Pumping thin liquid PD pump 1

[bmw318be]

Pd pump is well known for pumping high viscosity 18000 cps.

How possible if we use pd pump to flush polymer with acetone that has viscosity 0.4 cp.

Are we able to calculate the slippage as the issue of pumping thin liquid is slippage which sould result in overheating the pump.

Would there be a problem in pumping acetone which has high temp of 110 degree c to flush the pipe and pump ? Will the slippage cause the acetone to evaporate before discharge .

 

[micalbrch]

What kind of PD pump do you use? Gear pump? Rotary lobe pump? Progressive cavity pump? Acetone has a boling temperature of around 55 °C at atmospheric pressure. So, it seems that in your process even the pressure into the pump is higher. How high?

To avoid overheating of the pump you can simply attach one or two temperature detectors to the pump housing. The pump manufacturer will tell you what the set point shall be.

 

[TD2K]

What sort of dP do you need across the pump?

 

[bmw318be]

Hi the pump is internal gear pump,The differential pressure is around 3.5 bars and My concerns is the slippage eould cause the acetone to evaporate instead of flushing out the polymer.

 

[Pumpsonly]

The viscosity would be too low for internal gear pump to handle. Check with the pump manufacturer about the material of construction is suitable for such low viscosity.

 

[Compositepro]

Your pump is not ideal for pumping acetone but there is nothing wrong with using an acetone flush to clean your system. This is a common practice with pumps used with thermoset polymers (acetone will not dissolve most thermoplastics). Sometimes compressed air can be used to push the bulk of the polymer out of the pipes before the acetone flush. This reduces acetone useage, but appropriate safety procedures are needed because compressed air will cause some sprayed polymer at the pipe outlet. Minor amounts of evaporation of acetone will occur, and perhaps boiling, but this is not a problem. Your work area must be electrically rated for flammable atmosphere.

 

[bmw318be]

Hi, would the toulene is more appropriate to flush the polymer than acetone ?. Yes the temperature would be a factor to be considered when pumping to flush . So u suggest to use compressed air to flush, what if the polymer has solidify in the pipe ?

 

[Compositepro]

Toluene can work, it depends on your polymer. If the polymer has cured in your piping there is little you can do except replace the piping or perhaps burn the polymer out with high temperature. If the polymer will melt, then melt it and blow open a flow channel with compressed air. Once there is an open channel a solvent flush can be used. The solvent flush can be done at room temperature and solid (not cured) polymer can be dissolved. Solvent will not open a plugged pipe unless the plug is very small. What is your polymer?

 

[bmw318be]

Hi Compositepro,thx for initial meaningful view, i do not have the actual info yet for actual polymer types. However,This is a Polymerization process with batches process  here the pump is useful in polymerization process. The Process is expected to handle different types of Polymer.

Process is started by adding polymer ingredient into a mixing vessel, the initial polymer viscosity is low Assuming it is 30 CPs, the solution is then heated up to a temperature of 120 degree C and agitator inside the Mixing Vessel is used to stir the solution. At this stage, I believe the polymer has becoming heated up and resulted in very low viscosity (Not sure how lower compared to initial CP of 30 CPs )
(assuming it is a closed loop) The pump will suck the polymer solution out of the vessel tank, and the it will then circulated to a heat exchanger which will cool the polymer, this will increase the cp of polymer to 20000 cp  and 60000 cp for Polymer A and PolymerB respectively. The polymerization will end after the final CPs reached .

Q1 : Should the heat exchanger before suction or after suction?

Q2 : Does the circulation happen just once, Meaning from elevated temperature of 120 degree C, we cool it down with heat exchanger, the polymer will be able to reach its final Viscosity of 20000 Cps ?

Q3:  Assuming the final Cps of PRODUCT A has reached 20000 Cps, the product will be transferred to another storage tank and new batch takes place. As the batch sequence ended, Probably Flush with Solvent is required, should we do it immediately before the Polymer cured in the pipe, I am not to sure if it is feasible to flush totally out after polymerization occurred. My two Concerns are

Q4: is  the PD pump has the ability to do the flushing of thin liquid Toluene which has 0.2 CPs , Slippage  is to be expected for such thin liquid  as pump is designed for high viscosity. It will cause the tolune to evaporate due to circulating the liquid back to the pump. As a result I was not able to flush out the residues.

Q5 2nd concern, the boiling Temp of the Toluene, I am not sure its boiling point is 110, however this would be a concern if my pumping temperature is 112 Degree C, cavitation of the pump could happened.?

Q6: Another hypothesis is to considerer the flushing of toluene has mixed up with the residual of polymer of 20000 CPs, so it become a compounded solution, so my assumption is the Toluene has greater Viscosity now which are above 0.2 CPs regardless the heated up Temperature of 112 Degree C, So Assuming it has CPs greater than 1 now, I hope The PD pump can flush out with less slippage now. I am sure this what has been practised in flushing out the polymer residual