CoMate in Wood-Fired Furnaces
Wood is by far the most common form of biomass utilized in industrial scale applications. In industries like pulp and paper and board manufacturing, wood waste that would otherwise be disposed of through other means is instead utilized in wood-fired furnaces.
How CoMate Works in a Wood-Fired Furnace
Typically, a wood fueled furnace will see a large amount of grate ash, a negligible amount of wall ash and a small amount of glassy ash which, if untreated, will eventually plug the unit.
The wood used to fuel these boilers has contaminants from several sources, usually in the form of sands and salts which:
- are incorporated during the growth of the wood;
- lodge in the bark during growth; and
- are collected during harvesting, transport and processing of the fuel.
These contaminants will have a range of sensitivity to heat; they may ionize, melt or be unaffected. When wood fuel is delivered to the furnace, it will contain some of the previously listed contaminants. They will react as follows:
- larger sand, rocks and other heavy materials will separate and be removed on or through the grate;
- lighter materials will be carried up by the burning process;
- temperature resistant materials will carry over;
- melted materials may stick to boiler surfaces; and
- ionized materials will join in with the flue gas and become sticky as they cool and will deposit on the surface that cools them.
The CoMate Advantage
When CoMate is applied, it will cause deposits to be friable and easy to remove, keeping the unit free of problematic deposits throughout its operating cycle. Normally, without CoMate, when ash deposits are removed from the cooler portions of the boiler, it is in the following forms:
- colloidal glass beads formed from completely melted or ionized silicates;
- pieces of melted, lava-like material; and
- sharp, broken, heat resistant materials.
All of these materials can be abrasive; broken material is the most abrasive.
When CoMate is used in a furnace, it will increase the furnace temperature and reduce the fraction of unaffected ash. Old ash deposited in the boiler will be removed by attrition from areas inaccessible by normal cleaning methods. While this old ash is being removed, there may be a higher fraction of broken ash carried over. Once the unit is clean, the ability of dust collectors to remove heat resistant ash will improve and it will be beneficial to operate the collectors to prevent abrasive carryover.