Photos are from Egtved District Heating Plant (left) and Gjerlev District Heating Plant (right).

• The straw handling system includes a Linka® straw conveyor and shredder, which adjusts the drum speed according to the boiler’s heat demand. The shredded straw is conveyed to the straw auger, through the cell gate, and into the stoker auger, and is then directed to the moving grate at the front of the boiler.

• The wood chip handling system is supplied with a walking floor system/scraper conveyor, which transports the chips via augers. The scraper conveyor features horizontal frames that direct the fuel to a cross auger monitored by photo sensors. If the auger is not fully loaded, the scraper conveyor is activated automatically. The chips are conveyed through the cell gate to the stoker auger and then to the moving grate in the boiler. The system includes both inclined and cross augers.

Facts

• The filter is delivered as a complete unit, with all wiring, insulation, and cladding done at the factory.
• The filter is equipped with side doors for inspection and service.
• The service area has a handrail installed, and a staircase leading to the ground.
• All exterior surfaces are insulated with mineral wool.
• The cladding is made of aluminium sheets in a colour of the customer’s choice.
• Easy to connect to existing plants that use wood pellets or wood chips. Dust from straw cannot be magnetised.

The energy consumption of the electrostatic precipitator is modest, and it requires only minimal maintenance – as we say at Linka:

Think about the working environment – avoid fly ash in the boiler room.

The dust-loaded flue gas is directed through a chamber in the electrostatic precipitator, which is divided into channels by vertical steel plates, also known as precipitation plates. Between the plates, vertical wires are stretched parallel to the plates.
A substantial electric potential difference is applied between the wires and the plates, typically 30-100 kV depending on the distance between them, which gene-rates a weak electric discharge.
This discharge ionizes some of the gas molecules, cau-sing the ions to attach to the dust particles and give them an electric charge. These charged particles are then attracted to the plates, where they are held.
The plates are periodically vibrated, causing the dust to fall into the bottom silo of the filter. From here, dust and ash particles are discharged via an ash auger to the common ash system.

The electrostatic precipitator is one of the most effective methods for removing very fine dust. The increasing requirements for flue gas cleaning have led to higher demand and usage in various processes, including the district heating sector. The energy consumption of the electrostatic precipitator is low, and the maintenance requirement is minimal. The filter is insulated with 100 mm of insulating material and clad with aluminium sheets in a standard colour.
After the flue gas has passed through the filter, the dust emission is reduced to an absolute minimum. The noise emission from the electrostatic precipitator’s “hammers” is less than 70 dB(a) and will be further noise dampened.
After the filter, the flue gas is directed through a frequency-controlled flue gas fan to ensure optimal discharge through the chimney.

Advantages

Linka® recommends an electrostatic precipitator for wood chip/pellet-fired biomass plants because it:

• Cleans automatically and is controlled via a valve control system.
• Is inexpensive to operate.
• Requires minimal supervision.
• Is an investment that can pay off over time.
• Is easy to integrate with an existing plant.

Facts

• Fully complies with current regulations for meeting emission requirements (MCP Directive).
• The filter is assembled in segments made of steel plates.
• Top doors are mounted on the filter for inspection and service purposes.
• The service area has a handrail installed, and a staircase leading to the ground.
• All external surfaces are insulated with mineral wool.
• The cladding is made of plastic-coated aluminium sheets in a standard colour of the customer’s choice.
• Easy to connect to existing installations.

The energy consumption of the bag-filter is modest, and it requires only minimal maintenance – as we say at Linka:

Think about the working environment – avoid fly ash in the boiler room.

The bag-filter is used for purifying flue gases from biomass boilers and is an efficient and reliable solution that combines several advanced technologies for optimal performance and low maintenance.
The filter is equipped with a necessary service platform on the “filter top” and at the lower inspection door on the flat scraper bottom of the filter. Additionally, it is designed as a buffer tank and is equipped with a robust hub and gear system sized to rotate and empty fly ash from the filter’s scraper bottom. The filter baskets are made of either black steel or AISI (stainless steel) and are split in two or three parts depending on filter height.
The filter is fitted with a spark arrestor and filter bags expected to have a lifespan of 4-5 years. The filter bags are available in 3 different qualities depending on the boiler’s flue gas temperature.
The filter is equipped with three bypass dampers which, in emergency situations, can divert the flue gas past the filter during startup, shutdown, and operation. This bypass damper is activated if temperatures exceed what the bags can handle. Additionally, the filter has standstill heating to keep it dry and warm during standby periods. The standby heating circuit can be equipped with an energy meter to register how much heat is used for this process.

The filter is insulated with mineral wool (100 mm indoors / 200 mm outdoors) and has a service platform on top as well as an inspection door at the bottom.
The filter cleaning system is not just a fully automatic cleaning system, meaning it doesn’t just clean based on a certain pressure differential, but it is programmed to clean based on varied pressure differentials.
This means, for example, that it starts the cleaning cycle at a pressure differential of 80 mmWC – at 100% plant load, and the setpoint for starting the cleaning cycle varies with increasing and decreasing plant load. For example, at a plant load of 70%, the cleaning cycle will start at 56 mmWC. This ensures that there is always approximately the same amount of fly ash on the filter medium regardless of significant variations in plant load.

It is a definite advantage that there is always the same amount of ash on the filter medium and the filter medium is never exposed to any sticky particles in the flue gas. At the same time, there will be a modest energy saving as the pressure drop across the filter is reduced with decreasing plant load.
The filter’s cleaning system is extremely efficient, where one row of filter bags is cleaned via a “shot tube” which delivers a pressure pulse of air into the bags.
Afterward, the flue gas is drawn through the frequency-controlled flue gas fan and subsequently out into the chimney.

Advantages

• Low filter load, which extends the lifespan of the filter bags.
• Automatic cleaning controlled via a valve control system.
• Reliable operation using standard components that do not require service from specially trained technicians.
• The filter’s cleaning system has no moving parts apart from the mechanical movement in the diaphragm valves and the scraper arm at the bottom of the filter.
• Inexpensive to operate.
• Requires less supervision.
• An investment that can pay off over time.
• Easy to integrate with an existing system.