KR880001494B1 - Evaporation-concentration method by emchanical compression - Google Patents

Abstract

Waste fluid coming from rayon or staple fiber spinning bath is evaporated and concentrated by mechanical compression so as to recover and reuse acid. Waste fluid is preheated in a heat exchanger (4) disposed upstream of a vacuum gas-releasing tube (1) in which 1-3 wt.% of waste fluid is evaporated, and then concentrated in an evaporator (10). The evaporated steam from the evaporator flows to an alkali scrubber (11) so as to be purified by alkali purifier, and then the purified steam is sucked into a turbo-compressor (23) in which it is compressed and heated to be used as a heating source of the evaporator. A steam ejector (2) is disposed downstream of the gas-releasing tube.

Description

Mechanical Compression Evaporative Concentration Method

BRIEF DESCRIPTION OF THE DRAWINGS Fig. Is a flow sheet of an embodiment for explaining the present invention.

* Explanation of symbols for main parts of the drawings

1: vacuum degassing pipe 2: steam ejector

4: heater 7: evaporation tube

8 heating tube 10 evaporator

11: alkali scrubber 12: packed column

23: mechanical compressor 24: heat exchanger

浴)산증발 농축방법에 관한다.The present invention is a spinning bath for pickling (picring acid) waste liquid and various waste acids such as rayon, staple fiber plant and steel mill by mechanical compression method.

I) Regarding acid evaporation concentration method.

For example, when evaporating and concentrating to recover and reuse the radiation bath acid discharged from a spinning process in a rayon or soup factory, the vaporized steam generated in the evaporation tube is compressed and heated by a vapor ejector as a method of thermal energy economy of the evaporator. By returning this to the heating tube and using it as a heating source for the evaporated liquid, a self-vapor compression type evaporative concentration method which uses the latent heat of the generated steam repeatedly is widely used. However, in the self-steam compression method using the steam ejector, the steam generated for compression is reused as a steam for heating by compressing the generated steam with the steam ejector, so most of the steam used for the compression is surplus steam and is not economical, and energy of In terms of saving, the latent heat of the generated steam is repeatedly reused by compressing the evaporated steam generated in the evaporation tube by using a mechanical compressor such as a rotary blower or a turbo compressor, increasing the enthalpy and using it as a heated steam. A mechanical compression method is proposed.

However, steam generated when the sulfuric acid solution containing about 10% by weight of sulfuric acid and zinc sulfate containing inorganic sulfuric acid as an inorganic gas, such as rayon and radioactive acid in a soup plant, is concentrated by mechanical compression. Due to the acid mist containing acidic gas and trace mineral salts, the efficiency is reduced in a short time due to the attachment of solids to the casing, rotor, impeller, etc. of mechanical compressors, wear, corrosion, etc. Enforcement is almost difficult.

Considering this phenomenon, the present invention has been studied. The present invention is extremely thermally efficient for producing a sulfuric acid solution dissolving an acid gas and an inorganic salt, in particular, rayon and a soup plant, and also has excellent equipment and maintenance costs. To provide an inexpensive mechanical compression evaporative concentration method.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

(1) is a vacuum degassing tube incorporating a mist catcher, (2) is a steam ejector which maintains the inside of the degassing tube (1) at a predetermined vacuum degree, and the discharge steam is passed through the pipe (3) as a heating source. It is introduced into (4) and is introduced into the heater (4) through the pipe (5). The stock solution heated by heat-exchanging with the stock solution preheated in the heat exchanger 24 to be described later is configured to be introduced into the degassing pipe 1 through the pipe 6.

In this embodiment, a wet wall type degassing tube is used, but other types such as a filling type can also be used. Moreover, although a multipipe type was used as a heater, the other type can also be used. (7) is an evaporation tube, (8) is a multi-pipe type heating tube, (9) is a forced circulation pump, and constitutes an evaporation apparatus (10).

In this embodiment, a forced circulation type in which a heating tube is directly connected to the lower part of the evaporation tube is used, but other types of evaporation apparatuses, such as natural circulation, external heating pipe type, liquid film rising, liquid film falling type, and the like, may also be used.

The alkaline scrubber 11 includes a pump 15 for circulating a washing liquid (alkaline liquid) via a packed tower 12 filled with a recipe ring, a liquid reservoir 13 disposed below the pipe, and a pipe 14, And a liquid distributor 16, and a heating pipe 17 is installed in the liquid reservoir, and is connected to the pipe 20 via a valve 19 interlocked with the temperature detector 18 of the cleaning liquid flowing in the pipe 14. Heating steam is introduced to heat the cleaning liquid to a predetermined temperature. Reference numeral 21 denotes an alkali aqueous solution introduction pipe, and 22 denotes a mist catcher.

流)의 충전탑을 사용했으나 스프레이탑, 붕단탑(棚段塔), 젖은 벽탑 등 다른 형식의 기액접촉장치도 사용할 수있다. (23)은 기계식 압축기이고 터어보식 압축기를 사용했으나 로우터리블로어등, 다른 형식의 기계식압축기를 사용해도 좋다. (24)는 열교환기이고, 파이프(25)로부터 펌프(26)를 거쳐 도입되는 증발장치(10)로부터의 농축액을 가열원으로하여 파이프(27)에서 도입되는 원액을 예열한다.In this embodiment, co-current flow as an alkali scrubber (

A flow packed tower was used, but other types of gas-liquid contacting devices such as spray towers, mandarin towers, and wet wall towers can also be used. (23) is a mechanical compressor and a turbo compressor is used, but other types of mechanical compressors, such as a rotary blower, may be used. Reference numeral 24 denotes a heat exchanger and preheats the stock solution introduced in the pipe 27 by using the concentrated liquid from the evaporator 10 introduced from the pipe 25 via the pump 26 as a heating source.

In this embodiment, a plate type is used, but other types such as a pipe type are also used. In the present embodiment, the concentrated liquid is used as the heat source. However, the heat efficiency can be further improved by using the heat exchanger having the heat source as the heat source 4 and the drain discharged from the heat pipe 8 again.

In the present invention, the raw liquid is introduced into the heat exchanger 24 in the pipe 27, and the raw liquid preheated by heat exchange with the concentrate from the evaporator 10 introduced from the pipe 25 via the pump 26 is transferred to the pipe. Passed by (5) to the heater (4). On the other hand, the concentrated liquid cooled by heat exchange with the stock solution at a predetermined temperature is transferred to a crystallization apparatus (not shown), and the precipitated inorganic material is separated, and then the liquid concentration is adjusted and reused as a radiation bath.

The stock solution introduced into the heater 4 is heat-exchanged with the discharge steam of the steam ejector 2 in the heater, heated above the boiling point, and then introduced into the degassing pipe 1 through the pipe 6 to obtain 1.0-3.0 weight of the stock solution. Flash evaporation of% and at the same time release most of the acidic gas dissolved in the stock solution, which is then passed through pipe 28 to evaporator 10. The evaporated vapor generated in the degassing pipe in the meantime is sucked, compressed and heated by the steam ejector 2 and reused as a heat source of the heater 4, and the drain is passed from the pipe 29 through a pump not shown in the drawing to the outside of the system. It is taken out.

As described above, in the present invention, 1.0-3.0% by weight of the stock solution is flash-evaporated in the degassing tube, whereby the acid gas dissolved in the stock solution can be easily released as a medium. There are differences depending on the composition of the stock solution, but in general, when the evaporation amount is less than 1.0% by weight, the degassing effect is small. When the evaporation amount is more than 3.0% by weight, the steam ejector of the vapor ejector for compressing the evaporative vapor increases, which is separated from the thermal economy. In this way, by sufficiently discharging and removing the acid gas contained in the stock solution, the acid gas contained in the vapor generated from the evaporator of the next stage is reduced, thereby reducing the load of the late alkali scrubber 11 and improving its removal efficiency. And the removal of acid gases in the steam is carried out completely. In addition, since part of the stock solution has evaporated in the degassing pipe, the load on the evaporator and the mechanical compressor can be reduced accordingly.

The raw liquid conveyed through the pipe 28 to the evaporator 10 is introduced into the heating tube 8 by joining the circulating liquid circulating through the pump 9 in the pipe 30 and introduced into the heating tube 8 so as to ascend the inside of the heat transfer pipe. Heat exchanged with the steam introduced from 23, the heated and boiled liquid is ejected into the evaporation tube 7, the generated steam is passed through the pipe 31 to the alkali scrubber 11. At the same time, the drain of the heating tube 8 is taken out of the pipe 32 through the pump not shown in the drawing. On the other hand, a part of the internal liquid of the evaporation tube 7 is forcedly circulated by the pump 9 via the pipe 30, while the other part is taken out as a concentrated liquid from the pipe 25 via the pump 26 through the heat exchanger ( 24).

In addition, the pipes 38 and 34 are bleed pipes and are connected to a vacuum generator (not shown) to discharge the non-condensable gas while maintaining the inside of the heater 4 of the heating tube 8 at a predetermined vacuum degree. do.

The vapor generated in the evaporation tube 7 introduced into the alkali scrubber 11 through the pipe 31 is in parallel contact with the alkaline cleaning liquid circulated in the packing material in the liquid distributor 16 while descending the packed column 12. Trace acid mists and acid gases contained in steam are absorbed and removed. During the movement, an aqueous alkali solution (10-20 wt% aqueous solution of caustic soda) is continuously injected into the pipe 21, and a part of the cleaning solution for dissolving the reaction product is continuously discharged from the pipe 35 at the same time, and the temperature detector ( The heating steam is introduced from the pipe 20 via the valve 19 which cooperates with 18), and the cleaning liquid is maintained at the same temperature as the saturation temperature of the introduced steam. Reference numeral 36 denotes the drain discharge pipe. In this way, the acid mist and the evaporated vapor in which the acid mist and the acid gas are removed without any latent heat loss by contacting and washing with an alkaline cleaning liquid at a temperature substantially equal to the saturation temperature are again removed by the cleaning liquid mist accompanying the mist catcher 22. Aspirated by the turbo compressor 23 through 37, compressed and heated to become superheated steam, passed through the pipe 38 to the desuperheater 39, and brought into contact with hot water sprayed through the pipe 40 to warm it. The temperature is reduced and introduced into the heating tube 8 through the pipe 41 as saturated steam.

42 is a temperature detector, part of the superheated steam flowing through the pipe 38 by operating the valve 43 to interlock by detecting the temperature of the steam flowing through the pipe 37 near the intake hole of the turbo compressor 23 Is led to the pipe 37 through the pipe 44 to maintain the suction steam temperature of the compressor at about 5 ℃ higher than the saturation temperature and to prevent corrosion of the impeller of the compressor by the drain. Reference numeral 45 denotes a temperature detector, which operates a valve 46 which detects the temperature of steam flowing through the pipe 41 in the vicinity of the temperature reducer 39 and interlocks with it, and introduces hot water from the pipe 40 to overheat as described above. Warm steam to saturated steam. (47) is a steam inlet pipe for star art, and supplementary steam is supplied from this pipe when the F / D (stock supply / evaporation amount) is large and the heating steam is insufficient. Reference numeral 48 denotes a steam introduction pipe for driving the steam ejector 2.

It is concentrated by evaporation by the above continuous operation. In the present embodiment, the heating pipe 17 for adjusting the temperature of the cleaning liquid is provided in the alkali scrubber. However, since the steam generated in the evaporation tube due to the boiling point rises due to overheating steam, such a heating pipe is increased when the boiling point increases. There is no need to install it.

As described above, in the present invention, 1.0-3.0% by weight of the stock solution is flash-evaporated in a vacuum degassing tube, which is used as a medium to remove most of the acidic gas in the stock solution, thereby reducing the load of the alkaline scrubber and improving the removal efficiency. And the vapors from which the acid gas and the acid mist are completely removed are sucked into the mechanical compressor, thereby preventing the attachment of the solids to the casing, the rotor, and the impeller of the compressor, abrasion, corrosion, etc., and at the same time, the corrosion of the heating tube 8 Almost no maintenance is required and maintenance costs can be extremely reduced. In the present invention, the steam generated in the vacuum degassing tube is sucked into the vapor ejector, compressed and heated up, and reused as a heating source of the heater 4 to recover latent salts of the discharge steam, and the concentrate is transferred to the heat exchanger 24. It is configured to recover the sensible heat, and the steam generated in the evaporation tube 7 is washed with an alkali cleaning liquid at a temperature approximately equal to its saturation temperature and the acidic substances are removed, so that the latent heat of the steam is not lost. In addition, since the steam from which the acidic gas has been completely removed is supplied to the heating tube 8, the overall heat transfer coefficient of the heating tube is not lowered and the thermal efficiency is extremely good. In the present invention, by evaporating 1.0-3.0% by weight of the stock solution in the vacuum degassing tube, the load on the evaporator and the mechanical compression device can be reduced accordingly.

Claims (1)

After preheating the stock solution by heat exchange with the concentrate, a heater is placed at the front end, and a steam ejector is installed at the rear end, and the discharged steam of this steam ejector is led to a vacuum degassing pipe configured to use as a heating source of this heater, and the total amount is 1.0-3.0 weight. % Is evaporated, then transferred to an evaporator, concentrated to a predetermined concentration, and the evaporated steam is introduced into an alkali scrubber, washed with an alkaline scrubbing liquid at a temperature substantially equal to the saturation temperature of the evaporated steam, followed by a mechanical compressor. A method for mechanically compressing evaporative condensation of pickling (peaking acid) waste liquids and various waste acids such as rayon, soup spinning bath and steel mill, characterized in that they are compressed, heated and used as a heating source of the evaporator.

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