Processes With Integration

The input disturbance for a pulse test begins and ends at the same value. In terms of perturbation variables, the input m ) is initially zero and is returned to zero after some time,  

The perturbation in the output variable will usually also return to zero. Once in a while, however, a process will give an output curve that will not return to zero. This occurs if the process contains a pure integration element. For example, suppose the process is a tank, with the output variable the liquid level in the tank and the input variable the flow rate into the tank. Assume the flow rate out of the tank is constant. If a positive pulse in feed Bow rate is made, the liquid level will rise by the total incremental amount of material added during the pulse. The liquid level will stay at this new higher level, as sketched in Fig. 14.5. 

If the output signal does not return to zero, the integral in the numerator of Eq. (14.8) becomes infinitely large. This situation can be handled by separating 

First the gain of integration element is found from the final steadystate offset of from zero. Ax, and the integral of the input pulse. 

Separation of the output signal into contributions from the integrator and G transfer function. 

---

Integrated HF-regeneration in Process with integrated HF regeneration 112... 

We can see quickly that the system has unity gain and there should be no offset. The point is that integral action can be introduced by the process and we do not need PI control under such circumstances. We come across processes with integral action in the control of rotating bodies and liquid levels in tanks connected to pumps (Example 3.1, p. 3-4). 

Fig. 7.5. Tandem reactor concept for single-stage, high-conversion Claus process with integrated elutive regeneration.

The book is divided into three parts. Part I surveys concepts for heat-integrated chemical reactors, with special focus on coupling reactions and heat transfer in fixed beds and in fuel cells. Part II is dedicated to the conceptual design, control and analysis of chemical processes with integrated separation steps, whilst Part III focuses on how mechanical unit operations can be integrated into chemical reactors. 

FIGURE 19 Illustration of a two-stage aqueous two-phase partitioning process with integrated phase recycling. (From Huddleston and Lyddiatc.61 Copyright John Wiley Sons Limited. Reproduced with permission.)... 

Fig. 28 MTBE-synthesis—optimized process with integrated pervaporation. (View this art in Pervaporatior color at www.dekker.com.)...

Processes with integrating action most commonly encountered in a chemical process are tanks with liquids, vessels with gases, inventory systems for raw materials or products, and so on. 

Sample Processing with Integrated Microfluidic Systems... 

Outlook Extension to Other Synthetic Processes With Integrated Separation... 

The US company Mesoscopic Devices patented a method for an adsorptive desulfurization process with integrated regeneration in mobile fuel-cell systems... 

Schematic of a CLC process with integrated S-capture The oxygen carrier serves a dual purpose as oxidant and S sorbent, resuiting in the simultaneous capture of CO2 and of sulfur contaminants in separate effiuent streams from the fuei and air reactor, respectively.

Fig. 3.28 Flowsheet of paper production process with integrated metering points and addition sequences of various chemical additives. (DSR = dry strength resin, DSR-PAM = dry strength resin - poiacryiamide, OBA = opticai brightening agent, PAC = polyaiuminum chioride, RDA = retention drainage aid, WSR = wet strength resin.)...

The contribution of the sampling element is evident, in that the natural period of a dead-time process with integral control is 4t( without sanpling. Sampling adds 2 At to the period. The phase shift introduced by the sampling element can then be related to the period of the loop ... 

---