Power plant instrumentation

A Project Report on SMART SENSORS/TRANSDUCERS FOR THERMAL POWER PLANT

Submitted By: Upendra Pratap Singh (PG-103) Sudhir Singh (PG-106) Vivekanand Kherwar (PG-111) Ashwin John Tirkey (PG-113) Amit Kumar Das (PG-117)

Under the guidance of

Mr. D. K. Dey Asst. Professor JINDAL INSTITUTE OF POWER TECHNOLOGY (JIPT) O. P. Jindal Super Thermal Power Plant (4X250 MW) Vill & PO: Tamnar, Dist.: Raigarh Pin-496107 (CG)

CERTIFICATE

This is to certify that Upendra Pratap Singh (PG-103), Sudhir Singh (PG-106), Vivekanand Kherwar (PG-111) , Ashwin John Tirkey (PG-113) and Amit Kumar Das (PG-117), students of JINDAL INSTITUTE OF POWER TECHNOLOGY has completed the project work entitled “Smart Sensors/Transducers for Thermal Power Plant” as a partial requirement for completion of Post graduate Program in Thermal Power Plant Technology. This work has been carried out by them under my guidance and supervision. For completion of this project they have worked with their determination & dedication. We wish them best of luck for their bright future.

Mr .D. K. Dey (Project Guide)

Dr. K. C. Yadav (Director) Jindal Institute of Power Technology Tamnar, Raigarh (CG)

Date:

ACKNOWLEDGEMENT

It gives a great sense of pleasure to present the report during PG Program in Thermal Power Technology. We owe our heartiest thanks to Mr. D. K. Dey for giving us full guidance and support during the completion of our project. We wish to express our profound sense of gratitude to Director Dr. K. C. Yadav sir, Principal S. K. Nag sir & all the faculty members of Jindal Institute of Power Technology, Tamnar for their delightful guidance and constant encouragement throughout the process; they have always been a great motivator for us. We also take this opportunity to express our whole hearted thanks to the employees of JPL who made it possible by providing necessary documents and field experience to achieve the completion of our project with success.

Upendra Pratap Singh Sudhir Singh Vivekanand Kherwar Ashwin John Tirkey Amit Kumar Das PGPTPT (2011-12)

Date: -

Jindal Institute of Power Technology Tamnar, Raigarh (CG)

ABSTRACT The SMART concept provides a standard modular platform for the complete range of power plant sensor. It enables the sensor to stand alone with the processing power normally associated with much larger data acquisition systems. The intelligence built into the Smart Sensor allows measurement, storage and processing of raw data on multiple channels within a compact, rugged and technically advanced recording unit, able to withstand harsh environmental conditions. The processing power of the system is powerful enough to include complete linearity correction and temperature stability over a wide range, thereby maintaining its factory accurate calibration while in the field. Each sensor is band run in a temperature controlled oven which establishes the sensitivity of the individual parameters to ambient temperature variations. The data collected during this process is used as a basis to provide software error correction for parameters over the specified temperature range. This process provides error correction of an order of magnitude better than traditional technologies. This Smart Sensor includes a special low power sleep mode to conserve battery power and reduce battery physical size. An interface software application called SmartCom is supplied with the sensor to enable setting up, manipulation and retrieval of data. Processing of data files for graphing and analysis is provided by Aqua graph. Various alarm and triggering functions can be selected to activate external equipment such as water samplers, modem phone connections and warning alarms. The following range of sensors or combination of sensors can be optioned with the smart system









Pressure Sensors Temperature Sensors Flow sensors Vibration Sensors Dissolved Oxygen Sensors Electrical Conductivity pH Value Sensors I/P Converter

List of Figures:

Fig. 1.1 Fig. 3.1.1 Fig. 3.1.2 Fig. 3.1.3 Fig. 3.1.4 Fig. 3.1.5 (i) & (ii) Fig. 3.1.6 Fig. 3.1.7 Fig. 3.1.8 Fig 3.1.9 Fig. 3.1.10 Fig. 3.1.11 Fig. 3.2.1 Fig. 3.2.2 Fig. 3.2.3 Fig. 3.2.4 Fig 3.3.1 Fig 3.3.2 Fig 3.3.3 Fig 3.3.4 Fig 3.3.5 Fig 3.3.6 Fig 3.3.7 Fig 3.3.7 Fig 3.3.8 Fig 3.4.1 Fig 3.4.2 Fig 3.4.3 Fig 3.4.4 Fig 3.4.5 Fig 3.4.6 Fig 3.5.1 Fig 3.5.2 Fig 3.5.3

Smart Sensor Network Types of Pressure Pictorial View of Bourdon-Tube Gauge 2600T Pressure Transmitter Functional Block Diagram of Pressure Transmitter Various Parts of Pressure Transmitter PS 310 Pressure Sensor Differential Pressure Transmitter EJA-A Digital Sensor Design of DPR Ceramic process isolating diaphragm used in PMC51 Level Measurement Cerabar M-Pressure Transmitter with Ceramic Sensor Thermocouple Resistance Temperature Detector Bimetallic Thermometer Rosemount 644 Temperature Transmitter

Fig 3.5.4

Vibration Monitoring System

Fig. 3.6.1 Fig. 3.6.2 Fig. 3.6.3 Fig. 3.6.4 Fig. 3.6.5 Fig. 3.6.6 Fig. 3.6.7 Fig. 3.6.8 Fig. 3.6.9

Overview of Power Plant Pressure Reducing Element Back Pressure Regulator Thermal Shut-Off Valve Working of pH Sensor Liquiline M CM42 Dissolved O2 Sensor Conductivity Measurement Various Models of Conductivity Sensors

Promass 80F Functional block diagram of Promass 80F Proline Promass 80 Promass 80F Pictorial view of Level Switches Float operated level switch

Ash Slurry Tank BFP with Vibration Sensor Vibration Sensor RN-LP202 Series CW Pump with Vibration Sensor

Fig. 3.6.10 Fig. 3.6.11 Fig. 3.6.12 Fig. 3.6.13 Fig. 3.7.1 Fig. 3.7.2 Fig. 3.7.3 Fig. 3.7.4 Fig. 3.7.5 Fig. 3.8.1 Fig. 3.8.2 Fig. 3.8.3 Fig. 3.8.4 Fig. 4.1 Fig. 4.2 Fig. 4.3 Fig. 4.4 Fig. 4.5 Fig. 4.6

Duplex Type Cation Column Rosemount Solu Comp II Rosemount Analytical Analyzer Liquiline M CM42 Conductivity and pH Sensor Application of I/P Converter Watson I/P Converter Characteristic Graph of I/P converter Watson I/P Converter ABB I/P Converter Sensor Assembly Schematic diagram of Field Amplifier Module Field Amplifier Unit Schematic diagram of Signal Processing Module Simultaneous Analog and Digital Communication Point -to-Point Mode of Operation Multidrop Mode of Operation Examples of Device Parameter Sent to Control Room 4-20 mA Loop with a Zener Barrier 4-20 mA Loop with Isolator

List of Tables:

Table 3.1.1 Table 3.1.2. Table 3.1.3 (i) Table 3.1.3 (ii) Table 3.1.4 Table 3.2.1 Table 3.2.2 Table 3.2.3 Table 3.2.4 Table 3.2.5 Table 3.3.1 Table 3.3.2 Table 3.5.1 Table 3.6.1 Table 3.6.2 Table 4.1

Specifications of Bourdon Type Gauges Description of DPR EJA-A Measuring Range of Cerabar M Measuring Range of Cerabar M Specifications of Cerabar M PMC51 Types of Thermocouple Types of Resistance Thermometers Comparison between RTD and Thermocouples Specifications of Bimetallic Thermometer Specifications of Rosemount 644 Temperature Transmitter Technical Specifications Measuring ranges for liquids for Proline Promass 80 Specifications of RN-LP202 Vibration Sensor

Table of Aqueous Conductivities Characteristics of Rosemount Solu Comp II HART Communication Layers

Chapter 1: INTRODUCTION Smart Sensor & It’s Networks


Smart sensors are wireless or wired computing devices that sense information in much variety of environments to provide a multidimensional view of the environment.
For eg: sensors can sense light, some can sense temperature, pressure and flow simultaneously.
Smart Sensors are connected to Sensor networks. Sensor network is a collection of some (sometimes even hundreds & thousands) smart sensor nodes which collaborate among themselves to form a sensing network.
The main task of a sensor network can be divided into three categories. Sensing, processing and acting.
After sensing the environment based on the query provided by the sensor node the networks can process the sensed data, may even sometimes aggregate it with other nodes data and send it to the base station.
It enables the sensor to stand alone with the processing power normally associated with much larger data acquisition systems.
The intelligence built into the Smart Sensor allows measurement, storage and processing of raw data on multiple channels within a compact, rugged and technically advanced recording unit, able to withstand harsh environmental conditions.
The Smart Sensor includes a special low power sleep mode to conserve battery power and reduce battery physical size. An interface software application called Smart Com is supplied with the sensor to enable setting up, manipulation and retrieval of data.

Smart Grid Sensors & Networks: A smart grid sensor is a small, lightweight node that serves as a detection station in a sensor network. Smart grid sensors enable the remote monitoring of equipment such as transformers and power lines and the demand-side management of resources on an energy smart grid. Smart grid sensors can be used to monitor weather conditions and power line temperature, which can then be used to calculate the line’s carrying capacity. This process is called dynamic line rating and it enables power companies to increase the power flow of existing transmission lines. Smart grid sensors can also be used within homes and businesses to increase energy efficiency.

A sensor network is a group of specialized transducers with a communications infrastructure intended to monitor and record conditions at diverse locations. Commonly monitored parameters are temperature, humidity, pressure and speed, illumination intensity, vibration intensity, sound intensity, power-line voltage, chemical concentrations, pollutant levels and vital body functions. A sensor network consists of multiple detection stations called sensor nodes, each of which is small, lightweight and portable. Every sensor node is equipped with a transducer, microcomputer, transceiver and power source. The transducer generates electrical signals based on sensed physical effects and phenomena. The microcomputer processes and stores the sensor output. The transceiver, which can be hard-wired or wireless, receives commands from a central computer and transmits data to that computer. The power for each sensor node is derived from the electric utility or from a battery.

Fig. 1.1

Chapter 3: System Description 3.1.1 Pressure Sensor and its Transmitters A device for measuring the magnitude gnitude of a physical variable. variable All sensing is using physical measurement of phenomena. Pressure measurements are the most common measurements taken and recorded in the power station. It ranges from very low i.e. condenser vacuum to very high high i.e. hydraulic pressure in some actuator systems. Between these two limits of 30-40 30 40 milibar to 300 bar are to be the measurements of different process media-stream, media stream, water, oil, gas etc. and each with varying degree of accuracy and reliability. The commonn pressure measuring devices are:are: 1. 2. 3. 4.

Manometer using water and mercury Diaphragm, Capsule bellow Bourdonn Tube Gauges Transducers of different types for all range of telemetric purposes.

3.1.2 Types of Pressure:

Fig. 3.1.1 Pictorial Representation of Different types of Pressure

3.1.3 Bourdon Type Pressure Gauges Bourdon pressure gauges are used for measurement of pressure and vacuum and are suitable for all clean and non-clogging non liquid and gaseous media. a. The Bourdon Tube is a thin walled tube of oval cross section which may be of ‘C’ form or spirally wound. This tube expands when pressure is applied internally. This expansion is converted into rotation of a concentric pointer with a gear movement. The reading reading indicated on a dial by the pointer is proportional to the pressure applied. C-type C type Bourdon tubes are used for low pressure ranges and helical / spiral tubes for higher pressure ranges.

Fig. 3.1. 1.2 Pictorial View of Bourdon-Tube Gauge

3.1.4 Specifications of Bourdon Type Gauges: Gauges Company Dial Size Range Standard Accuracy Sensing Element Bourdon Tube Material Connection Shape of Bourdon Tube Joint Between Bourdon Tube Connection Connection Size

AN Instruments 50mm, 100mm, 150 mm, 200 mm 60, 100, 160, 250, 400 & 600 kg/cm2 ± 0.25% of FSD Bourdon Tube Stainless Steel Screwed In C P< 100kg/cm2, Coil P> 100kg/cm2 Argon Arc Welded ½ BSP, NPT, BSPT, API; M 20 x 1.5 (1/4" NPT (M) for 50 mm dial)

Table 3.1. 1.1 Specifications of Bourdon Type Gauges

3.1.5 Protection in Pressure Sensing S Instruments Snubber: - It is a protection device for pressure sensing instrument from violent pressure surges and pulsation. Snubbers are also known as deadners reduce the effect of pulsating pressure. They result in the instrument indicating or recording an average pressure, instead of recording each individual surge or pulse. Snubbers are used in pipe lines leading to the instrument.

3.1.6 Necessity of Smart Pressure P Transmitters In the trend of modern plant, the distance between the field instruments and centralized control rooms increases too many hundred yards. Hence it becomes very difficult to watch these many instruments and supervise the operation of such large number of equipments. To overcome this problem Smart Transmitters came into the field and become popular for their reliability andd accuracy.

3.1.7 A General 2600T Series Pressure Transmitter The 2600T series is a modular range of field mounted; microprocessor based electronic transmitters, using a unique inductive sensing element. The models have a pressure transmitter with "single port" process connection. This provides accurate and reliable measurement of gauge and absolute pressure, in the even most difficult and hazardous industrial environments.

Fig. 3.1.3 3. A 2600T Pressure Transmitter

Fig. 3.1.44 Functional Block Diagram of Pressure Transmitter

This instrument consists of two functional units: • Primary Unit • Secondary Unit Primary Unit includes the process interface and the sensor, the Secondary Unit includes the electronics, the terminal block and the housing. The two units are mechanically coupled by a threaded joint. Electronics of Secondary Units is based on custom integrated components (Application Specific Integrated Circuit – ASIC). The principle of operation of the Primary Unit is “The process fluid (liquid, gas or vapour) exerts pressure on to the measuring diaphragm via flexible, corrosion-resistant isolating diaphragm and the fill fluid. The other side of the measuring diaphragm is either at atmosphere, for gauge measurement, or at vacuum, for absolute measurement. As the measuring diaphragm deflects in response to input pressure changes, it simultaneously produces variations in the gap between the magnetic disc and the magnetic core of the coil, which is mounted rigidly on to the primary body.” As a result, the inductance of the coil changes. The inductance value of the coil is compared to that of a reference inductor carried by the primary electronics. The unit also includes a temperature sensor. The two inductance values and the sensor temperature are combined in the primary electronics to provide a proprietary standard signal. The measured value and the sensor parameter are transferred to the secondary unit, where a microprocessor computes precise primary output.

Fig. 3.1.5(i) Various Parts of Pressure Transmitter

Fig. 3.1.5(ii) Various Parts of Pressure Transmitter

3.1.8 Features of 2600T Smart Transmitter: Transmitter The 2600T 0T Smart series transmitter includes an Analog Version plus HART digital communication, a Profibus DP-PA DP Version and a Fieldbus FOUNDATION Version. Digital communication protocols allow remote re-ranging, re calibration and diagnostics. Profibus has a complete digital only communication, as well as Fieldbus FOUNDATION. With respect to HART, the bidirectional digital communication does not have any interference with the standard 4-20 4 mA analog output signal. This manual describes the features, the installation and calibration procedures related to the 2600T Series Transmitter with HART Communication Protocol. The 2600T series also gives the opportunity opportu to utilize ceramic and silicon sensing elements, depending on measuring range and measured variable.

3.1.9 PS 310 Pressure Sensors The PS310 Pressure Sensor utilises a ceramic based capacitive element as the transducer. This is designed to be of rugged construction and incorporates active electronics as an integral part of the transducer substrate to enhance reliability and accuracy. The onboard microprocessor converts the transducer output voltage to a 16 bit digital signal and also measures the transducer temperature. This information is used to temperature compensate the sensor over the range 0 - 50°C. Both pressure and temperature are displayed in SmartCom in real units i.e. metres of depth and degrees centigrade. centi

Fig. 3.1.6 PS 310 Pressure Sensor

3.1.10 PS 310 Sensor Specifications Standard Ranges Available: • Pressure: 0-1m, 0-2.5m, 0-5m, 0-10m, 0-20m, 0-40m, 0-75m, 0-100m, 0-200m (Gauge) • 0-10m, 0-20m, 0-40m, 0-75m, 0-100m (Absolute) • Temperature: 0-50°C Operational Parameters: • Over Range Pressure: 1-10m 10x minimum 20-100m 4x minimum 100+m 2x minimum Linearity: • Pressure: +/- 0.02% FS (Combined linearity, hysteresis and repeatability) • Temperature: +/- 0.2°C Accuracy: • Pressure: +/- 0.12% FS (over temp range 0-50°C) • Temperature: +/-1°C Temperature Stability: • ±0.002%/°C FS @ offset

Supply Voltage: 8-15V • Reverse polarity protected • Surge current protected to 2kV Quiescent Current: • 130µA to 30mA

3.1.10 Differential Pressure Transmitter The EJA-A A range is Yokogawa’s differential pressure transmitter. First released in 1991, it continues to offer high performance and high reliability for almost any application. With an installed base of over 4-1/2 4 million EJA-A A transmitters worldwide, it has a proven track record of exceptional mean-time-between-failure mean failure that is unmatched in the industry.

1.7 Differential Pressure Transmitter EJA-A Fig. 3.1.

Table 3.1.2. 3 Description of DPR EJA-A

3.1.11 Measuring principle Silicon resonant sensors are fabricated from single crystal silicon using proven 3-D semi-conductor conductor micromachining techniques. Two "H" shaped resonators are patterned on the sensor, each operating at a high frequency output. As pressure is applied, the bridges are simultaneously stressed, one in compression and one in tension. The resulting change in resonant frequency produces a high differential output (kHz) (kHz) directly proportional to the applied pressure. This simple time-based time based function is managed by a microprocessor.

Micro-machined machined from a single silicone crystal to provide superior stability and repeatability while eliminating hysteresis. Temperature effects cts are less than 1/10th of other silicon technologies (10 ppm/deg C), making this extremely stable in the most demanding process applications. The output produces a much higher signal to noise ratio as compared to analog sensors. Compared to piezoresistance ce silicon sensors, the silicon resonant sensor's immediate predecessor, the output is at least four times greater. Errors resulting from temperature and static pressure are insignificant in relation to total output. This advanced sensor technology is applied applied to Yokogawa's DPharp pressure transmitter. transmitter

DPharp stands for: Differential Pressure High Accuracy Resonant Pressure sensor

Fig. 3.1 .1.8 Digital Sensor Design of DPR

3.1.12 CERABAR M PMC51 Process pressure measurement Pressure transmitter with ceramic sensors; Modular design and easy operation; with analog or HART electronics The Cerabar M pressure transmitter is used for the following measuring tasks: Absolute pressure and gauge pressure measurement in gases, steams or liquids in all areas of process engineering and process measurement technology. Level, volume & mass measurements in liquids. High process temperature without diaphragm seals up to 125°C (257°F), with diaphragm seals up to 400°C (752°F). High pressure up to 400 bar (6000 psi)

Measuring principle

Fig 3.1.9 Ceramic process isolating diaphragm used in PMC51 Ceramic sensor 1 Air pressure (gauge pressure sensors) 2 Ceramic substrate 3 Electrodes 4 Ceramic process isolating diaphragm The ceramic sensor is a dry sensor, i.e. the process pressure acts directly on the robust ceramic process isolating diaphragm and deflects it. A pressure-dependent change in capacitance is measured at the electrodes of the ceramic substrate and the process isolating diaphragm. The measuring range is determined by the thickness of the ceramic process isolating diaphragm.

Fig. 3.1.10 Level Measurement

Level measurement h Height (level) p Pressure ƥ Density of the medium g Gravitation constant Communication protocol 4 to 20 mA without communication protocol (analog electronics) 4 to 20 mA with HART communication protocol Input Measured variable • Analog electronics: Absolute pressure and gauge pressure • HART electronics: Absolute pressure and gauge pressure, from which level (level, volume or mass) is derived Output Output signal • 4 to 20 mA analog, 2-wire • 4 to 20 mA with superimposed digital communication protocol HART 6.0, 2-wire Signal range 4 to 20 mA analog, 4 to 20 mA HART: 3.8 to 20.5 mA

Table 3.1.3 3.1. (i) Measuring Range of Cerabar M

Table 3.1.3 3.1. (ii) Measuring Range of Cerabar M

M Pressure Transmitter with Ceramic Sensor Fig 3.1.11 Cerabar M-Pressure

Field of application

Process connections

Measuring ranges OPL Process temperature range Ambient temperature range

Reference accuracy

Specialties

Gauge pressure and absolute pressure Level Thread EN flanges DN 25 – DN 80 ANSI flanges 1" – 4" JIS flanges 50 A – 100 A From –100/0 to 100 mbar (–1.5/0 to 1.5 psi) to –1/0 to 40 bar (–15/0 to 600 psi) Max. 60 bar (900 psi) –20 to +100 °C (–4 to +212°F) • Without LCD display: -40 to +85°C (–40 to +185 °F) • With LCD display: –20 to +70°C (–4 to +158°F) (extended temperature application range (-40 to 85°C (-40 to 185°F)) with restrictions in optical properties such as display speed and contrast) • Separate housing: –20 to +60°C (–4 to +140°F) • Diaphragm seal systems depending on the version Up to +0.15% of the set span PLATINUM version: up to +0.075% of the set span. Metal-free measurement with PVDF Connection. Special cleaning of the transmitter to remove paint-wetting substances, for use in paint shops. Table 3.1.4 Specifications of Cerabar M PMC51

3.2.1 Temperature Measurement and its Transmitters Temperature rise in a substance is due to the resultant increase in modular activity of the substance on application of heat which increases the internal energy of the material. The temperature measurement based on this very fact that there exist some observable properties of the substance which with its energy content. The change can be observed in the substance which itself or in a subsidiary system in thermal equilibrium with it. The subsidiary system is called the testing body while the system itself is called the hot body.

3.2.2 Types of Temperature Measuring Devices 1. 2. 3. 4. 5. 6.

Thermocouples Resistance Thermometers Thermistors Bimetallic Thermometers Acoustic Pyrometers Local Instruments.

3.2.3 Thermocouples: Thermocouples are based on Seeback effect which says that when heat is applied to a junction of two dissimilar metals, an emf is generated which can be measured at the other junction.

Fig. 3.2.1 Thermocouple

3.2.4 DDC Cards: For thermocouples input EA404 card is used which is taking mV as input. Total 8 input channels are available. For RTD’s EA03 cards are used which takes resistance as input. Total 4 input channels are available in EA03 DDC cards.

Type K Ni chromium Ni aluminium

Range 0 TO 1100 -180 TO 1350

Notes widely used because of range and cheapness

T Copper Copper nickel

-185 TO 300 -250 TO 400

Excellent for low temperature and cryogenic applications

R Platinum-13%rhodium platinum

0 TO 1600 -50 TO 1700

Used in high temperature applications

J Iron Copper nickel

20 TO 700 -180 TO 750

Commonly used in plastic moulding industry

N Nickel chromium-si Ni-si-magnesium

0 TO 1100 -270 TO 1300

Very stable at high temperature and good oxidation resistance

E Nickel chromium Copper nickel

0 TO 800 -40 TO 900

Maximum output change for per degree C

S Platinum-10%rhodium platinum

0 TO 1550 -50 TO 1750

Continuous use for high temperature

B Platinum-30%rhodium Platinum-6%rhodium

100 TO 1600 100 TO 1820

Generally used in glass industry

Table 3.2.1 Types of Thermocouple

3.2.5 Resistance Thermometers: Thermometers Resistance Thermometers works on the principle of change of resistance of a conductor when its temperature is changed. Rt = Ro (1+βdT) Where β = Temp. co-efficient efficient of resistance dT = Temperature emperature difference

Fig. 3.2.2 Resistance R Temperature Detector

METAL

RANGE

PLATINUM

-200 TO 600

COPPER

-100 TO 100

NICKEL

-60 TO 180

Table 3.2.2 Types of Resistance Thermometers

Factors Accuracy Range Cost Sensitivity Speed of response Power Supply Size Long term stability Vibration effects

Resistance Thermometers More accurate Narrower -200 to 650 More expensive Stem sensitive Slower Required 2 mA Larger Excellent Less suitable

Thermocouples Less accurate Wider -200 200 to 2000 Less expensive Tip sensitive Faster Not required Smaller Less satisfactory Suitable

Table 3.2.3 Comparison between Resistance Thermometers and Thermocouples

3.2.6 Bimetallic imetallic Thermometers: Thermometers All types of metal contract or expand with change in temperature. The temperature coefficient of expansion for every metal is different. Hence their rate of expansion or contraction is not same. Bimetallic Thermometers uses this concept to measure the temperature of materials in many industries. It is also used as overload cut out switch in electrical apparatus by monitoring current flow.

Fig. 3.2.3 Bimetallic Thermometer The measuring element of a bimetallic thermometer is a fast response bi-metallic bi helix. Iti is manufactured from two cold-welded cold welded strips of metal with different thermal coefficients of expansion and it becomes twisted as a function of temperature. The rotary rotar motion is transferred with low friction to pointer.

Table 3.2.2 Specifications of Bimetallic Thermometer

3.2.7 Temperature Transmitter (Rosemount Model 644) The Rosemount Model 644 Smart Temperature Transmitter is a microprocessormicroprocessor based instrument that accepts inputs from a wide variety of sensors, and transmits temperature data to a HART--Based Based control system or transmitter interface. The transmitter combines Rosemount reliability with the flexibility of digital electronics, and is ideal for applications that require high performance or remote communication. The transmitter is designed to communicate with a Rosemount HART-based HART communicator.. Communicators can be used to interrogate, configure, test, or format the transmitter, as well as other products in the Rosemount family of microprocessor-based microprocessor instruments. Moreover, HART-based HART based communicators can communicate with a transmitter from the control ntrol room, from the transmitter site, or from any other wiring termination point in the loop where there is between 250 and 1100 ohms resistance between the transmitter power connection and the power supply. Electrical temperature sensors, sensors, such as RTDs and thermocouples, produce lowlow level signals proportional to their sensed temperature. The Model 644 converts the low-level low sensor signal to a standard 4––20 20 mA dc signal that is relatively insensitive to lead length and electrical noise. This current signal is then transmitted to the control room via two wires.

Fig. 3.2.4 Rosemount 644 Temperature Transmitter

Digital Accuracy

+ 0.15° C (+0.27° F) for Pt100 RTD

D/A Accuracy

+0.03% of span

Ambient Temperature Effects

0.003°C per 1.0°C (1.8°F) change in ambient (Pt100 RTD)

Stability

.15% of Reading or .15°C for 2 years

Input

2-, 3-, and 4-wire wire RTDs, thermocouple, millivolt, ohm

Supply Voltage

12 - 42.2V in HART Protocol

Form Factor

DIN A Head Mount or Rail Mount

Table 3.2.2 Specifications of Rosemount 644 Temperature Transmitter ansmitter

3.3.1 FLOW MEASUREMENT Most widely used differential pressure flow meters are:    

Orifice Plates Flow Nozzles Venturi Tubes Variable Area flowmeters, i.e. Rotameters

Over 40% of all liquid, gas, and steam measurements made in industry are still accomplished using common types of differential pressure flowmeter; that is, the orifice plate, Venturi tube, and nozzle. The operation of these flowmeters is based on the observation made by Bernoulli that if an annular restriction is placed in a pipeline, then the velocity of the fluid through the restriction is increased. The increase in velocity at the restriction causes the static pressure to decrease at this section, and a pressure difference is created across the element. The difference between the pressure upstream and pressure downstream of this obstruction is related to the rate of fluid flowing through the restriction and therefore through the pipe. A differential pressure flowmeter consists of two basic elements: an obstruction to cause a pressure drop in the flow (a differential producer) and a method of measuring the pressure drop across this obstruction (a differential pressure transducer).One of the major advantages of the orifice plate, Venturi tube, or nozzle is that the measurement uncertainty can be predicted without the need for calibration, if it is manufactured and installed in accordance with one of the international standards covering these devices.

3.3.2 Bernoulli’s Equation The Bernoulli equation defines the relationship between fluid velocity (v), fluid pressure (p), and height (h) above some fixed point for a fluid flowing through a pipe of varying cross-section, and is the starting point for understanding the principle of the differential pressure flowmeter. Bernoulli’s equation states that:

Thus, the sum of the pressure head (p/pg), the velocity head (v/2g), and potential head (h) is constant along a flow streamline. The term “head” is commonly used because each of these terms has the unit of meters. Bernoulli’s equation can be used to show how a restriction in a pipe can be used to measure flow rate. Consider the pipe section shown below. Since the pipe is horizontal, h1=h2, then equation reduces to

The conservation of mass principle requires that:

Fig 3.3.1

Rearranging previous equations and substituting for v2 gives:

This shows that the volumetric flow rate of fluid Q can be determined by measuring the drop in pressure (p1– p2) across the restriction in the pipeline — the basic principle of all differential pressure flowmeters. This equation has limitations, the main ones being that it is assumed that the fluid is incompressible (a reasonable assumption for most liquids), and that the fluid has no viscosity (resulting in a flat velocity profile). These assumptions need to be compensated when equations are used for practical flow measurement.

Fig 3.3.2

Fig 3.3.3

Fig 3.3.4

3.3.3 DPHARP LOW FLOW TRANSMITTERS DPharp low flow transmitters are designed to measure infinitesimal flow rates (water-equivalent flow rates ranging from approximately 0.016 to 33 litres per minute [L/min] or air-equivalent flow rates from0.45 to 910 L/min) and transmit a 4 to 20 mA DC signal responsive to the flow rate. A DPharp low flow transmitter consists of a differential pressure transmitter and an integral flow orifice manifold. The orifice plate can be replaced by removing only the manifold from the piping without removing the transmitter. The integral flow orifice manifold is directly mounted in-line on a nominal 0.5-inch (25 mm) process pipe, and hence there is no need of a separate detector or of lead pipes. The upstream and downstream pressures across the orifice are directed to the low- and high-pressure side chambers, respectively, and the differential pressure is converted into an electric signal of 4 to 20 mA DC. Six orifice plates are available in different bore sizes from 0.508 to 6.530 mm in diameter. A choice from these six different orifice plates and the variable settings of the measurement range of the differential pressure transmitter enables a wide range of extremely low flow rates to be measured. The difference between the upstream and downstream pressures across the orifice, P1 – P2, has the following relationship with the flow rate Q:

Q =
 (1 − 2)/ρ Where, k = Proportionality factor P1 – P2 = Differential pressure ρ = Specific density of the process fluid d = Diameter of the orifice bore Differential pressure flowmeters are also known as Head type flowmeters. They are the most prevalent type of flowmeters in use today. It has been projected that more than 50 percent of all liquid flow measurement applications make use of this type of unit. The basic Working principle of differential pressure flowmeters is based upon the Bernoulli’s Equation which states the fact that the pressure drop across the meter is directly proportional to the square of the flow rate. The flow rate is calculated by measuring the pressure differential and extracting its square root. This differential pressure is then transmitted to the pressure transducer. The resonant-wire pressure transducer is a device generally employed for measurement of pressure in industrial applications. It was brought out in the late 1970s. The figure below shows a typical resonant wire type differential pressure transducer. In this design there are: 1. 2. 3. 4. 5. 6.

Resonant wire High-pressure diaphragm Low-pressure diaphragm Magnets Metal tube High side backup plate

7. Low side backup plate 8. Electrical insulator 9. Preload spring 10. Fluid transfer port 11. Oscillator circuit

Fig 3.3.5 In a resonant wire pressure transducer, a wire is fixed by a static member at one end, and by a pressure sensing diaphragm at the other (under tension). The process pressures are detected by high pressure and low pressure diaphragms on the right and left of the unit. The wire is positioned in a magnetic field and allowed to oscillate. The oscillator circuit results in the oscillation of wire at its resonant frequency. The variations in process pressure affect the wire tension, due to which the resonant frequency of the wire also gets changed. For instance, as the pressure is increased, the element increases the th tension in the wire, thus raising its resonant frequency. A digital counter circuit is used to detect the shift. Since this change in frequency can be detected accurately to a certain extent, this type of transducer can be employed for low differential pressure pressure applications as well as to detect absolute and gauge pressures.

3.3.4 MASS FLOW METERS CORIOLIS MASS FLOW MEASURING SYSTEM Coriolis flowmeters were developed in the 1980s to fill the need for a flowmeter that measures mass directly, as opposed to those that measure velocity or volume. Because they are independent of changing fluid parameters, Coriolis meters have found wide application. Many velocity and volumetric meters are affected by changes in fluid pressure, temperature, viscosity, and density. Coriolis meters, on the other hand, are virtually unaffected by these types of changes. By measuring mass directly as it passes through the meter, Coriolis meters make a highly accurate measurement that is virtually independent of changing process conditions. As a result, Coriolis meters can be used on a variety of process fluids without recalibration and without compensating for parameters specific to a particular type of fluid. Coriolis flowmeters are named after Gaspard G. Coriolis (1792–1843), a French civil engineer and physicist for whom the Coriolis force is named. Coriolis meters typically consist of one or two vibrating tubes with an inlet and an outlet. While some are U-shaped, most Coriolis meters have some type of complex geometric shape that is proprietary to the manufacturer. Fluid enters the meter in the inlet, and mass flow is determined based on the action of the fluid on the vibrating tubes. Common to Coriolis meters is a central point that serves as the axis of rotation. This point is also the peak amplitude of vibration. What is distinctive about this point is that fluid behaves differently, depending on which side of the axis of rotation, or point of peak amplitude, it is on. As fluid flows toward this central point, the fluid takes on acceleration due to the vibration of the tube. As the fluid flows away from the amplitude of peak vibration, it decelerates as it moves toward the tube outlet. On the inlet side of the tube, the accelerating force of the flowing fluid causes the tube to lag behind its no-flow position. On the outlet side of the tube, the decelerating force of the flowing fluid causes the tube to lead ahead of its no-flow position. As a result of these forces, the tube takes on a twisting motion as it passes through each vibrational cycle; the amount of twist is directly proportional to the mass flow through the tube. The Coriolis tube (or tubes, for multi tube devices) is vibrated through the use of electromagnetic devices. The tube has a drive assembly, and has a predictable vibratory profile in the no-flow position. As flow occurs and the tube twists in response to the flow, it departs from this predictable profile. The degree of tube twisting is sensed by the Coriolis meter’s detector system. At any point on the tube, tube motion represents a sine wave. As mass flow occurs, there is a phase shift between the inlet side and the outlet side. The most significant advantage of Coriolis meters is high accuracy under wide flow ranges and conditions. Because Coriolis meters measure mass flow directly, they have fewer sources of errors. Coriolis meters have a high turndown, which makes them applicable over a wide flow range. This gives them a strong advantage over orifice plate meters, which typically have low turndown. Coriolis meters are also insensitive to swirl effects, making flow conditioning unnecessary. Flow conditioners are placed upstream from some flowmeters to reduce swirl and turbulence for flowmeters whose accuracy or reliability is affected by these factors. Coriolis meters have a low cost of ownership. Unlike turbine and positive displacement meters, Coriolis meters have no moving parts to wear down over time. The only motion is due to the vibration of

the tube, and the motion of the fluid flowing inside the tube. Because Coriolis flowmeters are designed not to be affected by fluid parameters such as viscosity, pressure, temperature, and density, they do not have to be recalibrated for different fluids. Installation is simpler than installation for many other flowmeters, especially orifice plate meters, because Coriolis meters have fewer components. Coriolis meters can measure more than one process variable. Besides mass flow, they can also measure density, temperature, and viscosity. This makes them especially valuable in process applications where information about these variables reduces costs. It also makes it unnecessary to have a separate instrument to measure these additional Variables.

Fig 3.3.6 Promass 80F

1. Flow meter type

Direct mass flow

2. Measuring principle

Coriolis mass flow

3. Measuring material

Stainless steel

4. Power supply

85-260V AC

5. Local display

WEA, 2-line display, push buttons

6. Flow accuracy

+/- 0.15%

7. Density accuracy

+/- 0.001g/cc

8. Temperature accuracy

+/- 0.5 deg ˚C

Table 3.3.1 Technical Specifications

The measuring device described in these Operating Instructions is to be used only for measuring the mass flow rate of liquids and gases. At the same time, the system also measures fluid density and fluid temperature. These parameters are then used to calculate other variables such as volume flow. Fluids with widely differing properties can be measured.

Fig 3.3.7 Functional block diagram of Promass 80F

3.3.5 PROLINE PROMASS 80 Coriolis Mass Flow Measuring System The universal and multivariable flowmeter for liquids and gases Application The Coriolis measuring principle operates independently of the physical fluid properties, such as viscosity and density. Extremely accurate measurement of liquids and gases such as oils, lubricants, fuels, liquefied gases, solvents, foodstuffs and compressed gases (CNG) Fluid temperatures up to +350 C Process pressures up to 350 bar Mass flow measurement up to 2200 t/h

Features and benefits The Promass measuring devices make it possible to simultaneously record several process variables (mass/density/temperature) for various process conditions during measuring operation. The Proline transmitter concept comprises: Modular device and operating concept resulting in a higher degree of efficiency. Software options for batching and concentration measurement for extended range of application. Diagnostic ability and data back-up for increased process quality. The Promass sensors, offer: Multivariable flow measurement in compact design. Insensitivity to vibrations thanks to balanced two-tube measuring system. Immune from external piping forces due to robust design. Easy installation without taking inlet and outlet runs into consideration. Measuring principle The measuring principle is based on the controlled generation of Coriolis forces. These forces are always present when both translational and rotational movements are superimposed. FC = 2 · ∆m (v · ω) FC = Coriolis force ∆m = moving mass ω = rotational velocity v = radial velocity in rotating or oscillating system

The amplitude of the Coriolis force depends on the moving mass ∆m, m, its velocity v in the system, and thus on the mass flow. Instead of a constant angular velocity ω, the Promass sensor uses oscillation. In the Promass F and M sensors, two parallel parallel measuring tubes containing flowing fluid oscillate in anti phase, acting like a tuning fork. The Coriolis forces produced at the measuring tubes cause a phase shift in the tube oscillations (see illustration): At zero flow, in other words when the fluid fluid is at a standstill, the two tubes oscillate in phase (1). Mass flow causes deceleration of the oscillation at the inlet of the tubes (2) and acceleration at the outlet (3).

The phase difference (A-B) (A B) increases with increasing mass flow. Electrodynamics sensors register the tube oscillations at the inlet and outlet. System balance is ensured by the anti phase oscillation of the two measuring tubes. The measuring principle operates independently of temperature, pressure, viscosity, viscosity, conductivity and flow profile. Density measurement The measuring tubes are continuously excited at their resonance frequency. A change in the mass and thus the density of the oscillating system (comprising measuring tubes and fluid) results in a corresponding, automatic adjustment in the oscillation frequency. Resonance frequency is thus a function of fluid density. The microprocessor utilizes this relationship to obtain a density signal. Temperature measurement The temperature of the measuring tubes is determined in order to calculate the compensation factor due to temperature effects. This signal corresponds to the process temperature and is also available as an output.

Fig 3.3.7 Proline Promass 80

Measured variable Mass flow (proportional to the phase difference between two sensors mounted on the measuring tube to register a phase shift in the oscillation). Fluid density (proportional to resonance frequency of the measuring tube). Fluid temperature (measured with temperature sensors).

DN

Range for full scale values (liquids) mmin(F) to mmax(F)

8 15 25 40 50 80 100 (only Promass F) 150 (only Promass F) 250 (only Promass F)

0 to 2000 kg/h 0 to 6500 kg/h 0 to 18000 kg/h 0 to 45000 kg/h 0 to 70000 kg/h 0 to 180000 kg/h 0 to 350000 kg/h 0 to 800000 kg/h 0 to 2200000 kg/h

Table 3.3.2 Measuring ranges for liquids for Proline Promass 80 Input signal Status input (auxiliary input): U = 3 to 30 V DC, Ri = 5 kΩ, galvanically isolated. Configurable for: totalizer reset, positive zero return, error message reset, zero point adjustment start, batching start/stop (optional). Output signal Current output: Active/passive selectable, galvanically isolated, time constant selectable (0.05 to 100 s), full scale value selectable, temperature coefficient: typically 0.005% of full scale value/C, resolution: 0.5 µA o Active: 0/4 to 20 mA, RL < 700 Ω (for HART: RL ≥ 250 Ω) o Passive: 4 to 20 mA; supply voltage US 18 to 30 V DC; Ri ≥ 150 Ω Pulse/frequency output: Passive, open collector, 30 V DC, 250 mA, galvanically isolated. Frequency output: end frequency 2 to 1000 Hz (fmax = 1250 Hz), on/off ratio 1:1, pulse width max. 2 s Pulse output: pulse value and pulse polarity can be selected, pulse width adjustable (0.5 to 2000 ms).

Power consumption AC: 10K its conductivity can be obtained by Two electrodes measurement. On the other hand, Four electrodes measurement with guard electrodes is applied when that of conductive polymer sheet is low (R