Clean Coal Technology Research Articles

Clean Coal Technologies in every stage of coal production in Polish industry

Clean Coal Technologies in every stage of coal production in Polish industry

Oxy-fuel combustionとクリーンコールテクノロジー～CO2回収型新燃焼技術の展開～

Oxy-fuel combustionとクリーンコールテクノロジー～CO2回収型新燃焼技術の展開～

Science Mining and Clean Coal Technology in China

Science Mining and Clean Coal Technology in China

Managing Innovation: Accelerating the Development of Clean Coal Technology

Coal gasification technology concerns the clean, efficient utilization of coal, providing a core solution to address its negative environmental image and impact. Presently, China is pursuing the development of coal gasification technology despite industry setbacks, limited progress and elusive solutions due to limited specialty materials, technological shortfalls and intellectual expertise. The most prominent challenges to overcome include unbalanced research and project scale development issues followed by an excessive emphasis on equipment manufacturing rather than responsible management practices. The ENN Group explored these industry shortcomings to develop a comprehensive management philosophy that is specifically tailored to overcome these fundamental hurdles. Such innovative solutions include the Centralized Innovation Camp, TRIZ (Theory of Inventive Problem Solving) training, Extensive Alliance Network and enhanced process management, focusing upon engineering, quality assurance and process efficiency with the overall objective of industrial scale application. As a result, ENN’s Clean Coal Technologies include: Coal Hydrogasification, Supercritical Coal Gasification, Catalytic Coal Gasification and Underground Coal Gasification, having successfully completed all pilot plant testing requirements and the construction of demonstration commercial units.

Using Mathematica software for coal gasification simulations – Selected kinetic model application

Abstract Coal gasification is recognized as a one of promising Clean Coal Technologies. As the process itself is complicated and technologically demanding, it is subject of many research. In the paper a problem of using volumetric, non-reactive core and Johnson model for coal gasification and underground coal gasification is considered. The usage of Mathematica software for models' equations solving and analysis is presented. Coal parameters were estimated for five Polish mines: Piast, Ziemowit, Janina, Szczyglowice and Bobrek. For each coal the models' parameters were determined. The determination of parameters was based on reactivity assessment for 50% char conversion. The calculations show relatively small differences between conversion predicted by volumetric and non reactive core model. More significant differences were observed for Johnson model, but they do not exceeded 10% for final char conversion. The conceptual model for underground coal gasification was presented.

Power generation from chemically cleaned coals: do environmental benefits of firing cleaner coal outweigh environmental burden of cleaning?

Chemical beneficiation of coals using acid and alkali–acid leaching procedures is assessed as a potential coal cleaning technology employing life cycle assessment.

TRIG™: An advanced gasification technology to utilize low rank coals for power

This paper presents the results of a recent low rank coal 850MW class IGCC (“Integrated Gasification Combined Cycle”) feasibility study for the 50Hz market. The study aimed to position the Transport Integrated Gasification (“TRIG™”) technology for power generation in the China market where coal gasification has been widely practiced. It assumed a mine mouth project in eastern Inner Mongolia, China and used a low rank coal from the area. Results from the study indicate that the low rank coal TRIG™ IGCC is more efficient and with a superior environmental performance and less water usage than the best available conventional ultra-supercritical (“USC”) technology in the China market. With environmental regulation compliance costs increasing in China, the low rank coal TRIG™ IGCC will become competitive as one of the viable clean coal technologies for power generation. Converting the large reserve of low cost and low heating value coals located in remote areas to electricity for the coastal areas will certainly help these areas manage the increasing pressure for further reductions in emissions from coal firing power plants. The paper also provides an update on Southern Company’s Kemper IGCC project in the USA that includes CO2 capture and is currently in its final stage of construction.

Penetration of clean coal technology and its impact on China's power industry

This paper discusses the penetration of clean coal technology and its impact on China's power sector. To better understand the development of China's clean coal technology in the power sector, first, the development of clean coal technology and the status of coal consumption in the past 20 years are briefly analyzed. Second, it is vital to present the future trend of clean coal power. Based on several uncertainty analyses, two scenarios for the penetration of clean coal technology are constructed to probe the role of clean coal technology in China's sustainable development. Finally policy implications are proposed to fully develop and deploy feasible technologies for China's coal power sector.

Low-calorific gasification of underground coal with a higher humidity

The technology of underground coal gasification (UCG) belongs to the group of so called clean coal technologies. It can form a product called syngas, which can serve as a fuel for energy production or can be further processed in the chemical industry. This technology can gasify coal underground which cannot be mined by current methods from economic and technological reasons. Like any technology, UCG also has its limitations. One of them is the high humidity of coal (40%). Article, based on long lasting experimental research, analyzes the possibilities of increasing the UCG efficiency. Especially for lignite with a higher humidity content using only air as an oxidiser. It analyzes the creation of syngas components (CO, H2, CH4), its calorific value during the process in a special laboratory equipment for UCG research. It was demonstrated that the calorific value and syngas quality also depends on the location of sampling point. Based on this knowledge, the principle of a new method, that for the above mentioned conditions (low-calorific coal with a higher humidity), improves the UCG technology from the point of syngas quality and is mentioned in the conclusion.

Integration of in-situ CO2-oxy coal gasification with advanced power generating systems performing in a chemical looping approach of clean combustion

Underground coal gasification (UCG) is a clean coal technology to utilize deep coal resources effectively. In-situ CO2-oxy coal gasification may eliminate the operational difficulty of the steam gasification process and utilize CO2 (greenhouse gas) effectively. Furthermore, it is necessary to convert the clean gasified energy from the UCG into clean combustion energy for an end-use. In order to achieve efficient clean power production, the present work investigates the thermodynamic feasibility of integration of CO2 based UCG with power generating systems operating in a chemical looping combustion (CLC) of product gas. The use of CO enriched syngas from O2/CO2 based UCG reduces the difficulty of the heat balance between a fuel reactor and an air reactor in a nickel oxygen-carrier based CLC system. Thermodynamic analyses have been made for various routes of power generation systems such as subcritical, supercritical and ultra-supercritical boiler based steam turbines and gas turbines for the UCG integrated system. It is shown, based on mass and energy balance analysis, that the integration of CO2 based UCG with the CLC system reduces the energy penalty of carbon capture and storage (CCS) significantly. A net thermal efficiency of 29.42% is estimated for the CCS incorporated system, which operates in a subcritical condition based steam turbine power plant. Furthermore, it is found that the efficiency of the proposed steam turbine system increases to 35.40% for an ultra-supercritical operating condition. The effect of operating temperature of the air reactor and the fuel reactor of the CLC system on the net thermal efficiency of combined cycle power plant is investigated. It is found that a net thermal efficiency of 42.53% can be obtained for the CCS incorporated combined cycle power system operating at an air reactor temperature of 1200°C.

Waiting for Godot? China's Search for Shale Gas and Clean Coal Technologies

China’s 12th Five-Year Plan (2011-2015) envisages that shale gas and coal will be central to its energy future. However, for China to meet the energy security and climate change objectives set out in its 12th Five-Year Plan it will be reliant on the widespread commercial deployment of two key technologies; hydraulic fracturing combined with horizontal drilling for shale gas and carbon capture and storage (CCS) for coal. China is moving to acquire these technologies through technology transfer and diffusion from the US, but progress has been slow and neither is currently available in China at a commercial scale. Drawing on interviews in the US and China, we argue that China’s expectation of technology from the US may well be disappointed because of factors unique to the US institutional environment that have made the development of fracking technology possible and hinder the development of CCS technology at a commercial scale. As a result, Chinese policymakers would be well-advised not to count on these technologies to meet their energy and climate goals.

Environmental and Operational Performance Evaluation of Taiwan Thermal Power Plants

An integrated environmental and operational efficiency model for evaluation of seven thermal power plants in Taiwan was constructed by data envelopment analysis (DEA). Inputs and desirable outputs along with 3 undesirable outputs, including CO2, SOx, and NOx emissions were simulated. From results we found that the integrated efficiency and the production scale of most plants were inefficient during 2001- 2008. Reductions in fuel consumption and CO2 emission are the major solutions for efficiency improvement. Other improvements include enhancing pollution control measures and optimizing power plant scales. Also, clean-coal technology and lower-carbon fuels should be enhanced to reduce CO2 emissions from thermal power plants in Taiwan. In addition, flue gas desulfurization (FGD) and high efficient selective catalytic reduction (SCR) and advanced low-NOx burners can be installed to remove extra SOx and NOx emissions. Findings of this study can be of value for improving environmental and operational performance of thermal power plants in Taiwan as well as countries with similar concerns.

A Polygeneration System Based on Multi-Input Chemical Looping Combustion

This paper proposes a polygeneration system based on a multi-input chemical looping combustion system, which generates methanol and electricity, through the use of natural gas and coal. In this system, the chemical looping hydrogen (CLH) production system and the coal-based methanol production system are integrated. A high quality fuel, natural gas, is used to improve the conversion ratio of coal. The Gibbs energy of the two kinds of fuels is fully used. Benefitting from the chemical looping process, 27% CO2 can be captured without energy penalty. With the same outputs of methanol and electricity, the energy savings ratio of the new system is about 12%. Based on the exergy analyses, it is disclosed that the integration of synthetic utilization of natural gas and coal plays a significant role in reducing the exergy destruction of the new system. The promising results obtained in this paper may lead to a clean coal technology that will utilize natural gas and coal more efficiently and economically.

Greenhouse gas emissions reduction in China by cleaner coal technology towards 2020

The Chinese energy system, a major CO2 emitter, relies heavily on fossil fuels, especially coal. Coal will continue to play a major role in the new installed power generation capacity in the future, which will cause unavoidable environmental problems. Clean coal technologies (CCTs) are essential for emissions reduction in the power sector. In general, CCTs cover coal upgrading, efficiency improvements, advanced technologies and zero emissions technologies. Besides these, CCTs also include other emissions reduction technologies and comprehensive utilization technologies in China.This paper review the complete life cycle modeling of CCTs. The advanced technologies include super-critical (super-C), ultra super-critical (USC) and integrated gasification combined cycle (IGCC). The results show that the higher efficiency technologies have lower potential impacts. Compared with the average level of power generation technology, CO2 emissions reduction is 6.4% for super-C, 37.4% for USC and 61.5% for IGCC. Four coal power scenarios are developed based on the assumption of potential investment power for CCTs in 2020, which are super-C, USC, USC and old low efficiency generation substitution by USC, IGCC and carbon capture and storage (CCS). The CO2 emissions intensity is 1.93 kg/kWh for super-C, 1.69 kg/kWh for USC, 1.59 kg/kWh for USC + replacement and 1.29 kg/kWh for IGCC + CCS. The CO2 emissions intensity was 1.95 kg/kWh in 2010, which had decreased 5.5% compared with the level in 2005. The energy structure is continuously being improved and optimized. The potential carbon reduction will be limited in the power system in 2020 by current commercial CCTs with the generation efficiency increase. The most impressive technology is IGCC with CCS which enables greenhouse gas reduction of 37.6% compared with the level in 2005.

Coal’s Last Chance

This article presents an overview of clean coal technologies that promise to produce electricity with fewer emissions. The 600 MW John W. Turk Jr. power plant built by American Electric Power near Fulton is the first “ultra-supercritical” electric-generating clean coal unit in the U.S. Turk’s efficiency is 39 percent to 40 percent, versus about 35 percent for conventional plants. Turk burns roughly 11 percent less coal than a subcritical plant would need to produce the same amount of power. Less coal means fewer emissions, and what’s left – aside from carbon dioxide – is further reduced by the state-of-the-art emission control technologies. Another clean coal technology that has seen wider adoption is the circulating fluidized bed combustion (CFBC) technology. One of CFBS’ greatest advantages is that since the furnaces burn at low temperatures, it can use very low-quality fuel, such as waste piles left over from mining and even chicken litter.

부분 용융 운전 조건에서 석탄슬러리 가스화 운전 특성

Coal gasification technology is considered as next generation clean coal technology even though it uses coal as fuel which releases huge amount of greenhouse gas because it has many advantages for carbon capture. Coal or pet-coke slurry gasification is very attractive technology at present and in the future because of its low construction cost and flexibility of slurry feeding system in spite of lower efficiency compared to dry feeding technology. In this study, we carried out gasification experiment using bituminous coal slurry sample by integrating coal slurry feeding facility and slurry burner into existing dry feeding compact gasifier. Especially, our experiment was conducted under fairly lower operation temperature than that of existing entrained-bed gasifier, resulting in partial slagging operation mode in which only part of ash was converted to slag and the rest of ash was released as fly ash. Carbon conversion rate was calculated from data analysis of collected slag and ash, and then cold gas efficiency, which is the most important indicator of gasifier performance, was estimated by carbon mass balance method. Fairly high performance considering pilot-scale experiment, 98.5% of carbon conversion and 60.4% of cold gas efficiency, was achieved. In addition, soundness of experimental result was verified from the comparison with chemical equilibrium composition and energy balance calculations.

Coal to SNG: Technical progress, modeling and system optimization through exergy analysis

For both energy security and CO2 emission reduction, synthetic natural gas (SNG) production from coal is an important path to implement clean coal technologies in China. In this paper, an overview of the progress of coal to SNG technologies, including the development of catalysts, reactor designs, synthesis processes, and systems integration, is provided. The coal to SNG system is modeled, the coupling between SNG production and power generation is investigated, the breakthrough points for further energy savings are determined, and the system performance is optimized based on the first and the second laws of thermodynamics. From the viewpoint of the first law of thermodynamics, the energy conversion efficiency of coal to SNG system can reach 59.8%. To reduce the plant auxiliary power, the breakthrough points are the development of low-energy-consumption oxygen production technology and gas purification technology or seeking new oxidants for coal gasification instead of oxygen. From the viewpoint of the second law of thermodynamics, the major exergy destruction in a coal to SNG system occurs in the coal gasification unit, SNG synthesis unit and the raw syngas cooling process. How to reduce the exergy destruction in these units is the key to energy savings and system performance enhancement. The conversion ratio of the first SNG synthesis reactor and the split ratio of the recycle gas are key factors that determine the performance of both the SNG synthesis process and the whole plant. A “turning point” phenomenon is observed: when the split ratio is higher than 0.90, the exergy destruction of the SNG synthesis process will increase sharply, which causes a decrease in overall system efficiency. Keeping the conversion ratio of the first synthesis reaction between 0.78 and 0.90 not only avoids the rapid increase of exergy destruction in the SNG synthesis process but also produces the SNG product with a high CH4 purity (>94.0%), and the catalyst can be maintained with a high activity. When the split ratio of the recycle gas is approximately 0.85, the best coupling/balance between SNG production and power generation can be attained and thus the highest overall system efficiency of approximately 62% is achieved, much higher than approximately 55% efficiency in a traditional coal to SNG plant. The findings presented in this paper are important steps for future improvements of coal to SNG systems, especially the SNG and power cogeneration systems, integration in the future.

The New IPPC Directive: A Threat to the Polish Power Sector

Implementation of the directive on industrial emissions will radically change the status quo in the national power sector, especially the heating sector. The amendment of the integrated pollution prevention and control directive introduces significant changes to the legal conditions in the scope of permissible standards of sulphur dioxide, nitrogen oxides, and dust emissions. As coal is the basic fuel applied in the electricity and heat generation technologies of the national power industry, the change of the directive provisions will be particularly sensible in Poland. The Directive clearly points to the use of clean coal technology—efficient desulphurisation, denitrogenation, and particulate removal from exhaust gases—if not a wholesale rejection of coal in favor of other sources such as gas, biomass, and municipal waste. The implementation of the proposed provisions of the industrial emission directive in Poland in 2016 will significantly reduce the production capabilities of the heat and power generators. In result, the national energy security will probably be endangered.

System approach to the analysis of an integrated oxy-fuel combustion power plant

Abstract Oxy-fuel combustion (OFC) belongs to one of the three commonly known clean coal technologies for power generation sector and other industry sectors responsible for CO2 emissions (e.g., steel or cement production). The OFC capture technology is based on using high-purity oxygen in the combustion process instead of atmospheric air. Therefore flue gases have a high concentration of CO2. Due to the limited adiabatic temperature of combustion some part of CO2 must be recycled to the boiler in order to maintain a proper flame temperature. An integrated oxy-fuel combustion power plant constitutes a system consisting of the following technological modules: boiler, steam cycle, air separation unit, cooling water and water treatment system, flue gas quality control system and CO2 processing unit. Due to the interconnections between technological modules, energy, exergy and ecological analyses require a system approach. The paper present the system approach based on the ‘input-output’ method to the analysis of the: direct energy and material consumption, cumulative energy and exergy consumption, system (local and cumulative) exergy losses, and thermoecological cost. Other measures like cumulative degree of perfection or index of sustainable development are also proposed. The paper presents a complex example of the system analysis (from direct energy consumption to thermoecological cost) of an advanced integrated OFC power plant.

Exploring the impacts of a carbon tax on the Chinese economy using a CGE model with a detailed disaggregation of energy sectors

This paper applies a computable general equilibrium model to investigate the impacts of a carbon tax on China's economy and carbon emissions based on China's 2010 Input–Output Table. To obtain robust simulation results, we further disaggregate the energy sectors into eight departments according to energy use characteristics. The empirical results indicate that a moderate carbon tax would significantly reduce carbon emissions and fossil fuel energy consumption and slightly reduce the pace of economic growth. However, a large carbon tax has a significantly negative impact on China's economy and social welfare. Moreover, a large carbon tax would entail marked price changes in China. Of the fossil fuels in use, reducing coal consumption would have the greatest impact on reducing carbon emissions, and the ad valorem duty rate for coal would be the highest after levying a carbon tax because it has the highest carbon emission coefficient. Therefore, China should strive to promote clean coal technology, which may be crucial to reducing carbon emissions. Moreover, levying a carbon tax would improve the use of clean energy, which would be an effective means of reducing carbon emissions. Therefore, the Chinese government should formulate the regulations for and pass a carbon tax as early as possible to achieve its carbon emission abatement target and further contribute to mitigating climate change.