Operation characteristics of external heat exchangers in the 600 MW supercritical CFB boiler

Cai, Runxia; Zhang, Man; Mo, X. H.; Lyu, Junfu; Yang, Hairui; Lei, Xiujian; Liu, Wen; Su, Hu; Zhou, Qi

doi:10.1016/j.fuproc.2017.12.006

Cited by 34 publications

(12 citation statements)

References 17 publications

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“…However, the inlet solid flow rate into the EHEX (m·EHEX) can be adjusted by using the cone-valve (CV) of each LS. 4 This allows the steam temperature to be controlled by adjusting the inlet solid flow into the EHEX when used as SH or RH. Therefore, in this section, the dynamic responses of the steam temperature and the heat transfer rates of each component in the CFB loop were simulated by controlling the solid flow rate.…”

Section: Dynamic Responses Of the Steam Temperaturementioning

confidence: 99%

“…In particular, the steam and FUR temperatures can be controlled by adjusting the inlet solid flow rate into the EHEX. 4 In addition, because the supercritical steam flow is designed for once-through operation, its flow and conditions are closely related to the feedwater flow rate as well as the heat generation rate from the fuel combustion. Therefore, the steam temperature varies more directly and sensitively than in the cases of drum boilers in response to changes in the feed water and fuel flow rates.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic simulation study of the steam temperature in a ultra-supercritical circulating fluidized bed boiler system

Kim

Choi

Song

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part A:

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A dynamic simulation of a modern ultra-supercritical circulating fluidized bed (USC-CFB) boiler system was performed using a physics-based model, where the boiler system was composed of an integrated system of heat exchanger (HEX) blocks. In each of the discretized elements of the HEX blocks, supercritical steam flow interacted with the solid–gas flow via heat transfer, and conservation laws, and physical phenomena of the CFB, and the supercritical steam flow was modeled to obtain the flow properties of each material side. By utilizing this model, the dynamic behavior of the main steam temperature, which was selected as the representative performance parameter for achieving safe and fast load changes, was simulated in response to changes applied to the main operating parameters such as the feedwater and fuel flow rates. The dynamic characteristics of the USC-CFB boiler were demonstrated by presenting the temperature responses of the steam and the circulating solid–gas after a step change in the feedwater and fuel flow rates. In the case of a load change, the dynamic response of the steam temperature was quantitatively presented by showing the transient overshoot and undershoot behavior, depending on the selection of the ramp speed when changing the feedwater and fuel flow rates. The steam temperature was also shown to be controlled by manipulating the inlet solid mass flow rate into the final superheater section of the external HEX. The comprehensive set of plant performance data that was generated from the model simulation can be utilized in setting up the operation strategies and/or in determining the control parameters for achieving stable steam temperature behavior during a load change.

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Section: Dynamic Responses Of the Steam Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic simulation study of the steam temperature in a ultra-supercritical circulating fluidized bed boiler system

Kim

Choi

Song

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part A:

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show abstract

“…In the last decade, it has been observed that the diffusion, jointly with the dynamic development of CFB boilers around the world, has led to the increase in capacity of single-unit CFB boilers [1][2][3]. Recently, CFB boiler capacities increased up to 1000 MWe with supercritical and ultra-supercritical working medium parameters [4][5][6][7][8][9]. The fluidized bed technology is very efficient and economically preferable due to the high heat transfer rates that are attained from the fluidized bed to the active heat transfer surface.…”

Section: Introductionmentioning

confidence: 99%

“…It is a result of the limited availability of experimental data for FBHEs in the published literature due to commercial reasons. However, the selected experimental data deal with heat transfer characteristics for large-scale CFB units that are usually presented under different boiler loads only [4,8,12,14,26]. Only a few papers [15,27] discussed the heat transfer between the horizontal tube bundle and the fluidized bed in detail.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Błaszczuk

Jagodzik

2021

Energies

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In the research work, energy transport between a dense fluidized bed and submerged horizontal tube bundle is analyzed in the commercial external heat exchanger (EHE). In order to investigate the heat transfer behavior, the authors carried out eight performance tests in a fluidized bed heat exchange chamber with a cross-section of 2.7 × 2.3 m in depth and width and a height of 1.3 m. The authors have been developing a mechanistic model for the prediction of the average heat transfer coefficient, which includes the effect of the geometric structure of the tube bundle and the location of the heat transfer surface on the heat transfer rate. The computational results depict that the average heat transfer coefficient is essentially affected by superficial gas velocity and suspension density rather than bed particle size. The empirical correlations have been proposed for predicting heat transfer data since the existing literature data is not sufficient for industrial fluidized bed heat exchangers. On the basis of the evaluated operating conditions of an external heat exchanger, the optimal conditions where heat transfer occurs could be deduced. The developed mechanistic heat transfer model is validated by experimental data under the examined conditions.

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“…In fact, the problem of the increased heating surface is a common challenge to large-scale boilers that is being addressed in many ways. − Among them, Lyu et al has put forward an innovative scheme of an annular furnace suitable for 600–1000 MW ultra/ultra-supercritical CFB boilers. For the annular furnace, the addition of an inner ring wall was able to remarkably increase the heating surface, as well as solve the secondary air penetration problems for the large-scale boilers.…”

Section: Introductionmentioning

confidence: 99%

Gas–Solid Hydrodynamics and Combustion Characteristics in a 600 MW Annular CFB Boiler for Supercritical CO₂ Cycles

Cui

Zhong

Liu

et al. 2020

Ind. Eng. Chem. Res.

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The detailed operational performance, gas−solid hydrodynamics, and combustion characteristics in a 600 MW coalfired CFB boiler with a novel annular furnace, which was designed to meet the significant increase in heating surfaces for supercritical carbon dioxide (S-CO 2 ) cycles, were studied in this article. In multiphase particle-in-cell (MP-PIC) simulations, the flow pattern and pressure drop were explored in a wide range of operating gas velocities to determine the suitable operation interval. Within a fastfluidized bed, affected by the increasing fluidization velocity, the voidage and gas−solid velocity obviously increased, indicating good flexibility and adjustability of the annular CFB for varying operating conditions. At the most representative operating velocity, the annular S-CO 2 CFB showed relatively more satisfactory dynamic and combustion characteristics compared with conventional steam CFBs, including a uniform temperature distribution, larger heat flux, and lower pollution emissions, which indicated good heat transfer characteristics of S-CO 2 heating surfaces and higher combustion efficiency.

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Operation characteristics of external heat exchangers in the 600 MW supercritical CFB boiler

Cited by 34 publications

References 17 publications

Dynamic simulation study of the steam temperature in a ultra-supercritical circulating fluidized bed boiler system

Dynamic simulation study of the steam temperature in a ultra-supercritical circulating fluidized bed boiler system

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Gas–Solid Hydrodynamics and Combustion Characteristics in a 600 MW Annular CFB Boiler for Supercritical CO₂ Cycles

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Operation characteristics of external heat exchangers in the 600 MW supercritical CFB boiler

Cited by 34 publications

References 17 publications

Dynamic simulation study of the steam temperature in a ultra-supercritical circulating fluidized bed boiler system

Dynamic simulation study of the steam temperature in a ultra-supercritical circulating fluidized bed boiler system

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Gas–Solid Hydrodynamics and Combustion Characteristics in a 600 MW Annular CFB Boiler for Supercritical CO2 Cycles

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Gas–Solid Hydrodynamics and Combustion Characteristics in a 600 MW Annular CFB Boiler for Supercritical CO₂ Cycles