Ash Problem Up to Modification of Power Plant in the Framework of Coal Substitution to Wood Pellet on Pulverized System

The ash of various biomass in combustion causes a number of problems in the pulverized system. That's because the pulverized system is designed to burn coal. Does not the coal also produce ash after burning even more quantity? Yeah right, but the chemical content of coal ash is different from that of biomass. The difference is that coal ash contains a lot of heavy metals such as arsenic, cadmium, mercury, selenium, lead, and nickel which have high melting point so it does not cause problems to the pulverized, whereas biomass ash mainly contains alkali metals such as potassium and alkaline earths are calcium, which has a low melting point so it creates a problem on the pulverized. The content of coal ash is also much larger compare with biomass ash content.

Ash Slagging: Melt ash deposits on boilers or generally on radiant exposed surfaces in a furnace at temperatures above
1,000 C

High-temperature fouling (around 1000 ° C) while low-temperature fouling (300-600 ° C) usually occurs in boiler pipes

What is the problem with the biomass ash chemistry? There are several problems caused by the ash chemistry on the pulverized system, namely slagging and fouling. How to avoid it? There are several ways to avoid it, namely first, determine the exact percentage of biomass fuel in the pulverized system or co-firing. At the appropriate percentage of biomass fuel can be used simultaneously (co-firing) with coal. The type of biomass fuel also determines its percentage, eg wood pellets will have a larger portion than agro-waste pellets. Secondly, by modifying the coal-fired power plant so that it can even be 100% with biomass fuel such as wood pellets.

Burning biomass fuel in addition to environmentally friendly or carbon neutral, fewer CO2 emissions, SO2 emissions are also very small, very little fly ash even does not occur, and the ash is rich in potassium, and phospur so it becomes a good fertilizer for plants. While coal ash is otherwise and even categorized as dangerous waste due to the heavy metal content. Based on these things, it is natural that the use of biomass fuel continues to be improved even has become government policy in some countries.

The entry point for massive biomass fuel usage is co-firing with coal. The modification of the coal-fired power plant has become an opportunity, so a number of companies have emerged to capture such opportunities as Ramboll and Doosan Babcock. While in Indonesia it seems still long enough to make biomass fuel has a large portion as a source of energy, especially in power plants, because there is no policy that supports it.

Sectors of Pellet Fuel Usage

As a source of energy or wood pellet fuel or pellet fuel can be used in small-scale such as the household to large-scale on power plants. Both quantity and quality pellet are the parameters in its use in relation to equipment that is used. Basically from small-scale to large scale on the use pellet fuel especially related to efficiency factor, easy in operation, safety and gas emission impact (eventhough wood pellet include as renewable fuel that enter the category as carbon neutral) while the use on large-scale the qualityfactor of pellet got a serious attention. Technology that was used to utilize the wood pellet is almost all use combustion technology (direct combustion) to get output in form of heat or electricity.

In small-scale the use pellet fuel for mainly in the four season countries for room/space heating, even for this sector needs premium quality of wood pellet for pellet stove. Pellet stove has not yet been familiar in Indonesia because the wood pellet also still very difficult to get. Other equipment that are to be used in small-scale is boiler and burner. Boiler system will produce steam to source of steam and hot water. While burner can be used for various source of heat.

On the medium-large scale, users mainly for industries and coal-fired power plants. Grate combustor and stoker are equipments that general used in the industry. Pulverized technology system and fluidized bed commonly used in power plant. The percentage of wood pellets this time is still less than 5 percent on the use of cofiring in the coal powerplant. Wood pellet for pulverized while biomass pellet for fluidized bed. The characteristics of both pellet cause of the difference.