基于热经济学模型的烧结余热双压锅炉操作参数优化

以最大年度化收益为目标函数,建立了烧结余热双压锅炉蒸汽参数热经济学优化模型,基于遗传算法采用MATLAB编程,对余热锅炉出口蒸汽参数进行优化得出适宜操作参数。以处理量为390万t/a的烧结矿余热竖罐式回收系统为例,其烟气温度为540℃,流量为62.5万m~3/h,得出了锅炉最大年度化收益对应的蒸汽参数为:高压蒸汽压力4.49 MPa,高压蒸汽温度450℃,低压蒸汽压力0.33 MPa,低压蒸汽温度235℃,此时的高压蒸发量为25.41 kg/s,低压蒸发量为4.05 kg/s,发电功率为21.02 MW,年度化收益为7 925.2万元。     

联合循环供热机组双压余热锅炉主蒸汽参数匹配研究

针对供热机组余热锅炉(heat recover steam generator,HRSG)主蒸汽参数匹配研究不足问题及提高联合循环机组经济效益,针对某燃机常用工况下的余热锅炉主蒸汽参数进行优化匹配。通过效益值对参数进行优化选取,并假设与同样条件下的纯凝汽轮机主蒸汽参数选取进行对比分析,观察供热对余热锅炉主蒸汽参数匹配的影响。结果表明:汽轮机类型不同,选取的主蒸汽参数也会有差异,两种汽轮机选取蒸汽压力参数的趋势类似,在一定范围内,低压蒸汽压力选取是越低越好,高压蒸汽压力选取越高越好;对于蒸汽温度参数的选取,纯凝汽轮机蒸汽温度选取是越高越好,供热汽轮机则是蒸汽温度选取越低越好;余热锅炉主蒸汽参数匹配结果显示,选取高压蒸汽压力6 MPa、高压蒸汽温度505℃、低压蒸汽压力0.5 MPa、低压蒸汽温度250℃,较于原设计参数重新匹配后的主蒸汽参数可使年化收益增加230多万元。     

纯低温余热发电系统的优化分析

通过建立纯低温余热发电系统的热力学模型,计算分析了过热蒸汽压力、进口烟气温度和节点温差等因素对纯低温余热发电系统发电性能的影响.结果表明:在设计纯低温余热发电系统时,存在一优化过热蒸汽压力,使得纯低温余热发电系统的单位烟气发电功率最大;随着进口烟气温度的升高,系统单位烟气发电功率增大,对应的优化过热蒸汽压力升高;而随着节点温差的增大,系统单位烟气发电功率减小,对应的优化过热蒸汽压力降低.     

双压无再热联合循环系统热力参数优化分析

文中针对燃气蒸汽联合循环中双压无再热汽水系统的热力参数对循环效率的影响,利用热平衡方程式通过Matlab计算软件建立了汽水系统的计算模型,基于PG9171E型燃气轮机,以底循环效率为目标函数,建立了余热锅炉的高压蒸汽温度上限,排汽湿度,高压蒸汽膨胀到低压蒸汽压力时与低压蒸汽的温差三个约束条件,对系统热力参数进行计算,得到热力参数对系统性能的影响曲线,通过进一步优化,最终得到汽轮机最佳的运行参数。     

纯低温余热发电系统热工参数的设计优化

通过建立低温余热发电系统的热力学模型,定量分析和对比了不同热丁参数对低温余热发电系统设计性能的影响.研究表明:进口烟气温度、蒸汽压力以及节点温差是影响纯低温余热发电系统设计性能的主要热工参数,其它热工参数对系统性能的影响很小;提高进口烟气温度、降低蒸汽压力或减小节点温差,均可显著降低设计出口烟气温度,从而增大蒸发量,提高热效率;但是当系统对最低排烟温度有要求时,蒸汽压力和节点温差存在下限值.     

纯低温双压余热发电系统性能分析及参数优化

针对新型干法水泥窑纯低温双压余热发电系统,进一步完善了性能评价方法,以 5 000t/d水泥生产过程为实例分析了窑头AQC、窑尾SP余热锅炉废气参数、高压段、低压段蒸汽参数、公共省煤器出口水温对余热发电系统性能的影响以及各参数之间的耦合关系.结果表明:在确定的水泥窑废气参数下,通过对纯低温双压余热发电系统热力参数的优化,能够进一步提高余热发电量.     

铁合金矿热炉余热发电双压系统的技术应用分析

基于铁合金矿热炉立式双压余热发电系统,首先对4台25500kV·A硅铁矿热炉冶进行了余热资源评估及?值分析,得出烟气余热?值为65528.24MJ/h,其次对过热器热端温差取40℃,蒸发器窄点温差取30℃,省煤器接近点温差取5.0℃,得出双压系统产生蒸汽1.55MPa、360℃、40.2t/h,蒸汽0.3MPa、180℃、7.5t/h,单压系统产生蒸汽1.15MPa、360℃、42.1t/h,双压系统比单压系统排烟温度低21.5℃,汽耗率高0.16kWh/kg,发电机输出功率高774.07KW,系统整体效率高1.6%,再次根据工程实际运行经验,得出双压立式锅炉传热特性、汽水循环方式、漏风量、系统阻力、清灰效果、占地面积等均优于单压卧式锅炉。然后根据4台25500kV·A硅铁矿热炉运行情况,对双压系统进行了经济效益分析,得出年均税后利润为1142万元,全投资内部收益率20.8%,全投资回收期3.7年。最后进行了展望,根据全国年产量铁合金约为1300万吨,余热利用年发电量约能达到100亿KWh,所以这项技术具有广阔的运用前景。     

降低联合循环电厂余热锅炉排烟温度的措施

针对某工程西门子SGT5-2000E燃气轮机,余热锅炉采用双压蒸汽循环系统,优化蒸汽参数,降低低压节点温差,余热锅炉尾部设热水加热器,回收利用烟气余热,通过以上措施,余热锅炉排烟温度降到90℃以下。     

基于BEST系统超超临界1000 MW二次再热蒸汽机组的参数选取

为研究抽汽背压式汽轮机(BEST)系统超超临界1 000 MW二次再热蒸汽机组参数的选取,基于某电厂二期2×1 000 MW超超临界机组扩建项目,建立1 000 MW超超临界高效二次再热蒸汽机组的设计计算,使用EBSILON软件建立完整的热力系统模型,得出主蒸汽温度、再热蒸汽温度、主蒸汽压力、再热蒸汽压力和锅炉效率等参数对BEST系统的影响规律。研究结果表明：对于12级回热的BEST系统来说提高主蒸汽的温度比提高主蒸汽的压力更能提高系统的发电热效率;BEST系统最佳工况点的再热蒸汽压力是15.028 MPa/4.079 MPa;锅炉效率变化范围在85%～95%时,随着锅炉效率变化1%,系统发电热效率随之变化0.51%。     

东方汽轮机厂N300-165-535/535双缸双排汽30万千瓦汽轮机组的设计

一、主要技术规范及经济指标 1.主要技术规范 型号: N300-165/535/535型 型式:亚临界中间再热单轴双缸双排汽凝汽式汽轮机 额定功率:30万千瓦 计算功率(经济功率或最大功率):31.8万千瓦 额定参数:蒸汽压力:165绝对大气压 蒸汽温度:535℃ 再热蒸汽压力:32.61绝对大气压 再热蒸汽温度:535℃ 冷却水温度:20℃ 背压:0.055绝对大气压 进汽流量: 1025吨/时 中间再热汽量:864吨/时 低压缸排汽量:577吨/时 给水温度:266.5℃ 回热系统:3高加 1除氧 4低加,共八级回热 通流型式:高中压合缸(高压8级 中     

Matching of a DC motor to a photovoltaic generator using a step-upconverter with a current-locked loop

A photovoltaic (PV) generator is a nonlinear device having insolation-dependent volt-ampere characteristics. Because of its relatively high cost, the system designer is interested in optimum matching of the motor and its mechanical load to the PV generator so that maximum power is obtained during the entire operating period. However, since the maximum-power point varies with solar insolation, it is difficult to achieve an optimum matching that is valid for all insolation levels. In this paper it is shown that for maximum power, the generator current must be directly proportional to insolation. This remarkable property is utilized to achieve insolation-independent optimum matching. A shunt DC motor driving a centrifugal water pump is supplied from a PV generator via a step-up converter whose duty ratio is controlled using a current-locked feedback loop     

Natural convection of a non-Newtonian fluid about a horizontal cylinder and a sphere in a porous medium

The problem of natural convection of a non-Newtonian fluid about a horizontal isothermal cylinder and an isothermal sphere in the porous medium is considered. The present study is based on the boundary layer approximation and only suitable for a high Rayleigh number. Similarity solutions are obtained by using the fourth order Runge-Kutta method. The effects of the wall temperature T_W and the new power-law index n on the characteristics of heat transfer are discussed.     

Exploration of heat transfer effect in a magnetohydrodynamics flow of a micropolar fluid between a porous and a nonporous disk

An analysis is carried out for the flow characteristics of a conducting micropolar fluid. The fluid was passed in between two parallel disks of infinite radii. The novelty of the study is to consider one of the disks as porous and the other one as nonporous, and the external magnetic field is applied along the transverse direction of the flow. The flow phenomena for the polar fluid characterized by the magnetic effect in conjunction with the temperature equation reduce to a set of coupled nonlinear ordinary differential equations using the requisite transformations and nondimensionalization. An analytical approach such as the variation parameter method is employed to tackle the system efficiently. To emphasize the effect of various physical parameters contributing to the flow phenomena, that is, non-zero tangential slip, Reynolds number, Prandtl number, magnetic parameter, and material parameter on the flow profiles of axial and radial velocities, the microrotation and temperature profiles are presented graphically. To validate the simulated results, a comparison with established results is made, and it is concluded that both are in good correlation.     

Evaporating characteristics of a microlayer under a bubble

Using the Hallinan‐Ervin model, the flow and evaporation in a bubble microlayer were theoretically analyzed, and the dryout characteristics and Staub's criterion were discussed in detail. It was revealed that the critical dryout radius is associated with the wettability of the heated surface, and that the dominant role for microlayer evaporation is disjoining pressure, not surface tension gradient. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(6): 456–462, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10052     

Solidification of a liquid about a cylindrical pipe

The temperature distribution and the rate of removal of heat by a coolant are predicted for the process of solidification of a liquid about a cold, isothermal pipe. The heat balance integral method incorporating spacial sub-division is used. It is found that acceptable results can be obtained by using only a small number of sub-divisions together with a piece-wise, linear profile. Furthermore, the results illustrate that the sensitivity which is normally associated with the heat balance integral method is overcome.     

Stability of a multi-machine system incorporating a superconductingalternator

A preliminary study on the transient behavior of a superconducting turbo-alternator in a typical multimachine system is described. The study covers the effect of conventional controllers, power-system stabilizers and phase advance networks. The open-loop response of the system is compared to the response when the superconducting alternator is replaced by its conventional counterpart     

Bioconvection in a squeezing flow of a micropolar fluid in a horizontal channel

The bioconvection flow of an incompressible micropolar fluid containing microorganisms between two infinite stretchable parallel plates is considered. A mathematical model, with a fully coupled nonlinear system of equations describing the total mass, momentum, thermal energy, mass diffusion, and microorganisms is presented. The governing equations are reduced to a set of nonlinear ordinary differential equations with the help of suitable transformations. The resulting nonlinear ordinary differential equations are linearized using successive linearization method, and the resulting system of linear equations is solved using the Chebyshev collocation method. The detailed analysis illustrating the influences of various physical parameters, such as the micropolar coupling number, squeezing parameter, the bioconvection Schmidt number, Prandtl numbers, Lewis number, and bioconvection Peclet number on the velocity, microrotation, temperature, concentration and motile microorganism distributions, skin friction coefficient, Nusselt number, Sherwood number, and density number of motile microorganism, is examined. The influence of the squeezing parameter is to increase the dimensionless velocities and temperature and to decrease the local Nusselt number and local Sherwood number. The density number of motile microorganism is decreasing with squeezing parameter, bioconvection Lewis number, bioconvection Peclet number, and bioconvection Schmidt number.     

Hydrothermal Behavior of a Ferrofluid in a Corrugated Channel in the Presence of a Magnetic Field

In this paper, results of applying a non‐uniform magnetic field on a dilute ferrofluid (water and 3% vol. Fe₃O₄) flow in a corrugated channel under a constant heat flux boundary condition have been reported. The thermal behavior of the flow is investigated numerically using a two‐phase mixture model and control volume technique. It is concluded that using a magnetic field with a negative gradient on a nanofluid flow in corrugated channels can be proposed as a suitable method to achieve higher heat transfer performance and augment the heat transfer coefficient and also reduces the wall temperature. This method can lead to the design of more compact heat exchangers. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(1): 80–92, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21060     

The limiting characteristics of a cascade photoconverter of a new type based on a homogeneous semiconductor

A homogeneous planar photoconverter (PC) of a new type based on a multi-junction n-p-p ⁺-n-p-p ⁺-...-n-p-p ⁺ semiconductor structure was proposed. This semiconductor structure is a cascade PC consisting of several exposed PCs connected in series, with the light passing through the previous semiconductor layers. A theory was worked out, and the limiting values of photoelectric and energy characteristics of high-voltage devices that convert monochromatic and solar light were developed. These values include optimum values of the thickness and the number of the PCs applied onto the base PC, spectral selectivity, voltage-current characteristics, and performance. The no-load voltage rises practically in a linear fashion when the number of cells in the cascade increases. With an optimum number of cells, the peak performance values reach their peaks and considerably exceed the performance of the base PC, especially at a low carrier collection coefficient in the base PC.