RU2761689C2 - System for central heating and hot water supply, operating mode control and heat consumption control - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: at the heat point, cold water for hot water supply is heated and directed to buildings through pipelines of the recirculation system to be consumed by residents. Excess hot water is returned to the heat point, wherein heated water is admixed to compensate for hot water consumption and heat losses. In the unit for preparing a heat carrier for heating, a heat carrier with a temperature linearly dependent on the reduction in the atmospheric temperature is prepared by mixing the return with a hot heat carrier. The heat carrier is supplied to the buildings at a constant pressure. At least one heating circuit with heat carrier recirculation is provided in each building, wherein constant pressure is maintained. Heat carrier from the heating point is admixed to the heating circuit using an injector. The flow rate of the admixed heat carrier is controlled in each building to achieve a set indoor temperature once at any steady-state temperature of the atmosphere. A comfortable indoor temperature is thus provided at any temperature of the atmosphere. Excess heat carrier is directed to the return pipeline of the heat point from the heating circuit of the building.

EFFECT: ensured control of central heating and hot water supply.

1 cl, 2 dwg

Description

The invention relates to heating systems for residential and other buildings and hot water supply of residential buildings.

From the existing state of the art, devices for heating and hot water supply are known (RU 2719170, RU 2710632, RU 2710633, RU 2677108, RU 2676579, 2674713), which propose different methods and devices for regulating the temperatures of the heat carrier and hot water, as well as a method for controlling the filling of the system heating and draining the coolant from the system (RU 2372560, RU 2313731). Known methods for determining heat loss from a consumer by influencing the premises with stepwise changes in heating power (RU 2655640) and a method for regulating heat supply according to calculated schedules (2642038). The disadvantages of these inventions are a detailed substantiation of the solution of individual control problems by known methods of controlling the temperature regime of heating according to the calculated schedules, which do not provide sufficient accuracy in setting the thermal regime of the premises.

In the book. M. Makhov "Heating", Moscow, 2014. - a textbook of universities sets out the theoretical foundations and recommendations for the organization of space heating. There is a controversial statement; “With a one-pipe system,“ water flows sequentially through all devices ”(heating).

The closest to the claimed are the heat supply and hot water supply systems, described in the regulatory document of the Ministry of Construction of the Russian Federation SP41-101-96 "Design of heating units".

The systems described in this document have significant drawbacks.

1. It is recommended to connect the heating systems of buildings directly to heating networks with a coolant temperature of up to 150 ° C, which will lead to overheating of the basement floor and the walls of the building.

2. If it is necessary to reduce the temperature of the heat carrier supplied to the building, it is recommended to use an elevator and pressure regulator at the inlet to the heating point, to regulate the temperature difference in the supply and return pipelines.

Heat output to a building can be determined from the temperature difference. But the amount of thermal energy required to heat a building is not determined by the temperature difference but by the temperature of the batteries and depends on the ambient temperature. If there is a control of the elevator cross-section, the stabilization of the pressure at the inlet to the heating point is unnecessary.

3. There is a circuit for controlling the temperature of the coolant taking into account the outside air temperature using a pressure regulator, a regulating valve on the supply pipeline and a differential pressure regulator using a pump on the return pipeline used to mix the cooled coolant. This circuit is unnecessarily complex and the regulators interfere with each other. The calculated temperature schedule does not provide the target air temperature in the building.

4. In the unit for heating water for hot heating, cold water is mixed with the return water and enters the heat exchanger, from which it is supplied to the buildings. The pumps are installed at the return pump and for supplying water to buildings. This reduces the efficiency of heat transfer and leads to errors in the measurement of heat consumption. The use of two pumps is not justified.

The weather control system of Intelpribor LLC provides for work with an elevator and is designed to fulfill the MOEK temperature schedule for temperatures in the supply and return pipelines of the heating unit, which does not guarantee the specified thermal regime of a particular building and requires complex adjustment operations.

There are a number of patents for inventions (RU 2729177 (issued on 06/16/2006); RU 2310820 (06/16/2006); RU 2300086, RU 2300087, RU 2300088 (03/23/2006); and others, as well as heat metering devices Intelprobor ", Having two flow meters, two temperature meters and two pressure meters of the heat carrier. They calculate the weight flow rates of the heat carrier in the supply and return pipelines, taking into account the dependence of density on pressure and temperature. The difference in flow rates determines the leakage of the heat carrier. Calculate the heat consumption for heating and hot water supply by the difference between the heat fluxes in the supply and return pipelines, taking into account the dependence of the heat content on pressure and temperature.At the same time, the patent RU 2300086 refers to GSSSD 188-99, which gives the dependence of the enthalpy of water in the temperature range 0-1000 ° C and pressures 0у001-1000 MPa However, the density of water in the range from 1 to 25 bar changes by 0.2%, which is negligible. The density of water in the temperature range from 0 to 100 ° C changes by 3%, the volume heat capacity of ox by 2.5%, and in the temperature range 30-80 ° С - 2%. You can take the average value of the volumetric heat capacity of water when calculating the heat consumption. The deviation from the average value in this temperature range will not exceed 1%, which is within the permissible additional errors for devices of class 3 and 5. Therefore, the easiest way is not to calculate the weight flow rate of the coolant taking into account its temperature and take into account the thermal dependence of the weight heat capacity of water, but simply take into account the average value of the volumetric heat capacity of water in the desired temperature range of the coolant

The mass flow rate of the coolant is also not needed: it is enough to know the volume flow rate measured by all flow meters.

It is much more important to increase the accuracy of control of heat consumption to measure not two temperatures, but their difference, the error of which is half the error of the calculated difference between two temperature measurements.

Further reduction of the error will be achieved if a heat meter is used with a standard size of the flow meter included in it, corresponding to the range of changes in flow rate at the controlled object and the design of the heat meter will provide the ability to set the heat capacity value in the operating temperature range and select the temperature difference measurement range. For example, in the heating circuit of a building, it is necessary to supply a heat carrier with temperatures from 30 to 80 degrees and the temperature difference between the added heat carrier and the heat carrier in the heating circuit will be from 3 to 30 degrees.

As the inventors correctly point out, the error in controlling the flow rates is many times greater than the possible leakage of the coolant, and it is impossible to determine the leakage from the difference in flow rates. However, they propose a method to calibrate flow meters in order to detect leaks.

Leakage of coolant can occur due to a malfunction of the oil seals. Its presence is easiest to determine by inspection of the equipment.

The use of two flow meters to account for heat consumption for hot water supply leads to gross errors. From the product of the flow rate of the coolant in the supply pipeline by the difference in the heat content of hot and cold water, subtract the product of the flow rate of the coolant in the return pipeline by the difference in the heat content in front of the heat exchanger and the heat content of cold water. In this case, there is no cold water temperature sensor and I accept its value as 5 ° C. And this is not a major mistake. The water return flow rate is measured before mixing with cold water, and the return temperature is measured after mixing, therefore it is lower than the temperature in the supply pipeline. To calculate the heat consumption for the preparation of hot water, the water consumption in the supply pipeline must be multiplied by the heat capacity of the water and the temperature difference before and after the heat exchanger. And it is even easier to heat only cold water, multiply its consumption by the heat capacity and by the temperature difference before and after the heat exchanger.

In the same way, the heat consumption for heating with the open method can be determined by the flow rate of the mixed coolant and the temperature difference between the injected coolant and the coolant in the heating circuit of the building.

Simpler and cheaper house and apartment heat meters can cope with this task. It is easier for them, as well as for ox counters, to calculate monthly payments.

As a prototype of the invention, a certain SP41-101-96 "Design of heat points", a central heating and hot water supply system was adopted.

The aim of the invention is to maintain comfortable temperatures in buildings, prepare hot water at a given temperature and economical heat consumption.

To achieve this goal, in a central heating and hot water supply system, operating mode control and heat consumption control, consisting of a heating station, several heating points and heated buildings, at least one central hot water preparation unit and one heat carrier preparation unit for heating with appliances automatic control and monitoring at each heating point and at least one heating circuit of each building,

- only water from the cold water pipeline is heated in the heat exchanger of the hot water preparation unit;

- the outlet pipe of the heat exchanger together with the hot water return pipe is connected to the inlet of the circulation pump;

- a flow meter and a temperature sensor are installed on the cold water pipeline at the inlet to the heat exchanger;

- temperature sensors are installed on the pipeline after the heat exchanger and on the pipeline after the pump;

- the temperature of the hot water after the heat exchanger is regulated by changing the flow rate of the coolant flowing countercurrently to the water;

- the set temperature value is determined by the difference between the standard value and the temperature after the circulation pump;

- the central heating unit consists of a liquid elevator installed on the supply pipeline, a booster pump, a manifold for distributing a coolant to heating circuits of buildings, an automatic coolant temperature regulator, a flow meter at the outlet of the booster pump, a heat meter and a frequency regulator of the pump drive speed;

- the elevator is equipped with an electric drive to change the flow rate of the hot coolant;

- the coolant return pipeline is connected to the elevator;

- a check valve is installed in front of the pump to prevent leakage of the coolant when the booster pump is stopped;

- automatic regulator of the coolant temperature has an ambient temperature sensor and a coolant temperature sensor;

- frequency speed controller is used to stabilize the coolant pressure after the booster pump in operating mode and control the coolant flow rate when filling the heating circuits of buildings;

- in each building, at least one heating circuit is installed, consisting of an elevator with a manual control of the nozzle section, a circulation pump, horizontal pipelines in the basement of the building and on the technical floor, risers for distributing coolant to rooms on different floors, heating batteries, air release devices from the heating circuits and a pressure regulator in the lower part of the circuits to prevent the formation of a vacuum in the circuits;

- using an elevator, the flow rate of the heat carrier from the central heating unit is adjusted to obtain the set temperature of the heat carrier in the heating circuit of the building at any outside temperature;

- pipelines for the return of the heat carrier of each building are connected to the pipeline for the return of the heat carrier at the heating point, where the excess of the heat carrier is supplied after the pressure regulators;

- to account for the heat consumption, a heat meter is used, which measures the flow rate of the replenishment with the heat carrier coming from the central heating unit, and the temperature difference between this heat carrier and the heat carrier in the heating circuit of the building.

The technical result, due to this set of features, is the most efficient use of the heat transfer area of the heat exchanger and the temperature potential of the coolant when preparing hot water, ensuring the optimal room temperature in all weather conditions and therefore the optimal heat consumption for heating buildings.

To explain the essence of the invention and the reasons for achieving the technical result, the graphs of temperature regimes are used in Fig. 1 and the technological diagram of the central heating and hot water supply system, shown in Fig. 2.

Since the thermal conductivity of the metal is high and the heat transfer coefficient from the water coolant to the metal of the batteries is high, and the heat transfer to the air of the premises with its free convection is very low, the temperature of the surface of the pipes and the upper part of the batteries practically coincides with the temperature of the coolant in the heating circuit of the building. The coolant that fills the batteries is cooled, giving off heat to the air in the room. The denser cooled heat carrier is lowered to the bottom of the batteries and then, at a very low flow rate, is forced into the riser of the building heating circuit. Under the action of a circulation pump, the flow rate of the coolant in the risers is high, which ensures a practically insignificant temperature difference along the height of the riser and equal heating of the premises on all floors. Make-up with hot coolant ensures that the temperature of the coolant is constant over time.

The heat losses of the building caused by heat transfer through walls, windows and doors and the intake of cold outside air through windows and doors are proportional to the difference between the outside air temperatures T and the room temperature p. Heat transfer from heating batteries is proportional to the difference between the temperature of the batteries (and the coolant in them) t and the temperature of the room air p. At a steady temperature of air, building partitions and internal surfaces of the walls of the room, the ratio of these differences is a constant K = (p-t) / (T-p).

This constant can be simply calculated from the results of temperature measurements after a sufficiently long period of time after the start of the heating season. A delay in the heating season violates the rights of consumers to a comfortable temperature and leads to the need to supply a heat carrier with elevated temperatures to compensate for the heat consumption for heating the building.

In fig. 1 shows various graphs of the dependence of the temperature of the coolant on the ambient temperature. The two upper solid lines represent the schedule recommended by PJSC MOEK for heat points. Line "P" corresponds to the temperature of the coolant in the supply pipeline. Line "B" corresponds to the temperatures in the return line. These charts are taken as a basis for setting the weather regulators for room temperatures. The temperature difference between the graph lines is from 3 to 20 degrees and characterizes the recommended use of the coolant potential.

The lowest solid line "K = 0.7" reflects the temperature of the batteries required to obtain an air temperature of 20 ° C in the premises of the house with improved thermal insulation. The dotted graphs reflect the temperatures of the coolant required to reach an air temperature of 20 ° C in rooms characterized by the K coefficient with values of 0.8, 1 and 1.2, respectively. The graph "1.2" coincides with the line "P" at a temperature of -40 ° C and lower by 4.5 ° C at a temperature of 10 C, since it does not take into account the costs of heating a building that has cooled down by the beginning of the heating season. Graph "B" corresponds to the temperatures of the heat carrier, providing a temperature of 26 ° C in a room with K = 0.8. That is, for the same reason, it is designed to supply an excessive amount of heat to heat the building.

The greatest difference in the temperatures of the coolant in the supply and return pipelines according to the MOEK schedules is 20 degrees. If the heating agent is supplied from the heating point to the buildings according to the schedule K = 1.2, then for buildings with K = 0.7 and K = 0.8, the temperature gap will be greater than 20 ° C and therefore their heating will be ensured at a lower heat carrier flow rate, than according to the MOEK schedules.

It is possible to reduce the K coefficient for any room not only with the help of improved thermal insulation or sealing of doors and windows (but less oxygen will enter the room), but also by increasing the area of the heating batteries. The same value of the coefficient K for all rooms of one building will be ensured if the area of the heating battery in each room is proportional to the area of the outer walls of this room, including for rooms in the corners of the building.

At any outside temperature (for greater accuracy at low), the flow rate of the hot coolant is selected, which ensures the set temperature of the batteries and the room air. Then, at any other outside air temperature, the room temperature will not change, since the temperature of the hot heat carrier changes in proportion to the decrease in the outside air temperature and at a constant flow rate of the heat carrier, the heat inflow will increase in proportion to the decrease in the outside air temperature. This will ensure comfortable heating conditions in all weather conditions.

The device of the heating and hot heat supply system at the heat point, proposed in this invention, is illustrated by the diagram in Fig. 2.

The heating point is supplied with a hot coolant through the supply pipeline 1; the cooled heat carrier is returned through the return pipeline 2. Cold water is supplied through the water pipeline 3. Flow meters 4 control the flow of the heat carrier and water. The temperature of water and heat carrier in all sections is controlled by resistance thermometers 6. Heat meter 5 controls the consumption of heat supplied to the heating point. Heat meter 7 controls the heat consumption for hot water supply. Heat meter 8 controls the heat consumption for heating all buildings served by the heat point. Each building can have its own meter installed in the heating circuit.

When heating water for hot water supply, a heat exchanger 9 with a counterflow of water and a heat carrier is used, which ensures the full use of the potential of the heat carrier, which is cooled to a temperature close to the temperature of cold water. Heated water together with hot water from the return pipeline enters the pump inlet 10, is supplied to the buildings, and returns through the pipelines 11. The heating of water in the heat exchanger 9 is controlled by a multi-channel controller 12 using temperature sensors 6 at the outlet of the heat exchanger and at the outlet of the pump. 10. As a result, when hot water is consumed, the set temperature is maintained, and in the absence of flow, the circulation pump can be stopped by a signal from the heat meter. 7. When hot water consumption is stopped, there is no water flow through the heat exchanger. The temperature of the water in the pipeline after the pump decreases, which is recorded by the temperature sensor after the pump and leads to an increase in the regulator setting and an increase in the water temperature in the heat exchanger. When the water flow is resumed, the pump turns on, water from the heat exchanger enters the network and compensates for the drop in temperature in the network.

In the central heating unit, a liquid elevator (injector) 13 with an electric drive of the adjusting needle and a frequency controller 14 of the pump 15 speed are used to control the flow rate of the coolant when filling the system and the pressure of the coolant in the operating mode. The multichannel temperature controller 12, using the heat carrier temperature sensor 6 and the outside air temperature sensor 17, controls the heat carrier temperature depending on the outside air temperature.

Through the collector 16 and pipelines 18, the coolant with a given temperature and with a stabilized pressure enters the heating circuits of buildings

In each heating circuit of the building, in addition to radiators, risers and horizontal pipelines in the basement and on the technical floor, there is a circulation pump 19 and an elevator 20 with manual control for adjusting the replenishment of the heating circuit of the building with a heat carrier at a given temperature from the central heating unit.

The excess coolant through the pipeline 21 with a direct-acting pressure regulator 22 enters the pipeline 2 for the return of the coolant. Pipeline 2 also has a pressure regulator 23, which provides a pressure in it sufficient to ensure the suction of the returned coolant by the elevator 13. Since the pressure at the inlet to the elevator 20 is stabilized by the frequency control of the pump of the central heating unit and in the building circulation circuit by the regulator 22, then with a fixed the position of the needle of the elevator 20, the flow of heat carrier has a constant flow rate. When the ambient temperature changes, the make-up temperature and the temperature in the heating office of the building change, which ensures the constancy of the set room temperature.

This ensures a comfortable air temperature in the building and prevents excessive heat consumption.

To solve all problems, at any time of the year, a heat carrier with a temperature of up to 95 ° C, and not overheated water, can be sent to a heating point. This temperature will be sufficient for hot water supply and heating of buildings at any ambient temperature. Only at -40 ° С will a heat carrier with a temperature of 92 ° С enter the buildings and return with a temperature of 50 ... 60 ° С. At zero ambient temperature this will be 40 ° C and 30 ... 40 ° C, respectively, and at the beginning of the heating season about 30 ° C.

The filling of the pipelines begins with setting the operating pressures on the regulators 22 and 23. The heat carrier is supplied to the heat exchanger 7 and the air from their hot water preparation system is removed. After increasing the pressure to the level provided for the return pipeline, the flow rate of the coolant for heating the water is determined and the resulting value is used to set the flow rate to the pump drive controller 15. The coolant temperature controller 12 is turned on. affecting the speed of the pump motor.

Air is vented in the heating circuits of buildings. The system begins to operate in operating mode.

Claims (17)

A central heating and hot water supply system, operating mode control and heat consumption control, consisting of a heat station, several heat points and heated buildings, at least one central hot water preparation unit and one heat carrier preparation unit for heating with automatic control and monitoring systems for each heating point and at least one heating circuit of each building, characterized in that in order to maintain comfortable temperatures in the premises of buildings, prepare hot water at a given temperature and economical heat consumption: - only water from the cold water pipeline is heated in the heat exchanger of the hot water preparation unit; - the outlet pipe of the heat exchanger together with the hot water return pipe is connected to the inlet of the circulation pump; - a flow meter and a temperature sensor are installed on the cold water pipeline at the inlet to the heat exchanger; - temperature sensors are installed on the pipeline after the heat exchanger and on the pipeline after the pump; - the temperature of the hot water after the heat exchanger is regulated by changing the flow rate of the coolant flowing countercurrently to the water; - the set temperature value is determined by the difference between the standard value and the temperature after the circulation pump; - the central heating unit consists of a liquid elevator installed on the supply pipeline, a booster pump, a manifold for distributing the coolant to the heating circuits of buildings, an automatic coolant temperature regulator, a flow meter at the outlet of the booster pump and a frequency regulator of the pump drive speed; - the elevator is equipped with an electric drive to change the flow rate of the hot coolant; - the coolant return pipeline is connected to the elevator; - a check valve is installed in front of the pump to prevent leakage of the coolant when the booster pump is stopped; - automatic regulator of the coolant temperature has an ambient temperature sensor and a coolant temperature sensor; - the frequency regulator is used to stabilize the coolant pressure after the booster pump in operating mode and to control the coolant flow rate when filling the heating circuits of buildings; - in each building, at least one heating circuit is installed, consisting of an elevator with a manual control of the nozzle section, a circulation pump, horizontal pipelines in the basement of the building and on the technical floor, risers for distributing coolant to rooms on different floors, heating batteries, air release devices from the heating circuits and a pressure regulator in the lower part of the circuits to prevent the formation of a vacuum in the circuits; - using an elevator, the flow rate of the heat carrier from the central heating unit is adjusted to obtain the set temperature of the heat carrier in the heating circuit of the building at any outside temperature; - the pipelines for the return of the heat carrier of each building are connected to the pipeline for the return of the heat carrier at the heating point, where the excess of the heat carrier is supplied after the pressure regulator; - to account for the heat consumption, a heat meter is used, which measures the flow rate of the replenishment with the heat carrier coming from the central heating unit, and the temperature difference between this heat carrier and the heat carrier in the heating circuit of the building.

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