Answer / nimesh

PID means proportional integral deerivative.
PID used to eliminate offset & for least maximum deviation.
OR
PID means piping & instrumentation.
PID used to eloborate plant layout with all instrumentation.

Answer / murthy

PID- proportional integral and derivative
there different types of controlling techniques,
combinations of these parameters in designing controllers.
it depends on what type of errror occurs in ur
system,deviation from ur set point,time u want ur
controller to take action.
if u want quick acting one then go for only proportional
controller,the disadvantage is you get higher deviation.
if u want to minimze error (measured-set value) go for
integrated controller,disadvantage-your final forms cyclic
fluctuations.
derivative is taken into acount when u want zero cycling
always it is not suggeted to go for PID controller,as it is
costly,ur system may not need it at all.for eg if u want to
control level of a tank with 2 feeds and one withdrawl u
dont need integral action so u can go for PD controller
only

Answer / r sridhar

PID is Proportional Integral and derivative Control.this
closed loop control system is the basis on which a DCS
works.In a Distributed Control system environment you will
find almost all the controllers are of PID type of
Controllers.

Answer / baskar

pid are the controller where it can used in closed loop
system or non-interacting level system.

why distillation of water takes more time than toluene ,eventhough the later boiling point is more than water ?

3 Answers  

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In a crusher where is the energy provided to it is used up for?

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MASS TRANSFER - EXAMPLE 4.3 : According to Adolf Eugen Fick (1829 - 1901) : rate of diffusion v increases with less wall thickness t, increased area A and decreased molecular weight of a fluid M. The diffusion constant D decreased with increasing M. (a) By assuming v, t, dP, A, M and D changes proportionally of each other, find the equation of v as a function of t, dP, A and D. (b) The ratio of self diffusion constant D, at T = 273 K and P = 0.1 MPa, for gases B and C are 1.604 : 0.155. If only 2 gases exist in such a system : hydrogen and nitrogen, find the type of gas for B and C with reference to their molecular weights M. (c) By using the equation of kinetic energy 0.5 MV = constant where V = square of v, find the ratio of V for B and V for C, or V(B) / V(C), as a function of M(B) and M(C), where M(B) is molecular weight of B and M(C) the molecular weight of C : Graham's Law of Diffusion.

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Question 49 - According to rules of thumb in chemical process design, consider the use of an expander for reducing the pressure of a gas when more than 20 horsepowers can be recovered. The theoretical adiabatic horsepower (THp) for expanding a gas could be estimated from the equation : THp = Q [ Ti / (8130a) ] [ 1 - (Po / Pi) ^ a ] where 3 ^ 3 is 3 power 3 or 27, Q is volumetric flowrate in standard cubic feet per minute, Ti is inlet temperature in degree Rankine, a = (k - 1) / k where k = Cp / Cv, Po and Pi are reference and systemic pressures respectively. (a) Assume Cp / Cv = 1.4, Po = 14.7 psia, (temperature in degree Rankine) = [ (temperature in degree Celsius) + 273.15 ] (9 / 5), nitrogen gas at Pi = 90 psia and 25 degree Celsius flowing at Q = 230 standard cubic feet per minute is to be vented to the atmosphere. According to rules of thumb, should an expander or a valve be used? (b) Find the outlet temperature To by using the equation To = Ti (Po / Pi) ^ a.

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Question 102 - (a) As an approximation, let v = Zc / 137 where v is the radial velocity for 1 s electron of an element, c is the speed of light, Z is the atomic number. For gold with Z = 79, find the radial velocity of its 1 s electron, in term of c and percentage of the speed of light. (b) As an approximation, let A x A = 1 - Z x Z / 18769 where A is the ratio of the relativistic and non-relativistic Bohr radius. Find the value of A.

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Can you pls tell me how to calculate the amphere rating of cable in case of three phase supply but all load is single phase

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PROCESS CONTROL - EXAMPLE 6.2 : A stream with volumetric flow rate Q enters a cylindrical tank and a stream with volumetric flow rate q exits the tank. The fluid has a constant heat capacity and density. There is no temperature change or chemical reaction occurring in the tank. Develop a model for determining the height of the tank, h. Let V is the volume, A is the cross sectional area, r is the density, m is the mass, where V and A are for the tank, r and m are for the fluid. The rate of mass of fluid accumulation, dm / dt = (Q - q) r. Prove the model to be dh / dt = (Q - q) / A.

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Hi this is aparna.............can any one send drdo question papers on my email id-aparna_patna08@yahoo.com Thanks in advance

2 Answers   DRDO,

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Is there a difference in mtd (mean temperature difference) between 'e' and 'j' (divided flow) type shell and tube heat exchangers?

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As a chemical engineer, which are the subjects to whom more importance should be given....for technical interview.

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how can we calculate reflux ratio? what is difference between internal reflux and external reflux?

0 Answers   Sabic,

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Explain the difference between cfm (cubic feet per minute) and scfm (standard cubic feet per minute)?

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