instrumentation portfolios - michigan water environment ... - level controls.pdf · instrumentation...

[File Name or Event] Emerson Confidential 27-Jun-01, Slide 1

Instrumentation Portfolios

Pressure Flow

Level


Agenda

Level Measurement Overview

– Technology Overview

– Selection Criteria

– Installation Guidelines

Level Measurements for Municipal Applications

– Sump Level

– Open Channel Flow

– Differential Filter Screens

– Lime Storage Silos

– Sludge Blanket Level


20%

Radar

Ultrasonic

Technologies for Continuous Level Measurement

Submersible

Level

PR

ICE

Application Difficulty


The Right Technology for the Application

Process Condition Submersible Hydrostatic

Ultrasonic Guided Wave

Radar Non-Contacting

Radar Aeration

Agitation

Ambient Temp Changes

Corrosion

Density Changes

Foam

Internal Obstructions

Coating

Vapors

Viscous, Sticky


Indicator

9710 Hydrostatic Level Transmitters

Hydrostatic Level - head pressure of a liquid which is proportional

to level in a vented tank or open to atmosphere application


Ceramic Capacitive Sensor

• As the applied pressure changes, the ceramic wafer flexes.

• Changes the distance between the capacitance plates

• Sensor’s electronics convert deflection to 4-20mA

• Rugged, Ceramic Sensor Face

• No oil-fill, very low deflection for low hysteresis

Capacitive Plates Force (pressure)

Surface mount electronics


Submersible Level

Technology Advantages

Flexible mounting, typically suspended

Unaffected by conditions in the vapor space or on the liquid surface

Useful Features

Ruggedized sensor made of ceramic or protected by external cage

Vent tube protected with Teflon filter or sealed bellows

9700

Submersible

Hydrostatic Level

Transmitter

Process Condition Submersible Hydrostatic

Aeration

Agitation


Corrosion

Density Changes

Foam


Coating

Vapors

Viscous, Sticky

Vent tube

Bellows


Bottom

reference

Reference

Height

Ultrasonic Level Measurement

Distance

to surface = Speed x (Round Trip Time / 2)

Level = Reference Height – Distance


Installation Considerations

Avoid mounting very close to the tank wall

Avoid turbulence & splashing

Align vertically

Do not mount in the center of a tank

Be mindful that most ultrasonics use an onboard temp sensor to compensate for speed of sound

– Protect with a sunshield or use an external temp input to provide more accurate ambient temp compensation

Optional external temperature input

can be mounted in the shade


Distance out = 32 in

External Temperature Input

Why is this important?

Bottom

reference

36 in actual distance 75 deg F

Distance out = 36 in

Electronics Temp = 75 deg F Electronics Temp = 100 deg F External Temp Input= 75 deg F

Vapor Space Temp is 75

deg F, but, we’re

correcting for SoS based

on 100 deg F!!!

If we measure the vapor

space temperature, we get

accurate SoS correction.

http://www.google.com/imgres?imgurl=http://www.imajlar.com/free_clipart/summer_clipart/summer_clipart_sun.gif&imgrefurl=http://www.free-clipart-pictures.net/summer_clipart.html&h=200&w=200&sz=7&tbnid=4tVbmBuRssQRGM:&tbnh=104&tbnw=104&prev=/images?q=sun+clip+art&hl=en&usg=__rr-tVMwbBQ8e9wmVQ7SDPWvCg9k=&ei=zqGFS8ypKcSWlAew1uzvAQ&sa=X&oi=image_result&resnum=2&ct=image&ved=0CAsQ9QEwAQ

http://www.google.com/imgres?imgurl=http://img53.imageshack.us/img53/3091/symb573pg4.jpg&imgrefurl=http://clipart-for-free.blogspot.com/2008_08_01_archive.html&h=295&w=284&sz=38&tbnid=wW3v5G055tqkaM:&tbnh=115&tbnw=111&prev=/images?q=cloudy+clip+art&hl=en&usg=__L1vQyjacd5plVOhmOMJaTBIBCpg=&ei=A6KFS-2kKYuZlAeXr8XwAQ&sa=X&oi=image_result&resnum=2&ct=image&ved=0CAgQ9QEwAQ


Ultrasonic Technology Advantages

Non-contact, no moving parts

Unaffected by fluid density or viscosity

Widely-compatible materials of construction for chemical tanks

Useful Features

Submersion-rated to withstand occasional flooding

Signal-processing done at the device for highest integrity and reliability

External temperature input for more accurate speed of sound compensation

Rosemount 3107

Submersion-rated

Ultrasonic Level

Transmitter

Process Condition Ultrasonic

Aeration

Agitation


Corrosion

Density Changes

Foam


Coating

Vapors

Viscous, Sticky

Rosemount 3102

Ultrasonic Level Transmitter

with integral keypad and

display


Guided Wave Radar Level Measurement

• The microwave pulse is

guided down a probe

• Energy is reflected from the

product surface

• Distance is calculated

• Some of the pulse may

continue past the product

surface

• Allows for interface

measurement (e.g. Oil

and water)

Distance = Speed x Time of Travel / 2


Guided Wave Radar Technology Advantages

Highly reliable and robust measurement

Excellent choice for solids applications

Useful Features

Ability to handle difficult applications with a single probe

Useful software interface for ease of configuration

Coated probe diagnostics

Rosemount 5300

Guided Wave

Radar with Single-

Lead Probe

Process Condition Guided Wave

Radar

Aeration

Agitation


Corrosion

Density Changes

Foam


Coating

Vapors

Viscous, Sticky

Single-lead flexible cable ideally

suited for solids applications



A single-lead probe is the best choice where possible

Mount the probe away from inlet pipes

A shorter nozzle helps prevent the probe from shorting

Anchor flex probes to the tank bottom in turbulent applications

For tanks with internal obstructions such as agitator blades, non-contacting radar is a better choice


For Difficult Applications, Choose non-Contacting Radar

View from inside the pumping station

Here the customer

wanted a non-contacting

technology, but had very

restricted “view” from

above.


Non-Contacting Radar

• Microwave pulse emitted from

antenna

• Microwave pulse reflected from

product surface

• Distance to the product surface is

calculated

Distance = Speed x Time of Travel / 2


Non-contacting Radar Technology Advantages

Non-contact, no moving parts

Unaffected by fluid density or viscosity

Tight, focused beam helps avoid false reflections from internal tank obstructions

Useful Features

Physical design that sheds water condensation

Rosemount 5400

Non-contacting

Radar

Process Condition Non-Contacting

Radar

Aeration

Agitation


Corrosion

Density Changes

Foam


Coating

Vapors

Viscous, Sticky

37° 9° Beam angles with 4” antennas

26 GHz 10 GHz

High-frequency option (26 GHz) for tanks with obstructions

Low-frequency option (10 GHz) for foaming applications



Maintain a clear and unobstructed view of the level surface

Mount away from product inlets

Avoid mounting above internal tank hardware (e.g. ladders and baffles)

Do not install in the center of the tank

Generally ok to mount close to the wall if the surface is smooth

Condensation Resistant Antenna

• Larger Diameter Seal

• No Dirt or Condensate accumulation

Rosemount 5400 has a

large diameter seal


W&WW Measurements

Sump Level

Open Channel Flow

Differential Filter Screens

Sludge Blanket Level

Solids Storage Silo’s


Sump Level

Monitor level in sumps and lift stations

Transmit level to a PLC or Local Display

Trip high level alarms to prevent overflow

Typical Level Technologies

Submersible

Hydrostatic Ultrasonic

Because the signal processing is performed in

the transmitters, a separate control box is not

required, though it can be useful…….


Sump Level Control

Requires a PLC or Controller

Pumps are activated when level reaches set point

Large wells may have more than one pump

– Multiple pumps in series provide assist and/or standby for heavy loads

Rosemount 3490

Universal Controller

Relay 1—Pump 1

Relay 2—Pump 2

Pump 1 Pump 2

The controller has onboard pump-

control algorithms and serves as an

intrinsically-safe power supply for the

transmitters. It also features local

display and integrated keypad for

configuration.


For Difficult Applications, Choose Radar

View from inside the pumping station

Here the customer

wanted a non-contacting

technology, but had very

restricted “view” from

above.


Open Channel Flow—Application Overview

What is measured?

– Flow is inferred by measuring the level of water flowing through a restricted channel

Typical Level

Technology

Ultrasonic


Open Channel Flow

Channel has a built-in flow restriction with known geometry

– Flow rate can be determined by measuring level upstream of the flow restriction

Rosemount 3100 Family of Ultrasonic

Transmitters with

Onboard Configurable Flow Geometries


Open Channel Flow—Application Overview

What is measured?

– Flow is inferred by measuring the level of water flowing through a restricted channel

Typical Level

Technology

Ultrasonic


Open Channel Flow

Channel has a built-in flow restriction with known geometry

– Flow rate can be determined by measuring level upstream of the flow restriction

Rosemount 3100 Family of Ultrasonic

Transmitters with

Onboard Configurable Flow Geometries


Open Channel Flow Measurement W

AS

TE

WA

TE

R T

RE

AT

ME

NT


Open Channel Flow—Flumes & Weirs


More Flumes & weirs


Flume & Weir Flow Calculations

Basic equation for rectangular flume :-

Q = (2/3)3/2

(gn)1/2

CvCdbh3/2

gn = acceleration due to gravity

Basic equation for “V” notch weir :-

Q = 8/15 tan a/2 (2gn)1/2

Cehe5/2

(Kindsvater Shen)

These formulas

embedded in all

3100’s and 3490’s!!!


Open Channel Flow—Equipment Selection

Ultrasonic Level Measurement

– Flow calculated in the transmitter

Equipment Considerations

– Level accuracy makes a big difference

• Consider that a V-notch weir may have only a 6-inch span!

– For best accuracy, use an external temp sensor mounted in the shade

– Application typically uses a submersion-rated device

– Easy configuration with built-in equations for flow geometries

– Flow totalization (daily and/or cumulative)

– Make it easy to verify the calibration

Rosemount 3493 Universal

Control Unit for Totalizing

and Logging Flow

Rosemount 3108 Ultrasonic

Level Transmitter with

External Temp Sensor


Differential Level Across Filter Screen

Downstream level subtracted from upstream level to indicate when screen needs to be cleaned


Guided Wave Radar for Lime Storage Silos

– No moving parts

– No maintenance

– No exposure to lime dust

Replaces mechanical measurements


Parshall Flumes Standard sizes & geometry

– 1”, 2”, 3”, 6”, 9”, 1ft, 1.5ft, 2ft, 3ft,4ft, 5ft, 6ft, 8ft,10ft to 50ft

Self cleaning at critical flow conditions

Easy to maintain

Support for Parshall

Flumes embedded in all

3100’s and 3490’s!!!


Sludge Level Measurement for Clarifiers

“Sludge Judge”

– Operator dips a tube into the clarifier

– Pulls up a “core sample”

– Determines interface between supernatant and sludge ‘by eye”

– Typically performed a few times per day


Sludge Measurements--Overview

Sludge forms as solids fall out of suspension in a clarifier

Clarified Water

Sludge

Wastewater Sludge

Supernatant


Automated Sludge Level Control

Ultrasonic pulse transmitted from submerged sensor

Pulse reflects off sludge blanket

System determines the travel time of return echo

System calculates distance to the blanket

Sludge Level

MOBREY MSL600

ENT

Relay 1

Relay 2

Relay 3


Sludge Level Control

Prevent solids from overflowing the clarifier’s weir

Save power by running desludge only when needed

Clarified Water

Sludge

Wastewater Sludge

Supernatant


Typical Profile (top-down)


Benefits of Automation

Protect health and safety by eliminating manual measurements

Trend the process to understand it better

– Use Sludge Level as feedback for Flow Balancing in the plant

– Is the Blanket Level at the last clarifier as healthy as the first?

Relays in the controller can be used to automate control of the sludge level

Prevent carry-over

MSL600

Automated Sludge

Control System


Benefits of Automation

Protect health and safety by eliminating manual measurements

Trend the process to understand it better

– Use Sludge Level as feedback for Flow Balancing in the plant

– Is the Blanket Level at the last clarifier as healthy as the first?

Relays in the controller can be used to automate control of the sludge level

Prevent carry-over

Automated Sludge

Control System


Point Level Detection & Pump Protection

Pump Protection High Level Alarm Limit Detection

Vibrating Fork

Level Switches


Configure & Monitor Everything from the Control Room

http://www2.emersonprocess.com/en-US/brands/rosemount/Wireless/THUM-Adapter/Pages/index.aspx

http://www2.emersonprocess.com/en-US/brands/rosemount/Wireless/THUM-Adapter/Pages/index.aspx

Level Solutions for W&WW

instrumentation portfolios - michigan water environment ... - level controls.pdf · instrumentation...

Documents