Gas power plants: an autonomous energy source in a wide power range

Recommendation points

• The principle of operation of gas power plants
• Gas turbine power plants (GTE)
• Gas reciprocating power plants (GGE)
• The advantage of using gas piston power plants in an individual farm
• Low power gas generators
• Medium power modular type power plants
• Energy complexes and mini-CHP
• Small-scale cogeneration
• Device of a generator room for GGE
• Connection and operation
• Maintenance and admission
• Conclusion

Gas piston portable power plants have become an excellent analogue of units running on diesel fuel and gasoline. How profitable is the use of such sources of electricity, how to equip your home with them and what nuances you need to consider when using them, this article will tell.

The rise in electricity prices gives rise to new proposals on the market of autonomous energy supply sources. A new word in this area is thermal power plants powered by natural gas. Over the past 15 years, the production of installations of this kind has almost doubled, and the technology of local power generation itself has become so sophisticated that the cost of one kilowatt of generated electricity is cheaper than when it is consumed from urban networks. More about the benefits of gas-fired power plants:

1. Versatility of placement. Gas power plants do not require special geological or climatic conditions for installation. Due to its relatively small size and weight, only a prepared concrete base is required for the installation of an autonomous station. The lack of a large supply of water for them is also not critical..
2. Durability. Different manufacturers guarantee different service life. In general, the stations operate without major repairs for 30 years, and with the replacement of a number of executive units – up to 100 years.
3. Fully automatic operating mode. The built-in electronic control unit, which is found in almost all installations, automatically regulates the fuel supply and monitors the health of the unit in real time. The role of the service personnel is reduced to operational switching, monitoring and control of parameters.
4. Wide power range. Gas mini-power plants can provide electricity to both energy-intensive enterprises and a small country house. Depending on the version, they guarantee the production of electricity from 5 kW to several megawatts..
5. The ability to use as a backup source. Almost any power plant can be equipped with an ATS and automatic start unit. Many manufacturers produce standard modules for upgrading previously installed generators.
6. Low cost of electricity generated. The cost of electricity consumed from urban grids includes the costs of its transportation through power lines and maintenance of substations. It is much cheaper to transport a gas energy carrier, so the cost of electricity generated by gas power plants is less than two rubles per kilowatt.
7. Freedom in the choice of fuel. Power plants operate on any type of gaseous fuel, including biogas. This is relevant for livestock farms: combining a methane reactor, an enrichment plant and a power plant into one energy complex will make production independent of energy supplies.

The principle of operation of gas power plants

According to the principle of the device, power plants are divided into two types: gas turbine and gas piston. The latter have a simpler design, do not require expensive maintenance during operation and are the most economical option for a gas installation. Moreover, they have almost no limitation in maximum power. Gas turbine power plants are more technological and complex in design, but less economical: their use is justified only on the scale of industrial production. Their main advantage is high wear resistance of units and complete unpretentiousness to the type of fuel: in some cases even coal dust can be used, but a special module for preparing the fuel mixture is required.

Gas turbine power plants (GTE)

The basis of the GTE is a gas turbine, arranged according to the principle of a jet aircraft engine. It is a cylindrical combustion chamber that houses the main gas turbine impeller. High pressure air and fuel vapors enter the chamber, where they ignite. In the process of fuel combustion, a stream of hot gases is formed, which causes the turbine to rotate. It, in turn, transfers rotation to the compressor and generator, thus providing power generation..

It is characteristic that turbine power plants produce almost twice as much heat energy as electricity. Therefore, they are often used as a component of a CHP plant by installing a waste heat boiler in the exhaust system, thus ensuring not only electricity generation, but also heat supply in a large volume and at a minimal cost..

Gas reciprocating power plants (GGE)

In gas piston power plants, the source of kinetic energy is a machine unit operating on the principle of an internal combustion engine. Fuel supply is carried out by an injector and is controlled by an electronic control unit, due to which piston power plants have a sufficiently high efficiency. A significant disadvantage of the gas piston system is the high level of noise and vibration during operation due to the presence of a large number of moving parts. The advantage of these engines is their high adaptability to various modes and load levels, which cannot be achieved in gas turbine plants operating at almost constant power..

The advantage of using gas piston power plants in an individual farm

Autonomous gas generators are of great interest to both individual entrepreneurs and residents of private sectors, cottages and small agglomerations. In practice, gas-fired power plants fully justify their use, and their payback is achievable in a very foreseeable time. The only drawback is the need for serious investment, in addition, there are the following nuances:

1. Gas piston units are mainly used.
2. The payback period is the lower, the higher the actual capacity of the plant.
3. Installation requires a separate land plot.
4. In the case of shared use, a developed infrastructure is required.
5. The operation of the installations is impossible without qualified maintenance.

Autonomous gas power plants and CHP plants can be divided into three groups.

Low power gas generators

Outwardly they are similar to gasoline ones, they have a similar principle of operation and the highest cost of generated electricity. They can be protected in the form of an all-weather casing or require a special room. They are not used as the main source of electricity with very few exceptions. The choice of such generators is chosen by private households and production workshops that need a backup source of electricity and have a natural gas supply to the facility. Designed for bottled fuel, but this feature is rarely used. Unlike more powerful installations, they have a significant limitation on continuous operation (from 6 to 10 hours). Also have a disadvantage in the low quality of generated electricity.

Main characteristics:

1. Engine type: Single-cylinder four-stroke carburetor with forced cooling.
2. Generator type: usually asynchronous single or three-phase self-excited generator.
3. Output power: up to 20 kW.
4. Fuel: natural gas, propane-butane.
5. Control: analog control unit, relay protection, automatic transfer switch in most models.
6. Commissioning: less than one minute.
7. Cost: from $ 2000 to $ 10000.

This is the only type of gas generator that can be moved effortlessly. It is often used on those construction sites where there is no power supply or during field events. Mobile use comes at the expense of the high cost of a portable power station, which makes the use of gasoline fuel more efficient in this case..

Medium power modular type power plants

They are machine blocks of large dimensions, they can be open or limited by a protective noise-absorbing casing. They are mainly used as the main or reserve sources of electricity for suburban housing cooperatives, office and small industrial and shopping centers, warehouses. The productivity of such power plants is quite high, and the cost of the generated electricity is comparable to electricity from the city grid..

Main characteristics:

1. Engine type: V-type carburetor or injection engine with 6-16 cylinders, overhead valves and water cooling.
2. Generator type: asynchronous three-phase brushless generator with self-excitation.
3. Output power: up to 1 MW.
4. Fuel: natural gas, biomethane, propane-butane.
5. Management: digital controller, combined multilevel protection, automatic transfer switch, self-diagnosis. Work is fully automated.
6. Output to rated power: up to one hour.
7. Cost: from $ 10,000 to $ 250,000.

Gas piston units of this class are the most rational method of autonomous supply of electricity to residential areas and energy-intensive enterprises. The established limit of engine hours allows them to be used on a permanent basis, stopping twice a year for one day for maintenance. Power plants are equipped with separate units for the preparation of gaseous fuel and indoor switchgear for primary switching.

This equipment is completely stationary and, when installed, requires specially equipped sites or buildings equipped with a prepared concrete base to compensate for vibration, fuel bins, gas extraction and ventilation systems. Thanks to automatic regulation of fuel supply, the cost of generated electricity is significantly lower than the network.

Energy complexes and mini-CHP

Although gas-fired power plants include the possibility of operating in cogeneration mode starting from 100 kW of electric power, the greatest efficiency should be expected from power complexes with a potential of several megawatts. These units are miniature combined heat and power plants equipped with hot water or steam boilers, or heat pumps. The most advanced energy systems focused on resource-saving work simultaneously use several levels of heat removal: a waste heat boiler, an economizer and a low potential heat removal circuit.

Main characteristics:

1. Engine type: 12 or more cylinders, with forced air injection, two-level cooling circuit and a heat exchanger on the exhaust manifold.
2. Generator type: Asynchronous three-phase brushless generator.
3. Power output: over 1 MW.
4. Fuel: natural gas, biofuel, propane-butane, associated petroleum gas.
5. Management: fully automated operational post.
6. Full power: 4-5 hours.

Design, manufacture and installation of energy complexes are carried out individually. The task of each project is the greatest harmonization of the thermal and electrical loads of the facility with the production capacity of the complex. The construction of power plants is usually carried out on a turnkey basis. The main consumers are residential complexes, energy-intensive enterprises, data centers and shift camps. The cost of 1 kW of generated energy – no more than one and a half rubles.

Small-scale cogeneration

Mini-CHP plants operating on gaseous fuels began to appear in Russia relatively recently, but nevertheless they demonstrated excellent efficiency. Today, more than 200 installations operate on the territory of the Russian Federation, most of which are located in remote regions. The main argument for installing a mini-CHP at the facility is the requirement for complete autonomy or the impossibility of connecting to the main power supply lines. In this case, the question of economic feasibility is brought into the background..

The advantage of a mini-CHP is that the station produces electric energy, which is almost half the cost of the grid. Thermal energy is completely free in production, and therefore its consumer value consists exclusively of the cost of equipment maintenance and transportation over short distances..

The prospect of using mini-CHP plants everywhere is just a matter of time. So, when building new-generation residential complexes, the question of connecting to centralized sources of heat and electricity is not at all worth it. Since the quality and mode of supply of these resources leaves much to be desired, new buildings are equipped with their own power systems, from which both property owners and their users benefit..

Reconstruction of utility lines to use mini-CHP is associated with a number of difficulties. First of all, this is the question of volumetric capital investments. Restructuring the power supply industry for a small enterprise with a heat and electrical load of 2 MW will cost the administration 20 million rubles. The second reason for the low distribution is the problem of the lack of its own network of utilities: if the central sources of heat and power supply are abandoned, the enterprise will have to either buy out the entire existing infrastructure or create its own. It is profitable only if energy resources are sold to third-party consumers..

Device of a generator room for GGE

It will not be possible to carry out installation and commissioning work on our own, with all the desire, unless we are talking about low-power generators. But it is quite possible to prepare a room or a site for the installation of a power plant: this will help to partially save on expensive services of installation organizations.

Open placement. When installing an installation with an electric power of more than 500 kW, it will be necessary to install a concrete platform equipped with means of passive vibration damping. The main advantage of the open location of the power unit is effective heat removal and the absence of the need for smoke exhaust systems. To increase the convenience of the service personnel, a canopy is built over the operating panels and the mechanical block.

Indoor installation. The need for complete insulation of the power plant depends on the climatic design of the equipment. The room must have an advanced supply and exhaust ventilation and fire extinguishing system. The smoke exhaust system is represented by smoke exhausters paired with a common header. It will be necessary to install a chimney, the throughput and height of which is selected in accordance with the recommendations of the equipment manufacturer. Requirements for buildings of thermal power plants are regulated by SNiP II-58-75.

Connection and operation

The power plant is powered either from a cylinder through a special reducer, or by main gas, the pressure of which corresponds to the required parameters. To connect to the main, the power plant must be registered as an additional gas appliance, which is done according to the standard procedure with the introduction of changes to the house gas supply project.

The gas generator is connected to the electrical network through a two-position switch, if the installation itself does not turn on the ATS unit, or through a power limiter, a circuit breaker or a line disconnector with a RZAiT complex. It is very useful to organize an internal metering unit for direct connection or on current transformers on the generator line – this will help control the cost of generated electricity and quickly track fuel consumption.

During operation, it is important to comply with the prescribed operating mode, expressed in the number of engine hours per day. Power plants over 100 kW have a continuous mode of operation for 361 days a year, less powerful ones can operate from 6 to 20 hours a day. During operation, almost all parameters are monitored automatically, in the event of a malfunction, either the engine stops or the generator cuts off the voltage supply. Further diagnostics are carried out in accordance with the instruction manual.

Maintenance and admission

Most gas piston plants with a capacity of up to 5 MW do not require the constant presence of operating personnel. Monitoring and control of parameters can be established via the wireless link, but periodic inspection must be done personally. The maintenance of the station consists in carrying out scheduled repairs by the specialists of service companies and maintaining a normal oil level in the engine. Independent intervention in the design of the station is not allowed by the terms of warranty service. All that is required from the owner is to stop the operation of the generator during a scheduled repair or transport a low-power station to a service center if necessary.

Conclusion

The industry of local production of electricity and heat is considered potential for development at the global level. Generating energy in this way is a significant contribution to saving the world’s fossil fuel reserves and will give enough time for a full transition to the extraction of electricity and heat from renewable sources..

The main problem of the local use of power plants is the maintenance of environmental safety within the boundaries of urban development. But even this drawback is very easy to eliminate when using installations that absorb the combustion products of natural gas.

For ordinary citizens, gas power plants provide an excellent opportunity to reduce the price of electricity by almost half, and, if necessary, use almost free centralized heating..