DE10028542A1 - Diagnostic system for gas feed in fuel supply in fuel station for vehicles - Google Patents

Abstract

The petrol fuelling facility of a station has a number of buried storage tanks (4-6) that are coupled to a common take line (3) having a pump (2) connecting with nozzles (1). A metering system is activated at the start of delivery. A diagnostic system provides a check on gas products in feed and return lines and uses a pressure difference signal (15).

Description

The invention relates to a method according to the preamble of Claim 1 and according to the preamble of the patent claims 2-4.

It is based on reports from the federal authorities (Federal Environment Agency in Berlin) and from information on the Internet of the C.A.R.B. (Air Resource Board) from California announced that service stations with Gas return facilities are equipped, but these have a high susceptibility to failure with total failure. Conditionally due to higher fuel temperatures in the car tank as a technological consequence Environmentally friendly cars with catalytic converters are the emissions from refueling increased significantly.

In practice, the above petrol stations were often only in the frame a simulation of a refueling checked. Such tests have the disadvantage that the test effort to find defective tap points with a decrease in the susceptibility to failure per defective tap increases. So the Federal Environment Agency has one automatic monitoring or an ISD (In-Station Diagnostic) based on the American model also at existing petrol stations required.

Such a method for controlling gas recirculation in individual storage tanks are known from DE 198 60 682.6-23. On this application as the main application is referred to. Further Methods are under DE 199 21 799.8 and DE 199 51 856.4 to which reference is also made.

US Pat. No. 5,269,353 - Gilbarco - describes a method after which a volume flow in a gas return line  by means of 2 pressure sensors before and after a gas pump in Dependence on the measured pressure difference is determined. One way these sensors for other functions and / or Use for several gas pumps is not shown.

In EP 04 61 770 A1 - Gilbaraco - is in the gas return line a pressure sensor in the flow direction in front of a gas pump built-in. A volume flow at the individual tap should be determined by means of the negative pressure indicated by the pressure sensor become. Again, it is not shown whether this can be used for Use the provided vacuum measurement sensor for other purposes can.

Because of the importance of refueling-related emissions and the technical variety of individual petrol stations and the variety a metrological need at filling stations is a method for Diagnosis needs which diagnoses of different Functional parameters at petrol stations, for existing and for New installations, made possible.

According to the invention, this object is achieved by the method according to the main claim 1 and the method according to claims 2-4 solved. Further embodiments of the invention are in the Claims 5-11 described.

As part of the planning and installation of diagnostics facilities can be assumed that the information on the amount and location of the tank of liquid fuel exist as part of the fuel bill. The Corresponding data on the tanked quantities are included custody transfer accuracy on individual petrol pumps and on the Cash machine available.

Generally usable information about the volume flows in the gas-carrying lines are currently not available. there have the measuring method, which is temporarily from the car tank coming supersaturated gasoline / air mixture through pure air  replace deficits in the way that an existing, more stable Operating state in the pipelines due to the supply of air in relation to the operating conditions, such as humidity, temperature, Density, aerosol content. . . for the duration of the measurement and the Function of subsequent refueling is unstabilized.

Regarding the construction of petrol stations with facilities for gas recirculation and the volumes in the gas-carrying part, it can be stated as a common factor that individual underground tanks have an extraction line for liquid fuel and are connected to one another via a gas return line. The volumes for holding the gasoline / air mixture are made up as follows:

• - a constant volume formed by pipes,
• - a larger variable volume in the free space above the Fuel.

If there are several gases in the above volume and / or more are added, "each of them spreads over the entire volume as if the other were not present, and the pressure is equal to the sum of the individual gases". According to E. Schmidt, Technische Thermodynamik, p. 42 Springerverlag 1960, this describes the DALTON law based on experience. For mixtures of gases at petrol stations that do not react chemically with one another, according to E. Schmidt, there are the following typical operating cases for gas recirculation and the removal of fuel in volume V from storage tanks:

• 1. Feeding a mixture into a constant volume V:
  Conditions / assumptions: V = constant;
  Temperature T ₁ = T ₂ ;
  Differential pressure p ₂ = Δp;
  Volume V ₂ V ₂ = m ₂ R ₂ T ₂ / p ₁ ;
• 2. Delivery of a mixture V2 and simultaneous withdrawal of a volume-equivalent liquid fuel quantity V2:
  Conditions / assumptions: p = constant;
  Temperature T ₁ = T ₂ ;
  Differential pressure Δp = 0;
  Total volume V = V ₁ + V ₂ ;
  Volume V ₂ V ₂ = quantity of fuel in "liters";
• 3. Withdrawal of a liquid fuel quantity ΔV with constant gas quantity:
  Conditions / assumptions:
  Temperature T ₁ = T ₂ ;
  Differential pressure Δp = p - p ₂ ;
  Total volume V = V ₁ + ΔV;
  Volume ΔV ΔV = quantity of fuel in "liters"; ΔV = Δp V ₁ / p ₂ ;

Result

The volume .DELTA.V of a gas quantity supplied or withdrawn from the total volume V is proportional to the measured pressure change and the ratio of the volume V to the total pressure p ₂ over the fuel.

Currently a publicly run in Germany Discussion of the use of rapid testers called for the Record failures of gas recirculation devices. A such rapid diagnosis is carried out according to the characteristic part of claim 1 achieved in that a pressure sensor to the Volume of a pipeline leading to the underground tank connected becomes. According to the small one effective in the pipeline Volume builds up when gas recirculation begins noticeable pressure on that as a pressure peak at the beginning of a Refueling and gas recirculation, according to the Representation in example 1, can be measured. It depends Training the pressure peak u. a. of the currently fed Gas volume. This pressure peak can be in the context of a Rapid tests using a mechanical sensor e.g. B. a U-tube or measured electronically.

Such a diagnostic method can be used in gas recirculation devices, which support gas production through pumps become. It is also suitable for the diagnosis of so-called passive working systems in which the gas production by means of a Sealing at the tank neck of the car is ensured.

Simultaneously with the demand for quick tests is to Achieve an effective emission reduction of the gasoline / air mixture in the storage tank as shown to check in example 2 above. Such Diagnosis according to the characterizing part of claim 2 achieved in that the volume supply in the entire volume, consisting of the free space above the fuel and the Pipeline volume according to the dependencies of example 2 above the duration of a refueling is checked. According to the characteristic in The preamble of claim 2 are the gas-carrying Pipelines to the outside z. B. via a valve on Vent mast at least temporarily completed. The The diagnosis described is also for gas recirculation directions that are constructed as a passive system are suitable.  

The advantage of these diagnoses is that the rapid tests and the exact control can be carried out via a measuring point and the adequate function over a measured value, namely Δp = 0, according to claim 2, according to example 2 can be defined. On time-consuming search for defective tap points e.g. B. in the context of This saves trial refueling.

According to the features in the characterizing part of the claim 3, an installation for quick tests can also be used for control the vapor tightness used in the entire gaseous volume become. The test pressure required for this in known Way z. B. is adjustable by the supply of nitrogen (N2) and then the amount of leakage as shown in example 1 as a negative pressure change Δp in the total volume V is measurable.

These vapor tightness measurements are also supported by heat and Metabolism over the fuel affects that one Change in volume caused by condensation or evaporation can.

According to the features in the characterizing part of claim 4 these influences after completion of the free space against the Atmosphere measured from the ambient pressure. In which the dependencies between volume and Pressure change Δp are shown in Example 1.

The general validity of the DALTON equations is for ideal gases specified. The respective dependency, also with different levels of storage tanks, can by the Removal of z. B. 5 l of fuel and the measurement of Pressure difference Δp, as shown in Example 3, determined become. In this case, the function of the gas recirculation furnishings deliberately interrupted.

In addition to the multiple use of a measuring point for multiple Functional diagnoses are advantageously based on the measured values  long valid scientific knowledge about the Mixing gases. When using electronic Pressure sensors show the other advantages that this Sensors partially with a security and one custody transfer approval for gas billing, on the part of PTB, e.g. B. are available from Rosemount.

For the above diagnoses, the data is on the fueled Petrol volume also with custody accuracy in the center Check-out room available.

A schematic description of the invention is to be taken from Figs. 1 and FIG. 2.

Show it:

Figure 1 is a diagram of a gas station with a typical pressure curve.

Fig. 2 is a diagram of a documentation of the measured values.

The representation in FIG. 1 is first described:
The diagram shows the gas recirculation device of a tap 1 with 3 valves 19 , which is actively supported by a pump 2 and is connected via a pipeline 3 to the gas-carrying volume of 3 underground tanks 4 , 5 and 6 . The effect of the smallest volume of the line to the storage tanks extends up to a branch 7 , from which a gasoline / air mixture can escape into the underground tanks 4 , 5 , 6 and to a ventilation mast 8 . As an example for existing petrol stations, the underground tanks 4 and 5 are connected to a line 12 for gas recirculation in parallel and / or the storage tank 6 is connected via a gas-carrying line 13 to the variable volume above the fuel, this line 13 also being used for loading / Venting can be used.

From the storage tanks 4 , 5 , 6 lead 3 lines for fuel removal 9 , 10 , 11 to individual taps z. B. the position 1 , pumps, regulating and shut-off devices not being specified in the diagram, required for the function.

An at least intermittent interruption of the gas exchange with the environment is possible by installing a valve 16 .

A volume increase in the underground tank that occurs when fuel is withdrawn is measured via a fuel meter 14 as volume flow F (flow indication). The measured value is displayed on the petrol pump and is documented in the cash desk.

A pressure sensor 15 can be connected to the constant volume of the pipeline 3 . This volume can be expanded by further tapping points 17 . The pressure measurements are also possible at taps with passive systems 17 , as shown here without a pump. As a connection point for the sensor 15 , a connection to the line 3 can be established in the foot of a petrol pump. It is advantageous to measure the pressure at one of the t-shaped connections 18 of the tapping points 1 , 17 with the line 3 .

A pressure curve Δp over a refueling at point 18 is shown in diagram 20 . The pressure 21 is plotted against the time 22 . A pressure curve 23 , 24 , 25 , 26 , 27 , 28 , 29 can result during operation of the gas recirculation device.

The start of gas production is indicated by the pressure rise 24 , 25 in line 3 . The pressure 26 , 27 shows the pressure curve in the sum of the gas-carrying volumes over the fuel. Point 27 marks the end of gas production. From the difference between the measuring points 24 and 28 , the differential pressure Δp can be determined over the duration of a refueling.

If gas production fails, the pressure could run along a line 30 . According to the pressure curve, further pressure peaks corresponding to lines 24 , 25 and 27 , 28 will be recognizable in the measured pressure curve when refueling is carried out at several tapping points.

In the case of a gas-tight closure 16 on the ventilation mast, the setpoint value and the actual value for refueling can be determined via the pressure curve. According to Example 2, the pressure should be at the end of the extension of line 23 , 24 or a setpoint for the corner points 24 , 28 of a refueling, e.g. B. Δp = 0; fulfill.

Pressure sensors based on U-tube manometers are already used when testing individual taps of passive systems. When using these sensors in the measuring point 15 , a quick test of a petrol station or a check of the susceptibility to faults can be carried out via a measuring connection. Based on this measuring principle, the recording of the measurement data and the scope of test functions for petrol stations can be expanded and improved by connecting electronic sensors.

The connection of an electronic sensor and the structure of an automatic monitoring will now be described in connection with FIG. 2.

A transducer 31 is connected to the gas return line 3 and the constant volume in this line via a line 32 which can be shut off. This line 3 leads to the underground tank 4 . A line 33 leads from the transmitter 31 to a computer unit 34 , from which the transmitter can be fed with a current of 4-20 mA.

In the implementation as an ISD center (in-station diagnostic), the computer unit 34 can be set up centrally. The data on the time and the amounts of refueling or volume withdrawals can be fed in via an input 35 .

An output 36 is provided for an analog recorder, another 37 for electronic data storage with a connectable printer 38 . An output 39 enables connection of further devices. Another output leads to a modem 40 , via which the data can be queried and managed centrally.

Deviations or interruptions in the feed current can be recognized in an amperage display 41 and reported as an alarm function. At the beginning of refueling, which is characterized by the fuel flow, the absence of the gas flow can trigger an alarm within seconds via a pressure-dependent display 42 with the function PIA (pressure indication alarm).

If the vent line 8 , 13 is terminated, the diagnoses can be documented via the outputs 36 , 37 in accordance with the features of claims 2-4.

example

for quick diagnosis
required fuel quantity approx. 1 liter
Setpoint pressure increase

24th

,

25th

,
Alarm message when pressure drops curve

30th

Personnel requirements at times 1 person

List of reference numbers

1

Tap

2

pump

3rd

Pipeline

4

Underground tank

5

Underground tank

6

Underground tank

7

branch

8th

Ventilation mast

9

Fuel line

10th

Fuel line

11

Fuel line

12th

Pipeline

13

Pipeline

14

Fuel meter

15

Pressure sensor

16

Valve

17th

Tap

18th

T-branch

19th

Valve

20th

diagram

21

Pressure axis

22

Timeline

23-29

Pressure values

30th

Pressure history

31

Pressure sensor

32

Connecting cable

33

management

34

Computing unit

35

Data input

36

Data output

37

Data output

38

printer

39

free exit

40

Output for modem

41

Amper display

42

Pressure display
It means:
p pressure
V volume
m amount
R gas constant of a mixture
T temperature

Claims (11)

1. Diagnosis of devices for gas recirculation, which are installed as part of the storage and refueling of petrol at petrol stations,
at least one line for supplying and discharging gaseous volumes and at least one line for fuel extraction being connected to the storage tanks,
at least one closable vent line for the space above the fuel and
a connection of a sensor suitable for differential pressure measurement is provided,
characterized in that
the pressure sensor is connected to the volume of the pipeline for gases leading to an underground tank and
When refueling begins, the effect of the volume supply on the pressure in the constant volume of the pipeline is measured as the actual value. 2. Diagnosis of devices for gas recirculation, which are installed as part of the storage and refueling of petrol at petrol stations,
at least one line for supplying and discharging gaseous volumes and at least one line for fuel extraction being connected to the storage tanks,
at least one closable vent line for the space above the fuel and
a connection of a sensor suitable for differential pressure measurement is provided,
characterized in that
the vent line to the atmosphere is closed, the pressure sensor is connected to the volume of the pipeline leading to an underground tank for gases and
the effect of the volume supply in the total volume above the free space of at least one storage tank as a result of refueling is measured as the actual value. 3. Diagnosis of devices for gas recirculation, which are installed at petrol stations as part of the storage and refueling of petrol,
at least one line for supplying and discharging gaseous volumes and at least one line for fuel extraction being connected to the storage tanks,
at least one closable vent line for the space above the fuel and
a connection of a sensor suitable for differential pressure measurement is provided,
characterized in that
the vent line to the atmosphere is closed, the pressure sensor is connected to the volume of the pipeline for gases leading to an underground tank and
the vapor tightness of the gas recirculation device is measured as the actual value at a pressure level that deviates from atmospheric pressure. 4. Diagnosis of devices for gas recirculation, which are installed as part of the storage and refueling of petrol at petrol stations,
at least one line for supplying and discharging gaseous volumes and at least one line for fuel extraction being connected to the storage tanks,
at least one closable vent line for the space above the fuel and
a connection of a sensor suitable for differential pressure measurement is provided,
characterized in that
the vent line to the atmosphere is closed, the pressure sensor is connected to the volume of the pipeline leading to an underground tank for gases and
the volume development over the fuel, which is given by heat and mass transfer processes, is measured as the actual value of the pressure curve that is developing. 5. Diagnosis according to one or more of the preceding claims, characterized in that the connection for the pressure sensor is provided in a shaft becomes. 6. Diagnosis according to one or more of the preceding claims, characterized in that when using an electronically working sensor, the Computer unit with data from the official fuel measurement is fed. 7. Diagnosis according to one or more of the preceding claims, characterized in that the computer unit is set up centrally and the connection to the sensor is created via a live cable. 8. Diagnosis according to one or more of the preceding claims, characterized in that the formation of a pressure peak as a setpoint for the beginning of Gas transport is used. 9. Diagnosis according to one or more of the preceding claims, characterized in that the lack of a pressure spike at the start of refueling with a Alarm message is connected. 10. Diagnosis according to one or more of the above Claims, characterized in that  the lack of a spike in pressure at the same time Refueling that starts later is linked to an alarm message becomes. 11. Diagnosis according to one or more of the above Claims, characterized in that the counts from a refueling, without the function of one Gas recirculation, at the same time as the fuel is withdrawn via the Interface are fed and for the closed volume A calibration curve for the physical over the fuel Relationship between the pressure change Δp and the volume change ΔV can be updated in the computer unit.