Bulk Bag System Design Considerations

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BBU Mix TankDesigning a new Bulk Bag Mix Tank Feed System? Here are some considerations during the design phase that will help meet expectations of plant managers and operators alike:

Gravity feed of solution or metering pumps:

Depending on the installation, solution/slurry from the mix tank can be gravity fed to process or if discharging into pressure, metering pumps will be required. Once you determine you need metering pumps there are different types. VeloDyne doesn't manufacture any pumps but has used various types over the years, the most common used in a bulk bag system application would be progressive cavity or hose pump styles.  

Volumetric feeder hopper capacity and type:

Some chemicals such as soda ash are hygroscopic and the intermediate hopper size should be minimized to reduce the possibility of moisture entering the hopper and contaminating the chemical.  Intermediate hopper capacities ranging from 2-8 cubic feet are available. 

Room Height and Equipment Layout:

A ceiling height of appx. 16.5 feet is required to utilize a 2,000 lb. bulk bag. Dimensions for bulk bags are not standardized, most bags are appx. 36” square. Considering the loading and storage area of the bulk bag equipment to ensure adequate space is available for fork truck or pallet jack movement for locating bulk bags under the hoist I-beam is key. Making previsions for the Main Control Panel (MCP) whether it is mounted to the bulk bag frame or wall mounted remotely, NFPA70E code requirements are space must be open the width of the control panel, then extending out from the face of the panel 36” for panels containing 120v or 42” for 480v panels.

Platforms:

A platform may be required for the operator to load the bulk bag discharge chute through the Iris valve into the intermediate hopper.  Height of the platform will depend on the hopper size and loading height desired.

Voltage:

Systems are available in several voltages depending on total hp requirement.  460 VAC/ 3 phase/ 60 Hz is typical.

Multiple power supplies:

A separate power supply is suggested for the bulk bag system and the solution/slurry pump(s).  This allows the operator to continue pumping solution/slurry while the power is disconnected from the bulk bag system for maintenance, etc.

Water supply:

Water capacity required is dictated by the desired solution concentration, mix tank capacity and desired tank fill time, 20 to 30 gpm is typical.  Minimum water pressure of 20 psi is required to overcome pressure drop of valves, spray nozzles, fittings, etc.  A booster pump is required if sufficient pressure is not available.  A pressure reducing valve is suggested if water pressure fluctuates or is higher than 75 psi.

Water Temperature:

Most chemicals will dissolve more rapidly in warm water.  Water temperature should not exceed PVC pipe and valve ratings depending on water pressure and temperature. 

Solution/Slurry Pump Flushing Provision:

BBU, Feeder, Tank, PumpsThe ability to flush out the pumps and solution discharge line is a great feature to have in order to reduce chemical build up (scaling) during maintenance or prolonged shut downs.

Safety Considerations:

  • Consult the chemical MSDS for proper handling and safety procedures.
  • A curb around the equipment will prevent chemical spills and leaks from entering the plant walkway.
  • A textured floor or grating may be advantageous in the loading area to reduce slip hazards.
  • A drain should be located in the equipment area to allow for wash-down in the event of a chemical spill and to contain pump or piping leaks.

The above considerations are not the only things that come into play when designing a system or multiple systems. If you start with these points you will be well on your way to designing a reliable bulk bag handling system that operators and plant managers will be satisfied with.