Comparison of the advantages and disadvantages of the \"washing method\" and \"pressure swing adsorption method\" for concentrating and purifying biogas to produce biomethane

This post was last edited by Sky Gate on 2016-3-22 at 16:08. Both methods have their own advantages and disadvantages. We can handle both process flows. In comparison, pressure swing adsorption has a greater competitive advantage. The poster can leave a contact method and send over the detailed parameters (components, pressures of feed gas and product gas, etc.). We can then develop a plan for comparison and have a discussion.

Pressure swing adsorption is used for methane gas decarbonization, and the parameters of the resulting gas can meet CNG standards right from the start; however, the maximum yield of CH4 is only 93%, and in some cases it is even lower. Ammonia-based absorption is used; the product gas needs to be dried. Although the yield of CH4 is high, the energy consumption for separation and regeneration is considerable ； It is commonly used in the pre-CO2 removal process for LNG. Another point is that if desulfurization is carried out using the amine method, it will consume the amine solvent contained within. Through membrane-based decarburization, the parameters of the product gas can directly meet CNG standards, with a CH4 recovery rate of over 95% ； The process is simple, requires no regeneration, and has relatively low energy consumption. High requirements are mainly placed on gaseous impurities that enter the membrane. The washing process is similar to the amine method, with no chemical solvents used.

The programmable valves in the pressure swing adsorption process need to be replaced frequently, which affects startup time. The amine method has the problem of secondary solvent pollution; I still recommend the membrane method. However, it also needs to be determined based on different scales and materials.

The programmable valves used in pressure swing adsorption need to be replaced frequently. Please make sure that those who manufacture programmable valves don’t see this statement~~~ How often does \"frequently\" refer to here?

The valve operates by opening and closing every 10 minutes or so; you can calculate how many times it does this in a year. If valves made abroad are of good quality, the competition in the domestic market is so fierce that it’s difficult to ensure consistent quality. Everyone claims their valves are fine, but if customers choose suppliers based on price, there’s not much that can be done but sigh. This is true not only for valves but also for many other domestic products – they either don’t work properly or sacrifice quality in order to be affordable. It’s a pity for the domestic market

Well, the project we’ve been working on for seven or eight years now, and there have been no problems with the programmable valves so far. The mechanical operation and sealing of these programmable valves are generally fine; it’s usually the solenoid valves that cause issues. It’s essential to choose imported solenoid valves

Are you also working on biogas purification projects? Is one running? Which project?

It’s been seven or eight years and the programmable valve hasn’t had any problems? That’s true; there are many problems associated with the solenoid valves that go along with programmable valves. Those solenoid valves are used to supply instrument air to the pneumatic programmable valves, and if there’s a problem with them, the programmable valves can no longer switch in accordance with the PSA timing. We use American solenoid valves; due to the harsh working conditions, they often get clogged, and the soil and sludge need to be cleaned and replaced frequently. The sealing of the programmable valve must be perfect; there must be no air leakage or cross-ventilation.

Pressure swing adsorption technology is highly developed in China, and it is more than sufficient for use in purification purposes.