scholarly journals CORROSION OF AIR PREHEATER TUBES OF OIL SHALE CFB BOILER. PART I. DEW POINT OF FLUE GAS AND LOW-TEMPERATURE CORROSION

Oil Shale ◽  
2009 ◽  
Vol 26 (1) ◽  
pp. 5 ◽  
Author(s):  
T PIHU ◽  
H ARRO ◽  
A PRIKK ◽  
R ROOTAMM ◽  
A KONIST
Keyword(s):  
Low Temperature ◽  
Flue Gas ◽  
Oil Shale ◽  
Dew Point ◽  
Cfb Boiler ◽  
Air Preheater

Review of flue gas acid dew-point and related low temperature corrosion

2020 ◽  
Vol 93 (4) ◽  
pp. 1666-1677 ◽  
Author(s):  
Wujun Zuo ◽  
Xiaoyu Zhang ◽  
Yuzhong Li
Keyword(s):  
Low Temperature ◽  
Flue Gas ◽  
Dew Point

Performance Analysis and Optimization of Flue Gas Waste Heat Recovery System of a 600MW Coal-Fired Power Plant

2020 ◽  
Author(s):  
Xun Chen ◽  
Shu Xu ◽  
Yi Yang ◽  
Li-min Wang ◽  
Dun-dun Wang
Keyword(s):  
Performance Analysis ◽  
Flue Gas ◽  
Waste Heat ◽  
Structural Characteristics ◽  
Heating System ◽  
Heat Transfer Process ◽  
Dew Point ◽  
Air Preheater ◽  
Waste Heat Recovery System ◽  
Saving Effect

Abstract Recovering the waste heat of the flue gas from the boilers of coal-fired units, so that part of the boiler’s flue gas waste heat can be utilized in the turbine regenerative heating system is an important way to increase efficiency and reduce emissions of coal-fired units. In this paper, a 600MW supercritical coal-fired unit is taken as an example, and the conceptual design of a flue gas waste heat cascade utilization system is carried out. Based on the first and second laws of thermodynamics, the thermodynamic perfection of the heat transfer process of the rotary regenerative air preheater, the exergy efficiency of the heat displacement process of the flue gas waste heat cascade utilization system, and the overall performance parameters of the coal-fired unit are calculated and analyzed under different parameters such as the bypass flue ratio and the inlet air temperature of the regenerative air preheater. The energy-saving effect of flue gas waste heat cascade utilization system is restricted by factors such as acid dew point temperature, ammonium bisulfate (ABS) deposition inside the air preheater, etc. Based on the performance analysis of regenerative air preheater and ABS deposition law, considering the structural characteristics and operating parameters of air preheater, this paper gives a criterion number (R-number) of ABS deposition tendency, and analyzes the actual operation performance of flue gas waste heat cascade utilization system considering the restrictions.

scholarly journals Status and development for detection and control of ammonium bisulfate as a by-product of SCR denitrification

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kunling Jiao ◽  
Xiangyang Chen ◽  
Xuan Bie ◽  
Daokuan Liu ◽  
Mingjie Qiu ◽  
...  
Keyword(s):  
Flue Gas ◽  
Negative Impact ◽  
Dew Point ◽  
Detection Methods ◽  
Nox Removal ◽  
Air Preheater ◽  
Catalyst Life ◽  
Ammonium Bisulfate ◽  
The Impact ◽  
Ammonia Injection

AbstractWhen denitrification technology using NH3 or urea as the reducing agent is applied to remove NOx from the flue gas, ammonium bisulfate (ABS) by-product will also be generated in the flue gas. ABS has an impact on catalyst life span, denitrification efficiency etc., air preheater and its downstream thermal equipment also have a significant negative impact due to its plugging and corrosion. The requirement for NOx removal efficiency is improved by ultra-low emissions in China. However, wide-load denitrification makes the flue gas composition and temperature changing more complicated. Increasing ammonia injection can improve the NOx removal effect, but too much ammonia injection will lead to the formation of ABS and the increase of deposition risk, the contradiction between these two aspects is amplified by ultra-low emissions and wide-load denitrification in many plants. Coordinating NOx control and reducing the impact of ABS on equipment are issues that the industry needs to solve urgently. In recent years, extensive research on ABS had been carried out deeply, consequently, there has been a relatively in-deepth knowledge foundation for ABS formation, formation temperature, deposition temperature, dew point temperature, decomposition behavior, etc., but the existing researches are insufficient to support the problem of ABS under full load denitrification completely resolved. Therefore, some analysis and detection methods related to ABS are reviewed in this paper, and the impact of ABS on SCR, air preheater and other equipment and the existing research results on reducing the impact of ABS are summarized also. It is hoped that this review will provide a reference for the industry to solve the problems of ABS that hinder wide-load denitrification and affect ultra-low emissions.

scholarly journals Experiment Comparison between Engineering Acid Dew Point and Thermodynamic Acid Dew Point

2018 ◽  
Vol 38 ◽  
pp. 04008 ◽  
Author(s):  
Jinghui Song ◽  
Hui Yuan ◽  
Jianhua Deng
Keyword(s):  
Flue Gas ◽  
Pipe Wall ◽  
Waste Heat ◽  
Coupling Effect ◽  
Dew Point ◽  
Air Preheater ◽  
Heat Utilization ◽  
Actual Operation ◽  
Waste Heat Utilization ◽  
Coal Type

in order to realize the accurate prediction of acid dew point, a set of measurement system of acid dew point for the flue gas flue gas in the tail of the boiler was designed and built, And measured at the outlet of an air preheater of a power plant of 1 000 MW, The results show that: Under the same conditions, with the test temperature decreases, Nu of heat transfer tubes, fouling and corrosion of pipe wall and corrosion pieces gradually deepened. Then, the measured acid dew point is compared with the acid dew point obtained by using the existing empirical formula under the same coal type. The dew point of engineering acid is usually about 40 ℃ lower than the dew point of thermodynamic acid because of the coupling effect of fouling on the acid liquid, which can better reflect the actual operation of flue gas in engineering and has certain theoretical guidance for the design and operation of deep waste heat utilization system significance.

Process Simulation of Oil Shale Circulating Fluidized Bed Boiler Based on Aspen Plus

2012 ◽  
Vol 614-615 ◽  
pp. 49-52
Author(s):  
Qing Wang ◽  
Hai Bo Long ◽  
Hong Peng Liu ◽  
Zhi Feng Wang
Keyword(s):  
Fluidized Bed ◽  
Flue Gas ◽  
Oil Shale ◽  
Circulating Fluidized Bed ◽  
Circulation System ◽  
Performance Parameters ◽  
Gas Emission ◽  
Boiler Load ◽  
Cfb Boiler ◽  
Experimental Values

A model for the combustion of oil shale in the 65t/h circulating fluidized bed (CFB) boiler was developed, consisting of oil shale combustion, steam-water and ash circulation system, calculating the O2 and RO2 content of flue gas emission under three kinds of oil shale combustion in 65t/h CFB boiler. The calculated results indicate that the simulation values are consistent with the experimental values. Effect of boiler load on the temperature of furnace, flue gas emission, inlet and outlet flue gas of economizer was discussed based on the model. Boiler load on the increase results in a increase in temperature of furnace, flue gas emission, inlet and outlet flue gas of economizer. The main performance parameters of 65t/h oil shale CFB boiler system were discussed and preliminarily predicted by the model.

Waste / Low Quality Heat Recovery and Utilization With Low Temperature Economizers

2013 ◽  
Author(s):  
John M. Preston ◽  
W. Reid Watson ◽  
Charles B. Jones
Keyword(s):  
Sulfuric Acid ◽  
Fly Ash ◽  
Low Temperature ◽  
Flue Gas ◽  
Heat Recovery ◽  
Heat Rate ◽  
Economic Feasibility ◽  
Dew Point ◽  
Plant Performance ◽  
Acid Mist

Modern combustion steam-electric plants are designed to recover as much heat as economically feasible from the combustion products. As a part of the continuing effort by utilities to increase plant efficiency, extracting low quality heat from the flue gas stream prior to discharge through the stack to the environment has become economically attractive. “Economic feasibility” is strongly dependent on the cost of the fuel as well as quality of the heat recovered. The economic feasibility of deploying low-temperature economizers to cool flue gas from coal-fired steam-electric plants to a temperature well below the sulfuric acid mist dew point is not commonly practiced but could have a number of salutary effects on unit operations including reduction in fuel use, reduction in water, reduction in fly ash resistivity upstream of cold-side electrostatic precipitators and enhanced mercury oxidation/capture. Using a theoretical 600 MW (nominal) coal fired facility an additional 30.8 MW of electrical output is available with the installation of a Low Temperature Economizer. This represents a 1% improvement in the plant heat rate with an attractive payback period. The components required for this heat recovery sub-system are readily available and the technology has matured to a point where uncertainties are minimized. In addition to improving the operation of the plant, Low Temperature Economizer can reduce emissions of SOx, NOx, Hg, PM and CO2. In a difficult regulatory environment reducing emissions while increasing plant performance is extremely beneficial. Furthermore Low Temperature Economizer lowers the volume of scrubber water required. Cooling the flue gas leaving the air heater below the acid mist dew point is not commonly practiced. The corrosion potential of the condensed sulfuric acid is a major materials selection/maintenance challenge as is the potential for gas-side fouling of the heat exchange surface with fly ash.

Improving the Boiler Efficiency by Optimizing the Combustion Air

2015 ◽  
Vol 787 ◽  
pp. 238-242 ◽  
Author(s):  
R. Pachaiyappan ◽  
J. Dasa Prakash
Keyword(s):  
Heat Transfer ◽  
Water Temperature ◽  
Steam Generator ◽  
Air Temperature ◽  
Flue Gas ◽  
Maximum Heat ◽  
Air Preheater ◽  
Hot Air ◽  
Boiler Efficiency ◽  
Efficient Combustion

Air pre-heater and economizer are heat transfer surfaces in which air temperature and water temperature are raised by transferring heat from other media such as flue gas. Hot air is necessary for rapid combustion in the furnace and also for drying coal in milling plants. So an essential boiler accessory which serves this purpose is air pre-heater. The air pre-heater is not essential for operation of steam generator, but they are used where a study of cost indicates that money can be saved or efficient combustion can be obtained by their use. The decision for its adoption can be made when the financial advantages is weighed against the capital cost of heater. The efficiency of the boiler increases with the increase in the temperature of the combustion air used in the furnace. This is achieved by the increased temperature of the flue gas in the air preheater and economizer zone. This paper deals with the different ways to obtain the maximum heat from the flue gas travelling through the air preheater and the economizer zone to improve the boiler efficiency.

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