Boost pumps for water. Booster pumping units

The pressure that needs to be developed by the booster unit is determined by formula (1.7)

H p = H geom + ∑ H L + H f - H g (1.7)

H p =8+15+3-22=4 m.

We install the TsNSh-40 pump with the following characteristics: flow - 7 m 3 / h, head - 6 m, rotation speed 1350 min -1, power - 0.6 kW. With the help of this pump the required head of 26.42 m will be achieved.

2 Internal and yard sewerage

2.1 Construction of internal sewerage

The internal sewer network consists of outlet pipes, risers, ventilation exhaust pipes and outlets. When designing an internal sewer network, the following conditions must be taken into account:

The outlets are located, if possible, on one side of the building, and in residential buildings, as a rule, there is one outlet per section;

Outside the building, outlets are laid 0.3 m above the soil freezing line, the minimum laying depth is 1 m to the top of the pipe;

Devices for cleaning the network are installed on risers in the lower and upper floors (in buildings with a height of five floors or more, no less than three floors apart), at the beginning of sections of outlet pipes (according to the movement of liquid in the risers), when the number of connected devices is three or more, under which there are no cleaning devices, at network turns, when changing the direction of movement of wastewater, before discharges from the building;

The minimum diameter of the riser is 100mm;

The height of the exhaust part of the riser above the unused roof is 0.3...0.5 m;

The slopes of the main sections of the sewer system are directed towards the yard network. The distance from the well to the wall of the building must be at least 5 m.

2.2 Determination of wastewater flow rates

Hydraulic calculation consists of determining the diameters of risers, outlets, yard sewer pipes, as well as slopes in each section of the sewer water supply. In this case, it is necessary to determine the flow of wastewater on risers, outlets internal sewerage and in the yard sewer network.

We will divide the internal and yard sewerage into design sections. The first section is the pipeline from the wastewater receiver to the riser (second floor). The second section is the same on the first floor. The last section of the internal sewage system is from the riser to the basement wall.

The yard sewerage system is divided into sections: from the basement wall to the first sewer well, then - sections between the sewer wells and the section from the last yard sewerage well (difference) to the yard sewerage well.

When calculating the sewerage system, the following conditions must be observed:

The diameter of the pipeline of the subsequent section should not be less than the diameter of the previous one.

Similarly, the slope of the subsequent section should not be less than the slope of the previous section.

The diameter and slopes of the outlet pipelines are taken structurally. The diameter is determined by the diameter of the wastewater receiver outlet. The slope should be within 0.02...0.15. The diameter of the riser is determined by the total calculated flow rate of all floors (at the base of the riser), taking into account the diameters of the outlet pipelines and the angle of their connection (see Table 6.3).

The estimated flow rate for each section is determined by formula (2.1):

where is the flow rate from the device with maximum flow, l/s. Accepted according to table 6.4.

To determine , we determine the number of devices and the probability of their simultaneous operation using formula (2.2):

where hr,u is the rate of consumption of cold and hot water per peak hour

water consumption (see table 5.2).

The diameters of sewer pipelines (at outlets and in the yard network) should be determined according to Table 6.2. In this case, the fluid velocity V and the filling H/d are assigned so that the following condition is satisfied:

where V is the speed of the waste liquid, m/s;

H/d – pipeline filling;

K=0.5 – for pipelines made of plastic or glass pipes;

K=0.6 – for pipelines made of other materials.

Section 1-2:

 determined from table 5.3, knowing N 1 and P, N 1 =2,U=9.

We determine the estimated consumption:

The diameter of the outlet pipe in this section is assumed to be structurally equal to 75 mm, with a slope of 30·10 -3.

Section 3-4:

 determined from table 5.3, knowing N 2 and P, N 2 =3,U=8.

We determine the estimated consumption:

For this section, the pipe diameter is taken to be 75 mm, with a slope of 30·10 -3.

Section 5-6:

a is determined from Table 5.3, knowing N 3 and P, N 3 =7, U=8.

We determine the estimated consumption:

We add the flow rate from one toilet (toilet bowls on the first and second floors are connected to the riser separately with pipes with a diameter of 85 mm, not included in the calculation areas):

For this section, the pipe diameter will be 100 mm, with a slope of 30·10 -3.

In the following sections, the calculation is similar to the calculations in section 5-6.

The results of the hydraulic calculation are summarized in the following table 2.

The results of the hydraulic calculation of the yard sewerage system are summarized in Table 2.

Table 2. Results of hydraulic calculations of internal and yard sewerage

Plot number

Estimated consumption.

Speed

Filling, H/d.

Diameter d, mm

Section length l, m

Elevation, m

Tray depth

Booster pumping units

In cases where the guaranteed pressure in the external water supply network is lower than required, booster pumping units are installed. Typically, in these cases, centrifugal pumps directly connected to electric motors are used. If uninterrupted water supply is necessary, the installation of backup pumping units is designed.

The pumps are connected to the network after the water metering unit. Pumping units are placed in a dry and warm insulated room with a height of at least 2.2 m. It is not allowed to place utility supplies. pumping units under residential apartments, children's rooms, hospital premises, classrooms educational institutions and other similar premises.

Pumping units are installed on foundations that rise above the floor level by at least 20 cm, with reliable sound insulation, consisting of shock absorbers under the units, elastic linings and elastic pipes at least 1 m long (vibration inserts) on the suction and pressure pipelines. Fire pumps do not require sound insulation.

When installing pumps, it is advisable to provide a bypass line with a valve and check valve to bypass the pumps. Pump starting can be automatic, remote or manual. Fire pumps can be activated by trigger buttons located at fire hydrants or by jet relays.

A pressure gauge is installed on the pressure line of each pump, check valve and a valve or valve, and on the suction line - a gate valve. To absorb the forces arising in pressure pipelines from static and dynamic pressures, stops are installed at the places where the pipelines turn. Transition bridges are made through pipelines laid on the floor. In some cases, pipelines are laid in underground non-passable channels.

The pump is selected based on the missing pressure and estimated water flow. Pump pressure Hn is determined as the difference between the highest required pressure in the internal water supply Htr and the lowest (guaranteed) pressure in external network- Hgar:

Hn = Htr-Hgar.

The guaranteed pressure in the external network can be set from the axis mark of the input pipe at the point of its connection to the external network or from the ground mark at this place (the so-called guarantee pressure marks).

Required pressure for the network internal water supply is composed of the geometric height of the location of the dictating water tap above the guarantee pressure mark, the working pressure in front of the fittings of the dictating water tap, and the pressure necessary to overcome all resistance along the path of water movement from the external network to the dictating water tap.

It is recommended to select pumps using the Q - H characteristics given in the current pump catalogue. In this case, the operating point with coordinates Htr and qtr is determined at the intersection of the network characteristic with the Q - H curve of the pump.

When selecting a pump, you should strive to ensure that it supplies the calculated water flow to consumers at highest value Efficiency

If the pump operates in a water supply system without a water tank, then its flow must correspond to the maximum calculated second water flow q, l/s. In systems with a water pressure or hydropneumatic tank, the pump flow must correspond to the maximum calculated hourly water flow Q, m 3 / h. The operating mode of the pump is determined according to the integral or stepped daily schedule of water consumption, aiming to obtain the smallest control volume of the water tank.

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The pumps are connected to the network after the water metering unit. Pumping units are placed in a dry and warm insulated room with a height of at least 2.2 m. It is not allowed to place utility pumping units under residential apartments, children's rooms, hospital premises, classrooms of educational institutions and other similar premises.

A pressure gauge, a check valve and a valve or valve are installed on the pressure line of each pump, and a gate valve on the suction line. To absorb the forces arising in pressure pipelines from static and dynamic pressures, stops are installed at the places where the pipelines turn. Transition bridges are made through pipelines laid on the floor. In some cases, pipelines are laid in underground non-passable channels.

The pump is selected based on the missing pressure and estimated water flow. Pump pressure Hn is determined as the difference between the highest required pressure in the internal water supply system Htr and the lowest (guaranteed) pressure in the external network - Hgar:

Hn = Htr-Hgar.

The required pressure for the internal water supply network is composed of the geometric height of the location of the dictating water tap above the guarantee pressure mark, the working pressure in front of the fittings of the dictating water tap, and the pressure necessary to overcome all resistance along the path of water movement from the external network to the dictating water tap.

When selecting a pump, you should strive to ensure that it supplies the calculated water flow to consumers at the highest efficiency value.

Boost Settings

The internal water supply diagram shown in Fig. 6, applies if at the point of connection of the building free guarantee pressure in the outside water supply network, N g, exceeds required pressure, Ntr, necessary for supplying water to the highest-lying water distribution device located farthest from the input at any time of the day. As a rule, these conditions in urban areas are met for elevator-free buildings.

In the event that during the day the free guarantee pressure in the external water supply network periodically changes, and for one part of the day, for example, at night N g> N tr, and for another part of the day, for example during the day N g<N tr, then it is necessary to take additional measures to stabilize the pressure in the internal water supply and guarantee water supply to consumers. This can be done in different ways.

Water tank

The first method is to place it at the top of the building water tank, which is filled with water from the external water supply network during the day when N g> N tr, and when the pressure in the external water supply network decreases below the value N tr, water supply from the tank with the necessary pressure to the water fittings is ensured. The diagram of the internal water supply with a water tank is shown in Fig. 7 and has additional elements - water tank 8, float valve 9 and check valve 10.

Water enters the water tank through a float valve during the period of the day when N g> N tr. When the maximum permissible water level in the bar is reached, the float valve closes and the flow of water into the tank stops.

During the period of the day when N g<N tr, the water pressure created by the water tank exceeds the pressure in the external water supply network, so water from the tank flows through a check valve into the distribution line and then to consumers. To prevent reverse leakage of water from the internal water supply to the external network, a check valve 10 is installed between the water metering unit and the distribution main, allowing water to pass only in the direction from the water metering unit to the distribution main.

Rice. 7. Scheme of internal water supply with a water tank.

1 – input; 2 – water measuring unit; 3 – distribution line; 4 - riser; 5 – connection to the water fittings; 6 – water fittings; 7 – shut-off valves; 8 – water tank; 9 - float valve; 10 – check valve.

The advantages of stabilizing the pressure in the internal water supply using a water tank include simplicity and independence from electricity. The disadvantages are the need to place a tank of significant size and weight on the ceiling of the top floor, the need to monitor the condition of the tank and its periodic repairs, as well as possible deterioration in water quality and the appearance of leaks if the tank is not used correctly.

Pumping unit

The second way to provide the required pressure to consumers is to use booster (pump) installation, creating additional water pressure in the internal water supply. Boosting installations are used both when the required pressure in the internal water supply system periodically and constantly exceeds the value of the free pressure at the entrance to the building. The booster unit is located after the water metering unit and before the distribution main. The diagram of the internal water supply with a booster installation is shown in Fig. 8.

The internal water supply is a combined utility and drinking water supply - fire protection. To ensure uninterrupted water supply, it is equipped with two inlets 1 connected to different sections of the external water supply. A water meter unit 2 and a check valve 10 are installed at each inlet to prevent the reverse movement of water from the internal water supply to the external network. Both inputs are united by a common pipeline and connected to booster unit 3. A check valve 10 and valve 11 are installed on the bypass line of the booster unit.

Rice. 8. Diagram of the internal water supply of a residential building with a booster installation.

1 – input; 2 – water measuring unit; 3 – boost setting; 4 – distribution line; 5 – fire riser; 6 - fire hydrant; 7 – riser; 8 – tap at the entrance to the apartment; 9 – valve for disconnecting the riser; 10 – check valve;

11 – valve; 12 – watering tap; 13 – plug for draining water.

After the booster installation, the water enters the distribution line 4, which is designed in a ring pattern to increase the reliability of water supply. To ensure the possibility of disconnecting individual sections of the distribution main, valves 11 are installed on it. Fire risers 5, on which fire hydrants 6 are installed, and drinking water supply risers 7, having taps 8 on branches to the apartments, are connected to the distribution main. To turn off the risers, taps 9 are installed in their lower part. Watering of the area adjacent to the house is carried out using a watering tap 12. To drain water from the pipe supplying water to the watering tap, a plug 13 is installed.

The use of booster units makes it possible to provide the required water pressure to consumers at any number of floors in a building, however, the use of pumps leads to additional electricity consumption and the need to allocate space to accommodate pumps.

When placing booster units, it is necessary to take into account the requirements to prevent an increase in noise levels in buildings. Yes, pumping units prohibited place directly under residential apartments, children's or group rooms of kindergartens and nurseries, classrooms of secondary schools, hospital premises, workrooms of administrative buildings, classrooms of educational institutions. Pumping installations with fire-fighting pumps for internal fire extinguishing are located in the first and basement floors of buildings of I and II degrees of fire resistance made of fireproof materials. In this case, the premises of pumping units must be heated, fenced off with fire walls (partitions) and ceilings, and have a separate exit to the outside or to the staircase.

Modern pumping units are equipped with automatic control systems that provide: turning on and off pumps depending on the ratio of the required water pressure and its actual value at the entrance to the building; water supply through the bypass line of the pumping unit when it is turned off; shutting down the pumping unit if there is no water in the external water supply.

The minimum number of pumps in a pumping installation is two, of which one is a working pump and the other is a reserve pump. The pumping installation diagram for this case is shown in axonometry in Fig. 9.