Last Updated 04 Sep 2020

Problems of Process Control

Words 624 (2 pages)
8 views
Table of contents

Problem

A thermometer having a time constant of 0. min is placed in a temperature bath and after the thermometer comes to equilibrium with the bath, the temperature of the bath is increased linearly with time at the rate of I deg C / min what is the difference between the indicated temperature and bath temperature (a) 0. 1 min (b) 10. min after the change in temperature begins. (c) What is the maximum deviation between the indicated temperature and bath temperature and when does it occurs. (d) plot the forcing function and the response on the same graph. After the long enough time buy how many minutes does the response lag the input?

Solution

Order custom essay Problems of Process Control with free plagiarism report

GET ORIGINAL PAPER

Consider thermometer to be in equilibrium with temperature bath at temperature (a) the difference between the indicated temperature and bath temperature

Problem

Determine the transfer function H(s)/Q(s) for the liquid level shown in figure below Resistance R1 and R2 are linear. The flow rate from tank 3 is maintained constant at b by means of a pump; the flow rate from tank 3 is independent of head h. The tanks are non-interacting.

Solution

Balance on tank 3 gives writing the steady state equation Subtracting and writing in terms of deviation Taking Laplace transforms

We have three equations and 4 unknowns (Q(s),H(s),H1(s) and H2(s). So we can express one in terms of other. From (1) Combining equation 4,5,6

Problem

Heat transfer equipment shown in fig. consists of tow tanks, one nested inside the other. Heat is transferred by convection through the wall of inner tank.

  1. Hold up volume of each tank is 1 ft3
  2. The cross sectional area for heat transfer is 1 ft2
  3. The overall heat transfer coefficient for the flow of heat between the tanks is 10 Btu/(hr)(ft2)(oF)
  4. Heat capacity of fluid in each tank is 2 Btu/(lb)(oF)
  5.  Density of each fluid is 50 lb/ft3 Initially the temp of feed stream to the outer tank and the contents of the outer tank are equal to 100 oF.

Contents of inner tank are initially at 100 oF. the flow of heat to the inner tank (Q) changed according to a step change from 0 to 500 Btu/hr. (a) Obtain an expression for the laplace transform of the temperature of inner tank T(s). (b) Invert T(s) and obtain T for t= 0,5,10, U

Solution

(a)For outer tank Substituting numerical values Now Ti(s) = 0, since there is no change in temp of feed stream to outer tank. Which gives For inner tank

Problem

The thermal system shown in fig P 13. 6 is controlled by PD controller. Data; w = 250 lb/min; ? = 62. 5 lb/ft3; V1 = 4 ft3, V2=5 ft3; V3=6ft3; C = 1 Btu/(lb)(°F) Change of 1 psi from the controller changes the flow rate of heat of by 500 Btu/min. the temperature of the inlet stream may vary. There is no lag in the measuring element. (a) Draw a block diagram of the control system with the appropriate transfer function in each block. Each transfer function should contain a numerical values of the parameters. b) From the block diagram, determine the overall transfer function relating the temperature in tank 3 to a change in set point. (c ) Find the offset for a unit steo change in inlet temperature if the controller gain KC is 3psi/°F of temperature error and the derivative time is 0. 5 min. Fig. (1) (b)

Problem

For the control shown, the characteristics equation is s 4 +4 s3 +6 s 2 +4 s +(1 + k) =0 (a) Determine value of k above which the system is unstable. (b) Determine the value of k for which the two of the roots are on the imaginary axis.

Solution

s 4 +4 s3 +6 s 2 +4 s +(1 + k) =0 For the system to be unstable.

Problems of Process Control essay

This essay was written by a fellow student. You can use it as an example when writing your own essay or use it as a source, but you need cite it.

Get professional help and free up your time for more important courses

Starting from 3 hours delivery 450+ experts on 30 subjects
get essay help 124  experts online

Did you know that we have over 70,000 essays on 3,000 topics in our database?

Cite this page

Explore how the human body functions as one unit in harmony in order to life

Problems of Process Control. (2017, Jan 15). Retrieved from https://phdessay.com/problems-of-process-control/

We use cookies to give you the best experience possible. By continuing we’ll assume you’re on board with our cookie policy

Save time and let our verified experts help you.

Hire writer