19.05.2008 | Editor: Dr. Jörg Kempf
What’s happening in terms of vacuum pumps? PROCESS has tracked down the current trends and latest developments. And one thing’s for sure: Producing “empty spaces” is and remains attractive.
Using vacuums ranks as one of the traditional interface technologies. Vacuums are used in industry and commerce for packaging, drying, suction and pick-and-place. Some process engineering operations are carried out in a vacuum because low pressure is an advantage on temperature-sensitive products. And in a vacuum column, it is even possible to split azeotropic mixes.
But first, you have to create the vacuum: And this is where the vacuum pumps come in. However, it’s worth clearing up a few key questions right at the outset. What volume of what end-pressure needs to be achieved, and in what time? Are there application-specific parameters which need to be taken into account? And what compression principle is best suited for a specific application? Answering these questions requires a wide variety of solutions. Rapidity and performance capability, speed and quality of processes are decisively determined by the sources used in creating the vacuum, i.e. by the manner in which the vacuum is created and controlled. That is good news for those manufacturers offering the broadest possible product range.
The most important area of applications for vacuum engineering is in the semiconductor industry, which accounts for around a 40 percent share. Chip manufacturers work in a high-vacuum range of between 10–3 and 10–7 mbar. It is only in this pure atmosphere that 100 percent circuits can be manufactured during doping. Amongst relatively new users, mention can be made of the solar section, currently enjoying an international boom, with its hunger for wafers as the carrier material in the production of modules. The sector for surface coatings and finishes has, to date, enjoyed a share of just under nine percent of the total vacuum technology market.
Pfeiffer Vacuum states that it is primarily rotary vane pumps, Roots pumps and dry pumps which are used for rough and medium vacuum applications. Turbomolecular pumps are employed to produce a high and ultra-high vacuum. Turbopumps—the key product group at Pfeiffer Vacuum and “invented” by that company—are available in a range of options: From the smallest and most compact pump in the world, with a suction capacity of 11 l/s, for the analytics industry, through to the large 3000 l pump used primarily in the coating and semiconductor industry.
The Korean company Dongbang manufactures dry screw vacuum pumps in the EVAP series. The company emphasizes that its patented, unique design with directly internally water-cooled screws offers particular advantages in chemical, petrochemical and pharmaceutical applications (evaporation, condensation, freeze-drying, distillation, deodorization, degassing, absorption, impregnation). Hermetic has exclusive responsibility in many European countries for marketing, repair and servicing of these vacuum pumps. The pump works as follows: The EVAP is a single-stage, dry-running screw vacuum pump with a contact-free mode of operation. Two screws, arranged in parallel, rotate in opposite directions, with cut timing gears positioning the screws relative to one another. A defined clearance is maintained between the rotors and between the rotor and the housing. The pumping chamber is an oil- and water-free design. The drive power is transferred to the driveshaft via a coupling. All parts coming into contact with the gas are corrosion-protected using a special coating. The design, with cooling water in the screw interior, exhibits the following advantages: no heat expansion on the screws; no warm-up phase to achieve the final vacuum, and low surface temperature.
One interesting area of application for vacuum pumps is in biofuel production. This is true of both first- and second-generation biofuels, as Dr. Marinella Varallo, Edwards General Manager Industrial Sales explains: “Edwards vacuum equipment can supply the full starting material for first- and second-generation for methanol recovery and purification of ethanol.” That includes traditional fluid ring pump technology and dry-running pumps from the CDX range for producing biofuels. There are considerable advantages to using the CDX range, fully in line with the ideas behind the biofuel industry: lower energy consumption, no consumption of water, and in addition to this they also require less space. Edwards offers systems which do not compete for water and energy in biofuel production.
The NT series of chemical vacuum pumps is setting new standards in performance, quietness of operation, ease of servicing and design, according to Vacuubrand. At the same time, they achieve the robustness and reliability of the predecessor models—even in demanding applications in the chemicals and pharmaceuticals industries. The range is rounded off with vacuum systems and chemical pump stands with electronic vacuum control using the CVC 3000 vacuum controller.
The screw rotors on the S-VSI Twister from Gardner Denver, with their contact-free operation, are making lubrication of the working chamber a thing of the past. In other words, no costs incurred for disposing of contaminated oil. The optimized screw rotors have a variable pitch and are synchronized using a system of gears. Other features of this new innovation emphasized by the manufacturer are the short evacuation times, the low compression heat, the high maximum tolerable water vapor inlet pressure and the good suction capacity. When it comes to profitability, the high efficiency level and variable speed are significant. The final vacuum achieved by the pump is 0.1 mbar.
Dry-running vacuum pumps for rough and medium vacuum range play an important role in research, laboratory work and industry. In all these areas, Ilmvac diaphragm pumps are used. The company claims that, with the range of types it has available, it can always offer a solution which is optimized in terms of suction capacity and final pressure, whilst also being economical. Diaphragm pumps are available in different materials finishes for chemical and physical processes, with regulated or non-regulated under-pressure, and with suction capacity from 0.3 to 16 m3/h and final pressures from 75 to <1 mbar. Atex-compliant versions are also available.
Busch has launched two complete series of liquid ring vacuum pumps onto the market. Dolphin pumps are available in a single-stage version in a modular design (Dolphin LC) and in single-stage or two-stage versions with base plate (Dolphin LA and LB). These new liquid ring vacuum pumps cover suction capacities from 25 to 5100 m³/h. Dolphin vacuum pumps achieve a final pressure of up to 33 mbar. Given their robust design, these pumps are equipped for demanding continuous operation in applications for the chemicals, crude petroleum and pharmaceuticals industries.
Sterling Sihi similarly offers liquid ring vacuum pumps: The pumps are available in a single-stage and two-stage finish, with suction capacity of up to 12,000. In addition to the familiar advantages of liquid ring vacuum pumps, e.g. isothermal compression, an oil-free vacuum, low-noise operation and high flexibility in terms of applications, the company emphasizes the following features of the LPH-X series:
In April, Oerlikon Leybold Vacuum began supplying cryopumps produced at its Dresden plant with a suction capacity of 60,000 l/s, to a customer in India. This is a global first. The company’s information suggests that this capacity puts all other known high vacuum pumps in the shade. Cryopumps (Coolvac) are used for applications in vacuum coating engineering, in vacuum furnaces, in physical laboratories and, at present, also in space simulation. The cryopump exploits the physical effect that gases can freeze or be bound onto extremely cold surfaces. To that end, the cryopump creates temperatures down to below ten Kelvin (–253 °C).
Conclusion: Producing “empty spaces” remains attractive, and the market in vacuum components (globally at around US$ 4.5 billion) is growing year on year; over the period from 2004 to 2006 alone, at an annual rate of eight percent, according to Dr. Stephen Ormrod, spokesman for the International Statistics on Vacuum Technology (ISVT) working group. And similarly noteworthy: Almost half of this market volume is in Asia.
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