Project of gas supply of the settlement

Contents

Introduction

1 Calculation of gaseous fuel characteristics

2 Population definition

3 Calculation of gas demand

3.1 Determination of annual heat consumption

3.1.1 Determination of annual heat consumption for gas consumption in apartments

3.1.2 Determination of annual heat consumption during gas consumption at consumer service enterprises

3.1.3 Determination of annual heat consumption during gas consumption at bakeries and bakeries

3.1.4 Determination of annual heat consumption for heating, ventilation, hot water supply of residential and public buildings

3.1.5 Drawing up the final table of gas consumption by the city

3.2 Determination of annual and hourly gas consumption by different consumers

3.3 Planning of annual gas consumption by the city

4 Selection and justification of gas supply system

4.1 Determination of the optimal number of GRP

4.2 Typical diagrams of GRP and GRU

4.3 Selection of gas control stations and units equipment

4.3.1 Selection of pressure regulator

4.3.2 Selection of safety valve

4.3.3 Safety relief valve selection

4.3.4 Filter selection

4.3.5 Selection of shutoff valves

4.4 Structural elements of gas pipelines

4.4.1 Of the Pipe

4.4.2 Gas Pipeline Details

5 Hydraulic calculation of gas pipelines

5.1 Hydraulic calculation of high and medium pressure ring networks

5.1.1 Calculation in emergency modes

5.1.2 Calculation of branches

5.1.3 Calculation at normal flow distribution

5.2 Hydraulic calculation of low pressure dead end gas pipelines

5.3 Hydraulic calculation of internal gas pipeline

Conclusion

List of literature

Introduction

The goal of the course project is to consolidate theoretical material on the main issues of the Gas Supply course, to acquire skills in independent work in the field of gas supply systems design and experience with reference and special literature.

In the design, it is necessary to develop a two-stage gas distribution system with the first stage by high pressure gas pipelines, and the second - by low pressure. From the high-pressure network, design the supply of gas to concentrated consumers: gas control points (GRP), boiler room, bakery, bath and laundry. Gas supply to household and communal consumers is designed from the low-pressure network.

Modern city distribution systems are a complex complex of structures, consisting of the following main elements: gas networks of low, medium and high pressure, gas distribution stations, gas distribution points and installations. In the above stations and installations, the gas pressure is reduced to the required value and automatically kept constant. They have automatic safety devices that exclude the possibility of increasing gas pressure in networks above normal.

The gas supply system shall ensure uninterrupted gas supply to consumers, be safe in operation, simple and convenient to maintain, shall provide for the possibility of disconnecting its individual elements or sections of gas pipelines for emergency or repair work.

4 Selection and justification of gas supply system

Gas supply systems are a complex complex of structures. The choice of the gas supply system of the city is influenced by a number of factors. This is primarily: the size of the gasified territory, the features of its layout, population density, the number and nature of gas consumers, the presence of natural and artificial obstacles to the laying of gas pipelines (rivers, dams, ravines, railways, underground structures, etc.). When designing a gas supply system, a number of options are developed and their technical and economic comparison is made. For construction, the best option is used. Depending on the maximum gas pressure, city gas pipelines are divided into the following groups:

* high pressure category 1 with pressure from 0.6 to 1.2 MPa;

* medium pressure from 5 kPa to 0.3 MPa;

* low pressure up to 5 kPa;

High and medium pressure gas pipelines serve to supply medium and low pressure urban distribution networks. They are the bulk of the gas to all consumers of the city. These gas pipelines are the main arteries supplying the city with gas. They are made in the form of rings, the floor of rings or rays. Gas is supplied to high and medium pressure gas pipelines from gas distribution stations.

Modern systems of urban gas networks have a hierarchical construction system, which is associated with the above classification of gas pipelines by pressure. The upper level consists of high-pressure gas pipelines of the first and second categories, and lower low-pressure gas pipelines. The gas pressure during the transition from a high level to a lower level gradually decreases. This is done using pressure regulators installed on the FRG. According to the number of pressure stages used in urban gas networks, they are divided into :

* two-stage, consisting of high or medium pressure and low pressure networks;

* three-stage, including high, medium and low pressure gas pipelines;

* multi-stage, in which gas is supplied through gas pipelines of high (1 and 2 categories) pressure, medium and low pressure.

The choice of the gas supply system in the city depends on the nature of gas consumers who need gas of the appropriate pressure, as well as on the length and load of gas pipelines. The more diverse gas consumers and the greater the length and load of gas pipelines, the more difficult the gas supply system will be.

In most cases, for cities with a population of up to 500 thousand people, the most economically feasible is a two-stage system. For large cities with a population of more than 1,000,000 people and the presence of large industrial enterprises, a three-stage or multi-stage system is preferable.

Gas pipeline routes are designed based on the minimum length of the network. At the same time, high-pressure gas pipelines are trying to lay along the outskirts of the city, where there is a small population density and a smaller number of underground structures.

Low-pressure networks consist of street distribution gas pipelines, subscriber branches supplying gas to the building and internal gas pipelines that distribute gas between individual devices inside the building. The density of distribution gas pipelines is accepted so that the length of subscriber branches before entering the buildings is 50 100 m. Residential and public buildings, utility consumers, as well as small enterprises are connected directly to distribution gas pipelines.

To increase reliability of gas supply, the networks ring. In low-pressure networks, it is advisable to ring only distribution gas pipelines, and make secondary (subscriber branches) dead end branched.

When routing low pressure networks, it is necessary to determine the main passage of the area on the general plan. Then, considering that there are no gas pipelines along the main passages, along the neighboring parallel passages (through one), outline the routes of the gas pipelines. Similarly, map the routes in the direction perpendicular to the main passage. After analysis, excess gas pipeline routes are removed .

The number of gas control points (GRP) is determined by technical and economic calculation. EMG is located in the centers of the zones that they feed. The range of one GRP shall not be covered by the range of another GRP. The meeting points of gas flows in the system with several GRP are assigned at the boundary of the zones of neighboring GRP.

In this design, the network of high-pressure gas pipelines is made dead end, the distribution network of low-pressure gas pipelines is ring.

4.2 Typical diagrams of GRP and GRU

Gas control points (GRP) are located in separate buildings made of brick or reinforced concrete blocks. The location of GRP in settlements is regulated by the SNiP. At industrial enterprises, GRP are located at the places of gas pipeline inputs to their territory.

The FRG building has 4 separate rooms:

* Main room where all gas control equipment is located;

* room for instrumentation;

* room for heating equipment with gas boiler;

* room for inlet and outlet gas pipeline and manual control of gas pressure.

In the typical GRP, the following nodes can be distinguished:

* Gas I/O unit with bypass for manual control of gas pressure downstream of FRG;

* mechanical gas purification unit with filter;

* gas pressure control unit with regulator and safety valve;

* gas flow measurement unit with diaphragm or gas counter.

In the room for instrumentation there are self-recording pressure gauges measuring the gas pressure before and after the FRG, a gas flowmeter, a differential pressure gauge measuring the pressure drop on the filter. In the main room of FRG there installed are indicating pressure gauges measuring gas pressure before and after FRG; expansion thermometers measuring the gas temperature at the gas input to the FRG and after the gas flow measurement unit.

In the FRG room it is necessary to maintain a positive air temperature of not less than 10 ° С. To do this, the FRG is equipped with a local heating system or connected to the heating system of one of the nearest buildings .

A deflector is installed in the FRG room to provide three-fold air exchange in the FRG main room.

The front door to the main room of the FRG in its lower part must have slots for air passage.

GRP lighting is most often performed externally by installation

directional light sources on GRP windows. You can perform lighting

FRG in explosion-proof design. In any case, turn on the lighting

FRG shall be performed from outside.

Lightning protection and grounding circuit are equipped near the FRG building.

Gas control units

Gas control units (GRU) in terms of their tasks and principle of operation do not differ from GRP. Their main difference from GRP is that GRU can be placed directly in those rooms where gas is used, or somewhere nearby, providing free access to GRU. Separate buildings for GRU are not built. The GRU is covered with a barrier net and warning posters are posted near it. GRU, as a rule, are built in production shops, in boiler houses, at utility gas consumers. GRU can be made in metal cabinets, which are fixed on the external walls of production buildings. GRU placement rules are regulated by SNiP.

To the room where the GRU is located, from the point of view of ventilation and

Lighting requirements are the same as for GRP.

4.3 Selection of gas control stations and units equipment

The selection of FRG and GRU equipment begins with the determination of the type of gas pressure regulator. After selecting the pressure regulator, the types of safety shut-off and safety relief valves are determined. Next, a filter for gas cleaning is selected, and then shut-off valves and control and measuring instruments.

4.3.5 Selection of shutoff valves

Shutoff valves (latches, gates, pith cranes), are applied in GRP and GRU it has to be calculated on the gas environment. The main criteria for the selection of shutoff valves are the conventional diameter DY and the actuating pressure of the switchgear.

Gate valves are used with both retractable and non-retractable spindle. The former are preferable for an above-ground installation, the latter for an underground installation.

Valves are used in cases where increased pressure loss can be neglected, for example, on pulse lines.

Plug valves have significantly less hydraulic resistance than valves. They are distinguished by tightening of the conical plug on tension and gland, and by the method of connection to pipes - on coupling and flange.

The material for the manufacture of shutoff valves is: carbon steel, alloyed steel, gray and ductile cast iron, brass and bronze.

Shut-off valves made of gray cast iron are used at operating gas pressure of not more than 0.6 MPa. Steel, brass and bronze at a pressure of up to 1.6 MPa. Operating temperature for cast iron and bronze reinforcement shall not be lower than - 35 С, for steel at least - 40 С.

Steel fittings or ductile iron fittings shall be used at the gas inlet to the FRG. At the outlet of the GRP at low pressure, gray cast iron reinforcement can be used. It's cheaper than steel.

The nominal diameter of the gate valves in the FRG shall correspond to the diameter of the gas pipelines at the gas inlet and outlet. It is recommended to select the nominal diameter of valves and cranes on impulse lines of FRG or FRG equal to 20 mm or 15 mm.

4.4 Structural elements of gas pipelines

The following structural elements are used in gas pipelines: pipes; shut-off control valves; lens compensators; condensate collectors; cases; wells; supports and brackets for external gas pipelines; systems for protection of underground gas pipelines against corrosion; control points for measuring the potential of gas pipelines relative to the soil and determining gas leaks.

The pipes form the main part of the gas pipelines, along which gas is transported to consumers. All pipe connections in gas pipelines are welded only. Flange connections are allowed only in places of installation of shutoff valves.

4.4.1 Pipes

For the construction of gas supply systems, steel straight-joint, spiral-flow welded and seamless pipes made of well-welded steels containing no more than 0.25% carbon, 0.056% sulfur and 0.046% phosphorus should be used. For gas pipelines, for example, common-quality carbon steel, calm, groups B of GOST 1463789 and GOST 1652389 are not lower than the second category of St grades. 2, St. 3, as well as St. 4 with carbon content of not more than 0.25%.

A - rationing (guarantee) of mechanical properties;

B - rationing (warranty) of chemical composition;

C - rationing (warranty) of chemical composition and mechanical properties;

D - rationing (warranty) of chemical composition and mechanical properties on heat-treated samples;

E - without regulated chemical composition and mechanical properties.

It is recommended to use pipes of the following delivery groups:

- at design outside air temperature up to - 40 ° С - group B;

- at a temperature of - 40 ° C and below - groups B and G.

When selecting pipes for the construction of gas pipelines, as a rule, pipes made of cheaper carbon steel according to GOST 38088 or GOST 105088 should be used.