Performance improvement of integrated coal gasification combined cycle by a new approach in exergy analysis

A new approach to exergy analysis is proposed for examing the consumption of energy as the minimum driving force and of exergy consumption that is avoidable, and for the development of a method to predict the alternatives in system improvement by exploring possible reduction in the avoidable exergy consumption. Also suggested in this study is a dimensionless parameter γ_AVO, which is the ratio of avoidable exergy consumption over total fuel energy input to the system. Detailed analyses, including the calculation of exergy consumption, exergy loss and avoidable exergy consumption, were conducted for each component in the syngas cooling system in the Integrated coal Gasification Combined Cycle (IGCC) plant, to prove the effective application of the proposed method. The analysis showed that the rank of avoidable exergy consumption was different from that of total energy consumption, and hence it confirmed that an energy analysis by conventional methods misled the focus of improvement in system design. The methodology developed in this study offers a new approach for system designers to analyze and to improve the performance of a complex energy system such as an IGCC plant.     

A new approach to catalytic coal gasification: The recovery and reuse of calcium using biomass derived crude vinegars

A new concept in catalytic coal gasification has been developed. The use of crude vinegars (CVs) derived from different lignocellulosic biomass resources is described for the recovery and reuse of calcium in coal gasification. Calcium introduced by impregnation with a CV solution produced a higher catalytic activity than calcium loaded by impregnation with an aqueous acetic acid solution. Furthermore, CVs were found to be capable of reclaiming calcium from gasification residue and of improving the catalytic activity of the indigenous crystalline calcite in bituminous coal as in situ catalyst.     

New approach for gasification of coal char

To reduce the cost of catalyst in catalytic gasification and to eliminate the need for catalyst recovery, the effect of potassium carbonate and magnesium nitrate catalyst in the gasification of Shen Bei brown coal with steam was studied. Potassium carbonate, magnesium oxide and coal ash are recovered as a potassium silicate complex fertilizer of economic significance.     

A new mix design concept for earth-moist concrete: A theoretical and experimental study

This paper addresses experiments on earth-moist concrete (EMC) based on the ideas of a new mix design concept. First, a brief introduction into particle packing and relevant packing theories is given. Based on packing theories for geometric packing, a new concept for the mix design of earth-moist concrete will be introduced and discussed in detail. Within the new mix design concept, the original grading line of Andreasen and Andersen [Andreasen, A.H.M. and Andersen, J., 1930, Ueber die Beziehungen zwischen Kornabstufungen und Zwischenraum in Produkten aus losen Körnern (mit einigen Experimenten). Kolloid-Zeitschrift 50, p. 217-228 (in German).], modified by Funk and Dinger [Funk, J.E. and Dinger, D.R., 1994, Predictive Process Control of Crowded Particulate Suspensions, Applied to Ceramic Manufacturing. Kluwer Academic Press, Boston.], will be used for the mix proportioning of the concrete mixtures.Mixes consisting of a blend of slag cement and Portland cement, gravel (4-16), granite (2-8), three types of sand (0-1, 0-2 and 0-4) and a polycarboxylic ether type superplasticizer are designed using the new mix design concept. The designed concrete mixes are tested in the lab, both in fresh and hardened states, to show the suitability of the ideas of the new mix design concept. The tested concrete mixes meet the requirements on the mechanical and durability properties.Furthermore, the application of fine stone waste materials in the form of premixed sand (Premix 0-4) is presented. By means of an optimized particle packing, stone waste materials can be used to reduce the amount of the most cost intensive materials in earth-moist concrete mixes, viz. binder and filler. The results of tests carried out on mortar samples as well as on paving blocks produced on a laboratory paving stone machine will be discussed. The application of fine stone waste materials in earth-moist concrete mixes does not only meet the current trends in raw materials use, but also fulfill the technical requirements of the concrete in fresh and hardened state.     

绿氢重构的粉煤气化煤制甲醇近零碳排放工艺研究

在“碳达峰、碳中和”的背景下,传统煤制甲醇工艺存在CO₂排放强度大、能耗高等问题成为制约煤制甲醇工艺发展的瓶颈问题。本研究基于外源性的绿氢,重构粉煤气化煤制甲醇工艺,省掉了空分单元、变换单元,开发了短流程低温甲醇洗单元,提出了粉煤气化集成绿氢的近零碳排放煤制甲醇新工艺。从碳元素利用率、CO₂排放、成本分析等角度对新工艺进行了评价。结果表明,与传统煤制甲醇工艺相比,新工艺碳元素利用率从41.50%提高到95.77%,CO₂直接排放量由1.939降低至0.035 t·(t MeOH)^-1,通过分析H₂价格与碳税对产品成本的影响发现,当氢气价格和碳税分别为10.36 CNY·(kg H₂)^-1和223.3 CNY·(t CO₂)^-1时,两种工艺的产品成本相当。新工艺不仅减少了煤制甲醇过程碳排放,而且可以提高可再生能源就地消纳能力,具有良好的应用前景。     

An experimental study on gasification of Colombian coal in fluidised bed

The main results of an experimental work on gasification of Colombian coal in a fluidised bed are reported in this paper. Experiments were carried out at different steam/coal (F_s/F_c) and air/coal (F_a/F_c) ratios and temperatures of gasifying agent. In addition, the influence of bed temperature on coal conversion was analysed. Results show a maximum value in the curve of high heating value versus F_a/F_c. From the environmental standpoint, low concentrations of sulphur compounds were obtained but more work should be done in order to decrease particulate matter.     

典型煤气化技术概述

我国煤炭资源丰富,能源消费以煤炭为主。煤炭气化是煤高效洁净利用的关键技术。分别对固定床、流化床及气流床气化工艺进行了简介,列举了典型的煤气化技术,分析了各自的工艺特点,并对其应用现状进行了综述。     

煤气化制氢新技术的探讨

简单介绍了煤气化制氢的2种方法,详细分析了靠外部提供反应所需热量来实现煤气化制氢的新技术.构造了煤制氢新工艺系统,对新工艺进行了系统模拟和分析,系统中气化炉的气化效率达到96.3%,热效率可达87.4%.煤产氢比现有工艺提高了约25%.     

A new experimental Continuous Fixed Bed Reactor to characterise wood char gasification

Two-stage fixed bed gasification is one of the most promising technologies for low and medium energy production from biomass. In industrial processes, control and optimisation is often based on constructor know-how rather than on an understanding of the mechanisms involved. We present a new original tool, the Continuous Fixed Bed Reactor (CFiBR), which was specifically designed and built to enable a fine understanding of the limiting stage of a gasifier: the char bed gasification zone. The reactor, the instrumentation, the operating procedure and set-up tests are described in detail. The potential of the reactor is demonstrated through the characterisation of the gasification of a continuous wood char bed. Temperature profiles and gas concentrations along the 65 cm bed were established and showed that the most reactive zone was the first 10 cm of the char bed. Accurate energy and mass balances provided relevant information regarding the contributions of the main reactions involved in the fixed char bed gasification process.     

Technology and economics of coal gasification

The best known commercial coal gasification processes which use oxygen (air) and steam as gasifying media are the gas producer process (normal pressure, fixed bed), Lurgi process (high pressure, fixed bed), Winkler process (normal pressure, fluidized bed) and Koppers-Tetzek process (normal pressure, entrained). Fixed bed and fluidized bed processes are suitable for gasification of noncaking and weakly caking coals with high ash fusion temperatures (> 1200°C). The entrained system is suitable for gasification of any coal. Low-caloric gas (～ 150 Btu/scf) can be produced by the gas producer, Lurgi and Kinkier processes; medium- (～ 300 Btu/scf) and high-caloric (～ 950 Btu/scf) gas by any process. Lurgi and Koppers-Totzek processes are preferred processes for production of synthesis gas at the present time. The costs (/Btu) of production of low-caloric gas are the lowest followed by the medium- and high-caloric gas costs (see Figure 6). The costs of gas production from coal are mainly dependent on the efficiency of the gasification process, scale of operation and the cost of fuel.     

Underground gasification of coal and lignite

The underground gasification of coal and lignite is of interest when traditional coal extraction is impossible or unprofitable and also with increasing demand for thermal and/or electric power. In the Soviet Union, at six industrial Podzemgaz stations, beginning in the 1930s, more than 15 million t of coal was processed to obtain more than 50 billion m³ of gas. The South Abinsk station operated from 1955 to 1996, while the Angren station has been operating since 1963. Research on the underground gasification of coal has been largely theoretical, without close connection to industrial practice, and the results are based on mathematical modeling and data from 50–70 years ago. Obviously, Russia’s leading position in the underground gasification of coal has been lost. Russia now lags a number of countries that are making significant investments in the process. Note that, in Russia, despite the obvious benefits of underground gasification of coal, interest in the process has waned, on account of its significant deficiencies: the possibility of gas filtration to the surface; insufficient controllability of coal-bed preparation and thermal processing; the relatively low heat of combustion of the gas produced; and considerable losses of gas and coal underground. Note also the environmental impact of the underground gasification of coal, associated with the deformation of rock, its thermal, chemical, and hydrogeological changes, increase in its temperature, and active chemical pollution of groundwater. An obstacle to the adoption of the underground gasification of coal is the lack of clear ideas regarding the preparation and use of fuel gas. Recommendations for improving the process focus on the design of the underground gas generator and the gasification of the coal bed, without addressing the technology of the underground system, whose cost accounts for ~75% of the total equipment costs. The method proposed in the present work for the preparation of fuel gas from coal challenges the notion that the gas produced in underground gasification of coal should be divided into two products: gas and the tar (hydrocarbons) that forms in the preparation of the gas for combustion. If the specified temperatures are maintained, no condensation of hydrocarbons in the equipment and gas lines is observed, and dry dust removal from the gas may be employed, without complex processing of wastewater and of explosive and toxic materials. That significantly improves the economic and environmental characteristics of the process, Analysis of the results shows that the proposed approach to purifying the fuel gas produced by underground gasification of coal and lignite reduces capital costs in construction of the system by almost half; and the costs of gas production by a factor of 1.7. The time to recoup the initial investment is shortened by 41%; the yield of thermal energy is increased by 10.5%; and annual power output is increased by 151296 MW-h.     

Polygeneration of hydrogen and power based on coal gasification integrated with a dual chemical looping process: Thermodynamic investigation

This paper assesses, from a thermodynamic perspective, the conversion of coal to power and hydrogen through gasification simultaneously with a dual chemical looping processes, namely chemical looping air separation (CLAS) and water–gas shift with calcium looping CO₂ absorption (WGS-CaL). CLAS offers an advantage over other mature technologies in that it can significantly reduce its capital cost. WGS-CaL is an efficient method for hydrogen production and CO₂ capture. The three major factors, oxygen to coal (O/C), steam to coal (S/C) and CaO to coal (Ca/C) were analyzed. Moreover, the comparisons of this suggested process and the traditional processes including integrated gasification combined cycle (IGCC), integrated gasification combined cycle with carbon capture and storage (IGCC-CCS) and integrated gasification combined cycle with calcium-based chemical looping (IGCC-CaL) were discussed. And, the exergy destruction analysis of this suggested process has also been calculated.     

Energetic exploitation of vine shoot by gasification processes: A preliminary study

In this study the energy potential generated by the biomass remnants of vine shoot produced in Extremadura (Spain) by a gasification process is evaluated. The raw material was characterised by elemental and proximate analysis, its Higher Heating Value (HHV) being evaluated as well. In order to determine the optimal gasification temperature for the production of gases, the vine shoots were treated at different temperatures, i.e., 650, 700, 750 and 800 °C in air atmosphere. The optimal temperature (800 °C) was selected and the vine shoot remnants were gasified in air stream (200 mL min^− 1) and for different times (8 and 50 min). The yield of the so-obtained phases was calculated and the study was focused on solid and gaseous phases. The solid phase was characterised by elemental and proximate analysis as well as by HHV. In order to determine their properties as precursors of activated carbons, the adsorption isotherms of N₂ at 77 K were measured. Finally, the electric power that could be obtained by a combustion process in a vapor boiler was calculated.     

一种新形深拉成形模具的设计与试验

在大批量生产金属板料杯形零件时，深拉深成形是一项很重要的成形工艺。在拉深成形过程中，有许多可变化的因素直接影响着拉深的效果和拉深件的质量，如坯料形状、凸模和凹模的圆角半径以及坯料材料的可成形性能等。特别是在深拉成形过程中，为了获得最佳的产品质量，坯料和凹模的形状对拉深成形影响较大。文章对五种类形压料板和凹模型状的影响情况进行了重点试验和分析，并在拉深凸模和凹模的圆角半径保持不变的条件下，依据金属板料的拉深比（即拉深系数d／D的倒数，用β表示），测量压料板压力的分布情况。由试验研究得出，在深拉成形工艺过程中，坯料和凹模问的夹角α直接影响着压料板压力的分布和拉深比。     

整体煤气化燃料电池联合发电(IGFC)技术研究进展

整体煤气化燃料电池联合发电技术(IGFC)是一种新型煤基洁净高效发电技术,不考虑热电联供的情况下,发电效率达60%以上,可有效控制污染物的排放,为CO₂捕集和回收创造了条件,可实现CO₂的近零排放。IGFC系统一般由煤气化净化、燃料电池发电、余热回收及CO₂捕集和封存等子系统构成,其中燃料电池发电技术是制约IGFC发展的关键技术。固体氧化物燃料电池(SOFC)及熔融碳酸盐燃料电池(MCFC)是适配IGFC系统的2种燃料电池技术,其中SOFC在生产成本及发电效率方面更具优越性。2017年国家能源集团牵头,联合中国矿业大学(北京)、北京低碳清洁能源研究院、华能清洁能源技术研究院、清华大学等,在国家重点研发计划项目支持下承担了开发100 kW级SOFC和MCFC发电单元,建成MW_th级CO₂近零排放的IGFC示范工程任务,项目成果推动了我国IGFC系统从基础技术研发向产业化迈进的步伐。     

现代煤气化技术及其煤种的适应性分析

结合国内外煤气化技术发展现状与趋势,讨论了煤质特性对气化过程的影响及其在不同气化炉型中的适应性。分析表明,煤种的多样性及气化工艺的选择促进了煤气化技术的快速发展,气流床和流化床代替固定床是煤气化技术发展的必然所趋。在充分认识各类煤气化技术优缺点的基础上,应发挥优势,针对煤种选用炉型,开发具有单炉生产能力高、煤种适应性强、气体成分可调等优势的加压气化技术以及可有效利用煤气高温显热的两段或多段式气化技术。     

Flash hydrogenation of coal. 1. Experimental methods and preliminary results

A laboratory reactor system has been developed for the determination of products obtainable from the flash heating of raw coal in flowing hydrogen at pressures up to 100 atm. The system provides for control of heating rate, solids-contact time and vapour-product residence time. A comparison of results in which each of these time parameters was varied in turn illustrates their importance in determining the yields of alkanes and single-ring aromatics.     

Pilot-trial and modeling of a new type of pressurized entrained-flow pulverized coal gasification technology

A new type of pressurized entrained-flow pulverized coal gasification technology has been developed by ECUST. It is characterized with four nozzles symmetrically disposed on the upper part of a gasifier. The effects of operation conditions on gasification, N₂ as carrier gas with middle pressure superheated (MP SH) steam, CO₂ as carrier gas with MP SH steam and CO₂ as carrier gas without MP SH steam, respectively, have been tested in the pilot plant. The carbon conversion of all gasification schemes is larger than 99%. For N₂ as carrier gas, the volume fraction (Dry) of CO + H₂ is larger than 90% (v). For CO₂ as carrier gas, the volume fraction (Dry) of CO + H₂ is larger than 92% (v) with MP SH steam and larger than 95% (v) without MP SH steam.At the same time, based on Gibbs energy minimization principle, the pulverized coal gasification system model was built. The simulation results well matched the pilot-trial data under different operation conditions. The model can be used for the design, assessment, and improvement of the entrained-flow coal gasification system.     

煤气化技术的应用与发展

介绍了国内外煤气化技术的发展概况和发展趋势,重点对几种典型煤气化技术的应用与发展进行了研究,并对Lurgi炉、BGL炉、GE气化炉、多喷嘴炉、清华炉、Shell炉、GSP炉、两段炉、航天炉等典型煤气化炉的结构、性能进行了对比分析。从8个方面分析了煤气化技术的选择需要注意的问题。提出了煤气化技术创新建议,指出未来煤炭的清洁高效转化利用将以大型、先进的煤气化技术为核心,以电、化、热等多联产为方向进行技术集成。     

煤气化化学与技术进展

阐述了煤气化化学及气化过程,说明煤气化过程主要包括煤的热裂解、部分氧化燃烧、炭的气化、炉渣的生成和排出4个转化步骤。论述了固定床气化技术、流化床气化技术、气流床气化技术3种煤气化技术的工艺、设备、优缺点和适用范围。从煤灰液渣对耐火衬里的腐蚀机理、煤灰化学组成、灰熔融性和灰熔融温度、液渣黏度四方面分析了气流床灰/渣特性。最后阐述了美国煤气化技术进展及发展方向,提出应重点开展IGCC煤气化、低阶煤(褐煤和次烟煤)气化技术研究,开展以提高气化炉可靠性、气化效率和煤种适应性为目标的气化炉优化研究,控制多种污染物排放至极低水平的合成气净化技术研究,低成本高效率的O2分离技术及H2和CO2的分离技术研究等。