Browsing by Author "Wang, Meihong"

Now showing 1 - 8 of 8
  • Thumbnail Image
    ItemOpen Access
    Demonstrating full-scale post-combustion CO2 capture for coal-fired power plants through dynamic modelling and simulation
    (Elsevier Science B.V., Amsterdam., 2012-11-12T00:00:00Z) Lawal, Adekola; Wang, Meihong; Stephenson, Peter; Obi, Okwose
    This study aims to provide insights into the design and operation of full-scale post-combustion CO2 capture for a 500MWe sub-critical power plant through dynamic modelling and simulation. The development and validation of the dynamic models of the power plant and CO2 capture plant are described. In addition, the scale-up of the CO2 capture plant from pilot plant scale (where it was validated) to full scale is discussed. Subsequently the manner in which the two plant models were linked is discussed. A floating IP/LP crossover pressure configuration is used. A throttling valve is included between the LP turbine and draw-off point to prevent pressures at the crossover from dropping below required levels in the reboiler for solvent regeneration. The flue gas from the power plant is treated before it is sent to the CO2 capture plant. Four case studies are considered. The first investigates the effect of increasing solvent concentration on the performance of the power plant with the capture plant. The second investigates which absorber packing height offers a good balance between capital and operating costs. The two dynamic case studies show that the CO2 capture plant has a slower response than the power plant. They also reveal an interaction of CO2 capture level and power plant output control loops making it difficult to achieve steady power output levels quickly.
  • Thumbnail Image
    ItemOpen Access
    Dynamic modeling and simulation of CO2 chemical absorption process for coal- fired power plants
    (2009-10-04) Lawal, Adekola; Wang, Meihong; Yeung, Hoi; Stephenson, Peter; de Brito Alves, RM, Oller do Nascimento, CA, Biscaia Jr, EC
    Post combustion capture via chemical absorption is viewed as the most mature CO capture technique. The effects of the addition of CO chemical absorption process on power plant performance have been studied using various steady-state models. However, there are several gaps in the understanding of the impact of post combustion capture on the operability of the power plant. These questions could be addressed by studying the dynamic behavior of such plants. In this study, dynamic models of the CO chemical absorption process were developed and validated. Dynamic analyses of the process reveal that absorber performance is sensitive to L/G ratio and that changes in reboiler duty significantly affect the regenerator performance.
  • Thumbnail Image
    ItemOpen Access
    Dynamic modelling and analysis of post-combustion CO2 chemical absorption process for coal-fired power plants
    (Elsevier Science B.V., Amsterdam., 2011-12-06) Lawal, Adekola; Wang, Meihong; Stephenson, Peter; Koumpouras, G.; Yeung, Hoi
    Post-combustion capture by chemical absorption using MEA solvent remains the only commercial technology for large scale CO2 capture for coal-fired power plants. This paper presents a study of the dynamic responses of a post- combustion CO2 capture plant by modelling and simulation. Such a plant consists mainly of the absorber (where CO2 is chemically absorbed) and the regenerator (where the chemical solvent is regenerated). Model development and validation are described followed by dynamic analysis of the absorber and regenerator columns linked together with recycle. The gPROMS (Process Systems Enterprise Ltd.) advanced process modelling environment has been used to implement the proposed work. The study gives insights into the operation of the absorber- regenerator combination with possible disturbances arising from integrated operation with a power generation plant. It is shown that the performance of the absorber is more sensitive to the molar L/G ratio than the actual flow rates of the liquid solvent and flue gas. In addition, the importance of appropriate water balance in the absorber column is shown. A step change of the reboiler duty indicates a slow response. A case involving the combination of two fundamental CO2 capture technologies (the partial oxyfuel mode in the furnace and the post-combustion solvent scrubbing) is studied. The flue gas composition was altered to mimic that observed with the combination. There was an initial sharp decrease in CO2 absorption level which may not be observed in steady-state simulations. (C) 2010 Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    ItemOpen Access
    Dynamic modelling of CO2 absorption for post combustion capture in coal-fired power plants
    (Elsevier Science B.V., Amsterdam., 2009-12-01T00:00:00Z) Lawal, Adekola; Wang, Meihong; Stephenson, Peter; Yeung, Hoi
    Power generation from fossil fuel-fired power plants is the largest single source of CO2 emissions. Post combustion capture via chemical absorption is viewed as the most mature CO2 capture technique. This paper presents a study of the post combustion CO2 capture with monoethanolamine (MEA) based on dynamic modelling of the process. The aims of the project were to compare two different approaches (the equilibrium-based approach versus the rate-based approach) in modelling the absorber dynamically and to understand the dynamic behaviour of the absorber during part load operation and with disturbances from the stripper. A powerful modelling and simulation tool gPROMS was chosen to implement the proposed work. The study indicates that the rate-based model gives a better prediction of the chemical absorption process than the equilibrium-based model. The dynamic simulation of the absorber indicates normal absorber column operation could be maintained during part load operation by maintaining the ratio of the flow rates of the lean solvent and flue gas to the absorber. Disturbances in the CO2 loading of the lean solvent to the absorber significantly affect absorber performance. Further work will extend the dynamic modelling to the stripper for whole plant analysis.
  • Thumbnail Image
    ItemOpen Access
    Harnessing the power of machine learning for carbon capture, utilisation, and storage (CCUS) – A state-of-the-art review
    (Royal Society of Chemistry, 2021-11-01) Yan, Yongliang; Borhani, Tohid N.; Subraveti, Sai Gokul; Pai, Kasturi Nagesh; Prasad, Vinay; Rajendran, Arvind; Nkulikiyinka, Paula; Asibor, Jude Odianosen; Zhang, Zhien; Shao, Ding; Wang, Lijuan; Zhang, Wenbiao; Yan, Yong; Ampomah, William; You, Junyu; Wang, Meihong; Anthony, Edward J.; Manovic, Vasilije; Clough, Peter T.
    Carbon capture, utilisation and storage (CCUS) will play a critical role in future decarbonisation efforts to meet the Paris Agreement targets and mitigate the worst effects of climate change. Whilst there are many well developed CCUS technologies there is the potential for improvement that can encourage CCUS deployment. A time and cost-efficient way of advancing CCUS is through the application of machine learning (ML). ML is a collective term for high-level statistical tools and algorithms that can be used to classify, predict, optimise, and cluster data. Within this review we address the main steps of the CCUS value chain (CO2 capture, transport, utilisation, storage) and explore how ML is playing a leading role in expanding the knowledge across all fields of CCUS. We finish with a set of recommendations for further work and research that will develop the role that ML plays in CCUS and enable greater deployment of the technologies.
  • Thumbnail Image
    ItemOpen Access
    Planning for the integrated refinery subsystems
    (Cranfield University, 2012-06) Ejikeme-Ugwu, Edith; Wang, Meihong; Yeung, Hoi
    In global energy and industrial market, petroleum refining industry accounts for a major share. Through proper planning and the use of adequate mathematical models for the different processing units, many profit improving opportunities can be realized. The increasing crude oil price has also made refining of crude oil blends to be a common practice. This thesis aims to provide useful insight for planning of the integrated refinery subsystems. The main subsystems referred to are (1) The crude oil unloading subsystem (2) The production and product blending subsystem and (3) The product distribution subsystem. Aspen HYSYS® was first used to develop a rigorous model for crude distillation unit (CDU) and vacuum distillation unit (VDU). The rigorous model was validated with pilot plant data from literature. The information obtained from the rigorous model is further used to develop a model for planning of the CDU and VDU. This was combined with models (obtained from empirical correlations) for fluid catalytic cracker (FCC) and hydrotreater (HDT) units to form a mathematical programming planning model used for refinery production and product blending subsystem planning. Since two different types of crude were considered, the optimum volumetric mixing ratio, the sulphur content at that mixing ratio and the CDU flow rate were determined. The yields fraction obtained from the rigorous model were then used to generate regression model using least square method. The sulphur composition of the crude oil was used as independent variable in the regression model. The generated regression models were then used to replace the regular fixed yield approach in a refinery planning model and the results compared. From the results obtained, the proposed method provided an alternative and convenient means for estimating yields from CDU and VDU than the regular fixed yield approach. The proposed aggregate model for the production and products blending subsystem was integrated with the modified scheduling model for the crude unloading subsystem developed by Lee et al. (1996) and products distribution model developed by Alabi and Castro (2009) for refinery planning. It was found that the regression model could be integrated in a refinery planning model and that the CDU flow rate was maximised as compared to the non- integrated system.
  • Thumbnail Image
    ItemOpen Access
    Post-combustion CO2 capture with chemical absorption: a state-of-the-art review
    (Elsevier Science B.V., Amsterdam, 2011-09-01T00:00:00Z) Wang, Meihong; Lawal, Adekola; Stephenson, Peter; Sidders, J.; Ramshaw, C.
    Global concentration of CO2 in the atmosphere is increasing rapidly. CO2 emissions have an impact on global climate change. Effective CO2 emission abatement strategies such as Carbon Capture and Storage (CCS) are required to combat this trend. There are three major approaches for CCS: post-combustion capture, pre-combustion capture and oxyfuel process. Post-combustion capture offers some advantages as existing combustion technologies can still be used without radical changes on them. This makes post-combustion capture easier to implement as a retrofit option (to existing power plants) compared to the other two approaches. Therefore, post-combustion capture is probably the first technology that will be deployed. This paper aims to provide a state-of-the-art assessment of the research work carried out so far in post-combustion capture with chemical absorption. The technology will be introduced first, followed by required preparation of flue gas from power plants to use this technology. The important research programmes worldwide and the experimental studies based on pilot plants will be reviewed. This is followed by an overview of various studies based on modelling and simulation. Then the focus is turned to review development of different solvents and process intensification. Based on these, we try to predict challenges and potential new developments from different aspects such as new solvents, pilot plants, process heat integration (to improve efficiency), modelling and simulation, process intensification and government policy impact.
  • Thumbnail Image
    ItemOpen Access
    Study of post-combustion Carbon Dioxide capture for coal-fired plant through modelling and simulation
    (Cranfield University, 2010-12) Lawal, Adekola; Wang, Meihong; Yeung, Hoi
    Fossil-fuel power plants are the largest single source of carbon dioxide (CO2) emissions. Post-combustion capture through monoethanolamine-based absorption is viewed as the most mature technology proposed for mitigating CO2 emissions from such power plants. Despite its advantages, several design and operational challenges arise in the application of this technology. The amount of flue gas to process is much greater than current applications. As a consequence, there will be a large thermal energy requirement for solvent regeneration. There are also concerns about how post-combustion CO2 capture would affect the flexibility and operability of coal-fired power plants. Though expensive pilot plant studies exist worldwide, they are still on a much smaller scale than what would be required commercially. This thesis provides useful insights for the design and operation of pilot and commercial plants through modelling and simulation. Cont/d.