mylespetro
Member
Hey everyone,
I was on a customer's site on friday where they have a large bioreactor that they bought secondhand from a previous user. System is controlled by a SLC 5/04 and one of the feeds into the reactor is glucose. I'm not sure what sort of pump was used for the feed, but the customer has installed dosing pumps for most of the ingredient feeds. This has worked out pretty well for the most part, but the glucose is giving them problems lately.
The original control scheme was pump -> Coriolis flow meter -> pneumatic control valve -> bioreactor. Just to reiterate, I'm not sure what kind of feed pump was used in the original install. The new control scheme is the same, except they're sending a 4-20mA to the dosing pump (4-20mA = 0-30L/h) and have the control valve set to a certain percentage to maintain a little bit of back pressure on the line, keeping the Coriolis meter full. However, this has caused the loop to be unable to be controlled even in manual. If we set the dosing pump to 50%, the flow measurement (0-600g/m, don't love the mismatch in engineering units, but we've been unable to open the HMI file to edit it) can be anywhere from 150-300 g/m, and fluctuating +/- 50g/m. I think this is a combination of having the control valve closed off to maintain back pressure and the periodic nature of the pulse on the dosing pump going through the Coriolis meter.
I feel like ideally either the feed would be more of a constant flow and the control valve would regulate it based on the flow measured by the Coriolis meter, or you would just have an on/off valve (for isolation from CIP/SIP backflow into the line) and send the desired rate straight to the dosing pump and assume it's pumping the correct/desired amount, allowing it to pump freely into the tank. I just feel like a dosing pump on a Coriolis meter isn't an ideal setup, but I admittedly don't have a ton of experience in the biochemical processing world and was just curious what everyone else's thoughts are on this.
Thanks in advance!
I was on a customer's site on friday where they have a large bioreactor that they bought secondhand from a previous user. System is controlled by a SLC 5/04 and one of the feeds into the reactor is glucose. I'm not sure what sort of pump was used for the feed, but the customer has installed dosing pumps for most of the ingredient feeds. This has worked out pretty well for the most part, but the glucose is giving them problems lately.
The original control scheme was pump -> Coriolis flow meter -> pneumatic control valve -> bioreactor. Just to reiterate, I'm not sure what kind of feed pump was used in the original install. The new control scheme is the same, except they're sending a 4-20mA to the dosing pump (4-20mA = 0-30L/h) and have the control valve set to a certain percentage to maintain a little bit of back pressure on the line, keeping the Coriolis meter full. However, this has caused the loop to be unable to be controlled even in manual. If we set the dosing pump to 50%, the flow measurement (0-600g/m, don't love the mismatch in engineering units, but we've been unable to open the HMI file to edit it) can be anywhere from 150-300 g/m, and fluctuating +/- 50g/m. I think this is a combination of having the control valve closed off to maintain back pressure and the periodic nature of the pulse on the dosing pump going through the Coriolis meter.
I feel like ideally either the feed would be more of a constant flow and the control valve would regulate it based on the flow measured by the Coriolis meter, or you would just have an on/off valve (for isolation from CIP/SIP backflow into the line) and send the desired rate straight to the dosing pump and assume it's pumping the correct/desired amount, allowing it to pump freely into the tank. I just feel like a dosing pump on a Coriolis meter isn't an ideal setup, but I admittedly don't have a ton of experience in the biochemical processing world and was just curious what everyone else's thoughts are on this.
Thanks in advance!