7Dec 7, 2011
Interview with Patrick Esor, Sodimate, Inc. General Manager
What types of discharge systems are available for bulk products?
There are 3 main types of bulk discharge systems:
- The first one and the simplest one is vibration. In this system, bulk chemicals, or pellets contained in a container, bin, or hopper, are discharged by shaking the structure of the container with simple vibrators. Another type of vibration unloader quite commonly used is the bin activator. Instead of the vibrators’ being directly connected to the bottom part of the container, there is a bottom section (stand alone cone) separated by a rubber gasket were the vibrators shake only lower part of the container or the hopper in the area where the dry chemical as a tendency to bridge or arch.
- The second type of bulk discharge system uses air injection or fluidization instead of shaking or vibrating. As the name indicates, it uses pressurized air sprayed or injected into the container, generally at its base or at its cone depending on the shape of the container, to hydrate and fluidized the dry chemical. By injecting air, or compressed air, the dry chemical is aerated and discharged like a liquid.
- The third type of bulk discharge is the mechanical bin agitator or mechanical discharger. This uses an agitation device, the arch breaker, whose flexible blades are mounted on a single center shaft and rotate within the bottom of the container. The mechanical discharger gently agitates the powder within the bottom section of the container and allows for easy extraction.
What are the pros and cons of these dry chemical discharge systems?
Vibrators and bin activators
It is one of the cheapest systems to install as it simply requires adding a vibrator to agitate the product.
It is quite efficient with granulates and free flowing plastic material.
It is not very efficient with bulk products that are sticky or that react poorly to compaction. The best way to demonstrate this is to put wheat in a cup, knock it on a table a couple of times, and then turn it upside down. You will see that although some of the wheat will loosely fall, there is still wheat remaining at the bottom of the upside-down cup. This is the same principle that happens with the vibration of chemicals within a container/silo. The vibration compacts the product, increasing its density and preventing the dry chemical to discharge freely.
It is the cheapest system for a low discharge rate. But reaching high discharge rates, bin activators or vibrators can be expensive and inefficient.
The bin activator requires a gasket to absorb the vibration. This gasket comes in contact with abrasive and corrosive material, so it has a short life and needs to be replaced often. The cost to replace this gasket can be at least half the price of the actual bin activator unit itself.
The vibration shakes the attached equipment along with the container itself. This can be structurally damaging to the equipment and the connected equipment.
Most applications using vibrator discharge systems needs to be programmed with the downstream equipment and are rarely calibrated properly (screw feeder, screw conveyor, belt conveyor, rotary airlock, pneumatic transfer, etc.)
Air injection system or fluidization
It is quite easy to assemble and mount because most sites already have compressed air.
It is extremely simple, as the system is only composed of spray nozzles that are installed within the container and is controlled with inexpensive solenoids.
It works well with non-hygroscopic material, material which does not react with water or moisture, such as powdered activated carbon.
Air acts like water- instead of fluffing the dry chemical within the container it will find a way out, creating funneling. Regardless of the pressure you set for the air, it will always find the easiest way out.
Not all sites have compressed air available to use.
Some products are sensitive to moisture, and the injected air contains moisture; so air and/or oil desiccant is needed to make sure the compressed air that goes inside the container is completely dry. If not managed properly, moisture will come into contact with dry chemicals, such as quick lime or sodium bicarbonate or polymers, clogging the pores, nozzles and finally the injection system. This stops air from coming inside the silo.
Mechanical bin agitator or mechanical discharge
No vibration of the structure.
No need of compressed air.
No moisture is injected into the container.
Product is discharged efficiently even at high rates
Density of the material is not changed
Easily retrofitted onto old air injection and bin activator systems
Cheaper than air injection and bin activators for medium and high discharge rates.
It is difficult to operate when the container is full of dry product, as the device is turning inside of the container.
It requires a greater upfront expense than the vibration or injection system, although the long-term cost is competitive or advantageous compared to the other systems.
What is the competitive advantage of a Sodimate system?
Our main competitive advantage is that we guarantee a complete discharge of the container without vibration or air injection. We offer a great solution to avoid the disadvantages of those two types of systems. Our mechanical bin agitator gently agitates within the container or the silo. We do not change the density or the characteristic of the product by compacting or fluidizing it.
We have total control of what is being discharged compared to the other types of discharge systems, which can be inconsistent (eg. erratic discharge, segregation discharge)
We engineer multi-functional equipment that integrates uniquely designed screw feeder(s) and isolation systems, where other systems are only discharge systems.
The space requirement is much less for Sodimate’s mechanical bin discharger compared to the other discharge systems.
Our systems offer, with the same design, a wide range of discharge rates. From the small feed rate of a couple of pounds per minute to the larger rate of several tons per hour, our system is designed to easily accommodate rate variations without significant change in size or expense.
Our mechanical discharge systems are suitable for most dry chemicals- from low density pellets and powders, plastic pellets, or powdered activated carbon, to high density dry chemicals such as quick lime, soda ash, or cement.
It is the simplest retrofit/update that can be made to an existing system currently using vibration or air injection with a mechanical silo unloader. And our experienced engineering and installation team makes it an effortless process for your operation team to implement.