KR960010363B1 - Evaporating and concentrating method of aqueous organic materials - Google Patents

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Description

Evaporative Concentration Method of Aqueous Solution Containing Water-Soluble Organics

1 is a view showing a first embodiment in the present invention,

2 is a view showing a second embodiment in the present invention,

3 is a view showing a third embodiment in the present invention,

4 is a diagram showing a multi-purpose evaporation concentrator,

5 is a view showing the gas-liquid equilibrium state of ethylene glycol aqueous solution.

* Explanation of symbols for main parts of the drawings

10: high concentration side evaporation tube, 12 low concentration side evaporation tube,

11, 13 heater, 14 condenser,

18: pipeline for supplying aqueous solution of ethylene glycol, 20, 24: circulation pipeline

28, 31: steam duct, 32: blower compressor,

35: steam ejector, 39: precooler.

The present invention relates to an evaporation concentration method in which an aqueous solution containing a water-soluble organic matter having a boiling point higher than water, such as ethylene glycol or ethylene glycol, is concentrated in evaporating water in the aqueous solution.

Generally, ethylene glycol is used as a snow removing agent, and diethylene glycol is used as an auxiliary material in the manufacture of ink pigments, and these are all returned in a state containing water.

By removing the moisture, it is reused for the use as described above in a high concentration.

By the way, it is common to use a distillation column to increase the concentration of the ethylene glycol aqueous solution by removing water from the aqueous solution. However, since the distillation column is extremely low in thermal efficiency, the operating cost required to increase the concentration of the aqueous solution of ethylene glycol is high. This will be greatly increased.

Therefore, in recent years, although the concentration of the ethylene glycol aqueous solution described above is increased, it has been practiced to use a multi-efficiency evaporation concentrator whose thermal efficiency is much higher than that of the aforementioned distillation column.

This multi-efficiency evaporative concentration apparatus is described in Figs. 4 and 45 on page 429 of, for example, 4th edition of Chemical Engineering Handbook, Issue 4, published by Yuhan Corporation, and also shown in Fig. 4, 1st stage evaporation tube 1 with the heater 1a which uses the steam in a boiler as a heat source, and 2nd stage provided with the heater 2a which uses the steam which arose in the 1st stage evaporation tube 1 as a heat source. It consists of a condenser (3) equipped with a vacuum pump (3a) for the vapor generated in the evaporation tube (2) and the second stage evaporation tube (2), and a thinner (low concentration) concentrate by means of a conduit (4). It is supplied to the first stage evaporation tube (1) described above, and the concentrated liquid evaporated and concentrated in the first stage evaporation tube (1) is transferred to the second stage evaporation tube (2), which is communicated via the conduit (5), Then, the concentrated liquid after being evaporated and concentrated in the second stage evaporation tube is restarted and taken out of the pipeline 6 (in this case, the concentrated liquid is It may be supplied to the second stage evaporation tube 2, transferred from the second stage evaporation tube to the first stage evaporation tube 1, and the concentrated liquid may be taken out from the first stage evaporation tube 1). The steam generated in the second stage evaporation tube (2) is condensed by the condenser (3), and then discharged from the conduit (7). In addition, (8) and (9) are conduits for conveying the condensed water in the heaters 1a and 2a of each evaporation tube 1 and 2 to the condenser 3 which was electric.

However, when the above-mentioned ethylene glycol aqueous solution is evaporated and concentrated by this multi-use evaporation concentrator, there is a problem as described below.

That is, the gas-liquid equilibrium relationship of the aqueous solution of ethylene glycol and water shows that the liquid phase composition (X) and the gas phase composition are shown in FIG. 5 when the horizontal axis is the concentration of ethylene glycol and the vertical axis is the equilibrium temperature. (Y).

Therefore, in the above-described multi-use evaporation concentrator, if the aqueous solution of ethylene glycol is evaporated to 50 wt% with an ethylene glycol concentration, for example, the ethylene glycol concentration in the final evaporation tube for final evaporation is 50 wt%. The vapor generated in the final stage evaporation tube is about 2wt%, as indicated by solid lines (a), (a ') and (a' ') in the gas-liquid equilibrium line of the aqueous ethylene glycol solution of FIG. By containing ethylene glycol, the condensate of this vapor is discharged in the state containing about 2 wt% of ethylene glycol as described above, resulting in the loss of ethylene glycol.

The concentration of ethylene glycol in the condensed water described above is a single-dot chain line in the gas-liquid equilibrium line of the ethylene glycol aqueous solution of FIG. As indicated by b), (b ') and (b' '), the amount of ethylene glycol disappeared with condensate by increasing the concentration of the aqueous solution of ethylene glycol, as indicated by about 4 wt%, is reduced. In other words, the concentration of ethylene glycol in the final short evaporation pipe must be low, that is, the concentration of ethylene glycol aqueous solution must be low. Therefore, there is a problem that the concentration of ethylene glycol aqueous solution can not be increased under the reduced amount of ethylene glycol. .

The present invention provides a method for solving the above-mentioned problems while maintaining high thermal efficiency when evaporating and condensing an aqueous solution containing a water-soluble organic matter having a boiling point higher than water, such as ethylene glycol or diethylene glycol. Let it be technical problem.

In order to achieve this technical problem, Claim 1 of Claim 1 supplies the aqueous solution containing the aqueous solution organic substance whose boiling point is higher than water, such as ethylene glycol or ethylene glycol, into a low concentration side evaporation tube, and continues steam. It is to be taken out from the high concentration side evaporation tube after supplying it into the high concentration side evaporation tube equipped with a heater as a heat source, and the low concentration side evaporation tube is compressed by the part of the vapor evaporated from the aqueous solution in the low concentration side evaporation tube. The heater in was introduced as a member of the heater, and the remaining vapor was led to the condenser, while the vapor evaporated from the aqueous solution was led into the low concentration side evaporation tube in the high concentration side evaporation tube.

In the present invention, the claim 2 is to supply an aqueous solution containing a water-soluble organic substance having a boiling point higher than that of water, such as ethylene glycol or diethylene glycol, into the low concentration side evaporation tube, and then to use steam or the like as a heat source. Heater in a low concentration evaporation tube which is fed into a high concentration side evaporation tube equipped with a heater and taken out from the high concentration side evaporation tube, and compresses a part of the vapor evaporated from the aqueous solution in the low concentration side evaporation tube. As a member of this heater, the remaining steam is introduced into the condenser, while the vapor evaporated from the aqueous solution in the high concentration side evaporation tube is introduced into the low concentration side evaporation tube. Precooler before introducing the steam from the evaporator tube into the heater and the condenser in the low concentration side evaporator tube It was introduced into a pre-cooler, where it was brought into direct contact with the lean aqueous solution.

The water solution supplied to the low concentration side evaporation tube is heated by a heater in this low concentration side evaporation tube, and is evaporated to an appropriate concentration in this low concentration side evaporation tube.

The aqueous solution after evaporation and concentration in the low concentration side evaporation tube is supplied into the high concentration side evaporation tube, where it is evaporated to a predetermined concentration concentration by heating with a heater in the high concentration side evaporation tube and then taken out.

On the other hand, the vapor evaporated from the aqueous solution in the above-mentioned high concentration side evaporation tube is introduced into the above-mentioned low concentration side evaporation tube, and then a part thereof is compressed together with the vapor evaporated from the aqueous solution in the low concentration side evaporation tube. It is introduced as a member of this heater to the heater in the low concentration side evaporation tube, and residual steam is introduced into the condenser and becomes condensed water and discharged.

In this case, the vapor concentration evaporated from the aqueous solution in the low concentration side evaporation tube described above, and the low concentration concentration of the vapor evaporated from the aqueous solution in the high concentration side evaporation tube described above and then compressed by a portion of the steam entering the low concentration side evaporation tube. Since it is a so-called self-medium compression type which is introduced into the heater in the side evaporation tube and is used for heating evaporation of the aqueous solution in the above-mentioned low concentration side evaporation tube, high thermal efficiency can be maintained.

On the other hand, since the concentration of the aqueous solution in the high concentration side evaporation tube described above is a predetermined concentration, the vapor-liquid state value corresponding to the predetermined high concentration concentration is given to the vapor evaporated from the aqueous solution in the high concentration side evaporation tube. Although it contains water-soluble organic substances, such as ethylene glycol, the vapor evaporated from aqueous solution in the high concentration side evaporation tube mentioned above is not condensed as it is, but is introduce | transduced into the low concentration side evaporation tube mentioned above, and the water-soluble organic substance in this steam is By dissolving in an aqueous solution in the low concentration side evaporation tube, the solution is in the gas-liquid equilibrium state according to the concentration in the aqueous solution in the low concentration side evaporation tube, and after this state, it is introduced into a few condensers and condensed. Vapor-liquid equilibrium according to the concentration in the aqueous solution in the low-concentration evaporation tube containing the concentration of the water-soluble organics contained It can lower the value of the state.

In addition, as described in claim 2, the vapor in the low-density side steam pipe described above is introduced into the precooler before being introduced into the heater and the condenser in the low-density side evaporation tube, and is brought into direct contact with the lean aqueous solution. In this case, some of the water-soluble organics in the above-mentioned low concentration side steam pipes are dissolved in the lean aqueous solution, and thus the gas is in equilibrium with the concentration in the lean aqueous solution. The concentration of the water-soluble organics can be lowered to the value of the gas-liquid equilibrium according to the concentration in the aforementioned thin aqueous solution.

Therefore, according to the present invention, since the concentration of the water-soluble organics contained in the condensed water can be drastically reduced while maintaining high thermal efficiency, the concentration of the aqueous solution containing the water-soluble organics is evaporated and concentrated. It does not lead to an increase in the loss of water-soluble organic matter and has an effect that can be raised significantly under high thermal efficiency.

In addition, according to claim 2, since the concentration of the water-soluble organics contained in the condensate can be lowered than in the case of the foregoing, the above-mentioned effect is further improved.

EMBODIMENT OF THE INVENTION Hereinafter, the Example in this invention is described by drawing. 1 shows an embodiment according to claim 1 and in this figure, 10 denotes a closed high concentration evaporation tube, in which the high concentration side evaporation tube 10 has a pair of headers at both ends. The heater 11 which consists of a header 11a, 11b and the some heat exchanger pipe 11c which connects between the both header 11a, 11b is provided.

Similarly, reference numeral 12 denotes a hermetic low concentration evaporation tube, and in this low concentration evaporation tube 12, a pair of headers 13a, 13b and both headers 13a are disposed at both ends. The heater 13 which consists of a some heat exchanger tube 13c which connects between and (13b) is provided.

Moreover, 14 denotes a condenser which is cooled by the cooling water supplied from the conduit 15, and the condenser 14 is connected with a vacuum generator such as a vacuum pump 16, The discharge pump 17 is connected.

The ethylene glycol aqueous solution supplied from the conduit 18 in the low concentration side evaporation tube 12 was pumped out to the circulation pump 19, and then installed in the upper portion of the lower concentration side evaporation tube 12 than the circulation conduit 20 ( 21, and the ethylene glycol aqueous solution pumped out by the circulation pump 19 which carried out the circulation distributed to the outer surface of each heat exchanger tube 13c in the heater 13 which was electric-charged by this nozzle 221 was carried out. A part of is fed into the high concentration side evaporation tube 10, which is electricity from the conduit 22. The ethylene glycol aqueous solution supplied into this high concentration side evaporation tube 10 is sent to the circulation pump 23, and then sent to the nozzle 25 installed in the high concentration side evaporation tube 10 in the circulation line 24, While the circulation is spread out on the outer surface of each heat pipe 11c in the heater 11 that is electricized by the nozzle 25, a part of the ethylene glycol aqueous solution that is pumped out by the electric circulation pump 23 is a pipe line. Discharged at 26.

In addition, the steam outlet 27 is connected to the vapor inlet 29 into the high concentration side evaporation tube 12 through the vapor duct 28 in the high concentration side evaporation tube 10 that is described above. The steam duct 31 at the steam outlet 30 in the low concentration side evaporation tube 12 is connected to the electric condenser 14.

A portion of the steam flowing in the steam duct 31 from the low concentration side evaporator tube 12 to the condenser 14 is compressed by a blower compressor 32 and then through the steam duct 33. A steam ejector driven by the steam supplied from the steam pipe line 34 in a boiler (not shown), while one side of the heater 13 of the low concentration side evaporator tube 12 is supplied to the header 13a. After being compressed by the ejector 35, it is supplied to one of the headers 11a of the heater 11 of the high concentration side evaporation tube 10 via the vapor duct 36.

In addition, the heater 13 of the low-concentration evaporation tube 12 in which the condensed water in the heater 11 of the high-concentration-side evaporation tube 10 described above is communicated through the conduit 37 in the other header 11b. After supplying into the one header 13a in (), together with the condensed water in the heater (13) of this low concentration side evaporation tube (12), the other header (13b) is connected via the pipe line (38). To a condenser (14).

In this configuration, the ethylene glycol aqueous solution supplied from the conduit 18 in the low concentration side evaporator 12 is circulated by the circulation pump 19 to heat the heater 13 in the low concentration side evaporator 12. ), The concentration is evaporated to an appropriate concentration in the low concentration side evaporation tube 12.

The ethylene glycol aqueous solution after evaporation and concentration in the low concentration side evaporation tube 12 is supplied into the high concentration side evaporation tube 10 via the tube 22, whereby the circulation is repeated to the circulation pump 23, Since it is heated by the heater 11 in this high concentration side evaporation tube 10, it is proficiently concentrated up to predetermined | prescribed concentration concentration, and is taken out from the pipe line 26.

On the other hand, in the above-described high concentration side evaporation tube 10, the vapor evaporated from the ethylene glycol aqueous solution is introduced into the low concentration side steam tube 12 described above via the vapor duct 28, and then the low concentration side evaporation tube ( 12, together with the vapor evaporated from the aqueous ethylene glycol solution, a part of it is compressed by the blower compressor 32 and the vapor ejector 35, and the heater 13 in the low concentration side evaporation tube 12 described above, and Into the heater 11 in the above-mentioned high concentration side evaporation tube 10, as a member therein, residual steam is introduced into the condenser 14, and after the condensed water is converted into the discharge pump 17. Will be discharged.

Vapor evaporated from the ethylene glycol aqueous solution in the low concentration side evaporation tube 12 described above, and steam entering the low concentration evaporation tube 12 described above after evaporating from the ethylene glycol aqueous solution in the high concentration evaporation tube 10 described above. A part is compressed by the blower compressor 32 and the vapor ejector 35, and the heater 13 in the low concentration side evaporation tube 12 mentioned above, and the heater 11 in the high concentration side evaporation tube 10 mentioned above. Introduced as a member thereof, and used for heating evaporation of the aqueous ethylene glycol solution, so-called self-vapor compressor type, it is possible to maintain high thermal efficiency.

In addition, the vapor ejector 35 may be abolished so as to supply steam from the steam pipe path 34 to the heater 11 in the high-concentration side evaporation pipe 10. In the case where the ethylene glycol aqueous solution having an ethylene glycol concentration of 10 wt% is evaporated to 50 wt%, the evaporation concentration is reduced to 30 wt% in the low concentration side evaporation tube 12 described above, and the high concentration evaporation tube 10 described above. When the evaporation concentration is finally set to 50 wt%, the concentration of the ethylene glycol aqueous solution in the high concentration side evaporation tube 10 is 50 wt% of the predetermined (final), so that the high concentration side evaporation tube 10 The vapor evaporated from the aqueous ethylene glycol solution contains about 2 wt% of ethylene glycol, as indicated by the solid line (a) (a ') (a' ') in the gas-liquid parallel of the aqueous ethylene glycol solution of FIG. The vapor evaporated from the ethylene glycol aqueous solution in the above-described high concentration side evaporation tube 10 is not condensed as it is, but is introduced into the above-described low concentration side evaporation tube 12, so that As to by, the low-concentration side evaporator is in a gas-liquid equilibrium of the 30wt% concentration in the ethylene glycol aqueous solution of 30wt% concentration in ethylene glycol in the low concentration side evaporator 12 in the (12).

Therefore, the ethylene glycol concentration contained in the vapor discharged from the low concentration side evaporation tube 12 described above is the double-dotted line (c) (c ') (c' 'in the gas-liquid equilibrium of the aqueous ethylene glycol solution of FIG. As indicated by), the amount of ethylene glycol lost together with the condensed water discharged by the discharge pump 17 can be greatly reduced.

2 shows an embodiment corresponding to claim 2, in which a closed precooler 39 is installed in a vapor duct 31 in the low-concentration evaporation tube 12 described above. The vapor in the low concentration side evaporation tube 12 passes through the precooler 39 and flows to the regular condenser 14 and the blower compressor 32 or the steam ejector 35, Then, the water cooled by the cooler 40 using the cooling water for the condenser 14, which has been introduced into the precooler 38, as the cooling source, is scattered by the nozzle 42 via the conduit 41, and the water is dispersed. It is comprised so that circulation to supply to the cooler 40 which was transmitted by the pump 43 is performed.

In this case, in the precooler 39 described above, a plurality of metal meshes 44 and the like are provided with a mist collecting and responding portion.

In this configuration, since the vapor pressure of the ethylene glycol in the vapor in the low concentration side evaporation tube 12 is lower than the vapor pressure of water, most of the ethylene glycol is dissolved in the circulating water dispersed in the precooler 39 described above. .

In this embodiment, when the ethylene glycol solution having an ethylene glycol concentration of 10 wt% is evaporated to 90 wt%, in the low concentration side evaporation tube 12 described above, the high concentration is evaporated to 40 wt%. When the vaporization in the low concentration evaporation tube 12 described above is set to evaporative concentration to the final 90 wt% in the side evaporation tube 10, it corresponds to 40 wt% in the gas-liquid equilibrium line of the aqueous ethylene glycol solution of FIG. Although ethylene glycol is contained in the concentration, most of the ethylene glycol in the vapor is dissolved in the water supplied to it in the precooler 39, so that the concentration of ethylene glycol in this water is 0 wt%. The concentration of ethylene glycol in the vapor leaving the precooler 39 is almost zero, as indicated by the dotted lines d and d 'in the gas-liquid form of the aqueous solution of ethylene glycol in FIG. Therefore, the amount of ethylene glycol lost together with the condensed water discharged by the discharge pump 7 described above can be further reduced than in the case of the first embodiment described above, while the aqueous solution of ethylene glycol can be evaporated to 90 wt%. It is.

In the present embodiment, the circulating water in the preheater 39 described above is made of a dilute ethylene glycol aqueous solution and then supplied to the low concentration side evaporation tube 12 provided in the conduit 45, and this precooler 39 As a supply water for the pre-cooler using the ethylene glycol aqueous solution supplied from the conduit 18 to the low concentration side evaporation tube 12 described above, and all or part of the ethylene glycol aqueous solution in the conduit 18 mentioned above. The precooler 40 may be configured to be supplied to the low-concentration side evaporation tube 12 which has been passed through 39, and the cooler 40 is circulated in the circulating water of the precooler 39 as shown in FIG. 3. 39) may be installed inside.

In each of the above-described embodiments, the heaters 11 and 13 in each of the evaporation tubes 10 and 12 are provided inside the evaporation tubes 10 and 12, respectively. Although the case where the ethylene glycol aqueous solution in each evaporation tube 10 and 12 is heated outward of the heat exchanger tubes 11c and 13c in 11 and 13 is shown, this invention is not limited to this. The heaters 11 and 13 in each of the above-described evaporation tubes 10 and 12 are provided outside the evaporation tubes 10 and 12 to the heaters 11 and 13. The present invention can also be applied to a case in which the ethylene glycol aqueous solution in each of the evaporation tubes 10 and 12 is heated, and the present invention can also be applied to the case where three or more evaporation tubes are used.

Claims (2)

After supplying an aqueous solution containing water-soluble organic matter higher than boiling water, such as ethylene glycol or diethylene glycol, into the low concentration evaporation tube, and subsequently supplying it into the high concentration evaporation tube equipped with a heater having steam as a unit, this high concentration It is taken out from the side evaporation tube, and a part of the vapor evaporated from the aqueous solution in the above low concentration side evaporation tube is compressed and introduced as a member of the heater to the heater in the previously described low concentration side evaporation tube. A method of evaporating and condensing an aqueous solution containing a water-soluble organic matter, characterized in that it is introduced into a condenser and vapor is evaporated from an aqueous solution in said high concentration side evaporation tube into said low concentration side evaporation tube. An aqueous solution containing a water-soluble organic substance having a boiling point higher than that of water, such as ethylene glycol or diethylene glycol, is supplied into the low concentration side evaporation tube, and then supplied into the high concentration side evaporation tube having a heater using steam as a heat source. The part of the vapor evaporated from the aqueous solution in the low concentration side evaporation tube is compressed and introduced into the heater in the concentration side evaporation tube as a member of the heater, and the remaining steam is introduced into the condenser. In the meantime, the vapor evaporated from the aqueous solution in the high concentration side evaporation tube was introduced into the low concentration side evaporation tube, and the heater and the electric heater of the low concentration side evaporation tube in which the steam of the low concentration side evaporation tube was introduced. Before being introduced into the condenser, it is introduced into a precooler where it is brought into direct contact with the lean aqueous solution. Evaporation and concentration method of the aqueous solution containing the water-soluble organic substance made into.