Heat supply of the quarter
- Added: 26.02.2017
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In course work, hydraulic and thermal calculations of the heat supply system from CTP to residential buildings were carried out.
1. General part
1. Basic Project Information
1.2 Selection of type of thermal network laying, building structures and equipment
2. Calculation part
2.1 Calculation of heat flow rates
2.1.1 Calculation of heating heat costs
2.1.2 Calculation of heat consumption for ventilation
2.1.3. Calculation of household heat
2.1.4. Calculation of heat consumption per HVAC
2.2. Hydraulic calculation of WAN system
2.2.1. Calculation of required pressures at the base of section units
2.2.2. Determination of flow rates and pressure losses in section units
2.2.3.Hydraulic calculation of the main main line of the supply pipeline in the water disassembly mode
2.2.4. Hydraulic calculation of side branches of supply pipeline
2.2.5. Calculation of circulation pipeline main line
2.2.6. Calculation of circulation pipeline side branches
2.3. Hydraulic calculation of heat networks
2.3.1. Hydraulic calculation of main line
2.3.2. Hydraulic calculation of lateral branches
2.4. Pressure Schedule
2.5. Check for boiling water
3. Labor Protection for Pipe Laying of Process Pipelines of Heat Trails
List of literature used
Thermal power is the most important branch of the national economy, which plays a huge role in creating the material and technical base for the development of the country.
An important component of district heating systems are heating networks designed for transportation and distribution of heat carrier. By connecting the heat source with a large number of consumers, the heat networks should ensure the coordinated operation of all links of the heat supply systems. Compliance with this requirement is achieved not only by rational design and construction of heat networks, but also by proper operation, maintenance of appropriate regimes, organization of control and preventive measures.
Heating networks are very expensive structures, and significant funds are spent on their construction and operation. Due to the increased requirements for cleanliness of the air basin of cities and towns, large thermal stations began to be built outside the city limits at a significant distance from the areas of thermal consumption. This necessitates the construction of long highways, which in turn requires increased capital expenditures. The uninterrupted and economical operation of district heating systems depends mainly on the quality of construction of heating networks and on how well their technical operation is carried out.
The main factor in reducing the cost of building heat networks is the use of new efficient structures and materials, progressive construction methods. The domestic practice of building heating networks and scientific developments of recent years have revealed a number of new highly efficient industrial structures of thermal pipelines and methods of their laying.
The purpose of the graduation qualification work: to design a heat pipeline from the Central Technical Center to residential multi-storey buildings.
In order to achieve this goal, a number of objectives have been set:
characterize the conditions and places of construction of the heat pipeline and heat consumers ;
determine the heat consumption, choose how to control the heat load;
Select the optimal direction of the network route
draw up a design diagram of the heating network ;
perform hydraulic calculation of the designed heating system ;
select compensators, supports, building structures.
1. Basic information about the project.
The construction area is the city of Bratsk. The buildings are located on a site with a calm relief, with a slight slope. This area is characterized by average natural-climatic conditions with outdoor temperature (the coldest five-day coverage is 0.92) 430C. Buildings are designed in a residential microdistrict, with an average level of groundwater standing and the presence of low-sedimentary soils.
The diploma project is based on the general plan of part of the city development quarter indicating the parameters of thermal energy consumers, the location of the thermal energy source (UT). In this microdistrict, underground laying of thermal pipelines and the WAN system is used. Underground gasket is used channel and channel-less. Heat networks and GVA system pass in impassable channels from standard reinforced concrete trays of series 3.006.1 - 2/82, issue 1-1. This project uses standard thermal chambers with typical dimensions. Heat networks according to the heat carrier type belong to water (mode 15070), according to the purpose of distribution, according to the number of pipelines to four-tube.
The number of sectional units of buildings is accepted by the number of sections of these buildings. According to SNiP 2.04.0786 "Thermal networks," the minimum permissible horizontal distances to above-ground and underground structures are determined. Compliance with these values is mandatory.
To divert flood or atmospheric waters, the overlap is installed with a transverse slope of about 1-2%. The external surface of the walls, floor and bottom of the channel is covered with waterproofing. Water entering the channels is removed by gravity through trays having a slope of at least 0.02 into special pits, from which it is pumped to the sewage system by the pump .
A channel-free gasket is also used in the sections. In order to protect pipelines from mechanical effects in this method of laying, reinforced thermal insulation is used - a shell.
To compensate for thermal extensions, U-shaped compensators are provided, and fixed supports are used to compensate for loads on pipelines. On pipelines there is a disconnecting valve located in the heating chambers, as well as a drain valve for water and air discharge). During underground laying, the slope of the branches is taken in the direction from the buildings to the chambers of the thermal network .
1.2 Selection of type of thermal network laying, building structures and equipment
The selection of the heat network route and the routing method should be taken according to the following data:
SNiP 11012003 "Instructions on the procedure for the development, approval and compliance of design documentation for the construction of buildings, enterprises and structures."
SNiP 2.04.0786 * "Heat Networks"
According to their purpose, the heat networks connecting the heat source with the heat point are divided into main, distribution and intra-quarter.
Main heat networks are sections that carry the main load and connect heat sources to large consumers.
Distribution heat networks transport heat from heat mains to objects of heat consumption.
Intra-quarter networks accordingly transport heat from distribution networks to heat points of heat consumers.
Water heat supply systems are used in two types: closed (closed) and open (open). In closed systems, the network water circulating in the heat network is used only as a coolant, but is not withdrawn from the network.
In open systems, network water is partially (rarely completely) disassembled for hot water supply.
Depending on the number of water pipelines used to heat this group of consumers, water systems are divided into one-, two-, three- and multi-tube. The minimum number of water pipes for an open system is one, and for a closed system is two.
For heat supply to cities, in most cases, double-tube water systems are used, in which the heat network consists of two pipelines: supply and return. Through the supply pipeline, hot water is supplied from the station to the subscribers, and through the return pipeline, cooled water returns to the station.
The predominant use of dual-tube systems in cities is due to the fact that these systems, compared to multi-tube systems, require less initial investments and are cheaper to operate. These systems are used when all consumers in the area require about one potential heat.
The issue of the type of laying (above-ground or underground) is decided taking into account local conditions and technical and economic indicators. In residential areas of any city, for architectural reasons, as a rule, underground laying of heating networks is used.
Modern heat lines shall meet the following basic requirements:
- high and stable in operating conditions heat and moisture resistance of the thermal insulation structure.
- Industriality and assembly. The possibility of manufacturing in factories and construction yards all the main parts, enlarged to the limits determined by the type and capacity of lifting vehicles. Assemble heat conductors on a route from finished parts.
- possibility of mechanization of all labor-intensive construction and installation processes.
The underground method of laying is divided into two types: channel and channel-free.
This type of underground piping is channel piping, it has a number of positive properties corresponding to the specific condition of hot piping operation. Channels are a construction structure that encloses heat conductors and thermal insulation from direct contact with soil, which has both mechanical and electrochemical effects on them.
2.4. Pressure chart.
Heat network pressure graphs are developed for the main line and characteristic branches.
On the coordinate grid in the selected scale, the earth surface profile is applied along the route (sweep) from the heat source (origin) to the most distant consumer. The zero elevation is taken as the level of CTP or the level of the ground surface at the initial point of the calculation scheme. Note that 1m = 0,001 MPa.
Coolant pressure lines are drawn in static and dynamic modes. The line shall not exceed 55 m (0.55MPa) above the ground so that the pressure in the lower floor instruments does not exceed the allowable working pressure of 0.6 MPa.
The minimum pressure at the starting point of the line (at the CTP) should be sufficient to overcome the hydraulic resistance in the return pipeline sections from the end point of the network to the circulation pump, maintain the necessary overpressure in the microdistrict buildings and provide cavitation reserve (for 3-9 storey buildings this pressure is within 0.16 - 0.30 MPa).
From the tallest building No. 5, I set aside the value of 50 kPa and receive the SS line. " From line SS "I put down the pressure loss on the main line - I get point A." From point A, "B," C. " D. "I connect these points. From point B "I lay down the pressure loss at point 6 and along line SS" I draw a segment to point 6 - I get point E "I find all other points in the same way. Points D "; E "; F"; G "are located on the line SS," I connect them to the corresponding intermediate points and obtain sections B'E "; C "-F"; C’G’; E’-G’. Sections DD "; E-E’; FF’; G-G "is the pressure loss in the ITP and they are 150 kPa. The pressure loss line in the feed line is constructed as a mirror reflection of the pressure loss line in the return line .
Piezometric graph (Appendix 1).
2.5. Check for boiling water.
When using water with a temperature above 1000C for heat supply needs, it is possible to boil it in the pipelines of the heating networks and in the heating system of the building if the pressure drops below the saturation pressure Pnas.
To determine the possible boiling of water in the pressure graph, we build a boiling line.
At 1050C for residential buildings Rnas = 20.9kPa.
The boil-in line is graphically transferred down the pressure loss line in the supply pipeline by the value of excessive saturation pressure Pnas. Boiling water can occur in residential building No. 5 at an elevation of 155.28 m. (see Annex)
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