The Innovative Design of Air Caps for Improving the Thermal Efficiency of CFB Boilers

Xiaozhou Liu; Guangyu   Zhu; Taimoor Asim; Yu Zhang; Rakesh Mishra

doi:10.1016/j.energy.2021.119844

The Innovative Design of Air Caps for Improving the Thermal Efficiency of CFB Boilers

Xiaozhou Liu, Guangyu Zhu, Taimoor Asim, Yu Zhang, Rakesh Mishra

Research output: Contribution to journal › Article › peer-review

9 Citations (Scopus)

Abstract

Air caps are an effective way of ensuring uniformity of air flow in Circulating Fluidized Bed (CFB) boilers. Published literature on the design and configuration of these air caps is severely limited. In this study, extensive theoretical as well as experimental investigations have been carried out to design novel air caps in order to improve efficiency of CFB boilers. A small-scale test bench of 220 t/h CFB boiler has been developed, integrated with novel air caps. It has been observed that inhomogeneity in air flow velocity decreases from 65.79% to 21.25%, while the pressure drop decreases by 20%. A mathematic model of air caps has been derived and its accuracy verified through cold tests. Two empirical correlations for calculating the pressure drop and the air jet penetration length of the novel air caps have been obtained and verified. Finally, in order to validate the innovative design of air caps, this methodology has been implemented to a full-scale 220 t/h CFB boiler. The hot test results depict that the thermal efficiency of the boiler has increased from 86.4% to 91.8% when tested with the novel air caps in-place, which is equivalent to a saving of 6000 tons of coal per year.

Original language	English
Article number	119844
Number of pages	11
Journal	Energy
Volume	221
Early online date	16 Jan 2021
DOIs	https://doi.org/10.1016/j.energy.2021.119844
Publication status	Published - 15 Apr 2021

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title = "The Innovative Design of Air Caps for Improving the Thermal Efficiency of CFB Boilers",

abstract = "Air caps are an effective way of ensuring uniformity of air flow in Circulating Fluidized Bed (CFB) boilers. Published literature on the design and configuration of these air caps is severely limited. In this study, extensive theoretical as well as experimental investigations have been carried out to design novel air caps in order to improve efficiency of CFB boilers. A small-scale test bench of 220 t/h CFB boiler has been developed, integrated with novel air caps. It has been observed that inhomogeneity in air flow velocity decreases from 65.79% to 21.25%, while the pressure drop decreases by 20%. A mathematic model of air caps has been derived and its accuracy verified through cold tests. Two empirical correlations for calculating the pressure drop and the air jet penetration length of the novel air caps have been obtained and verified. Finally, in order to validate the innovative design of air caps, this methodology has been implemented to a full-scale 220 t/h CFB boiler. The hot test results depict that the thermal efficiency of the boiler has increased from 86.4% to 91.8% when tested with the novel air caps in-place, which is equivalent to a saving of 6000 tons of coal per year.",

keywords = "Circulating Fluidized Bed (CFB), Flow uniformity, Mathematical model, Velocity distribution, Hot test, Error analysis, Circulating fluidized bed (CFB), Mathematic model",

author = "Xiaozhou Liu and Guangyu Zhu and Taimoor Asim and Yu Zhang and Rakesh Mishra",

note = "Funding Information: This work is supported by the Scientific and Technological Plan of Guangdong Province (No. 2017A040405049 ). Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd Copyright: Copyright 2021 Elsevier B.V., All rights reserved.",

year = "2021",

month = apr,

day = "15",

doi = "10.1016/j.energy.2021.119844",

language = "English",

volume = "221",

journal = "Energy",

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T1 - The Innovative Design of Air Caps for Improving the Thermal Efficiency of CFB Boilers

AU - Liu, Xiaozhou

AU - Zhu, Guangyu

AU - Asim, Taimoor

AU - Zhang, Yu

AU - Mishra, Rakesh

N1 - Funding Information: This work is supported by the Scientific and Technological Plan of Guangdong Province (No. 2017A040405049 ). Publisher Copyright: © 2021 Elsevier Ltd Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/4/15

Y1 - 2021/4/15

N2 - Air caps are an effective way of ensuring uniformity of air flow in Circulating Fluidized Bed (CFB) boilers. Published literature on the design and configuration of these air caps is severely limited. In this study, extensive theoretical as well as experimental investigations have been carried out to design novel air caps in order to improve efficiency of CFB boilers. A small-scale test bench of 220 t/h CFB boiler has been developed, integrated with novel air caps. It has been observed that inhomogeneity in air flow velocity decreases from 65.79% to 21.25%, while the pressure drop decreases by 20%. A mathematic model of air caps has been derived and its accuracy verified through cold tests. Two empirical correlations for calculating the pressure drop and the air jet penetration length of the novel air caps have been obtained and verified. Finally, in order to validate the innovative design of air caps, this methodology has been implemented to a full-scale 220 t/h CFB boiler. The hot test results depict that the thermal efficiency of the boiler has increased from 86.4% to 91.8% when tested with the novel air caps in-place, which is equivalent to a saving of 6000 tons of coal per year.

AB - Air caps are an effective way of ensuring uniformity of air flow in Circulating Fluidized Bed (CFB) boilers. Published literature on the design and configuration of these air caps is severely limited. In this study, extensive theoretical as well as experimental investigations have been carried out to design novel air caps in order to improve efficiency of CFB boilers. A small-scale test bench of 220 t/h CFB boiler has been developed, integrated with novel air caps. It has been observed that inhomogeneity in air flow velocity decreases from 65.79% to 21.25%, while the pressure drop decreases by 20%. A mathematic model of air caps has been derived and its accuracy verified through cold tests. Two empirical correlations for calculating the pressure drop and the air jet penetration length of the novel air caps have been obtained and verified. Finally, in order to validate the innovative design of air caps, this methodology has been implemented to a full-scale 220 t/h CFB boiler. The hot test results depict that the thermal efficiency of the boiler has increased from 86.4% to 91.8% when tested with the novel air caps in-place, which is equivalent to a saving of 6000 tons of coal per year.

KW - Circulating Fluidized Bed (CFB)

KW - Flow uniformity

KW - Mathematical model

KW - Velocity distribution

KW - Hot test

KW - Error analysis

KW - Circulating fluidized bed (CFB)

KW - Mathematic model

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ER -

The Innovative Design of Air Caps for Improving the Thermal Efficiency of CFB Boilers

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