CCS (Carbon Capture and Storage) technology is one of the methods that limit the release of carbon dioxide into the atmosphere. However, the high cost of capturing CO2 in this technology is a major obstacle to the implementation of this solution by power plants. The reduction of costs is expected primarily on the side of the capture and separation of CO2 from flue/ industrial gas. The article presents the financial performance of the most popular amine technology (MEA) against mesoporous material about MCM-41 structure obtained from fly ash, impregnated with polyethyleneimine (PEI), for CCS installations. The study was conducted for an investment comprising three key components that provide a full value chain in CCS validation (capture, transport and storage). The mineralogical studies and determination of the physicochemical properties of mesoporous material produced from waste materials such as fly ash allowed us to identify the best class sorbents of MCM-41, which can be used in CO2 capture technologies. Developing an innovative relationship not only allows 100% of CO2 to be removed but also reduces operating costs (OPEX), primarily including energy by 40% and multiple material costs relative to amine mixtures such as MEA.
Amine absorption processes are widely used in the industry to purify refinery gases, process gases or natural gas. Recently, amine absorption has also been considered for CO2 removal from flue gases. It has a number of advantages, but there is one major disadvantage - high energy consumption. This can be reduced by using an appropriate sorbent. From a group of several dozen solutions, three amine sorbents were selected based on primary, tertiary and sterically hindered amines. The solutions were used to test CO2 absorption capacity, absorption kinetics and heat of CO2 absorption. Additional tests were performed on the actual absorber-desorber system to indicate the most appropriate sorbent for capturing CO2 from flue gases.
Integrated gasification combined cycle systems (IGCC) are becoming more popular because of the characteristics, by which they are characterized, including low pollutants emissions, relatively high efficiency of electricity production and the ability to integrate the installation of carbon capture and storage (CCS). Currently, the most frequently used CO2 capture technology in IGCC systems is based on the absorption process. This method causes a significant increase of the internal load and decreases the efficiency of the entire system. It is therefore necessary to look for new methods of carbon dioxide capture. The authors of the present paper propose the use of membrane separation. The paper reviews available membranes for use in IGCC systems, indicates, inter alia, possible places of their implementation in the system and the required operation parameters. Attention is drawn to the most important parameters of membranes (among other selectivity and permeability) influencing the cost and performance of the whole installation. Numerical model of a membrane was used, among others, to analyze the influence of the basic parameters of the selected membranes on the purity and recovery ratio of the obtained permeate, as well as to determine the energetic cost of the use of membranes for the CO2 separation in IGCC systems. The calculations were made within the environment of the commercial package Aspen Plus. For the calculations both, membranes selective for carbon dioxide and membranes selective for hydrogen were used. Properly selected pressure before and after membrane module allowed for minimization of energy input on CCS installation assuring high purity and recovery ratio of separated gas.
The new efficient method of modeling and thermodynamic analysis of power engineering systems has been presented. With its help a comparison of different structures and investigation of the influence of a particular constituent process onto the whole system efficiency is possible. The shaft work or the exergy is the main thermodynamic quantity taken into account in analyses, and the appropriate dimensionless modeling parameter has been introduced.
The paper presents the structure and parameters of advanced zero emission power plant (AZEP). This concept is based on the replacement of the combustion chamber in a gas turbine by the membrane reactor. The reactor has three basic functions: (i) oxygen separation from the air through the membrane, (ii) combustion of the fuel, and (iii) heat transfer to heat the oxygen-depleted air. In the discussed unit hot depleted air is expanded in a turbine and further feeds a bottoming steam cycle (BSC) through the main heat recovery steam generator (HRSG). Flue gas leaving the membrane reactor feeds the second HRSG. The flue gas consist mainly of CO2and water vapor, thus, CO2separation involves only the flue gas drying. Results of the thermodynamic analysis of described power plant are presented.
The paper presents the results and analysis of biomass processing in order to provide the conditions for the most profitable use of the biomass in modern and efficient power generation systems with particular attention put on the decrease of the emission of carbon dioxide (CO2) and no need to develop carbon capture and storage plants. The promising concept of CO2 storage via the production of biochar and the advantages of its application as a promising carbon sink is also presented and the results are supported by authors’ own experimental data. The idea enables the production of electricity, as well as (optionally) heat and cold from the thermal treatment of biomass with simultaneous storage of the CO2 in a stable and environmentally-friendly way. The key part of the process is run in a specially-designed reactor where the biomass is heated up in the absence of oxygen. The evolved volatile matter is used to produce heat/cold and electricity while the remaining solid product (almost completely dry residue) is sequestrated in soil. The results indicate that in order to reduce the emission of CO2 the biomass should rather be ‘cut and char’ than just ‘cut and burn’, particularly that the charred biomass may also become a significant source of nutrients for the plants after sequestration in soil.
The paper deals with the computational fluid dynamics modelling of carbon dioxide capture from flue gases in the post combustioncapture method, one of the available carbon capture and storage technologies. 30% aqueous monoethanolamine solution was used as a solvent in absorption process. The complex flow system including multiphase countercurrent streams with chemical reaction and heat transfer was considered to resolve the CO2 absorption. The simulation results have shown the realistic behaviour and good consistency with experimental data. The model was employed to analyse the influence of liquid to gas ratio on CO2 capture efficiency.
This article presents changes in the operating parameters of a combined gas-steam cycle with a CO2 capture installation and flue gas recirculation. Parametric equations are solved in a purpose-built mathematical model of the system using the Ebsilon Professional code. Recirculated flue gases from the heat recovery boiler outlet, after being cooled and dried, are fed together with primary air into the mixer and then into the gas turbine compressor. This leads to an increase in carbon dioxide concentration in the flue gases fed into the CO2 capture installation from 7.12 to 15.7%. As a consequence, there is a reduction in the demand for heat in the form of steam extracted from the turbine for the amine solution regeneration in the CO2 capture reactor. In addition, the flue gas recirculation involves a rise in the flue gas temperature (by 18 K) at the heat recovery boiler inlet and makes it possible to produce more steam. These changes contribute to an increase in net electricity generation efficiency by 1%. The proposed model and the obtained results of numerical simulations are useful in the analysis of combined gas-steam cycles integrated with carbon dioxide separation from flue gases.
The installations of CO2 capture from flue gases using chemical absorption require a supply of large amounts of heat into the system. The most common heating medium is steam extracted from the cycle, which results in a decrease in the power unit efficiency. The use of heat needed for the desorption process from another source could be an option for this configuration. The paper presents an application of gas-air systems for the generation of extra amounts of energy and heat. Gas-air systems, referred to as the air bottoming cycle (ABC), are composed of a gas turbine powered by natural gas, air compressor and air turbine coupled to the system by means of a heat exchanger. Example configurations of gas-air systems are presented. The efficiency and power values, as well as heat fluxes of the systems under consideration are determined. For comparison purposes, the results of modelling a system consisting of a gas turbine and a regenerative exchanger are presented.
In this paper, thermodynamic analysis of a proposed innovative double Brayton cycle with the use of oxy combustion and capture of CO2, is presented. For that purpose, the computation flow mechanics (CFM) approach has been developed. The double Brayton cycle (DBC) consists of primary Brayton and secondary inverse Brayton cycle. Inversion means that the role of the compressor and the gas turbine is changed and firstly we have expansion before compression. Additionally, the workingfluid in the DBC with the use of oxy combustion and CO2 capture contains a great amount of H2O and CO2, and the condensation process of steam (H2O) overlaps in negative pressure conditions. The analysis has been done for variants values of the compression ratio, which determines the lowest pressure in the double Brayton cycle.
The paper deals with numerical modelling of carbon dioxide capture by amine solvent from flue gases in post-combustion technology. A complex flow system including a countercurrent two-phase flow in a porous region, chemical reaction and heat transfer is considered to resolve CO2 absorption. In order to approach the hydrodynamics of the process a two-fluid Eulerian model was applied. At the present stage of model development only the first part of the cycle, i.e. CO2 absorption was included. A series of parametric simulations has shown that carbon dioxide capture efficiency is mostly influenced by the ratio of liquid (aqueous amine solution) to gas (flue gases) mass fluxes. Good consistency of numerical results with experimental data acquired at a small-scale laboratory CO2 capture installation (at the Institute for Chemical Processing of Coal, Zabrze, Poland) has proved the reliability of the model.
This paper presents the Life Cycle Assessment (LCA) analysis concerning the selected options of supercritical coal power units. The investigation covers a pulverized power unit without a CCS (Carbon Capture and Storage) installation, a pulverized unit with a "post-combustion" installation (MEA type) and a pulverized power unit working in the "oxy-combustion" mode. For each variant the net electric power amounts to 600 MW. The energy component of the LCA analysis has been determined. It describes the depletion of non-renewable natural resources. The energy component is determined by the coefficient of cumulative energy consumption in the life cycle. For the calculation of the ecological component of the LCA analysis the cumulative CO2 emission has been applied. At present it is the basic emission factor for the LCA analysis of power plants. The work also presents the sensitivity analysis of calculated energy and ecological factors.