I will explain about Cyclone.
Cyclones have become famous for being tropical cyclones and vacuum cleaners.
Cyclones are also used as equipment in chemical plants, etc.
Although it is an analog facility, it is extremely effective when it is used.
You may be wondering how to design equipment that is a black box.
You can try a trial and choose the best one, but let’s explain a simple design method to reduce the number of trials.
Principle of Cyclone
Explain the principle of a cyclone.
Think of a cyclone as a mechanism that uses centrifugal force to separate two objects with different densities.
It has the following structure.
The contents of the entrance have the following characteristics:
- Solids mixed in liquid (rust, etc.)
- Gas mixed with liquid (mist, etc.)
- Gas mixed with solids (vacuum cleaner)
This is separated from the two exits using a cyclone.
In general, the upper side is the lighter density object, and the lower side is the heavier density object.
The inlet nozzle is connected to the tangential direction of the cylindrical barrel.
The contents entering the cylindrical body try to move downward in a spiral along the outer circumference of the cylindrical body.
At this time, the outer circumferential surface is balanced by the centrifugal force and the drag force on the outer circumferential surface.
The magnitude of centrifugal force is proportional to mass m, radius r, and angular velocity ω.
If you look a little more closely…
- Mass m is related to particle size and density
- Radius r is related to the size of the cyclone
- Angular velocity ω is related to inlet velocity and cyclone size
There is a connection.
Simply put,
Heavier objects move outward, lighter objects move inward.
I am using this relationship.
This is the same idea as a centrifuge.
The conical part moves downward in a spiral pattern, and eventually heavy objects are ejected from the bottom end.
The remaining light items are pushed out from the top.
A cyclone is a device that separates heavy and light objects.
a formula
We will introduce the generally known formula for calculating a cyclone.
This formula calculates the particle size that can be discharged by a cyclone.
$$dρ_c=\sqrt{\frac{9αβμQ}{πρv^2A}}(\frac{Y}{V})^{(2n)}$$
I don’t know what you’re talking about.
Let’s explain them one by one.
α・β
α and β are each coefficients.
α is the overflow ratio and β is the vortex center radius.
I have no choice but to think that this is what it is.
Use numbers around α=0.7 to 0.9 and β=0.7 .
μ・ρ
μ is the density of the light component and ρ is the density of the heavy component.
You need to be careful because you might make a mistake.
Q・v
Q is the flow rate at the nozzle inlet and v is its flow velocity.
v is related to centrifugal force, and the larger v is, the smaller the particle size that can be removed by the cyclone and the higher the performance.
However, the pressure loss will be higher.
A・V・Y
A, V, and Y are the dimensions of the cyclone.
The E dimension of the linear motion part is not included in the calculation.
The barrel should be large enough to connect the inlet nozzle, and does not need to be excessively long.
unit
The common units are m (meter), kg (kilogram), and s (second).
The results obtained are in units of m, but in reality we will discuss in units of mm.
pressure loss
Pressure loss is generally very low.
It is best to consider the sudden expansion and contraction of the nozzle at the entrance and exit.
Example of use
Here are some examples of how cyclones are used.
mist separation
Cyclone is used for mist separation.
Since it can be separated automatically and requires no maintenance, it is very useful when you want to do a small separation.
If you want to remove mist that cannot be removed even with a cyclone, consider another method such as a demister.
mechanical seal protection
Cyclones are used to protect mechanical seals.
It is also stipulated in the flushing plan.
In the case of a pump, the lighter component is a liquid, so the heavier component is limited.
For example, metals such as iron rust are preferable, but it often does not work properly with slurry systems where there is little difference in specific gravity.
Dust collection
Cyclones can also be used for dust collection purposes.
The area where powder is handled is collected using a blower, etc., but the idea is to install a cyclone in front of the dust collector to reduce the frequency of replacing the dust collector’s filter.
If automatic discharge is used, it must be installed on the secondary side of the blower, and air mixed with powder passes through the blower.
You may need to consider countermeasures against blower impeller wear.
reference
I’m wondering whether a design like a cyclone is piping or equipment.
The principle of considering the properties of gases, liquids, and solids remains the same, so you will probably learn this while gathering knowledge about piping.
Books such as the following may be helpful.
lastly
I explained about cyclones.
This is analog, maintenance-free equipment that separates liquids and solids from gases and solids from liquids.
Although the calculation formula is complicated and difficult to design, this is a facility that should be manufactured through trial and error.
If you get it right, the effect is tremendous.
Please feel free to post any concerns, questions, or concerns you may have regarding the design, maintenance, and operation of chemical plants in the comments section. (The comment section is at the bottom of this article.)
*We will read all comments received and respond seriously.