16-apartment residential building - gas supply

1.3. city gas supply system

1.3.1. Gas Supply Diagram

The power supply of the city gas distribution system is two gas distribution stations: GS1 and GS2.

Gas supply system is two-stage:

stage - high-pressure gas pipelines (P up to 6 kgf/cm2).

stage - low-pressure gas pipelines (P up to 300 mm. waters. article).

The high-pressure gas supply scheme is adopted as a dead end ring.

Gas control stations are supplied with natural gas from high-pressure urban distribution networks:

- low pressure distribution networks;

- heating boiler houses;

- bath and laundry plants;

- industrial enterprises;

- bakery.

Utilities (hospitals), connected to low-pressure distribution networks as concentrated consumers. The number of gas control points is determined by the radius of optimal action of one gas control point, which is equal to RGRPopt = 700 1000 m.

The diagram of laying low-pressure gas pipelines is adopted as dead-end ring. The main consumers of this gas supply system are residential buildings.

The gas pipelines of the low and high pressure network are laid along the streets. When high and low pressure gas pipelines pass through one street, the pipes are laid in one trench parallel to each other.

The project considers two options for laying low-pressure gas networks. Hydraulic calculation and calculation scheme are made for the gas pipelines routing.

In the first version, a dead-end circuit of gas pipelines with a range of GRP equal to 1000 m (the number of gas control points is 5 pcs) is adopted.

In the second version, the diagram of gas pipelines wiring with the range of GRP equal to 700 m (number of gas control points - 7 pcs) is adopted.

1.3.2. Hydraulic calculation of gas pipelines

The diameters of low and high pressure gas pipelines are determined by hydraulic calculation from the conditions of normal and economic gas consumption by all consumers during the hours of maximum gas consumption at maximum permissible pressure drops. The design pressure drop in low pressure distribution networks is accepted from 100 to 120 mm. waters. at gas pressure at EMG outlet - 300 mm. waters. Gas pressure on high-pressure networks is accepted at the outlet of SGN - 6.0 kgf/cm2 (g). The pressure at the point of connection of the concentrated consumer in the high pressure network exceeds 3 kgf/cm2 (g.).

Hydraulic calculations of low-pressure gas pipelines are made on a personal computer.

When calculating according to variant No. 1, 5 pcs are accepted. FRG (network), according to variant No. 2 - 4 pcs. FRG (network) and 3 pcs. FRG (cabinet). Cabinet GRP installed based on natural gas flow rate up to 1000 m3/h

As a result of a technical and economic comparison of the two options, option No. 1 was adopted. Results of hydraulic calculation of high and low pressure networks are attached

1.8. boiler house

This section provides the internal gas equipment of the boiler house of the industrial enterprise.

The boiler house has 4 KVSA1.0 boilers with a thermal capacity of 0.86 Gcal/hour each. The boiler room is designed to heat existing buildings of the industrial site. Natural gas with combustion heat QH = 8040 kcal/m3 is used as the main fuel. Gas composition and properties are given in Table 1.1.2

1.8.1. Internal gas equipment

The project provides for the supply of gas to the gas cooler unit of the boiler.

Technical characteristics of KPSA1.0 boiler

Heating capacity, MW (Gcal/hr) 1.0 (0.86)

Type of natural gas fuel

EFFICIENCY, % 93

Gas flow rate per boiler, m3/h 115

Nominal gas pressure upstream of the burner, mm.w.s. 250

Furnace pressure, Pa 500

Exhaust gas temperature, С, not less than 160

Hydraulic resistance, kgf/cm2 not more than 0.25

Specific power consumption, kW/MW 1.2

Rated vacuum downstream boiler, Pa 30

Type of BG1,6 - G2 - 1 Automatic control principle 100%, 40%, OFF

Volume of water in the boiler, l 980

Content of dry combustion products of oxides

- carbon, mg/m3 0

- nitrogen, mg/m3 86

Operating pressure of water in the boiler, MPa not more than 0.6

Overall dimensions. mm 2860х1200х2480

For pressure decrease of gas from PBX=3.02 of kgf/cm2 (log huts) to RVYH = 420 mm. water column. there is a cabinet GRP with one process line with one control stage. For uninterrupted operation of the cabinet GRP during repair or replacement of gas equipment, a bypass gas pipeline is provided. The cabinet GRP of GRPSH 13-1VU1 type is equipped with:

• RDG 50V type natural gas pressure regulator;

• safety relief valve providing discharge of a part of the gas into the atmosphere at gas pressure increase of 0.175 kgf/cm2;

• safety shut-off valve providing gas supply termination to the consumer at pressure increase more than 0.190 kgf/cm2 or pressure decrease below 0.115 kgf/cm2;

• disconnecting devices at the inlet and outlet of the cabinet GRP;

• removed fine filter with pressure gauge to measure pressure in front of it and self-recording devices to measure the difference on it.

• pressure gauge at the outlet for pressure measurement;

bypass cranes, which allow carrying out preventive work.

2. automation of gr and kvsa boiler - 1.0

2.1. General provisions

The city gas supply system is a complex system including a gas supply source, a gas distribution network, and internal gas equipment. When supplying the city with natural gas, the source of gas supply is a main gas pipeline with one or more gas distribution stations (GRS). Through the city there are city distribution gas pipelines with gas control points (GRP) designed to reduce the gas pressure to the pressure necessary for the operation of the consumer. Reliable, economical and safe operation of this system is possible only if there is comprehensive automation of all nodes included in it. The positive properties of gas as a fuel create favorable conditions for the complex automation of the combustion process.

The structure of gas supply systems can be different. One-, two-, and multistage gas distribution systems are used, in the elements of which pressure is successively reduced (reduced) to the working one.

Automatic control of the combustion process in order to maintain a given technological mode while observing high combustion rates and gas combustion safety significantly increases the economy of gas-using plants. Increasing the efficiency of equipment and plants, better meeting the quality of heat generated to technological requirements and reducing the number of maintenance personnel make it possible to increase the cost-effectiveness of gas use. In addition, automation improves the working conditions of service personnel and contributes to their technical level.

Depending on the functions performed, the automatic devices carry out:

monitoring and measurement

alarm system

protection

management

regulation

Automatic monitoring and measurements allow you to continuously monitor the quantitative and qualitative indicators of the process using instrumentation and equipment. Automatic control means the automatic start and stop of individual units of equipment and units as a whole. Automatic control devices are divided into automatic and semi-automatic. In the first case, the device is switched on under the influence of pulses sent by sensors that monitor the mode of process equipment. In the second case, the devices are switched on with the participation of a person, pressing buttons and levers. In automated electric motor control systems, they are protected from short circuit, from reduced voltage and from heat load. Automatic adjustment is designed to maintain the specified operating modes without human participation.

In accordance with this, they distinguish:

system for automatic maintenance of specified parameter value

automatic program control system

tracking system

optimal control system.

2.2. Functional diagrams

2.2.1. Functional diagram of FRG automation

The GRP (GRU) should provide for the installation of display and recording instrumentation (instrumentation), including for the measurement of inlet and outlet pressure. According to the requirements of paragraph 5.19 of SNiP 2.04.-8-87 *, it is allowed not to provide for the installation of recording devices in cabinet GRP.

The FRG circuit has a gas flow rate unit using a narrowing device (diaphragm), a filter unit, two process reduction lines with a pressure regulator, a safety shutoff valve (PSV), and a safety relief valve (PSV) is installed on the outlet gas pipeline. Two lines - in case of failure of one of the reduction lines, operation on the second line is possible. It is provided to install blowdown and discharge pipelines brought out to places providing safe conditions for gas dispersion, but not less than 1 m above the eaves of the building.

Monitoring of pressure at the inlet, on the process line before PZK and on the outlet is performed by indicating pressure gauges of MTS712 type (2, pos.3, pos.9, pos.10, pos.12).

Temperature control is provided by technical indication pressure gauge of P-2 type (pos.1) with measuring range from -50 to + 50С and thermometers with self-recording liquid pressure gauges of TZhS712 type (pos.72, pos.8-2) with measuring range from -50 to + 50С.

Measurement of gas flow is performed by self-recording differential pressure gauges with additional record of excess pressure of DSS7122C type (item 52, item 53, item 62, item 6-3).

The pressure difference on the filter is controlled by the differential pressure gage recording the DSS712M type (poses.3).

2.2.2. Functional diagram of KVSA1.0 boiler automation

In this section, the project of automation of KVSA1.0 boiler designed for heat supply of the enterprise was developed.

Control

Controlled parameters are:

- air and gas pressure at certain points of the process diagram;

- gas and air temperature;

- gas flow rate;

- presence of a flame in the volume of the boiler furnace.

The air pressure at the boiler burner inlet is controlled by the MTS712 indicating pressure gauges (item 10c, item 18);

Flue gas pressure is controlled by MTS712 pressure gauges (item 24).

The pressure in the furnace is controlled by the MTS712 indicator pressure gauges (item 11, item 23) by a self-recording differential pressure gauge with remote transmission of the CPD type (item 13a).

The gas pressure upstream of the boiler is controlled by a MTS type pressure gauge (item 5).

The gas pressure at the boiler inlet, after the last shutoff element, is controlled by the MTS712 indicator pressure gauge (item 16).

The hot water temperature at the boiler outlet is controlled by a pressure gauge thermometer with remote transmission (pos.15a) connected to an IR GF type indicating thermometer (pos.15b).

Gas flow rate is controlled by DSS7122C display and recording differential pressure gauge.

Management

Control of the autoregulator of fuel, autoregulator of pressure in the boiler furnace, electromagnetic valves is carried out using electric drives.

Automatic regulation and protection

Control automation includes:

- fuel automatic regulator and temperature relay (pos.15b) - fuel flow control depending on hot water temperature (maintaining it at the level not higher than 115 С).

- autoregulator of pressure in boiler furnace.

- automatic air supply regulator (regulation of "gas air" ratio).

All regulators are made on the basis of devices of RS 29.0.12 type; RS 29.2.22 with electric actuators of MEW type.

The emergency protection system includes:

- pressure switch of maximum protection (pos.8) and pressure switch of minimum protection (pos.9), which respectively at pressure increase or decrease above permissible limits, cut off gas supply and send a signal to the control board.

- temperature relay (pos.14b), connected to the manometric thermometer (pos.14a), which, when the water temperature at the boiler outlet rises above the permissible limit (115C), cuts off the gas supply and sends a signal to the automation board.

2.3. Schematic electrical diagrams

2.3.1. Electrical ignition diagram

Ignition

The universal SA1 switch is put in position "P". When the SB1 button is pressed, the current passes through relay KV1; closes the contact KV1, shunt button and contact KV1, which includes three-minute purging of gas ducts; HL1 lamp comes ON (see protection diagram); after 3 minutes the contact of time relay KT1 is closed. Current goes to the solenoid of the igniter, opening the gas supply. At the same time, the current goes to the transformer of the igniter - a spark occurs. If there is no flame, the contact of flame presence sensor (7c) is opened. When a flame appears, it closes, the current goes through the KV2 relay, the KV2 contact closes, passing current through the electromagnets of the gas supply valves and at the same time the current supply to the transformer is turned off. The time relay KT2 opens the contact KT2, the relay KV1 is de-energized, which turns off the solenoid of the igniter, cutting off the gas supply to the igniter.

Pressing of the SB4 button cuts off power electromagnets of U1 and U2 cut-off valves; the valves are closed, cutting off the gas supply.

2.3.2. Electrical circuit of automatic protection

Gas pressure deviation

If the gas pressure exceeds the allowable limits, one of the contacts (item 8 or item 9) is opened and relay KV4 is de-energized, contact KV4 is closed and lamp HL4 is lit, which signals the deviation of the gas pressure. At the same time, contact KV4 on the emergency shutdown line is opened, relays KV10 and KV11 are de-energized. Contact of relay KV10 in power supply line of solenoids of shut-off valves is opened. The solenoids of the shut-off valves are de-energized, the valves are closed, cutting off the gas supply.

Air pressure is low

If the air pressure drops below the allowable limits, the pressure switch contact (pos.17) is opened and relay KV5 is de-energized. Contact of relay KV5 is closed and signal lamp HL5 "Air pressure is low" comes ON; KV5 contact in emergency shutdown line is opened at the same time; this causes relays KV10 and KV11 to de-energize. Contact of relay KV10 in power supply line of solenoids of shut-off valves is opened. The solenoids of the shut-off valves are de-energized, the valves are closed, cutting off the gas supply.

Furnace pressure high

If the boiler furnace pressure is higher than permissible, the pressure switch contact (12) is opened and relay KV6 is de-energized. Contact of relay KV6 is closed and signal lamp HL6 "Pressure in the furnace is high" is illuminated; KV6 contact in emergency shutdown line is opened at the same time; this causes relays KV10 and KV11 to de-energize. Contact of relay KV10 in power supply line of solenoids of shut-off valves is opened. The solenoids of the shut-off valves are de-energized, the valves are closed, cutting off the gas supply.

Temperature is high

If the hot water temperature at the boiler outlet rises above the allowable value, the contact of the temperature relay is opened (pos.14b) and relay KV7 is de-energized. Contact of relay KV7 is closed and signal lamp HL7 "High temperature" comes ON; KV7 contact in emergency shutdown line is opened at the same time; this causes relays KV10 and KV11 to de-energize. Contact of relay KV10 in power supply line of solenoids of shut-off valves is opened. The solenoids of the shut-off valves are de-energized, the valves are closed, cutting off the gas supply.

Flare failure

If the flare goes off, the flame sensor contact (p.7c) opens, relay KV3 is de-energized, contact KV3 opens, de-energizing relay KV8. Contact KV8 closes and the signal lamp HL8 "Torch Flare Off" comes ON. At the same time, contact KV8 in the emergency shutdown line is opened; this causes relays KV10 and KV11 to de-energize. Contact of relay KV10 in power supply line of solenoids of shut-off valves is opened. The solenoids of the shut-off valves are de-energized, the valves are closed, cutting off the gas supply.

Emergency shutdown

Pressing SB3 button opens the electrical circuit, de-energizing relays KV10 and KV11. Contact of relay KV10 in power supply line of solenoids of shut-off valves is opened. The solenoids of the shut-off valves are de-energized, the valves are closed, cutting off the gas supply.

Voltage control

At absence in network of tension the KV12 relay is cut off power, the contact of KV12 is disconnected (cm the scheme of ignition), electromagnets of U1 and U2 cut-off valves are cut off power, valves are closed, cutting gas supply.

Conclusion

Automation of TGiV systems allows you to safely operate gas-using equipment, rationally use gas fuel, and reduce the cost of maintaining maintenance personnel.