The need to use economical fuels has ripened in the world for a long time. For example, in Europe today pyrolysis gas is quite widely used. Various types of kitchen equipment, heating systems, and even automobiles can run on such fuel.
Definition
Actually, under the very concept of "pyrolysis" chemists understand the decomposition of matter at the molecular level under the influence of high temperature, usually in the absence of air. Complex compounds under these conditions decompose into simpler ones. At the same time, various new elements are formed in the medium. Essentially, pyrolysis is thus a common dry distillation process.
Gas from firewood
When burning fuel at high temperatures in an oxygen-free environment, the following combustion products are formed:
The first product from the list has, among other things, the feature that can be formed during the combustion of fuel in an oxygen environment. However, in this case, gas can only be obtained if the fuel is burned at a temperature of at least 500 ° C.
What products can be used
Pyrolysis boilers in houses can work on ordinary wood or special pallets, for example, from sawdust or pressed shavings. Various kinds of household and industrial waste can also be pyrolyzed. It burns in a similar way, for example, rubber, old car tires, plastic, used ones, things, etc. In this case, pyrolysis can not only get a certain amount of heat, but also keep the environment clean. After all, as you know, plastic does not decompose in the earth for a long time. All sorts of oily materials very strongly pollute both the soils themselves and water bodies.
Also burned in this way can:
paper, cardboard, textiles;
methane;
hydrocarbons;
peat;
non-marketed wood (including chemically impregnated ones);
straw, foliage, nutshells, weeds.
In addition, residues of paints and varnishes, oils, etc. can be processed through the pyrolysis reaction. This also helps to keep the environment clean.
Composition
The gas produced by pyrolysis contains, among other things, a lot of solid particles, usually in the form of soot. Also, its composition includes various kinds of chemical components, for example, hydrogen. However, the main composition of the pyrolysis gas is still as follows:
volatile hydrocarbons;
carbon monoxide.
In this reaction, very dangerous for human health and even his life, CO 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:
The first kind of reaction, in turn, is divided into:
low temperature;
high temperature.
How to get gas: oxidative pyrolysis
This reaction is today called the most environmentally friendly and productive. 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 16,000 ° C.
The oxidative pyrolysis reaction is used mainly for burning various industrial materials containing oil, as well as plastic and rubber. Gas in this case can go, for example, for heating the workshops of the enterprise itself, engaged in waste management.
Dry pyrolysis
Such a reaction occurs without the participation of oxygen and, as already mentioned, in turn, can be low or high temperature. In the first case, the fuel is heated to a maximum - up to 1000 ° C, in the second - above 1000 ° C. To obtain a large amount of pyrolysis gas per se, mainly high-temperature reactions are used.
When burning fuel 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 remains.
The most appropriate is the production of pyrolysis gas at a temperature of from 900 to 1000 ° C. In this case, the maximum percentage of its production is already observed. 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 burning fuel at a temperature of 450 to 500 ° C, very little solid residue or gas is obtained at the outlet. The latter is not of high quality, since it has a maximum calorific value.
Where can gas be used?
The pyrolysis process, thus, allows you to heat all sorts of rooms with the least loss of fuel. Also, through the use of this reaction, the environment is kept clean. But where can the pyrolysis gas generated during fuel combustion in an oxygen-free environment be used?
This product of combustion today is considered primarily around the world as an alternative economical source of thermal energy. In some European countries, pyrolysis gas has long become a common fuel that runs equipment that heats water (for heating and domestic hot water), 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 for heating 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. In the chambers of such units there are many combustion residues. In addition, part of the heat generated by such equipment simply flies “into the pipe” along with smoke.
The engineers who decided to fix this minus of solid fuel boilers ultimately came up with pyrolysis heating units that are economical and easy to use. In such boilers, there is, among other things, additional chambers in which the pyrolysis gas is burned.
The reaction in the aggregates of this species 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. In pyrolysis gases, the combustion temperature in the afterburner can reach 110-1200 ° .
Where else is gas used?
Thus, the widest application of pyrolysis was obtained in heating and water heating systems. Also, this reaction is widely used:
Sometimes pyrolysis gas is used today as a fuel for various kinds of equipment or, as already mentioned, automobiles.
Gas generating units
This type of equipment is used to produce high-quality pyrolysis fuel, which in some cases can be replaced, for example, traditional natural gas. Such installations are hermetic furnaces with controlled air supply. The chimney of this type of equipment may, among other things, overlap.
Get pyrolysis gas in such installations as follows:
They pump air into the furnace through a pump.
After heating the contents of the unit to a certain temperature, the air supply is stopped.
Thick black smoke coming out of the unit is cleaned of soot using cyclones.
Steam is removed from the pyrolysis gas to increase its combustion temperature (conducted through a cooler).
Gas is supplied to the fine filter, the design of which includes a container of water, an electrostatic unit and cardboard cartridges.
Purification of pyrolysis gases before their use in industry, and sometimes in everyday life, must be carried out necessarily. Particulate matter and various kinds of chemical impurities can cause damage to equipment operating on this type of fuel. Further, for example, pyrolysis gas can be pumped into the cylinder.
The use of fuel from a gas generator in everyday life
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 owners connect ordinary stoves to gas generators. 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 when using it.
Also, for example, an autogen is often connected to gas generators in everyday life. When oxygen is supplied when using trolium gas, the flame temperature in such equipment reaches 2000 ° C.
As already mentioned, at home, pyrolysis gas can also be used as automobile fuel. For this application, the machine engine will only need to be slightly modified. At the same time, both gasoline and diesel engines can operate on such fuel. Such gas is used at home and often in electric generators.
Application features
Thus, pyrolysis gas has a slightly lower degree of heat transfer than natural or liquefied gas. Therefore, for the correct operation of various kinds of heating and kitchen equipment when using it for the correct more intense combustion, it is necessary to increase its supply.
In the kitchen equipment, for example, nozzles can be drilled for this. The pyrolysis gas furnace in this case will work in the same way as on natural gas. That is, the intensity of fuel combustion will be the same. Also, for the transfer of various kinds of equipment to another type of gas, its firmware often changes. In cars for working on such fuel, the fuel system is completely replaced.
Wood burning machines
In the Soviet Union in the early 1920s, gas-generating trucks were used very widely. In those years, competitive tests of such cars were even conducted in our country.
The first gas generator engine in our USSR was installed by professor V. S. Naumov in 1927. In 1928, the Scientific Automotive Institute began to design such cars in Russia. Experts of this institution then conducted 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, created with the support of Avtodor society, appeared in Russia. He 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 with their use was actually very high quality. Automobiles running on this fuel were notable for their reliability, excellent performance and long service life.
During WWII, the ZIS-5 and GAZ-AA gas-generating trucks 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 shortage of oil products in the country at that time. However, you 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 20-30 years of the last century, pyrolysis vehicles were widely used in countries such as France, Germany, Great Britain, Finland, Sweden. Also, machines operating on such gas were widely used in some countries of Asia. For example, cars of this type were successfully operated at that time in China, Japan and India.
Historical reference
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 back in the 12th century to produce pine resin. The latter was further used for the impregnation of ropes, as well as for the processing of river and sea vessels. On an industrial scale, the Swedes were the first to apply pyrolysis for wood impregnation. In this country, such a reaction was also used to obtain an impregnating resin.
At the beginning of the 20th century, several 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 are growing in our country. Prior to the start of the use of natural gas, powerful gas-generating equipment was installed in many enterprises in Russia in Russia. Such installations were used until the appearance of those working on natural gas for a sufficiently long time.
Of course, in the future, such equipment was considered obsolete. The gas generating units were removed from the plants. And up to the present moment, unfortunately, pyrolysis as a type of alternative economical type of fuel, unlike European countries, has not received wide distribution in the Russian Federation. However, this type of fuel in Russia is currently recognized as quite promising. Therefore, it is possible that soon pyrolysis gas will be used in our country much more widely. Indeed, the use of such fuel allows not only saving money, but also preserving the environment.