Pulverized Coal Fired Power Plant Research Articles

Thermodynamic analysis and life cycle assessment of supercritical pulverized coal-fired power plant integrated with No.0 feedwater pre-heater under partial loads

With ever increasing share of renewable energy sources in the electricity mix, pulverized coal-fired power plants (PCPP) have to participate in peak load regulations frequently and thus, they regularly operate under partial loads. The energy efficiency and eco-efficiency are both significantly affected by such operating patterns. Therefore, the present work aims to establish an overall concept for the estimation of environmental impacts from PCPP under nominal and partial loads with combined thermodynamic analysis and life cycle assessment (LCA) methodology. A 1000 MW supercritical PCPP was modeled using commercial simulation software (GSE for thermodynamic simulation and SimaPro for LCA analysis). Results indicated that global warming was the predominant environmental impact of PCPP, while ozone formation, acidification and eutrophication were also serious concerns attributed to NOx emissions in electricity generation process. The mechanisms of formation, migration and removal of different kinds of pollutant emissions significantly influenced the LCA results. Particularly, the total environmental impact potential considerably increased by approximately 90% under partial/low loads due to reductions in the plant thermal efficiency and NOx removal efficiency. A novel partial load No.0 feedwater preheating system driven by steam ejector was thus proposed for NOx reduction improvement. Operation optimization was carried out based on the guidelines of the LCA framework. It was found that the total environmental impact could be effectively reduced by up to 27.3%. Therefore, the implementation of the No.0 feedwater pre-heater was favorable for environmental performance improvement under partial/low loads.

Dual phase high-temperature membranes for CO2 separation - performance assessment in post- and pre-combustion processes.

Dual phase membranes are highly CO2-selective membranes with an operating temperature above 400 °C. The focus of this work is to quantify the potential of dual phase membranes in pre- and post-combustion CO2 capture processes. The process evaluations show that the dual phase membranes integrated with an NGCC power plant for CO2 capture are not competitive with the MEA process for post-combustion capture. However, dual phase membrane concepts outperform the reference Selexol technology for pre-combustion CO2 capture in an IGCC process. The two processes evaluated in this work, post-combustion NGCC and pre-combustion IGCC, represent extremes in CO2 partial pressure fed to the separation unit. Based on the evaluations it is expected that dual phase membranes could be competitive for post-combustion capture from a pulverized coal fired power plant (PCC) and pre-combustion capture from an Integrated Reforming Cycle (IRCC).

Steady state modeling on energy and exergy analysis of a pulverized coal fired thermal power plant

AbstractSteady state concept has relevance in many fields, particularly in economics, engineering and thermodynamics. In a steady state system, the recent observed behavior will continue to be so in future. Energy and exergy analysis (first and second law of thermodynamic) in steady state condition of a thermal power plant provides in‐depth information to find out areas for potential improvement in efficiency. This study deals with the performance analysis of a pulverized coal fired power plant using energy and exergy analysis in steady state condition. The overall plant performance is assessed by undertaking detailed modeling and simulating thermal cycle of the plant scheme. Off design energy and exergy utilization efficiencies and thermodynamic properties are assessed from the model simulation based on actual operating data collected from the plant Distributed Control System (DCS) at operating load of 460 MW on 15‐min average for a period of 8 h. The analysis revealed that the combustion chamber and boiler are the major source of exergy destruction with 40.29% and 53.20% respectively. Whereas gross energy and exergy efficiency of overall plant are calculated as 34.33% and 31.47% at 460 MW gross generation as compared to the design rating of 37.77% and 34.53% respectively at 500 MW. This paper deals with methodology and assessment of exergy destruction in the plant and how to reduce it. Simultaneously a comparison has been made of energy losses vis‐a‐vis exergy destruction of various plant components, which brings out advantages of using exergy method over energy method calculation. Copyright © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.

Conception of a Pulverized Coal Fired Power Plant with Carbon Capture around a Supercritical Carbon Dioxide Brayton Cycle

Power generation efficiency penalty is the main concern about carbon capture technologies. Improvement of power plant efficiency due to higher steam condition is frequently foreseen to outbalance the carbon capture penalty. This work focuses on the conceptual design of two coal-fired power plants using CO2 as working fluid: one with post- combustion MEA-based CO2 capture and one with oxy-combustion CO2 capture with cryogenic air separation. Two maximal supercritical CO2 temperatures are investigated (620 and 700°C). The combination of a Brayton supercritical CO2 power cycle, a coal boiler and a capture process allows significant increase of the overall plant efficiency. Both post-combustion and oxy-combustion capture processes lead to a very high overall plant efficiency: approximately 41.5% for a 620°C power cycle and 44.5% for a 700°C power cycle. Oxy-combustion seems best fitted for supercritical CO2 Brayton cycle due to a simpler thermal integration and the CO2 purification devices already integrated in the CO2 processing unit. Main resulting technological challenges are the very large heat exchanger needed in the CO2 cycle in order to achieve high power cycle efficiency and the development of supercritical CO2 turbine significantly different than steam or gas turbine especially because of the very large effort on wheel and the small size of the equipment. Numerous technological developments on process component will be necessary and a representative CO2 cycle pilot plant will be needed to assess CO2 leakage, corrosion and flexibility issues.

Experimental reconstructions of flame temperature distributions in laboratory-scale and large-scale pulverized-coal fired furnaces by inverse radiation analysis

Two-dimensional (2-D) and three-dimensional (3-D) temperature distributions in laboratory-scale and large-scale pulverized-coal fired furnaces were reconstructed experimentally by means of CCD cameras through the inverse radiation analysis. The reconstruction technique was developed based on the backward Monte Carlo method. The reconstruction matrix equation was solved by the least square QR decomposition (LSQR) method. The numerical reconstructions were utilized for checking the validity of inverse method before each experimental reconstruction. The experimental reconstruction results were compared with those in references. The temperature distributions for both laboratory-scale and large-scale pulverized-coal fired furnaces can be numerically reconstructed well, and the experimentally reconstructed temperature distributions can reasonably reproduce the main features of actual temperature distributions in the pulverized-coal fired furnaces. The reconstruction technique also has a good ability of on-line temperature distributions reconstruction and monitoring, and will be useful for the combustion diagnostics and control of pulverized-coal fired power plant.

F112 半炭化木質ブリケット燃料のGHG削減効果と最適成形条件(OS3 バイオマス・新燃料・環境技術)

The purpose of this study is to develop "Semi-Carbonized Wood-Briquette Fuels (SCWB)" used in the Pulverized coal fired power plant. This study was conducted to clarify reduction effect in GHG for co-combustion in the coal fired power plants and optimum molding conditions of Biomass solid fuels. The experimental results obtained are as follows. (1) Optimum molding temperature of SCWB: Density of SCWB has the highest value when consolidated at thermo-fluid occurrence temperature of material. (2) Reduction effect in GHG: SCWB has the highest reduction of GHG owing to its higher bulk density and better grindability than other fuels. It is found that SCWB are appropriate for co-combustion in the Pulverized coal fired power plant.

Hybrid coal-fired power plants with CO2 capture: A technical and economic evaluation based on computational simulations

Pulverized coal-fired (PC) power plants are the major technology used to generate electricity for power generation around the world. These processes are generally considered to make a significant contribution to global climate change since they have high CO2 emissions, with the exception of those coal-fired power plants that employ CO2 capture and storage (CCS) technology.With regard to coal-fired power plants, two main options for capturing CO2 from flue gases can be adopted, namely post-combustion and oxy-fuel combustion systems. The former technology option separates CO2 from the flue gas generated by the combustion of coal with air. For chemical absorption, generally a solvent such as MEA is used. However, there is a serious concern about the energy consumption required for regeneration of the solvent MEA. Oxy-fuel combustion systems, on the other hand, involve separating the oxygen from air and then burning the coal in a mixture of pure oxygen and recycled flue gas. This approach reduces the amount of flue gas substantially and simplifies the separation process due to the absence of nitrogen and argon in the stream. However there are some drawbacks in connection with some components, such as air separation units (ASU), which require high capital and operating costs and are energy intensive.A new idea was proposed by Zanganeh et al. [1]. This was a hybrid of oxy-combustion and post-combustion capture and would use air with O2 enrichment. Such PC power stations would use an ASU plant to obtain O2 enrichment and would still require the CO2 purification and compression processes. The ASU plant would be smaller than for oxy-fuel and the CO2 purification and compression systems would be smaller than for air-firing. This paper is to evaluate the proposed process technically and economically based on detailed simulation. The hybrid coal-fired power plant with CO2 capture system has the potential advantage of reducing energy consumption and costs. To explore the advantages and disadvantages of the hybrid process with CO2 capture, a comparative analysis of the supercritical PC power plant is carried out. The technical design and the mass and energy balances are implemented by using the ECLIPSE simulation package.

B110 STUDY RESULTS OF OXYFUEL COMBUSTION ON CALLIDE OXYFUEL PROJECT : ACTIVITIES TOWARD THE COMMERCIALIZATION OF OXYFUEL COMBUSTION SYSTEM(Combustion-3)

Oxyfuel combustion is expected to be one of the promising systems on CO_2 capture from pulverized-coal fired power plant, and enable the CO_2 to be captured in a more cost-effective manner compared to other CO_2 capture process from the power plant. The demonstration project (Callide Oxyfuel Project) on this field is now under way for applying oxyfuel combustion to an existing plant that is the power generation system in Callide-A power plant No.4 unit with a capacity of 30M We in Australia. One of main objectives of this project is to capture CO_2 from an actual power plant for CO_2 storage. At present, the studies toward the commercialization plant through this demonstration project on this area are implemented. In this paper, the activities for the approach on the commercialization for the oxyfuel combustion are mainly introduced and the current situation of Callide Oxyfuel Project is also outlined.

木質バイオマスの粉砕エネルギーと輸送性評価に及ぼす半炭化熱分解の影響

In order to promote the utilization of unused woody biomass such as forestry biomass and pruned branch of fruit, the utilization of woody biomass has come to attract attention as a fuel at the pulverized-coal fired power plant. When the woody biomass in the forestry region is utilized, it is necessary to examine and reduce the energy consumption for collecting of resources, preprocessing such as comminuting and drying and transportation . In the present study, effect of semi-carbonization pyrolysis on comminution energy and assessment of transport property of woody biomass is investigated. The results obtained are as follows. Empirical correlations of work index in Bond′s Law are presented for both woody and semi-carbonization regions. The comminution energy can be estimated by the present empirical correlations within an accuracy of ±30 percent. To evaluate the effect of semi-carbonization process on the energy reduction of transport and comminution, an analysis of energy consumptions is conducted. From the result of analysis, it is found that the energy consumption ratio is the minimum at a mass yield condition of 0.6 for the same transport distance.

Effects of H2O, SO2, and NO on Homogeneous Hg Oxidation by Cl2

Several researchers have determined that water (H2O) and sulfur dioxide (SO2) in a flue gas stream have an impact on the amount of elemental mercury (Hg0) that is homogeneously oxidized by a chlorine-containing species. Generally, it is concluded that H2O inhibits Hg oxidation by chlorine (Cl2). However, doubt remains as to whether SO2 promotes or inhibits Hg oxidation. Further, most published results seem to indicate that nitric oxide (NO) does not have a significant impact on Hg oxidation. This paper will present data taken in a laboratory-scale apparatus designed to test these observations. In this work, Cl2 is intentionally added to a synthetic flue gas stream containing known amounts of elemental mercury. This gas blend is similar to a flue gas obtained by burning Powder River Basin coal in a pulverized coal fired power plant and is subject to a time−temperature profile similar to a power plant. The results obtained show that H2O, SO2, and NO all have an inhibitory effect on the homogeneous oxidation of Hg by Cl2. Further, the presence of H2O increases the inhibitory effect of SO2 and NO. Two new reactions are proposed to explain these results, in which SO2 and NO react with Cl2. The consequences of these reactions are a reduction in the oxidative interactions that take place between Hg and Cl2, thus decreasing the amount of Hg oxidation that occurs.

4305 微粉炭火力からの高効率CO_2回収システム(酸素燃焼技術)の燃焼特性(S62-2 高効率石炭火力発電(2),S62 高効率石炭火力発電)

Pulverized-coal combustion under oxygen and recycle flue gas (Oxy-fuel combustion) is expected to be one of the promising systems on CO_2 recovery from pulverized-coal fired power plant. The research and development on Oxy-fuel combustion technology had advanced under the Clean Coal Technology Program from 1992. It can be suggested through these studies that Oxy-fuel combustion system is the economical and effective systems for CO_2 recovery from the pulverized-coal fired power plant. Feasibility study has been now carried out toward the demonstration of Oxy-fuel. Combustion test of three kinds of Australian coal was carried out using the pilot-test facilities in order to confirm the flame stability and combustion characteristics in it. In this paper, we introduce the test results with both air and oxy-fuel combustion.

Effect of Flow Distributors on Uniformity of Velocity Profile in a Baghouse

In recent years, the utility industry has turned to bag-houses as an alternative technology for particulate emission control from pulverized-coal–fired power plants. One of the more significant issues is to improve poor gas distribution that causes bag failures in baghouse operation. Bag failures during operation are almost impossible to prevent, but proper flow design can help in their prevention. This study investigated vertical velocity profiles below the bags in a baghouse (the hopper region) to determine whether flow could be improved with the installation of flow distributors in the hopper region. Three types of flow distributors were used to improve flow distribution and were compared with the original baghouse without flow distributors. Velocity profiles were measured by a hot-wire anemometer at an inlet velocity of 18 m/sec. Uniformity of flow distribution was calculated by the uniformity value U for the velocity profile of each flow distributor. Experimental results showed that the velocity profile of the empty configuration (without flow distributors) was poor because the uniformity value was 2.048. The uniformity values of type 1 (flow distributor with three vertical vanes), type 2 (flow distributor with one vertical and one inclined vane), and type 3 (flow distributor with two inclined vanes) configurations were reduced to 1.051, 0.617, and 0.526, respectively. These results indicate that the flow distributors designed in this study made significant improvements in the velocity profile of a baghouse, with the type 3 configuration having the best performance.

3628 既設微粉炭火力からの高効率CO_2回収 : 酸素燃焼技術の紹介と現在の取組み(S54 高効率石炭火力発電技術)

Pulverized-coal combustion under oxygen and recycle flue gas (Oxy-fuel combustion) is expected to be one of the promising systems on CO_2 recovery from pulverized-coal fired power plant. The research and development on Oxy-fuel combustion technology had advanced under the Clean Coal Technology Program from 1992. It can be suggested through these studies that Qxy-fuel combustion system is the economical and high efficiency systems for CO_2 recovery from the pulverized-coal fired power plant. Feasible study is now advanced on the application of this technology to the actual existing power plant in Australia. In this paper, we introduce the results of previous study on the conceptual design of the boiler and the outline of current feasible study.

Characteristics of Pulverized-Coal Combustion in CO2-Recovery Power Plant Applied O2/CO2 Combustion.

The system of oxygen/recycled flue gas combustion for the removal of carbon dioxide from pulverized-coal fired power plants, the combustion characteristics of pulverized coal, and the trial designing of a 1 000 MWe pulverized-coal power plant were studied. The flame propagation speed of pulverized-coal cloud was measured in a microgravity combustion chamber at O 2 /CO 2 , O 2 /N 2 and O 2 /Ar atmosphere. NO x and SO 2 emissions from the system were investigated in the industrial scale combustion test facilities. Based on these results and the previous works, the trial designing of a 1 000 MWe pulverized--coal fired power plant applying this combustion system was also studied. As for the heat absorption performance of the boiler furnace, a 3 dimensional numerical analysis was applied to a large utility boiler furnace. It was compared with another promising system CO 2 -recovery, pulverized-coal power plant combined with amine absorption process.

24 O 03 Continuous particle emission mass monitoring in a pulverized coal fired power plant

24 O 03 Continuous particle emission mass monitoring in a pulverized coal fired power plant