艾默生質(zhì)量流量計(jì)原理-

WelcomeLatest

DevelopmentsIntroductions1.高準(zhǔn)質(zhì)量流量計(jì)客戶(hù)培訓(xùn)質(zhì)量流量計(jì)工作原理和安裝、投用、基本維護(hù)Flow

Application

Team(=

Transparency

2)Note:

TX-2

depicts

a

systembased

on

the

RFT9739.

For

the

same

systemwith

the

RFT9712,

use

TX-144;

for

the

IFT9701,

use

TX-145.Use

TX-2

to

orient

the

class:Point

out

corresponding

components

on

the

PMDs.Don’t

spenda

lot

oftime

atthis

point

explaining

what

particular

components

do

orhow

to

operate

them.

Also,

don’t

confuse

things

atthis

pointby

usingmodel

designations.Make

sure

class

understands

the

distinction

between

the

transmitter

interface

(used

to

communicate

with

the

transmitter

but

generally

not

requiredfor

normal

operation)

and

the

peripheral

interface

(which

is

usually

the

operating

interface

with

the

flowmeter).議程Micro

Motion

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2科里奧利質(zhì)量流量計(jì)原理安裝、投用和基本維護(hù)(=

Transparency

2)Note:

TX-2

depicts

a

systembased

on

the

RFT9739.

For

the

same

systemwith

the

RFT9712,

use

TX-144;

for

the

IFT9701,

use

TX-145.Use

TX-2

to

orient

the

class:Point

out

corresponding

components

on

the

PMDs.Don’t

spenda

lot

oftime

atthis

point

explaining

what

particular

components

do

orhow

to

operate

them.

Also,

don’t

confuse

things

atthis

pointby

usingmodel

designations.Make

sure

class

understands

the

distinction

between

the

transmitter

interface

(used

to

communicate

with

the

transmitter

but

generally

not

requiredfor

normal

operation)

and

the

peripheral

interface

(which

is

usually

the

operating

interface

with

the

flowmeter).流量計(jì)系統(tǒng)部件流量變送器(RFT9739)流量傳感器(ELITE

CMF)頻率/脈沖輸出(0-10

kHz)毫安輸出(4-20

mA)后位設(shè)備后位設(shè)備(ALTUS

Model

3300)變送器接口(HC275)Micro

Motion

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3(=

Transparency

9)Other

factors

besides

temperature

and

pressure

come

into

play

when

using

most

volumetric

flow

measurement

technologies.

These

factors

don’taffect

Coriolis.Perhaps

the

best

way

to

get

at

this

is

to

ask

the

question

first:

Is

volumetric

measurement

affected

by

other

factors?If

there’s

no

response,

just

give

the

answer,

as

shown

on

the

transparency.

If

the

audience

has

some

knowledge,

makeaquick

list.

There’s

noneed

to

discuss

flow

regime

or

Reynolds

numbers.One

important

point

is

that

Coriolis

measures

mass

directly.

Until

relativelyrecently,

this

technologywasn’t

available.

If

you

wanted

to

measuremass

using

a

volumetric

method,

how

would

you

do

it?

The

answer

involves

density,

whichleads

to

the

next

topic.Micro

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4(=

Transparency

8)Perhaps

better

question:

Why

measure

volume?The

volume

of

afluid

(and

its

density)

varies

with

its

temperature

(and

pressure).

What

about

mass?If

you

are

paying

by

the

gallon,

do

you

want

to

buy

the

834

poundsat

200

degrees

or

at

60

degrees?Micro

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5(=

Transparency

10)Coriolis

density

measurement

is

direct

and

virtuallycontinuous.

Why

is

that

better

than

sampling?Remember

that

density

varies

with

temperature

and

pressure.

What

happens

when

you

remove

material

from

the

process?What

if

your

process

is

inconsistent?

How

often

do

you

need

to

sample

in

order

to

be

able

to

approximate

average

density?It’s

performed

automatically

and

almost

instantaneously,

so

it’s

more

convenient

and

the

information

is

much

more

useful

for

controlling

theprocess.Micro

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6(=

Transparency

15)We’ll

start

by

lookingat

the

variables

that

are

measured

directly.Micro

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7傳感器操作原理動(dòng)畫(huà)演示Micro

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8Coriolis

Meters

operate

byvibrating

the

flow

tubes

at

their

natural

frequency.科里奧利流量計(jì)–彎管結(jié)構(gòu)Micro

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9An

RTD

is

attached

to

the

flow

tubes

to

provide

compensation

for

the

change

in

elasticity

of

the

tubes

as

the

temperature

changes.

Thistemperature

signal

is

also

available

as

an

monitoring

or

control

variable.科里奧利流量計(jì)–彎管結(jié)構(gòu)Micro

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10Here

is

a

side

view

showing

the

tubes

vibrating

attheir

natural

frequency,

and

how

acoil

passing

through

a

magnet

on

both

the

inlet

and

outletsides

will

create

a

sine

wave.科里奧利流量計(jì)–彎管工作原理Micro

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11Under

a

no-flowcondition

(end

view)

both

the

inlet

and

outlet

pickoff

coils

are

in-phase.

The

time

difference

between

the

measurements

(deltaT)

is

zero.Micro

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Confidential科里奧利流量計(jì)–彎管工作原理Page

12As

flow

moves

through

the

meter,

the

tubes

resist

the

change

inangular

momentumcausingthe

tubes

to

twist.

This

twist

causes

a

change

in

DeltaT

as

measured

between

the

left

and

right

pick-off

coils.

This

Delta

T

measurement

is

directly

proportional

to

mass

flow.Micro

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13科里奧利流量計(jì)–彎管工作原理(=

Transparency

22)Whenthere

is

no

flow,

there’s

no

twist,

so

sine

waves

from

the

inlet

and

outlet

side

pickoffs

are

in

phase.When

the

process

is

flowing,

the

twist

results

in

sine

wave

waves

being

outof

phase,

with

the

inlet

side

signallagging

the

outlet

side

signal.The

amount

of

time

that

the

signals

are

out

of

phase,

referred

to

as

Dt,

is

proportional

to

the

mass

flow

rate.Micro

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14(=

Transparency

117)Micro

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15變送器怎樣計(jì)算質(zhì)量流量流量標(biāo)定常數(shù)(在工廠或現(xiàn)場(chǎng)標(biāo)定)流量標(biāo)定常數(shù)，4.5523g/s/us

X

(1-1)usK

flow=每產(chǎn)生1μs相差所對(duì)應(yīng)的流量(單位為克每秒)零流量偏移，調(diào)零(滿(mǎn)管,靜止,等溫)K

zero=傳感器無(wú)流量時(shí)的相差流量溫度修正，5.13%/100CFTC=溫度變化100C時(shí)由于流量管剛性變化而引起的流量百分比誤差質(zhì)量流量計(jì)算(由變送器進(jìn)行)質(zhì)量流量

=

K

flow

X

(△t-

Kzero

)X(1-(FTC

X

TDegC))Micro

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16Density

is

a

natural

by-product

of

how

a

Coriolis

meter

works.

The

more

mass

in

the

tubes,

the

lower

the

natural

frequency

of

the

tubes.密度工作原理2.當(dāng)質(zhì)量減少時(shí)，系統(tǒng)的諧振頻率就增加。

在高準(zhǔn)質(zhì)量流量計(jì)中，質(zhì)量和諧振頻率之間的關(guān)系是密度測(cè)量的基礎(chǔ)。去理解這個(gè)關(guān)系，就認(rèn)為是彈簧和質(zhì)量系統(tǒng)?！?/p>

當(dāng)質(zhì)量增加時(shí)，系統(tǒng)的諧振頻率就減少。Micro

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17As

the

natural

frequency

of

the

tubes

(measured

by

the

left

pick-off

coil)

increases,

the

tube

period

becomes

shorter.

This

example

would

meanthat

the

mass

in

the

tubes

is

decreasing.

It

is

easierto

time

tube

cycles

(frequency)

than

count

them,

so

we

measure

the

tube

period

which

is

theinverse

of

the

tube

frequency.

[Tube

period

=

1

/

tube

frequency]密度工作原理Micro

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18(=

transparency

24)Tube

period

t

(tau)

is

determined

by

sampling

the

sine

wave

generated

by

the

sensor’s

Left

Pickoff

Coil.Densityis

calculated

by

comparing

the

registered

tube

period

with

tube

periods

produced

by

fluids

of

known

process

density:

air

and

water.Micro

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19密度標(biāo)定系數(shù)密度標(biāo)定系數(shù)(在標(biāo)定時(shí)得出)K

1

傳感器注入低密度標(biāo)定介質(zhì)(空氣)時(shí)的管道周期D

1

低密度標(biāo)定介質(zhì)的密度K

2

傳感器注入高密度標(biāo)定介質(zhì)(水)時(shí)的管道周期D

2

高密度標(biāo)定介質(zhì)的密度T

c

溫度變化100C時(shí)由于流量管剛性變化而引起的密度百分比誤差Micro

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20The

meters

are

calibrated

at

the

factory

on

Air

and

Water.

The

measurement

is

very

linear

so

by

filling

the

meter

with

air

and

measuringthe

tubeperiod,

and

then

repeating

the

process

with

water

a

straight-line

relationship

is

determined.

Measuring

the

tube

period

whenthe

meter

is

filledwithprocess

fluid

provides

as

very

accurate

on-line

density

measurement

that

is

available

as

a

monitoring

or

control

variable.密度工作原理Micro

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21(=

Transparency

19)We

need

to

knowtemperature

to

compensate

for

its

affect

on

the

elasticity

and

rigidity

of

the

metal

flow

tubes,

which

determine

how

the

tubesresponds

specifically

to

flow

and

density.

We’ll

discuss

that

againlater.The

temperature

indicated

by

the

RTD

also

represents

the

temperature

of

the

process

with

considerable

accuracy.

In

current

Micro

Motionsensor

design,

the

RTD

temperature

is

equivalent

to

a

thermowell

sensor

in

terms

of

indicating

process

temperature.Micro

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22(=Transparency31)Features

of

the

D

series:compatible

with

all

transmitters

(except6-inchsensors,

which

are

not

compitible

with

the

IFT9701).

Only

sensor

series

that

can

be

used

with

theRFT9712.standard

sensor

available

in

sizes

from

.06-inch

to

6-inch;

flow

ranges

from

0-2

lb/min

to

0-25,000

lb/mincan

be

installed

up

to

1000

feet

from

transmitteravailable

with

high

pressure

fittings

(except

DS600)wetted

parts

316Lstainless;

also

available

with

nickel

alloy

(with

304

stailess

lap

joingflanges);

or

lined

with

Tefzel

(1.5-

and

3-inchonly)high

pressure

(DH)

and

high

temperature

(DT)

models

also

available

in

several

sizessingle-tube,

self-draining

loop

sensor

(DL)

for

sanitary

process

applications

or

shear-sensitive

fluids

is

available

in

.5-,

1-,

and

2-inchsizes.Review

the

function

of

each

of

the

elements

labeled

on

the

transparency.Micro

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23(=

Transparency

39)Correct

installation

is

extremely

important.

Remember

that

the

sensor

will

performaccurately

if:the

flow

tubes

are

free

to

oscillate

at

their

natural

frequencywhen

filled

withprocess

fluid,

andthe

signal

generated

by

the

sensor

is

not

interrupted

or

distorted.Recommended

sensor

orientations,

determined

by

the

process

fluid,

minimize

the

risk

of

developing

slug

flow

condition:For

liquid

processes,

installing

the

tubes

pointing

downallows

gases

in

the

flowstream

to

bubble

upward

and

out

of

the

tubes

wirthout

collecting.For

gaseous

processes,

the

tubes

up

orientation

prevents

condensate

fromaccumulating

in

the

tube

bends.For

slurries,

the

“flag”orientation

is

recommended

because

of

the

uneven

consistency.Micro

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24標(biāo)準(zhǔn)安裝方式適當(dāng)?shù)闹亓χ谓Y(jié)構(gòu)適當(dāng)?shù)姆ㄌm連接結(jié)構(gòu)無(wú)需直管段Micro

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25質(zhì)量流量計(jì)的安裝傳感器的安裝管線：上下游都不需要有直管段；調(diào)節(jié)閥要裝到流量計(jì)的下游；在傳感器的兩側(cè)安裝截止閥；在傳感器的兩側(cè)管段設(shè)置穩(wěn)固的支撐；為便于調(diào)試及維護(hù)，考慮安裝旁路。在測(cè)量易汽化介質(zhì)時(shí)，傳感器后建議工藝管與流量計(jì)保持同口徑一段距離，以及傳感器后安裝閥門(mén)可以用以調(diào)節(jié)適當(dāng)?shù)谋硥?，防止汽化或氣穴發(fā)生。Micro

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26質(zhì)量流量計(jì)的安裝變送器的安裝位置要易于數(shù)據(jù)查看和維護(hù)。便于過(guò)程數(shù)據(jù)查看方便儀表組態(tài)與檢查專(zhuān)用的儀表電源，保證儀表運(yùn)行穩(wěn)定，避免硬件損壞Micro

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27施工注意問(wèn)題如為新建管線，在吹掃過(guò)程結(jié)束后再安裝傳感器；在管線上進(jìn)行焊接作業(yè)時(shí)，要取下傳感器；在安裝大口徑傳感器時(shí)，不要將支撐物支撐在傳感器外殼上。Micro

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28投表準(zhǔn)備工作傳感器、變送器接線檢查及設(shè)備上電。檢查儀表參數(shù)。儀表基本組態(tài)。儀表組態(tài)數(shù)據(jù)記錄。注：上述組態(tài)項(xiàng)目可通過(guò)變送器的顯示器、手操器或組態(tài)軟件完成。Micro

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29投表準(zhǔn)備工作傳感器、變送器接線檢查及設(shè)備上電。專(zhuān)用信號(hào)電纜電源接線輸出接線Micro

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30投表準(zhǔn)備工作儀表參數(shù)檢查–傳感器特性化參數(shù)、儀表系數(shù)等與設(shè)備銘牌、校準(zhǔn)證書(shū)是否一致。Micro

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31投表準(zhǔn)備工作儀表基本組態(tài)組態(tài)測(cè)量單位，根據(jù)需要選擇過(guò)程變量的單位，包括質(zhì)量流量、體積流量、溫度、密度等；組態(tài)毫安輸出或脈沖輸出的過(guò)程變量與量程；組態(tài)過(guò)程變量阻尼，包括流量，密度，溫度；組態(tài)流向；回路測(cè)試（數(shù)據(jù)遠(yuǎn)傳）；儀表調(diào)零（并不總是需要）。Micro

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32What

does

an

improperly

zeroed

meter

look

like?

The

slopeof

the

line

is

unchanged,

the

meter

factor

is

still

1.0000.

Clearly

there

is

an

error,however

as

what

changes

is

the

Y-intercept.For

the

mass

flow

rate

of

A,

the

meter

indicates

a

rate

thatis

too

high,

A’’.

Note

the

meter

always

indicates

the

same

amount

too

high,

(A’’

–

A’),

regardless

of

the

flow

rate.

This

is

the

definition

of

a

zero

error,

and

why

we

have

traditionally

recommended

to

“check

the

zero”.

At

zero

flow,

the

meter

will

indicate

(A’’

–

A’).Meter

performance

is

normally

quoted

as

a

percentage

of

mass

flow

rate

(as

opposed

to

what

is

shown

above

whichis

a

%

of

spanerror).

Remembering

that

A’

=

A,

the

percentage

error

is

calculated

as

shown

in

the

formula

at

thebottomleft.

Since

(A’’

–

A’)

is

constant

(and

hopefully

small),

high

flow

rates

result

in

small

%

error.零點(diǎn)影響不正確的零點(diǎn)會(huì)帶來(lái)什么?改變了在Y軸的截距斜率(儀表系數(shù))沒(méi)有變化ATrue

Mass

Flow

RateIndicated

Mass

Flow

RateA”A’%

Mass

Flow

Error

=(A”

–

A’)A’X

100

%MFMicro

Mot