Process for generating at least one warning signal relating to the level in a product storage tank and device for implementing the process

• US 6,064,311 A
• Filed: 06/24/1998
• Issued: 05/16/2000
• Est. Priority Date: 06/26/1997
• Status: Expired due to Term

• Current Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Original Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Inventors: Viard, Nicolas, Barth, Frederic, Ferenczi, Laurent, Dulphy-Vigor, Veronique
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US09/103,503
• Time in Patent Office: 692 Days
• Field of Search: 340/605, 340/606, 340/612, 340/614, 340/618, 340/619-625, 73/290 R, 73/304 R, 73/304 C, 73/305, 73/307, 73/308, 73/311, 73/313, 73/302, 364/143, 364/144
• US Class Current: 340/618
• CPC Class Codes: F17C 2250/0434 Pressure difference
• CPC Class Codes: G01M 3/2892 for underground fuel dispensing systems G01M3/30 takes precedence
• CPC Class Codes: G01M 3/3263 using a differential pressure detector G01M3/3245, G01M3/3272 take precedence

Abstract

The process for generating at least one warning signal relating to the level in a tank (3) for storing a product (4) comprises the following steps:

the storage level of the product in the tank, together with the values of the product quantity consumed during predefined time intervals are determined,

these values are placed in memory together with the associated measurement instants,

at other successive instants

the values placed in memory of the product quantity consumed are used to calculate a value of the estimated quantity of product which will be consumed in the future,

this estimated value is subtracted from the last measurement value so as to obtain an estimated value of the storage level at a future instant,

this estimated value of the storage level is compared with a preset threshold, and

a warning signal is generated if the estimated value is less than the preset threshold.

Claims

1. Process for generating at least one warning signal relating to the level in a tank (3) for storing a product (4) with a view to the restocking of the tank (3), in which at least one measurement sensor (10) associated with the tank (3) is used to determine, at successive instants t₀, t₁ . . . t_i-1, t_i respectively, the values N₀, N₁ . . . N_i-1, N_i of the level of storage of the product in the tank (3), together with the values of the quantity of product Δ

N₁, Δ

N₂, . . . Δ

N_i-1, Δ

N_i consumed during the time intervals defined by two successive instants Δ

t₁ =t₁ -t₀, Δ

t₂ =t₂ -t₁, . . . Δ

t_i-1 =t_i-1 -t_i-2, Δ

t_i =t_i -t_i-1, comprising the following steps;

the measured values N₀, N₁, . . . N_i-1, N_i, together with Δ

N₁, Δ

N₂, . . . Δ

N_i-1, Δ

N_i and the associated measurement instants t₀, t₁ . . . t_i-1, t_i are placed in memory,

at successive instants τ

₀, τ

₁ . . . τ

_j-1, τ

_j which are spaced apart by time intervals Δ

τ

₁ =τ

₁ -τ

₀, Δ

τ

₂ =τ

₂ -τ

₁, . . . Δ

τ

_j =τ

_j -τ

_j-1 respectively, the time intervals Δ

τ

being predefined and their duration being greater than or equal to the time intervals Δ

t_n, n being any natural number lying between 0 and i, the values placed in memory of the product quantity consumed Δ

N_n during the time intervals Δ

t_n are used to calculate a value of the estimated quantity of product C_k which will be consumed between the instant τ

_j and the instant τ

_j+k, τ

_j+k being the k-th instant following τ

_j and spaced apart therefrom by the time interval δ

τ

_k =Δ

τ

_j+1 +Δ

τ

_j+2 + . . . +Δ

τ

_j+k,

this value C_k is subtracted from the most recent measured value N_i so as to obtain an estimated value N_i -C_k of the storage level at the instant τ

_j+k,

this estimated value N_i -C_k of the storage level is compared with a preset threshold θ

, and

a warning signal is generated if the estimated value N_i -C_k is less than the preset threshold θ

.

2. Process according to claim 1, characterized in that the values of the product quantity Δ

N_n consumed during the time interval Δ

t_n are determined by subtracting the value N_n of the storage level measured at the instant t_n from the value N_n-1 of the storage level measured at the instant t_n-1.

3. Process according to claim 1, characterized in that the value of the product quantity Δ

N_n consumed during the time interval Δ

t_n is determined by measuring by means of a second sensor the flow rate of product drawn off from the tank and by integrating this measured flow rate between the instants t_n-1 and t_n.

4. Process according to claim 1, characterized in that all the intervals Δ

t_n are equal.

5. Process according to claim 1, characterized in that the duration of the time intervals Δ

t_n is less than two hours, preferably less than one hour and especially equal to 30 minutes.

6. Process according to claim 1, characterized in that the time intervals Δ

τ

_i are multiples of the time intervals Δ

t_n and preferably, Δ

τ

_i is moreover equal to twenty-four hours or a multiple or twenty-four hours, i being any natural number lying between 0 and j+k.

7. Process according to claim 1, characterized in that each instant τ

_i corresponds to a given moment of a working day of a centre (42) for restocking the tank (3).

8. Process according to claim 1, characterized in that the total quantity of product N_tot which can be stored in the said tank (3) is placed in memory, and in that an estimate of the quantity of product L_j+k =N_tot -(N_i -C_k) which can be placed in the tank (3) during a restocking of the latter at the instant τ

_j+k is moreover calculated at the instants τ

_i.

9. Process according to claim 1, characterized in that the duration of the time intervals δ

τ

_k corresponds to a predefined delivery deadline.

10. Process according to claim 1, characterized in that the threshold θ

is made up of a critical stock depletion threshold θ

_c and a margin M, the margin M being chosen in such a way that the probability of the storage level dropping below θ

_c at the instant τ

_j+k-1 is almost equal to zero.

11. Process according to claim 10, characterized in that an emergency warning signal is generated if the estimated value N_i -C₁ is less than or equal to the critical threshold θ

_c, C₁ being the estimated quantity of consumption between two successive instants τ

_i.

12. Process according claim 8, characterized in that a warning signal is transmitted to a restocking centre (42) which is remote from the storage tank (3).

13. Process according to claim 12, characterized in that a signal corresponding to the estimated quantity of product L_j+k, which can be placed in the tank during a restocking of the tank (3) at the instant τ

_j+k is transmitted together with the warning signal.

14. Process according to claim 12, characterized in that a signal corresponding to the instant τ

_j+k at which the product storage level runs the risk of being less than the preset threshold θ

is transmitted together with the warning signal.

15. Process according to claim 12, characterized in that a signal acknowledging receipt of the warning signal is transmitted from the restocking centre (42).

16. A device for generating at least one warning signal, the device comprising:

a measuring means for measuring storage level information N_n of a product in a tank;

a clock for generating measurement times t_n ;

a central processing unit for utilizing the storage level information N_n measured by said measuring means and for computing a value C_k of the estimated quantity of the product which will be consumed during a future time interval Δ

τ

_k ;

a memory unit connected to said central processing unit for holding the measurement times t_n output by said clock, storage level information N_n corresponding to the measurement times t_n, and product quantities Δ

N_n consumed during the time interval Δ

t_n ;

a means for placing at least one storage level threshold θ

into another memory unit;

a comparison means for comparing the projected value of the storage level N_i -C_k at a future time τ

_j+k with the at least one storage level threshold θ

;

a warning generation means controlled by said comparison means for generating a warning signal; and

a transmission means linked to said central processing unit for transmission to a restocking center a signal corresponding to the value L_j+k of the quantity of the product which can be placed in the tank during a restocking at the future time τ

_j+k and for transmission of a signal corresponding to the future time τ

_j+k.

17. The device according to claim 16, wherein said transmission means is controlled by said warning generation means.

18. The device according to claim 16, wherein said measuring means comprises a sensor for measuring a differential pressure between two capillaries, wherein a first of said two capillaries is linked to a high point of the tank, and a second of said two capillaries is linked to a low point of the tank.

19. The device according to claim 16, further comprising a display unit for displaying the type of product contained in the tank and the storage level information N_n of the storage level of the product.

20. A device according to claim 18 further comprising

a means for receiving information sent by a restocking center.

21. The device according to claim 20, further comprising a display unit for displaying an acknowledgment of receipt by the restocking center of the warning signal generated by said warning generation means.

22. The device according to claim 16, further comprising a display unit for displaying an acknowledgment of receipt by the restocking center of the warning signal from the device.

23. A tank level storage indication and prediction system, the system comprising:

a tank for storing a product;

a measuring means for measuring storage level information N_n of a product in a tank;

a clock for generating measurement times t_n ;

a central processing unit for utilizing the storage level information N_n measured by said measuring means and for computing a value C_k of the estimated quantity of the product which will be consumed during a future time interval Δ

τ

_k ;

a memory unit connected to said central processing unit for holding the measurement times t_n output by said clock, storage level information N_n corresponding to the measurement times t_n, and product quantities Δ

N_n consumed during the time interval Δ

t_n ;

a means for placing at least one storage level threshold θ

into another memory unit;

a comparison means for comparing the projected value of the storage level N_i -C_k at a future time τ

_j+k with the at least one storage level threshold θ

;

a warning generation means controlled by said comparison means for generating a warning signal; and

a transmission means linked to said central processing unit for transmission to a restocking center a signal corresponding to the value L_j+k of the quantity of the product which can be placed in the tank during a restocking at the future time τ

_j+k and for transmission of a signal corresponding to the future time τ

_j+k ;

a means for receiving information sent by a restocking center; and

a display unit for displaying an acknowledgment of receipt by the restocking center of the warning signal generated by said warning generation means.