Types of Compressed Air Dryers Part 3 –Heat of Compression, Single-Tower Deliquescent and Membrane Type Dryers
A careful examination of a facility's compressed air system will likely reveal several opportunities to improve the performance of the compressed air system by effectively and efficiently removing moisture from the compressed air system. The Compressed Air and Gas Institute (CAGI) committed to issuing a series of articles discussing moisture in the compressed air system.
Because of such a wide breadth of product offering, we will cover each of these dryer types in some detail. It is always recommended that the compressed air treatment products be discussed in concert with the entire compressed air system and the application of the products. You should consult a compressed air expert to assure that the compressed air dryer selected is correct for your application.
Every facility has differing application needs and usage demands, but selecting the right compressed air dryer for the situation will have a significant impact on energy savings and efficiencies. Two categories of air dryers — refrigerated dryers and desiccant dryers — are widely used in industrial applications, and both have a place in the market. There isn’t a one-size-fits-all dryer solution for every facility. However, looking at the energy costs associated with the various options can help determine which solution will be most beneficial.
Nitrogen is primarily used as a clean, dry inert gas where the reduction of Oxygen is required for certain products and processes. It is widely used in the food and beverage, electronics, laser cutting, chemical and oil & gas industries. The cost of producing Nitrogen by separating compressed air using Pressure Swing Adsorption (PSA) is significantly impacted by the treatment of the compressed air supply. The introduction of Adsorption Media Tube (AMT) technology in order to dry the compressed air prior to separation offers the potential to reduce compressed air energy costs up to 25%.
The Compressed Air and Gas Institute (CAGI) will be issuing a series of articles discussing moisture in the compressed air system and will provide a brief overview of the compressed air drying technologies available.
Triethylene glycol (TEG) dehydrators are the most prevalent technology for removing water vapor from natural gas . Molecular sieve dryers are also quite common in gas processing plants. Molecular sieve units have operating processes similar to industrial heat-regenerated compressed air dryers. Natural gas, however, often needs to be purified at the wellhead before reaching the processing plant. Deliquescent dehydrators are normally used, in remote locations where no power supply exists, to dry small gas volumes located between the wellhead and these main treatment plants. The most common applications are instrument gas, fuel gas, sales gas, and emissions mitigation.
Compressed Natural Gas (CNG) is an alternative fuel source (to diesel and gasoline) with far-reaching benefits to North America. Strategically important benefits include energy independence, improved air quality, job creation, and lower and more stable fuel prices. This paper discusses natural gas desiccant dryer requirements in Natural Gas Vehicle (NGV) refueling stations, compares deliquescent to desiccant dryers and reviews two on-site field gas upgrading examples in displacing diesel fuel.
In an ideal world, industrial air or gas supply lines would be free of particulate, water, oil and other contaminants. In the real world, however, supply lines typically deliver some contaminants along with the air or gas they were designed to carry. Left unchecked, these contaminants will cause efficiency losses, maintenance headaches and the premature failure of pneumatic components.
Energy efficiency and sustainability solutions are often associated with more obvious initiatives--such as installing compact fluorescent bulbs—but those solutions fail to dig deeper for the “hidden gems” that can have a much greater impact. For manufacturing and building engineers or anyone else dealing with high potential energy consumption and inrush current demands, compressed air systems are one of the first places to look for significant energy savings and greater sustainability.
What are the conditions inside your pipes, is it cloudy and hot with showers or cool and dry? Could there be snow and blowing snow and excessive icing conditions? Are there smog and dust storm conditions or is the air as fresh as a mountain breeze. All these conditions are commonly experienced inside compressed air systems. What you get is determined by your selection of system equipment, ambient conditions and how well your system is maintained.
Desiccant compressed air dryers offer a simple solution where very dry compressed air is required however there are some key issues which must be considered to make their operation reliable. In particular, excessive flow, low pressure, silencer back pressure and purge air must be carefully monitored and controlled. This paper discusses common issues affecting the reliability of compressed air desiccant dryers which lead to loss of performance.
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