Decarbonisation Technology - August 2023 Issue

H 2

CO 2

Carbon impact 1

CO 2

Capex 2

Lead time

Down time

Opex 2,3

production

recovery

[gCO 2 eq/MJH 2 ]

KgCO 2 /kgH 2

Nm³/h

Months

80,000

<15.5

0.45

Base

Table 1 Reference case: post-combustion carbon capture – carbon capture efficiency and investment metrics

costs and potentially additional CO₂ emissions (depending on the power source). A second shortcoming is that the system requires a larger plot area which can be undesirable in many brownfield applications where space can be constrained. In addition, for chemistry reasons, the solvent of the post-combustion carbon capture degrades easier than the pre- combustion carbon capture, also yielding higher Opex for solvent replacement costs. The post-combustion capture system can remove 95% of the CO₂ contained in the flue gas stream, and the residual CO₂ emissions at the stack are in the range of 0.45 kg CO₂ per kg of produced H₂. The other key results of this solution are summarised in Table 1 . As previously stated, this is the reference case of the study, and the decarbonisation solutions following this case are all measured relative to this solution. Option 1: BlueSMR+ This option (see Figure 2 ) aims to significantly increase the performance of the existing unit

by introducing a solution that is differentiated by the installation of pre-combustion carbon capture, a gas heated reformer, and a pre- reformer. Hydrogen-rich gas firing will also displace the CO₂ emissions from the combustion side of the process. The pre-reformer and the gas heated reformer are two fixed bed reactors that exploit the ‘waste’ heat available in the hydrogen unit to support the reforming process and reduce the need for fuel firing in the steam reforming furnace. The pre-combustion carbon capture brings significant advantages in terms of investment cost, plot area, and operational expenditure. This is because the system is installed on the syngas stream, where the pressure is in the range of 25 barg, and therefore the concentration of the CO₂ is higher, making separation easier. The equipment is smaller than is needed for the post-combustion carbon capture used for the reference case due to the lower specific volumes of gas that needs to be processed. The solvent has limited degradation, and there is lower electric power consumption as no

Clean ue gas to atmosphere

CO for use or sequestration

Steam reforming

Gas heated reformer

Hydrogen product

Pre-reforming

Shift CO capture PSA

Feed

H enriched fuel gas

Figure 2 Option 1: BlueSMR+ pre-combustion carbon capture

H 2

CO 2

Carbon impact 1

CO 2

Capex 2

Lead time

Down time

Opex 2 , 3

production

recovery

[gCO 2 eq/MJH 2 ]

KgCO 2 /kgH 2

Nm³/h

Months

80,000

<16.5

0.96

Table 2 Option 1: BlueSMR+ pre-combustion carbon capture – carbon capture efficiency and investment metrics