A gas generator is an apparatus for producing gas from coal, firewood, woodworking waste and other materials. Generated fuel can replace traditional hydrocarbon fuel - natural gas for heating homes and gasoline for a car.
The main idea of using such a unit is to save on fuel costs. The constant rise in price of gasoline, propane and methane makes home craftsmen look for alternative ways to get fuel.
To make a gas generator with your own hands, you need to understand its structure and principle of operation.
We will explain how solid fuel is converted to combustible gas, designate the design features of the unit, and give examples of self-assembly of simple devices. For better assimilation of information, we supplemented the article with visual diagrams, photographs and video clips.
Gas generator: device and principle of operation
A gas generator is a device that converts liquid or solid fuel into a gaseous state for its further combustion in order to obtain heat.
Fuel Options for a Generation Unit
Units operating on fuel oil or mining have a more complex construction than models using various types of coal or firewood.
Therefore, it is most often solid propellant gas generators that are found - fortunately, fuel is affordable and cheap for them.
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Gas supply to the boiler for heating a house
Gas production for vehicles
Gas production for agricultural machinery
Gas lamps and heaters
As a solid fuel in a gas generator use:
- charcoal, brown and hard coal;
- fuel pellets from wood waste;
- straw, sawdust and firewood;
- peat briquettes, coke;
- the husk of the seeds.
Particularly thrifty owners harvest briquettes from sawdust with their own hands.
Gas generation is possible from all these types of fuel. Energy release depends on the calorific value of different types of fuel.
Moreover, the heat from the combustion of raw materials in the gas generator is obtained more than from the use of solid fuel in boilers. If the efficiency of a conventional wood-burning boiler varies between 60–70%, then in a gas-generating complex the indicator reaches 95%.
But here we must take into account one caveat. A boiler burns fuel to heat water, and a gas generator only produces fuel. Without a heater, stove or ICE, the sense of a homemade gas generator will be zero.
The resulting gas should be used immediately - it is economically unprofitable to accumulate it in any tank. To do this, you will have to install additional equipment, depending on the power supply.
In Soviet times, gas generators were even used to operate trucks; the produced gas is enough for the operation of the internal combustion engine
What happens inside the gas generator
The operation of the gas generator is based on the pyrolysis of solid fuel, which occurs at high temperatures and low oxygen content in the furnace. Inside the gas generating device, several chemical reactions occur simultaneously.
The scheme of an industrial gas generator is a rather complex installation with many separate devices, each of which has its own operation (+)
Technologically, the process of generating combustible gas is divided into three successively occurring stages:
- Thermal decomposition of fuel. The process proceeds in conditions of oxygen deficiency, which is supplied to the reactor only a third of the required for normal combustion.
- Purification of the resulting gas. In a cyclone (dry vortex filter), a gas cloud is filtered from volatile ash particles.
- Cooling. The resulting gas mixture is cooled and subjected to further purification from impurities.
In fact, in the gas generator unit itself, it is the first process that takes place - pyrolysis. All the rest is the preparation of the gas mixture for further combustion.
The pyrolysis chamber of a self-made gas generator is divided into a solid fuel hopper (1), firebox (2) and ash pan (3)
At the exit of the gas generating unit, a combustible mixture of carbon monoxide, hydrogen, methane and other hydrocarbons is obtained.
Also, depending on the fuel used in the pyrolysis, water in the form of steam, oxygen, carbon dioxide and nitrogen are added to them in various amounts. According to the described principle, pyrolysis heating boilers also operate, demonstrating high efficiency.
Features of the various converters
Gas generators for the device and technology of internal processes are:
- straight;
- Converted
- horizontal.
They differ in the points of air supply and output of the generated gas.
Direct process occurs when the air mass is injected from below and the exit of the combustible mixture at the top of the structure.
Inverted Option involves the supply of oxygen directly to the oxidation zone. At the same time, it is the hottest in the gas generating device.
It is quite difficult to independently inject it into it; therefore, this principle of operation is applied only in industrial plants.
With a direct gas-generating process, a large volume of tar and moisture is formed at the outlet, the inverted one is too complicated to do with one’s own hands, while the horizontal one has reduced productivity, but an extremely simple design (+)
AT horizontal gas generator the outlet pipe with gas is located immediately above the grate in the zone of combining oxidation and reduction reactions. This design is the simplest in independent execution.
Advantages and disadvantages of gas generators
A factory-made household gas generator will cost 1.5–2 times more expensive than a conventional solid fuel boiler. Is it worth it to spend money on this “miracle technique”?
Among the advantages of using gas generators are:
- complete burnout of fuelloaded into the furnace, and the minimum amount of ash;
- relatively high efficiency when working together with an internal combustion engine or a gas boiler;
- wide selection of solid fuels;
- ease of operation and the lack of the need to continuously monitor the operation of the unit;
- time interval between reboots firebox - up to a day on wood and up to a week on coal;
- the possibility of using raw wood - wet raw materials can be used only in some models of gas generators;
- environmental friendliness of the device - this device does not have an exhaust pipe, all the generated gas goes in direct flow to the combustion chamber of the engine or boiler.
When using wet wood, the generator will work, but the gas production will be reduced by 20–25%. The drop in performance is due to the evaporation of natural moisture from wood.
This leads to a decrease in temperature in the furnace, which slows down the pyrolysis process. It is best to thoroughly dry the logs before loading them into the pyrolysis chamber. Industrial devices are fully automated, fuel is supplied to them by a screw from a nearby container.
A self-made gas generator does not please with such autonomy, but it is also quite simple to operate. It is only necessary from time to time to load it with fuel to the eyeballs.
Operating temperatures in the gas generator reach values of 1200–1500 ° C; its body must be made of materials that can withstand similar loads
The gas generator has fewer disadvantages, but they are:
- poorly regulated gas volumes - when the temperature in the furnace decreases, the pyrolysis stops and instead of a combustible gas mixture, a mash of resins forms at the outlet;
- bulkiness of installation - even a home-made gas generator of average power of 10-15 kW takes up a fairly large space;
- kindling time - before the reactor produces the first gas, it will take 20-30 minutes.
After “warming up” the generator stably produces a certain volume of the gas mixture, which must be burned or thrown into the air. To make this unit with your own hands you will need durable gas cylinders or thick steel, and this is a lot of money. But all this pays off with the economics of the generator and the low cost of the initial fuel.
Some models of gas generators are equipped with an air blower, while others are not. The first option allows you to increase the power of the installation, but it ties it to the mains. If you need a small generator for cooking outdoors, then you can do a compact unit without an air supercharger.
Most self-made gas generating units operate through natural traction.
A portable gas generator with a capacity of 2.4 kW, powered by wood, allows you to easily cook dinner in the country away from civilization (+)
To heat a private house, you will need an already more powerful and volatile device. However, in this case, it is worth taking care of the backup power generator, so that overnight during an accident on the network, you will not be left without power supply or without heating.
Work units of a homemade unit
To understand how you can make a solid fuel gas generator with your own hands, you need to clearly imagine its design. Each of the elements has its own purpose, even the absence of one of them is unacceptable.
Inside the housing of a homemade gas generator should be present:
- solid fuel hopper at the top of the unit;
- pyrolysis chamber, where the smoldering process takes place;
- air distribution device with check valve;
- grate with an ash pan;
- outlet pipe for produced gas;
- cleaning filters.
In a home-made generator on wood, a fairly high temperature is formed, therefore, strict requirements are imposed on each of its elements. For the case, durable sheet steel is used, and all the parts inside are selected as heat-resistant as possible.
To ensure the tightness of the fuel loading hatch in the closed state, the lid will need a sealant. The cheapest material for this is asbestos. However, it is not harmless to human health; it is better to find special heat-resistant gaskets based on silicones or silicates in the store.
The gases generated in the combustion chamber are first mixed with air and cooled, and then they are cleaned in an expanded clay or sawdust filter (+)
The body can be either cylindrical or rectangular. Often, to simplify the work, a couple of cylinders for natural gas or iron barrels are taken. One of the grates at the bottom of the firebox is welded “tightly”, and the second is built in so that it can be moved. This is necessary to clean them of slag and ash.
The air distribution unit is located outside the housing. It ensures that the necessary volumes of oxygen enter the furnace, but due to the non-return valve, it does not release combustible gases from it.
Gas generator manufacturing technologies
There are several ways to make a gas generating installation on your own. The choice here depends on the availability of materials and the further use of the resulting gas.
Option # 1: An example of building a coal-fired apparatus
Consider an example of making a useful homemade product from a metal bucket with a lid. First, we will prepare the unit, which will process the gas received from the installation into electricity.
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Alteration of the fuel system of the generator
Unit air filter upgrade
Replacement of plastic pipes with metal counterparts
Improving the exhaust pipe of the device
After preparing the consumer for the upcoming operation, it is possible to engage in the construction of a gas generator directly.
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Metal plate to strengthen the entrance
Drilling holes in a metal plate
Drilling holes in the gasifier blank
Installing the inlet tube into the bucket wall
Fastening the inlet tube with a welding machine
Silicone sealant treatment
The specifics of installing the nozzle in the lid of the bucket
Strengthening the outlet pipe at the top of the gas generator
The branch pipe that exhausts gas from the installation must be equipped with a filter, as in the process of combustion, coal emits a lot of fine suspension and dust.
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Filter Materials
Bank hole formation
Foam is placed inside the can
Installing a gas filter
Having completed the construction process of a homemade gas generator, it is necessary to check it for operability.
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Connection to an electric generator
Fuel loading into the furnace
Gas Leak Check
Installing a plug on the inlet
Option # 2: Gas generator from two-hundred-barrel drums
For a barrel home-made gas generator, a pair of tanks of 200 liters is required. One of them is inserted into the other two-thirds.
The space formed below will be used as a combustion chamber, and the upper part will ideally fit a firewood bin or pellet.
Smoldering with gas generation will occur inside the barrel from the barrel, and outside the cylinder from the old fire extinguisher in the cleaning filter it will be cleaned of non-combustible impurities
On the side, at the level of the pyrolysis section, a pipe with a cross section of 50 mm is welded to pump air, and closer to the lid is a gas outlet pipe. A hole is cut in the bottom of the inner barrel for fuel to enter the combustion chamber, and a blower door is attached to the bottom of the outer barrel.
It remains only to make filters for cleaning the gas mixture before transferring it to the boiler. For this you will need used fire extinguishers or pipe sections of a similar size.
From above, they are tightly closed, and from below, a conical nozzle is welded, at the end of which there is a fitting for removing ash. Then, a nozzle is inserted into the side for supplying the gas mixture for cleaning, and an outlet for already filtered gas is inserted into the lid.
The primary gas purification from soot and ash particles occurs due to centrifugal forces in the external filter for rough cleaning (+)
Further, to lower the temperature of the combustible gas, a cooling radiator is made of several pipes with a diameter of 10 cm. They are interconnected by small pipes.
For the final gas purification, another filter is installed with expanded clay, small metal washers or sawdust inside. The use of the latter material is permissible only provided that the incoming gas has already cooled, otherwise the matter may reach a fire.
It will turn out to make a “potbelly stove” from a gas cylinder. Instructions for creating a primitive furnace are given in this article.
Option # 3: Homemade ICE Model
For a car or motorcycle, a homemade gas generator is made according to a similar scheme. Only here you will have to reduce the installation size to a minimum. It’s unprofitable to carry a heavy unit with you, and it doesn’t look very aesthetically pleasing.
To facilitate your work, for the automotive version of the generator, it is best to take gas cylinders. The main thing is to make sure before welding that there is no hint of the presence of propane in the tank, otherwise a small explosion may occur. To do this, unscrew the balloon valve and fill the container to the eyeballs with water.
To cool the combustible mixture at the outlet of the installation, a conventional heating radiator
Initially, an automobile gas generator produces too hot gases. They must be cooled without fail. Otherwise, upon contact with the hot parts of the engine, they may ignite spontaneously. In addition, the heated gaseous fuel has a low density, which is why it is simply problematic to set it on fire in the cylinders.
A home-made gas generator for a car can be mounted in the trunk or on a trailer.
The second method is preferable due to:
- ease of repair;
- the ability to leave the gas generating unit in the garage;
- the availability of free space in the trunk;
- the possibility of using the installation for other needs in addition to supplying fuel to the internal combustion engine.
Do not be afraid of road bumps. When bouncing on bumps, the solid fuel in the combustion chamber will be shaken, which will only contribute to its better mixing and combustion.
The nuances of the operation and operation of gas generators
It is important to remember that the gas produced by the installation is odorless and poisonous. If mistakes are made when welding metal parts of the gas generator with your own hands, then trouble can not be avoided.
For a natural air flow in the combustion chamber, 5 mm holes can be drilled around the circumference of the housing. All installation work and performance checks should be carried out in a well-ventilated workshop or on the street.
The kindling of a solid fuel gas generator does not differ from the ignition of a wood stove. Firewood or another type of fuel is placed inside, and then they are set on fire by a torch
After ignition, the shutter is closed to limit the flow of oxygen into the combustion chamber. In order for the self-made gas-generating system to work properly, it is necessary to correctly adjust the discharge of the resulting gas mixture and the oxygen supply.
Before starting to tinker with a gas generator, engineering calculations should be made, in which it is necessary to take into account the combustion area and type of fuel, as well as the required output power and the expected operating mode.
How to use a charcoal processing gas generator as a fuel supplier for a small car:
Simple gas generator from propane cylinders:
The device of a wood gas generator:
The above methods are suitable for self-production of an effective gas generator. But there are many more models of this device. Some of them are easier to make, others more complicated.
The main thing when assembling the unit is to pay maximum attention to the quality of the welds, otherwise gas leaks and explosions can occur. If everything is done correctly, then the gas generator will regularly serve 10-15 years. And then the metal of the case will start to burn, and you will have to do everything anew.
Do you have practical assembly skills or experience using a homemade gas generator? Please share your knowledge and ask questions about the topic in the comments below.