Parametric Pumping: Dynamic Principle for Separating Fluid Mixtures

Wilhelm, Richard; Rice, Adrian; Bendelius, A. R.

doi:10.1021/i160017a028

Cited by 112 publications

(33 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This method is similar in some respects to parametric pumping (PP) (Wilhelm et al, 1966) and sedimentation field-flow fractionation (SFFF) (Giddings et al, 1974). It employs cyclic flow as does PP.…”

Section: Scopementioning

confidence: 99%

Separation of fine particle dispersions using periodic flows in a spining coiled tube

Papanu¹,

Adler²,

Gorensek³

et al. 1986

AIChE Journal

View full text Add to dashboard Cite

show abstract

Section: Scopementioning

confidence: 99%

Separation of fine particle dispersions using periodic flows in a spining coiled tube

Papanu¹,

Adler²,

Gorensek³

et al. 1986

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…The name parametric pumping was coined by Wilhelm (22), who described an adsorption-based separation process involving reversing flows. When the flow is in one direction a parameter, such as temperature, which influences adsorptivity, is at one value, while the parameter is changed to another value when the flow is in the opposite direction.…”

Section: Gas-adsorptionmentioning

confidence: 99%

Gas-Adsorption Processes: State of the Art

Keller¹

1983

ACS Symposium Series

View full text Add to dashboard Cite

Gas-adsorption processes are used for a wide variety of separations throughout the chemical and other industries. But to effect various separations, quite different process embodiments are necessary. These differences are primarily concerned with the method by which the adsorbent is regenerated. This choice is influenced by the percentage of adsorbate in the feed, ease of desorption and degree of separation required. In this paper, we discuss temperature-swing, inert-purge, displacement-purge, pressure-swing, parametric-pumping, chromatographic and other cycles; the separations for which they are best suited; and their limitations. Commercial examples are given. Finally, predictions are made as to future improvements in various technologies as well as to what new separations will be amenable to adsorption separation.Gas-adsorption processes involve the selective concentration (adsorption) of one or more components (adsorbates) of a gas (or vapor) at the surface of a microporous solid (adsorbent).The attractive forces causing the adsorption are generally weaker than those of chemical bonds and are such that, by increasing the temperature of the adsorbent or reducing an adsorbate's partial pressure, the adsorbate can be desorbed.The desorption step is quite important in the overall process.First, desorption allows recovery of adsorbates in those separations where they are valuable, and second, it permits reuse of the adsorbent for further cycles.This paper is concerned with a broad range of gas-adsorption processes as practiced in the organic-chemical, petroleum, natural-gas and allied industries.Emphasis will be on a description of processes rather than a review of adsorber design 0097-6156/83/0223-0145$07.25/0

show abstract

“…Significant recent research interest has been focused on possible advantages of intentional unsteady state processing Among the potential benefits of periodic operation are increased reactor selectivity (see Bailey, 1974) and enhanced separation (see, for example, Robinson and Engel, 1967;Wilhelm et al, 1968). All previous work, however, has considered only the question of periodic process design: how should some manipulated variable be oscillated to achieve optimum performance?…”

Section: Scopementioning

confidence: 99%

“…Among the indirect profit indicators employed in earlier studies are reactor selectivity (Bailey, 1974) and column separation factor (Wilhelm et al, 1968). Ideally, maximum profit should remain the goal for an operating system which is subjected to disturbances.…”

Section: Conclusion and Significancementioning

confidence: 99%

Regulation of lumped periodic processes

Liaw

Bailey

1974

AIChE Journal

View full text Add to dashboard Cite

When a periodic process is disturbed, control action may be necessary to maintain satisfactory performance. Regulating controls to achieve this objective can be synthesized by solving a linear-quadratic optimization problem with periodic coefficients. Generalized proportional and proportional-integral feedback regulators developed in this manner are tested by simulating a cyclic reactor. Very satisfactory control is achieved for 10% step disturbances in reactor feed conditions although the results are sensitive to the choice of manipulated variables. J . 4 . SCOPESignificant recent research interest has been focused on possible advantages of intentional unsteady state processing Among the potential benefits of periodic operation are increased reactor selectivity (see Bailey, 1974) and enhanced separation (see, for example, Robinson and Engel, 1967;Wilhelm et al., 1968). All previous work, however, has considered only the question of periodic process design: how should some manipulated variable be oscillated to achieve optimum performance? Once a suitable design has been developed, another problem which we call periodic process regulation must be resolved: What control manipulations are necessary when the operating cyclic system is disturbed by an unexpected change in its environment? This paper presents one approach to this problem for systems described by ordinary differential equations, By adopting the objective of maintaining design conditions and assuming that deviations from these conditions are sufficiently small, regulating controls can be synthesized in feedback form by solving a time-varying linearquadratic optimization problem (see Edgar et al., 1973). Employing this approach, generalized proportional (P) and proportional-integral (PI) regulators are developed. A continuous-flow stirred tank reactor (CSTR) in which parallel reactions occur is employed to test these regulating controls. In the absence of disturbances, periodic variations in heat flux to the reactor provide greater selectivity for the desired product than can be obtained by steady state operation.Step disturbances in feed conditions can unfavorably alter the reactor's performance. The effectiveness of flow rate or heat flux manipulation in counteracting these upsets is investigated using simulation studies. CONCLUSIONS AND SIGNIFICANCEA generalized proportional-integral control employing heat flux as the regulating variable effectively returns the cyclic reaction system to its design specifications following 10% step decreases and increases in feed concentration and temperature. This can be seen by comparing the response with this controller, denoted PI-Heat, to the periodic fluctuations of the reference design (undisturbed) process in Figures 2, 4, and 5. Proportional control using heat flux regulates the reactor almost as well but requires more extreme fluctuations in the manipulated variable as shows that flow rate is far less effective than heat flux in maintaining reference design conditions. Without a regulating control these distu...

show abstract

Parametric Pumping: Dynamic Principle for Separating Fluid Mixtures

Cited by 112 publications

References 0 publications

Separation of fine particle dispersions using periodic flows in a spining coiled tube

Separation of fine particle dispersions using periodic flows in a spining coiled tube

Gas-Adsorption Processes: State of the Art

Regulation of lumped periodic processes

Contact Info

Product

Resources

About