Optimal operation of a tubular chemical reactor

A theoretical and experimental study was conducted on the optimal steady state operation of a jacketed, tubular, liquid-phase reactor in which consecutive second-order reactions occurred in turbulent flow. To verify the proposed mathematical model, diethyl adipate was saponified with sodium hydroxide in aqueous solution. The 150 ft. long reactor jacket was divided into 5, 30 ft. sections. Hot water flow rates in the jacket sections were chosen to maximize the concentration of monoethyl adipate ion at the reactor exit. The plug-flow model and a position-dependent heat transfer coefficient accurately described temperature and concentration profiles. The Pontryagin maximum principle was used to choose idealized reactor temperature and wall heat flux profiles which would maximize the exit concentration of monoester. The maximum principle was shown to be an effective tool for this type of reactor optimization. A technique is given for optimizing more complex reaction systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37363/1/690170619_ftp.pd

Kinetics of the saponification of diethyl adipate

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37368/1/690190635_ftp.pd

Modeling nutrient behavior in Wetlands

A simple mathematical model os developed which permites dynamic simulation of wetland hydrology and of nutrient-driven interactions between wastewater and the wetland ecosystem. Spatial variations due to surface water flow are described, and material balance calculations carried out for phosphorus, nitrogen, and chloride. A hydrology model, described elsewhere, predicts overland flow. Ecosystem phenomena are represented, using a one-dimensional, spatially distributed compartmental model. Compartments representing active parts of the ecosystem include soil, surface water, interstitial soil water, and various types of live biomass, standing dead and litter. Solutions to the partial differential equations which comprise these spatial models are demostrated using finite-difference methods. Computer simulations are compared with operating data from the Porter Ranch wastewater treatment facility at Houghton Lake, Michigan. They accurately predict solute concentrations in surface water, biomass growth patters, changes in the litter pool, and soil accretion rates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27451/1/0000491.pd

Optimal control of a continuous flow stirred tank chemical reactor

The time optimal control problem for jacket cooled continuous flow stirred tank reactor (CSTR) with an exothermic, irreversible, second-order, homogeneous, liquid-phase reaction (the saponification of ethyl acetate) was solved with the maximum principle and phase plane analysis. Both experimental studies and analogue computer simulation studies were conducted. The overall performance of the experimental system agreed very well with the performance of the corresponding system simulated on an analogue computer. However, there were enough differences in the observed and predicted operating states and switching curves to warrant the conclusion that the experimental performance can be significantly improved if experimental results are used to modify the results predicted with computer analysis. These differences were attributed to uncertainties in the model and the values of the model parameters as well as nonrandom (and unforeseen) measurement errors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37357/1/690160611_ftp.pd

Separation of nitrogen and methane via periodic adsorption

The periodic process utilizes a rapid pressure swing cycle in an adsorbent bed to effect the separation of gas mixtures. During the first portion of a cycle the compressed gas mixture flows into the adsorbent-filled column. Next, while the feed gas is restrained, an exhaust orifice is opened at the feed end of the column providing depressurization. The product stream is enriched in the component exhibiting the lowest coefficient of adsorption. A mathematical model based upon the assumption of instantaneous equilibrium between the gas phase and the adsorbed gas was formulated and solved to simulate the periodic, adsorption process. The measured nitrogen content of the product gas stream was found to correlate with the ratio of the product gas rate to the feed gas rate. At 24°C. the calculated pressure response, feed gas flow rate, and product gas composition correspond favorably with related experimental measurements for all values of the feed gas pressure, cycling frequency, and product gas flow rate within the ranges investigated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37359/1/690170219_ftp.pd

Impact tube gas velocity measurement at high temperatures

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37365/1/690180530_ftp.pd

Equilibrium-limited periodic separating reactors

A new unit operation is presented that utilizes a rapid feed pressure swing cycle in a bed packed with catalyst and adsorbent to effect both reaction and separation. This hybrid device combines features of a cyclic-steady-state pressure swing adsorber with those of a flow-forced catalytic reactor. Feed sequences for the periodic separating reactor (PSR) are those of rapid, single-bed pressure swing adsorbers (PSA). Only the case of extremely fast reactions is considered here. A perturbed reaction-sorption equilibrium model is formulated and solved for isothermal operation for different equilibrium constants and reaction stoichiometries. The capacity and separation performance for an equilibrium-limited PSR (EPSR) can be of the same order of magnitude as PSA alone. For reactions involving a single reactant or single product, the principal component in a particular exit stream depends upon both the reaction stoichiometry and feed fraction of the process cycle. The pressure dependency of the reaction equilibrium expression is the cause of separation reversals as parameters are varied.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37397/1/690330810_ftp.pd

Periodic separating reactors: Experiments and theory

The novel combination of a pressure swing adsorber (PSA) with a periodic flow-forced packed-bed reactor is explored. The device provides integral component separation and reaction. Feed sequences studied for the periodic separating reactor (PSR) were those of rapid, single-bed pressure swing adsorption (RPSA). The experimental investigation employed CO oxidation over a packed bed of supported platinum catalyst and molecular sieve adsorbent. A reaction rate limited model is formulated and solved for a variety of irreversible and reversible reactions. The presence of irreversible chemical reaction is shown to greatly enhance the separation achievable by RPSA alone. For a wide range of inlet CO/O 2 ratios, CO 2 production could be increased up to two times over steady-state plug-flow reactor operation, while providing a recycle stream without phase change or extractive procedures. Selectivity and conversion improvements were predicted for multiple reaction systems. Other unusual features of operation, such as separation reversals, were also predicted and observed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37406/1/690350514_ftp.pd