TWI558667B - Apparatus and method for the production of solution by concentrating volatile substances from steam stripping of wastewater - Google Patents

Description

Method and device for preparing volatile substance solution by steam stripping wastewater concentration

The invention relates to a mass transfer system for recovering volatile substances in water by steam stripping, which can perform a multi-stage (stage) steam-solution mass transfer process using a general rotary packed bed or a sandwich rotary packed bed to recover The volatile matter in the wastewater is converted into a high concentration solution containing the volatile material.

Industrial wastewater or residential sewage often contains a large amount of volatile substances, such as ammonia nitrogen, hydrogen chloride and volatile organic compounds (VOCs). Common volatile organic compounds include methanol, ethanol, isopropanol, formaldehyde, and acetaldehyde. , acetone, formic acid and acetic acid. Common treatment methods for removing these volatile substances include adsorption, biological treatment, air blowing and oxidation, but these methods usually have disadvantages such as high operating cost or poor removal effect. Among them, air blowing is a physical method, which transfers volatile substances from the aqueous phase to the gas phase, and then uses other solutions for absorption and concentration. The operating cost is relatively low, but secondary pollutants may be generated; steam may be used. Instead of air for stripping, a concentrated solution containing volatile substances can be obtained after condensation, but if a conventional stripper or distillation column is used, high steam usage is required, and the concentration of volatile substances is treated. Low wastewater, it is not easy to obtain high concentration and economic value of the recovery solution.

The volatility of volatile pollutants is usually expressed by Henry's law (H). The higher the Henry's constant, the more volatile it is. It is usually expressed by the following equation: P _i =H _i C _L,i

Where P _i is the gas phase partial pressure (atm) of the substance _i , C _L,i is the concentration of the substance i in the solution (mol/m ³ ), and H _i (atm.m ³ /mol) is the substance of Henry constant.

The other form of the Henry's constant of substance i is H _C,i :C _G,i =H _C,i C _L,i

Wherein C _G,i is the concentration (mol/m ³ ) of the substance i in the gas phase, and the unit of H _C,i is (mol.m ³ )/(mol.m ³ ).

H _C,i =H _i /(RT)

Where R is the ideal gas constant and T is the absolute temperature.

Assuming that the wastewater flow rate is Q _L (m ³ /s), the theoretical minimum minimum gas flow Q _G (m ³ /s) is Q _L /H _C to completely remove the i material from the wastewater to the gas phase. Suppose that the substance i is completely transported from the wastewater to the gas phase and the gas phase is only vapor and substance i. According to the ideal gas equation, the minimum Moir flow rate required for steam is theoretically , mol / s) can be calculated as follows

Where P is the pressure (atm) of the gas phase.

If the concentration of substance i in the raw wastewater is not high, the Mohr flow rate of water in the wastewater ( , mol/s) is approximately Q _L ρ _w /M _w , where ρ _w and M _w are the density of water (about 1000 kg/m ³ ) and the molecular weight (1.8 x 10 ^-2 kg/mol), respectively. If the substance i can be completely transported from the wastewater to the vapor phase, the concentration factor is theoretically / In direct proportion.

Generally, the P value of the operating environment is close to 1 atm and the temperature is about 100 ° C. From the above formula, the H value of the substance i at 100 ° C is greater than 1.8 x 10 ^-5 atm. m ³ /mol, in theory, has the feasibility of steam concentration. Table 1 shows the values of the H value and the solubility in water of a common volatile substance at around 25 ° C. However, the H value at 100 ° C is usually about 10 to 20 times that at 25 ° C. Therefore, many volatile substances are known. It has the feasibility of carrying out steam concentration.

General industrial production and agriculture, including aquaculture and animal husbandry, may produce ammonia nitrogen wastewater. According to the analysis of the amount and concentration of ammonia nitrogen wastewater emitted by the Taiwan Industrial Technology Research Institute for high-tech industries, the ammonia nitrogen emitted by the semiconductor industry's 12-inch wafer fab. The water volume of the wastewater is about 1000 CMD (m ³ /day) and the concentration is about 0.2 wt.%, and the ammonia nitrogen wastewater of the Light-Emitting Diode (LED) factory has a water volume of about 30 CMD and a concentration of about 2 wt. %, the amount of ammonia nitrogen wastewater in the ammonia-copper process of the Printed Circuit Board (PCB) industry is about 5 CMD and the concentration is about 7 wt.%, and the amount of ammonia-nitrogen wastewater in the solar photovoltaic industry is about 50 CMD. The concentration is about 1 wt.%. In summary, Taiwan's high-tech industry's ammonia nitrogen wastewater discharge is close to 1 million tons per year and the concentration is about 1wt.%.

The ammonia nitrogen in the wastewater refers to a compound in the form of ammonia (NH ₃ ) or ammonium ion (NH ₄ ⁺ ). The ammonia nitrogen is toxic to aquatic organisms, and the ammonia nitrogen is also decomposed by microorganisms to consume dissolved oxygen in the water body, resulting in water body. Black or stinky. Ammonia nitrogen can be oxidized by microorganisms to nitrite nitrogen in the presence of sufficient oxygen to decompose into nitrate nitrogen. In a natural environment, nitrite nitrogen may combine with proteins to form nitrosamines that are carcinogenic and teratogenic, and endanger human health. On the other hand, ammonia nitrogen can provide a nitrogen nutrient source for the growth of algae and aquatic plants, which can lead to the proliferation of certain aquatic plants such as seaweed and aquatic plants. In addition, ammonia-nitrogen wastewater can also cause damage to certain industrial equipment, such as corrosion of certain metals such as copper and the proliferation of microorganisms in water pipelines and water equipment to form bioscale, leading to blockage of pipelines and equipment. It can be seen that ammonia nitrogen can cause serious harm to the water environment. How to effectively treat ammonia-containing wastewater to reduce its impact on the water environment has become an important issue at present.

At present, there are several methods for removing ammonia nitrogen from wastewater, including (1) stripping method: using the gas-liquid mass transfer effect under alkaline water quality (high pH value), the air is introduced into the wastewater containing ammonia nitrogen. Ammonia is extracted from the gas in the aqueous phase. Generally, the stripping tower is used for the separation, and the separated gaseous ammonia can be absorbed by the acid, but the secondary pollutant may be derived; (2) the chemical precipitation method: adding magnesium ions under a certain pH condition ( Mg ²⁺ ), phosphate (HPO ₄ ^3- ) and NH ₄ ⁺ can form a precipitate of magnesium ammonium phosphate (MgNH ₄ PO ₄ ), which separates the ammonium ions from the water. The main problems of the chemical precipitation method are the large amount of precipitant and the high cost of magnesium salt. In addition, the precipitated particles formed are fine or floccules are formed, which has certain difficulty in solid-liquid separation; (3) Ion exchange method: It mainly uses the ion exchange program to replace and remove the ammonium ions in the wastewater. However, if the wastewater contains oxidizing substances, it may damage the ion exchange resin and cause the treatment efficiency to decrease. In addition, there are problems such as regeneration and disposal of the ion exchange resin. In order to increase the processing cost; (4) Reverse osmosis method: the reverse osmosis membrane is used to concentrate the ammonia ions, and the reverse osmosis membrane can block the ammonia ions to produce low-concentration ammonia nitrogen to produce water, but the installation cost is high and the reverse osmosis membrane pore size Xiaoyi reduces the water production rate due to clogging of impurities or organic matter in the wastewater, and may also damage the reverse osmosis membrane due to other chemical substances in the wastewater, thereby increasing the difficulty of operation and increasing the treatment cost; (5) Biological treatment: appropriate cultivation in wastewater The microorganism removes ammonia nitrogen by the metabolism of microorganisms. The biological treatment nitrogen removal method mainly comprises two steps. First, the ammonia nitrogen is oxidized to nitrogen nitrate by the ammonia oxidizing bacteria and the nitrous acid oxidizing bacteria, and then the nitrogen nitrogen is reduced to nitrogen by the denitrifying bacteria to achieve the removal effect. Although biological nitrogen removal is one of the commonly used methods, it has a large footprint and has operational difficulties for high-concentration or intermittent ammonia-nitrogen wastewater, as well as problems and costs of subsequent sludge treatment; and (6) thin film distillation Technology: The thin film distillation technology flows through the porous and hydrophobic film side after increasing the temperature of the wastewater, and the other side of the film is circulated with a low-temperature acidic solution, and the ammonia nitrogen vapor pressure difference between the fluid contact surfaces on both sides of the film is the driving force, so that the ammonia nitrogen vapor The molecules are absorbed into the ammonium salt-containing liquid through the pores of the film and transported from the high-temperature wastewater side to the low-temperature acidic solution side, but similarly there may be a problem of secondary pollutants being derived.

Isopropanol is commonly used in paints, thinners, coatings, detergents, surface sterilization, food processing plants and other related industries. Isopropanol is the largest waste organic solvent in current semiconductor processes. Isopropanol is also used as a solvent and equipment cleaner in flexo, lithographic and gravure printing processes. In addition, the photovoltaic industry will also produce a large amount of organic wastewater containing isopropanol in the cleaning stage process. Isopropanol emissions not only pollute the environment, but because isopropyl alcohol is a photochemical oxidant that forms ozone when exposed to sunlight, irritating the eyes and respiratory system, endangering human health and plant growth.

Hypergravity technology is an innovative technology that enhances the mass transfer process of gases and liquids. The main feature is that in the centrifugal acceleration environment of tens to hundreds of times the Earth's gravitational field, the liquid will be dispersed at the surface and pores of the filler. The tiny droplets, liquid film and liquid filament carry out the flow from the inner radial outer diameter, increasing the specific surface area of the gas-liquid contact. Also because of gas and liquid The micro-violent mixing effect can increase the specific surface area of the gas-liquid contact and reduce the mass transfer resistance between the gas and liquid, thereby achieving the purpose of increasing the gas-liquid mass transfer rate and reducing the reactor volume. Compared to conventional steam-liquid contact devices, such as stripping columns or distillation columns, the mass transfer rate per unit volume of a supergravity reactor can be increased by tens to hundreds of times, thus significantly reducing the equipment volume required for the reactor. It can be used to treat large volumes of wastewater while reducing steam usage.

The recovery solution containing volatile substances generally must reach a higher concentration value in order to have the economic value of subsequent purification and reuse. For example, the concentrated ammonia water concentration should be above 20 wt.%, and it is usually suitable for further purification of ammonia water for industrial conversion. At present, for ammonia nitrogen wastewater with low concentrations such as hundreds or thousands of mg/L, it is still necessary to develop a novel treatment process to convert to a high concentration (>20 wt.%) of ammonia water. By the same token, if the volatile organic substances (such as isopropyl alcohol) are to be recycled, the recovered organic matter solution needs to reach tens of wt.% or more, and the economic benefits of subsequent purification and reuse can be achieved.

The invention adopts steam stripping to recover volatile substances in waste water, has the advantages of high recovery efficiency, simple process and small occupied area, and can effectively reduce the content of volatile substances in waste water to reduce environmental load and achieve resource recycling. Reuse and increase the economic value of the recovered solution.

The invention provides a method for preparing a volatile substance by steam stripping wastewater, which comprises introducing steam and volatile matter-containing wastewater into a rotary packed bed device, and the steam and the waste water are filled in the rotation The vapor-liquid mass transfer procedure is performed in the bed apparatus; and the gas leaving the rotating packed bed apparatus is condensed and collected into a solution containing a volatile substance.

The present invention further provides a sandwich type rotating packed bed device which can replace the rotary packed bed device used in the above method, the device comprising an inner layer casing having a gas opening and provided with a a steam inlet pipe and a liquid discharge pipe; An outer casing defining a space between the outer casing and an outer casing, wherein the outer cavity is in communication with the gas opening and is provided with a fluid outlet, wherein the outer cavity covers the inner layer a housing and the gas opening; a rotating packed bed disposed in the inner casing, the rotating packed bed comprising a cavity filled with a solid filling member; a rotating mandrel extending through the inner casing Coupling with the rotating packed bed to rotate the rotating packed bed relative to the inner casing; and a liquid passage pipe passing through the gas opening and having a liquid discharge opening The liquid opening is disposed in an intermediate passage; the introduced steam will sequentially pass through the rotating packed bed, the gas opening, the outer cavity, and the fluid outlet connected to the external line; wherein the steam is passed into the tube, the liquid A discharge tube and the liquid passage tube pass through the outer casing.

In the present invention, the form of the volatile matter recovery process can be determined based on the initial concentration of the volatile matter in the wastewater and the target concentration of the recovered solution.

The present invention provides a sandwich type rotary packed bed apparatus and a method for preparing a solution containing a high concentration of volatile substances by steam stripping wastewater, which will be further understood by the following description of the embodiments and the accompanying drawings.

Other aspects and specific embodiments are also contemplated by the present invention. The above summary of the invention and the following embodiments are not intended to limit the invention to any particular embodiments.

A‧‧‧ Wastewater containing volatile substances

B‧‧‧Adjustment

C‧‧‧Steam

D‧‧‧Outflow

E‧‧‧Recovery solution

F‧‧‧Exhaust

1‧‧‧Rotary packed bed device

2‧‧‧ Shell

3‧‧‧Rotary packed bed

4‧‧‧Upper cover

5‧‧‧Shell

6‧‧‧floor

7‧‧‧Rotating mandrel

8‧‧‧Porous inner ring

9‧‧‧Porous outer ring

10‧‧‧ hollow cover

11‧‧‧Chassis

12‧‧‧solid filling parts

13‧‧‧ gas discharge pipe

14‧‧‧Liquid access tube

15‧‧‧spray opening

16‧‧‧Rotary sealing element

17‧‧‧Steam access tube

18‧‧‧Liquid drain

19‧‧‧ hollow body

20‧‧‧Mezzanine rotary packed bed device

21‧‧‧ outer shell

22‧‧‧ Inner shell

23‧‧‧Rotary packed bed

24‧‧‧Porous inner ring

25‧‧‧Porous outer ring

26‧‧‧ hollow cover

27‧‧‧Chassis

28‧‧‧Rotating mandrel

29‧‧‧solid filling parts

30‧‧‧With cover

31‧‧‧ inner casing

32‧‧‧Inner backplane

33‧‧‧Rotary sealing element

34‧‧‧Steam access pipe

35‧‧‧Liquid drain

36‧‧‧ gas opening

37‧‧‧Liquid access tube

38‧‧‧Intermediate passage

39‧‧‧spray opening

40‧‧‧Outer cover

41‧‧‧Outer casing

42‧‧‧Outer floor

43‧‧‧ Fluid outlet

44‧‧‧ Outer hollow body

45‧‧‧Inner hollow body

100‧‧‧ adjustment slot

110‧‧‧ pump

120‧‧‧Waste water heat exchanger

130‧‧‧First-stage rotating packed bed

140‧‧‧First stage condenser

150‧‧‧First-stage recovery solution storage tank

160‧‧‧ heat exchanger

170‧‧‧Rotary packed bed

310‧‧‧Second stage rotating packed bed

320‧‧‧Second stage condenser

330‧‧‧Second grade recovery solution storage tank

410‧‧‧third-stage rotating packed bed

420‧‧‧third stage condenser

430‧‧‧ third-stage recovery solution storage tank

Figure 1 is a schematic view of the structure of a rotating packed bed.

Figure 2 is a schematic diagram of a primary wastewater recovery process.

Figure 3 is a schematic diagram of a two-stage wastewater recovery process.

Figure 4 is a schematic diagram of a three-stage wastewater recovery process.

Figure 5 is a schematic view showing the structure of a sandwich type rotating packed bed.

The invention provides a method for preparing volatiles by concentrating volatile substances in steam stripping wastewater The recovery system of the substance solution is designed according to the concentration of the original volatile substances in the treated wastewater, combined with a suitable multi-stage (stage) program design, and can utilize the high vapor-liquid mass transfer efficiency and the heat preservation effect of the rotary packed bed device. The volatile matter in the wastewater is recovered to obtain a solution containing a high concentration of volatile matter.

Figure 1 shows a rotary packed bed apparatus 1 for use in the present invention for concentrating a volatile matter solution in a steam stripping wastewater, the rotating packed bed apparatus 1 comprising and preferably a cylindrical outer casing 2; A packed bed 3 is rotated, which is disposed in the outer casing 2. The outer casing 2 comprises an upper cover 4, a casing 5 and a bottom plate 6; the upper cover 4 and the bottom plate 6 are respectively coupled with the upper edge and the lower edge of the casing 5, and a rotating mandrel 7 penetrates the center of the bottom plate 6. The rotary mandrel 7 is driven to rotate by a motor (not shown) to rotate the rotary packed bed 3 relative to the outer casing 2. The rotary packed bed 3 comprises a porous inner ring 8, a porous outer ring 9, a hollow upper cover 10, and a chassis 11, the porous inner ring 8 and the porous outer ring 9 being coupled to the chassis 11, and the chassis 11 is coupled to the rotating mandrel 7. The rotating packed bed 3 has a cavity defined between the porous inner ring 8 and the porous outer ring 9. The cavity is filled with a solid filling member 12, and the material of the solid filling member 12 can be selected from stainless steel, fiber, and oxidation. At least one of aluminum, resin, plastic, zeolite, silicone, activated carbon, Teflon, etc., of which stainless steel is preferred. The porous inner ring 8 and the porous outer ring 9 communicate with each other through a plurality of holes. The rotational speed of the rotary packed bed 3 can be adjusted as needed. Preferably, the rotational speed of the rotary packed bed 3 is 150 to 3000 rpm. The hollow upper cover 10 of the rotary packed bed 3 is provided with a gas discharge pipe 13 through which the gas discharge pipe 13 passes, and a liquid passage pipe 14 enters the gas discharge pipe 13, and the liquid discharge pipe 14 is sprayed. The opening 15 is located inside the porous inner ring 8 of the rotating packed bed 3. A rotary sealing member 16 is disposed between the upper portion of the rotary packed bed 3 and the gas discharge pipe 13 to prevent steam entering the casing 5 from passing through the rotary packed bed 3 and directly discharged from the gas discharge pipe 13. The rotary packed bed device 1 is provided with a steam inlet pipe 17 and a liquid discharge pipe 18, and the gas discharge pipe 13, the steam inlet pipe 17, and the liquid discharge pipe 18 are all passed out of the casing 5 to be connected to an external pipeline. liquid The body passage pipe 14 is passed through the gas discharge pipe 13 and connected to the outside line. The rotary packed bed apparatus 1 comprises a hollow body 19 interposed between the housing 5 and the rotating packed bed 3.

The invention treats wastewater containing ammonia nitrogen or isopropanol as an example, and describes a method and a device for preparing a high concentration aqueous ammonia or isopropyl alcohol solution by concentration, and can refer to FIGS. 2, 3 and 4. In one aspect of the invention, a volatile matter recovery system in a multi-stage (stage) type of wastewater is used to obtain a higher solution concentration, the system comprising more than two rotating packed beds, more than two heat exchanges , more than one condenser, more than two liquid pumps and a steam supply system.

2 is a schematic diagram of a first-stage wastewater containing waste water recovery process, in which the volatile matter-containing wastewater A is adjusted in the conditioning tank 100 (passing the adjusting agent B), and then the liquid pump 110 is used to treat the volatile matter-containing wastewater. After the transportation is increased by the waste water heat exchanger 120 to raise the temperature of the wastewater, it is ejected from the liquid inlet pipe of the first stage rotating packed bed 130 while the steam C is introduced into the steam inlet pipe of the first stage rotating packed bed 130. By transferring the volatile matter in the wastewater to the vapor phase via the vapor-liquid mass transfer mechanism of the first-stage rotating packed bed 130, the volatility contained in the outflow D discharged from the first-stage rotating packed bed 130 can be significantly reduced. Substance concentration. After the volatile matter-containing gas leaves the first-stage rotating packed bed 130, it is connected to the first-stage condenser 140 (the cooling water used is not shown, and the original wastewater can also be used as cooling water), and the gas is condensed. The solution collected as a volatile substance is stored in the first stage recovery solution storage tank 150. If the first stage condenser 140 has a gas that has not been condensed, it will be led to a rotating packed bed 170, and the solution of the first stage recovery solution storage tank 150 is cooled by a heat exchanger 160, and then introduced into the rotary filling. The bed 170 absorbs the uncondensed gas to obtain a recovery solution E containing a volatile substance, and discharges the exhaust gas F.

If the concentration of the volatile matter-containing recovery solution obtained by using the above-mentioned primary wastewater recovery process is still not high enough, the secondary (Fig. 3) or tertiary (Fig. 4) volatile substances will be used. Waste water recycling process. Compared with the first-stage wastewater recovery process, the secondary wastewater recovery process introduces the solution of the first-stage recovery solution storage tank 150 into the second-stage rotary packed bed 310 (Fig. 3), and introduces the fresh steam C into the In the second stage of rotating packed bed 310, the use of fresh steam C ensures high and stable ammonia nitrogen removal efficiency of the second stage rotating packed bed 310. After the volatile matter-containing gas leaves the second-stage rotating packed bed 310, it is connected to the second-stage condenser 320, and the gas is condensed and collected to obtain a higher concentration volatile matter solution, and stored in the second-stage recycling. In solution reservoir 330. The aqueous solution flowing out of the second stage rotating packed bed 310 can be directly discharged or redirected back into the conditioning tank 100. If the first stage condenser 140 and the second stage condenser 320 have gas that has not been condensed, the gas will be led to a rotating packed bed 170, and the solution of the second stage recovery solution storage tank 330 is passed through a heat exchanger. After cooling 160, it is introduced into the rotating packed bed 170 for absorbing the uncondensed gas to prepare a recovery solution E which is higher in concentration than the volatile matter used in the first-stage wastewater recovery process.

Compared with the above-mentioned two-stage waste water recovery process, the three-stage waste water recovery process re-introduces the solution of the second-stage recovery solution storage tank 330 into the third-stage rotary packed bed 410 (Fig. 4), and simultaneously fresh steam C. Introduced into the third stage rotating packed bed 410. After the ammonia-containing steam leaves the third-stage rotating packed bed 410, it is connected to the third-stage condenser 420, and the gas is condensed and collected to obtain a higher concentration volatile matter solution and stored in the third-stage recovery solution. In the tank 430. The aqueous solution flowing from the third stage rotating packed bed 410 can be directly discharged or re-conducted back into the conditioning tank 100 or the first stage recovery solution storage tank 150. If the first stage condenser 140, the second stage condenser 320 and the third stage condenser 420 have not yet condensed gas will be led to a rotating packed bed 170, and the third stage recovery solution storage tank After the solution of 430 is cooled by the heat exchanger 160, it is introduced into the rotating packed bed 170 for absorbing the uncondensed gas, thereby preparing a recovery solution of a higher concentration of volatile substances than the second-stage wastewater recovery process. E.

Volatile material recovery in multi-stage wastewater over three stages (grades), if required system.

In addition, the ratio of the mass flow rate of steam to the mass flow rate of wastewater affects the removal efficiency of pollutants in the wastewater and the concentration of volatiles in the recovered solution. When the ratio is large (for example, greater than 0.25 kg/kg), the removal efficiency of the volatile matter in the wastewater can be obtained, but the concentration of the volatile matter in the recovered solution is lower; when the ratio is small (for example, less than 0.25 kg/kg), the lower volatile matter removal efficiency in the wastewater is obtained, but the concentration of the volatile matter in the recovered solution is higher.

In the present invention, the ratio of the mass flow rate of steam in each stage (stage) to the mass flow rate of the wastewater is about 0.01 to 0.5 kg/kg, preferably 0.05 to 0.4 kg/kg. The invention proposes that the ratio of the mass flow rate of the lower steam to the mass flow rate of the waste water can be used for the wastewater containing the low concentration volatile matter, because the concentration of the volatile matter in the original waste water is low, and high volatile matter removal efficiency is not required. A recovery solution of a higher concentration of volatile substances can be obtained.

The sandwich type rotating packed bed apparatus shown in FIG. 5 is an aspect of the present invention, and the sandwich type rotary packed bed apparatus 20 includes and preferably has a cylindrical outer casing 21 and an inner casing 22; a rotating packed bed 23, which is disposed in the inner casing 22 and rotatable relative to the inner casing 22. The rotating packed bed 23 includes a porous inner ring 24, a porous outer ring 25, a hollow upper cover 26, and a chassis 27, the porous inner ring 24 and the porous outer ring 25 being coupled to the chassis 27, and the chassis 27 is coupled to a rotating mandrel 28. The rotating packed bed 23 has a cavity defined between the porous inner ring 24 and the porous outer ring 25. The cavity is filled with a solid filling member 29, and the material of the solid filling member 29 can be selected from stainless steel, fiber, and oxidation. At least one of aluminum, resin, plastic, zeolite, silicone, activated carbon, Teflon, etc., of which stainless steel is preferred. The porous inner ring 24 and the porous outer ring 25 communicate with each other through a plurality of holes.

The inner casing 22 includes an inner upper cover 30, an inner casing 31 and an inner bottom plate 32. The inner upper cover 30 and the inner bottom plate 32 are respectively coupled with an upper edge and a lower edge of the inner casing 31. The rotating mandrel 28 extends through the center of the inner bottom plate 32. The rotating mandrel 28 is driven by a motor (not shown) The rotation is performed to rotate the rotating packed bed 23 relative to the inner casing 22. The rotational speed of the rotary packed bed 23 can be adjusted as needed. Preferably, the rotational speed of the rotary packed bed 23 is 150 to 3000 rpm. The rotating mandrel 28 is provided with a rotary sealing element 33, such as a shaft seal, through the bottom plate 32. A steam inlet pipe 34 is provided on the side wall of the inner casing 22, and the bottom plate 32 is provided with a liquid discharge pipe 35. The inner upper cover 30 is provided with a gas opening 36 and a liquid inlet pipe 37 into an intermediate passage 38, and a liquid discharge opening 39 of the liquid inlet pipe 37 is located inside the porous inner ring 24 of the rotary packed bed 23. There is a rotary sealing member 33 between the upper portion of the rotating packed bed 23 and the gas opening 36 to prevent steam entering the inner casing 22 from passing through the rotating packed bed 23 and being directly discharged from the gas opening 36.

An outer casing 21 is covered on the outer side of the inner casing 22 and the gas opening 36 at a certain interval, and communicates with the gas opening 36. The outer cylindrical casing 21 is composed of an outer upper cover 40, an outer casing 41 and an outer bottom plate. 42 is configured such that the outer casing 41 is connected to a fluid outlet 43. The liquid inlet pipe 37, the liquid discharge pipe 35, and the steam inlet pipe 34 are all passed through the outer casing 21 to be connected to the outside line. The gas passing through the rotating packed bed 23 enters the outer hollow cavity 44 via the gas opening 36, and part of the gas cools and condenses while simultaneously insulating the hollow body 45 in the inner layer, and the fluid outlet 43 is disposed in the outer casing 21 The case where condensed liquid accumulates in the outer casing 21 can be avoided below. That is, the outer hollow body 44 has the function of a fluid passage, and the presence of the hollow body 44 in the outer layer can achieve the effect of internal heat preservation. In another embodiment of the invention (not shown), the fluid outlets may be disposed at corresponding locations below the outer casing in accordance with external stub requirements.

According to one aspect of the present invention, in the primary waste water recovery process, the above-described sandwich type rotary packed bed apparatus can be used for part or all of the rotating packed bed apparatus; according to another aspect of the present invention, in the secondary type waste water recycling process In the middle, part or all of the rotating packed bed device, the above-mentioned sandwich type rotating packed bed device can be used; according to another aspect of the present invention, in the three-stage waste water recycling process, some or all of the rotating packed bed devices can use the above-mentioned interlayer Rotary packed bed device.

The invention uses steam stripping to recover volatile substances in waste water. In particular, the present invention provides a multi-stage (stage) type rotary packed bed apparatus recovery process for waste water containing low concentration volatile substances. As shown in the following embodiments, the concentration of the ammonia nitrogen wastewater in the embodiment of the present invention ranges from 0.1 to 2.5 wt.%, which proves that the present invention can achieve the purpose of recovering volatile substances from waste water containing low concentrations of volatile materials.

Example

The process for the concentration and recovery of volatile materials from wastewater according to the present invention can be further illustrated by the following preferred embodiments and the accompanying drawings. However, the invention is not limited to the listed embodiments.

Example 1

The aqueous ammonia-containing wastewater is stripped using the primary recovery system of the present invention, and the ammonia nitrogen concentration in the wastewater is about 2.5 wt.%. Firstly, the pH value of the wastewater is adjusted to about 12 in the adjustment tank, and the water temperature is adjusted to about 70 ° C through a heat exchanger, and is introduced into a rotating packed bed by a pump at a flow rate of about 200 kg/h. The steam has a temperature of about 110 ° C and a flow rate of about 25 kg / h, the ratio of steam to wastewater is about 0.125 kg / kg, in the rotating packed bed to carry out the vapor-liquid mass transfer program of ammonia nitrogen, can obtain the ammonia nitrogen of the running water The concentration is about 0.05 wt.% (the ammonia nitrogen removal efficiency is about 98%). At the same time, the ammonia nitrogen-containing gas is discharged from the rotating packed bed and condensed and collected in the first-stage recovery solution storage tank, and the concentration of the recovered ammonia water is about 22 wt.%.

Example 2

The wastewater containing ammonia nitrogen is stripped using the secondary recovery system of the present invention, and the ammonia nitrogen concentration in the wastewater is about 1.2 wt.%. First, the pH value of the wastewater is adjusted to about 12 in the adjustment tank, and the water temperature is adjusted to about 70 ° C through a heat exchanger, and is introduced into the first rotating packed bed by a pump at a flow rate of about 140 kg/h. The steam has a temperature of about 110 ° C and a flow rate of about 25 kg / h, the ratio of steam to wastewater is about 0.18 kg / kg, the first ammonia nitrogen vapor-liquid mass transfer procedure, the ammonia nitrogen concentration of the running water can be obtained 0.01wt.% (Ammonia nitrogen removal efficiency is about 99%). The ammonia nitrogen-containing gas discharged from the rotating packed bed is condensed and collected in the first-stage recovery solution storage tank, and the concentration of the ammonia water recovered by condensation is about 7 wt.%. The ammonia water is pumped into a second rotating packed bed at a flow rate of about 60 kg/h, and a steam having a temperature of about 110 ° C and a flow rate of about 15 kg / h is introduced, and the ratio of steam to wastewater is about 0.25. Kg/kg, the second ammonia-nitrogen vapor-liquid mass transfer program, the ammonia nitrogen concentration of the outflow wastewater is about 0.05wt.% (the ammonia nitrogen removal efficiency is about 99%), and can be directly discharged or returned to the adjustment tank. The ammonia nitrogen-containing gas is discharged from the second rotating packed bed and condensed and collected in the second-stage recovery solution storage tank, and the concentration of the recovered ammonia water is about 25 wt.%.

Example 3

The wastewater containing ammonia nitrogen is stripped using the secondary recovery system of the present invention, and the ammonia nitrogen concentration in the wastewater is about 0.6 wt.%. First, the pH value of the wastewater is adjusted to about 12 in the adjustment tank, and the water temperature is adjusted to about 70 ° C through a heat exchanger, and is introduced into the first rotating packed bed by a pump at a flow rate of about 140 kg/h. The steam has a temperature of about 110 ° C and a flow rate of about 25 kg / h, the ratio of steam to wastewater is about 0.18 kg / kg, the first ammonia nitrogen vapor-liquid mass transfer procedure, the ammonia nitrogen concentration of the running water can be obtained It is 0.005 wt.% (ammonia nitrogen removal efficiency is about 99%). The ammonia nitrogen-containing gas discharged from the rotating packed bed is condensed and collected in a first-stage recovery solution storage tank, and the concentration of the ammonia water recovered by condensation is about 3.5 wt.%. The ammonia water is pumped into the second rotating packed bed at a flow rate of about 160 kg/h, and a steam having a temperature of about 110 ° C and a flow rate of about 20 kg / h is introduced, and the ratio of steam to wastewater is about 0.125kg/kg, the second ammonia-nitrogen vapor-liquid mass transfer program, the ammonia nitrogen concentration of the outflow wastewater is about 0.08wt.% (the ammonia nitrogen removal efficiency is about 98%), and can be directly discharged or returned to the adjustment tank. At the same time, the ammonia nitrogen-containing gas is discharged from the second rotating packed bed for condensation and collected in the second-stage recovery solution storage tank, and the concentration of the recovered ammonia water is about 25 wt.%.

Example 4

The ammonia-containing wastewater is stripped using the three-stage recovery system of the present invention, and the ammonia nitrogen concentration in the wastewater is about 0.1 wt.%. First, the pH value of the wastewater is adjusted to about 12 in the adjustment tank, and the water temperature is adjusted to about 70 ° C through a heat exchanger, and is introduced into the first rotating packed bed by a pump at a flow rate of about 200 kg/h. The steam has a temperature of about 110 ° C and a flow rate of about 20 kg / h, the steam to wastewater ratio of about 0.1 kg / kg, the first ammonia nitrogen vapor-liquid mass transfer program, the ammonia nitrogen concentration of the run-off water can be obtained It is 0.003 wt.% (ammonia nitrogen removal efficiency is about 97%). The ammonia nitrogen-containing gas discharged from the rotating packed bed is condensed and collected in the first-stage recovery solution storage tank, and the concentration of the ammonia water recovered by condensation is about 1.3 wt.%. The ammonia water is then pumped into a second rotating packed bed at a flow rate of about 150 kg/h, while a steam having a temperature of about 110 ° C and a flow rate of about 20 kg/h is introduced, and the ratio of steam to wastewater is about 0.13. Kg/kg, the second ammonia-nitrogen vapor-liquid mass transfer program, the ammonia nitrogen concentration of the outflow wastewater is about 0.02 wt.% (the ammonia nitrogen removal efficiency is about 98%), and can be directly discharged or returned to the adjustment tank, The ammonia-containing gas is discharged from the second rotating packed bed and condensed and collected in the second-stage recovery solution storage tank, and the concentration of the recovered ammonia water is about 8 wt.%. The ammonia water is pumped into a third rotating packed bed at a flow rate of about 60 kg/h, and a steam having a temperature of about 110 ° C and a flow rate of about 20 kg/h is introduced, and the ratio of steam to wastewater is about 0.33. Kg/kg, the third ammonia-nitrogen vapor-liquid mass transfer program, the ammonia nitrogen concentration of the outflow wastewater is about 0.05wt.% (the ammonia nitrogen removal efficiency is about 98%), and can be directly discharged or returned to the adjustment tank. The ammonia nitrogen-containing gas was discharged from the third rotating packed bed and condensed and collected in a third-stage recovery solution storage tank, and the concentration of the recovered ammonia water was about 23 wt.%.

Example 5

The wastewater containing isopropyl alcohol is stripped using the primary recovery system of the present invention, and the isopropanol concentration in the wastewater is about 2 wt.%. First, the wastewater is adjusted to a temperature of about 80 ° C through a heat exchanger, and then introduced into a rotating packed bed by a pump at a flow rate of about 15 kg / h, while the inlet temperature is about 110 ° C and the flow rate is about 3.8 kg. /h of steam, its steam and wastewater The ratio is about 0.25 kg/kg, and the vapor-liquid mass transfer procedure of isopropanol is carried out in the rotating packed bed, and the isopropanol concentration of the produced water is about 0.08 wt.% (the isopropyl alcohol removal efficiency is about 96%). ). At the same time, the isopropanol-containing gas is discharged from the rotating packed bed and condensed and collected in the first-stage recovery solution storage tank, and the concentration of the recovered isopropanol solution is about 9 wt.%.

Example 6

The wastewater containing isopropyl alcohol is stripped using the primary recovery system of the present invention, and the isopropanol concentration in the wastewater is about 2 wt.%. First, the wastewater is adjusted to a temperature of about 80 ° C through a heat exchanger, and then introduced into a rotating packed bed by a pump at a flow rate of about 25 kg / h, while the inlet temperature is about 120 ° C and the flow rate is about 1.65 kg. /h of steam, the ratio of steam to wastewater is about 0.065kg / kg, in the rotating packed bed to carry out the vapor-liquid mass transfer procedure of isopropanol, the isopropanol concentration of the produced water can be obtained is about 0.2wt.% (Isopropanol removal efficiency is about 90%), and the isopropyl alcohol-containing gas is discharged from the rotating packed bed for condensation and collected in the first-stage recovery solution storage tank, and the concentration of the recovered isopropanol solution is about 25 wt. .%.

Example 7

The waste water containing isopropanol is stripped using the secondary recovery system of the present invention, and the isopropanol concentration in the wastewater is about 2 wt.%. First, the wastewater is adjusted to a temperature of about 80 ° C through a heat exchanger, and is introduced into the first rotating packed bed by a pump at a flow rate of about 20 kg/h, and the temperature is about 120 ° C and the flow rate is about 1.5 kg. /h steam, the ratio of steam to wastewater is about 0.08kg / kg, the first isopropyl alcohol vapor-liquid mass transfer procedure, the isopropanol concentration of the produced water can be obtained is about 0.17wt.% (isopropyl The alcohol removal efficiency is about 92%). The isopropyl alcohol-containing gas discharged from the rotating packed bed was condensed and collected in a first-stage recovery solution storage tank, and the concentration of the isopropyl alcohol solution recovered by condensation was about 21 wt.%. The condensed recovered isopropanol solution is then pumped into a second rotating packed bed at a flow rate of about 20 kg/h, while steam having a temperature of about 120 ° C and a flow rate of about 1.6 kg/h is introduced. The ratio of wastewater to wastewater is about 0.08 kg/kg, and the second isopropyl alcohol vapor-liquid mass transfer procedure is carried out. The isopropanol concentration of the outflow wastewater is about 3.2 wt.% (the isopropyl alcohol removal efficiency is about 85%). It can be guided back into the adjusting tank, and the isopropyl alcohol-containing gas is discharged from the second rotating packed bed for condensation and collected in the second-stage recovery solution storage tank, and the concentration of the recovered isopropanol solution is about 70 wt.%. .

A‧‧‧ Wastewater containing volatile substances

B‧‧‧Adjustment

C‧‧‧Steam

D‧‧‧Outflow

E‧‧‧Recovery solution

F‧‧‧Exhaust

100‧‧‧ adjustment slot

110‧‧‧ pump

120‧‧‧Waste water heat exchanger

130‧‧‧First-stage rotating packed bed

140‧‧‧First stage condenser

150‧‧‧First-stage recovery solution storage tank

160‧‧‧ heat exchanger

170‧‧‧Rotary packed bed

310‧‧‧Second stage rotating packed bed

320‧‧‧Second stage condenser

330‧‧‧Second grade recovery solution storage tank

Claims (11)

A sandwich rotary packed bed apparatus comprising: an inner casing (22) having a gas opening (36) and provided with a steam inlet pipe (34) and a liquid discharge pipe (35); an outer casing (21), the space between the inner casing and the inner casing defines an outer hollow body (44), the outer hollow body (44) is connected to the gas opening (36), and is provided with a fluid outlet (43). The outer hollow body (44) encloses the inner casing (22) and the gas opening (36); a rotating packed bed (23) disposed in the inner casing (22), the rotating filling The bed (23) includes a cavity filled with a solid filler (29); a rotating mandrel (28) extending through the inner casing, coupled to the rotating packed bed (23) for rotation The packed bed (23) is rotatable relative to the inner casing (22); and a liquid passage pipe (37) passes through the gas opening (36) and has a liquid discharge opening (39), the liquid discharge opening is disposed in an intermediate passage (38); wherein: the steam inlet pipe (34), the liquid discharge pipe (35), and the liquid inlet pipe (37) pass through the outer casing ( twenty one). The sandwich rotary packed bed apparatus of claim 1, wherein: the outer casing (21) comprises an outer upper cover (40), an outer casing (41) and an outer bottom plate (42), wherein: the fluid outlet (43) is disposed at Below the outer casing (41). The sandwich rotary packed bed apparatus of claim 1, wherein the inner casing (22) comprises an inner upper cover (30), an inner casing (31) and an inner bottom plate (32), wherein: the liquid discharge pipe (35) ) is disposed on the inner bottom plate (32). A sandwich type rotating packed bed apparatus according to claim 1, wherein: There is a rotary sealing element (33) between the upper portion of the rotating packed bed (23) and the gas opening (36). The sandwich rotary packed bed apparatus of claim 1, wherein: the solid filler (29) is selected from at least one of the group consisting of stainless steel, fiber, alumina, resin, plastic, zeolite, silicone , activated carbon and Teflon. A method for steam-releasing waste water containing volatile substances to concentrate a preparation solution containing a high concentration of volatile substances, comprising: introducing steam and volatile matter-containing wastewater into a rotating packed bed device to make the steam And the wastewater is subjected to a vapor-liquid mass transfer procedure in the rotary packed bed apparatus; and the gas leaving the rotating packed bed apparatus is condensed and collected into a recovery solution containing a volatile substance, wherein: the rotary packed bed apparatus is as claimed A sandwich type rotating packed bed apparatus according to any one of 1 to 5. The method of claim 6, wherein: the rotational speed of the rotating packed bed of the rotary packed bed apparatus is from 150 to 3000 rpm. The method of claim 6, wherein the ratio of the mass flow rate of the steam to the mass flow rate of the wastewater is from 0.01 to 0.5 kg/kg. The method of claim 6 wherein: the steam and the volatile matter-containing recovery solution are passed to a second rotary packed bed apparatus such that the vapor and the volatile matter-containing recovery solution are in the second spin fill Performing a vapor-liquid mass transfer procedure in the bed apparatus; and condensing the gas leaving the second rotating packed bed apparatus to contain volatiles A recovery solution of the substance. The method of claim 9 wherein: the steam and the volatile matter-containing recovery solution are passed to a third rotary packed bed apparatus such that the vapor and the volatile matter-containing recovery solution are in the third spin fill A vapor-liquid mass transfer procedure is performed in the bed apparatus; and the gas leaving the third rotating packed bed apparatus is condensed and collected into a recovered solution containing a volatile substance. The method of any one of claims 6, 9 and 10, wherein: the uncondensed gas and the recovery solution are further passed into a rotating packed bed apparatus such that the uncondensed gas is absorbed by the recovered solution .