Magnetic couplings for hydrocarbon pumps

NMB magnetic couplings as solution for extreme operating conditions

KeyVisual_CaseStudy_NMB.jpg
Situation

Modifications of several units in a German refinery as part of the TMC (total monomer concept) process

Challenge

High pressure, extremely high torque, high power rating and highly flammable medium

Solution

Magnetic coupling by EagleBurgmann Nova Magnetics

As part of the TMC (total monomer concept) process, modifications were made to an ethylene cracker and a new olefin conversion unit (OCU) was built to boost ethylene and propylene productivity at a German refinery. During the course of this project, EagleBurgmann was awarded a contract to provide hermetic sealing for four multistage vertical can pumps. The pumps are used to circulate highly flammable liquid hydrocarbons (C2 and C4).

Magnetic couplings have several advantages in this type of application. On the one hand, they seal hermetically and there is no need for an external supply system. On the other hand the coupling only require minimal maintenance, and they are extremely low wearing. However, the application represents a signficant challenge from the engineering and materials point of view (e.g. the can on the coupling). The requirements profile includes high pressure, extremely high torque, high power rating and a highly flammable medium.

Initially, an NMB 22P-8R-65-ND2 was used, but it became apparent after only a few starts that a coupling with a higher power rating was needed. The sealing function did however remain intact at all times.

The reason was high torque which resulted in a break-away of the magnetic coupling between the rotating outer rotor (connection to the motor) and the synchronous inner rotor (connection of the impeller). Strong vibration and elevated temperatures were evident in the can.

An identical magnetic coupling which started gently with the aid of a frequency converter was provided as an interim solution, and it worked satisfactorily (startup profile: 0 ... 2,980 min-1 in 60 s).

NMB Model_006.tiff

EagleBurgmann Nova Magnetics designed a new magnetic coupling with a significantly higher power rating, which supports direct start and provides a more efficient and reliable solution. The coupling withstands high pressure at high rotational speeds and high torque without problems. Hastelloy (which has high strength and low electrical conductivity) was used for the can in place of 1.4571 to minimize eddy current losses and increase the efficiency and safety of the coupling. With this design, torque was increased by 63 % and eddy current losses were reduced by 35 %.

MAK66_01.tiff

Magnetic couplings offer distinct advantages compared to other sealing systems: they are hermetically sealed, require little maintenance and help suppress vibration. For high drive power applications (>75 kW), EagleBurgmann Nova Magnetics developed a special can which continues to operate extremely efficiently at high pressure and speed (only around 2 % eddy current loses compared to 10 % on a conventional can). Lamination and electrical insulation between the layers reduce the generation of eddy currents, increasing efficiency. Engineers can provide solutions which ensure safe and cost-effective sealing and operation on large pumps.

CaseStudy_Grafik_NMB.jpg

Illustr.: Yellow parts = rotating, blue = stationary, gray = housing

  • Medium: hydrocarbons C2 and C4
  • Temperature: -32 °C und +40 °C (-25 °F ... +104 °F)
  • Pressure: 65 bar
  • Speed: 2,980 min-1
  • Drive power: 315 kW direct start
  • Design torque: up tp 1,700 Nm
  • Seal type: NMB 22P-10R-65-ND2 magnetic coupling
     
  • Can: Hastelloy, 1.4571, PTFE,
  • Inner rotor: 1.4571, neodymium iron boron
  • Outer rotor: carbon steel, neodymium iron boron
Contact us

Inquiry

for additional information about magnetic couplings

Show locations

Magnetic couplings for hydrocarbon pumps

Download the solution flyer

PDF download - 528.2 KB

Further reference projects

KeyVisual_CaseStudy_AGSR_Schaufeltrockner.jpg
Germany

Clean sealing solution for demanding crystal production

Seals are a risk factor in the production of liquid crystals. If there is even the slightest contamination of the liquid crystals, this will later affect the image quality of the display. Read on to see which sealing solution Merck KGaA uses in paddle dryers for the production of liquid crystals.

Read on for the entire case study
KeyVisual_CaseStudy_SHFVI_Finland
Finland

Does not blow off steam

A boiler circulation pump in a power plant conveys very hot and pressurized water. The pump has no cooling jacket, which increases the risk of a thermosiphon effect.

Read on for the entire case study
KeyVisual_CaseStudy_HSMR_Rührwerk
Belgium

Robust component in ensuring sterile vaccine production

In the highly sensitive production of vaccines, only a few barrier media and materials are approved for mechanical seals. If steam condensate is to lubricate silicon carbide sealing surfaces, premature wear is inevitable. How it actually does work is demonstrated by the case of an internationally operating pharmaceutical company.

Read on for the entire case study
CaseStudy_DF-SeccoMixR_Mobilbehälter_3
Belgium

Rotates silently and unobtrusively

Sealing the agitator shaft of a mobile vessel is a very special task when dealing with a process in vaccine production. Liquid lubricated seals offer the best conditions for this application. However, the operation of dry contacting seals is more convenient and just as reliable as it is safe.

Read on for the entire case study
KeyVisual_CaseStudy_DF-H75VN_Cooling-pump
Saudi Arabia

Saving the day

A chemicals company in the Middle East uses the refrigerant R134A-Freon in the production of toluene diisocyanate (TDI). Shortly after the refrigeration plant is commissioned, the seal of a magnetic coupling pump fails. Quick help was called for.

Read on for the entire case study
KeyVisual_CaseStudy_SeccoMixR_Schaufeltrockner_GB
United Kingdom

Service life of three years and more

Barrier fluid for seals is a risk factor in the pharmaceutical industry as it could contaminate the active ingredients produced. A globally active company is playing it safe and replacing liquid lubricated mechanical seals in paddle-wheel dryers with dry-running mechanical seals.

Read on for the entire case study
Show all references
Newsletter

Excellence in Practice

With our free e-mail newsletter „Excellence in Practice“, you will receive first-hand information about current products, services, references and worthwhile industry insights.

False