Coal-fired Power Plant Flue Gas Research Articles

Techno-Economic Assessment of Novel vs. Standard 5m Piperazine CCS Absorption Processes for Conventional and High-efficiency NGCC Power Plants

CO2 capture and storage (CCS) can play a key role in the mitigation of greenhouse gas emissions, as it is generally applicable to many industrial sectors to limit the environmental impacts from fossil fuels usage. In this regard, natural gas-fired power plants are a suitable application for CCS technologies, although they produce flue gases with a much lower CO2 concentration (i.e. ~4 %mol) than coal-fired power plant flue gases. Amine-based solvent absorption has been widely studied as a practical solution to decarbonize post-combustion flue gases from natural gas combined cycle power plants (NGCC). This paper presents the methodology and the results of a techno-economic assessment of 5 molal (5m) piperazine (PZ) as a new potential baseline solvent for carbon capture from NGCC in three different case studies that have been considered relevant from a preliminary literature analysis. The three evaluated configurations are (i) conventional F-class NGCC coupled with the conventional absorber configuration with a direct contact cooler (DCC), (ii) conventional F-class NGCC coupled with an advanced absorber configuration (no DCC – flue gas cooling integrated within the absorber) and (iii) high efficiency, state-of-the-art H-class NGCC, coupled with the advanced absorber configuration. The present work is based on the most recent findings from University of Texas at Austin (UT) research activities, and it has been carried out by Laboratorio Energia e Ambiente Piacenza (LEAP) and Politecnico di Milano (POLIMI) researchers supported and sponsored by the CO2 Capture Project (CCP).

Testing the stability of novel adsorbents for carbon capture applications using the zero length column technique

In this paper, a semi-automated ZLC technique was used to study the stability of novel adsorbents in the presence of water, SOx and NOx impurities present in coal-fired power plant flue gas. The tests were carried out at 38°C and 0.1bar pressure on the most promising materials of the M/DOBDC ((M=Co, Ni, Mg)) MOF series, as well as on commercial 13X zeolite pellets. The experimental results indicated that even if the DOBDC family shows high CO2 adsorption capacity at low partial pressure at ambient conditions, impurities have a strong effect on their stability. The ZLC system provides quantitative information on the deactivation of samples due to SOx and NOx in a relatively short time and using less than 15mg of sample. The fact that the treatment can be repeated in situ in the apparatus used also for measuring the CO2 capacity of the sample has shown that the ZLC can be a valuable tool in screening novel adsorbents for carbon capture applications.

Application of Spent H2S Scavenger of Iron Oxide in Mercury Capture from Flue Gas

A commercial H2S scavenger of iron-oxide base, namely TG-4 in the Chinese market, was found to have activity for mercury (Hg) capture from flue gas after its use in H2S removal. The technical feasibility of using this industrial spent material to replace expensive activated carbon for mercury capture from coal-fired power plant flue gas was studied in this paper. The effects of temperature, space velocity, and compositions of the flue gas on the efficiency of Hg removal was investigated using a packed-bed tubular reactor on the benchtop scale. The mercury sorbents prepared from the spent TG-4 H2S sorbent were characterized by sulfur measurement, thermogravimetric and differential thermal analysis (TG-DTA), and X-ray absorption spectroscopy (XAS). The Hg L3-edge XAS was used to analyze the material after its contact with Hg. The results show that the spent TG-4 can efficiently remove elemental mercury from the gas at a temperature range between 80 and 240 °C and at reasonable space velocity. The efficiency...

Poly(ionic liquid)/Ionic Liquid Ion-Gels with High "Free" Ionic Liquid Content: Platform Membrane Materials for CO2/Light Gas Separations.

The recycling or sequestration of carbon dioxide (CO2) from the waste gas of fossil-fuel power plants is widely acknowledged as one of the most realistic strategies for delaying or avoiding the severest environmental, economic, political, and social consequences that will result from global climate change and ocean acidification. For context, in 2013 coal and natural gas power plants accounted for roughly 31% of total U.S. CO2 emissions. Recycling or sequestering this CO2 would reduce U.S. emissions by ca. 1800 million metric tons-easily meeting the U.S.'s currently stated CO2 reduction targets of ca. 17% relative to 2005 levels by 2020. This situation is similar for many developed and developing nations, many of which officially target a 20% reduction relative to 1990 baseline levels by 2020. To make CO2 recycling or sequestration processes technologically and economically viable, the CO2 must first be separated from the rest of the waste gas mixture-which is comprised mostly of nitrogen gas and water (ca. 85%). Of the many potential separation technologies available, membrane technology is particularly attractive due to its low energy operating cost, low maintenance, smaller equipment footprint, and relatively facile retrofit integration with existing power plant designs. From a techno-economic standpoint, the separation of CO2 from flue gas requires membranes that can process extremely high amounts of CO2 over a short time period, a property defined as the membrane "permeance". In contrast, the membrane's CO2/N2 selectivity has only a minor effect on the overall cost of some separation processes once a threshold permeability selectivity of ca. 20 is reached. Given the above criteria, the critical properties when developing membrane materials for postcombustion CO2 separation are CO2 permeability (i.e., the rate of CO2 transport normalized to the material thickness), a reasonable CO2/N2 selectivity (≥20), and the ability to be processed into defect-free thin-films (ca. 100-nm-thick active layer). Traditional polymeric membrane materials are limited by a trade-off between permeability and selectivity empirically described by the "Robeson upper bound"-placing the desired membrane properties beyond reach. Therefore, the investigation of advanced and composite materials that can overcome the limitations of traditional polymeric materials is the focus of significant academic and industrial research. In particular, there has been substantial work on ionic-liquid (IL)-based materials due to their gas transport properties. This review provides an overview of our collaborative work on developing poly(ionic liquid)/ionic liquid (PIL/IL) ion-gel membrane technology. We detail developmental work on the preparation of PIL/IL composites and describe how this chemical technology was adapted to allow the roll-to-roll processing and preparation of membranes with defect-free active layers ca. 100 nm thick, CO2 permeances of over 6000 GPU, and CO2/N2 selectivity of ≥20-properties with the potential to reduce the cost of CO2 removal from coal-fired power plant flue gas to ca. $15 per ton of CO2 captured. Additionally, we examine the materials developments that have produced advanced PIL/IL composite membranes. These advancements include cross-linked PIL/IL blends, step-growth PIL/IL networks with facilitated transport groups, and PIL/IL composites with microporous additives for CO2/CH4 separations.

Method of flash evaporation and condensation – heat pump for deep cooling of coal-fired power plant flue gas: Latent heat and water recovery

Flue gas waste heat recovery and utilization is an efficient means to improve the energy efficiency of coal-fired power plants. At present, the surface corrosion and fouling problems of heat exchanger hinder the development of flue gas deep cooling. In this study, a novel flue gas deep cooling method that can reduce flue gas temperature below the dew point of vapor to recover latent heat and obtain clean water simultaneously is proposed to achieve improved energy efficiency. The heat transfer mode of this method is the direct contact mode, which takes the scrubber, e.g. the flue gas desulfurization (FGD) scrubber, as the deep cooling exchanger. The flash evaporation and condensation (FEC) device and heat pump (HP) are utilized to provide low-temperature medium, such as FGD slurry or water, for washing and deep cooling flue gas, to collect recovered water, and to absorb recovered waste heat. This method is called as the FEC–HP method. This paper elaborated on two optional models of the proposed method. The mechanism for recovering heat and water was also analyzed using the customized flue gas humidity chart, and the method to quantitate recovered heat and water, as well as the results of the case of a 300MW coal-fired generator set were provided. Net present value calculations showed that this method is profitable in the scenario of burning high-water-content coals. Several potential advantages of this method and suggestions for practical application were also discussed.

Qualitative and quantitative characterization of a coal power plant waste by TG/DSC/MS, XRF and XRD

SO2 removal from coal-fired power plant flue gases can be done by dry, semi-dry or wet desulphurization processes, using limestone or lime-containing products as sorbents. In a Brazilian coal power plant, there is a dry desulphurization unit to capture SO2 with hydrated lime from the combustion gases. A part of the flying ashes produced is mixed with the bottom coal ashes and the spent sulphated product generated after SO2 capture. This residual solid blend is then buried in a non-productive area, from which coal was already extracted and is studied in this work. According to the authors’ experience in the development and characterization of adsorbents for low-temperature dry desulphurization processes and in thermogravimetric analysis, this paper shows and discusses a method which was developed to characterize qualitatively and quantitatively the chemical and mineral composition of this waste by using thermogravimetry coupled with mass spectrometry, X-ray fluorescence and X-ray diffraction, to preview new potential industrial applications for this waste.

Impact of Catalyst Performance on the Life-Cycle CO2 Emissions of Methanol Production By Direct Electrocatalytic Reduction of CO2

Direct electrocatalytic reduction of carbon dioxide (eCO2RR) is one technology being developed to convert solar photovoltaic power into energy-dense, easily dispatchable liquid fuels. In addition to providing a stable and energy-dense storage medium for solar energy, fuels synthesized using solar energy and CO2 would provide a non-fossil, low-emissions route to liquid fuels for a carbon-constrained future. Although extensive basic science research is focused on eCO2RR catalyst development, the full life-cycle emissions of this technology platform have not been quantified. In particular, the relative importance of catalyst performance improvements, compared to other system parameters, for the emissions profile of a large-scale eCO2RR process have not been analyzed in the literature.This work uses a hybrid life cycle assessment (LCA) approach to estimate how the choice of catalyst material and the performance of the catalyst influence the life cycle CO2 emissions associated with producing methanol by the eCO2RR process. Methanol is a potential drop-in transportation fuel, useful in both combustion engines and fuel cells. In this analysis, the CO2 reduction electrocatalyst and its carbonaceous support are explicitly modeled using process-based LCA. For the balance of the CO2 reduction cell system, a water electrolyzer is used as a surrogate technology, and incorporated using input-output LCA.The CO2 emissions intensity of methanol produced by a prospective direct CO2 electrocatalytic reduction process are dominated by the emissions intensity of the electrical power used to carry out the electrocatalytic reduction. The emissions intensity is strongly influenced by the electrocatalyst's faradaic efficiency for the desired methanol product, but is only weakly sensitive to catalyst overpotential and current density. Ancillary processes such as CO2 capture and product methanol purification generate only a small fraction of the total emissions. In a preliminary analysis, the total system CO2 emissions are 1.24 g CO2 emitted / g methanol, and 97% of these emissions are from generating the electricity used to drive the electrocatalytic reduction. (In contrast, methanol production from conventional natural gas reforming has an emissions intensity of 0.50–0.67 g CO2 emitted / g methanol.) The CO2 capture process, the product purification process, and the embodied emissions in the process equipment each contribute 2% or less to the CO2 intensity of the methanol product. The CO2 intensity of the product is therefore influenced by those technical parameters relevant to the generation and use of the electric power, especially the CO2 intensity of the electricity and the faradaic efficiency of the cathode catalyst for the desired methanol product. Doubling the faradaic efficiency from 25% to 50% would reduce the CO2 intensity by one-third (from 1.24 to 0.79 g CO2 emitted / g methanol). The emissions intensity is only moderately sensitive to catalyst overpotential: decreasing the cathode potential by about one third, from –0.8 V to –0.5 V, would decrease the emissions intensity by about one tenth (from 1.24 to 1.12 g CO2 emitted / g methanol). If the feedstock CO2 is provided from direct air capture instead of flue gas, the total emissions intensity of the methanol would be higher: at least 1.74 g CO2 emitted / g methanol, if the direct air capture process is powered by renewable energy sources, and higher still if powered by fossil sources. The reference case eCO2RR system in this analysis contains a nanoparticulate copper catalyst (100 nm particle diameter) that reduces CO2 to methanol with 25% faradaic efficiency, a current density of 0.5 A cm-2, and 0.8 V of overpotential. The anode reaction is water oxidation, carried out with 0.3 V of overpotential. The feedstock CO2 provided to the reduction cell is captured from coal-fired power plant flue gas, with an emissions intensity of 97 g CO2 emitted / g CO2 captured. The emissions intensity of the electricity that powers the electrocatalytic reduction is 20 g/kWh, typical of photovoltaic generation.

Cyclic stability testing of aminated-silica solid sorbent for post-combustion CO2 capture.

The National Energy Technology Laboratory (NETL) is examining the use of solid sorbents for CO2 removal from coal-fired power plant flue gas streams. An aminated sorbent (previously reported by the NETL) is tested for stability by cyclic exposure to simulated flue gas and subsequent regeneration for 100 cycles. Each cycle was quantified using a traced gas in the simulated flue gas monitored by a mass spectrometer, which allowed for rapid determination of the capacity.

Coal-Fired Power Plant Flue Gas Desulfurization Wastewater Treatment

Coal-Fired Power Plant Flue Gas Desulfurization Wastewater Treatment

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.

燃煤电厂排烟粉尘浓度在线监测方法

燃煤电厂烟气污染物排放到大气中，这不仅关系到环境问题，而且直接危害人们身体的健康。因此粉尘浓度的测量越来越重要。本文采用支持向量机软测量技术，利用支持向量机的非线性映射和强大的泛化能力，建立排烟粉尘浓度的软测量模型，实现粉尘浓度的最佳估计。仿真结果表明该方法可以对粉尘浓度进行有效估计，可以作为粉尘浓度的在线监测方法。Coal-fired power plant flue gases are discharged into the atmosphere without treatment, which not only aggravates environmental issues, but also directly endangers people’s physical health. So the measurement of dust concentration becomes more and more important. In this paper, strong nonlinearity mapping and generalization ability of support vector machine soft-sensing technique is used to establish soft-sensing model and to reach best estimate of dust concentration. Simulation results show that this method can estimate the dust concentration effectively and it can be applied to online monitoring of dust concentration.

Advanced Solid Sorbent-Based CO2 Capture Process

Abstract RTI International, Masdar, and Pennsylvania State University (PSU) are leading an effort to develop an advanced solid sorbent- based CO2 capture process for application to exhaust gas from various industrial sources – including coal-fired power plant flue gas. The technical and economic hurdles to solid sorbent CO2 capture are being addressed through transitioning a promising sorbent chemistry (based on supported amines) to a low-cost sorbent suitable for use in a fluidized-bed process. In parallel, a scalable circulating fluidized-bed process arrangement is being developed. Efforts have focused on improving sorbent stability and performance, converting sorbents to a fluidizable form, producing large quantities (100+ kg) of sorbent through scalable methods, and evaluating the viability of new process designs through bench-scale testing using simulated coal-fired flue gas.

Electrochemical CO2 Capture Using Resin-Wafer Electrodeionization

Energy-efficient capture of CO2 from power-plant flue gas is one of the grand challenges to reduce greenhouse gas (GHG) emissions. Current CO2-capture technologies are limited by parasitic energy loss, inefficient capture, and unfavorable process economics. We present a novel electrochemical method for CO2 capture from coal-fired power-plant flue gas. The method utilizes in-situ electrochemical pH control with a resin wafer electrodeionization (RW-EDI) device that continuously shifts the pH of the process fluid between basic and acidic in sequential chambers (pH swing). This pH swing enables capture of CO2 from flue gas in the basic chamber followed by release (recovery) of the captured CO2 (purified) in the acidic chamber of the same device. The approach is based on the sensitivity of the thermodynamic equilibrium of CO2 hydration/dehydration reactions over a narrow pH range. The method enables simultaneous absorption (capture) of CO2 from flue gas and desorption (release) at atmospheric pressure without heating, vacuum, or consumptive chemical usage. In other words, the method concentrates CO2 from ∼15% in flue gas to >98% in the recovery stream. To the best of our knowledge, this is the first experimental study focusing on simultaneous capture and release (recovery) of CO2 using an electrochemical method. We describe the method, the role of operating parameters on CO2 recovery, and advancements in process design and engineering for improved efficiency. We report on a method to enhance gas/liquid mixing inside the RW-EDI, which significantly increased CO2 capture rates. We also discuss the importance of using an enzyme/catalyst in enhancing the reaction kinetics. CO2 capture was observed to be a strong function of gas and liquid flow rates and applied electrical field. Up to 80% of the CO2 was captured from a simulated flue gas stream with >98% purity. The results indicate that a narrow pH swing from 8 to 6 (near-neutral pH) could offer a viable pathway for energy-efficient CO2 capture if the reaction kinetics are enhanced. Carbonic anhydrase enzyme enhances the reaction kinetics at near-neutral pH; however, the enzyme lost activity due to the instability at the operating conditions. This observation highlighted the necessity of robust enzymes/catalysts to enhance kinetics of CO2 recovery near-neutral pH.

Research Summarize about Controlling Technology of Ultrafine Powder

PM2.5has serious harm to human health and the environment, coal-fired power plant flue gas emission is one of the important sources of PM2.5, however dust removal equipment for PM2.5and finer particulate collection efficiency is very low.Mixed dust removal technology have various problems such as cost increasing , complex operation, the material requirements and capture efficiency of fine particle is not obvious. Coagulation as an effective method of collecting sub-micron particles, has good prospects for development.Further study of the mechanism of coagulation and coagulation technology in practical application of industrial production became focus of future research.

The Nature of Adsorbed CO2 and Amine Sites on the Immobilized Amine Sorbents Regenerated by Industrial Boiler Steam

The nature of adsorbed CO2 on immobilized amine sorbents regenerated with utility boiler steam was studied by in-situ infrared spectroscopy. The use of industrial boiler steam is the key factor lowering the overall operating cost of the immobilized amine CO2 capture process for megawatt-scale coal-fired power plants. The industrial steam is known to contain trace amounts of Cu, Fe, and Zn species. The present study was undertaken to understand the chemistry occurring between the Cu contaminants in the steam and the amine sites on the sorbent. Cu-containing steam from the utility boilers resulted in a 91% loss of CO2 capture capacity over 30 continuous CO2 capture and regeneration cycles. UV–vis and in-situ IR studies suggest that the degraded sorbent contained CuII ions coordinated with nitrogen atoms of an imine species. These imine species are incapable of adsorbing CO2. The remaining amine species could bind weakly with CO2, mainly in the form of carbamic acid. The formation of ammonium ion species was inhibited by adsorbed Cu species on the degraded sorbent. Cu-free steam is required for stripping adsorbed CO2 from the amine sorbent in the CO2 capture process. The findings presented here should be considered before implementing a pilot-scale CO2 capture process from coal-fired power plant flue gas.

The Effect of Curing System on Mechanical Properties of Desulphurization Gypsum-Slag Composite Binder

Desulphurization gypsum-slag composite binder is a hydraulic composite binding material made by slag, desulphurization generated by coal-fired power plant flue gas desulphurization, activator and other materials. In order to study the effect of curing system on the composite binder, steam curing, autoclave curing, nature curing, standard curing and water curing were selected. The mechanical properties of desulphurization gypsum-slag composite binder were compared, and the best curing system for strength development was proposed.

Effects of SO2 on CO2 capture using a hollow fiber membrane contactor

Membrane gas absorption technology is a promising alternative to conventional technologies for the mitigation of acid gases. In this study, with a polypropylene (PP) hollow fiber membrane contactor as absorber and a packed column as stripper, the influence of SO2 on the CO2 capture from coal-fired power plant flue gas was investigated in an absorption–desorption experimental set-up using aqueous monoethanolamine (MEA) as the absorbent. The experimental results showed that the MEA loss per ton captured CO2 increased with the addition of SO2, resulting in sharp decreases in CO2 removal efficiency and mass transfer rate of CO2 after initial several days of operation. This tendency is mainly attributed to the promotional effect of SO2 on the degradation of MEA by the formation of sulfate. Thus, it is necessary to regenerate MEA using a reclaimer in this case. The respective SO2 concentrations at the outlets of absorber and stripper remained constant values of 24 and 120ppb throughout the operation although the CO2 removal efficiency decreased dramatically with time. This co-capture of CO2 and SO2 could play an important role in further desulfuration, thus alleviating the burden of desulfuration to some extent and benefiting the subsequent CO2 purification and storage. More progresses are greatly needed in high-efficiency and stable absorbents, high-efficiency reclaimer, and methods to reduce MEA loss by evaporation.

Membrane processes for carbon capture from coal-fired power plant flue gas: A modeling and cost study

Favorable economics of electricity generation will be crucial to the successful implementation of post-combustion carbon capture. Hence, the US DOE has set a goal of <35% for the increase on the cost of electricity (COE) due to CO2 capture. For meeting this goal, there is thus a growing need to perform a cost analysis of emerging separation methods. This paper goes through a detailed modeling and cost-sensitivity study of a promising membrane-based process for carbon capture: the air-sweep process. We have studied the impact of membrane performance, selectivity and permeance, on the COE increase and the capture cost. The effects of operating parameters as well as the membrane price on the overall cost were determined. Cost calculations show a COE increase of about 33% along with a capture cost of <$24/t CO2 for the air-sweep process to achieve 90% CO2 recovery and 95% purity of the CO2 product. This process operates at close to atmospheric feed pressure and requires a low membrane module price of $27/m2, a CO2/N2 selectivity of about 140 combined with a high CO2 permeance of 3000GPU. Although the required membrane properties have not yet been achieved, this research emphasizes quantitatively the need to improve the present membranes to realize a purely membrane-based process for the above application.

Analysis of K2CO3/Al2O3 CO2 sorbent tested with coal-fired power plant flue gas: Effect of SOx

The mass produced K2CO3/Al2O3 sorbents were tested for their CO2 sorption capacity by a 2000Nm3/h (0.5MW) CO2 capture pilot plant, which was built for unit 3 of Hadong thermal power station in 2010. After the commissioning, CO2 capture pilot plant was tested with the flue gas from the power station for 60days. To assess the effect of SOx in the flue gas of coal-fired power plant on the sorbent, the new and used K2CO3/Al2O3 sorbents were analyzed by FE-SEM, IC, EPMA, XRD and XPS. The results show that SOx of 10–40ppm in flue gas was reacted with K2CO3, but not with any other support materials, and formed K2SO4. And also, it is proved that the formed K2SO4 was quite stable in the range of 180–550°C.

Oxidative Degradation of Aminosilica Adsorbents Relevant to Postcombustion CO2 Capture

Coal-fired power plant flue gas exhaust typically contains 3–10% oxygen. While it is known that the monoethanolamine (MEA) oxidative degradation rate is a critical parameter affecting liquid amine ...