Comparative Evaluation of Membrane Based Condensate Treatment Systems for Biomass-fired CHP Plants
(2018) KETM05 20181Chemical Engineering (M.Sc.Eng.)
- Abstract
- Biomass-fired combined heat and power (CHP) plants in Sweden are usually equipped with a flue gas condenser, where the flue gas is sprayed with water which absorbs contaminants and makes the flue gas meet emission restrictions. This results in a contaminated condensate that has to be treated to be discharged or re-used in the plant. This can be done in various ways, but at the moment the interest in this area is focused on membrane technology to avoid unnecessary use of chemicals. To be able to draw conclusions on which parameters that affects the flue gas condensate quality, and thus what affects the condensate treatment system in a CHP plant, case studies has been performed on two CHP plants owned by Vattenfall, located in Jordbro... (More)
- Biomass-fired combined heat and power (CHP) plants in Sweden are usually equipped with a flue gas condenser, where the flue gas is sprayed with water which absorbs contaminants and makes the flue gas meet emission restrictions. This results in a contaminated condensate that has to be treated to be discharged or re-used in the plant. This can be done in various ways, but at the moment the interest in this area is focused on membrane technology to avoid unnecessary use of chemicals. To be able to draw conclusions on which parameters that affects the flue gas condensate quality, and thus what affects the condensate treatment system in a CHP plant, case studies has been performed on two CHP plants owned by Vattenfall, located in Jordbro (Stockholm) and Idbäcken (Nyköping).
In this study, both measurement of the content of the process streams in the condensate treatment system at Jordbro, and simulation of the condensate treatment with reverse osmosis (RO) in the softwares Matlab and Winflows, were performed. The condensate treatment system in Jordbro was recently installed and was estimated to meet the presented state-of-the-art performance. The investigation indicated that the old equipment still in operation at Jordbro could be redundant since the treatment in these units did not significantly improve the condensate quality.
The results from the Jordbro RO condensate treatment system were used to investigate how a similar system could be implemented in Idbäcken. The aim was to study if the Idbäcken condensate treatment system could be less chemical dependent, and if the production of condensate that can be re-used in e.g. the district heating network, could be increased. The implementation study was done in Matlab and Winflows, and was considered successful. The simulations indicated that the current treatment units: the ion-exchanger, the softening and NH3 membrane, could be redundant if implementing a RO condensate treatment system similar to the one in Jordbro.
It was also shown that at optimal operating conditions, the inlet concentration does not significantly affect the quality of the purified condensate. It was also indicated that the preceding flue gas cleaning and flue gas condensation set-up affects the condensate quality more than the level of contaminants in the incinerated fuel in a CHP plant. (Less) - Popular Abstract
- Reduced Environmental Impact of Flue Gases Through Membrane Technology:
Heat and electricity are generated in a net-CO2 neutral way in biomass- fired combined heat and power (CHP) plants. Contaminants in the flue gas are absorbed in water, the flue gas condensate, which can be purified and re- used, if treated with membrane technology.
Biomass is used as fuel to generate heat for the production of high quality steam for electricity generation in the CHP plants studied in this work. The combusted biomass also results in a high temperature flue gas which is net-CO2 neutral due to the renewable energy source, but contains contaminants that are restricted to be emitted from the process. To make sure that the quality of the flue gas... (More) - Reduced Environmental Impact of Flue Gases Through Membrane Technology:
Heat and electricity are generated in a net-CO2 neutral way in biomass- fired combined heat and power (CHP) plants. Contaminants in the flue gas are absorbed in water, the flue gas condensate, which can be purified and re- used, if treated with membrane technology.
Biomass is used as fuel to generate heat for the production of high quality steam for electricity generation in the CHP plants studied in this work. The combusted biomass also results in a high temperature flue gas which is net-CO2 neutral due to the renewable energy source, but contains contaminants that are restricted to be emitted from the process. To make sure that the quality of the flue gas meets the restrictions, the flue gas is treated in different stages.
The final flue gas treatment before emission is called flue gas condensation (FGC). This means that water is sprayed on the flue gas to absorb the contaminants and thereby form a hot condensate that can be heat exchanged to the district heating network. The flue gas is thus cleaned with the FGC technique but the unwanted contaminants, such as salts (sodium chloride), heavy metals and ammonia, are transferred to the condensate. To be able to re-use the formed condensate, the condensate has to be treated.
The treatment of the condensate can be done in various ways but at the moment the interest in this area is focused on membrane technology, to avoid unnecessary use of chemicals. The membrane technology can be described as that the condensate is pumped through a semipermeable membrane creating one purified stream that has gone through the membrane and one stream containing the retained contaminants. Solutes as small as salts can be retained, depending on the membrane.
Two CHP facilities owned by Vattenfall were studied, one in Jordbro (Stockholm) and one in Idbäcken (Nyköping). The Jordbro plant has recently updated their FGC equipment and installed a membrane based condensate treatment system which needed to be evaluated. The Idbäcken plant operates an older FGC set-up and has a condensate treatment system consuming a considerable amount of chemicals and discharges condensate continuously to a recipient. The aim of the project was therefore to investigate the performance of the recently installed condensate treatment system in Jordbro and then to give suggestions to Idbäcken on how to develop their condensate treatment to a similar set-up. This was to reduce the chemical usage and increase the re-usage of the condensate in Idbäcken. The impact that flue gas treatment has on the condensate quality was also estimated.
By an experimental investigation in Jordbro, the condensate treatment was considered as living up to standards and it was indicated that the old equipment still in operation could be redundant since these units did not improve the condensate quality significantly. The Jordbro condensate treatment system was successfully implemented in Idbäcken through simulations in the computer softwares Matlab and Winflows. It was shown that, in addition to that more purified condensate could be produced, that some of the currently operating unit operations in Idbäcken could be considered as redundant for the process. On an overall perspective, the study thereby showed that the inlet condensate quality did not significantly affect the performance of the membrane process and that the flue gas treatment has a larger impact on the formed FGC condensate than the level of contaminants in the combusted fuel. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/8950795
- author
- Kylhammar, Klara LU
- supervisor
- organization
- course
- KETM05 20181
- year
- 2018
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- CHP Plants, Flue Gas Condensation, Membrane Technology, Condensate Treatment, Reverse Osmosis, Matlab, Winflows, Chemical engineering, Kemiteknik
- language
- English
- id
- 8950795
- date added to LUP
- 2018-06-21 10:46:51
- date last changed
- 2018-06-21 10:46:51
@misc{8950795,
abstract = {{Biomass-fired combined heat and power (CHP) plants in Sweden are usually equipped with a flue gas condenser, where the flue gas is sprayed with water which absorbs contaminants and makes the flue gas meet emission restrictions. This results in a contaminated condensate that has to be treated to be discharged or re-used in the plant. This can be done in various ways, but at the moment the interest in this area is focused on membrane technology to avoid unnecessary use of chemicals. To be able to draw conclusions on which parameters that affects the flue gas condensate quality, and thus what affects the condensate treatment system in a CHP plant, case studies has been performed on two CHP plants owned by Vattenfall, located in Jordbro (Stockholm) and Idbäcken (Nyköping).
In this study, both measurement of the content of the process streams in the condensate treatment system at Jordbro, and simulation of the condensate treatment with reverse osmosis (RO) in the softwares Matlab and Winflows, were performed. The condensate treatment system in Jordbro was recently installed and was estimated to meet the presented state-of-the-art performance. The investigation indicated that the old equipment still in operation at Jordbro could be redundant since the treatment in these units did not significantly improve the condensate quality.
The results from the Jordbro RO condensate treatment system were used to investigate how a similar system could be implemented in Idbäcken. The aim was to study if the Idbäcken condensate treatment system could be less chemical dependent, and if the production of condensate that can be re-used in e.g. the district heating network, could be increased. The implementation study was done in Matlab and Winflows, and was considered successful. The simulations indicated that the current treatment units: the ion-exchanger, the softening and NH3 membrane, could be redundant if implementing a RO condensate treatment system similar to the one in Jordbro.
It was also shown that at optimal operating conditions, the inlet concentration does not significantly affect the quality of the purified condensate. It was also indicated that the preceding flue gas cleaning and flue gas condensation set-up affects the condensate quality more than the level of contaminants in the incinerated fuel in a CHP plant.}},
author = {{Kylhammar, Klara}},
language = {{eng}},
note = {{Student Paper}},
title = {{Comparative Evaluation of Membrane Based Condensate Treatment Systems for Biomass-fired CHP Plants}},
year = {{2018}},
}