Analysis of Electroplating Bath Control System: Mechanical Engineering

This assignment solution provides a detailed analysis of an electroplating bath control system. It begins with the selection and explanation of a K-type thermocouple for temperature measurement, coupled with a digital PID temperature controller and a capacitance level sensor. The solution then explores different flow measurement techniques, including orifice plates, U-tube manometers, and Venturi flow meters, and provides specifications for an electromagnetic flow meter. The document further discusses the principles and applications of various flow meters like ultrasonic and Coriolis mass flow meters, along with the types of flow profiles and the concept of head in fluid dynamics. It also covers selection criteria for flow meters, variable-area flow meters, turbine flow meters, and thermal mass flow meters. The assignment includes a calculation of mass flow rate and a discussion on positive displacement meters and metering pumps. Finally, it concludes with an analysis of pressure measurement using Bourdon tubes and pressure transmitters, including a case study on level measurement.

Part A
13) 1) Temperature Sensor: K-type Thermocouple
Transmitter: Omega TX13 in head mounting thermocouple transmitter
PID Controller: Digital PID temperature controller
Table 1: Specifications of Digital PID temperature controller
Input sensor Universal
Model Name and Number DQ 100 UN
Control type High Limit
Type Automatic
Temperature range 1200℃
Low level detection device: Capacitance measurement Probe
2) Explanation:
i. K-type Thermocouple could be used, which measures a broad range of temperature
detection (-200℃-1260 ℃). The temperature sensor is usually Ni plated that promotes
an excellent resistance towards corrosion. In order to measure the uniform temperature
within the electroplating bath, the thermocouple should be placed within a glass tube
filled with water.
ii. The temperature transmitter Omega TX13 has the capacity to get integrated with the K-
type thermocouple. This transmitter converts the temperature to a standard signal of 4-20
mA. The temperature sensor along with the transmitter will be provided with the
protection head supported with the stainless steel (Tao Liu & Furong Gao, 2009).
iii. Digital PID temperature controller supports Auto tunings and could also work with the
Pt100/J/K, R, S, T type thermocouple. PID controller takes significant action and also
delivers control output at desired levels. PID controller maintains the output in a way of
promoting much minimized error among the process variable and the set point in closed
loop operations.
iv. Capacitance level sensor could handle point or continuous level measurement. Usually
the sensor will be in the form of a probe type that converts the change in capacitance vale
in the form of analog signals. They are able to withstand high temperature and non-
corrosive. When the liquid in the tank falls below a minimum range the sensor detects
and could provide it in the form of signal. PTFE model could be used to prevent it from
short circuiting.
3) PID controller:

Figure 1: PID control of Electroplating bath
4) PID controller is the most suitable one for this process due to the following reasons:
 Proportional controller when used alone could provide with offset error
 PI (Proportional and Integral controller) could be used but Integral controller provides
oscillations that is formed as a noise factor, which could be eliminated with the
Derivative controller (Rosinová & Veselý, 2017)
Part 2:
1)
Transmitte
r
Range Output 4-20 mA
Flow Measured
mA
Expecte
d
mA
% Error
(span)
Calculated flow
based upon
readings
100 3.8 4 -0.05% 99.95
150 7.9 8
-
0.0125
% 149.98
200 12.1 12
0.0083
% 200.0166
250 16.4 16 0.025% 250.0625
300 21.5 20 0.075% 300.225
250 16.2 16
0.0125
% 250.0312
200 12.3 12 0.025% 200.05
150 8.2 8 0.025% 150.0375
100 3.9 4
-
0.025% 99.97

2) a) Orifice plate:
One of the simplest equipment in measuring the differential pressure is the orifice plate. The
pipleline through which the differential pressure is measured should be inserted with the orifice
plate. This plate causes an increase in the velocity of flow and decreases pressure. Positioning
the pressure tap also lays a major role in obtaining differential pressure.
 For all pipe size, the tap should lie within the same position relative to the orifice plane.
 The error rate could be minimized when the tap is located at a position where the pressure
profile is least (Zhai and Yu, 2009).
Types of taps:
 Flange taps
 Radius taps
 Corner taps
 Vena contracta taps
 Full flow/pipe taps
b) U-tube Manometer:
This instrument could be fitted along with the orifice plate in the two varying pressure tapings.
The difference in the pressure obtained by the U-tube manometer is given as,
P1−P2= ( ρm− ρf ) h
Where,
ρm −¿Density of manometer fluid
ρf −¿ Density of the given fluid
h- height of the restriction liquid at the differential column.
c) Venturi flow meters:
It promotes continuous contact among the flow of the fluid and he surface of the primary device.
Venturi tubes have a convergence entrance with the divergent outlet. The middle region is the
throat section from which 6-8 pressure taps that connects the throat to the annular chamber is
provided. This averages the throat pressure. The taps pave the way in measuring the throat
pressure.
3) a) SITRANS FM MAG 3100 P (7ME634)

b) link: https://new.siemens.com/global/en/products/automation/process-instrumentation/flow-
measurement/electromagnetic/sitrans-f-m-mag-3100-p.html
c) Conductive fluid flow measurement could be obtained by this flow meter. This follows the
principle of Electromagnetic Induction
d)

Figure 2: Electromagnetic flow meter with common to –ve, +ve and HART (FEX100)
variant communication module
e) The Device is connected with the NPN opto-coupled transistors used as switches. Maximum
permitted output will be 30 V DC. The current limit across the transistor is 220 mA.
f) For the accurate flow measurement, the sensor should be completely filled with the fluid.
Promoting straight lengths of outlet and inlet pipes and creating certain distance among the
pumps and the valves could promote accurate flow measurement. The meter should also be
placed in the middle of the pipe gasket and flanges (Buhl, 2010).
4) Principle:
Electromagnetic flow meters works on the basis of Faradays law of Electromagnetic Induction.
When the electrically conductive fluid flows with the velocity (v) along the length of the tube (L)
perpendicular to the lines of flux (B) through the magnetic field, Voltage (U) is induced.
U = B × L × V
---------------------------------------------------------------------2
It is suitable only for the conductive fluids (not suitable for the gases, steams and petroleum
products that has very low conductivity)

Figure 3: Simplified electrical circuit of Electro-magnetic flow meter
(Krishnaswamy, 2012)
The electrodes emf will be directly proportional to the flow velocity, unless there is no current
flow; the specific resistance will not be varied and gets influenced. This could be balanced with
the null balance potentiometer (Kozáková ,Veselý , and Osuský, 2009). The input signal and the
feedback signal should be equal in magnitude as well as in phase thus obtaining perfect balance
(Veselý, Kozáková & Grman, 2006).
5) a) The velocity of sound in a moving fluid is the resultant of the velocity of sound in a resting
fluid ± the velocity of fluid itself. Pressure variations travel across the fluid relative to the
velocity of sound.
b) Temperature of the fluid could influence the sound; therefore it should be made uniform.
Other factors include pressure changes, signal attenuation, presence of dust, steam and humidity
that affects the accuracy of measurement.
c) Ultrasonic flow meters adapts to multi-pulse technology with error correction and signal
digitization process. Obtaining proper choice of mode along with the location determination are
the 2 most important factors involved in the installation (sufficient upstream and downstream
straight pipe) of transducer
6) Differential pressure flow meters especially orifice plate is the simplest, cheap and it is
adapted to any fluid type. To enhance the accuracy, the plate should be in a good shape with the
sharp edge at the upstream side. The Turn Down Ratio is said to be 5:1 in orifice plates.
7) Principle:
It is based on the controlled generation of Coriolis forces. When both the rotational and
translational movements in the fluid is superimposed, then coriolis force will be present.

Where,
Fc
→
- Coriolis force
∆m- change in mass
ω
→
−¿Angular velocity
v
→
−¿ Radial velocity of an oscillating system
b) Torque measurement
R1 and R2 are the inner and the outer diameter
c) It can handle clean liquids, mixed fluids, multiphase fluids, foams, slurries and liquids
with entrained gases. Coriolis mass flow meter should be installed in the upper part if the
pressure drop is acceptable. Low flow rate could degrade the accuracy. Pipe vibration could
also affect the operational problems.
8) 1) Weights
2) Drive coils
3) Outlet pipe
4) flow tubes
9) a) The three types of flow includes the following:
 Laminar flow
 Turbulent flow
 Transitional flow
b) Reynolds Number:
Where, μ – Viscosity
ρ- Density

V, D- Velocity and Diameter of the pipe
The above expression is defined by the ratio of inertial forces to the viscous fluid. When the
viscosity is high then the inertial force has a very little effect on the fluid.
c)
Figure 4: Types of flow profile and patterns (https://www.azom.com/article.aspx?
ArticleID=15412)
10) Head is a term used to relate the energy associated with the incompressible flow of liquid
with the equivalent static column height. There are 4 types of head namely,

 velocity head (Kinetic energy),
 elevation head (Gravitational force),
 pressure head (Static pressure), and
 Resistance head (head loss)
11) Selection Criteria:
 Flow profile: Based on the behaviour of the fluid (Newtonian and non-newtonian fluid)
 Meter capabilities and performance: This is given by the Reynolds number
 Purpose and Application oriented: Based on the environmental impacts
 Budget: Includes Installation cost, running and maintenance service costs
12) Three styles of weir namely rectangular, Cippoletti, and V-notch
Variable-area flow meter is the best suitable flow meter for the head measurement
13) Rotameter is the positive displacement type flow meter. The float directed from the
downwards of the vertical pipe tends to lift the float upwards. The differential pressure across the
float decreases with the increase in the area.
14) One of the mass type flow meter is the turbine flow meter. The turbine wheel rotates at the
speed based on the flow rate. The frequency of the output signal obtained is the linear variation
of volumetric flow. The major disadvantages are:
 Calibration should be done at regular intervals of time.
 When liquid entering the meter is composed of suspended particles/ corrosive substances
then the particles stick to the rotor blades and affect the bearing wear (therefore filters
should be used).
 The swirling flow and the flow velocity distribution affect the fluid flow.
15) Thermal mass flow meters:
Types:
 Rate of Loss Flow meter: It measures the rate of loss of heat in the fluid stream from
the heated element that includes Thermistor, thermocouple, resistance wire or thin
film.
 Temperature Rise Thermal Flow Meter: It measures the rise of temperature from the
fluid stream as it passes through the heated source.
16) Mass flow rate = Mass of the material / time taken
According to the given data, at 4.00 PM there was 9.8 tons of powder in silo. Then within half an
hour i.e., at 4.30 PM it became 6.5 tons.

Hence 3.3 tons weight of powder is carried out by conveyor belt,
Therefore, Mass flow rate = 3300 / 0.5 = 6600 kg’s/hr
17) Positive displacement meters are the most suitable one for the custody transfer of industrial
and commercial water liquids. They can achieve high level of accuracy with internal precision.
Oval-gear type flow meter is generally used with the viscous liquid.
Operation:
 Position A- Gears A and B experience uniform forces and do not rotate. The trapped
liquid on the A forces it to rotate Clockwise (CW) direction followed by B in Counter
clockwise (CCW) direction.
 Position B- The rotation continues since the gap by the gears A and B tend to rotate with
the upstream and downstream pressure.
 Position C- Liquid is entrapped in gear B and meter body. The operation continues 4
times with the fluid amount and hence the flow is proportional to the rotational velocity
of gears
Figure 5: Working of oval gear meter (Krishnaswamy, 2012)
18) Common Metering tubes:
 Diaphragm Metering Pump Makro TZ -
https://www.prominent.com/en/Products/Products/Process-Metering-Pumps/Diaphragm-
Metering-Pumps/p-makro-tz-diaphragm.html
 Hydraulic Diaphragm Metering Pump Hydro/ 4 -
https://www.prominent.com/en/Products/Products/Process-Metering-Pumps/Hydraulic-
Diaphragm-Metering-Pumps/p-hydro-4.html
 Motor-Driven Metering Pump Sigma/ 2 (Basic Type) -
https://www.prominent.com/en/Products/Products/Metering-Pumps/Motor-Driven-
Metering-Pumps/p-sigma-2-basis-type-motor-driven.html
Part C:

2) A bourdon tube is a hand-held device with the pointer and socket arrangement. It does not
require electric supply for its operation. Pressure of about 0.6 ... 7,000 bar is measured. For
higher pressure, the tube should be provided with the spiral coil and helical tubes. The end of the
C-shaped tube is provided with the pressure that is indicated by the pointer mounted towards the
scale arrangement (Osusky and Vesely, 2011).
Adjustments:
 Pressure vent could be provided to avoid pressure build-up
 Glass provided for the measurement should be an open type
 The screw located at the scale face should be rotatable
 Adjust the knob at the lower side of the pressure gauge
3) a)SITRANS P DS III / P410, HART,4-20 mA transmitter for pressure
b) https://mall.industry.siemens.com/mall/en/WW/Catalog/Product/?mlfb=7MF4033-.....-....
c) Gauge Pressure
d)
Figure 7: Pressure gauge with HART communication
e) Case 1: Level is fixed at the tank base

For pressure transmitter :
LRV = 0 ft
URV = H ft
For LRV:
LRV = 0 - ( H * W * SPw ) ;
SPw is the given specific density of liquid in wet leg
W is width of wet leg side LP.
For URV:
URV = ( H * W * SPt) - LRV
SPt is the specific gravity pressure of liquid in tank
Case 2: The DP transmitter cannot be fixed