Monitor for deposition on heat transfer surfaces

Abstract

A monitor for determining a buildup of slag on the flame side of water cooled walls of coal fired steam generators and other heat transfer surfaces. This monitor has a body to be positioned in an orientation similar to the water tubes of the steam generator (or other heat transfer surfaces) so that any deleterious buildup on the surfaces will also be effected upon the exterior of the monitor. Positioned within the body of the monitor is a temperature sensor, such is a thermocouple having at least a hot junction. Also positioned within the body and proximate the sensor (e.g., thermocouple) is a heater unit having a high temperature portion located proximate the hot junction. In this manner, when the heater is energized, the hot junction is raised to a preselected temperature. By monitoring the time constant of temperature change of the sensor with current to the heater being cycled, information as to the degree of buildup on the exterior of the body can be obtained. Accordingly, deposit removing equipment of conventional type can be operated when the buildup has reached a point where a change in the heat exchange qualities of the surface has become ineffective. Additional temperature sensors (e.g., thermocouples) can be used to provide temperature information from which instantaneous heat flux can be computed.