HOME ELECTROSTATIC PRECIPITATOR Contact Us Site Map
CUSTOMERS
There are no dreams too large, no imaginations unimaginable and no frontiers beyond our reach. Our innovation engine is in overdrive and shows no signs of slowing down.
Our business world gives us an opportunity to better serve the entrepreneurs and job seekers. We have privileged to introduce ourselves as the best consultancy team having team leaders, designers, and advisers, HR Managers etc. We are also associated with the reputed companies for their day-to-day requirement of manufacturing, procurement, product finding, and manpower recruitment.
PRE ORDER NETWORK ON MS PROJECT:
Besides this our in-house activities involve R&D activities, designing, market survey and provide consultancy to the new upcoming organization, sick industries and growing organization. In brief we are in following major activities:
Project Consultancy Services
Consultancy For Erection and Commissioning
Project Execution Software and its Demo
Detailed Project Reports for upcoming projects.
Design, Engineering, manufacturing, supply consultancy services.
Undertake product marketing, erection and commissioning services.
Manpower recruitment for IT professionals, Engineering, Technologist etc.
Import and Export documentation services
Business Linkers and Associations
Technical and Financial assistance
Resident Operation and Maintenance services.Register of Industrial Product Finder/Projects and Vacancies from Recruiters
INVITE FREELANCERS,DESIGNERS,ENGINEERS AS MEMBERS(FREE JOINING WITH SHARING BENEFITS)OF TEAM
Description on dense phase conveying and dilute phase conveying.
The Zenz diagram is widely accepted as a description of pneumatic conveying.
Since the calculation of a Zenz diagram is now possible by an extensive computer program, it is also possible to investigate how the diagram is formed.
Bulkblog article “Pneumatic Conveying, Performance and Calculations!”. By varying the air flow at constant capacity, the resulting partial pressure drops were calculated and combined into a table.Zenz diagram
From The Graph following information can be Taken:
- Filter pressure drop increases with increasing air volume
- Gas pressure drop increases with increasing air volume
- Suspension pressure drop decreases with increasing air volume
- Elevation pressure drop decreases with increasing air volume
- Product pressure drop:
- In case of sedimentation the product pressure drop decreases with increasing airflow.
- Above sedimentation, the product pressure drop firstly increases with increasing airflow, due to the stronger influence of the velocity increase opposed to the influence of the SLR.
- Above the airflow, whereby the influence of the decreasing SLR is stronger than the influence of the increasing velocity, the product pressure drop decreases with increasing airflow.
- The acceleration pressure drop increases with increasing airflow.
6. The pressure drop for the material intake stays constant
7. The summation of the partial pressure drops for each airflow generates the Zenz curve.
8. The lowest point in the Zenz curve, where the pressure drop per meter is minimum, is the boundary between dense- and dilute phase conveying.
Left of this point, the pneumatic conveying is considered dense phase conveying.
Left of this point, the pneumatic conveying is considered dense phase conveying.
In dense phase conveying the solid Loading Ratio (SLR) is higher than in dilute phase conveying.
As the absolute SLR is depending on the conveying length, the absolute SLR in it self is not an indication about the conveying regime being dense or dilute.
9. At lower airflows, sedimentation starts because of too low air velocities and at even lower velocities, the airflow changes from turbulent to non turbulent.
In that region the pneumatic conveying circumstances vary significantly with a small change in airflow.
Airflow changes can also occur through air surges, caused by material flow irregularities.
Induced pressure waves forces the pneumatic conveying conditions from f.i asub turbulent flow into a turbulent flow and combined with changes in sedimentation, the pneumatic conveying behavior can become unstable, which is often observed in practice.
When the graph is build up in the reverse order (from intake to filter), discontinuities show up in the curves for acceleration and product resistance.
The remarkable discontinuities in the graph are caused by the introduction of criteria for sedimentation and turbulence into the calculation algorithm.
10. The lowest energy consumption occurs at the point where the turbulence changes from turbulent to non turbulent.
Sedimentation is then already present.
The lowest pressure drop per meter is therefore not the most energy efficient conveying design.
This is because the energy is the multiplication of pressure and airflow.
Although the pressure is low, the airflow has increased more, resulting in a higher energy consumption.
10. The lowest energy consumption occurs at the point where the turbulence changes from turbulent to non turbulent.
Sedimentation is then already present.
The lowest pressure drop per meter is therefore not the most energy efficient conveying design.
This is because the energy is the multiplication of pressure and airflow.
Although the pressure is low, the airflow has increased more, resulting in a higher energy consumption.
In general an installation should be designed in dense phase in order to have the benefit of low energy consumption per ton. Although in dense phase, the installation is not necessarily optimal, regarding energy efficiency.
In case the design is in the region where sedimentation and turbulence changes are occurring and the material conveying properties are difficult under that regime, then additional measures have to be taken to ensure controlled “unstable” conveying or redesign to a stable conveying region.
Also irregular feeding can induce unstable behavior.
The magnitude in which these phenomena are occurring depends on installation time constants and -time responses to changes.
Whether an installation is operating in the dense phase mode or the dilute phase mode can only be concluded after calculations for different air flows have been executed.
Judging whether a conveying installation is in dense- or dilute phase just by the Solid Loading Ratio is useless, because a long pipe line (low SLR) can be in dense phase and a short pipe line (high SLR) van be in dilute phase.
These examples show that dense- and dilute phase pneumatic conveying are 2 regions by definition, but belong to the same pneumatic conveying technology.
In theoretical discussion, the interpretation can be very useful, but in practice it is not so important, because a properly designed installation should always be the installation with the lowest energy demand and still meeting the desired performance.
This could be a dense phase installation but a dilute installation as well.
The interpretation of dense- and dilute phase conveying should now be clear.
Que: Sir we are running the f.k.pump for last 20 Years@155-166tph with two Compressor having designed FAD of 56 m3/min each but measured value of FAD of 45m3/min each at @2kg/cm2 pressure. We are upgrading the cement mill for 225tph by installing V-seprator in the circuit so we are redesigning it for 225tph. I am doubtful wheather it will work smoothly at FAD of 60.6m3/min. Normal back pressure is coming around 1.0 bar but sometime we are facing tripping of the F.K.Pump due to high back pressure even at 155-160tph.Please clarify our doubt for smooth functioning at FAD of 60.6m3/min@225tph.
Ans. : Dear, The FK pump is the feeder of a pneumatic system.
The feeder function of the FK pump is 150-165 tons/hr against the pneumatic pressure. For FK pump,this pressure is limited at approx.1.8bar(O)
(For 150 tons /hr,the drive motor of the FK pump should be approx.110KW at 980rpm)
Increasing the FK pump capacity from 150tons/hr to 225 tons/hr will at least require a drive change to 165KW at 1500rpm or a new FK pump or an additional FK pump.
As you experience overloading tripping of your present FK pump drive motor,due to high conveying pressure,this is an indication that the pneumatic conveying system needs to be redesigned,to keep the conveying pressure at maximum of 1.8bar at225 tons/hr
Que:Can anybody give me the suggestion for the equation of calculation of pressure drop in pneumatic conveying of spherical granular material in horizontal pipe ?
I have used the Ergun equation but it gives higher pressure drop than the expected.
My Parameters:
Particle Diameter:- 3mm
Density of Fluid (Air) :- 1.2
Porosity:- 54.8%
Length of Pipe :- 1.5 m
Viscosity of Fluid (Air):- 1.8E-05
Superficial Velocity (Assumed):- 5m/s
I have used this book and on the page 232-233. I could find the equation for the calculation of pressure drop. Through that I could find expected pressure drop.I have used the Ergun equation but it gives higher pressure drop than the expected.
My Parameters:
Particle Diameter:- 3mm
Density of Fluid (Air) :- 1.2
Porosity:- 54.8%
Length of Pipe :- 1.5 m
Viscosity of Fluid (Air):- 1.8E-05
Superficial Velocity (Assumed):- 5m/s
http://books.google.com/books?id=wnFRV_rZAwUC&printsec=frontcover&dq=Pneumatic+Conveying+of+Solids#v=onepage&q=&f=false
The equation is as follows,
Delta P = [fri.factor(fluid)*density(gas)*velocity(gas)*velocity(gas)*length(pipe)/2*Dia(pipe)*gravity]
+
[fri.factor(solid)*density(gas)*velocity(gas)*velocity(gas)*length(pipe)*solid loading ratio/2*Dia(pipe)*gravity]
But still I am confused about the exact value of gas(air) friction factor and loading ratio.
Here, I have attached one paper which is quite similar to my topic, from which I have used the Ergen equation (Equation no.5) for the calculation of pressure drop.
Ans :The equation you give,
“
Delta P = [fri.factor(fluid)*density(gas)*velocity(gas)*velocity(gas)*length(pipe)/2*Dia(pipe)*gravity]
+
[fri.factor(solid)*density(gas)*velocity(gas)*velocity(gas)*length(pipe)*solid loading ratio/2*Dia(pipe)*gravity]
“
is the summation of the gas only pressure drop plus the product loss pressure drop as a factor times the gas only pressure drop and proportional to the Solids Loading Ratio.
The SLR is defined as:
(mass flow of material)/(mass flow of gas) in f.i (kgs material/sec)/(kgs air/sec)
The above equation does not account for keeping the material in suspension, accelerating the material and elevating. This shortcoming cannot be incorporated in the fri.factor(solid), as these conditions vary widely for different installations.
Neither the material velocity (or slip velocity) is accounted for.
The slip velocity is depending on the suspension velocity of the material particles and the material loss factor.
The value of gas(air) friction factor is the fanning factor, which can be calculated by the
Swamee-Jain equation.
The formula, which you used is for Horizontal Low Velocity Slug Flow and not for dense- or dilute pneumatic conveying.
The research in pneumatic conveying has revealed many important phenomena, however, it never resulted in a uniform mathematical approach and easy, flexible to use calculation program (apart from some simple spreadsheets) that showed a transparent output.
Therefore, it is not safe, just to pick an equation from a book or article and apply that formula to your own situation.
It is understandable that universities and research laboratories focus on the theory of pneumatic conveying, but the manufacturers must develop working calculation programs that are in conformity with practice.
However, those manufacturers keep that information to themselves for commercial reasons.
In this forum, many pneumatic conveying questions are put forward and I try to answer them in such a way that a discussion about the principles of pneumatic conveying would emerge.
The latter, unfortunately, is not really happening.
“
Delta P = [fri.factor(fluid)*density(gas)*velocity(gas)*velocity(gas)*length(pipe)/2*Dia(pipe)*gravity]
+
[fri.factor(solid)*density(gas)*velocity(gas)*velocity(gas)*length(pipe)*solid loading ratio/2*Dia(pipe)*gravity]
“
is the summation of the gas only pressure drop plus the product loss pressure drop as a factor times the gas only pressure drop and proportional to the Solids Loading Ratio.
The SLR is defined as:
(mass flow of material)/(mass flow of gas) in f.i (kgs material/sec)/(kgs air/sec)
The above equation does not account for keeping the material in suspension, accelerating the material and elevating. This shortcoming cannot be incorporated in the fri.factor(solid), as these conditions vary widely for different installations.
Neither the material velocity (or slip velocity) is accounted for.
The slip velocity is depending on the suspension velocity of the material particles and the material loss factor.
The value of gas(air) friction factor is the fanning factor, which can be calculated by the
Swamee-Jain equation.
The formula, which you used is for Horizontal Low Velocity Slug Flow and not for dense- or dilute pneumatic conveying.
The research in pneumatic conveying has revealed many important phenomena, however, it never resulted in a uniform mathematical approach and easy, flexible to use calculation program (apart from some simple spreadsheets) that showed a transparent output.
Therefore, it is not safe, just to pick an equation from a book or article and apply that formula to your own situation.
It is understandable that universities and research laboratories focus on the theory of pneumatic conveying, but the manufacturers must develop working calculation programs that are in conformity with practice.
However, those manufacturers keep that information to themselves for commercial reasons.
In this forum, many pneumatic conveying questions are put forward and I try to answer them in such a way that a discussion about the principles of pneumatic conveying would emerge.
The latter, unfortunately, is not really happening.
.>>
There is no simple, reliable equation from which you can find out the pressure drop in your system.There are a set of equations that can calculate the pressure drop over a short pipe distance dL.
Newton’s laws to calculate accelerations and velocity equations supplement these equations.
The integration of these calculated pressure drops over the total length gives you the total pressure drop.
The pressure drop for product losses requires a product loss factor and formula.
This product loss factor is determined from existing installations or tests.
Suspension velocity and SLR are some of the main parameters in these equations.
The integration method (plus an iteration process) is necessary because of the compressibility of the conveying gas.
The application of a computer facilitates the possibility of executing the high number of calculations to get to this result. (Visual Basic is a great tool to achieve this)
In addition, there are extra pressure drops involved, s.a. filters.
The parameters you supplied in your initial thread are not sufficient to perform a calculation.
At least the following values are needed:
Material
particle size
particle density
bulk density
(suspension velocity)
pipe geometry
capacity
Any other important information s.a. temperatures, altitude, etc.
Que:Dear sir,
I am an engineer working in plastic factory. Could you please give me the calculated results from following data.
Material to convey : Calcium carbonate
Conveying rate : 1500 kg / hrs.
Line diameter : 2 inch
Starting from the inlet, line is 4 meter horizontal, then 90 degree long radius bend, then line is 6 meter vertical, then 90 degree long radius bend connected to the inlet of receiving bin.
Conveying line material : stainless steel pipe
Use ambient air at standard conditions.
Need to know : pressure drop in a vacuum type conveying system and
: type of blower and power used
Your assistance is much appreciated.
How is the marerial fed into the pipe line.
Suction nozzle or rotary airlock or gravity mixing inlet?
Is there a rotary lock underneath the filter-receiver bin?
Material feeding influences the initial intake pressure drop.
A rotary lock underneath the receiving bin causes air leakage, which has to be compensated for by the vacuum pump.
Ans:I did a quick design calculation of which the results are given in the attached pdf.
These calculations can only be regarded as an indication.
1500 kg/hr is not much. (2 buckets per minute) and the distance (10 m) is very short.
Que :Theory and Design of Dilute Phase Pneumatic Conveying Systems ,Article:
The paper is a straight forward approach to the subject and is easy to follow, however,
- are there inconsistencies in the attached worksheet?
-- the roughness factor used seems to be 0.00015 instead of 0.0005
-- the pipe section in worksheet 2 section 9 was moved to section 10 in worksheet 3
- I do not feel comfortable when a pressure is given as mass/area rather than force/area, but this is just my problem with Newtons/sqm.
- Is it possible that the calculation method
-- does not represent the pressure drop minimum at the point of saltation velocity properly?
-- is wrong in regard to assuming a constant product friction multiplier over the whole velocity range?
- I miss some limits within which the formulae are applicable, like
-- maximum solid/gas ratio
-- minimum velocity depending on different products and particle sizes
- The Zenz equation also considers acceleration of the carrier gas, however, though the dp is small, it is not listed in the calculation table.
- What are common criterion for stepping up a pipe? Shall this be based on dynamic gas pressure, same pressure ratio for same diameter sections, Reynold number minimum, Froude number minimum?
- The gas pressure drop for bends can be calculated fairly accurately with a factor of 0.12. Is there a different way to calculate the pressure drop due to the product rather than using an equivalent length? Solids deceleration to xx% gas speed and re-acceleration as per W*Vp/4640 might be an option.
I have concerns whether the approach is as "easy" to apply to reality as it looks. I appreciate your comments ;-)
Ans :Thanks very much for your comments and questions on my article. My responses to these are given below:
1. The calculation method given in the article is correct. There are a few “typos”, i.e., mistakes that were made by the publisher in the process of printing. But most people who are conversant with Excel and the calculation method given in the article should be able to easily spot them out.
2. One mistake is in the equation for the Fanning Friction Factor. I will be happy to send the correct equation if you need it.
3. The other mistake is in Worksheet No. 3. Row Nos. 11 to 14 should all be moved up by one row.
4. The pipe line friction factor used in the sample calculations is for internally shot-peened pipe. This factor is 0.0005, not 0.00015.
5. All of the units used in the equations are correct. You may change them if you prefer any other units.
6. Calculation method is applicable to dilute phase only, up to the minimum pressure point. For calculations to be correct, solids velocity must be higher than the saltation velocity.
7. Please send your data that shows a relationship between the Solids Friction Factor and Solids Velocity. Information that I have does not show that there is this relationship.
8. Regarding putting limits in the calculations for maximum solids to gas ratio, this can be hone but the conveying system should be designed by people who know what they are doing. As regards putting a limit on minimum conveying velocity, this limit is the saltation velocity with an adequate safety factor. This velocity should be calculated using well-known co-relations given in the literature. It varies depending upon thm conveyed material, pipe line diameter, etc. I can send this co-relation to you if you need it.
9. For all practical purposes pressure drop due to the acceleration of gas is so small that it can be ignored, but it can be included in the calculations if someone wants to include it.
10. As regards criteria for stepping up a pipe line, this is another subject. It is not covered in the present article.
11. For bend pressure drop, the method given in the article is empirical but gives fairly correct results. The analytical method that you are thinking of requires accurate data on the effect of solids properties on decrease of solids velocity going through a bend. This complicated relationship can be mathematically derived, but its results may not be much better. This subject however is worth more study.
12. At the end you are saying “I have concerns whether the approach is as “easy” to apply to reality as it looks”. I am sure the calculation method given in the article can be converted into a software program to make it easier to use. But for those people who know Excel, I think that this method is quite easy to follow.
