You need JavaScript to view this

Chemical and mechanical control of corrosion product transport

Abstract

The corrosion products formed in the condensate and feedwater system of once-through boilers are precipitated and deposited inside the evaporator tubes mainly in the burner zone at the highest heat flux. Depositions lead to increased oxidation rate and increased metal temperature of the evaporator tubes, hereby decreasing tube lifetime. This effect is more important in the new high efficiency USC boilers due to increased feedwater temperature and hence higher thermal load on the evaporator tubes. The only way to reduce the load on the evaporator tubes is to minimise corrosion product transport to the boiler. Two general methods for minimising corrosion product transport to the boiler have been evaluated through measurement campaigns for Fe in the water/steam cycle in supercritical boilers within the ELSAM area. One method is to reduce corrosion in the low temperature condensate system by changing conditioning mode from alkaline volatile treatment (AVT) to oxygenated treatment (OT). The other method is to filtrate part of the condensate with a mechanical filter at the deaerator. The results show, that both methods are effective at minimising Fe-transport to the boiler, but changing to OT has the highest effect and should always be used, whenever high purity condensate is maintained.  More>>
Authors:
Hede Larsen, O; Blum, R; [1]  Daucik, K [2] 
  1. I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark)
  2. I/S Skaerbaekvaerket, Faelleskemikerne, Fredericia (Denmark)
Publication Date:
Dec 01, 1996
Product Type:
Conference
Report Number:
NEI-DK-2465; CONF-9609282-
Reference Number:
SCA: 200104; 400800; 360105; PA: DK-96:001781; EDB-97:001754; SN: 96001697010
Resource Relation:
Conference: International conference on power plant chemical technology, Kolding (Denmark), 4-6 Sep 1996; Other Information: PBD: 1996; Related Information: Is Part Of Power plant chemical technology; PB: 357 p.
Subject:
20 FOSSIL-FUELED POWER PLANTS; 40 CHEMISTRY; 36 MATERIALS SCIENCE; BOILERS; CORROSION PRODUCTS; FEEDWATER; EVAPORATORS; SERVICE LIFE; MECHANICAL FILTERS; WATER TREATMENT
OSTI ID:
401722
Research Organizations:
Faelleskemikerne (Denmark)
Country of Origin:
Denmark
Language:
English
Other Identifying Numbers:
Other: ON: DE97714817; TRN: DK9601781
Availability:
OSTI as DE97714817
Submitting Site:
DK
Size:
pp. 11.1-11.17
Announcement Date:
Dec 17, 1996

Citation Formats

Hede Larsen, O, Blum, R, and Daucik, K. Chemical and mechanical control of corrosion product transport. Denmark: N. p., 1996. Web.
Hede Larsen, O, Blum, R, & Daucik, K. Chemical and mechanical control of corrosion product transport. Denmark.
Hede Larsen, O, Blum, R, and Daucik, K. 1996. "Chemical and mechanical control of corrosion product transport." Denmark.
@misc{etde_401722,
title = {Chemical and mechanical control of corrosion product transport}
author = {Hede Larsen, O, Blum, R, and Daucik, K}
abstractNote = {The corrosion products formed in the condensate and feedwater system of once-through boilers are precipitated and deposited inside the evaporator tubes mainly in the burner zone at the highest heat flux. Depositions lead to increased oxidation rate and increased metal temperature of the evaporator tubes, hereby decreasing tube lifetime. This effect is more important in the new high efficiency USC boilers due to increased feedwater temperature and hence higher thermal load on the evaporator tubes. The only way to reduce the load on the evaporator tubes is to minimise corrosion product transport to the boiler. Two general methods for minimising corrosion product transport to the boiler have been evaluated through measurement campaigns for Fe in the water/steam cycle in supercritical boilers within the ELSAM area. One method is to reduce corrosion in the low temperature condensate system by changing conditioning mode from alkaline volatile treatment (AVT) to oxygenated treatment (OT). The other method is to filtrate part of the condensate with a mechanical filter at the deaerator. The results show, that both methods are effective at minimising Fe-transport to the boiler, but changing to OT has the highest effect and should always be used, whenever high purity condensate is maintained. Whether mechanical filtration also is required, depends on the boiler, specifically the load on the evaporator. A simplified calculation model for lifetime evaluation of evaporator tubes has been developed. This model has been used for evaluating the effect of corrosion product transport to the boiler on evaporator tube lifetime. Conventional supercritical boilers generally can achieve sufficient lifetime by AVT and even better by OT, whereas all measures to reduce Fe-content of feedwater, including OT and mechanical filtration, should be taken, to ensure sufficient lifetime for the new boilers with advanced steam data - 290 bar/580 deg. C and above. (au)}
place = {Denmark}
year = {1996}
month = {Dec}
}