Expander-compressor is a unit used in process cycles to lower the temperature of gas and to increase the pressure of process gas due to operation of the compressor stage.
Expander-compressor units are designed to produce deep cold in natural gas preparation and treatment units, providing temperature difference up to 55°C.
In accordance with the temperature at the unit outlet, expander-compressors can be used:
- For cooling natural gas (2°C below zero)
- To extract fraction C5 + (to 30°C below zero)
- To obtain propane-butane fraction (to 80°С below zero)
- For low-temperature gas separation in production of olefins (to 153°С below zero)
Expander-compressors are used:
- For low-temperature preparation of natural gas as well as its cooling for subsequent transportation.
- For gas processing at gas treatment plants by low-temperature separation of heavy fractions from natural gas.
- For production of various technical gases (O2, N2, Ar etc.) in air separation plants by their low-temperature separation from air.
- In chemical and petrochemical industry, during production of olefins, ammonia, nitric acid, hydrogen etc. (low-temperature separation of different compounds in gaseous form).
- For production of liquefied natural gas.
- In cryogenic plants for obtaining low temperatures (liquefaction of various gases, helium recovery).
Depending on composition of natural gas, use of an expander-compressor allows extraction of target components including:
- methane fraction;
- ethane fraction;
- propane-butane fraction;
- BFLH (broad fraction of light hydrocarbons);
- stable natural gasoline;
- normal butane;
- isobutane
- isopentane;
- normal pentane;
- pentane-hexane fraction.
Our company has developed and commercially produced expander-compressors with a capacity of 0.5 to 40.0 million m³/day at pressure levels up to 20 MPa.
In development of each new design, the latest achievements of science and technology, the latest technologies and new materials are used which allow reliable operation in any climatic conditions from arctic to southern latitudes.
Depending on initial parameters expander-compressors are designed and manufactured in several fundamentally different structural designs:
- With a low available differential pressure across the turbine (Pt <1.4) and correspondingly low (up to 10,000 rpm) rotational speed, expander-compressors with expander rotor on rolling bearings and simplified lubrication system are developed and manufactured. Implementation of high-precision rolling bearings made it possible to bring the maintenance-free life of the unit to 16 thousand hours;
- When high pressure drops (Pt > 1.4) and, correspondingly, high revolutions of the expander rotor are activated, units on sliding bearings or on active magnetic bearings are designed and manufactured. Five-segment thrust bearings and self-aligning (Mitchell type) thrust bearings are used as sliding bearings. Use of sliding bearings requires advanced lubrication and cooling system. An oil tank, pumps, filters, differential pressure regulators and other equipment are added to the expander design.
Implementation of SKF (S2M) active magnetic bearings completely eliminates the oil system, which significantly reduces the maintenance costs of the units and makes the units absolutely environmentally friendly.
Design of each expander-compressor unit takes into account specific operating conditions as well as process features of the plants operation. Units are supplied complete with piping, shut-off and control valves and automatic control system, in required climatic version.
Results of industrial operation confirm the effectiveness of expander-compressor units application as well as possibility of their use for natural gas preparation in gas-condensate fields with different gas-condensate characteristics and at different stages of operation, in particular, at the stage of declining production.
| Standard Size | Q 1 | Q 3 | Q 5 | Q 10 | Q 20 |
| Gas Flow, st.m³/hour | Up to 45 000,0 | Up to 125 000,0 | Up to 210 000,0 | Up to 425 000,0 | Up to 850 000,0 |
| Inlet Pressure, bar | Up to 209 | Up to 209 | Up to 209 | Up to 209 | Up to 209 |
| Temperature, °C | From -200°C to 280°C | From -200°C to 280°C | From -200°C to 280°C | From -200°C to 280°C | From -200°C to 280°C |
| Bearing Type | AMB or SB | AMB or SB | AMB or SB | AMB or SB | AMB or SB |
| Compliance with API 617 (Yes/No) | Yes | Yes | Yes | Yes | Yes |
AMB – Active magnetic bearing; SB – sliding bearing;
Turbogaz designs and manufactures such units individually for specific parameters of a particular technology, with consideration of proper climatic conditions.
We use the International Standards ANSI, API, ASME, DIN, ISO, GOST, DSTU.
