Dependent wiring diagram. Classification of heat supply systems by heat carrier. Schemes for connecting heating systems to heating networks. Determination of estimated water consumption. Calculation of thermal insulation

Heat supply

Lecture #9

1. Classification of heat supply systems by heat carrier.

1. According to the method of organizing the movement of the coolant, the systems are:

a) Closed two-pipe

They are installed for the prevailing household load of HW systems; The heating system can be either dependent or independent.

Three-pipe

Apply on industrial enterprise with constant pressure on technology. In this case, a separate T1 branch is being laid, because stress on

GW does not depend on the temperature N.V. with this scheme, the surface of the boiler hot water turns out to be minimal.

Four-pipe.

Such a squeeze is used for short residential settlements with heat supply from a boiler house.

B) Semi-open.

It is applied at municipal and household loading. The heating system can be either dependent or independent.

AT) open

All water after heating and ventilation installations

Used for hot water supply. rational when

or as a temporary scheme in the initial period

construction.

1. According to the method of connecting heating systems to heating networks.

Dependent Independent

· direct connection

· elevator

· Pumping.

4. According to the method of connecting hot water systems

Open Closed

With battery parallel

and without battery serial

· With circulation and mixed

without circulation upstream

With mixing

cold water and without.

Lecture 10

Schemes for connecting heating systems to heat networks

1. Dependents.

1) Direct connections are used if the temperature of the heat carrier in the local system corresponds to the temperature in the ash network when heat is supplied from external heat networks of industrial buildings.

With heat supply from a boiler room with a temperature of 95-70 · C, 105-70 · C, it can be used for residential buildings. Excess pressure at the input is extinguished by a throttle washer.

2.Elevator

It is used when the water temperature in heating networks is higher than the required temperature in the local system, while D H ras. 15 m w.c.

When arranging heat supply at home, a dependent and independent heating system is used. Their difference lies in different schemes for connecting to the heating main.

Dependent heat supply scheme

If we imagine the elevator unit of a residential building (you can see how it looks in the photo), then it is arranged as follows:

• the elevator is separated from the heating main by inlet valves;
• behind them, in the place of supply and return, valves or gate valves are located. Through them from the server or return piping connect hot water. Often in modern elevators there are two tie-ins on the supply and return lines, which are separated by a retaining washer. Their purpose is to ensure constant circulation of hot water;
• after inserting the elements to provide hot water, there is a nozzle with a chamber where mixing is performed. The flow of hotter liquid coming from a direct pipeline under high pressure, heats up part of the water in the return and is sent for re-circulation;
• house valves block heating system buildings - they are open in winter, and closed in the warm season.

Dependent and independent heating systems differ in that in the first version, water enters the hot water supply and heat supply systems directly from the heating main.

Independent heating scheme

An independent heating circuit looks like this:

• from the supply pipeline, the liquid enters the return line, at the same time giving thermal energy heat exchanger. Water in this case is not used for hot water supply and space heating;
• in the same heat exchanger, but in its other circuit, drinking water from the water supply enters. After heating, it is fed into the heating system and for domestic use.

It looks like an independent connection of the heating system.

Dependent and independent heating system - comparison

The advantage of a dependent heating connection scheme is that the cost of its implementation is inexpensive. The fact is that with a small area of ​​\u200b\u200bthe house, the elevator unit of the heating system for it can be mounted independently, using the usual stop valves. The most expensive will be the manufacture of the nozzle, it depends on its diameter thermal power elevator.

The advantages that an independent heat supply scheme has:

• it allows you to more flexibly adjust the temperature of the coolant for heating. To do this, it will be enough to reduce the flow of coolant through the heat exchanger and, as a result, the air temperature in the house will drop. You can also press the latches in elevator node and thereby remove the gap. But for these elements, such a situation is considered abnormal, since cheeks may fall and circulation may stop. If the system is independent, performance is easily regulated - using circulation pump;
• efficiency is a consequence of the flexible heating settings depending on the needs of residents. In the dependent system, this indicator is at the level of no more than 40%;
• an independent heat supply system allows the use of water purified from impurities or non-freezing liquids as a heat carrier. heat up drinking water for hot water is not difficult. In turn, in the presence of a dependent system, consumers are forced to use water with large contaminants - sand, scale and mineral salts.

Dependence on electricity supply

A non-volatile heating system means that the heating equipment can operate in the absence of electricity. Some types of heating boilers and heat supply structures cannot work without electricity, while others can function without it.

Solid fuel boilers

The heat generator, which is a boiler (steel or cast iron), having a water jacket in the furnace and mechanical adjustment of the blower with a thermostat, is a completely non-volatile device. True, this design has a serious drawback, which is that a constant reloading of solid fuel is required.

Do independent heating of a private house, that is, without involving people, several technical solutions help:

1. Installation of the bunker and conveyor belt. As the fuel burns out, new portions of pellets or sawdust will be fed. But for the operation of the conveyor, electricity is required.
2. The use of a pyrolysis boiler, in which the combustion process is divided into two stages. The first of them consists in the pyrolysis of firewood with a limited supply of oxygen, and the second in the combustion of the resulting gas. At the top is a pyrolysis chamber, and below it is a compartment where the gas is burned. At the same time, in order for the combustion products to move against the direction of natural draft, an electric fan is needed.
3. Boiler top burning can function on one tab of coal for about five days, since only its upper layer smolders. Air is supplied to the fuel from top to bottom, and the ash is carried away by a hot stream of combustion products. But to ensure air circulation, an electric fan is required.

gas boilers

To make a non-volatile gas boiler work, they use manual ignition using a piezoelectric element and adjusting the burner flame with a mechanical thermostat. When the main burner high temperature coolant goes out, the pilot remains in working order.

Appliances equipped with electronic ignition, in case of downtime, stop the gas supply completely. After the coolant cools down below the critical level, heating resumes, but before the discharge must ignite the main burner. Air is supplied to the burner by an electrically driven forced draft fan.

Which heating scheme is better

If there are frequent power outages in the house, it is preferable to install a non-volatile gas heating boiler, since it can be used without electricity. But it should be noted that these devices do not differ in efficiency: in order to maintain a pilot flame, about 20% of the consumed gas volume is spent.

There is one more drawback of gas-fired non-volatile heating boilers - they do not have the ability to control the weather and control the unit using an external thermostat, which determines temperature regime, for example, in the most remote room. Accordingly, it is not possible to program the temperature for a long period, for example, for two weeks.

When you need to make a choice, which is the best dependent and independent heating system, it should be noted that the first of them has become unclaimed today.

At the same time, it must be said that in modern construction, an exclusively independent scheme for connecting the heating system is used, despite significant financial costs. Now everywhere they are switching to independent heat supply. In some cases, a combined scheme for connecting a heating point is used, using a dependent and independent system.

The heat supply system provides heat to buildings and structures (residential, public, industrial), and also satisfies the utility and technological needs of the consumer.

Heat supply can be local and centralized (centralized - for industrial and residential areas, local - for servicing one or more buildings).

The heating system consists of the following parts:

1. Source of heat energy (for example, CHP, boiler room).

2. Devices that transport thermal energy to the premises (heat networks).

3. Heat-consuming devices that transfer thermal energy to the consumer (for example, heaters, heating radiators).

Types of heating systems:

dependent;

independent.

Dependent heating systems

In dependent systems, the heat carrier passes through the pipeline without intermediate heat points directly to the consumer's heating system, heat exchangers and hydraulic insulation.

This scheme is economical, easy to maintain and does not require additional equipment(automatic regulation and control devices, circulation pump, heat exchangers, and so on).

The disadvantage of the dependent system is the impossibility at the beginning and end heating season adjust the heat supply when there is excess heat. This problem is solved by switching from a dependent heat supply system to an independent one.

Figure 28– Dependent heating network

Independent heating systems

In independent systems for heat supply to consumers, additional heat exchangers are used, located in central heating points, the heating equipment of consumers is hydraulically isolated from the heat producer.

Advantages independent system:

Possibility to control the amount of heat delivered to the consumer;

· high reliability;

· energy-saving effect (heat saving 10-40%);

· the possibility to improve the technical and operational qualities of the coolant, thereby increasing the protection of boiler installations from pollution.

Figure 29– Independent heating network

The main manufacturers of equipment for heating systems are the following companies:

· Buderus (Germany) – heating equipment, comfort climate systems (boilers, burners, boilers, radiators, collectors, etc.);

ICI Caldaie (Italy) – boiler equipment;

· Daikin (Japan) – air conditioning and ventilation systems;

GREE Electric Appliances Inc. (China) - climatic equipment (air conditioners, industrial chillers, fan coil units, etc.);

· Toshiba (Japan) – air conditioning and ventilation systems;

Panasonic (Japan) - air conditioners and split systems;

· A-Clima (Russia) – ventilation units and central air conditioners.