1000 MW燃煤机组不同负荷锅炉传热特性

以1000MW超超临界塔式锅炉为研究对象,建立了锅侧和炉侧的三维耦合传热计算模型。基于锅炉的设计参数,采用该模型计算了锅炉传热过程。对超超临界锅炉不同负荷条件进行数值模拟,分别选取锅炉的最大连续蒸发量(boiler maximum continuous rating,BMCR)工况、75%BMCR工况和50%BMCR工况来考察机组在调峰时锅炉传热规律。通过对炉侧炉膛壁面、炉膛内部、炉膛水平截面温度和热流分布以及水冷壁管壁和工质温度分布的分析,发现BMCR工况、75%BMCR工况的温度和热流在炉膛内的变化趋势一致,而50%BMCR工况的温度变化缺乏一般性规律,并且在螺旋水冷壁区域容易出现传热恶化现象。

面向对象的通用锅炉热力计算软件开发

分析了锅炉传热的抽象物理模型。采用面向对象技术建立了锅炉传热的软件对象模型并讨论了建模关键技术 ,据此设计了通用于各炉种、炉型。

电站锅炉水动力研究

综述了我国电站锅炉水动力研究发展历史和现状,阐述了我国早期的电站锅炉水动力研究,亚临界直流锅炉研制,自然循环锅炉水动力研究,超临界压力直流锅炉水动力特性研究,并提出了我国电站锅炉水动力今后工作的发展方向和重点:发电设备将向着更高参数、更大容量发展,超超临界锅炉的蒸汽参数将达到700°C、35 MPa,这就要求针对该参数开展锅炉水动力研究;三大发电设备制造集团相继从国外引进了各种锅炉炉型配以不同的燃烧方式,应针对不同炉型、燃烧方式及煤种开展水动力研究,以确保锅炉运行的安全性;上世纪80年代编制出版了JB/Z 201—1983《电站锅炉水动力计算方法》,受出版时间的限制,许多新的技术和研究成果亟待补充.

对锅炉运行中的问题的浅析

本文首先概述了锅炉的原理再对常见锅炉进行了分类讨论, 对几个现在面临的大问题进行深入的讨论并提出几个有效的解决措施,主要解决水垢问题和蒸发管传热恶化的问题,最后对锅炉论以自己的展望思考.

The Heat Transfer Coefficients of the Heating Surface of 300 MWe CFB Boiler

A study of the heat transfer about the heating surface of three commercial 300 MWe CFB boilers was conducted in this work. The heat transfer coefficients of the platen heating surface, the external heat exchanger (EHE) and cyclone separator were calculated according to the relative operation data at different boiler loads. Moreover, the heat transfer coefficient of the waterwall was calculated by heat balance of the hot circuit of the CFB boiler. With the boiler capacity increasing, the heat transfer coefficients of these heating surface increases, and the heat transfer coefficient of the water wall is higher than that of the platen heating surface. The heat transfer coefficient of the EHE is the highest in high boiler load, the heat transfer coefficient of the cyclone separator is the lowest. Because the fired coal is different from the design coal in No.1 boiler, the ash content of the fired coal is much lower than that of the design coal. The heat transfer coefficients which calculated with the operation data are lower than the previous design value and that is the reason why the bed temperature is rather high during the boiler operation in No.1 boiler.

The Impact of Bed Temperature on Heat Transfer Characteristic between Fluidized Bed and Vertical Rifled Tubes

In the present work,the heat transfer study focuses on assessment of the impact of bed temperature on the local heat transfer characteristic between a fluidized bed and vertical rifled tubes(38mm-O.D.) in a commercial circulating fluidized bed(CFB) boiler.Heat transfer behavior in a 1296t/h supercritical CFB furnace has been analyzed for Geldart B particle with Sauter mean diameter of 0.219 and 0.246 mm.The heat transfer experiments were conducted for the active heat transfer surface in the form of membrane tube with a longitudinal fin at the tube crest under the normal operating conditions of CFB boiler.A heat transfer analysis of CFB boiler with detailed consideration of the bed-to-wall heat transfer coefficient and the contribution of heat transfer mechanisms inside furnace chamber were investigated using mechanistic heat transfer model based on cluster renewal approach.The predicted values of heat transfer coefficient are compared with empirical correlation for CFB units in large-scale.

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.

The Study on the Heat Transfer Characteristics of Oxygen Fuel Combustion Boiler

According to 350 MW and 600 MW boilers,under oxygen fuel condition,through the reasonable control of the primary and secondary flow and the correct option and revision of mathematical model,the temperature distribution,heat flux distribution and absorption heat distribution,etc.was obtained which compared with those under air condition.Through calculation,it is obtained that the primary and secondary flow mixed well,good tangentially fired combustion in furnace was formed,the temperature under air condition obviously higher than the temperature under O26 condition.The adiabatic flame temperature of wet cycle was slightly higher than that of dry cycle.The maximum heat load appeared on the waterwall around the burner area.The heat load gradually decreased along the furnace height up and down in burner area.The heat absorption capacity of the furnace under O26 was lower than that under the air condition.The heat absorption capacity of the platen heating surface under 026 was equal to that under air condition.And the heat absorbing capacity of waterwall under O26 was about 7%~12% less than that under air condition.

Experimental Investigation of Transient Heat Transferin the Once-Through Boiler Water Separator

The transient heat transfer between working fluid and inner wall of 600 MW supercritical pressureboiler's water separator model during start-up was experimentally explored. The test conditions forwater steam two-phase were as follows: pressure P = 3 ~ 11 MPa, mass now M = 0.2 ~ 0.35 kg/s,and mass quality x = O.2 ~ 0.8; for subcooled water P = 3 ~ 11 MPa, M = 0.2 ~ 0.35 kg/s, andsubcooled degree △θ = 10℃. By using an accurate and tractable inverse heat conduction solution,the correlations of single phase and twouphase transient heat transfer coefficients were obtained. Theexperimental results demonstrated the heat transfer enhanced for subcooled water and water steammixture compared with fully developed turbulent flow in tube. The increasing heat transfer effect maybe attributed to the deformation or destruction f the boundary layer.

The Imaginary Plane Mothod of Radiation Heat Transfer in The Freeboard of Atmospheric Bubbling Fluidized Bed Boiler

An imaginary plane method for calculation of radiative heat trensfer and its application in the freeboard of AFBC boiler is presented in this paper. The combustion reaction and particle concentration are taken into account in this method. With is method, one-dimensional freeboard model for radiative heat transfer has been made. Results from this model have been compared with the experimental results of a 130 t/h AFBC boiler. The distribution of flue gas temperature and heat flux at the waterwell are obtained. It is shown that this model has the advantage of good accuracy and requiring less computation time. The applicability of the predicted results in the AFBC boiler design and operation was also discussed.

Experimental Investigation on Heat Transfer Characteristics of Water in Inclined Downward Tube of a Supercritical Pressure CFB Boiler

In this study, experiments have been performed for an investigation on heat transfer of water in an inclined downward tube with an inner diameter of 20 mm and an inclined angle of 45° from the horizon, with the range of pressure from 11.5 to 28 MPa, mass flux from 450 to 1550 kg/(m2 s), and heat flux from 50 to 585 k W/m2. Based on the experimental data, the temperature distribution in the tube wall was derived. The heat transfer characteristics of inclined downward flow were compared with that of vertical downward flow. The effects of heat flux on wall temperature were analyzed and the corresponding empirical correlations were presented. The results show that heat transfer characteristics of water in the inclined downward tube are not uniform along the circumference from the top surface to the bottom surface. An increase in heat flux exacerbates the non-uniformity. At subcritical pressures, both dry-out and departure from nucleate boiling(DNB) occur at the top surface of the inclined downward tube; inversely, only dry-out takes place on the bottom surface of the inclined downward tube and in the vertical downward tube. At near-critical pressures, DNB and dry-out occur in the comparing tubes with greater possibility. At supercritical pressures, heat transfer gets enhanced in the pseudo-critical enthalpy region; in the high enthalpy region, the top surface temperature of the inclined downward tube decreases obviously.