Hi 

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I'm working on a design for a gas sparger in a water column, and so far I have not been able to really understand how to design this in correct way.

I have been reading a lot on sparger online (and in Perry hand book edition 7) but i have not fully understand how to get it to work like I want to.

I have attached some pictures of my test stand, this has the following specs:

1 water tank ø490mm (inside diameter).

1 inlet pipe for the gas (test stand it is air or nitrogen) ø33,7mm

Water height is 1,5m static water.

Outlet pipe is the same as inlet pipe.

The sparger is designed as a hole plate sparger - mounted on a box that is mounted on the inlet pipe and then submerged to the bottom of the tank.

The specs for the plate is a outside diamter of ø470

The specs for the gas is the following:

Inlet speed of gas/air is: 15-16m/s

Inlet pressure from the pressure regulator right now is around 1bar

Inlet pressure on the column when running 750lpm is 0,35bar (taken from the manometer)

Volume flow is up to around 50m3/hr or around 750 lpm

I want the outlet speed out of plate in bottom (superficial gas velocity) total out the sparger to be as low as possible, around 1m/s. 

Current plate is 1,64m/s -> this is 741 holes, ø3,5mm evely distrubuted in 13 lines (16 holes inner circle and 98 outer circle) 

Here is my problems that I do not know how to calculate on:

• How to get a even distrubution out of all the holes? Right now there is not, i have tried many thing larger holes, different sizes of holes etc. But i'm pretty sure this has something to do with the counter pressure of the sparger plate, and I do not know what i should aim for? So far I have just been testing different plates and patterns to get some understanding of the system. 
  Only calculating on the total area of all the holes. 
  The problem is, that at low volume flow only the inner holes are used, and even at the full load I do not see a even distribution out of all the holes.
• Second problem, I can see that the water level as a impact on the system, when the column is tilting forward must of the gas is coming out of the holes where the water level is lower. (less static pressure on top of these) 

So my question is, does anybody has some advice on how to calculate on such a gas sparger box with a plate on top, what parameters to I need to tweak on? 

Is the box design also something I need to look into? The size of this could have an impact on the amount of water that need to get pushed out before the gas is coming out of all the holes I assume? 

I'm trying to get this "small" scale to work, so I can make my larger water tank of a diamter of 1,5m - but right now I do fill confident enough to upscale my system and still believe I can get the distrubution to be on as much surface as possible.

Attached Files

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Edited by mikkelpoulsen, 12 September - 07:59 AM.

Spargers like this are often needed for bubble column reactors. See this reference for ideas, equations, and experimental discussion: https://www.scienced... (Chemical Engineering Journal, 15 September , Pages 173-186)

Your sieve plate will tend to favor the center in a level vessel due to the column hydraulics. Once the bubbles begin, the mixed fluid is less dense in that vertical column therefore the pressure drop is less so more bubbles flow into that region. Perhaps eliminating the center holes would help -- then your sparger is more like a ring. Consider whether using random packing inside the vessel would suit your needs. The packing should tend to redistribute the bubbles for a more even flow pattern. Consider also Bobby Strain's suggestion of using an eductor. A properly designed eductor would help thoroughly mix the air and water and probably reduce the bubble size as well.

Edited by Pilesar, 12 September - 12:25 PM.

Spargers like this are often needed for bubble column reactors. See this reference for ideas, equations, and experimental discussion: https://www.scienced... (Chemical Engineering Journal, 15 September , Pages 173-186)

Your sieve plate will tend to favor the center in a level vessel due to the column hydraulics. Once the bubbles begin, the mixed fluid is less dense in that vertical column therefore the pressure drop is less so more bubbles flow into that region. Perhaps eliminating the center holes would help -- then your sparger is more like a ring. Consider whether using random packing inside the vessel would suit your needs. The packing should tend to redistribute the bubbles for a more even flow pattern. Consider also Bobby Strain's suggestion of using an eductor. A properly designed eductor would help thoroughly mix the air and water and probably reduce the bubble size as well.

That makes sense, and is also what i'm seeing, that it is in the middle of the column, especial in low loads. 

I have tried to make one pipe sparger also, with 4 arms - my problem with this is that I can not have enough holes in releation to the area I need to get down into speed.

I'm currenty testing with random packing also, and yes this has a influence where it distributes the gas over the area I can see. 

This was also seen when i tested with multiple sieves up in the column. 

It is a bubble column kind of system correct, i'm trying to catch ammonia gas in a water tank when it is purged out with nitrogen

Edited by mikkelpoulsen, 13 September - 07:32 AM.

Here is some information I have on pipe distributors:

Flow distribution and pressure drop are two primary considerations in design of distributors. Flow distribution is dependent on Ar, which is the ratio of total perforation or orifice area to pipe cross sectional area. To a lesser extent, it also depends on the distributor length-to-diameter ratio (L/D). FIGURE 16 shows the effect of these parameters on maldistribution. It is evident from the graph that if Ar = 0.5, the distribution is good and above Ar = 1 it is poor. Note that a positive maldistribution indicates higher orifice velocity and pressure near the end of the distributor. Pressure drop through a distributor pipe can be assumed to be 2.8 velocity heads based on the orifice velocity. For Ar > 1, the velocity head should be based on the inlet pipe velocity.

Capture.JPG

I would think this information can give some insight here.  It appears you have too much hole area (too many holes and/or holes too large), and you have a high degree of maldistribution.

What is your total hole area/feed pipe cross-sectional area?  About 8?

Does water leak into the sparger chamber?  Is it a lot?

My area of the tank is:  0,18m2 (ø490 inside diamter) 

My total are of the holes in orifce is: 0,m2 on the case I presented in this (i have teste different areas)

There is water in the sparger chamber - beacuse the water is standing still so the chamber is submerged and there is water up in the inlet pipe also.

Then i the water is pushed out of the pipe when the gas is purged into the tank.

I do not know if all water is pushed out of the chamber, maybe that could be a problem? that the chamber is to large?

i'm not sure how to read the table.

My area of the tank is:  0,18m2 (ø490 inside diamter) 

My total are of the holes in orifce is: 0,m2 on the case I presented in this (i have teste different areas)

There is water in the sparger chamber - beacuse the water is standing still so the chamber is submerged and there is water up in the inlet pipe also.

Then i the water is pushed out of the pipe when the gas is purged into the tank.

I do not know if all water is pushed out of the chamber, maybe that could be a problem? that the chamber is to large?

i'm not sure how to read the table.

The 33.7 mm dia. air feed pipe (1" or 1-1/4" ?) is about 0. m2 in cross-sectional area.  So your AR = 8.  This AR = 8 is indicative of extremely poor distribution of air in a pipe sparger.  Your application is not 100% apples-to-apples to the correlation I provided, but as I said, I think this information can give some insight here. You have a pipe and holes, there is just a large chamber between the two.

I would think the presence of water in the chamber would contribute to maldistribution of air.  Sloshing water will affect the air a lot.

Good distribution has an AR = 0.5, or about 0. m2, or about 46 holes.  However, with only 46 holes your chamber will have more pressure in it than with 741 holes, and you need to be sure it can handle that air pressure safely before proceeding.  If it cannot handle the same air pressure as in the upstream section of that pipe, then you may never be able to get to good air distribution in this column.  Then, listen to the folks suggesting alternative technologies.

Contact us to discuss your requirements of sparger ring. Our experienced sales team can help you identify the options that best suit your needs.

hi,
To me this is an absorption process, a simple column with packing should do the job. Use your existing tank to collect the ammonia solution to be recirculated or not (based on calculation) somewhere on the top of the column. On very top you need to spray clean water to clean the residual ammonia.

Breizh

You are right it is not the most effecient way, i'm fully aware of these absorbers for my project here - i can not use this system. This system has to work without the use of pumping water for other reasons. It will not be the most effecient way, but that is not the goal.

You are right it is not the most effecient way, but the choosen way for other reasons for this project this is how is has to be done.

With this calculation of hole area, the total speed out of the holes will actually increase to the double, where my idea and wish (espcecially in a bubble column) is to decrease the speed of the gas. To give it more time in the water and not to spray it out of the tank i want to decrease the velocity.

I understand you are stuck with this column.  Just a thought.  The air distribution is so bad you may be fooling yourself when looking and discussing average velocity through the holes.  Some holes are actually zero velocity, or negative (water getting in).  And, some holes are very high velocity, to make the mass balance work with all the non-bubbling holes.

I'm also not sure that low speed of bubble rise should be your objective function in a bubble column.  My recollection and experience points to maximizing bubble surface area to increase mass transfer.  This means lots of small bubbles, and not large bubbles coming out of a few holes.  My $0.02.  Good luck with your project, and enjoy!

For sieve plate sparger design, Froude number seems key. See the attached.  Design of Sieve Plate Spargers for Bubble Columns - Joshi.pdf

That is very interesting and good article this one. 

I'm not sure exactly if i get all the numbers and what the froude means, but i will try to study it a littel more.

But i'm pretty sure that my proplem is weeping now, which means that there is water in my chamber and in the holes and that is properly why my distribution is poor.

but the article also claims in the beginning that the window of controlling the weeping of a bubble column could be very narrow.

What is a Sparger in Bioreactor?

In Short, Bioreactors are essential tools for industrial and research processes that involve the cultivation of microorganisms and cells. One key aspect of bioreactor design is the sparger, which plays a critical role in providing oxygen and mixing the contents of the bioreactor. In this blog post, we'll explore what a sparger is, its importance in bioreactors, and the challenges and solutions associated with sparger design and maintenance.

What is a Sparger ?

A sparger is a device used to introduce gas, typically oxygen, into a liquid medium in a bioreactor. The sparger is located at the bottom of the bioreactor and typically consists of a porous or non-porous material that allows gas to flow through it. Spargers come in a variety of designs, including disc spargers, ring spargers, and custom-designed spargers.

Importance of Spargers in Bioreactors

Spargers play two crucial roles in bioreactors: oxygen transfer and mixing. 

Oxygen Transfer

In bioreactors, the availability of oxygen is essential for the growth and metabolism of microorganisms and cells. Spargers aid in the transfer of oxygen from the gas phase to the liquid phase in the bioreactor. The efficiency of oxygen transfer depends on factors such as the gas flow rate and pressure, the type of sparger, and the vessel geometry.

Mixing

Uniform mixing of the contents of a bioreactor is essential for optimal growth and productivity of microorganisms and cells. Spargers aid in mixing by creating a stream of gas bubbles that rise to the surface and agitate the liquid contents of the bioreactor.

Sparger Design and Selection

Choosing the right sparger design and size is critical for the efficient operation of a bioreactor. The factors that influence the selection of a sparger include the type of bioreactor, gas flow rate and pressure, vessel geometry, and process requirements.

Types of Sparger Designs

Porous spargers are made of materials such as sintered metal, ceramic, or polymer, which allow gas to flow through the material. Non-porous spargers, on the other hand, are made of materials such as stainless steel and have holes or slots to allow gas to flow through. Custom-designed spargers can be tailored to specific bioreactor configurations and process requirements.

Challenges and Solutions with Spargers in Bioreactors

Several challenges are associated with spargers in bioreactors, including fouling, pressure drop, and inefficiency. Proper sparger design, regular cleaning, and maintenance can help overcome these challenges.

Fouling

Fouling occurs when the sparger becomes clogged with microorganisms or other particles, which reduces its efficiency. Regular cleaning and maintenance can help prevent fouling and prolong the life of the sparger.

Pressure Drop

A pressure drop can occur when gas flow through the sparger is restricted, which reduces the efficiency of oxygen transfer and mixing. The pressure drop can be minimized by selecting the right sparger design and size for the bioreactor configuration.

Inefficiency

Inefficiency occurs when the sparger is not delivering enough oxygen or creating enough mixing to meet process requirements. Inefficiency can be addressed by optimizing the sparger design and process conditions.

Applications of Spargers in Bioreactors

Spargers are used in a variety of industrial and research applications, including:

Industrial Applications

1. Pharmaceutical production:

Spargers are used in the production of drugs, vaccines, and other biological products. Bioremediation: Spargers are used to aerate contaminated water and soil, which promotes the growth of microorganisms that break down pollutants.

2. Wastewater treatment: 

Spargers are used in the treatment of wastewater to promote the growth of microorganisms that consume organic matter and pollutants.

3. Food and beverage production: 

Spargers are used in the production of beer, wine, and other fermented foods and beverages.

Research Applications

1. Cell culture: Spargers are used to provide oxygen and mixing in cell culture systems, which are used to grow and study cells.

2. Microbial fermentation: Spargers are used in microbial fermentation systems to promote the growth and metabolism of microorganisms.

FAQ about the Sparger in Bioreactor ? 

1. What is a sparger in a bioreactor?

A sparger is a device that is used to introduce gases, such as air or oxygen, into a bioreactor. The sparger is typically located at the bottom of the bioreactor and consists of a porous material through which the gas is passed.

2. Why is a sparger used in bioreactors?

Spargers are used in bioreactors to provide oxygen to the microorganisms or cells being grown. Oxygen is necessary for cellular respiration and growth, and a sparger provides a means of introducing oxygen into the culture medium.

3. What types of spargers are there?

There are several types of spargers, including sintered metal spargers, ceramic spargers, and frit spargers. The type of sparger used depends on the specific requirements of the bioreactor and the process being used.

4. How does a sparger work?

A sparger works by introducing gas into the bioreactor through a porous material. The gas then bubbles through the culture medium, providing oxygen to the microorganisms or cells.

5. What are some factors to consider when selecting a sparger?

Some factors to consider when selecting a sparger include the size of the bioreactor, the type of microorganisms or cells being grown, the desired oxygen transfer rate, and the availability of the gas being used.

6. How can the performance of a sparger be optimized?

The performance of a sparger can be optimized by selecting the appropriate sparger type and size, controlling the flow rate of the gas, and ensuring that the sparger is properly positioned in the bioreactor.

7. Can a sparger be used for other gases besides oxygen?

Yes, spargers can be used to introduce other gases, such as carbon dioxide or nitrogen, into a bioreactor. The type of gas used depends on the specific requirements of the process being used.

8. What is the effect of sparger design on bioreactor performance?

The design of the sparger can have a significant impact on the performance of the bioreactor. Factors such as sparger size, shape, and porosity can affect the rate of gas transfer, mixing, and shear stress in the culture medium.

9. What is the role of sparger placement in a bioreactor?

The placement of the sparger in a bioreactor can affect the distribution of gas and the mixing of the culture medium. Proper sparger placement is important for achieving uniform oxygen transfer and maintaining a homogeneous culture.

10. Can sparger fouling affect bioreactor performance?

Yes, sparger fouling can affect bioreactor performance by reducing the rate of gas transfer and altering the mixing of the culture medium. Regular cleaning and maintenance of the sparger can help prevent fouling.

11. How does sparger design affect shear stress in a bioreactor?

Sparger design can affect the shear stress in a bioreactor by altering the rate of mixing and the size and distribution of bubbles. High shear stress can be detrimental to some microorganisms or cells, so sparger design should be carefully considered.

12. What is the impact of sparger type on gas bubble size?

The type of sparger used can affect the size of gas bubbles produced. Ceramic and frit spargers tend to produce smaller bubbles, while sintered metal spargers tend to produce larger bubbles.

13. How does sparger design affect oxygen transfer rate?

Sparger design can affect the oxygen transfer rate by altering the surface area available for gas transfer and the size and distribution of bubbles. Factors such as sparger porosity and gas flow rate can also impact the oxygen transfer rate. 

14. Can sparger design impact cell viability or product yield?

Yes, sparger design can impact cell viability or product yield by affecting factors such as oxygen transfer rate, shear stress, and mixing. Improper sparger design can lead to poor cell growth or product yield, so careful consideration of sparger design is important.

15. What are some common challenges associated with sparger use in bioreactors?

Common challenges associated with sparger use include fouling, uneven gas distribution, excessive shear stress, and difficulty controlling gas flow rates. Regular maintenance and monitoring can help mitigate these challenges and ensure optimal bioreactor performance. 

16. What is the impact of sparger design on gas holdup in a bioreactor?

Sparger design can affect the gas holdup in a bioreactor by altering the size and distribution of bubbles. The amount of gas in the culture medium can impact factors such as mixing, oxygen transfer rate, and shear stress.

17. How does sparger design impact the formation of foam in a bioreactor?

Sparger design can impact the formation of foam in a bioreactor by altering the rate of gas introduction and the size and distribution of bubbles. Sparger design can also impact the distribution of nutrients and cells in the culture medium, which can impact foam formation.

18. Can sparger design impact the pH of the culture medium in a bioreactor?

Yes, sparger design can impact the pH of the culture medium by altering the rate of gas introduction and the mixing of the culture medium. Careful consideration of sparger design and gas flow rates can help maintain a stable pH in the culture medium. 

19. How can the size of the sparger impact bioreactor performance?

The size of the sparger can impact bioreactor performance by affecting factors such as gas transfer rate, mixing, and shear stress. A larger sparger can provide a greater surface area for gas transfer, but may also increase shear stress in the culture medium. 

20. What is the impact of sparger design on energy consumption in a bioreactor?

Sparger design can impact energy consumption in a bioreactor by affecting the rate of gas transfer and the mixing of the culture medium. Efficient sparger design can help reduce energy consumption while still providing adequate oxygen transfer and mixing. 

Conclusion

In conclusion, spargers play a critical role in providing oxygen and mixing in bioreactors. The selection and design of a sparger depend on several factors, including the type of bioreactor, gas flow rate and pressure, vessel geometry, and process requirements. Regular cleaning and maintenance of the sparger are essential to prevent fouling and ensure efficient operation. Spargers are used in a variety of industrial and research applications, including pharmaceutical production, bioremediation, wastewater treatment, and food and beverage production.

Are you interested in optimizing your bioreactor performance?

If so, consider incorporating a sparger into your system. Spargers are devices used to introduce gases into bioreactors, promoting better mixing and aeration of the culture medium, which can lead to improved cell growth and production.

By using a sparger in your bioreactor, you can increase the dissolved oxygen concentration, which is essential for many cell types to thrive. Additionally, spargers can help to distribute nutrients evenly throughout the bioreactor, preventing the buildup of harmful byproducts and reducing the risk of cell death.

If you want to take your bioreactor performance to the next level, consider investing in a high-quality sparger.

If you want to learn more, please visit our website sintered stainless steel sparger.

Post time: Apr-10-