The industries, mainly small-scale and household industries, have been traditionally dependent on the diesel and furnace oil for their heat requirement. So, when these industries decided to shift towards a greener and economical option, they were seeking a solution that can work with their existing systems without any significant modification. This could have been done in three ways:
- Replacing diesel with biodiesel
- Installing a gasifier and use a gas burner
- Developing equipment that can burn solid biomass just like diesel.
The first two options were a distant reality at that time and even now. The biodiesel is still an ongoing research process and hasn’t made much development outside the laboratories. Gasifier, on the other hand, has just a handful of success stories but a lot more of failure stories. The third option was what led to the development of the biomass/pellet burner.
Let’s first understand what pellet burner is and its principle.
Principle of Operations
The pellet burner is simple equipment that works on the principle of updraft gasification. The significant difference between an updraft gasifier and pellet burner is that that gasification chamber and gas burner are attached units and not separate.
The fuel is fed into the hopper which is conveyed to the combustion/gasification chamber through a screw conveyor. The fuel/pellets are gasified through incomplete combustion from the air coming from the bottom. The producer gas, thus generated, then raises and reaches the burner nozzle/ flame cone. This gas has a high calorific value. So, when the producer gas is mixed with the secondary air, it starts burning, and a high-temperature flame is generated. This flame can be fed into the systems where diesel burners were installed.
What’s Wrong with Pellet Burners?
Now that you have understood the design of pellet burners, let us explain why pellet burners are the biggest conspiracy in the biomass market!
The pellet burners in India were introduced by the pellet manufacturers in 2000s. They were designed in such a way that they can only burn pellets of specific size and type, i.e., pinewood pellets of 6-mm diameter and 25mm length. If you try to feed any other biomass or any different size of pellets, the system will stop working, or breakdown will happen. Let us explain this in more details:
- First, these pellet manufactures, who were selling pellet burners, they knew that manufacturing 6-mm sized pine wood pellet is an arduous process, and consumers will have to depend on those pellet manufacturers for the fuel supply. The reason is that India imports the pinewood as pine is a protected species in India. Then making a 6-mm sized pellet requires special kind of machines which are also not made in India and are expensive. So, that’s how they started creating their monopoly. They tied up with some fabricators who started designing burners for their fuel as per their design. So, as soon as the customer installs burner, the customer will have no choice for the fuel and will have to depend on them, no matter what the cost of pellets are.
- Second, the burner’s hopper and feeder system were designed in a way that doesn’t let any other fuel to be fed adequately to the system. The feeder will jam if any pellet higher than 6-mm is added to the hopper.
- Third, the burner was designed in such a way to keep the screw conveyor and burner nozzle at the same height. With this, if any other small-sized fuel, such as sawdust/woodchips/Astillas are fed into the system, the fuel will directly be thrown to the nozzle from the conveyor. The carryover will increase as the fuel will have much lesser bulk density and will go unburned, reducing the output from the system tremendously.
- Fourth, if you compare the diesel burner with a pellet burner, there is a difference in how the fuel is burned. In a diesel burner, the fuel is sprayed, and external combustion happens. On the other hand, the flame is generated inside the burner nozzle in the pellet burner. Therefore, the temperature of the nozzle increases significantly due to which these burners are not suitable for continuous 24-hours operations.
And that’s when we decided to break this monopoly.
What Did We Change?
We always believed that the end-consumer should have a choice to select their fuel. They shouldn’t be forced by any way in their fuel choice. We completely changed the design to make the system flexible for other fuels too.
- We changed the hopper angle to allow the free-flow of the materials with higher wall resistance such as rice husk, sawdust, dried wood chips, Astillas, etc.
- The feeder diameter and pitch was also increased to compensate for the lower bulk density of other fuels.
- The burner nozzle centre height was increased to avoid the carryover of the biomass.
- The burner nozzle design was optimized to keep it cool for longer. The water-jacketed nozzle was also worked upon for 24-hour operations.
- We also created a new biomass fuel blend, Astillas, that has higher calorific value and much lesser cost than the pellets.
In short, we gave the power back to the hand of the consumer to be independent of their fuel choice. They can use all fuels as per their choice without worrying about the health of their systems. We call our system as Two-stage Combustor. We have also designed a specialised system for the roaster industry, i.e., Roaster Heater Combustor (REC).
What do you think about this? Is it a right way to create a monopoly where you handicap your customers? We would love to hear your opinion on this.