What is a “real pyrolysis boiler”

This article will discuss the “pyrolysis boiler,” widely used in recent years, which is used to process solid fuels of plant origin, including pellets, briquettes, etc.

Let’s start with the origins of the name “pyrolysis boiler”. The essence of the pyrolysis reaction is discussed in Wikipedia: briefly, through biomass pyrolysis two main products are obtained:

  • Carbon residue (charcoal)
  • Gas-vapor mixture (combustible pyrolysis gas). This in turn can be divided into 2 fractions; condensable (liquid) and non-condensable (gaseous) pyrolysis products

The main problem in terminology is that the so-called “pyrolysis boilers” in the market, in essence, do not employ true pyrolysis. In fact they are boilers with “two-stage combustion”, which is a fundamentally different process. The reaction in such boilers is more accurately called “Gasification”; again, the essence of the biomass gasification process is disclosed in Wikipedia. In gasification of biomass, two main products are obtained:

  • Ash residue (ash)
  • Combustible generator gas (often called “syngas”), which cannot be condensed at normal ambient temperatures (+ 10-40 ° C)

Understanding this distinction, a logical question arises for manufacturers of the so-called “pyrolysis boilers”: “Where is the carbon residue that should result from the pyrolysis reaction?”. If the answer is: “The carbon residue burned up during the reaction”, this means that their the reaction is not pyrolysis, but gasification!

The saddest thing is that with the increasing uptake of renewable energy sources, many “amateur” constructors have entered the market. They do not understand the principles of the reactions, but only use the buzzword “pyrolysis” – mis-naming their two-stage combustion boilers as “pyrolysis boilers”.

Greenpower’s pyrolysis furnaces do indeed have a pyrolysis process. You can read more about them here.