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Plants and Equipment
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
Use some caution with this term. Normally, a heat trap is meant when the term preheater is used. Some manufacturers will call a steam coil installed in an air supply an air preheater since it does do what the name implies. Within the trade, such devices are called “steam air heaters” or “steam coil air heaters” to differentiate them from the traditional heat traps. An air preheater uses energy left in the flue gas that leaves the boiler to preheat the combustion air. This makes the air preheater the only true heat trap. It does trap the heat without adding any surface to the boiler. The way the air preheater increases the efficiency of the boiler is by raising the temperature of the combustion air using the stack heat instead of fuel. There is also a slight increase in heat flow through the boiler heating surface due to higher furnace temperatures. An advantage of air heaters is higher temperature differentials. Instead of using 200°F plus feed water to cool the flue gas, the combustion air entering at 80°F is used. There is potential for lower flue gas outlet temperatures, which means higher boiler efficiency. However, corrosion of metal parts of the preheaters and ductwork to and including the stack must be given consideration. The steam coil air heater is used to warm up the cold air experienced in the winter to a temperature sufficient to protect the air preheater and the associated duct work. Since it uses steam, it detracts from the overall plant efficiency.
Plants and Equipment
Published in Kenneth E. Heselton, Boiler Operator’s Handbook, 2020
Use some caution with this term. Normally we mean a heat trap when we use the term preheater but some manufacturers will call a steam coil installed in an air supply an air preheater because it does do what the name implies. Within the trade such devices are called “steam air heaters” to differentiate them from our traditional heat traps. An air preheater uses energy left in the flue gas that leaves the boiler to preheat the combustion air. This makes the air preheater the only true heat trap because it does trap the heat without adding any surface to the boiler. The way the air preheater increases the efficiency of the boiler is by raising the temperature of the combustion air using the stack heat instead of fuel. There’s also a slight increase in heat flow through the boiler heating surface due to higher furnace temperatures.
Reliability Analysis Using Condition Monitoring Approach in Thermal Power Plants
Published in Harish Garg, Mangey Ram, Reliability Management and Engineering, 2020
Hanumant Jagtap, Anand Bewoor, Ravinder Kumar, Mohammad H. Ahmadi, Dipen Kumar Rajak
The process of electricity generation is initiated by drawing atmospheric air by a forced draft fan through an air preheater. While passing the air through the air preheater, the air gets heated and is then transferred to the combustion chamber. At the same instant, the primary air fan sucks the air and supplies it to the coal mill. Inside the coal mill, the crushing of coal is done. Afterward, the primary air fan takes the pulverized coal and using a classifier supplies it to the furnace for the purpose of heating and steam is generated.
System design and thermo-economic analysis of municipal solid waste power system integrated with steam dryer
Published in Drying Technology, 2022
Mengjie Li, Kaixuan Yang, Rongtang Liu, Ming Liu, Junjie Yan
The air preheater is used to preheat air before air is fed to the boiler. However, if the flue gas air preheater is used in the MSWPs, then serious low-temperature erosion may occur due to the HCl contained in boiler flue gas. Therefore, steam-air preheaters are used in MSWPs, i.e., LTAP and HTAP. As shown in Figure 2, if the dryer exhaust of MSWPD is discharged to the environment after condensation, then the energy in the dryer exhaust is wasted. The waste heat recovery system (WHRS) can be adopted to reduce heat loss from the dryer exhaust gas. The WHRS is also shown in Figure 2. The WHRS consists of two waste heat recovery devices, namely, an additional air preheater (AAP) and a low-temperature economizer (LTE), which includes a vapor condensation section and a drainage heat release section. The AAP is used to heat air fed to the boiler, and the LTE is used to heat water condensate of steam turbine system.
A framework of clustering based on W-EFC with updating strategy for power plant air preheater monitoring
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Hui Gu, Pan Chen, Hongxia Zhu, Kening Zhang
Air preheater ash fouling occurs when the metal surface temperature is below the acid dew point. The acid substances in the flue gas condensing process will cause grime adhesion and heat transfer channel blockage. Fouling and low-temperature corrosion are the two problems closely related with air preheater. Corrosion causes fouling, and fouling will increase the corrosion degree, leading to blocking ash phenomenon at last. Fouling by substances on the surface of the tube contains three categories. The first one is generated by the acid etching various amounts of corrosion products, the amount of which depends on the number of acid etching amount produced, the temperature, and the type of metal. The second type is the formation of fouling ash captured from pipe, and the third one is the acid and sulfate formed by iron, sodium, and calcium metal elements in fly ash.
Thermodynamic studies and parametric effects on exergetic performance of a steam power plant
Published in International Journal of Ambient Energy, 2019
Vinay Kumar, Bhargav Pandya, Vijay Matawala
Table 8 represents energy analysis of power plant components. Here, efficiency of boiler is found by the direct method. Boiler E has the maximum efficiency on comparing with the other four boilers because of advance design (compact separator). In case of turbine efficiency, turbine BHEL has maximum efficiency comparing with other turbines because of back-pressure-type turbine. Table 2 shows the energy analysis for components of each boiler. Boiler consists of super-heater, air preheater and economizer as components of second pass and combustion chamber. Super-heater has low efficiency comparing with all components of boilers due to superheating process. Air preheater has high efficiency comparing with all boiler components.