Correction of residence time distribution measurements for short holding times in pasteurization processes

AbstractWhen in-line cells are used for obtaining residence time distribution (RTD) data from systems with short residence time, the signal distortion caused by the cell can compromise the results. A procedure to correct such distortion using convolution of signals in the time domain is proposed. First, the RTD of the cell is characterized, and then the E-curve of an RTD model is convoluted with the cell curve. The convoluted E-curve is fitted to the experimental data by adjusting the mean time and the model parameter. The procedure is demonstrated using a pilot scale pasteurization unit with two heaters, one cooler and six options of holding tube. Pulse experiments were performed, E-curves were obtained for each process step and five RTD models were tested. The convolution procedure was successful in removing the distortion caused by the detection cell, which was very significant for the holding tubes.

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Residence time distribution study in a pilot-scale liquid phase catalytic exchange (LPCE) column packed with a mixture of hydrophobic and hydrophilic catalysts

Applied Radiation and Isotopes ◽

10.1016/j.apradiso.2021.109840 ◽

2021 ◽

pp. 109840

Author(s):

Sunil Goswami ◽

Niranjan S. Shenoy ◽

Krunal A. Mistry ◽

Sulabh Gupta ◽

Vijay K. Sharma ◽

...

Keyword(s):

Liquid Phase ◽

Residence Time ◽

Time Distribution ◽

Residence Time Distribution ◽

Pilot Scale ◽

Distribution Study ◽

Catalytic Exchange

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Quantitative Analysis of Residence Time Distribution in Kenics Static Mixer

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.499.198 ◽

2012 ◽

Vol 499 ◽

pp. 198-202 ◽

Cited By ~ 2

Author(s):

Dan Jin ◽

Hai Ling Fu ◽

Jian Hua Wu ◽

Dan Sun

Keyword(s):

Quantitative Analysis ◽

Residence Time ◽

Time Distribution ◽

Residence Time Distribution ◽

Plug Flow ◽

Axial Direction ◽

Static Mixer ◽

Mixing Quality ◽

Experimental Approaches ◽

The Mean

The residence time distribution in Kenics static mixer is investigated using experimental approaches. Experimentally, RTD measure in SK with pulse tracer technology was used to characterize flow and mixing quality. The effect of velocity on the RTD was investigated for all sections. The results show that the flow in SK mixer tends to the plug flow along the axial direction when the velocity increases. The quantization analysis, the effect of factors on the mean residence time, is done by using the power function considering the numbers of mixer element, diameter, element aspect radio, and velocity. The validity of this function is testified by other experiments.

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Residence Time Distribution (RTD) of Particulate Foods in a Continuous Flow Pilot-Scale Ohmic Heater

Journal of Food Science ◽

10.1111/j.1750-3841.2009.01248.x ◽

2009 ◽

Vol 74 (6) ◽

pp. E322-E327 ◽

Cited By ~ 9

Author(s):

Sanjay Sarang ◽

Brian Heskitt ◽

Priyank Tulsiyan ◽

Sudhir K. Sastry

Keyword(s):

Residence Time ◽

Continuous Flow ◽

Time Distribution ◽

Residence Time Distribution ◽

Pilot Scale ◽

Ohmic Heater

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Self-similarity of fluid residence time statistics in a turbulent round jet

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.304 ◽

2017 ◽

Vol 823 ◽

pp. 1-25 ◽

Cited By ~ 12

Author(s):

Dong-hyuk Shin ◽

R. D. Sandberg ◽

E. S. Richardson

Keyword(s):

Reynolds Number ◽

Probability Density ◽

Residence Time ◽

Time Distribution ◽

Residence Time Distribution ◽

Mass Fraction ◽

The Self ◽

Similar Profile ◽

Self Similar ◽

The Mean

Fluid residence time is a key concept in the understanding and design of chemically reacting flows. In order to investigate how turbulent mixing affects the residence time distribution within a flow, this study examines statistics of fluid residence time from a direct numerical simulation (DNS) of a statistically stationary turbulent round jet with a jet Reynolds number of 7290. The residence time distribution in the flow is characterised by solving transport equations for the residence time of the jet fluid and for the jet fluid mass fraction. The product of the jet fluid residence time and the jet fluid mass fraction, referred to as the mass-weighted stream age, gives a quantity that has stationary statistics in the turbulent jet. Based on the observation that the statistics of the mass fraction and velocity are self-similar downstream of an initial development region, the transport equation for the jet fluid residence time is used to derive a model describing a self-similar profile for the mean of the mass-weighted stream age. The self-similar profile predicted is dependent on, but different from, the self-similar profiles for the mass fraction and the axial velocity. The DNS data confirm that the first four moments and the shape of the one-point probability density function of mass-weighted stream age are indeed self-similar, and that the model derived for the mean mass-weighted stream-age profile provides a useful approximation. Using the self-similar form of the moments and probability density functions presented it is therefore possible to estimate the local residence time distribution in a wide range of practical situations in which fluid is introduced by a high-Reynolds-number jet of fluid.

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Determination of the residence-time distribution in industrial dryer for the production of recycled polyester

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq200121047z ◽

2020 ◽

pp. 47-47

Author(s):

Felipe Zauli da Silva ◽

Izabella Bastos ◽

Rafael Perna ◽

Sergio Villalba Morales

Keyword(s):

Intrinsic Viscosity ◽

Residence Time ◽

Time Distribution ◽

Residence Time Distribution ◽

Industrial Processes ◽

Polyester Fibers ◽

Pulse Type ◽

The Mean

The study proposes the evaluation of the residence-time distribution (RTD) in-situ in an industrial dryer for the production of recycled polyester fibers (PES) from colorless polyethylene terephthalate (PET) flakes without interruption of the production. A disturbance of the pulse type was employed, in which the tracer (blue PET flakes) had previously been crystalized and its concentration was obtained according to the time at the dryer outlet. Additionally, analyses of intrinsic viscosity and crystallization percentage of the PET flakes (colorless and blue) and PES intrinsic viscosity and color force were performed. By RTD, the mean residence time (322.8 min), the variance (1305.4 min2), the standard deviation (36.1 min) and the relative error (1.5%) were obtained when compared to the theoretical residence time, indicating the absence of preferred paths or flake agglomerates in the equipment. Finally, the characterization demonstrated that there was no alteration in the parameters of product quality during RTD evaluation, confirming the potential of application of this methodology for diagnoses of continuous industrial processes.

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