Decarbonisation Technology - February 2022 Issue

FC 4111

Acid gas

Total O demand

FY 4141

FC 4102

SWS acid gas

Oxygen burner

Set point

–

Oxygen

Combustion chamber

Set point

FC 4112

Process air

Figure 3 The control system and the burner management system

valuable and cleaner burning gas previously used for EOR, power generation desalination, and industrial usage. Many oil companies use CCUS technologies in tandem with gas conditioning within an overall circular carbon economy policy, taking advantage of the technologies to reduce, recycle, reuse, and remove CO 2 , as well as employing artificial intelligence and big data to reduce emissions by monitoring energy consumption and optimising operations. Design of an SRU using high purity oxygen enrichment must include safety considerations. Two important features are the control and burner management systems to establish a safe environment for the operations team at the facility. Figure 3 represents the control system and the burner management system where oxygen enrichment is added to the design of the SRU. Safety concerns on SRU oxygen enrichment are two-fold: the introduction of oxygen to a new plant area and changes in design and equipment

off and then flows to the hydrolysis reactor (a proprietary design). The outlet of this reactor flows to the quench system. Tail gas is desuperheated in a bed of grid- type packing in the lower section of the column by a circulating water stream pumped by the desuperheater circulating pump. This water is maintained alkaline to protect against any SO 2 breakthrough from the hydrogenation reactor. The desuperheater section is initially filled with a 10 wt% caustic (NaOH) solution. This solution quickly reacts with the CO 2 in the tail gas to form a sodium carbonate/bicarbonate (Na 2 CO 3 / NaHCO 3 ) buffer solution. Any SO 2 that breaks through from the hydrogenation reactor will react with the solution to form sodium sulphite/bisulphite (Na 2 SO 3 / NaHSO 3 ). Periodically, as the carbonate/ bicarbonate is depleted, a portion of the solution is drained to the spent caustic system and replaced by fresh caustic solution. The spent caustic is cooled in the spent caustic cooler and then sent off-plot for disposal. Gases exiting the quench column are normally routed to the Selexol unit through a compressor. Back-up incineration is also provided for normal conditions where the quench overhead flows to the incinerator instead of recycling back to the AGRU. Carbon capture usage and storage (CCUS) is not only an important part of a wide range of critical solutions to mitigate industrial CO 2 emissions and reduce environmental footprint, it also enables

from a conventional air-based SRU. The following safety features should be incorporated into the DCS and burner management systems:

 Oxygen and natural gas should be interlocked so they are not introduced to the burner at the same time.  The oxygen line should be equipped with