Waste Water Gas Compression

One of the by-products of anaerobic digestion in a sewage treatment plant is produced vapor from the digester tank. This relatively low BTU gas (typically 900-1000 BTU/cu. ft.) is comprised primarily of 55% methane and 45% carbon dioxide (CO₂). Sewage digestion takes place in an aqueous environment, therefore, the gas is saturated with water when it comes off the system. HY-BON/EDI was instrumental in the development of a specialized compressor package for the capture and compression of these highly corrosive vapors.

Since that time, HY-BON/EDI has provided integrated packages for waste water treatment facilities across the United States and across the globe. HY-BON/EDI is a leader in waste water gas recovery, and can offer standard packages or custom designed units to highly detailed customer specifications. With over 50 years experience in handling low pressure gas streams, HY-BON/EDI’s engineers can draw on experience from multiple industries to address the most challenging gas streams.

These waster water compression packages typically incorporate the use of a rotary vane compressor to take these vapors from a pressure of 2-3” W.C. to 40 psig or less discharge pressure. These waste water compressed vapors are sent to one of three systems where they are utilized for a beneficial purpose. One system involves natural gas burning generator sets to generate electricity to be used by the sewage treatment plant. The second system consists of a low-BTU fuel gas boiler system to generate steam for the sewage plant for heating purposes or to feed steam-powered turbines. The third beneficial use for the gas is to send it back to the bottom of the digester tank to be used to churn the sludge that collects on the bottom of the tanks.

Digester gas units must be constructed to combat the destructive effects of a saturated, high carbon dioxide (CO₂) content gas stream. HY-BON/EDI’s units are equipped with stainless steel piping and valve trims to handle the corrosive nature of the gas. In addition, the units must be able to address the issue of removing the water vapor from the gas stream. We utilize a suction filtration system and a discharge liquid knockout system to handle the water content within the gas stream. Despite sophisticated controls, all HY-BON/EDI units are designed for ease of maintenance, and years of trouble free service.

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