The solvating ability of Novolyte's glymes for the acidic gases, polar and non-polar compounds, together with their chemical stability and their availability at low cost in a wide range of boiling points permits the higher molecular weight glymes to be used in a wide variety of processes for gas purification. These systems work very simply by countercurrent flowing the gases and the glymes at ambient conditions.
Polyglyme has a high capacity to absorb acid gases under pressure. The absorbed gases boil off when the pressure is relieved. The cost of operation is less than when amine scrubbing is employed, since the amine must be heated to release the acid gases. In addition, Polyglyme is chemically inert, has a low vapor pressure, and allows many cycles to be achieved. Some examples follow:
- Acidic gases, such as carbon dioxide and hydrogen sulfide, can be removed from natural gas or ammonia synthesis gas feed stocks by pressure scrubbing with Polyglyme.
- Hydrogen sulfide can be removed from varying feed gases by absorption in a solvent containing a glyme. Reaction with sulfur dioxide then yields water and sulfur. Sulfur has a very high solubility in the glymes. By adjusting solvent composition and conditions, the process can be made applicable to natural gas, synthesis gas, or tail gas from a Claus plant.
- Hydrogen can be recovered from the effluent gases of hydrogenation and hydrocracking facilities by scrubbing the gas with a mixture of glymes and isopropanolamine. Light hydrocarbons, carbon dioxide, hydrogen sulfide, mercaptan, and water are removed from the effluent gas and the purified hydrogen is recycled. The absorbed contaminants are removed from the solvent by flash evaporation and refrigeration. The organic amine salts can be decomposed to acidic gases and amine by heating the solvent after flash evaporation. The solvent can then be recycled.
- Natural gas can be treated to remove ethane and heavier hydrocarbons, to remove water, or to remove the acidic gases (H2S, CO2, COS, RSH, CS2). Glymes should be efficient at removing carbon dioxide, hydrogen sulfide and water from gas generated by anerobic digestion of refuse or sewerage to yield purified methane.
- Water, methanol, and formic acid can be removed from formaldehyde vapor.
- Polyglyme is very selective for H2S. Thus it is used at several hundred PSI and 30-70C for removing H2S to pipeline-quality levels (<4-10ppm) from natural gas.
| Relative Solubility of Acid Gases in Polyglyme |
| Methane |
1.0 |
| CO2 |
15 |
| H2S |
137 |
| SO2 |
1400 |
| H2O |
11,000 |