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How does biogas upgrading process work?

Biogas is a mixture of CH4, CO2, O2, N2 and other trace gases. It is produced from anaerobic digestion of food waste, animal manure, landfills, and sewage. After pre-treatment and purification steps (removing H2S, VOCs, Siloxanes, Ammonia and H2O), biogas is upgraded to biomethane, a renewable substitute for natural gas.

From Biogas to Biomethane – Renewable Natural Gas

1

H2S Scavenger

A desulpherization unit for H2S removal by activated carbon, lead-lag configuration.
2

Compressor Room/ Container

Biogas low pressure de-watering package, feed biogas blower package, biogas compressor package, regeneration vacuum pumps, instrument air.
3

Buffer Tanks

PSA inlet, recycle, biomethane, and exhaust gas buffer tanks to facilitate the gas balance.
4

PSA System

Nine vessel, fast cycle, single rotary valve combined with high efficiency regenerative adsorbent.
5

Control Room

Fully automated control of biogas flow and composition to optimize product gas recovery.
6

Water Chiller Package

A dehumidifier/ compact cooler with heat exchanger.

Our biogas upgrading process

Pre-treatment Compression CO2, N2 and O2 Removal

Biogas Plant Components

Equipement Included

1

H2S Scavenger. A desulpherization unit for H2S removal by activated carbon, lead-lag configuration.

2

Compressor Room/ Container. Biogas low pressure de-watering package, feed biogas blower package, biogas compressor package, regeneration vacuum pumps, instrument air.

3

Buffer Tanks. PSA inlet, recycle, biomethane, and exhaust gas buffer tanks to facilitate the gas balance.

4

PSA System. Nine vessel, fast cycle, single rotary valve combined with high efficiency regenerative adsorbent.

5

Control Room. Fully automated control of biogas flow and composition to optimize product gas recovery.

6

Water Chiller Package. A dehumidifier/ compact cooler with heat exchanger.

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How does a PSA work?

Steam reforming and other hydrogen-containing off-gas streams typically contain gases such as water vapour, carbon dioxide, carbon monoxide, methane, nitrogen and other trace gases.

Xebec’s PSA H-Series remove these contaminants in the adsorber bed at feed pressure. Virtually pure hydrogen passes through the bed with minimal loss in pressure. The impurities are desorbed from the bed as the pressure is reduced to the PSA exhaust pressure.

This PSA process is completely reversible and repeats to provide continuous flows, splitting the mixed-feed flow into purified product and exhaust flows. The exhaust gas is typically used as the primary fuel input to the hydrogen-generating reforming process or other fuel, making it a very efficient, integrated process.

Absorption Process

PSA system separates CO2, CO, CH4, N2, H2O from SMR, ATR, MeOH
reformer gas and other H2 enriched streams such as chemical off gas.

Our PSA systems

Xebec’s PSA unit consists of nine identical beds filled with high-efficiency adsorbent. Beds are connected via a single proprietary rotary valve. All the steps occur via the rotary valve.

The valve rotation speed controls the product purity and recovery. Feed gas enters the bottom of each bed and the product leaves from the top of the bed, while the separated contaminants are removed in an exhaust stream from the bottom of the bed.

Our rotary valves: Xebec PSA has one rotary valve (feed valve) connected to the bottom of each bed and one rotary valve (product valve) connected to the top of each bed. Feed gas is allowed to flow through a passage in the feed valve to at least one bed while, at the same time, purified product gas is allowed to flow from the bed through the product valve passage to the product line. Other flows are similarly connected through the rotary valve for exhaust, purge, equalizations, etc.

As the two valves rotate together, gas flows are gradually switched from one bed to the next to produce the efficient Xebec PSA cycle. Although this cycle is much faster than conventional PSAs (with the inherent advantages), this is still a very slow rotational speed of 1.0 to 0.3 RPM (Rotations Per Minute)

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How does a TSA work?

Temperature Swing Adsorption (TSA)

TSA uses temperature in order to regenerate the adsorbent. At low temperatures, adsorbents can retain significant amounts of water. At temperatures above 200°C, however, adsorbents hold almost no water. By swinging the temperature from low to high, it is possible to adsorb large quantities of moisture at low temperature, such as 40°C, and release it at high temperature.

TSA TECHNOLOGY SCHEMATIC