Publication detail

Total Site Heat Integration of Mechanical Vapour Recompression Multi-Effect Evaporators for Older Kraft Mills

Walmsley, T.G. Ong, B.H.Y. Atkins, M.J. Klemeš, J.J. Walmsley, M.R.W. Varbanov, P.S.

English title

Total Site Heat Integration of Mechanical Vapour Recompression Multi-Effect Evaporators for Older Kraft Mills

Type

conference paper

Language

en

Original abstract

This paper aims to apply Total Site Heat Integration (TSHI) to appropriately integrate Mechanical and Thermal Vapour Recompression with multi-effect evaporators at older Kraft Mills, to cause a step reduction in fossil fuel use and its associated emissions. Heat and power demands for older Kraft Mills are chiefly satisfied from Recovery Boilers (RB), heavily supplemented by biomass/fossil fuel boilers, and integrated with steam turbines. Prior to firing, black liquor – the RB fuel – is concentrated from about 18 % to 67 % in a multi-effect evaporator, which demands 20 % of site-wide thermal energy. With access to renewable electricity, this study finds that vapour recompression can be economically integrated into a multi-effect evaporator at older Kraft Mills. The vapour recompression configuration with the greatest economic potential used 2-stages of mechanical vapour recompression and 1-stage of thermal vapour recompression. This system achieved a levelised profit of NZD 8.56 M/y, a payback period of 1.0 y and an internal rate of return of 103 %. An optimum integrated set-up needs to account for site-specific heat demand and utility supply profiles through TSHI.

English abstract

This paper aims to apply Total Site Heat Integration (TSHI) to appropriately integrate Mechanical and Thermal Vapour Recompression with multi-effect evaporators at older Kraft Mills, to cause a step reduction in fossil fuel use and its associated emissions. Heat and power demands for older Kraft Mills are chiefly satisfied from Recovery Boilers (RB), heavily supplemented by biomass/fossil fuel boilers, and integrated with steam turbines. Prior to firing, black liquor – the RB fuel – is concentrated from about 18 % to 67 % in a multi-effect evaporator, which demands 20 % of site-wide thermal energy. With access to renewable electricity, this study finds that vapour recompression can be economically integrated into a multi-effect evaporator at older Kraft Mills. The vapour recompression configuration with the greatest economic potential used 2-stages of mechanical vapour recompression and 1-stage of thermal vapour recompression. This system achieved a levelised profit of NZD 8.56 M/y, a payback period of 1.0 y and an internal rate of return of 103 %. An optimum integrated set-up needs to account for site-specific heat demand and utility supply profiles through TSHI.

Keywords in English

Earnings; Evaporators; Fossil fuels; Fuels; Investments; Specific heat; Steam turbines; Economic potentials; Heat integration; Internal rate of return; Multi-effect evaporators; Payback periods; Recovery boilers; Renewable electricity; Vapour recompression; Kraft Mills;

Released

01.10.2017

Publisher

Italian Association of Chemical Engineering - AIDIC

ISBN

978-88-95608-51-8

ISSN

2283-9216

Book

Chemical Engineering Transactions

Number

61

Pages from–to

265–270

Pages count

6

BIBTEX


@inproceedings{BUT146021,
  author="Timothy Gordon {Walmsley} and Jiří {Klemeš} and Petar Sabev {Varbanov},
  title="Total Site Heat Integration of Mechanical Vapour Recompression Multi-Effect Evaporators for Older Kraft Mills",
  booktitle="Chemical Engineering Transactions  ",
  year="2017",
  number="61",
  month="October",
  pages="265--270",
  publisher="Italian Association of Chemical Engineering - AIDIC",
  isbn="978-88-95608-51-8",
  issn="2283-9216"
}