Performance of Gas-Steam Combined Cycle Cogeneration Units Influenced by Heating Network Terminal Steam Parameters

The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and power system multidimensionally based on the operating characteristics of the cogeneration units,the hydraulic and thermodynamic characteristics of the heating network,and the energy loads.Taking a steam network supported by a gas-steam combined cycle cogeneration system as the research case,the interaction effect among the source-side prime movers,the heating networks,and the terminal demand thermal parameters were investigated based on the designed values,the plant testing data,and the validated simulation.The operating maps of the gas-steam combined cycle cogeneration units were obtained using THERMOFLEX,and the minimum source-side steam parameters of the steam network were solved using an inverse solution procedure based on the hydro-thermodynamic coupling model.The cogeneration operating maps indicate that the available operating domain considerably narrows with the rise of the extraction steam pressure and flow rate.The heating network inverse solution demonstrates that the source-side steam pressure and temperature can be optimized from the originally designed 1.11 MPa and 238.8°C to 1.074 MPa and 191.15°C,respectively.Under the operating strategy with the minimum source-side heating parameters,the power peak regulation depth remarkably increases to 18.30%whereas the comprehensive thermal efficiency decreases.The operation under the minimum source-side heating steam parameters can be superior to the originally designed one in the economy at a higher price of the heating steam.At a fuel price of$0.38/kg and the power to fuel price of 0.18 kg/(kW·h),the critical price ratio of heating steam to fuel is 119.1 kg/t.The influence of the power-fuel price ratio on the economic deviation appears relatively weak.

Study of steam heat transfer enhanced by CO_(2) and chemical agents: In heavy oil production

Steam flooding with the assistance of carbon dioxide (CO_(2)) and chemicals is an effective approach for enhancing super heavy oil recovery. However, the promotion and application of CO_(2) and chemical agent-assisted steam flooding technology have been restricted by the current lack of research on the synergistic effect of CO_(2) and chemical agents on enhanced steam flooding heat transfer. The novel experiments on CO_(2)–chemicals cooperate affected steam condensation and seepage were conducted by adding CO_(2) and two chemicals (sodium dodecyl sulfate (SDS) and the betaine temperature-salt resistant foaming agent ZK-05200).According to the experimental findings, a “film” formed on the heat-transfer medium surface following the co-injection of CO_(2) and the chemical to impede the steam heat transfer, reducing the heat transfer efficiency of steam, heat flux and condensation heat transfer coefficient. The steam seepage experiment revealed that the temperature at the back end of the sandpack model was dramatically raised by 3.5–12.8 °C by adding CO_(2) and chemical agents, achieving the goal of driving deep-formation heavy oil. The combined effect of CO_(2) and SDS was the most effective for improving steam heat transfer, the steam heat loss was reduced by 6.2%, the steam condensation cycle was prolonged by 1.3 times, the condensation heat transfer coefficient was decreased by 15.5%, and the heavy oil recovery was enhanced by 9.82%. Theoretical recommendations are offered in this study for improving the CO_(2)–chemical-assisted steam flooding technique.

Regeneration of waste activated carbon after extracting gold with steam under microwave heating:Optimization using response surface methodology

The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology （RSM） technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 ℃, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m2/g, with total pore volume of 1.242 cm3/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores.

Thermodynamic Analysis of a Condensate Heating System from a Marine Steam Propulsion Plant with Steam Reheating

The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy analysis of any condensate heating system should be avoided because it is highly influenced by the measuring equipment accuracy and precision.All the components from the observed marine condensate heating system have energy destructions lower than 3 kW,while the energy efficiencies of this system are higher than 99%.The exergy efficiency of closed condensate heaters continuously increases from the lowest to the highest steam pressures(from 70.10%to 92.29%).The ambient temperature variation between 5℃and 45℃notably influences the exergy efficiency change of both low pressure heaters and the low pressure segment equal to 31.61%,12.37%,and 18.35%,respectively.

Research of Influence of Steam Contact Heating on Thermal Stability of a Wall of Glass Canning Jar

One of ways of intensification of process of manufacture of heterogeneous tinned products of fruits and vegetables is the use of sated water steam （Patent of USSR No. 500792）. This process at application as consumer glass container for such products is especially effective. However, there are some questions which are connected with thermal influence on glass container at realization of such heating. The given research is devoted as the decision of practical questions arising at process engineers.

The Calculation of Heating Radius and Determination of Parameters in Heavy Oil Steam Stimulation

在稠油吞吐过程中,加热半径是热采中的重要指标,对注汽参数和生产制度起到了指导性作用。运用能量守恒原理,从热量注入方面考虑了蒸汽相变释放的气化潜热,从热量损失方面考虑井筒热量损失和顶底盖层热量损失,最终得到了新的加热半径计算公式。计算结果表明,加热半径受注汽参数、焖井时间、储层参数等因素影响,并系统阐述了岩层各物性参数的计算及选择方法。最后通过实例验证了该方法的计算值和试井解释出的值较为相符,为现场实际应用提供了可靠的方法。

Effects of Steam Heat Treatment on the Surface Contact Angle of Chinese Fir

The aim of this study was investigate the effects of heat treatment on the contact angle of Chinese fir, and the indicators affecting the change of contact an-gle change. It was determined that the duration of treatment had significant effect on the change curves of contact angle of Chinese fir wood due to the change curves of contact angle became more centralized and orderly after the specimens heat treated at 180 ℃. Compared with the untreated wood, the contact angle in-creased from 51＆#176; to 124＆#176; after 4 h treatment, and hydroxyl absorbance of hy-drophilic functional groups decreased from 2.08 to 1.63, while carbonyl absorbance from 0.92 to 0.62. The surface roughness has not significant influence on the con-tact angle. Heat treatment of the Chinese fir caused surface morphological change, which produced hol owed-out phenomenon. The increased surface contact angle caused by heat treatment can be used for outdoor and sauna facilities.

Transient Heat Transfer Study of Direct Contact Condensation of Steam in Spray Cooling Water

We conducted a transient experimental investigation of steam–water direct contact condensation in the absence of noncondensible gas in a laboratory-scale column with the inner diameter of 325 mm and the height of 1045 mm. We applied a new analysis method for the steam state equation to analyze the molar quantity change in steam over the course of the experiment and determined the transient steam variation. We also investigated the influence of flow rates and temperatures ofcooling water on the efficiency ofsteam condensation. Our experimental results show that appropriate increasing of the cooling water flow rate can significantly accelerate the steam condensation. We achieved a rapid increase in the total volumetric heat transfer coefficient by increasing the flow rate of cooling water, which indicated a higher thermal convection between the steam and the cooling water with higher flow rates. We found that the temperature ofcooling water did not play an important role on steam condensation. This method was confirmed to be effective for rapid recovering ofsteam.

Numerical analysis of heat transfer enhancement on steam condensation in the presence of air outside the tube

In loss-of-coolant accidents,a passive containment heat removal system protects the integrity of the containment by condensing steam.As a large amount of air exists in the containment,the steam condensation heat transfer can be significantly reduced.Based on previous research,traditional methods for enhancing pure steam condensation may not be applicable to steam–air condensation.In the present study,new methods of enhancing condensation heat transfer were adopted and several potentially enhanced heat transfer tubes,including corrugated tubes,spiral fin tubes,and ring fin tubes were designed.STAR-CCM+was used to determine the effect of enhanced heat transfer tubes on the steam condensation heat transfer.According to the calculations,the gas pressure ranged from 0.2 to 1.6 MPa,and air mass fraction ranged from 0.1 to 0.9.The effective perturbation of the high-concentration air layer was identified as the key factor for enhancing steam–air condensation heat transfer.Further,the designed corrugated tube performed well at atmospheric pressure,with a maximum enhancement of 27.4%,and performed poorly at high pressures.In the design of spiral fin tubes,special attention should be paid to the locations that may accumulate high-concentration air.Nonetheless,the ring-fin tubes generally displayed good performance under all conditions of interest,with a maximum enhancement of 24.2%.

External Heat Transfer in Moist Air and Superheated Steam for Softwood Drying

In kiln drying of softwood timber, external heat and moisture mass transfercoefficients are important in defining boundary temperature and moisture content at the woodsurface. In addition, superheated steam drying of wood is a promising technology but this has notbeen widely accepted commercially, partially due to the lack of understanding of the dryingphenomena occurred during drying. In this work, experimental investigation was performed to quantifythe heat transfer between wood surface and surrounding moist air or superheated steam. In theexperiment, saturated radiata pine sapwood samples were dried using dry-bulb/wet-bulb temperaturesof 60℃/50℃, 90℃/60℃, 120℃/70℃, 140℃/90℃, 160℃/90℃, 140℃/100℃ and 160℃/100℃. The lasttwo schedules were for superheated steam drying as the wet-bulb temperature was set at 100℃. Thecirculation velocity over the board surface was controlled at 4.2m·s^(-1). Two additional runs(90℃/60℃) using air velocities of 2.4 m·s^(-1) and 4.8 m·s^(-1) were performed to check theeffect of the circulation velocity. During drying, sample weight and temperatures at wood surfaceand different depths were continuously measured. Prom these measurements, changes in woodtemperature and moisture content were calculated and external heat-transfer coefficient wasdetermined for both the moist air and the superheated steam drying.

Performance Optimization of Dual Pressure Heat Recovery Steam Generator (HRSG) in the Tropical Rainforest

This work evaluates the performance optimization of heat recovery steam generator system in Afam VI power plant, Rivers State. Nigeria. Steady state monitoring and direct collection of data from the plant was performed including logged data for a period of 12 months. The data were analysed using various energy equations. Hysys software was used to model the temperature across the heating surfaces, and MATLAB software was used to determine the heat transfer coefficient, heat duties, steam flow, effectiveness of the HRSG. The optimization technique was carried out by varying the exhaust gas flow, exhaust gas temperature, steam pressure and the theoretical introduction of duct burner for supplementary firing. The results show that between 490℃ and 526℃, the percentage increase in the overall heat absorbed in the HRSG is 37.39%. It also show that for an increase in the exhaust gas mass flow by 80 kg/s, the steam generation increase by 19.29% and 18.18% for the low and high pressure levels respectively. The overall result indicates an improvement in the HRSG energy efficiency and steam generation. As the exhaust gas mass flow and temperature increases, the steam generation and system effectiveness greatly improved under the various considerations, which satisfy the research objective.

Heat calculation and numerical simulation in steam mining of permafrost gas hydrate

Steam mining method was injecting hot steam into the borehole to heat the hydrate strata at the same time of depressurization mining,which could promote further decomposition and expand mining areas of gas hydrate. Steam heat calculation would provide the basis for the design of heating device and the choice of the field test parameters. There were piping heat loss in the process of mining. The heat transfer of steam flowing in the pipe was steady,so the heat loss could be obtained easily by formula calculation. The power of stratum heating should be determined by numerical simulation for the process of heating was dynamic and the equations were usually nonlinear. The selected mining conditions were 500-millimeter mining radius,10 centigrade mining temperature and 180 centigrade steam temperature. Heat loss and best heating power,obtained by formula calculation and numerical simulation,were 21. 35 W/m and 20 kW.

A Study of the Jet System of the Recovery Concerning Waste Heat of Steam Condensate

This paper presents a frame figure of the recovery system concerning waste heat of steam condensate. When steam phase changes into liquid state in the condenser, the heat equilibium equation, gas state equation, mass flow calculating equation of the jet steam and incondensable gas equation are established. The coupling function between condensate unit and recovery pump of the hot condensate with ejector is studied. The paper sets up the fluid continuity equation, heat equilibium equation and efficiency equation of the ejector and points out the technical key how the prevent hot condensate change into steam phase. When fluid passes from circulation loop through pump to export, the energy equations are obtained here. At last, signal figure of the applied examples are given and settle the techanical questions of the jet system are discussed.

The Research of Heat Transfer Area for 55/19 Steam Generator

A calculation method of heat transfer area for vertical natural circulated steam generator was introduced. According to the design requirements of steam generator 55/19 of CPR1000, its heat transfer area was calculated based on this method. The results show that the accuracy of partitional and overall calculation method is almost the same, but the result is different when using different calculation models. And the results are compared with the foreign companies for 55/19 steam generator.

Dynamic simulation of drum level sloshing of heat recovery steam generator

Drum level sloshing is the latest discovery in the application of heat recovery steam generator (HRSG) in combined cycle, and shows certain negative influence on drum level controlling. In order to improve drum level controlling, influence factors on the drum level sloshing were investigated. Firstly, drum sub-modules were developed using the method of modularization modeling, and then the model of drum level sloshing was set up as well. Experiments were carried out on the experimental rig, and the model was validated using the obtained experimental results. Dynamic simulation was made based on the model to get a 3-D graph of drum level sloshing, which shows a vivid procedure of drum level sloshing. The effect of feed-water flow rate, main-steam flow rate and heating quantity on the drum level sloshing was analyzed. The simulation results indicate that the signals with frequency higher than 0.05 Hz are that of drum level sloshing, the signals with frequency of 0.0-0.05 Hz are that of drum level trendy and "false water level", and variation of the feed-water flow rates, main-steam flow rates and heating quantities can change the frequency of drum level sloshing, i.e., the frequency of sloshing increases with the increase of feed-water flow rate, or the decrease of the main-steam flow rate and the heating quantity. This research work is fundamental to improve signal-to-noise ratio of drum level signal and precise controlling of drum level.

Study of Models for Heating Power Station Operator Training Systems

This paper is devoted to development and study of models for operator training systems of heating power station processes management. It proposed a mathematical model describing the management processes of heating power units of the technological complex considering the relationship of technological variables in deviations effective in real time. A software complex is developed for the system of training of operators controlling processes in heating station units. Obtained results may be used in the course of development of computer training systems for operators of heating power stations with cross-linkage.

配置吸收式热泵的热电联产机组厂级智能运行优化

为提高配置吸收式热泵的热电联产机组的全厂运行经济性,基于案例电厂的运行历史数据,使用滑动窗口法进行数据预处理并提取稳态工况,建立配置吸收式热泵的热电联产机组煤耗预测数学模型。以全厂热电联产机组总煤耗最小为适应度函数,利用粒子群优化算法求解得出配置吸收式热泵的热电机组最佳背压和各台热电机组最佳抽汽量。基于以上研究设计了供热系统智能优化软件,实现供热系统在线监测与优化调节,对各供热单元分别提出优化指导,使机组运行经济性最佳,进而降低整体煤耗。计算结果表明:实行供热系统智能优化策略可为案例电厂供热系统平均每小时节省标准煤约1.81 t,节能效果显著。

自然对流下蒸汽凝结表面传热系数测定实验装置研制

自然对流下蒸汽凝结表面传热系数测定实验是将蒸汽通过一组表面状态各不相同的管道,测定管道在大空间空气介质中自然冷却过程中的蒸汽凝结表面传热系数。由于管道的材质、几何形状、接触方式及管外空气流动状况都会不同程度地影响换热效果,因此测定每根管道的表面传热系数值,可条理性和系统性地分析影响传热过程的各因素。该文设计了自然对流下蒸汽凝结表面传热系数测定实验装置,可开展管道材质、肋片结构、管道横截面几何形状、管道保温材料对传热系数的影响实验研究。应用实践表明,实验项目内容全面,提高了学生的课堂积极性,具有良好的教学效果。

湿热处理对杂豆馒头淀粉消化特性及风味品质的影响

目的研究湿热处理对杂豆馒头消化特性及风味品质的影响。方法选取湿热处理豌豆、红豆、白芸豆3种杂豆制作杂豆馒头,对湿热杂豆馒头的色度、比容、感官评分等进行评价,通过固相微萃取-气相色谱-质谱法(solid phase microextraction-gas chromatography-mass spectrometry,SPME-GC-MS)分析湿热粉杂豆馒头挥发性风味物质变化规律,并对馒头进行体外淀粉消化实验。结果湿热处理杂豆粉的添加降低了馒头的比容,改变了馒头的色度。对豌豆馒头和白芸豆馒头感官评分没有影响,但可显著提高红豆馒头的感官评分(P<0.05)。SPME-GC-MS从湿热杂豆馒头中共检出47种挥发性成分,主要为醛类、醇类、酯类、酮类、芳香族类、烷烃类及杂环类。淀粉体外消化特性表明3种杂豆馒头的抗性淀粉含量显著高于小麦馒头,淀粉水解率低于小麦馒头。结论湿热处理可使杂豆馒头风味品质改善,使红豆馒头和白芸豆馒头抗性淀粉含量提高和淀粉水解率降低,但对豌豆馒头没有影响。研究结果为淀粉基杂豆营养健康食品的加工提供数据支撑。