A combined numerical simulation was conducted to couple fluid flow between exhaust hood and last-stage blades of a 600MW steam turbine using the computational fluid dynamics software CFX.The influence of the initial diffusion angle,the diameter and the axial length of the guide on the aerodynamic performance of the exhaust hood was studied.The results indicate that the aerodynamic performance of the exhaust hood has been improved with the increase of the initial diffusion angle.There is a flow separation in diffuser when the initial angle increases to 30°.The most appropriate value is 25°.It is not conducive to the aerodynamic performance of the exhaust hood that the diameter and the axial length of the guide are too large or too small.The most appropriate value of the diameter and the axial length of the guide are 5000mm and 900mm,respectively.The most appropriate value of the three variables was selected as the modification scheme of the guide.Comparing with the aerodynamic performance of the exhaust hood before reformation, the static pressure recovery coefficient of the outlet of the exhaust hood increases by 7.2%,as well as the total pressure loss coefficient of the outlet of the exhaust hood reduces by 8.4%.The aerodynamic performance is improved obviously.

目前火力发电厂均安装有烟气脱硝系统.烟气脱硝催化剂的最佳活性温度区间一般为320~420摄氏度.机组启动期间,发电机并网前,脱硝反应器入口温度无法达到催化剂要求的最低连续喷氨温度,导致机组在并网后长时间氮氧化物排放超标.为满足机组正常启动过程中氮氧化物全负荷达标排放,华能沁北发电有限责任公司(简称沁北电厂)锅炉专业对本厂60万千瓦、100万千瓦机组的锅炉管屏布置、设备结构、运行方式以及机组启动过程中影响脱硝催化剂入口温升速度的各种因素进行了深入分析,并结合历次机组启动参数的变化规律,确定了脱硝全负荷投运方案,达到了预期的效果.

The steam leakage of diaphragm gland influences on relative internal efficiency of steam turbine greatly.There are larger formal differences between current steam leakage calculation formulas for various diaphragm glands.The differences and the similarities of several frequently-used steam leakage calculation formulas for various diaphragm glands and the applicable conditions for each formula were theoretically analyzed in depth;and a general formula of steam leakage calculation for diaphragm glands was given.Based on practical examples,the calculation results of various calculating formulas were analyzed.

The O_2/CO_2 pulverized coal combustion technology for power plant is a new kind of pulverized coal combustion technology,which uses pure oxygen and recycled flue gas to make pulverized coal combustion instead of air,also known as oxygen-enriched combustion technology or oxygen/flue gas recirculation technology. In the paper,the development status at home and abroad is described;the features of the O_2/CO_2 pulverized coal combustion technology are represented,and the 600MW sub-critical parameters,corner tangential,once reheat, controlled circulation steam drum boiler in a power plant is as a example to calculate and analyze.The results show that:the O_2/CO_2 pulverized coal combustion technology for power plant is an economical,high-efficiency, saving-energy,environment-friendly combustion technology,which is in the pilot study stage.In the case of the low-carbon economy,the application of the O_2/CO_2 pulverized coal combustion technology for power plant is convenient to the realization of saving-energy and reducing-emission goals,in line with the demand of building a resource-saving and environment-friendly society.

With the development of the times,people continue to raise the awareness of energy saving,and variable-speed control pumps is both convenient and energy saving.At present,because of the higher the price of converter,it becomes a trend for small and medium type pumps to adopt variable-speed control to save energy. But energy-saving is difficult to quantify.This paper presents a simple method to be used for Frequency Control of engineering and technical personnel,as estimating and budgeting and decision-making theory.

The author compile the thermodynamics calculating program for a 300MW steam turbine in constant pressure and variable pressure operation condition,using it a series of indexes is got,such as governing valve pressure loss,exit temperature in high pressure casing,relative internal efficiency of governing stage,consumed power of feed-water pump,heat rate and ideal cycle thermal efficiency.Through compared and analyzed the above indexes,the optimal sliding pressure operation mode is obtained and the range of load is definitude.The influence upon safety of steam turbine with sliding pressure operation is also analyzed in this paper.