Electrically Driven Gas - Pumping Units (EGPU)

Compressor power: 4, 6 and 12 MW.

The centrifugal compressors are equipped with:

• dry gas dynamic seals system;
• active magnetic bearing system of the rotor (complete set of bearings) produced under the license of S2M;
• confusor, complete set of transducers to measure gas flow for operation of the anti-surge protection and in-process measurement of the centrifugal compressor capacity with an accuracy of no more than 4 %;
• complete set of tools for assembly and disassembly of the compressor.

The compressor rotor is equipped with two radial magnetic bearings and a double-sided axial magnetic bearing, the electric motor rotor — with two radial magnetic bearings. Safety bearings (included in the AMBS) provides the runaway of the unit rotors in case of emergency power cutoff of the magnetic bearing system.

Safety bearings (included in the AMBS) provides the runaway of the unit rotors in case of emergency power cutoff of the magnetic bearing system.

The active magnetic bearing system of the centrifugal compressor is controlled and monitored from the dedicated control cabinet.

Explosion protection of the magnetic bearing is provided by the compressor design.

Technical characteristics centrifugal compressors

All the EGPA described are supplied in the completely dry version (with dry gas seals and active magnetic bearings) excluding the need for oil, which, in its turn, reduces considerably the operating costs.

The motor and compressor design employs an active magnetic bearing providing non–contact suspension of the compressor and motor rotors in the controlled magnetic field before startup, during operation and shutdown of the unit.

The active magnetic bearing system is produced on Nevskiy Zavod site according to the licensed technology of S2M.

The bearings are completed with:

• auxiliary bearings providing up to 20 emergency “falls” emergency falls of the rotor at the nominal speed;
• temperature sensors;
• inductive transducers of radial and axial movement;
• the rotor speed transducers.

Advantages of the system:

• lower operating costs;
• longer service life of the bearing parts;
• higher efficiency due to absence of mechanical losses;
• fewer additional equipment;
• higher reliability;
• better environmental characteristics.

Produced under the license of Converteam or Joint Venture “Siemens– Electric Drive”.

The semiconductor frequency converters are equipped with an input matching transformer (transformers), cooling system, providing the output parameters of the electric drive to the preset accuracy in case of changing supply voltage, acceleration and deceleration of the electric motor at a preset rate within the allowable output current of the semiconductor frequency converter.

The control system of the semiconductor frequency converter is microprocessor–based and provides control of the el. motor, control, diagnostics and protection of the semiconductor frequency converter.

The operating area of the semiconductor frequency converter relay protection covers both the electrical circuits of the semiconductor frequency converter proper, and the el. motor stator coils.

The cooling system of the semiconductor frequency converter allows for any number of starts of the EGPU without limiting the interval between starts.

The el. motor power rating — 4.0; 6,3 and 12.5 MW.

The el. motors produced at the “Siemens– Electroprivod” Co., Ltd. are designed to drive the centrifugal compressor having squared relationship between the torque on the shaft and speed. The torque of the electric motor is transmitted directly to the compressor shaft by means of an intermediate flexible shaft.

The electric motor operates as part of the frequency variable electric drive with power supply from the frequency converter.

The 4 and 6 MW el. motors are cooled by air. The 4.0 MW el. motor is equipped with a built–in fan; the 6.3 MW el. motor is provided with an external ventilation unit.

The 12.5 MW el. motor has a combined air–liquid cooling with an internal heat–exchanger.

Converter protection

Type of protection	Protection implementation
Current protection against external multi-phase shorting	Current cutoff without time delay
Current protection against single - phase ground short circuit	Current protection without time delay, operating for trip
Protection against overload	Operates for reduction of the motor rotor speed
Current protection against phase failure	Operates for trip without time delay
Protection against the internal cooling system failures	Its operation is determined by the algorithms specified in the operational documentation
Protection against voltage rise	Operates for trip
Protection against voltage drop	Operates for trip with a delay and possible use of kinetic energy store of the motor rotor to maintain voltage

The ACS is similar to that of the EMCM (electronic means of control and management) type and is designed to provide the preset operating conditions and to control the main parameters of the gas–pumping unit, its continuous and trouble-free operation.p>

The ACS provides the operation of the EGPU both completely independently, and as part of the compressor station under control of the dispatcher level systems.

The EGPU ACS is made as an integrated complete control and information system for the EGPU and its auxiliary equipment based on the industrial and proven hardware, information and software, using the rational number of the information representation formats.

ACS components:

- control cabinet — one per compressor;

- monitoring and control panel consisting of:

• tandby control panel — one per compressor;
• operator’s workstation — two compl. sets (one — the main for a group of compressors and the other — standby).

• application of the frequency variable electric drive;
• application of magnetic bearings and dry gas dynamic seals;
• decrease in the operating costs due to employment of the direct drive and absence of the oil system;
• complete automation of the equipment, application of the minimally manned technologies;
• energy saving up to 30 %;
• possibility of remote operation of the compressor station equipment;
• compliance with the up-to-date environmental requirements;
• packaged turnkey supply of the unit.