In many instances, in-line blending means the act of liquid processing in a pipeline as fluid is pumped from point A to point B. The equipment that handles this process is called a static mixer.
Static mixers mount inside a pipe and are installed after some pumping mechanism and fluids are mixed by way of direction change and flow division. Many companies that require in-line mixing and blending can simply install these units in the pipeline and call it a day.
Customized In-Line Blending Systems
More complex systems like Sonic Corp’s TechBlend Blending System help lessen labor requirements and reduce the costs associated with processing various liquids. Companies may lack the knowledge and engineering capabilities to design and fabricate their own sophisticated systems, however. For example, a customer of ours was making a blend of mostly miscible fluids in a large tank. This involved manually transferring fluids from totes to the tank. There were only four ingredients and it seemed to them that there must be a better way. They were right! They didn’t have in-house engineering specializing in equipment design and fabrication, so found Sonic Corp after a web search for “in-line blending” and “continuous mixing systems”.
It was apparent what needed to be done: raw materials, already coming in totes, would be placed on a custom built tote rack system. Level indication in the pipework leading from the totes to the system would trigger stack lights and alarms to alert operators of empty totes. The tote rack would accommodate two totes per ingredient to prevent stoppage as empty totes were replaced. A four-pump metering and blending system would then take the ingredients from totes and process them through a static mixer and fill totes of finished product on the output side of the system.
Many system fabricators try to create less expensive solutions that ultimately save on initial budget, but terrorize you later as the system fails you. For example, using a modulating valve with a turbine flow meter to regulate fluid flow is commonly used a cost saving metering solution. This method provides for a lot of flaws and process hiccups as fluid viscosity can be troublesome for turbine style flow meters so anything other than water would typically fail. The process controls for modulating a valve is less accurate than a PD pump with mass flow meter control. The valve positioners tend to be much less responsive and much slower in response time and you find a constant cat and mouse chase in your PID control loop.
Another common error in thinking is that centrifugal pumps can do it all, or that piston metering pumps are the best route. This is where pump selection is key. Sonic has over 50 years of experience in this field. You need pumps with predictable slip patterns and as near-to-pulseless flow as possible. This provides for the best accuracy and PID control.
Final System Design
Using 3D design in AutoCAD, we were able to illustrate to the customer how this could be done. Take a look:
This illustration shows the system design, the space required, etc. It shows the PD pumps selected and the mass flow meter technology used. It also shows the operator controls and locally installed PLC and VFD cabinets. Sonic was able to provide a complete design package inclusive of:
System P&ID drawing
System mechanical layout and design in 2D and 3D
System electrical design including cabinet panel layouts and wiring schematics
Component selection criteria
FDS for system automation and control
Overall, Sonic Corp’s design saved this company a lot of money and a lot of headaches. Labor involvement was reduced as material was made on demand directly from the source totes. Labor could be used in other areas of the factory now. Errors and waste were reduced because manual transfers were eliminated and replaced with the simple task of keeping full totes on the tote rack!