The growing global warming due to CO emissions has drawn attention to the use of biomass as fuel for power and heat production. Biomass fuel, i.e. straw, rice husk, bagasse, coconut shell, palm kernel shell, wood pellet, is an attractive fuel to replace fossil fuel in boiler system.
However, some serious problems are existing during biomass boiler operating. Let’s take straw fired utility boileras an example.
straw CFB boiler for power generation
The use of straw for heat production in small scale boiler furnaces, e.g., at individual farms, has been practiced for many years. However, power generation from biomass straw-fired-boiler has generally experienced serious problems with slagging and fouling of the superheaters. We know, there are some large content of ‘troublesome’ elements such as potassium and chlorine in the straw, then during the fuel is burning in boiler furnace, the potassium and chlorine may either deposit directly on the heat transfer surfaces as KCl or the potassium may react with the silicate part of the ash, creating low melting fly ash that has an increased tendency for adhering to heat transfer surfaces.
A part of the KCl may alternatively react with gaseous SO to form K SO. The chlorine containing deposits are known for being able to attack the metal surfaces of the superheaters leading to serious corrosion problems in the boilers.
Corrosion in straw-fired boilers is generally believed to happen by reaction between gaseous chloride species and the metal. This reaction leads to formation of volatile metal chlorides and leaves a weakened metal skeleton behind observation of selective chlorine corrosion, in which iron and chromium have been selectively removed from the superheater alloy, leaving behind a weak skeleton of nickel.
Safety is the primary. For boiler running, the corrosion can cause serious accident. Thus, timely measures must be taken once corrosion is inspected. We are leading manufacturer and supplier of Biomass Boilers that are in compliance with the industry standards. Our straw utility boiler boilers are highly efficient and have a long functional life setting high standards in the industry.
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