DE2355639A1 - DEVICE FOR DELIVERY AND GASIFICATION OF A LIQUID GAS MIXTURE - Google Patents

Description

Patent notice

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8Wur _: ifen2, Rosental7
Tel. 2603989

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Vogelbusch Society m.b.H. in ¥ ien

Device for conveying and gassing a liquid gas mixture

The invention relates to a device for conveying

and gassing of a liquid gas device with a Krexselpumpenlaiafrad having impeller channels. The invention particularly relates to a device for gassing one in one. Container located liquid, the .Flüssigkeit from the container is sucked, is recirculated via a fumigation and recovered in the tank ₀ In such a device sur finest fumigation a "in a reaction vessel liquid contained, the zn gassed liquid by means of ain @ s uihI on end, equipped with impeller channels, radially from the inside nacli externally applied impeller ₉ which 'the su fumigated draws liquid ₉ and aussclaleudert means & ®τ blades iia circuit aur Begasuagsstell® out ₉ wherein the Lsufrad preferably gassed liquid into the w. © intauoht . Heibei to the ^ © gas in the liquid feiisst Mn are uniformly distributed _o © B i teohniseheH Begasungsproblemen-

has the liquid to be gassed that has been sucked in by the paddle wheel usually a gas content of 5 to 50% by volume.

It is now inevitable that gas bubbles, which interfere with the conveying effect or make it impossible, with the additional to be fumigated are sucked in.

All these known devices therefore have the disadvantage that they contain the gas-liquid mixture to be conveyed not at all or only with the greatest expenditure of energy «- can change. The reason for this is obviously to be found in the fact that the gas bubbles in the rotating impeller are smaller because of their smaller size specific gravity relative to the liquid migrate in the opposite direction to the conveying direction. This separation of serious and light mixture components in centrifugal pumps of known design is caused by the pressure gradient in the centrifugal wheel, which causes the bubbles to lift towards the lower pressure, i.e. counter to the conveying direction. (The movement of the Bubbles in the liquid will be used below for the sake of simplicity referred to as "rising", although not in vertical Direction must take place). At the wheel entry, with radial or semi-axial pressurized centrifugal pumps, i.e. in the area close to the axis, this effect of centrifuging out occurs only to a small extent, so that the gas bubbles together with the liquid get into the wheel channels and there with increasing steepness of the pressure gradient more and more in relation to the liquid lag behind. They collect at the point where the relative speed of the The conveyed liquid and the component of the opposite direction related to the liquid flow. : "!: Rate of climb of the bubbles are the same size, and in the further course form a gas cushion which cannot be conveyed further can and leads to the known tearing off (interruption) of the promotion. It has already been suggested for the purpose Provide a centrifugal pump impeller for conveying and gassing a liquid mixture and between the two halves of the impeller to supply the gas used for fumigation. By such a Training is the mixing of the gas with the ge

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promoted liquid, but this in no way eliminates the disadvantage that there are in the impeller channels Air collects, causing the pump delivery to stall.

The invention now aims to eliminate these disadvantages. The invention relates in particular to a device for conveying and gassing a liquid gas mixture, with a two-rutigen impeller channels having Centrifugal pump impeller of radial or semi-axial design, the two impeller halves of which are used for gas supply through one at the periphery open chamber are separated from each other and consists essentially that the cross-section of the impeller channels steadily decreases in the conveying direction and that both impeller halves are surrounded by a common stationary guide ring designed as a compressor.

The fact that the cross section of the impeller channels steadily decreases in the conveying direction ensures that in the conveying direction the relative speed (flow speed relative to the impeller) increases and the pressure decreases or at least does not increase significantly. The resultant of the relative speed of the pumped liquid and the rate of rise of the Bubble is therefore directed in the direction of the relative speed. In other words, it gives everyone Place the resultant of the relative speed in the impeller channel the liquid related to the impeller channel on the one hand and the rate of rise of the bubbles related to the liquid on the other hand, a component in the longitudinal direction of the impeller channel, which points towards the channel outlet and is larger than Is zero. It is thus achieved that the gas bubbles are in the direction of the conveyed flow are conveyed away and the formation of a gas cushion in the conveying device is avoided. If the pressure decreases in the direction of the liquid flow, the bubbles can even lead in relation to the Result in the flow of liquid, while at constant pressure in the conveying direction, the gas bubbles are equal to the liquid.

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be promoted sensibly. If the pressure increases slightly in the conveying direction, the gas bubbles will remain, but they will still be carried away by the flow of liquid. In the latter case, the remaining gas bubbles can adversely affect the delivery rate, but in all cases the formation of a gas cushion is avoided and the risk of the pump delivery being torn off is definitely eliminated. The measure of reducing the cross-section of the impeller channels in the conveying direction now has the effect of preventing the pump conveying from breaking off, but this measure alone cannot overcome the conveying problems that occur. The device according to the invention is used in a preferred measure to circulate the liquid to be gassed in a tub, the pump .below the liquid level is arranged in the tub and the pumped and newly gassed liquid must be pushed back into the tub, the static pressure on the relevant point below the liquid level in the vat must be overcome. If, however, the pressure in the impeller channels decreases and the outlet pressure is lower than that. static pressure is in the vicinity of the exit point, the promotion is again carried out by the

. Gegenruok interrupted. The same also applies to the handling of other conveying problems . To avoid this, the second Merkaal is now required, namely that both running

, the wheel halves of a common stationary guide crane designed as a compressor are provided by this guide ring, the pressure of the liquid escaping from the impeller channels is increased again, so that the pumping of the pump is ensured. Ia fixed Leitradkranz there is now no longer the risk that the promotion is interrupted by opposite to the Ford establishment "urUekbleibende Gasblaeen, since the Flttssigkeltsgasgemisoh is naohgesohoben speak ax by pump in the fixed nozzle ring and also" in "tan optionally forming GAE

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upholstery could no longer affect the promotion.

According to the invention, the centrifugal pump impeller is expediently designed so that the square d © r realtiven Flow velocity (w *) of the conveyed medium the exit point is equal to or greater than the sum of the square of the relative flow velocity (w) of the to conveying medium at the point of entry and the difference between the square of the peripheral speed (µg) of the Impeller at the exit point and the square of the peripheral speed (u ^) of the impeller at the point of entry. The energy equation for the relative disturbance in the impeller channels such a centrifugal pump

Here and in dan mean the following statements

w = relative speed of the liquid in relation to the impeller,

w ~ - relative speed of the liquid -

related to the impeller, on the third side outside the channel,

w- relative speed of the liquid referred aiaf the Laufraäj, ae @ aug © @ itigen circumference d @ s Lbmf schaff®lkrems @ s _s outside the Lswfkanal.

Impeller ο

Ug- = UiQfangsgesefewimdiglseit a point of the impeller & m taaeka-sided impeller circumference.

U ^ - circumference g®s © hwiiadigkeit ®inas point ö®s Impeller on the dirty side of the barrel chauf e1kranz e s.

h = pressure expressed as a column of liquid.

hg pressure, expressed in PltiSBigkeitssäul® am Output of the impeller channels.

h _± - pressure - expressed as a column of liquid at the entrance of the impeller channels.

g - acceleration due to gravity.

In any case, g is constant. The following two cases can be distinguished. For h ^ = In ₂ we get

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• For hg \ as h ₁ we get

V> o ² ♦ <- H ² ·

The pressure on the outlet side of the impeller is then equal to or less than the pressure on the Entry side if

This condition gives the designer the guideline for the design of the impeller channels. This condition gives sor with the preferred case that the pressure in the conveying direction remains the same or decreases, i.e. that the gas bubbles are also conveyed and a separation from the liquid is avoided.

The arrangement is expediently such that the flow cross-section of the impeller channels at the point of entry is up to four times, preferably twice that Flow cross-section at the exit point is. In this way a safety factor is created so that Even under the most unfavorable conditions, the production cannot be impaired. Such a safety factor is advantageous because the suction of the gas at the outlet point of the impeller channels consumes energy.

The invention thus offers significant advantages for the conveyance of liquids or liquids containing gas inclusions. Liquid gas mixtures of any kind, but can be used in particular for pumping liquid gas mixtures, their gas content 10 to 50% by volume, as is the case with technical fumigation pro- » blemen comes into question, and auoh more amounts to application Find. If the device according to the invention is in a fermentation tank is arranged, a liquid gas mixture is already in the tub after a short period of operation before, which uragepumpt through a fumigation point and there is re-fumigated. The pump must therefore be able to cope with the delivery of a liquid gas mixture with a large proportion of gas and for this purpose the device according to the invention is in particular Dimensions suitable.

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In the drawing, the invention is based on exemplary embodiments shown schematically.

Fig.l shows the speed triangle in known pumps and Fig.2 shows the speed triangle in the device according to the invention, Fig.3 and h show the device according to the invention, xiobei Fig. 3 is a vertical section along the line III-III of Fig.4 and FIG. K shows a horizontal section along the line IV-IV of FIG. 5 shows a vertical section through a device according to the invention, in which several running wheels are arranged on a vertical hollow shaft.

Fig.! Represents the speed triangle in a common Pump impeller, whereas FIG. 2 shows the speed ratios at the wheel inlet and outlet for a pump impeller represents the device according to the invention. The designation of the sides of the speed triangles is according to DIN 1331 selected. Unless the terms have already been explained above, means

e is the absolute velocity of a liquid particle on the suction-side circumference of the rotor blade ring outside the runner channel.

c_ the absolute speed on the pressure-side * impeller circumference outside of the runner channel,

^C 3m is the component of the absolute velocity of a liquid particle on the pressure-side impeller circumference outside of the running channel in the meridional direction and

c- the component of the absolute velocity of a liquid particle on the pressure side Impeller circumference outside the runner channel in Circumferential direction.

In contrast to a known pump wheel, in which c_ is approximately equal to c _q , in a paddle wheel according to the invention c_ must be increased to a degree that has not yet been carried out. The large meridian exit speed enables the majority of the delivery head of the pump to be accommodated in the exit speed q ". According to the invention, it is possible to use c- and thus w "

C =, "7 ^

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to be increased so that the nip pressure becomes negative. If the pressure at the inlet of the paddle wheel is, for example, 4 m WS, the Hrid entrance be dimensioned so that there is only a pressure of 0.5m prevails and the remaining part of the pressure energy, i.e. 3 »5m WS is converted into speed energy of 8.26m / s. In the paddle wheel itself, for example, the pressure of + 0.5m WS can be reduced to -0.5m WS, while at the same time the energy content of the liquid emerging from the paddle wheel to, for example 8 kpm /, is increased; about 4 kpm /, then serve for Overcoming the static pressure, with the remaining 4 kpm /,

are available for the compression of the sucked gas.

Fig.3 and Fig.4 show an arrangement for gassing a liquid located in a reaction container 1. The impeller 18 has a double-flow design and rotates within the reaction container 1, the bottom of which is denoted by 2. the the two halves of the impeller are labeled 7 and 8. The drive shaft 9 is passed through the bottom 2 of the container 1 and against the bottom by a seal, for example a Stuffing box 10, sealed. The drive takes place by means of a Shaft 9. 3 are the impeller channels, which are formed by 4 blades. 5 are the entry points into the impeller and 6 the exit points. A hollow shaft 11 is used for the gas supply. The gas enters a through openings 12 Chamber 13 between the two impeller halves 7 and 8. The at The liquid exiting the exit points 6 of the two impeller halves enters an annular mixing chamber 14 Chamber 13 is open at its periphery and opens into the mixing chamber 14. The delivery pressure at the outlet point 6 is lower than the gas pressure in the chamber 13, so that gas is sucked out of the chamber 13. When through the hollow shaft 11 gas with atmospheric Pressure is supplied, the delivery pressure at the outlet point 6 should be below atmospheric pressure. In the mixing chamber 14 therefore forms a gas vacuole 15, at the interfaces of which the gas is finely distributed in the liquid flowing past is introduced. In a ring-shaped diffuser l6 of the stationary one adjoining the ring-shaped mixing chamber 14

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Guide ring 21 is the liquid gas mixture to the required Brought pressure, which is the static pressure of the liquid gas mixture in the container 1 in the Height of this diffuser 16 must exceed. The two halves of the impeller 7 and 8 are connected to one another by radial ribs 17.

FIG. 5 shows an arrangement in which several impellers 18 according to FIG. 3 and FIG. 3 are arranged on a common hollow shaft 9 at different heights a gas outlet opening 12 is provided for each impeller. 19 is the holder for the diffuser. Each of these impellers now fumigates an area belonging to it via the diffuser 16. The arrows 20 indicate the circulation of the liquid gas mixture from the diffuser ± 6 to the entry points 5 of the impellers _o

If the feed process is used, it can It can happen that at the beginning of the process, one or more of the higher-order impellers are in a gas atmosphere run above the liquid gas mixture. The radial Ribs 17 are now designed as compressor blades, so that the gas supplied through the channel Ii has a slight overpressure is issued, by which it is prevented that used gas from the gas atmosphere above that to be gassed Liquid gas mixture penetrates into the gas supply 11. Such an arrangement with several superposed impellers has a strong overturning movement and a great turbulence and micro-turbulence result. This increased Turbulence causes an increased exchange of substances, which at the known devices can not be achieved. In the diffuser ~ 16 the gas has to pass through the conveying energy of the impellers to be compensated for the static pressure at the exit point. The arrangement of several impellers on top of each other requires thus a lower energy consumption, because at the exit point With the impellers arranged higher up, only a lower static pressure has to be overcome.

Claims;

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Claims (3)

Patent claims: (i.j device for conveying and gassing a liquid sgasgemisches, with a double flow having impeller channels Centrifugal pump impeller of radial or semi-axial design, the two halves of the impeller through one of the gas supply lines serving chambers which are open on the periphery are separated from one another, characterized in that the cross-section of the impeller channels (3) decreases steadily in the conveying direction and that both impeller halves (7> 8) are surrounded by a common stationary guide ring (21) designed as a compressor. 2. Apparatus according to claim 1, characterized in that the centrifugal pump impeller (18) is designed so that the square of the relative flow rate (w-) of the conveyed medium at the outlet point (6) is equal to or greater than the sum of the square of the relative flow velocity (w) of the medium to be conveyed at the entry point (5) and the difference between the square of the circumferential speed (ug) of the impeller at the exit point (6) and the square of the circumferential speed (u _± ) of the impeller at the entry point (5 ). 3. Apparatus according to claim 1 or 2, characterized in that the flow cross-section of the impeller channels (3) at the entry point (5) up to four times, preferably twice the flow cross-section at the exit point (6) is. 409820/08 8 6 i6.io.73 / si