Reliable and effective, hopper heaters are designed for preheating the hopper to prevent moisture condensation from collecting during startup conditions, as well as maintaining the hopper (and fly-ash) above the flue gas acid dew-point during normal operating conditions.
During the last decade many designs and operating procedures have been tried to minimise or eliminate hopper pluggage caused by compaction, agglomeration and solidification. Many of the earlier designs aimed to solve the compaction problem by means of poke tubes and mechanical vibrators, while another method, fluidising systems, tended to require significant maintenance.
Hopper heating was recognised as the most practical method to prevent agglomeration and solidification. Earlier designs of hopper heater that used strip heaters, MI cable and tubular heaters proved to be unreliable due to constructions being prone to vibration failure modes.
In 1975 the first modular hopper heaters became available; specifically designed to provide a reliable source of hopper heating.
For this special application Thermon has developed highly rugged modular hopper heaters. Instead of resistance wire they contain a heating element stamped from a high temperature alloy, Inconel 600, providing multiple paths and eliminating series wire burnout which is typical for conventional systems.
Type HT Thermon hopper heaters have been designed to withstand harsh environments over 20 plus years of operating life of the system.
Typical applications for Thermon hopper heaters include:
- parallel circuit heating elements
- reliable connection design
- low watt density
- vibration and shock resistance
- rugged construction
- ease of installation.