Decarbonisation Technology - February 2022 Issue

oxygen enrichment in the SRU allows for a smaller TGU, and hence a lower capital cost and better performance. It is obvious that oxygen enrichment reduces the plot area required for SRU capacity expansion. For operating facilities with limited plot space, oxygen enrichment may be the only viable option. Lower capital costs are offset by a higher operating cost due to the cost of oxygen, but without it, it is not possible to design these units. Figure 5 represents the TGU with hydrogenation and hydrolysis reactors and the quench system. Conclusions This article focuses on the recoveries of H 2 S and CO 2 from waste streams using advanced technologies. The AGRU is designed to separate H 2 S and CO 2 , where H 2 S is routed to the SRU to produce sulphur as a product. The CO 2 is then compressed so it can be used in different applications such as stripping gas or routed to the CO 2 liquefaction unit for other uses. The amine section of the TGU is eliminated; the quench overhead is recycled back to the AGRU, where the remaining H 2 S and CO 2 are removed through three different towers. Even though there is a COS hydrolysis unit located upstream of the AGR, RATE has included a second hydrolysis reactor after the hydrogenation reactor of the TGU to treat the lean acid gas, COS, and CS 2 , which are byproducts

automated double isolation safety blocks and bleed to a safe location (similar to natural gas).  A proper material oxygen line, valve, or any other instrumentation should be selected.  A proper shutdown system should be provided to prevent equipment damage during the oxygen enrichment operation when high temperature occurs. There is no doubt that the presence of oxygen requires operators to exercise additional safety precautions, but operators and designers are gaining more experience in handling oxygen in hydrocarbon-rich environments. The necessary materials, safeguards, and operating procedures for handling oxygen are well defined and understood. Furthermore, the oxygen distribution system will be designed with minimum inventory near combustibles. Figure 4 shows the process flow diagram for the thermal section using 100% oxygen enrichment. The catalytic section is not shown because it is the same as the air operation scheme. The advantages of using oxygen enrichment are to establish a stable combustion temperature where NH 3 can be fully destructed in the reaction furnace burner among other impurities that enter the SRU. As a result, oxygen enrichment will reduce the size of the equipment, lower capital costs, and improve sulphur recovery. Using

Tail gas compressor

Recycle to AGRU

Quench column

Quench water trim cooler

TGU start-up vent ejector

CWR

Tail gas heater

LPS

CWS

MPS

Tail gas from No. 3 condenser

Note 1

To SWS

MPC

Hydrogenation reactor

Hydrolysis reactor

LLPS

Quench water pump

Quench water air cooler

Reactor euent cooler

BFW

Figure 4 Process flow diagram for the thermal section using 100% oxygen enrichment