DE2544198C3 - Device for neutralizing alkaline waste water - Google Patents

Description

The invention relates to a device for neutralizing alkaline wastewater, liquid carbon dioxide being introduced in controllable quantities from a pressure vessel through a pipe to a CO ₂ pressure relief valve and from this directly into the liquid in a reaction vessel.

Alkaline wastewater, such as that found in the operation of vessel cleaning machines in the beverage industry occur continuously and periodically, can often not without prior neutralization in the Sewer to be let. It is known to waste water in a reactor with strong mineral acids, for example hydrochloric acid. This can be done in batches or in a continuous process. After reaching permissible pH values, the wastewater is then drained, if it is not yet to the To comply with regulations, must be cooled.

It is also already known to use strong mineral acids to neutralize washing machine wastewater To use carbon dioxide, the neutralization very effectively and without the risk of a Causes hyperacidity

Carbon dioxide is present in the usual flue gases and thus flue gas can be used for neutralization draw in. However, the flue gas produced in a boiler system that is currently in operation must be introduced into the liquor to be neutralized, what relatively complicated facilities, for example to compress the flue gas.

Carbon dioxide is produced in considerable quantities in breweries and beverage bottling plants, but it also has to Here a system for collecting, cleaning and Compressing must be available, especially since the carbon dioxide is still used for other purposes within the brewery Should be used if such an extraction system is available.

It is known, for example from DE-OS 22 40 390 and 23 56 510, in connection with counter pressure filling Carbon dioxide from vessels for neutralizing the in vessel cleaning machines to use the resulting alkaline waste water.

A device for neutralizing alkaline wastewater within its own, from the liquid flowed through the liquid container, the one

i "Injector gaseous carbon dioxide is supplied, has become known from DE-OS 22 32 341. DE-GM 69 29 628 has already proposed to impregnate drinking water with carbonic acid, for the production of mixed drinks, in a continuous process, the required carbon dioxide in liquid To meter the form and then, after passing through a CO ₂ pressure relief valve, to introduce it into the interior of a reaction container through which the liquid to be impregnated flows.

· "'Through is not only an exact metering of the carbon dioxide (liquid phase), but also through the Introduction of the evaporated carbon dioxide directly into the reaction vessel, a certain cooling of the to be impregnated achieved.

A simple way that regardless of operational circumstances is the use of carbon dioxide Allowed for neutralization is the purchase of carbon dioxide from pressurized gas containers. That as a neutralizing agent carbon dioxide to be used is in

i "in liquefied form in these pressurized gas containers held and is introduced into the liquid to be neutralized after relaxation.

If the liquid carbon dioxide, which is under high pressure in the carbon dioxide storage container, is in a

'> "> Relief valve (needle valve) to low external pressure relaxed, as it is necessary for introduction into the liquid to be neutralized, then becomes a considerable amount of heat required, which must be supplied to the carbon dioxide so that none

ho icing of the valve and the connected Fittings occurs.

This additional heat requirement, which is usually covered by electrical heating, causes additional ones Costs that the process of neutralization of

^h "Make brewery wastewater more expensive and complicate if the carbon dioxide used for neutralization is taken from carbon dioxide pressurized gas containers in which it is stored in liquid form.

The object of the invention is to prevent the technical, energetic and commercial effort involved the icing of the COr pressure relief valve and the fittings used during the neutralization process of alkaline wastewater and a high degree of efficiency (as complete as possible To achieve neutralization with the lowest possible loss of carbon dioxide).

To solve this problem, in a device of the type specified according to the Invention proposed that a known CO ^ pressure relief valve inside the reaction vessel arranged, is completely surrounded by the wastewater to be neutralized and the Control means or impulse lines of the COr pressure relief valve from the reaction vessel in this way are led out that the CCfc pressure relief valve controllable from the outside> st.

Since the liquid CO ₂ is fed under full high pressure into the liquid to be neutralized, according to the invention the CCh pressure relief valve (needle valve) is arranged within the liquid to be neutralized and completely surrounded by it, whereby the required amount of heat is fed into the valve and then into the CO ₂ can be initiated. This completely prevents the valve and fittings from icing up; on the other hand, means must be provided by which the pressure relief valve can be controlled and switched from outside. The control shaft attached to the valve spindle, control rod or, if the valve is controlled with compressed air or magnetically, the impulse lines come into question as control means. The introduction of the liquid carbon dioxide is the liquid to be neutralized and the associated transition from the liquid to the vapor phase takes place quickly, without disruption and without loss of carbon dioxide, since the introduction of the liquid carbon dioxide takes place below the surface of the liquid to be neutralized. The good meterability of the liquid carbon dioxide also allows a sensitive control, so that a minimal consumption of carbon dioxide is achieved with extensive saturation.

According to the invention it is further proposed that the CO ₂ pressure relief valve is placed inside a pipe through which the liquid to be neutralized flows, its inlet side for liquid CO _{2 is connected to the high pressure CO 2} line introduced into the pipe and the control rod of the CO ₂ pressure relief valve is led out through the pipeline and can be actuated from the outside and that the CO ₂ outlet side of the COr pressure relief valve opens out in the outflow direction of the liquid to be neutralized.

To achieve a uniform neutralization of the amount of liquid, the liquid CO ₂ must be introduced into the liquid that is moved by it. Insofar as the liquid to be neutralized flows inside a pipe, the pressure relief valve is therefore firmly placed inside this pipe and the actuating means are passed through the wall of the pipe to the outside. The outlet opening of the needle valve is then directed towards the outflow direction of the liquid to be re-established and is expediently open or only provided with a small pipe socket around which the liquid flows.

According to the invention, it is further proposed that the pipeline is designed as a circulation line of a waste water collection tub and the CO ₂ expansion valve is arranged within a nozzle-like end piece of the circulation line submerged inside the collection tub, the control rod through the pipeline and the one located in the waste water collection tank to be neutralized Liquid is passed through to the outside.

If the neutralization takes place in a collecting tank, a circulation line is provided and in the nozzle-like end piece of the circulation line, which ends in the interior of the liquid supply, is the Needle valve arranged. The control means are then not only through the wall of the circulation pipe passed through, but also extend above the liquid level of the liquid to be neutralized.

The pressure relief valve can also be arranged directly in the waste water tank, whereby through other means a movement or flow of the sewage can be achieved, for example by a Agitator or a jet nozzle.

On the other hand, if the needle valve is installed in a pipeline, an external one can also be used There is no need for a vat filled with waste water. The neutralization then takes place exclusively in a pipeline can have loop-shaped return and vortex zones.

According to the invention it is further proposed that a heat exchanger, which is also acted upon by the liquid to be neutralized, is arranged in the high-pressure CO _{2 line leading to the submerged CO 2 pressure relief valve.}

As a result, the still liquid CO _{2 can} already be brought to an elevated temperature, as is usually found in the liquid to be neutralized in the collecting tub. There is no need for additional heat to cover the heat of evaporation from the liquid carbon dioxide flowing out of the pressure relief valve. Rather, there is a desired, but in practice mostly quite moderate, re-cooling of the liquid to be neutralized. Nevertheless, this is an additional desired effect, especially since it can reduce the energy expenditure for a possibly necessary recooling of the wastewater before it is discharged into the local sewer system. According to the invention, there is not only an overall reduction in the energy expenditure and the technical effort for heating the liquid CO ₂ , but also an, albeit slight, reduction in the cooling requirement if the wastewater still has to be cooled down.

The relatively small amount of wastewater that occurs continuously can, for example, be up to one A certain amount of lye initially accumulated in the collecting tub, then during repeated pumping over neutralized and discharged in batches. The periodic in a longer period of time with the periodic Renew 6er cleaning solution accumulating wastewater wastewater quantities can be in quite corresponding Be treated in batches or slowly and continuously.

If the amount of lye present in the cleaning machine is drained off quickly, the must also Collecting containers have a correspondingly large volume. In the collecting container, a possibly necessary recooling can be carried out, including appropriately sized heat exchange surfaces in it must be present.

Further advantages and properties can be found in the description and the drawing.

In the drawing, the invention is for example and shown schematically.

F i g. 1 shows a view, partly in section,

F i g. 2 shows the top view of the device according to FIG. 1 and

F i g. 3 shows a detail.

The liquid to be neutralized is located in the collecting tub 1, in the present case the alkaline one Wastewater 2, as it occurs, for example, in bottle washing machines. Before this sewage into the Local sewerage can be initiated, it must be neutralized. If necessary, there is also one Recooling required.

This is always done in relatively small quantities during the operation of cleaning machines Waste water that arises is let into the collecting tub 1 through the pipe 3 and the nozzle 3a and accumulated there and, if necessary, cooled back.

The lye tubs of the cleaning machine become complete at longer intervals emptied and the cleaning solution made up again. When they are emptied, they then fall in a relatively short time relatively large amounts of strongly alkaline wastewater. These are through the pipeline 4, 5, 6, 7, 8 is fed to the tub 1 with the aid of the pump 9 conveying in the direction of the arrow. Here are those if necessary remotely controllable valves 10 and 12 open and valves 11 and 13 closed. The end piece 8a of the Pipeline 8 is nozzle-shaped and is located inside the collecting tub and is submerged in the wastewater 2 located in the collecting tub 1.

It is advantageous to fill the tub 1 with sewage up to an upper liquid level mark and only then to begin neutralization. The height of the liquid level 19 can be arbitrary Manner, for example with a float 15, can be scanned, which relates to the liquid level pulses via a pulse line 15a to the switching and not shown and described Control center passes on. To neutralize the wastewater in the collecting tank 1 are the Valves 10 and 13 closed, but valves 11 and 12 open. The pump 9 promotes while running Motor 9a in the direction of the arrow, whereby liquid through the suction port 16 via the lines 17 and 5 sucked in and fed via the lines 6, 7, 8 to the end piece 8a and there as a liquid jet 2a in Longitudinal direction of the collecting tub emerges. This results in an overturning movement and the partition 17 comes about, which is arranged in the middle of the vat and a separate forward and backward flow of the to neutralizing liquid 2 allowed.

The wastewater 2 present in the container starts rotating, with part of the liquid in each case 2 sucked in through the intake port 16 and through the circulation line 16, 17, 5, 6, 7, 8, 8a under increased Brought pressure and at a correspondingly high speed from the nozzle-shaped end piece 8a is expelled.

Inside the pipe section 8 is the CCb relief valve 18 arranged, which can be designed as a needle valve, the valve spindle 18a from the tube 8 and further to above the liquid level 19 and at the upper end with a

Actuator 20 including control line 20a is mistaken. At the rear end of the expansion valve 18 in the downstream direction, the CCVHochdruckleitunj; connected, which can have a heat exchanger 22 in the form of a helical winding of the high-pressure line 21. Depending on the pH value determined by the measuring device 23 and passed on via the measuring line 23a, the valve spindle 18a is actuated via the actuator 20, so that there; Expansion valve 18 more or less, or ir shorter or longer time intervals is opened within the CO ₂ -Druckgasbehälters 24 eir riser pipe 25 is arranged, which extends almost to the bottom of the pressure vessel 24th At the high pressure prevailing in the pressure vessel 24, CO _{2 is present as liquid CO 2} 26, which, after opening the vessel fitting 27, flows through the line 21 directly to the expansion valve 18 and remains under the full internal pressure of the pressurized gas vessel 24 until there. If the expansion valve 18 is opened, liquid CO2 exits the expansion valve 18 on the downstream side, whereby the CO2 expands at the ambient pressure prevailing at this point, evaporates and the heat required for evaporation is withdrawn from the environment. Since the expansion valve 18 according to the invention is completely immersed in liquid 2 and this liquid 2 flows through the pipe 8, no icing occurs because the heat is partially extracted directly from the wastewater 2 and insofar as there is a cooling effect also for the expansion valve 18, the heat demand is easily covered by the flowing liquid 2 completely surrounding the valve. It is therefore possible to add the CO2 directly in liquid form to the wastewater 2 to be neutralized, whereby additional energy expenditure to prevent the valve etc. from icing up can be avoided and also due to the extremely good and rapid effect of the CO ₂ on the surrounding wastewater 2 during the evaporation process the neutralization effect can be achieved quickly, completely and without CO _{2 gas disposal.} If particularly warm wastewater 2 is to be neutralized, it can be useful to heat the liquid carbonic acid before it enters the expansion valve 18 with the aid of a small heat exchanger 22 and thus bring it to almost the same temperature as the wastewater 2. As a result of the thorough mixing of the liquid jet 2a with the total amount of liquid 2, which moves much more slowly, the entire contents of the tub are neutralized quickly and evenly. Before a partial flow of the liquid 2 enters the suction port 16, the alkalinity of the liquid 2 is determined by the measuring device 23 and, if the neutralization has progressed far enough, the further addition of CO ₂ is stopped by closing the expansion valve 18 with the aid of the actuator 20 and the valve spindle 18 throttled or completely adjusted, whereupon the neutralized wastewater can be fed through the pipeline 28 to the local sewer with the valves 10 and 12 closed and the valves 11 and 13 open.

An additional measuring device that checks the alkalinity in the pipeline 6 or 28 is not shown This measuring device is used for control purposes and, in the event of insufficient neutralization, would open valve 13 close again and open the valve 12 again, whereupon the neutralization process would be repeated.

The valves 10 and 11 or 12 and 13 could also be used as

Be designed three-way valves.

Depending on the desired control program, it is also possible to run as much wastewater 2 through the Continue valve 13, as alkaline waste water is supplied through line 3 and the addition of CO2 so that with constant circulation of the wastewater located in the collecting tank 1 2 the latter always has a permissible residual alkalinity and consequently just as much neutralized wastewater is drained how alkaline wastewater flows in.

The partition 17, which is arranged vertically inside the tub 1 in the example, divides the tub 1 Lengthways in two tracks and, together with the circulation of the liquid, causes that around this tub wall a horizontal circulation of the liquid 2 is created. This partition wall 17 can as well as other walls of the tub also have the function of a cooling surface. So you can use refrigerant or cold brine, in which case special connections and refrigerant lines are provided must be connected.

The circuit inside the tub 1 can also take place in the vertical direction, namely when the Partition 17 is not arranged vertically in the tub, but horizontally at about half the height of the liquid is inserted. Then, through a correspondingly arranged circulation line under the inserted horizontal partition sheet liquid to flow to the other end of the tub 1 and above the Flow back through the partition. Here too, however, the relief valve 18 must be completely off in any case Liquid 2 be surrounded or rinsed so that the addition of the liquid CO2 directly into the neutralizing liquid 2 is possible. Especially if the liquid to be neutralized 2 is still has to be cooled, there is an additional, very desirable effect. Namely, the liquid 2 cools by the immediate relaxation of the liquid CO2 in the liquid 2, what the cooling demand somewhat reduces, possibly also the waiting time until the liquid 2 has cooled down to the required level Maximum temperature that the wastewater 2 may have before it is discharged into the local sewer, slightly reduced. In any case, there is no additional heat input to prevent the expansion valve 18 from icing up necessary.

The expansion valve 18 can also be arranged directly inside the liquid 2 to be neutralized without an external pipeline 8. A very similar pumping device can be used to achieve good mixing. It is also possible to use a stirrer or the like. Instead of an automatic actuation of the expansion valve 18, this valve can also be set manually. Likewise, all other valves can be operated manually. The switching on and off of the pump motor 9a via the energy or pulse line 9b can also take place automatically or manually. It is often expedient to fully open the expansion valve 18 by emitting pulses that are variable over time more or less often per unit of time with a small outlet cross-section and to close it again immediately. This pulse sequence can also be set manually or automatically. Instead of a single CC> 2 pressurized gas container 24, an entire battery of these pressurized gas containers can of course also be provided.

Also a perforated body surrounded by the liquid, the one on the CO2 outlet side of the pressure relief valve 18 is connected, can be used to distribute larger amounts of liquid CO2.

1 sheet of drawings

Claims (4)

Patent claims: 1. Device for neutralizing alkaline wastewater, wherein liquid carbon dioxide is introduced in controllable quantities from a pressure vessel through a pipe to a CO ₂ pressure relief valve and from this directly into the liquid in a reaction _{vessel, characterized in that a per se known CO 2} - Pressure relief valve (18) arranged inside the reaction vessel (1, 8), completely surrounded by the wastewater (2) to be neutralized, and the control means (18a ^ or pulse lines of the CO ₂ pressure relief valve (18) from the reaction vessel (1, 8) are brought out in such a way that the CO ₂ pressure relief valve (18) is steusrbai from the outside. 2. Apparatus according to claim 1, characterized in that the CO ₂ pressure relief valve (18) is placed inside a pipe (8, 8a) through which the liquid to be neutralized (2) flows, its inlet side for liquid CO ₂ to the Pipeline (8) is connected to the CO ₂ high-pressure line (21) and the control rod (iSa) of the CO ₂ pressure relief valve (18) is led out through the pipe (8) and can be operated from the outside and that the CO ₂ -Austri'.tsseite of the CO ₂ pressure relief valve opens in the outflow direction of the liquid to be neutralized (2). 3. Apparatus according to claim 2, characterized in that the pipeline (16, 17, 5,6,7,8, ea ^ is designed as a circulation line of a sewage collection tub (1) and the CO ₂ -E.entspannungsventil (18) within a nozzle-like end piece (Sa) of the circulation line (16,17,5,6, 7,8, 8a) submerged in the interior of the collecting tub (1) is arranged, the control rod (18a, / through the pipeline (8) and the liquid (2) to be neutralized in the collecting tub (1) is passed to the outside. 4. Device according to one or more of claims I to 3, characterized in that in the submerged CO ₂ pressure relief valve (18) guided CO ₂ high-pressure line (21) is also acted upon by the liquid (2) to be neutralized heat exchanger (22 ) is arranged.