Heat supply of the development quarter

Contents

CONTENTS

Introduction

Contents

1. Determination of estimated heat and water consumption for heating and WAN

2. Selecting a Route and How to Route Heat Networks

3. Hydraulic calculation of heat networks

4. To Create a Longitudinal Heat Network Profile

5. Calculation of temperature extensions and compensation zones

6. Calculation of compensating devices

7. Preparation of thermal network wiring diagram

8. Development of the UEC system

9. Calculation of heat networks from GPI pipes

10. Economic calculation and comparison of PI and GPI pipes

Conclusion

Literature

Introduction

District heating systems are characterized by a combination of three main links: heat sources, heat networks and local heat consumption (heat use) systems of individual buildings and structures.

Currently, the organization of heat networks is one of the most important tasks, the solution of which depends on the possibility of a comfortable life for heat consumers. The design of heat networks is a multi-stage process depending on many factors: from the choice of pipe material and type of coolant to the density of development and type of soil.

In this course project, we are tasked with designing and calculating the section of the heating main: from the connection point of the heating main to the introduction into multi-storey buildings .

The initial data for the project is: the location of the development quarter - the city of Lelchitsy; Development quarter plan with heatline connection point; buildings of the quarter: panel, built after 1995; type of heat network - water double-tube with temperature on supply pipeline Tg = 105OS and on reverse maintenance = 70OS; piping type: steel pipes pre-thermally insulated with polyurethane foam (PI-pipes) in a pipe shell made of low pressure polyethylene (LP), intended for underground channel-free laying of heat networks, steel 10; terrain is flat, elevation is 80.000, the base is sandy, deepening to the top of the pipe at the point of connection to the heat network is 2 meters.

2. selection of route and method of heat network laying

When designing the heat supply of new areas at the first stage, it is required to select the direction (route) of the heat networks from the heat source to the consumers. This is done according to the thermal map of the region, taking into account the materials of geodetic survey of the area, the plan of existing and planned above-ground and underground structures and communications, data on the characteristics of soils and the height of standing groundwater, etc.

When choosing a heat network route, the following basic conditions are taken into account: reliability of heat supply, quick elimination of possible malfunctions and accidents, safety of maintenance personnel, the smallest length of the heat network and the minimum amount of work on its construction. At the same time, the possibility of joint laying of heat pipelines with other engineering networks (water supply, gas pipeline, sewage, electric cables, etc.) is also taken into account, if this is allowed according to the conditions of reliability of all networks and safety of their maintenance .

It is desirable to connect the heating network to buildings and structures at an angle of 90 °; for metro lines, this angle can be reduced to 60 °, for the rest - to 45 °. The minimum permissible distances in the light horizontally and vertically from the outer face of building structures or the cladding of the channel-less laying of heating networks to buildings, structures, utilities and utility networks for various cases are indicated in [1] and for our system are 5 meters .

The slope of heat networks, regardless of the direction of movement of the coolant and the method of laying, should be at least 0.002 .

In this course design, the heat networks are laid in a channel-free manner, i.e. directly in the ground. This is the most cost-effective method.

The compensation gasket method was also used. The essence of the method is the use of natural compensation due to a change in the direction of pipelines forming sections of L, P, Z-shape.

The maximum deepening of the pipeline is assumed based on the condition of its structure strength. As a rule, it should not exceed 3 m.

At a distance of 30 cm, a warning (alarm) tape must be laid above the heating network pipeline.

In backfilling, foam polyethylene cushions are installed to allow free movement of pipes at their temperature elongation.

4. construction of longitudinal profile of heat network

A longitudinal profile of a thermal network is a schematic image of a section of a thermal network with a vertical plane passing through its axis.

The longitudinal profile shows the terrain of the ground surface along the axis of the heat network, the position of the brow line of the earth bed of the heat network relative to the ground surface, the ground cut along the axis of the network and the placement of artificial structures.

Due to the fact that the longitudinal profile is one of the main documents on the basis of which the construction of the thermal network is carried out, it is drawn up strictly in accordance with current requirements.

The ground surface line is drawn according to the elevations obtained as a result of instrumental surveys during surveys. This line characterizes the terrain along the road route.

The design line characterizes the longitudinal profile of the thresholds along the edge of the roadbed. It is drawn from the calculated design elevations. The difference between the design elevation and the ground surface elevation on one crosspiece is called the working elevation; it shows fill height or cut depth.

When the design line passes above the ground surface line, the earth bed is erected in embankments, working marks are signed above the design line. When it passes below the ground surface line, the earth web is arranged in a recess.

And in the course project, the design line and the ground surface line coincide and are at elevation 80.000

Next, the pipeline insulation top elevation and the trench bottom elevation are calculated. The insulation top elevation is calculated from the beginning of the design direction, taking into account the freezing depth and design slope. The elevation of the trench bottom is obtained by subtracting the elevation of the insulation top of the pipeline diameter and the sand cushion.

The profile also indicates the length and grade of the sections, their diameter and the cross section number.

There is also an expanded plan on which the angles of rotation of the calculated direction and shaped elements found on the path are indicated.

Specifies the base of the heat network profile.

The scale taken in the construction of the profile: vertical 1:100, horizontal 1:600.

Development of the Odk System

The on-line remote monitoring system is designed to systematically monitor the state of insulation of pipelines previously insulated with polyurethane foam and to quickly detect areas with high insulation humidity in the annular gap between the steel pipe and the hydraulic containment.

The on-line remote monitoring system allows:

perform timely periodic monitoring of pipeline insulation condition [periodic monitoring mode];

continuously monitor during pipeline operation [continuous monitoring mode].

The monitoring system allows to identify the following pipeline defects from PI-pipes and determine their location:

wetting of thermal insulation layer from SGP;

contact of signal wire with steel pipe;

breaking of signal conductors;

failure of connection cable insulation integrity.

The UEC system cannot indicate the reason for the wetting of the thermal insulation, i.e. determine whether it is a leak from the inside (the main steel pipe is damaged) or it is a leak from the outside (the pipe-shell is damaged).

Structure and composition of the operational remote control system: the signal circuit is formed by two copper wires located in the position "without 10 minutes 14 hours" and passing along the entire length of the heating line. Remote monitoring consists in monitoring the electrical parameters of this circuit.

Polyurethane foam used for heat insulation of steel pipe in absolutely dry state is dielectric and has infinitely high resistance [R]. When moisture appears in the annular gap between the steel pipe and the shell pipe, the insulation resistance from the polyurethane foam begins to fall.

Signal conductors

As the main (signal) wire, a copper wire is used, which is located in the pipeline on the right in the direction of coolant movement. It enters all branches of the heating line, and is the main one for determining the state of the pipeline, since it repeats its contour.

The transit wire-copper wire, which is located on the left in the direction of the coolant movement, passes along the shortest path between the start and end point of the pipeline, and mainly serves to form a signal loop.

The wires to be installed shall have no chips, incisions, cracks or other visible defects.

Connecting cables

Connecting cables provide connection of signal wires to switching terminals, as well as extension of cable leads.

In the course project, using a pulse-type system, we use three-core and five-core cables of the brand NYM3x1, 5 NYM5x1, 5 with standard color marking of strands.

Measuring terminal "IT-11"

Measuring terminal is designed for:

switching the conductors of the UEC system of pipelines with SGP insulation at control points;

connection to the UEC system of portable damage detectors and pulse reflectometers [locators].

The terminal is connected to the piping signal conductors via 3NYM 3x1.5 connecting 3wire cables.

The terminal has two cable inputs, two connectors for connecting a portable detector (to the supply and return pipelines). It is installed in design control points (CTP, ground carpets, etc., installation is prohibited in the heat chamber, since the terminal has external metal connectors].

IT-12 Intermediate Terminal

Intermediate terminal is designed for:

switching the conductors of the UEC system of pipelines with SGP insulation at intermediate points;

connection to the UEC system of pulse reflectometers [locators].

The terminal is connected to the signal conductors of the pipelines by means of connecting 5 wire cables NYM5xl, 5.

The terminal has two cable inputs and four copper wire jumpers located inside the terminal. It is installed in design control points (ground carpets, heat chambers, etc.).

Carpet Boxes

The carpet box is designed to accommodate switching terminals, provides protection of terminals from adverse environmental impact and is a means of protection against vandalism.

Damage detectors

Purpose: Damage detectors are designed to monitor the state of insulation of pipes with polyurethane foam insulation. Damage detectors allow you to determine the presence of moisture in the insulation of the pipeline and the integrity of the signal wires of the on-line remote control system itself.

Operating principle: the instrument operation is based on the comparison of the electrical insulation resistance measured between the steel pipe and copper wires installed at the plant in PPU insulation.

Basic Rules for SDS Design

Cable connection for intermediate and end test points to signal wires through sealed cable leads shall be provided;

The main signal wire must be located on the diagrams and on the route on the right in the direction of water supply to the consumer (on all pipes).

All tee branches must be included in the rupture of the main signal wire of the main pipeline, it is forbidden to connect the main tee branches to the transit wire located on the left in the direction of water supply to the consumer;

At the control points, end terminals are installed at the ends of the heating network, one of which must have an output to a stationary or portable detector.

When designing the heating line, it is necessary to provide for the arrangement of intermediate control points with the installation of intermediate terminals, the distance between which should not exceed 300 m (countdown from the beginning of the route).

For pipelines less than 100 m long, only one control point can be installed with the signal conductors looped under the metal insulation plug at the other end of the pipeline.

At the beginning of side branches longer than 30 m, an intermediate terminal is installed regardless of the location of other control points on the main pipeline.

The maximum length of the cable from the pipeline to the carpet box shall not exceed 10 meters. If a longer cable length is required, an intermediate terminal should be installed.

In the ground the cable should be run in galvanized pipe. Allowable cable types NYM Ex 1, 5 mm and NYM 5x 1, 5 mm;

Conclusion

In the course project "heat supply of the development quarter," a thermal network from PI pipes was designed. The necessary calculations were carried out.

route profile, wiring diagram, PI of pipes in the trench are built and heat networks are applied to the plot plan. They also determined the thermal loads of buildings and water flow rates in the heating network, chose the route and method of laying the pipeline, calculated temperature extensions and compensation zones of the heating network sections, made a hydraulic calculation of the thermal network, and developed the UEC system.

Designed a thermal network from GPIpipes. They brought an economic comparison. We found out that, in our case, ISOPROFLEX pipes cost 63.7% more than Pitrubs, excluding the cost of sealing joints.

The project used PI pipelines of the company "Module"

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