How does it control so accurately ?
By using the best components we can find and by clever software.
Three FMT hygienic flow
meters are used (one for each ingredient flow), and each one provides two sources of information to the PLC, namely the instantaneous flow rate (lph) and a pulse whenever a litre of product has passed through the meter. Accuracy is
excellent and the PLC's analogue inputs are calibrated to the flow meter signals during manufacture. High specification analogue inputs on the PLC allow resolution of flow rate to better than one lph. Generic high speed counter inputs on
the PLC ensure that flow pulses from the flow meters are all correctly counted and analysed. High positioning accuracy Samson control valves are used with high resolution analogue output channels to very accurately control the valve
position and hence, the individual flow rates.
How is the cream flow controlled?
In an innovative way
In the case of the Cream flow, a PD (positive displacement or lobe type)
pump is used, while standard centrifugal pumps are used on the Concentrate and Skim pumps. As it is not possible to close a control valve against a PD pump, and inverter speed control of the motor would not give sufficient accuracy, two
Samson valves are used on the Cream flow, one controlling the forward flow, the other controlling the "spill back" flow. These are controlled by one analogue output and the valves are arranged so that one opens while the other
closes and vice versa.This arrangement gives excellent accuracy and "turn down" ratios for the Cream flow, with flow rate control from 50 lph all the way up to 7,000 lph.
How about higher flow rate pasteurisers?
Initial design caters for this.
The flow rates and tank volumes quoted in this document
all relate to a pasteuriser with a flow rate of 9,000 lph and ingredient control valves and pumps are designed to match.
When designing for a pasteuriser with larger (or smaller) flow rates, these components would be designed
accordingly. The same control principles apply in all cases
How is the SmartMixer cleaned?
In one of two ways
In common with all
modern food equipment, the SmartMixer is designed to be cleaned on a CIP (Clean in Place) principle. The system has a CIP OPTION, which, when enabled, turns on the pumps, sets control valves in positions so that proper flow will pass
through all the lines, and cycles hygienic butterfly valves to ensure correct cleaning of the Buffer Tank and all delivery lines. Each installation will have different methods of cleaning the mixer, though in most cases it would be cleaned
when the pasteuriser cleans or be cleaned by a remote CIP
What about installation?
We can design and deliver the SmartMixer as a "standalone", skid mounted package that only requires electrical connection, or we
can design and install the whole thing as a "turnkey" project. Normally, we would have some design input into the installation, but this depends on the requirements of the customer
How do we know we can trust your calculations?
Check Us Out.
We have re-created the equation solving mathematics on a
spreadsheet, so if you would like to E_Mail us your product data we can then advise you how much of each ingredient stream you will need to create the batch. Obviously we can also do this as part of an on site presentation
Technical FAQ
Why use a Buffer Tank ?
Many reasons
There are a lot of good reasons for using a buffer tank. Initially, while the pasteuriser is
being started on water, the system primes the buffer tank with 800 litres of correctly mixed product. This is done so that base product pipework and valves can be primed and fully operational before the actual pasteuriser run commences. As
this operation works on a "litres passed" basis rather than on a "real time flow control" basis, it allows the operator time to sort out any air locking or valve problems. The system will only allow the "production
run" operation to start when the initial priming of the balance tank has been completed. The buffer tank also allows the operator some leeway when one of the base product streams fails, (eg. when a
tank goes empty). The product in the buffer tank is normally designed to give around 5 minutes of pasteuriser running time,even when no flow is being received from the mix system.
How is the Buffer Tank level controlled?
To always give an adequate liquid head
The PLC needs to know the design flow rate at
which the pasteuriser works. This is most important, as it needs to be able to calculate
the real time flow rates of the ingredient flows, and to control them accordingly. However, the pasteuriser flow rate will never be *exactly* the design flow rate and will vary depending on the product being produced. For example, pure Skim will flow faster through the pasteuriser than the thicker range of Cultured Products. The addition of thickening agents such as Guar Gum will also have an effect on the flow rate through the pasteuriser. Therefore, if the system continuously produced a flow rate equal to the design flow rate of the pasteuriser, then, depending on conditions, the Buffer Tank would either lag behind (and go empty) or produce too much (and overfill). This is obviously not acceptable.
To overcome this, the Buffer Tank is fitted with a level gauge which tells the PLC the height of the liquid in the Buffer Tank expressed as a % of the total tank volume. The PLC software then continuously monitors the liquid level
and calculates the total flow rate which the SmartMixer must produce to enable a sensible level of product to be maintained in the Buffer Tank. It then calculates the required flow rate of each of the ingredients and controls to that new
set point, ensuring that the volume ratios of the ingredients are always correct, regardless of the flow rate that it is producing. Normally, the system will be set up so that the Buffer Tank will run at 70% full (to ensure a good gravity
head) and would be configured to produce the design pasteuriser flow rate at this level. If the level falls, then the Mixer flow rate will increase, if it rises, then the Mixer flow rate will decrease.In practice, the system finds a
"balance point" where it is producing exactly the flow rate that the pasteuriser is requesting and the level is staying constant. This feature also means that it can cope with "Skim only" products such as Quarg.
What happens when something goes wrong?
There is plenty of warning
The SmartMixer has been designed to be as foolproof as
possible, as, once a batch is in progress and steady state conditions have been achieved, it is obviously best for the batch to run to completion. The PLC continuously monitors signals from all the electrical components of the plant and
will not let a batch be started if anything is incorrect. The HMI will tell maintenance staff if anything is incorrect. Once the batch is started and in "production run" mode, there are three "HOLD" modes which can
occur. When this happens, the operator is audibly and visually warned, the pumps stop, the valves close and the system "remembers" where it is in relation to the required batch. On resetting the HOLD condition, the system will
restart from the point where the HOLD condition occurred.