DE1100060B - Pressure boosting device for storage tanks for liquefied gases - Google Patents

Description

The invention "relates to a pressure increasing device for storage tanks of liquefied gases, in which the liquefied gases are pumped by the storage tank to be pumped to the consumer. In particular, it relates to an automatic one Pressure control, which is suitable for delivery and storage containers of liquefied gases with relatively low Boiling point, e.g. B. liquid oxygen is suitable.

When a liquefied gas is withdrawn from a storage container via a pump, it occurs Pressure loss in the inlet line and in the pump inlet. This is a consequence of the friction · and the increase in speed of the medium. Such a pressure drop also occurs when the pump is in immersing the liquid and removing the inlet conduit. Furthermore, the liquid is inside the pump as a result of its turbulence and as a result of the friction of the moving pump parts and through the heating of the pump drive heat is supplied. Such a supply of heat causes evaporation some of the liquid before it exits the pump.

If there is evaporation in front of or in the pump, this means that the pump only has one Partial filling absorbs or the filling is even prevented. Even a small amount of evaporation works adversely affect the performance of the pump. In centrifugal pumps, the evaporation causes the formation of bubbles In the rotor, with piston pumps, strong shocks occur, which in both cases leads to premature wear the pumps as well as the drives. Furthermore, the pump output and the pump efficiency deteriorates.

Attempts have already been made to remove the liquid from a storage container through the above Liquid to cause standing gas pressure alone. With this method, which dispenses with a pump, however, there are greater difficulties to overcome than using a pump. In particular a high gas pressure is required. Other disadvantages arise from the lower overflow speed and determining the amount of liquefied gases to be transferred. In many cases transmission by pumps therefore offers advantages.

Usually one tries to solve the difficulties that arise with a liquid withdrawal with the help of a Adjust the pump by overcoming the fact that the liquid initially compares to its pressure is hypothermic. If you choose the way to subcool the liquid by extracting heat, it is necessary a colder medium to dissipate the excess heat. An expensive heat exchange device is also required.

Pressure increasing device
for storage tanks for liquefied gases

Applicant:

Union Carbide Corporation,
New York, NY (V. St. A.)

Representative: Dipl.-Ing. H. Görtz, patent attorney,
Frankfurt / M., Schneckenhofstr. 27

Claimed priority:
V. St. v. America December 2, 1955

Jesse Brand Starnes, Snyder, NY (V. St. A.),
has been named as the inventor

It is therefore more convenient to keep the pressure above the liquid Increase gas to prevent boiling and suppress premature evaporation. Efforts are therefore made to quickly increase the gas pressure immediately before pumping. Man achieves the same effect as with supercooling, because the pressure-temperature relationships of the liquefied gas are kept so that the liquid at the then prevailing pressure under her Boiling point remains. The handling and transport of the liquid thus winds with a certain degree unavoidable pressure drop possible, but there is no sudden or excessive evaporation the liquid.

Solving the problem in this way depends on a number of different factors. from The heat losses and the pressure drop in the pipes that occur during the closing are significant the resulting turbulence and the efficiency of the pump. The solution to the problem is thus essentially a rule problem.

Devices are known for influencing the transmission process by hand controls in such a way that that the desired 'best performance is achieved. In particular, methods are known which regulate the pressure increase in the storage tank during the pumping process. The disadvantage of this procedure lies in the fact that the quality of the liquid withdrawal, d. H. the most loss-free transmission possible depends on the skill of the operator.

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Lately, therefore, attempts have been made to be partly pending. One at low temperature close Control devices for regulating the withdrawal of their boiling point of stored liquid increases allof low-boiling liquefied gases from a gradually increasing their pressure as a result of inevitable heat storage containers to automate via a pump. Losses except when steam is withdrawn. Of the In these known control devices there is 5 accumulator pressure is usually below the upper one however, problems still exist, especially when operating limit held by periodically withdrawing steam with a pump that does not require maintenance and which is either blown into the atmosphere the setting of the pressure in the storage tank a gas storage released or connected during pumping times. Consumption devices must also always be supplied. If the another switch to the pressure state in the io liquid is stored at or above the pressure, Container for the time in which no pump transmission is consumed, the steam can be in takes place. Since the liquefied gases are normally delivered through a supply line. That's why close to or even at their boiling point! is stored in the gas space of the storage container with a the, must be tried to unnecessary pressure increase in connection, which is from an electro-magnetic to avoid during the storage period. Des- 15 table operated valve is controlled, its working half It required great skill the coil is connected to a power circuit, wel-operators, around the storage container to rather the normally closed electric and monitor a transmission process without a switch of a pressure switch that is set to the largest Steam formation and to be carried out without losses. Before accumulator pressure responds, and that normally everything must include the pre-cooling of the pump and the "lower open relay" which responds to the initiation of the pump cooling " the liquid in the storage tank responds carefully.

If the liquid is stored at low pressure, this can be done by hand.

pump operation with all its disadvantages is ensured, it may be necessary to reduce the excess

Constant readjustment within tolerable limits to compress sigen steam before its use.

keep. Special attention must be paid to the 25 In this case, the compressor can

Pressure increase in the storage tank, some automatic, responsive to the tank pressure

since too high a pressure rise an escape of the table control devices are provided.

Medium through the safety valves to If the liquid is also under-

Consequence. is cooled, the storage pressure must be above the

These disadvantages are avoided by increasing the upper range limit and for the new one

when closing a switch, the pumping pressure range must have new upper and lower limits

initiates a device for increasing the pressure to prevent premature evaporation of the

to be avoided in the storage tank through the entry of pressurized liquid. The lower limit will be

the gas is switched on automatically. determined by the lowest subcooling pressure.

This creates a device that winds in the same way under the At the moment of the withdrawal, it is completely automatic and kept at the upper limit, as with regard to the reliable has been described for one in the stipulated area, exiting the lower area. The for Reaching pressure increase ensures to completely independent the storage container described control device from the attention and dexterity of one for the upper limit will be in addition to the usual Operator the disadvantages of a steam generation 40 overpressure safety devices provided. One to be eliminated during pumping. Such a device is provided that the

There are fewer entertainment and loading storage containers with a second pressure switch in

operating costs and greater simplicity and reliability of connection, the normally open contacts

nonchalance of the whole area. The new device has, on the. electrical switch of the first

also has the effect that immediately after the pump pre- 45 pressure switch and the switch of the relay are located,

the accumulator pressure increases to the normal value - whereby the second pressure switch is designed in such a way that

declines, so that neither an increased accumulator pressure that its contacts at a certain low

the safety valves still open at high pressures close the accumulator pressure.

unavoidable heat losses occur. This double pressure area control, which has a normal

Advantageously, the gas space of the memory 50 includes pressure range control that occurs during container with a pressure switch in connection, the standby time takes effect to 'the control depending on the closing of a switch, the pressure within a relatively low by the pumping process is initiated to keep a Ven- gen pressure range effective, includes toil actuated, the access of the 'pressure-forming gas equal to the control of the storage pressure between causes in the storage tank. This makes the 55 of the upper and lower limits of one in proportion pressure-forming means for a pressure increase 'higher upper pressure range. The double pressure of pumping, only then with the Reichssteuerung is with the control for the Flüs-Innenrautn of the storage tank, connected when connected between fluid pump and takes effect when a pumping period is introduced into the pressure-forming means and the memory. Then the Pressure difference is present. This means that normal pressure range control of the container is not accessible via this 60 in the opposite case, a pressure loss takes effect and the pump range control is turned off Avoided container out. switched. Likewise, the double pressure area speaks -

The storage of liquefied gases requires that the control "wain" the pumping period has ended on the

the tank pressure changes to the condition of the pump control after an upper limit, but

as is also determined according to a lower limit. 65 means that the Punipenbereichs-

The lower limit is set by the control to be connected and sets the normal pressure range control.

ßende consumer system determines in which the process is going again. When the pump range control

liquefied gas is to be introduced. This control is activated, the pressure above the liquid

The user system can therefore automatically switch from the maintenance in the container to a higher one

the storage pressure is increased within certain limits, which is sufficient to cover a possible

5 6

Evaporation in the line to the pump or in the A further embodiment relates to the electrical

To prevent pump itself. In this way the control system of the device achieves. Particularly beneficial

one has an effect equivalent to undercooling, is that in the shunt to the electromagnetic

and in a reliable manner, without a table-actuated valve being a valve which is

Monitoring or manual operation required 5 tem tank pressure closes,

is. The drawing represents an embodiment of the

The invention is particularly suitable for "cold" subject matter of the invention. It shows

Pumps that are incorporated into the stored liquid Fig. 1 is a schematic representation of the pressure

be thawed or well insulated outside of the elevation device,

same are located. In this modification, one in FIG. 2 becomes a schematic representation of another

Hypothermia similar effect by using embodiment with the automatically controlled

achieved by a pressure-increasing evaporation coil. Double area pressure increasing circuit,

A single area as well as a double Fig. 3 can be a schematic representation of a further

area control are provided. In any case, an embodiment with the automatic double

the tank pressure is reached to the desired level - high pressure gas control,

is brought about by drawing off part of the liquid from the container, evaporating the object of the invention in an evaporation coil with a vapor phase and the vapor that forms into the vapor-controlled control for the double-range vapor phase of the container. For this purpose, a relief and the double area pressure increase and device in which the gas space of the storage container 20 Fig. 5 is a simplified electrical circuit diagram, such as ters over a pair of lines with a compressed gas is used in the arrangement shown in FIG.
The device according to the invention is suitable for having a pressure-dependent valve which, in one case for so-called "cold pumps", in which during the highest storage pressure closes, and in the other, the filling of the pump does not have any noticeable pressure. Line a second pressure-dependent valve that enters at 25 elevation. For this purpose, the special type that closes the highest pump pressure, as well as an elec- tric pressure increase is provided, which achieves an effect, tromagnetically actuated valve is arranged, which is equivalent to subcooling. This pressure work coil is connected to an excitation circuit, increase is softer in the known devices has a relay that responds to the initiation of the pumping process by means of an evaporation coil. 3 ° strives, which is separated from the main liquid part

Such a double-range pressure-increasing controlled amount of liquid evaporates and the steam

tion could for example be used to reintroduce the vapor phase of the container,

an overpressure area and a lower area A device in which no pressure increase except

for transferring liquid to another during pumping is required in Fig. 1

Device shown only on the basis of the pressure difference. From the storage tank 5 "is fluid

to provide. The high pressure gas is withdrawn from an external fluid and applied against a higher pressure

The source could be pumped by means of a cold pump P instead of the evaporation coil. The pump / ³

be turned. In each arrangement, for can in or in part of the storage container 6 "

For safety reasons, steam relief can be arranged comfortably, or it can be in a special

devices and / or pressure relief devices require 40 liquid containers, for example in the antechamber

Tigt, with these facilities at a higher mer 1, immerse. The antechamber 1 is on the

Pressure become effective as the pressure, which is controlled by the valve 3 line 2 with liquefied

supercooling-like effect in this device learn gas filled. A vent or pressure release

achieved. The same connection 4 is between the antechamber 1

According to a further modification, the new ⁴⁵ and the storage container 6 ¹ provided in order to remove an electromagnetically actuated valve from the steam device, to allow a free flow of liquid into the pre-chamber 1, which is switched on in an excitation circuit, and to allow a certain one Branch of the normally open contacts th liquid level in the antechamber 1 upright a pressure switch contains which on the pump to maintain. The connection 4 is responded to by a back pressure, and the other branch of the normal 5 ° impact valve S is controlled. Liquid is released from the sometimes closed contacts of a pressure switch pump P via line 6,
The pressure increase circuit has a line 2, speaks, the switching to the various branches with the lower part of the storage tank ο * ver being effected by a relay that is tied to the and responds via a branch line 7 in a ver-initiating the pumping process. 55 steam coil 8 leads. An electromagnetically

Such a device is advantageous when it regulates actuated valve 9 in branch line 7 which is desired to reduce the storage pressure between the pumping liquid flow to the evaporation coil 8 and the pumping train container-S * passed through the line 10. To remove the dissipated heat. By eliminating the ⁶ ° til 9, the pressure clearance side of the evaporation pipe 8 can be attached on the inlet side or on the outlet heat after pumping, between the liquid saturation point and the The valve 9 is automatically limited by a pressure switch 11 of the vapor relief safety - Automatically actuated, which responds to the container pressure always correctly for what is required and then comes into action when the pressure falls below a certain value to the extent of the pressure increase that for one of the storage containers 6 * falls below a certain value. Hypothermia similar effect is needed. This with the pressure switch 11 is an electrical switch again cooling the liquid in the storage container ter 11 α connected, which is via a further switch by steam extraction is particularly advantageous when 12 is in series with an electrical circuit 15 and the steam is drawn into a consumer line when it is closed, the work coil 9 α of the elekwird instead of venting it into the atmosphere. 70 solenoid operated valve 9 can respond.

7 8

The opening and closing of the switch 12 is controlled by a pressure-actuated valve 18, which is controlled by that of the pump / ³ via a relay 13. If the tank pressure is controlled, pump / ³ starts up in the branch line, the relay 13 responds, and 19 is arranged, and a tank pump pressure range normally open switch 12 with the pump at standstill control with a pressure-actuated valve 22, which is closed, which at the same time , the electromagnetic 5 is also controlled by the tank pressure, table-operated valve 9 under the control of the pressure in the branch line 20 is provided. Since the up switch 11 is brought. The pressure switch 11 is pressurized gas under a pressure which is significantly above the normal working pressure of the Speichenbehäl- working pressure of the container, but Sj is below the value of the setting of the valves 18 and 22 are preferably pressure reduction vapor relief device 14, which for safety io ornamental valves to allow the entry of high pressure gas into the grounds is set. The normal pressure low pressure gas system to prevent
Because of the high consumption and because of the frequent refilling of a normally closed electromagnetically a valve 9, which is actuated at low pressure, is low in the line 20 before the saturated liquid. Therefore, if the pressure valve · 22 for the control of the higher pressure helmet storage tank S is placed below the value of the lower! 5 range and is used, this control valve setting of the pressure switch 11 falls and the suction pump does not work except during the "subcooling times". so that the pressure drive to keep. Therefore, the valve 18 speaks for the switch 11 is closed, the pressure switch control of the lower pressure range on the Bell closes the electrical switch 11 α and thus excites the container pressure to let in high pressure gas when the work coil 9 a, which causes the electromagnetically to be ² ° this is necessary so that the container pressure opens via actuated valve 9 and an inflow of the fluids is maintained at a certain lower limit. If fluid in the evaporation coil 8 allows. The liquid saibKiugs - Puimpeii 'control circuit is excited When the tank pressure is again its upper value, the relay 13 causes a closing movement, the pressure switch 11 opens the electrical of the normally open switch 12 in the circuit switch 11 α and the electromagnetically actuated «5 of the work coil 9 α the solenoid operated valve 9 closes, whereby an excessive pressure valve 9, whereby the control of the accumulator pressure increase is avoided. The circuit 15 is connected to the valve 22, which, in accordance with the two power supply lines L ₁ and L ₂ . prevailing accumulator pressure is effective to a

In those cases in which stored liquid is stored in a certain higher minimum pressure in the container This can be maintained solely by an existing pressure difference of 3 °.

can be transferred, this can be shown in FIG. The pressure increase circuit is similar to that of the liquid during pressure increase shown in FIG. 1, except that to remove the heat applied to the pumps, liquid flow through the evaporation coil 8 35 uses a device according to FIG. Here, there is a regulating, electromagnetically operated valve 9 on which the vapor relief control is combined with the pressure increase outlet side of the evaporation base 8 in the line control. The steam relief 10 is located. In addition to the pressure switch 11, the device, which is shown as an electrically operated valve 25 which controls a pressure range in a vapor relief line 30 higher than the normal operating pressure, i.e. a 4 ° discharge during normal operation, is caused by a pressure difference A second troll of a pressure switch 26 is provided for the low-pressure pressure switch 16, which is set to a low range and below the constant pressure as the pressure switch 11 during the pumping times. Trolle a pressure switch 27 for the higher pressure-The contacts 16 α of the pressure switch 16 are parallel area. Both switches respond to the container to the pressure switch 11 in the circuit 15 in such a way arranged pressure and have upper and lower boundary network that they can make electrical settings via the work coil 9 α. in which they open the valve 25 actuate magnetically operated valve 9 when they are closed or closed. The pressure increase for the fume cupboard should be closed. Then it opens electromagnetically both by pressure difference alone and by actuated valve 9, liquid flows into the pump against a higher one; Pressure is brought about by a steam coil 8, and the pressure in the container 5 °. When the container is energized through lines 7 and 2 and to the pump circuit, the relay 13 closes the upper "part of the storage container 5 ¹ through the line switch 12, and the pressure switch 11 is connected to the higher 10. The line 10 has each A branch pressure range overrides the pressure switch 16 for lines 28 and 29, both of which lead to a line 31 in the lower pressure range, whereby a line 31 and the vapor relief subcooling has a corresponding effect. Line 30 have one, common Connecting line

The pressure increase for this effect can also 32 to the upper part of the storage tank> S. the

through the inlet of high pressure gas into the steam branch line 28 contains a pressure actuated valve 33,

space of the storage container 6 ^{1 can be} effected, as 6o .as responds to the container pressure and for the control

this is shown in FIG. 3. A source of under tion for the lower range pressure increase

The pressure is considerably higher than the pressure in the tank. The branch line 29 contains a pressure switch

The gas must be available for this. One achieves ter 34, which the valve 35 for the control of the

compared to the pressure coil system, this actuates certain higher pressure ranges. The vapor evacuation

Advantages in that a strong pressure increase 65 load circuit and the pressure increase control circuit

without extensive facilities. In regulation, are with the pump control circuit by means of

3 is connected to high pressure gas from a relay 36, not shown, which has an armature 37

th source of the storage tank 6 "is actuated by a line, which at the same time supplies the normally used

21, the parallel branch lines 19 and 20 closed switches 38 in the electrical circuit 40

having. A container normal pressure range control 7 ° opens, which is connected to the power supply lines L ₁

and L ₂ lies. Here, a normally open switch 39 closes in the pressure increasing circuit 41, which is also connected to the power supply lines L ₁ and L ₂ .

In another embodiment of the evaporation coil 8 and the line 7, a high pressure gas source can also be used can be used to pressurize the container via line 10. In this Case is a pressure reduction control in the branch line 29 instead of the pressure switch 34 for the High pressure area used. The pressure increase circuit 41 is then activated directly via the switch 39 connected to the solenoid-operated valve 35, and the valve 35 serves as a switching device for the branch line 29 of the higher pressure range.

The liquid is sent to the storage tank vS "with released at a pressure close to atmospheric pressure. With the pressure control of Fig. 4, the container pressure first brought to Druckaibzugshöhe, through the valve 33, which is at a below pressure lying at its lower limit setting opens and fluid from the lower part of the Can flow container into the evaporation coil 8. The steam passes through lines 10, 28, 31 and 32 in the upper part of the tank until the accumulator pressure reaches the value of the upper limit setting of the valve 33 is reached. At this pressure, the valve 33 closes. The pressure switch 26 for the Low pressure range is set to a lower limit which is usually higher than the upper limit Limiting adjustment of the valve 33 to the tank pressure to be kept in the range required for the extraction by means of a pressure difference.

When the liquid draw pump control circuit is energized, relay 36 opens switch 38 in the steam relief line 30 to make the pressure switch 26 ineffective and thereby the valve 25 under the control of the pressure switch 27 for the higher pressure range. At the same time it closes the relay 36 the switch 39 in the pressure increase circuit to open and close the valve 35 in 'to bring the branch line 29 under the control of the pressure switch 34. The pressure switch 27 for the higher pressure range wind set so that it the valve 25 at a setting above the upper Pressure increase limit setting opens. When the pumping period is over, relay 36 acts to the effect that the control of the valve 25 is again the pressure switch 26 for the low pressure range is assumed. As a result, the valve 25 remains open until the steam pressure in the container on the The value of the lower limit setting of the pressure switch 27 has fallen.

If it is not necessary to maintain a minimum pressure in the lower pressure range, i. H. if there is no pressure differential withdrawal, valve 33 and branch line 28 can be omitted will. The operation of the remaining parts is the same as described above. During the Standby time, the tank pressure is under the control of pressure switch 26 for the low pressure range, and no pressure increase is necessary. During a pumping process, as a result of the switchover the switches 38 and 39 the tank pressure under the common control of the pressure switch 27 for the higher pressure range and the pressure switch 34 brought.

An example circuit for a pressure increasing system such as that shown in FIG. 2 is shown schematically in FIG. 5 in order to explain the connection between the pressure increasing circuit and the pumping circuit. The pump motor PM is controlled by a starter 42, the contacts 43 of which are actuated magnetically by a coil 44. The circuit to the coil 44 is briefly closed by a start switch 45, and then a hold circuit is established via the auxiliary contacts 46 and a normally closed contact of a stop switch 47, which runs parallel to the start switch 45 in the pump control circuit

48 is located, which in turn is connected to the power supply lines L ₁ and L ₂ . The auxiliary contacts 46 are closed by energizing the coil 44. The start switch 45 can be operated manually or automatically, e.g. B. by a liquid level.

The normally closed stop switch 47 can be operated manually or automatically, to open the hold circuit to interrupt the pumping process. The pressure increase circle

49 has a coil 51 of an electromagnetically operated valve 50, which the current through the not illustrated evaporative coil regulates, further a pressure switch pair 52 and 53, which are in parallel in the Circle lie, and a switch 54 in series in the circuit of the pressure switch 53, operated by the relay 55 in the pump control circuit 48. The control, which has an effect similar to subcooling Achieved is so connected to the pump controls that the filling, pumping and pressure boosting ("Subcooling") is initiated and terminated by switches 45 and 47.

The controls according to the invention are in the same way with other than the described pressure increase methods applicable, e.g. B. the pressure increasing gas formed by evaporation of container liquid could be both in the container and, as described, can be generated without the same.

A snake that is heated electrically or otherwise, e.g. B. by passing through a warmer medium, could be immersed in the liquefied gas in the container or outside it are arranged and surround the liquefied gas in the container. How this evaporation coil works could be caused by a normally ineffective control, e.g. B. by a pressure switch, controlled, which responds to the tank pressure and connected to the liquid pump control is to be put into operation during the pumping period.

Claims (6)

Patent claims: 1. Pressure increasing device for storage tanks of liquefied gases, in which the liquefied Gases are pumped by a pump from the storage container to the consumer, characterized in that when closing a switch that initiates the pumping process, a device for increasing the pressure in the Storage tank is automatically switched on by the admission of pressure-generating gas. 2. Apparatus according to claim 1, characterized in that the gas space of the storage container (S) is in communication with a pressure switch (11) which, depending on the closing of a switch (12, 13), whereby the pumping process is initiated, a valve ( 9) actuated, which causes the pressure-generating gas to enter the storage container (S). 3. Apparatus according to claim 1 and 2, characterized in that the gas space of the storage 109 527/117 container (S) with a line (10) in connection, which is controlled by an electromagnetically operated valve (9), whose work coil (9 a) is connected to a line circuit, which the normally closed electrical switch (11 a) of a pressure switch (11), which responds to the greatest accumulator pressure, and contains the normally open relay (13), which responds to the initiation of the pumping process. 4. Apparatus according to claim 1 to 3, characterized in that the storage container (S) is in communication with a second pressure switch (16) which normally has open contacts (16 a) connected to the electrical switch (11 a) of the first Pressure switch (11) and the switch (12) of the relay (13) are located, the second pressure switch (16) being designed so that its contacts (16 a) close at a certain low storage pressure. 5. Apparatus according to claim 1 to 4, characterized in that the gas space of the storage container (S) is in communication with a pressurized gas source via a pair of lines (19, 20), the one line (19) being a pressure-dependent valve (18) which closes at a greatest storage pressure, and in the other line (20) a second pressure-dependent valve (22) which closes at a greatest pump pressure, and an electromagnetically operated valve (9) is arranged, the work coil (9 a) of which is connected to an excitation circuit is connected, which has a relay (12) which reacts to the initiation of the pumping process appeals to. 6. Apparatus according to claim 1 to 5, characterized by an electromagnetically actuated Valve (25) which is switched on in an excitation circuit, one branch of which is normally open Contains contacts of a pressure switch (27) which responds to the pump pressure, and its other Branch has the normally closed contacts of a pressure switch (26) that clicks on the largest accumulator pressure responds, with the switchover to the various branches by a Relay (36) is effected, which responds to the initiation of the pumping process. 7, device according to claim 6, characterized in that that in the shunt to the electromagnetically operated valve (25) a valve (33) that closes at the highest accumulator pressure. Considered publications:
as German patent specifications No. 627 636, 634204,
670387, 687146, 918 750; U.S. Patents Nos. 2,435,332, 2,453,766,
530521, 2,593,916. . 1 sheet of drawings © 109 527/117 2.61