GPE in association with Schmack Carbotech GmbH, Germany engineer and delivers gas plants and skids which separate, clean and purify some of the dirtiest gases. Stringent product gas specifications are achieved using both wet and dry processes such as caustic wash, pressure swing adsorption, chemisorption, filtration, and separation.

Bulk removal, as well as fine separation with optimized recoveries, are ensured due to proper selection and combination of processes. Application in a wide variety of sectors such as steel, biogas and general industry.

Separation and Purification

PSA Plants

GPE designs and supplies PSA plants for extraction of hydrogen, nitrogen, carbon dioxide and methane from various feed sources, for a wide range of flow rates and product purities. Optional process design and execution supervision by Schmack Carbotech.

Various Pressure Swing Adsorption (PSA) / Vacuum Pressure Swing Adsorption (VPSA) processes are offered for gas separation and purification.

Nitrogen Hydrogen Methane Carbon Dioxide
Feed Air


The nitrogen plants consist oftwo towers operating on pressure swing adsorption process. Purified compressed air is passed through one tower whereinoxygen is adsorbed and the outlet gas contains high purity nitrogen. A portion of this nitrogen is used to regenerate the other tower which is in the regeneration cycle.The outlet gas from the regenerating tower is then vented into the atmosphere with 30-35% oxygen (by volume) content. The typical cycle time for the PSA process is 1 + 1 minute and achieved using specially designed change over valves.


The PSA hydrogen-unit consists of four or more adsorption towers. Each of these towers passes subsequently through the stages of pressure build up, adsorption, and regeneration. By this, a continuous supply of product gas can be achieved. The pressure build-up is carried out in one or more steps. The tower in adsorption is switched over to regeneration. During this step, hydrogen-enriched gas flows to another tower for the next adsorption step.

The remaining part of the pressure build-up is done with product gas. In the subsequent production step, the feed gas is passed through the adsorption tower and hydrogen with very high purity leaves the tower. The regeneration is also done in several steps.

After pressure equalization with the previously regenerated adsorption tower, the present adsorption tower is depressurized. This is followed by a purge step with a counter-current flow of hydrogen. In case there is a high concentration of heavy hydrocarbons in the feed gas, a pre-filter system is integrated into the PSA-process.


Pressure swing adsorption systemscan be used for the production of methane from a number of feed gases such as biogas from digesters, biogas from sewage treatment plants, biogas from liquid manure towers, landfill gases and coal bed methane.In case of feed gases with carbon dioxide as the main component to be removed, methane is produced at line pressure. Whereas in case the main components to be removed are nitrogen and oxygen, methane is produced at atmospheric pressure (during regeneration). For feed gases with equal quantities of carbon dioxide, nitrogen and oxygen, a two stage process is used.Methane of purity upto 99 % can be produced using the PSA process.

The methane production units generally consist of four adsorbers, each of which passes through three stages-pressure build up, adsorption, and regeneration. This configuration ensures a continuous flow of product gas.

Carbon Dioxide

The PSA process is especially suitable for the production of carbon dioxide since carbon dioxide is adsorbed to a higher extent as compared to other gases such as nitrogen, hydrogen, oxygen, methane orcarbon monoxide. The PSA plants for carbon dioxide recovery generally consist of multiple beds which are sequentially passed through the process steps of pressure build-up, adsorption and regeneration. These plants operate at adsorption pressures of 1.1 to 1.5 bar (g) and desorption pressures below 200 mbar (g). The feed gas for these units can be any carbon-dioxide rich gas.

Combined Plants

Cokeoven gas desulphurization & hydrogen generation is required as utilities for continuous annealing lines of integrated steel plants. Combined plants with caustic wash, adsorption by activated carbon, gas boosting, chemisorption & pressure swing adsorption are provided.

GPE also offers combined process plants including absorption, condensation, sacrificial adsorption, temperature swing adsorption, pressure swing adsorption and distillation. These packages are custom built based on the application, composition of input gases, output parameters required, capital and operating costs etc. Some examples are provided here.

Biogas up-gradation plant

This combined process package is used for the removal of hydrogen sulphide, carbon dioxide and other impurities from biogas. The biogas is first fed into a caustic wash tower, where the bulk of the hydrogen sulphide is chemically converted using caustic soda. The biogas is then compressed and passed through a specially processed adsorbent to remove the balance hydrogen sulphide, down to less than 5 ppm. Then the compressed gas is fed into a methane PSA to produce 99% pure methane, where the other impurities are removed. This package described here for biogas up-gradation can also be used for landfill gas and coal bed methane.

Coke oven gas cleaning plant

This combined process package is used for the removal of tar, naphthalene, ammonia and hydrogen sulphide from coke-oven gas. From the cleaned gas, a stream is taken out to produce hydrogen for batch annealing furnace. The coke oven gas is first fed into a caustic wash tower, where the bulk of the hydrogen sulphide is chemically converted using caustic soda. The gas then passes through adsorbent beds, wherein tar and naphthalene are removed. The gas is then passed through a specially processed adsorbent to remove the balance hydrogen sulphide, down to less than 5 ppm.

The process gas is then compressed and fed to a hydrogen PSA to produce 99.99% pure hydrogen. This package is used in steel plants that operate a cold rolling mill and have coke batteries.

For other combined plants please contact us for further details.

Carbon Adsorption & VOC

Use of specialized activated carbon sourced from Europe & USA, in extremely critical applications such as removal of volatile organic compounds, toxic gases, organic odor creators and hazardous inorganic pollutants from gas streams.

Carbon Adsorption Plants

GPE offers vapor phase activated carbon systems for the removal of volatile organic compounds such as hydrocarbons, solvents, toxic gases and organic based odors. In addition, we design chemically impregnated activated carbon systems to control inorganic pollutants such as hydrogen sulfide, mercaptan, mercury, radon, dioxin, ammonia, amine, arsine, phosphine, aldehydes, radioactive Iodine, radioactive methyl iodide, acid gases (HCL,SO2,HF,HCN), nitrogen oxide and many more. The most common applications of activated carbon are for process gas and off-gases, tank vent emissions, work area air purification, and odor control, either within the plant or related to plant exhausts. We also recommend the use of activated carbon for hazardous waste remediation, to treat off-gases from air strippers & soil vapor extraction remediation projects and to handle toxic/hazardous air pollutants.

VOC Recovery Systems

Controlling volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions are achieved by various means. We offer the following options:

  • Activated Carbon for Vapour Phase Adsorption and Recovery.
  • Activated Carbon for VOC removal from water with Air Stripper. Recovery can also be done.
  • Condensation for Vapour Phase and Recovery.
  • Particulate filters.

Vapour Phase Adsorption

The design of an adsorber system depends on the chemical characteristics of the VOC or HAP being recovered, the physical properties of the inlet stream (temperature pressure and gas flow) and the physical properties of the adsorbent. Physical adsorption is an exothermic process that is most efficient within a narrow range of temperature and pressure.

Vapour Phase Condensation

Separation via condensation can be achieved by increasing the system pressure at a given temperature (compression condensation) or by lowering the temperature at a constant pressure (refrigerated condensation). In a two-component system where one of the components is non-condensable (e.g., air), condensation occurs at the dew point (saturation) when the partial pressure of the volatile compound is equal to its vapor pressure.