Removal sulfur from natural gas

Natural gas is used by millions to heat their homes and businesses, cook their food, and even fuel some vehicles. These applications as well as others have caused the use of natural gas to increase 35% over the last decade and demand is expected to increase 53% by 2025. Natural gas contains many impurities such as hydrogen sulfide (H2S) which must be reduced to acceptable levels before the gas is suitable for use. The term ‘sour’ is used in the petroleum industry to describe a fluid contaminated with H2S or acid-labile salts of sulfide or bisulfide. Some of the problems presented by sulfides include: human health risk, environmental compliance, toxicity, corrosion, reduced efficiency of fluid handling equipment, reduced well production, offensive odor, reduced value of products, and increased operation costs.  33% of produced gas and 50% of reserve gas is subquality meaning it contains high levels of impurities2. The most common problem in the gas industry is the removal and disposal of H2S. The toxicity and corrosive properties of H2S dictate stringent control of its release into the environment and contact of aqueous solutions of H2S with iron and steel as in tanks, piping, valves, and pumps.

methane is the main component of natural gas but not the only one. In fact in natural gas are usually present also higher alkanes (ethane, propane, butane, and pentanes), water, nitrogen carbon dioxide and sulphur containing molecules.

Sour gas constituents in natural gas, such as hydrogen sulfide (H2S), create special challenges when removal is required to meet final product specifications. Depending upon the concentration, handling of the H2S often requires special materials of construction and safety procedures. In addition, the technologies typically used to remove H2S from natural gas are both complex and expensive.

Traditionally natural gas treatment for sulphur removal is done with Claus/amine based scavenging or technology (dry or wet). In the past decades this hasn't changed much, event though the needs of the market have shifted. Today smaller (shale) multi-well gas fields in isolated locations, gas sources with relatively low H2S content are quite common.

 

A process for removing hydrogen sulfide from crude petroleum, which comprises contacting the crude petroleum to be freed from hydrogen sulfide with a stripping gas for removing hydrogen sulfide in a hydrogen sulfide stripping column, supplying the spent stripping gas now containing the thus stripped hydrogen sulfide to a hydrogen sulfide absorbing tower, separating the stripping gas from hydrogen sulfide in said absorbing tower by contacting the gas with a hydrogen sulfide absorbing agent to absorb hydrogen sulfide therein and returning the so refreshed hydrogen sulfide stripping gas now freed from hydrogen sulfide to said hydrogen sulfide stripping column under compression at a superatmospheric pressure in order to effect recirculation of the gas.