DE102020206554B3 - Process for operating two vacuum degassers connected in parallel with fluid technology and use of the process - Google Patents

Abstract

The present invention relates to a method for degassing a fluid circuit, the fluid circuit having a first vacuum degasser 10, the first vacuum degasser 10 having a first inlet valve 12, a first degassing chamber 14, a first outlet valve and a first pump 16, the first pump 16 of the first vacuum degasser 10 is operated continuously so that the first pump continuously conveys fluid from the first degassing chamber back into the fluid circuit, the first vacuum degasser 10 being operated in two cycle steps, with the first inlet valve 12 being opened for a first time 110 in a first cycle step is, wherein in a second cycle step the first inlet valve 12 is closed for a second time 120, the duration of the cycle of the first vacuum degasser 10 being formed from the sum of the first time 110 and the second time 120, characterized in that the fluid circuit has a second vacuum degasser 20 aufwe The second vacuum degasser 20 has a second inlet valve 22, a second degassing chamber 24, a second outlet valve and a second pump 26, the second vacuum degasser 20 being operated in two cycle steps, with the second in a first cycle step for a third time 130 Inlet valve 22 is open, the second inlet valve 22 being closed for a fourth time 140 in a second cycle step, the duration of the cycle of the second vacuum degasser 20 being formed from the sum of the third time 130 and the fourth time 140, at least in individual cases Cycles, the first time 110 is replaced by a modified first time 112 or the third time 130 by a modified third time, so that simultaneous parallel running of the cycles of the first vacuum degasser (10) and the second vacuum degasser (20) is avoided.

Description

Process for operating two vacuum degassers connected in parallel with fluid technology and use of the process

The invention relates to a method for operating two vacuum degassers connected in parallel for fluid technology and to the use of the method.

In applications where redundancy is very important, the use of two vacuum degassers connected in parallel can be important. An example here is the degassing of the cooling water of a fuel cell on board a military submarine. In order to further reduce the independence of these systems and thus the total failure, it can be expedient to output the two vacuum degassers connected in parallel in slightly different ways, for example to use different pumps. The idea behind this is that a problem which causes one type of pump to fail may not have any effect on the other type of pump and so at least 50% of the capacity is still available.

However, if two vacuum degassers are run in parallel, there are two different extremes. If both run in parallel in the cycle at the same time, the effect on the fluid circuit, for example the cooling circuit, is maximum, and pressure minima and pressure maxima add up. If both vacuum degassers run offset by half the cycle time, the effect is minimized, the pressure maxima and pressure minima in the overall system are minimized.

However, two vacuum degassers never always run completely synchronously. Even structurally identical, differences can occur, which of course turn out to be even greater if different components are used. Different aging or deposits can also mean that the cycle times may differ, if only slightly. It can therefore always happen that at a certain point in time both vacuum degassers run synchronously and the system must therefore be designed for the maximum pressure loads, for example by means of a correspondingly large pressure compensation tank.

However, especially in the area of application in a submarine, space and weight are critical, so that it would be desirable to minimize such fluctuations in order to save space and weight. In addition, by reducing the fluctuations, noise can also be minimized by reducing the pressure pulses, which reduces the acoustic signature. Similar considerations apply to all mobile applications, for example in the automotive sector, in the aerospace industry.

From the postpublished DE 10 2020 202 024 A1 a vacuum degasser is known.

From the JP 2002/239 303 A a device for degassing liquid is known.

From the DE 10 2011 083 988 A1 a cooling device for a fuel cell system of a submarine is known.

The object of the invention is to increase the redundancy by connecting two vacuum degassers in parallel and to provide a method for operating the two vacuum degassers.

This object is achieved by the method with the features specified in claim 1 and by using the method with the features specified in claim 8. Advantageous further developments result from the subclaims, the following description and the drawings.

The inventive method is used for degassing a fluid circuit. For example, the fluid circuit is a cooling circuit. The fluid circuit has a first vacuum degasser, the first vacuum degasser having a first inlet valve, a first degassing chamber, a first outlet valve and a first pump. The vacuum degasser can also have a more complex structure, for example as shown in FIG DE 10 2020 202 024 A1 known. The first pump of the first vacuum degasser is operated continuously. The first pump thus continuously conveys fluid from the first degassing chamber back into the fluid circuit. The first vacuum degasser is operated in two cycle steps: in a first cycle step the first inlet valve is open for a first time, in a second cycle step the first inlet valve is closed for a second time. During the first cycle step, fluid thus flows from the fluid circuit through the first inlet valve into the first degassing chamber and is at the same time conveyed back into the fluid circuit by the first pump from the first degassing chamber. No fluid can flow in during the second cycle step because the first inlet valve is closed. However, the first pump continues to deliver fluid from the first degassing chamber and thus generates a negative pressure in the first degassing chamber at the end of the second cycle step, so that fluid which then flows into the negative pressure of the first degassing chamber in the next first cycle step is degassed. The duration of the cycle of the first vacuum degasser is calculated from the sum of the first time and the second time, because the cycle consists of these two cycle steps.

According to the invention, the fluid circuit has a second vacuum degasser. The second vacuum degasser has a second inlet valve, a second degassing chamber, a second outlet valve and a second pump. Just like the first vacuum degasser, the second vacuum degasser is operated in two cycle steps. In the first cycle step, the second inlet valve is open for a third time, while in the second cycle step the second inlet valve is closed for a fourth time. The basic process is the same. For example, however, the second pump can be of a different type than the first pump in order to make the simultaneous failure of both pumps less likely. The duration of the cycle of the second vacuum degasser is thus formed from the sum of the third time and the fourth time.

According to the invention, the first time is replaced by a modified first time or the third time is replaced by a modified third time at least in individual cycles. This makes it possible to change the phase position of the first vacuum degasser relative to the second vacuum degasser

Another great advantage is that the two vacuum degassers can be switched on practically at any time interval. After only a few cycles, the method according to the invention ensures that these two have an optimal phase relationship with one another.

The first outlet valve is necessary in order to be able to remove the gas that has escaped from the fluid in the first degassing chamber from the fluid circuit. The second outlet valve is also necessary in order to be able to remove the gas that has escaped from the fluid in the second degassing chamber from the fluid circuit. Possible ways of working within the cycle steps can, for example, be the DE 10 2020 202 024 can be removed.

A control unit which controls the first inlet valve and the second inlet valve is particularly preferably used to carry out the method. In one embodiment, the first time, the second time, the third time and the fourth time are stored in the control unit. This control device also preferably has a clock. The control unit can further be connected, for example, to a first pressure measuring device, which is connected to the first degassing chamber, and a second pressure measuring device, which is connected to the second degassing chamber. A modified first time and / or a modified third time can be stored in the control unit. Alternatively, a rule for generating a modified first time and / or a modified third time can be stored in the control unit. In a further embodiment, the first pump and the second pump for the control unit can also be regulated. Thus, in this embodiment, the first vacuum degasser and the second vacuum degasser can not only be regulated via the control unit, but can also be switched on and off via the control unit.

In an alternative embodiment, the second and fourth times are stored in the control unit. A modified first time and a modified third time are also stored in the control unit. This control device also preferably has a clock. The control unit is connected to a first pressure measuring device, which is connected to the first degassing chamber, and a second pressure measuring device, which is connected to the second degassing chamber. A first limit value for the pressure that must be exceeded in the respective degassing space during the first and third time is also stored in the control unit. A second limit value for the pressure which must be fallen below in the respective degassing space during the second and fourth time can also be stored. A temperature sensor can also be attached to the degassing space so that the first limit value or the second limit value can also be stored as a function of temperature.

The control unit opens the first inlet valve at a first point in time and the second inlet valve at a second point in time and keeps it open until the first limit value for the pressure is exceeded. At the same time, the control unit measures the duration of the filling process and saves this time as the first or third time. After the first pressure is exceeded, the control unit closes the first inlet valve for the duration of the second time and the second inlet valve for the duration of the fourth time.

The control unit in this alternative embodiment is set up to use the clock to measure the first time and the third time which the degassing spaces need to reach a certain pressure. Alternatively, the control unit is set up to also determine the second time and fourth time or the entire cycle duration of the respective vacuum degassers. From the measured times, the control unit determines the transit time difference of the respective throughput times and / or the time offset of the respective switching points. The control unit is also set up to replace the first and third time with the modified first time or the modified third time when predetermined limit values for the transit time difference and / or the time offset are exceeded. The modified first time and the modified third time are selected in such a way that, after the time has elapsed, the predetermined limit values for the transit time difference and / or the time offset are again undershot. This means in particular that the first inlet valve or second inlet valve remains open for a further time after the specific pressure has been reached. The modified third time can therefore consist of the third time and an additional time interval Δt.

In a further embodiment of the invention, the first time is replaced by a modified first time if the duration of the cycle of the first vacuum degasser is shorter than the duration of the cycle of the second vacuum degasser, or the third time is replaced by a modified third time if the The duration of the cycle of the first vacuum degasser is greater than the duration of the cycle of the second vacuum degasser.

The faster cycle is thus modified, particularly preferably slowed down. For example, if the cycle of the first vacuum degasser were normally about 1 second faster than the cycle of the second vacuum degasser, the first time could be extended by 10 seconds every 10 cycles. This makes it possible to compensate for both small and large differences in a simple manner.

In a further embodiment of the invention, the modified first time is obtained by adding a time interval Δt to the first time, or the modified third time is obtained by adding a time interval Δt to the third time. The time interval Δt is preferably selected in the range from (sum of the first time, the second time, the third time and the fourth time) divided by 40 to (the sum of the first time, the second time, the third time and the fourth time ) divided by 8. In other words, the time interval is in the range from 25% of the averaged cycle time to 5% of the averaged cycle time. If one were to assume an average cycle time of 5 minutes, the result would be a range from 10/8 minutes = 75 seconds to 10/40 minutes = 15 seconds. The first time, if the first vacuum degasser is faster, or the third time, if the second vacuum degasser is faster, would accordingly be lengthened by this interval.

For example, in this embodiment, the first time, the second time, the third time and the fourth time and also the time interval Δt are stored in the control unit.

In a further embodiment of the invention, a fixed cycle point is defined which is used jointly for both vacuum degassers. The time difference between the fixed cycle point of the first vacuum degasser and the fixed cycle point of the second vacuum degasser is measured. As a result, the phase relationship between the first vacuum degasser and the second vacuum degasser can be easily detected. Opening or closing the inlet valve is particularly suitable as a fixed cycle point. With a perfect phase shift, the time difference would ideally correspond to half the averaged cycle duration. If the deviation from this is greater than Δt / 2, for example, then the first time or the third time can be modified in the next cycle. It is also possible to calculate the exact difference between the measured time difference and half the averaged cycle duration and to use this value for Δt and thus to modify the first time or the third time in the next cycle. Due to the much simpler control, however, a constant choice of Δt is often easier, even if the dynamic method enables operation closer to the optimum.

The time difference can be recorded in a comparatively simple manner in a control unit. In particular with a clock integrated in the control unit, the time difference between the opening of the first inlet valve and the opening of the second inlet valve, for example, or the time difference between the closing of the first inlet valve and the closing of the second inlet valve, for example, can easily be measured .

In a further embodiment of the invention, the first time is replaced by a modified first time or the third time is replaced by a modified third time, provided that the measured time difference is the sum of the first time, the second time, the third time and the fourth time) divided by 4 by more than the time interval Δt deviates.

In a further embodiment of the invention, a first vacuum degasser with a first flow rate regulating device fluidly arranged upstream of the first degassing chamber and / or a second vacuum degasser with a second flow rate regulating device fluidically arranged upstream of the second degassing chamber is selected. For example, a flow control device can only be inserted in front of the faster vacuum degasser. It is also possible to arrange a flow rate control device in front of both vacuum degassers during manufacture and, if necessary, in ignorance of which one will be faster. A flow rate regulating device in the sense of the invention is any device which can change the fluid flow in a targeted manner in terms of quantity. For example, it is a throttle valve or a diaphragm. But it can also be a simple 2-way stopcock where The flow rate can be regulated at least roughly via the angle. An absolutely precise regulation of the flow rate is possible, but not necessarily expedient. The relationship between the vacuum degassers can change due to time or temperature fluctuations. In order to compensate for this, the first time or the third time is modified according to the invention. The flow rate regulating device only serves to roughly set the first vacuum degasser and the second vacuum degasser to a similar cycle duration. By means of the first flow rate regulating device, the flow through the first vacuum degasser and thus the first time is changed and / or by means of the second flow rate regulating device, the flow through the second vacuum degasser and thus the third time is changed, so that the sum of the first time and the second time with a tolerance of ± 15% is equal to the sum of the third time and the fourth time.

Theoretically, instead of the modified first time and the modified third time, one could leave the first time and the third time unmodified and instead use a modified second time and a modified fourth time analogously. In this alternative variant, however, fluid would be pumped out of the degassing space for a longer period of time, which in the extreme case could lead to gas entering the pump, which in turn would be disadvantageous. It could therefore be provided that in this variant a fill level sensor is provided for a minimum fill level in the degassing spaces. But this is a little more complex. Therefore, this alternative is not preferred.

In a further embodiment of the invention, a first pressure is measured in the first degassing space and a second pressure is measured in the second degassing space. The time difference between the pressure maximum in the first degassing chamber and the pressure maximum in the second degassing chamber is measured If the deviation is greater than Δt / 2, for example, the first time or the third time can be modified in the next cycle.

In a further aspect, the invention relates to a method for operating a submarine with a fluid circuit, the method for degassing a fluid circuit being carried out according to one of the preceding claims. The submarine is particularly preferably a military submarine with a fuel cell device, in which failure safety is therefore a high priority.

The method can be adapted accordingly to three, four or more vacuum degassers connected in parallel, the time difference between the individual vacuum degassers then being set to the cycle time divided by the number of degassers.

• 1 Fluidkreislauf mit zwei Vakuumentgasern
• 2 Zeitachse ohne Modifikation
• 3 Zeitachse mit Modifikation

The method according to the invention is explained in more detail below using an exemplary embodiment shown in the drawings.

• 1 Fluid circuit with two vacuum degassers
• 2 Timeline without modification
• 3 Timeline with modification

In 1 is a fluid circuit with two vacuum degassers 10 , 20th shown. In the example shown, the fluid circuit serves as a coolant circuit for a fuel cell device 40 , in which a coolant pump 50 the coolant through a heat exchanger 70 transported. A pressure equalization tank is attached to the circuit 30th connected in order to be able to compensate for changes in volume due to changes in the temperature of the coolant, for example. The arrows shown serve to illustrate the coolant flow and the coolant flow direction. Here, the coolant flow divides upstream of the fuel cell device 40 , for example and preferably 80% to 95% of the coolant flows over the fuel cell device 40 . Only 5% to 20% of the coolant flows through the first vacuum degasser 10 or the second vacuum degasser 20th . Theoretically, the coolant circuit can, at least for a short time, also without the two vacuum degassers 10 , 20th operated, for example to reduce the acoustic signature temporarily by switching it off.

Fluid technology parallel to the fuel cell device 40 are the first vacuum degasser 10 and the second vacuum degasser 20th switched. The first vacuum degasser 10 has a first inlet valve 12th , a first degassing space 14th and a first pump 16 on. The second vacuum degasser 20th has a second inlet valve 22nd , a second degassing room 24 and a second pump 26th on. Via a control unit 60 become the first inlet valve 12th and the second intake valve 22nd controlled according to the method of the invention. This is based on the time courses in the 2 and 3 shown.

2 first shows the course of the first time 110 , the second time 120 , the third time 130 and the fourth time 140 . The upper graph is intended to show the state of the first intake valve 12th demonstrate. If the graph is high, the first intake valve is 12th open, the graph below is the first inlet valve 12th closed. The lower graph is intended to show the state of the second intake valve 22nd demonstrate. If the graph is high, the second inlet valve is open, if the graph is down, the second inlet valve is open 22nd closed.

In the example shown, the first time is 110 35 s, the second time 120 35 s, the third time 40 S and the fourth time 40 s. Here, for the sake of simplicity, are the first time 110 and the second time 120 as well as the third time 130 and the fourth time140 was chosen to be of the same length, which only serves to simplify and improve clarity. In reality, all four times will be different from each other.

At the beginning of the time, the first vacuum degasser is running on the far left 10 and the second vacuum degasser 20th perfectly counter-rotating, the pressure fluctuations in the fluid circuit are minimal. Due to the difference in the cycle duration of 10 s, the cycles are shifted relative to one another, so that after a certain time they would run in parallel and thus the pressure fluctuations would be maximal. To prevent this, the first time is used in some cycles in the example shown 110 modified at a modified first time 112 because the cycle time of the first vacuum degasser 10 is shorter than the cycle time of the second vacuum degasser 20th . This is in 3 shown. For this purpose, a time interval Δt of 20 s is added so that a modified first time occurs 120 of 55 s results.

List of reference symbols

10

first vacuum degasser

12th

first inlet valve

14th

first degassing room

16

first pump

20th

second vacuum degasser

22nd

second inlet valve

24

second degassing room

26th

second pump

30th

Pressure expansion tank

40

Fuel cell device

50

Coolant pump

60

Control unit

70

Heat exchanger

110

first time

112

modified first time

120

second time

130

third time

140

fourth time

Claims (8)

A method for degassing a fluid circuit, the fluid circuit having a first vacuum degasser (10), the first vacuum degasser (10) having a first inlet valve (12), a first degassing chamber (14), a first outlet valve and a first pump (16), wherein the first pump (16) of the first vacuum degasser (10) is operated continuously so that the first pump continuously conveys fluid from the first degassing chamber back into the fluid circuit, the first vacuum degasser (10) being operated in two cycle steps, with a first Cycle step for a first time (110) the first inlet valve (12) is open, wherein in a second cycle step for a second time (120) the first inlet valve (12) is closed, the duration of the cycle of the first vacuum degasser (10) off the sum of the first time (110) and the second time (120) is formed, characterized in that the fluid circuit has a second vacuum degasser (20), w whether the second vacuum degasser (20) has a second inlet valve (22), a second degassing chamber (24), a second outlet valve and a second pump (26), the second vacuum degasser (20) being operated in two cycle steps, with a first Cycle step for a third time (130) the second inlet valve (22) is open, wherein in a second cycle step for a fourth time (140) the second inlet valve (22) is closed, the duration of the cycle of the second vacuum degasser (20) off the sum of the third time (130) and the fourth time (140) is formed, the first time (110) being replaced by a modified first time (112) or the third time (130) by a modified third time at least in individual cycles so that a simultaneous parallel running of the cycles of the first vacuum degasser (10) and the second vacuum degasser (20) is avoided. Procedure according to Claim 1 , characterized in that the first time (110) is replaced by a modified first time (112) if the duration of the cycle of the first vacuum degasser (10) is less than the duration of the cycle of the second vacuum degasser (20), or the third time (130) is replaced by a modified third time, provided that the duration of the cycle of the first vacuum degasser (10) is greater than the duration of the cycle of the second vacuum degasser (20). Method according to one of the preceding claims, characterized in that the modified first time (112) is obtained by adding a time interval Δt to the first time (110) or the modified third time (130) is obtained by adding a time interval Δt to the third time will. Procedure according to Claim 3 , characterized in that the time interval Δt is selected in the range of (sum of the first time (110), the second time (120), the third time (130) and the fourth time (140)) divided by 40 to (sum of the first time (110), the second time (120), the third time (130) and the fourth time (140)) divided by 8. Method according to one of the preceding claims, characterized in that a fixed cycle point is defined, the time difference being measured which lies between the fixed cycle point of the first vacuum degasser (10) and the fixed cycle point of the second vacuum degasser (20). Method according to a combination of Claim 4 and Claim 5 , characterized in that the first time (110) is replaced by a modified first time (112) or the third time (130) is replaced by a modified third time, provided that the measured time difference differs from the value of the sum of the first time (110), the second time (120), third time (130) and fourth time (140) divided by 4 by more than the time interval Δt deviates. Method according to one of the preceding claims, characterized in that a first vacuum degasser (10) with a first flow rate regulating device fluidly arranged in front of the first degassing chamber (14) and / or a second vacuum degasser (20) with a fluidically arranged in front of the second degassing chamber (24) second flow rate control device is selected, the first time (110) is changed by means of the first flow rate control device and / or the third time (130) is changed by means of the second flow rate control device, so that the sum of the first time (110) and the second time (120 ) is equal to the sum of the third time (130) and the fourth time (140) with a tolerance of ± 15%. Use of the method according to one of the preceding claims in a submarine with a fluid circuit.

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