Charcoal is one of the oldest types of fuel. It is used not only for cooking and home heating. It is used in the chemical and metallurgical industries, in livestock and construction, medicine and pharmacology. Today, the bulk of charcoal is produced in small enterprises. Charcoal production and sale is a profitable business in areas where forests grow, and you can even organize it on your own suburban area.
Charcoal process
As wood raw materials, not only firewood of various types of wood is used, but also waste from woodworking or furniture production: knots, hemp, sawdust. In marshes peat is used.
In the process of carbonization, wood goes through three stages: preliminary drying, thermal decomposition and cooling.
The initial drying and heating of the raw materials in the chamber occurs due to the heat supplied from the outside. The own process of heat generation (chemical exothermic reaction) begins when the wood temperature reaches 280 ° C. Further supply of heat is no longer needed.
After burning, the finished coal is cooled to a temperature at which spontaneous combustion of coal is impossible, i.e. below 40 ° C.
During the first day in the mixture of flue gases and carbonization products there are still a lot of water vapor that is released during the drying process. Then the mixture becomes drier and can be used as additional fuel in the same furnace or, more efficiently, in a nearby one.
Coal Burning Equipment
Charcoal furnaces of various capacities are used for the production of charcoal. Such coal is obtained in the process of pyrolysis, that is, the wood is burned without oxygen.
Charcoal furnaces for the production of charcoal are available stationary and mobile.
Stationary equipment is used by large enough manufacturers for the continuous pyrolysis process of large volumes of wood.
Large furnaces are much more productive than mobile ones; several types of fuel can be used in them, but high environmental safety requirements are imposed on them.
Mobile furnaces are inefficient, small in size, and are used either in places where there is raw material, for example, in forestry areas, or where the final product is needed, for example, at construction sites.
In mobile furnaces, the same wood waste is used as fuel from which coal is produced.
If the furnace operates on waste, then the benefit is twofold, and coal is produced without additional fuel costs, and waste is recycled that would still have to be disposed of, spending time and money on it. This type of charcoal production is the cheapest.
Continuous coal burning equipment
A separate group consists of charcoal burning furnaces, in which the flue gases from the burning fuel enter the chamber, pass through the wood, attach fumes and gases, which are products of drying and carbonization of wood raw materials, to the outside. In them, the pyrolysis process proceeds most evenly, since the wood is in direct contact with the coolant supplied from below. But pyrogases contain a large concentration of chemical compounds that are products of the decomposition of wood, so you need to install additional equipment for the beneficial use or incineration of by-products of pyrolysis.
This is how continuously operating vertical retorts work, in the chamber of which the wood at the top is dried, pyrolysis takes place in the middle layer, calcining of the coal and its cooling at the very bottom.
Carboniferous furnaces with replaceable containers or retorts work continuously. The principle of operation of such plants is that each subsequent batch of raw materials is heated to the required temperature due to the exothermic reaction in the previous one.
In this case, the process of coal formation occurs in each retort independently of the others, and the furnace, into the furnace of which pyrolysis gases are removed, is located separately from the interchangeable chambers.
Retorts and pyrolysis chambers are made of metal with thermal insulation.
Periodic cycle coal burning equipment
The simplest design of an incinerator is an ordinary two-liter metal barrel into which wood is laid and set on fire. Additional heat is not supplied, and combined-cycle gases are removed through a special small hole. The production of low-quality coal, with output less than fifteen percent, is dirty, but practically costless.
Today there are designs of charcoal stoves in which the walls of the chamber are heated with the coolant, from which heat is transferred to the wood in it. These are, as a rule, charcoal-burning furnaces of a periodic cycle, where, at certain intervals, the whole process of burning coal takes place: firewood is loaded, charred, finished coal is unloaded, firewood is loaded again, and so on.
In mixed-action apparatuses, wood is loaded periodically and finished coal is unloaded, but some part of the wood is constantly in the process of pyrolysis.
Furnaces can also be made of metal or brick.
Three-chamber charcoal kiln
The gas-vapor mixture, which is discharged from the pyrolysis chamber, condenses upon cooling. Pyrolysis liquid (liquid) and non-condensable gases, since they are not widely used, are used as additional fuel in the combustion chamber. The conclusion of by-products for afterburning is provided by the design of the furnace. The effect of this design is not only in fuel economy, but also in environmental protection.
Three-chamber charcoal furnaces provide a continuous cycle of coal production. In each chamber, one of the stages of the cycle passes separately, and the initial drying of the raw material occurs due to the heat that is obtained by burning pyrolysis gases. In addition to fuel economy, such furnaces have many other advantages. Since the loading of wood and the unloading of finished coal occur at different times, the maintenance staff is more evenly loaded. The cost of a three-chamber furnace is lower than a single-chamber furnace of the same volume, and the efficiency and service life are higher due to load distribution.
Such equipment is designed for long-term operation in large industries, and if it is equipped with a gas-generating boiler, then sawdust and shavings can be used as fuel.
Single chamber charcoal kiln
Charcoal in small quantities (up to 8 tons per month) can be produced in a single-chamber furnace. The full production cycle depends on the model of the device and may take 1-3 days.
Such a furnace can be used in private households, in public catering establishments, with the goal of utilizing industrial wastes and substandard products in small woodworking enterprises.
The principle of production in them and large industrial furnaces is no different. Single-chamber furnaces are usually smaller in size, the raw materials are also loaded less, but they also take up less space and are easy to transport if necessary.
Overseas, there has long been a production of charcoal stoves for home use. Grilled or barbecue dishes are cooked on organic charcoal.
Characteristics and design of a charcoal kiln
Manufacturers of carbon-burning furnaces, both foreign and domestic, indicate the working volume of one chamber and the total number of chambers in the furnace as the first characteristics. Then, usually the volume of firewood with the specified dimensions and humidity is indicated, which can be loaded into the furnace at a time. This indicator is important for observing the following parameter - the duration in hours of the main duty cycle.
To determine the performance of a particular model, two parameters are set for wood of the same species - the estimated amount of firewood loaded into the pyrolysis chamber and the output of coal from them.
The dimensions of the furnace and its mass are indicated last. If the device is not intended to be transported, this data may not play a special role, but during transportation it can become decisive.
As a rule, a household single-chamber furnace is a metal barrel stacked with a slight slope or mounted on a support with a firebox built into the bottom.
The furnace itself, the furnace body, the duct box and the hatch door are made of steel with a thickness of at least 3 mm, and the outer skin is 1 mm.
The double-sided welds that connect the shell shells are reinforced with bandages that are made of a rectangular pipe, give structural rigidity and additional strength if pressure suddenly rises in the tank.
To reduce heat loss, a heat-insulating material is laid between the camera body and the outer skin. This measure increases the efficiency of the furnace. The walls of the furnace are laid out from the inside with refractory bricks.
Carbon afterburners may be supplied separately.
DIY charcoal stove
The barrel on the stand is the simplest design, but for greater efficiency and fire safety, the barrel must be installed on a non-combustible base or buried in a pit.
From brick or metal, you can independently make charcoal kilns. The drawing can be found on the Internet, as, however, are quite detailed descriptions. However, one must understand that the quality of a home-made furnace and the final product is much lower, and there will be no large amounts of coal.
At the summer cottage, you can make a coal pit, or you can build a charcoal stove from barrels. To do this, dig a hole of such a diameter so that a barrel is placed in it, which still needs to be bricked, cut a hole with a diameter of about 100 mm in the bottom of the barrel and put it in the hole with the hole down.
Then you need to cover the barrel with bricks, close the cracks at the top with some fireproof material, and insulate the upper bottom with mineral wool. That's all, you can get your coal for the fireplace and barbecue.
The design of two barrels is more efficient and reliable. A container, which is two times smaller in volume, is put into a large one, filled with firewood and tightly covered with a lid, and finely fractioned wood waste is poured into the space between the walls and set on fire, then the big barrel is also closed with a lid into which the pipe is inserted. But both of these furnaces are suitable for use only outdoors and far enough from them.