DE102018108214A1 - Tank arrangement and method for level control - Google Patents

Abstract

Method and tank arrangement for level control of cryogenic media, comprising: a tank (6) with an inflow line (10) and a discharge line (12), a differential pressure measuring device (16) connected via a connecting line (26) to a lower tank area (28) is connected, in which the liquid portion of the medium is present, and also via another connecting line (20) to an upper tank region (22) is connected, in which the gaseous portion of the medium is present, an absolute pressure measuring device (18) and or a temperature sensor (18) for measuring the pressure and / or the temperature in the upper tank region (22), an evaporator (38) in a branch line (36) between the inflow line (10) and the upper tank region (22) Pressure control suitable, the evaporator (38) in the branch line (36) downstream gas pressure control valve (34) for controlling the pressure in the upper tank area (22), one with the differential pressure measuring device (16) as the absolute pressure measuring device (18) and / or a temperature sensor (18) connected bottom pressure regulator (32) for controlling the gas pressure control valve (34), wherein the bottom pressure regulator (32) is configured, the pressure in the gaseous portion of the medium in the Tank (6) depending on the level of the liquid portion of the medium to a constant ground pressure to regulate.

Description

The invention relates to a tank arrangement for cryogenic media and to a method for level control of cryogenic media in a tank arrangement.

From the DE 20 2014 102 808 U a tank assembly for level measurement of cryogenic fluids is known, comprising a tank and a differential pressure gauge, which is connected via a fluid line to the lower tank area in the liquid portion of the cryogenic medium and also via a further fluid line to the upper tank area in the gaseous portion of the Cryogenic medium is connected. A temperature sensor for detecting the temperature of the fluid and / or an absolute pressure measuring device serve to detect the pressure in and / or the temperature of the fluid in the upper tank area. An evaluation unit, which communicates with the differential pressure gauge and the absolute pressure measurement submission and / or the temperature sensor, calculates the fill level on the basis of the determined values. In this tank arrangement, only the level is measured so that the potential of this tank assembly can not be exhausted.

The invention has for its object to provide a tank assembly by which not only the level can be measured, but extended in the application of the known tank assembly and energy-saving operation of the tank assembly is to be achieved.

To achieve the object, a tank arrangement according to the invention for level control of cryogenic media comprises a tank with an inflow line and a drain line. Further, the tank assembly detects a differential pressure measuring device, which is connected via a fluid line to a lower tank area in which the liquid portion of the medium is present and is connected via a further fluid line to an upper tank area in which the gaseous portion of the medium as a gas bubble is present, an absolute pressure measuring device and / or a temperature sensor for measuring the pressure and / or the temperature in the upper tank area. In addition, the tank arrangement comprises an evaporator in a branch line between the inflow line and the upper tank area of the tank. Furthermore, the tank arrangement comprises a control unit which regulates a gas pressure control valve which is suitable for pressure control and follows the evaporator in the branch line in order to control the pressure in the upper tank area. Furthermore, the control unit and a ground pressure regulator connected to the differential pressure measuring device and the absolute pressure measuring device and / or a temperature sensor for controlling the gas pressure control valve, wherein the ground pressure regulator is configured, the pressure in the gaseous portion of the medium in the tank depending on the Level of the liquid portion of the medium to a constant ground pressure to regulate.

When the ground pressure is regulated to the constant target value, the pressure in the gaseous medium required to maintain the target ground pressure decreases with increase of the liquid medium, resulting in a saving of required medium in the operation. This evaporates a minimal amount of liquid medium over the lifetime. When the gas pressure control valve is directly driven by the control unit using the absolute pressure and / or the temperature in the upper tank area as a controlled variable, the control margin can be reduced and the gas bubble in the upper tank area can be made smaller. Finally, it is advantageous that in the tank arrangement according to the invention, the functions of the bottom pressure regulator and the gas pressure control valve complement each other by the gas pressure control is used both for controlling the gas pressure in the gas bubble in the upper tank area and for ground pressure control.

According to an advantageous embodiment of the invention, a memory is provided in the control unit, in which a desired pressure in the gaseous portion of the cryogenic medium in the tank is preferably stored as a function or table depending on the level of the liquid portion of the cryogenic medium.

A temperature sensor in the branch pipe may be used in the region of the gas pressure control valve for controlling the flow rate such that an evaporator disposed in the branch pipe is capable of evaporating the amount of gas passed by the control valve. When the temperature sensor measures a temperature indicative of liquid medium, the flow of the medium through the gas pressure control valve is throttled to the point where the evaporator can completely vaporize the medium arriving at the gas pressure control valve, allowing the tank assembly to operate smoothly.

According to an advantageous embodiment of the invention, the tank arrangement comprises a flow measuring device in the inflow line and in the control unit a flow regulator configured to control the inflow of the cryogenic liquid through an inflow control valve in the inflow line. According to an alternative embodiment, the tank arrangement comprises a flow meter in the drain line and in the control unit a flow regulator configured to To regulate outflow of cryogenic liquid through a drain control valve in the drain line. When the inflow of the cryogenic liquid to the tank is controlled in consideration of a control signal from the bottom pressure regulator and the inflow controller, and when the outflow of the cryogenic liquid from the tank is controlled taking into account a control signal of the bottom pressure regulator and the outflow regulator, then advantageously For the target discharge velocity or the target inflow rate required ground pressure can be adjusted so that the specifications are met and that a predetermined outflow or inflow rate can be kept constant. As a result, a much more accurate and above all safer filling and emptying of the tank can be achieved.

To achieve the object, a method for level control of cryogenic media according to the invention comprises the features of claim 7, while advantageous embodiments of the method according to the invention are characterized in the remaining subclaims. The advantages are achieved analogously to those of the tank arrangement according to claims 1 to 6.

Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

• 1 eine schematische Darstellung eines ersten Ausführungsbeispiels der erfindungsgemäßen Tankanordnung, und
• 2 eine schematische Darstellung eines zweiten Ausführungsbeispiels der erfindungsgemäßen Tankanordnung.

In the description, the claims, and the drawing, the terms and associated reference numerals used in the list of reference numerals below are used. In the drawing:

• 1 a schematic representation of a first embodiment of the tank assembly according to the invention, and
• 2 a schematic representation of a second embodiment of the tank assembly according to the invention.

1 shows a tank arrangement 2 for regulating the level 4 in a tank 6 that with a cryogenic medium 8th to be filled. The Tank 6 is with an inflow line 10 and a drainage line 12 connected. The tank arrangement 2 includes a control unit 14A equipped with a differential pressure measuring device 16 , an absolute pressure measuring device 18 and a flow sensor in the drain line 12 connected to receive measurement signals. The absolute pressure measuring device 18 is via a connection cable 20 with an upper tank area 22 connected and accordingly detects the absolute pressure in the gas bubble in the upper tank area 22 , The differential pressure measuring device 16 is through a connecting line to the upper tank area 22 and with a connecting cable 26 with the lower tank area 28 connected, in which the liquid portion of the liquid medium is present. The differential pressure measuring device 16 therefore detects the differential pressure between the pressure in the upper tank area 22 and in the lower tank area 28 ,

The differential pressure measuring device 16 and the absolute pressure measuring device 18 are with a control unit 14A connected, in which boiling curves and density curves are available for selection for different media. These media are, for example, nitrogen, oxygen, argon, carbon dioxide or natural gas. With the measured values of the absolute pressure as well as the differential pressure can be considered taking into account the on the control unit 14A stored data accurate calculation of the volume of liquid state in the medium state and thus the level done.

The control unit 14A includes a memory 30 in which boiling curves and density curves for different media, that is, target pressure values for the pressure in the gaseous portion of the cryogenic medium in the tank 6 are stored as a table or function depending on the level of the liquid portion of the cryogenic medium.

The control unit 14A further includes a bottom pressure regulator 32 , which as input the output signals of the differential pressure measuring device 16 and the absolute pressure measuring device 18 receives and a control signal for the controlled variable Y _pB which outputs a gas pressure control valve 34 with which the pressure in the gas bubble in the upper tank area 22 according to the controlled variable Y _pB is controlled. The gas pressure control valve 34 lies in a branch line 36 from the inflow line 10 to the upper tank area 22 and controls together with an evaporator 38 who is in the branch line 36 between the inflow line 10 and the gas pressure control valve 34 is positioned, the inflow of vaporized medium in the upper tank area 22 , When the pressure in the upper tank area 22 gets too high, the pressure is over an overflow valve 40 relieved. When the pressure in the upper tank area 22 too low, liquid medium is added to the evaporator 38 delivered, evaporated there and via the gas pressure control valve 34 to the upper tank area 22 delivered until a corresponding target pressure in the upper tank area 22 is reached, whereupon the gas pressure control valve 34 closed again.

$${\text{y}}_{\text{Qaus}}=\text{f}\left({\text{e}}_{\text{Qaus}}{\text{, }\dot{\text{e}}}_{\text{Qaus}}\text{, }{\displaystyle \int {\text{e}}_{\text{Qaus}}\text{ dt}}\right)$$

wobei e_Qaus die Regeldifferenz für die Durchflussgeschwindigkeit in der Abflussleitung, Q_{AUS SOLL} die Soll-Durchflussgeschwindigkeit in der Abflussleitung, Q_{AUS IST} die Ist-Durchflussgeschwindigkeit in der Abflussleitung, Y_QAUS die Regelgröße für die Durchflussgeschwindigkeit in der Abflussleitung, , ė_Qaus die zeitliche Ableitung der Regeldifferenz und ∫e_Qaus dt das Integral von der Regeldifferenz nach der Zeit bedeutet.The control unit 14A includes a flow regulator 42 , which as input the output signal of the flow measuring device 44 receives and a flow control signal for the controlled variable Y _QAUS which outputs a flow control valve 45 controls, with the flow in the drain line 12 according to the controlled variable Y _QAUS is controlled. The flow control valve 45 is in the drainage line 12 downstream of the flowmeter 44 , The flow regulator 42 regulates the flow through a flow control algorithm Q _out by providing a flow control signal for the controlled variable Y _QAUS to the flow regulator 42 is delivered. $${\text{e}}_{\text{Qaus}}={\text{Q}}_{\text{OFF SHOULD}}-{\text{Q}}_{\text{IS OVER}}$$

$${\text{y}}_{\text{Qaus}}=\text{f}\left({\text{e}}_{\text{Qaus}}{\text{.}\dot{\text{e}}}_{\text{Qaus}}\text{.}{\displaystyle \int {\text{e}}_{\text{Qaus}}\text{dt}}\right)$$

in which e _Qaus the control difference for the flow rate in the drain line, Q _{OFF SET} the target flow rate in the drain line, Q _{IS OFF} the actual flow rate in the drain line, Y _QAUS the control variable for the flow velocity in the discharge line,, ė _Qout the time derivative of the control difference and ∫e _Qaus dt the integral of the control difference after the time.

Finally, to regulate the flow rate of the medium in the branch line 36 between the gas pressure control valve 34 in the branch line 36 and the upper tank area 22 a temperature sensor 46 arranged, which determines the temperature of the medium in the branch line 36 measures and the appropriate readings to the control unit 14A emits. In the control unit 14A it is then determined whether the temperature of the medium at the temperature sensor 46 is in a range in which the cryogenic medium is liquid. If so, the flow through the evaporator is throttled so far that the evaporator 38 is capable of that of the gas pressure control valve 34 to let vaporized gas flow through. This will ensure that there is no liquid medium over the branch line 36 in the upper tank area 22 arrives.

$${\text{y}}_{\text{pB}}=\text{f}\left({\text{e}}_{\text{pB}},{\dot{\text{e}}}_{\text{pB}},{\displaystyle \int {\text{e}}_{\text{pB}}\text{ dt}}\right)$$

wobei e_pB die Regeldifferenz für den Bodendruck, p_{B SOLL} der Soll-Bodendruck, p_{B IST} der Ist-Bodendruck und Y_pB das Stellsignal am Ausgang des Bodendruckreglers, ė_pB die zeitliche Ableitung der Regeldifferenz und ∫e_pB dt das Integral von der Regeldifferenz nach der Zeit bedeutet.The tank arrangement according to the invention is designed such that a desired pressure in the gaseous medium is determined from the measured values for the differential pressure between the pressure in the gaseous medium and the pressure in the liquid medium, for the absolute pressure or the temperature in the gaseous medium the ground pressure is kept constant regardless of the level, wherein the target ground pressure for a particular tank assembly and a specific gas, for example, manufacturer specified. The regulation of the desired ground pressure is carried out according to the following formulas: $${\text{e}}_{\text{pB}}={\underset{\_}{\text{p}}}_{\text{B SHOULD}}-{\text{p}}_{\text{B IS}}$$

$${\text{y}}_{\text{pB}}=\text{f}\left({\text{e}}_{\text{pB}}.{\dot{\text{e}}}_{\text{pB}}.{\displaystyle \int {\text{e}}_{\text{pB}}\text{dt}}\right)$$

in which e _pB the control difference for ground pressure, p _{B SHOULD} the desired ground pressure, p _{B IS} the actual ground pressure and Y _pB the control signal at the output of the bottom pressure controller, ě _pB the time derivative of the control difference and ∫e _pB dt the integral of the control difference after the time means.

$${\text{p}}_{\text{B}}=\text{const}$$

Because in such a scheme, the gas pressure in the upper tank area 22 via the gas pressure control valve 34 is regulated, the ground pressure can p _B be kept constant over a variable gas pressure by the gas pressure on the ground pressure p _B minus the actual differential pressure Δp is controlled. The gas pressure setpoint is calculated from the specification of the operator for the ground pressure p _B and from the differential pressure Δp measured at the differential pressure measuring device according to the following formulas: $${\text{p}}_{\text{gas}}={\text{p}}_{\text{B}}-\Delta \text{p}$$

$${\text{p}}_{\text{B}}=\text{const}$$

2 shows a modified embodiment of the tank assembly according to the invention 2 from 1 , wherein like reference numerals are used for corresponding parts. In particular, the bottom pressure regulator 32 to regulate the ground pressure, the gas pressure control by the gas pressure control valve 34 , the temperature sensor 46 and the flow control circuit are in 2 analogous to the corresponding units in 1 educated.

$${\text{y}}_{\text{Qein}}=\text{f}\left({\text{e}}_{\text{Qein}}{\text{, }\dot{\text{e}}}_{\text{Qein}}\text{, }{\displaystyle \int {\text{e}}_{\text{Qein}}\text{ dt}}\right)$$

wbei e_Qein die Regeldifferenz für die Durchflussgeschwindigkeit in der Zuflussleitung, Q _{EIN SOLL} die Soll-Durchflussgeschwindigkeit in der Zuflussleitung, Q _{EIN IST} die Ist- Durchflussgeschwindigkeit in der Zuflussleitung, Y_QAUS die Regelgröße für die Durchflussgeschwindigkeit in der Zuflussleitung, , ė_QEIN die zeitliche Ableitung der Regeldifferenz und ∫e_QEIN dt das Integral von der Regeldifferenz nach der Zeit bedeutet.The control unit 14B includes a flow regulator 50 , which as input the output signal of the flow measuring device 52 receives and a flow control signal for the controlled variable Y _0ein via a control algorithm for the flow Q is _a which outputs a flow control valve 54 controls, with which the flow in the outlet pipe 10 according to the controlled variable Y _0ein is controlled. The flow control valve 54 lies in the inflow line 10 of the tank 6 upstream of the flowmeter 52 and regulates the flow through a control signal for the controlled variable Y _0ein that of the flow regulator 50 to the flow control valve 54 is delivered. The controlled variable Y _0ein is determined as follows: $${\text{e}}_{\text{Qin}}={\text{Q}}_{\text{A TARGET}}-{\text{Q}}_{\text{ONE IS}}$$

$${\text{y}}_{\text{Qin}}=\text{f}\left({\text{e}}_{\text{Qin}}{\text{.}\dot{\text{e}}}_{\text{Qin}}\text{.}{\displaystyle \int {\text{e}}_{\text{Qin}}\text{dt}}\right)$$

wbei e _Qein the control difference for the flow rate in the inflow line, Q _{ONE SHOULD} the desired flow rate in the inflow line, Q _{IS ON} the actual flow rate in the inflow pipe, Y _QAUS the control variable for the flow velocity in the inflow pipe,, ė _{QEIN means} the time derivative of the control difference and ∫e _QEIN dt means the integral of the control difference after the time.

In contrast to 1 is in the tank arrangement of 2 the flow rate in the inflow pipe 10 regulated. This is in place of the absolute pressure measuring device 18 in 1 a temperature sensor 56 in 2 provided that the temperature of the gaseous portion of the medium in the upper tank area 22 detected. Since the gas pressure and the temperature are coupled via the boiling curve, the level in the tank can also be due to the knowledge of differential pressure and temperature 6 be calculated.

LIST OF REFERENCE NUMBERS

2

tank assembly

4

level

6

tank

8th

medium

10

inflow line

12

drain line

14A

control unit

14B

control unit

16

Differential pressure measuring device

18

Absolute pressure measuring device

20

connecting cable

22

upper tank area

24

connecting cable

26

connecting cable

28

lower tank area

30

Storage

32

Ground pressure regulator

34

Gas pressure control valve

36

branch line

38

Evaporator

40

Overflow valve

42

Flow Controllers

44

Flow measurement device

45

Flow control valve

46

temperature sensor

50

Flow Controllers

52

Flow measurement device

54

Flow control valve

56

temperature sensor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202014102808 U [0002]

Claims (11)

Tank arrangement for level control of cryogenic media comprising: a tank (6) with an inflow line (10) and a discharge line (12), a differential pressure measuring device (16) which is connected via a fluid line (26) to a lower tank region (28) in which the liquid portion of the medium is present, and also via a further fluid line (20) having an upper tank region (22 ) in which the gaseous portion of the medium is present, an absolute pressure measuring device (18) and / or a temperature sensor (18) for measuring the pressure and / or the temperature in the upper tank region (22), an evaporator (38) in a branch line (36) between the inflow line (10) and the upper tank area (22), a control unit (14A, 14B) which is suitable for pressure regulation, the evaporator (38) in the branch line (36) downstream gas pressure control valve (34) for controlling the pressure in the upper tank region (22) controls, and connected to the differential pressure measuring device (16) and the absolute pressure measuring device (18) and / or a temperature sensor (18) ground pressure regulator ( 32) for actuating the gas pressure control valve (34), wherein the bottom pressure regulator (32) is configured to increase the pressure in the gaseous portion of the medium in the tank (6) to a constant bottom pressure depending on the level of the liquid portion of the medium regulate. Tank arrangement after Claim 1 , characterized in that in the control unit (14B, 14B) a memory (30) is provided, in which a desired pressure in the gaseous portion of the cryogenic medium in the tank (6) depending on the level of the liquid portion of the cryogenic medium is stored. Tank arrangement after Claim 2 characterized in that in the memory (30) in the control unit (14B, 14B) the desired pressure in the gaseous portion of the cryogenic medium in the tank is stored as a function or table depending on the liquid level of the cryogenic medium. Tank arrangement after Claim 2 or 3 characterized in that a temperature sensor (46) is used in the branch line (36) in the region of the gas pressure control valve (34) for regulating the flow rate, such that an evaporator (38) disposed in the branch line (36) in the It is able to vaporize the amount of gas passed by the gas pressure control valve (34). Tank arrangement according to one of the Claims 1 to 4 characterized in that a flow meter (52) is provided in the inflow conduit (10) and in the control unit (14B, 14B) a flow regulator (50) configured to control the inflow of the cryogenic fluid through an inflow control valve (10). 54) in the inflow line (10). Tank arrangement according to one of the Claims 1 to 3 characterized in that a flow meter (44) is provided in the drain line (12) and in the control unit (14B, 14B) comprises a flow regulator (42) configured to control the flow of cryogenic fluid through a drain control valve (14). 45) in the drain line (12). A method for level control of cryogenic media in a tank comprising: measuring a differential pressure by a differential pressure measuring device (16) which is connected via a connecting line (26) to the lower tank region (28) and also via a further connecting line (20) with the upper tank area (22), measuring an absolute pressure by an absolute pressure measuring device (18) and / or a temperature sensor (56) in the upper tank area (22) in the gaseous portion of the cryogenic medium, and controlling the pressure in the gaseous portion of the cryogenic medium Medium in the tank (6) by a gas pressure control valve (34), characterized in that the pressure in the gaseous portion of the cryogenic medium by the gas pressure control valve (34) in a branch line (36) between an inflow line (10) and the upper tank area (22) is controlled, and the driving of the gas pressure control valve (34) by a connected to the differential pressure measuring device (16) Bod Enddruckregler (32), wherein the bottom pressure regulator (32) regulates the pressure in the gaseous portion of the cryogenic medium in the tank (6) depending on the level of the liquid portion of the cryogenic medium to a constant ground pressure. Method according to Claim 7 , characterized in that in the bottom pressure regulator (32) a target pressure in the gaseous portion of the cryogenic medium in the tank (6) is stored depending on the level of the liquid portion of the cryogenic medium. Method according to Claim 7 or 8th , characterized in that in the memory (30) in the ground pressure regulator (32) the target pressure in the gaseous portion of the cryogenic medium in the tank (6) is stored as a function or table depending on the level of the liquid portion of the cryogenic medium , Method according to Claim 4 , characterized in that an inflow of the cryogenic liquid to the tank (6) is controlled taking into account a control signal from the ground pressure regulator (32) and an inflow controller (54). Method according to one of Claims 7 to 9 , characterized in that an outflow of the cryogenic liquid from the tank (6) is controlled taking into account a control signal of the ground pressure regulator (32) and a discharge regulator (42).

Images