Acid gas drying is a process that removes a large percentage of the water vapor in natural gas, allowing for a more stable pipeline and decreasing corrosion, hydrate formation, and the need for corrosive chemicals.acid gas drying It is a vital part of the natural gas processing chain for many natural gas projects and is often paired with molecular sieves to meet strict sulfur emission requirements. This article provides a detailed discussion of the processes and equipment used to dry acid gas and the benefits of using this type of technology. It also discusses the various factors that can affect dehydration performance.
There are two types of acid gas drying technologies: chemical and physical. Chemical solvents are liquid solutions that are able to absorb and dissolve acid gases. Chemicals such as monoethanolamine (MEA), diethylene glycol (DEG) and triethylene glycol (TEG) are the most common. Physical desiccants such as silica gel and zeolites are also common. These solid desiccants, however, are unable to adsorb water vapor at lower temperatures and require high temperatures for regeneration.
Typically, natural gas is first dehydrated with an AGRU prior to compression and cooling. The gas then goes to a central processing plant, where the final pipeline or LNG specification is met through further dehydration. In this type of system, a TEG dehydration unit is commonly installed downstream of the AGRU.
This process can be expensive. It requires high pressure pumps, heat exchangers, reboilers and amine reclaimers. Additionally, it may require special metallurgy to ensure longevity. To reduce these costs, it is possible to use a new technology that offers the same results with significantly less energy.
Molecular sieves are a non-chemical way to remove moisture from natural gas. Unlike chemical solvents, which require a high temperature for regeneration, molecular sieves can be regenerated at much lower temperatures. This makes them a cost-effective and environmentally friendly alternative to conventional dehydration methods.
A new process for separating CO2 from sour gas was developed recently, and it is very promising for the oxy-fuel IGCC power generation industry. The proposed process uses steam condensation instead of the traditional MDEA or other carbon capture processes, which consumes a lot of energy. Its energy efficiency is estimated to be as high as 44% LHV.
The acid gas drying process is critical for oxy-fuel IGCC plants because it reduces energy consumption and increases thermal efficiency. However, the current sour gas dehydration processes are unable to achieve this goal because they produce a significant amount of water. This is due to the fact that they are based on the reversible chemical reaction of aqueous amines at high temperatures and pressures.
Nevertheless, a new technology was designed to remove acid gas from sour syngas with the help of a dry adsorbent material. The key feature of this technology is the use of a vapor phase of hydrogen sulfide, which is an excellent solvent for removing acidity and sulfur components from the gas. The technology was developed by a company called GazSurf, and it is capable of producing a full scale sour gas dehydration plant on a modular skid basis.
