Eccentric screw pump

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Sectional view of an eccentric screw pump
Animation of the mode of action

Eccentric screw pumps , also called PCP (from English progressing or progressive cavity pump ), are pumps for pumping a variety of media, in particular thick, highly viscous and abrasive media such as sludge , slurry , petroleum and fats . It is also called the Moineau pump after its inventor, René Moineau , and is also called the Mohno, Moyno or Mono pump after the trademarks of the original licensees.

functionality

The eccentric screw pump belongs to the group of rotating displacement pumps. The main parts are a rotating part, the rotor , and a stationary part, the stator , in which the former rotates. The rotor is designed as a kind of round thread screw with an extremely large pitch, large thread depth and a small core diameter. The elastic stator has one more thread and twice the pitch length of the rotor. As a result, conveying chambers remain between the stator and the rotor rotating in it and also moving radially, which move continuously from the inlet to the outlet side. Valves to limit the conveying spaces are not required.

The size of the pumping chambers and thus the theoretical delivery rate depends on the pump size. A 360 ° rotation with a free outlet gives the volumetric delivery rate per revolution. The pump delivery rate can thus be changed via the speed. The actual delivery rate depends on the counter pressure that is set. The medium always tries to achieve a pressure equalization from high to low pressure. Since the seal between the rotor and stator is not static, the medium will always flow from the pressure side to the suction side. These “slip losses” can be seen from the characteristic curve as the difference between the theoretical and the actual flow rate. If the maximum permissible stage pressure is set at 6 bar and twelve-stage conveying elements are used, pressures of up to 72 bar can be overcome.

The shape of the cavities is constant so that the pumped medium is not compressed. With a suitable design, progressing cavity pumps can convey not only fluids but also solids. The shear forces that act on the conveyed material are very small, so that, for. B. whole fruits can also be promoted. A particular advantage is that eccentric screw pumps deliver continuously and with little pulsation, which makes them suitable for use in potting systems. Highly viscous and abrasive media can also be conveyed without any problems. They are also suitable as pumps with round plates at the end connection for emptying barrels.

The inventor of this pump technology is the Frenchman René Moineau (1887–1948), who applied for a patent for his invention in 1930 and founded the pump manufacturer PCM Pompes with Robert Bienaimé in 1932 and also granted licenses worldwide. The technology of eccentric screw pumps was also part of his dissertation in 1939.

scope of application

A wide variety of media can be conveyed gently and with low pulsation with the eccentric screw pump. The spectrum of media ranges from water to media that are no longer self-flowing. Since the delivery rate is proportional to the speed, the eccentric screw pump can be used very well for dosing tasks in conjunction with the appropriate measurement and control technology.

The progressing cavity pump system combines many positive properties of other pump systems: like the centrifugal pump , it has no suction and pressure valves. Like the piston pump , it has excellent self-priming capabilities. Like the diaphragm or peristaltic pump , it can convey any type of inhomogeneous and abrasive media, even mixed with solids and fibers. Multi-phase mixtures are also conveyed safely and gently by the eccentric screw pump. Like the gear or screw pump , it is able to cope with the highest viscosity of the medium. And like the piston, diaphragm, gear or screw spindle pump, it has a speed-dependent, continuous flow rate and is therefore able to perform metering tasks.

The eccentric screw pump can be used in all industrial areas in which special conveying tasks have to be solved.

environmental engineering

In environmental technology, progressive cavity pumps are primarily used in sewage treatment plants. The following list should show the variety of possible uses.

Municipal sewage treatment plants

Industrial sewage treatment plants

  • Pumping industrial wastewater: sludge from neutralization, FGD wastewater, gypsum suspension, activated carbon suspension, metal hydroxide sludge, acid sludge, oil suspension (from fat separators).
  • Disposal and recycling systems
  • Pumping of landfill leachate, fat and oil emulsion, solvent mixtures, centrifuge sludge from nuclear power plants , radioactive sludge, tar residues (TÖF), mixed sludge
  • Dosing of flocculants , acids, lye, ammonia water , milk of lime, metal salt solution, waste oil for incineration, thick sludge for drying and incineration

Drinking water treatment plants

  • Pumping calcium carbonate sludge, milk of lime, flocculants, flocculants, iron-manganese sludge, river sludge, drained sludge from filter presses

Civil protection

  • Pumping oil sludge, oil-water emulsion, waste water, solvent mixture, chemical mixture

food industry

In the food industry, highly viscous media such as syrup, quark, yoghurt and ketchup are pumped in the various low-germ processing stages. When pumping cream, the pumps run very slowly so that butter is not produced unintentionally. The progressing cavity pumps for the food industry are built in accordance with the relevant regulations and standards. They can be CIP cleaned and SIP sterilized (without dismantling). Here are a few examples of the wide range of delivery options for the progressing cavity pump in

bakeries

Conveying baking additives, egg mass, fat, yeast, dough, wholemeal dough

Meat and sausage factories

Conveying blood sausage meat, corned beef, meat porridge, foie gras, goulash soup , brine, lard

Fruit and vegetable processing and in the canning industry

Conveying applesauce, vinegar, fruits, vegetable puree, potato graters, fruit pomace, olive paste, pectin, syrup, cooking oil, tomato paste

Making butter and cheese

Pumping: butter, clarified butter, cheese mass, cooked cheese, herb butter, cream, raw milk

Milk processing

Conveying buttermilk, added fruit, yoghurt, kefir , milk drinks, quark, cream

In sweet juice factories and for beverage production

  • Conveying of mash and pulp , raw products, fruit, vegetable and fruit juice, nectar, whole stone fruits, frozen and chopped fruits, sugar solutions, syrups, concentrates, basic, coloring and flavoring substances and carbonated end products
  • Removal of the dry matter discharge from filtration systems through pipelines
  • Conveying washing water when cleaning fruits

Pasta production

Conveying egg, egg yolk, fat, liquid egg, noodle filling, dough, fruit fillings, nut and almond fillings

Breweries and malt houses

  • Conveying of undiluted spent grains, additionally dehydrated grains, mash , wet meal, wort, yeast (any kind), hot lees, decanted lees, diatomaceous earth thick sludge from the filters, beer in every production stage, washing water with paper residues, label glue, caustic soda, lime milk for water treatment and waste water
  • Loading of machines and systems for solid / liquid separation such as centrifuges, filter separators and presses
  • Removal of the accumulating dry matter through pipelines
  • Use for automatic yeast dosing
  • Use as beer blending pumps

Chocolate and confectionery production

Conveying ice cream, fondant mass, gelatine , glucose , cocoa mass, marzipan , nut paste, chocolate and wafer filling.

In viticulture and in wineries

  • Conveying whole grapes without loss of bouquet or CO 2 , including stems, must, trub wine, mash, pre-juiced mash, yeast and wine
  • Loading of machines and systems for solid / liquid separation, such as centrifuges, continuous presses and separators
  • Removal of the pomace or dry matter

Chemical industry

In the chemical industry , a wide variety of basic chemicals, semi-finished and finished products are promoted. Here, too, the eccentric screw pump is designed based on the properties of the pumped medium; additional safety regulations (e.g. Ex area) must often be observed. Eccentric screw pumps are used for the safe pumping and dosing of aggressive, highly viscous and abrasive products. The basic requirement is absolute security, whether in the field of chemical raw materials, cosmetics or pharmaceuticals, plastics production or in paint and varnish production. Harmful and dangerous substances, highly viscous, fibrous or sensitive materials require pumps that can also convey difficult media in hermetically sealed systems. But they shouldn't compromise on security. This is why progressing cavity pumps in the chemical industry convey and meter safely, gently and economically.

Plastics industry

Eccentric screw pumps are used to convey or meter liquid color and liquid additives such as flame retardants , antistatic agents , etc.

Paint and lacquer industry

Eccentric screw pumps are used to convey emulsion paints, printing inks, water-based paints, fillers, rotary printing inks, solvents, synthetic resin paints, etc.

Pulp industry

Eccentric screw pumps are used to convey pulp suspensions, e.g. B. wood pulp, sulphate, sulphite, rag and rejects, quarry, linters, kaolin, coating pastes in the processing plant or for charging the coating machine, starch, glue and paste, latex, lime slime, stearate, alum, melamine , chemicals such as Urea formaldehyde used.

Automotive industry

Eccentric screw pumps are suitable for conveying and metering: underbody protection, sealing compound, adhesive, wax, oil, grease, paint and varnish, paraffin. They are also used for windscreen washer pumps.

Papermaking

Oil production

If the use of conventional rod deep pumps does not seem appropriate, progressing cavity pumps are also used when pumping crude oil . These are either driven from the surface of the earth by means of a drive head and a screwable linkage or driven by a submersible electric motor located directly on the eccentric screw.

In reverse of the principle, eccentric screw pumps are also used as underground drives in drilling technology. The drive unit is attached directly above the drill bit . It is driven by the drilling fluid that is fed through the riser to the drill bit. The use of eccentric worm drives directly above the drill bit enables flexible guidance of the bore and thus the realization of directed bores.

In general, progressing cavity pumps are suitable for pumping crude oil, oil sludge, petroleum, heating oil, paraffin, dirty oil, as transfer pumps for crude oil, loading and unloading pumps for tank farms, oil sludge pumps for suction from collecting basins. They are used as feed pumps for filling stations or centrifuges.

Agriculture

In agriculture, eccentric screw pumps are installed as liquid manure pumps both for stationary use and for mobile use in liquid manure tanks. Pumping of slurry, biomass, vapor water, waste water from bioreactors, thickened sludge, pig feed, molasses, oil, fat.

shipbuilding

Pumping bilge water, faecal sludge, machine oil, waste oil.

Construction industry

Pumping cement suspension, bentonite, mortar, spray plaster.

Dosing technology

Dispensers based on eccentric screw pumps are used to dispense adhesives, silicones, sealants and many other media. Even the smallest dosing quantities from approx. 0.005 ml are possible. Because of the proportionality of the delivery volume and the angle of rotation, eccentric screw pumps are very suitable as dosing pumps in the packaging sector.

See also

Individual evidence

  1. ↑ Patent US1892217A : Applied April 27, 1931 , published December 31, 1932 , Applicant: Louis Moineau Rene Joseph, Inventor: Louis Moineau Rene Joseph. ‌
  2. ↑ Moyno in Russia . Retrieved February 27, 2014.
  3. ↑ http://www.herold-gefrees.de/de/drehkolbenpumpe/vorteilenachteile

Web links

Commons : Progressing cavity pump  - collection of images, videos and audio files