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I am investigating what would be the most appropriate compressed air source (fan/blower/compressor) for designing a separate air compressor system.

The information is as follows:

  • the compressed air would be supplied to the lens of an industrial sensing instrument, which is mounted onto a pipe leading into a boiler's furnace

  • there are 12 instruments on each row and there are four rows in total (first row starts at 20m and there is an increase of 5m per row).

Purpose:

  • to provide sufficient pressure in order to prevent accumulation of dust on an instrumentation's lens

  • to provide sufficient flow to keep the entire pipe free of contaminants in the first place

Demand requirements:

  • flow (800 m3/hour) for all 84 instruments (100 m3/hour for one row of instruments) (8.6 m3/hour for one instrument)
  • pressure (40 mbar)

I know that the pressure demand is very little, it simply needs to be slightly above the furnace pressure. However, my concern is that the fans we have been using have not been able to provide sufficient pressure. Meanwhile, the flow is quite large.

Therefore, I am contemplating between a blower (more powerful fan) or a compressor (not sure if an air receiver would be necessary).

Which one would be more suitable (for both 100 m3 per hour and 800 m3/hour)?

What are the pros and cons of either (in terms of cost and space required and efficiency).?

If a compressor, which type of compressor (positive displacement, rotary, reciprocating) would be suggested?

Also, the duty cycle is 100% (all the tube needs to be cleaned at all times). If a compressor is used, is a receiver necessary?

How many instruments could be fed with one compressor?

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  • $\begingroup$ That is 220 litres a second... really? are all instruments to be cleaned at the same time or sequentially... $\endgroup$ – Solar Mike May 26 '18 at 10:22
  • $\begingroup$ All instruments should be cleaned at the same time. Yes, 220 liters per second if I had just one blower/compressor to clean all the instruments at once. What are your thoughts? $\endgroup$ – udidosa May 26 '18 at 10:26
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    $\begingroup$ First idea is to use a small compressor to charge a receiver tank and then drive the cleaning system from the tank at suitable intervals... $\endgroup$ – Solar Mike May 26 '18 at 10:40
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    $\begingroup$ The first paragraph after the bullet-points seems to have been cut off. $\endgroup$ – Wasabi May 26 '18 at 10:49
  • $\begingroup$ @SolarMike What are your reasons for choosing a small compressor over a blower or fan? how far should the receiver tank be placed from the small compressor? are you suggesting just one compressor and a receiver tank for all 84 flame monitors? (there are 4 rows each on different elevations of 2m each). $\endgroup$ – udidosa May 26 '18 at 10:57
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From skimming a (sadly german language) "blower bible", it seems that high pressure radial blowers are mostly used in the pressure range you need. Axial blowers appear to deliver a too low pressure, a compressor is certainly overblown for just 40mbar. However, I would suggest that due to your high volume flows you experience significant pressure losses and that may be why your existing blowers are not up to the task.

I don't understand your requirement to deliver 100 or 800 m³/h. A radial blower is the wrong tool to adjust over such a wide range of flow rates when you need mostly contant pressure, you you'd need to mount several in paralell and switch them on/off as needed.

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  • $\begingroup$ I forgot: The time honoured engineers way of solving these question is to talk to a likely supplier. Finding a good fit for a problem is what sales engineers are paif for. $\endgroup$ – mart Jun 8 '18 at 10:09
  • $\begingroup$ I will draw a proper P&ID and clarify my situation. Essentially I would just like to know if it is feasibly to have centrifugal blowers or use compressors (with air receivers) instead for this compressed air system. By the way, radial blower (centrifugal fan) IS the existing configuration and it can only produce about 50mbar of static pressure. $\endgroup$ – udidosa Jun 8 '18 at 10:12
  • $\begingroup$ then get different radial blowers. I've seen them for up to 300mbar. $\endgroup$ – mart Jun 8 '18 at 10:17

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