KR101769949B1 - Evaporation and concentration system and method having improved energy efficiency - Google Patents

Abstract

The present invention provides an evaporation and concentration system and a method thereof with the improved efficiency of energy consumption, capable of evaporating and concentrating a large amount of high concentration waste water. The system includes: a waste water pretreating part primarily removing solids from waste water by using chemicals or a filter; a preheater preheating the pretreated water by using condensate water supplied from a condensate pump; a first evaporator evaporating the pretreated water, which has gone through the preheater, to make concentrate; a second evaporator re-concentrating the concentrate of which temperature is increased through a second heat exchanger; a concentration tank storing the concentrate more concentrated through the second evaporator; and a concentration pump transferring the concentrate from the second evaporator to the concentration tank.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an evaporation concentration system and an evaporation concentration system,

The present invention relates to an apparatus and a method for concentrating wastewater, and more particularly, to an evaporation concentration system and an evaporation concentration method that can reduce the amount of heat energy to be supplied while treating a high concentration wastewater at a high capacity .

Generally, as a method for purifying and treating industrial wastewater or the like, there is a method in which a coagulant is added to wastewater to precipitate coagulated foreign substances, and a method in which foreign matter contained in wastewater is screened and removed.

Also, the wastewater filtered primarily by the foreign matter is supplied to the evaporation concentrator, which is the secondary treatment facility, and the waste water is heated in the evaporator to evaporate and separate the residual sludge.

The wastewater treatment process using the evaporation concentrator is a process of separating the wastewater into steam and residual concentrate. When the concentration of the concentrate increases with the repetition of the concentration process, the boiling point rises and the evaporation efficiency decreases sharply do.

At this time, inorganic salts or organic salts in the concentrated liquid adhere to the inside of the first evaporator or the heat exchanger, thereby lowering the heat transfer efficiency.

An example of a wastewater treatment apparatus is disclosed in Korean Patent Registration No. 0870449.

Fig. 1 is a view schematically showing a configuration of an example of a conventional wastewater treatment apparatus.

1, a conventional wastewater treatment apparatus includes a chamber 10, a condensing section 20 having a cooling pipe through which a low-temperature fluid flows, and a condensing section 20 for condensing the condensed water generated on the surface of the cooling pipe A cooling tower 40 for circulating and supplying cooling water to the cooling pipe and a wastewater for heating the wastewater to supply the wastewater into the chamber 10 is provided with a heating portion 50 .

When the heated wastewater passes through the inside of the chamber 10, the steam generated from the wastewater is condensed on the outer circumferential surface of the cooling pipe, so that the water content in the wastewater is reduced by a certain amount. The remaining wastewater is recovered into the wastewater tank 70, The heating unit 50 and the chamber 10 are repeatedly circulated while the wastewater is vaporized and condensed so that only a small amount of sludge can finally be discharged.

However, in such an apparatus, the steam of the wastewater heated by the heating unit 50 is condensed and discharged in the chamber 10 as it is, so that the steam heat of the generated wastewater can not be recycled. As a result, the energy consumption for heating the wastewater is increased, and the number of repeated cycles of wastewater circulating through the wastewater tank 70, the wastewater heating unit 50, and the chamber 10 is increased, thereby increasing the wastewater treatment time.

On the other hand, in general, a system that does not have a separate condenser and sucks the entire evaporation amount into the vapor compressor, reuses the evaporation amount as the heat source of the evaporator after the adiabatic compression is referred to as an MVR (Mechanical Vapor Precompression) system.

MVR generally has a disadvantage in that initial equipment cost is high, but it is suitable for large-volume evaporation concentration. MVR is difficult to use when high concentration wastewater, that is, scale-inducing substance, and saturated concentration are low, and is suitable for low concentration wastewater. The reason is that the boiling point rising (BPR) occurs due to the increase of precipitation crystals in the evaporation concentration process of the high concentration wastewater. Therefore, the vapor compression ratio should be adopted to be about 2 ~ 3 times higher than the normal compression ratio Therefore, the amount of power consumption compared to the normal evaporation amount is 2 to 3 times, which is disadvantageous in terms of operating cost.

Therefore, there is a great need to devise a system capable of treating high-concentration wastewater and a method of concentrating the evaporation, while taking advantage of the MVR capable of mass-processing while reducing energy consumption.

Korean Patent Registration No. 0870449

An object of the present invention is to provide a highly efficient evaporation and concentration system capable of effectively reducing thermal energy applied in an evaporation and concentration system for discharging a solid material by evaporating waste water by injecting thermal energy and capable of evaporating and concentrating high- And a method for concentrating the evaporation.

It is an object of the present invention to provide a wastewater treatment apparatus for treating a wastewater to be treated as a wastewater by first treating a solid matter using a chemical treatment or a filtering network;

A preheater for preheating pre-treatment water passed through the pre-treatment section using condensed water supplied from a condensing pump;

A first evaporator for evaporating the pretreated water through the preheater to produce a concentrated liquid;

A first circulation pump for transferring the concentrated liquid evaporated in the first evaporator to the first heat exchanger in the first evaporator;

A condenser circulating in the first evaporator is heated using steam of a motive steam supplied from the boiler supplied from the boiler and the steam supplied from the steam recompressor provided in the upper portion of the evaporator, A first heat exchanger;

A steam recompressor for re-compressing the steam generated in the first evaporator and returning it to the inside of the first evaporator;

A second heat exchanger for raising the concentrated liquid concentrated in the first evaporator;

A second evaporator for concentrating again the concentrated liquid heated by the second heat exchanger;

A second evaporator and a first heat exchanger are connected to supply a part of the steam generated in the second evaporator 810 to the second heat exchanger 820 or alternatively to a second evaporator and a steam aspirator A steam recovery pipe (A);

A steam ejector 840 for introducing vapor generated in the second evaporator and high temperature and high pressure motive steam generated in the boiler and supplied along the auxiliary steam supply line 101 to the second heat exchanger, ;

A second circulation pump for transferring a part of the concentrated liquid concentrated in the second evaporator to the second heat exchanger and recirculating a part of the concentrated liquid to the second evaporator;

A concentrating tank for storing a concentrate further concentrated in the second evaporator; And

And an enrichment pump for transferring the concentrated liquid from the second evaporator to the enrichment tank.

The first heat exchanger is provided with a plurality of heating tubes extending in parallel to the vertical direction, and a concentrate which has been subjected to the pretreatment water or one or more evaporation and concentration steps rides on the surface of the heating tube, Lt; / RTI >

Here, the steam recompressor may supply steam to the inside of the heating pipe from the end disposed at the inlet side of the heating pipe.

Here, when the steam pressure on the steam regenerating pipe connecting the first heat exchanger from the steam ejector is not higher than that in the first heat exchanger shell, the pressure regulating pipe C Lt; / RTI >

The steam pressure inside the second heat exchanger is higher than the steam pressure inside the first heat exchanger and the steam regeneration pipe (A), so that a part of the inner steam of the second heat exchanger flows into the pressure supplement pipe (C) So that steam on the steam regenerating line (A) flows into the first heat exchanger.

It is another object of the present invention to provide a method and a device for treating wastewater, comprising: a pretreatment step of precipitating suspended solids using a chemical agent or filtering suspended solids using a perforated mesh or a filter;

A step of introducing the pretreated water into the first evaporator and then introducing heat energy to concentrate the water while evaporating the water;

Compressing the vapor generated in the evaporation concentration step to an adiabatic compression process, raising the temperature of the vapor, and re-introducing the vapor into the first evaporator in which the evaporation concentration step is performed;

A post-evaporation concentration step of supplying a part of the concentrated liquid through the first evaporator to a second evaporator positioned at a rear end of the first evaporator, and then concentrating the concentrated liquid in the second evaporator; And

And a steam regeneration step of supplying a part of the steam generated in the second evaporator to the second evaporator and transferring a part of the steam to the suction side of the first evaporator or the vapor recompressor, .

Here, in the case of transferring some of the steam to the first evaporator in the steam regeneration step, the steam pressure on the steam regeneration line connecting the first heat exchanger from the steam ejector performing the steam regeneration may be supplied to the inside of the first heat exchanger shell There is a pressure supplement pipe (C) connecting the second heat exchanger and the steam regenerating pipe to the second heat exchanger,

The steam pressure inside the second heat exchanger is higher than the steam pressure inside the first heat exchanger and the steam regeneration pipe so that a part of the inner steam of the second heat exchanger flows into the steam regeneration pipe, And a steam regeneration step of allowing the steam to flow into the first heat exchanger.

According to the present invention, the MVR system capable of evaporating and concentrating the wastewater in a large capacity by using the steam recompressor can be advantageously used, and the conventional MVR system can overcome the limitation that it is not suitable for the wastewater treatment at a high concentration.

Particularly, according to the present invention, high-concentration wastewater treatment can be performed while using a steam ejector that increases the flow rate so as to be suitable for treatment of high concentration wastewater, and at the same time, the steam, which can not flow into the steam ejector, The energy consumption efficiency can be improved remarkably.

In addition, when the pressure of the steam which can not flow into the steam ejector is low, the steam of the second heat exchanger is partially mixed to increase the steam pressure, so that the steam can be smoothly introduced into the first evaporator.

In addition, in the conventional MVR system, additional concentration of the downstream end of the dryer is required. However, in the present invention, the steam fed to the first evaporator at the front end is supplied from the steam recompressor and supplied to the downstream steam injector, It is not necessary to further concentrate the subsequent stage such as a separate dryer by circulating and concentrating the vapor in each evaporator.

1 is a view showing an example of a wastewater treatment apparatus disclosed in Korean Patent Registration No. 0870449.
2 is a schematic view showing a configuration of an embodiment of an evaporation and concentration system with improved energy consumption efficiency according to the present invention.

The term " concentrate "refers to wastewater that has been subjected to evaporation concentration in an evaporator or wastewater that has been circulated through an evaporator. The term " pre-treatment water "Quot; concentration "refers to the degree to which the wastewater is condensed as it evaporates. In describing the present invention, the term "steam" is used to refer to both motive steam generated in a boiler or vapor generated in an evaporation concentration process in an evaporator.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a view showing an embodiment of an evaporation concentration system according to the present invention.

2, the evaporation and concentration system according to the present invention includes a first preheater 505, a supply tank 600, a second preheater 605, a first evaporator 710, a first circulation pump 730 A second evaporator 810, a second heat exchanger 820, a second circulation pump 830, and a steam ejector 840. The first heat exchanger 720, the vapor recompressor 740, the second evaporator 810, the second heat exchanger 820,

The first preheater 505 partially branches the steam from the inlet side of the first heat exchanger 720 to preheat the pretreated water to be concentrated. Herein, the pretreated water refers to wastewater in which solids, suspended matters, and the like in the wastewater are firstly removed by using a chemical method such as chemical treatment or the like using a physical method using wastewater to be treated.

The supply tank 600 stores the pre-treatment water passed through the first pre-heater 505 before supplying the pretreated water to the first evaporator 710.

The second preheater 605 preheats the pre-treatment water flowing into the first evaporator 710 from the supply tank 600 by using the condensed water supplied from the condensing pump.

The first evaporator 710 is circulated through the first pre-heater 505 and the first evaporator 710 after being circulated through the first evaporator 710, and is concentrated by evaporating the concentrated liquid. Herein, the concentrated liquid refers to wastewater which is concentrated through the first evaporator 710 by the pretreated water. The level of the concentrated liquid in the first evaporator 710 is kept constant. A first variable valve 660 is disposed between the supply tank 600 and the second pre-heater 605 and the first evaporator 710 to regulate the inflow amount of the pretreated water into the first evaporator 710, The water level in the evaporator 710 can be maintained.

The first circulation pump 730 conveys the concentrated liquid evaporated in the first evaporator 710 to the first heat exchanger 720 in the upper portion of the first evaporator 710 and supplies the concentrated liquid to the first evaporator 710 710). The first circulation pump 730 does not recycle all of the concentrated liquid concentrated in the first evaporator 710 into the first evaporator 710 but recirculates only some of the concentrated liquid according to the conditions described below.

The first heat exchanger 720 is disposed above the first evaporator 710 to heat the concentrate circulating the first evaporator 710.

The steam recompressor 740 adiabatically compresses the steam generated in the first evaporator 710 and puts it into the first heat exchanger 720 again. The steam supplied from the boiler through the auxiliary steam supply line 101 flows into the first heat exchanger 720 together with the steam supplied from the steam recompressor and is used as an evaporation heat source. The vapor compressor 740 used in the present invention is a mechanical vapor recompressor (MVR), which functions to adiabatically compress the vapor generated in the first evaporator 710 and recycle it into the first evaporator 710 . In this process, the temperature of the steam increases from 5 ° C to 15 ° C.

The second heat exchanger 820 increases the concentration of the concentrated liquid in the first evaporator and is connected to the second evaporator 810.

The second evaporator 810 functions to concentrate the concentrated liquid heated in the second heat exchanger 820 again. A portion of the vapor generated in the second evaporator 810 is sucked into the steam ejector 840 and the remaining portion of the vapor is supplied to the heat source of the first heat exchanger 720.

The steam ejector 840 mixes motive steam supplied from some of the boilers generated in the second evaporator 810 and supplies the mixed steam to the heat source of the second heat exchanger. Steam from the boiler is supplied to the steam ejector 840 through the auxiliary steam supply line 101.

The second circulation pump 830 transfers part of the concentrated liquid concentrated in the second evaporator 810 to the second heat exchanger 820 and recycles the second evaporator 810 to the second evaporator 810.

On the other hand, the concentrated liquid in the second evaporator 810 is transferred to the concentration tank by the concentration pump 835 and stored.

Hereinafter, the operation of the evaporation concentration apparatus according to the present invention having the above-described structure will be described.

The present invention maintains the advantage of evaporating and concentrating a large amount of wastewater at low cost through the first concentration in the conventional MVR system. Further, by using the steam ejector 840, the flow rate in the heat transfer pipe of the heat exchanger is circulated at a constant speed or more, thereby preventing scale adhesion and enabling treatment of high concentration wastewater. That is, the high concentration wastewater can be treated in a large capacity.

In more detail, the first evaporator uses the steam supplied by the vapor recompressor as a heat source, and the second evaporator 810 supplies steam through the steam ejector 840 to the supersonic solution , It is possible to treat a large amount of wastewater even in the case of high concentration wastewater containing a large amount of scale-inducing substances, and at the same time, additional concentration of the downstream end of a dryer or the like is unnecessary.

The steam ejector 840 sucks about 50% (B) of the steam generated in the second evaporator 810 and mixes it with motive steam, and then uses the steam as the heat source of the second evaporator 810 . The remaining 50% of the steam, which has not been sucked into the steam ejector 840, flows into the condenser where the additional cooling water is circulated and is condensed, thereby releasing the steam to the atmosphere through the cooling tower.

However, the present invention greatly improves the efficiency of the system by recovering the heat amount of the corresponding 50% of the steam radiating to the atmosphere. That is, the remaining steam (A) that has not been sucked by the steam ejector 840 among the steam vapor evaporated in the second evaporator 810 is absorbed as the heat source of the first evaporator at the previous stage, and the heat is used.

In this case, both of the method (first route of FIG. 2) or the method of introducing the gas into the first evaporator (second route of FIG. 2) is possible.

The pressure in the steam regeneration duct A may be lower than the pressure in the first heat exchanger and the first evaporator shell due to the pressure condition. In this case, in order to ensure a sufficient pressure (first heat exchange The pressure in the second heat exchanger 820 of FIG. 2 may be increased by mixing some of the steam in the second heat exchanger 820 of FIG.

Or by regulating the flow rate of the steam regeneration pipe (A) to flow into the suction side of the vapor recompressor at the upstream side, thereby reducing the energy consumption by recycling the steam without considering the steam pressure difference.

The high-efficiency evaporation concentration method of the present invention, which corresponds to the method of operating the evaporation concentration system described above, is as follows.

The evaporation concentration method according to the present invention includes a pre-treatment step, a shear-evaporation concentration step, a vapor recompression step, a post-evaporation concentration step and a steam regeneration step.

In the pretreatment step, the waste water is precipitated with a chemical agent, or the floating matter is filtered using a perforated network or a filter.

In the shear-evaporation concentration step, the pre-treatment water is introduced into the first evaporator and then heat energy is applied to concentrate the water while evaporating.

The steam recompression step is a step in which the steam generated in the shear-end evaporation step is stepped up and raised to an adiabatic compression step, and then re-introduced into the first evaporator in which the evaporation step is performed.

The post-evaporation concentration step is a step of supplying a part of the concentrated liquid through the first evaporator to the second evaporator 810 positioned at the rear end of the first evaporator, and then concentrating the concentrated liquid in the second evaporator 810 .

In the steam regeneration step, a part of the steam generated in the second evaporator 810 is sucked together with the steam supplied from the boiler by the steam ejector 840 and is supplied to the second evaporator 810 again, 1 heat exchanger 720 to the high temperature steam inlet side or the vapor recompressor 740 suction side.

The steam pressure on the steam regenerating line A connecting the first heat exchanger from the steam ejector 840 is lower than the steam pressure on the steam regenerating line A connecting the first heat exchanger 720 to the first heat exchanger 720. [ There may be a case where the inner diameter of the shell 720 is not high. In order to solve this problem, a pressure supplement pipe (C) for connecting the second heat exchanger (820) and the steam recovery pipe (A) is disposed. The steam pressure inside the second heat exchanger 820 is higher than the steam pressure inside the first heat exchanger and the steam regenerating pipe A so that the steam pressure in the second heat exchanger 820 A portion of the steam may be introduced through the pressure supplement pipe (C) so that steam on the steam regeneration duct (A) may be introduced into the first heat exchanger. A pressure replenishing step utilizing this pressure replenishing line (C) may be further included in the steam regeneration step.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit of the invention.

101: Auxiliary steam supply line
505: first preheater 600: supply tank
605: second preheater 660: variable valve
710: First evaporator
720: heat exchanger 725: specific gravity meter
730: first circulation pump 735: first enrichment pump
740: steam recompressor 750: enrichment tank
780: Condensate pump
790: Vacuum pump 810: Second evaporator
820: second heat exchanger 830: second circulation pump
835: Enrichment pump 840: Steam ejector

Claims (6)

delete delete delete A wastewater pretreatment unit for firstly removing solid matter by using a chemical treatment or a screening wastewater to be treated;
A preheater 605 for preheating the pretreated water using condensed water supplied from a condensing pump 780;
A first evaporator 710 for evaporating the pretreated water through the preheater 605 to produce a concentrated liquid;
A first circulation pump 730 for transferring the concentrated liquid evaporated in the first evaporator 710 to the first heat exchanger 720 on the first evaporator 710;
The first evaporator 710 is disposed above the first evaporator 710 and uses steam of a motive steam supplied from the boiler through the auxiliary steam supply line 101 as a heat source, A first heat exchanger 720 for heating the concentrate circulating in the first heat exchanger 720;
A steam recompressor 740 for re-compressing the steam generated in the first evaporator 710 by an adiabatic compression process, raising the pressure, raising the temperature, and returning the steam to the inside of the first evaporator 710;
A second heat exchanger (820) for heating the concentrated liquid concentrated in the first evaporator;
A second evaporator 810 for concentrating the concentrated liquid heated in the second heat exchanger 820 again;
A second evaporator and a first heat exchanger are connected to supply a part of the steam generated in the second evaporator 810 to the second heat exchanger 820 or alternatively to a second evaporator and a steam aspirator A steam recovery pipe (A);
A steam ejector 840 for introducing vapor generated in the second evaporator and high temperature and high pressure motive steam generated in the boiler and supplied along the auxiliary steam supply line 101 to the second heat exchanger, ;
A second circulation pump 830 for transferring a part of the concentrated liquid concentrated in the second evaporator 810 to the second heat exchanger 820 and recirculating a part of the concentrated liquid to the second evaporator 810;
A concentrating tank for storing the concentrated liquid further concentrated in the second evaporator 810; And
And a concentration pump (835) for transferring the concentrated liquid from the second evaporator (810) to the concentration tank,
The steam regenerating line A connects the first heat exchanger 720 from the second evaporator 810,
A pressure replenishment line connecting the second heat exchanger 820 and the steam regenerating line A in preparation for a case where the steam pressure on the steam regeneration line A is not higher than that in the shell of the first heat exchanger 720, Further comprising a conduit (C)
The steam pressure inside the second heat exchanger 820 is higher than the steam pressure inside the first heat exchanger and the steam regenerating pipe A so that a part of the inner steam of the second heat exchanger 820 is pressurized by the pressure Flows into the steam regenerating line (A) through the supplementary line (C)
So that steam on the steam recovery pipe (A) flows into the first heat exchanger. delete delete

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