CLASSIFICATION OF HEAT NETWORKS
According to the number of heat pipelines laid in parallel, heat networks can be single-pipe, two-pipe and multi-pipe. Single-pipe networks are the most economical and simple. In them, network water after heating and ventilation systems should be fully used for hot water supply. One-pipe heat networks are progressive in terms of a significant acceleration in the construction of heat networks. In three-pipe networks, two pipes are used as supply pipes for supplying coolant with different thermal potentials, and the third pipe is used as a common return, the so-called "return". In four-pipe networks, one pair of heat pipelines serves heating and ventilation systems, and the other pair serves the hot water supply system, and is also used for technological needs.
Currently, the most widespread are two-pipe heating networks, consisting of a supply and return heat pipeline for water networks and a steam pipeline with a condensate pipeline for steam networks. Due to the high storage capacity of water, which allows for distant heat supply, as well as greater efficiency and the possibility of central control of heat supply to consumers, water networks are more widely used than steam networks.
Water heating networks according to the method of preparing water for hot water supply are divided into closed and open. In closed networks for hot water supply, tap water is used, heated by network water in water heaters. In this case, the network water is returned to the CHPP or to the boiler room. In open networks, hot water is disassembled by consumers directly from the heating network and is not returned to the network after its use. The quality of water in an open heating network must meet the requirements of GOST 2874-82*.
Heating networks are divided into main, laid on the main directions of settlements, distribution - within the quarter, microdistrict and branches to individual buildings.
Radial networks are constructed with a gradual decrease in the diameters of heat pipes in the direction away from the heat source. Such networks are the most simple and economical in terms of initial costs. Their main drawback is the lack of redundancy. In order to avoid interruptions in heat supply (in the event of an accident on the main of the radial network, the heat supply to consumers connected in the emergency section is stopped) according to SNiP 2.04. heating networks of adjacent areas and joint operation of heat sources (if there are several). The range of water networks in many cities reaches a significant value (15-20 km).
With the device of jumpers, the heating network turns into a radial-ring network, there is a partial transition to ring networks. For enterprises in which a break in heat supply is not allowed, duplication or ring (with two-way heat supply) schemes of heat networks are provided. Despite the fact that the ringing of networks significantly increases their cost, nevertheless, on large heat supply systems, the reliability of heat supply is significantly increased, the possibility of redundancy is created, and the quality of civil defense is also improved.
Steam networks suit mainly two-pipe. Condensate is returned through a separate pipe - a condensate pipeline. Steam from the CHP through the steam pipeline at a speed of 40-60 m/s or more goes to the place of consumption.In cases where steam is used in heat exchangers, its condensate is collected in condensate tanks, from where it is returned by pumps through a condensate pipeline to the CHP.
The direction of the route of heat networks in cities and other settlements should be provided mainly for areas of the highest heat load, taking into account the type of laying, data on the composition of soils and the presence of groundwater.
Nominal passage of the fitting and shut-off valves for draining water from sectioned sections of water heating networks or condensate from condensate networks
|
Conditional |
Before |
80-125 |
150 |
200-250 |
300 |
500 |
600 |
800 |
1000-1400 |
|
Conditional |
25 |
40 |
50 |
80 |
100 |
150 |
200 |
250 |
300 |
Appendix
10*
Recommended
CONDITIONAL PASSIONS OF FITTINGS AND FITTINGS
FOR AIR EXHAUST IN HYDROPNEUMATIC
FLUSHING, DRAINING AND COMPRESSED
AIR*
Table 1
Nominal passage of the fitting and shut-off
air outlet fittings
|
Conditional |
25-80 |
100-150 |
200-300 |
350-400 |
500-700 |
800-1200 |
1400 |
|
Conditional |
15 |
20 |
25 |
32 |
40 |
50 |
65 |
table 2
Nominal passage of fitting and armature
for draining water and supplying compressed air
|
Conditional |
50- 80 |
100-150 |
200-250 |
300-400 |
500-600 |
700- 900 |
1000-1400 |
|
Conditional |
40 |
80 |
100 |
200 |
250 |
300 |
400 |
|
Same for |
25 |
40 |
40 |
50 |
80 |
80 |
100 |
|
Conditional |
50 |
80 |
150 |
200 |
300 |
400 |
500 |
APPENDIX 11
Recommended
CONDITIONAL PASSES OF FITTINGS AND SHUT-OFF
FITTINGS FOR START-UP AND CONTINUOUS
STEAM DRAINAGE
Table 1
Nominal passage of the fitting and shut-off
fittings for start-up drainage
steam pipelines
|
Conditional |
Before |
80-125 |
150 |
200-250 |
300-400 |
500-600 |
700-800 |
900-1000 |
1200 |
|
Conditional |
25 |
32 |
40 |
50 |
80 |
100 |
150 |
150 |
200 |
table 2
Nominal nozzle diameter for permanent
steam drainage
|
Conditional |
25-40 |
50-65 |
80 |
100-125 |
150 |
200-250 |
300-350 |
400 |
500-600 |
700-800 |
900-1200 |
|
Conditional |
20 |
32 |
40 |
50 |
80 |
100 |
150 |
200 |
250 |
300 |
350 |
|
Conditional |
15 |
25 |
32 |
32 |
40 |
50 |
80 |
80 |
100 |
150 |
150 |
Applications 12—19exclude.
APPENDIX 20
Reference
TYPES OF COATINGS FOR EXTERNAL PROTECTION
SURFACES OF PIPES OF HEAT NETWORKS FROM
CORROSION
|
Way |
Temperature |
Types of coatings |
Total thickness |
Regulatory |
|
1. Aboveground, |
Regardless |
Oil-bituminous |
0,15-0,2 |
OST 6-10-426-79 GOST 25129-82 |
|
outside |
300 |
Metallization |
0,25-0,3 |
GOST |
|
2. Underground |
300 |
Glass enamel |
TU VNIIST |
|
|
in impassable |
105T in three |
0,5-0,6 |
||
|
channels |
64/64 in three |
0,5-0,6 |
||
|
13-111 at three |
0,5-0,6 |
|||
|
596 into one |
0,5 |
|||
|
180 |
Organosilicate |
0,25-0,3 |
TU84-725-83 |
|
|
With |
0,45 |
|||
|
150 |
Isol at two |
5-6 |
GOST 10296-79 THAT |
|
|
Epoxy |
0,35-0,4 |
GOST 10277-90 TU6-10-1243-72 |
||
|
Metallization |
025-0,3 |
GOST 7871-75 |
||
|
3. Channelless |
300 180 150 |
Glass enamel - according to clause 2 of the application
Protective - according to clause 2 of the application, except |
||
|
Notes: 1. If the manufacturers
2. When using heat-insulating
3.Metallized aluminum |
APPENDIX 21
Recommended
Purpose
The main tasks of the TP are:
- - Converting the type of coolant
- — Control and regulation of coolant parameters
- — Distribution of heat carrier among heat consumption systems
- — Shutdown of heat consumption systems
- — Protection of heat consumption systems from an emergency increase in the parameters of the coolant
- - Accounting for the cost of coolant and heat.
The heating point is equipped with: heat exchangers, pumps (network, make-up), devices for recording the parameters of heat carriers. Heated water from the CHP under pressure enters the heat exchanger. On the other hand, cold water enters the heat exchanger through network pumps. Giving part of the energy to heat the network water, the water from the CHP is cooled and fed back. Heated network water of the required temperature is supplied for heating and hot water supply to the population.
Description
Heating mains are distinguished by:
- types of coolant
- steam
- water
- laying methods
- underground: without channels, in impassable channels, semi-through channels, through channels and in common collectors together with other engineering communications
- elevated: on low and high free-standing supports.
The total length of the heating pipeline due to heat losses is usually limited to 10-20 kilometers and does not exceed 40 kilometers. The limitation on the length is associated with an increase in the share of heat losses, the need to use improved thermal insulation, the need to use additional pumping stations and (or) stronger pipelines to ensure pressure drops at consumers, which leads to an increase in the cost of production and a decrease in the efficiency of the technical solution; Ultimately, this forces the consumer to use alternative heat supply schemes (local boilers, electric boilers, stoves). To improve maintainability with sectional fittings (for example, valves), the heating main is divided into sectioned sections. This allows you to reduce the emptying-filling time to 5-6 hours, even for pipelines of large diameter. Fixed (dead) supports are used to fix the mechanical, including reactive, movement of pipelines. Compensators are used to compensate for thermal deformation. Rotation angles can be used as compensators, including specially designed ones (U-shaped compensators). As compensators-elements, stuffing box, bellows, lens and other compensators are used. For the purposes of emptying and filling, heating pipelines are equipped with bypasses, drains, air vents and jumpers.
The boxes of the underground heating main are often blocked by walls in case of a coolant breakthrough.
One of the options for the heating system: deep heating network - a tunnel with a diameter of 2.5 meters. Examples of those under construction in Moscow: a deep heating network runs under Bolshaya Dmitrovka Street, a shaft behind the Pushkinsky cinema is at a depth of 26 meters. On the Taganskaya area, the depth of occurrence is less - 7 meters.
Similar tunnels of heating networks are laid by a mining shield.
Channelless laying
Channelless laying is the laying of pipelines directly in the ground. For channelless laying, pipes and fittings are used in special insulation - polyurethane foam (PPU) thermal insulation in a polyethylene sheath, foam polymer-mineral insulation (shellless).
Heat pipelines in industrial polyurethane foam insulation are equipped with an on-line remote monitoring system (SODK) of the state of insulation, which makes it possible to timely track the ingress of moisture into the heat-insulating layer using instruments.Pipelines in polyurethane foam and polyethylene sheath are used for channelless laying; in polyurethane foam and a steel twisted sheath are used in canals, technical undergrounds, on overpasses.
In the factory, not only steel pipes are thermally waterproofed, but also shaped products: bends, diameter transitions, fixed supports, valves.
GENERAL INFORMATION ABOUT HEAT SUPPLY
heat consumers. Thermal consumption is understood as the use of thermal energy for a variety of domestic and industrial purposes: heating, ventilation, air conditioning, hot water supply, technological processes.
According to the nature of their loading in time, heat consumers can be divided into seasonal and year-round. Seasonal consumers include heating, ventilation and air conditioning systems, and year-round consumers include hot water systems and technological apparatus. The thermal loads of consumers do not remain constant.
Heat costs for heating, ventilation and air conditioning depend mainly on climatic conditions: outdoor temperature, wind direction and speed, air humidity, etc. Of these factors, the outdoor temperature is of primary importance. Seasonal load has a relatively constant daily schedule and a variable annual schedule. Heating and ventilation are winter heat loads; air conditioning in summer requires artificial cold.
The load of hot water supply depends on the degree of improvement of residential and public buildings, the mode of operation of baths, laundries, etc. Technological heat consumption depends mainly on the nature of production, type of equipment, type of products.
Hot water supply and process load have a variable daily schedule, and their annual schedules depend to a certain extent on the season. Summer loads are usually lower than winter ones due to the higher temperature of tap water and processed raw materials, as well as due to lower heat losses from heat pipelines and process pipelines.
The maximum heat fluxes for heating, ventilation and hot water supply of residential, public and industrial buildings should be taken according to the relevant projects.
