Micro-travel showers are common now-a-days. However, this presentation gives some new ideas to think about.

1. By:
Rethinking MicroRethinking MicroRethinking MicroRethinking Micro----Travel ShowerTravel ShowerTravel ShowerTravel Shower
By:
D K Singhal
deveshksinghal@gmail.com

2. Rethink? But WHY?
Micro-travel showers are being used since decades.
These are proven to be more effective than conventional
showers.
All machinery suppliers (almost) are supplying machines
with micro-travel showers only.
June 2014Rethinking Micro-Travel Shower2
with micro-travel showers only.
Micro-travel showers have already been well documented.
We are aiming towards 23rd century, why should we think
something that is decades old, obsolete?

3. Reasons to Think…..
Any technology is most suitable only for a particular set of
operating conditions.
Problem starts when we use new technology with old
machines.
If you run latest software on your old laptop, this may run,
but not very efficiently (and vice versa). Maybe much older
June 2014Rethinking Micro-Travel Shower3
If you run latest software on your old laptop, this may run,
but not very efficiently (and vice versa). Maybe much older
version works better satisfying most of your needs.
Furthermore, thinking does not cost a capital investment,
does not risk our operating equipment or does not
deteriorate product quality.
However, it may give some clues for further improvement.

4. Back to the Basics…..
You might have already seen the
following pattern in the literature of
micro-travel shower suppliers.
The black lines are areas cleaned by the
showers and the white area represents
June 2014Rethinking Micro-Travel Shower4
showers and the white area represents
part of fabric that is not clean.
Nobody would like fabric cleaning in this
way. Right?

5. Look at the Pattern
Look at the white area in the figure.
You get unclean areas on fabric in the
shape as in the shape given below.
This shape can be characterized by the
vertical and horizontal dimensions.
June 2014Rethinking Micro-Travel Shower5
vertical and horizontal dimensions.
Vertical dimension is in machine
direction, while the horizontal one is in
cross direction.

6. Typical Dimensions
As obvious, the horizontal dimension (size in cross direction)
cannot exceed distance between nozzles. Say it is 100, 125 or
150mm.
Similarly, the vertical dimension (size in machine direction)
cannot exceed length of fabric.
June 2014Rethinking Micro-Travel Shower6
cannot exceed length of fabric.
But, what is the minimum limit of this length we can achieve?
The vertical dimension can be reduced only if the shower
makes a rotation faster than the two rotations of fabric.

7. Increase Shower Speed
Yes.To get a smaller vertical dimension in the
figure, you need to increase shower speed, but
that is not practically possible.
10-12 rpm is very high for showers.
So, can such a pattern really exist on our paper
June 2014Rethinking Micro-Travel Shower7
So, can such a pattern really exist on our paper
machines really?
Should we not start recalculating dimensions
according to our running machines?
By the way, if you had an experience of using
conventional shower, did you see such pattern
on your fabric anytime?

8. Machine Direction Strips
If you are using a micro travel shower, do you, sometimes,
notice different dirty and clean strips across the full length of
fabric?
If yes, let us rethink micro-travel showers.
June 2014Rethinking Micro-Travel Shower8

9. Micro-Travel Showers
The speed of micro-travel shower can be calculated by the
following formula-
June 2014Rethinking Micro-Travel Shower9
This looks very fine. By this one can be sure that each and
every point on fabric will get cleaned by the high pressure
water jet on its turn.

10. Possible Problems
The biggest problem on slower speed machines is that the
shower needs a long time to complete one revolution.That
means complete cleaning after a caustic wash takes long time
this increasing downtime.
Some mills have installed two HP showers, a micro-travel for
normal operation, and another standard HP shower for faster
June 2014Rethinking Micro-Travel Shower10
normal operation, and another standard HP shower for faster
fabric cleaning after a caustic wash. However, officers from
‘Pollution Control Board’ often object to this saying that the
mill seems uses both showers almost all the time and thus
water consumption increases.
Some other mills have started depending on LP showers for
fabric cleaning after a caustic wash.

11. Possible Problems
Another practical problem is that the speed of micro-travel
shower is so low that it often appears stationary to the
operators.
In developed countries, you can trust equipment; but in our
area, where frequent power cuts and voltage fluctuations
June 2014Rethinking Micro-Travel Shower11
area, where frequent power cuts and voltage fluctuations
causing electrical tripping is common; a tripping of micro-
travel shower motor goes unnoticed, and it often gets too
late when you detect a problem.

12. Possible Problems
The micro-travel shower design speed calculation does not
take care of the fabric guiding effect.
If fabric is being guided towards drive side and the shower is
also moving in the same direction, uniform fabric cleaning
will NOT take place.
June 2014Rethinking Micro-Travel Shower12
will NOT take place.
If both are moving in opposite directions, uniform but
inadequate cleaning will take place.
Have you noticed machine direction strips of clean and
unclean area easily visible just by looking at a glance?

13. Thinking Out of the Box
The basic idea behind the micro-travel shower is that the
shower should move equal to its nozzle diameter in one
fabric revolution.
But, on slow speed machines this results in increased time to
cover the complete fabric.
June 2014Rethinking Micro-Travel Shower13
cover the complete fabric.

14. Typical Micro-Travel Pattern
A typical pattern showing micro-
travel shower cleaning is given here.
If the nozzle diameter is 0.7mm,
each cleaning line is 0.7mm apart.
Well, this means shower speed to be
June 2014Rethinking Micro-Travel Shower14
Well, this means shower speed to be
very slow, say less than 0.05rpm.
Can we get a similar pattern even
after increasing shower speed?

15. Imagine of Another Pattern
Suppose, the shower moves equal to
twice of shower displacement plus
nozzle diameter, the pattern could be
something like given here.
In fact, here, there is no difference in
June 2014Rethinking Micro-Travel Shower15
In fact, here, there is no difference in
cleaning of fabric compared to
conventional micro-travel one.
But, here again, the fabric cleaning
time will be high.

16. Another Case
If we consider shower movement only
equal to the shower displacement at
one fabric rotation, we may get
something like shown here.
This is not acceptable. Right?
June 2014Rethinking Micro-Travel Shower16
This is not acceptable. Right?
But, overall, what is the main
difference between all these concepts?

17. Summing up Information
At shower movement equal to shower displacement at each
fabric revolution, we are supposed to get‘X’ pattern with
clean and unclean areas.
If shower movement is increased to‘nozzle diameter’ plus
‘integer times the nozzle spacing’ in every fabric rotation, the
June 2014Rethinking Micro-Travel Shower17
‘integer times the nozzle spacing’ in every fabric rotation, the
cleaning can be made similar to theoretical micro-travel
shower.

18. Case Study
Here, one can see that the
micro-travel effect can be
obtained at different shower
speeds.
One can calculate that the
June 2014Rethinking Micro-Travel Shower18
One can calculate that the
cleaning would be identical and
same if we operate shower at
any of the 0.016, 2.25, 8.95,
or15.6rpm.

19. Is There Something Missing?
Yet, a significant point to consider is still missing.
That is effect of fabric guiding.
June 2014Rethinking Micro-Travel Shower19

20. Fabric Guiding
In conventional micro-travel shower design, we assume that
the fabric is stationary with respect to machine center line,
i.e. cross direction movement is ZERO.
But, that is not the case generally.
Fabric moves to and fro in cross direction during run.
June 2014Rethinking Micro-Travel Shower20
Fabric moves to and fro in cross direction during run.
In this way, some areas may remain unclean and have to wait
long for their next turn.
This can easily be seen on most fabrics as a band of clean and
dirty machine direction strips.

21. Showering with Guiding
One can understand that a grid pattern formed in
conventional showers will shift its position due to movement
of fabric due to guiding.
So, it is unlikely that we may see such clear demarcation of
clean and dirty areas on any fabric.
June 2014Rethinking Micro-Travel Shower21
clean and dirty areas on any fabric.

22. Making Use of Guiding
This hints a new concept for efficient cleaning.
If we are able to alter the shower speed with time, the grid
pattern formed by one speed will overlap with the pattern
formed earlier, and you get a cleaner fabric.
For better results with this approach, the shower speed
June 2014Rethinking Micro-Travel Shower22
For better results with this approach, the shower speed
should be properly chosen.
But the results will be same as in conventional micro-travel,
except that the whole cycle will repeat fast, thus minimizing
the problems caused by guiding.
Let us name this as Floating Speed Micro-Travel.

23. Floating Speed MicroFloating Speed MicroFloating Speed MicroFloating Speed Micro----TravelTravelTravelTravel
For aVFD, it is generally considered better if we operate the
same at speeds between 60%-100%. ConventionalVFDs may
work at speeds as low as 10%, but torque limitations may
create problems of current overload in some situations.
So, for any speed of shower, we may work above 60% of
June 2014Rethinking Micro-Travel Shower23
So, for any speed of shower, we may work above 60% of
rated withVFD controlled system easily.
In this way, if the nozzle displacement was 0.7, 100.7,
200.7…700.7…; and we try to operate at 0.7mm
(conventional micro-travel), we won’t be able to get to
another regime of micro-travel like results.

24. Floating Speed Micro-Travel
But, suppose you are operating at 400.7 or 500.7mm nozzle
displacement and reduce speed of shower to 60%, you will
cross previous nozzle displacement figures of 300.7 and
400.7.
So, the shower will continuously float between one micro-
June 2014Rethinking Micro-Travel Shower24
So, the shower will continuously float between one micro-
travel condition to the other, thus ensuring your fabric will
be regularly cleaned at all positions.

25. Result
In other words, you will have an overlap of different fabric
cleaning patterns like shown in figure.
For this system, a PLC controlledVFD can be used.
June 2014Rethinking Micro-Travel Shower25

26. Another Approach
There could be another approach for shower operation that
overrides the guiding action.
Let us name it Intelligent Micro-Travel.
June 2014Rethinking Micro-Travel Shower26

27. Intelligent MicroIntelligent MicroIntelligent MicroIntelligent Micro----TravelTravelTravelTravel
If we are able to provide speed of shower as a sum of the
following two in every fabric rotation-
Movement of nozzle diameter
Movement of fabric itself
We’ll end up in a situation where effect of fabric guiding will
June 2014Rethinking Micro-Travel Shower27
We’ll end up in a situation where effect of fabric guiding will
be compensated by the shower.
I consider this as “micro-travel shower of future”.
It works as if a shower nozzle is‘following’ the fabric itself to
ensure best cleaning of fabric.

28. Intelligent Micro-Travel
The overall system will include a fabric position sensor, a
computer to evaluate the differential change in cross
direction position of fabric (CD speed), which finally sums
up the target shower speed with fabric CD speed and govern
the shower speed accordingly.
Today, fabric position sensors are easily available, and such
June 2014Rethinking Micro-Travel Shower28
Today, fabric position sensors are easily available, and such
computation is also not very difficult.
The only problem that may appear with conventional micro-
travel is the range of speed change.
But, we may be required to run shower at very slow and very
high speeds.

29. Intelligent Micro-Travel
We already know by operating micro-travel at higher speeds
according to approach of floating micro-travel, we can get rid
of too low showering speed without affecting micro-travel
performance.
In this way, intelligent micro-travel may make use of floating
June 2014Rethinking Micro-Travel Shower29
In this way, intelligent micro-travel may make use of floating
micro-travel technique.
The system may be named as-

30. Showering of the Future
Intelligent Floating Micro-Travel (IFµT)
June 2014Rethinking Micro-Travel Shower30
Intelligent Floating Micro-Travel (IFµT)

31. ThankYou.
June 2014Rethinking Micro-Travel Shower31
ThankYou.

32. About the Author:
Born in 1968, D K Singhal is B.E., M.E. (Pulp & Paper, 1993) from Dept. of Paper
Technology, University of Roorkee (now IIT, Roorkee, India). He is Certified Energy
Auditor and Chartered Engineer also.
With nearly 7 dozen publications on slideshare.net, energymanagertraining.com and
paperonweb.com, he has been constantly contributing to IPPTA(Indian Pulp & Paper
TechnicalAssociation). He is also serving IPPTA as a member of Editorial Board and had
been a member of Executive Committee.
June 2014Rethinking Micro-Travel Shower32
An initiative by D K Singhal, a cyber campaign initiated against unjustified targeting of paper
industry by “Idea” mobile, in their “Sirjee” advertisement campaign, after which this
advertisement was taken off air.
He also moderated aYahoo group,“PaperTechnology” with nearly 360 members from
India and abroad to discuss problems related to pulp & paper making for five years.
He can be contacted at deveshksinghal@gmail.com

33. Happy Showering!
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Please send your comments and feedback to:
D K Singhal
deveshksinghal@gmail.com