Compressed kilowatts

When planning the construction of a country house, we, first of all, consider the possibility of heating it with gas. At the same time, it is assumed by default that the gas will be mainline. However, liquefied gases have been used abroad for these purposes for a long time and on an ever-growing scale. BUTlike we have?

The structure of fuels is changing right before our eyes— the market does not stand on ceremony with traditions. Literally 2-3 years ago, only boilers operating on solid fuel, diesel fuel and gas appeared in our articles. Today, news about non-traditional energy sources is of interest. There is a revision of established views on comfort and ways to achieve it.

One of the «old» novelties is autonomous gas supply (AGS) of cottages using liquefied gas. It is clearly not developing in a vacuum. Judge for yourself: in the first year of this century, world consumption of gasoline amounted to 800 million tons, and liquefied gases— 200 milliont! But if we have to deal with gasoline at every step, then how much have we heard about «liquid» gas at all? Meanwhile, it is widely used in industry (there are many varieties of it) and to some extent— at home. Here, such gas is burned in gas stoves and radiators, in furnaces of boilers and fireplaces, supplies heat for absorption refrigerators and air conditioners, and also works in drives for heat pumps and cogenerators.

For Russia, liquefied gas (LNG) in everyday life is also not a curiosity. Small gas cylinders for 5, 27 and 50l have become an indispensable attribute not only of most country houses, but also reached many remote villages. But in order to heat a house with «liquid» gas, as millions of families abroad have been doing for decades,— the Russians are not seriously thinking about this yet. There are probably two reasons for this. First, we are spoiled by the cheapness of natural gas and evaluate all alternatives on the basis of it, using by inertia the scale of values ​​of bygone decades. Second: a subconscious feeling of fear of the hidden power of liquefied fuel, born of myths, rumors and horrors of television pictures from the places of fires and explosions of gas cylinders. There is a clear lack of reliable information.

Meanwhile, there is also a successful experience of heating with the help of SG in Russia, and considerable. ATin the sixties, the SG «worked» for the benefit of thousands of remote villages and state farms. Later, gasification of settlements, «perestroika» and the collapse of the USSR destroyed the SG supply system. Today it is ready for work again, but under new, market conditions. Andwith a more or less consistent analysis, it turns out that the idea of ​​​​heating a house with the help of SG is clearly competitive, and often the only reasonable one.

There are no words, where the main gas pipeline passes nearby, gas heating is unrivaled. But with every kilometer away from the «pipe» its cheapness becomes more and more relative. In 5km about it (in the suburbs, at least), perhaps, you can forget. Count yourself: 5-15thousand for 1km of the local gas pipeline (and the highway generally «pulls» on 250-500thousand) plus the construction of a gas distribution point (GRP) to reduce pressure, and even «modest» 5-15thousand only for permission to connect gas. True, these data were obtained privately and not officially confirmed, but their order already speaks of one thing. Connection to the highway is feasible only for a group of houses or a village, but not for the owner of a remote dwelling. He is left with an autonomous system. I must say, there is a choice: these are traditional boilers for solid or diesel fuel or new solutions— heat pumps or AGS system.

ATwhat are the advantages of autonomous gas supply? It combined some of the advantages of its rivals. Firstly, it is the comfort and environmental friendliness of gas heating. Both the stove and the boiler are supplied with gas. There is no ash with problems of its removal (as in the case of coal), no soot, no sulfur oxides and smell (as from diesel fuel). SG that has fallen on the soil does not destroy it, like diesel fuel. Secondly, it is autonomy, like in liquid fuel boilers, and, therefore, independence from gas pressure drops in the pipe, which are simply the scourge of gas heating systems. Therefore, turning off the gas and defrosting your radiators does not threaten. Thirdly, economy. In terms of the cost of the energy carrier, systems with SG are inferior to gas boilers and heat pumps, but outperform liquid fuel boilers. For a year, the savings on fuel from SG compared to diesel fuel is about 40-60rub. for 1m² house area. And, finally, equipment on such gas works better and lasts longer.

Well, are there any disadvantages? Of course, not jokes. SGs are flammable and explosive substances and require careful observance of safety measures. But that is why all installations using SG are under the vigilant eye of Rostekhnadzor (former Gosgortekh-nadzor), from the purchase of a tank for SG to the expiration of its service life. Each installation at «birth» receives its own passport, which is registered with the supervisory authority and then reflects the full history of its life. All installations have a variety of protection systems. Toonly licensed specialists are allowed to install and maintain them, and the owner of the house has the right only to visually take instrument readings (by the way, do not forget to look at the level gauge and clean the tank hatch from snow). ATIn general, all equipment is reliable and has a service life of 20-30 years. BUTit can only ignite or explode as a result of malicious acts. To make sure that there are no grounds for doubts about the safety of AGS systems, we will consider their design and operation in more detail.

Resource of reservoirs for heating at home, day (according to the company «GAMARD PCT»)

Concentrated Energy

The principle of the AGS system is simple. A capacious durable tank is buried in the ground near the house (and in warm areas they are placed on the surface of the earth). A pipeline is pulled from its neck to the house, from which branches are made to the boiler room and to the kitchen. the container is filled with liquefied gas (God forbid— «down the neck»!) from a special tank truck that comes to you 1-3once a year. The filled SG begins to evaporate, and the vapors (gas phase), passing through the reducers, under reduced pressure 30mbar flow through the pipe to the consumption devices. Such is the scheme. Well, then many details come into play, which determine the success of the case.

The beginning of everything— type SG. Today, AGS uses mixtures of liquefied technical propane and butane (SPBT), or, as they are also called, liquefied petroleum gas (given its origin), and not liquefied natural gas (methane). The latter is stored at low temperatures in special cryogenic vessels, requires additional evaporators and is economically justified only for heating a group of houses (villages).

So what is so special about a «good» SG? First of all, it is hydrocarbon gas (LHG), which under normal conditions is in a gaseous state. With a slight increase in pressure, it should go into a liquid state. Then it can be easily transported and stored. With a decrease in pressure or a slight increase in temperature, the «liquid» gas begins to evaporate and passes into the gas phase. The process ends when the saturation state is reached. Saturated vapor pressure depends only on the ambient temperature and does not depend on the amount of liquid. One liter of LPG produces about 0.25m³ gas phase. In winter, the gas pressure decreases and the productivity of the gas phase supply, of course, drops noticeably. That is why it is more profitable to bury tanks in the ground, where the heat flow comes from, maintaining stable regasification parameters.

When using LPG, one has to take into account that the process of their evaporation has the property of self-regulation. If steam is taken intensively (for example, several boilers are connected), then accelerated evaporation of the liquid will lead to its cooling and, therefore, to a decrease in gas pressure above the liquid mirror. ATAs a result, the performance of the plant will decrease. To obtain large volumes of gases, they resort to additional heating of containers or increase their number in one installation.

When the temperature rises, the liquid in the tank expands very much and, since it is incompressible, can even depressurize the vessel. Therefore, it is strictly forbidden to fill the tank with liquefied gas by more than 85% of the geometric volume. Refuelers strictly observe this norm.

Propane has the optimal set of necessary properties. It steadily supplies the gas phase even in frosts, but is relatively expensive and good only in winter. In summer, when it is hot, its vapor pressure reaches the limit value allowed for the walls of the vessel (1.6MPa). Therefore, propane is diluted with cheaper and less volatile butane. The norms stipulate that in winter the mixture is made in proportions of 70:30 (percent propane and butane, respectively), and in summer— 60:40 or 50:fifty.

LPG is twice as light as water, so water condensate gradually accumulates at the bottom of the vessel, from where it has to be pumped out (from small containers about once a year). ATin the gaseous state, the mixture is 1.5-2 times heavier than air. This means that during leaks, gases flow to the lower points. Given that these gases, although non-toxic, have a suffocating property, when using LPG, boiler rooms cannot be placed in basements and even basements if the window area in them is less than 1m². Since SPBT requires a lot of air for complete combustion (see table), good ventilation must be provided in boiler rooms— better forced. In addition, it is necessary to organize natural lighting in the room, as well as install a gas leak detection sensor and a self-powered automatic shut-off valve.

But the main problems with LPG lie elsewhere. By itself, liquefied gas does not burn and does not detonate. However, a mixture of the gas phase with air in the range of 1.8-10% instantly ignites if there is a heat source nearby with a temperature of about 500C (recall that in the flame of a match there are areas with a temperature of more than 1000FROM). At certain ratios of volume, pressure and temperature, this combustion can be accompanied by an explosion. Leaks of «liquid» gas are fraught with the spread of evaporated gases over a long distance, and in their mixture with air— danger of ignition by a large cloud. Meanwhile, the outflowing gas phase, having mixed with air, can only ignite with a small torch, and the flame does not spread into the gas flow and does not lead to an explosion of the container. In order to 100% eliminate liquid leakage, special safety measures are provided in the installations.

Stronger than a safe

The heart of the AGS system is the LPG storage tank. Containers are made cylindrical by welding from thick (up to 10mm) strong cold-resistant steel (for example, 09G2S). They are designed for an operating pressure of 1.6MPa. At the factory, each is tested for tightness and receives a numbered quality certificate. The range of products on the market is still small. Only half a dozen import suppliers— affects the complexity of transporting bulky barrels. A significant part of the market is occupied by domestic producers. True, the size range of their containers is limited (usually 5, 8 or 10m³), but most enterprises are ready to custom-made tanks of any volume. The widest range of products from Italian manufacturers (from 0.5 to 5m³ in increments of about 0.5m³), so you can choose a suitable vessel even for a small cottage.

Domestic firms produce horizontal tanks, while Italian ones also have vertical ones, with a neck at the end. It is believed that such a vessel is deeper and more heated by the heat of the soil. In addition, its performance is more uniform over time. But with the same volume, horizontal devices have a larger liquid mirror area than vertical ones, and therefore they are more productive.

Outside, all vessels are necessarily protected from chemical corrosion, but each manufacturer does this in its own way. Possible bituminous or glass bitumen coating with a thickness of 3-4mm, as well as polyurethane (up to 1.5mm), epoxy (up to 0.8mm) or isoplast layer (8mm). ANTONIO MERLONI (Italy) has gone further and supplies a system of galvanic protection against electrochemical corrosion together with its tanks. ATthe system includes a reference electrode (Сu/CuSO_four) and 2-3 consumable magnesium anodes, which are buried in the ground near the tank. Usually anodes last for 5 years.

The Italian company WALTER TOSTO SERBATOI (WTS) protects its containers in an original way. Its tanks (vertical execution) are arranged according to the principle of a thermos. The metal container is inserted into the outer container made of HPDE polyethylene. A cap-neck is put on top of it (with a seal) so that a sealed compartment is formed to accommodate safety and control devices. ATThe cap has three sealed inputs: for filling, grounding a metal vessel and a control system cable. The plastic casing works «for seven». It not only protects the metal from environmental influences (aggressive soil components, stray currents, microorganisms), that is, it performs the function of chemical and electrochemical protection, but also prevents LPG from penetrating into the soil in case of valve leakage. And perhaps the smartest— allows you to easily remove a metal container for mandatory (according to Rostekhnadzor standards) verification of its integrity. By the way, such a check is carried out once every 10 years, and not annually, as many potential customers fear.

BUTTECHNO-ITALY GRAND specialists used this design feature to wrap the vessel with special heating “bandages” (3-5 kW power) and heat it up on frosty days. Thanks to this, the gas production capacity can be adjusted according to demand.

On all tanks, the so-called reducing heads are installed without fail, in which control equipment is located: safety shut-off and relief valves, pressure regulator, level gauge, pressure gauge, shutoff valves. Heads protect this equipment from moisture, snow and dust. For domestic tanks, they are purchased separately (they cost about 50-70 thousand rubles), but in imported— are built into the design of the vessel and all equipment is included in the cost of delivery.

The most important question when buying a tank— determination of its volume. To do this, generally simple logic is used. Less volume— cheaper device. However, the mirror of the liquid phase is smaller and, therefore, the productivity is lower, that is, the gas may simply not be enough to feed the boiler. But even with sufficient performance, the low volume means that the tank needs to be refilled more often. Consequently, it will be necessary to call a refueling tank truck more often, and each of its trips, regardless of the amount of LPG filled, costs approximately $100. At the same time, the cost of the liquefied gas itself is paid separately. BUTin winter, for each arrival of a tank truck, it is necessary to clear the access road, which also requires costs.

In fact, the calculation of the required size of the tank is done by the designer for a specific system, depending on the power of the gas appliances installed in the house. In practice, tanks with a margin of volume are more often chosen. «Running» variantis volume 3-5m³.

Properties of liquefied gases

Annual heating costs 1m² area of ​​the house in different ways *

Reliability test

Reliability— this is what the consumer of any product is looking for first of all. ATIn the case of AGS systems, two aspects have to be considered: equipment and fuel supply.

FROMno technical hassle— its maintenance is carried out by qualified personnel according to the regulations. Vessels serve for 25-30 years. Elements of their equipment are forcibly replaced after the expiration of the standard period. This idea of ​​maintenance is familiar to many from the example of a maintenance system for cars.

BUTHere the situation with the provision of LPG for most homeowners is very vague. After all, this is not diesel fuel, which can be bought at almost any gas station, but a product of increased danger, you cannot pour it into a barrel yourself. Liquefied gases are supplied only through gas distribution stations (GDS), which are mainly run by government agencies. ATThe Moscow region is the State Unitary Enterprise MO «MOSOBLGAZ». ATHe has 6 GRS under his command.

Petroleum liquefied gas is produced in refineries as a by-product of gasoline production. From there, it is delivered through pipelines or in tanks to the GDS. Togas can be brought to you only from these stations and only officially, there is no “left fuel” in this business. Delivery is carried out by the company with which you have entered into an agreement for the maintenance of the tank. Usually this is the same organization that installed the gasification system for you.

So, where to start if you have firmly decided on autonomous gasification of your home? First— look for a company with a license to carry out such work. There are not very many such companies: gasis a responsible matter. This may be a division of the oblgaz (gas trust) or a private company. They operate a little differently, but are subject to the same safety rules. For a public company, the procedure is as follows:

one. You write an application addressed to the director of the gas distribution station nearest to you with a request to issue technical conditions (TU) for gasification of the house with the installation of an installation for liquefied gas. Attach copies of: passport, title documents for the land plot, situational plan, heat engineering calculation of the heating system (to know the boiler capacity and determine the annual gas consumption).

2. After the interview and payment of the advance payment, a specialist visits the site and evaluates the possibility of installing a tank on the spot. At the same time, the relief and hydrogeology of the site are important, as well as the norms for the safe location of the tank: to the house— tenm, to buildings— eightm, to the fence and sewer hatch— 3m andt.e. Also determine the corrosiveness of the soil and the presence of stray currents. If the electrical resistivity of the soil is less than 50 ohmsm or average cathode current density more than 0.05A/m²you are out of luck: the vessel will require additional corrosion protection measures. Usually this is galvanic or even cathodic protection. The latter will require not only one-time costs (minimum $1000), but also current during the operation of the tank. At the same time, the problem cannot be dismissed, since without protection measures the project will not be approved, and without it, the MOSOBLGAZ division will not mount the vessel.

3. By adding the received specifications to the package of papers, you order a gasification project from a licensed organization. It is being coordinated in the services of architectural management, power supply, gas supply and environmental protection, as well as independent examination (by firefighters, environmentalists and builders). It is clear that these services do not want to work «for a private trader» for free, and you will have to spend a lot of money. Which? There is no single answer. When preparing the material, we received different answers: they did not disclose the figures to us at all, they called the sums of 30thousandrub., 120thousandrub. and even 12thousandrub. (in the regions). The project is registered with the territorial department of Rostekhnadzor, which gives the go-ahead for the start of construction. Everything takes 3-4 weeks.

four. After passing the examination of the project, you can buy a container. This is usually done by the installation company on the basis of a separate contract for the purchase of the tank. You can buy it yourself, but then the installation will cost more.

5. Sign an installation contract. After that, the company begins work, which ends with the connection of the gas phase supply pipe to the house. The work lasts 1-3 days and costs about $1000. At the same time, earthworks are done by the customer (the cost is $10-25 /m³ ).

6. Upon completion of the installation work, the installation is tested for tightness in the presence of an inspector of the territorial department of Rostekhnadzor and a representative of the gas network service. Only after receiving positive results, the vessel can be instilled. An act of «delivery and acceptance» of completed works is issued.

7. To all the papers accumulated by this time, a service agreement is added (it costs about $300 per year), a civil liability insurance policy and an act of separation of liability, if another company is laying an internal gas pipeline around the house and connecting equipment. You attach the entire package to the application for registration of the assembled unit in Rostekhnadzor, which registers the unit and gives permission to fill the tank with liquefied gas.

You see how serious everything is, with multi-stage control, without the slightest possibility for accidents!

Private firms operate differently— usually turnkey. They do a pre-project survey themselves, carry out the project, conduct it through all instances and approve it. They also test and register the installed installation with supervisory authorities, just like a state-owned company. Variants with the performance of part of the work by other companies at the discretion of the customer are possible. The cost of work is negotiable.

LPG storage tanks

System installation features

The amount of installation work is small. The pit for the vessel is made with a margin of length and width of about 0.5m. The depth is provided so that the neck of the container protrudes above the ground. The barrel must be anchored to a heavy concrete base slab in order to avoid movement of the vessel in the spring when the soil thaws. Grounding, protection against electrochemical corrosion and lightning are carried out according to the project. The gas pipeline is made of steel, corrosion-protected or polyethylene pipes with a diameter of 25-63mm. All connections are made only by welding. Pipes are laid in trenches below the freezing depth. A sand cushion is made under the pipe and above it. The exit of the gas pipeline from the ground near the house is carried out using a special basement input unit. It ends with a flange connection. Entry into the house is carried out only with a steel pipe. Fill the container with sifted sand, manually. Therefore, the owners of the house need to think about where to put the earth taken out of the pit, and take care of the delivery of sand (2-3 cars).

Issue price

Today, LPG is cheaper than diesel fuel.— about 7-9rub. per litre. But on the world market, its cost is 0.6-0.7 of the price of gasoline. We have almost reached these proportions, so there should be no sharp price changes. The cost of operating the installation is still low, no higher than that of a gas boiler. Therefore, for a house with an area of, say, 300m² heating with «liquid» gas for a year will cost about $400 cheaper than using an oil boiler. However, the capital costs for the construction of the AGS system are high. Today they start from $10 thousand. Moreover, a big difference in the cost of the system when using domestic or imported equipment is often not visible.

The fact that prices are too high and are opportunistic is confirmed by the very long payback period of such systems.— 15-20 years. According to the specialists of the company «AZS-SNAB», for a more massive introduction of autonomous gasification systems in the Moscow region, their turnkey cost should be a maximum of $eightthousand. This amount is more in line with both the real labor costs of all parties involved in the process (designers, tank manufacturers, installers and supervisory authorities), and the solvency of developers. Understanding of this circumstance by firms and lower prices for services will incline a large number of doubting potential customers in favor of autonomous gasification. ATin the end, everyone will benefit.

The editors would like to thank TECHNO-ITALY GRAND, SERVISTRANSGAZ, AZS-SNAB, ENTIS and MOSGAZNIIPROEKT for their help in preparing the material.

• Source: Ideas for Your Home magazine#86