search.noResults

search.searching

dataCollection.invalidEmail
note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
Lube-Tech


Microwave Heating Process Industrial microwaves operate at 915 MHz which is different than the frequency of household microwaves operating at 2450 MHz. These waves carry an electric field and a magnetic field. At 915 MHz, the polarity of the waves changes 915 million cycles per second. Simplified, a di-polar molecule like that of water exposed to such change in polarity attempts to align its N and S poles with those of the magnetic field of the incoming waves. This results in the water molecules vibrating and colliding with each other resulting in frictional heat. The heat is then conducted throughout the product causing an expansion of the molecules. The expansion of the molecules further increases impacts resulting in faster heating. Polarity of mineral oils is different than vegetable oils and as a result microwave absorption is slower for mineral oils. But this has been remedied through the use of susceptors.


PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE


No.123 page 3


Improvements Aluminium or calcium greases tend to thicken up as soon as the reaction begins. This renders circulation alone useless and circulation leads to the creation of worm holes where hotter materials would find their way to the inlet of the pump from circulation jets. Without actively turning the thick product, the microwaves would superheat its top layers while leaving the products at the bottom of the vessel unheated. Figure 3 shows the inside of a reactor with mixing arms designed for turning the products.


Figure 3: Inside view of the new modified reactor with mixing arms


Figure 1: Microwaves with a Magnetic and an Electrical Field interact with a Dipolar Molecule


Figure 2: Two Waveguides from two 75KW Microwave Transmitters attached to top of the Grease Reactor


When applying microwaves to metallic vessels, arcing could occur if there are gaps between metal components where the waves could resonate. Also, a rotating metal shaft could act as an antenna and a conduit for the microwaves to escape from the shaft ends. A new design was incorporated that utilises mixing arms but overcomes the microwave seepage at the shaft ends through the use of chokes. Its design incorporated a means to prevent arcing as the paddles approach the surface walls of the vessel and form momentary narrow metal to metal gaps. Chokes refer to various ways to contain microwaves. The metal screen in front of the window of household microwaves is considered a choke without which microwaves could escape through the glass.


28 LUBE MAGAZINE NO.152 AUGUST 2019


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56