Rethinking micro travel shower

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

Transcript of Rethinking micro travel shower

  • 1. By: Rethinking MicroRethinking MicroRethinking MicroRethinking Micro----Travel ShowerTravel ShowerTravel ShowerTravel Shower By: D K Singhal
  • 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 getX pattern with clean and unclean areas. If shower movement is increased tonozzle 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 thei