Once Through Benson Boiler - Vertical Tube Furnace

Abstract:

<p>This document is a report for the project titled 'Once Through Benson Boiler - Vertical Tube Furnace'.</p> <p>Situated in Henan Province, PRC, Yaomeng Power Plant consists of 4 × 300MWe coal-fired boilers, units 1 and 2 of which, entered service in the mid 1970's. They were of the high mass flux, once through, sub-critical universal pressure ( UP ) type, designed for base load operation to generate 935te/h main steam at 570&deg;C.</p> <p>From 1992 onwards, after overheating in some of the pressure parts, which led to a restriction of 545&deg;C on the main steam temperature, the maximum output was reduced to 270MWe. The boiler's intrinsic intolerances to load changes, and operation below 230MWe were also problematic, and the prospect of more onerous emissions legislation was thought likely to impose even further restrictions on plant usage in the future, or even bring about its closure.</p> <p>The scope of work for Mitsui Babcock was centred on the upgrade of the existing boiler, comprising refurbishment of the furnace pressure parts and improvement of the burners, start-up system and control philosophies. </p> <p>The 168-hour full load reliability test was completed successfully during May, 2002. What made the occasion particularly significant for all concerned was that this was the first time Low Water Mass Flux Vertical Ribbed Tube Benson Boiler Technology had been used for commercial power generation anywhere in the world, a very significant achievement by Mitsui Babcock.</p> <p>The Performance Guarantee Tests ( PGT's ) were performed by the Thermal Power Research Institute ( TPRI ) during the end of July / early August 2002, and these results and subsequent operation have confirmed the major improvements in the unit. Peak steam output is 1010.3t/hr and maximum continuous output is 954t/hr, both exceeding the guarantee requirements. Peak power output has increased from 270MWe to 327MWe, and in fact the boiler has now been formally up-rated to 310MWe.</p> <p>The successful completion of this refurbishment is a major milestone in both the development of the technology of once through low mass flow vertical tube boilers and Mitsui Babcock's presence in the refurbishment market in the PRC. Wherever sub-critical once through boilers are suffering load restrictions, intolerances to load changes or high metal temperatures, this technology now offers a proven solution, which also extends to super-critical pressure conditions. </p> This report is divided into the following sections: <ol> <li>Introduction</li> <li>Original Furnace Design and Performance</li> <li>Design of the Refurbished Vertical Ribbed Tube Furnace</li> <li>Boiler Performance</li> <li>Operational Feedback since the Performance Guarantee Tests</li> <li>Future Applications</li> </ol>

Author(s):

Smith, BW