CO strip gas
CO compression
CO liquifaction
CO product
COS/HCN unit
AGR
TGTU Hydrogenation & hydrolysis section
SWS & condensate stripper
TGU compressor
SRU with O
Treated water
Liquid sulphur
Figure 1 Configuration of the project for major units
process condensate stripper and NH 3 stripper. The first treatment step is the removal of sour gases and volatile components in the RATE process condensate stripper. The liquid phase of the process condensate flash drum is preheated and fed to the stripper column in-between the upper and middle packing. The process condensate stripper column consists of two sections. In the upper section, CO 2 strip gas is utilised to remove H 2 S and to minimise stripping of NH 3 . In the lower section, volatile components and CO 2 are removed by means of uprising steam. Additionally, any dissolved carbonates are thermally decomposed. The stripped water is routed to the NH 3 stripper where NH 3 is removed and mixed with H 2 S from another stripper and then routed to the SRU. As described above, the design comprises COS/ HCN hydrolysis, however there is still some HCN and COS not fully hydrolysed, which flows to the AGRU and eventually reaches the SRU. HCN can be washed as well as combusted in the reaction furnace, and we provided an additional feature in the TGU to hydrolyse the remaining COS. Oxygen enrichment technology There are a number of units involved in this plant, including the SRU, which require oxygen enrichment. In gas plants and refineries, oxygen enrichment technologies are used to expand sulphur recovery capacity or reduce the number of trains. Oxygen enrichment raises the flame temperature by eliminating the diluent effect of nitrogen in the air. An economical source of oxygen is the key in this case. However, in waste recovery or waste management plants, the temperature for sulphur recovery is raised to destroy impurities that enter
regarding the design of the SRU and the acid gas removal unit (AGRU) due to the different feed compositions and impurities in these units. The waste management plants require a quench system, COS /hydrogen cyanide (HCN) hydrolysis, AGRU, and CO 2 removal, as well as wastewater treatment with a SWS, SRU, and another hydrolysis unit. Here a brief description of the project would help in understanding the impacts on the SRU design. Figure 1 represents the configuration of the project for major units. In the COS/HCN hydrolysis section, CO and HCN will be catalytically converted to H 2 S, CO 2 , NH 3 , and H 2 O, which could be further removed from this plant. The conversion is described in the following hydrolysis reactions: COS + H 2 O H 2 S + CO 2 HCN + H 2 O NH 3 + CO 2 In the CO shift reactor, CO is converted to H 2 according to the water gas reaction: CO + H 2 O H 2 + CO 2 The gas stream from the hydrolysis section flows to the AGRU where a physical solvent, such as Selexol or similar, is used. In the AGRU, the treated gas containing high CO 2 is sent to the RATE CO 2 liquefaction unit to purify CO 2 further as the product. The acid gas stream from the AGRU is sent to the SRU. The RATE process condensate stripper is proprietary as it uses CO 2 as the stripping gas to strip H 2 S. This design is unique to this application. The SWS and condensate stripper comprises two separate stripper columns: the
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