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Applications
The Sulfinol process is a regenerative process developed to reduce H2S, CO2, COS and mercaptans from gases. The sulfur compounds in the product gas can be reduced to low ppm levels. This process has been developed specifically for treating large quantities of gas, such as natural gas, which are available at elevated pressures. The Sulfinol process is unique in the class of absorption processes because it uses a mixture of solvents, which allows it to behave as both a chemical and a physical absorption process. The solvent is composed of Sulfolane, DIPA or MDEA and water. The acid gas loading of the Sulfinol solvent is higher and the energy required for its regeneration is lower than those of purely chemical solvents. At the same time it has the advantage over purely physical solvents that severe product specifications can be met more easily and co-absorption of hydrocarbons is relatively low. For selective absorpton of H2S, COS and mercaptans, while co-absorbing only part of the CO2, the Sulfinol-M process is used. Deep removal of CO2 in LNG plants is another application. Integration of gas treating with the SCOT solvent system is an option.

Description
The feed gas is contacted counter-currently in an absorption column with the Sulfinol solvent. The regenerated solvent is introduced at the top of the absorber. The sulfur compounds loaded solvent (rich solvent) is heated by heat exchange with the regenerated solvent and is fed back to the regenerator where it is further heated and freed of the acid gases with steam.

The acid gases removed from the solvent in the regenerator are cooled with air or water, so that the major part of the water vapor they contain is condensed. The sour condensate is reintroduced into the system as a reflux. The acid gas is passed to the sulfur recovery plant (Claus plant) in which elemental sulfur is recovered.

The gas feed from the hydrotreating units enter the bottom section of the absorber column. The regenerated and cooled lean solvent enters the column at the top. The flow of the lean solvent to the absorber is flow-controlled. The treated gas passes from the absorber to the treated gas knock-out drum, where any entrained solvent is separated from the gas. The rich solvent containing H2S leaves the bottom of the absorber under level control and is pumped by the rich solvent pump towards the lean/rich heat exchanger. In the lean/rich heat exchanger the rich solvent is heated by the hot lean solvent from the regenerator. Regeneration takes place in the regenerator column, which is equipped with a stripping section and one wash section in the top. The rich solvent from the lean/rich heat exchanger enters the regenerator below the wash sections and is stripped counter-currently with steam. The steam is generated in the reboiler. Low-pressure steam is used as heating medium. The top gas from the regenerator is cooled in the overhead condenser. Practically all steam present in the overhead gas is condensed. The acid gas and condensate are passed to the reflux drum from which the condensate is pumped back to the top of the regenerator by a reflux pump, in order to remove entrained solvent from the overhead gas. The acid gas, which also contains some hydrocarbons, is fed to the Sulfur Recovery Unit under pressure control. The hot lean solvent leaves the bottom of the regenerator and is pumped to the lean/rich heat exchanger by the lean solvent pump. The lean solvent is further cooled in the lean solvent cooler. Then the cooled lean solvent is sent to the absorber. The application of a flash vessel is optional and the use depends on the amount of heavier hydrocarbons present in the feed gas. The application of a reclaimer vessel is optional and the use depends on the amount of non-regenerative compounds in the solvent.

Operating Conditions
Very wide ranges of treating pressures and contaminant concentrations can be accommodated. Natural gas pipeline specifications are easily met. Removal of organic sulfur compounds is usually accomplished by the solvent circulations as set by H2S and CO2. In LNG plants a specification of 50 ppm CO2 prior to liquefaction is attained without difficulty.

Utilities
The utility consumption varies widely with feed gas composition and product gas specification

Features
   Removal of H2S, COS and organic sulfur to natural gas pipeline specification.
   Low steam consumption and solvent circulation.
   Low corrosion rates.
   Selective removal of H2S in some natural gas applications.
   Smaller equipment due to low foaming tendency.
   High on-stream factor.


References
More than 200 Sulfinol units ranging in capacity from 10.000 Nm3/d to 32.000.000 Nm3/d are in operation throughout the world, demonstrating the reliability of the process.

Licensor
Jacobs Nederland B.V., Leiden, The Netherlands, is one of the three authorized licensors on behalf of Shell Research Ltd. since 1981

Streams to be Treated
Contaminants Removed
Natural gases
Oil and coal gasification
Natural gases
LNG feedstock, hydrogen manufacture synthesis gas
 H2S, CO2, COS, RSH + organic S
H2S, COS (H2S is selectively removed)
H2S, CO2 (partly)
CO2
 

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