Temp. Monitoring Inside Rotating Assembly

[khan101]

Hello Forum,
We have a large number of disk stack centrifuges (Alfa Laval).
The feed containing the liquid and the solids is introduced to the rotating centrifuge bowl from the top via a stationary inlet pipe, and is accelerated in a distributor before entering the disc stack. The separation takes place between the discs.

The light phase moves through the disc stack towards the centre of the bowl, from where it is pumped out under pressure by means of a built-in paring disc.

The heavy phase is collected at the bowl periphery, from where it is continuously discharged through the nozzles. Filler pieces that avoid build-up of the sludge between the Nozzles can also be fitted.

A portion of the concentrated solids, discharged through the nozzles, can be recirculated into the bowl again through the recirculation inlet pipe, a separate distributor and the recirculation tubes. The bowl is mounted on a vertical spindle.

Now the problem is that these centrifuges are failing regularly. Some times when we put these machines on standby (without feeding them and on water only)the temp. gets too hot inside and as soon as we introduce feed (Hydrocarbon) there is a chance of explosion. There is no temp. indication for the inner bearing and we can not figure out how to install one (The whole assy. is inside the bowl which is rotating at 3600 rpm).
If any of you have any suggestion on how to measure temp. of the inner bearing, we will appreciate it.

Thanks.
p.s. For an illustration of how this thing works please click on the link below:

http://www.alfalaval.com/ecoreJava/...?siteNodeID=5427&contentID=28077&languageID=1

 

[m777182]

There are two problems: to obtain information about the temperature of the bearing and to control the temperature inside the centrifuge.
The first problem should be and will be solved by Alfa laval.
The second one is due to a hihg power input that is delivered to your centrifuge and is almost entirely converted into heat.The eficiency of separation is proportional to the energy input.You cannot insert some sort of heat exchanger inside. Again contact Alfa laval and they will deal with the problem. In the meantime you can insert T sensors into the inflow and outflow to monitor T; you can add a water cooler into a feedback line although it would not be very effective because only a small portion of the flow is fed back;perhaps you can use some protective athmosphere(CO2,N2) or you could deduct heat from the walls of the centrifuge from outside with a cold air blower.The problem is similar to a colloid mill where heat is removed by water cooling jacket.
m777182

 

[CMfgE1]

Short of saying there is no way to do it.............
I would concentrate on monitoring the vibration, rpm and amperage of the system. The seperator should be overhauled at least once a year depending on use. Also do you CIP (clean in place) your seperators? These units require clean at very regular intervals. Normally what happens is the build up will cause excess temperatures and your bearings and disk will burn up. I work for a company and we have several alfa lavals as well. We are constantly overhauling (because of use) and maintaining these units. I am curious as to why you are recirculating the solids. I would check with Alfa Laval on that. I wouldnt recommend it but not sure of your situation. The solids could be causing you problems with the unit plugging up.

Post some more info on what your separating and I also look into where you can insert a thermocouple or rtd for measuring. Also I assume your talking about the bowl bearing.


Good Luck

Quote: "Its not what you know, its who you know" - anybody trying to find a decent job