Ash and certified pellets: what to give preference to in terms of economy

Quite often, you can hear positive reviews about pellet technology due to the low cost of pellets. But for a person who is faced with pellet boiler houses for the first time, it is important to clarify that fuel pellets differ in cost, heat transfer and ash content. Not only certified pellets are on sale in Ukraine. Moreover, a high rate of combustion products is characteristic of pellet fuel with high heat transfer.

In Ukraine, the most popular are sunflower husk pellets. Their ash content is 3% with a heat transfer of 21 MJ / kg against wood pellets according to a certificate with the same characteristic of less than 1% and a heat transfer of 18-23 MJ / kg. Certified pellets have a higher cost than agricultural pellets, which should be taken into account when calculating potential costs. European equipment for pellet boiler houses is designed for the use of pellets that meet the requirements of the EN Plus A-1 standard. The ash content for pellets according to certificates should not exceed 0.5-0.7%.

Pellet pellets for heating private houses, offices and factories

The table below clearly shows that wood pellets are by far the most profitable fuel when comparing costs per kilowatt. When using pellets from sunflower husk, the costs are even lower. If you have affordable equipment, you can granulate the pellet yourself, but it will differ in quality from the pellet according to the certificate.

Fuel	Calorific value according to standard	Required amount, 1 kW * h	Estimated fuel price	Fuel cost per kW
Main gas	8.6 kWh / m3	0.116 m3	8.07 UAH / m3	0.936 UAH
Liquefied gas	12.8 kWh / l	0.0782 l	11.60 UAH / l	UAH 0.907
Wood pellets	4.05 kWh / kg	0.247 kg	4,3 UAH / kg	UAH 0.995
Agropellet (sunflower husk)	5.01 kWh / kg	0.201 kg	1,5 UAH / kg	UAH 0.3
Electricity	—	1 kWh	1.68 kWh	1.68 UAH

 

The choice of pellets: how it affects the choice of the boiler

If you plan to use granular fuel without a certificate, consider only proposals for boiler equipment designed for all types of pellets. Or just choose a domestic manufacturer. As a rule, foreign pellet boiler houses do not work with Ukrainian pellets without a certificate and are not designed for such fuel parameters.

Installation for self-granulating pellet fuel

What to look for when choosing a pellet boiler room

If you plan to use uncertified pellets as fuel for the heating system and equipment, you need to pay attention to the following technical parameters of the boiler. The possibility of using pellets with high ash content inevitably affects the technical solution of the boiler.

Burner type

Combustion of fuel in a pellet module is different from the combustion process in a conventional solid fuel boiler. Boilers or burners of rotary or flare type are offered for sale. In the second case, the technology of volumetric combustion is used, which differs from conventional ignition at once in the entire volume of fuel with high heat transfer.

Pellet burner FOCUS

In this case, the release of heat does not depend on the quality of the pellet. The pyrolysis afterburning of the resulting combustion products not only increases the efficiency, but also reduces the amount of ash settling on the walls of the equipment.

Please note that soot and ash have thermal insulation properties. Accordingly, pollution entails a decrease in the heat transfer of the flame to the heat carrier.

When choosing equipment for burning ash pellets, give preference to:

• flare burner with microprogram control of combustion intensity;
• equipment with pyrolysis afterburning of combustion products.

This combination of technical characteristics guarantees less ash settling on the boiler walls when using high ash fuels.

Boiler cleaning system

The second important characteristic when choosing pellet equipment is the cleaning system. Manufacturers offer mechanical, semi-automatic, automatic and pneumatic cleaning. The heat exchanger can be cleaned with catalytic fuel. In practice, a mechanical type of cleaning is most suitable for powerful boiler houses - manual, automatic or semi-automatic cleaning by shaking the grates.

Whichever choice of boiler you choose, be sure to pay attention to the equipment cleaning system. Especially considering the use of cheaper sunflower husk pellets.

Feeder

Automatic pellet feeders will help to fully automate the process of fuel combustion. They are designed as two augers. One screw conveyor transports the pellet to the pellet burner. The other auger feeds the pellet from a storage location, usually from a special hopper of modular design. Metered auto-feed and pellet hopper allow keeping low moisture content of the pellets, this characteristic affects the ash content during combustion.

Pellet boiler or pellet burner?

Before choosing the FOCUS brand, many of our customers preferred monoblock pellet boilers of foreign production, but, trying to understand the technical part of the issue, they opted for a pellet burner in combination with solid fuel boiler FOCUS... It is a more economical technical solution with an inexpensive initial installation. It also meets the requirements for the use of ash granules. When using only pellets, turbolizers are installed according to the manufacturer's certificate.

What you need to know when installing a pellet burner in an existing boiler:

• The pellet burner can be installed in almost any floor standing boiler with comparable power. For these purposes, it will be necessary to make structural changes only to the unit door. FOCUS solid fuel boilers have two doors for operating the boiler in different modes.
• for efficient transfer of heat energy to the coolant, the boiler must have a developed heat exchanger with a sufficient contact area. For example, Focus boilers for 300 kW have a heat exchanger with a total area of 30 sq. m. At the same time, the surface of the lower grates and the combustion chamber is not taken into account in the heat exchange area, as other manufacturers do when calculating the power.

In this case, the following should be taken into account:

• does the solid fuel boiler have enough space to open the torch;
• Is the ash pan sufficient when using agropellets;
• what is the convection of the heat exchanger.

If the purchase is made inadvertently, the effect of overheating of the equipment can be observed. As shown in the photo.

Conclusion

When choosing a boiler for burning pellets, you need to pay attention to the technical solution. A pellet boiler is a heating equipment in which efficiency and high heat transfer depend on the thermodynamic parameters of combustion. If the equipment reaches the desired operating mode, then the afterburning of combustion products is ensured when secondary air is supplied with the expected increase in efficiency and low ash deposition on the walls of the boiler equipment.

The most effective, providing bulk combustion pellet burners are considered. At the same time, the equipment must have a built-in cleaning system; in practice, mechanical cleaning by shaking the grates is considered the most effective.

When buying a pellet boiler from a foreign manufacturer, pay attention to the recommendations for the use of fuel pellets. By default, pellets with EN Plus A-1 certificate and ash content 0.5-0.7% are used. Some foreign companies produce boiler equipment designed for operation with high-ash fuel.

Alternatives

What are the alternatives in Ukraine? Modular pellet boilers with gravitational fuel supply and rotary burner are available for Ukrainian buyers. This equipment has an air preparation chamber for air heating and is intended for heating small houses, offices, shops, kiosks, summer cottages and even apartments.

A feature of the equipment is a lower installation price, convenience and relatively low power compared to pellet equipment with flare burners. In order for the boiler to operate at rated power, you need to pay attention to the cleaning method when purchasing and follow the manufacturer's recommendations.

According to the certificate, pellets are more expensive, so consumers rarely rely on them. But they do not always pay attention to the features of the purchased equipment.

 

A detailed review of solid fuel boilers FOCUS

Go to the article about the types and characteristics of pellets

Go to Bulk Combustion Article

 

Choose a boiler FOCUS 50-500 kW

Select pellet burner FOCUS 17-900 kW

Buy pellet hopper

 

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