Different materials
Rotan pumps are available in many different materials, with or without heating jackets. When transporting toxic and environmentally hazardous liquids, the use of magnetically coupled ED pumps can be a very good alternative to traditional mechanical seal construction, as only minimal maintenance is necessary.
This especially goes for applications requiring the use of double mechanical shaft seals and support systems requiring regular attention or replacement. In this case, the life cycle costs for ED pumps are generally much lower than for pumps using double seals.
The Rotan magnetically driven pump has two unique design features which gives them maximum performance during liquid transfer.
One is the dynamic axial balancing system which minimise axial loads, energy use, and ultimately increases lifespan.
The second feature is a patented cooling system which is an internal pumping system, eliminating the need for external cooling.
Pumping raw material
Using an ED pump to pump chemical raw material such as isocyanate (Toluene di-isocyanate and MD), prevents serious implications for health, safety and environment (HSE).
At the same time life cycle costs are significantly reduced compared with traditionally sealed pumps.
Positive displacement (PD) pumps give a higher effectiveness as well as higher efficiency compared with other types of pumps when pumping high viscosity liquids.
Gear pumps, especially internal gear pumps perform best among all PD pumps in terms of efficiency, energy consumption, and maintenance costs. ROTAN's magnetically coupled (ED) pump, in particular is a solution to one of most hazardous problems of all pumps, namely the leakage problem.
Leakage-free option
The Rotan ED pump offers a leakage free option and environmentally friendly transfer of liquids with viscosity up to 10000cSt.
Isocyanate is one of the components in almost all foam products, such as foam mattresses, inner linings in cars, cushioning in car seats, chairs, and sofas. The hard qualities are used for the insulation of houses, machines and tubes.
There are various types of isocyanate, but common to all of them is that they react to the humidity of the air, thus forming very hard crystals which wear out the pumps and mechanical shaft seals. There are different methods to avoid this problem of humid air getting into storage tanks.
he tank is provided with a silica-gel filter which absorbs the humidity from the air as the tank is emptied and air is sucked into the tank, in this way the air in the tank is totally dry.
Another way of protecting the isocyanate from moisture is to have a protecting layer of gas (nitrogen) at the top of the tank.
Additionally the tanker which brings in the raw material, has got gas at the top of the tank. When filling the tank, the tanker pumps the liquid into the storage tank, the top of which is connected to the top of the tanker.
In this way, no air at all gets into the isocyanate, and no isocyanate vapour gets out in the environment. Instead of using nitrogen, ultra-dry air can be used, for example, by air-dryers which totally remove the humidity.
Systems pumping isocyanate should be provided with a filter or a strainer to avoid crystals, if any, to circulate in the system constantly.
All isocyanates are hazardous and the vapour should not be inhaled. Contact with the skin leads to discoloration and prolonged contact may result in allergic reactions.
Shaft seals of many different types have been used, from soft shaft seals to double mechanical shaft seals with DOP (dioctylphthalate) or mesamol under pressure between the seals.
The result have been mixed, but the risk of running into problems has been so high that it can only be recommended to implement these solutions it the customer takes the responsibility for the chosen solution.
Bronze bearings
Rotan always recommend the use of magnetically-coupled pumps for isocyanate. With regard to selecting bearings, the first choice should be bronze bearings. Some isocyanates, however, contain additives which do not go well with bronze, so must be rejected. The next solution is to put carbon bearings into the pump. But, if there are crystals in the isocyanate carbon bearings cannot be used. Here carbide bearings will be the only safe solution.
Normally the viscosity varies from 10 to 200cSt. The first magnetically coupled pump for isocyanate was sold in 1992. Since then, it has been running 24 hours a day, and has still not been opened - a period of almost 20 years.
Reduced life-cycle costs
Rotan's ED pumps are recognised by leading international and domestic manufacturers such as Bayer, BASF and Huntsman. The ED pumps effectively reduce the life cycle costs and increase relative usage life.
Underpinned by its performance stability and energy transfer efficiency, the ED pump holds a major future in the petrochemical, paint and coating business as well as the liquid pitch and tar industry.
Enter 23 or at www.engineerlive.com/epe
Dan Roldgaard is with Desmi Rotan, Norresundby, Denmark. www.desmi.com
