Activity

Biomass pellet heaters can be used in home heating, cooking, drying and other fields by matching with boilers, heaters or hot-blast stoves. A properly designed wood pellet burners can enhance the burning performance of biomass pellets up to greater than 86%. As biomass pellets have consistent size and density, they can recognize automatic feeding and continual burning.

Categories of biomass pellet heaters

According to various feeding technique, the pellet heaters can be classified into 3 types: upper feed type, lower feed type, as well as perspective feed type.

Upper feed kind pellet burner

Upper feed type pellet heaters are the most widely used in boilers and also ranges. Most upper feed kind burning tool has blanking channel on the inner wall, which the pellet fuels pass through as well as get involved in the burning chamber. The key air and the warm air required for automated ignition come in via all-time low of the burning chamber. The secondary air come in through the holes on the wall surface of the burning chamber.

Upper feed kind pellet heater is generally outfitted with a blower to supply burning air and advertise warmth exchange in between ranges as well as bordering air. To help with ash getting rid of, the grate is made to be manual or automated, to make sure that the ash falls under the dirt collection agency with the grate activity.

Base feed kind pellet heater

Base feed type heaters are originally used for the burning of timber chips, after that they progressively become functional for biomass pellet fuel. The pellet fuels are fed to the combustion bed via the pipeline at the end of the pellet heater by the feed conveyor. The key air enter into the burning chamber via the holes on the feeding tool or the burning bed. And also the additional air get involved in the combustion chamber via the holes above the burning bed. The bottom feed kind pellet heater does not need a different dirt collector. The ash after melting are squeezed right into the dirt collector or ash transmission system on the bottom.

Horizon feed type pellet heater

The working concept of perspective feed kind pellet burner is the same with bottom kind feed kind. The only different is the form of the burning bed. Besides, horizon feed kind pellet heater require extra dust enthusiast.

Feed conveyor in the pellet burning system

In many cases, the burning burner is divided with the stock bin, so there must be a feed system between them. The feed system offers to feed the wood pellet gas to the combustion chamber. The feeding rate is identified by the warm demand. The most typical feeding techniques are spiral conveyor and also air flow communicating system.

Spiral conveyor

Spiral conveyor is one of the most typical sort of feeding tool. It has simple framework, little volume and also small style. It is very easy to run as well as manage, with high safety and security as well as good sealing. It is suitable for short-distance communicating. The cost is low yet the power consumption is relatively high. It is sensitive to the steels, minerals and also other impurities, so it requires the biomass pellet gas are consistent, tidy and under particular size.

Air flow sharing system

If the pellet heater has big distance with the supply container, air movement conveying system is better. The operation of air movement conveyor is comparable with vacuum. Under solid suction of the pneumatic gadget, the wood pellets enter into the burning chamber with the pipe.

The air flow communicating system can understand long-distance and also continuous sharing of small pellets as well as small-size block products. It can recognize horizontal and also inclined communicating. The air flow conveyor features easy structure, great securing, simple setup and upkeep. But the transmission rate is not uniform and also constant, the exhaust noise is big, and also the cost is relatively high.

The procedure and also control of pellet burners

Ignition

Pellet burners embrace 2 methods of ignition: electronic ignition gadget and also pilot flam. Electric ignition is more straightforward to regulate, with much less toxin exhaust than pilot flam.

Warmth efficiency

To make certain the sanitation of pellet heater, you need to prevent several introducing or using pilot flam, and guarantee the burning problem is secure. Properly designed pellet burner can achieve greater than 90% effectiveness at rated heat. Also under low tons or unsteady tons, the warmth performance is above 86%.

Combustion control

The pellet heater can readjust the feed quantity or combustion air quantity to regulate the burning process. According to the warmth need, the pellet heater usually has a number of various outcome gears. When the result heat is less than the set degree, the pellet heater will certainly run immediately till it attains the set degree.

The pellet heater is generally outfitted with a temperature level sensing unit to keep track of the warm result. The combustion air is supplied by wind blower and also kept track of and managed by a sensor. Little pellet burners embraces thermostat to control the heat result, while large burners adopts much more complicated approaches.

Running modes

Pellet heaters has 2 primary running modes. The initial setting is stood for by Sweden. The pellet heater is an independent system. It usually matches with a typical boiler. The feeding, ignition and burning are automatic. But the warm output is uncontrollable or has 2 qualities, complete outcome and also half result.

The various other mode is stood for by Austria. The feeding, ignition, burning as well as ash cleaning are automated. The warmth output can be readjusted within a certain array, for example, 30% -100%. It is easy to use, but the price is 50% greater than the very first setting.

Ash removal gadget

The ash eliminating technique of a timber pellet heater are mechanical scuffing and mechanical resonance. Some pellet burners are outfitted with ash compressor to make sure long time running. Properly designed feed machine for poultry require little maintenance. Many ash removal tool in pellet burners can fulfill the need of cleaning once a week.

Pollutant discharge

The smoke of biomass pellet burner generally contains CxHy and also CO. They are generated by the not enough burning of timber pellets, affected by the structure of the timber pellets. The smoke from pellet heater is little bit, particularly those with inlet and exhaust gadgets. As the nitrogen as well as sulfur content in the biomass pellet fuel is reduced, so the NOx as well as Sox emission is much less than coal.

Troubles of biomass pellet heater

The technology of pellet heater is obtaining fully grown with the increasing application of biomass pellet fuel. But presently, the wood pellet burner still have some problems: the varieties are not wide, the application areas are restricted.

High ash deposition and also slagging price

The Si material is high in straw products. The deformation temperature of straw ash is usually 750 ~ 1000 ℃, so the ash deposition rate is more than timber pellets.

Ash removal is a problem that can not be ignored in biomass pellet heater. The ash deposit generally includes huge amounts of alkaline parts and chloride. The range and also slag will certainly not just affect the warm efficiency of the burner, but likewise endanger the safety of shedding equipment.

According to research, the potassium, chloride and also sulfur aspects has terrific impact on slagging. The slagging rate boost together with the temperature level, the dimension of fireplace, and also the density of gas.

Chlorine corrosion

Straw pellets contains high antacids steel as well as chlorine material. In burning process, nearly all the chlorines have evaporate. They turn into HCL, CL2 as well as alkali chloride. As the smoke get cooled, the alkali chloride cake on the surface of heat exchanger. They have reaction and generate sulfate and also chloride, which has strong oxidizing capacity. They can quicken the corrosion of metals, as well as lower the warmth transfer performance. Hereof, straw pellets has even more damage to the pellet heater than wood pellets. To put it simply, straw pellets has greater requirement on the burning tool.

Low degree of automation

Previously, a huge part of pellet burners still embrace hands-on feeding as well as half-automatic feeding system. The reduced degree of automation impedes the large-scale application of timber pellet gas.

Numerous tiny pellet burners ventilate naturally, so they generally have the problems of insufficient burning and also high toxin exhaust.

Conclusion

Biomass pellet burners have been extensively used in warm supply, biomass boiler as well as biomass power generation. Properly designed pellet heater can boost the heating performance, reduce slag and also contaminant exhaust, and conserve labor job. With biomass wood pellet machine enhancing application of biomass power, it has higher demand on the pellet burning technology.