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.

Technical and Economic Aspects and Experience from 6 Years of Operating the Technology Using the Waste Heat from the Exhaust Gases of Heat Sources and 3 Years of Operating a Heating Plant in an Autonomous, Island Regime

This article is focused on technical and economic evaluation of more than 6-years experiences of operating the Waste Heat Recovery technology—the manner and system of flue gas processing generated in the combustion process in heat & power plants, cogeneration units, etc., which burn the gaseous fuel, primarily natural gas, or methane, biogas, geothermal gas, or other gaseous mixtures containing hydrogen. The solution proposes a more effective and non-traditional use of gaseous fuel for heating, the flue gases of which are processed in order to extract additional utilisable heat, with potential elimination of CO2 from them. Deploying of the heating plant in an island regime (OFF-GRID) enables definition of the benefits brought by the 3 years of operational experience and presents visions for the future offering the possibility to utilise the support energy services at the municipal as well as regional level.

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.

Characteristics of gaseous product from municipal solid waste gasification with hot blast furnace slag

Possibility of combustible gas production from municipal solid waste （MSW） using hot blast furnace （BF） slag has been studied.The objective of this work is to generate combustible gas from MSW using heated BF slag.In this experiment,the thermal stability of the MSW was analyzed by thermogravimetric analysis,and effects of temperature,gasifying agent （air,N2,steam） and BF slag on the gas products were investigated at 600？900 ？C.The thermogravimetric analysis indicates that the weight loss of MSW includes four stages：evaporation of the moisture,combustion of volatile materials,burning of carbon residue and burnout of ash.The contents of the combustible gas increase with increasing temperature,and the lower calorific value （LCV） increases rapidly at 600？900 ？C.It is found that volume fraction of CO,H2 and CH4 at different atmospheres increases in the order N2〈air〈steam.It is believed that BF slag acts as the catalyst and the heat carrier,which promotes the gasification reactivity of MSW.

Experiment Study on the Exhaust-Gas Heat Exchanger for Small and Medium-Sized Marine Diesel Engine

This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.

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.

Experimental Investigation on Solution Regeneration Performance and Coefficients in Full-Open System for Heat and Water Recovery of Flue Gas

The recovery of heat and water from low-grade flue gas is of considerable importance for energy conservation and environmental preservation.While the full-open absorption heat pump shows promise as a means of achieving heat and water recovery,the lack of research on heat and mass transfer performance of open-type solution evaporation regeneration represents a significant impediment to its design and operation.This paper experimentally investigates the regeneration performance of an open-type spaying tower equipped with ceramic structured packings.Two different regeneration modes are proposed,namely ambient air receiver mode and flue gas receiver mode,to utilize air or low-grade flue gas as a driving source.The impact of different input parameters on the regeneration characteristics,including heat transfer capacity,water removal rate,thermal efficiency,and humidity effectiveness,are demonstrated.The findings indicate that the enhancement of regeneration can be achieved through the increase of solution flow rate,solution temperature,and flue gas flow rate in both regeneration modes.However,high solution concentration and flue gas humidity ratio can weaken water removal rates and reduce thermal efficiency.For the regeneration of CaCl_(2)-H_(2)O with a concentration of55%,flue gas around 200℃with a humidity ratio below 44 g/kg can successfully drive the solution regeneration process.When the solution concentration or flue gas humidity ratio continues to rise,additional energy is necessary for regeneration.Furthermore,the coupled heat and mass transfer coefficients are fitted,which can contribute to the design and optimization of the open-type regenerator.

Heat Transfer and Energy Utilization of Waste Heat Recovery Device with Different Internal Component

Steel industry is high energy-consuming industry, and its waste?heat recovery is critically?important for energy utilization. In this study, pipeline bundle is used to enhance heat transfer in?waste?heat recovery device,?and?associated gas-solid heat transfer and energy utilization performance with different pipeline arrangement, pipe diameter and shape of internal component are further analyzed. The temperatures of gas and particle in device with pipeline bundle periodically fluctuate in horizontal direction, and those in staggered system distribute more uniformly than those in paralleled system. Compared with paralleled device, exergy and waste heat utilization efficiency of staggered device have been improved, and they are both higher than?those without pipeline. As pipe diameter increases, exergy and waste heat utilization efficiency first increases and then decreases, and they reach the maxima with optimal pipe diameter.?As the width of internal component keeps constant, influence of its shape on heat transfer is very little.

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 pulverizing system with a large amount of cold air mixed.

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.

Transforming Waste Heat into“Renewable Heat”

Introduction:The current worldwide electric power&heat&cool production has a negative impact on the environment by emissions and enormous leaks of low-potential waste heat.Transformation of unused industrial low power heat into“renewable heat”useful to enhance the efficiency of the system is essential and actual innovation in the field of worldwide environmental protection.By introducing and defining the terminology of low-potential,“renewable”,“green heat”has created a new,parallel category of research in the energy sector.Traditional co-generation systems produce heat for space heating and hot water and generate electricity.Moving to tri-generation allows growing demand for air conditioning for homes,offices and commercial spaces such as server rooms and switchboards to be met simultaneously or on a seasonal basis.Tri-generation,or combined cooling,heat and power,is the process by which some of the heat produced by a co-generation plant is used to generate chilled water for air conditioning or refrigeration.Usually an absorption chiller is linked to the plant to provide this functionality.The technical solution is related to the new efficient manner and system of simultaneous generation of heat/cold from multiple heat sources,which has not yet been known,but in practice required.New system also enables advantageous utilization of solar power in supporting of the cooling output.The innovative system can be operated also within the existing central heating distribution systems.

一种智控型烟气余热深度回收装置的实践探索

为了解决大庆油田加热炉排烟温度高、生产能耗大的问题,在加热炉排烟系统增设智控型烟气余热深度回收装置,以加热炉进液为冷源,将排烟温度冷却至50℃以下,综合回收烟气的显热和潜热,达到深度回收烟气余热的目的,并对烟气降温过程中产生的冷凝水进行全部回收,从根本上解决了冷凝水排放问题。应用装置前后系统整体热效率分别为79.94%和87.47%,综合计算得到装置的节能率为8.35%,节能效果显著;此外,对于1.0 MW加热炉,年平均负荷率50%,年运行时间330 h,测算得到每年节约天然气4.58×10^(4) m^(3),折合7.4万元,具有良好的经济效益。

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。

耦合余热回收下电站锅炉尾部烟气热能高效梯级利用系统设计

针对电站锅炉尾部烟气热能利用效率较低,梯级利用数值模拟过程与全尺度数据分析过程偏差较大的问题,设计了一种耦合余热回收下的电站锅炉尾部烟气热能高效梯级利用系统。实验结果表明,系统的最佳烟气热能高效梯级节点利用情况和热能梯级置换情况整体都保持在60%以上,采用热能阶梯式温差电站后,系统整体效率提高了约22%,证明了所设计系统的使用优越性。

燃气电厂烟气余热回收吸收塔设计优化与实验研究

为减少碳排放、有效提高能源利用效率,对某燃气热电厂烟气系统进行了余热回收改进设计。采用填料喷淋技术对原有的余热喷淋塔进行结构优化设计,将吸收换热塔优化为填料塔,有效强化换热性能。结果表明,优化后烟气余热回收吸收塔不仅消除了原系统水泵气蚀、振动和噪声的问题,还解决了换热塔“失水”的问题。在输入燃气量不变、输出电力不变的前提下,输出热量有效提高10%以上,脱硝效率稳定达到70%以上,NO_(x)最低浓度可稳定维持<10 mg/m^(3)。与常规供热方案相比,本余热回收方案年回收烟气热量2.789万GJ,并带来了可观的经济与环境效益,每个采暖季减少天然气使用量约86.70万标方,减少CO_(2)排量约1610 t/年。

工业锅炉燃烧烟气余热回收技术研究

工业锅炉是大型工业生产中常见的能源消耗设备,每年耗用原煤约占年总产量的1/3,排放大量的二氧化碳、二氧化硫等,不仅造成环境污染而且其燃烧过程中产生的烟气含有丰富的热能,然而传统的锅炉系统中这部分烟气余热往往被直接排放到大气中,造成了能源的浪费和环境污染。随着能源和环境问题的日益突出,工业锅炉燃烟气余热回收问题受到广泛的关注。科学技术的发展为工业锅炉燃烧烟气余热回收提供了可能性。在分析现阶段工业锅炉燃烧烟气利用现状的基础上,介绍工业锅炉燃烧烟气的特性以及能量分布,探讨较为常见的工业锅炉燃烧烟气余热回收技术,并分析其经济以及环境效益,提高能源利用效率、减少排放、降低能源成本,推动可持续发展和绿色生产。

清洁环保型熔盐炉及烟气余热回收节能装置研究

分析了燃天然气立式圆筒型熔盐炉的结构型式,研究了燃生物质柴油立式圆筒型熔盐炉的构造(组成),讨论了燃生物质固硫型煤熔盐炉的机械化燃烧装置与立式圆形盘管式炉体结构特点,探讨了熔盐炉烟气余热回收利用节能装置的常用结构型式:对流型换热器、辐射型换热器、热管式换热器、余热锅炉。

火力发电厂燃煤发电机组烟气余热回收利用技术研究

传统烟气余热回收技术水平较低,换热效率不高,能级匹配也不够合理,导致回收热量低,为此本文进行火力发电厂燃煤发电机组烟气余热回收利用技术研究。首先对烟气余热资源特性参数进行测定,以了解其特性和潜力。其次,确定余热资源的能级,选择合适的回收技术和设备。接下来,安装烟气余热回收装置。最后,通过烟气余热转换热量利用,将烟气中的余热转换为其他形式的能量。实验结果表明:利用火力发电厂燃煤发电机组烟气余热回收利用技术回收热量回收利用热量为19MW,应用价值较高。

An Experimental Study on Latent Heat Recovery of Exhaust Wet Flue Gas

The experiment was conducted to investigate the heat transfer performance of wet flue gas in a vertical tube. The factors influencing the convective condensation of wet flue gas were experimentally investigated. The measured results indicate that the convective heat transfer of bulk flow and condensation heat transfer of vapor have significant contribution to the total heat transfer and the dominant transport mechanism is dependent upon the vapor fraction in mixture.

喷淋式烟气源热泵冷凝余热回收系统性能分析

受限于锅炉房的建造环境,采用喷淋塔回收烟气余热时,热网回水往往是唯一的冷源选择。但回水温度过高时无法回收烟气潜热,造成大量浪费。为实现高效的全热回收,本文提出了一种直接接触式换热器与压缩式热泵耦合的烟气冷凝余热回收系统,旨在通过热泵对低品位热能的提取能力制造人工冷源以满足回收烟气潜热的温度需求。实验研究了系统在变热泵冷凝端进口水流量、温度工况下的余热回收能力和供热能力。结果表明,以输入燃气的最低热值为基准,系统在全工况下的供热效率均超过100%,具备优秀的供热能力。在热泵冷凝端进口水温50℃、流量40L/min的工况下,系统的排烟温度可降至26.9℃,余热回收效率可达13.85%。此外烟气中的水蒸气冷凝量为6.5~7kg/h,证明系统可以在实现高效余热回收的同时具有优秀的余水回收能力。实测每年可节省约1966.42m3燃气,投资回收期约为3.33年,具备优秀的节能与经济效益。