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Recovery boiler back-end heat recovery

Year of publication

2023

Authors

Saari Jussi; Kaikko Juha; Sermyagina Ekaterina; Hamaguchi Marcelo; Cardoso Marcelo; Vakkilainen Esa; Haider Markus

Abstract

Sustainability and efficient use of resources are becoming increasingly important aspects in the operation of all industries. Recently, some biomass-fired boilers have been equipped with increasingly complex condensing back-end heat recovery solutions, sometimes also using heat pumps to upgrade the low-grade heat. In kraft recovery boilers, however, scrubbers are still mainly for gas cleaning, with only simple heat recovery solutions. In this paper, we use process simulation software to study the potential to improve the power generation and energy efficiency by applying condensing back-end heat recovery on a recovery boiler. Different configurations are considered, including heat pumps. Potential streams to serve as heat sinks are considered and evaluated. Lowering the recovery boiler flue gas temperature to approximately 65°C significantly decreases the flue gas losses. The heat can be recovered as hot water, which is used to partially replace low-pressure (LP) steam, making more steam available for the condensing steam turbine portion for increased power generation. The results indicate that in a simple condensing plant, some 1%•4% additional electricity could be generated. In a Nordic mill that provides district heating, even more additional electricity generation, up to 6%, could be achieved. Provided the availability of sufficient low-temperature heat sinks to use the recovered heat, as well as sufficient condensing turbine swallowing capacity to utilize the LP steam, the use of scrubbing and possibly upgrading the heat using heat pumps appears potentially useful.
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Organizations and authors

LUT University

Sermyagina Ekaterina Orcid -palvelun logo

Vakkilainen Esa Orcid -palvelun logo

Kaikko Juha

Saari Jussi Orcid -palvelun logo

Publication type

Publication format

Article

Parent publication type

Journal

Article type

Original article

Audience

Scientific

Peer-reviewed

Peer-Reviewed

MINEDU's publication type classification code

A1 Journal article (refereed), original research

Publication channel information

Volume

22

Issue

3

Pages

174-183

​Publication forum

68059

​Publication forum level

1

Open access

Open access in the publisher’s service

Yes

Open access of publication channel

Fully open publication channel

Self-archived

No

Other information

Fields of science

Chemical engineering

Keywords

[object Object],[object Object],[object Object]

Internationality of the publisher

International

International co-publication

Yes

Co-publication with a company

Yes

DOI

10.32964/TJ22.3.174

The publication is included in the Ministry of Education and Culture’s Publication data collection

Yes