Associated gas is a mixture of gases and various substances that is released from oil well during oil extraction process. In contrast with natural gas, associated gas contains not only methane and ethane but also a considerable quantity of propane, butane and vapours of heavier hydrocarbons.
In Russia, like in any other oil-producing country, associated gas recovery issues have massive ecological significance. Oil and gas industry emissions account for up to 30% of all industrial emissions and 12% of all exhaust emissions. Soot, incomplete hydrocarbon combustion products, carbon monoxide, sulfur dioxide and nitrogen oxide are released into the atmosphere. Gas flaring is the main air contamination source in oil production areas.
According to various estimates 400 thousand tons of hazardous substances — carbon monoxide, nitrogen oxides, hydrocarbons and soot are discharged into the atmosphere as a result of gas flaring. On average 1 ton of produced oil leads to release of 8 kg of hazardous emissions mainly concentrated in oil regions. That is why it is necessary to consider detrimental influence of thermal pollution caused by petroleum gas flares.
Russian Federation Government issued a regulation «On measures aimed at reduction of atmospheric air pollution by gas flaring combustion byproducts» in January 2009. In this situation research on alternative gas recovery methods becomes very actual. Thermocatalytic decomposition is one of the most efficient recovery methods.
Thermocatalytic treatment that ECAT equipment is based on is more efficient than flare systems. No secondary emissions are realeased during thermocatalytic decomposition that is why the equipment is safe for the environment. Modularity and compact sizes of the equipment make it possible to move the it between oil wells.
One of the advantages of this engineering solution is that it is possible to recuperate heat generated during gas recovery and use it for drawing DH water for space heating and formation water heating.
First, associated gas fed into catalytic boiler, flows to burner units which facilitate its preliminary recovery. Then the gas is cooled down to 400°С by means of adding atmosphere air to the flow with the help of centrifugal blower. This temperature is necessary for steady thermocatalyric process — closing stage of associated gas recovery.
Thermocatalytic gas neutralization is based on gas oxidation decomposition to carbon dioxide, water and nitrogen. Pollution components of gas mixture enter into a flameless reaction with oxidizer molecules over catalyst during oxidation process. Reaction final substances — water vapours and carbon dioxide — are safe components.
When associated gas is rich in sulfur-containing substances, it is recommended to remove them from the flow with a chemisorption module. Chemisorption module consists of metal enclosure filled with ECAT brand chemisorbent. Sorbent change rate is determined by operating mode, used sorbent must be treated.
Heat from catalytic boiler can be used for district heating water production and formation fluid heating which has adds economic benefits to associated gas recovery. Heat recovery system (HRS) must be installed as optional equipment. HRS is an optional module installed at the request of the Client. HRS is Gas heated after treatment system and pure cool air (water) from inlet ventilation pass through heat exchanger. Vent gas heat is continuously transferred to inlet pure air (water) through a plate dividing the flows and providing recuperation up to 50%.