With the use of modern automation equipment. Heat supply systems Equipment and systems for automatic control of heat supply

The introduction of automatic control systems (ACS) for heating, ventilation, hot water supply is the main approach to saving thermal energy. The installation of automatic control systems in individual heat points, according to the All-Russian Thermal Engineering Institute (Moscow), reduces heat consumption in the residential sector by 5-10%, and in administrative premises by 40%. The greatest effect is obtained due to optimal regulation in the spring-autumn period of the heating season, when the automation of central heating points practically does not fully fulfill its functionality. In the conditions of the continental climate of the Southern Urals, when during the day the difference in outside temperature can be 15-20 ° C, the introduction of automatic control systems for heating, ventilation and hot water supply becomes very relevant.

Building thermal management

Management of the thermal regime is reduced to maintaining it at a given level or changing it in accordance with a given law.

At thermal points, mainly two types of heat load are regulated: hot water supply and heating.

For both types of heat load, the ACP must maintain unchanged the setpoints for the temperature of hot water supply water and air in heated rooms.

A distinctive feature of heating regulation is its large thermal inertia, while the inertia of the hot water supply system is much less. Therefore, the task of stabilizing the air temperature in a heated room is much more difficult than the task of stabilizing the temperature of hot water in a hot water supply system.

The main disturbing influences are external meteorological conditions: outdoor temperature, wind, solar radiation.

There are the following fundamentally possible control schemes:

regulation of the deviation of the internal temperature of the premises from the set one by influencing the flow of water entering the heating system;
regulation depending on the perturbation of external parameters, leading to a deviation of the internal temperature from the set one;
regulation depending on changes in the outside temperature and inside the room (by disturbance and by deviation).

Rice. 2.1 Structural diagram of room thermal management by room temperature deviation

On fig. 2.1 shows a block diagram of the control of the thermal regime of the room according to the deviation of the internal temperature of the premises, and in fig. 2.2 shows a block diagram of the control of the thermal regime of the room by perturbation of external parameters.

Rice. 2.2. Structural diagram of the control of the thermal regime of the room by perturbation of external parameters

Internal disturbing effects on the thermal regime of the building are insignificant.

For the disturbance control method, the following signals can be selected as signals to monitor the outside temperature:

the temperature of the water entering the heating system;
the amount of heat entering the heating system:
coolant consumption.

ACP must take into account the following modes of operation of the district heating system, in which:

the water temperature control at the heat source is not based on the current outdoor temperature, which is the main disturbing factor for the indoor temperature. The temperature of the network water at the heat source is determined by the air temperature over a long period, taking into account the forecast and the available heat output of the equipment. The transport delay, measured by the clock, also leads to a mismatch between the subscriber's network water temperature and the current outdoor temperature;
hydraulic regimes of heating networks require limiting the maximum and sometimes the minimum consumption of network water for a thermal substation;
the load of hot water supply has a significant impact on the operating modes of heating systems, leading to variable water temperatures during the day in the heating system or network water consumption for the heating system, depending on the type of heat supply system, the scheme for connecting hot water heaters and the heating scheme.

Disturbance control system

For a disturbance control system, it is characteristic that:

there is a device that measures the magnitude of the disturbance;
according to the results of measurements, the controller exercises a control effect on the flow rate of the coolant;
the controller receives information about the temperature inside the room;
the main disturbance is the outdoor air temperature, which is controlled by the ACP, so the disturbance will be called controlled.

Variants of control schemes for disturbance with the above tracking signals:

regulation of the temperature of the water entering the heating system according to the current outdoor temperature;
regulation of the flow of heat supplied to the heating system according to the current outdoor temperature;
regulation of network water consumption according to the outdoor air temperature.

As can be seen from Figures 2.1, 2.2, regardless of the method of regulation, the automatic heat supply control system should contain the following main elements:

primary measuring devices - temperature, flow, pressure, differential pressure sensors;
secondary measuring devices;
executive mechanisms containing regulatory bodies and drives;
microprocessor controllers;
heating devices (boilers, heaters, radiators).

ASR heat supply sensors

The main parameters of heat supply, which are maintained in accordance with the task with the help of automatic control systems, are widely known.

In heating, ventilation and hot water systems, temperature, flow, pressure, pressure drop are usually measured. In some systems, the heat load is measured. Methods and methods for measuring the parameters of heat carriers are traditional.

Rice. 2.3

On fig. 2.3 shows the temperature sensors of the Swedish company Tour and Anderson.

Automatic regulators

An automatic regulator is an automation tool that receives, amplifies and converts the shutdown signal of the controlled variable and purposefully influences the object of regulation.

Currently, digital controllers based on microprocessors are mainly used. In this case, usually in one microprocessor controller, several regulators for heating, ventilation and hot water supply systems are implemented.

Most domestic and foreign controllers for heat supply systems have the same functionality:

depending on the outdoor air temperature, the regulator provides the necessary temperature of the heat carrier for heating the building according to the heating schedule, controlling the control valve with an electric drive installed on the heating network pipeline;

automatic adjustment of the heating schedule is made in accordance with the needs of a particular building. For the greatest efficiency of heat saving, the supply schedule is constantly adjusted taking into account the actual conditions of the heat point, climate, and heat losses in the room;

the saving of the heat carrier at night is achieved due to the temporary method of regulation. Changing the task for a partial decrease in the coolant depends on the outside temperature so that, on the one hand, reduce heat consumption, on the other hand, do not freeze and warm up the room in time in the morning. At the same time, the moment of turning on the daytime heating mode, or intensive heating, is automatically calculated to achieve the desired room temperature at the right time;

the controllers make it possible to ensure the return water temperature as low as possible. This provides for the protection of the system from freezing;

the automatic correction set in the hot water system is performed. When the consumption in the domestic hot water system is low, large deviations in temperature are acceptable (increased dead band). This way the valve stem will not be changed too often and its service life will be extended. When the load increases, the dead zone automatically decreases, and the control accuracy increases;

alarm is triggered when the setpoints are exceeded. The following alarms are usually generated:
- temperature alarm, in case of difference between the real and the set temperature;
- an alarm from the pump comes in case of a malfunction;
- alarm signal from the pressure sensor in the expansion tank;
- a life-of-life alarm is triggered if the equipment has reached its end of life;
- general alarm - if the controller has registered one or more alarms;

the parameters of the regulated object are registered and transferred to a computer.

Rice. 2.4

On fig. 2.4 microprocessor controllers ECL-1000 from Danfoss are shown.

Regulators

The actuator is one of the links of automatic control systems designed to directly influence the object of regulation. In the general case, the actuating device consists of an actuating mechanism and a regulating body.

Rice. 2.5

The actuator is the drive part of the regulatory body (Fig. 2.5).

In automatic heat supply control systems, mainly electrical (electromagnetic and electric motor) are used.

The regulatory body is designed to change the flow of matter or energy in the object of regulation. There are dosing and throttle regulating bodies. Dosing devices include such devices that change the flow rate of a substance by changing the performance of units (dosers, feeders, pumps).

Rice. 2.6

Throttle regulators (Fig. 2.6) are a variable hydraulic resistance that changes the flow rate of the substance by changing its flow area. These include control valves, elevators, secondary dampers, taps, etc.

Regulators are characterized by many parameters, the main of which are: throughput K v , nominal pressure P y , pressure drop across the regulator D y , and nominal passage D y .

In addition to the above parameters of the regulatory body, which mainly determine their design and dimensions, there are other characteristics that are taken into account when choosing a regulatory body, depending on the specific conditions of their use.

The most important is the flow characteristic, which establishes the dependence of the flow in relation to the movement of the valve at a constant pressure drop.

Throttle control valves are usually profiled with a linear or equal percentage flow characteristic.

With a linear bandwidth characteristic, the increase in bandwidth is proportional to the increment in gate movement.

With an equal-percentage bandwidth characteristic, the bandwidth increment (when the shutter movement changes) is proportional to the current bandwidth value.

Under operating conditions, the type of flow characteristic changes depending on the pressure drop across the valve. When assisted, the control valve is characterized by a flow characteristic, which is the dependence of the relative flow rate of the medium on the degree of opening of the regulating body.

The smallest value of the throughput, at which the throughput characteristic remains within the specified tolerance, is evaluated as the minimum throughput.

In many industrial process automation applications, the regulator must have a wide range of throughput, which is the ratio of the nominal throughput to the minimum throughput.

A necessary condition for the reliable operation of an automatic control system is the correct choice of the shape of the flow characteristic of the control valve.

For a particular system, the flow characteristic is determined by the values of the parameters of the medium flowing through the valve and its throughput characteristic. In general, the flow characteristic differs from the flow characteristic, since the parameters of the medium (mainly pressure and pressure drop) usually depend on the flow rate. Therefore, the task of choosing the preferred flow characteristics of the control valve is divided into two stages:

selection of the form of the flow characteristics, ensuring the constancy of the transmission coefficient of the control valve over the entire range of loads;

selection of the form of the throughput characteristic, which provides the desired form of the flow characteristic for the given parameters of the medium.

When modernizing heating, ventilation and hot water supply systems, the dimensions of a typical network, the available pressure and the initial pressure of the medium are specified, the regulating body is chosen so that at a minimum flow rate through the valve, the loss in it corresponds to the excess pressure of the medium developed by the source, and the shape of the flow characteristic is close to given. The method of hydraulic calculation when choosing a control valve is quite laborious.

AUZhKH trust 42 in collaboration with SUSU has developed a program for calculating and selecting regulatory bodies for the most common heating and hot water supply systems.

Circular pumps

Regardless of the scheme for connecting the heat load, a circulation pump is installed in the heating system circuit (Fig. 2.7).

Rice. 2.7. Circular pump (Grundfog).

It consists of a speed controller, an electric motor and the pump itself. The modern circulation pump is a glandless, glandless pump that requires no maintenance. The engine control is usually carried out by an electronic speed controller designed to optimize the performance of the pump operating in conditions of increased external disturbances affecting the heating system.

The action of the circulation pump is based on the dependence of the pressure on the performance of the pump and, as a rule, has a quadratic character.

Circulation pump parameters:

performance;
maximum pressure;
speed;
speed range.

AUZhKH trust 42 has the necessary information on the calculation and selection of circulation pumps and can provide the necessary advice.

Heat exchangers

The most important elements of heat supply are heat exchangers. There are two types of heat exchangers: tubular and plate. Simplified, a tubular heat exchanger can be represented as two pipes (one pipe is inside the other rough). The plate heat exchanger is a compact heat exchanger assembled on a suitable frame of corrugated plates fitted with seals. Tubular and plate heat exchangers are used for hot water supply, heating and ventilation. The main parameters of any heat exchanger are:

power;
heat transfer coefficient;
loss of pressure;
maximum operating temperature;
maximum working pressure;
maximum flow.

Shell-and-tube heat exchangers have low efficiency due to low water flow rates in the tubes and annulus. This leads to low values of the heat transfer coefficient and, as a result, unreasonably large dimensions. During the operation of heat exchangers, significant deposits in the form of scale and corrosion products are possible. In shell-and-tube heat exchangers, the elimination of deposits is very difficult.

Compared to tubular heat exchangers, plate heat exchangers are characterized by increased efficiency due to improved heat transfer between the plates, in which turbulent coolant flows countercurrently. In addition, the repair of the heat exchanger is carried out quite simply and without high costs.

Plate heat exchangers successfully solve the problems of preparing hot water in heating points with virtually no heat loss, so they are actively used today.

The principle of operation of plate heat exchangers is as follows. The liquids involved in the heat transfer process are introduced through the nozzles into the heat exchanger (Fig. 2.8).

Rice. 2.8

Gaskets, installed in a special way, ensure the distribution of liquids in the appropriate channels, eliminating the possibility of mixing flows. The type of corrugations on the plates and the configuration of the channel are selected in accordance with the required free passage between the plates, thus ensuring optimal conditions for the heat exchange process.

Rice. 2.9

The plate heat exchanger (Fig. 2.9) consists of a set of corrugated metal plates with holes in the corners for the passage of two fluids. Each plate is equipped with a gasket that limits the space between the plates and ensures the flow of liquids in this channel. The flow rate of coolants, the physical properties of liquids, pressure losses and temperature conditions determine the number and size of plates. Their corrugated surface contributes to an increase in turbulent flow. Contacting in intersecting directions, the corrugations support the plates, which are under conditions of different pressure from both coolants. To change the capacity (increase the heat load), a certain number of plates must be added to the heat exchanger package.

Summing up the above, we note that the advantages of plate heat exchangers are:

compactness. Plate heat exchangers are more than three times more compact than shell and tube heat exchangers and more than six times lighter at the same power;
ease of installation. Heat exchangers do not require a special foundation;
low maintenance costs. The highly turbulent flow results in a low degree of pollution. New models of heat exchangers are designed in such a way as to extend the period of operation, which does not require repair, as much as possible. Cleaning and checking takes little time, since in the heat exchangers each heating sheet is taken out, which can be cleaned individually;
efficient use of thermal energy. The plate heat exchanger has a high heat transfer coefficient, transfers heat from the source to the consumer with low losses;
reliability;
the ability to significantly increase the thermal load by adding a certain number of plates.

The temperature regime of the building as an object of regulation

When describing technological processes of heat supply, design schemes of statics are used that describe steady states, and design schemes of dynamics that describe transient modes.

The design schemes of the heat supply system determine the relationship between the input and output effects on the control object under the main internal and external disturbances.

A modern building is a complex heat and power system; therefore, simplifying assumptions are introduced to describe the temperature regime of a building.

For multi-storey civil buildings, the part of the building for which the calculation is made is localized. Since the temperature regime in the building varies depending on the floor, the horizontal layout of the premises, the temperature regime is calculated for one or more of the most favorably located premises.

The calculation of convective heat transfer in a room is derived from the assumption that the air temperature at each moment of time is the same throughout the entire volume of the room.

When determining heat transfer through external enclosures, it is assumed that the enclosure or its characteristic part have the same temperature in planes perpendicular to the direction of air flow. Then the process of heat transfer through the outer enclosures will be described by a one-dimensional heat conduction equation.

The calculation of radiant heat transfer in a room also allows a number of simplifications:
a) we consider the air in the room to be a radiant medium;
b) we neglect multiple reflections of radiant fluxes from surfaces;
c) complex geometric shapes are replaced by simpler ones.

Outdoor climate parameters:
a) if the temperature regime of the premises is calculated at extreme values of the outdoor climate indicators that are possible in a given area, then the thermal protection of the fences and the power of the microclimate control system will ensure stable compliance with the specified conditions;
b) if we accept softer requirements, then in the room at some points in time there will be deviations from the design conditions.

Therefore, when assigning the design characteristics of the outdoor climate, it is mandatory to take into account the security of internal conditions.

AUZhKH Trust 42 specialists, together with SUSU scientists, have developed a computer program for calculating static and dynamic operating modes of subscriber bushings.

Rice. 2.10

On fig. 2.10 shows the main disturbing factors acting on the object of regulation (room). The heat Q source, coming from the heat source, performs the functions of a control action to maintain the room temperature T pom at the outlet of the object. Outside temperature T nar, wind speed V wind, solar radiation J rad, internal heat loss Q inside are disturbing influences. All these effects are functions of time and are random. The task is complicated by the fact that heat transfer processes are non-stationary and are described by differential equations in partial derivatives.

Below is a simplified design scheme of the heating system, which accurately describes the static thermal conditions in the building, and also allows you to qualitatively assess the impact of the main disturbances on the dynamics of heat transfer, to implement the main methods for regulating the processes of space heating.

Currently, studies of complex nonlinear systems (these include heat transfer processes in a heated room) are carried out using mathematical modeling methods. The use of computer technology to study the dynamics of the space heating process and possible control methods is an effective and convenient engineering method. The effectiveness of modeling lies in the fact that the dynamics of a complex real system can be studied using relatively simple application programs. Mathematical modeling allows you to explore the system with continuously changing its parameters, as well as perturbing influences. The use of modeling software packages for studying the heating process is especially valuable, since the study by analytical methods turns out to be very laborious and completely unsuitable.

Rice. 2.11

On fig. 2.11 shows fragments of the design scheme of the static mode of the heating system.

The figure has the following symbols:

t 1 (T n) - the temperature of the network water in the supply line of the power network;
T n (t) - outdoor temperature;
U - mixing ratio of the mixing unit;
φ - relative consumption of network water;
ΔT - design temperature difference in the heating system;
δt is the calculated temperature difference in the heating network;
T in - internal temperature of heated premises;
G - consumption of network water at the heating point;
D p - water pressure drop in the heating system;
t - time.

With subscriber input with installed equipment for given calculated heating load Q 0 and daily schedule of hot water supply load Q r, the program allows you to solve any of the following tasks.

At an arbitrary outdoor temperature T n:

determine the internal temperature of the heated premises T in, while the specified are the flow of network water or the input G with and the temperature graph in the supply line;
determine the consumption of network water for input G c, required to provide a given internal temperature of heated premises T in with a known temperature graph of the heating network;
determine the required water temperature in the supply line of the heating network t 1 (network temperature graph) to ensure the specified internal temperature of heated rooms T in at a given flow rate of network water G s. These tasks are solved for any heating system connection scheme (dependent, independent) and any hot water supply connection scheme (series, parallel, mixed).

In addition to the above parameters, water flow rates and temperatures are determined at all characteristic points of the scheme, heat flow rates for the heating system and thermal loads of both stages of the heater, and pressure losses of heat carriers in them. The program allows you to calculate the modes of subscriber inputs with any type of heat exchangers (shell and tube or plate).

Rice. 2.12

On fig. 2.12 shows fragments of the design scheme of the dynamic mode of the heating system.

The program for calculating the dynamic thermal regime of the building allows for subscriber input with the selected equipment for a given design heating load Q 0 to solve any of the following tasks:

calculation of the control scheme for the thermal regime of the room according to the deviation of its internal temperature;
calculation of the control scheme for the thermal regime of the room according to the perturbation of external parameters;
calculation of the thermal regime of the building with qualitative, quantitative and combined methods of regulation;
calculation of the optimal controller with non-linear static characteristics of real elements of the system (sensors, control valves, heat exchangers, etc.);
with an arbitrarily time-varying outdoor temperature T n (t), it is necessary:
determine the change in time of the internal temperature of the heated premises T in;
determine the change in time of the consumption of network water pa input G with required to provide a given internal temperature of the heated premises T in with an arbitrary temperature graph of the heating network;
determine the change in time of the water temperature in the supply line of the heating network t 1 (t).

These tasks are solved for any heating system connection scheme (dependent, independent) and any hot water supply connection scheme (series, parallel, mixed).

Implementation of ASR for heat supply in residential buildings

Rice. 2.13

On fig. 2.13 shows a schematic diagram of an automatic control system for heating and hot water supply in an individual heating point (ITP) with dependent connection of the heating system and a two-stage scheme of hot water heaters. It was mounted by AUZhKH trust 42, passed tests and operational checks. This system is applicable to any connection scheme for heating and hot water systems of this type.

The main task of this system is to maintain a given dependence of the change in the consumption of network water for the heating and hot water supply system on the outside air temperature.

The connection of the heating system of the building to the heating networks is made according to a dependent scheme with pump mixing. For the preparation of hot water for the needs of hot water supply, it is planned to install plate heaters connected to the heating network according to a mixed two-stage scheme.

The heating system of the building is a two-pipe vertical system with a lower distribution of main pipelines.

The building's automatic heat supply control system includes solutions for:

for automatic control of the operation of the external heat supply circuit;
for automatic control of the operation of the internal circuit of the heating system of the building;
to create a mode of comfort in the premises;
for automatic control of the operation of the DHW heat exchanger.

The heating system is equipped with a microprocessor-based water temperature controller for the heating circuit of the building (internal circuit), complete with temperature sensors and a motorized control valve. Depending on the outside air temperature, the control device ensures the required temperature of the coolant for heating the building according to the heating schedule, controlling the control valve with an electric drive installed on a direct pipeline from the heating network. To limit the maximum temperature of the return water returned to the heating network, a signal from a temperature sensor installed on the return water pipeline to the heating network is input to the microprocessor controller. The microprocessor controller protects the heating system from freezing. To maintain a constant differential pressure, a differential pressure regulator is provided on the temperature control valve.

To automatically control the air temperature in the premises of the building, the project provides for thermostats on heating devices. Thermoregulators provide comfort and save heat energy.

To maintain a constant differential pressure between the direct and return pipelines of the heating system, a differential pressure regulator is installed.

To automatically control the operation of the heat exchanger, an automatic temperature controller is installed on the heating water, which changes the supply of heating water depending on the temperature of the heated water entering the DHW system.

In accordance with the requirements of the "Rules for accounting for thermal energy and coolant" of 1995, commercial accounting of thermal energy was carried out at the input of the heating network to the ITP by means of a heat meter installed on the supply pipeline from the heating network and a volume meter installed on the return pipeline to the heating network.

The heat meter includes:

flowmeter;
CPU;
two temperature sensors.

The microprocessor controller provides indication of parameters:

quantity of heat;
the amount of coolant;
coolant temperature;
temperature difference;
operating time of the heat meter.

All elements of automatic control systems and hot water supply are made using Danfoss equipment.

The microprocessor controller ECL 9600 is designed to control the temperature regime of water in heating and hot water supply systems in two independent circuits and is used for installation at heating points.

The regulator has relay outputs for controlling control valves and circulation pumps.

Items to be connected to the ECL 9600 controller:

outdoor air temperature sensor ESMT;
temperature sensor at the coolant supply in the circulation circuit 2, ESMA/C/U;
reversible drive of the control valve of the AMB or AMV series (220 V).

In addition, the following elements can be attached optionally:

return water temperature sensor from the circulation circuit, ESMA/C/U;
ESMR indoor air temperature sensor.

The ECL 9600 microprocessor controller has built-in analog or digital timers and an LCD display for easy maintenance.

The built-in indicator serves for visual observation of parameters and adjustment.

When an ESMR/F indoor air temperature sensor is connected, the temperature of the heating medium is automatically corrected at the supply to the heating system.

The controller can limit the value of the return water temperature from the circulation circuit in follow-up mode depending on the outdoor temperature (proportional limitation) or set a constant value for the maximum or minimum limitation of the return water temperature from the circulation circuit.

Comfort and heat saving features:

lowering the temperature in the heating system at night and depending on the outdoor temperature or according to the set reduction value;
the possibility of operating the system with increased power after each period of temperature decrease in the heating system (quick heating of the room);
the possibility of automatic shutdown of the heating system at a certain set outdoor temperature (summer shutdown);
the ability to work with various types of mechanized actuators of the control valve;
remote control of the controller using ESMF/ECA 9020.

Protective features:

limiting the maximum and minimum temperatures of the water supplied to the circulation circuit;
pump control, periodic promenade in summer;
protection of the heating system from freezing;
the possibility of connecting a safety thermostat.

Modern equipment for automatic heat supply control systems

Domestic and foreign companies provide a wide range of modern equipment for automatic heat supply control systems with almost the same functionality:

Heating control:
- Damping outdoor temperature.
- Monday Effect.
- Linear restrictions.
- Return temperature limits.
- Room temperature correction.
- Self-correcting feed schedule.
- Startup time optimization.
- Economy mode at night.

DHW management:
- Low load feature.
- Return water temperature limit.
- Separate timer.

Pump control:
- Freeze protection.
- Turn off the pump.
- Pump exchange.

Alarms:
- From the pump.
- Freezing temperature.
- General.

Sets of heat supply equipment from well-known companies, Danfoss (Denmark), Alfa Laval (Sweden), Tour and Anderson (Sweden), Raab Karcher (Germany), Honeywell (USA) generally include the following instruments and devices for control and accounting systems.

Equipment for automation of the heating point of the building:

Heat metering equipment.

Auxiliary equipment.
- Check valves.
- Ball valves are installed for hermetic shutdown of risers and for draining water. At the same time, in the open state, during the operation of the system, ball valves practically do not create additional resistance. They can also be installed on all branches at the entrance to the building and at the substation.
- Drain ball valves.
- A non-return valve is installed to prevent water from entering the return line from the supply line when the pump is stopped.
- The mesh filter, with a ball valve on the drain, at the inlet to the system provides water purification from solid suspensions.
- Automatic air vents provide automatic air release when filling the heating system, as well as during the operation of the heating system.
- Radiators.
- Convectors.
- Intercoms ("Vika" AUZhKH trust 42).

The AUZhKH of trust 42 analyzed the functionality of the equipment of automatic heat supply control systems of the most famous companies: Danfoss, Tour and Anderson, Honeywell. Employees of the trust can provide qualified advice on the implementation of the equipment of these firms.

Article 18. Distribution of heat load and management of heat supply systems

1. The distribution of the heat load of consumers of thermal energy in the heat supply system between those supplying thermal energy in this heat supply system is carried out by the body authorized in accordance with this Federal Law to approve the heat supply scheme by making annual changes to the heat supply scheme.

2. To distribute the heat load of consumers of heat energy, all heat supply organizations that own sources of heat energy in this heat supply system are required to submit to the body authorized in accordance with this Federal Law to approve the heat supply scheme, an application containing information:

1) on the amount of heat energy that the heat supply organization undertakes to supply to consumers and heat supply organizations in this heat supply system;

2) on the amount of capacity of thermal energy sources, which the heat supply organization undertakes to support;

3) on current tariffs in the field of heat supply and predicted specific variable costs for the production of thermal energy, heat carrier and power maintenance.

3. In the heat supply scheme, conditions must be determined under which it is possible to supply thermal energy to consumers from various sources of thermal energy while maintaining the reliability of heat supply. In the presence of such conditions, the distribution of heat load between sources of heat energy is carried out on a competitive basis in accordance with the criterion of minimum specific variable costs for the production of heat energy by sources of heat energy, determined in the manner established by the pricing principles in the field of heat supply, approved by the Government of the Russian Federation, on the basis of applications organizations that own sources of thermal energy, and standards taken into account when regulating tariffs in the field of heat supply for the corresponding period of regulation.

4. If the heat supply organization does not agree with the distribution of the heat load carried out in the heat supply scheme, it has the right to appeal against the decision on such distribution, taken by the body authorized in accordance with this Federal Law to approve the heat supply scheme, to the federal executive body authorized by the Government of the Russian Federation.

5. Heat supply organizations and heat network organizations operating in the same heat supply system, annually before the start of the heating period, are required to conclude an agreement between themselves on the management of the heat supply system in accordance with the rules for organizing heat supply, approved by the Government of the Russian Federation.

6. The subject of the agreement specified in part 5 of this article is the procedure for mutual actions to ensure the functioning of the heat supply system in accordance with the requirements of this Federal Law. The obligatory conditions of this agreement are:

1) determining the subordination of dispatching services of heat supply organizations and heat network organizations, the procedure for their interaction;

3) the procedure for ensuring access of the parties to the agreement or, by mutual agreement of the parties to the agreement, to another organization to heat networks for the adjustment of heat networks and regulation of the operation of the heat supply system;

4) the procedure for interaction between heat supply organizations and heat network organizations in emergency situations and emergencies.

7. If the heat supply organizations and heat network organizations have not concluded the agreement specified in this article, the procedure for managing the heat supply system is determined by the agreement concluded for the previous heating period, and if such an agreement has not been concluded earlier, the specified procedure is established by the body authorized in accordance with this Federal law for approval of the heat supply scheme.

An important utility service in modern cities is heat supply. The heat supply system serves to meet the needs of the population in heating services for residential and public buildings, hot water supply (water heating) and ventilation.

The modern urban heat supply system includes the following main elements: a heat source, heat transmission networks and devices, as well as heat-consuming equipment and devices - heating, ventilation and hot water supply systems.

City heating systems are classified according to the following criteria:

- degree of centralization;
- type of coolant;
- method of generating thermal energy;
- method of supplying water for hot water supply and heating;
- the number of pipelines of heating networks;
- a way to provide consumers with thermal energy, etc.

By degree of centralization heat supply distinguish two main types:

1) centralized heat supply systems, which have been developed in cities and districts with predominantly multi-storey buildings. Among them are: highly organized centralized heat supply based on the combined generation of heat and electricity at CHP - district heating and district heating from district heating and industrial heating boilers;
2) decentralized heat supply from small adjoining boiler plants (attached, basement, roof), individual heating devices, etc.; at the same time, there are no heating networks and associated losses of thermal energy.

By coolant type Distinguish between steam and water heating systems. In steam heating systems, superheated steam acts as a heat carrier. These systems are mainly used for technological purposes in industry, power industry. For the needs of communal heat supply of the population due to the increased danger during their operation, they are practically not used.

In water heating systems, the heat carrier is hot water. These systems are used mainly for supplying thermal energy to urban consumers, for hot water supply and heating, and in some cases for technological processes. In our country, water heating systems account for more than half of all heating networks.

By method of generating heat energy distinguish:

- Combined generation of heat and electricity at combined heat and power plants. In this case, the heat of the working thermal steam is used to generate electricity when the steam expands in the turbines, and then the remaining heat of the exhaust steam is used to heat water in the heat exchangers that make up the heating equipment of the CHP. Hot water is used for heating urban consumers. Thus, in a CHP plant, high-potential heat is used to generate electricity, and low-potential heat is used to supply heat. This is the energy meaning of the combined generation of heat and electricity, which provides a significant reduction in the specific fuel consumption in the production of heat and electricity;
- separate generation of thermal energy, when heating water in boiler plants (thermal power plants) is separated from the generation of electrical energy.

By water supply method for hot water supply, water heating systems are divided into open and closed. In open water heating systems, hot water is supplied to the taps of the local hot water supply system directly from the heating networks. In closed water heating systems, water from heating networks is used only as a heating medium for heating in water heaters - heat exchangers (boilers) of tap water, which then enters the local hot water supply system.

By number of pipelines There are single-pipe, two-pipe and multi-pipe heat supply systems.

By way to provide consumers with thermal energy, single-stage and multi-stage heat supply systems are distinguished - depending on the schemes for connecting subscribers (consumers) to heating networks. The nodes for connecting heat consumers to heating networks are called subscriber inputs. At the subscriber input of each building, hot water heaters, elevators, pumps, fittings, instrumentation are installed to regulate the parameters and flow of the coolant according to local heating and water fittings. Therefore, often a subscriber input is called a local heating point (MTP). If a subscriber input is being constructed for a separate facility, then it is called an individual heating point (ITP).

When organizing single-stage heat supply systems, heat consumers are connected directly to heat networks. Such a direct connection of heating devices limits the limits of permissible pressure in heating networks, since the high pressure required to transport the coolant to end consumers is dangerous for heating radiators. Because of this, single-stage systems are used to supply heat to a limited number of consumers from boiler houses with a short length of heating networks.

In multistage systems, between the heat source and consumers, central heating centers (CHP) or control and distribution points (CDP) are placed, in which the parameters of the coolant can be changed at the request of local consumers. The central heating and distribution centers are equipped with pumping and water heating units, control and safety fittings, instrumentation designed to provide a group of consumers in a quarter or district with thermal energy of the required parameters. With the help of pumping or water heating installations, main pipelines (first stage) are partially or completely hydraulically isolated from distribution networks (second stage). From the CHP or KRP, a heat carrier with acceptable or established parameters is supplied through common or separate pipelines of the second stage to the MTP of each building for local consumers. At the same time, only elevator mixing of return water from local heating installations, local regulation of water consumption for hot water supply and metering of heat consumption are carried out in the MTP.

The organization of complete hydraulic isolation of heat networks of the first and second stages is the most important measure to improve the reliability of heat supply and increase the range of heat transport. Multi-stage heat supply systems with central heating and distribution centers allow reducing the number of local hot water heaters, circulation pumps and temperature controllers installed in the MTP with a single-stage system by tens of times. In the central heating center, it is possible to organize the treatment of local tap water to prevent corrosion of hot water supply systems. Finally, during the construction of the central heating and distribution centers, the unit operating costs and the costs of maintaining personnel for servicing equipment in the MTP are significantly reduced.

Thermal energy in the form of hot water or steam is transported from a thermal power plant or boiler house to consumers (to residential buildings, public buildings and industrial enterprises) through special pipelines - heating networks. The route of heat networks in cities and other settlements should be provided in the technical lanes allocated for engineering networks.

Modern heating networks of urban systems are complex engineering structures. Their length from the source to consumers is tens of kilometers, and the diameter of the mains reaches 1400 mm. The structure of thermal networks includes heat pipelines; compensators that perceive temperature elongations; disconnecting, regulating and safety equipment installed in special chambers or pavilions; pumping stations; district heating points (RTP) and heating points (TP).

Heating networks are divided into main, laid on the main directions of the settlement, distribution - within the quarter, microdistrict - and branches to individual buildings and subscribers.

Schemes of thermal networks are used, as a rule, beam. In order to avoid interruptions in the supply of heat to the consumer, individual main networks are connected to each other, as well as the installation of jumpers between branches. In large cities, in the presence of several large heat sources, more complex heat networks are built according to the ring scheme.

To ensure the reliable functioning of such systems, their hierarchical construction is necessary, in which the entire system is divided into a number of levels, each of which has its own task, decreasing in value from the top level to the bottom. The upper hierarchical level is made up of heat sources, the next level is main heating networks with RTP, the lower one is distribution networks with subscriber inputs of consumers. Heat sources supply hot water of a given temperature and a given pressure to the heating networks, ensure the circulation of water in the system and maintain the proper hydrodynamic and static pressure in it. They have special water treatment plants, where chemical purification and deaeration of water is carried out. The main heat carrier flows are transported through the main heat networks to the heat consumption nodes. In the RTP, the coolant is distributed among the districts, autonomous hydraulic and thermal regimes are maintained in the networks of the districts. The organization of the hierarchical construction of heat supply systems ensures their controllability during operation.

To control the hydraulic and thermal modes of the heat supply system, it is automated, and the amount of heat supplied is regulated in accordance with consumption standards and subscriber requirements. The largest amount of heat is spent on heating buildings. The heating load changes with the outside temperature. To maintain the conformity of heat supply to consumers, it uses central regulation on heat sources. It is not possible to achieve a high quality of heat supply using only central regulation; therefore, additional automatic regulation is used at heating points and consumers. The water consumption for hot water supply is constantly changing, and in order to maintain a stable heat supply, the hydraulic mode of heat networks is automatically regulated, and the temperature of hot water is maintained constant and equal to 65 ° C.

The main systemic problems that complicate the organization of an effective mechanism for the functioning of heat supply in modern cities include the following:

- significant physical and moral wear and tear of equipment of heat supply systems;
- high level of losses in heat networks;
- massive lack of heat energy meters and heat supply regulators among residents;
- overestimated thermal loads of consumers;
- imperfection of normative-legal and legislative base.

The equipment of thermal power plants and heating networks has a high degree of wear on average in Russia, reaching 70%. The total number of heating boiler houses is dominated by small, inefficient ones, the process of their reconstruction and liquidation proceeds very slowly. The increase in thermal capacities annually lags behind the increasing loads by 2 times or more. Due to systematic interruptions in the provision of boiler fuel in many cities, serious difficulties annually arise in the heat supply of residential areas and houses. The launch of heating systems in the fall stretches for several months, "underheated" residential premises in the winter have become the norm, not the exception; the rate of equipment replacement is declining, the number of equipment in emergency condition is increasing. This predetermined in recent years a sharp increase in the accident rate of heat supply systems.

1. The distribution of the heat load of heat energy consumers in the heat supply system between heat energy sources supplying heat energy in this heat supply system is carried out by the body authorized in accordance with this Federal Law to approve the heat supply scheme, by making annual changes to the heat supply scheme.

1) on the amount of heat energy that the heat supply organization undertakes to supply to consumers and heat supply organizations in this heat supply system;

2) on the amount of capacity of thermal energy sources, which the heat supply organization undertakes to support;

3) on current tariffs in the field of heat supply and predicted specific variable costs for the production of thermal energy, heat carrier and power maintenance.

1) determining the subordination of dispatching services of heat supply organizations and heat network organizations, the procedure for their interaction;

2) the procedure for organizing the adjustment of heat networks and regulating the operation of the heat supply system;

4) the procedure for interaction between heat supply organizations and heat network organizations in emergency situations and emergencies.

As part of the supply of switchboard equipment, power cabinets and control cabinets for two buildings (ITP) were supplied. For the reception and distribution of electricity in heating points, input-distributing devices are used, consisting of five panels each (10 panels in total). Switching switches, surge arresters, ammeters and voltmeters are installed in the input panels. ATS panels in ITP1 and ITP2 are implemented on the basis of automatic transfer units. In the distribution panels of the ASU, protection and switching devices (contactors, soft starters, buttons and lamps) are installed for the technological equipment of heating points. All circuit breakers are equipped with status contacts signaling an emergency shutdown. This information is transmitted to the controllers installed in the automation cabinets.

To control and manage the equipment, OWEN PLC110 controllers are used. They are connected to the input / output modules ARIES MV110-224.16DN, MV110-224.8A, MU110-224.6U, as well as operator touch panels.

The coolant is introduced directly into the ITP room. Water supply for hot water supply, heating and heat supply of air heaters of air ventilation systems is carried out with a correction according to the outside air temperature.

The display of technological parameters, accidents, equipment status and dispatch control of the ITP is carried out from the workstation of dispatchers in the integrated central control room of the building. On the dispatching server, the archive of technological parameters, accidents, and the state of the ITP equipment is stored.

Automation of heat points provides for:

maintaining the temperature of the coolant supplied to the heating and ventilation systems in accordance with the temperature schedule;
maintaining the temperature of the water in the DHW system at the supply to consumers;
programming of various temperature regimes by hours of the day, days of the week and holidays;
control of compliance with the values of parameters determined by the technological algorithm, support of technological and emergency parameters limits;
temperature control of the heat carrier returned to the heating network of the heat supply system, according to a given temperature schedule;
outside air temperature measurement;
maintaining a given pressure drop between the supply and return pipelines of ventilation and heating systems;
control of circulation pumps according to a given algorithm:
- on/off;
- control of pumping equipment with frequency drives according to signals from PLC installed in automation cabinets;
- periodic switching main / reserve to ensure the same operating time;
- automatic emergency transfer to the standby pump according to the control of the differential pressure sensor;
- automatic maintenance of a given differential pressure in heat consumption systems.
control of heat carrier control valves in primary consumer circuits;
control of pumps and valves for feeding circuits of heating and ventilation;
setting the values of technological and emergency parameters through the dispatching system;
control of drainage pumps;
control of the state of electrical inputs by phases;
synchronization of the controller time with the common time of the dispatching system (SOEV);
start-up of equipment after restoration of power supply in accordance with a given algorithm;
sending emergency messages to the dispatching system.

Information exchange between automation controllers and the upper level (workstation with specialized MasterSCADA dispatching software) is carried out using the Modbus/TCP protocol.