scholarly journals The Causes Analysis of the Air Preheater and Performance Blocking Evaluation of the Measures on the SCR De-NOx Unit

2019 ◽  
Vol 118 ◽  
pp. 03056
Author(s):  
Su Pan ◽  
Pengfeng Yu ◽  
Linbo Liu ◽  
Jing Han ◽  
Xiao Shen
Keyword(s):  
Flue Gas ◽  
Differential Pressure ◽  
Control Measures ◽  
Gas Temperature ◽  
Air Preheater ◽  
Environment Temperature ◽  
Ammonium Bisulfate ◽  
And Performance ◽  
Exhaust Gas Temperature ◽  
Ammonia Injection

In order to solve the problem of abnormal rise of the differential pressure of the revolving air preheater on 300MW unit, we analysed the causes of abnormal rise of the differential pressure of the air preheater and evaluated performances of control measures, through historical data mining and on-site inspection of the unit. The results show that, with the gradual decrease of environment temperature with the decrease of the exhaust gas temperature, the ashes in flue gas are bound by acid liquid produced by condensation of flue gas, and the adhesion areas of the ammonium bisulfate produced in the denitration process are enlarged. However the original set ash blowing pressure can no longer satisfy the requirements of the air preheater, giving rise to the differential pressure of the air preheater on both sides to rise. The reason of the higher differential pressure of the unilateral air preheater is that the large ammonia injection amount, leading to the increases of ammonia escape of the denitrification system. So the side of the air on preheater ammonium bisulfate type blockage is more serious. After the Measures of Adjusting distribution coefficient of ammonia supply valve on both sides, increasing the dust blowing frequency and pressure of the air preheater, the differential pressure of air preheater on both sides are close to the consistent. The decrease amplitude of the differential pressure of the air preheater on 280MW is about 300-500Pa.

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.

A Novel Design for Reduction of Ammonium Bisulfate Deposition in the Rotary Air Preheater

2018 ◽  
Author(s):  
Yufan Bu ◽  
Limin Wang ◽  
Xiaoyang Wei ◽  
Lei Deng ◽  
Defu Che
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Catalytic Reduction ◽  
Operating Cost ◽  
Reaction Chamber ◽  
Air Preheater ◽  
Accurate Temperature ◽  
Ammonium Bisulfate ◽  
Lower Temperature ◽  
Novel Design

Nitrogen oxide (NOx) emitted from boilers in coal-fired power plant may be reduced by 90 percent through the application of the selective catalytic reduction (SCR). However, the escaped ammonia from the SCR systems could react with sulfur oxides (SOx) in the flue gas to form ammonium bisulfate (ABS) in exhaust systems. The blockage and corrosion caused by ABS seriously impact the rotary air preheater (RAPH), which would not only increase operating cost on ash-blowing and cleaning but also lead to unplanned outage. To solve the problem, in this paper a novel preheater system is proposed. A single preheater is split into two sub-preheaters, between which the main flue gas flow is mixed with the recirculated flue gas from outlet of the lower-temperature preheater. After the mixing point, a reaction chamber and a precipitator are installed. A numerical finite difference method (FDM) is employed to model the RAPH and obtain the accurate temperature distribution of fluid and heat transfer elements. The initial formation temperatures of (NH4)2SO4 and ABS are 200 °C and 170 °C, respectively, according to the flue gas composition in this work. By calculation, this split design of the RAPH is believed to be effective in reducing deposition of ABS.

scholarly journals Application and performance evaluation of desulfurization wastewater spray drying technology

2020 ◽  
Vol 143 ◽  
pp. 02029
Author(s):  
Zhang Shanshan ◽  
Wang Renlei ◽  
Tang Guorui ◽  
Dai YU
Keyword(s):  
Spray Drying ◽  
Flue Gas ◽  
Unit Load ◽  
Air Preheater ◽  
Mass Fractions ◽  
Denitrification Reactor ◽  
And Performance ◽  
Drying Technology ◽  
Gas Volume ◽  
Desulfurization Wastewater

In order to realize zero discharge of desulfurization wastewater, spray drying technology of desulfurization wastewater was used in 2x330MW unit of a power plant. Its principle was to use a rotary atomizer for atomization,and a part of hot flue gas was drawn from the SCR denitrification reactor and air preheater into the drying tower, the heat was used to evaporate the desulfurization wastewater in a spray drying tower. The salt in the waste water was mixed with the dust, which was collected and removed by the electric dust remover. Then the water vapor was mixed with the flue gas and finally enters the desulfurization tower.The field test was carried out under the condition that the unit load was 100% and the amount of desulfurization wastewater treated was 5.1m3/h.The results showed that the hot smoke gas volume of drying tower was about 64896m3/h, The smoke temperature at the inlet and outlet of the drying tower were 335℃ and 205℃ respectively,the moisture content of drying products was only 0.05%. The content of HCl in the flue gas at the inlet and outlet of the drying tower were 55mg/L and 195mg/L respectively, the mass fractions of Cl removal and Cl volatilization in desulfurization wastewater were 87.7% and 12.3% respectively. The increase of Cl content in the dried products had little effect on the utilization of fly ash.

Energy-Saving Analysis of 215MW Cogeneration Boiler Adding Low Temperature Economizer

2013 ◽  
Vol 448-453 ◽  
pp. 2777-2780 ◽  
Author(s):  
Yan Feng Liu ◽  
Shi Ping Li ◽  
Xiang Hong Li
Keyword(s):  
Low Temperature ◽  
Flue Gas ◽  
Waste Heat ◽  
Natural Circulation ◽  
Peak Load ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Bag Filter ◽  
Actual Operation ◽  
Exhaust Gas Temperature

A 215MW cogeneration B&W670/13.7-M type high-pressure natural circulation boilers, the exhaust gas temperature is set as 143 °C, while in the actual operation, the average exhaust gas temperature is 155 °C, and when the unit is running at full capacity in summer the highest exhaust gas temperature is 169.6 °C. In order to satisfy the normal operating temperature of bag filter in summer peak load, and recover low temperature waste heat of fule gas, low temperature economizer is added to the thermal system. Therefore, low-temperature economizers are respectively added in four flues which are between the outlet of the air preheater and the entrance of the bag filter, this will achieve the purpose of reducing flue gas temperature by transferring heat between condensate and flue gas, ensuring the units safe operating and improving the overall operating performance of the boiler.

scholarly journals A Variable-Geometry Combustor Used to Study Primary and Secondary Zone Stoichiometry

1983 ◽  
Author(s):  
Daniel Briehl ◽  
Donald F. Schultz ◽  
Robert C. Ehlers
Keyword(s):  
Operating Conditions ◽  
Fuel Quality ◽  
Variable Geometry ◽  
Gas Temperature ◽  
Reference Velocity ◽  
Primary Zone ◽  
Wide Range ◽  
Secondary Zone ◽  
And Performance ◽  
Exhaust Gas Temperature

A combustion program is underway to evaluate fuel quality effects on gas turbine combustors. A rich-lean variable geometry combustor design was chosen to evaluate fuel quality effects over a wide range of primary and secondary zone equivalence ratios at simulated engine operating conditions. The first task of this effort, was to evaluate the performance of the variable geometry combustor. The combustor incorporates three stations of variable geometry to control primary and secondary zone equivalence ratio and overall pressure loss. Geometry changes could be made while a test was in progress through the use of remote control actuators. The primary zone liner was water cooled to eliminate the concern of liner durability. Emissions and performance data were obtained at simulated engine conditions of 80 percent and full power. Inlet air temperature varied from 611 to 665 K, inlet total pressure varied from 1.02 to 1.24 MPa, reference velocity was 18.0 m/sec and exhaust gas temperature was a constant 1400 K.

scholarly journals Deterioration effects of coupled blisk blades

2018 ◽  
Vol 2 ◽  
pp. CKB8N6 ◽  
Author(s):  
Andreas Kellersmann ◽  
Gerald Reitz ◽  
Jens Friedrichs
Keyword(s):  
Engine Performance ◽  
Aerodynamic Performance ◽  
Gas Temperature ◽  
Key Factors ◽  
Engine Operation ◽  
Geometric Properties ◽  
Safety Standards ◽  
Operation Conditions ◽  
And Performance ◽  
Exhaust Gas Temperature

Performance degradation due to wear of high pressure compressors (HPC) is a major concern in aero-engine operation and maintenance. Among other effects especially erosion of airfoils leads to changed aerodynamic behavior and therefore to deterioration. These affects engine performance parameter like thrust specific fuel consumption (TSFC) and exhaust gas temperature (EGT). Reaching EGT-limit, the engine typically has to be overhauled during a shop visit to restore safety standards and performance. During state of the art shop visits, engines are repaired based on EGT-specifications. To further enhance the maintenance, tailored repairs for each jet engine based on engine history and operation conditions are necessary to take TSFC into account. To ensure such an effective maintenance, the aerodynamic behavior of deteriorated and repaired airfoils is the key factors. Therefore, geometric properties with high influence on aerodynamic performance have to be known. For blisks (BLade-Integrated-diSK) the approach of tailored maintenance will be even more complicated because the airfoil arrangement cannot be changed or individual airfoils cannot be replaced. Thus, the effects of coupled misshaped airfoils have a high significance. This study will present a Design of Experiments (DoE) for circumferential coupled HPC-airfoils to identify the geometric properties which lead to a reduction of performance. To focus on geometric variations, quasi3D (Q3D) simulations are taken out. Based on a sensitivity analysis, the thickness related parameters, the stagger angle as well as the max. profile camber thickness are identified as the most important parameters which are influencing adjacent airfoils and reduce the aerodynamic performance.

Heat Recovery and Burner Modification of an Industrial Tubular Furnace

2015 ◽  
Vol 737 ◽  
pp. 296-300
Author(s):  
Xi Lai Zhang ◽  
Wei Yao
Keyword(s):  
Heat Recovery ◽  
Radiation Heat Transfer ◽  
Exhaust Gas ◽  
Heat Absorption ◽  
Tubular Furnace ◽  
Gas Temperature ◽  
Radiation Heat ◽  
Air Preheater ◽  
Burner Flame ◽  
Exhaust Gas Temperature

The air preheater was installed on the furnace to decrease the exhaust gas temperature and heat the air to about 290°C. A radiant cylinder was added to the radiation section. Swirl flames were formed by adjusting the shape and the installation angles of the burner flame tubes. The radiation heat transfer was strengthened and the heat absorption was enhanced in the radiation section, while the temperature at the outlet of the furnace was decreased. Thus energy was saved by 16.7%.

scholarly journals Experimental Study on Operation Regulation of a Coupled High–Low Energy Flue Gas Waste Heat Recovery System Based on Exhaust Gas Temperature Control

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 706 ◽  
Author(s):  
Jiayou Liu ◽  
Fengzhong Sun
Keyword(s):  
Flue Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Gas Flow ◽  
Waste Heat ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Exhaust Gas Temperature

Controlling the exhaust gas temperature (EGT) of coal–fired boilers at a reasonable value is beneficial to ensuring unit efficiency and preventing acid corrosion and fouling of tail heating surfaces in power plants. To obtain the operation regulation of coupled high–low energy flue gas waste heat recovery system (CWHRS) under a given EGT, experimental equipment was designed and built. Experiments were carried out to maintain the exhaust gas temperature under different flue gas flow, flue gas temperature and air temperature conditions. As the flue gas flows, the flue gas temperatures and air temperatures increased, and the bypass flue gas flow proportions or the water flows of the additional economizer were increased to maintain the EGT at about 85 °C. An improved low temperature economizer (LTE) and front located air heater (FAH) system were put forward. As the flow of the crossover pipe increased, the EGT and the inlet water temperature of the LTE increased. As the flow of the circulating loop increased, the EGT and the inlet water temperature of the LTE decreased. Operation regulations of LTE–FAH system under four cases were given. The operation regulations of CWHRS and LTE–FAH system can provide references for power plant operation.

Linear Transfer Functions Extraction for a Power Generation Three-Shaft Gas Turbine Based on Actual Specifications

2020 ◽  
Vol 234 (14) ◽  
pp. 2781-2802
Author(s):  
Abdollah Mehrpanahi ◽  
Gholamhassan Payganeh ◽  
Mohammadreza Arbabtafti
Keyword(s):  
Gas Turbine ◽  
Transfer Functions ◽  
Moving Average ◽  
Binary Sequence ◽  
Hammerstein Model ◽  
Gas Temperature ◽  
Environment Temperature ◽  
Real Performance ◽  
Industrial Gas Turbine ◽  
Exhaust Gas Temperature

The design and testing of various types of controllers require accurate and reliable transfer functions that are compatible with the performance condition of the system. In this paper, the linear and the nonlinear methods have been utilized for extracting the transfer functions for a three-shaft industrial gas turbine. The main variables are the fuel input and environment temperature, while the main outputs are the LPT exhaust gas temperature and the generated power. According to the nonlinear structure of the system and the input variation intervals, the quasi-amplitude-modulated pseudo random binary sequence signals have been utilized for generating input parameters. Finally, the results extracted from the selected methods were compared to the outputs of real performance data under loading and unloading conditions. Based on the comparison between the accuracies obtained by the results, the auto-regressive moving average with eXogenous, try and error transfer function and linearized Hammerstein model methods are proposed, respectively. The outcome of using the controller indicated higher compatibility from transfer functions as compared to the reference dynamic model.

scholarly journals Hybrid technology of reduction of nitrogen oxides (NOx) in exhaust gases; Part 2 – Numerical model of pilot scale regenerative rotary air heater (RAH) retrofited with selective catalyst reduction (SCR) modules

2019 ◽  
Vol 82 ◽  
pp. 01016 ◽  
Author(s):  
Andrzej Kwiczala ◽  
Robert Wejkowski
Keyword(s):  
Numerical Model ◽  
Flue Gas ◽  
Catalytic Reduction ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Gas Temperature ◽  
Air Heater ◽  
Exhaust Gas Temperature ◽  
Heat Exchange Efficiency ◽  
Flue Gas Denitrification

This article exhibits the results of the analysis performed to verify the effectiveness of the hybrid flue gas denitrification system (herein referred to as HDS) which involved the retrofitting for selective catalytic reduction (SCR) material into a regenerative rotary air heater (RAH). A numerical model corresponding to the actual pilot scale RAH operating conditions was developed. The ultimate intent of the numerical model is to provide a platform where the technology can be implemented on full scale air preheaters. The numerical analysis performed on the pilot scale HDS installation showed a 3% decrease in heat exchange efficiency in the exchanger. This decrease was significantly minimized by the use of blades adjusting the distribution of flue gases entering the RAH. This means that the exhaust gas temperature at the exchanger outlet increased by 4°C, which corresponds to an average of 0.3% increase in the boiler outlet loss. It was also recognized that the air temperature was reduced by 8°C, which does not translate into significant changes in boiler performance parameters. other boiler operating parameters in a noticeable way during operation.

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