Throttle washer. Why do you need a throttle washer for heating

When calculating the throttle washer installed at the heat consumption installations of industrial buildings,

Δ R w = R o.d. - (∆ R c + Δ R y),

where ∆ R s - pressure loss in the network from the input to the device, MPa;

Δ R y is the pressure loss in the heat-consuming installation, MPa;

R o.d. - available pressure after the throttle, installed on the thermal input, MPa.

The available pressure after the throttle washer installed on the heat input is taken based on the following conditions:

1) the size of the washer hole in the device must be at least 2.5 mm;

2) the heat consumption system must be hydraulically stable, i.e. so that the ratio of the pressure loss in the device (together with the washer) to the available pressure after the diaphragm at the thermal inlet is as close as possible to 1.

/ Throttle washers at the heat input and at the heat-consuming device are mounted, as a rule, on the supply pipeline after the shut-off valve between the flanges or in spurs. Washers are installed on the return pipeline only when the pressure in it is below static (taking into account the vapor pressure of superheated water). If, when installing a washer on the return pipeline, the system or device becomes dangerous for their strength under pressure, two washers must be installed: on the return pipeline to raise the pressure in it to the washer along the course above the static pressure (taking into account the vapor pressure of superheated water) by 0.05 MPa and on the supply pipeline to extinguish the remaining overpressure./

Throttle washer for installation in flanges

The throttle washer installed between the flanges is shown in the figure, and its dimensions are in the table. The hole diameter d is taken from the calculation. The thickness of the washer for pipes with a diameter of up to 89 mm is 2-3 mm, over 89 mm is 3-4 mm. If there is a valve or valve, the washer is installed between the valves (or valve) and the heat sink in a flange connection.

50. Thermal and hydraulic calculation of water-water sectional heater

Sectional heaters of the Mosenergo Heating System type, manufactured according to OST-34-588-68, have a wide practical application. The bodies of these heaters are made of steel pipes, and the heating surface is made of L-68 brass tubes with a diameter of 16/14 mm, the thermal conductivity coefficient λ=110.7 W/(m∙K). The tube sheets are welded to the heater body.

In water-to-water heaters, usually quite high heat transfer coefficients are achieved, approximately 1000-1500 W / (m 2 ∙K). Typically, heater sections are made in lengths of 4 m.

At closed system heat supply, when the connection of the hot water supply system is carried out through water-to-water heaters, the scheme for switching on these heaters is mainly determined by the temperature regime of the heating network and the ratio maximum spending heat for hot water supply and heating should be taken in accordance with SNiP 2.04.07-86:

a) 0.2 < < 1.0 - two-stage sequential scheme

where Q o - calculated thermal load heating, Gcal/h;

Q hot water supply - calculated heat load of hot water supply, Gcal/h;

b) for other ratios - according to a single-stage parallel scheme.

Rice. 50.1. Single-stage parallel water heater connection

Rice. 50.2. Two-stage serial wiring diagram

water heater

A two-stage sequential connection scheme for hot water heaters is usually used with increased temperature chart(schedule of central regulation by total load).

The calculation sequence is as follows:

1) according to the given loads, the water-to-water heater connection scheme is determined;

2) the type of heater and the corresponding specifications from the table;

3) sequential calculation is carried out in accordance with the connection diagram;

4) at the end, it is checked that the total hydraulic resistance for network water at a flow rate network water was not more than 50 kPa. If the value of the hydraulic resistance turned out to be greater, then it is necessary to change the type of heater to a higher one, and repeat the calculation, taking into account the characteristics of this heater.

The sequence of calculation for a single-stage

parallel connection of the heater:

1. Average temperature of heating water, 0 С

t gr.av =( t 1 - t 2)/2,

where t 1 - heating water temperature at the heater inlet, 0 С;

t 2 - temperature of the heating water at the outlet to the heater, 0 C.

2. Average temperature of heated water, 0 С

t n.sr =( t P1 - t P2)/2,

where t P1 - temperature of heated water at the inlet to the heater, 0 С;

t P2 - the temperature of the heated water at the outlet to the heater, 0 C.

3. Heating water consumption, kg/h

,

where is the thermal performance of the water heater in the design mode, kcal/h.

4. Consumption of heated water, kg/h

5. Speed ​​of heating water (in the annulus), m/s

,

where - the area of ​​​​the living section of the annular space, m 2;

Any organization that operates a heat supply system must be able to carry out and adjust. There are several basic steps to carry out this operation, as well as one important element- throttle washer.

Step one. Calculations

It should be noted that two identical heating systems do not exist. However, certain patterns were noticed that are repeated when adjusting the thermal system. The first step in more than 90% of cases is the moment of hydraulic calculation. There are several options for this operation.

Option 1. Manual calculation option. In this case, you must have at hand all the necessary reference literature, and the calculation is carried out step by step on each required section of the network. If on any segment an incorrect answer occurs, then it is necessary to change the parameters and carry out the computational work again. The main disadvantage of this work is long term implementation, and the process itself is very laborious.

Option 2. An expensive electronic computer is bought, which is able to carry out all calculations accurately and quickly. It will take only some time to study it, and then the necessary parameters are simply entered.

Option 3. Currently, there are organizations that provide services specifically for the calculation of all the necessary network parameters.

Step two. readiness

In the second step, it is necessary to determine whether the thermal system is ready for regulation. In order to carry out this step, it is necessary to resort to installing a throttle washer. There are several types of mounting.

The first option is based on the fact that the company does not rely too much on the calculations and the results obtained. In this case, washers are installed in some places that need to be checked. Here it is worth noting that the diameter for each device will be rounded. Moreover, rounding will occur in the direction of the drill with the largest diameter. However, experts say that this method is terribly inefficient. It's best not to use it at all.

Mounting washers

There are two other ways to check. The second option is the production of throttle washers with a clear bore diameter. After their manufacture, they are installed in the system. In this case, you have to mount about 100 washers, if not more. Therefore, it often happens that installation workers miss up to 10 devices. However, even in this scenario, the data obtained will be quite correct. The percentage of measurement error in this case will be equal to 20-25% in any direction.

The third option is to install an adjustable throttle washer. In this case, some people have a question about why to carry out the calculation if the washer is adjustable. The answer is simple enough. When performing computational operations, you need to find out if the value falls within the diameter of the device. This operation is necessary, since the diameter of the throttle washer can vary from 5.5 to 18 mm.

Defects in the system

Naturally, no one is immune from mistakes, and such a situation can always arise. For example, after starting the heating system, it will be seen that a certain amount consumers, the actual consumption is much higher than the calculated one. In such a situation, you must do the following. It is immediately necessary to determine which devices were used during setup. If all throttle washers are non-adjustable, then the following must be done.

A complete recount of all problem areas. The devices installed in them are removed, the diameter of the holes of the device changes, after which they are mounted back. After that, a recalculation is carried out, in which, most likely, about 20% of consumers, and not 40, will turn out to be problematic. Most often, it is not possible to carry out the third adjustment, since heating season already going. Because of this, some people have problems with heating.

Adjustment with adjustable washers

If throttle washers were installed during installation, which are subject to adjustment, then the process will take only a couple of days, and it will be possible to carry it out more efficiently. You need to do the following. For a certain period of time, the duration of which depends on the inertia and the load on heating network, you need to adjust the device. It is important to note here that adjustment work can be carried out without disconnecting the consumer from the source. It is necessary to carry out such a setup process at each facility for which the actual consumption does not coincide with the calculated one. After the adjustment work is fully completed, the devices that were adjusted are sealed, and their setting values ​​\u200b\u200bare written next to them.

As practice shows, conducting quality adjustment works for heating with throttle washers is only possible if they are all adjustable.

Device design

If we talk about the design of this device, then it has next view. Appearance- this is a steel disk, the thickness of which is 14 mm, and in the middle there is an oval hole. In addition, there are two rods that are located diametrically in relation to each other. They exit through the side sealing holes. When these elements are fully connected, they partially cover what is inside the disk. In addition, these rods can move radially inside the washer.

Changing the position of these parts will also change the flow area of ​​the hole in the disk. If they are fully retracted, that is, closed, then the cross section will be 5.5 mm. If you fully open these parts, then the diameter will be equal to 18 mm. The throttle washer is installed between the flanges. It is also important to note that it is possible to limit the movement of the rods if the part is sealed. In addition, such devices are additionally supplied with keys for adjusting the cross section.

Purpose of the device

The main purpose of the adjustable throttle washer is the adjustment of the heat supply system. hallmark was that the installation of such devices made it possible to change the characteristics without its depressurization. This type of washer allows you to change, as well as fix its throughput.

If we compare the characteristics and application of this unit with others, then it is completely similar to a device such as MSV-F2. The only difference between them is that the washer cannot be used as a stop valve.

It is important to note that after thermal system install such washers, the total consumption in them is reduced by 1.5-3 times. Thanks to this, it is possible to reduce the number of pumps in operation at the station. All this leads to the fact that it becomes possible to save electricity, fuel, etc. A throttle washer is made according to the drawings.

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This led to the need to install throttle washers on all boiler coils, similar to how it was done in boilers with multiple forced circulation, as well as to the use of intermediate manifolds installed on separate sections heating surfaces. The installation of throttle washers, changing the hydraulic resistance of the coils (see Chapter XVI), makes it possible, by selecting the appropriate sections for the passage of water, to ensure the alignment of its flow rates for individual coils.

Throttle washers can be installed on the supply or return heat pipe or on both heat pipes. When installing throttle washers at the inlet of the heating system, they should be installed: on the supply pipeline - with a significant pressure in it, on the return pipeline - with a slight pressure in it in order to create a backwater in the heating system. It is not recommended to install throttle washers with a diameter of less than 2-5 mm.

After a five-minute purge, valves 2, bis and 5 are closed and the pressure in the blower housing begins to rise to the pressure in the manifold. Thanks to the installation of a throttle washer with a diameter of 20 mm after valve 4, the pressure is smoothly equalized within 3 minutes. In this case, it is necessary to monitor the operation and temperature of the supercharger and the speed of the turbine.

This is achieved by increasing the resistance of the economizer-grain section, for which it grows almost in proportion to the square of the flow rate. The resistance is increased by installing throttle washers at the inlet to each steam-generating pipe or by reducing the diameter of the economizer pipes, obtaining a stepped coil.

Then the individual branches are calculated. Equalization is carried out by installing throttle washers or a pipe segment of a smaller diameter.

Circulation circuits are made of both horizontal and vertical pipes with lifting and lowering movement, and individual circuits may be of unequal length. However, their resistance by installing throttle washers of appropriate diameters is selected so that it corresponds to the heat absorption of the circuit.

Acting as throttle washers, the latter make the hydrodynamic characteristic stable. In this case, there is no need to install throttle washers. To reduce the thermal spread, the inner diameter of the evaporator tubes is chosen relatively large (50 mm), which makes it possible to design screens with a small tape width.

Boilers of the new series are calculated for operating conditions at an initial gas temperature of up to 650 C. Uniform circulation of water between parallel coils is achieved by installing equalizing throttle washers with a diameter of 8 mm. If necessary, boiler plants produce additional upstream evaporator sections, and in this case, waste heat boilers joint work with evaporative cooling can be used at the initial gas temperature up to 850 C. The operation of the upstream sections was tested on boilers of the KU-80 and KUU-80 types and showed quite satisfactory results.

The obtained critical dimensions of the throttle washers are comparable with the experimental data available in the literature. Based on the materials of L.K. Ramzin, we find that for SPPN-200 / 35, when installing throttle washers dm8 mm, the oscillations did not stop, but at s.

For boilers with a pressure of more than 0 8 MPa (8 kgf / cm2), at least two shut-off devices or one shut-off and one regulating one must be installed on each purge, drainage pipeline, as well as the water (steam) sampling pipeline. In boilers with a pressure of more than 10 MPa (100 kgf / cm2) on these pipelines, in addition, the installation of throttle washers is allowed. To purge the chambers of superheaters, it is allowed to install one shut-off element. The conditional passage of the purge pipelines and fittings installed on them must be at least. MPa (140 kgf / cm2) and not less than 10 mm for boilers with a pressure of 14 MPa (140 kgf / cm2) and more.

For boilers with a pressure of more than 0 8 MPa (8 kgf / cm2), at least two shut-off devices or one shut-off and one regulating one must be installed on each purge, drainage pipeline, as well as the water (steam) sampling pipeline. In boilers with a pressure of more than 10 MPa (100 kgf / cm2) on these pipelines, in addition, the installation of throttle washers is allowed. To purge the chambers of superheaters, it is allowed to install one shut-off element. The conditional passage of the purge pipelines and fittings installed on them must be at least 20 mm for boilers with a pressure of up to 14 MPa (140 kgf / cm2) and at least 10 mm for boilers with a pressure of 14 MPa (140 kgf / cm2) and more.

On the open tab, we will try to find and select the necessary parts of the system for your apartment. Any node is unambiguously important. Based on this, the selection of each part of the system must be done correctly. Cottage heating installation includes important devices. Heating installation includes, air vents, collectors, connection system, pipes, fasteners, boiler batteries, expansion tank, thermostats, pressure increasing pumps.

A modern analogue for systems with constant hydraulic mode is an balancing valve. the resistance of which can be changed by manual adjustment, and the specified setting is sealed.

Despite this, throttling diaphragms are still used to reduce capital costs or according to the conservative requirements of old-school officials in heat supply organizations.

Throttle Bore Diameter Calculation

D = 10 *(G²/dP) 0.25. mm

• G is the volumetric flow rate of water, m³/h;
• dP - pressure drop across the diaphragm, m.a.c.

Source: http://www.ktto.com.ua/calculation/drosselnaya_shayba

To calculate the diameter of the throttle washer hole in the ITP, the following formula is given:

D0 = 10*[^ 1/4(Gр^2/H)]

The question is what is meant by H?

Or is it the available head H1 in front of the throttle washer, then the washer turns out to “eat” all the excess pressure, equalizing the pressure of the direct and return lines and there will be no conditions for circulation.

Or is it the head, taking into account the deduction of head losses in the internal heating system of the house (H2), i.e. (H1 - H3), where H3 is the head loss in the house?

I checked my doubts on the program for the hydraulic calculation of the heating network, recently downloaded from the same forum, H1 is laid in it.

Or third, the question claims to be idiotic?

Drawing in application

Attached files

Source: http://forum.abok.ru/index.php?showtopic=60250

Pucking of thermal networks is produced in order to distribute the coolant flows between consumers in accordance with their needs. Unregulated hot water from a heat source for the most part enters buildings located near the boiler house. The remaining small volume of water is sent to the periphery. Remote buildings lack heat, they freeze, while in nearby buildings there is overheating. People, opening the windows, literally heat the street.

To prevent this from happening, restrictive washers with a calibrated hole of a smaller cross section than the pipeline are installed on the branches of heating networks to buildings. This makes it possible to increase the volume of coolant for remote buildings.

Washers (hole size) are calculated for each house depending on the required amount of heat. A positive result from the washing of heat networks can only be obtained in the case of 100% coverage of all buildings connected to the heat network. In parallel with the washer, it is necessary to bring the operation of the pumps in the boiler room into line with the hydraulic resistance of the heating network and.

The effect of installing washers

After installing the washers, the coolant flow through the pipelines of the heating network is reduced by 1.5-3 times. Accordingly, the number of operating pumps in the boiler room also decreases. This results in savings in fuel, electricity, chemicals for make-up water. It becomes possible to increase the temperature of the water at the outlet of the boiler room. For more information about setting up external heating networks and the scope of work, see ... ..Here you need to give a link to the section of the site "Setting up heating networks"

Pucking is necessary not only for regulating external heating networks, but also for the heating system inside buildings. The risers of the heating system, located further from the heat point located in the house, receive hot water less, it's cold in the apartments here. It is hot in apartments located close to the heat point, since more heat carrier is supplied to them. The distribution of coolant flow rates among risers in accordance with the required amount of heat is also carried out by calculating washers and installing them on risers.

Stages of washing the heating system

• Hydraulic calculation of the heating system, calculation of washers
• Development of recommendations for improving the operation of the heat point, heating system
• Installation of control washers on risers (this work can be carried out by the customer independently)

• Verification of implementation of recommended activities
• Analysis of the new steady state after washing the heating system
• Correction of the size of washers in places where the required result is not achieved (by calculation)
• Dismantling washers requiring adjustment, installing new washers

On the internal systems heating washers can be installed in both winter and summer. Check their work - only in the heating season.

Reducing the cost of work is possible if the installation of the washers is assumed by the customer under the supervision of the contractor.

Service order

Order the calculation and installation of heating system washers in LLC "Center for Design and Energy Saving" by tel.

We link the risers according to the formula:

On those risers where the linkage of pressure losses in the risers is more than 15%, then on these risers we provide for the installation of a diaphragm (throttle washer) according to the formula (5.6):

, mm (5.6)

where G st - coolant flow in riser No. 5 (table 4.3);

р sh – required pressure loss in the washer, Pa.

For riser No. 6:

For riser number 9:

6 Selection of heating unit equipment

Building heating systems should be connected to heating networks:

Through the elevator, if necessary, to reduce the temperature of the water in the heating system and the available pressure in front of the elevator, sufficient for its operation;

6.1 Heating substation with dependent connection, water jet elevator and facade regulation

The main equipment of the thermal unit

water jet elevator;

heat meter;

sump;

hand pump;

input fittings;

drain fittings;

air outlet fittings;

instrumentation.

6.2 Selection of non-adjustable water jet elevator

Water jet elevators are designed to lower the temperature of superheated water coming from the heating network into the heating system to the required temperature by mixing it with water that has passed through the heating system. The elevator consists of a nozzle, a suction chamber, a mixing chamber and a diffuser.

In design practice, a water-jet elevator brand 40s106k TU26-07-1255-82 is used, made of carbon steel with a coolant temperature of up to 150 ° C (Figure 6.1).

Figure 6.1. Scheme of a water jet elevator

Table 6.1 - Structural characteristics of various sizes of the 40s10bk elevator

The determination of the elevator number, the diameter of the nozzle and the mixing chamber is carried out by calculation in the following order.

The water consumption in the heating system is determined by the formula, t / h:

(6.1)

where
- total heat loss of the building, W;

c - specific heat capacity of water, equal to c \u003d 4.187 kJ / (kg ° C);

t g, t o - parameters of the coolant in the supply and return pipelines of the heating system, ° С.

(t/h)

The mixing ratio is calculated:

(6.2)

where  1 \u003d 150 ° С are the parameters of the coolant in the supply pipeline in the heating network.

The calculated diameter of the mixing chamber of the elevator, mm, is determined by the formula:

(6.3)

where
\u003d 1.285 kPa - the required pressure developed by the elevator, taken equal to the pressure loss in the main circulation ring.

The calculated nozzle diameter, mm, is calculated by the formula:

(6.4)

=3 mm

The pressure required for the operation of the elevator, 10 kPa, is determined by the formula:

(6.5)

There is pressure in front of elevator node, 10 kPa, taking into account hydraulic losses in the pressure regulator according to the formula:

(6.6)

kPa

After determining the calculated diameter of the mixing chamber d k , mm, according to Table 6.1, the number of the elevator with the nearest largest diameter d k (d k = 15 mm) is selected.

Accepted elevator 40s10bk No. 1, d k =15 mm.