Process control, Chemical Engineering

Assignment Help:

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


Related Discussions:- Process control

Molar flow rate., 100 mol/hr of methane reacts with steam to produce CO2 in...

100 mol/hr of methane reacts with steam to produce CO2 in a main reaction of the reformer. The amount of steam used is 12.5% excess based on this main reaction. Some of the methane

Phase diagram, what is proportion of austenite present at 724 centigrade

what is proportion of austenite present at 724 centigrade

Concentrate a naoh solution , It is desired to concentrate a NaOH solution ...

It is desired to concentrate a NaOH solution from 12.5 % to 40% in a double effect evaporator. 50,000 lb/hr of feed solution enters the evaporator at 120 o F, and steam at 15 psig

Thermal spelling, Thermal spelling: The breaking or cracking or peeling of...

Thermal spelling: The breaking or cracking or peeling off the refractory is known as spelling. A good refractory must show a good resistance to thermal spelling. Thermal spelling

Material balance, Strawberries contain about 20 wt% solids and 80 wt% water...

Strawberries contain about 20 wt% solids and 80 wt% water. To make strawberry jam, crushed strawberries and sugar are mixed in a 40:60 mass ratio, and the mixture is heated to evap

Chemical bonding, Why protons doesn''t react which each other?

Why protons doesn''t react which each other?

Applications of diffusion, Applications of Diffusion is of fundamental sig...

Applications of Diffusion is of fundamental significance in many disciplines of mechanical, electronics, chemistry, and biology. Some example applications of diffusion: Sin

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd