Purification of sulfur recovery unit (SRU) tail gas for incineration. Resulf, Resulf-10 and Resulf-MM units are easily retrofitted to existing SRU complexes. They feature a low unit pressure drop and can use the latest specialty solvents to lower energy consumption and maximize flexibility.
Products: Treated vent gas from a Resulf-MM unit typically contains 1,000 ppm H2S and must be incinerated. Treated vent gas from a Resulf unit typically contains less than 150 ppmv H2S and is oxidized in an incinerator before venting to the atmosphere. Vent gas from a Resulf-10 unit has a maximum of 10 ppmv H2S and may not require incineration.
SRU tail gas is heated in the feed heater, then mixed with a reducing gas containing H2. The heated stream passes through the reactor (1), where the SO2, elemental sulfur and other sulfur-containing compounds, such as COS and CS2, are converted to H2S. Hot gas leaving the reactor is cooled in a waste-heat steam generator. The gas is further cooled in a direct contact water cooler (2). The overhead gas stream is fed to the absorber (3).
Lean solvent is also fed to the absorber. The downward flowing solvent contacts the upward flowing gas and absorbs nearly all the H2S and only part of the CO2. Rich solvent is sent to the regenerator (4) where the H2S and CO2 are removed by steam stripping. Acid gas from the regenerator is recycled to the SRU. Lean solvent from the regenerator is cooled and returned to the absorber.
Operating conditions: Resulf units use MDEA or formulated MDEA as a solvent. Resulf-10 units are designed using specialty amines such as formulated MDEA. Resulf units use generic MDEA solvents. Resulf-MM units use amine from the primary amine unit (MEA, DEA or MDEA).
Economics: Plate and frame heat exchangers have been used to reduce capital costs. Modular designs can also be used to reduce capital costs while maintaining critical project schedules. The cost for Resulf-MM is significantly lower than for Resulf or Resulf-10 due to the lower recovery. Key features of the Resulf-MM and Resulf technologies are that they can be inexpensively upgraded.
Supplier: CB&I TPA