The need for the use of economical fuels has been long overdue in the world. For example, pyrolysis gas is already widely used in Europe today. All sorts of kitchen equipment, heating installations and even cars can run on such fuel.
Definition
Actually, under the very concept of "pyrolysis" chemists understand the decomposition of a substance at the molecular level under the influence of high temperature, usually in the absence of air. Complex compounds under such conditions decompose into simpler ones. In this case, various kinds of new elements are formed in the medium. Essentially, pyrolysis is thus a conventional dry distillation process.
Gas from firewood
When fuel is burned at high temperatures in an oxygen-free environment, the following combustion products are formed:
- pyrolysis gas;
- pyrolysis resin (liquid product).
The first product from the list has, among other things, the feature that can also be formed during the combustion of fuel in an oxygen environment. However, in this case, gas can be obtained only if the fuel is burned at a temperature not lower than 500 °C.
Which products can be used
Pyrolysis boilers in homes can run on ordinary wood or special pallets, such as sawdust or pressed wood shavings. Various types of household and industrial waste can also be pyrolyzed. It is burned in a similar way, for example, rubber, old car tires, plastic, old things, etc. In this case, pyrolysis allows not only to get a certain amount of heat, but also to keep the environment clean. After all, as you know, plastic does not decompose in the ground for a long time. Oil-containing materials of various kinds pollute both the soils themselves and water bodies.
Also can be burned in a similar way:
- paper, cardboard, textiles;
- methane;
- hydrocarbons;
- peat;
- commodity wood (including chemically impregnated wood);
- straw, leaves, nut shells, weeds.
In addition, paint residues, oils, etc. can be recycled through the pyrolysis reaction. This also helps to keep the environment clean.
Composition
The resulting pyrolysis gas contains, among other things, a lot of particulate matter, usually in the form of soot. It also contains various kinds of chemical components, for example, hydrogen. However, the mainthe composition of the pyrolysis gas is still as follows:
- volatile hydrocarbons;
- carbon monoxide.
Very dangerous for human he alth and even his life, CO in such a reaction is formed due to incomplete combustion of charcoal.
Types of pyrolysis
At the moment, there are only two main types of such reactions. Pyrolysis can be:
- dry;
- oxidative.
The first type of reactions, in turn, is divided into:
- low temperature;
- high temperature.
How gas is produced: oxidative pyrolysis
This reaction is called the most environmentally friendly and productive today. Pyrolysis occurs in this case at very high temperatures. For example, when methane is burned in this way, a certain percentage of oxygen is mixed with it. With partial combustion, the substance in this case releases a huge amount of energy. As a result, the remains of the mixture are heated to a temperature of 16000 ° C.
The reaction of oxidative pyrolysis is mainly used to burn various industrial materials containing oil, as well as plastic and rubber. Gas in this case can go, for example, to heat the shops of the waste disposal company itself.
Dry pyrolysis
This reaction occurs without the participation of oxygen and, as already mentioned, in turn, can be low or high temperature. In the first casethe fuel is heated up to a maximum - up to 1000 ° C, in the second - above 1000 ° C. To obtain a large amount of pyrolysis gas itself, high-temperature reactions are mainly used.
When fuel is burned in an environment up to 800 °C, quite a lot of gas with a low calorific value is obtained. Also in this case, a fairly small amount of coke and liquid resins remain.
The most appropriate is to obtain pyrolysis gas at a temperature of 900 to 1000 °C. In this case, there is already a maximum percentage of its production. In this case, the gas obtained in this way has a minimum calorific value. Such a product is considered, among other things, high-quality fuel, suitable for transportation over long distances.
When fuel is burned at temperatures between 450 and 500 °C, the output is very low in both solid residues and gas. The latter, however, is not of high quality, since it has the maximum calorific value.
Where gas can be used
The pyrolysis process thus allows heating various kinds of premises with the least fuel loss. Also, by using this reaction, the environment is kept clean. But where can the pyrolysis gas formed during the combustion of fuel in an oxygen-free environment be used?
This combustion product today is considered worldwide primarily as an alternative economical source of thermal energy. In some European countries, pyrolysis gas has long been commonfuel used by equipment that heats water (for heating and hot water systems), electricity, steam.
Boilers
Since ancient times, people have heated their homes using conventional stoves that operate on wood and coal. Later, houses began to be equipped with modern solid fuel boilers operating on the same type of fuel. Such units are used to heat homes in our time. They are inexpensive and for their installation it is not necessary to obtain permits in various instances. However, conventional solid fuel boilers have one rather serious drawback. They consume fuel extremely uneconomically. A lot of combustion residues remain in the chambers of such units. In addition, part of the heat generated by such equipment simply flies "down the chimney" along with the smoke.
Engineers who decided to correct this minus of solid fuel boilers, and eventually came up with pyrolysis heating units that are economical and easy to use. In such boilers, among other things, there are additional chambers in which the afterburning of pyrolysis gas takes place.
The reaction in the aggregates of this variety proceeds with a strong oxygen deficiency (15%). Wood or any other fuel in this type of equipment breaks down into gases and a small amount of inorganic residues. For pyrolysis gases, the combustion temperature in the afterburner can reach up to 110-1200 °C.
Where else is gas used
The most widely used pyrolysis, therefore, received in heating and water heating systems. Also this reaction is widely used:
- in the processing industry;
- in chemical;
- when disinfecting.
Sometimes pyrolysis gas is also used today as a fuel for various kinds of equipment or, as already mentioned, cars.
Gas generating plants
Equipment of this type is used to produce high-quality pyrolysis fuel, which in some cases can replace, for example, traditional natural gas. Such installations are hermetic furnaces with adjustable air supply. The chimney of this type of equipment may, among other things, be blocked.
Get pyrolysis gas in such installations as follows:
- Force air into the furnace through a pump.
- After heating the contents of the installation to a certain temperature, the air supply is stopped.
- Dense black smoke coming out of the unit is cleaned of soot using cyclones.
- Remove water vapor from the pyrolysis gas to increase its combustion temperature (pass through a cooler).
- The gas is fed into the fine filter, the design of which includes a water tank, electrostatic installation and cardboard cartridges.
Purification of pyrolysis gases before their use in industry, and sometimes in everyday life, must be carried out without fail. Solid particles and all kinds of chemical impurities can cause damage to equipment,running on this type of fuel. Further, for example, pyrolysis gas can be pumped into a cylinder.
Using fuel from a gas generator at home
Installations of this type are most often used, of course, in production. But sometimes they are purchased for private homes. Getting pyrolysis gas at home is a relatively simple matter. Some craftsmen often even make gas generators with their own hands.
The gas obtained from domestic installations can be used for different purposes. Very often, for example, private traders connect ordinary stoves to gas generators. The combustion of pyrolysis gas is not as intense as natural gas. However, it is still quite convenient to use the stove for its intended purpose.
Also, for example, an autogenous generator is often connected to gas generators in everyday life. When oxygen is supplied using natural gas, the flame temperature in such equipment reaches 2000 °C.
As already mentioned, at home, pyrolysis gas can also be used as an automotive fuel. For such an application, the engine of the machine will only need to be slightly modified. At the same time, both gasoline and diesel engines can work on such fuel. Such gas is used at home, often in power generators.
Application features
Thus, pyrolysis gas has a slightly lower degree of heat transfer than natural or liquefied. Therefore, for the correct operation of various kinds of heating andkitchen equipment, when using it, for proper, more intensive combustion, it is necessary to increase its supply.
In kitchen equipment, jets can be drilled for this, for example. The pyrolysis gas furnace in this case will work in the same way as on natural gas. That is, the intensity of combustion of the fuel will be the same. Also, to transfer various kinds of equipment to another type of gas, its firmware is often changed. In vehicles to operate on such fuel, the fuel system is completely replaced.
Wood-burning machines
In the Soviet Union in the early 1920s, gas generator trucks were used very widely. In those years, we even conducted competitive tests of such cars in our country.
The first gas generator engine for a car in our USSR was installed by Professor V. S. Naumov in 1927. In 1928, the Scientific Automotive and Tractor Institute began to design such cars in Russia. The specialists of this institution then carried out experiments with foreign machines "Imbert-Dietrich" and "Pip".
The first NATI-1 gas generator built in our country worked on ordinary wood. In 1932, the NATI-3 installation was also created, designed for a motor boat. At the same time, the first automobile gas generator appeared in Russia, created with the support of the Avtodor society. It received the name "Avtodor-1". Even later, several more advanced installations of this type were developed in the USSR. The composition of the pyrolysis gas obtained from theiruse, was actually very high quality. Vehicles powered by this fuel have been known for their reliability, superior performance and long service life.
During the Second World War, gas-generator trucks ZIS-5 and GAZ-AA were actively used at the fronts and in the rear in the USSR. By the end of the war, about 200 thousand cars with pyrolysis gas engines were already in operation in the country.
Of course, the use of such fuel was caused primarily by the lack of oil products in the country at that time. However, one should not think that pyrolysis gas was used only because of the state budget deficit. Such fuel in those days was considered quite effective and promising and was used not only in Russia. For example, in the 20-30s of the last century, pyrolysis vehicles became widespread in countries such as France, Germany, Great Britain, Finland, and Sweden. Also, machines operating on such gas were widely used in some Asian countries. For example, cars of this type were successfully operated at that time in China, Japan and India.
Historical background
Wood pyrolysis is one of the first chemical processes that began to be actively used by people. In Russia, for example, such a reaction was widely used as early as the 12th century for the production of pine resin. The latter was further used for impregnating ropes, as well as for processing river and sea vessels. On an industrial scale, the Swedes were the first to use pyrolysis to impregnate wood. In this country, such a reaction is alsoused to make impregnating resin.
At the beginning of the 20th century, some of the best wood pyrolysis schools in the world were formed in Russia. This was, of course, primarily due to the fact that many forests grow on the territory of our country. Prior to the use of natural gas in Russia, many enterprises installed powerful gas generating equipment. Such installations were used for a long time before the advent of those powered by natural gas.
Of course, later such equipment was declared obsolete. The gas generators were removed from the factories. And until now, unfortunately, pyrolysis as a type of alternative economical type of fuel, in contrast to European countries, has not become widespread in the Russian Federation. However, this type of fuel in Russia is currently recognized as quite promising. Therefore, it is possible that in the near future pyrolysis gas will be used much more widely in our country. After all, the use of such fuel allows not only to save money, but also to save the environment.
