scholarly journals Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2487 ◽  
Author(s):  
Heng Chen ◽  
Zhen Qi ◽  
Qiao Chen ◽  
Yunyun Wu ◽  
Gang Xu ◽  
...  
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Waste Heat ◽  
Heating System ◽  
Combined Heat And Power ◽  
Back Pressure ◽  
Coal Consumption ◽  
Heating Capacity ◽  
Boiler Efficiency ◽  
Saving Effect

A conceptual high-back pressure (HBP) heating system cooperating raw coal pre-drying for combined heat and power (CHP) was proposed to improve the performance of the HBP-CHP unit. In the new design, besides of heating the supply-water of the heating network, a portion of the exhaust steam from the turbine is employed to desiccate the raw coal prior to the coal pulverizer, which further recovers the waste heat of the exhaust steam and contributes to raising the overall efficiency of the unit. Thermodynamic and economic analyzes were conducted based on a typical 300 MW coal-fired HBP-CHP unit with the application of the modified configuration. The results showed that the power generation thermal efficiency promotion of the unit reaches 1.7% (absolute value) owing to suggested retrofitting, and meanwhile, the power generation standard coal consumption rate is diminished by 5.8 g/kWh. Due to the raw coal pre-drying, the energy loss of the exhaust flue gas of the boiler is reduced by 19.1% and the boiler efficiency increases from 92.7% to 95.4%. The impacts of the water content of the dried coal and the unit heating capacity on the energy-saving effect of the new concept were also examined.

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 Cascade Utilization of Flue Gas Waste Heat in Combined Heat and Power System with high Back-pressure (CHP-HBP)

2016 ◽  
Vol 104 ◽  
pp. 27-31 ◽  
Author(s):  
Shifei Zhao ◽  
Xiaoze Du ◽  
Zhihua Ge ◽  
Yongping Yang
Keyword(s):  
Power System ◽  
Flue Gas ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Back Pressure

scholarly journals Energy and Exergy Evaluations of a Combined Heat and Power System with a High Back-Pressure Turbine under Full Operating Conditions

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4484 ◽  
Author(s):  
Shifei Zhao ◽  
Weishu Wang ◽  
Zhihua Ge
Keyword(s):  
Power Systems ◽  
Power System ◽  
Evaluation Method ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Back Pressure ◽  
Operating Conditions ◽  
Pressure System ◽  
Heating Capacity ◽  
Energy And Exergy

High back-pressure technology is a promising method for the waste heat recovery of exhaust steams in combined heat and power systems. In this research, a 300 MW coal-fired subcritical combined heat and power system was selected as the reference system, and modeled in EBSILON professional. Then, energy-based and exergy-based performances of the high back-pressure system and traditional combined heat and power system were compared under full operating conditions. Moreover, a novel exergy-based evaluation method, which considers the energy level of the heating supply, was proposed and applied to evaluate the two systems. Results show that: In design conditions, both the heating capacity and power output of the high back-pressure system were higher than those of the extraction condensing system, which led to 17.67% and 33.21% increments of the gross thermal efficiency and generation efficiency, respectively. Compared with the extraction condensing system, the exergy efficiencies of the high back-pressure system were 7.04–8.21% higher. According to the novel exergy-based evaluation, the exergy efficiencies for the generation of the high back-pressure system and extraction condensing system were 46.48% and 41.22%, respectively. This paper provides references for the thermodynamic performance evaluation of the combined heat and power system.

scholarly journals Sensitivity Analysis and Optimization of Operating Parameters of an Oxyfuel Combustion Power Generation System Based on Single-Factor and Orthogonal Design Methods

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 998
Author(s):  
Zhiyu Zhang ◽  
Rongrong Zhai ◽  
Xinwei Wang ◽  
Yongping Yang
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Consumption Rate ◽  
Orthogonal Design ◽  
Excess Oxygen ◽  
Operating Parameters ◽  
Generation System ◽  
Coal Consumption ◽  
Oxygen Coefficient ◽  
Power Generation System

The main purpose of this paper is to quantitatively analyze the sensitivity of operating parameters of the system to the thermodynamic performance of an oxyfuel combustion (OC) power generation system. Therefore, the thermodynamic model of a 600 MW subcritical OC power generation system with semi-dry flue gas recirculation was established. Two energy consumption indexes of the system were selected, process simulation was adopted, and orthogonal design, range analysis, and variance analysis were used for the first time on the basis of single-factor analysis to conduct a comprehensive sensitivity analysis and optimization research on the changes of four operating parameters. The results show that with increasing oxygen purity, the net standard coal consumption rate first decreases and then increases. With decreasing oxygen concentration, the recirculation rate of dry flue gas in boiler flue gas ( χ 1 ) and an increasing excess oxygen coefficient, the net standard coal consumption rate increases. The net electrical efficiency was just the opposite. The sensitivity order of two factors for four indexes is obtained: the excess oxygen coefficient was the main factor that affects the net standard coal consumption rate and the net electrical efficiency. The influence of oxygen concentration and oxygen purity was lower than that of excess oxygen coefficient, and χ 1 has almost no effect.

Thermodynamic and Performance Study of Solar Regenerative Organic Rankine Cycle System for Use in Residential Micro-Combined Heat and Power Generation

2019 ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev
Keyword(s):  
Power Generation ◽  
Energy Demand ◽  
Waste Heat ◽  
Residential Buildings ◽  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Heat And Power ◽  
Energy Sources ◽  
Performance Study

Abstract A continued increase in both energy demand and greenhouse gas emissions (GHGs) call for utilising energy sources effectively. In comparison with traditional energy set-ups, micro-combined heat and power (micro-CHP) generation is viewed as an effective alternative; the aforementioned system’s definite electrical and thermal generation may be attributed to an augmented energy efficiency, decreased capacity as well as GHGs percentage. In this regard, organic Rankine cycle (ORC) has gained increasing recognition as a system, which is capable for generating electrical power from solar-based, waste heat, or thermal energy sources of a lower quality, for instance, below 120 °C. This study focuses on investigating a solar-based micro-CHP system’s performance for use in residential buildings through utilising a regenerative ORC. The analysis will focus on modelling and simulation as well as optimisation of operating condition of several working fluids (WFs) in ORC in order to use a heat source with low-temperature derived from solar thermal collectors for both heat and power generation. A parametric study has been carried out in detail for analysing the effects of different WFs at varying temperatures and flowrates from hot and cold sources on system performance. Significant changes were revealed in the study’s outcomes regarding performance including efficiency as well as power obtained from the expander and generator, taking into account the different temperatures of hot and cold sources for each WF. Work extraction carried out by the expander and electrical power had a range suitable for residential building applications; this range was 0.5–5 kWe with up to 60% electrical isentropic efficiency and up to 8% cycle efficiency for 50–120 °C temperature from a hot source. The operation of WFs will occur in the hot source temperature range, allowing the usage of either solar flat plate or evacuated tube collectors.

scholarly journals Thermodynamic and Exergoeconomic Analysis of a Supercritical CO2 Cycle Integrated with a LiBr-H2O Absorption Heat Pump for Combined Heat and Power Generation

2020 ◽  
Vol 10 (1) ◽  
pp. 323 ◽  
Author(s):  
Yi Yang ◽  
Zihua Wang ◽  
Qingya Ma ◽  
Yongquan Lai ◽  
Jiangfeng Wang ◽  
...  
Keyword(s):  
Heat Pump ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Unit Cost ◽  
Heating System ◽  
Combined Heat And Power ◽  
Economic Benefits ◽  
Ammonia Water ◽  
Absorption Heat Pump ◽  
Comparison Results

In this paper, a novel combined heat and power (CHP) system is proposed in which the waste heat from a supercritical CO2 recompression Brayton cycle (sCO2) is recovered by a LiBr-H2O absorption heat pump (AHP). Thermodynamic and exergoeconomic models are established on the basis of the mass, energy, and cost balance equations. The proposed sCO2/LiBr-H2O AHP system is examined and compared with a stand-alone sCO2 system, a sCO2/DH system (sCO2/direct heating system), and a sCO2/ammonia-water AHP system from the viewpoints of energy, exergy, and exergoeconomics. Parametric studies are performed to reveal the influences of decision variables on the performances of these systems, and the particle swarm optimization (PSO) algorithm is utilized to optimize the system performances. Results show that the sCO2/LiBr-H2O AHP system can obtain an improvement of 13.39% in exergy efficiency and a reduction of 8.66% in total product unit cost compared with the stand-alone sCO2 system. In addition, the sCO2/LiBr-H2O AHP system performs better than sCO2/DH system and sCO2/ammonia-water AHP system do, indicating that the LiBr-H2O AHP is a preferable bottoming cycle for heat production. The detailed parametric analysis, optimization, and comparison results may provide some references in the design and operation of sCO2/AHP system to save energy consumption and provide considerable economic benefits.

Targeting and design of industrial zone waste heat reuse for combined heat and power generation

Energy ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 302-313 ◽  
Author(s):  
Vladimir Z. Stijepovic ◽  
Patrick Linke ◽  
Mirko Z. Stijepovic ◽  
Mirjana Lj. Kijevčanin ◽  
Slobodan Šerbanović
Keyword(s):  
Power Generation ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Industrial Zone ◽  
Waste Heat Reuse
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