The Cryodynamics Division of Ebara International Corporation is proud to introduce our line of single phase and two phase submerged generator turbine expanders. Cryodynamics has developed the world's first site-proven variable speed, liquefied gas turbine expander and most recently, the first variable speed two phase Exducer expander.

At EBARA Cryodynamics, we look beyond traditional concepts to find new, innovative ideas that will meet our customer's needs. The development of the variable speed submerged generator cryogenic turbine expander and now the Exducer turbine are both prime examples of our commitment to providing the safest, most reliable products with proven performance for the liquefied gas industry.

The Cryodynamics cryogenic turbine expander is a radial inflow reaction turbine with an induction generator mounted on an integral shaft. The entire unit, including the turbine and generator is totally submerged in the cryogenic fluid. This design approach completely eliminates the need for dynamic seals, shaft couplings, generator support structure and any concern for possible misalignment between the turbine and generator. By eliminating possible leakage from rotating seals, the design is extremely safe, especially when hazardous fluids are being handled.

By using the technology and extensive experience from the proven Cryodynamics pump design, an extremely reliable and efficient turbine has now been developed. The submerged expander includes the same Thrust Equalizing Mechanism (TEM) as used in the pumps in order to balance the axial thrust loads over the operating range. By completely balancing the thrust loads, bearing life is increased dramatically.

For many years, the traditional method to let down pressure in a liquid stream used a Joule-Thomson (J-T) valve. An improvement in the overall efficiency of this let-down process can be achieved by replacing the J-T valve with a turbine expander.

With the installation of a turbine expander, an increase in overall process efficiency of approximately 5% can be obtained. In a typical LNG liquefaction train, additional LNG output is achieved through the enthalpy reduction of the LNG during the expansion across the turbine. The enthalpy reduction of the LNG reduces the boil-off losses and increases the LNG mass output for the same mass input. A typical expander with a 1000 kW generator installed in an LNG pressure reduction stream can provide as much as 60,000 tons of additional LNG per year!

A typical design has a power generation potential of from 1.0 to 3.0 megawatts, and with an expander efficiency of 80 to 88 percent, an output of 800 to 2640 kW can be realized. Over the course of a year, this totals more than approximately 7,700,000 kilowatt-hours, and at a cost of about $0.07 per kilowatt-hour, more than $500,000 of power is produced per year.

The design used by EBARA Cryodynamics can be supplied with variable speed technology together with fixed inlet vane geometry. By introducing variable speed technology to the application, the efficiency of the turbine can be optimized over a wide range of flows and desired pressure reductions. This method enables automatic optimization of work transfer and performance to match changes in process conditions. At the heart of the system is the variable speed, constant frequency (VSCF) controller, which can vary the speed of the generator and expander to precisely match process conditions. At the same time, power is produced at constant frequency with unity power factor. The low harmonic sinusoidal output can then be fed directly back into the plant electrical system.

The Cryodynamics turbine expander can also be supplied without the VSCF for fixed-speed applications when only a small range of duty points is required. The expander and generator is identical to the variable speed unit, but is connected directly to the plant's power grid, operating at standard 50 or 60 Hz power at standard voltages.

The expander is installed inside a pressure vessel designed and built to applicable pressure vessel codes. The system is suitable for installation in hazardous area locations as required and defined by applicable codes and standards. In addition, EBARA Cryodynamics has the capability to fully performance test each turbine to simulate actual site conditions. Testing can be performed at full speed and full power with a variety of liquids such as LNG, LPG or LN2, depending on the temperature and specific gravity of the service fluid.