Introduction


ARC Technologies' (ARC) proven two stage methane extraction system takes raw Landfill/Digester Gas (biogas) and converts it to pipeline quality natural gas and or CNG by removing all impurities in the raw feedstock.

Figure 1 - PSA
Figure 1

Figure 1 above shows the second stage of ARC Technologies' proprietary methane extraction system. The pressure swing absorption (PSA) unit is designed to remove carbon dioxide (CO2), nitrogen (N2) and oxygen (O2) from pretreated biogas gas streams. The resulting high-grade methane (CH4) product stream can be used as pipeline natural gas or CNG fuel. The PSA unit will automatically adjust its configuration when a sudden increase in N2 & O2 is seen in its feedstock, due to an upset (broken hose, etc.) in the gas collection system. This automatic function allows the system to continually produce pipeline quality gas. The system is designed to recover the maximum methane possible based on its feedstock gas quality.

The first stage of ARC Technologies' methane extraction system is its proprietary pretreatment process which removes the contaminants that are in the biogas's feedstock. These contaminants can cause serious problems in any plant's feedstock in regards to engine, turbine and gas processing equipment.

What is pretreated biogas?

Pretreated biogas is a gas stream in which the contaminants have been removed and can be delivered to the gas separation section of the gas plant or to a turbine/engine generator set to produce electrical power. The following contaminants need to be addressed in biogas, which will in turn greatly extend the life expectancy of the overall plant media, compressors and/or turbine/engine generator sets.  ARC Technologies' pretreatment process will remove the following contaminants:

Process Description

Figure 2 shows a schematic diagram of the major components of ARC Technologies' biogas treatment process.
 

Schematic diagram of the major components of ARC Technologies' biogas treatment process
Figure 2


In Figure 2, the landfill generates methane in an anaerobic bacterial environment. ARC Technologies' landfill vacuum blower shown as the "Landfill Vacuum Source" pulls landfill gas (LFG) into the gas processing system. The control system allows the proper vacuum set point to be maintained to maximize the methane production. The gas enters through the first of two gas scrubbers, designed to reduce H2S and siloxanes. The fluid in this scrubber is regenerated and reused by the system. A second scrubber is shown on the discharge side of a vacuum blower, which removes Non-methane organic compounds (NMOC's).

The main compression system has the capability to take the gas pressure from 0 psig to as high as 120 psig. ARC Technologies' gas separation process, shown above, normally operates in the range of 100 psig for proper gas separation. The main advantage of the low compression design is safety and energy consumption.

After the compression stage, water is removed and a final gas-polishing step is used to catch any remaining contaminants.

The pretreated biogas now enters one or more vertical PSA columns. Each PSA column has three sections for processing gas.
The system adjusts the control algorithm to achieve the maximum recovery rate for the product gas. ARC Technologies' design allows for a 3 to 1 turn down ratio in regards to plant inlet feedstock flow. The plant's design allows for additional capacity with the addition of vertical columns.

The PSA column has a second product port, which, when used, will deliver product feed gas for turbine, engine and CNG use with very little pressure drop (loss). For the past two years ARC has been successfully operating a system on a Waste Management landfill and injecting high quality gas into the pipeline.


Benefits

Turnkey installation

When you buy a system from ARC Technologies, you will be dealing with only one manufacturer who will take care of all the complex issues of a project this size. No matter if you are a landfill owner or a developer, ARC Technologies is capable of completing all phases of the project such as:


ARC Technologies High BTU PSA system located at the Seminole Road Landfill near Atlanta, Georgia

ARC Technologies High BTU PSA Unit located on Waste Management's South Hills Landfill

Complete -- ready to run

Complete -- ready to run

ARC is the leader in process technology for pretreatment and total treatment of waste gas.  We offer competitive pricing, high process efficiency, low operating costs and reliability that are second to none.  Whether you are cleaning the gas to enhance your turbines reliability, producing vehicle fuel or looking to enter the pipeline, there is only one company who can meet your needs.  The ARC process stands alone in its ability to clean waste gases cost effectively and efficiently utilizing proven technology at a competitive price.

Please feel free to contact us today to visit our operating plant or to discuss your project.

Phone: (724) 722-7066
FAX: (724) 722-7068
Email: ssiegel@controlledgas.com

ARC Technologies Corp.
P.O. Box 485
226 Lumber Street
Yukon, PA 15698-0485

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ARC Technologies is granted US Patent US8568512.