Energy-saving mechanism and parametric analysis of the high back-pressure heating process in a 300 MW coal-fired combined heat and power unit

Heng, Chen; Xiao, Yao; Xu, Gang; Xu, Jie; Yao, Xianhuai; Yang, Yongping

doi:10.1016/j.applthermaleng.2018.12.001

Cited by 50 publications

(28 citation statements)

References 30 publications

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“…where Q 1 is the heat output from AHP, MW; Q 2 is the heat absorbed from circulating water, MW; W is the heat released by driving steam, MW; Q 2 and W can be calculated according to Eq. (17) and (18) respectively.…”

Section: Htrmentioning

confidence: 99%

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Research on Modeling and Deep Peak Regulation Control of a Combined Heat and Power Unit

et al. 2020

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This paper firstly proposes a nonlinear dynamic model of a combined heat and power (CHP) unit with absorption heat pump (AHP) and bypass systems, the unknown parameters are determined based on design data and perturbation test. Simulation results show that the model can reveal the couplings of AHP and bypass systems to the CHP unit, and provide model support for controller design. On the basis of the model, this paper further proposes a deep peak regulation control strategy, in which, the generalized predictive control algorithm with feedforward-feedback structure is adopted to fundamentally solve the control problems of large delay and inertia on the boiler side, and overcome known disturbances on the turbine side; the ratio of the first stage pressure to the exhaust pressure from high pressure cylinder is adopted to control the high pressure bypass. The deep peak regulation process is divided into two stages: 1) CHP and AHP are used for heating when their heating capacity can meet the heat load requirements of residents, 2) as the unit load is further reduced, bypass mode is activated for heating when the steam flow entering the low pressure cylinder is lower than its cooling flow. Simulation results show that the strategy can meet the heat load requirements of residents and ensure the safe and stable operation of the turbine when the unit is in deep peak regulation condition. INDEX TERMS Combined heat and power unit, absorption heat pump, bypass heating, dynamic model, deep peak regulation control.

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Section: Htrmentioning

confidence: 99%

“…The main methods to decouple the constraint of CHP units are absorption heat pump (AHP) [8], [9], bypass [10], electric boiler) [11]- [13], heat storage tank [14], [15], low pressure cylinder (LPC) removal [16], high back pressure [17], etc. This paper mainly study a CHP unit with AHP and bypass systems.…”

Section: Introductionmentioning

confidence: 99%

Research on Modeling and Deep Peak Regulation Control of a Combined Heat and Power Unit

et al. 2020

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“…In addition, the waste heat of the exhaust steam is recovered by the HBP design, and making use of more exhaust steam contributes to a higher energy efficiency of the cogeneration unit [ 28 ]. The recovery efficiency of the exhaust steam (

) is defined as Equation (3), which is another performance indicator of the HBP configuration.…”

Section: System Simulation and Evaluation Criteriamentioning

confidence: 99%

“…Its adoption is encouraged in retrofitting power generation plants into cogeneration by the Chinese government [ 25 ]. The thermodynamic characteristics of the HBP heating system have been explored by several researchers [ 13 , 26 , 27 , 28 ]. However, there is still a massive loss of exergy in a typical HB–CHP unit due to the pressure waste of the extracted heating steam, which must be reduced to further boost unit efficiency.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units

Chen

et al. 2019

Entropy

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High back-pressure (HBP) heating technology has been identified as an effective approach to improve the efficiency of combined heat and power (CHP). In this study, the novel concept of a HBP heating system with energy cascade utilization is developed and its probability examined. In the reformative design, the extracted heating steam from the intermediate-pressure turbine (IPT) is first drawn to an additional turbine where its excess pressure can be converted into electricity, then steam with a lower pressure can be employed to heat the supply water. As a consequence, the exergy destruction in the supply water heating process can be reduced and the efficiency of the cogeneration unit raised. A detailed thermodynamic investigation was performed based on a typical coal-fired HBP–CHP unit incorporating the proposed configuration. The results show that the artificial thermal efficiency (ATE) promotion was as much as 2.01 percentage points, with an additional net power output of 8.4 MW compared to the reference unit. This was attributed to a 14.65 percentage-point increment in the exergy efficiency of the supply water heating process caused by the suggested retrofitting. The influences of the unit power output, unit heat output, supply water and return water temperatures and turbine back pressure on the thermal performance of the modified system are discussed as well. In addition, the economic performance of the new design is assessed, indicating that the proposed concept is financially feasible.

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“…Chen et al [14] proposed a high back pressure heating system combined with the pre-drying of raw coal, in order to improve the performance of cogeneration units. In terms of energy-saving effects, the current research mainly focuses on two aspects: the contribution of cogeneration to reducing greenhouse gas emissions such as carbon dioxide from the macro level [15][16][17] and the analysis of the energy-saving measurement and emission reduction potential of cogeneration units at the micro level [18,19]. Luking [20] calculated the reduction of standard coal consumption before and after technical innovation by evaluating the efficiency of cogeneration units and auxiliary power consumption rate.…”

Section: Introductionmentioning

confidence: 99%

Research on the Economic Benefit Evaluation of Combined Heat and Power (CHP) Technical Renovation Projects Based on the Improved Factor Analysis and Incremental Method in China

Yang

Niu

et al. 2019

Sustainability

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With the increasingly prominent problems of resources and environment, thermal power enterprises in China are facing more severe challenges. To improve energy efficiency, a great number of thermal power enterprises implement the technical renovation of equipment. However, current methods cannot meet the needs of scientific and effective evaluations. In this context, the internal rate of return (IRR) is used as the main index to evaluate the economic benefits of the technical renovation of combined heat and power (CHP) plants. In order to improve the accuracy of the economic benefit evaluation results, the incremental cash flow is calculated through the incremental method, which is based on the existence and non-existence method, and the improved factor analysis method is utilized to eliminate the influence of price factors from markets that have no direct and definite relationship with the technical renovation. Then, the evaluation method is validated by taking a CHP technical renovation project in B city of China as an example. By comparing with other methods, the results show that the IRRs calculated by different methods are quite different, and the difference between the maximum and the minimum can reach 69.95%. The result of the method proposed in this paper is more reasonable and reliable and can effectively evaluate the economic benefits of CHP technical renovation projects.

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Energy-saving mechanism and parametric analysis of the high back-pressure heating process in a 300 MW coal-fired combined heat and power unit

Cited by 50 publications

References 30 publications

Research on Modeling and Deep Peak Regulation Control of a Combined Heat and Power Unit

Research on Modeling and Deep Peak Regulation Control of a Combined Heat and Power Unit

Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units

Research on the Economic Benefit Evaluation of Combined Heat and Power (CHP) Technical Renovation Projects Based on the Improved Factor Analysis and Incremental Method in China

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Energy-saving mechanism and parametric analysis of the high back-pressure heating process in a 300 MW coal-fired combined heat and power unit

Cited by 50 publications

References 30 publications

Research on Modeling and Deep Peak Regulation Control of a Combined Heat and Power Unit

Research on Modeling and Deep Peak Regulation Control of a Combined Heat and Power Unit

Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units

Research on the Economic Benefit Evaluation of Combined Heat and Power (CHP) Technical Renovation Projects Based on the Improved Factor Analysis and Incremental Method in China

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Energy-saving mechanism and parametric analysis of the high back-pressure heating process in a 300 MW coal-fired combined heat and power unit