Gentlemen! Why is the temperature of the feed gas entering the methanol wash generally controlled at around 35–40°C?
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Gentlemen! Why is the temperature of the raw gas fed into the methanol washing unit generally controlled at around 35–40°C, in order to prevent excessive water content? Balanced cooling capacity? There must be some other reasons as well. All the pipelines in our facility are equipped with heat tracing. What is the purpose of heat tracing? Prevent ammonium salt crystallization?
It is necessary to prevent excessive water content; if the temperature exceeds 40 degrees Celsius, the amount of water will definitely increase, which will affect the separation of methanol from water. This, in turn, impacts the moisture content in methanol and subsequently affects the absorption process. The purpose of providing heating is mainly to prevent the crystallization of ammonium salts.
This post was last edited by caocheng on 2024-11-13 09:00, awaiting a standard analysis answer
High temperatures, along with water, affect the separation of methanol from water and also increase the load on the system. Too low a level can cause ammonium salt crystallization. Excessively high temperatures will inevitably lead to a high ammonia content, as it is detrimental to the desired effect. Low temperatures can cause the temperature of the converter cooler to drop too low, leading to the liquefaction of CO2 and affecting the methanol-water separation system, which in turn results in unstable pressure in that system
As I understand it, with circulating water cooling, the temperature usually stays this high. We don’t have heat tracing, and temperatures can drop to the low teens in winter.
At what temperature below does carbon dioxide liquefy?
Low-temperature methanol washing (Rectisol) is a gas purification process that utilizes the high solubility of methanol for acidic gases such as CO2 and H2S at low temperatures, in order to remove these acidic gases from the feed gas. This process is typically operated at low temperatures (around -35°C to -55°C, and even up to -60°C) to ensure efficient absorption of acidic gases. Improving absorption efficiency: The solubility of methanol for acidic gases increases significantly as the temperature decreases. However, allowing the feed gas to enter an environment with excessively low temperatures may cause issues such as frosting and blockages in the equipment. Therefore, preheating the feed gas to around 35–40°C before it enters the methanol washing system ensures that methanol can maintain a certain absorption efficiency at relatively high temperatures, while also avoiding equipment issues. Protection equipment: The feed gas may contain moisture, impurities, etc.; if it enters a low-temperature environment directly, it can freeze and deposit inside the equipment, leading to equipment damage or blockages. Preheating the feed gas makes it easier to handle moisture and impurities in it, thereby reducing damage to the equipment. Optimizing process operations: Preheating the feed gas to an appropriate temperature can also optimize the operating conditions of the entire methanol washing process, such as reducing energy consumption and improving system stability.
At 3.3 MPa, liquefaction at -1 degree； Liquefaction at 22 degrees at 6.0 MPa