How does an aspirator(destoner) work?

[gogulashanth]

good day,
I am having trouble designing a destoner with an intergrated aspirator. hence I would like to know about the inner structure of a zig zag aspirator. thanks in advance.

 

[Baluncore]

What are you trying to sort? Are you removing a few stones from many seed. If so, they are separated based on aerodynamic drag and density. The use of a pair of sieves to select only particles with the size range of the seed will reduce the problem to one of density alone. Adjustment of the duct size or airflow can then be made to separate the densities.

Google; “zig zag aspirator”,
Or ask a more specific question.

 

[drragonx]

Aspirator design?

I need to remove dust from sesame seeds so i decided to make a zigzag aspirator. I have searched the net and found a bigger version but I need to make a smaller version. I have attached the picture. I need to know the inner layout of the top part (aspirator) A small sketch would be adequate. Btw thanks for taking ur time to reply.

 

[Baluncore]

Here is an example sectional drawing of a zig-zag aspirator, (on page 3).
http://www.kimseed.com.au/Seed Processing/Kimseed Zigzag Aspirator.pdf
Notice that it has a clear side so the operator can see the process in action and adjust the air vents precisely.

Stock is fed in at a controlled rate from a vibrating table at the top. You can make that table from a rubber mounted, gently sloping tray, with a small electric motor attached. The motor has a slightly unbalanced flywheel that gently vibrates the table and so stock creeps or walks into the zigzag column. The table and vibrator are mounted in a sealed cavity at the top of the machine to prevent loss of air at the top of the column.

Air is introduced near the bottom of the column at a calibrated volumetric flow rate. It flows up the zigzag column but some air escapes at each level so the volume is reduced progressively. The section of the zigzag column remains the same so the velocity of the airflow reduces up the column. At each zig or zag there is a mixing due to slight turbulence at the bend. That mixing tumbles the stock and so prevents clustering or clumping.

Now as stock falls down the column the free falling speed = terminal velocity of the particles is effectively compared with the speed of the rising airflow. If the particle is falling slower than the airflow in the zig below, it will stay at that level and eventually moves sideways into the hopper at that level.

Each hopper has a large section upper part with an adjustable air vent. Material will fall down into the bottom of the hopper because the air velocity in the upper part is slower than that in the column needed to reach that level.

By adjusting the individual hopper vents you divide the airflow to select various terminal velocities in the separator column that are close to optimum for your stock. That makes it possible to select a different component of the stock at each zag. It is possible that a clean separation may not be achieved. In that case the heavy and light hoppers will be clean but the intermediate will still be a mix. The intermediate mix can be reprocessed again several times, possibly with new stock, sorted on a gravity table or maybe discarded.

Now that you have a summary, you can ask more specific questions about the process.

 

[alphy]

An aspirator, also known as a destoner, is a machine used to remove stones, debris, and other foreign objects from grains, seeds, and other agricultural products. The inner structure of an aspirator typically consists of a series of zig-zag channels or air ducts that allow the product to pass through while using air to separate out the heavier foreign objects.

The process of separation in an aspirator is based on the principle of differential air pressure. As the product passes through the channels, a fan or blower creates a high velocity air stream, which causes the lighter particles to be carried away and separated from the heavier particles. The heavier particles, such as stones, fall to the bottom of the channels and are removed from the product stream.

The zig-zag design of the channels allows for multiple stages of separation, increasing the efficiency of the process. The channels are also designed to have a decreasing cross-sectional area, which helps to maintain the air velocity and increase the separation efficiency.

In an integrated aspirator, the destoning process is combined with other cleaning processes, such as sieving and air aspiration, to provide a more comprehensive cleaning solution. This allows for the removal of a wider range of impurities and ensures a higher quality end product.

I hope this information helps with your design process. If you require further assistance, I would recommend consulting with an expert in the field of agricultural machinery. They can provide more detailed information and guidance on the specific design and operation of an integrated aspirator. Best of luck with your project.