Suspension-Firing of Biomass. Part 1: Full-Scale Measurements of Ash Deposit Build-up

Abstract

This paper is Part 1 in a series of two describing probe measurements of deposit build-up and removal (shedding) in a 350 MWth suspension boiler, firing straw and wood. The influence of fuel type (straw share in wood), probe exposure time, probe surface temperature (500, 550, and 600 °C), and flue gas temperature (600–1050 °C) on ash deposit formation rate has been investigated. Investigations of deposit formation rate were made by use of an advanced online deposit probe that allowed nearly continuous measurement of the deposited mass. Two different measures of deposit formation rate are used in the analysis of the data. The first is the integral deposit formation rate (IDF-rate) found by dividing the integral mass change over integral time intervals (of order several hours) by the time interval. The IDF-rate is similar to deposit formation rates based on total deposit mass uptake divided by probe exposure time reported in previous full-scale investigations, but it is a relatively crude measure that inclu...