Biomass gasification technology:The state of the art overview

In the last decades the interest in the biomass gasification process has increased due to the growing attention to the use of sustainable energy. Biomass is a renewable energy source and represents a valid alternative to fossil fuels. Gasification is the thermochemical conversion of an organic material into a valuable gaseous product, called syngas, and a solid product, called char. The biomass gasification represents an efficient process for the production of power and heat and the production of hydrogen and second-generation biofuels.This paper deals with the state of the art biomass gasification technologies, evaluating advantages and disadvantages, the potential use of the syngas and the application of the biomass gasification. Syngas cleaning though fundamental to evaluate any gasification technology is not included in this paper since; in the authors＇ opinion, a dedicated review is necessary.

A remining technology of underground coal gasification at Zhongliangshan Coal Mine

The field trail used a mixture of steam and air with various levels of oxygen en- richment.Steady conditions were achieved in the field trail which produced high quality hydrogen-enriched syngas.To understand and optimize the UCG process,a simplified heat and mass transfer model was presented,providing a predictive tool for temperature and the major constituents of the syngas production.The model is compared with the field trail measurements for air and two levels of oxygen enrichment,showing reasonable agreement for the channel temperature and product syngas concentration profile.

Off-design Characteristics of IGCC System Based on Two-stage Coal-slurry Gasification Technology

整体煤气化联合循环（integrated gasification combinedcycle,IGCC）机组在一定情况下处于非设计工况运行。为了研究IGCC系统变工况特性,采用ThermoFlex软件建立基于两段式水煤浆气化技术的200 MW级整体煤气化联合循环系统模型,主要考查燃气轮机负荷、整体空分系数Xas、大气温度、大气压力对系统性能的影响。研究结果表明,降低燃气轮机负荷或者提高大气温度系统效率均呈先升高而后降低的趋势。整体空分系数Xas增加,机组发电效率降低。大气压力对系统效率影响较小。上述条件下采用两段水煤浆气化技术,系统性能可以得到有效改善。研究结果可为采用两段式水煤浆气化技术的IGCC系统的设计、运行提供参考。

Treatment of gasification effluent of fertilizer with biochemical united technology

Introduced the technology and application of treating the gasification effluent offertilizer with the physical-chemistry and biochemistry united technology.The technology issimple and viable, and occupies less land.When the main equipment runs normally, thegasification effluent of fertilizer treated with the united technology reached the requirementby second-degree discharge standard of the'Discharge standard of water pollutants forsynthesize ammonia industry'.

New Breakthroughs in China's Coal Gasification Technology

It is learned from the 2013 Summit Forum on Strategic Development of Coal-to-Natural Gas in China that the China Sedin Engineering Company,Ltd.has developed with independent intellectual property rights two experimental furnaces for pressurized gasification of crushed coal,5 m

Development of catalytic combustion and CO_(2)capture and conversion technology

Changes are needed to improve the efficiency and lower the CO_(2)emissions of traditional coal-fired power generation,which is the main source of global CO_(2)emissions.The integrated gasification fuel cell(IGFC)process,which combines coal gasification and high-temperature fuel cells,was proposed in 2017 to improve the efficiency of coal-based power generation and reduce CO_(2)emissions.Supported by the National Key R&D Program of China,the IGFC for nearzero CO_(2)emissions program was enacted with the goal of achieving near-zero CO_(2)emissions based on(1)catalytic combustion of the flue gas from solid oxide fuel cell(SOFC)stacks and(2)CO_(2)conversion using solid oxide electrolysis cells(SOECs).In this work,we investigated a kW-level catalytic combustion burner and SOEC stack,evaluated the electrochemical performance of the SOEC stack in H2O electrolysis and H2O/CO_(2)co-electrolysis,and established a multiscale and multi-physical coupling simulation model of SOFCs and SOECs.The process developed in this work paves the way for the demonstration and deployment of IGFC technology in the future.

Gasification of lignite from Polish coal mine to hydrogen-rich gas

The efforts of the world research activities involved in clean coal technologies development focus to a considerable extent on integrated hydrogen and power generation technologies based on coal gasification.As an alternative to combustion pro-cesses,gasification offers increased efficiency,lower negative environmental impact as well as wider application range of the main product—synthesis gas—in power generation and chemical syntheses.In order to select the most optimal lignite for the purpose of gasification,it is necessary to determine coal reactivity,the key parameter characterizing how fast the fuel reacts with the gasifying medium and controlling its process ability in thermochemical conversion to energy and/or energy carriers.This paper presents the experimental results of oxygen/steam gasification of lignite coal char in a fixed bed reactor under atmospheric pressure and at the temperature of 700,800 and 900℃;the samples come from an open pit lignite mine in the southwest of Poland.The effectiveness of the gasification process was tested in terms of the total gas and hydrogen yields,gas composition,carbon conversion rate and chars reactivity.

Technology Roadmap of IGCC Industry in China

With the increasing energy demand and environmental pressures caused by consumption of fossil fuels, the world casts their eyes on new energy, hoping to transform the existing energy structure through technological innovation to new energy field, to promote the optimization and upgrading of the world’s energy structure. The new energy in key areas of Chinese high-tech industries includes mainly nuclear power, wind power, solar power, IGCC (Integrated Gasification Combined Cycle), new energy vehicles and smart grids. The present paper will carry on an in-depth study on IGCC industry technology roadmap in China. Technology roadmap is a kind of technology management tool, expressing the structure and time dimension of technical elements’ evolution with icons. It spans a wide range of applications from a single company to industry, and national and international coalition, from detailed product technology to component technology, as well as the integration of several relevant industry technologies. The roadmap is a kind of multi-layered time-dependent icon. IGCC industry has excellent environmental characteristics and benefits, which are in accordance with the principle of coordinated development between energy and environment. Based on the analysis of current situation, market demand, industry objectives and technical barriers of IGCC technology, we highlight IGCC industrial development model with Chinese characteristics, and concisely propose the major research needs and technology projects of key technology areas in IGCC industry. We highlight IGCC industrial development model with Chinese characteristics, and concisely propose the major research needs and technology projects of key technology areas in IGCC industry. Furthermore, some relevant suggestions on IGCC technology management and industry development are put forward to promote the remarkable progress in the development of IGCC industry in China and build an efficient, economical and clean sustainable energy supply system in line with the requirements of low-carbon economy.

An analysis of new generation coal gasification projects

The global trends of increasing oil and gas costs have compelled coal possessing countries to start long term underground coal gasification （UCG） projects. These enhance national energy security and are among the cleanest, ecologically safest coal utilization technologies. This paper delineates the major characteristics of such technologies and analyzes technical solutions. Highlighting the desire to develop large scale industrial UCG plants, pilot level projects are presented using a new UCG method developed in Russia by Joint Stock Company Gazprom Promgaz. This method is distinct for its high controllability, stability, and energy efficiency. New, efficient technical solutions have been developed over the last 10-15 years and are patented in Russia. They guarantee controllability and stability of UCG gas produc- tion. Over one hundred iniection and gas production wells have been operated simultaneously.

Production of synthetic hydrocarbons from coal through its underground gasification

The problem of the high-level processing of coal into synthetic motor fuels assumes worldwide actual meaning nowadays. Thereat, it is important especially for countries and regions which possess extensive coal resources and are forced to be guided by the import of liquid and gas hydrocarbons. However, a greater emphasis is paid to the given issue in Russia-The development of the federal program for highlevel processing of coal into synthetic motor fuels was initiated. This article describes options of underground coal gasification (UCG) use for the generation of hydrocarbons from UCG gas in the process of the Fischer-Tropsch synthesis (FTS). The technical and economic analysis of the integrated UCG-FTS powerchemical factories has detected their investment attractiveness and practicability of experimental-industrial testing at coal deposits of the Russian Federation.

Semi-Industrial Test of Underground Coal Gasification In Well No.2 in Xinhe, Xuzhou

The necessity of underground coal gasification is explained. The condition,technology character,and process of the semi-industrial test of underground coal gasification in well No. 2 at Xinhe, Xuzhou,are introduced. The test results indicate that the technique of long tunnel,large sectiou,two stage underground coal gasification can obtain a large output of coal gas with a high heat value, making the working process stable. So the feasibility of the new techuology is verified. It can be concluded that there will have a good application prospect of the technique in China.

Employment of Two-Stage Oxygen Feeding to Control Temperature in a Downdraft Entrained-Flow Coal Gasifier

The traditional practice of employing a two-stage coal-fed gasification process is to feed all of the oxygen to provide a vigorous amount of combustion in the first stage but only feed the coal without oxygen in the second stage to allow the endothermic gasification process to occur downstream of the second stage. One of the merits of this 2-stage practice is to keep the gasifier temperature low downstream from the 2nd stage. This helps to extend the life of refractory bricks, decrease gasifier shut-down frequency for scheduled maintenance, and reduce the maintenance costs. In this traditional 2-stage practice, the temperature reduction in the second stage is achieved at the expense of a higher than normal temperature in the first stage. This study investigates a concept totally opposite to the traditional two-stage coal feeding practices in which the injected oxygen is split between the two stages, while all the coal is fed into the first stage. The hypothesis of this two-stage oxygen injection is that a distributed oxygen injection scheme can also distribute the release of heat to a larger gasifier volume and, thus, reduce the peak temperature distribution in the gasifier. The increased life expectancy and reduced maintenance of the refractory bricks can prevail in the entire gasifier and not just downstream from the second stage. In this study, both experiments and computational simulations have been performed to verify the hypothesis. A series of experiments conducted at 2.5 - 3.0 bars shows that the peak temperature and temperature range in the gasifier do decrease from 600?C - 1550?C with one stage oxygen injection to 950?C - 1230?C with a 60 - 40 oxygen split-injection. The CFD results conducted at 2.5 bars show that 1) the carbon conversion ratio for different oxygen injection schemes are all above 95%;2) H2 (about 70% vol.) dominates the syngas composition at the exit;3) the 80% - 20% case yields the lowest peak temperature and the most uniform temperature distribution along the gasifier;and 4) the 40% - 60% case produces the syngas with the highest HHV. Both experimental data and CFD predictions verify the hypothesis that it is feasible to reduce the peak temperature and achieve more uniform temperature in the gasifier by adequately controlling a two-stage oxygen injection with only minor changes of the composition and heating value of the syngas.

Implementation of a Demoisturization and Devolatilization Model in Multi-Phase Simulation of a Hybrid Entrained-Flow and Fluidized Bed Mild Gasifier

A mild gasification process has been implemented to provide an alternative form of clean coal technology called the Integrated Mild Gasification Combined Cycle (IMGCC), which can be utilized to build a new, highly efficient, and compact power plant or to retrofit an existing coal-fired power plant in order to achieve lower emissions and significantly improved thermal efficiency. The core technology of the mild gasification power plant lies on the design of a compact and effective mild gasifier that can produce synthesis gases with high energy volatiles through a hybrid system: utilizing the features of both entrained-flow and fluidized bed gasifiers. To aid in the design of the mild gasifier, a computational model has been implemented to investigate the thermal-flow and gasification process inside this mild gasifier using the commercial CFD (Computational Fluid Dynamics) solver ANSYS/FLUENT. The Eulerian-Eulerian method is employed to model both the primary phase (air) and the secondary phase (coal particles). However, the Eulerian-Eulerian model used in the software does not facilitate any built-in devolatilization model. The objective of this study is therefore to implement a devolatilization model (along with demoisturization) and incorporate it into the existing code. The Navier-Stokes equations and seven species transport equations are solved with three heterogeneous (gas-solid) and two homogeneous (gas-gas) global gasification reactions. Implementation of the complete model starts from adding demoisturization first, then devolatilization, and then adding one chemical equation at a time until finally all reactions are included in the multiphase flow. The result shows that the demoisturization and devolatilization models are successfully incorporated and a large amount of volatiles are preserved as high-energy fuels in the syngas stream without being further cracked or reacted into lighter gases. The overall results are encouraging but require future experimental data for verification.

Characterization of Size and Density Separated Fractions of a Bituminous Coal as a Feedstock for Entrained Slagging Gasification

Coal is one of the main sources of energy in many parts of the world and has one of the largest reserves/production ratios amongst all the non-renewable energy sources. Gasification of coal is one among the advanced technologies that has potential to be used in a carbon constrained economy. However, gasification availability at several commercial demonstrations had run into problems associated with fouling of syngas coolers due to unpredictable flyash formation and unburnt carbon losses. Computer models of gasifiers are emerging as a powerful tool to predict gasifier performance and reliability, without expensive testing. Most computer models used to simulate gasifiers tend to model coal as a homogenous entity based on bulk properties. However, coal is a heterogeneous material and comminution during feedstock preparation produces particle classes with different physical and chemical properties. It is crucial to characterize the heterogeneity of the feedstocks used by entrained flow gasifiers. To this end, a low ash US bituminous coal that could be used as a gasifier feedstock was segregated into density and size fractions to represent the major mineral matter distributions in the coal. Float and sink method and sieving were employed to partition the ground coal. The organic and inorganic content of all density fractions was characterized for particle size distribution, heating value, ultimate analysis, proximate analysis, mineral matter composition, ash composition, and petrographic components, while size fractions were characterized for heating value, ash composition, ultimate and proximate analysis. The proximate, ultimate and high heating value analysis showed that variation in these values is limited across the range of size fractions, while the heterogeneity is significant over the range of density fractions. With respect to inorganics, the mineral matter in the heavy density fractions contribute significantly to the ash yield in the coal while contributing very little to its heating value. The ash yield across the size fractions exhibits a bimodal distribution. The heterogeneity is also significant with respect to the base-to-acid ratio across the size and density fractions. The results indicate that the variations in organic and inorganic content over a range of density and size classes are significant, even in the low ash, vitrinite rich coal sample characterized here. Incorporating this information appropriately into particle population models used in gasifier simulations will significantly enhance their accuracy of performance predictions.

Clean coal technologies in Japan： A review

Coal is the primary fossil fuel most used in the world for the electricity generation, iron making, and cement/concrete and chemical production. However, utilization of coal also results in emissions of CO_2, SO_x, NO_x and other noxious compounds. The development of clean coal technology(CCT) is a main issue to maintain a clean environment. CCT in Japan is considered the highest level in the world. In this review, the developing CCTs in Japan including high efficiency combustion technologies, advanced gasification technologies, CO_2 recovery and utilization technologies, and flue gas cleaning technologies are introduced and discussed. It is expected to provide some new view-of-points for CCT development.

An Investigation on Performance of a Horizontal Entrained Flow Gasifier

A novel study on biomassair gasification using a horizontal entrained-flow gasifier has been conducted. The use of a horizontal entrained-flow gasifier reactor was employed to assess the effect of the gasifier reactor orientation on the gasification process. The gasification experiments were conducted at 800℃ and equivalence ratio of 0.23 while maintaining gas hourly space velocity (GHSV) of 8000 h-1. Preparation and characterisation of wood powder were performed using classical methods. The research findings showed that maximum fuel conversion and cold gas efficiency using a horizontal entrained-flow gasifier were 99% and 70% respectively compared to 91% and 62% respectively of the vertical design. Moreover, the gasifier length can also be reduced from the common 1000 - 2000 mm to 500 mm. In general, the results of this study suggest that there exists a sensitivity to the gasifier orientation on the overall gasification process.

Simulation of Ash Deposition Behavior in an Entrained Flow Coal Gasifier

Fly ash deposition is an important phenomenon associated with ash/slag handling and discharge in the entrained-flow coal gasification process. Fouling and slagging inside the gasifier may cause reliability and safety problems because they can impose strong negative effects on the gasifier wall in the way of heat transfer and chemical corrosion. For these reasons, this study focuses on investigating the ash deposition distribution inside of a two-stage entrained-flow gasifier. The computational model is developed in order to simulate the gasification process with a focus on modeling ash formation, fly ash, and ash deposition. The Eulerian-Lagrangian approach is applied to solve the reactive thermal-flow field and particle trajectories with heterogeneous reactions. The governing equations include the Navier-Stokes equations, twelve species transport equations, and ten global chemical reactions consisting of three heterogeneous reactions and seven homogeneous reactions. The coal/ash particles are tracked with the Lagrangian method. The effects of different coal/ash injection schemes and different coal types on ash deposition have been investigated. The results show that the two-stage fuel feeding scheme could distribute the ash throughout a larger gasifier’s volume and, hence, could reduce the peak ash deposition rate and make the ash distribution more uniform inside the gasifier. Gasification of a high-ash coal results in a high ash deposition rate, low syngas higher heating value (HHV), and low carbon conversion rate. The result of ash deposition rate in this study can be used as a boundary condition to provide ash particle influx distribution for use in slagging models.

气化炉内熔渣流动特性预测模型的研究进展

双碳战略目标下,煤气化技术将会是我国未来煤炭领域的重要发展路线。在煤气化技术推广应用中,熔渣的流动行为严重影响气化炉的平稳运行时长,间接影响合成气的质量和炉壁的热量损失,有效求解流动参数的熔渣流动特性预测模型备受关注。本研究论述了现有的气化炉内熔渣流动特性的预测模型,并展望了预测模型的未来研究方向。综述当下,预测模型根据熔渣流动维数可分为一维预测模型和二维预测模型;一维稳态和非稳态预测模型均经历了构建和完善阶段;二维预测模型因无相关的数学公式描述和流动理念假设尚处于构建阶段;通过对液态熔渣的温度分布、附加应力的取舍,临界黏度的选取和熔渣黏度的处理方式等方面可以提高模型的计算精度。展望未来,一维预测模型的应用场景需更完善的规定,针对稳态和非稳态预测模型求解的参数需要更细致的辨析;二维预测模型的构建理论需更详细的突破,明确非稳态工况下熔渣在轴向和周向上流动的优先级;流动预测模型的计算精度需更全面的提升,熔渣性质的非恒定性、熔化的不均匀性、烟气流速的波动性等因素需要侧重考虑。

煤化工生产技术路线及产品现状

中国煤炭资源丰富,是我国重要的能源资源,传统煤炭加工过程中能耗高,污染大,对环境和人体健康产生严重影响。在“双碳”背景、能耗双控政策影响下,选择合适的路线生产具有市场竞争力的产品是一个战略性的问题。文章从煤炭焦化、气化、液化三个方面综述了煤化工生产的技术路线及产品现状,并对其发展趋势进行预测,以期为煤化工产品路线选择提供参考。

生物质气化的研究进展

生物质能源具有安全性高、环保性强、分布广泛、易储存运输和产量大的优点,生物质能已成为继三大化石能源后的第四大能源,生物质气化作为生物质的一种重要应用形式,具有巨大的发展潜力和价值。介绍了生物质气化的概念、基本原理,并分析了气化剂气化、热解气化、催化气化、等离子体气化、超临界水气化等气化技术的优缺点,同时阐述了固定床气化炉、流化床气化炉、气流床气化炉、回转窑炉和等离子气化炉的工作原理及各自优缺点,最后指出生物质气化技术目前面临的问题,提出解决措施。