more thorough? Another question is why, for the separation of hydrocarbons from water, the required temperature for the gas is between 6 and 10 degrees Celsius. Is this temperature not a bit too low? Isn’t there a large difference compared to the temperature of 65 to 75 degrees Celsius used in the hydrocarbon separator earlier?
Let me share my understanding: As the name suggests, a hydrocarbon separator is primarily used for separating hydrocarbons. Hydrocarbons are likely multi-carbon organic molecules that begin to condense at temperatures in the high 60s; they have high viscosity, and separation after water cooling can easily lead to wax formation that blocks the heat exchange tubes； Hydrocracking water separation primarily removes water; the lower the temperature, the more thorough the separation, but it is necessary to keep the temperature above 0 degrees to prevent freezing, so it is maintained between 6 and 10 degrees
The installation of this separation point can be considered here when waxing occurs in large methanol towers.