Primary Energy Consumption For CO2 Research Articles

Integrated gasification carbon capture plant using molten carbonate fuel cell: An application to a cement industry

This study presents a novel integrated gasification carbon capture plant (IGCCP) as a post-combustion capture for a cement plant with a capacity of 4200 t clinker per day. The IGCCP includes externally reforming molten carbonate fuel cells (MCFC) fueled with syngas generated from the gasification of plastic wastes and produces low-carbon electricity and a CO2 stream for sequestration. The new thermodynamic model of MCFC developed here assesses the impact of syngas composition and cell temperature on the performances of the IGCCP system. An increase in the equivalence ratio (ER) from 0.20 to 1.00 of the gasification process increases the Nernst voltage loss factor from 86 to 132 mV thereby lowering voltage efficiency, but decreases the fuel demand to the IGCCP from 3462 to 2579 GJ/h. The maximum net generation efficiency is estimated to be 31.1% at ER = 0.33. Raising the cell temperature from 600 °C to 700 °C results in a decrease in ohmic voltage loss thereby increasing both voltage and MCFC efficiencies. Since the power generation increases at a higher cell temperature, the net power generation efficiency also increases but the CO2 capture efficiency remains constant (∼93%). The estimated specific primary energy consumption for CO2 avoided and captured are in the range of (−4.5) – (20.9) GJ/tCO2 and (−5.3) – (6.6) GJ/tCO2, respectively. The IGCCP system fueled by plastic wastes could decarbonize the cement plant completely while producing low-carbon electricity with an emission intensity of 87 kgCO2/MWh.

Negative CO2 emissions in the lime production using an indirectly heated carbonate looping process

Lime is an essential raw material for iron and steel production, in construction and agriculture, in civil engineering, in environmental protection, and in manifold chemical manufacturing processes. To address the problem of unavoidable process CO2 emissions associated with the production of lime, efficient capture technologies need to be developed and implemented. The indirectly heated carbonate looping (IHCaL) process is an efficient candidate for this application because it utilizes lime as the sorbent for the CO2 capture. In this work, a retrofit configuration of this process is presented and analyzed for net negative CO2 emissions. This is done considering different fuels that provide the heat required for the regeneration of the sorbent. The different scenarios were simulated with an AspenPlus® model, key performance indicators were calculated, and the process was compared with other post-combustion capture methods. The results show that net negative CO2 emissions as high as −1805 kgCO2/tCaO, calculated with a state-of-the-art coal power plant energy scenario (ηe = 44.2 %; eref,el = 770 kgCO2/MWhel), can be obtained. This represents an equivalent CO2 avoidance of more than 230% with respect to the reference plant without capture (1368 kgCO2/tCaO). A specific primary energy consumption for CO2 avoided (SPECCA) lower than 1.5 MJLHV/kgCO2,av was achieved for the same energy scenario. Particularly promising results can be accomplished when applying fuels with high biogenic fraction and low specific CO2 emissions, such as solid recovered fuels (SRFs) with a high calorific value.

Comparative techno-economic analysis of the integration of MEA-based scrubbing and silica PEI adsorbent-based CO2 capture processes into cement plants

The objective of this work was to perform the techno-economic analysis for the integration of two post-combustion carbon capture technologies into cement plants, namely monoethanolamine (MEA) scrubbing-based and silica-alkoxylated polyethyleneimine (SPEI) adsorbent-based processes. The key performance indicators were investigated, including emission abatement, energy performance, break-even selling price, CO2 capture and avoidance cost. The technical evaluation showed that the conventional MEA and SPEI-based processes required 3.53 GJ/tonne CO2 and 2.36 GJ/tonne CO2 of regeneration energy when achieving 90% of CO2 capture rate, respectively. In addition, the specific primary energy consumption for CO2 avoided was estimated at 6.5 GJ/tonne CO2 for the MEA-based and 4.3 GJ/tonne CO2 for the SPEI-based process. The CO2 capture costs of MEA and SPEI-based processes were estimated at 61.4 and 49.8 €/tonne CO2, respectively. Meanwhile, the CO2 avoidance cost of MEA and SPEI processes were estimated at 84.7 and 62.2 €/tonne CO2 respectively. The economic evaluation indicated that the cost of clinker production was increased by 108% with the integration of the solvent-based MEA-based and 84% for the SPEI-based processes. However, in the case, the maximum heat of 53.9 MWth is recovered from the reference cement plant, the costs of CO2 capture and CO2 avoidance for both the MEA and SPEI-based processes would be reduced. The CO2 capture costs of MEA and SPEI-based processes would decrease to 48.0 and 35.6 €/tonne CO2, respectively. Additionally, the CO2 avoidance costs for the MEA and SPEI-based processes would be reduced to 57.5 and 44.5 €/tonne CO2, respectively.

Solar-driven calcium looping system for carbon capture in cement plants: Process modelling and energy analysis

The cement industry produces around 6–7% of the global anthropogenic CO2 emissions. This sector, therefore, needs to be decarbonized to meet the international goals on greenhouse gas emissions. In a cement plant, however, around 60% of the CO2 emissions are hard-to-abate because they come from the calcination of the raw materials. Carbon capture is thus needed to perform deep decarbonization of the cement production process. Among all the carbon capture technologies proposed in the literature, Calcium looping (CaL) is one of the most promising ones. This work analyses on novel solar-driven CaL process for carbon capture in a cement plant. In the system proposed, the energy required for the CO2 sorbent regeneration is fully supplied by a heliostat field. The performances of the overall system were evaluated through detailed process modelling and energy analyses. Primary energy consumption and CO2 emissions (sum of both direct process emissions and indirect emissions due to electricity consumption) were assessed considering different grid electricity mixes and integration levels (IL) between the carbon capture system and the clinker kiln. We estimate that the integration of a solar-driven CaL in a cement plant could be able to reduce over 90% of the plant CO2 emissions. Furthermore, this solution could potentially decrease the plant fuel consumption thanks to the reuse of the exhausted sorbent in the production process. On the other hand, a large heliostat field will be required to feed energy to the CaL process. Both the carbon intensity of the grid electricity mix and the IL impact on the system energy and carbon balance, as shown by the obtained values for the specific primary energy consumption for CO2 avoided (SPECCA) index. Obtained SPECCA indexes vary between a maximum of 2.17 MJ/kgCO2, obtained for an IL of 20% and grid electricity produced entirely from renewables, and a minimum of 0.57 MJ/kgCO2, estimated for an IL of 80% and grid electricity produced from state-of-the-art pulverized coal.

Integrated Calcium Looping System with Circulating Fluidized Bed Reactors for Low CO2 Emission Cement Plants

In this work, a Calcium Looping (CaL) configuration for cement plants using two interconnected circulating fluidized bed (CFB) reactors integrated into the clinker production process, is investigated. In the proposed system, the oxy-fired CFB calciner has a dual task: (i) calcining the finer fraction of the raw meal to feed the rotary kiln of the plant and (ii) calcining the coarser fed raw meal fraction, so as to recirculate part of it to the carbonator to capture CO2 from the flue gases of the kiln. Such arrangement also exploits the known tendency of limestone materials to experience intense attrition and fragmentation under the severe calcination conditions in the oxyfired CFB calciner, so that the calciner also performs the task of an auxiliary mill. The techno-economic study conducted in this work has been carried out by analysing different levels of fragmentation of the raw material, consistent with experimental results from the TRL7 la Pereda CaL pilot plant. Two different configurations were analysed: the first, in which limestone with a larger particle size than the correctives is fed, to be used in CFB reactors; the second, in which no separation of limestone from other solid species is possible and all raw meal is used as CO2-sorbent in the CaL system. The benefits of this approach are confirmed by the estimated specific primary energy consumption for CO2 avoided (SPECCA) of 2.8-3.0 MJLHV/kgCO2 when pure limestone is used in the carbonator and of 3.5-4.6 MJLHV/kgCO2 when the raw meal is used as sorbent. The economic analysis indicates the competitiveness of the novel proposed process compared to other CaL systems, resulting in a cost of CO2 avoided (CCA) between 49.2 to 57.9 €/tCO2, excluding costs for CO2 transport and storage.

Integrated Calcium Looping System with Circulating Fluidized Bed Reactors for Low CO2 Emission Cement Plants

This article presents the techno-economic evaluation of a new integrated CFB Calcium Looping (CaL) configuration for cement plants, using well established design parameters that have been tested up to TRL7 in la Pereda CaL pilot. The system is based on the use in the Calcium looping (CaL) process of two interconnected circulating fluidized bed (CFB) reactors integrated into the clinker production process. The system uses the raw material entering the cement plant as CO2 sorbent. All the raw meal is processed in the CaL calciner, which has the dual task of (i) preparing the raw meal for the burning phases in the rotary kiln and (ii) preparing the sorbent for CO2 capture in the carbonator. As a result of the severe calcination conditions in the system, part of the raw meal is fragmented and can be used directly in the rotary kiln, thus also performing the task of an auxiliary mill. The study conducted was carried out by analysing different levels of fragmentation of the raw material. The calculated specific primary energy consumption for CO2 avoided (SPECCA) is 3.29 MJLHV/kgCO2 if a medium level of fragmentation is considered. In order to further improve energy performance, it was decided to study a variant of the system in which limestone and correctives are fed with two different particle sizes in the calciner. In this way, it is possible to have a once through process, to reduce the residence time of the particles in the calciner and, therefore, reduce the impact of possible parasitic reactions, such as the belite formation. Adopting the once through process, the SPECCA reduces to 2.76 MJLHV/kgCO2. Finally, the economic analysis highlights the competitiveness of the processes studied compared to other CaL systems showing a cost of CO2 avoided (CCA) between 49.0 and 54.6 €/tCO2.

Unlocking the potential of pulp and paper industry to achieve carbon-negative emissions via calcium looping retrofit

Pulp and paper is considered to be the fourth most energy-intensive industry (EII) worldwide. However, as most of the CO2 emissions are of biomass origin, this sector has the potential to become a carbon-negative industry. This study proposes a new concept for conversion of the pulp and paper industry to carbon negative that relies on the inherent CO2 capture capability of the Kraft process. The techno-economic performance of the proposed carbon-negative system, based on calcium looping (CaL) retrofitted to a pulp and paper plant, was evaluated. The effect of CaL design specifications and cost assumptions on the thermodynamic and economic performance were evaluated. Under the initial design assumptions, the reference pulp and paper plant was shown to turn from electricity importer to electricity exporter with the cost of CO2 avoided equal to 39.0 €/tCO2. The parametric study showed that an increase in the fresh limestone make-up rate resulted in a linear increase of the specific primary energy consumption for CO2 avoided (SPECCA) and a reduction in the amount of electricity exported to the electric grid. This translates into an increase in the price of pulp and newsprint, and the cost of CO2 avoided. This study has also demonstrated that the pulp and paper industry has high potential to become carbon negative. It has been shown that carbon capture and storage would become economically viable in this industry if the negative CO2 emissions are recognised and a negative CO2 emissions credit of at least 41.8 €/tCO2 is implemented.

Integration of LNG Regasification Process in Natural Gas-Fired Power System with Oxy-Fuel Combustion

Oxy-fuel combustion power systems can utilize the cold energy released during the liquefied natural gas (LNG) regasification to reduce the power consumption of CO2 capture, but the specific LNG cold energy consumption of CO2 capture is still too large. To recover more CO2 with the limited LNG cold energy at a low energy cost, a novel natural gas-fired oxy-fuel power system with the cascade utilization of LNG cold energy is proposed in this work, where the LNG cold energy could be sequentially utilized in the air separation unit and the CO2 recovery process. The new system is evaluated with the Aspen Plus software. The results show that the net electrical efficiency and the specific primary energy consumption for CO2 avoided (SPECCA) of the new system are comparable to those of the chemical looping combustion cycle, and superior to those of the conventional O2/CO2 cycles. Moreover, the specific LNG needed for CO2 avoided (SLNCC) of the new system is more than 67.2% lower than the existing oxy-fuel power systems utilizing the LNG cold energy. Furthermore, it is found that the O2 purity of 97.0 mol.% and the CO2 capture ratio of 97.0% are optimal conditions, because the SPECCA, the specific exergy consumption for CO2 avoided (SECCA) and the SLNCC are at the minimum of 1.87 $${\rm{G}}{{\rm{J}}_{LHV}} \cdot {{\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}}^{- 1},2.60\,\,{\rm{GJ}} \cdot {{\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}}^{- 1}$$ and $$1.88\,\,{{\rm{t}}_{{\rm{LNG}}}} \cdot {{\rm{t}}_{{\rm{C}}{{\rm{O}}_2}}}^{- 1}$$ , respectively. Meanwhile, the net electrical efficiency and the exergy efficiency of the new system reach 51.51% and 49.23%, respectively.

A high‐efficiency novel IGCC‐OTM carbon capture power plant design

AbstractCoal power plants play an important role in supplying affordable and reliable electricity. It is necessary to develop high‐efficiency and low‐cost carbon capture (CC) technologies to mitigate the associated global warming. Using H2S‐tolerant oxygen transport membranes (OTMs) for hydrogen production and CO2 separation can significantly reduce the energy penalty of CC in integrated gasification combined cycle (IGCC) power plants. We carried out system‐level analysis to investigate a novel IGCC‐CC power plant design using OTMs. We studied the impacts of various operating parameters on the overall efficiency and energy penalty. This novel IGCC‐OTM system has an overall efficiency 3.2%‐point lower than the same system without CC, much lower than the IGCC with water‐gas shift reactors and acid gas removal units (IGCC‐WGS) of 6.8%‐point drop. The specific primary energy consumption for CO2 avoided (SPECCA) of this novel technology is 1.08 MJ kgCO2−1, which is 59.4% lower than that of the IGCC‐WGS.

Assessing the potential of molten carbonate fuel cell-based schemes for carbon capture in natural gas-fired combined cycle power plants

This work explores two configurations of natural gas-fired combined cycles (NGCC) with molten carbonate fuel cells (MCFC) for CO2 capture. Special attention is devoted to the selection of MCFC operating conditions (trade-off between CO2 capture and voltage losses), heat integration scheme, fuel use and CO2 purification. Two schemes are considered: (i) in the first “integrated” scheme, MCFC modules are installed between the gas turbine and the heat recovery steam generator (HRSG) to maximize the efficiency of the integrated power plant; (ii) in the second “non-integrated” layout, the MCFC is located downstream of the HRSG and a regenerative heat exchanger is designed to preheat cathode reactants up to the MCFC working temperature. This study includes a full techno-economic analysis of the two layouts based on a preliminary sizing of the key-components, and a sensitivity analysis on the CO2 utilization factor. Compared to a benchmark amine scrubbing process, the “integrated” configuration shows considerably better performance (Specific Primary Energy Consumption for CO2 Avoided - SPECCA = 0.31 MJ kgCO2-1; Cost of CO2 avoided - CCA = 50 $ tCO2−1), whereas the “non-integrated” solution shows higher energy penalties but similar CO2 avoidance cost (SPECCA = 2.4 MJ kgCO2−1; CCA = 76 $ tCO2−1).

Comparison of Technologies for CO2 Capture from Cement Production—Part 1: Technical Evaluation

A technical evaluation of CO2 capture technologies when retrofitted to a cement plant is performed. The investigated technologies are the oxyfuel process, the chilled ammonia process, membrane-assisted CO2 liquefaction, and the calcium looping process with tail-end and integrated configurations. For comparison, absorption with monoethanolamine (MEA) is used as reference technology. The focus of the evaluation is on emission abatement, energy performance, and retrofitability. All the investigated technologies perform better than the reference both in terms of emission abatement and energy consumption. The equivalent CO2 avoided are 73–90%, while it is 64% for MEA, considering the average EU-28 electricity mix. The specific primary energy consumption for CO2 avoided is 1.63–4.07 MJ/kg CO2, compared to 7.08 MJ/kg CO2 for MEA. The calcium looping technologies have the highest emission abatement potential, while the oxyfuel process has the best energy performance. When it comes to retrofitability, the post-combustion technologies show significant advantages compared to the oxyfuel and to the integrated calcium looping technologies. Furthermore, the performance of the individual technologies shows strong dependencies on site-specific and plant-specific factors. Therefore, rather than identifying one single best technology, it is emphasized that CO2 capture in the cement industry should be performed with a portfolio of capture technologies, where the preferred choice for each specific plant depends on local factors.

Techno-economic analysis of calcium looping processes for low CO2 emission cement plants

The scope of this work is to perform a techno-economic analysis of two Calcium Looping processes (CaL) for CO2 capture in cement plants. Both tail-end CaL system with fluidized bed reactors and integrated CaL system with entrained flow reactors have been considered in the analysis. The calculation of the heat and mass balances and the economic analysis are consistent with the methodology defined in the framework of the H2020 Cemcap project.The analysis shows that the assessed CaL systems (especially the tail-end configuration) involve a significant increase of fuel consumption compared to a reference cement kiln without carbon capture. However, a large part of this additional energy input is exploited in a heat recovery steam cycle, which generates the electric power required to satisfy the consumption of the CO2 capture auxiliaries (i.e. the power absorbed by the air separation and CO2 compression and purification units). The integrated CaL process features a lower rise of equivalent fuel consumption (+59% compared to the reference) and a larger reduction of direct CO2 emission (-93% compared to the reference). The specific primary energy consumption for CO2 avoided (SPECCA), which takes into account also the indirect fuel consumption/savings and indirect emissions/avoided emissions due to electricity exchange (import/export) with the grid, ranges between 3.17–3.27 MJLHV/kgCO2 for the integrated system vs. 3.76–4.42 MJLHV/kgCO2 for tail-end cases, depending on the scenario considered for the grid electricity mix.The economic analysis highlights that CaL processes are capital intensive, which involve, roughly, a doubling of the Capex of the whole cement plant with CCS compared to a greenfield conventional cement plant. However, the obtained cost of CO2 avoided is competitive with alternative technologies and ranges between about 52 €/tCO2 of the tail-end configuration and 58.6 €/tCO2 of the integrated one.

Techno-Economic Analysis of Calcium Looping Processes for Low CO2 Emission Cement Plants

This work presents the results of the techno-economic analysis of cement plants with Calcium looping (CaL) process for CO2 capture. Two different CaL integration approaches are compared, namely the tail-end CaL with fluidized bed reactors and the integrated CaL with entrained flow reactors. Specific primary energy consumption for CO2 avoided (SPECCA) of 3.3 and 3.8 MJLHV/kgCO2 have been calculated for the integrated and the tail end CaL cases respectively. Cost of CO2 avoided between 50 and 56 €/tCO2 have been obtained.

Process integration study of tail-end Ca-Looping process for CO2 capture in cement plants

In this work, the integration of Calcium looping (CaL) process into a cement plant for post-combustion CO2 capture is assessed via process simulations. In the proposed scheme, the carbonator of the CaL process is used as an end-of-pipe unit to capture the CO2 from the cement kiln gas.From the results obtained, it is demonstrated that CO2 capture efficiencies of the order of 90% are achievable, with CaL reactors operating in conditions not far from those demonstrated for application in power plants. The integration of the tail-end CaL process results in a significant increase of the total fuel consumption (about two to three times higher) compared to the benchmark cement plant without CO2 capture. On the other hand, the heat from the CaL process can be recovered by a steam cycle producing decarbonized electric power that may exceed the needs of the plant auxiliaries (including the ASU and the CO2 compression and purification unit), exporting in this way electricity to the grid and so resulting in CO2 emission credits from a life cycle perspective. The resulting specific primary energy consumption for CO2 avoided (SPECCA) highly depends on the reference power generation technology considered, and it ranges between 2.7 and 3.7 MJLHV/kgCO2 in a coal-fired power generation scenario.As for the retrofittability of existing cement plants, the operation of the suspension preheating tower after the implementation of the CaL unit, as well as the position of the CaL carbonator with respect to the raw mill, have been assessed. Based on the results obtained, no critical issues have been found from a technical point of view in the adoption of the tail-end CaL process in existing cement kilns.

Kinetic study of a Layout for the Carbon Capture with Aqueous Ammonia without Salt Precipitation

This paper focuses on carbon capture in an Ultra Super Critical power plant. The technology selected for CO2 capture is based on cooled ammonia scrubbing in post-combustion mode, as recently investigated by the authors in another work. Here, a rate-based approach is adopted. In detail, a specific primary energy consumption for CO2 avoided (SPECCA) of 2.77MJ/kgCO2 is calculated in case of 85% of CO2 capture, with an ultimate power plant efficiency of 37.27%.

Performance Improvement of Cooled Ammonia-based CO2 Capture in Combined Cycles with Gasification of High-sulfur Coal

This paper focuses on carbon capture in an advanced combined cycle with air-blown gasification of high-sulfur coal. The technology selected for CO2 capture is based on cooled ammonia scrubbing in post-combustion mode, as recently investigated by the authors in another work. Here, a stronger integration among the desulfurization unit, the CO2 capture plant and the steam cycle is considered, in order to improve the ultimate performance. In detail, a specific primary energy consumption for CO2 avoided (SPECCA) as low as 1.97MJ/kgCO2 is calculated in case of 90% of CO2 capture, with an ultimate power plant efficiency of 42.53%.

Assessment of MDEA absorption process for sequential H2S removal and CO2 capture in air-blown IGCC plants

This work deals with pre-combustion CO2 capture by Methyldiethanolamine (MDEA) scrubbing in air-blown integrated gasification combined cycles (IGCCs). Two types of coal, with low- and high-sulphur content, are considered as fuel input in power plants, as well as two combustion turbines, with different turbine inlet temperature, representative of state-of-the-art and advanced technologies.The gasification section and the power island are simulated by means of the proprietary code GS. Acid gas removal (AGR), consisting in the sequential H2S removal and CO2 capture from the syngas by MDEA solvent, is calculated with Aspen Plus®. MDEA concentration and solvent circulation are varied in each of the assessed cases to comply with the target CO2 capture efficiency and with the CO2 and H2S purity specifications. The resulting heat duties for H2S and CO2 stripping, the consumption of the auxiliaries in the AGR plants, as well as the CO2 compression work are used to calculate the energy and mass balances of the integrated gasification combined cycles. Sensitivity analysis on the temperature approach in the recuperative heat exchanger of the CO2 capture section and on the pressure of the CO2 stripping column have been performed to assess potential energy savings. Results are compared with benchmark IGCC plants without CO2 capture.Net electric efficiencies between 36.6% and 40.4%, with 95% of CO2 capture efficiency, are achieved depending on the coal quality (i.e. the sulphur content), the combustion turbine technology and the MDEA regeneration pressure and heat exchanger temperature difference. Correspondingly, a specific primary energy consumption for CO2 avoided (SPECCA) between 2.85 and 3.2MJ/kgCO2 for the low-sulphur coal cases and between 3.2 and 3.7MJ/kgCO2 for the high-sulphur coal cases have been calculated.

A thermo-economic analysis of repowering of a 250 MW coal fired power plant through integration of Molten Carbonate Fuel Cell with carbon capture

This paper presents a thermo-economic assessment of a repowering configuration of a 250MW old existing coal fired power plant through integration of Molten Carbonate Fuel Cells (MCFC) at the downstream of the existing boiler. Hydrogen-rich syngas generated from natural gas in an external reformer used as fuel in MCFC unit. In the downstream of MCFC the residual combustible species from anode side is burnt with 98% pure oxygen, followed by heat recovery, cooling and moisture separation, CO2 compression and storage. The proposed repowering scheme helps to increase the plant capacity by about 27%, while capturing 67% of emitted CO2. Contrary to the conventional CO2 capture process, this MCFC repowering does not eat up the plant's efficiency, rather, it increases the net efficiency by 1.1%-points. The effect of repowering on cost of electricity, CO2 avoided cost (CCA), specific primary energy consumption for CO2 avoided (SPECCA) are estimated. The study shows that this repowering scheme yields a lesser unit cost of electricity (COE) compared to the commercially available monoethanolamine (MEA) based carbon capture retrofit.

Integrated gasification combined cycle with carbon dioxide capture by elevated temperature pressure swing adsorption

This paper investigates the CO2 capture energy consumption via elevated-temperature pressure swing adsorption (ET-PSA) for CO2/H2 separation. IGCC power plants with ET-PSA, with the conventional Selexol process and without CO2 capture are built in Aspen Plus. The CO2 capture energy consumption of ET-PSA is evaluated by the specific primary energy consumption for CO2 avoided (SPECCA), which is a function of the net electrical efficiency and the specific CO2 emission rate. The ET-PSA unit with different processes simulated in gPROMS is coupled into the IGCC model, the operation parameters of which are analyzed to achieve the lowest SPECCA. The results show that the CO2 capture energy consumption has a tendency to decrease by increasing the adsorption time, the residence time, and the purge-to-feed ratio; reducing the purge ratio; and adding the CO2 reflux. The SPECCA of ET-PSA with the 5–3–1 process is 2.79MJ/kgCO2 with a 90.5% CO2 capture ratio, which is 11.71% lower than that of the Selexol process. An effective way to further reduce the SPECCA of ET-PSA is to add rinse and purge steps, whose energy loss mainly comes from the consumption of high-temperature steam. The calculated SPECCA of ET-PSA with rinse and purge steps is 2.32–2.52MJ/kgCO2, which is 20.3–26.6% lower than that of the Selexol process.

Investigations of an air-blown integrated gasification combined cycle fired with high-sulphur coal with post-combustion carbon capture by aqueous ammonia

This work deals with CO2 capture plants for an advanced air-blown gasification-based combined cycle where a coal with high sulphur content, which is really relevant for the coal market, is used as feedstock. The sulphur removed as H2S from the coal-derived gas enters a wet sulphuric acid process. Later, the resulting acid is used to control ammonia slip in a post-combustion CO2 capture plant based on ammonia scrubbing and designed for a reduced energy demand. Thus, limiting the energy impact of the CO2 capture technology will improve the power plant efficiency, according to a presumable lower cost of the generated electricity, as a high-sulphur coal is used as fuel input.In detail, a cooled ammonia-based process is found to be more attractive than a more conventional chilled ammonia-based solution: in case of 90% of CO2 avoided, the overall power plant efficiency is equal to 41.7% and the SPECCA (specific primary energy consumption for CO2 avoided) as low as 2.3MJ/kgCO2. Moreover, the calculation results show the SPECCA for CO2 avoided ranging from 80% to 90% is almost constant, even though the power plant efficiency increases if lower levels of CO2 capture are considered.