Design methods for calculations of dilute phase pneumatic conveying linesReview of published models in literatureExcel Calculation filesDo you have a question, a remark ? Please contact the author at powder.process@protonmail.com 

Pneumatic
Transport
# Types of pneumatic transport # Conveying phases # Dilute Phase transport # Dense Phase transport # Air mover # Roots Blower #
Roots Blower performance curve
# After Cooler # Airlock Rotary Valve # Product inlet / Injector # Piping #
Filters
#
Choking velocity
# Conveying speed / velocity # Air volumetric and mass flowrate # Pipe Equivalent Length # Solids particle velocity in pipe # Bends # Solids Breakage #Pipe Diameter or Bore
# Selecting dilute or dense
phase

1. IntroductionThere are not many design
models for pressure dense phase published in the
literature. The knowledge mainly remains with systems
vendors. The author has found 4 detailed methods in books
or articles, which are presented in this page. Some explanations on each
models is given and an Excel Calculation Sheet is proposed
for 3 of the pressure drop calculation methods. These
files are given without guarantee and the user should
keep a critical eye on the results and revert to
reputable companies for detail design. Note some of the methods are
iterative. It is necessary to make some assumptions
perform iteration to confirm them by calculation. Commercial companies and consulting firms have indeed their own models or have modified the methods presented in this page to make them more accurate. They also have large database of materials conveyed that are helpful to calibrate the models. 2. Methods from RhodesThis method has been published in Principles of Powder Technology, M.J. Rhodes et al., Wiley, 1990. It is a rigorous method in its approach which is to breakdown the pressure drop in multiple components, allowing to calculate them one by one. The following link gives access
to an Excel file performing the calculations according to
this method  no guarantee is given, one should use this
file as a 1st approximation and consult a reputable
company for detail design : Link The file is showing an example
given in the solutions to the problems of the books and
that can be found in the site of the editor (Link).
There are minor differences in the calculations results. 3. Air only pressure drop method (Mills)Contrary to the method proposed
by Rhodes, this method is mainly empirical and relies 1st
on the calculation of the pressure drop of the conveying
flowing alone (air ONLY). From this pressure drop, a
correlation is applied to estimate the pressure drop when
materials is transported. This calculation procedure for
calculating the pressure drop in dilute phase conveying is
given in Pneumatic Conveying Design Guide, Mills,
2004, Elsevier. The following link gives access to an Excel file performing the calculations according to this method  no guarantee is given, one should use this file as a 1st approximation and consult a reputable company for detail design : Link The file is showing the example
used in the book of Mills, page 411 onwards. 4. Universal Conveying method (Mills)This method is also empirical
and relies on abacus built from experimental data on a 53
mm bore line. To be used, the characteristics of the
industrial line foreseen must therefore be scaled down to
define what is specific pressure drop foreseen as a
function of the air flowrate and product flowrate. From
the specific pressure drop, the calculation of equivalent
length of the industrial line for horizontal, vertical and
bends allow to calculate the expected pressure drop. This design method is given in
Pneumatic Conveying Design Guide, Mills, 2004, Elsevier.
To be noted that this method is also valid for dense phase
conveying. The method is not given here but the reader can refer to the book mentionned. 5. Modified ZenzOthmer method (Agarwal)This method is similar to the one presented by Rhodes (see above) as it breaks down the pressure drop in several components that are representing the physical phenomena experienced by the fluid and the solids and which are leading to pressure drop. It is modified from the original method of ZenzOthmer as the friction due to the solid has been simplified and represented by a single coefficient K called friction multiplier. This factor must be calculated from experimental data for every product transported. This makes the method very
interesting in order to adjust the model to a particular
component thanks to the K friction multiplier. However, it
means that the method cannot be used a priori, while the
methods presented above can. The following link gives access to an Excel file performing the calculations according to this method  no guarantee is given, one should use this file as a 1st approximation and consult a reputable company for detail design : Link
The file shows the example
given in the article from Agarwal, the reader will not
there is a slight difference in the results of the article
and the calculation file probably due to slightly
different inputs. The
note can be found on internet.
Please refer to the article for more details on the inputs
required.
Shortcut calculation methodWhen almost no data are available on the product to transport, a shortcut calculation method can be used to have an idea of the pressure drop of a line. Note that it is not at all an accurate methodology and should therefore not be used for the design of industrial installation. 
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