Method of recovering vapors emitted when a liquid is dispensed

SWEDEN (12) PATENT (13) C2 tu) 523 952

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2004-06-08

1999-10-25

1999-04-23

1999-04-23 (19) SE ₍₅₁₎

International class⁷

B67D 5/04 (21)

PATENT AND REGISTRATION (45) (41) (22) (24) (62) (86) (86) (83)

Patent filed Application widely available The patent application was submitted on expiration date

Tribal application number International filing day Filing date dares to apply for European patent Deposit of microorganism

Patent Application Number 9901463 1

Application received as:

Swedish patent application completed international patent application with number □ converted European patent application with number (30)

1998-04-24 FR 9805196 (73) (72) (74) (54) (56) (57)

Assignee

INVENTOR

AGENT

NAME

Tokheim Services France, Avenue Galilee 92350 Le Plessis Robinson FR

Jacques Fournier, Bretigny Sur FR, Claude Redon, Taverny FR Noréns Patentbyrå AB

Process for recovery of vapors emitted when a liquid is dispensed

CALLED PUBLICATIONS:

WO 9706095 (B67D 5/04)

SUMMARY:

A process for recovering vapors emitted when liquid is discharged to a tank, in particular a fuel tank, by means of a plant comprising:

means for dispensing liquid, means for measuring a liquid flow rate Q_Lmeans for recovering vapors at a vapor flow rate Qv controlled by a value g characteristic of the recovery means, means for measuring the vapor flow rate Qv, and where, according to the invention, an original calibration of the recovery means is performed after installation in place by suction of air.

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The numbers in brackets indicate international identification code, INID code. Letters in chiams indicate international document code.

523 952

Summary

A process for recovering vapors emitted when liquid is dispensed to a tank, in particular a fuel tank, by means of a plant comprising:

means for dispensing liquid, means for measuring a liquid flow rate Q_L, means for recovering vapors at a vapor flow rate

Q_v controlled by a value g characteristic of the recovery means, means for measuring the steam flow rate Q_v, and where, according to the invention, an original calibration of the recovery means is carried out after installation on site by suction of air.

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The present invention relates to a process for recovering vapors emitted when a liquid is discharged to the interior of a tank.

The invention is particularly advantageous when used in the field of fuel distribution for, for example, motor vehicles, such as a means for recovering hydrocarbon vapors emitted from the tank in the vehicle when filled with liquid fuel.

A liquid dispensing system such as motor vehicle fuel usually consists of liquid dispensing means, generally comprising dispensing means provided with pumps designed to deliver the fuel from a storage tank to the tank of the vehicle at a fluid flow rate Q_L. The distributing means also has a system for measuring the liquid, connected to a pulse generator, to enable a computer to determine the volume and price of the supplied liquid, which are shown on a display provided with the distributing means.

Further, if the system is provided with means for recovering released hydrocarbon vapors, the system has recycling means designed to deliver the vapors at a vapor flow rate Qv through a channel from the tank of the vehicle to a collection tank, e.g. the storage tank, wherein the steam flow rate Q_vis controlled by a value g characteristic of the recovery means to maintain a proportionality ratio Q_v = k * Q_L between the steam flow rate Q_v and liquid flow rate Q_l, where k is equal to or close to 1. Finally, measuring means will allow the vapor flow rate Qv to be determined.

For the most part, the recovery means include a pump which sucks the vapors from the tank to deliver them to the hydrocarbon storage tank. When this is the case, the characteristic p: \ patranor \ docs \ doctemp \ final presentation.inl.doc, 3/3/2004

523 952 value g to be the rotational speed of the pump, which is controlled by the pulse generator of the distributor.

In most cases, however, it is not possible to simply impose a pump proportional to the fluid flow rate Q_L.

In practice, operating conditions can vary considerably from one system to another depending on:

pressure losses in the recovery duct, upstream and downstream of the pump, there may be calibrated valves at the level of the collection tank and which may cause a pressure therein that differs from atmospheric pressure, corresponding to an additional pressure loss applied to the pump in the recovery duct, internal leakage in the recovery pump, / downstream pressure difference affecting efficiency.

In summary, in order to achieve a given steam flow rate Qv, a rotational speed must be applied to the recovery pump and this depends on the system.

In order to take into account the aforementioned parameters, it is in practice common to calibrate the entire system when installed on site. During this calibration procedure, a recovery pump speed and the corresponding steam flow rate Q are set._v is measured using a flow meter or gas counter. Accordingly, a relationship between the velocity and the vapor flow velocity Q is determined_v by making a sufficient number of measurements to determine the characteristics of the pump under these operating conditions. This ratio is stored in the memory of a microcomputer.

During normal operation, the flow meter is turned off when hydrocarbons are discharged at a liquid flow rate Q_L, and the microcomputer searches for the speed to be applied to the recovery pump so that Qv - Ql · p: \ patranor \ docs \ doctemp \ final publishing.inl.doc, 2004-03-03

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However, this known recycling method according to WO 97/06095 has the following disadvantages:

Pressure losses can occur in the recycling channel over time as a result of:

- gradual partial blockage due to dust, change in cross-sectional area of ​​elastomer tubes due to prolonged presence of hydrocarbons. This is particularly common in the portion of the duct located upstream of the pump, which is usually in the form of an elastomeric tube surrounded by fluid under pressure, as this portion represents the core of a coaxial flex tube.

internal leakage that can develop in the pump due to wear, for example. is the case of centrifugal pumps, the density of the vapors which will vary depending on the hydrocarbons and the temperature of the vehicle tanks as the ambient temperature changes, thereby changing the effect that the upstream and downstream pressure losses will have, the vapor pressure in the collection tank may also vary depending on the hydrocarbons and temperature.

Accordingly, the technical problem which the invention is intended to solve is to propose a process for the recovery of vapors dispensed when a liquid is dispensed to a tank by means of a system comprising:

means for dispensing the liquid, designed to deliver the liquid at a fluid flow rate Q_L from a storage tank to the tank, means for measuring the fluid flow rate Q_Lmeans for steam recovery, designed to deliver the vapors at a vapor flow rate Qv from the tank to a collection tank, the vapor flow rate Q_v controlled by a value g characteristic of the recovery means, means for measuring the steam flow rate Q_v, p: \ patranor \ docs \ doctemp \ finalfbreläggande.inl.doc, 3/3/2004

523 952 wherein this method, which takes into account the gradual change in characteristic parameters of the steam as it is fed along the recovery channel, allows a time-delayed recalibration of the characteristic value g to be performed as a function of the measured steam flow rate Q_v.

The solution proposed by the invention as a way of solving this technical problem is a process comprising the following steps, wherein:

after the installation has been carried out on site, a single initial calibration of the recovery means is performed by suction of air and by varying the parameter g in steps, i, and by measuring for each value g ° i on g corresponding to the flow rate Q_Vi for air to create an original calibration table T_O:

To = [g ° i, Qvi] thereafter, under actual operating conditions and at each liquid dispensing event, n:

measurement of steam flow rate Q_v at each time interval and calculation of a similarity coefficient K_n as a function of the differences between the measured values ​​of Q1 and Qv to create a corrected calibration table T_n from experimental measurements and using the original calibration table obtained by air intake as a reference, so that:

Tn - tgⁿi, Qvi] = K_n* Two and measurement of fluid flow rate Q_L at regular time intervals using as characteristic magnitude g a value determined from the corrected calibration table T_n-i created by experimental measurements performed during the previous output n-1.

Accordingly, as will be explained in more detail below, the value used by the procedure is: \ patranor \ docs \ doctemp \ final-submission.inl.doc, 3/3/2004

523 952 the finding of the characteristic value g when fluid is output a value determined from the creation of the calibration table during the previous dispatch event, while a new updated calibration table is created in preparation for the next dispatch event.

In order to take into account any pressure drop in the ducts, according to the invention it is proposed that the steam flow rate Q_v is measured by a vapor flow velocity value Q supplied by a flow meter in series with the recovery means, Q being corrected by a pressure factor P / Pa where P is the pressure measured at the level of the flow meter and Pa is the atmospheric pressure.

In a further developed version of the method, the invention proposes that:

during the initial calibration step, an original correlation table Hq is created which links the vapor flow rate Qv to the vapor flow rate Q for vapors indicated by the flowmeter (123):

hrs_O = [Qⁿi, during the liquid dispensing event n:

flow rate Qⁿ for vapors indicated by the flow meter at each time interval is compared with the flow rate Q^N_1i defined by the correlation table H_n__LZ

Hn-l = [Q^{n 1}j 'QlI where Qvi = Ql' the value g^N_1j is set in step 5g during the output event so that the value of Qⁿ moves closer to that of Q^n_at the end of the output case, a second coefficient of similarity k is calculated_n on the basis of the differences between the measured values ​​of Qⁿ and Q_v, a new correlation table H_n is prepared in preparation for the next dispatch event n + 1 by:

hn ⁼ [Q i 'Qvil ⁼ * Ho

During the output, this further development allows the value g^N_1j can be adjusted by the value g supplied by the calibration table such that the vapor flow rate Q_v is as close as p: \ patranor \ docs \ doctemp \ finalforeläggande.inl.doc, 3/3/2004

523 952 possible to the flow rate Q_we as defined by Table H_n-i and therefore also the fluid flow rate Q_L without, however, really reaching the latter.

Two special but not exclusive embodiments of the method according to the invention are proposed.

In a first embodiment, the recovery means consists of a fixed rate recovery pump and a valve with a variable aperture, the characteristic value g being the effective channel cross-section of the valve.

In a second embodiment, the recovery means consists of a variable speed recovery pump, the characteristic value g being the speed of the recovery pump.

The description given below with reference to the accompanying drawings, which are by way of example only and are not limiting in any way, will provide a clearer understanding of what the invention encompasses and how it may be used. Fig. 1 is a diagram of a first embodiment for implementing the method according to the invention; Fig. 2 is a diagram for a second embodiment for implementing the method according to the invention; 3 a graph illustrating an original calibration table proposed by the method according to the invention; and Fig. 4 a graph illustrating an original correlation table proposed by the method according to the invention.

The diagram in Fig. 1 illustrates a plant for dispensing liquid, e.g. fuel, to the interior of a tank in a motor vehicle, not illustrated.

This plant has fuel delivery means, substantially comprising a pump P_L designed to deliver the fuel L at a fluid flow rate Q1 from a storage tank 100 to the tank along a channel 110 to a discharge nozzle 111.

As already mentioned above, a distributor 112, possibly including the liquid pump P, has_L, a measuring device 113 located at ip: \ patranor \ docs \ doctemp \ final presentation.inl.doc, 3/3/2004

523 952 channel 110 in series with pump P_L so that a pulse generator

114, coupled to the measuring means 113, will supply a pulse signal representative of the fluid flow rate.

Q1 and as a computer 115 translates to the volume and price displayed on a display 116.

The plant illustrated in Fig. 1 also has means for recovery of gases V delivered when the liquid is discharged to the vehicle tank. In the example of Fig. 1, the recovery means mainly comprises a recovery pump P_v at a variable rate W, designed to deliver the vapors at a steam flow rate Q_v along a channel 120, from the tank, passing through the discharge nozzle 111, to a collection tank 100 which, in the case of Fig. 1, is also the storage tank for the liquid 75 shaped fuel.

In a practical way, the steam soldering velocity Q is measured_v of a vapor flow rate value Q supplied by the flow meter 123 located in series with the pump P_v, where Q is corrected by a pressure factor of 20 P / Pa where P is the pressure measured by a sensor 122 at the level of a flow meter 123 and Pa is the atmospheric pressure:

Qv = Q * P / Pa

By way of example, the flow meter 123 may conveniently be a fluid oscillator.

in the case of Fig. 2, the recovery means consists of a pump P_v with a fixed speed wo and a valve 126 with variable opening.

Regardless of the design chosen, the method of the present invention comprises applying a value g characteristic to the recovery means for a value such as the vapor flow rate Qv which, as a result, is as close as possible to the liquid flow rate Q_L. In the examples in Fig. 1, the value g is the variable speed w of the recovery pump P_v and the effective duct cross section Rx of valve 126, respectively.

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For this purpose, an electronic control system 121, 121 'receives information relating to the fluid flow rate Q_L from the pulse generator 114 and partly information relating to the steam flow rate Q_v from the measuring means 123, 122. This information is then processed by the electronic control system so that a control signal can be supplied to the motor M_v for the recovery pump P_v or solenoid valve 126, to bring the characteristic value g, speed W of pump P_v or the effective cross-section Rx of the solenoid valve 126, to a value determined by the electronic control system which provides the best fit between the flow rates Q_v and Q_L.

The method according to the invention comprises a first initial calibration phase for the recovery means by air suction.

During the first phase, the fluid flow is not activated. The pump P_v for the recovery of the vapors, on the other hand, is started to allow air to be sucked in through the opening in the nozzle

111th The control electronics 121 or 121 'supply to the motor M_vfor the pump PV or to the solenoid valve 126, an activation signal set for a period At, corresponding to a value g ° for the relevant characteristic value g, the index 0 indicating that this is the initial calibration phase. The activation signal is then incremented step by step, which produces an increase step by step of the value g °. Accordingly, a known value g ° and a value Q correspond_Vi for the steam flow rate resulting from the reading of the flow rate Qi taken from the flow meter 123 and corrected by the pressure factor Pi / Pa against each step i.

The set of pairs of degrees and Q_Vi forms an original calibration table Tq ··

To = [g ° i, Qvil

This table T_O, illustrated by the curve in Fig. 2, is stored in the memory of the electronic control system.

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After the initial calibration, the recycler is ready to dispense liquid for the first time. The user hooks off the nozzle 111 and fills the tank of his vehicle with a fluid flow rate Q_L, whose value is transferred from meter 113 to the electronic control system which will then search the table T_O for the value g ° j to be imposed on the corresponding value g at Q_Vj = Q_L:

T₀ = Cg ° J / QlJ

At this stage, the vapor flow velocity corresponding to gue cannot reach Q_l since the device has been calibrated with air. Since, in the case of a fuel, the density of the vapors from the liquid is higher than that of air, the pressure drop increases, which tends to reduce the absolute pressure P on the suction side of the pump P_v and as a result, the steam flow rate Q is reduced_v. About Q_l to be really achieved, g would need to be increased by a value g indicated in Fig. 3, to compensate for a decrease in the efficiency of the recovery pump P_v. This is exactly the purpose proposed with the method according to the invention. In operation, during the dispensing time, the fluid flow rate Q1 is measured at regular intervals, e.g. every 500 ms, and stored in the memory of the electronic control system. For each value of Q1 measured in this way, the value g ° j to be added to the value g is obtained from the table T_O.

Measurements and readings on values ​​Q are taken from the flow meter 122 and also stored in the memory every 500 ms.

At the end of the first output, the value Q is obtained_v for the steam flow rate from each pair of stored values ​​of Q and P through the equation:

Qv = Q * P / Pa.

Finally, a similarity coefficient Κχ is calculated based on the observed differences between the different values ​​of Q_L and

Qv, to be able to determine a new calibration table Τχ to be used for the next dispatch event:

Ti = [g¹!, Qvil = Ki * T₀ p: \ patranor \ docs \ doctemp \ final presentation.inl.doc, 3/3/2004

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The coefficient of similarity K_x can be calculated as follows, e.g. for each measurement 1 taken every 500 ms, a ratio K¹! defined by:

K¹1 = Qlx / Qvi.

is calculated, whereby the coefficient K_x is obtained as an average for all conditions K¹!·

Then:

Ti = [K_LZ g ° i, Q_we]

With the second dispensing time, the measurement of the fluid flow rate Q1 will allow a corresponding value g¹j, to be added to the value g, to be determined by:

Ti = [g¹!, Ql! ·

This time, if no significant difference occurs in the form of pressure losses in the channel 120 and the density of the vapors, the vapor flow rate Q_v forced by g¹! substantially equal to the liquid flow rate Q_L. In general, there will be variations on the temperature of the recovery pump P_v varies, especially if there is a rapid succession of customers at the service station during peak hours. Similarly, during the day, vehicles get warmer as does the fuel in their tanks and the density of the vapors increases.

In the same way as at the first output, the values ​​of Q and P are stored at regular intervals so that, when the output process is over, it becomes possible to calculate a series of values ​​of Q_v which can be compared with the corresponding values ​​of Q_l and can then be used to obtain a new similarity coefficient K₂ and determine a new calibration table T₂:

T₂ = [g²iz Qvi] = K₂ * T₀ which can be used for a third dispatch event, whereby the same process is repeated from one dispatch event to the next.

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It should be noted that the use of a flow meter 123 and a pressure sensor 122 will enable abnormal conditions to be detected in the operation of the steam recovery device, such as:

an abnormal change in pressure loss. If the pressure loss is too great, there may be a blockage in the duct, or a leak if it is too low, an inability to achieve the desired steam flow rate even when the speed w of the pump P_v or the effective cross-section Rx of valve 126 is at its maximum value. This indicates that either pump is P_v worn or the pressure drop in the recovery duct is too large, the steam flow rate Q_v is zero when the fluid flow rate Q_l is not zero. From this it can be concluded that the pump P_v is out of order.

In all cases, it is possible to activate an alarm signal.

The process for the recovery of gases described above can be further developed as follows.

During the initial calibration phase, using air suction can, in addition to calibration table T_O, another table H is set up_O, referred to as the original correlation table, which links the vapor flow rate Q_v to the vapor flow rate Q indicated by the flow meter 122 for each step of:

hrs₀ = [Q ° i, Qvi]

This Table H_O, illustrated by the curve in Fig. 4, represents the ratio of the flow rate of vapors read by the flow meter to the actual vapor flow rate. This curve changes depending on the density of the vapors and falls into pressure in the duct.

When the liquid such as e.g. fuel is discharged for the first time, the electronic control system seeks the original calibration table Tq for the value g ° j to be imposed on the value g for the period of 500 ms, corresponding to Qvj = Ql, as explained above. During the same period, the values ​​Q are placed¹, P¹ p: \ patranor \ docs \ doctemp \ finalfeleläggande.inl.doc, 3/3/2004

523 952 and Q_l in the memory. Since the function applies to fuel vapors while the table Tq is formed with air, again the actual flow rate of the vapors Q_v being too low (Qv &lt;Ql) ·

The electronic control system will then compare the flow rate Q¹ indicated by the flowmeter with the value Q ° j at each time interval:

hrs₀ = [Q ° j, Ql!

In general, Q¹ &lt;Q ° j (see Fig. 4). To compensate for this difference, the value of g is adjusted with the step 5g during the output process starting from the value g ° j so that the value of Q¹ will move ever closer to Q ° j until they may coincide.

At the end of the first output, the electronic control system uses the values ​​of Q¹! and P¹! stored in memory for each regular interval 1 of 50 ms to form a series of vapor flow rate values ​​QVi = Q χ * P χ / Pa, which will allow to determine a second similarity coefficient k¹! on the basis of the differences between Q¹! and QVi and a similarity coefficient kx obtained as the mean of coefficients k¹! · This coefficient k_T was used to update the correlation table Hq in preparation for the next liquid dispensing event:

Ηχ = ki * H_O = [Q¹!, Q_we]

For example, k¹1 = Q¹x / Qviz also

Ηχ = [kx * Q ° x, Q_we]

The procedure is repeated in the same way for the second and subsequent output case.

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