Build Daily


August 12, 2017 18:06

All of the pellets : production rules , standards and methods of quality control

this article, you'll learn all about pellets: production rules, standards and methods of quality control.To ensure stable operation of the pellet heating boilers, which are often installed in the boiler operating independently, need the "right" pellets.This English word means small pellets, which are prepared by compression of the wood meal.Raw material is very simple for this fuel.It can act as oshkurennaya not oshkurennaya wood waste from sawmills, large or small woodworking companies and furniture industries.

Manufacturers such alternative solid fuel mastered even agropellet issue of ordinary straw, sunflower husks, corn, buckwheat husks, etc.When transporting the pellets and their storage is necessary to observe a number of requirements, which is much softer than the rules that apply to liquid and gaseous fuels.Therefore, the popularity of solid-fuel heating boilers for pellets is growing significantly among individual owners of suburban housing.When buying such a granular fuel all consumers inter

ested in its properties and quality, as this depends on the performance of all of the boiler equipment and the percentage of efficiency.The main influence on the quality of pellets has the raw materials, the organization of the production cycle, the conditions of storage of the final product and its delivery to the consumer.

essence pellet production

Forming these small pellets under a high pressure of 300 atm, and under the influence of heat.In the process of the crushed mass interesting stuff is released, which is called lignin.It provides high-quality bonding of the individual pieces of material into granules.The length of a pellet may vary from 10-30 mm.Diameter pellets are from 6 to 10 mm.No wonder they are referred to environmentally friendly types of solid fuel, since only natural materials are used in their production.During the combustion of solid granular fuels, pellet boilers maximum amount of carbon dioxide that enters the atmosphere is negligibly small.Degradation of natural wood in vivo release is accompanied by the same amount of carbon dioxide.Pellets - environmentally friendly and very cost-effective fuel for solid fuel fireplaces, furnaces, boilers

Pellets - this is the most eco-friendly and very economical fuel for home heating stoves , fireplaces , solid fuel boilers

Pellets - this is the most eco-friendly and very economical fuel for home heating stoves, fireplaces, solid fuel boilers

What are the different varieties of pellets

substantially in the worldclassification of fuel pellet granules are divided into three main groups:

  • White pellets - also called premium fuel that is suitable for use in high-tech heating boilers.
  • Dark or different industrial pellets, which are somewhat inferior to the first group of quality.In them, the course is not only the timber but also the bark.This fuel is suitable for burning in conventional pellet boilers, but require more frequent ash removal.
  • Agropellety considered the cheapest fuel in standard quality.They burned in boilers, which are made specifically for this type of coarse solid fuel.

Calorific value of white and dark pellets no different: 17.2 MJ / kg, and at agropellet is slightly lower - 15 MJ / kg.Ash products is 0.5% premium dark - about 0.7%, and sometimes even higher agropellety left after burning most of the ash - 3% or more.

It looks solid fuel boiler with automatic feed pellets

It looks solid fuel boiler with automatic feed pellets

Excellent flowability of dry pellets is best achieved their cylindrical shape and specific physical and geometrical characteristics, such as abrasion, density and bulk density.Due to these qualities, such fuel can be automatically fed through the special auger device that is used in the boiler.Automation of the fuel supply to the heating boiler maintains its long-term operation without active human intervention.Therein lies the main secret of success of pellets in most European countries.

The main stages of the manufacturing process

pellet production can be easily represented in the form of several distinct phases:

  • prepared by grinding the raw material;
  • drying shredded ready-made components;
  • regrinding already thoroughly dried particles;
  • raw water treatment with the aim of dampening produced wood flour;
  • compacting crushed and already moistened raw materials into finished granules;
  • cooling pellets and blowing cleaning them from dust;
  • packing pellets and their packaging.

well to understand this process, it is necessary to consider in more detail each of these stages.

Stage grinding of raw wood

With special chippers which are called grinders, milling ensured harvested wood raw material to these factions, the length and width of not more than 25 mm, and a thickness of only 2 mm.Then the chopped raw material is dried.Moreover, the smaller size of the obtained fractions after crushing, the less power is necessary for drying them.

So look for a pellet mill

So look for pellet mills

step further drying and regrinding

humidity level of wood raw material, which is sent by the press, not to exceed 10% with a tolerance of 2% in either direction.If the resulting materials will be too wet, always will require additional energy-intensive drying.If part of the wood used to be too dry, they need to moisten a bit in order to achieve a 10 per cent humidity.

Dryer pellet pellets

Dryer pellet pellets

driers producing drum and belt type.This latter option is the preferred, though expensive.The use of belt-type dryers for pellets is much safer.Dryers can run on gas or on the same wood waste.There is also a division according to the type of equipment used for drying unit.It usually act as: hot air, steam or flue gases.Stable operation of pellet press is possible only when the size of the input fractions in raw materials will not exceed the allowable 4 mm.Well re-dried raw material is subjected to special grinding hammer mills, looms in particle or disintegrators.

Water feed

If the moisture level of raw material does not hold up to 8%, it is very difficult to give in compression.To obtain the required degree of humidity, you need to skip over dried raw materials through additional moistening device.An excellent option considered mixers augers, which are supplied hot steam or water.Steam is generally used in the processing of raw wood material, which is derived from hardwood.Under the influence of hot steam greatly reduced the strength of the wood itself, and significantly increases its plasticity.Press some manufacturers are arranged so that they do not need to pre-steam the impact of raw materials.Some are not very conscientious manufacturers use steam to process too old and already the settled material.At the same time, get a high-quality pellets "reanimated" in such a way so raw and so will not succeed.

pressing process The flow of the process of the granules is carried out by means of special presses, which have different designs, mainly in form of matrix.There are pellet presses:

  • With round type of matrix, which had previously been created for use in the food and chemical industries.They are also used for the production of animal feed.
  • With flat-type matrix created for the disposal of solid waste.

Despite significant structural differences, those and other media carried out work on the same basis.In these running rollers crushes raw materials supplied to the die, providing its indispensable punching through provided holes for this purpose on its surface.Appeared out of the matrix pellets are cut with special knives sharp.During the entire process of compaction such equipment fails to condense the initial feedstock tripled.

The process of formation of pellets using a cylindrical press matrix type

process of forming pellets using a cylindrical press matrix type

friction forces that under adiabatic thermodynamic process caused a very sharp contraction of raw materials, contribute to a significant temperature rise in the operating section of the press up to 100 degrees.So just 30-50 kWh of electricity consumed for the processing of tons of raw materials per hour.When wood pelleting plants Equipment experiencing tremendous constant load, so it is made of high-strength materials.Some details like matrix produced from specially hardened wear-resistant alloys.

finished pellets Cooling and cleansing them from contamination

pressure and temperature in the area has a strong influence on the quality of the finished fuel.For this reason, the raw material should not be heated above 120 degrees, as this facilitates the beginning of irreversible processes in its structure, all of which greatly reduce the fuel consumption characteristics.Therefore, already compacted pellets be cooled.For this purpose, the conditioning equipment is for one and blows the dust from the granules.

pellets Packing and packaging

pellet can pre-pack and packaged in different ways.This would greatly satisfy the needs of all consumers.Pellets are shipped loose in a fully free or very bulky bags, which are sometimes referred to as "big bags" (can accommodate from 500 to 1200 kg).

The circuit elements of the polymeric bag ( Big -Bag )

Driving elements polymeric bag (Big-Bag)

Bulk often shipped fuel pellets that are sent to large CHP.Although it is possible and shipment of bulk pellets with high quality.Their purchase for use in small businesses or boilers available for sale, after filling in small bags."Big-bags" are plastics bags, which are equipped with durable slings for mechanization of loading and unloading.Pellets, which are stored and transported in bags, absolutely does not lose its flowability and maintain the necessary level of humidity.The acquisition has already pre-packaged pellets naturally more expensive ordinary consumer.

Specially equipped trailers for the transport of big bags with granules

Specially equipped trailers for the transport of big bags with granules

big bags are transported on special automotive platforms on which they loaded truck.But the bags of 10 - 20 kg is also enjoying success, but from private owners of solid boilers.The owners of pellet boilers and fireplaces that do not have space for large stocks, purchase them in small packages.So sell selected quality wood pellets.

Small packing the choicest white pellets

small packing the choicest white pellets

By what standards determine the quality of the finished pellets?

all domestic producers of pellets quality standards used today, which are accepted in most European countries.Foreign manufacturers of solid fuel for pellet boilers must obtain certificates of conformity for its products according to current EU standards.If such a document is missing, this fact discourages buyers.Quality standards EN plus and EN-B are fixed requirements as to household and industrial pellets according to several criteria.These include: diameter, lengths, bulk density, combustion heat, humidity, abrasion dust or percentage, hardness, ash, ash fusion temperatures, and the metals content of other chemical elements.

How to choose pellets?

When buying pellets ordinary citizen should pay attention to the presence of a quality certificate.In addition to this important document, you need to find out the place where they were manufactured pellets.Large manufacturers have contracts with regular suppliers of raw materials, the peculiarities which set all the manufacturing equipment companies.Therefore, the pellets have to be better.Visual inspection of the pellets also helps to determine the suitability of products for specific pellet boilers.When such control is necessary to pay attention to the color of the pellets themselves, dimensional stability, the amount of remaining dust pellets integrity, absence of odors and others. You can order laboratory tests and highly efficient fuel pellets for their full compliance with European quality standards.Naturally, the service rendered can afford only companies that have established solid fuel boilers.