Diploma project Gas supply to the city and district boiler house

Contents

Contents

1. Gas supply to the city and the district boiler house

1.1. Introduction

1.2. Characteristics of the city and gas consumers

1.3. Gas Properties Definition

1.4. Determination of the number of network GRP, identification of their zones of operation and calculation

number of inhabitants in these zones

1.5. Determination of estimated gas flow rates by network GRP

1.6. Determination of gas consumption by concentrated consumers

1.6.1. Determination of gas consumption by hospitals

1.6.2. Determination of gas consumption by bakery

1.6.3. Determination of BOD gas flow rate

1.6.4. Determination of gas flow rate by district boiler houses

1.6.5. Determination of gas consumption by industrial consumers

1.7. Choice of gas supply scheme of the city. Hydraulic calculation of gas pipelines

high pressure for 3 operating modes

1.8. Hydraulic calculation of medium pressure gas pipelines

1.9. Selection of low-pressure gas supply scheme

1.10. Selection of gas supply scheme and hydraulic calculation of gas pipelines

low pressure in the area of hydraulic fracturing

1.11. Calculation and selection of network GRP equipment

1.12. Gas equipment of the district boiler house

1.13. Calculation of gas burners

1.14. Hydraulic calculation of boiler house gas pipelines

1.15. Selection and calculation of GRU equipment of district boiler house No.

1.16. Anti-corrosion protection of gas pipelines

2. Automation of the city gas supply system and district boiler house

2.1. Introduction

2.2. Automation of the city gas supply system

2.3. District Boiler House Automation

3. Project for the production of bot

3.1. Introduction

3.3. Specification of main and auxiliary materials

3.4. Accepted installation technology for construction and installation works

3.5. Required number of machines, mechanisms and tools for the production of bot

3.6. Bill of Quantities for Construction and Installation Works

3.7. Production costing

3.8. Calculation of labor capacity of enlarged assembly processes for

of the calendar plan

3.9. Production schedule of the bot

3.10. Work Schedule

3.11 Network Schedule

3.12 Basic Rules for Building a Network Graph

3.13. Build a network graph

3.14 Network Calculation

3.15. Procedure for preparation of Job Instruction for Installation Proekt

3.16 Technical and economic indicators of the PPR

4. Economic performance of the gas supply system

4.1. Introduction

4.2 Calculation of estimated cost of construction and installation works

4.3 Calculation of annual operating costs for the gas system

4.4 Technical and economic indicators of the project

5 Occupational safety

5.1 Safety precautions when laying gas pipelines

5.1.1Safety Technics for Handling Works

5.1.2 Excavation Safety

5.1.3 Safety precautions when laying pipes in trenches and welding works

5.1.4. Safety precautions for waterproofing works

5.1.5. Piping Test Safety

5.1.6. Safety precautions during operation of gas-using units

5.1.7 Hazardous areas on the construction site

5.2 Industrial sanitary service

5.3 Fire Safety

Literature

1. Gas supply to the city and district boiler house

1.1. Introduction

The development of the gas industry and gas supply of cities, towns, industrial enterprises based on natural gases in the USSR began in the mid-40s. In 1946, the first large Saratov-Moscow gas pipeline was commissioned. The launch of this gas pipeline is the beginning of the wide gasification of the country. Currently, the CIS countries rank first in the world in terms of natural gas reserves and production.

The development of the gas complex of the Republic of Belarus began forty years ago. The first consumers of Minsk natural gas was supplied in 1960. Wide gasification of RB was carried out in 1976-1980. Gasification of housing stock in cities was completed, and in rural areas its level reached 75%. To improve the reliability of gas supply to the Minsk Industrial Hub, an underground gas storage facility in Osipovichi was commissioned in 1976. For 19801985 An extensive network of main gas pipelines was built and 3 lines of the Torzhok-Minsk-Ivatsevichi gas pipeline were put into operation and branches from it to Mogilev, Gomel, Klimovichi, later branches to Bobruisk, Vitebsk, Molodechno. Currently, the construction of the Pribug underground gas storage is underway.

A significant increase in demand for natural gas as a coolant is facilitated by its low cost, ease of transportation to the consumer, which, together with high quality indicators and ease of control of technological processes, provides a high economic effect.

The modern city distributive systems of gas supply represent themselves the difficult complex of constructions consisting of the following basic elements:

Low, medium and high pressure gas networks;

- gas distribution stations (GDS);

- gas control stations (GRP);

- gas control units (GRU).

For the control and operation of this system there is a special service with appropriate means to ensure the possibility of uninterrupted gas supply.

Gas supply projects of regions, cities, villages are developed on the basis of promising gas flows, schemes for the development and placement of sectors of the national economy and regional planning projects, master plans of cities taking into account their development for the future. The gas supply system shall ensure uninterrupted gas supply to consumers, be convenient in operation and maintenance, shall provide for disconnection of its individual elements or sections of gas pipelines for repair and emergency works.

The main element of urban gas supply systems are gas pipelines, which are classified by gas pressure and purpose. Depending on the maximum gas pressure, city gas pipelines are divided into the following groups:

1. low-pressure gas pipelines with a gas pressure of up to 5 kPa;

2. medium-pressure gas pipelines with a pressure from 5 kPa to 0.3 MPa;

3. high-pressure gas pipeline of category 2 with pressure from 0.3 to 0.6 MPa;

4. high-pressure gas pipelines of 1 category with gas pressure from 0, 6 to 1.2MPa.

Low-pressure gas pipelines serve to transport gas to residential, public buildings and consumer services.

Medium and high (2 category) pressure pipelines are used to supply urban low and medium pressure distribution networks through the FRG.

City gas pipelines of high (1 Category) pressure are arteries feeding a large city, they are made in the form of a ring, half-ring or in the form of rays. In this project, it is necessary to select and calculate the gas supply systems of the city and the district boiler house .

The use of gas fuel in the national economy makes it possible to intensify and automate production processes in industry and agriculture, provides easy regulation of temperature fields and the composition of the gas medium in the working space of furnaces and plants, as a result of which the quality of the obtained products is improved.

The use of gas as fuel makes it possible to significantly improve the living conditions of the population, improve the sanitary level of production and improve the air pool in cities and industrial centers.

1.16. Corrosion protection of gas pipelines

Depending on gas composition, pipeline material, laying conditions and physical and mechanical properties of soil, gas pipelines are subject to some degree of internal and external corrosion. Corrosion of internal pipe surfaces mainly depends on gas properties. It is due to the increased content of oxygen, moisture, hydrogen sulfide and other aggressive compounds in the gas. The control of internal corrosion is reduced to the removal of aggressive compounds from the gas, that is, to its good cleaning.

It is much more difficult to control corrosion of the outer surfaces of pipes laid in the ground, i.e. soil corrosion, which is inherently divided into chemical, electrochemical and electrical.

Corrosion of the metal in the soil is mainly electrochemical in nature and is the result of the interaction of the metal, which acts as electrodes, with aggressive soil solutions that act as an electrolyte, i.e. the metal of the pipe will be destroyed due to the formation of galvanic (corrosive) pairs. The process of electrochemical corrosion is increased many times in the presence of wandering currents in the ground, branching off from various electrical installations and current-conducting underground structures. The type of corrosion arising under the influence of wandering currents is called electrical .

In sections of the route where there are wandering currents, underground pipelines become conductors, and in the anode zone the current drains from the pipes and "takes away" the metal the stronger, the greater the current density. In this regard, special protection of underground pipelines against corrosion is carried out.

A passive method of protecting underground pipelines from corrosion consists in applying waterproofing coatings that prevent the pipelines from contacting the environment and increase electrical resistance to electric currents.

Active methods include electrical drainage, cathode and anode protection. These are special electrical devices used for organized removal of wandering currents from the anode zones or for bringing the pipeline to the cathode state with current from an external source.

According to GOST 9.60289, protective coatings corresponding to a very reinforced type should be used on steel gas pipelines laid directly in the ground within the territories of cities and other settlements, and with increased, high and very high corrosion activity of the soil, in addition to the use of insulation coatings, it is also necessary to carry out cathode polarization of the structure.

Thus, to protect gas pipelines from soil corrosion, an insulating coating based on extruded polyethylene is adopted, having the following structure: an adhesive sublayer based on savylene with adhesive active additives; extruded polyethylene. The total thickness of the protective coating is not less than 3 mm.

Gas pipelines made of polyethylene pipes are located on the territory of the design area. A feature of the use of polyethylene pipes is their high resistance to three-person types of electrochemical corrosion. They are not subject to soil corrosion and do not require cathodic protection.

2. Automation of the city gas supply system and district boiler house

2.1. Introduction

The principles of automation of gas supply and gas consumption systems depend on the main technological processes, which include: movement, storage and combustion of gas in industrial and domestic installations.

The specifics of gas supply and gas consumption systems determine the equipping of subsystems for automatic control of technological parameters and automatic safety, and the latter pays more attention, bearing in mind the requirements of labor protection and reliability of equipment operation.

This section of the diploma project deals with automation of the city gas supply system and automatic regulation of the gas combustion process in boilers.

2.2. Automation of the city gas supply system

To supply natural gas to the city, a high-pressure network has been designed. Gas from the GRS through the ring network is supplied to concentrated consumers and network GRPs. In GRP, the gas pressure decreases and then gas flows through a branched network of low-pressure gas pipelines to residential buildings. To cover the needs of the population in hot water supply and heating, district boiler houses have been designed.

The equipment of the network gas control stations consists of the following main links and elements: a gas pressure control unit with a safety shut-off valve and a bypass gas pipeline (bypass); safety relief valve; filter; set of instrumentation; purge lines.

High-pressure gas enters the FRG and enters the control unit, in which the equipment along the gas flow is located in the following sequence: disconnecting device; filter for gas cleaning from mechanical impurities and dust; safety shut-off valve for disconnecting gas supply to consumers at unacceptable increase or decrease of gas pressure downstream the regulator; pressure regulator for reducing gas pressure and keeping it constant after itself; disconnecting device.

Cast-iron hair filters are installed on FRG for gas cleaning. The gas pressure drop in the filter shall not exceed 10,000 Pa, at greater pressure drop the filter shall be removed and cleaned. The differential pressure is controlled by a differential pressure gauge.

The output pressure from the FRG is controlled by a safety shut-off valve (PSV) and a safety relief valve (PSV). SZK controls the upper and lower limit, UCS - only the upper limit. The UCS is adjusted to a lower pressure than the PZK, because of this it operates first. The gas is released into the atmosphere if the pressure regulator is operating normally, but when closed, the valve does not provide leak tightness of the shutdown (due to clogging, wear, etc.). If leakage through the loosely closed valve exceeds gas consumption, then the output pressure will increase. To prevent pressure rise, excess gas must be discharged into the atmosphere. Such situations are usually short-lived (at night), and the amount of gas discharged is insignificant. UCS actuation under specified circumstances prevents closing of safety shut-off valve and violation of normal gas supply to consumers.

If the pressure regulator failed, the UCS worked, and the pressure in the networks continues to grow, then this situation is emergency. In this case, the MPC operates, its valve closes the gas pipeline before the regulator and stops the gas supply to consumers. The BSV will also operate in case of unacceptable reduction of gas pressure, which can occur in case of an accident at the gas pipeline. By eliminating the reasons for the gas shutdown, its supply to consumers does not automatically resume. Only maintenance personnel can start gas again, which prevents accidents and accidents during gas start-up.

The UCS is adjusted to a pressure above the controlled pressure of 10%. At low output pressure, the difference between the valve setting pressures and the controlled pressure shall be at least 500 Pa.

The upper limit of SGSV setting is assumed to be 20% higher than the controlled pressure after the FRG. The lower limit is the minimum permissible gas pressure in the networks.

Pulses for PZK, UCS and pressure regulator are taken from the gas pipeline after the FRG at the place where the gas inflow has stabilized.

For uninterrupted supply of gas to consumers in case of failure of pressure regulator, replacement, repair or inspection of control unit equipment, bypass gas pipeline (bypass) is provided. In these cases, the control line is disconnected, and gas is supplied by bypass with manual pressure control. For reliability and convenience of manual control, two disconnecting devices are installed in series on the bypass: a crane and a gate valve. During manual control, the main pressure drop is actuated on the valve, and the gate valve controls the pressure in accordance with the changing load.

To blow down the gas pipeline to the FRG, gas pipelines and equipment of FRG, as well as to discharge gas during repairs and replacement of FRG equipment, special blowdown gas pipelines are provided, which are brought outside to safe places for surrounding buildings and structures, but not less than 1 m above the eaves of FRG building. Discharge gas pipelines (plugs) from the UCS obey the same requirements.

Gas from the main gas pipelines is supplied to the city gas supply system through the gas distribution station (GRS). gas pressure is reduced to 0.7 MPa at GPC and kept constant.

The main difference between the gas distribution station and the city and industrial gas distribution points is that it receives gas from main gas pipelines, and therefore its equipment is calculated for an operating pressure of 5.5 MPa, i.e. for the maximum possible in main gas pipelines. In addition, the GRS is characterized by a large throughput, in this regard, gas throttling on it is carried out in several lines and a high throughput pressure regulator is installed on each of them, respectively.

In addition to gas purification, GVC filters also provide for its gifting. Flow meters for measuring the amount of flowing gas are installed on the GDC. Since it is impossible to allow a break in the gas supply to the city and large industrial consumers, the protective automation of the GRS is created on the principle of redundancy, and not disconnection of gas flow in case of failures of regulatory equipment.

The automation of the GRS is carried out in such a way that it is possible to maintain it without watchless. For this purpose, the GDC is equipped with instrumentation, protective automation, remote control of disconnecting devices and alarm. Such a GRS is served by two operators at home. In case of malfunctions, light and sound unencrypted signals are sent to both operator's apartments, upon receipt of which the operator on duty is sent to the operator's apartment for troubleshooting. The duty of one operator lasts for a day, while he is in the GRS for about 4 hours. The operator's house is located at a distance of 300500 m from the GRS.

The GDC is equipped with the following process equipment located along the gas flow: inlet valve of the disconnection unit, gas purification unit, gas pressure throttling and control lines, flow meter line, outlet disconnecting valve.

In case of emergency or during repair works it is possible to supply consumers with gas via bypass line (bypass) with manual control of gas pressure.

To automatically prevent the controlled gas pressure from going beyond the permissible limits, automatic protection systems are provided on the GRS, which are built using the following two principles.

1. Systems with reconfiguration of operating modes of pressure regulators. These systems provide for operating and standby control lines. Working and check valves are installed on each line. Under normal operating conditions, the control valves are open because they are set to a pressure slightly higher than nominal. The backup line valves are set to a pressure slightly less than nominal, so they are closed. Therefore, the system operates using the lightweight reserve method (when the reserve is in incomplete working mode).

In case of emergency opening of the operating control valve and increase of output pressure, the control valve is actuated, which prevents unacceptable pressure increase and keeps it constant. In case of emergency closing of the control valve and pressure reduction, the standby line is switched on and pressure reduction is stopped.

2. The next protection principle is to install a valve with pneumatic drive and program control on each line of reduction. When the controlled pressure increases, the valve turns off the line with the failed control valve, pressure decrease prevents the standby line.

The program can selectively turn off the damaged reduction strings and turn on the backup ones. In this case, with three reducing threads, one of which is standby, under normal conditions, all the threads work and all pneumatic valves are open. Thus, the system operates according to the method of loaded reserve, i.e., when the reserve is in working mode. In case of emergency opening of one of the regulators and increase of output pressure, the protection system sends a command to close the first line. If after its closing the pressure continues to increase, therefore, the regulator is serviceable, then the valve on the second line closes, and on the first line opens. If at the same time the controlled pressure stops increasing, then the protection ceases to work, since, obviously, the regulator of the second thread failed. If, finally, the pressure continues to grow, then the defense will close the third line and open the second.

2.3. District Boiler House Automation

The diploma project considers the system of automatic regulation of the gas combustion process in PTVM30M boilers. The schematic diagram as well as the protection diagram are shown on the graphic material sheet.

Automatic control of the combustion process significantly increases the economy of gas-using plants. The use of automation ensures the safety of gas use, improves the working conditions of maintenance personnel and helps to increase its technical level. Complex automation consists of the following main systems: regulation automation, safety automation, alarm and heat control.

Automatic control of boilers is designed to control the process of gas combustion so that the gas-using plant operates at a given technological mode while observing optimal indicators of gas combustion.

Control of coolant discharge to consumers is performed by changing its temperature. To do this, three sensors are installed: for measuring the temperature of the outside air, for measuring the temperature of the coolant in the supply and return pipelines. Signals from sensors are transmitted to temperature controller, which is connected to magnetic starter of shutter actuator. When the position of the damper changes, the gas supply to the boiler furnace increases or decreases.

The combustion process of gaseous fuel is controlled by stabilizing the vacuum in the boiler furnace and proportioning the air supply to the burners depending on the gas flow rate. Air supply is controlled by means of magnetic starter of shutter actuator. When the vacuum falls in the furnace, the boiler protection and alarm are triggered. The gas supply to the boiler stops.

Monitoring of stable gas combustion in the boiler furnace is a mandatory and basic requirement in the automation of gas fired boilers. To do this, flame monitoring devices are installed in the automation system. When it goes off, the alarm is triggered and the signal is transmitted to the boiler protection circuit. At the same time, the gas supply to the boiler stops.

Safety automation ensures trouble-free operation of the boiler, immediately stopping the gas supply to the burners in case of disruption of the gas-using plant. In addition to the above parameters, the safety system also monitors the gas pressure before the burners and the air pressure. If the gas pressure before the burners increases or decreases against the required value (25 kPa), the gas supply to the boiler stops. The signal from the monitoring devices is transmitted to the alarm system and to the boiler protection system. The gas supply is controlled by a valve motor, which is connected to devices that monitor the gas pressure in front of the burners. When the valve compartment is disconnected, the solenoid valve operates and the gas supply to the igniters is cut off.

When the air pressure drops, the alarm is triggered and the signal enters the protection circuit, the valve switch on the supply gas pipeline is actuated, stopping its supply.

Electrical diagram of boiler protection is given on the graphic material sheet. The scheme provides for termination of fuel supply in case of:

- lowering or increasing the gas pressure;

- decrease of air pressure;

- rarefaction drop in the furnace;

- burner flare failure.

In case of one of the above deviations, the contact cycles of the corresponding relay open, the circuit opens and the gas supply to the boiler stops. The interlock relay can only be switched on if there is no flame in the boiler furnace. Gas supply to burners is cut off.

The safety automation circuit provides recording of the cause of the boiler shutdown, for which it is provided to switch on the contacts of the relays of the operated sensor and the starting relay with simultaneous alarm of the cause of the shutdown on the annunciator.

When starting the boiler, ignition transformers are turned on, which open the valves of the igniters, include a ignition device and devices that monitor the presence of flame of the igniters. Then the valve switch is opened manually and gas is supplied to the burners. Then the ignition transformers are de-energized with some time delay, cutting off the gas supply to the igniters.

Work Execution Project

3.1. Introduction

The activities of the production units during the installation of gas systems are organized on the basis of the work execution project (PDP). The WDP is a working project for the organization of work on the construction site. The PWP is developed prior to the commencement of works and consists of a general part and Job Instructions .

Main documents of the PPR:

- description of the accepted method of work execution;

- specification of main and auxiliary materials;

- a statement of the need for the necessary machines and mechanisms;

- schedule of machines and mechanisms movement from object to object;

- list of scope of work;

- Production costing;

- work execution schedule;

- Labour movement schedule;

- network schedule;

- Job Instructions;

- technical and economic indicators of the PPR.

In this section of the degree project the project of works on installation of site 5 (PK2)-6 (HZ)-7 (GRP4) of the gas pipeline of high pressure is developed and the checklist on welding of not rotary joints is made.

3.2. Description of accepted method of work execution

When installing external gas networks in the diploma project, I used a consequently parallel method of performing work.

A sequential-parallel method is called such a construction organization method, which provides a systematic, rhythmic production of finished construction products (completed buildings, structures of types of work, etc.) on the basis of continuous and even work of labor collectives (brigades, flows) of constant composition, equipped with a timely and complex supply of all necessary material and technical resources.

The application of the sequential-parallel method is due to the tasks that are set and solved by construction organizations of various levels. All resources of the organization should be used continuously and continuously. This condition must be provided for each individual labor resource - the team (link) and all related tools (mechanisms, equipment, etc.).

The composition and number for a fairly long period of time should remain on average constant during the construction of heterogeneous facilities.

With the sequential-parallel method, the entire complex of works is divided into grips - part of the scope of work is carried out by a team (link) of a permanent composition with a certain rhythm that ensures the in-line organization of the construction of the facility as a whole. Homogeneous works are performed sequentially one after another, and heterogeneous works are performed in parallel.

The following features are characteristic of this method:

1. Segregation of work into constituent processes in accordance with the specialty and qualifications of the performers;

2. Dividing the work front into separate areas to create the most favorable working conditions for individual performers;

3. Maximum alignment of processes over time.

The organization of sequential-parallel production provides:

1. identification of objects close to each other in terms of space-planning and structural solutions, technology of their construction;

2. dividing the process of erecting objects into separate works, preferably equal or multiple in terms of labor intensity;

3. establishment of a reasonable sequence of works;

4. assignment of certain types of work to certain teams of workers;

5. calculation of sequence of transition of leading construction teams of workers and machines from object to object taking into account compliance with planned rhythm of construction.

The advantages of this method of work execution are:

1. preservation of construction dates;

2. possibility of performing a set of works for each capture from zero to commissioning.