Tag: concrete

Dust Suppression with an EXAIR Atomizing Nozzle

Published on by Lee EvansLeave a comment
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An EXAIR Atomizing Nozzle used to minimize dust in the feed bowl of a cement mixer.

One of the most difficult aspects of handling and working with dusty materials is suppression of airborne contaminants.  Small particles can easily become a dust cloud, minimizing visibility and decreasing the quality of working conditions.  This then leads to lower productivity, low morale, and a missed opportunity to maximize the potential of personnel and equipment.

Our distributor in New Zealand recently assisted one of their customers facing this set of problems when working with cement and microsilica as it was poured into a mixer.  An exhaust fan was in place, but failed to extract the dust sufficiently, so a new approach was needed to minimize the dust.

 

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An AN2010SS No Drip Atomizing Nozzle provides the needed dust suppression in this application.

 

The solution was to use an EXAIR AN2010SS No Drip Internal Mix Atomizing Nozzle, shown above in the red box, to produce an atomized water mist.  The dust produced during pouring is captured by the small droplets of atomized water produced with this nozzle, reducing the dust and allowing proper use of the mixer.

 

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The 9218 Stay Set Hose positions the atomizing nozzle where it needs to be.

 

In order to position the nozzle exactly where it needs to be, an 18” Stay Set Hose, shown above with the red arrow, was used to position the nozzle.  This hose is built specifically to have “memory” of the desired position, allowing for quick, easy, and repeatable position of the nozzle attached to the hose.

This simple setup is controlled through a timer to ensure water and compressed air use realize maximum efficiency.  It’s an easy solution to a painful problem for this customer.

If you’d like to explore how an EXAIR solution can solve problems in your facility or application, please contact an EXAIR Application Engineer.

 

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

How Do You Make Cement? Start with Clinkers

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Last week I wrote about the use of the Atomizing Nozzles to create a fog for wet room curing of concrete samples poured during road construction.  This week, I had the opportunity to work with another customer about concrete, but this time it was regarding the the manufacturing process.  Invariably, I always learn something new , and for this interaction, it was the term ‘clinkers.’

Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement that hardens over time.  The customer I was working with was a cement manufacturer.  Cement production is basically a 2 step process – 1) clinker is produced from raw materials and 2) cement is produced from cement clinker.

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Typical Cement Clinkers

To make the clinker (step one), several powder raw materials are fed into a rotary kiln.  The kiln is heated to very high temperatures, and when the materials are mixed and heated, new compounds are formed and hydraulic hardening occurs resulting in the formation of the clinker.

My customer needed a way to clean off the residual dust left on the transport belts, after the clinkers were transported to storage silos.  Due to the high temperatures in the area, we focused in on the EXAIR Type 303 Stainless Steel model of the Super Air Knife, as it can withstand temperatures up to 800°F.  The customer went with (3) of the Super Air Knife Kits, which include the Shim Set, Auto Drain Filter Separator, and Pressure Regulator w/ Gauge, for easiest installation with maximum functionality.

The Super Air Knife is a tried and true product for cleaning, drying, cooling and general blowoff for conveyors.  And with widths up to 108″ available, any size conveyor can be handled.

To make cement (step two), the clinker is ground into fine powder with other ingredients including gypsum (calcium sulphates) and possibly additional cementitious (such as blastfurnace slag, coal fly ash, natural pozzolanas, etc.) or inert materials (limestone). It is then stored or packaged and ready to be made into concrete.

To discuss your application and how an EXAIR Super Air Knife can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Atomizing Nozzles Create Fog for Wet Room Testing

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Recently, I was working with a customer that has purchased several of the EXAIR Atomizing Spray Nozzles, specifically the model Aw5020SS.  The customer had another project coming up and needed two more nozzles. I inquired about the application and we discussed at length the way the nozzles are being used.

When a concrete road is being poured, several sample forms are poured during the process. The local Department of Transportation takes the samples and cures them in a wet room for 30 days, and then performs tensile testing, to confirm the concrete meets the strength requirements.  The wet room must be kept at 23°C (73.4°F) and 100% Humidity during this time frame.  The EXAIR model AW5020SS Atomizing Nozzles are used to provide the moisture that ensures the room humidity conditions are met and maintained.  Because the droplets are very fine, the effect of a fog is achieved, with the water droplets suspended in the air, keeping the humidity at 100%.

Atomizing spray nozzles are capable of producing very fine droplet sizes.  A typical rain drop is 6000 microns in diameter, standard liquid nozzles produce droplets ranging from 300-4000 microns.  The EXAIR Atomizing Nozzles produce droplets from 20-100 microns!

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Model AW5020SS

Droplet  sizes can be adjusted by varying either the liquid pressure or air pressure. Increasing the air or decreasing the liquid pressure will generally produce a smaller droplet size.

EXAIR manufactures (3) types of Atomizing Nozzles – Internal Mix, External Mix, and Siphon Fed, in both 1/4 NPT and 1/2 NPT sizes. Maximum liquid viscosity is 800 cP. Flow rates range from 0.6 GPH up to 303 GPH, so we’ll be able to find one that meets your flow requirements.

To discuss your application and how an EXAIR Atomizing Nozzle can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

Send me an email
Find us on the Web
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Twitter: @EXAIR_BB