VSSG/VSG Compressor for Natural and Process Gas Compression

Why Choose a Vilter Single-Screw Compressor?

Vilter's VSSG/VSG single-screw compressors offer extended service life, high reliability, and superior energy efficiency compared to twin-screw compressors. Their design features fewer moving parts, a balanced rotor construction for reduced bearing loads, and minimal vibration and noise. The high energy efficiency is achieved through the exclusive Parallex™™ slide valve system, which ensures optimal compressor performance across the entire capacity range.

Comparison of energy consumption for single-screw and twin-screw compressors at partial loads.

Comparison of isentropic efficiency for variable and fixed capacity.

Applications

Gas liquefaction
Moisture removal
Utilisation of associated gas
Methane utilisation from coal seams
Gas compression
Wellhead gas utilisation
Secondary oil recovery
Gas recovery from organic waste
LNG evaporation
Gas collection
Biogas utilisation
Digester
CO2
Nitrogen
Hydrogen
Refrigerants

Features and Benefits

Capacity from 527 to 3480 m³/hr
Capacity control from 10-100%
Variable volume ratio (Vi) from 1.2 – 7.0
Compression ratio from 2 - 20
Moisture-proof electrical drives compliant with Class 1, Group C+D, Division II
Balanced main rotor, eliminating radial and axial loads
Parallex™™ slide valve system for maximum energy efficiency
Low bearing loads
Operation with high suction pressure
Clockwise rotation models available
Low noise levels
Low maintenance costs

Parallex™™ Slide Valve System: Provides higher efficiency at partial loads compared to twin-screw compressors. Independent control of capacity and flow rate based on load optimizes compression and saves energy.

Programmable Controller Allen-Bradley: The CompactLogix controller and AB 1000 PanelView graphic display offer high performance for standalone or integrated system control.

Heavy-Duty Oil Filter: Oil filters installed upstream of the compressor remove particles down to 25 microns. They are equipped with differential pressure sensors and shut-off valves for control and service.

Oil Cooling: Water-cooled or air-cooled options.

Unit Features

Standard Configuration

Main rotor bearings: Roller and ball, angular contact.
Unloader rotor bearings: Roller and ball, angular contact.
Manual handwheel or motor-driven optical slide valve for capacity and performance control. Complies with Class 1, Group C+D, Division II.
Variable Vi: Independent control of capacity and performance for maximum efficiency.
Separate pre-lube oil pump.
Lubrication system piping: Carbon steel with socket weld or butt weld. Minimised threaded connections.
ASME-compliant oil separator with coalescing filter.
CompactLogix programmable controller with AB 1000 PanelView graphic display.
Separate shut-off and check valves on suction and discharge sides.

Gas Line

Shut-off and check valve on the suction side.
Compressor suction filter: Stainless steel for gas systems.
Gas/Oil Separator: Removes oil from the compressed gas stream, ASME compliant with five-stage separation for oil carryover not exceeding 4 ppm.
Pressure relief valve.

Oil Line

Pre-lube oil pump with TEFC motor (totally enclosed, fan-cooled).
Oil cooling/Temperature control valve: Installed on both water-cooled and air-cooled oil coolers to remove heat of compression from the oil. A two-way valve precisely controls oil temperature entering the compressor via the programmable controller.
Oil filtration: 25 microns standard. Optional duplex oil filters allow cartridge replacement without shutting down the unit for servicing.
Oil heaters: Installed to heat oil to a minimum of 33°C before compressor start-up.

Options

Stainless steel lubrication system piping.
Suction bypass for booster applications.
Duplex oil pump.
Duplex oil filter.
Water or air-cooled oil cooler.
Low and high ambient temperature configurations.

Note: Due to the pressure differential used for the VSSG/VSG compressor lubrication system, all components are under discharge pressure and must be serviced accordingly.

Hydraulic Diagram (Figure 1)

Instrumentation

Pressure

Four pressure transmitter sensors are installed for measurement as shown in Figure 1:

PT1 Suction Pressure Sensor: (-15.0 - 400 PSIG) measures gas suction pressure at the compressor inlet.
PT2 Discharge Pressure Sensor: (-1.0 - 27.6 BARG) measures gas discharge pressure at the oil separator.
PT3 Oil Pressure Sensor: (-1.0 - 27.6 BARG) measures oil pressure before the oil filter.
PT4 Oil Pressure Sensor: (-15.0 - 400 PSIG) measures oil pressure after the oil filter at the compressor inlet.

Additional pressure sensors with specified ranges can be installed per customer request for measuring gas discharge pressure, cooling fluid pressure, or oil cooler pressure, etc.

Temperature

Four temperature transmitter sensors are installed for measurement as shown in Figure 1:

RTD1 Suction Temperature Sensor: Measures suction gas temperature at the compressor inlet.
RTD2 Discharge Temperature Sensor: Measures gas-oil mixture temperature at the compressor outlet.
RTD3 Oil Separator Temperature Sensor: Measures liquid oil temperature in the separator.
RTD4 Oil Injection Temperature Sensor: Measures oil temperature at the compressor inlet.

Additional RTD temperature sensors with specified ranges can be installed per customer request for measuring gas inlet temperature, cooling fluid temperature, or oil cooler temperature, etc.

Additional Instrumentation

Motor current transformer.
Optical sensors for determining the position of capacity and volume slide valves.

Other Options

Remote start/stop input.
Remote alarm/notification output.

Alarm and Shutdown Signals/Sequencing

The VSSG/VSG compressor control system protects the unit from operating outside normal conditions. It transmits alarm signals upon reaching critical parameter values to shut down the compressor before damage occurs.

Setpoints:

Low inlet gas temperature
High discharge temperature
Low oil temperature
High oil separator temperature
Low oil injection temperature
High oil injection temperature
Low suction pressure
High discharge pressure
Pre-lube oil pressure
Low oil pressure
High differential oil filter pressure at start-up
High differential oil filter pressure during operation
High motor current

The above-mentioned limit values should correspond to the process requirements and not necessarily the compressor's design limitations. Pressure and temperature can vary significantly depending on the application. The VSG compressor is designed for a wide range of applications. Minimum and maximum limits are indicated for each alarm value, but specific values should be determined for each installation.

Application Guidelines

For normal operation of the VSSG/VSG compressor, follow the recommendations below.

Proper lubrication is crucial for VSG compressor operation. The oil supplied to the compressor absorbs and removes heat of compression and seals the gaps between the rotors, while also lubricating all moving parts. Therefore, select oil with the appropriate viscosity and constantly monitor the oil supply. Use an auxiliary oil pump if necessary. The oil must be compatible with the process gas to prevent thinning and viscosity reduction. Oil must also be filtered to remove particles down to 25 microns to ensure only clean oil enters the compressor. Consult with Vilter representatives to select the correct oil and oil pump.

Monitoring the oil injection temperature is critical for normal unit operation. The oil temperature should be 15-20°C above the dew point of the gas mixture to prevent condensation or liquid entering the compression chamber.

Gas composition is also important for VSSG/VSG compressor operation. While the VSSG/VSG compressor can handle a wide range of gases, if hydrogen sulfide is present in any quantity, special oil additives are required to protect the compressor from corrosion. Less than 100 PPM of hydrogen sulfide does not affect the standard warranty conditions.

Typical gases: natural gas, landfill gas, carbon dioxide, propane, helium, propylene, and ammonia. Other gases require consultation with Vilter.

Compressor Performance and Design Limitations - Standard Models

Description	VSG 301	VSG 361	VSG 401	VSG 501	VSG 601	VSG 701	VSG 751	VSG 791	VSG 891	VSG 901	VSG 1051	VSG 1201	VSG 1301	VSG 1551	VSG 1851	VSG 2101	VSG 2401	VSG 2601	VSG 2801	VSG 3001
Rotor Diameter (mm)	195	205	205	240	280	310	312	350	401	216	225	240	252	268	280	289	300	298	310	312	331	350	368	388	400	411	416
Gaterotor Diameter (mm)	216	225	225	240	268	280	289	300	298	310	312	331	350	368	388	400	411	416	401	411	416	401	411	416	401	411	416
Max. kW at 3600 rpm*	224 kW	373 kW	503 kW	1491 kW	503 kW	746 kW	1491 kW	224 kW	373 kW	503 kW	746 kW	1491 kW	1491 kW	1491 kW	1491 kW	1491 kW	1491 kW	1491 kW	1491 kW	1491 kW
Max. allowable torque (N-m)	602 N-m	1002 N-m	1353 N-m	4011 N-m	1002 N-m	2005 N-m	4011 N-m	602 N-m	1002 N-m	1353 N-m	2005 N-m	4011 N-m	4011 N-m	4011 N-m	4011 N-m	4011 N-m	4011 N-m	4011 N-m	4011 N-m	4011 N-m
Rotor speed (rpm)	1200-4200	1200-4000	1200-3800	1200-4200	1200-4000	1200-3800	1200-4200	1200-4000	1200-3800	1200-4200	1200-4000	1200-3800	1200-3800	1200-3800	1200-3800	1200-3800	1200-3800	1200-3800	1200-3800	1200-3800
Rotation direction	Counter-clockwise, viewed from shaft end	Clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end	Counter-clockwise, viewed from shaft end
Drive type	Direct, electric motor, gas engine
Volume ratio	1.2 to 7.0 (Automatically regulated or manually controlled)
Capacity regulation	10% to 100% (Automatically regulated or manually controlled)
Max. allowable working pressure (barg)**	36	33	76	22	33	37	36	33	76	22	33	37	36	33	76	22	33	37	36	33
Max. differential pressure (barg)***	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22
Min. inlet temperature (°C)	-46°C
Max. inlet temperature (°C)	82°C
Max. discharge temperature (°C)	107°C (Contact Vilter if limits are exceeded)
Max. Oil Temperature (°C)	88°C (Contact Vilter if limits are exceeded)

*Higher maximum values are possible. Consult Vilter Manufacturing LLC.
**Higher discharge pressures are possible. Consult Vilter Manufacturing LLC for agreement and confirmation.
***Higher differential pressure values are possible. Consult Vilter Manufacturing LLC for agreement and confirmation.
Note: Safety valve settings must be below the maximum allowable working pressure. Typically 10% lower than maximum allowable.

VSG Compressor Dimensions and Outline

Models VSG 301-701

Models VSG 301-701 shown with standard C-Flange electric motor, single oil filter, and standard water-cooled oil cooler, designated as "D" in the drawings. Note that all VSG models can be configured with single or duplex oil filters, and with frame-mounted or separate oil coolers.

Models VSG 751-3001

Note that all VSG models can be configured with single or duplex oil filters, and with frame-mounted or separate oil coolers.

VSG Outline Dimensions

Vilter Model	Inlet	Outlet	A Length (mm)	B Width (mm)	C Height (mm)	D Optional Oil Cooler (mm)	Approx. Weight (kg)**
VSG-301	76 mm	76 mm	2692 mm	1270 mm	1829 mm	2153 mm	3175
VSG-361	76 mm	76 mm	2692 mm	1270 mm	1829 mm	2153 mm	3311
VSG-401	76 mm	76 mm	2692 mm	1270 mm	1829 mm	2153 mm	3402
VSG-501	102 mm	76 mm	2667 mm	1118 mm	2286 mm	3067 mm	3856
VSG-601	102 mm	102 mm	2997 mm	1219 mm	2388 mm	3067 mm	3992
VSG-701	102 mm	102 mm	2997 mm	1219 mm	2388 mm	3067 mm	4082
VSG-751	152 mm	102 mm	3658 mm	1092 mm	2438 mm	4877 mm	6713
VSG-791	152 mm	102 mm	3658 mm	1092 mm	2438 mm	4877 mm	6713
VSG-891	152 mm	102 mm	3658 mm	1092 mm	2438 mm	4877 mm	6895
VSG-901	152 mm	152 mm	3658 mm	1092 mm	2438 mm	4877 mm	6895
VSG-1051	152 mm	102 mm	4013 mm	1245 mm	2642 mm	4877 mm	7031
VSG-1201	152 mm	152 mm	4013 mm	1245 mm	2692 mm	4877 mm	7257
VSG-1301	152 mm	152 mm	4013 mm	1245 mm	2692 mm	4877 mm	7257
VSG-1551	152 mm	203 mm	4572 mm	1727 mm	3048 mm	5182 mm	8165
VSG-1851	152 mm	203 mm	4572 mm	1727 mm	3048 mm	5182 mm	8255
VSG-2101	152 mm	254 mm	4572 mm	1727 mm	3048 mm	5182 mm	8391
VSG-2401	305 mm	203 mm	5283 mm	2235 mm	3454 mm	5182 mm	8618
VSG-2601	305 mm	203 mm	5283 mm	2235 mm	3454 mm	5182 mm	8618
VSG-2801	305 mm	203 mm	5283 mm	2235 mm	3454 mm	5182 mm	8709
VSG-3001	305 mm	203 mm	5283 mm	2235 mm	3454 mm	5182 mm	8845

*Dimensions are approximate and should not be used for design purposes.
**Weight of standard and installed electric motors may vary.

VSSG Compressor Specifications and Design Limitations - Standard Models

Description	VSSG 291	VSSG 341	VSSG 451	VSSG 601
Rotor Diameter (mm)	240	240	240	240
Gaterotor Diameter (mm)	220	225	225	240
Max. kW at 3600 rpm*	373 kW	373 kW	373 kW	373 kW
Max. allowable torque (N-m)	1002 N-m	1002 N-m	1002 N-m	1002 N-m
Rotor speed (rpm)	1200-4200	1200-4200	1200-4200	1200-4200
Rotation direction	Clockwise, viewed from shaft end
Drive type	Direct, electric motor, gas engine
Volume ratio	1.2 to 7.0 (Automatically regulated or manually controlled)
Capacity regulation	10% to 100% (Automatically regulated or manually controlled)
Max. allowable working pressure (barg)**	22	22	22	22
Max. differential pressure (barg)***	-46°C	-46°C	-46°C	-46°C
Min. inlet temperature (°C)	82°C	82°C	82°C	82°C
Max. inlet temperature (°C)	107° (Contact Vilter if limits are exceeded)	107° (Contact Vilter if limits are exceeded)	107° (Contact Vilter if limits are exceeded)	107° (Contact Vilter if limits are exceeded)
Max. discharge temperature (°C)	88° (Contact Vilter if limits are exceeded)	88° (Contact Vilter if limits are exceeded)	88° (Contact Vilter if limits are exceeded)	88° (Contact Vilter if limits are exceeded)
Max. Oil Temperature (°C)	Higher maximum values are possible. Consult Vilter Manufacturing LLC. Higher discharge pressures are possible. Consult Vilter Manufacturing LLC for agreement and confirmation. Higher differential pressure values are possible. Consult Vilter Manufacturing LLC for agreement and confirmation. Note:** Safety valve settings must be below the maximum allowable working pressure. Typically 10% lower than maximum allowable.

Emerson Climate Technologies – 115114, Moscow, Letnikovskaya St., Bldg. 10, Str. 2, Floor 5
Tel.: +7 495 981-98-11 Fax: +7 495 981-98-16 Internet: www.emersonclimate.eu

2012VM-17 R3 (4/14) "Emerson" and "Vilter" are trademarks of Emerson Electric Co. or one of its affiliated companies. ©2014 Emerson Climate Technologies, Inc. All rights reserved. Printed in the USA. Vilter Manufacturing LLC reserves the right to make changes to the design and specifications without prior notice.

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