Rubber processing has a bizarre energy pattern, when seen from a layman’s perspective. Because you add heat into your process and then you cool down!
Heat addition and removal is repeated in each of your subsequent stages as well.
When you process rubber, energy is consumed across the value chain – right from transport of raw rubber, to the various processing operations (be it rubber mixing, rubber extrusion, rubber calendering, moulding etc) to convert into your suitable product and then transportation of your product.
This implies that you need to cool down your rubber processing machinery regularly, which simultaneously involves heat exchange from a hot medium to a cooler medium.
And the most common medium to cool is water.
But where there’s water, you will face water-related problems caused by its mineral deposits. These deposits could give you varying degrees of water-related problems that affect your operating efficiencies and/or even leading to more costly equipment downtime issues.
This could be in your Rubber Machinery like Mixer, Mixing Mill Rolls, Calender Rolls, Press, Extruder, Heat Exchangers, Moulds, and factory equipment like Boilers, Chillers, Compressors, and TCU‘s or other Ancillary Units, etc.
You would notice that the mineral deposits accumulate quickly regardless of screens or treatment actions adopted. Even a thin coating of water scale will act to insulate the water system’s surface and retard the transfer of heat.
Hence, scaling is the biggest problem affecting the heat transfer efficiency in rubber machinery.
To increase heat transfer efficiency, lower maintenance cost, conserve overall energy consumption and thus enhance the usable life of your machinery, removing scales in all your water-cooled or water-heated rubber and tyre equipment is very important.
In a simple rubber machinery like the mixing mill, the presence of scales on rolls leads to localized hot spots affecting your mixing quality. In the case of boilers, scales can be very damaging leading to even boiler rupture. When water scale, lime and rust deposits accumulate on the water side of chambers, rotors and the drop door of the Mixer, it causes temperature of your rubber stock to rise and gradually lead to a loss in production.
Different machinery has different safe and effective method to remove scales. Recently, I was shown an instruction sheet, from one of the descalers (RYDLYME), on the process to descale a rubber mixer that I found interesting.
Here’s the process reproduced. I hope you too find it informative.
- Take mixer out of service.
- Close water supply valve at header as shown in the sketch above.
- Drain all water from all sections of mixer.
- Connect Descaling Solution pump discharge hose to water header. Header usually supplies all circuits.
- Connect return hoses to drain lines from all circuits and place into the Descaling Solution receiver.
- Close water supply valves to gate and jacket circuits.
- Start pump and pump the descaling solution into rotors to purge the water from this circuit to sewer. When the descaling solution begins to discharge from this hose, return to the receiver.
- Open water supply valve to gate and maintain Descaling Solution circulation through this circuit.
- Open water supply valve to jacket and maintain Descaling Solution circulation through this circuit.
- If any circuit is NOT flowing properly, restrict Descaling Solution flow in other circuits until flow returns to normal in this circuit.
- Circulate a total of 120 Litres of Descaling Solution through all circuits of mixer until clean. This will require approximately four (4) hours pumping time.
- It is suggested to periodically rotate the rotors during Descaling Solution cleaning to assure that the Descaling Solution is in contact with all of the lobes of the rotor.
- Upon completion of cleaning, flush all Descaling Solution from all circuits with fresh water.
- Disconnect the Descaling Solution pump and all hoses. The mixer is now ready to be returned to service.
- Periodic descaling will keep the temperatures of the mixer within acceptable limits, assuring you a better product and minimize burnt or improperly mixed stock.
- Clean out the Descaling Solution System and store for future use.
Summarizing, scaling is the biggest problem with heat transfer efficiency in your rubber machinery. Descaling or cleaning the scales helps you fix this issue. Hence incorporating descaling solutions into your preventive maintenance program is recommended to keep your equipment running effectively and economically.
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