中试规模的第二代增压流化床联合循环发电技术研究与开发

第二代增压流化床联合循环发电技术(2G PFBC-CC)是当前具有应用前景的洁净煤发电技术之一。东南大学热能工程研究所构建了2 MWt加压喷动流化床部分气化炉,对原有1 MWt增压流化床燃烧炉进行了改造,形成了较完整的2G PFBC-CC系统．经过二年多的调试和试验研究,验证了2G PFBC-CC工艺可行性和先进性,部分气化炉产生的煤气热值在4．2 MJ／Nm3以上,满足燃气透平的要求,排出的半焦可在PFB燃烧炉内稳定燃烧,飞灰含碳量在2％以下,系统碳利用效率在99％以上。     

Single-port optical access for spectroscopic measurements in industrial flue gas ducts

An in situ optical access to industrial-scale flue-gas ducts under high pressure has been designed and realised. The system is used here for the determination, by excimer-laser-induced fragmentation fluorescence (ELIF), of alkali species released from the combustion of coal in a pressurised circulating fluidised bed (PCFB) combustor. However, it could be applied to the detection of other species in a variety of industrial plants. The essential feature of the design is the access for the light source and collection of signal via the same, single window. The set-up is compact, robust and durable, having been tested under realistic flue-gas conditions for periods of up to two weeks in the PCFB pilot plant. The main features of the access are described and examples of data collected are presented to demonstrate its capabilities. Received: 3 August 1998 / Revised version: 16 February 1999 / Published online: 26 May 1999     

Developments in geothermal energy in Mexico—part twenty-three. Operation of Cerro Prieto II and III power generation plants

Geothermal plants Cerro Prieto II and III of 220 MW_e each achieved excellent operating conditions during 1987 with plant factors of 0.74 and 0.85, respectively. This demonstrates the operation of large geothermal plants with plant factors higher than have been achieved in Mexican thermoelectric plants.With the total installed capacity in the Cerro Prieto field of 620 MW_e, 14.4 PJ_e (4 TW h) of electrical power have been generated, which represents a saving of 7.55 million barrels of oil.     

Oxy-coal combustion in a 30 kWth pressurized fluidized bed: Effect of combustion pressure on combustion performance,pollutant emissions and desulfurization

Oxy-coal combustion with pressurized fluidized beds has recently emerged as a promising carbon capture and storage (CCS) technology for coal-fired power plants. Although a large number of energy efficiency analyses have shown that an increase in combustion pressure can further increase the net plant efficiency, there are few experimental studies of pressurized oxy-coal combustion conducted on fluidized bed combustors/boilers with continuous coal feeding. In this study, oxy-coal combustion experiments with lignite and anthracite were conducted with a 30 kW_th pressurized fluidized bed combustor within the pressure range of 0.1 MPa to 0.4 MPa. The investigation focused on the elucidation of the impacts of combustion pressure on the combustion performance, pollutant emissions and desulfurization of oxy-coal combustion in fluidized beds. The results showed that an increase in pressure increased the combustion efficiency and combustion rate of coal particles, and the promoting effect of pressure increase was more significant for the high rank coal with smaller particle size and the high O₂ concentration atmosphere. For both coals, NO_x emissions decreased with pressure but N₂O emissions increased with pressure and accounted for a considerable part of the nitrogen oxide pollutants under high pressure oxy-coal combustion conditions. The pressure had insignificant impact on the SO₂ emissions of oxy-coal combustion but an increase in pressure enhanced the direct desulfurization of limestone.     

煤中痕量元素在低温燃烧下的分布规律

为了解流化床燃烧过程中痕量元素的分布与富集规律,以流化床燃煤过程为研究对象,在实验室的小型机理性试验台架上进行实验,研究了煤中痕量元素的排放特点。实验模拟流化床低温燃烧的特点, 6种典型煤分别在650℃、800℃、950℃三个工况下燃烧,分析得到Pb、Cr、Cd等痕量元素大部分留在灰中。Hg在灰中的富集规律不明显。     

Influence of combustion temperature and coal types on alumina crystal phase formation of high-alumina coal ash

The alumina content (more than 40%) of high-alumina coal ash is comparative to the middle content bauxite ores in China. So far, in order to meet the high demand of alumina and the rise of circular economy industrial chain, extracting alumina from coal ash has become a way to comprehensively utilize high-alumina coal ash. However, this process has high requirements on the crystal phase and stability of alumina. Different from most studies, this paper focuses on how to produce coal ash more beneficial to the later refining of aluminum. Therefore, the effects of combustion temperature and coal types by classifying high-alumina coal into dull coal and bright coal on alumina crystal phase formation were studied. Through proximate analysis, ultimate analysis, calorific value analysis, X-ray fluorescence spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM) and other methods, it is found that γ-Al₂O₃ in high-alumina coal ash translated into more stable θ-Al₂O₃ and finally α-Al₂O₃ when combustion temperature is higher than 1000°C. Thus compared with pulverized coal boilers, circulating fluidized bed (CFB) boilers with lower combustion temperature can produce higher quality coal ash. Moreover, at the same combustion temperature, alumina crystal phase in dull coal ash is relatively less stable than that in bright coal ash, which is more suitable to the later refining and electrolysis of aluminum.     

循环流化床热电气三联产装置研究

循环流化床热电气三联产装置研究岑可法，方梦祥，骆仲泱，李绚天，陈飞，王勤辉，陈冠益，倪明江（浙江大学热能工程研究所杭州３１００２７）关键词循环流化床，气化，煤气蒸汽联产１前言在近几年来，我国能源仍主要以煤炭为主，而目前煤炭的绝大部分作为燃料直接燃用，...     

燃煤循环流化床燃烧脱硫的模型预测

燃煤循环流化床燃烧脱硫的模型预测池涌，岑可法，倪明江Ｐ·Ｂａｓｕ（浙江大学能源系杭州３１００２７）关键词：循环流化床，燃烧，脱硫，模型预测一、引言循环流化床锅炉在过去十几年中得到了广泛的应用，但与此同时由于循环流化床内流体动力特性的高度复杂使得数学模...     

循环流化床煤燃烧中氮氧化物排放的研究

循环流化床煤燃烧中氮氧化物排放的研究冯波，袁建伟，刘皓，卢建欣，林志杰，刘德昌（华中理工大学动力系武汉４３００７４）关键词循环流化床，氮氧化物１前言近年来，ＮＺＯ由于对臭氧层的破坏作用和一定的温室效应而引起了较大的关注。特别地，在流化床煤燃烧中（包括...     

Development in geothermal energy in mexico—part twenty seven: The potential for geothermal organic rankine cycle power plants in Mexico

Mexico possesses large amounts of geothermal energy. Samples from over 800 geothermal surface phenomena indicate that only 1.1% have an estimated reservoir temperature greater than 200°C. Current practice in Mexico is to produce power from such reservoirs using an open flash steam cycle. It is estimated that 4.8% of geothermal resources are in the temperature rangefrom 140 to 200°C which is a suitable range in which to operate Organic Rankine cycle power plants. Organic Rankine cycle power plants have been built in a range of sizes from 10kW_e to 45 MW_e. They have considerable potential for increasing the production of electricity from Mexico's geothermal resources. Organic Rankine cycle plants are discussed together with the conditions for their economic operation.     

Simulation of a combined cycle power plant based on a pressurized circulating fluidized bed combustor

A comprehensive mathematical model for the simulation of a pressurized circulating fluidized bed combustor will be presented. The model consists of a combustor model describing the combustion chamber, the cyclone and the external heat exchanger as well as of a gas turbine model. The results of the simulation for the combustor at full load and different pressures and for the combined cycle power plant at full and part load are presented in form of temperature-, flue gas composition- and heat transfer-profiles in the combustor. Especially, energy fluxes from the combustor to the water-/steam cycle and the output of gas- and steam-turbine will be shown. The validity of the model will be shown by comparative simulation of an existing plant for the special case of atmospheric conditions.     

城市垃圾与煤混烧的灰渣中重金属的特性分析

在0.15MWt循环流化床燃烧试验台上进行了城市垃圾与煤混烧试验,对焚烧后的灰渣中重金属的特性进行了研究。研究结果显示,重金属在焚烧产物中通常以不同的化合物形态存在,改变垃圾与煤混烧时的燃烧工况条件,可以改变重金属的化合物形态,从而改变重金属在灰渣中的分布;灰渣中重金属的浸出毒性低于危险废物浸出毒性鉴别标准中的限定值。     

振动流化床冷渣器试验研究

本文提出了冷却高温炉渣的振动流化床技术，研制了集连续可控排放和冷却于一体的新型冷渣器工业装置．采用物理性质相异法较系统地研究了冷渣器内宽筛分物料的停留时间分布．对气固两相流的空气动力学特性和热态运行工况进行了试验研究和理论分析．结果表明，在风渣比为1．5～2．5Nm3／kg时，冷渣器的热回收率达到85％以上．     

城市下水污泥和煤/LPG在循环流化床上的混烧试验研究

在高6000 mm、直径300mm的循环流化床上进行了含水率为79％的湿污泥与煤／石油液化气(LPG)的混烧试验。试验结果表明:无论用煤还是LPG作为辅助燃料,试验都能在设定的工况条件下稳定运行;向炉内加入石灰石的量达到钙硫摩尔比为3．4∶1时,二氧化硫和氯化氢的排放达标,脱硫效率和脱氯效率分别为75％和94％;在试验中, 烟气中NOx排放、烟气中汞含量和二恶英类排放都不超标;试验产生的飞灰含碳量低,飞灰中痕量元素的浸出毒性不超标;计算表明,如果利用余热干燥污泥和预热空气可有效地减少辅助燃料的消耗量。     

Developments in geothermal energy in Mexico—part thirty-five. Direct contact and surface condensers in geothermal electric power plants

At present, direct contact condensers are the most widely used type in geothermal plants around the world. They have technical and economic advantages over surface condensers. The latter are only used where there are environmental problems associated with the release of polluting gases to the atmosphere, principally hydrogen sulphide.The non-condensable gas chemistry is an important factor in the decision to select direct contact or surface condensers. When plant emissions are strictly limited, surface condensers are used. In the Cerro Prieto geothermal field a total capacity of 620 MW_e has been installed. The field is in a large open valley with constant winds. This provides very good dispersion of the hydrogen sulphide released. However, further increases in installed capacity will need to incorporate control of hydrogen sulphide releases. Thus the Comisión Federal de Electricidad (CFE) has plans to build future plants with surface condensers and sulphur recovery systems.     

Investigation of chemical looping combustion of natural gas at 1 MWth scale

Chemical looping combustion (CLC) is an advanced oxyfuel process that enables CO₂ capture with low efficiency penalty. CLC of gaseous fuels has successfully been demonstrated in several pilots up to 150 kW_th. Numerous oxygen carriers have been tested regarding fuel conversion performance and lifetime. This work is a scale-up study of gaseous fuel CLC to MW_th scale. A Ca-Mn-based oxygen carrier has been developed and manufactured in ton-scale prior to the present test. Investigations were conducted in a 1 MW_th CLC unit that was adapted to utilize natural gas as fuel. Stable CLC conditions were reached during tests with Ca-Mn-based material, and the transition to operation with ilmenite was studied. The fuel conversion was in the range of 80%. During operation, 99% of the unburned methane was converted in the post oxidation chamber. The solids circulation rate and the lifetime of solids were determined by means of solids samples from the process, which were investigated in terms of attrition and degree of oxidation. The solids circulation rate was 17 tons h^?1  MW^?1 which is higher than in former tests but lower compared to other units. The most important limiting factors of the fuel conversion are the low solids inventory of the fuel reactor and the oxygen carrier to fuel ratio that corresponds to the solids circulation.     

In-situ gasification chemical looping combustion of plastic waste in a semi-continuously operated fluidized bed reactor

Conventional air incineration of plastic waste has been considered as one of important sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) through de novo synthesis and precursor conversion. Chemical looping combustion (CLC) is an attractive technology for the conversion of plastic wastes to energy with the potential to drastically suppress the formation of PCDD/Fs. In this paper, the iG-CLC (in-situ gasification CLC) experiments of plastic waste were implemented in a semi-continuously operated fluidized bed reactor, which actually simulates the fuel reactor of a continuously-operated interconnected fluidized bed reactor. A kind of low-cost material, natural iron ore without/with 5 wt% CaO adsorbent through the ultrasonic impregnation method, was used as oxygen carrier (OC). Firstly, some key performances of the reactor system, such as the relevance of the bed inventory to the flow rate of fluidizing agent as well as the relationship between the feeding rate and overflow rate of OC, were calibrated. Then, 90 min of single experiment was conducted for each experimental case and an accumulative operation of more than 10 h was attained. Typically, the combustion efficiency can reach at about 98%, and both the carbon conversion and CO₂ yield can approach to 95% at 900 °C and input thermal power of 150 W with a mixture of 5 vol% H₂O and 95 vol% N₂ as the fluidizing agent (U_FR/U_mf = 3). Moreover, the results obtained in the semi-continuously operated fluidized bed reactor demonstrated that CaO decoration to iron ore is conductive to suppressing the formation of chlorobenzene (as a toxic matter and precursor/intermediate of PCDD/Fs) and does not obviously deteriorate the OC performance.     

流化床焚烧炉中颗粒扩散特性理论研究

本文建立了流化床焚烧炉中粒子扩散方程,通过求解方程,得到了鼓泡床和内旋流床中颗粒扩散特性,并与试验结果进行了对比,两者符合较好。结果表明鼓泡床横向扩散能力较差,而内旋流床有很好的横向扩散特性,非常有利于废弃物在床内的快速扩散。     

Combustion of slugs of propane and air moving up through an incipiently fluidized bed

A mathematical model is proposed to show the evolution of temperature, chemical composition and energy release or transfer in slugs, clouds and particulate phase, in a fluidized bed where there are slugs, of a mixture of air and propane, moving up through the particulate phase previously set in the state of incipient fluidization with air. The analysis begins as the slugs are formed at the orifices of the distributor, until they explode inside the bed or emerge at the free surface. The model also makes the analysis of what happens in the gaseous mixture that leaves the free surface of the fluidized bed until the propane is thoroughly burnt. It is essentially built upon a simple quasi-global mechanism for the combustion reaction and the mass and heat transfer equations from the two-phase model of fluidization. The aim was not to propose a new modelling approach, but to combine classical models, one concerning the reaction kinetics and the other the bed hydrodynamic aspects, to obtain a better insight on the events occurring inside a fluidized bed reactor, enhancing the understanding of this type of reactor. Experimental data to balance with the numerical model were obtained through tests on the combustion of commercial propane, in a laboratory scale fluidized bed, using four sand particle sizes: 400–500, 315–400, 250–315 and 200–250 μ m. The mole fractions of CO₂, CO and O₂ in the flue gases and the temperature of the fluidized bed were measured and compared with the numerical results.     

Mechanism on the contribution of coal/char fragmentation to fly ash formation during pulverized coal combustion

In this paper, the correlations between coal/char fragmentation and fly ash formation during pulverized coal combustion are investigated. We observed an explosion-like fragmentation of Zhundong coal in the early devolatilization stage by means of high-speed photography in the Hencken flat-flame burner. While high ash-fusion (HAF) bituminous and coal-derived char samples only undergo gentle perimeter fragmentation in the char burning stage. Simultaneously, combustion experiments of two kinds of coals were conducted in a 25?kW down-fired combustor. The particle size distributions (PSDs) of both fine particulates (PM_1-10) and bulk fly ash (PM₁₀₊) were measured by Electrical Low Pressure Impactor (ELPI) and Malvern Mastersizer 2000, respectively. The results show that the mass PSD of residual fly ash (PM₁₊) from Zhundong coal exhibits a bi-modal shape with two peaks located at 14?µm and 102?µm, whereas that from HAF coal only possesses a single peak at 74?µm. A hybrid model accounting for multiple-route ash formation processes is developed to predict the PSD of fly ash during coal combustion. By incorporating coal/char fragmentation sub-models, the simulation can quantitatively reproduce the measured PM₁₊ PSDs for different kinds of coals. The sensitivity analysis further reveals that the bi-modal mass distribution of PM₁₊ intrinsically results from the coal fragmentation during devolatilization.