Gas Scrubbers for Natural Gas Generators
Gas scrubbers provide a way to cleanse wellhead natural gas, a byproduct of oil & gas wells, so that it can be used to power a generator. Before gas scrubbers, natural gas that was produced at oil & gas wells was considered unusable and was flared off. Now, gas scrubbers allow oil & gas companies to use this natural gas to power their on-site natural gas generators. Gas scrubbers help well operators save time and money compared to using diesel generators that require fuel to be transported to the remote oil well site.
Unprocessed natural gas, known as sour gas, contains more than 5.7 milligrams of hydrogen sulfide per cubic meter. If these contaminants are not removed, they can damage and corrode your natural gas generator engine and downstream equipment. The cost to repair or replace this equipment can turn a profitable well into an unprofitable well overnight.
Solid particles in the natural gas fuel are the most damaging impurities of wellhead natural gas. If not properly treated, not only can they cause damage to your equipment, they can also increase emissions and void the generators EPA emission certification.
How Wellhead Gas Scrubbers Work
There are three parts to the process of cleaning wellhead gas so that it can be used in a natural gas powered generator.
- Droplet Separation
Gas scrubbers and water separators are used as a pre-treatment for natural gas. This means that they are placed between the wellhead gas supply and the generator fuel inlet to remove contaminants from the natural gas before it enters the generator.
The first part of the gas scrubbing process involves removing water and oil condensates from the wet gas. Depending of the location, both gas scrubbers and heaters may be used to achieve this. Heaters are used to raise the temperature of the gas to prevent methane hydrate from forming. The gas scrubber then removes contaminants such as water, natural gas liquids sulfur and carbon dioxide.
The second part of the process removes water vapor by either the use of a dehydrating agent, or by condensing and collecting the water vapor.
Commonly used dehydration agents include diethylene glycol or triethylene glycol. These agents are introduced to the gas steam and absorb the water particles. This makes them heavier and they sink to the bottom of a collection vessel.
Solid desiccant dehydration can also be used. In this method, two towers are filled with either silica gel or activated alumina and the wet gas is passed through the towers from top to bottom. As the wet gas passes through the desiccant material, water is absorbed and the dry gas exits at the bottom of the tower.
Wellhead natural gas contain large amounts of sulfur and carbon dioxide. These contaminants must be removed before the natural gas is used in your generator. This process is similar to glycol dehydration. Natural gas is pushed through a tower containing an amine solution that has an affinity for sulfur. Solid desiccants like iron sponges can also be used.