What is Sulphur Recovery Unit SRU

 

A sulfur recovery unit (SRU) is an essential component of many oil and gas processing facilities. It is responsible for converting hydrogen sulfide (H2S) into elemental sulfur, which can then be sold or utilized for various purposes. This process not only helps in the production of useful products, but also eliminates the emission of harmful gases into the atmosphere.

The SRU process involves a series of steps, which typically include the following:

Acid gas removal: Before entering the SRU, the feed gas must be treated to remove contaminants such as carbon dioxide and water. This is done using an acid gas removal unit, which typically employs an amine-based solvent to absorb these impurities.

Thermal oxidation: Once the acid gas has been treated, it is then fed into the thermal oxidizer, where it is burned with air or oxygen to produce sulfur dioxide (SO2) and water vapor.

Catalytic conversion: The SO2 produced in the thermal oxidizer is then passed through a series of catalytic reactors, where it is reacted with a reducing agent such as hydrogen gas to form elemental sulfur.

Sulfur recovery: The elemental sulfur is then separated from the reaction products and purified to produce a high-quality sulfur product.

The design and operation of an SRU depend on several factors, including the composition and quantity of the feed gas, the desired sulfur recovery rate, and the local environmental regulations. However, there are several key components that are common to most SRUs, which are discussed below.

Thermal oxidizer: The thermal oxidizer is typically the first unit in the SRU process. It is responsible for converting H2S to SO2 through combustion with air or oxygen. The combustion reaction releases a significant amount of heat, which can be used to generate steam or provide heat for other processes.

Waste heat boiler: The waste heat boiler is used to recover the heat generated by the thermal oxidizer. The recovered heat is typically used to generate steam, which can be used for various purposes within the facility.

Catalytic reactors: The catalytic reactors are typically used to convert SO2 to elemental sulfur. These reactors contain catalysts such as alumina, which promote the reaction between SO2 and a reducing agent such as hydrogen gas.

Condensers: The condensers are used to cool and condense the reaction products from the catalytic reactors. This allows the elemental sulfur to be separated from the other reaction products and purified.

Tail gas treatment unit: The tail gas treatment unit is responsible for removing any remaining H2S or SO2 from the tail gas stream before it is released into the atmosphere. This is typically done using a series of scrubbers, which absorb the sulfur compounds using a solvent.

In addition to these key components, there are several other auxiliary systems that are required for the safe and efficient operation of an SRU. These may include a flare system, which is used to burn off excess gas during startup or shutdown, and a sulfur degassing system, which is used to remove any residual H2S or SO2 from the sulfur product.

Overall, the SRU is a critical component of many oil and gas processing facilities. It not only helps to reduce the emission of harmful gases into the environment, but also produces a valuable sulfur product that can be sold or utilized for various purposes. The design and operation of an SRU must be carefully planned to ensure that it meets the desired sulfur recovery rate, complies with local environmental regulations, and operates safely and efficiently.