Thermochemical conversion of fuels into hydrogen-containing gas using recuperative heat of internal combustion engines

The problem of the thermochemical recuperation of heat from the exhaust gases of internal combustion engines (ICEs) as a method of increasing of the efficiency of fuels has been considered. The thermodynamic analysis of thermochemical recuperation conditions was performed, and maximum efficiency conditions were determined. Catalysts for the steam conversion of oxygen-containing fuels into syngas were developed, and the Co-Mn/Al₂O₃ catalyst was shown to be the most promising. The model of a thermochemical heat recuperation system was developed and manufactured, and its bench tests in the conversion of alcohols were performed using the simulated exhaust gases from a heating device. Mathematical models for calculating units of the heat recuperation system were developed. A recuperation system was manufactured and tested in the ICE-free and ICE-integrated variants. Based on the test results, the equivalent fuel consumption characteristics of a recuperative ICE was revealed to decrease by 11–22% depending on its load with a decrease in the concentration of hazardous emissions by 8–12 times for CO, 2–3.5 times for CH, and 18–25 times for NO _x .     

褐煤锅炉冷端优化热力系统技术经济性比较

对电站锅炉排烟余热进行回收,使一部分锅炉冷端烟气热能梯级利用于汽轮机回热系统,是燃煤电厂增效减排的重要途径。以某600MW超临界燃褐煤机组为例,对低温省煤器、送风分段预热和旁通烟道3种锅炉冷端优化热力系统进行了热经济性与技术经济性比较。结果表明,由上述3种系统回收锅炉排烟由148℃降温至90℃余热,机组供电标准煤耗率分别减小4.43g/（kW·h）、5.84g/（kW·h）和6.48g/（kW·h）,项目投资分别为2562万元、2348万元和2261万元。以机组在THA工况下年运行5500h计,3种系统每年由节煤增加净收益994万元、1350万元和1514万元,动态投资回收期分别为3.13年、2.00年和1.71年。可见褐煤锅炉排烟余热回收可明显提高电厂效率。3种冷端优化热力系统中,旁通烟道系统展示出最优的热经济性和技术经济性,建议对其进一步研究和应用。     

硫酸装置除氧器乏汽回收节能技术改造

目前硫酸装置废热锅炉给水大多采用热力除氧,除氧后的蒸汽夹杂部分不凝气体,直接排空造成热能损失和环境污染,还伴随有放空噪声。介绍云南三环中化化肥有限公司利用蒸汽节能器回收除氧器乏汽的技改工艺及其应用效果,并对其经济效益进行分析。结果表明,采用该乏汽回收系统可以实现乏汽热能完全回收利用,既节约了能源,又消除了排空乏汽的噪声污染,改善厂区环境,每年可产生114.224万元的经济效益。     

稀土在汽车排气催化净化中的应用

催化剂技术是治理汽车污染的重要措施之一，作为催化剂组分的稀土在其中起了重要的作用。本文讨论了稀土在汽车排气催化净化中的应用。其作用在于：提高了载体性能，储氧功能，提高催化剂的抗中毒性，提高催化剂热稳定性，作为助剂，应用在氧传感器中等。     

Energy analysis of a lignite predrying power generation system with an efficient waste heat recovery system

Lignite has been extensively used for electricity generation in many regions worldwide. However, its high water content has obviously negative effect on plant thermal efficiency. Performance of lignite-fired power plant can be improved by predrying the lignite before combustion. In addition, recovery of waste heat from the dryer and the power generation system will enhance the plant thermal efficiency further. In the present study, a new lignite predrying power generation system integrated with an efficient waste heat recovery system was proposed. Both dryer exhaust waste heat and steam turbine exhaust latent heat were recovered to heat boiler feed water. Energy analysis indicates that system performance is improved significantly. The plant thermal efficiency increases linearly with drying degree and then increases at a lower rate. The generation of unused dryer exhaust changes the variation tendency of system performance with drying degree.     

冷凝水-乏汽余热回收技术在轮胎硫化工艺中的应用

对硫化工艺中冷凝水一乏汽的价值进行了介绍;列冷凝水一乏汽余热回收技术特点进行了详细说明;对乏汽余热回收装置技术原理和应用情况进行了细致论述;最后对经济效益和环境效益进行了认真分析。     

Site-wide low-grade heat recovery with a new cogeneration targeting method

One of the key performance indicators for designing site utility systems is cogeneration potential for the site. A new method has been developed to estimate cogeneration potential of site utility systems by a combination of bottom-up and top-down procedures, which allows systematic optimization of steam levels in the design of site utility configurations. A case study is used to illustrate the usefulness of the new cogeneration targeting method and benefits of optimizing steam levels for reducing the overall energy consumptions for the site. Techno-economic analysis has been carried out to improve heat recovery of low-grade waste heat in process industries, by addressing a wide range of low-grade heat recovery technologies, including heat pumping, organic Rankine cycles, energy recovery from exhaust gases, absorption refrigeration and boiler feed water heating. Simulation models have been built for the evaluation of site-wide impact associated with the introduction of each design option in industrial energy systems in the context of process integration. Integration of heat upgrading technologies within the total site has been demonstrated with a case study for the retrofit scenario.     

Utilisation of waste heat from exhaust gases of drying process

Nowadays a lot of low-grade heat is wasted from the industry through the off- and flue-gasses with different compositions. These gases provide the sensitive heat with utilisation potential and latent heat with the components for condensation. In this paper, process integration methodology has been applied to the partly condensed streams. A hot composite curve that represents the gas mixture cooling according to equation of state for real gases was drawn to account the gas-liquid equilibrium. According to the pinch analysis methodology, the pinch point was specified and optimal minimal temperature difference was determined. The location of the point where gas and liquid phases can be split for better recuperation of heat energy within heat exchangers is estimated using the developed methodology. The industrial case study of tobacco drying process off-gasses is analysed for heat recovery. The mathematical model was developed by using MathCad software to minimise the total annualised cost using compact plate heat exchangers for waste heat utilisation. The obtained payback period for the required investments is less than six months. The presented method was validated by comparison with industrial test data.

Open image in new window

     

热管式通风换热器热回收的实验研究

针对普通住宅日常通风换气的特点设计出一台小型热虹吸管式通风换热器的样机,并利用热虹吸管换热器对房间通风系统中的冷量(热量)进行热回收实验研究。通过实验测试了该换热器在不同风量和新、排风温差条件下的热回收效率,以及新、排风的压力损失随风速的变化情况。实验结果表明,新风的温降(升)随着新、排风温差的增大而增大,随着风量的增大而减小;该样机的最大热回收效率在夏季可达70%,冬季为63%,新、排风的最大阻力损失仅为25 Pa,节能效果显著。     

A practical approach for modelling and control of biomass pyrolysis pilot plant with heat recovery from combustion of pyrolysis products

A pilot plant of biomass pyrolysis using pyrolysis products as fuel has been tested and shown to improve energy balance of the process and to be environmentally friendly by avoiding rejection of pyrolysis pollutants fumes into the atmosphere. The high number of parameters involved in a pyrolysis process makes it difficult to specify an optimum procedure for charcoal yield and pyrolysis cycle durability. So the knowledge of the essential parameters which govern the kinetics mechanisms of the biomass thermal decomposition and the combustion of pyrolysis gases is very useful to understand the operating cycle of the plant. In the present study a thermochemical model is developed in order to simulate and control the operating cycle of the system. The effect of the inlet molar air flow rate on the temporal evolution of biomass mass loss rate and temperatures in the different active zones of the pilot plant as well as the determination of the critical inlet molar air flow rate for which accidental runaway of combustion reactions occurs are presented. To avoid this accidental phenomenon a Proportional-Integral-Derived (PID) anticipated regulation is used in order to control temperatures evolution in the different zones of the device and avoid the runaway of combustion reactions.     

高湿度工业废气冷凝脱湿模型研究与数值模拟

针对高湿度工业废气冷凝脱湿进行模型研究和数值模拟,引入分配系数α表征雾状冷凝和膜状冷凝并存的权重.恒壁温冷凝管外混合气体在环形空间湍流冷却冷凝的温度分布、湿度分布及其梯度（传热传质推动力）分布的模拟结果显示,雾状冷凝的控制机理是冷壁面附近温度梯度与湿度梯度协同作用下传热传质产生的局部过饱和;膜状冷凝从冷壁面移出大量冷凝潜热,促使气相主体传热传质过程更迅速,脱湿效果更好.实际过程介于二者之间.DAP尾气冷却冷凝现场实验传热传质数据,在水汽冷凝减量34%～57%的范围内,与α＝0.2的数值模拟结果相当吻合,验证了本文的模型与数值模拟.     

热化学复合吸附储热循环的理论及实验

对一种基于固-气可逆化学反应的热化学复合吸附储热循环的储热特性以及能量品位提升性能进行了理论分析,并以MnCl₂/SrCl₂/NH₃作为工质对进行了实验研究。理论分析表明,热化学复合吸附储热循环不仅可以降低外界驱动热源的温度并保证输出热能温度稳定,而且能大幅度地提升输出热能的温度品位。在MnCl₂和SrCl₂都参与放热的实验工况下,获得的储热效率为93.31%。MnCl₂复合吸附剂的总储热密度按单位质量反应盐MnCl₂和单位质量的固化吸附剂计量分别为4393.36和3734.36 kJ·kg^-1;SrCl₂复合吸附剂的总储热密度按单位质量反应盐SrCl₂和单位质量的固化吸附剂计量分别为1947.28和1655.19 kJ·kg^-1。结果表明,热化学储热是一种相当有潜力的储热方式,可为低品位热能的高效回收利用提供强有力的技术支持。     

Use of quantum-chemical methods in selecting catalysts for the removal of carbon and nitrogen oxides from exhaust gases

Carbon and nitrogen oxides contained in automobile exhaust gases are among the most hazardous air pollutants. Therefore, the search for new methods of the neutralization of noxious substances in exhaust gases is an urgent problem. Catalytic purification is among the most promising methods. The aim of this work is to show the applicability of quantum-chemical methods to the study of the mechanisms of NO _x reduction and CO oxidation on the Rh-catalyst surface. A faujasite zeolite was used as the carrier. Calculations showed that the support enhances the electrophilic properties of rhodium and, thus, improves its catalytic activity.     

一种天然气液化和CO2捕集相结合的余热回收发电系统

针对余热回收和能源利用的问题,以液化天然气(LNG)作为冷源,稠油开采废气作为热源,提出了一种结合天然气液化和废气发电与CO₂捕集的余热回收利用系统。分析了关键热力学参数对系统热力学性能的影响。结果表明：对于有机朗肯循环和制冷循环,增加透平膨胀机的进口温度,降低其出口压力以及减少制冷循环压缩机进出口的压缩比,可获得最大净输出功为454.9 kW,余热回收效率为34.2%。对于天然气液化系统,采用C++进行非线性约束优化计算,以氮膨胀制冷循环压缩机总功耗为目标函数进行优化,得到压缩机最优总功耗为101.54 kW。降低天然气压缩机(K110)进口温度,氮气膨胀机(T3)出口压力以及氮气质量流量,可获得最大LNG调峰量为378.8 kg/h,反之,CO₂捕集量可提高28.6%。     

汽车尾气排气系统冷启动热量传递数值模拟

发动机冷启动状态汽车尾气的排放情况对尾气排放控制起着关键的作用,文内建立了发动机冷启动状态排气系统传热、传质的非稳态单通道数学模型,通过对模型的数值求解,分析了汽车尾气排气系统温度的演变,经与实验结果对比,模型拟和与实验值能很好吻合。并模拟了催化器内尾气温度场的分布情况,对催化器的研究、设计具有重要意义。     

直冷式乏风热泵系统在小保当煤矿的应用分析

为实现煤矿企业清洁能源供热,针对煤矿生产矿井排出的乏风余热,采用目前国际先进的直冷式深焓取热乏风热泵系统供热技术替代传统的锅炉供热,解决我国北方煤矿企业冬季有防冻要求的进风井口供热需求。本文以小保当煤矿矿井乏风余热供热系统项目为例,阐述了直冷式深焓取热乏风热泵系统的间壁式（间接换式）乏风换热、乏风取热机组集尘及结霜原理;采用乏风取热机组清洗除尘和防结霜除霜解决方法,并与天然气锅炉、电锅炉两种供热方案进行对比,分析计算了三种方案的项目投资和系统运行费用,论述了各方案的优势和不足。分析表明,煤矿企业采用矿井乏风余热资源,利用直冷式深焓取热乏风热泵供热系统替代传统锅炉供热,技术可行,且具有更好的经济效益和应用效果。     

金属氧化物催化剂在消除柴油车排气颗粒物中的应用

介绍了用于柴油车排气颗粒物后处理的金属氧化物催化剂，包括过渡金属氧化物、主族金属氧化物和碱土金属氧化物。较详细地讨论了催化剂组成及性能、相关催化反应、控制因素和反应机理。     

Experimental research on convection–condensation heat transfer characteristics and sootblowing operation strategy of waste heat recovery heat exchanger for dryer exhaust

Abstract

In this study, air/water vapor mixture with ash particles was used to simulate actual dryer exhaust gas. An experimental study of the convection–condensation heat transfer characteristics of air/vapor mixtures with ash particles across horizontal tube-bundles was conducted under various water vapor mass fractions and concentrations of ash particles. The variation of convection–condensation heat transfer coefficient with time presented four different types, as follows: almost did not change with time; decreased first, then reached stable values; decreased continuously in the experimental time; and decreased rapidly, decreased slowly, and decreased rapidly, with potential to increase again. In general, the convection–condensation heat transfer coefficient decreased with increasing concentration of ash particles and increased with increasing water vapor mass fraction. The reducing effect on the convection–condensation heat transfer coefficient by ash deposition would be weakened by increasing the water vapor mass fraction, but the heat exchanger would be blocked further easily by increasing the concentration of ash particles. Then, a distribution diagram was drawn to present different types of convection–condensation heat transfer curves under various working parameters. Sootblowing operation strategies were proposed under different working conditions to provide reference for the actual operation of the waste heat recovery heat exchanger for dryer exhaust.     

氯化锰/氨热化学吸附储热的特性

热化学吸附储热具有储热损失小、储热密度高、可实现冷热复合储存等优点，近年来得到了广泛的关注。本文以MnCl₂/NH₃作为吸附储热工质对，基于热化学吸附技术构建了热化学吸附储热实验平台，对MnCl₂/NH₃热化学吸附系统的储热性能进行了理论分析和实验研究。结果表明：在解吸充热温度、吸附放热温度、冷凝/蒸发温度分别为162℃、45℃和25℃的运行条件下，试验获得的吸附储热密度最大，其值为1296.36kJ/kg MnCl₂或1101.90kJ/kg固化复合吸附剂。当放热温度从45℃增大到85℃时，热化学吸附储热系统的吸附储热效率从38.98%降低至24.08%。由于传热传质、化学反应动力学等因素的影响，相同运行工况下吸附储热系统实际所获得的储热性能要低于理论值。     

一种新型天然气锅炉烟气余热回收系统

引言随着城市生活水平的提高,空气质量逐渐成为人们关注热点,清洁能源得到越来越广泛的应用。天然气的大量开采,使得天然气锅炉凭借其节能环保的优势在城市供暖中逐渐占据主导地位。然而,天然气锅炉同样存在排烟温度高引起的一次能源浪费问题。目前大多数热水锅炉的排烟温度为140~200℃,一些蒸汽锅炉则高达250℃。同时,由于