Low Excess Air,High Performance Combustion System for Marine Boilers.

摘要

A design study was performed on low excess air combustion systems for a marine boiler having a nominal rating of 100,000pph at 955 F, 875psig. Two combustion configurations were selected for detailed evaluation consisting of (a) a staged furnace containing three combustion zones separated by a novel air introduction means,and (b) a conventional furnace configuration with massive recirculation burners. Based on earlier experimental work,excess air levels were predicted at less than 1% and less than 5%,respectively. The principal advantage expected due to low excess air is a reduction in the cost of maintenance and an improvement in overall performance. The staged combustion process offered the additional advantage of uniform velocity and temperature profiles to the superheater. An economic evaluation reveals that for the most cost effective system the initial investment would be recovered in less than three years. The ratio of present worth of future savings over 10years discounted at 11-1/9%/annum to initial investment was found to be from about 2to 14for the most cost effective systems.