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热风炉在非设计工况下的运行标准

2018-12-05 20:29:01 无锡科达脚手架厂 阅读

热风炉的结构设计是根据已选定的蒸汽容量参数,燃用的燃料的条件综合地考虑了各种因素,确保热风炉能安全和经济地运行前提下得出的。在基本满足这些条件下热风炉能符合各种安全和环保标准长期地运行。当然在设计时对各种参数都留有一定裕量,超过时则会引起一些运行的不正常。首先热风炉工作要符合热平衡原则,例如热风炉在额定参数下超出力,一般在超过额定负荷10%以下时,热风炉的经济性和安全性是能基本保证的。热风炉运行遇到非设计工况的情况主要有燃料特性、给水温度和漏风等。

The structure design of the hot blast stove is based on the selected steam capacity parameters and the fuel conditions, which comprehensively considers various factors to ensure the safe and economical operation of the hot blast stove. Under these conditions, the hot blast stove can meet various safety and environmental protection standards for long-term operation. Of course, there is a certain margin for all kinds of parameters in the design, which will cause some abnormal operation. Firstly, the hot stove should work in accordance with the principle of heat balance. For example, when the hot stove exceeds the rated load by 10%, the economy and safety of the hot stove can be basically guaranteed. The main operating conditions of hot blast stove are fuel characteristics, feed water temperature and air leakage.

一、燃料特性的变化

CHANGES IN FUEL CHARACTERISTICS

燃料成分对热风炉工作有多种影响。例如挥发分的多少会影响燃料的着火和燃烧。灰分的含量和性质会影响未燃尽损失、受热面的污染和磨损、炉膛的结渣等。水分的大小不但影响着火、燃烧和受热面的腐蚀等,而且还会使各区烟温、传热和热风炉热损失发生显著变化,水分和炉内过量空气对炉膛出口烟温、传热量和排烟热损失等在性质上是相似的,都是增加每公斤燃料燃烧后的烟气容积和降低理论燃烧温度。但是水分的比热容要比空气的大得多,所以在影响程度上要严重得多。燃料中水分增加时,由于理论燃烧温度降低显著,炉膛出口烟气温度也总要降低,而辐射传热量减少和对流传热量增加程度都比增大炉内过量空气时要大得多。这些情况都会使热风炉运行调节范围超过原有设计值。

Fuel composition has many effects on the operation of hot blast stove. For example, the amount of volatile matter will affect the ignition and combustion of fuel. The content and property of ash will affect unburned loss, contamination and wear of heating surface, slagging of furnace, etc. The size of moisture not only affects the ignition, combustion and corrosion of heating surface, but also causes significant changes in flue gas temperature, heat transfer and heat loss of hot blast stoves in different areas. The properties of moisture and excess air in the furnace are similar to those of flue gas temperature, heat transfer and heat loss of exhaust gas at the outlet of the furnace. They are all smoke after increasing the combustion of each kilogram of fuel. Gas volume and theoretical combustion temperature reduction. But the specific heat capacity of water is much larger than that of air, so the influence is much more serious. When the moisture content in fuel increases, the theoretical combustion temperature decreases significantly, so does the flue gas temperature at the outlet of the furnace. The reduction of radiation heat transfer and the increase of convective heat transfer are much greater than that of the increase of excess air in the furnace. These conditions will make the hot blast stove operation regulation range exceed the original design value.

二、给水温度的变化

II. Change of Feed Water Temperature

汽机负荷减少或高压加热器解列,都会使给水温度降低,尤其在机组运行初期,高压加热器尚未投入时,机组就要启动运行,这种现象经常发生。这时如果在同样燃料量下,热风炉蒸发量将下降,或在同样蒸发量下增加燃料量。所以热风炉运行将受到给水温度降低和燃料量增加的双重影响,即对流区吸热量将增大,对流过热器要加大减温量,省煤器吸热量增加,其出口烟温降低,空气预热器出口风温将降低。

Reduction of turbine load or decoupling of high-pressure heater will reduce feed water temperature. Especially in the early stage of unit operation, when high-pressure heater has not been put into operation, the unit will start operation. This phenomenon often occurs. At this time, if the same amount of fuel is used, the evaporation of hot blast stove will decrease, or the amount of fuel will increase at the same amount of evaporation. Therefore, the operation of hot blast stove will be affected by the decrease of feed water temperature and the increase of fuel quantity, that is, the heat absorption in convection zone will increase, the heat absorption of convection superheater will increase, the heat absorption of economizer will increase, the outlet flue gas temperature will decrease, and the outlet air temperature of air preheater will decrease.

三、热风炉漏风引起的变化

3. Change Caused by Air Leakage in Hot Stove

炉膛风同增加炉内过量空气系数的影响一样,但漏入冷风的影响和危害比热风要大,漏风处的位置不同,产生的影响也有差别。例如,燃烧器附近或炉膛下部漏入,会影响燃料着火和燃烧,以及理论燃烧温度,进而降低炉膛出口烟温。如果漏风在炉膛上部则主要会降低炉膛出口烟温。对流烟道各部位的漏风将降低该部位和以后烟道的烟温和传热温压,从而减少各部位的吸热量。如果漏风点接近热风炉出口,排烟温度可能低于原有水平,但排烟热损失将增大。综上情况热风炉运行应密切关注漏风部位和大小,采取必要措施增加热风炉严密性,现代热风炉大都采用膜式水冷壁结构,能有效地减少热风炉漏风。

The influence of furnace air is the same as that of increasing excess air coefficient in furnace, but the influence and harm of leakage of cold air is greater than that of hot air. The location of leakage is different, and the influence is also different. For example, the leakage near the burner or the lower part of the furnace will affect the ignition and combustion of fuel, as well as the theoretical combustion temperature, thereby reducing the flue gas temperature at the outlet of the furnace. If the air leakage is in the upper part of the furnace, it will mainly reduce the outlet flue gas temperature of the furnace. The air leakage in each part of the convective flue will reduce the flue temperature and heat transfer temperature and pressure in this part and the future flue, thus reducing the heat absorption in each part. If the air leakage point is close to the outlet of hot blast stove, the exhaust gas temperature may be lower than the original level, but the heat loss of exhaust gas will increase. In summary, hot blast stove operation should pay close attention to the location and size of air leakage, take necessary measures to increase the tightness of hot blast stove, modern hot blast stoves mostly use membrane water wall structure, which can effectively reduce air leakage of hot blast stove.

以上非设计工况下对热风炉运行的影响是经常可能发生的,热风炉的运行管理部门应当尽量采取措施避免发生。如影响较大,危及热风炉正常运行时,就需对热风炉进行技术改造,在经过详细的计算后,调整受热面大小,必要时增加炉膛高度,改进燃烧装置,提高对流受热面的防磨能力,改善辅助设备等。在这方面,国内外热风炉工作者也有很多成功的经验。

The influence of the above non-design conditions on the operation of hot blast stoves is often possible, and the operation management departments of hot blast stoves should take measures to avoid the occurrence as far as possible. If the influence is great and endangers the normal operation of the hot blast stove, it is necessary to carry out technical transformation of the hot blast stove. After detailed calculation, the size of the heating surface should be adjusted, the height of the furnace should be increased if necessary, the combustion device should be improved, the anti-wear ability of the convective heating surface should be improved, and the auxiliary equipment should be improved. In this regard, domestic and foreign hot stove workers also have a lot of successful experience. 



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