COMPRESSED NATURAL GAS MEASUREMENT FOR VEHICLES (NGV

COMPRESSED NATURAL GAS MEASUREMENT FOR VEHICLES (NGV) : MALAYSIA EXPERIENCE

PRESENTATION AT TCFF APMP MEETING

KLCC, KUALA LUMPUR, MALAYSIA

14 DECEMBER 2009

PREPARED BY

DR. ABDUL RAHMAN MOHAMEDHEAD, FLOW METROLOGY SECTION

NATIONAL METROLOGY LABORATORY, SIRIM BERHAD

NGV stands for Natural Gas for Vehicles, also commonly known as NGV stands for Natural Gas for Vehicles, also commonly known as Compressed Natural Gas or CNG.Compressed Natural Gas or CNG.

NGV has been used as fuel for vehicles for more than 50 years (eNGV has been used as fuel for vehicles for more than 50 years (e.g. .g. Italy).Italy).

More than 3 million vehicles worldwide are using NGV.More than 3 million vehicles worldwide are using NGV.

NGV is similar to natural gas supplied to power stations, industNGV is similar to natural gas supplied to power stations, industries, ries, commercial establishments and households. The only difference iscommercial establishments and households. The only difference is that that it is compressed and stored at 3,000 psi onboard vehicles.it is compressed and stored at 3,000 psi onboard vehicles.

NGV can be used as a single fuel (monoNGV can be used as a single fuel (mono--gas) or in conjunction with a gas) or in conjunction with a different type of fuel e.g. gasoline (bidifferent type of fuel e.g. gasoline (bi--fuel/dualfuel/dual--fuel). However, most fuel). However, most NGV vehicles use the biNGV vehicles use the bi--fuel system due to its flexibility.fuel system due to its flexibility.

What is NGV ? :What is NGV ? :

OVERVIEW ON CNG/NGV APPLICATION & SYSTEM FOR OVERVIEW ON CNG/NGV APPLICATION & SYSTEM FOR VEHICLESVEHICLES

Why NGV ? :Why NGV ? :

OVERVIEW ON CNG/NGV APPLICATION & OVERVIEW ON CNG/NGV APPLICATION & SYSTEM FOR VEHICLESSYSTEM FOR VEHICLES

•• It is a more environmental friendly fuelIt is a more environmental friendly fuel

Motor vehicles are major source of pollution, contributing to > 90 % of air pollutants.They are toxic and have adverse effects on human health and linked to many degenerative diseases.Therefore, NGV improves the quality of air and reduces health & medical care costs.

•• It is also an alternative fuel to reduce the nationIt is also an alternative fuel to reduce the nation’’s dependence on s dependence on traditional liquid fuelstraditional liquid fuels

CARBON MONOXIDE (CO)

NONMETHANE HYDROCARBON

(NMHC)

NITROGEN OXIDES (NO)

PETROL BASE BASE BASE

LPG - 20% - 10% + 20%

NGV - 60% - 90% - 10%

DIESEL - 40% - 10% + 700%

Comparison of emission levels by fuel type

NGV vehicles in NGV vehicles in Asia Pacific Asia Pacific countriescountries

NGV in Asia Pacific countries (2007): NGV in Asia Pacific countries (2007):


IranStations = 40

Vehicles = 22,058

South KoreaStations = 90

Vehicles = 3,700Pakistan

Stations = 476Vehicles = 540,000

JapanStations = 230

Vehicles = 19,406

ChinaStations = 300

Vehicles = 79,600

IndiaStations = 160

Vehicles = 160,000

ThailandStations = 22

Vehicles = 1,800Bangladesh

Stations = 50Vehicles = 26,500

MalaysiaStations = 60

Vehicles = 29,300

IndonesiaStations = 28

Vehicles = 4,660

SingaporeStations = 1Vehicles = 4


Classification of NGV stations :Classification of NGV stations :

Conventional stationsConventional stations

Gas from thedistributionpipeline at pressure of 50-250 psi.

Gas is compressedin 3-4 stages to a maximum pressure of 3600 psi.

Flow rate capacityfor a compressoris 200 -750 Nm3/hr.

Compressed gas is stored in three banks (high , medium and low) at the maximum pressure of 3600 psi.

Typical total volume for a storage cascade is 500-750 Nm3.

Double-hose dispenser witha filling rate ofless than three minutes per vehicle.

Gas is stored in The vehicle at 3000 psi.

PIPELINE1 COMPRESSOR2 STORAGECASCADE

3 DISPENSER4 NGV VEHICLE5

NGV


Main components for NGV stations :Main components for NGV stations :

DISPENSERDISPENSER

COMPRESSORSTORAGE CASCADESSTORAGE CASCADES


Typical NGV vehicle systems (biTypical NGV vehicle systems (bi--fuel) :fuel) :

Petrol solenoidvalve

NGV solenoidvalve

Selector switch & fuel indicator

NGV supply line

Filling connector and Master shut-off valve

Regulator

Mixer

Petrol supply line

Petrol tank NGV cylinder

DISPENSER CONSTRUCTION AND COMPONENTS

BACKGROUND:

THE FUNCTION OF A CNG DISPENSER ARE :

- TO SAFELY TRANSFER THE FUEL INTO THE VEHICLE

- MEASURE THE QUANTITY OF FUEL DELIVERED

Dispensers are second only to compression equipment as the most expensive part of a CNG fuelling station, with gas flow meters accounting for much of the high cost.

The reason: As CNG dispensers are located at public access stations and intended for trade used, the units have to comply to the Safety, and Weights and Measures regulation requirements


DISPENSER OPERATION:

Gas from cascade storage system is piped by way of 3 lines (low, medium and high pressure banks) to the dispenser through a combination of filter and valves.

During refuelling, the gas flows to the vehicles due to differential pressure between cascade and vehicle’s on-board storage.

From these banks, the gas passes through mass flowmeter and finally into the delivery hose. The delivery hose incorporates a breakaway coupling, bleed valve, return vent line and refuelling connection.

As the gas flows, the flowmeter provides an input electrical pulses proportionally to the flow through the dispenser, to the calculator/indicator unit.


DISPENSER COMPONENT: FLOWMETER

Flow measurement is an important aspect in gas industries since these are cash registers that measure the revenue of the gas produced by any petroleum companiesDuring the filling process the flow, pressure and temperature of the gaseous fuel being dispensed vary widely and rapidly and the Coriolis meter has become the dispensing technology of choice across the world.

Endress & Hauser Promass 64M and Micromotion CNG050 type are widely used for the mass flow measurement of compressed natural gas at the dispenser.

CNG050

Promass 64M


DISPENSER COMPONENT: FLOWMETER

A coriolis meter consists of two primary components: the flow tube assembly (the sensor) and an electronic assembly (the transmitter). The sensor's main components are the flow tubes, a driver for oscillating the flow tubes, flow detector (displacement transducer or pickoffs) which are mounted on either side of the driver.

Electronic assembly (transmitter)

Flow tube assembly (sensor)

DISPENSER COMPONENT: CALCULATOR/INDICATOR


This electronic device received and process the electrical pulse output from the flowmeter to compute for volume of the gas delivered, its price, totalization, etc.

In Malaysia, most of the dispenser used Kraus Industries manufactured device, Micon 500N model. A conversion factor of 0.7 is used for converting the measured mass to displayed volume. The total volume is displayed to the nearest 0.01 liter while the total sale is displayed to the nearest one sen.


DISPENSER COMPONENT: BREAKAWAY COUPLING

In the event of an emergency where excessive pulling force is applied to the fill hose, the breakaway coupling pulls apart and the gas flow stops


DISPENSER COMPONENT: NOZZLE, HOSE, BLEED VALVE

Gas passes through 3-way refuelling valve at the end of the fill hose. Gas then enters the vehicle through a coupling.

Once gas flow has stopped, the 3-way valve is closed and the gas pressure between the fill valve and the coupling is vented by the exhaust port on the valve. This small amount of gas is vented through the vent hose which is an integral part of the filling hose assembly.

METHOD OF CALIBRATION FOR NGV FUEL DISPENSERS

INTRODUCTION

While gravimetric testing of CNG dispensers is widely used for verification, the disposal of the dispensed gas after testing presents a problem and this method of testing requires the transport of heavy and bulky test cylinders and calibrated scales.

If a master meter in series with the existing dispenser meter isused to meter the gas into a vehicle, the problem of gas disposal and the need to transport test cylinders and scales can be eliminated.


MASTER METER METHOD

Disadvantage:It is not a direct proving method. The results are subjected to the accuracy of the master meter. Any inaccuracies in the master meter’s measurement will be passed on to the dispenser’s meter.

Advantage:More practical for compressed natural gases activities (e.g disposal problem).

Also, the conditions used for calibrating the master meter are the same as that during calibration of the dispenser.


MASTER METER CALIBRATION

- The performance is traceable to agreed standards.

- The master meter must obviously be of higher quality than the meter to be calibrated.

- It should be remembered that the reference meter performance mayalso change with time and periodic recalibration will be required


MASTER METER CALIBRATION: EQUIPMENT REQUIRED:

- Platform scale, having a valid calibration certificate(estimated measurement range 0 – 150 kg, resolution 1 gram)

- Verifying weights- CNG cylinders

(estimated capacity 45 - 60 litres)- Grounding cable - Data sheets, calculator- appropriate hoses and fittings- Wind shield, cylinder pad

Note:• At least 2 units of cylinders are required to speed up the

calibration process.• Maximum gas filled to a normal cylinder in a taxi is around 10 kg

EQUIPMENT REQUIRED: PLATFORM SCALE


PLATFORM SCALE

DISPLAY PANEL/ KEY PAD/PRINTER

PLATFORM SCALE: COVER REMOVED

VERIFYING WEIGHTS


EQUIPMENT REQUIRED: CNG CYLINDERS

CNG CYLINDERS

EQUIPMENT REQUIRED: GROUNDING CABLE


Pad (cloth) – to prevent cylinder movement

GROUNDING CABLE


EQUIPMENT REQUIRED: DATA SHEETS

Run No.

Cylinder Weights (kg)

(1) Empty / (2) Full

(3) Gas Weights = (2) – (1)

(standard value)

(4) Master meter reading

(measured value)

Accuracy (%) = ((4) – (3)) 100 /(3)

Meter Factor = (3)/(4)


NGV DISPENSER

MASTER METER

GAS CYLINDER

PLATFORM SCALESUPPLY

SET- UP FOR MASTER METER CALIBRATION


GAS CYLINDER

GAS SUPPLY HOSES

MASTER METER

DISPENSER

PLATFORM SCALE

SET- UP FOR MASTER METER CALIBRATION


MASTER METER CALIBRATION PROCEDURE

1) Turn on balance following manufacturers recommended procedure with reference to warm-up period before testing starts. Check zero and levelling.

2) Place CNG cylinder on the balance 3) Turn on master meter and then connect supply of CNG to the meter

4) Tare (zero) balance5) Insert probe from master meter into filling point of CNG cylinder6) Ensure that balance and master meter are all zeroed7) Turn on valve at master meter to start fill

8) Take at least 5 reading (5 runs); the amount of CNG filled between 4 -10 kg9) Finish fill by turning off valve at master meter and remove probe from CNG

cylinder fill point.10) Record amount of fill indicated by balance and master meter.



Calculated error for prover as follows:

Where Mt = mass indicated by master meterMb = mass indicated by balance

(Mt – Mb) x 100Error (E) =

Mb



The error must be within ± 0.5 %.

If the prover is to be adjusted, the new frequency (or K-factor) can be calculated using the following formula:

New frequency spanadjustment number

Old frequency spanAdjustment number

= Xaverage (mass indicated by balance

mass indicated by prover


SAMPLE CALCULATION

Run No.

Cylinder Weights (kg) (1) Empty / (2) Full

(3) Gas Weights = (2) – (1)

(standard value)

(4) Master meter reading

(measured value)

Accuracy (%)

= ((4) – (3)) 100 /(3)

Meter Factor = (3)/(4) 0.9980.9970.997

0.1990.3210.283

6.0434.0688.855

6.0314.0558.830

30.08928.15732.834

24.05824.10224.004

321


MATER METER SEALING

DISPENSER TESTING AND VERIFICATION

INTRODUCTION

Pattern approval ensures the reliability of measuring instruments by prescribing requirements for the pattern or design of an instrument to ensure reliability in use, and immunity to fraudulent readjustment


METROLOGICAL CHARACTERISTIC REQUIREMENT

Units

The dispenser shall register or record or be marked with International system of units.

Total delivery display : 999.99 liters with a resolution of at least 0.01 liter. This display shall be resettable to zero.

Total sale display: The capacity of the display shall not be less than RM99.99 with a resolution of 1 sen. This display shall be resettable to zero.


NGV DISPENSER

SUPPLY

MASTER METER

SET- UP FOR DISPENSER VERIFICATION

SET- UP FOR DISPENSER VERIFICATION



ACCURACY TEST

The maximum permissible errors applicable at verification are:

a) Measured quantity

The maximum permissible error for verification shall be ± 2% of the quantity delivered

(b)Price

The price indicated shall equal the price calculated from the volume and unit price indicated.

Procedure

• Turn the master meter on and allowed to warm

• Check and zero the master meter dispenser reading.

• Plug the dispenser nozzle into the master meter

• Fill the next vehicle availableNote: minimum size of fill for a test is 3 kg

v. Record the measured value displayed on the dispenser and the value indicated by the master meter. Calculate error for dispenser as follows:

ACCURACY TEST



ACCURACY TEST

Calculated error for dispenser as follows:

Where Md = mass indicated by dispenser (in kg)Mt = mass indicated by master meter (in kg)

(Md – Mt) x 100Error (E) =

Mt


ACCURACY TEST

vi. Take at least 5 reading (5 runs); the minimum size of fill for atest is 3 kg.

The error must be within ± 2.0 %. If the dispenser flowmeter is to be adjusted, the new frequency (or K-factor) can be calculated using the following formula:

New frequency spanadjustment number

Old frequency spanAdjustment number= X

average (mass indicated by master meter

mass indicated by dispenser

vii. Check price calculations for the quantities delivered and the unit price settings


ACCURACY TEST

0.7 kg/literCNG Density factor (F)

0.565 RM/LiterUnit price setting (P)

00000Sales computationalerror ( in sen)

(F – E)

G

6.026.205.273.334.49Calculated sales(A x P)

F

6.026.205.273.334.49Sales reading in Ringgit

E

-0.29-0.18-0.31-0.72-0.39% error=(( B-C) 100)/C

D

7.4867.6946.5534.1575.586Master meter Reading (kg)

C

7.4647.6806.5334.1275.564Mass dispensed(F x A) kg

B

10.66310.9719.3335.8967.949Dispenser display ( litre )

A

7654321TEST NO. (HOSE/SIDE)

Documents

COMPRESSED NATURAL GAS MEASUREMENT FOR VEHICLES (NGV