Coal-fired Power Plants In China Research Articles

Post-combustion capture of CO2 from coal-fired power plants in China and Australia: An experience based cost comparison

Abstract A techno-economic comparative assessment is made for an amine based post-combustion capture (PCC) process applied to representative coal-fired power plants in Australia and China. The assessment is based on an in-depth analysis of the cost of generation. The process and cost models for integrated power and capture plants have been obtained using ASPEN Rate-Sep, Steam-Pro, Steam-Master and PEACE software packages for process modelling and cost estimation. The equipment costs as well as the fuel costs have been based on the national experiences and circumstances. Important differences between PCC in China and Australia have been identified: - the limited environmental controls in existing Australian coal fired power stations requiring a retrofit to include extensive flue gas pre-treatment, - the low fuel cost in Australia as power plants are closely located to coal mines - the low capital costs in China as a result of lower local manufacturing costs. The results indicate that PCC in China can benefit significantly from more energy efficient processes, whereas for the Australian circumstances the focus should be on reduction of capital costs.

Measurement of Mercury in Flue Gas Based on an Aluminum Matrix Sorbent

The measurement of total mercury in flue gas based on an economical aluminum matrix sorbent was developed in this paper. A sorbent trap consisted of three tubes was employed to capture Hg from flue gas. Hg trapped on sorbent was transferred into solution by acid leaching and then detected by CVAAS. Hg adsorbed on sorbent was recovered completely by leaching process. The 87.7% recovery of Hg in flue gas by tube 1 and tube 2 was obtained on the equipment of coal combustion and sampling in lab. In order to evaluate the ability to recover and accurately quantify Hg0 on the sorbent media, the analytical bias test on tube 3 spiked with Hg0 was also performed and got the average recovery of 97.1%. Mercury measurements based on this method were conducted for three coal-fired power plants in China. The mercury in coal is distributed into bottom ash, electrostatic precipitator (ESP) ash, wet flue gas desulfurization (WFGD) reactant, and flue gas, and the relative distribution varied depending on factors such as the coal type and the operation conditions of plants. The mercury mass balances of three plants were also calculated which were 91.6%, 77.1%, and 118%, respectively. The reliability of this method was verified by the Ontario Hydro (OH) method either in lab or in field.

Energy cost and greenhouse gas emissions of a Chinese solar tower power plant

It is commonly assumed that the application of solar power system can save energy and relief global climate change. Presented in this study is the account of energy performance and greenhouse gas emissions of a planned solar tower power plant in China based on the life cycle analysis method. The conservative estimation of energy cost for the concerned plant is 1.21 times of the electricity output, which is a relatively decent performance amongst power generation technologies. In order to analyze the greenhouse gas performance, a comparison is carried out between the solar tower power plant and conventional coal-fired power plant in China. Results show the application of this solar system obtains a net greenhouse gas emission reduction of 0.31E+06 ton CO2 equivalent, during its operating period of twenty years. It is believed that this successful example can lend solid support to a future wide use of solar power in China.

An assessment of the potential for retrofitting existing coal-fired power plants in China

Abstract A consensus for the development of a low carbon economy in China is growing rapidly among Chinese energy stakeholders. But there is considerable uncertainty as to the role that carbon capture and storage (CCS) retrofit could play in this development. The State Council in China has set a target of cutting carbon dioxide emissions per unit of GDP by 40% by 2020 compared with the level for 2005. Although this provides some policy impetus for reducing carbon dioxide emissions in China, it is also important to note that over 350 GW of coal-fired power plant capacity has been built within the past five years and that these power plants are expected to operate for at least another 25 years. Because coal is an affordable and accessible fuel in China, both the China Electricity Council (CEC) and the International Energy Agency (IEA) estimates that another 300 GW of supercritical and ultra-supercritical new coalfired power plants will be constructed in the next decade to satisfy the growing energy demand of the country . But unless other options to reduce emissions can be implemented, a simple consideration of the emissions they produce suggests that some of these recently built power plants may be required to shut down within the next two decades to address Chinese and/or international climate policies. During the past five years, the national policy of ‘closing smaller and/or inefficient units to build large and more efficient units’ has been implemented not only to save energy, but also to reduce specific carbon dioxide emissions (i.e. reduced gCO 2 /kWh of electricity produced). Forcing early plant closure has, however, proved to be a difficult task under the institutional framework of the Chinese electricity sector, because these plants usually had not reached the end of their design lifetimes. Also it was only partially successful in the context of CO 2 reduction in the sense that companies wanted to build large plants to increase electrical output and strict rules meant they could only do this by closing a specified amount of older plant. But the end result was still that more coal was burnt and hence total CO 2 emissions to atmosphere increased. Retrofitting some of the existing power plants to capture CO 2 , which by contrast can achieve an absolute decrease in CO 2 emissions to atmosphere for an analogous loss in plant output (to the closures previously enforced) is therefore, an important option to address the threat of climate change while maintaining in the meantime the country’s electricity supply from coal. A preliminary investigation of over 100 large power plants in China was conducted to determine their potential for a retrofit with CO 2 capture, transport and storage. Factors assessed included geographic location, space on site, plant layout, water restriction, coal supply, efficiency, FGD status and potential access to storage sites. Based on these criteria, retrofitting prospects were evaluated and rated. It appears that about 45% of existing power plants may suffer from ‘carbon lock-in’ status, i.e. their emissions could not be abated using CCS technology, at least at ‘reasonable’ cost. Critical factors that would preclude capture retrofit are, not surprisingly, access to storage sites and unsuitable plant layout and/or space on site. Variations in other factors would affect the level of retrofitting cost, but this effect could be positive as well as negative. In principle, plants would be retrofitted in an order that reflects the extent to which these site specific factors would give higher or lower retrofit costs. The results aim to provide an overview of the potential issues that need to be considered by stakeholders, policy makers and manufacturing companies when deciding the market potential for CCS retrofit technology in China.

Synergistic Mercury Removal by Conventional Pollutant Control Strategies for Coal-Fired Power Plants in China

China’s 11th 5-yr plan has regulated total sulfur dioxide (SO2) emissions by installing flue gas desulfurization (FGD) devices and shutting down small thermal power units. These control measures will not only significantly reduce the emission of conventional pollutants but also benefit the reduction of mercury emissions from coal-fired power plants. This paper uses the emission factor method to estimate the efficiencies of these measures on mercury emission abatement. From 2005 to 2010, coal consumption in power plants will increase by 59%; however, the mercury emission will only rise from 141 to 155 t, with an increase of 10%. The average emission rate of mercury from coal burning will decrease from 126 mg Hg/t of coal to 87 mg Hg/t of coal. The effects of the three desulfurization measures were assessed and show that wet FGD will play an important role in mercury removal. Mercury emissions in 2015 and 2020 are also projected under different policy scenarios. Under the most probable scenario, the total mercury emission in coal-fired power plants in China will decrease to 130 t by 2020, which will benefit from the rapid installation of fabric filters and selective catalytic reduction.

Uncertainties in estimating mercury emissions from coal-fired power plants in China

Abstract. A detailed multiple-year inventory of mercury emissions from anthropogenic activities in China has been developed. Coal combustion and nonferrous metals production continue to be the two leading mercury sources in China, together contributing ~80% of total mercury emissions. However, many uncertainties still remain in our knowledge of primary anthropogenic releases of mercury to the atmosphere in China. In situations involving large uncertainties, our previous mercury emission inventory that used a deterministic approach could produce results that might not be a true reflection of reality; and in such cases stochastic simulations incorporating uncertainties need to be performed. Within our inventory, a new comprehensive sub-module for estimation of mercury emissions from coal-fired power plants in China is constructed as an uncertainty case study. The new sub-module integrates up-to-date information regarding mercury content in coal by province, coal washing and cleaning, coal consumption by province, mercury removal efficiencies by control technology or technology combinations, etc. Based on these detailed data, probability-based distribution functions are built into the sub-module to address the uncertainties of these key parameters. The sub-module incorporates Monte Carlo simulations to take into account the probability distributions of key input parameters and produce the mercury emission results in the form of a statistical distribution. For example, the best estimate for total mercury emissions from coal-fired power plants in China in 2003 is 90.5 Mg, with the uncertainty range from 57.1 Mg (P10) to 154.6 Mg (P90); and the best estimate for elemental mercury emissions is 43.0 Mg, with the uncertainty range from 25.6 Mg (P10) to 75.7 Mg (P90). The results further indicate that the majority of the uncertainty in mercury emission estimation comes from two factors: mercury content of coal and mercury removal efficiency.

Number Size Distribution of Particles Emitted from Two Kinds of Typical Boilers in a Coal-Fired Power Plant in China

Ultrafine particles (Dp < 100 nm) are suspected to have considerably stronger impacts on human health in recent studies, and the coal-fired power plants are one of the major anthropogenic sources of the ultrafine particles. In order to characterize the ultrafine particles emitted from power plants, comprehensive field research on the number size distribution for boilers with and without low NOx burners (LNBs) was conducted online in a pulverized coal-fired power plant in China. With the use of an engine exhaust particle sizer (EEPS) and an aerodynamic particle sizer (APS), the lower limit of particles measured is extended to 5.6 nm. The particle number concentrations decrease with increasing size, and the nucleation mode particles are dominant in the number concentration. Additionally, the size distributions for boilers with or without LNBs are compared. Results show that the concentrations of ultrafine particles are notably higher for the boiler with LNBs than those for the boiler without LNBs. In additi...

Mercury emission and speciation of coal-fired power plants in China

Abstract. Comprehensive field measurements are needed to understand the mercury emissions from Chinese power plants and to improve the accuracy of emission inventories. Characterization of mercury emissions and their behavior were measured in six typical coal-fired power plants in China. During the tests, the flue gas was sampled simultaneously at inlet and outlet of Selective Catalytic Reduction (SCR), electrostatic precipitators (ESP), and flue gas desulfurization (FGD) using the Ontario Hydro Method (OHM). The pulverized coal, bottom ash, fly ash and gypsum were also sampled in the field. Mercury concentrations in coal burned in the measured power plants ranged from 17 to 385 μg/kg. The mercury mass balances for the six power plants varied from 87 to 116% of the input coal mercury for the whole system. The total mercury concentrations in the flue gas from boilers were at the range of 1.92–27.15 μg/m3, which were significantly related to the mercury contents in burned coal. The mercury speciation in flue gas right after the boiler is influenced by the contents of halogen, mercury, and ash in the burned coal. The average mercury removal efficiencies of ESP, ESP plus wet FGD, and ESP plus dry FGD-FF systems were 24%, 73% and 66%, respectively, which were similar to the average removal efficiencies of pollution control device systems in other countries such as US, Japan and South Korea. The SCR system oxidized 16% elemental mercury and reduced about 32% of total mercury. Elemental mercury, accounting for 66–94% of total mercury, was the dominant species emitted to the atmosphere. The mercury emission factor was also calculated for each power plant.

Mineralogy and Chemical Composition of High-Calcium Fly Ashes and Density Fractions from a Coal-Fired Power Plant in China

To understand the formation mechanism of high-calcium fly ashes, the mineralogical, physical, and chemical properties of several high calcium fly ashes and their different density fractions (<1.0, 1.0−2.5, 2.5−2.89, and >2.89 g/cm3) from a coal-fired power plant were characterized by X-ray diffractometry (XRD), field scanning electron microscopy equipped with energy dispersive X-ray analysis (FSEM-EDX), and X-ray fluorescence spectroscopy (XRF). The occurrence of calcium in coal was determined using sequential extraction tests. The results show that the carbonate-bonded calcium is the dominant species in Xiaolongtan coal, and the ion-exchangeable calcium only occupies 19.2% of total calcium. The major calcium-bearing minerals in low temperature ash (LTA) of the feed coal, lignite from the Yunnan province, include calcite, bassanite, and dolomite. The fly ashes examined contained aluminosilicates with a high concentration of calcium oxide. The major minerals include mullite, quartz, lime, anhydrite, and gehlenite, and the minor minerals are comprised of hematite, magnetite, akermanite, portlandite, and larnite. Minerals in the density faction less than 1.0 g/cm3 consist of lime, calcite, anhydrite, and clay; between 1.0−2.5 g/cm3, quartz, mullite, anhydrite, and gehlenite; between 2.5−2.89 g/cm3, anhydrite, lime, gehlenite, hematite, and quartz; and greater than 2.89 g/cm3, larnite, gehlenite, anhydrite, brownmillerite, and some heavy minerals. In accordance with the microstructural characteristics of the fly ash particles, high-calcium fly ash can be classified into several groups, namely hollowed smooth particles, dense particles, agglomerate particles, porous particles, plerosphere, and other particles with complex surface characteristics. On the basis of chemical composition, high-calcium fly ashes can be classified into four groups namely: calcium oxide, calcium sulfates, Ca−Al−Si compounds, and Ca−S−X (X: Fe, Al, Si, Mg, etc.) compounds. Calcium oxide and calcium sulfates are mainly derived from the original calcium-bearing minerals in coal, whereas Ca−Al−Si and Ca−S−X compounds are formed by the secondary reaction of CaO and CaSO4.

Mineralogy and microstructure of ash deposits from the Zhuzhou coal-fired power plant in China

Ash deposition is one of the major problems encountered in coal-fired power plants. To understand its formation mechanism, six samples of the deposit were collected from different positions of boiler in the Zhuzhou coal-fired power plant in Hunan of China. The mineralogical, chemical compositions, and microstructure of ash samples were analyzed by X-ray diffraction spectrometry (XRD), X-ray fluorescence spectrometry (XRF), optical microscopy, and field scanning electron microscopy equipped with energy dispersive X-ray spectrometry (FSEM-EDX). The results show that the deposits were mainly composed of silica amorphous phases and their chemical compositions of different layers significantly varied. The identified minerals include mullite, cristobalite, hematite, quartz, hercynite, and anorthite. The silica-rich glass phases are derived from volatilization–recondensation of SiO and the interaction between aluminosilicates and other minerals. Several types of crystals were identified in the deposits, including iron-oxide crystals, Fe–Ca-bearing phase, Si-rich phase, and aluminosilicate phase. The deposition of crystals as well as the following melting is the main reason for the porosity structure of deposit. The interaction and eutectic of minerals in coal led to the serious deposition in the coal-fired power plant.

Assessing the value of CO 2 capture ready in new-build pulverised coal-fired power plants in China

Making new plants CO 2 capture ready (CCR) would enable them to retrofit to capture CO 2 at a later date at lower cost when the appropriate policy and/or economic drivers are in place. In order to understand the economic value and investment characteristics of making new plants CCR in China, a typical 600 MW pulverised coal-fired ultra-supercritical power plant, locating in Guangdong province, was examined. Combined with an engineering assessment, costs were estimated for different CCR scenarios. To analyze CCR investment opportunities, the paper applies a cash flow model for valuing capture options and CCR investment. Results were obtained by Monte-Carlo simulation, based on engineering surveys and an IEA GHG CCR study, as well as plant performance information and expert projections on carbon prices, coal prices and electricity prices. CCR investments are justified by factors such as higher retrofitting probabilities, lower early closure probabilities and fair economic return. However, the economic case for CCR largely depends on two factors: (a) whether the original plant is retrofittable without CCR; and (b) the type of investments made, for example, investments essential to CCR tend to be more economic than additional non-essential CCR features such as clutched low pressure turbines. The carbon price and discount rate were found to have significant impacts on the economics of CCR. Overall, it appears that the value of the ‘capture options’ that CCR generates for retrofitting CCS is significant, and so could justify a modest CCR investment, even assuming the original plant is retrofittable without CCR. It was also found the value of CCR might be significantly understated if the range of potential retrofitting dates is artificially constrained.

Assessing the value of CO2 capture ready in new-build coal-fired power plants in China

Abstract China has built at least 70 GW of new coal- fired power installed capacity annually since 2005 and the growth is expected to continue (CEC, 2008). Chinese government, industry and academic stakeholders perceive that China will not mandate new plants to be built with carbon dioxide capture and storage systems in the short term and there is little incentive even to contemplate the first steps needed to fit plants with capture equipment [Reiner, D., Liang, X., Sun, X., Zhu, Y., Li, D., 2007. Stakeholder attitudes towards carbon dioxide capture and storage technologies in China, International Climate Change Conference, Hong Kong, May 29–31 2007]. We investigate the value of making new plants CO 2 Capture Ready (CCR), which would enable them to retrofit to capture CO 2 without unnecessary additional costs when the appropriate policy and /or economic drivers are in place (IEA, 2007). In order to understand the value and investment characteristics of CCR in China, a typical 600 MW pulverized-coal -fired ultra-supercritical power plant, locating at Guangdong province, was examined. Combined with a detailed engineering assessment, we obtained the costs for different CCR scenarios. To analyze CCR investment opportunities, we apply a cash flow model for valuing Capture Options, as developed in [Liang, X., Reiner, D., Gibbins J., Li J., 2007. Fianncing CCR coal-fired power plants in China by issuing capture options, EPRG Working Paper Series, EPRG0728, Cambridge, December. Available at: www.electricitypolicy.org.uk/pubs/wp/eprg0728.pdf ]. Results are obtained by Monte-Carlo simulation, based on engineering surveys and the IEA (2007) CCR study, as well as plant performance information and expert projections on carbon prices, coal prices and electricity prices. CCR investments are justified by factors such as higher retrofitting probabilities, lower early-closure probabilities and fair economic return. However, the economic case for CCR largely depends on the type of investments made, for example, CCR-essential investments tend to be more economic than additional non-essential CCR features such as CCR Essential with clutched low-pressure turbines. Carbon price, coal price and discount rate also were found to have significant impacts on the economics of CCR. Overall, it appears that the value of capture options are significant, and therefore clear retrofitting strategies would be valuable for any CCR investment.

An economic feasibility study of O 2/CO 2 recycle combustion technology based on existing coal-fired power plants in China

In order to reduce the CO 2 emission from the coal-fired power plants, O 2/CO 2 recycle combustion (Oxy-combustion) technique has been proposed through combining a conventional combustion process with a cryogenic air separation process. The technique is capable of enriching CO 2 concentration and then allowing CO 2 sequestration in an efficient and energy-saving way. Taking into account the CO 2 taxation and CO 2 sale, the paper evaluates the economic feasibility of Oxy-combustion plants retrofitted from two typical existing conventional coal-fired power plants (with capacities of 2 × 300 MW and 2 × 600 MW, respectively) with Chinese data. The cost of electricity (COE) and the CO 2 avoidance cost (CAC) are also considered in the evaluation. The COE of the retrofitted Oxy-combustion plant is nearly the same as that of the corresponding conventional plant if the unit price of CO 2 sale reaches 17–22 $/t (different cases). The CAC of the retrofitted 2 × 300 MW Oxy-combustion plant is 1–3 $/t bigger than that of the retrofitted 2 × 600 MW Oxy-combustion plant. Supercritical plants are more economical and appropriate for Oxy-combustion retrofit. The result indicates that Oxy-combustion technique is not only feasible for CO 2 emission control based on existing power plants but is also cost-effective.

Primary air pollutant emissions of coal-fired power plants in China: Current status and future prediction

To explore the atmospheric emissions of coal-fired power sector in China, a unit-based method was developed based on detailed information of unit type, fuel quality, emission control technology, and geographical location. During 2000–2005, the period when power sector developed fastest in the past 20 years, SO 2, NO x and PM emissions of coal-fired power plants increased by 1.5, 1.7 and 1.2 times, respectively. The SO 2, emission of coal-fired power sector was estimated to be 16 097 kt in 2005, and would decrease to 11 801 kt in 2010, attributed mainly to the wide application of the flue gas desulfurization (FGD) technology. The NO x emission, however, would increase from 6965 kt in 2005 to 9680 kt in 2010, since few NO x control measures would be taken during the five years. The TSP, PM 10, and PM 2.5 emissions in 2005 were estimated to be 2774, 1842 and 994 kt, and the values would be 2540, 1824 and 1090 kt in 2010 respectively. The wet FGD would play an important role on dust emission removal. Through faithful implementation of closing small units and emission control policies in the acid rain and sulfur dioxide control zones, approximately 33%, 6% and 25% of SO 2, NO x , and TSP emissions respectively could be further reduced in 2010. Emissions in 2015 and 2020 of coal-fired power plants were predicted applying scenario analysis. For SO 2 and TSP, optimistic situation can be achieved through reasonable control policies; in contrast, NO x would probably be a more serious issue in future.

Mercury emissions from six coal-fired power plants in China

Mercury emission field measurements based on the Ontario Hydro Method (OHM) were conducted for six coal-fired power plants in China. The mercury mass balances for the six power plants varied from 100.3% to 139.5% of the input coal mercury for the whole system. About 0.02%–1.2% of the mercury remained in the bottom ash. In the first five power plants equipped with pulverized coal boiler, most of the mercury was emitted from the stack to the atmosphere. The plants with Electrostatic Precipitator (ESP) system emitted more Hg 0 than Hg 2+, while the plants with the Fabric Filter (FF) emitted less Hg 0 than Hg 2+. Virtually all of the Hg P enter the ESP or the FF was removed. The FF systems had better Hg 0 and Hg 2+ removal efficiencies than the ESP systems. The flue gas desulfurization (FGD) system removed up to 78.0% of Hg 2+ and only 3.14% of Hg 0 in the flue gas, while 8.94% of the original mercury in the coal was removed by the FGD system. The average mercury removal efficiencies of the ESP systems was 11.5%, that of the FF systems was 52.3% and that of the combined ESP + FGD system was 13.7%, much lower than the average removal efficiencies of pollution control device systems in US plants which have been used in previous studies of Chinese mercury emission inventory. Hg 0, rather than Hg 2+ as assumed in previous estimates, has been found to be the dominant species emitted in the atmosphere. The average emission factor was found to be 4.70 g/TJ (10.92 bl/Tbtu), which is much higher than for US plants burning bituminous coals due to the high mercury content in the Chinese coal and the low mercury removal efficiency of air pollution control devices of power plants.

Utilization of fly ash from coal-fired power plants in China

The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disposal of solid residues from combustion and off gas cleaning. This investigation describes chances for the utilization of fly ash from coal-fired power plants in China. After briefly comparing the situation in China and Germany, the status of aluminum recycling from fly ash and the advantages for using fly ash in concrete products are introduced. Chemical and physical analyses of Chinese fly ash samples, e.g., X-ray diffraction (XRD), ICP (Inductive Coupled Plasma) and particle size analysis, water requirement, etc. are presented. Reasonable amounts of aluminum were detected in the samples under investigation, but for recovery only sophisticated procedures are available up to now. Therefore, simpler techniques are suggested for the first steps in the utilization of Chinese fly ash.

Characteristics of particulate matter from emissions of four typical coal-fired power plants in China

The size distribution, microstructure, and chemical composition of particulate matter samples from coal-fired power plants in China were measured using a laser particle analyzer, a scanning electron microscope (SEM), and an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The size distribution showed differences between the electrostatic precipitator capture efficiencies for coarse and fine particles. The microstructure measurements showed three typical particulate microstructures, spherical particles, plerospheres, and irregular particles. The surfaces of most spherical particles had microspheres that were often agglomerated together. The chemical composition of the particulate matter changed as the size decreased, while had differences from different feed coal.

96/00946 Estimation of collective effective dose equivalent for the population due to airborne effluent from coal-fired power plants in China

96/00946 Estimation of collective effective dose equivalent for the population due to airborne effluent from coal-fired power plants in China