Gas distribution station AGDS

Gas distribution station AGDS


The Company profile is designing and manufacturing AGDS, that is new type of industrial gas equipment for gas supply and consumption systems as well as industrial, agricultural and municipal facilities.

Gas distribution station is a key link in a gas transmission system performing the fundamental functions on delivery the natural gas to the customers from gas-main pipelines.

In 2013 our AGRS underwent tests at the "Saratovorgdiagnostika" test room.
Gas distribution station AGDS
Our automated gas distribution station is designed to reduce the high pressure, clean, odorize and measure the quantity of gas before it is delivered to the customer.
AGRS EXFORMA is suitable for outdoor use in regions with seismic activity up to 9 points according to MSK - 64. They are produced for use in the following macro climatic areas: warm (T), moderate (U), moderately cold (UHL) and cold climate (HL) due to GOST 15150-69. The climatic version is chosen depending on the area of construction.

AGDS is a set of technological equipment that provides the following basic functions:

● gas purification from mechanic impurities and condensed moisture;
● automatic, remote or manual waste of cleaning products the collection tank;
● purifying, reduction and metering of gas flow supplied for own use;
● consumer's protection from exceeding output pressure using the safety relief valves;
● short-term supply of gas to consumers via bypass station
● pulsed gas preparation for air driven valves;
● gas heating to avoid formation of crystalline hydrates and prevent equipment freezing;
● automatic control of the coolant supply for heating the gas depending on the gas temperature at the output;
● reduction and maintenance at the specified level pressure of gas supplied to the consumer;
● automatic, remote or manual waste of gas from the station in case of an accident;
● measuring the amount of gas supplied to the consumer;
● automatic control of operating modes of technological equipment;
● alarms to the operator under fault conditions.

Design


AGRS EXFORMA is produced of a single-block item as well as of separated boxes or parts ready-to-use.

Block version AGRS includes:

• switching, technological box with purification, reduction and heating unit,
• gas flow metering box,
• box for coolant preparation,
• instrumentation box, gas odorizer, condensate collection unit, odorant unit (underground or overground versions).

As usual type of flow meter and location of the gas flow measuring unit is specified when designing or ordering the station. Quantity of blocks and building type (size) are determined by the AGDS carrying capacity.
Gas distribution station AGDS
AGRS EXFORMA boxes are ready-to-use items providing accelerated installation and on-site commissioning. Internal arrangement of block-boxes provides easy access to all components and parts of the unit for revision or repair.

Boxes' sizes provide its transportation to installation place via car's, railway and water transport without distance restriction.


Sizes



Each box consists of base, frameworks of walls and roof. Outside the frameworks of walls and roof are sandwich-panelled. Boxes construction decreases noise level to 80 dBA at the distance of 1 m from the walls and the height of 1,5 m.


Colours



The wide palette of the exterior coating of boxes, elements and components of AGDS structure allows us to meet the customer's wishes.

In each station box (except instrumentation box) there are portable frames and roof that provide the easiness of capital repairs or dismantling of large-size technological equipment.

At the exterior doors' sides there are gas detection sound and light signalling systems and push-button control stations of emergency ventilation and manual fire alarms.


Heating



All AGRS EXFORMA block-boxes are equipped with heating radiators. Temperature requirements inside boxes match the climatic requirements of the equipment. This is heating system that provides air temperature no lower than +5°C in switch, technological block-boxes. The same situation is in the box of coolant preparation and in the gas flow metering unit. The temperature in instrumentation group and welfare rooms is no lower than +20°C.
Gas distribution station AGDS
Thermostatic valves in the radiator inlets regulate and maintaining the necessary temperature providing economical and rational usage of heat energy.

As usual, the AGRS EXFORMA provides double-tube unvented system of heating. The circulation of coolant is forced. Either water or non-freezing solution from list or solution allowed by boiling equipment manufacturers are used as a coolant.

As a general thing, AGDS source of heating is gas boiler which is chosen in view of thermal loads of the heating system.


Ventilation


There is general ventilation designed for the following air exchanges in AGDS.
• triple air exchange per hour in the technological box and preparation of the coolant one;
• tenfold air exchange per hour in odorizing unit;
• 1,5 multiple air exchange per hour in control room.
Emergency exhaust ventilation system with an eight-fold air exchange is activated automatically (when gas concentration sensor triggering) or manually in the rooms of A/B-la categories.


AGDS P&ID



AGRS EXFORMA includes the following elements:
• switching unit;
• gas purification unit;
• hydrate prevention unit;
• gas reduction unit;
• gas flow metering unit;
• gas odorizing unit;
• gas offtake for own use unit;
• unit for pulsed gas preparation;
• automatic control system;
• power supply system, engine electrical system, electric lightening, protection against lightning and ground connection;
• heating and ventilation.

Diameters of pipes are calculated for required carrying capacity provided that the gas velocity in pipes does not exceed 25 meters per second.

Pipes and pipe fittings are approved for use by. Material of pipes and fittings is selected on the basis of pipeline operating, climatic conditions and temperature of carrying medium.

For ease of the operating staff there are electrical and process schemes with specifications on the doors of each box.

Switching unit consists of inlet and outlet manifolds that have:
• inlet and outlet valves with remote-controlled actuators designed to shut off the gas at station's input and output;
• flare valve with remote-controlled actuator designed to release the pressure from GDS circuit. There are two safety valves with a three-way valve designed to protect consumer from impermissible gas overpressure at the outlet with the setting of outlet pressure by 1,12 at the outlet manifold. Safety valves installation diagram allows its test and adjustment without removing. Selection of pulsed gas for valves control is made in inlet manifold. To clean and dry the pulsed gas drying filters are installed.

As a part of switching unit there is a bypass line connecting inlet and outlet manifolds, designed for a short-term gas supply of consumers avoiding AGDS.

The bypass line consists of manually operated valve and valve gate as the throttling device for manual control.

From the switching unit gas enters the purification unit, designed to clean gas from solid impurities and condensed moisture.

Purification unit consists of main and backup lines working alternately (as far as filter element is contaminated). Control over the state of the filter elements is carried out by the pressure difference between the inlet and outlet of the separator. Each line provides: pressure measurement, fittings for nitrogen supply and vent pipes. Condensate from mesh filter is drained into intermediate condensate tank which is equipped by an alarm of liquid high level. When filling the tank to a certain level the condensate drains into the outer tank automatically or manually, if necessary.

Gas distribution station AGDSThe purified gas from purification unit flows into the hydrate prevention unit designed to heat the gas to the required temperature before reduction. In case when there is no need to heat the gas or in an emergency situation in a heat exchanger the gas is temporarily passed via the bypass line.

Size of gas heaters depends on the required gas temperature at the outlet of AGDS (at least equal to -10°C) providing the station's stable operation and equipment's icing elimination.

Gas is heated in a heat exchanger by the circulation of the intermediate coolant heated in a box of coolant preparation that is designed or heating, filtering, providing circulation, maintaining the required excess pressure and regulation of coolant flow that is carried for gas and AGDS boxes heating.

The coolant from the heater is served in a heat exchanger where heat is transmitted to the heated body (gas) and then chilled coolant is supplied to the boiler for heating via return line.

Coolant circuit is protected from high-pressure gas via cutoff valve, and automatic switching to the bypass or the standby line.

At the coolant return pipe, coming out of the heat exchanger, the temperature regulator is set designed for automatic control of the circulation of the coolant in the circuit of gas heater. That is, the temperature regulator in the automatic mode restricts or increases the circulation of coolant, depending on the gas temperature at the output of the reduction unit.

The pressure of circulation system's variable-capacity pumps can vary in proportion to the intensity of the coolant flow or maintain at a constant level by adjusting the rotational speed.

Cleaned and heated gas enters the reduction unit designed to reduce inlet pressure to the specified and maintaining it with the required accuracy (5%).

Reducing unit consists of main and backup lines. Main and backup reduction lines are equal both in composition of their equipment and carrying capacity which is 100% from maximum AGDS capacity for each reduction line. Under the additional agreement it is possible to arrange station with a line of small flow rates and gas flow restrictor. The transition to the backup line is carried out automatically when a deviation of ± 10% from the estimated output working pressure. There is the discharge of gas on the flare and fittings for supply of nitrogen is provided on the lines.

After reduction unit gas flows to the gas flow metering unit. The function of odorizer unit is to give the characteristic smell. The odorant is imposed into GDS pipe after bypass line in proportion to the gas flow with automatic or duplicating manual adjustment. The odorant metering unit provides automatic refilling of the outer odorizer storage tank and works at both minimum and maximum flow rate.

Gas offtake for own use is provided from the output of the pipeline after the bypass line and odorizer unit.

Unit of gas offtake for own use involves reduction unit consisting of two regulators (main and backup) which provide stable outlet pressure independently from inlet pressure changes.

Safety shut-off valves built in regulators ensure gas shutoff in cases of rise and decline of pressure from the estimated values. The gas used for own and technological needs after reduction is subjected to metering with automatic temperature and pressure correction.


Software of control and management AGDS equipment



Gas distribution station AGDSSoftware for control and management (sensors, instruments, devices and a programmable controller) is designed to automatically measure and record the flow rate of gas, as well as monitoring and management of the technical condition of AGDS equipment.


AGDS Automatic Control System



AGRS EXFORMA's ACS provides the following functions:
• control and management of the individual blocks and units and GDS as a whole, while both normal operation and in emergency situations;
• consumer's protection from both rise and decline of pressure at the AGDS outlet;
• transmission of information on the work of the AGDS to the local monitoring and control panel, operator's remote control panel (depends of the station service) and LPD CP;
• control over the actions of personnel working in the system and prevention of unauthorized access to the system;
• high reliability and efficiency of the system;
• expanding functional capacities during the operation terms;
• preservation of information (operational and archive) in the following cases:
• power failure;
• switching backup power source;
• failure of ACS components;
• failure of connection with telemechanics control panel.