Boilers for wood chips and wood waste. Why choose wood waste boilers

Removal, processing and disposal of waste from 1 to 5 hazard class

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Wood waste is waste that is generated during the processing, disposal and use of wood. The sawdust boiler recycles this waste.

Wood debris is formed:

While working with the timber industry complex and wood processing plants.
When cutting low quality wood, tops, large branches and hardwoods.
When sanitary care for plantings in parks and squares.

It is worth remembering that a huge number of enterprises do not carry out the removal of wood waste, but use it as fuel. Such organizations place particular emphasis on sawdust, as they are an ideal source of fuel. Woodworking waste is an excellent raw material for the manufacture of various building materials. Such products are actively used in almost all spheres of human activity.

Classification

There are two main classifications according to which wood waste is divided. Depending on the production in which the waste is generated:

Harvesting waste is the detachable elements of the tree that are formed during the production of logging. For example, the remains of bark, needles and leaves.
Woodworking waste - wood waste generated as a result of woodworking production.

Based on the shape and size of the particles, wood waste can be divided into:

Lumpy wood waste - peaks, rail and short lengths
Soft wood waste - this includes sawdust and shavings

Export, processing and further use of each category occurs in different ways. So, in most cases, logging waste is sent for secondary processing, it can also be used to make wooden products like furniture, and solid fuel is made from lumpy waste.

Export of wood waste

The removal of such waste is carried out by special organizations, which then send it for incineration in a sawdust-fired CHP plant or to recycling plants. It should be noted that export as a way of getting rid of this type of waste is irrational.

There are two reasons for this:

Cheapness. Due to the glut of wood waste, the market value has dropped to a minimum. The cost depends on the specific region.
Transport costs. The cost of renting a vehicle can be higher than the profit received from the disposal of waste.

Disposal

In most cases, wood products are burned in order to use the released heat for space heating. This is the main and rational way to dispose of bark and other waste. For this purpose, you can take layer or swirl furnaces, dust burners, but the most successful solution would be to use boilers on sawdust and wood debris. With their help, you can even create gas generators on wood waste or mini-CHP, which will greatly save on heating.

A mini CHP plant operating on sawdust and wood waste is a thermal power plant that is designed to generate heat and electrical energy in mechanisms with a power not exceeding 25 mW.

Advantages

It is worth mentioning the advantages of a mini-CHP operating on wood waste and sawdust. Compared with other methods of heating, such as gas or coal, a mini-CHP using wood waste has a number of undeniable advantages.

Let's take a closer look at the main ones:

You can not depend on centralized heating networks and electricity. This is especially convenient in areas where there is no widespread electrification and gasification.
If a wood waste boiler house is intended for use in an industry whose waste is wood chips used as fuel, then it is possible to significantly reduce, if not completely eliminate the cost of other fuel materials.
Waste products will be used, so there is no need to spend money on their removal and further disposal.

In addition, it can be noted that reducing the cost of purchasing energy resources will help the development of production, because such an economical source of energy will make it possible to produce products that require significant energy costs.

Wood burning boilers

The basis for such a device as a wood waste boiler is a wood waste boiler. Boilers can be different, however, the general classification divides them into steam and hot water.

Waste and sawdust steam boilers, as the name suggests, produce steam by powering steam turbines. In this way, you can get electricity that can be used for heating and other technological needs.
The hot water boiler is used to supply the production hot water or heating.

In addition, there are a number of other criteria by which the classification is carried out:

Performance. For thermal boilers, it is called steam production and is measured in megapascals / cm 2. For water heaters, this parameter is called "heat performance" and is measured in megawatts. In part, the performance of such a device as a sawdust heating boiler depends on the type and quality of the material. So, one of the characteristics is the bulk density of sawdust.
The material from which sawdust boilers are made long burning. In most cases, such wood waste boilers are made of steel or cast iron.
Water circulation in hot water boilers, which can be once-through, natural, combined or forced.

If we talk about steam boilers, they are also divided according to the temperature of the steam they produce. Although a similar criterion can be observed in the water-heating type - the maximum temperature of the heated water is measured there. Here, too, the bulk density of sawdust can play a role. It is also important that the formula that specifies the ratio of wood chips, bark and sawdust is set correctly. To make sawdust boilers with your own hands, you will need knowledge in the field of physics, small skills and schemes.

Optional equipment

Of course, for the normal functioning of the system, the boiler alone will not be enough.

To create your own mini thermal power plant on wood waste, you will also need:

Warehouse for fuel storage
A device that transports chips from a warehouse to a boiler
Ventilation system for supplying fresh air to the boiler and removing combustion products
Temperature and smoke level sensors
Devices that clean the smoke coming from the boiler from ash and slag
Water Purifiers
Turbogenerator
A system that allows you to manage all processes in a mini CHP.

Although it seems that there are quite a lot of points, they are all extremely necessary in order for the power plant to be completely safe, because. it is based on a heating boiler using waste as fuel (bark, sawdust and other wood waste).

A thermal power plant operating on wood waste is in itself much more environmentally friendly than its counterparts operating on coal or fuel oil, special filtration systems will reduce air pollution by combustion products. This is another reason why wood waste burning with boilers is becoming more and more popular.

The use of wood waste

Use of wood waste from bark and wood as a secondary raw material:

Wood waste can be used to make useful wooden products, such as parquet or furniture.
Creation of building materials for thermal insulation and production of fiberboard, chipboard.
The remains of the bark are used in the field of pharmacology as a phytopreparation. Another way to use the remnant of the bark is in preparations for treating the skin.
The greens are used as fertilizer.
Large waste is used in the paper industry.
Small debris, such as wood chips, sawdust and bark, has proven to be an excellent fuel resource.
Devices for the treatment of polluted effluents with oil products operate on sawdust.

As a rule, only large organizations are engaged in recycling, while small ones prefer to take waste to landfills or for processing in order to generate additional income.

The UTPU-MT multi-fuel hot water boiler is designed to generate thermal energy by direct combustion in automatic mode without preliminary drying of high-ash (Ar up to 25%), wet (Wrel up to 55%) and dry (Wrel up to 10%) fuels with a maximum fraction of up to 250 mm at coolant temperatures 95-75 °С. Waste boilers use mechanized fuel supply from the "living bottom" fuel storage and automated removal of ash from the furnace using a screw conveyor

Automatic boilers of the UTPU-MT series burn waste:

Wood waste from furniture and wood processing enterprises: sawdust, wood chips, large-sized waste, chipboard waste, bark
Specialized waste: husks, peat, rice husks, bedding manure, coal
Pressed biofuels: briquettes, peat briquettes, pellets, eurofirewood
Solid household waste, plastic, MSW garbage, construction waste

Advantages of UTPU-MT boilers:

Multi-fuel, the boiler is able to burn almost any biofuel
Incineration of high-moisture waste due to the fuel drying zone at the inlet, mechanical movement of the waste along the grate and air supply to the furnace, heated in the lining circuit
Exclusion of overheating in the zone of docking with the hydraulic feeder due to the use of water cooling
Complete mechanization of the supply and removal of ash
Reliability of mechanized units due to their water cooling
Modular design: on the same frame with the boiler there are fuel supply mechanisms with a hydraulic pusher and ash removal mechanisms with a screeding bar, a blowing fan, a control cabinet
Ease of installation: delivered to a prepared site and connected to power supply, water supply and gas removal.

Technical description of the waste boiler:

Boiler furnace. Container type, complete with hydraulic fuel supply and ash removal, with fixed grate, lined fireclay bricks from operating temperature up to 1300оС. Provides layered combustion at a temperature of 1000 ° C.
Heat exchanger. Removable water pipe, with technological cleaning hatches, for manual cleaning of the outer surface of pipes from plaque and scale, with the possibility of installing automatic pneumatic cleaning of the outer convective surface. Pipes and heat exchanger body are made of special boiler steel.
The waste boiler is equipped with an automation and control system with boards based on Japanese OMRON microcontrollers with information output to the LCD screen and touch control. It is possible to prepare a computerized workplace with archiving and GSM informing.
Hydraulic mechanism for fuel supply of the boiler. Made of low-alloy steels, with a water-cooled circuit from the side of the combustion zone, a drive from a hydraulic station with a working pressure on the pusher, which guarantees the supply of large fractions of various fuels up to 250 mm in automatic mode.
Hydraulic ash removal system for boilers. Water-cooled screw bar made of heat-resistant stainless steel driven by a hydraulic station for moving fuel layers into the combustion zone and removing ash to a screw conveyor. The frequency of movement is set by the program depending on the ash content of the fuels and is automatically regulated to maintain the set temperature in the boiler furnace.

Modern trends require maximum efficiency from industrial wood processing enterprises in any process, but the issue is especially acute with waste processing. Firms that do not have time to adapt to a new format of work risk being left out of the market.

A powerful impetus to the industry was given boiler plants implemented as part of the import substitution program, and having affordable price unlike imported analogues.

Benefits of recycling wood waste

Waste woodworking (sawdust, lumpy waste slats, wood chips, slabs and wood dust) - in the end, taking into account deep processing, 60-70% of the volume of input raw materials. Therefore, the disposal of by-products of production is so in demand today.

Most industries get out of this situation the old-fashioned way, burning waste in stratified combustion boilers or in "potbelly stoves". In both cases, the process is accompanied by a large amount of soot, soot and other environmentally harmful emissions. harmful products combustion.

Others “litter” their production and nearby territories, creating a danger to the environment, forests and people living nearby, including due to the fact that recyclable materials can ignite spontaneously due to exothermic reactions occurring in their depths.

The situation is even worse with furniture production, where by-products from the processing of chipboard, MDF and fiberboard must be disposed of in special ovens or "burials", as they contain toxic phenols and formaldehydes.

Ideally for combustion at industrial enterprises, the Gefest gas-generating type boiler water heating plant is suitable.

Features of recycling processes

The process of environmentally friendly waste incineration in boilers includes:

complete decomposition of phenolic gases harmful to the atmosphere into carbon and hydrogen (flue gases) due to high temperature (>1200 degrees);
minimum amount of waste in the form of ash.

At the same time, waste and sawdust from sawmills, woodworking, carpentry and furniture production. This is especially true for the furniture industry.

Principle of operation

The operation of the wood waste boiler plant is based on the principle of gas generation. Gasification takes place in a special unit (gas generator) - thermal decomposition of wood into flue gas and hydrogen.

This method of utilization has the following advantages over layered combustion of fuel in conventional boilers:

high efficiency of boiler plants (up to 90%);
almost complete smokeless combustion of bulk fuel (ash content does not exceed 1 - 2%);
the possibility of recycling any by-products of woodworking production, including chipboard, chipboard, MDF;
installation of spark extinguishing and flue gas cleaning systems is not required;
ease of control - automatic mode of metered fuel supply;
durability - the life of the boiler without repair is up to 15 years;
automatic humidification of dry bulk fuel (relative humidity 35-55%) prevents heating of the gas generator lining, significantly increasing its service life without repair;
high maintainability of the gas generator;
the design of the water boiler eliminates the formation of scale inside the heat exchanger pipes, and also allows the use of equipment for water heating and heating;
characteristics of emissions into the atmosphere during combustion do not exceed the maximum permissible concentrations (MAC).

Advantages of KAMI

The environmental friendliness of the equipment is confirmed by a certificate based on laboratory tests. The data of the analysis obtained indicate that gas-generating boiler plants can be used even in cities, when burning chipboard, chipboard, MDF waste.

KAMI is the exclusive supplier of boiler equipment. On our site you can choose, compare specifications and buy the installation at competitive prices. Before ordering, consult with the company manager - he will help you fill out a request and help with delivery in Moscow and to any region of Russia, as well as advise on all types of machines that are in the company's nomenclature, including drying chambers and other types of industrial equipment.

Irrevocable combustible production waste is always of interest as a cheap fuel for industrial and domestic needs. During primary woodworking (cutting roundwood) such waste is sawdust, which is formed in considerable volumes.

Periodic removal or disposal of them translates into significant costs, and their permanent storage at the production site is fraught with sanctions from environmental and sanitary and epidemiological control authorities. The use of sawdust, taking into account their constant formation, for heating private houses and cottages looks very attractive.

Given the specifics of the fuel, it is useful to first carefully familiarize yourself with the characteristics and features of operation. In addition, a few words must be said about the fuel itself.

Fuel supply

So, for constant heating, sawdust should:

Formed in the volumes necessary for heating. It makes no sense to install such a boiler if there are not enough of them. This should be the first thing to pay attention to. For example, a 25 kW boiler consumes up to 40 kg of sawdust per hour during the heating season. On the other hand, an excessive amount of sawdust in the warehouse is also undesirable, since their storage sharply worsens the quality: sawdust becomes dense and damp, burns poorly with low heat transfer.
Get by cheap. Since sawdust is usually sold free of charge by the manufacturer, the only cost will be the transportation costs for delivering them to the house for heating. It should be borne in mind that they have a low density and are inconvenient for transportation.

Calculate how much it will cost you to deliver fuel, and what, accordingly, will be its price.

Fuel Requirements

The efficiency of the boilers directly depends on the moisture content of the sawdust. The use of dry shavings and sawdust from carpentry as fuel does not cause problems. The main mass of sawdust is, as noted, the waste of roundwood sawing shops.

Industrial waste sawing round timber on band sawmills are small (up to 0.3 mm) sawdust with a moisture content of up to 80%. Even with a constant forced air supply to the furnace, such sawdust burns very slowly, since it takes time to dry them. An even greater problem during combustion is raw, long-stored sawdust, compacted into a damp dusty mass.

Such fuel should be burned in a certain mode:

Dry and raw fuel must be supplied to the combustion chamber in a ratio of 3:1.
The supply of raw fuel can only be started when the boiler has reached full power after ignition.
Constantly forcibly supply air with a fan into the combustion chamber.

Advantages

The working process is based on the thermal decomposition of wood, called pyrolysis. In the smoldering mode, pyrolysis gas is released in the gas generation chamber, which then burns out in the combustion chamber under conditions of forced air supply.

The undeniable advantages are

High efficiency (up to 85-90%).
High profitability (up to 8-12 hours of heating on one boiler load). Pyrolysis boilers are 3-5 times more economical than classic wood-burning boilers, and 10-11 times more economical than gas boilers, with approximately the same heat release.
Rapid heating of the room (30-40 minutes) after ignition of the boiler.
Simplicity and reliability of a design.
Low fuel consumption.
Low fuel cost.
Possibility of switching to the mode of a conventional wood-burning boiler.
Independence of power from the grade of raw materials. The boiler, in addition to sawdust, can work on bark, wood chips, branches, wood.
Ease of maintenance and cleaning of the boiler.
Environmental Safety.
Ease of operation allows you not to spend money on expensive training of boiler room personnel.
Due to the low cost of sawdust and high efficiency, such boilers pay off very quickly.

Configuration options and operating principles

Consider several options for boiler equipment designed for heating a residential or country house.

Boiler plant

The most convenient and modern is an automated water heating plant that runs on sawdust, wood chips, shavings. If there is a large volume of the coarse-fraction part of the fuel, you can purchase a crushing machine for processing the coarse fraction into a fine one.

The installation includes the following nodes:

Fuel bunker
gas generator
Hot water boiler (combustion chamber and heat exchanger)
Automatic control unit

The design of the dwelling may provide for various options for placing equipment: completely outside or inside the room, as well as with the removal of individual units to the outside.

Description of the work process:

Sawdust is unloaded into the heating bunker by a dump truck (tractor, front loader). To prevent sawdust from caking, a tedder is provided in the bunker for their periodic loosening.
Through a conveyor (belt or screw), they are fed into the gas generation chamber, where, in the slow burning mode, thermal decomposition of the fuel occurs with the release of pyrolysis gas. Fuel is supplied to the conveyor and to the gas generation chamber automatically.

The pyrolysis gas coming from the gas generator into the combustion chamber burns out completely, heating the water. The content of unburned components in flue gases is minimal: carbon monoxide is only up to 1%, nitrogen oxides are up to 300 mg/m³. Hot air is supplied to the combustion chamber by a fan, which contributes to the deep burnout of the pyrolysis gas components.

The automation system controls the following processes:

Fuel supply to the gas generator
Hot air blown by a fan in proportion to the volume of fuel in the combustion chamber
The temperature of the coolant and its change
firefighting

Boilers on and sawdust HARGASSNER (Austria) are typical equipment of this level used for heating private houses, hotels, offices, cottages in Europe. The power of such boilers is 25 - 55 kW, the heated area is 200-600 square meters. m.

domestic producers

Domestic manufacturers also offer a wide range of sawdust and pellet boilers for heating individual housing and small industrial premises.

The offered boilers are mainly pyrolysis boilers operating in automatic mode. Technologically, the combustion process is similar to the one above. The only difference from imported equipment is that Russian boilers, as a rule, are not provided with automatic fuel supply lines.

Automation regulates the operation of the blower fan for a stable set temperature of the coolant, which is set by the control units. In case of scheduled or emergency shutdown of the fan, the boiler continues to operate at reduced power. The filling of sawdust, shavings and other wood waste burns out in them within 4-12 hours, depending on the selected combustion mode.

Long-burning mine boilers

Mine long-burning boilers (Kholmov's boilers) deserve special attention. These are pyrolysis boilers of a special design. Their constructive advantage is that the fuel placed in a special shaft partially dries up, which makes it possible to use high-moisture sawdust for heating.

Automation (controller) controls the combustion process, the set coolant temperature and the operation of the centrifugal pump.
The safety system is provided with an emergency boiler cooling circuit and a safety valve.
Maintenance of the boiler takes a few minutes 1-2 times a day.
The use of such boilers allows you to heat cottages and small industries with an area of 60 -250 square meters. m.

Own designs

The design of such boilers offers a lot of home-grown "homemade" ones on the network. Without focusing on creative innovations in the advertised devices, we note that such equipment cannot be reliable and durable, in principle.

The materials from which it is made most often do not meet the operating conditions, the structures themselves are primitive, they lack the most elementary automatic control and security systems. At the same time, a fully equipped factory boiler for sawdust or pellets with a capacity of 20 kW, with a guarantee, capable of heating a cottage or country house, costs only about 40-50 thousand rubles. Agree, this is not the amount, saving which you can risk your own health and housing.

Boilers operating on sawdust and other woodworking waste are today the most cost-effective equipment for heating private houses. When deciding on the choice of such equipment, special attention should be paid to the availability of the required volume of fuel that meets the moisture content. If it is planned to burn sawdust with a moisture content of more than 55-60%, then they should not exceed 20-25% of the material loaded into the furnace. The main fuel should be wood waste with a moisture content of up to 20%.

It is very important for owners of private houses to have a stable heating system, the main indicators of which will be: safety, reliability, convenience and reasonable cost.

The best choice would be to install a boiler for a long-burning house. One of the most accessible and diverse types of fuel is solid fuel.

To automatic solid fuel boilers long burning can be attributed units on wood waste. They can be used as the main or only source of heat in the heating and hot water supply (DHW) system.

The use of such boilers can be domestic and industrial.

The principle of operation of boilers on wood waste

A bunker is installed next to the boiler, into which they are loaded wood materials. Fuel from the bunker is fed into the boiler by means of an automatic conveyor. The unit burns fuel, and the released heat is transferred to the coolant using a heat exchanger.

The principle of operation of a long-burning boiler is the layered combustion of fuel, and the combustion zone moves from top to bottom.

Types of wood waste incineration:

Direct combustion is the combustion of fuel directly on the grate. Accompanied by high combustion temperature. It is used in low power boilers (up to 20 kW) for fuel with high humidity.
Combustion in a fluidized (circulating) bed is provided by supplying a strong jet of air from the bottom up, as a result of which the efficiency of fuel combustion is increased and the amount of harmful emissions is reduced.
Gasification (burning of gases) is the process of release of volatile substances from solid fuel under the influence of high temperatures and their subsequent incineration.

Read about the use of electric boilers in.

You can read about universal burners for liquid fuels here -

Also learn about the principle of operation, brands and main characteristics.

The design of long-burning wood-fired boilers

The unit includes in its design:

Fuel bunker.
Fuel conveyor.
Firebox.
Burner.
Heat exchanger.
flue.
Ash collection.
Fans and smoke exhausters.

Types of heat exchangers for solid fuel boilers

Heat exchangers are of two types:

Cast iron heat exchanger has a service life of up to 40 years. It has a large wall thickness, which complicates its heating, but after complete heating, the metal retains heat for a long time. The main requirement for operation cast iron heat exchanger is compliance temperature regime. Can't be added cold water to a hot heat exchanger.
The steel heat exchanger is not so picky about temperature distortions, but is more susceptible to corrosion, so the service life is significantly reduced - up to 20 years.

Gas boilers for sawdust and wood chips

The main difference between gas generating boilers is the type of fuel combustion. For combustion, a firebox is used, divided into 2 chambers.

In one of them, sawdust or wood chips are thermally treated, as a result of which combustible pyrolysis gas is released, which is burned in another chamber.

Construction of a gas generating boiler

The main design difference is the presence of two chambers in the furnace. In the fuel thermal treatment chamber (combustion chamber) is installed electric heater. It is needed for the initial heating of the air in the furnace after the first load.

The presence of electric heaters makes it possible to automate the process of ignition of the boiler. The second part of the furnace is called the gas afterburner.

Unit functionality

Boilers are divided into two types: single-circuit and double-circuit.

A single-circuit boiler provides heating of the coolant for the heating system.
A double-circuit boiler simultaneously heats the coolant for the heating system and water for the DHW system.

Read about the automatic control of the power of the burner of heating boilers.

Information about the automatic safety of the gas burner can be found at the link -

Advantages of solid fuel boilers for long burning

Units on wood waste (sawdust) are in high demand in those areas where there are difficulties with the supply of gas or electricity. Their main advantages:

Possibility of burning fuel with high humidity (up to 90%).
Automatic fuel supply.
The amount of harmful emissions is kept to a minimum.
Boiler automation.
Possibility of work on one loading of the bunker.

Disadvantages of sawdust boilers:

If a large piece of wood is caught in the sawdust, the screw conveyor will jam.
In smoldering type boilers, there is no possibility of additional loading of the fuel hopper during operation.
The increased moisture content of the fuel affects its calorific value, which reduces the efficiency of the unit.

Brands of automatic solid fuel long-burning boilers

Model	AGGU-60	AGGU-120	AGGU-250	AGGU-600
Rated thermal power, kW	60	120	250	600
Heat carrier temperature, С°	up to 95°	up to 95°	up to 95°	up to 95°
Heated area (height 3.5 m)	400 m²	800 m²	1700 m²	7000 m²
Drying chamber volume	up to 15 m³	up to 30 m³	up to 60 m³	up to 150 m³
Consumed amount of fuel:
– bulk volume of sawdust (chips), m³/day	2.5÷3.0	5.0÷6.0	10.0÷12.0	25
– volume of lumpy waste, m³/day	1.75÷0.95	1.5÷1.9	3.0÷38	7
Power consumption, kW	0,55	0,75	1,1	2,5
Hopper volume, m³	0,6	1,5	1,5	1,5
Dimensions of the room for EC, m	4.0×5.0×2.5	4.5×5.5×2.5	4.5×6.0×3.0	5.5×7.0×3.0
Weight, kg	1300	1950	3000	6000

Waste-fired industrial boilers:

Brand/parameters	KVm-0.2	KVm-0.3	KVm-0.4	KVm-0.6	KVm-0.8	KVm-1.16	KVm-1.5	KVm-2.0	KVm-2.5
Length, mm	2300	2600	2600	2850	3400	3400	3500	3500	4700
Width, mm	1450	1450	1650	1900	1900	1900	1900	2150	2150
Height, mm	2650	2800	2800	2800	2800	3000	3550	3550	3650
Heat output, MW	0,2	0,3	0,4	0,6	0,8	1,16	1,5	2,0	2,5
Weight, t	3,8	4,2	4,5	5,2	6,0	6,6	7,4	9,0	10,5
Fuel consumption, kg/h	107	161	214	322	429	623	806	1075	1344
Efficiency, %	At least 84
Air supply	Forced blow

Types of fuel for waste boilers

The following types of fuel are suitable for boilers:

Sawdust - characterized by high humidity, but affordable price.
Pallets are compressed waste from the woodworking industry. Differ good performance and are efficient at burning, but more expensive than sawdust and firewood.
Wood chips are logging waste.
Grain waste has a high calorie content.
Other biofuels: straw, sunflower husks and others.

Automatic fuel supply

The fuel supply system operates in automatic mode and consists of two elements: a fuel hopper and a conveyor.

The intensity of the fuel supply is regulated by the automatic system depending on the set temperature.

A modern long-burning solid fuel boiler has a reliable automation and protection system that will ensure heating of the coolant without unnecessary worries. This fuel has a more affordable price than analogues, therefore it is in demand.