Hot water supply of a 9-storey residential building

Contents

Contents

THEORISTIC PART

1. Calculation of hot water supply systems selection. Structural elements of the system

2. Determination of estimated hot water and heat flow rates

3.Hydraulic calculation of hot water supply pipelines

4. Determination of heat losses by supply pipelines

Determination of water temperature at the node points of the WAN system

5. Determination of water circulation rates

6. Correction of hydraulic calculation of supply pipelines

7. Hydraulic calculation of hot water system circulation

8. Selection of heat station equipment

8.1 Determination of the scheme of heaters connection to the heat network

8.2 Thermal and hydraulic calculation of hot water system water heating plant

8.3 Selection of water flow meter

8.4. Determination of the required head at the input to the building

8.5. Selection of circulation and booster-circulation pumps

9. List of literature used

DESIGN PART

10. Determination of estimated hot water and heat flow rates

11. Hydraulic calculation of hot water supply pipelines

12. Determination of heat losses by supply pipelines

13. Determination of water circulation rates

14. Correction of hydraulic calculation of supply pipelines

15. Hydraulic calculation of hot water system circulation

16. Select equipment of individual heat station

16.1. Definition of heating heaters connection to thermal

networks

16.2. Thermal and hydraulic calculation of hot water system water heating plant

16.3 Selection of water flow meter

16.4 Determination of the required head at the entry into the building

16.5. Selection of circulating and boosting circulating

pumps

17. List of literature used

1. Calculation of hot water supply systems selection.

Structural elements of the system

In course work, it is necessary to justify the choice of the scheme of the in-house hot water supply system based on the structural features of the building, the planning solutions of the kitchen rooms, the bathroom and the bathroom, their mutual location.

We accept the hot water supply system in accordance with the recommendation of the methodological instruction with the lower routing of the highways. When selecting the riser connection scheme, we proceed from the SNiP recommendation (item 5.7).

In order to ensure constant temperature of hot water from water-collecting cranes of multi-storey residential buildings, a circulation system of WCS is designed.

GVA risers are mounted to the right relative to cold water supply risers. Circulation riser is laid to the right of hot riser. Distance between riser axes is 80 mm.

Horizontal piping from risers to instruments is carried out at the floor: cold water pipeline 100 mm above the clean floor, and hot water - 200 mm.

Vertical connections to instruments: hot - on the right, cold - on the left.

Depending on the layout, the following water collection valves are installed in the apartments: in the bathroom - a combined mixer with a rotary pour for the bath and for the washbasin; in the kitchen - a mixer for washing. Towels are provided in the bathrooms.

In order to remove air and drain water from the system, pipelines are laid with a slope of 0.002, while the circulation pipeline is located parallel to the supply. Air is removed from the lower flow system through water discharge valves or air faucets at the top of the supply risers. Drain branch pipes with shut-off valves are provided for lowering water from the system in its lower points.

Installation of shut-off valves in hot water supply systems is provided: on cold and hot water pipelines near water heaters; at the base of supply and circulation risers in buildings 3 floors or more high: on branches from risers to each apartment; at the entrances to the building.

GVA system pipelines are designed from steel galvanized water and gas pipes according to GOST 326275 * with a diameter of 15 to 125 mm, and at diameters of more than 125 mm - it is allowed to use non-galvanized steel electric welded pipes according to GOST 1070476 *.

Check valves are installed at water heaters on circulation pipeline and cold water supply pipeline.

Hot water parameters are monitored by thermometers and pressure gauges. Pressure gauges are installed at the outlet of water heaters, before and after the circulation pump. Thermometers are placed before and after the water heaters and on the circulation pipeline before the pump.

To account for water flow, water flow meters are used, which are installed in closed heat supply systems on the cold water pipeline before the heater, and open ones - on the hot water pipeline after the mixer.

6. Correction of hydraulic calculation of supply pipelines

Having determined the qcir water circulation flow rates on separate sections of the hot water supply system, we specify the calculated values of hot water flow rates on the sections of supply pipelines of the internal house system to the first water separation riser (in the direction of water movement) according to formula (5). Then, based on qh cir, we specify specific pressure losses and water velocity in sections V. If the water velocity exceeds the permissible value, then increase the diameter of the section.

Since the calculated hot water flow rate for the sections of the internal house network, starting from the first water separation riser (in the direction of water movement) to the most remote water separation device, is determined without taking into account the circulation flow rate, i.e. qh cir = qh, the hydraulic calculation of these sections is not corrected.

The results of the final hydraulic calculation of the hot water supply pipelines are summarized in Table 4.

Therefore, no hydraulic calculation adjustment is required.

7. Hydraulic calculation of hot water system circulation

Hydraulic calculation of circulation rings is carried out for the circulation mode, i.e. at the highest circulation flow rate. Each circulation ring (through each water discharge riser) consists of supply pipelines, the diameters of which are selected in the maximum water discharge mode, and circulation pipelines.

Hydraulic calculation of circulation rings for the network circulation mode is carried out in two stages:

1. Calculation of pressure losses in supply pipelines provided that there is no water discharge and only water circulation flow is passed;

2. Calculation of pressure losses in circulation pipelines at water circulation flow rate.

At the second stage, diameters of circulation pipelines, pressure losses in them and in circulation rings are determined.

The calculation is similar to the calculation of supply pipelines. Pressure losses at design areas are calculated by formula (6) using hydraulic calculation tables [5, Annex 1]. The diameters of the prefabricated circulation pipeline and the outermost riser are assumed based on the allowable water speeds [8, p. 104]. Diameters of circulation pipelines are 1-2 gauge smaller than diameters of corresponding sections of supply pipelines.

Circulation risers are designed for pressure difference at the points of their connection with supply risers and circulation main. Difference of pressure losses in different circulation rings is not more than 10%. If it is impossible to link the pressure losses by changing the diameters of the pipelines in the sections of the circulation line, we provide for the installation of diaphragms at the base of the circulation risers. The diameter of the diaphragm holes dd is determined from the expression:

(13)

where q - water flow through the diaphragm, m 3/h;

Ner - excess head, m which must be extinguished by diaphragm:

d -Pipe diameter.

If in the calculation the diameter of the aperture of the diaphragm is less than 10 mm, then we allow you to install a valve instead to redeem the excess head. However, when installing the diaphragms, there is an increase in blocking and scale formation in these places, so it is allowed to link pressure losses in the circulation rings by increasing the hydraulic resistance of the risers, introducing smaller diameters into their lower part of the pipe insert.

8. Selection of heat station equipment

Heat stations are designed for heat carrier preparation and distribution with required parameters (pressure, temperature, flow rate) between local systems. They are equipped with instrumentation - pressure gauges, thermometers, flowmeters; automatic devices for control of heat release and maintenance of preset thermal and hydraulic modes in subscriber units; water heaters; circulation and booster pumps.

ITR equipment depends on the type of heat supply system, connection schemes of heat consuming plants, pressure in the supply and return lines of the heat network, as well as heat consumption modes.

Hot water heaters are connected to heat networks in ITR in parallel or two-stage schemes depending on the Qhmax/Qomax ratio. With independent schemes for connecting heating systems to heat networks, water-water heaters of heating plants are installed in thermal points.

Calculation of water heating units diagrams shall be performed for the most unfavorable mode corresponding to the ambient air temperature at the fracture point of the central quality control graph, or according to the minimum temperature of the network water, if there is no fracture in the temperature diagram.

To ensure water circulation in hot water supply and heating systems, circulation pumps of K, KM, TsNSH, TSC type are installed in ITP.

Elevators or mixing pumps are used to reduce the temperature of the network water coming from the heat network to the local heating system. Elevators are used in heating systems with design pressure losses of up to 15 kPa and are installed in individual heat points.

Meters are installed in heat stations to account for water consumption for hot water supply.

To clean water from suspended particles in heat supply systems, mud makers are used, which are installed in heat points on supply and return heat lines. Their dimensions depend on the diameters of the supply heat conductors [9, Table 2.13... 2.16].

To maintain the specified parameters of the heat carrier, the thermal points of the water heat supply systems are equipped with electronic or hydraulic automatic controllers. Hydraulic direct and indirect controls are most common. Constant flow of network water at subscribers, as well as maintenance of pressure in supply and return heat lines within specified limits, are provided by regulators: RP pressure drop (flow rate), RD pressure and universal RDDS.

To maintain design temperature of hot water in closed heat supply systems after hot water heaters, RP regulators are installed together with bimetallic thermostat of TRB as temperature sensor.

The automation schemes of thermal points depend on the hydraulic and thermal modes of the thermal network [9, p. 136... 155], [7, p. 79... 88], [8, p. 149... 156 ].

In course work, we also perform thermal and hydraulic calculation of a water-water heater, select circulation pumps and a water flow meter for hot water supply.

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