Cresap Pilot Plant CSF Process operations were simulated in cycling operations of a 10 Ib of coal/h continuous unit. Mass spectral and H NMR analyses indicated essentially steady-state operation in the third of the four completed cycles. Integrated gravity settling produced 0.22 wt % ash extract. Using an antisolvent did not improve deashing. Introduction and SummaryPittsburgh Seam 8 coal was liquefied by the Consol Synthetic Fuel (CSF) donor solvent process and deashed via gravity settling at 600 O F with and without an antisolvent. These continuous 10 lb coal/h tests were done to provide guidance for the 20 TPD Cresap CSF Pilot Plant. Highlights of these experiments follow.Mass spectral and NMR analyses showed that the CSF solvent closely approached steady state in three cycles of integrated operation and that tetralins, hydrophenanthrenes, and hydropyrenes were the predominant hydrogen donors.Extract from steady-state operations contained 0.22 wt 70 ash, which slightly exceeds the EPA specification of 0.20%. The low settler upflow velocity (0.3 in./min) used translates to about 34 40-ft diameter settlers for a commercial plant processing 25 000 TPD coal.Using paraffinic anti-solvent to precipitate a fraction of

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This paper presents a nonequilibrium mathematical model of a vapor-liquid separator. The model is used 0 s the focus of a computer simulation control study conducted to provide the foundation for applying recent multivoriote control developments to distillation systems.Greenfield and Word's structural analysis was found to provide reasonably goad feedforward ond decoqpling control of pressure, liquid temperoture, and liquid pressure. Because of implicit relationships between product composition variables and their monipulative inputs, structural analysis was inopplicoble when these composition variables were among the controlled variobles.A method is presented which provides feedforward and some decoupling control for linear multivarioble systems despite the existence of implicit relationships between controlled variables and their monipulotive inputs. It is seen however that genuinely decoupled servo action on isolated state voriobles requires control through derivatives and thus an exponsion of state space.The effective control of a multivariable system is complicated by the dynamic intercoupling or interaction between the variables of the system. If this interaction can be removed, single variable feedback control theory can be independently applied to each control loop of the multivariable system. Early workers (2, 6, 10) used dynamic matrix operands to produce a one-to-one correspondence between the elements of the set point vector and the elements of the controlled variable vector of a linear multivariable system. Morgan (14) found that nondynamic controllers would give noninteracting servo control if all of the state variables of the system were monitored. Planchard ( 1 5 ) showed that both dynamic and nondynamic controllers derived from a linear system model could produce good quality noninteracting control when used on an experimental system which contained significant nonlinearities.The efficacy of feedforward controllers in maintaining the controlled variables of a linear multivariable system invariate despite upsets in one or more of the system inputs has been demonstrated by Luyben and Lamb ( 1 3 ) and Tinkler ( 1 7 ) . Bollinger and Lamb (1) advanced control technology a step further by combining feedforward and feedback control for multivariable systems. However, the feedback controllers were incapable of removing system intercoupling. More recently, Foster and Stevens ( 5 ) and Greenfield and Ward (8, 9) have presented methods which completely decouple linear multivariable systems while simultaneously providing for feedforward control of measurable input disturbances. Greenfield and Ward's powerful structural analysis (8, 9) represents the state of the art for the feedforward and decoupling control of systems for which such control is possible. However, as pointed out by Falb and Wolovich ( 4 ) and Gilbert (7), not all linear multivariable systems can be dynamically decoupled by state variable feedback.To provide the groundwork for applying feedforward and dynamic decoupling control to distillatio...

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