Construction and Installation of a 0.9 MW Pellet-Fired Boiler Plant

The client’s task was to replace the existing woodchip boiler with a more powerful pellet boiler – to design and construct a fully automatic wood-pellet-fired boiler plant together with a fuel bunker. A biomass boiler with a thermal capacity of 0.9 MW was designed for the new boiler house. The existing 0.9 MW gas boiler with its current burner remained in use as a backup unit. The primary fuel is wood pellets, and the reserve fuel is natural gas.
The objective of the project was to design an automatic biomass boiler plant capable of operating unmanned, without the need for constant human presence.

For heat supply, a fully automatic pellet boiler with a burner is used, together with a reserve boiler. The boiler plant is equipped with an existing automatic system for activating the reserve boiler. This system consists of a motorised rotary valve installed on the return lines of both boilers, a temperature sensor on the pellet boiler’s supply line, and a two-stage temperature controller.

Under normal operating conditions, the pellet boiler is in use and the rotary valve of the gas boiler is closed. When the pellet boiler’s water temperature drops to the first threshold, the rotary valve of the gas boiler opens and the gas boiler starts. When the pellet boiler’s water temperature drops to the second threshold (likely due to a pellet boiler malfunction), the rotary valve of the pellet boiler closes and only the gas boiler remains in operation.

Once the pellet boiler’s water temperature rises back to the required level, the rotary valve opens again for the pellet boiler, and the gas boiler shuts down.
The boiler plant operates unmanned, and all processes function automatically according to the required power output.