DE102009049823A1 - Method for processing of water for the maintenance of rinsing baths in connection with wash baths, comprises producing fresh steam through indirect heat transfer, and heating and evaporating the processing water over a heat exchanger - Google Patents

Abstract

The method for processing of water for the maintenance of rinsing baths (3) in connection with wash baths (2), in which the processing water is evaporated, comprises producing fresh steam (7) through indirect heat transfer, and heating and evaporating the processing water over a first heat exchanger. The fresh steams transfer its thermal energy over the first heat exchanger directly to the processing water in which the fresh steams are supplied to a primary side of the first heat exchanger and the processing water is supplied to secondary side of the first heat exchanger. The method for processing of water for the maintenance of rinsing baths (3) in connection with wash baths (2), in which the processing water is evaporated, comprises producing fresh steam (7) through indirect heat transfer, and heating and evaporating the processing water over a first heat exchanger. The fresh steams transfer its thermal energy over the first heat exchanger directly to the processing water in which the fresh steams are supplied to a primary side of the first heat exchanger and the processing water is supplied to secondary side of the first heat exchanger. A thermal exhaust vapor condensation is carried out with a gas jet pump. The fresh steam is used for a drive of the gas jet pump, and exhaust vapors are removed from processing container. The evaporated processing water is separated in a two-stage condensation process in pure distillate and condensate of low-boiling substances. The condensate with low-boiling substances is fed to a steam generator (6) and is used for producing fresh steam. The steam-condensate mixture occurred from the primary side of the first heat exchanger are fed to a distillate container with droplet separator. The heat energy resulting in the condensation of low-boiling substances is transported to the wash-bath, where the heat transmission is carried out over a second heat exchanger in which a vapor phase is guided with low-boiling fraction from the distillate container to the second heat exchanger. An independent claim is included for an evaporation plant for processing of water.

Description

The present invention relates to a process for the treatment of process water according to the preamble of claim 1. Furthermore, it relates to an evaporator system for carrying out the method according to the preamble of patent claim 8.

Various processes in the processing industry produce so-called process wastewater. Parts must be cleaned after production or must be pretreated before coating processes. Often this is a combination of washing and rinsing bath provided, wherein in the washing usually a detergent is added to replace, for example, oils and fats, whereas the rinse is filled with ultrapure water. When transferring the parts from the washing bath into the rinsing bath, cleaning agents and / or other foreign substances, such as impurities and particles, enter the rinsing bath. Usual is instead of a complete replacement and replacement of the rinse the treatment of the same, the so-called Spülbadpflege. During this process, the medium in the rinsing bath should be reprocessed so that it is available again for rinsing purposes. For the treatment of the flushing medium, it is customary to supply it to a heatable bottom tank and to evaporate it. From the steam more substances are often separated, for example, at low temperatures boiling substances. The ultrapure water obtained as distillate or condensate after the process can in turn be added to the rinsing bath and recycled therewith. The systems known in the art are susceptible to wear and maintenance relatively expensive and it would be desirable to simplify the facilities.

Object of the present invention is therefore to provide a process for the treatment of process water and an apparatus for performing the method, which are technically improved over known methods and equipment and are cheaper to maintain.

This object is achieved by a method for the treatment of process water according to claim 1 and by an evaporator system for carrying out the method according to claim 8. Advantageous embodiments are the subject of the dependent claims.

According to the invention, live steam is generated, which is used for heating and evaporation of process water. For this purpose, the live steam is not introduced into the process water, but the live steam gives off its heat by heat transfer via a heat exchanger to the process water. Particularly preferably, the heat input into the process water is not via a secondary medium, but it is carried out via the heat exchanger, a transfer of heat energy from the steam to the process water by the live steam to a primary side of the heat exchanger and the process water to a secondary side of the heat exchanger are supplied.

Further, a thermal vapor compression with a gas jet pump is preferred. The steam produced in the steam generator is used for its drive and the vapor is removed from the process tank.

• a. mechanische Vorreinigung zur Festkörpertrennung
• b. Heizkreis des Prozesswassers
• c. Dampferzeugung
• d. Wärmeübertrag vom erzeugten Dampf auf Prozesswasserkreis
• e. Separation Destillat
• f. Separation Kondensat
• g. Wärmeübertrag von Kondensat auf Prozesswasserkreislauf
• h. Rückführung Destillat in Prozess
• i. Weiterbehandlung Kondensat
• j. Entleerung Prozessbehälter

According to a preferred embodiment, the overall method can be divided into several sub-processes as follows:

• a. mechanical pre-cleaning for solids separation
• b. Heating circuit of the process water
• c. steam generation
• d. Heat transfer from generated steam to process water circuit
• e. Separation distillate
• f. Separation of condensate
• G. Heat transfer from condensate to process water cycle
• H. Recycling distillate in process
• i. Further treatment condensate
• j. Emptying process container

The device according to the invention, here referred to as evaporator system, for carrying out the method according to the invention has a process container in which process water can be taken up and evaporated. Furthermore, at least one condensate container is provided, in which condensate arising during evaporation can be collected. The system has at least one heat exchanger with primary and secondary side and at least one gas compression unit. According to the invention, a steam generator is provided, in which live steam can be generated. Furthermore, a device for directing the live steam to the primary side of the heat exchanger is provided so that the heat energy of live steam and vapors can be transferred to process water present on the secondary side.

The invention will be explained in more detail with reference to the drawing and described, wherein 1 a flow chart of an evaporator system according to the invention shows.

1 is merely a schematic representation, based on which the inventive method will be explained below. It should be noted that flow directions are self-explanatory due to the arrows. Pumps, valves and other common Machine elements of such a system have been omitted for clarity. For a person skilled in the art, the provision of such elements in the appropriate places is daily practice.

The invention comprises a method and a device for the treatment of process water. By processing the z. B. dissolved in cleaning processes and got into the process water cleaning or other types of liquid or solid foreign substances are removed again. The treated process water is then returned to the process.

A possible application for such a treatment is the combination of washing bath and rinsing bath, which is frequently used in practice, for partial cleaning or partial pretreatment before coating processes. Usually, the washing bath is charged with cleaning agents in an aqueous solution and heated. Downstream of this is a rinsing bath which is intended to remove the soiling which has been dissolved by the washing and the cleaning liquid itself from the parts. The rinsing liquid in the rinsing bath is usually untreated water.

The purity of the rinsing bath is, based on the process reliability of the entire treatment process, of elementary importance. The rinsing liquid, referred to as process water, used in the described method as the input medium.

The basis for the treatment of such process waters is the principle of single-stage liquid evaporation and the targeted, stepwise condensation of the various liquid components. The liquid components are usually formed from water, low-boiling liquids and heavy boiling liquids.

During evaporation, first the water and the low-boiling components are evaporated. The components, which have a higher boiling point than water, remain in the process container 4 , The process water 5 is from the rinse 3 via a filter unit (not shown) for removing solid particles in the process container 4 pumped. The liquid is then by means of a circulation pump in a heat exchanger 10 directed and flows into the process vessel 4 back. The thus formed secondary circuit of the heat exchanger 10 is acted upon by water vapor on the primary side.

The water vapor on the primary side 11 At the beginning of the process, supplies the energy for heating the process water. In the current process, he supplies the driving energy for vapor compression at the gas jet pump. The steam can either be available from other processes, preferably this is in the device, for example by a steam generator 6 under fresh water supply, generated.

The generated water vapor, as live steam 7 referred to, is via a gas jet pump 8th with an overpressure relative to the atmosphere, preferably this pressure is between 1 bar and 5 bar, in the primary side 11 of the heat exchanger 10 initiated. The water vapor condenses in the heat exchanger 10 partially. The released heat of condensation increases the temperature of circulating in the secondary circuit process water 5 in the course of time at its boiling point.

It should be emphasized that the live steam 7 at the beginning of the process for heating the process water 5 at boiling temperature required by indirect heat transfer. Once the process has started, the live steam is used 7 mainly for driving the gas jet pump 8th and thus to the compression of the vapors 9 , In this process, the live steam 7 its mechanical energy through the pressure reduction. The uncompressed vapors 9 gives its heat energy through condensation on the primary side 11 of the heat exchanger 10 to the process water 5 on the secondary side 12 of the heat exchanger. The live steam 7 now has a proportionate importance for the heating of the process water 5 ,

The process water 5 starts in the process vessel 4 to boil and evaporate. This is the boiling point, depending on the composition of the process water 5 , in the range of approx. 100 ° C. The resulting process water vapor, the vapor 9 , becomes permanent from the gas jet pump 8th sucked and together with proportional live steam 7 from the steam generator 6 at elevated boiling point for condensation in the heat exchanger 10 brought.

The evaporated process liquid is made by refilling such in the process container 4 replaced.

The steam-condensate mixture 13 from the primary circuit 11 of the heat exchanger 10 is in a downstream distillate container 15 collected. This is kept at a temperature which is just below the boiling point of water. Thus, the condensation of the steam with the condensate mixture 13 entrained gaseous low boilers prevented. Advantageous is a device for droplet separation 26 in the container 15 to the vapor in the container in the vapor phase 15 to restrain and to avoid high flow turbulence. The gaseous light phases are over another Heat exchanger 18 in which they condense. The gaseous low boilers flow after opening a control valve (not shown) between the two containers 15 . 21 due to the pressure difference between the container arising in the process 15 and containers 21 over the heat exchanger 18 , The condensate tank 21 has a procedure 27 can be drained off the water separately from lighter liquids.

The released heat of condensation is in the secondary circuit z. B. to a washing liquid 24 issued.

The condensate formed in the condensation is in the container 21 collected. The condensate is then optionally the evaporation circuit in the process container 4 or the steam generator 6 fed again. This is in the process container 4 forming concentrate of heavy boiling liquids 14 and the concentrate of low-boiling liquids 23 in the container 21 is disposed of depending on the composition or the so-called washing 2 recycled as detergent concentrate.

washing bath 2 and rinse bath 3 are usually already present on site, so that the evaporator system according to the invention 1 neither washing bath in its basic form 2 still rinse 3 contains. However, they serve to complete the flowchart and for better understanding. As already mentioned above, parts to be cleaned, for example engine or engine parts, are first taken to the washing bath 2 transferred. In the embodiment according to the invention, the washing bath 2 a warm bath and accordingly the washing bath 2 Heat is supplied, as will be explained. The cleaned parts then enter the rinsing bath 3 where they are cleaned of detergents and other impurities. Detergent removal is of great importance in some processes, such as subsequent coating or painting of the parts. That's why it's important that the rinse bath 3 always kept as free as possible cleaning. In general, the rinse contains 3 Water. The rinsing liquid then passes, now as process water 5 referred to, in the process container 4 , There is the process water 5 evaporated to rid it of impurities. The resulting water is as a distillate 16 referred, returned to the rinse. In the process water 5 Contain heavy boiling liquids remain as a residue in the process vessel 4 back and are used as a concentrate of heavy boiling substances 14 removed from the process. Lightly boiling substances initially remain as part of the vapors 9 in the process and eventually become a concentrate of low-boiling substances 23 removed from the system.

That in the process container 4 located process water 5 must be heated and evaporated. Unlike in the prior art, this is not done by direct heating of the process container 4 , It is also not, as partially provided in the prior art alternatively, an indirect heating caused by the heat transfer medium through the process container 4 is passed. Instead, being in a steam generator 6 live steam 7 produced, ie it is evaporated water. This steam also drives a gas jet pump 8th at which a thermal vapor recompression is performed. The live steam 7 get along, along with the condensed vapors 9 on the primary side 11 a first heat exchanger 10 , The resulting condensation heat is the on the secondary side 12 circulating process water 5 supplied by indirect heat transfer. The process water 5 is circulated for example via a pump, so that the heat exchanger 10 is flowed through.

Due to the heat transfer condenses the live steam-vapor mixture 25 partially and leaves the primary page 11 of the heat exchanger 10 as a vapor-condensate mixture 13 , which is mixed with low-boiling substances. This steam-condensate mixture 13 enters the distillate tank, wherein a mist eliminator 26 is provided. At the mist eliminator 26 Water droplets form, which are then distillate 16 designates the rinse bath again 3 can be returned. The remaining vapor phase with low boilers 17 becomes a second heat exchanger 18 supplied and on its primary side 19 initiated. In the heat exchanger 18 gives the vapor phase with low boilers 17 their heat energy to the circulating on the secondary side washing liquid 24 from. In this way, a preheating of the washing liquid takes place 24 , As the in the wash 2 introduced to be cleaned parts are colder than the washing liquid 24 this is constantly cooled and must therefore be constantly heated. In the present appendix 1 Advantageously, the process heat is used to make the washing bath 2 to warm up. Depending on the selected process temperatures, it may be sufficient to heat the wash bath 2 purely on the described heat transfer perform. Consequently, an electrical heating of the washing bath 2 partially or completely omitted.

The evaporator system 1 preferably has an electronic control to regulate the evaporation process, in particular with respect to optimum operating pressures, temperature control and fluid levels. Preferably, the process parameters for the operation of the gas compression unit are kept constant by the controller.

As a result, there is an increase in energy efficiency solely by the fact that an indirect heat transfer by generating live steam 7 in one of the process vessel 4 separate steam generator 6 via a first heat exchanger 10 is carried out. By thermal vapor compression using the gas jet pump 8th eliminated mechanical compression devices, which are very susceptible to wear according to experience. In addition, there is a return of the evaporation of the process water 5 resulting heat energy, which again to heat the process water 5 is being used. Experiments showed that only during the heating process, ie for the first generation of live steam 7 in the steam generator 6 , larger amounts of energy must be supplied in the form of heating energy. Once the system is in operation, it only takes very small amounts of energy to keep the system running. In addition to the lower operating costs due to energy costs to be saved, the costs for the operation of the system are also cheaper, since the thermal vapor compression unlike thermal vapor compression needs no wear-prone parts such as rotary blower.

LIST OF REFERENCE NUMBERS

1

evaporator plant

2

washing bath

3

rinse

4

process vessels

5

process water

6

steam generator

7

live steam

8th

Gas jet pump

9

vapors

10

first heat exchanger

11

Primary side of the first heat exchanger

12

Secondary side of the first heat exchanger

13

Steam condensate mixture

14

Concentrate of heavy boiling substances

15

distillate vessel

16

distillate

17

Vapor phase with low boiler content

18

second heat exchanger

19

Primary side of the second heat exchanger

20

Secondary side of the second heat exchanger

21

Container for condensate of low-boiling substances

22

Condensate of low-boiling substances

23

Concentrate of low-boiling substances

24

washing liquid

25

Steam-vapor mixture

26

Droplet

27

procedure

Claims (10)

Process for the treatment of process water ( 5 ), in particular for the care of rinsing baths ( 3 ), used in conjunction with washing baths ( 2 ), in which the process water ( 5 ) is vaporized, characterized in that live steam ( 7 ) is generated by the heat transfer, in particular indirect heat transfer, via a first heat exchanger ( 10 ) the heating and evaporation of the process water ( 5 ) brought about. Method according to claim 1, characterized in that the live steam ( 7 ) its heat energy through the first heat exchanger ( 10 ) directly onto the process water ( 5 ) transfers, by the live steam ( 7 ) of a primary page ( 11 ) of the first heat exchanger ( 10 ) and the process water ( 5 ) of a secondary side ( 12 ) of the first heat exchanger ( 10 ). Method according to one of the preceding claims, characterized in that a thermal vapor compression with a gas jet pump ( 8th ), wherein the live steam ( 7 ) for a drive of the gas jet pump ( 8th ) and vapors ( 9 ) is removed from the process container. Method according to one of the preceding claims, characterized in that the evaporated process water ( 5 ) in a two-stage condensation process in pure distillate ( 16 ) and condensate of low-boiling substances ( 22 ) is separated. Method according to claim 4, characterized in that the condensate with low-boiling substances ( 22 ) a steam generator ( 6 ) and for generating the live steam ( 7 ) is being used. Method according to one of the claims 4-5, characterized in that on a primary side ( 11 ) of the first heat exchanger ( 10 ) accumulating vapor condensate mixture ( 13 ) a distillate container ( 15 ) with a separator, in particular a droplet separator ( 26 ) is supplied. Method according to one of the claims 4-6, characterized in that in the condensation of low-boiling substances resulting heat energy to a washing bath ( 2 ), wherein the heat transfer in particular via a second heat exchanger ( 18 ), preferably by a vapor phase with low boiler fraction ( 17 ) from the distillate container ( 15 ) to the second heat exchanger ( 18 ) is continued. Evaporator plant ( 1 ) for carrying out the method according to one of the preceding Claims, comprising a process container ( 4 ), in which process water ( 5 ) and can be vaporized, at least one condensate container ( 21 . 15 ), in which condensate produced during evaporation ( 16 . 22 ) can be collected, at least one heat exchanger ( 10 . 18 ) with primary side ( 11 . 19 ) and secondary side ( 12 . 20 ) and at least one gas compression unit, in particular a gas jet pump ( 8th ), for thermal vapor compression, characterized in that a steam generator ( 6 ) is provided, in which live steam ( 7 ) can be generated, and that a device for directing the live steam ( 7 ) to the primary page ( 11 . 19 ) of the heat exchanger ( 10 . 18 ) is provided so that the heat energy of the live steam ( 7 ) on the secondary side ( 12 . 20 ) of the heat exchanger ( 10 . 18 ) existing process water ( 5 ) is transferable. Evaporator plant ( 1 ) according to claim 8, characterized in that two condensate tanks ( 15 . 21 ) are provided, wherein in a condensate tank ( 21 ) Condensate of low-boiling substances ( 22 ) and in the other condensate container ( 15 ) Distillate ( 16 ) can be collected that the condensate tank ( 21 ) for the condensate of low-boiling substances ( 22 ) preferably a sequence ( 27 ) in the lower area and that the condensate tank ( 15 ) for the distillate ( 16 ) preferably a mist eliminator ( 26 ), on which water from a vapor-condensate mixture ( 13 ) can be deposited. Evaporator plant ( 1 ) according to claim 8 or 9, characterized in that an electronic control is provided, which controls the evaporation process, in particular operating pressures, temperatures, and liquid levels, and which holds in particular process parameters for operating a gas compression unit constant.

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