(170b) Inline Blending: Effect of Additive-Bulk Viscosity Difference on Mixing Length with Sulzer Smx & Smxplus in Transitional and Laminar Flow Regimes
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
North American Mixing Forum
Advances in Experimental Investigation of Mixing Processes
Tuesday, November 17, 2020 - 8:15am to 8:30am
The use of continuous, inline systems to dose, mix, sample and control injected additives is common in the process industries. However, published information describing the effect of additive (µa) and bulk (µb) viscosity differences on inline blending performance is sparse.
In this paper, experimental work carried out by BHR Group’s FMP consortium on the determination of mixing length (Lmix/D) in the transitional and laminar flow regimes using Sulzer SMX & SMXPlus at three scales (DN17, DN50 & DN100) is described. Test fluids were water, Newtonian 7M1 and non-Newtonian 7H4 aqueous CMC solutions and Newtonian glucose over the ranges 0.001Pa.s < ïAdditive < 3.9 Pa.s and 0.001 Pa.s < ïBulk < 1.03 Pa.s. The influence of additive viscosity (characterised using Re*), Remixer and viscosity ratio (µa/µb) were investigated over the ranges 0.1<Remixer<2000, 0.12<Re*<30000 and 1/1000<µa/µb <2200. Lmix/D measurements were made by visually observing the dispersion and blending of a coloured additive stream.
Comparison is made with the literature for blending with the Sulzer mixers in laminar and transitional flow. Both Re*critical and Remixer critical were influenced by mixer type. In transitional flow, the extent of the Lmix/D maximum observed between 10<Remixer<100 varied with Sulzer mixer type but in all cases where it was present it was very much smaller than that observed for the Chemineer Kenics. In transitional flow, Re* and not µa/µb governs Lmix/D along with Remixer. In laminar flow (Remixer<10), there was a dependence of Lmix/D on µa/µb as opposed to Re*.
With all mixers the laminar flow results demonstrated a strong influence of µa/µb on Lmix /D outside a fairly narrow range around µa/µb=1. The increase in Lmix/D when µa/µb <1 was always due to the presence of single or multiple strands of low viscosity additive (striations) which broke through Lmix/D=24 under some conditions.
In this paper, experimental work carried out by BHR Group’s FMP consortium on the determination of mixing length (Lmix/D) in the transitional and laminar flow regimes using Sulzer SMX & SMXPlus at three scales (DN17, DN50 & DN100) is described. Test fluids were water, Newtonian 7M1 and non-Newtonian 7H4 aqueous CMC solutions and Newtonian glucose over the ranges 0.001Pa.s < ïAdditive < 3.9 Pa.s and 0.001 Pa.s < ïBulk < 1.03 Pa.s. The influence of additive viscosity (characterised using Re*), Remixer and viscosity ratio (µa/µb) were investigated over the ranges 0.1<Remixer<2000, 0.12<Re*<30000 and 1/1000<µa/µb <2200. Lmix/D measurements were made by visually observing the dispersion and blending of a coloured additive stream.
Comparison is made with the literature for blending with the Sulzer mixers in laminar and transitional flow. Both Re*critical and Remixer critical were influenced by mixer type. In transitional flow, the extent of the Lmix/D maximum observed between 10<Remixer<100 varied with Sulzer mixer type but in all cases where it was present it was very much smaller than that observed for the Chemineer Kenics. In transitional flow, Re* and not µa/µb governs Lmix/D along with Remixer. In laminar flow (Remixer<10), there was a dependence of Lmix/D on µa/µb as opposed to Re*.
With all mixers the laminar flow results demonstrated a strong influence of µa/µb on Lmix /D outside a fairly narrow range around µa/µb=1. The increase in Lmix/D when µa/µb <1 was always due to the presence of single or multiple strands of low viscosity additive (striations) which broke through Lmix/D=24 under some conditions.