introduction tank gauging - endress+hauser

8/18/2019 Introduction Tank Gauging - Endress+Hauser

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Folie 1

Introduction Tank Gauging Why and What it is


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Slide 2

Introduction Tank Gauging

02/24/2004

Classification:INTERNAL

What is Tank Gauging? What is Tank Gauging?

A generic name for the static quantityassessment of liquid products in bulk

storage tanks


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Why Tank Gauging?

• Tank Gauging is essential to determine the inventory of liquidbulk storage tanks.

• Types of operation can be categorised to:

• Inventory Control• Custody Transfer

• Fluid Movement & Operations• Leakage Control & Reconciliation


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Slide 4


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Inventory Control

• Important ‘management tool’ for any refinery, terminal andstorage company. (How rich are we today?)

• Can be based on volume and/or Mass

• In-plant accuracy requirements are less critical compared withindependent storage companies and terminals. Reliability andrepeatability are much more important.

€


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Slide 5


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Custody Transfer

Measurement of product transfer between ship andshore and/or shore and pipeline transmissionsystems.(Batch dependant).

Use as verification tool for Flow meters.

Where Custody Transfer or assessment of taxes, dutiesor royalties are involved, the complete system must beofficially approved and certified.


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Leakage Control & Reconciliation

Increased awareness of the environmental impact of theindustry

Programs are initiated to reduce the risk of damage of theenvironment

More accurate information is generated for reconciliation, usedthe latest technology


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Slide 8


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Tank Gauging technologies

Because every user and application has its own requirements,there are different measurement techniques and solutions to

gauge the tank contentsThe following techniques are currently available:

Manual Gauging

Float and Tape Gauges

Servo Gauges

Radar Gauges

Hydrostatic Gauges

Hybrid Gauges


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Slide 9


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Manual Gauging

Using a graduated diptape or dipstick to determine the level

A method for verification of gauge performance, calibration and verification

Disadvantages:

Inaccurate (± 5-10 mm)

Inconsistency of the gauger

Safety regulations result in higher costs

Not always possible due to weather conditions


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Slide 10


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Servo Gauges

Developed during the 50’s

Float is replaced with a displacer suspended from a strongmeasuring wire

Accuracy is ± 0.7 mm

Can also measure interface and optional average density

Principle based on Archimedes law

Disadvantages:

Has still moving parts – perceives

Not suitable for heavy products (contamination of drum)


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Slide 11


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Radar Gauges

Developed in the 70’s for crude carriers (ships)

Non intrusive & no moving parts

Low maintenance costs

Uses microwaves to measure level

Accuracy ± 0.5, 3, 10 mm, depending on type/model

FMCW & PTOF

Disadvantages:

Less suitable for light products (e.g. LPG, LNG)


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Slide 12


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Uncertainties in Tank Gauging

Installation aspects

Temperature influences

Quantity assessment direct measured or derived.


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Slide 13


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Storage tank errors

Tank Bottom Movements

Tank Shell Thermal Expansion

Hydrostatic Deformation

Roof Weight changes

Gauge reference Height Stability


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Slide 14


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Tank Deformation

TYPICAL TANK DISTORTION DEFLECTION (mm)

0 10 20 30 40 50 60

720 kg/m

865 kg/m1,000 kg/m

3

3

3

HEIGHT (m)22

20

18

16

14

12

10

86

4

2


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Slide 15


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Comparison of typical errors

A 16 m high tank, 36 m Diameter:

Example:

Equivalent Surface Area = 1 000 m 2, i.e. 1 mm Ξ 1 m 3

Total Tank Volume (15m) ~ 15 000 m 3

0.25 oC Temp uncertainty Ξ 3.8 m 3

Conclusion: GoodTemperature Measurement isa ‘must’, i.e.averaging with sufficientspots, distributed over thetank height


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Slide 16


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Inventory Uncertainty

%0.5Ud15Ref. Density uncertainty

%0.3UVheel VHeel

%0.1UTCTTCT uncertainty

oC0.5Utemp.Total Temperature uncertainty

mm1UMDPManual Dip error

mm1UGRHGauge Ref Height uncertainty

mm1UATG ATG Level uncertainty


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Slide 17


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Batch Uncertainty

%0.5Ud15Ref. Density uncertainty

%0.1UTCTTCT uncertainty

oC0.5UtempTotal Temperature uncertainty

mm1UGRHGauge Ref Height uncertainty mm1UATG ATG Level uncertainty


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Requirements Tank Gauging systems

Safety

Accuracy and Repeatability

Reliability and Availability

Compatible with operations

Stand-Alone capabilities

Operator friendly

Low maintenance

Easy to expand


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Requirements Tank Gauging systems (continued)

First order failure detection

Accepted for Custody transfer (OIML/PTB/NMi)

Compatible with international standards(API, ASTM, ISO)

Interface to host computers

Software support

Upgradeability

Service & spare parts support

Price/Performance ratio

Vendors quality assurance procedures (ISO 9001)

Financial situation of vendor


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Requirements Automatic Tank Gauging

Product (& water) Level

Average Temperature (+ vapour temperature)

Average Density

Total Observed Volume (T.O.V.)

Gross Observed Volume (G.O.V.)

Gross Standard Volume (G.S.V.)

Volume of Water en Sediments (S&W)

Mass and Net Standard Volume (N.S.V.)

Mass or Net Weight in air


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Decision criteria Measuring method

Reliability & MTBF

Accuracy

Performance

Applicability to measurement task

Compatibility with existing field wiring

Cost of Ownership


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WMG-MSB

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Tankvision Basic Concept

(Field Protocol) V1, WM550

MODBUS

Tank Scanner

OPC

SCADA

LAN TCP/IP

Modbus

Data Concentrator

Host Link FieldCare

DCS/PLC

Top USP for Tankvision• Easy & Cost effective Scalability

• Single Tank to Refinery

• Open Systems (communications)

• Operating System Independent

• Reduced & Simplified Engineering • No special licensing or software

• Redundancy

• Scalable at multiple levels

• Remote & Asset Configuration

• Full support for FieldCare

Tank Scanner


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introduction tank gauging - endress+hauser

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