Energy and Power

Power Stations

Vacuum pumps for hydrogen cooled generators

The generator is cooled with a hydrogen gas recirculation system using fans mounted on the generator rotor shaft. The heat absorbed by the gas is removed as it passes over finned tube gas coolers mounted in the stator frame. Gas is prevented from escaping at the rotor shafts by a closedloop oil seal system. The oil seal system consists of a storage tank, pumps, filters, and pressure controls, all skid mounted. Tuthill Kinney Rotary Piston Vacuum pumps have been running for years in the hydrogen seal oil application in power stations.

The vacuum pump is drawing air, water vapor and hydrogen gas from the seal oil tank. Tuthill Kinney KD 30 & KD 50 are the ideal pumps for the hydrogen seal oil vacuum systems.

Solar Industry

1st Generation Cell (Crystalline Silicon) Producing Polysilicon

Producing Poly silicon Solar grade silicon is produced in the reactors using metallurgical grade silicon by means of chemical vapor deposition (CVD) process. The process introduces silane gas with high temperature polysilicon rods inside a cooled bell jar. The silicon contained in the gas will deposit on the heated rods, which gradually grow until the desired diameter has been reached. The usage of a vacuum system is to evacuate the reactors prior to a chemical reaction taking place. Vacuum operating level for this application is anywhere from 0.5 to 1 Torr. Tuthill Vacuum & Blower Systems can supply either booster/piston systems, booster/vane systems or booster/dry pumping systems.

Once solar grade silicon is produced in the CVD reactors, it is then melted in the crystal growing furnace. The final product is called “Monocrystalline silicon ingot” has a round shape.

Polysilicon chunks placed into the Die-cast Furnace (Directional Solidification System) to produce “Multicrystalline silicon ingot” have a square shape. Our Booster/Air Ejector/Liquid Ring System with a max vacuum capacity of less than .1 Torr and Two Stage Rotary Piston pumps with a max vacuum capacity of .0002 Torr and full pumping speed below .1 Torr. Our pumps have been running for years in the production of monocrystalline and multicrystalline ingots. This process requires vacuum systems that work reliably in dusty environments as vacuum pumps will see silicon monoxide particles. The Operating vacuum is anywhere from 0.03 to 18 Torr, and some applications even higher. We can also supply dry running screw pumps for this application.

Once the ingots are produced, it goes to the wire saw machine. It is cut it into wafers by taut wire that runs through abrasive slurry (silicon carbide and glycol), which acts as the cutting agent between the work piece and wire. From an economic point of view this slurry is recycled and conditioned to gain 75% to 90% in pure form.

2nd Generation Cell (Thin Film)

Many thin-film devices are based on amorphous silicon alloys. Other thin-film devices are usually poly-crystalline materials. The fabrication of a thin-film solar cell involves depositing a layer of semiconductor material (such as amorphous silicon, copper indium gallium diselenide, or cadmium telluride) on a low-cost substrate, such as glass, metal, or plastic. Current deposition techniques can be broadly classified into physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) or some combination of them.

Vacuum pumps will see toxic, corrosive, explosive, pyrophoric and light gases such as hydrogen, Silane, helium, sulfur hexafluoride (SF6), Nitrogen trifluoride (NF3), phosphine, Germane, Boron Trifluoride and many more depending on process and technology. In addition, vacuum pumping speeds and rapid chamber cycling are essential. Our two stage vacuum systems meet the above requirement. Our systems equipped with NEMA control panel to operate on/off the system as well as safety interlocks for the system such as high oil temperature and high gas discharge temperature. Inert gas purge controls also provided to suit the application.

Since the thin film process & technology varies by each manufacturer, Tuthill can provide customize vacuum solution using single stage or multistage vacuum pumping systems under one roof at our ISO 9001 certified factory in Springfield, MO.

Encapsulation of Lamination of Photovoltaic Cells

Both 1st generation and 2nd generation photovoltaic cells are assembled and laminated using EVA (Ethyl Vinyl Acetate) encapsulant. It helps to hold together the top surface of PV cells and rear surface of the PV module. Tuthill can supply either rotary vane or dry screw vacuum pumps for this application. Typical vacuum requirement is < 2 Torr.

 

Landfill Gas Applications

Blowers are commonly used in landfill gas applications.

The cost of energy continues to rise and the means by which to produce it are becoming more expensive and coming under increased scrutiny for various reasons including the amount of pollution released in the process. At the same time, municipal landfills are exceeding capacity and uses are being made for the decomposing organic waste. One of those uses is converting landfill gas to energy. 

As the waste in a landfill decomposes, a form of natural gas is created, commonly referred to as Landfill Gas, (LFG). LFG is a mixture of methane and carbon dioxide along with some other non-organic compounds. The gas is gathered for various reasons, primarily for odor control and to prevent it from going into the atmosphere. 

During this process, blowers are used to help collect and move the gas. Generally the gas is gathered under a slight vacuum and discharged at around 5 psig into a header that feeds the landfill gas as a fuel to a special natural gas engine that drives the generators which actually convert it to electricity where the gas is used to power the landfill operations, sold to a local utility provider or even used to power certain types of vehicles. 

Which blower is the best fit?  This is a good application for the M-D Pneumatics, PD Plus model blowers. For outdoor installations the single envelope 81/57-series with internal labyrinth-mechanical seal on the chamber and the single-lip seal on the drive shaft would be recommended. If the blower is located in an  enclosed area, a double envelope 67/64 series blower with internal labyrinth-mechanical seal on the chamber and another mechanical seal on the drive shaft would be the best selection as it offers the lowest leak rate. These particular options are the best fit because they have low gas leak rates of 1X10-4 cc/sec per mechanical seal. Many of these applications require up to 5000 acfm which makes them a good application for positive displacement blowers given the low vacuum and pressure requirements in these systems.