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Headloss of a static mixer

Headloss of a static mixer

Headloss of a static mixer

(OP)
Hello all, at a wastewater treatment plant a static mixer will be used to mix a thin suspension (~1m³/h, <2% solids) into the wastewater stream (~300m³/h). If possible I want to know the magnitude of the headloss of my mixer. 100mbar? 1 bar? 5?
DN350 pipe.

I don't yet have hard numbers for the mixing quality required, since the mixer is upstream of a stirred tank I don't think I need to achieve a very high quality (whatever that means). My thinking is that a huge determining factor (alongside final quality) will be the ratio between the two flows.

In mixing (basically) water into water, a helical mixer is used - correct?

Edit to add:
Perry states that headloss of static mixers is usually given as a factor K, ration between headloss mixer and headloss empty pipe. K is between 6 and "several hundred". At my flowrates, headloss of 1m pipe is ~0.2 mbar I would expect single digit mbar headloss for my mixer - correct?


RE: Headloss of a static mixer

It is difficult to give you any advice because at this stage it appears that you don't really know what you want. If as you say you don't require much mixing, injection before a couple of elbows or a valve that is slightly closed may give you enough turbulence to do the mixing required. Alternatively you might want to install an orifice plate or something similar between flanges and then inject upstream.
The headloss of the mixer will be dependent upon the amount of mixing the device is intended to impart and is normally carefully designed based on pipe size , flow velocity and the mixing energy required. A static mixer supplier should be able to give you some detail on this.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

RE: Headloss of a static mixer

Just to add , an inline helical mixer probably is not best in wastewater if it the pipeline contains any solids , rags , hair etc as the mixer will probably clog and foul up with the solids.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

RE: Headloss of a static mixer

(OP)
At this stage I only need to know the influence of the static mixer on the pressure I need to inject my suspension - which, if I'm not off by to orders of magnitude, will be negligible.
Re. solids, the whole affair is downstream of filter.

RE: Headloss of a static mixer

Yes the pressure increase will relatively small and will have little impact on your injection pump.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

RE: Headloss of a static mixer

(OP)
Ok, if I use the admixer sheet I arrive at ~8psig = ~ 0.5 bar for my application. past time to call a supplier. thanks bimr.

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