Kursovoy - Gas supply of the city of Muravlenko

Contents

Contents

CONTENTS

1. CONTENT OF THE COURSE PROJECT

1.1. SOURCE DATA SELECTION

2. CITY GAS SUPPLY DESIGN

2.1. CALCULATION OF GAS CONSUMPTION

2.1.1. POPULATION DEFINITION

2.1.2.SPECIFICATION OF GAS PARAMETERS

2.1.3. DETERMINATION OF GAS FLOW RATE FOR UTILITY NEEDS

2.1.3.1. DETERMINATION OF ANNUAL GAS CONSUMPTION FOR UTILITY NEEDS

2.3.2. HOURLY GAS FLOW RATE FOR UTILITIES

2.1.4. DETERMINATION OF GAS FLOW RATE FOR HEAT SUPPLY

2.1.4.1. HOURLY CONSUMPTION FOR HEATING

2.1.4.2. ANNUAL GAS CONSUMPTION FOR HEATING

2.1.5. DETERMINATION OF ANNUAL GAS CONSUMPTION FOR INDUSTRIAL ENTERPRISES

2.1.5.1. ANNUAL GAS FLOW RATE

2.1.5.2. HOURLY GAS FLOW RATE

2.2.1. DESIGN GAS FLOW RATE

2.3. GAS SUPPLY SYSTEM

2.3.1. SELECTION AND JUSTIFICATION OF GAS SUPPLY SYSTEM

I2.3.1.1. DETERMINATION OF THE NUMBER OF GCPS

2.3.1.2. DETERMINATION OF THE NUMBER OF PRESSURE STAGES IN GAS DISTRIBUTION PIPELINES

II.3.1.3. SELECTION OF GAS NETWORK STRUCTURAL DIAGRAM

2.3.1.4. CHOICE OF CONNECTION OF CONCENTRATED CONSUMERS TO GAS NETWORKS

2.3.2. DETERMINING THE OPTIMAL NUMBER OF NETWORK GRPS

2.3.3. HYDRAULIC OPERATION MODES OF GAS PIPELINES

2.4. HYDRAULIC CALCULATION OF HIGH-PRESSURE ANNULAR GAS NETWORKS

2.3.6. HYDRAULIC CALCULATION OF LOW PRESSURE ANNULAR GAS NETWORKS

CALCULATION OF DEAD END BRANCHES

Literature

1. Content of the course project

The course project consists of an explanatory note and a project of the gas distribution system of the city, where the following are completed:

calculations of the city's annual gas consumption;

hourly estimated expenses;

characteristics of combustible gas;

design of high (medium) and low pressure gas pipelines distribution system;

hydraulic calculation of high pressure gas pipelines of category II and low pressure.

The graphic part is 3 sheets of the A-3 format of the drawings, which reflect the general plan of the settlement with the application of a high (medium) pressure distribution network and design diagrams of gas pipelines.

Calculations were performed on PC in Excel.

1.1. Select Source Data

Gas supply source and chemical composition of gas accepted

Geographically, the city is divided into two administrative districts with different storeys of development. In district I there are 4-5-story buildings, in district II the building is represented by low-rise (1-2 floors) buildings.

District I is fully landscaped. Only gas stoves for cooking are installed in the kitchens of apartments. The heat supply of the districts is central from the CHP and the district heating boiler house .

In district II, represented by low-rise buildings, there is water supply and sewerage. Heat supply of public buildings is provided by the central, and individual housing stock - from local heat sources. Gas plates and flow water heaters are installed in the apartments.

The population of the city uses all types of communal services, there are baths, laundry, educational, children's and medical institutions. Coverage of the population with public services is adopted according to [11, Table 2]. We accept 100% coverage of all municipal services to the population with gas supply.

The main characteristics of industrial enterprises are adopted as per [11, Table 1].

Design of gas supply of the city

2.1. Calculation of gas consumption

When developing a gas supply project for a city or a settlement, annual and hourly gas consumption is determined according to the norms at the end of the calculation period, taking into account the prospects for the development of gas consumers. The estimated period is determined by the plan for the prospective development of the city and is 2025 years.

Gas consumption is determined separately for each category of consumers: for communal and sanitary needs of the population, for heating, ventilation and hot water supply of residential and public buildings, for the needs of industrial enterprises. Gas consumption in the city or in a settlement depends on the number of people, the degree of improvement of the settlement, the number and capacity of industrial enterprises, climatic conditions.

2.1.1. Population definition

Gas consumption for utility and heating needs of a city or a settlement depends on the number of inhabitants, it can be determined

2.1.3. Determination of gas consumption for utility needs

Gas consumption for utility needs is 1015% of the total gas consumption in the city. Utility consumers include apartments of residential buildings, medical institutions, consumer services enterprises, bakery enterprises. The exact calculation of the gas flow rate is complicated, so the gas consumption is determined by the averaged norms obtained from the statistical data.

2.1.3.1. Determination of annual gas consumption for utility needs

The annual gas consumption for communal needs of the population is determined depending on the number of consumers, the average rate of annual gas consumption, taking into account the coverage by the gas supply of municipal needs of the population and the coverage of the population with appropriate services, standards for the provision of services.

2.1.4. Determination of gas consumption for heat supply needs

Gas consumption for heat supply needs depends on ambient air temperature, quantity and type of heated buildings and is determined by thermal loads calculated according to the procedure given in [1].

2.1.4.1. Hourly consumption for heat supply needs

When developing gas supply projects for cities in the absence of specific thermal characteristics of the development, it is allowed to determine the estimated annual gas consumption according to the enlarged indicators.

2.2.1. Design gas flow rate

The difference between the maximum hourly gas flow rate determined according to the combined daily gas consumption schedule and the sum of the maximum hourly gas flow rate for certain categories of consumers for most cities is 24%.

Since the error of 5% in engineering calculations is considered sufficient, in practice, the maximum hourly flow rate of gas by individual consumers is taken as the calculated one. This leads to a slight increase in the cost of the gas supply system, but increases its reliability due to the greater throughput of high-pressure networks. Design gas flow rate

2.3. Gas supply system

2.3.1. Selection and justification of gas supply system

When selecting gas supply systems, the recommendations [3], [6] are preliminary studied, attention is paid to the following questions:

Determination of the optimal number of high (medium) and low pressure power supply sources; structure of gas networks (dead end, ring, mixed); determination of maximum pressures in distribution gas pipelines and number of pressure stages in the system.

The main criteria for evaluating gas supply systems are: economy, reliability, processability, cross-country ability of networks, explosion safety, ease of operation. Theoretical studies and practice have shown that the technical and economic indicators of gas supply systems depend on the number of served population and the capacity of industrial enterprises.

I2.3.1.1. Determination of the number of GVs

One of the important issues when developing a fundamental scheme for gas supply to the city is the rational placement of distribution stations (GRS) and the determination of their optimal amount. With an increase in the number of GRS, the loads and radius of action of city highways decrease, which leads to a decrease in their sections. Accordingly, metal consumption and investment in high (medium) pressure urban networks are reduced. More GRS provides greater reliability of gas supply systems. At the same time, it should be borne in mind that with an increase in the number of GCF, the costs of their construction and construction increase, and the operating costs are increased due to the maintenance personnel on GCF. For cities with a population of up to 200 thousand people. the most rational are systems with one GRS .

The gas at the GPC is cleaned, odorized, reduced to the upper stage pressure in the city networks and supplied to the distribution gas pipelines.

To power city gas pipelines, we receive one GRS located outside the city limits.

2.3.1.2. Determination of the number of pressure stages in gas distribution lines

For small and medium-sized cities with a number of inhabitants, respectively, up to 100 and 500 thousand people. two-stage gas supply systems are used as the most economical, consisting of low and high gas pipelines (up to 0.6 MPa) or low and medium pressures. Medium pressure is used only if it is impossible to lay high pressure gas pipelines. Such a case may arise with the gas supply of old cities with dense buildings or with the reconstruction of the gas supply system. If the development of the city is heterogeneous and characterized by different densities, three-stage gas supply systems are used with the laying of low and medium pressure gas pipelines in areas where high pressure networks cannot be laid (usually the central part of old cities and low-rise buildings) and high pressure in areas of new development. Multi-stage systems are used only in large cities with a population of more than 1 million people.

In our case, a two-stage gas supply system with maximum overpressure in networks P = 0.6 MPa is adopted.

II.3.1.3. Selection of gas networks structural diagram

Gas distribution systems can be dead end, annular and mixed. For medium-sized cities, high-pressure and medium-pressure networks are designed ring-shaped, for small cities, high-pressure gas pipelines are routed only if necessary.

To improve the reliability of low pressure systems, dedicated main lines are looped. The supply to the consumers is provided by dead ends with the separation of the main directions, that is, such highways along which the main part of the gas transit flow is transported. In this case, the metal consumption of the ring will be minimal.

2.3.1.4. Choosing the option of connecting concentrated consumers to gas networks

The issue of connecting concentrated domestic and industrial facilities to gas networks plays an important role in optimizing the gas supply system. The correct solution of this problem ensures the reduction of capital costs in the gas supply system. It is still considered advisable to connect concentrated consumers with a gas flow rate of up to 50 m3/h to low pressure networks, and more than 50 m3/h to medium and high pressure networks. Such an approach was erroneous and entailed cost overruns.

Connection of concentrated consumers to high-pressure networks leads to an increase in the length of the latter and requires the construction of a gas control station (GRP) or plant (GRU). Connection to low pressure networks leads to the need to increase the diameters of gas pipelines from the FRG to the location of consumers and the required capacity for capital investments in the construction of low and high pressure gas pipelines and the construction of FRG.

2.3.3. Hydraulic operation modes of gas pipelines

Hydraulic operation modes of gas pipelines are taken from the conditions of creation at maximum permissible gas pressure losses of the most economical and reliable system in operation, which ensures stability of operation of hydraulic fracturing and gas control plants (GRU), as well as operation of burners of the consumer in permissible gas pressure ranges. The design internal diameters of gas pipelines are determined by hydraulic calculation based on the condition of ensuring uninterrupted gas supply to all consumers during the hours of maximum gas consumption.

Hydraulic calculation of gas pipelines is performed on a computer with optimal distribution of design pressure losses between sections of the network.

2.4. Hydraulic calculation of high pressure ring gas networks

High-pressure gas networks are the upper hierarchical level of the urban gas supply system. For medium and large cities, they are designed in ring and only for small cities they can be carried out in the form of branched dead end networks.

All city networks count on a given pressure difference. This approach to the calculation is due to the fact that gas enters the city under a certain pressure and is maintained not lower than a given value.

The design differential for high pressure networks is determined based on the following considerations. The initial pressure is the maximum SNiP for the relevant gas pipeline category. The final pressure is taken so that at the maximum load of the network, the minimum permissible gas pressure before the burners is provided, taking into account the differential pressure in the subscriber branch at the maximum load and the differential pressure in the FRG .

When calculating the ring networks, the pressure reserve is left to increase the system capacity in emergency hydraulic modes. The accepted reserve is checked by calculation in case of most adverse emergency situations. Such modes usually occur when the head portions are turned off.

Due to short-term emergency situations, the quality of the system was reduced in case of failures of its elements. The quality reduction is estimated by the Kob security coefficient, which depends on the category of consumers .

2.3.6. Hydraulic calculation of low pressure ring gas networks

The task of the hydraulic calculation is to choose the best mode of gas flow and so select the network diameters to achieve the intended flow distribution.

First stage of calculation.

We perform calculation for the area of operation of GRP1. We compose the design diagram of the low-pressure network supplied from GRP1. In the diagram, we show the network, the power supply, we number all the nodes of the network. Geometric lengths of sections are measured according to the city plot plan in accordance with the scale. Next, we determine the track and equivalent gas flow rates for the sections, we determine the calculated lengths of the sections. If the analysis of gas from the network is one-sided, then the calculated length is taken equal to half the geometric length of the section, if two-sided, - the full length

Literature

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SNiP 2.07.0189 *. Urban planning. Planning and development of urban and rural settlements. M: Gosstroy of Russia, 2001.

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SP 421012003. General provisions for the design and construction of gas distribution systems made of metal and polyethylene pipes. M: CJSC Polymergaz, 2003.

SNiP 41022003. Thermal networks .M: Ministry of Construction of Russia, 1994.

Lived V.A., Ushakov M.A., Bryukhanov O.N. Gas networks and installations. -M.: "Academy," 2003.

Bryukhanov O.N. Natural and artificial gases. -M.: "Academy," 2004.

Gas control stations and installations. Reference Subed. And V Meshchaninova, V.A. Zhili, O.V. Platonova. M.-ZAO "Polymerigaz," 2000.

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SNiP 42012002. "Gas distribution systems." - M: Gosstroy of Russia, 2003.

N.I. Kurilenko, L.Yu.Mihailov. Methodological manual for the course project "Gas supply of the city." TyumGASA, 2007

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