Post-combustion CO2 Capture Pilot Plant Research Articles

Process simulation and optimization for post-combustion CO2 capture pilot plant using high CO2 concentration flue gas as a source

This work mainly focuses on process simulation and optimization of a high-concentrated CO2 chemical absorption process using aqueous amine solutions based on both pilot plant data and process modeling. To optimize operating parameters for reducing energy consumptions, this study explores the influence of process structure and operational parameters on the product purity, capture rate, and energy consumption, which would provide theoretical and technical support for optimizing high-concentration CO2 capture. At first, the rate-based absorption/desorption models are established and well-verified by a total of 25 sets of pilot plant data, which shows high accuracy for reliable model predictions. Under an annual absorption capacity of 50 tons at a 90% capture rate and 95% product purity, the optimal case using Monoethanolamine (MEA) solution shows an increased CO2 capture rate of 12.37% and a decreased unit energy consumption of 22.5%. After flowsheet optimization, a new system of blended MEA, Methyl diethanolamine (MDEA), and 2-Amino-2-methyl-1-propanol (AMP) solution is designed to capturing high-concentrated CO2 under the same conditions. Compared with the MEA system, its specified energy consumption is reduced by 10.35% and its CO2 capture capacity increases by 11.6 tons annually.

Numerical modelling and process simulation of a post-combustion CO2 capture pilot plant based on a membrane contactor unit

Hollow fiber membrane contactors (HFMC) have gained prominence in post-combustion CO2 capture applications due to their potential for high mass transfer rates, compactness, modularity and versatility. In this work, two pilot plant design have been proposed, an innovative solution which foresees the membrane contactor as CO2 absorption reactor, and a conventional one based on a packed column absorber. A one-dimensional model based on the resistance-in-series method has been developed for the membrane module and validated against experimental data from literature. The other process units have been simulated in Aspen Plus V11. According to the model results the membrane contactor unit is able to guarantee same levels of CO2 removal rates with improved energy performances compared to the conventional packed column absorber. In particular, if the same reactor volume is considered for the two absorber configurations, a reduction in the specific reboiler duty (SRD) of 8.5% is estimated. On the other hand, if the same liquid-to-gas (L/G) ratio is applied, the HFMC is able to guarantee a required reactor volume almost halved (45% reduction). These substantial improvements of the CO2 capture process could lead to lower investment cost and better economic indicators of the CO2 capture plant.

Seawater Desalination with an Amine-based CO2-Capture Process

A new concept for seawater desalination integrated into an amine-based CO2-capture process is presented. It is based on the use of forward osmosis to transfer water from seawater into the absorption solution via a membrane. Desalted water can subsequently be recovered as the condensate from the desorber outlet or through membrane distillation from the absorber. Suitable membranes have been identified and the most promising one was selected for laboratory evaluation using representative amine solutions. The process performance parameters, membrane water flux and reverse amine flux were determined. The process performance was best for amino-acid salt solutions. Further work will focus on demonstration of the technology using a post-combustion CO2 capture pilot plant operating on real flue gas.

Environmental Risk Assessment of MEA and its Degradation Products from Post-combustion CO2 Capture Pilot Plant: Drafting Technical Guidelines

To significantly reduce the amount of emission of carbon dioxide (CO2) to the atmosphere, which is a principal cause of climate change (global warming), and to realize a low-carbon society, the introduction of Carbon dioxide Capture and Storage (CCS) into coal-fired power plants is expected to be effective. Emissions from post-combustion CO2 capture plants using amine solution may affect the human health and environment. It is, therefore, important to evaluate the environmental impacts by conducting environmental risk assessment, and to, if necessary, employ emission reduction technologies, for effectively introducing CCS. Case studies on amine emissions from the CO2 capture process and the results of environmental risk assessment are reported. However, there are no guidelines on environmental risk assessment method for the CO2 capture process which enable plant owners to reduce the environmental impact of the process, to increase understanding of local residents (near CO2 capture plants) and public, and to promote the introduction of CCS.In this study, as part of the project by Ministry of the Environment (Japan), Mizuho Information & Research Institute, Inc. (MHIR) and Toshiba Corporation drafted the guidelines presenting the basic principles (methods, basic points) of environmental risk assessment with regard to exhaust gas and other parameters involved in the CO2 capture process. Based on Toshiba's emission data from 10 ton-CO2/day scale pilot plant using MEA solution at Mikawa coal fired thermal power plant, MHIR conducted a trial of environmental risk assessment for the CO2 capture process, examined the risk assessment procedure, and drafted technical guidelines. The guidelines are expected to enable plant owners to make reasonable judgement on “how far emission should be reduced”, and thus to decide “to what extent they should employ emission reduction technologies”. And, the guidelines include “whole-mixture approach”, which not only helps to conquer the issues typical of the CO2 capture process but also is easy to understand and thus familiar to local residents and public.

Effect of Acid Catalysts on CO2 Absorption Process by Mixed Amines

This study evaluated the effects of two solid acid catalysts (γ-Al2O3 and HZSM-5), and two tertiary amines (methyldiethanolamine and 4-(diethylamine)-2-butanol mixed with monoethanolamine on the CO2 capture process performance in terms of heat duty, cyclic capacity and absorber efficiency using a bench scale amine-based post-combustion CO2 capture pilot plant with different amounts of each solid acid catalyst in the desorber. Comparisons were made between 5M MEA, 5M MEA/2M MDEA, and 5M MEA/1.25M DEAB with and without catalyst in the desorber. It was found that 5M MEA/1.25M DEAB with HZSM-5 gave the highest cyclic capacity, absorption efficiency and lowest heat duty.

Development of Techno-Economic Evaluation Model for CCS (Carbon Capture & Sequestration)

In this study, Techno-economic evaluation model for carbon capture & sequestration (CCS) technologies are reviewed. Based on a key parameters of Korea’s electricity market, performance data of 10 ㎿-scale post-combustion CO₂ capture pilot plant in Boryong station, the cost of CO₂ avoided was evaluated followed by international guideline suggested by IEA CCS costing methods task force. The result showed that Korea’s Electricity cost including CAPEX & OPEX of reference power plant is relatively low compared to OECD nations which lead to a lower CCS cost (33 USD t/CO₂). And future work using newly evaluated CAPEX & OPEX data of power plant with/without CCS is recommended.

Comprehensive monitoring of MEA degradation in a post-combustion CO2 capture pilot plant with identification of novel degradation products in gaseous effluents

A pilot plant campaign was performed to study MEA degradation in CO2 capture conditions and anticipate potential degradation products emissions to the atmosphere in industrial case. Aqueous 30% wt MEA was cycled between absorption and regeneration steps during 1700h in the presence of a synthetic flue gas containing 81% of N2, 14% of CO2, 5% of O2, 97ppm of NO, 9ppm of SO2 and 5ppm of NO2. Specific methods (sampling, sample conditioning and analysis) were developed to improve degradation products identification and to provide a quantification of targeted compounds in liquid phase and above all in absorber and stripper gas effluents. Especially, trace elements were detected in liquid phase thanks to Head Space-Solid Phase MicroExtraction (HS-SPME) and liquid–liquid extraction with ChemElut cartridges and in gas phase thanks to adsorbent tubes of different type: Sep-Pak® for aldehydes and ketones, Orbo 60 for N-nitrosodimethylamine, Tenax and active charcoal for non-specific adsorption. 32 degradation products were identified in liquid phase and 38 in gas phase, 17 of which for the first time, especially derivatives of pyridine and oxazolidine, 1H-pyrrole and a new nitrosamine, the N-nitroso-2-methyl-oxazolidine.

Flexible operation of CSIRO's post-combustion CO2 capture pilot plant at the AGL Loy Yang power station

Flexible operation has the potential to significantly improve the economic viability of post-combustion CO2 capture (PCC). However, the impact of disturbances from flexible operation of the PCC process is unclear. The purpose of this study was to investigate the effects of flexible operation in a PCC pilot plant by implementing step-changes for improved dynamic data reliability. The flexible operation campaign was conducted at the CSIRO PCC pilot plant at AGL Loy Yang using monoethanolamine (MEA) absorbent. The pilot plant was operated under a broad range of transient conditions (changing flue gas flow, liquid absorbent flow and steam pressure) to capture the dynamics of a PCC process during flexible operation. The study demonstrated that the dynamics of flue gas flow rate was faster than absorbent flow rate. The greatest CO2 removal% was achieved at the lowest flue gas flow rate or at the highest absorbent flow rate; however, the latter provided improved energy efficiency. The steam pressure parameter could adjust the temperature of all columns simultaneously which can be used to compensate for effects from ambient conditions or heat losses. These results verify the technical feasibility of flexible PCC operation and provide a suitable dataset for dynamic model validation.

Dynamic modelling, identification and preliminary control analysis of an amine-based post-combustion CO2 capture pilot plant

Solvent-based post combustion CO2 capture (PCC) is considered as a mature technology for dealing with CO2 emissions from fossil-fired power plants. In this study, a mathematical black box model is developed to analyse the dynamic responses of a PCC pilot plant. The model identification reported the dynamics of variables of the key units in the plant, the absorber, rich/lean heat exchanger and desorber. Pilot plant dynamic data were used to develop a data-driven model for each unit operation. Individual models were integrated to produce a simplified 4 × 3 PCC process model of the PCC plant. The fastest dynamic with a time constant ranging from 2 to 3 min featured in the relationship between power plant flue gas flow rate and CO2 concentration in the absorber off gas. Whereas, the slowest response with a process time constant between 9 and 27 min occurred in CO2 concentration at the top of the stripper due to changes in reboiler heat duty. Preliminary control analysis using relative gain array (RGA) analysis suggested that carbon capture efficiency, CC (%), and energy performance, EP (MJ per kg of CO2 captured), can be controlled by manipulating the lean solvent flow rate and reboiler heat duty, respectively. The proposed control structure was tested and tracked CC and EP random set point step changes in the range between 7–25 h and 4–5 h respectively. This study contributes to understanding transient variable behaviours in PCC plants; concurrent with current industrial requirements for controllability and flexible operation of PCC plants, in response to the dynamics of power plant load, electricity and carbon prices.

Reclaiming of degraded MEA solutions by electrodialysis: Results of ED pilot campaign at post-combustion CO2 capture pilot plant

A study of the behavior of heat stable salts (HSS) during electrodialysis (ED) reclaiming of monoethanolamine solvent (30wt.% MEA) is reported in detail. Degraded lean MEA samples with a loading of approx. 0.2mol/mol were taken from the solvent loop of post-combustion capture (PCC) pilot plant after 400, 535 and 972h of operation at real conditions. The specially designed conventional pilot ED unit equipped with cation-exchanged membranes and anion-exchanged membranes was used. Before and after ED reclaiming, all streams were analyzed for specific solvent components. A quite uniform removal of all analyzed HSS anions (except for nitrate ions) during the ED treatment prevents accumulation of any specific undesirable compound in the solvent loop. Visual inspection of the ion-exchange membranes revealed the deposition on the membrane surface having reddish-brown color. It was experimentally confirmed that such deposition did not noticeable affect on membrane performance in ED process. Furthermore, it was demonstrated on the laboratory level that selected membranes possess a good long-term stability after being contacted with fresh and degraded MEA for approx. 2 years.

Reclaiming of Monoethanolamine (MEA) Used in Post-Combustion CO2-capture with Electrodialysis

Heat-stable salts (HSS) in amine-based solvents may lead to a long-term performance impairment of post-combustion CO2- capture process system. They can cause a loss of solvent capacity, corrosion, heat exchanger fouling, increased foaming or flooding, etc. The application of electrodialysis (ED) can be a possible cost effective technique for removal of HSS from degraded amine solutions. The paper presents the results of lab-scale ED experiments on HSS removal from synthetic degraded MEA solutions with different HSS content and CO2-loadings. The efficiency of ED-process for reclaiming of MEA solvent is shown. The influence of solvent CO2-loading on the specific energy consumption of ED-process is presented. The lab-scale data have been used for design and manufacturing of a pilot ED plant. Within the OCTAVIUS project it has been planned to test the ED-pilot plant at the EnBW post-combustion CO2 capture pilot plant.

Pilot-scale Demonstration of an Advanced Aqueous Amine-based Post-combustion Capture Technology for CO2 Capture from Power Plant Flue Gases

Abstract Post-combustion CO 2 capture (PCC) technology offers flexibility to treat the flue gas from both existing and new coal-fired power plants and can be applied to treat all or a portion of the flue gas. Solvent-based technologies are today the leading option for PCC from large coal-fired power plants as they have been applied in large-scale in other applications. Linde and BASF are working together to further improve a post-combustion capture technology incorporating BASF's novel aqueous amine-based process based on the results of the joint development of BASF, Linde and RWE at the PCC pilot plant in Niederaussem, Germany. This technology offers significant benefits compared to other solvent-based processes as it aims to reduce the regeneration energy requirements using novel solvents that are very stable under the coal-fired power plant feed gas conditions. BASF has developed the desired solvent based on the evaluation of a large number of candidates and long-term small pilot-scale testing has been performed on a lignite-fired flue gas. Linde has evaluated a number of options for capital cost reduction in large engineered systems for solvent-based PCC technology. Pilot-scale demonstration on a coal-fired power plant flue gas at a 1-1.5 MW e scale is currently planned under a project supported by DOE (project award DE-FE0007453). Mechanical completion of the pilot plant was achieved in July 2014 and the final commissioning activities are being completed to enable start-up of operations in late 2014. The pilot plant incorporates the capability to test a number of unique features of the Linde-BASF technology aimed at lowering the overall energy consumption as well as resulting in capital cost reduction. In this presentation, the details of the fabrication, construction and start-up of the pilot plant will be discussed. The pilot plant incorporates significant instrumentation and control features to enable automated and stable operation, and the ability to reliably check and verify mass and energy balance closures with adequate redundancies. Detailed plans for the parametric and long-term testing will be discussed; these tests are aimed at validating the technology performance against targets set based on a preliminary techno-economic assessment, and, the stability of the solvent with continued operation over an extended period.

Dynamic Operation of Post-combustion CO2 Capture in Australian Coal-fired Power Plants

Abstract Flexible operation of post-combustion CO 2 capture (PCC) plants can improve efficiency through coordinating the balance between consumer demands for electricity and CO 2 emission reductions. This strategy however, will impose process disturbances and the immediate and long term impact is unclear. There is a justified need for the development of accurate dynamic PCC models, as well as practical experience in dynamic operation of PCC pilot plants. This paper presents CSIRO PCC pilot plant data from the 2012 and 2013 dynamic campaigns using MEA solvent. The step-change approach to dynamic plant operation was implemented and the use of density meters to instantaneously measure CO 2 loading instantaneously was investigated.

Evaluation of amine emissions from the post-combustion CO2 capture pilot plant

In this work, we evaluated amine emissions from 10ton-CO2/day scale pilot plant in Mikawa Power Plant of Sigma Power Co. Ltd. within TS-1 solvent. Firstly, we investigated that how sampling gas flow rate affects measured value of amine concentration in flue gas by using on-line sampling method with PTR-MS analyzer. It was found that the error from an iso-kinetic sampling rises sharply for lower sampling velocities and in the range of higher sample stream velocities, however the error is lower. Secondly, we compared between beginning of operation and 2,800hours operation in terms of amine emissions at Mikawa pilot plant under one set of conditions. At beginning of operation, there were no degraded amines in TS-1 solution. Thus, there were no amine emissions of degraded amines. However, at 2,800hours operating, in addition to TS-1 emissions, some quantity of emissions of degraded amines were detected even though degraded amines were much less than TS-1 main amine in TS-1 solution. Toshiba improved operating conditions such as plant system, water wash system to reduce the amount of amine emissions. As a result, the latest tests showed lower emissions of less than 1 ppm(v/v) at 2,800hours operation. A concentration of degraded amine [D] in TS-1 solution at 2,800hours operation, which was nearly detection limit, was lower than other degraded amines. Nevertheless, degraded amine [D] accounted for the greater part of amine emissions after water wash was improved. This result suggested that it is crucial to reduce the volatility of emitted degraded amines in order to improve performance of suppression amine emissions further. Then, finally we evaluated effect of addition acid to reduce the volatility of degraded amine [D]. The results in diluted aqueous amines at 40°C showed that effectiveness of acid for reducing amine volatility is in the order: sulfuric acid > oxalic acid carbonic acid produced by 10%CO2 > boric acid.

CCPilot100+ Operating Experience and Test Results

Doosan Power Systems are developing competitive Post Combustion CO2 Capture (PCC) technologies for application on coal- and natural gas-fired power plants for commercialisation by 2020.The paper presents an overview of the UK's largest post combustion CO2 capture plant on a coal fired power station, the CCPilot100+, giving an insight into the design and construction processes, operating experience gained during commissioning and a presentation of preliminary results from the first period of testing.Doosan Power Systems completed commissioning the CCPilot100+ plant at SSE's Ferrybridge Power Station in West Yorkshire in March 2012. The 100 t CO2/day (15MWt, 5MWe equivalent) CCPilot100+ PCC pilot plant is the first of its size to be integrated into a live power plant in the UK and uses Doosan Power Systems’ technology. It is designed to demonstrate scale-up of the PCC process and provides a stepping stone from process characterisation on Doosan Power Systems’ 1 t CO2/day (160kWt) Emissions Reduction Test Facility (ERTF) to commercial-scale (150MWe plus) plant. The experience gained during the development and operation of the ERTF PCC pilot plant has been used in both the CCPilot100+ plant design and test programme development.The project is co-funded by the project partners: SSE, Vattenfall AB, the Technology Strategy Board (TSB), the Department of Energy and Climate Change (DECC), The Northern Way and Doosan Power Systems, who were also responsible for the design and EPC project. In addition to the partners, four universities are undertaking associated research as part of the project and there is a training programme for future CCS engineers on a ‘live’ plant, creating a valuable resource for future developments.A two year test programme started in the first quarter of 2012. The test programme and long-term operation of the CCPilot100+ aim to optimise the PCC process and provide the data to develop and validate performance models. The test programme will demonstrate the capability of the process over the range of operating conditions that exist in power plant resulting from modern day electrical demand. The test programme will also assess and optimise, where possible, the performance of solvents for regeneration steam consumption, solvent degradation and materials compatibility.Auxiliary power requirements, which add to power plant parasitic losses, will be assessed and, by working with the supply chain, more efficient methods of operation can be considered and developed.Benchmark performance on 30% w/w monoethanolamine (MEA) solvent is being established first and will be followed by extensive parametric and long-term performance testing using the RS2TM designer solvent. Optimisation and long-term testing of a next generation advanced solvent will also be conducted following the RS2 TM testing phase. The testing and verification programmes at both the CCPilot100+ and the ERTF will be used to substantiate the scalability of Doosan Power Systems’ PCC technology under real operating conditions.