3 replies to this topic

[modianurag]

We are scrubbing gas+fine powder after spray drying in series of 2 venturi scrubber. The issue is that we can see a visible stack plume even from a great distance. HCL content in gas is within pollution norms.

 

Please can anyone suggest how can we work towards reducing the stack plume.

I searched on net and got 2 approaches.

1. Reheating stack plume to avoid condensation which results in plume

2. Reducing water content of stack plume.

 

Kindly suggest which route will be better?

Edited by modianurag, 11 August 2016 - 05:00 AM.

[rilmehta]

Hello Anurag

 

I believe reheating would be a simpler option ( having some heating coil inthe vent)

compared to removing the moisture directly as at any temperature it would be at saturation and it would only be helpfull if you follow heating & cooling cycle.

Also are you sure that this plume is not due to mist or droplets due to higher velocities? If thats the case than you can have a possibility of demister.

[Saml]

When you see "a visible stack plume even from a great distance" does it means that the plume stays visible for long distance without complete evaporation, or that the stack can be seen from long distance.

 

In the first case, it may mean that you have dissolved solids, the droplets concentrate until the water activity is in equilibrium with air humidity and don't completely evaporate. Here, your options are, a better demister (as rilmehta said above), scrubbing with a more diluted solution, adding a third scrubbing stage. Reheating may help, but is difficult to predict the effect with simple rules of thumb.

 

 

If it is only that the stack is in a conspicuous location, reheating or mixing with a hotter stream will reduce the visual impact. The calculation for eliminating fogging from stacks requires specific models. You may have an exit temperature that is above dew point, but when it mix with cold air it causes a fog plume anyway.

 

The following is a link to a commercial site I have no affiliation with, nor I have worked with them, just seemed illustrative to this issue.

 

http://www.envirowar...tted-by-stacks/

[modianurag]

The plume is visible from a distance and as it rises up till a certain distance say 6-7 meter or so, its no longer visible.

 

Based on your inputs, a heating coil in the stack may be the easier way forward. Thanks to both of you for the valuable input.

 

Any reference to vendors who would be able to provide with such stacks?