Process control, Chemical Engineering

1.      In the system shown schematically below, water is supplied to a spray nozzle by a gear pump with a constant output of 20 US gpm. The flow rate of water discharged through the nozzle is controlled by manipulating the flow of water re-circulated around the pump using a proportional-plus-integral controller. The set point of the controller is normally 14 US gpm but can vary between 9 and 18 US gpm. The flow sensor has a range of 0-20 US gpm and responds instantaneously to flow variations. The control valve has a CV of 3 US gpm/psi1/2, a time constant of 2 seconds, a linear installed characteristic and is current-to-close.

(a) What should be the action of She controller (reverse or direct)? Why?

(b) Would it be better to eliminate the recirculation loop and install the control valve immediately downstream of the pump? Why?

(c) If the pump discharge pressure is 100 psig when the control valve is closed, show that the flow rate across the nozzle is 8 US gpm when the control valve is wide open,

Notes: The valve and nozzle are the only significant flow resistances in this system. You may also assume that the pump suction port and the spray leaving the nozzle are at atmospheric pressure. The nozzle behaves as an orifice.

(d) What are the outputs of the controller and flow transmitter (in %) when the set point is 12 US gpm and steady-state has been achieved?

148_Process Control.png

Posted Date: 2/23/2013 1:00:34 AM | Location : United States







Related Discussions:- Process control, Assignment Help, Ask Question on Process control, Get Answer, Expert's Help, Process control Discussions

Write discussion on Process control
Your posts are moderated
Related Questions

the pilling bedworth ratio of iron is 1.77 why it not stable as per rulr

Objectives After doing this exercise you should be able to: 1. Describe the features of the preparation room of the lab you have visited, 2. Examine and evaluate a prepar

Soft-Baking Soft-baking is the step during which almost all of the solvents are separate from the photo resist coating. Soft-baking plays a very critical role in photo-imaging.

advantages of fuel cell over batteries

The importance of oil acid and base titration in the saponification value of oil

Give reason phosphate conditioning is suitable for all operating pressures

Where we have strong bond:ch20 ,h20,n20 and why?

Diffusion: Molecular diffusion, often known as simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by chance mole

Number of rooms, their size and allocation: Count the number of rooms including ancillaries (if any). Estimate their size and note the allocation of the main lab, preparatory room