How to prevent frosting on liquefied gas pipelines

It can certainly be avoided, but frost formation usually occurs in areas where there is throttling or leakage, making it difficult to maintain insulation. The insulation layer must be properly sealed so that outside air cannot get in, in order to prevent frost from forming.

When liquid material is vaporized or when pressure is reduced rapidly, heat is absorbed due to volatilization or expansion of the vapor, causing the temperature around the pipes to drop sharply. When this temperature reaches the dew point, moisture in the surrounding air will condense on the pipe walls, resulting in dew formation – what is commonly referred to as \"sweating\". If the pipe temperature drops below freezing point, frost or ice will form. Under normal circumstances, as mentioned on the second floor, such situations are caused by throttling, venting, or liquid phase leakage. The main hazard of frosting lies in the low temperature of the pipelines, which can damage the pipe material; in severe cases, this can lead to brittle fracture, and this must be avoided. Therefore, controlling the rates of throttling and venting or using low-temperature steel are the fundamental solutions. Simply avoiding frosting is not a proper solution (frosting does not occur in a vacuum, but the hazards remain). I think it’s also impossible to avoid frosting by using insulation, unless there is heat tracing.

External frosting on the pipe is caused by throttling; according to the law of conservation of energy, kinetic energy increases while pressure energy and internal energy decrease. The decrease in temperature does not come from the outside environment but from within. Insulation helps prevent external moisture from entering, which reduces frost formation; however, the temperature still drops. At low temperatures, steel becomes brittle, which can eventually lead to the rupture of pipelines. Therefore, it is not necessary to insulate against cold – rather, increasing air circulation or using external heat exchange measures (such as fins) is what is needed. The fundamental method is to control the throttling speed. For details, please refer to \"Crude Oil Pipeline Transportation Technology\", compiled by Huang Chunfang from the China Petroleum and Natural Gas Pipeline Institute, published by Sinopec Press

Cooling is generally applied at the inlet of the pump, not at the outlet. Unless the company has so much money it can’t spend it and still feels compelled to do it.

Insulation is a wrong approach; heat needs to be supplied during flow restriction and pressure reduction, and insulation prevents external heat from entering, resulting in a greater drop in temperature even though frosting does not occur. Moreover, frosting generally makes it difficult to lower the material’s temperature below its allowable temperature; if such a situation does occur, care should be taken in selecting the material. Be cautious of potential heat interception and temperature drop, to avoid excessive temperature reductions.

For liquefied gas pipelines, frost forms whenever they come into contact with air; therefore, liquefied gas pipelines in refineries are insulated to prevent this. The most important aspect is having a reliable moisture-proof layer to stop air from coming into contact with the pipes (when they are exposed).

Add insulation layers, or heat tracing pipelines, etc

If it poses no harm, just let him drip it. We use dripping in many places here: L

As long as the pressure and flow rate remain stable, let frost form – it doesn’t affect safe production:lol

Polyurethane can provide insulation

This unit is also experiencing pipeline dew formation right now due to internal leakage in the front valve, but for some reason no one is addressing it. . .

By the way, this device’s pipeline is made of special steel; I’m not sure about the specific model