Study on Curing Effect and the Waste Heat Recovering Equipment Design of Flue Gas of Bulk Curing Barn

In order to realize tobacco curing with energy saving and emission reduc- ing and lower cost, the waste heat recovering equipment was designed and built on blowing-upward type bulk curing barn. The comparative experiment of tobacco leaf curing was conducted between a bulk curing barn with waste heat of flue gas and conventional bulk curing barn. The results showed that the effect of saving coal in bulk curing barn with waste heat of flue gas was obvious than the contrast. The coal consumption quantity was 1.531 kg per kg of dry tobacco leaf. The saving coal in bulk curing barn with use waste heat of flue gas was 0.181 kg per kg of dry tobacco leaf than the contrast and saving coal rate was 10.57%. The electricity consumption quantity was 0.593 kWh per kg of dry tobacco leaf. The saving elec- tricity quantity in bulk curing barn with use waste heat of flue gas was 0.022 kWh/kg and the saving electricity rate was 3.58% than the contrast. The saving curing cost was 0.158 yuan per kg of dry tobacco leaf and saving cost rate 9.09% in bulk cur- ing barn with use waste heat of flue gas than the contrast. The appearance quality, grade structure and primary chemical composition had no significant difference be- tween bulk curing barn with use waste heat of flue gas and the contrast.

Comprehensive Energy-Saving Technology for RTO Flue Gas Waste Heat Utilization

In the automobile painting workshop,the oven will discharge harmful exhaust gas,the exhaust gas can be reused through the TNV system,the natural gas can meet the emission standard to the atmosphere after burning,and the high temperature gas discharged TNV the system can carry considerable heat.Utilization can effectively improve the economic benefits of the factory.At present,the more mature scheme is to heat the high temperature exhaust gas through the heat exchanger,which can reduce the steam consumption of the factory.Based on the analysis of the comprehensive energy saving content of waste heat utilization of RTO flue gas,this paper hopes to provide some reference and reference for readers.

A Compound Cycle for Power Generation by Utilizing Residual Heat of Flue Gas in Electric Steelmaking Process

Electric furnace short process steelmaking is one of the most important steelmaking methods in the world today, and the waste heat recovery potential of electric furnace flue gas is huge.?The research on the recovery of electric furnace flue gas waste heat is of great significance. In order to make better use of this part of the heat,?in this paper, a compound cycle of nitrogen Brayton cycle as a first-order cycle and toluene transcritical Rankine cycle as a second-order cycle is proposed to recover waste heat from furnace flue gas in steelmaking process for power generation. A mathematical model was established with the net output power as the objective function and the initial expansion pressure, the final expansion pressure, the initial expansion temperature and the initial pressure of the second cycle as the independent variables. The effect of multivariate on the net output power of the waste heat power generation cycle is studied, and then, the optimal parameters of the compound cycle are determined. The results show that under the general electric furnace steelmaking process, the power generation efficiency of this new cycle can be increased by 21.02% compared with the conventional cycle.

Technical Measures and Selections for Reducing Flue Gas Heat Loss of Large Coal-Fired Boilers

The main technologies for reducing flue gas heat loss of pulverized coal-fired boilers are introduced, and the suitability of these technologies for boiler operation and the principles for selection of these technologies are explored. The main conclusions are： 1） the non-equilibrium control over flue gas flow rates at the inlet of the air heater and the reversal rotation of the air heater rotator should be popularized as regular technologies in large boilers; 2） increasing the area of the air heater to reduce the flue gas heat loss in pulverized coal-fired boilers should be the top option and increasing the area of the economizer be the next choice; 3） low- pressure economizer technology could save energy under special conditions and should be compared with the technology of increasing economizer area in terms of technical economics when the latter is feasible; 4） the hot primary air heater is only suitable to the pnlvefizing system with a large amount of cold air mixed.

Preparation of gangue ceramsite by sintering pot test and potential analysis of waste heat recovery from flue gas

Preparation of ceramsite from solid waste based on the sintering process is a new technology and had a high efficiency in improving producing capability, decreasing consumption of liquefied petroleum gas (LPG), and recovering waste heat of flue gas. An experiment sintering gangue ceramsite was conducted in a 25 kg scale sintering pot with a 100 cm height. The combustion characteristics, phase transformation, and the release profile of SO_(2)^(*) (SO and/or SO_(2)) and NO_(x)^(*) (N_(2)O, NO, and/or NO_(2)) of gangue ceramsite during the sintering process were studied by X-ray diffraction analysis, X-ray fluorescence spectrometry, thermogravimetry–differential thermogravimetry–differential scanning calorimetry, and measurement of physical properties of ceramsite and gas components of flue gas. The results showed that the gangue ceramsite had excellent properties, and its compressive strength and water absorption were 8.2–9.6 MPa and 8.9%–9.8%, respectively, far exceeding the requirement of standard (GB/T 17431.1–2010). The ignition temperature of gangue ceramsite was 443 ℃, and the ignition loss was 14.60 mass% at 1000 ℃. Kaolinite and calcite disappeared at 600 and 800 ℃, respectively. Albite disappeared and mullite formed at 1000 ℃. Two peaks of SO_(2)^(*) emissions emerged in the range of 311–346 mg m^(-3) near 500 ℃ of upper layer ceramsite and 420–489 mg m^(-3) near 1000 ℃ of lower layer ceramsite, respectively. NO_(x)^(*) emissions peak emerged in the range of 227–258 mg m^(-3) near 550 ℃ of the upper layer ceramsite, which was related to the oxidation of sulfide and the combustion of LPG. Gangue is a direct heat source for sintering of ceramsite as well. During sintering process, the heat of flue gas above and below 400 ℃ accounts for 55.9% and 30.0% of the all-output heat, respectively, and was potentially used for producing waste-heat steam or electricity as by-products and drying raw materials during its own initial sintering process, which can realize combined mass and heat utilization for the gangue and further reduce the cost of sintered gangue ceramsite.

Waste heat recovery from heavy-duty diesel engine exhaust gases by medium temperature ORC system

A medium-temperature waste-heat recovery system based on the organic Rankine cycle (ORC) is designed to recover the exhaust energy from a heavy-duty diesel engine. Analysis of the 1st law of thermodynamics for an ORC system is performed. This analysis contains two parts. The first part is an analysis with undefined heat exchangers to gain an understanding of the ORC and find out suitable organic fluid parameters for a better ORC efficiency. The second part of the analysis uses combined engine test results and two designs of heat exchangers. By comparing the two designs, an improved system of heat exchangers is described. This analysis also quantifies the effect of engine parameters on ORC system. The study concludes that the supercritical Rankine cycle is a better approach towards waste heat recovery. The ORC system is found to perform better under part-load conditions if the medium-high power condition rather than rated working point of the engine is used as the design parameter. The ORC system achieves the highest waste-heat recovery efficiency of up to 10-15% for the optimised heat ex-changer design.

湿法脱硫后烟气和浆液余热回收技术研究进展

低品位余热高效深度利用是促进燃煤电站进一步节能减排的关键之一,湿法脱硫后的低温饱和湿烟气蕴含大量潜热和水资源,大量脱硫浆液吸收烟气热量后温度升高。烟气与浆液具有巨大的余热利用和水资源回收的潜力,若直接排放烟气,直接排出浆液,不但造成资源浪费,还容易引发“白色烟羽”污染环境。本文以湿法脱硫后饱和湿烟气和脱硫浆液为研究对象,针对目前湿法脱硫技术余热回收效率低、利用难以匹配冷源等困境,总结了国内外针对脱硫后烟气水热回收和浆液余热回收技术及发展方向,研究中针对浆液余热利用仍待发展。其中,直接冷凝烟气和浆液技术和热泵技术成熟,应用广泛;溶液吸收技术能源利用率高,烟气腐蚀性低;烟气膜分离技术、浆液闪蒸、热泵技术清洁环保,回收质量高。直接冷凝烟气、浆液技术和膜分离技术需要进一步提高抗腐蚀性和转换效率;浆液闪蒸、热泵技术能耗较高,吸收式热泵技术仍需寻找高效安全环保无毒的吸收溶液。最后,探讨了目前脱硫浆液余热利用的主要方式及存在问题,回收余热主要用于供暖和电厂内部热利用,以期进一步推动湿法脱硫后烟气与浆液余热回收利用,实现燃煤电站的深度节能减排。

潜热储能系统热力特性研究及应用分析

研究搭建了一小试规模的潜热储能系统,能对200~300℃的热量进行存储、释放,通过不同方式表征所使用相变材料的物理性质,研究其与应用场景的匹配性,同时分析所设计系统循环过程中的参数变化,研究系统热力特性。试验结果表明:所用二元硝酸盐能够稳定的储存温度200~290℃的余热,所使用的带螺旋型翅片换热管的潜热储能系统具有较高的热效率,试验台储热耗时51.75 min,完成47.809 MJ的能量储存,放热耗时43.5 min,释放出46.209 MJ能量,系统的储热效率为79.16%,放热效率为79.15%。在系统的循环过程中,系统累计输入能量60.398 MJ,输出能量36.578 MJ,循环效率为60.56%。

氢氧化铝焙烧炉低温烟气余热发电系统

本文简要介绍了氢氧化铝焙烧生产氧化铝过程中所产生低温烟气的一种余热利用系统-低温烟气余热发电系统,该系统利用有机朗肯循环原理,将烟气中的部分热能转化为电能,单台4 000 t/d焙烧炉的低温烟气每小时发电功率约为741.7 kW,并分析了该余热利用系统的经济价值及社会意义,为行业从业者确定经济可行的氢氧化铝焙烧炉余热利用方案提供参考。

净烟道余热回收换热管腐蚀特性研究

烟道余热回收换热管在酸气作用下易腐蚀渗漏,研究其腐蚀规律对制定防腐策略有重要意义。通过挂片腐蚀试验装置,分析了烟气相对湿度、烟气温度、二氧化硫含量、积灰量、氧气含量对换热管腐蚀速率的影响规律。结果表明:随着烟气湿度的增加,换热管腐蚀速率先快速升高后趋于平缓,降低烟气相对湿度可抑制换热管腐蚀;烟气温度控制在50℃以下或80℃~100℃时换热管腐蚀程度较低,70℃为换热管腐蚀最严重的工况;脱硫效率影响换热管的腐蚀状态,降低烟气二氧化硫含量可有效抑制腐蚀;随积灰量的增加,换热管腐蚀速率先升高后降低,提高烟气流速、定期清理净烟道积灰均可有效抑制积灰腐蚀;随氧气含量升高,换热管腐蚀速率先升高后降低,氧气体积分数为8%时,氧化膜抑制作用最强。

高水分褐煤发电技术在我国的发展现状与分析

介绍我国褐煤资源特点和褐煤发电技术的发展现状,并分析褐煤锅炉、中速磨制粉系统及设备选型优化、烟气余热利用、烟气提水等褐煤发电关键技术。经分析可知,我国褐煤发电机组在机组参数、能耗水平、环保等方面处于世界领先水平,下一阶段应向着更加高效、绿色的方向发展。

Waste heat recovery and denitrification of flue gases from gas-fired boilers

A waste heat recovery and denitrification system was developed for improving energy conservation and emissions control especially for control of PM2.5 particles and haze. The system uses enhanced heat and mass transfer techniques in a packed heat exchange tower with self-rotation and zero-pressure spraying, low temperature NO oxidation by ozone, and neutralization with an alkali solution. Operating data in a test project gave NOx in the exhaust flue gas of less than 30 mg/Nm3 with an ozone addition rate of 8 kg/h and spray water p H of 7.5–8, an average heat recovery of 3 MW, and an average heat supply of 7.2 MW.

Oxidation Behaviors of Different Grades of Ferritic Heat Resistant Steels in High-Temperature Steam and Flue Gas Environments

For steam tubes used in thermal power plant,the inner and outer walls were operated in high-temperature steam and flue gas environments respectively.In this study,structure,microstructure and chemical composition of oxide films on inner and outer walls of exservice low Cr ferritic steel G102 tube and exservice high Cr ferritic steel T91 tube were analyzed.The oxide film was composed of outer oxide layer,inner oxide layer and internal oxidation zone.The outer oxide layer on the original surface of tube had a porous structure containing Fe oxides formed by diffusion and oxidation of Fe.More specially,the outer oxide layer formed in flue gas environment would mix with coal combustion products during the growth process.The inner oxide layer below the original surface of tube was made of Fe–Cr spinel.The internal oxidation zone was believed to be the precursor stage of inner oxide layer.The formation of internal oxidation zone was due to O diffusing along grain boundaries to form oxide.There were Fe–Cr–Si oxides discontinuously distributed along grain boundaries in the internal oxidation zone of G102,while there were Fe–Cr oxides continuously distributed along grain boundaries in that of T91.

Study on Calculation Method for Partition of Heat Transfer in an Ultra-supercritical Boiler

Use a 1000MW ultra-supercritical tower boiler as the research object. On the basis of one dimensional model, simplify the tube heat transfer model and the radiation heat transfer model;establish the two-dimensional area calculation model with the regional method;?summarize the heat load distribution of flue gas temperature and water wall surface;and compare with the measured data. The error range of the result is acceptable on the project. The distribution of water wall surface heat load along the furnace width and the area where heat transfer deterioration?cause easily along the furnace height direction are studied with the model and algorithm on different boiler load conditions. All these provide the reference for the design and operation of the ultra supercritical boiler.

330 MW机组变负荷下低温余热闪蒸脱硫废水特性

高含盐脱硫废水零排放已成为目前电厂亟待解决的瓶颈问题,利用机组低温余热对高盐废水进行闪蒸-浓缩-结晶-固化是实现脱硫废水零排放的关键技术之一。针对当前风、光等可再生能源并网后,机组变负荷运行引起脱硫废水的水质条件、处理量、热源不稳定造成脱硫废水低温余热闪蒸浓缩效率低、易结垢等问题,研究了电厂60%~100%变负荷过程中,低温负压蒸汽流量、废水处理量、浓液比、废水回收率等因素对三效蒸发器处理脱硫废水的影响规律。通过数据分析可知,应在三效蒸发系统前设置缓冲罐,避免流量过大导致系统损坏,且在系统进水量不大于200 t/d时,废水回收率可达80%~90%;低温负压蒸汽流量在700~1 000 kg/h,故应在首段冷凝水箱处安装流量计,根据系统进水量调节低温负压蒸汽产量,避免低温负压蒸汽产量过大导致热源浪费;严格按照三效蒸发系统在出料口处密度计指示,在浓缩液密度达1.35 g/mL时,即时排出浓缩液;通过对三效蒸发系统稳定运行时产生的冷凝水进行分析,氯离子质量浓度达到1.56 mg/L,可作为电厂的循环补给水,且该系统每天的电力消耗为4 000 kWh,在不考虑人员成本、折旧费、维修费等费用,三效蒸发系统每处理1 m^(3)废水的费用为5~10元。

低温烟气余热回收核心设备应用分析

综合分析了烟气换热器和溴化锂吸收式热泵在低温烟气余热回收中的特点和适用性。在烟气换热器选择方面,间接接触式换热器相较于直接接触式换热器体积更小、阻力更低、占地更少、系统更简单,但低温水温度要求更低。在溴化锂吸收式热泵选择方面,重点分析了单效溴化锂吸收式热泵和双效溴化锂吸收式热泵的供热特性及与不同换热器的匹配使用情况。实际应用表明:双效热泵供热温度低、效率高,适合与直接接触式换热器匹配;而单效热泵适用性更强,应用更广泛,2种换热器都可匹配。

低温烟气余热驱动ORC发电系统经济性分析

考虑到低温烟气余热利用中烟气腐蚀对经济性的影响,本文以国内某建筑陶瓷生产企业为对象,建立烟气余热驱动ORC发电系统,分析排烟温度、电价和停产时间对系统经济性的影响。结果表明,设备费用在全生命周期成本中占比超过37%,随着排烟温度下降,设备和维护费用迅速增加;排烟温度为110℃时,发电功率达到最大值1107.33 kW,但经济性最差;排烟温度为130℃时,获得最大净现值669.6万元;排烟温度为150℃时,获得最小回收期8.3年;可接受的最低电价为0.45元/(kWh),可根据电价设计排烟温度;停产时间是影响装机容量的关键因素。

固废循环流化床焚烧炉外置换热器运行特性研究

对主要燃料为造纸废渣的固废循环流化床焚烧炉外置换热器的运行特性进行了研究,分析了外置换热器中的温度、压力特征,获得了不同负荷下外置换热器中高温过热器和中温过热器的传热系数,可为固废焚烧炉外置换热器的设计及优化提供参考。

垃圾焚烧余热锅炉投运初期过热器吸热量特性研究

机械炉排垃圾焚烧余热锅炉投运初期(6个月内)主汽温度变化幅度较大,故从两方面对此问题进行了分析:通过与燃煤锅炉进行对比发现余热锅炉的过热器整体传热温压较小;通过余热锅炉投运5 d与投运6个月的热力计算数据对比,发现过热器传热温压变化是过热器吸热量变化的主要影响因素。分析得出,垃圾焚烧余热锅炉过热器入口烟温变化幅度大是过热器吸热量变化幅度大的主要影响因素。运行数据显示,投运初期过热器入口烟温提高100℃以上,过热器整体吸热量增加60%以上,主汽温度提高65℃以上。最后,对减小过热器入口烟温的变化幅度及保障过热器安全运行提出可行性建议。

480m^(2)烧结系统提高余热发电量探索与实践

莱钢炼铁厂通过分析480m^(2)烧结系统流程可控因子,治理余热系统汽、水、油设备跑冒滴漏,完善余热发电系统控制程序,制定余热发电系统操作法,统一4个班操作,提升了烧结矿吨矿发电稳定性。通过试验分析、探测关键因子烟气温度、循环水温度最佳控制水平,优化控制区间,将烧结矿余热发电量西格玛水平提升至1.47,吨矿发电量提高到24(kW·h)/t以上。