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Title: NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.

Abstract

Operation of the Next Generation Nuclear Plant (NGNP) with reduced reactor outlet temperature at full power was investigated for the High Temperature Electrolysis (HTE) hydrogen-production application. The foremost challenge for operation at design temperature is achieving an acceptably long service life for heat exchangers. In both the Intermediate Heat Exchanger (IHX) and the Process Heat Exchanger (PHX) (referred to collectively as high temperature heat exchangers) a pressure differential of several MPa exists with temperatures at or above 850 C. Thermal creep of the heat exchanger channel wall may severely limit heat exchanger life depending on the alloy selected. This report investigates plant performance with IHX temperatures reduced by lowering reactor outlet temperature. The objective is to lower the temperature in heat transfer channels to the point where existing materials can meet the 40 year lifetime needed for this component. A conservative estimate for this temperature is believed to be about 700 C. The reactor outlet temperature was reduced from 850 C to 700 C while maintaining reactor power at 600 MWt and high pressure compressor outlet at 7 MPa. We included a previously reported design option for reducing temperature at the PHX. Heat exchanger lengths were adjusted to reflect themore » change in performance resulting from coolant property changes and from resizing related to operating-point change. Turbomachine parameters were also optimized for the new operating condition. An integrated optimization of the complete system including heat transfer equipment was not performed. It is estimated, however, that by performing a pinch analysis the combined plant efficiency can be increased from 35.5 percent obtained in this report to a value between 38.5 and 40.1 percent. Then after normalizing for a more than three percent decrease in commodities inventory compared to the reference plant, the commodities-normalized efficiency lies between 40.0 and 41.3. This compares with a value of 43.9 for the reference plant. This latter plant has a reactor outlet temperature of 850 C and the two high temperature heat exchangers. The reduction in reactor outlet temperature from 850 C to 700 C reduces the tritium permeability rate in the IHX metal by a factor of three and thermal creep by five orders of magnitude. The design option for reducing PHX temperature from 800 C to 200 C reduces the permeability there by three orders of magnitude. In that design option this heat exchanger is the single 'choke-point' for tritium migration from the nuclear to the chemical plant.« less

Authors:
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
NE
OSTI Identifier:
951249
Report Number(s):
ANL-GENIV-105
TRN: US200911%%453
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Technical Report
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; ALLOYS; CHEMICAL PLANTS; COMPRESSORS; COOLANTS; CREEP; DESIGN; EFFICIENCY; ELECTROLYSIS; HEAT EXCHANGERS; HEAT TRANSFER; HYDROGEN PRODUCTION; LIFETIME; OPTIMIZATION; PERFORMANCE; PERMEABILITY; PROCESS HEAT; SERVICE LIFE; TRITIUM

Citation Formats

VIlim, R, and Nuclear Engineering Division. NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.. United States: N. p., 2009. Web. doi:10.2172/951249.
VIlim, R, & Nuclear Engineering Division. NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.. United States. https://doi.org/10.2172/951249
VIlim, R, and Nuclear Engineering Division. 2009. "NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.". United States. https://doi.org/10.2172/951249. https://www.osti.gov/servlets/purl/951249.
@article{osti_951249,
title = {NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.},
author = {VIlim, R and Nuclear Engineering Division},
abstractNote = {Operation of the Next Generation Nuclear Plant (NGNP) with reduced reactor outlet temperature at full power was investigated for the High Temperature Electrolysis (HTE) hydrogen-production application. The foremost challenge for operation at design temperature is achieving an acceptably long service life for heat exchangers. In both the Intermediate Heat Exchanger (IHX) and the Process Heat Exchanger (PHX) (referred to collectively as high temperature heat exchangers) a pressure differential of several MPa exists with temperatures at or above 850 C. Thermal creep of the heat exchanger channel wall may severely limit heat exchanger life depending on the alloy selected. This report investigates plant performance with IHX temperatures reduced by lowering reactor outlet temperature. The objective is to lower the temperature in heat transfer channels to the point where existing materials can meet the 40 year lifetime needed for this component. A conservative estimate for this temperature is believed to be about 700 C. The reactor outlet temperature was reduced from 850 C to 700 C while maintaining reactor power at 600 MWt and high pressure compressor outlet at 7 MPa. We included a previously reported design option for reducing temperature at the PHX. Heat exchanger lengths were adjusted to reflect the change in performance resulting from coolant property changes and from resizing related to operating-point change. Turbomachine parameters were also optimized for the new operating condition. An integrated optimization of the complete system including heat transfer equipment was not performed. It is estimated, however, that by performing a pinch analysis the combined plant efficiency can be increased from 35.5 percent obtained in this report to a value between 38.5 and 40.1 percent. Then after normalizing for a more than three percent decrease in commodities inventory compared to the reference plant, the commodities-normalized efficiency lies between 40.0 and 41.3. This compares with a value of 43.9 for the reference plant. This latter plant has a reactor outlet temperature of 850 C and the two high temperature heat exchangers. The reduction in reactor outlet temperature from 850 C to 700 C reduces the tritium permeability rate in the IHX metal by a factor of three and thermal creep by five orders of magnitude. The design option for reducing PHX temperature from 800 C to 200 C reduces the permeability there by three orders of magnitude. In that design option this heat exchanger is the single 'choke-point' for tritium migration from the nuclear to the chemical plant.},
doi = {10.2172/951249},
url = {https://www.osti.gov/biblio/951249}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 12 00:00:00 EDT 2009},
month = {Thu Mar 12 00:00:00 EDT 2009}
}