Peat and wood pellets – the fuel of the future from production waste

Peat and wood pellets

An environmentally friendly type of solid fuel, called pellets, is not widespread in Russia, unlike Europe. At the same time, a significant proportion of heating boilers for country houses, stoves and fireplaces have recently been developed by manufacturers precisely taking into account the use of this type of biofuel in them. Peat or wood pellets are considered the most promising alternative to coal and gas..

Content

• Fuel pellets and their application
• Varieties of pellets
• Production technology
• Is it possible to independently produce pellets

Fuel pellets and their application

There are plenty of regions where there is no centralized gas supply in Russia, and these are not only detached suburban houses, but also entire settlements and summer cottages. If the Russian hinterland can solve the heating problem in such conditions in the old fashion of cutting and harvesting firewood for the winter, then settlements located closer to large cities are deprived of such an opportunity. The search for alternative fuels in such areas is relevant..

Also, the problem of finding fuel arises among the owners of cottages and country houses, who decided, in addition to batteries, to build a fireplace in order to enjoy the contemplation of a live fire in the evenings. Pellets in such cases are a real salvation: with low ash content and minimal gas emission from combustion, they are characterized by high heat transfer. Compared to unprocessed wood, pellets are 3-10 times drier: pellet moisture does not exceed 10%, and firewood rarely reaches a moisture content of 30%. The calorific value of pellets is also in favor of the latter: when burning, the difference in density by 1.5 times turns into the same figure in comparison of heat transfer.

In addition to using wood pellets as fuel in water heating boilers, small boiler rooms, fireplaces, stoves and barbecues, there is another application:

• as an absorbent for emergency absorption of liquids;
• as filler in toilets for pets.

Varieties of pellets

Visually, pellets differ in size and color. The average pellet diameter is 0.5-1 cm with a length of up to 5 cm, which distinguishes this fuel in transportation, which is usually carried out in ordinary waterproof bags. The flowability and uniformity of the material eliminates manual labor in the production and packaging of granules. The color of the granulate depends on the material used to create it and on the production method. Material for creating pellets can be:

• peat;
• sawdust;
• round processing waste together with bark;
• waste from the processing of cereals and husks of sunflower seeds;
• chicken droppings;
• straw.

The latter species are not widespread, due to the low profitability of production. The most popular types of pellets are wood. It is not difficult to distinguish sawdust pellets created from good coniferous wood, they are given by a golden-honey color and the smell of fresh saw cut. Wood pellets made from trimmings with bark give a gray tint. The process of their production consists in pressing the crushed biomass without adding adhesives, only under the influence of high pressure.

The manufacture of black pellets is slightly different: the method called “torrefaction” or “frying” consists in slowly heating the mass in the absence of oxygen. Such pellets in appearance and properties differ little from charcoal. Black wood pellets are visually less attractive compared to white ones, but have several advantages:

• ash content within 1%;
• moisture resistance;
• increased heat transfer due to material density.

At the cost of production, black fuel pellets are significantly inferior to pressed pellets, since they require additional equipment for heating the starting material.

Peat pellets are made from peat lying on the surface of marshlands by pressing after drying. The technique also does not require heating of the material and the use of adhesives. This technology is considered one of the most promising in terms of the development of peat deposits, which causes a lot of trouble in the summer, being a frequent cause of large-scale forest fires. The industrial development of these fields, planned for the coming years, will be profitable both commercially and environmentally.

Production technology

All pellet manufacturers use a single technology consisting of several main stages:

• cleaning and sorting of biological raw materials;
• drying;
• crushing, sometimes passing in several stages and alternating with additional drying;
• steam treatment to release natural adhesives;
• granulation under pressure;
• cooling;
• cleaning and packaging of the finished product.

In Europe and America, there is a single standard to which fuel pellets sold in the relevant territory must comply. It strictly limits not only the size of the granules, but also their moisture content, the content of impurities and associated dust. In Russia, such a standard does not exist yet, and most of the products are sent for sale to Europe, where the demand for it is much higher. Therefore, wood pellets of domestic production, as a rule, are created according to the German standard DIN+.

Is it possible to independently produce pellets

The advantages of pellets as an economical and environmentally friendly fuel have already been appreciated by many owners of private households. At the same time, the product itself can hardly be called cheap: despite the availability of raw materials, which are often emitted by wood processing enterprises, the production of granules is costly.

It is profitable to buy pellets pellets only in large batches, receiving a discount for a bulk order from the manufacturer. Owners of private households, whose pellet consumption is low, see a way out in creating their own mini-factory for the production of this type of fuel.

Do-it-yourself pellet production is possible with the purchase of the necessary equipment. For home-made pellets, sawdust is most often used as the most affordable material. It does not cause great difficulties during drying and does not require additional crushing. The main difficulty in the handicraft production of sawdust pellets is the granulation process. Buying a granulator, as a rule, imported, is not difficult, but Russian craftsmen adapted themselves even to make such equipment. The basis is a flat or annular matrix, which is a form for granules, a pressing mechanism is welded to it. A standard electric motor drives the structure. Such an apparatus is capable of providing a decent volume of product, sufficient not only for private use, but also for implementation.