scholarly journals Experimental Study on a Flue Gas Waste Heat Cascade Recovery System under Variable Working Conditions

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 324
Author(s):  
Jiayou Liu ◽  
Xiaoyun Gong ◽  
Wenhua Zhang ◽  
Fengzhong Sun ◽  
Qingbiao Wang
Keyword(s):  
Working Conditions ◽  
Air Temperature ◽  
Flue Gas ◽  
Power Plants ◽  
Waste Heat ◽  
Inlet Temperature ◽  
Performance Parameters ◽  
Gas Temperature ◽  
Recovery System ◽  
Gas Ratio

Recovering flue gas waste heat is beneficial to improving the unit efficiency in power plants. To obtain the change rules of performance parameters of a flue gas waste heat cascade recovery system (FWCRS) under variable working conditions, an experiment bench was designed and built. The variation laws of the inlet temperature and exhaust flue gas temperature of a low temperature economizer (LTE), the inlet and outlet air temperature of an air preheater (AP), the heat exchange quantities of the AP, LTE, and front-located air heater and an additional economizer (AE), as well as the waste heat recovery efficiency, the system exergy efficiency, and the energy grade replacement coefficient were obtained as the flue gas flow, flue gas temperature, bypass flue gas ratio, air temperature, and circulating water flow in AE changed. Using an orthogonal test, the flue gas temperature, bypass flue gas ratio and air temperature were proved to be the significant factors affecting the performance parameters of FWCRS, and the bypass flue gas ratio was suggested as an adjusting parameter of FWCRS under variable working conditions.

scholarly journals Performance improvement of a 330MWe power plant by flue gas heat recovery system

2016 ◽  
Vol 20 (1) ◽  
pp. 303-314
Author(s):  
Changchun Xu ◽  
Min Xu ◽  
Ming Zhao ◽  
Junyu Liang ◽  
Juncong Sai ◽  
...  
Keyword(s):  
High Pressure ◽  
Power Plant ◽  
Flue Gas ◽  
Power Output ◽  
Heat Recovery ◽  
Waste Heat ◽  
Gas Temperature ◽  
Recovery System ◽  
Heat Recovery System ◽  
Plant Efficiency

In a utility boiler, the most heat loss is from the exhaust flue gas. In order to reduce the exhaust flue gas temperature and further boost the plant efficiency, an improved indirect flue gas heat recovery system and an additional economizer system are proposed. The waste heat of flue gas is used for high-pressure condensate regeneration heating. This reduces high pressure steam extraction from steam turbine and more power is generated. The waste heat recovery of flue gas decreases coal consumption. Other approaches for heat recovery of flue gas, direct utilization of flue gas energy and indirect flue gas heat recovery system, are also considered in this work. The proposed systems coupled with a reference 330MWe power plant are simulated using equivalent enthalpy drop method. The results show that the additional economizer scheme has the best performance. When the exhaust flue gas temperature decreases from 153? to 123?, power output increases by 6.37MWe and increment in plant efficiency is about 1.89%. For the improved indirect flue gas heat recovery system, power output increases by 5.68MWe and the increment in plant efficiency is 1.69%.

A Novel Flue Gas Heat Recovery System Integrated With Air Preheating in a Utility Boiler

2013 ◽  
Author(s):  
Cheng Xu ◽  
Gang Xu ◽  
Luyao Zhou ◽  
Yongping Yang ◽  
Yuanyuan Li ◽  
...  
Keyword(s):  
Flue Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Energy Savings ◽  
Waste Heat ◽  
The Novel ◽  
Air Preheater ◽  
Recovery System ◽  
Condensed Water

Exhaust gas temperature in coal-fired power plants can reach approximately 120 °C to 140 °C, with the thermal energy accounting for approximately 3% to 8% of the total input energy. Therefore, the heat recovery of exhaust flue gas can improve the thermal efficiency of coal-fired power plants. Currently, the waste heat of flue gas can be recovered by installing an extra heat exchanger, also called low-temperature economizer (LTE), at the end of the boiler flue to heat a part of the condensed water. Extra work can then be obtained by saving the extracted steam and using it to heat the condensed water. However, the temperature of exhaust flue gas is only about 130 °C, which causes the flue gas to heat only the condensed water in the #7 and #8 regenerative heaters. Thus, the energy savings are inconspicuous. This paper proposes a novel flue gas heat recovery system to dramatically increase the temperature of flue gas in the LTE by comprehensive optimization of the air preheater and the LTE. A low-temperature (LT) air preheater can be installed after the LTE in the novel system so that the flue gas can be divided into two parts to heat the air. Simultaneously, the LTE can be installed between the two air preheaters, causing the temperature of flue gas in the LTE to reach above 170 °C. Hence, the temperature of condensed water in the LTE can be increased significantly. In addition, the LTE can replace the high-pressure extracted steam from the turbine, resulting in better energy savings. We also conduct case studies based on a typical 1,000 MW supercritical power generation unit in China. The results indicate better performance of the novel system, with a decrease in exergy loss and improvement in heat transfer characteristics. The reduction in standard coal equivalent of the novel system can reach 3.31g/kWh, nearly 2.4 times that of the system that uses conventional waste heat recovery. Our achievements provide a promising waste heat recovery methods of the utility boiler flue gas.

scholarly journals Node Temperature of the Coupled High-Low Energy Grade Flus Gas Waste Heat Recovery System

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 248 ◽  
Author(s):  
Jiayou Liu ◽  
Fengzhong Sun
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Waste Heat ◽  
Low Energy ◽  
Gas Temperature ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Optimal Node ◽  
Exergy Balance

Coupled high-low energy grade flus gas waste heat recovery systems (CWHRS) have been applied in power plants to improve unit efficiency. In this study, to evaluate the rationality of waste heat recovery, the energy-grade balance coefficient (EBC) of the CWHRS was derived using the theory of heat balance, exergy balance and energy grade balance. The inlet flue gas temperature (IFT) of the low-temperature economizer was defined as the node temperature of the CWHRS. The optimal node temperature (ONT) was optimal when the absolute value of the EBC was the smallest. The exergy efficiency and EBC of the system installed on a supercritical 600 MW unit were calculated and the result shows that the ONT of the system was about 115 °C, the ONT decreased from about 135 °C to about 113 °C when the IFT increased from 335 °C to 380 °C and the ONT decreased from about 144 °C to about 113 °C when the inlet air temperature increased from −10 °C to 35 °C. The node temperature is recommended as an adjusting parameter of CWHRS to ensure the effect of waste heat recovery.

scholarly journals Waste Heat and Water Recovery System Optimization for Flue Gas in Thermal Power Plants

2019 ◽  
Vol 11 (7) ◽  
pp. 1881 ◽  
Author(s):  
Syed Shamsi ◽  
Assmelash Negash ◽  
Gyu Cho ◽  
Young Kim
Keyword(s):  
Ambient Temperature ◽  
Flue Gas ◽  
Power Plants ◽  
Waste Heat ◽  
System Optimization ◽  
Dew Point ◽  
Working Fluid ◽  
Water Yield ◽  
Water Recovery ◽  
Recovery System

Fossil-fueled power plants present a problem of significant water consumption, carbon dioxide emissions, and environmental pollution. Several techniques have been developed to utilize flue gas, which can help solve these problems. Among these, the ones focusing on energy extraction beyond the dew point of the moisture present within the flue gas are quite attractive. In this study, a novel waste heat and water recovery system (WHWRS) composed of an organic Rankine cycle (ORC) and cooling cycles using singular working fluid accompanied by phase change was proposed and optimized for maximum power output. Furthermore, WHWRS configurations were analyzed for fixed water yield and fixed ambient temperature, covering possible trade-off scenarios between power loss and the number of stages as per desired yields of water recovery at ambient temperatures in a practical range. For a 600 MW power plant with 16% water vapor volume in flue gas at 150 °C, the WHWRS can produce 4–6 MWe while recovering 50% water by cooling the flue gas to 40 °C at an ambient temperature of 20 °C. Pragmatic results and design flexibility, while utilizing single working fluid, makes this proposed system a desirable candidate for practical application.

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.

A novel flue gas waste heat recovery system for coal-fired ultra-supercritical power plants

2014 ◽  
Vol 67 (1-2) ◽  
pp. 240-249 ◽  
Author(s):  
Gang Xu ◽  
Cheng Xu ◽  
Yongping Yang ◽  
Yaxiong Fang ◽  
Yuanyuan Li ◽  
...  
Keyword(s):  
Flue Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Waste Heat ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Heat Recovery System

scholarly journals Modification and Application of Low and Low Temperature Economizer in Dezhou Power Plant

2021 ◽  
Vol 271 ◽  
pp. 01022
Author(s):  
Qiudong Hu
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
Flue Gas ◽  
Power Plants ◽  
Waste Heat ◽  
National Policy ◽  
Dust Removal ◽  
Gas Temperature ◽  
Coal Consumption ◽  
Waste Heat Recovery System

At present, the exhaust gas temperature of coal-fired power plants is 125-150℃, and the emission of high-temperature flue gas causes the loss of excess heat and wastes. For this kind of phenomenon, the waste heat recovery system is researched and designed, combined with the combination of a low-temperature economizer in a coal-fired power plant in Dezhou. The heater, through the low-temperature economizer combined with the heater system, reduces coal consumption for power generation, reduces flue gas emissions, while reducing dust specific resistance, improving dust removal efficiency of electric dust removal, and reducing dust emissions. This project responds to national policy guidelines.

Coupled High-Low Energy Level Flue Gas Heat Recovery System and its Application in 1000MW Ultra-Supercritical Double Reheat Coal-Fired Unit

2017 ◽  
Author(s):  
Jiayou Liu ◽  
Fengzhong Sun ◽  
Wei Wei ◽  
Lei Ma
Keyword(s):  
Power Plant ◽  
Energy Level ◽  
Flue Gas ◽  
Heat Recovery ◽  
Waste Heat ◽  
Low Energy ◽  
Gas Temperature ◽  
Coal Consumption ◽  
Recovery System ◽  
Heat Recovery System

Recovering the waste heat of flue gas to reduce its temperature with avoiding low-temperature corrosion is an effective way to improve the economic efficiency of coal-fired power plant. A coupled high-low energy level flue gas heat recovery system was introduced in the paper. The inlet air temperature of air preheater and the temperature of turbine condensate can be increased by using this system. Thermal economy model of the system was built based on equivalent heat drop method. The system was successfully applied in 1000MW ultra-supercritical double reheat coal-fired unit in Laiwu Power Plant of China Huaneng Group, and the operation data showed the boiler flue gas temperature was not higher than 90° C, and the coal consumption was reduced by using the system. (CSPE)

A novel lignite pre-drying system integrated with flue gas waste heat recovery at lignite-fired power plants

2019 ◽  
Vol 150 ◽  
pp. 200-209 ◽  
Author(s):  
Min Yan ◽  
Chunyuan Ma ◽  
Qiuwan Shen ◽  
Zhanlong Song ◽  
Jingcai Chang
Keyword(s):  
Flue Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Waste Heat ◽  
Drying System

Feasibility Study of a Supercritical Cycle as a Waste Heat Recovery System

2013 ◽  
Author(s):  
Antonio Agresta ◽  
Antonella Ingenito ◽  
Roberto Andriani ◽  
Fausto Gamma
Keyword(s):  
Power Systems ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Energy Savings ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Organic Fluids

Following the increasing interest of aero-naval industry to design and build systems that might provide fuel and energy savings, this study wants to point out the possibility to produce an increase in the power output from the prime mover propulsion systems of aircrafts. The complexity of using steam heat recovery systems, as well as the lower expected cycle efficiencies, temperature limitations, toxicity, material compatibilities, and/or costs of organic fluids in Rankine cycle power systems, precludes their consideration as a solution to power improvement for this application in turboprop engines. The power improvement system must also comply with the space constraints inherent with onboard power plants, as well as the interest to be economical with respect to the cost of the power recovery system compared to the fuel that can be saved per flight exercise. A waste heat recovery application of the CO2 supercritical cycle will culminate in the sizing of the major components.

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