JP4173708B2 - Wastewater wet oxidation method and equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is discharged from various industrial plants such as chemical plants, electronic component manufacturing facilities, food processing facilities, printing plate making facilities, power generation facilities, photo processing facilities, metal processing facilities, metal plating facilities, metal refining facilities, and paper pulp manufacturing facilities. And methods for purifying various wastewaters such as domestic wastewater such as human waste, sewage and sewage, waste incinerator wastewater, landfill leachate, etc. An improved wet oxidation method that improves the contact efficiency between gas and liquid by increasing the dispersion efficiency of gas and liquid when the above wastewater is wet-oxidized in the countercurrent system, and can improve the treatment performance. It relates to the device.
[0002]
[Prior art]
Conventionally, when supplying a gas and a liquid to a reaction tower, a gas-liquid dispersion member is often provided at the inlet of the reaction tower, and in the case of a gas-liquid upward flow method in which the liquid becomes a continuous phase, A sparger ring, a sintered tube, a porous orifice plate, a single-hole orifice plate or the like may be installed as a gas-liquid dispersion member at the lower part of the plate (for example, see Patent Document 1). Also, in the case of the gas-liquid downward flow method in which the gas becomes a continuous phase, it is conceivable to install a spray nozzle, a notch trough, a perforated plate, and the like.
[0003]
By the way, in the wet oxidation treatment using a catalyst, a gas-liquid upward flow system is usually employed in order to make the liquid a continuous phase as seen in Patent Document 1 and the like. By the way, when the catalytic wet oxidation process is performed by the gas-liquid down-flow method, the contact efficiency between the gas-liquid and the catalyst is low and a large amount of catalyst is required, so the equipment cost and operating cost increase, or the durability of the solid catalyst In addition, if wet oxidation using a catalyst is performed in a gas-liquid down-flow system, it is predicted that gas-liquid will drift in the catalyst layer and the processing performance will decrease. It is.
[0004]
However, as far as the present applicant knows, when the wastewater is wet-oxidized by a gas-liquid downflow method using a catalyst, a specific method for uniformizing the dispersion of the fluid to be treated supplied to the catalyst packed bed is used. No means are presented.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-118473 (claims, etc.).
[0006]
[Problems to be solved by the invention]
The present invention focuses on a method of wet oxidation treatment of wastewater containing an oxidizable substance in a gas-liquid downflow system using a solid catalyst under the circumstances as described above. An object of the present invention is to provide a wet oxidation method and apparatus capable of further improving the efficiency and extending the life of the wet oxidation catalyst, thereby reducing the equipment cost and increasing the operation efficiency.
[0007]
[Means for Solving the Problems]
The wet oxidation method according to the present invention, which has solved the above-mentioned problems, refers to a wet oxidation reaction when a wastewater containing an oxidizable substance is subjected to a wet oxidation treatment in a gas-liquid downflow system using a solid catalyst. The gist lies in that a gas-liquid dispersion member is installed above the solid catalyst packed bed in the tower and the waste water is dispersed in the flow path width direction of the packed bed above the catalyst packed bed.
[0008]
In carrying out the above method, if the gas-liquid dispersion member is of an overflow type and the liquid is overflowed and dispersedly supplied in the direction of the catalyst packed bed below, the dispersion efficiency can be improved more reliably. Preferably, if a gas-liquid separation unit is provided above the gas-liquid dispersion member to separate the gas and liquid in advance, and the liquid is supplied from the gas-liquid separation unit to the gas-liquid dispersion member through the liquid conduction pipe, It is preferable because the dispersion efficiency can be further improved.
[0009]
The wet oxidation treatment apparatus according to the present invention provides an apparatus suitable for carrying out the treatment method, and a gas-liquid dispersion member is installed above the solid catalyst packed bed in the wet oxidation reaction tower. There is a gist there. Also in this apparatus, the gas-liquid dispersion member installed on the upper part of the solid catalyst packed bed is particularly preferably an overflow type, and the gas-liquid separation that separates the gas-liquid in advance on the gas-liquid dispersion member It is recommended that the gas can be supplied to the gas-liquid dispersion member from the gas-liquid separation part through the liquid conducting tube so that the gas-liquid dispersion efficiency can be further improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have conducted wet oxidation treatment of wastewater containing an oxidizable substance by a gas-liquid downflow system using a solid catalyst. If a gas-liquid dispersion member is installed in the upper part of the oxidation reaction tower, the drift of the fluid to be treated in the solid catalyst packed bed is suppressed and the contact efficiency between the gas and the liquid and the catalyst is improved, so that the processing efficiency is greatly improved. As a result, the present invention has been completed.
[0011]
Hereinafter, the method and apparatus of the present invention will be described in detail.
[0012]
The present invention uses waste water containing an oxidizable substance as a liquid to be treated, and performs wet oxidation treatment in a gas-liquid downflow system using a solid catalyst. A gas-liquid dispersion member is installed in the upper part of the catalyst packed bed to disperse the drainage in the flow path width direction of the packed bed.
[0013]
In the case where the wastewater is wet-oxidized by a gas-liquid downward flow method using a solid catalyst, a gas-liquid dispersion member is installed at the upper part in the wet oxidation reaction tower (hereinafter sometimes simply referred to as a reaction tower). Dispersion efficiency of gas and liquid in the catalyst packed bed is improved, contact efficiency between the gas and liquid is increased, and processing performance is improved. As a result, the efficiency of the wet oxidation treatment is improved, and as a result, the equipment cost and the operating cost can be reduced. Moreover, since the entire solid catalyst packed in the reaction tower is uniformly and uniformly subjected to wet oxidation, local deactivation is unlikely to occur, and the durability of the catalyst is improved.
[0014]
If the wastewater to be treated contains SS (Suspended Solids) components or ions that generate solids in the catalytic wet oxidation process, an overflow type gas-liquid dispersion member should be used. It is preferable to use it. In the case of such drainage, if a gas-liquid dispersion member other than the overflow type (for example, liquid hole type) is used, the solid hole may block the liquid hole for the liquid to flow down, and the gas liquid may not be uniformly dispersed. Because there is.
[0015]
In order to further increase the dispersion efficiency when the overflow type gas-liquid dispersion member is used, it is preferable to suppress as much as possible the disturbance of the liquid surface of the liquid reservoir formed on the upper surface side of the dispersion member. That is, when the gas / liquid is supplied directly from above to the gas / liquid dispersion member, the liquid level of the liquid reservoir portion is often disturbed. Therefore, in order to further enhance the gas / liquid dispersion effect, the gas / liquid is disposed above the gas / liquid dispersion member. Is preferably separated in advance, and the liquid is supplied so that the liquid level in the liquid reservoir is not disturbed.
[0016]
Therefore, as will be described in detail later, it is possible to provide a gas-liquid separation unit above the gas-liquid dispersion member, and perform gas-liquid separation in advance at the gas-liquid separation unit before sending the liquid toward the gas-liquid dispersion member. It is recommended as a preferred embodiment when practicing the present invention.
[0017]
Examples of the wastewater to which the present invention is applied include chemical plants, electronic component manufacturing equipment, food processing equipment, printing plate making equipment, power generation equipment, photo processing equipment, metal processing equipment, metal plating equipment, metal refining equipment, and paper pulp manufacturing. Various types of wastewater such as wastewater discharged from various industrial plants such as facilities, domestic wastewater such as manure and sewage, waste incinerator wastewater such as wet smoke washing wastewater, and landfill leachate. In order to clean the soil containing harmful substances, an extract obtained by extracting the harmful substances in the soil with water or the like can also be treated as the wastewater to be treated of the present invention.
[0018]
Among them, the present invention is an apparatus for producing aliphatic carboxylic acids such as acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester and aliphatic carboxylic acid ester; aromatic carboxylic acid such as terephthalic acid and terephthalic acid ester; Production equipment for aromatic carboxylic acid esters; equipment for EOG production; equipment for producing alcohol such as methanol, ethanol, and higher alcohol; or wastewater containing organic matter discharged from food additives, pharmaceuticals, industrial chemical production equipment, etc. It can be effectively used for ammonia-containing wastewater discharged from electronic parts manufacturing facilities.
[0019]
The “oxidizable substance” contained in the waste water means an organic and / or inorganic compound that can be purified by oxidation / decomposition treatment, and various organic compounds, sulfur compounds, nitrogen compounds, organic halogen compounds, organic compounds. Phosphorus compounds and the like are included. Specifically, organic compounds such as methanol, ethanol, acetaldehyde, formic acid, acetone, acetic acid, propionic acid, tetrahydrofuran and phenol; nitrogen compounds such as ammonia, hydrazine, nitrite, dimethylformamide, monoethanolamine, pyridine and urea ; Sulfur compounds such as thiosulfate, sodium sulfide, dimethyl sulfoxide, alkylbenzene sulfonate; hydrogen peroxide and the like, of course, but not limited thereto. These oxidizable substances may be dissolved in the waste water or may be contained as a suspended substance.
[0020]
Oxidation / decomposition treatment here refers to, for example, oxidation treatment that converts ethanol into acetic acid, oxidative decomposition treatment that decomposes acetic acid into carbon dioxide and water, decarboxylation treatment that converts acetic acid into carbon dioxide and methane, and low molecular weights of various organic substances. Oxidative decomposition treatment, hydrolytic treatment to decompose urea into ammonia and carbon dioxide, oxidative decomposition treatment to convert ammonia and hydrazine into nitrogen gas and water, decomposition treatment to convert nitrate ion and nitrite ion into nitrogen gas, organic halogen compounds Including the dechlorination treatment of toxic substances in the wastewater, it means a treatment that converts the harmful substances in the wastewater into substantially harmless ones.
[0021]
In the present invention, “liquid” means liquid, and includes all of water, various wastewaters, organic solvents, inorganic and / or organic substance aqueous solutions, oil-water mixed dispersions and suspensions, slurries, etc. There are no restrictions on properties.
[0022]
In addition, the type of “gas” in the present invention is not particularly limited, and includes oxygen-containing gas, water vapor, organic vapor, carbon dioxide, and the like.
[0023]
Hereinafter, the wet oxidation method and apparatus of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited by the illustrated examples, and can be adapted to the purpose described above and below. Of course, it is possible to implement the design with appropriate changes within the range.
[0024]
FIG. 1 is a basic processing flow diagram of wastewater treatment to which the wet oxidation treatment of the present invention is applied, and wastewater to be treated is supplied from a wastewater supply line 1 after being boosted by a pump 2. On the other hand, an oxygen-containing gas is introduced from the oxygen-containing gas supply line 3, and the pressure is increased by the compressor 4 and then mixed into the wastewater to be treated. The obtained gas-liquid mixed fluid is heated by the heat exchanger 5 and further heated to a predetermined temperature by the heater 6, and then introduced into the wet oxidation reaction tower 7 filled with the solid catalyst, where the wet oxidation treatment is performed. Is called.
[0025]
The space velocity (LHSV) when the pressure is increased after being pumped by the pump 2 is not particularly limited, and may be appropriately determined according to the wet oxidation treatment capability of the reaction tower.^-1Or more, preferably 0.15 hr^-1Or more, more preferably 0.2 hr^-110hr^-1Or less, more preferably 7 hr^-1Or less, more preferably 5 hr^-1It is good to adjust so that it may become the following. By the way, space velocity is 0.1hr^-1Less than 10 hours, the amount of processing per unit time may be insufficient and excessive equipment may be required.^-1If the space velocity is excessively increased beyond this value, the purification action by wet oxidation may be insufficient.
[0026]
As shown in the drawing, the wet oxidation process employing the present invention is performed in the presence of an oxygen-containing gas. The type of oxygen-containing gas is not particularly limited, and pure oxygen, oxygen-enriched gas, air, ozone, hydrogen peroxide, etc. can be used, and oxygen-containing gas generated in other plants can also be used. . Among these, air is most preferable from the viewpoint of economy. When pure oxygen, ozone, or the like is used, it can be diluted with air or an inert gas.
[0027]
There is no particular limitation on the supply amount of the oxygen-containing gas, and an amount necessary for oxidizing and decomposing the harmful substances in the wastewater may be supplied. A preferable supply amount of the oxygen-containing gas is 0.4 times or more, more preferably 0.5 times or more, preferably 5.0 times or less, more preferably 3.0 times or less the theoretical oxygen demand of the waste water. If the supply amount of oxygen-containing gas is less than 0.4 times the theoretical oxygen demand, the oxidative decomposition of hazardous substances contained in the waste water may be insufficient, while the supply amount exceeds 5.0 times. However, the wet oxidation performance does not increase further, and not only the consumption of the oxygen-containing gas increases unnecessarily, but also the equipment is unnecessarily increased in size, which is useless. Here, the “theoretical oxygen demand” refers to the amount of oxygen necessary for decomposing the oxidizable substance in the wastewater into ash such as nitrogen, carbon dioxide, water, or sulfate.
[0028]
In the illustrated example, the gas-liquid mixed fluid in which oxygen-containing gas is mixed into the waste water is preheated by the heat exchanger 5, further heated to a predetermined temperature by the heater 6, and then supplied to the reaction tower 7. Although an example is shown, the heating method is of course not limited to this, and it may be heated by only one of the heat exchanger 5 and the heater 6, or a heater (not shown) in the pipeline or the reaction tower 7 may be used. ) Or the like may be provided for heating. These heating means may be employed alone, or two or more heating means may be arbitrarily combined and employed.
[0029]
Further, the gas-liquid mixed fluid supplied to the heat exchanger 5 is heat-exchanged with the high-temperature processing liquid discharged after being wet-oxidized in the reaction tower 7 or discharged from another plant. Heat exchange may be performed with a high-temperature gas or liquid, and the heat medium and heating means for heating the gas-liquid mixed fluid are not limited at all.
[0030]
In the reaction tower 7, catalytic wet oxidation is performed in a gas-liquid downward flow system. The preferred temperature for performing catalytic wet oxidation in the reaction tower 7 is affected by other conditions (type and concentration of oxidizable substances contained in the waste water, flow rate of waste water, type of catalyst, etc.), but 370 If it exceeds ℃, it becomes difficult to maintain the wastewater in the liquid phase state, and the equipment becomes larger, and the running cost may increase, so the processing temperature is 370 ° C or less, more preferably 300 ° C or less, more preferably It should be 280 ° C or lower. Further, when the catalyst contains a combustible component such as carbon, it is necessary to suppress the heating temperature to a temperature at which the catalyst does not burn, preferably 200 ° C. or less, more preferably 170 ° C. or less. However, when the heating temperature is less than 30 ° C., the wet oxidation reaction may not easily proceed efficiently. Therefore, it is preferably 30 ° C. or more, more preferably 40 ° C. or more, and further preferably 45 ° C. or more.
[0031]
In the catalytic wet oxidation reaction performed using the apparatus of the present invention, it is desirable to adjust the pressure condition so that the wastewater can maintain the liquid phase, and the specific pressure may be appropriately selected in consideration of the relationship with the treatment temperature.
[0032]
The type, shape, and structure of the reaction tower 7 used in the present invention are not particularly limited, and may be either a single tube type or a multi-tube type. In some cases, a plurality of the same or different structures can be used in combination.
[0033]
In the present invention, the reaction tower 7 is filled with a solid catalyst, and waste water is passed through the catalyst packed bed, whereby the oxidizable substance in the waste water is subjected to wet oxidation treatment. As the solid catalyst used here, any solid catalyst that exhibits oxidation and resolution under wet conditions can be used, and a known solid catalyst widely used for wet oxidation treatment can also be used. As a preferred specific example, as a catalyst having both oxidation activity and durability under wet oxidation conditions, for example, titanium, silicon, aluminum, zirconium, manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, Examples thereof include a catalyst containing at least one element selected from platinum, palladium, rhodium, ruthenium, iridium and the like, and / or activated carbon. The activated carbon here includes not only ordinary activated carbon but also activated coke, graphite carbon, activated carbon fiber and the like.
[0034]
Among them, particularly preferred is a solid catalyst containing the following catalyst component A and catalyst component B. That is, the preferred catalyst component A is an oxide of at least one element selected from the group consisting of iron, titanium, silicon, aluminum, and zirconium, or activated carbon, and the catalyst component B is manganese, cobalt, nickel And at least one metal selected from the group consisting of cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium and / or a compound thereof.
[0035]
More preferable specific examples of the catalyst component A include metal oxides such as titanium oxide, iron oxide, and zirconium oxide; binary systems such as titanium oxide-zirconium oxide and titanium oxide-iron oxide; System oxide (including composite oxide); activated carbon or a mixture of metal oxide and activated carbon. The ratio of the catalyst component A in the solid catalyst is preferably in the range of 30 to 99.95% by mass. This is because when the catalyst component A is blended at a ratio of 30% by mass or more, the durability of the solid catalyst is improved.
[0036]
Preferable specific examples of the catalyst component B include metals, oxides and composite oxides composed of the elements described above. The ratio of the catalyst component B in the solid catalyst is preferably in the range of 0.05 to 70% by mass. It is because the oxidation and / or decomposition | disassembly of the harmful substance in waste_water | drain can be advanced more efficiently by the mixture ratio being 0.05 mass% or more.
[0037]
In addition, when selecting silver, gold | metal | money, platinum, palladium, rhodium, ruthenium, and iridium (henceforth "B-1 component") among the said elements, the total amount of the said metal and / or compound is solid catalyst. It is good to set it as 0.05-10 mass% in the ratio for which it occupies. Even if it is used at a ratio exceeding 10% by mass, the corresponding improvement in wet oxidation efficiency is not recognized, and since it is an expensive raw material, the cost of the solid catalyst is increased, which is economically disadvantageous. When a metal other than the above, ie, manganese, cobalt, nickel, cerium, tungsten, and copper (hereinafter referred to as “B-2 component”) is selected, the total amount of the metal and / or compound is occupied in the solid catalyst. The ratio is preferably 0.05 to 70% by mass. If the total amount is in the range of 0.05 to 70% by mass, the above B-1 component and B-2 component can be used in appropriate combinations in the range of 0.05 to 10% by mass and 0.05 to 70% by mass, respectively.
[0038]
Among the solid catalysts, those containing the B-1 component as the catalyst component B are preferable because they exhibit particularly excellent catalytic activity. Among the components B-1, those containing at least one elemental metal and / or compound selected from platinum, palladium, rhodium, ruthenium and iridium are particularly preferable because they exhibit a high level of catalytic activity. Among the components B-2, manganese, cobalt, nickel and copper are preferably used.
[0039]
The shape of the solid catalyst is not particularly limited, and various shapes such as a granular shape, a spherical shape, a pellet shape, a ring shape, a crushed piece shape, and a honeycomb shape can be used. However, in consideration of cost, handling properties, etc., those molded into a spherical shape or a pellet shape are optimal.
[0040]
In the present invention, when filling the solid catalyst into the reaction tower, the front stage is filled with a packing material in order to efficiently stir the gas and liquid to increase the contact efficiency and suppress the gas-liquid drift. It is also effective to do. As a filler, as long as the gas-liquid contact efficiency can be improved, the material, type, size and the like are not limited at all, and various fillers can be used. Examples of the material for the filler include metal, ceramic, glass, and resin. Examples of the shape of the filler include pellets, spheres, granules, rings (such as Raschig rings, Lessing rings, and ball rings), honeycombs, nets, and nets or plates formed into a woven structure. The size of the packing is not particularly limited, but in the case of a pellet-shaped, spherical, granular, or ring-shaped packing, a size of about 3 mm to 50 mm is preferable.
[0041]
In the wet oxidation treatment apparatus of the present invention, a gas-liquid dispersion member is installed in the upper part of the reaction tower 7, that is, the gas-liquid inlet of the reaction tower 7, and the liquid dispersion efficiency in the channel width direction of the catalyst packed bed As a result, the contact efficiency between the gas (oxygen-containing gas) constituting the continuous layer, the liquid and the catalyst is increased, and the wet oxidation treatment efficiency is improved. Hereinafter, the gas-liquid dispersion member that is a main component of the present invention will be described with reference to the drawings.
[0042]
2 and 3 are a schematic plan view and a longitudinal sectional explanatory view illustrating a liquid hole type gas-liquid dispersion member, and a dispersion plate 16 is disposed at the upper part in the reaction tower 7 so as to block the flow path, The dispersion plate 16 is provided with a liquid hole 14 through which liquid flows and a gas conduction part 15 through which gas passes. The shape of the liquid hole 14 is not particularly limited, and various shapes such as a circle, an ellipse, and a polygon can be employed. The equivalent diameter and number of the liquid holes 14 are preferably 0.02 m / s or more and 10 m / s or less, more preferably 0.05 m / s or more and 5 m / s or less, and further preferably 0.1 m / s or more and 2 m in terms of the linear velocity of the liquid. / S or less may be determined. If the linear velocity of the liquid exceeds 10 m / s, the pressure loss increases, which is not preferable. On the other hand, a passage linear velocity of less than 0.02 m / s is not preferable because gas can easily pass through.
[0043]
The equivalent diameter mentioned above means a numerical value obtained by dividing the total side length of the cross-sectional shape by 4. For example, a square with a side of 1000 mm has a size of 1000 × 4/4 = 1000 mm, and the equivalent diameter is 1000 mm. Hereinafter, unless otherwise specified, the meaning of diameter, inner diameter, and diameter includes equivalent diameter.
[0044]
The number of liquid holes 14 is at least 1 / m per one dispersion plate 16.²Or more, preferably 5 / m²Or more, more preferably 10 pieces / m²More than 500 pieces / m²Or less, more preferably 400 pieces / m²Or less, more preferably 300 / m²The following is recommended. The equivalent diameter of the liquid hole 14 is preferably 0.1 mm to 1/4 of the dispersion plate diameter, more preferably 1 mm to 1/10 of the dispersion plate diameter, particularly preferably 3 mm to 1/20 of the dispersion plate diameter. It is a range. The opening ratio of the liquid hole 14 is preferably in the range of 0.005 to 30%, more preferably 0.05 to 10%, and still more preferably 0.1 to 3% with respect to the inner diameter cross-sectional area of the reaction tower 7. The dispersion efficiency improves as the hole diameter of the liquid hole 14 is smaller, but if it is too small, clogging may occur due to solids contained in the drainage, and processing for drilling the liquid hole 14 in the dispersion plate 16 It becomes complicated. Although the equivalent diameters of the liquid holes 14 are generally the same, even when the liquid holes 14 having different diameters are provided, basically the same dispersion effect can be obtained.
[0045]
The structure of the gas conduction part 15 is not particularly limited, but the opening 15a is preferably provided on the side surface so that the gas-liquid mixed fluid supplied from above does not pass directly. The area of the opening 15a is not particularly limited, but it is desirable to design the pressure loss before and after the gas-liquid dispersion member to be in the range of 0 to 0.3 MPa. The shape of the gas conduction portion 15 is not particularly limited, and may be any shape such as a prismatic shape, a cylindrical shape, a pyramid shape, or a conical shape.
[0046]
Further, the position of the opening 15a formed on the side surface of the gas conduction part 15 needs to be higher than the liquid level of the liquid pool formed on the dispersion plate 16. This is because when the liquid flows out from the opening 15a, the gas-liquid dispersion state intended in the present invention cannot be obtained. The position of the opening 15a is preferably 10 mm or more higher than the liquid level of the liquid reservoir, more preferably 30 mm or more, and still more preferably 50 mm or more.
[0047]
4 and 5 are a plan explanatory view and a vertical cross-sectional explanatory view illustrating an overflow type gas-liquid dispersion member, and a gas-liquid flow path is formed in the upper part of the reaction tower 7 in the same manner as in the examples of FIGS. A dispersion plate 18 is disposed so as to be blocked, and the dispersion plate 18 is provided with an overflow pipe 17 for allowing gas and liquid to flow down. The overflow pipe 17 is formed by extending a pipe having the same cross-sectional shape as the hole above the hole formed in the dispersion plate 18. The cross-sectional shape of the overflow pipe 17 is not particularly limited, and various shapes such as a circle, an ellipse, and a polygon can be used.
[0048]
The number of overflow pipes 17 is at least 1 / m per dispersion plate 18.²Or more, preferably 5 / m²Or more, more preferably 10 / m²More than 500 / m²Or less, more preferably 400 / m²Or less, more preferably 300 / m²The equivalent diameter of the overflow pipe 17 is 10 mm to 1/4 of the dispersion plate diameter, more preferably 15 mm to 1/10 of the dispersion plate diameter, and further preferably 20 mm to 1 of the dispersion plate diameter. / 20 is recommended. The opening ratio of the overflow pipe 17 is 5 to 50%, more preferably 7 to 45%, and still more preferably 10 to 40% with respect to the inner diameter cross-sectional area of the reaction tower 7.
[0049]
Of the gas and liquid, the liquid forms a liquid pool on the dispersion plate 18 and flows down along the inner wall of the overflow pipe 17. It is preferable to provide a notch at the upper end of the overflow pipe 17 in order to make the liquid overflow smoothly. There is no particular limitation on the shape of the cut, and examples thereof include a square shape, a V shape, and an arc shape. It is also effective to provide a square or V-shaped leg at the lower end of the overflow pipe 17 so that the liquid flows smoothly.
[0050]
In general, the cross-sectional shape and equivalent diameter of each overflow pipe 17 are the same, but not limited to this, even when a plurality of different shapes and equivalent diameters are provided, basically the same dispersion effect is obtained. be able to.
[0051]
When a gas-liquid dispersion member is installed above the catalyst packed bed as shown in the above example, and the liquid is dispersed and supplied in the flow path width direction of the catalyst packed bed by the gas-liquid dispersing member, the liquid is one of the catalyst packed bed. It flows evenly over the entire surface without flowing unevenly. As a result, the liquid contacts the gas (oxidizing gas) and the catalyst constituting the continuous layer evenly, and the wet oxidation proceeds efficiently in the entire catalyst packed bed.
[0052]
Therefore, the specific shape and structure of the gas-liquid dispersion member used in the present invention are not particularly limited as long as the uniform dispersion effect can be effectively exhibited, and there are various shapes and structures other than those illustrated. Can be used.
[0053]
As described above, in the present invention, the gas-liquid dispersion member is disposed above the catalyst packed bed in the reaction tower, and the liquid supplied to the catalyst packed bed by the dispersing member is as uniform as possible in the flow path width direction of the catalyst packed bed. It is characterized in that the contact efficiency between the catalyst and the fluid to be treated can be increased by dispersing the catalyst in the upper part of the gas-liquid dispersion member. It is also recommended as a preferred embodiment that a gas-liquid separation unit that separates the gas-liquid in advance is provided so that the liquid is supplied from the gas-liquid separation unit to the gas-liquid dispersion device through the liquid conduction pipe. The shape of the gas-liquid separation unit is such that the gas-liquid supplied from the upper part of the reaction tower is separated and the liquid can be smoothly supplied so as not to disturb the liquid level of the liquid reservoir on the gas-liquid dispersion member upper surface side. Preferably, the specific structure is not particularly limited.
[0054]
An example of the gas-liquid separator is shown in FIGS. In FIG. 6, the gas-liquid mixed fluid supplied from above through the gas-liquid introduction pipe 19 is received by the tray 20. A liquid conducting tube 21 is provided on the lower surface of the tray 20, the liquid is supplied downward through the liquid conducting tube 21, and the gas is released from the opened upper surface of the tray 20. The tray 20 may have only one stage, but it is preferable to provide a plurality of stages in order to minimize the liquid level disturbance. The shapes of the tray 20 and the liquid conducting tube 21 are not particularly limited, and may be any shape such as a circle, an ellipse, or a polygon. There are no particular restrictions on the number or equivalent diameter of the liquid conduction pipes 21, but when gas is mixed into the liquid conduction pipe 21, the gas is ejected from the lower end of the conduction pipe 21 and formed on the dispersion plate 18. Since the liquid level of the liquid reservoir is disturbed, it is desirable to consider so that the liquid can be accumulated on the tray 20 in order to prevent such a phenomenon.
[0055]
When a plurality of trays 20 are provided, the size and shape of the trays 20 in each step may be the same or different. When multiple trays 20 are provided, a liquid conduction pipe 21 is provided on the lowermost tray 20 to supply liquid to the gas-liquid dispersion device below, but liquid conduction pipes 21 are provided on the trays 20 other than the lowermost stage. Alternatively, the liquid may overflow from the tray 20 and flow down to the lower stage. In this case, the lower tray should be designed to be larger than the upper tray, and it is effective to provide a square or V-shaped notch for overflowing the liquid at the upper peripheral edge of the tray. It is.
[0056]
In the example of FIG. 7, an opening 22 a is provided on the upper surface of the gas-liquid introduction tube 22. The gas is discharged from the opening 22a, and the liquid is supplied downward through the liquid conduction pipe 23 provided on the lower surface side of the gas-liquid introduction pipe 22. The shape of the liquid conducting tube 23 is not particularly limited, and may be any shape such as a circle, an ellipse, or a polygon. The number and the equivalent diameter of the liquid conduction pipes 23 can be arbitrarily set. However, in order to prevent gas from being mixed into the liquid conduction pipes 23, consideration should be given so that liquid can be accumulated in the gas-liquid introduction pipes 22. Good. Further, it is preferable to provide a tray 20 as shown in FIG. 6 below the liquid conduction tube 23 because the gas-liquid dispersion effect can be further enhanced.
[0057]
When the packed bed of the solid catalyst (and / or packed material) packed in the reaction tower 7 is long, it is also effective to divide the packed bed into a plurality of layers. Specifically, when the layer length of the solid catalyst (and / or packing) packed bed is 2500 mm or more, particularly 3000 mm or more, it is desirable to divide the packed bed into a plurality of layers. And it is preferable to provide a gas-liquid dispersion member and a gas-liquid separation part similar to those described above at the upper part of each packed bed divided into a plurality, so that the gas-liquid drift can be reduced in each packed bed. .
[0058]
Referring again to FIG. 1, the processing liquid processed in the reaction tower 7 is cooled by the heat exchanger 5 and the cooler 8 as necessary, and then converted into gas and liquid by the gas-liquid separator 9. To be separated. At this time, both the heat exchanger 5 and the cooler 8 may be provided. In some cases, only one of them may be used.
[0059]
In addition, when the equipment as shown in FIG. 1 is automatically operated, the liquid level controller LC is provided in the gas / liquid separator 9 to detect the liquid level, and the liquid level control valve 10 detects the liquid level inside the gas / liquid separator 9. It is desirable to control the liquid level to be constant. Here, “constant” means that the liquid level is at a certain position or within a certain range.
[0060]
The water that has been treated may be cooled, then discharged through a pressure control valve (not shown), and separated into gas and liquid by the gas-liquid separator 9.
[0061]
The liquid separated by the gas-liquid separator 9 is discharged through the treated water discharge line 11, and this treated water may be sent to a treated liquid tank (not shown) or by a known method such as biological treatment. Further purification treatment may be performed.
[0062]
It is desirable that the pressure on the gas side in the gas-liquid separator 9 is detected by the pressure controller PC and the pressure control valve 12 is operated to maintain the pressure at an appropriate value. The gas separated by the gas-liquid separator 9 may be discharged from the exhaust gas discharge line 13 into the atmosphere, or may be processed by another method.
[0063]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited by the following examples, and may be appropriately changed within a range that can meet the purpose described above and below. It is also possible to implement them, and they are all included in the technical scope of the present invention.
[0064]
Example 1
In order to treat harmful substances in the waste water, wet oxidation treatment was performed according to the flow chart shown in FIG. The wastewater used for the treatment was wastewater discharged from a chemical plant, contained compounds such as alcohol, aldehyde, and carboxylic acid, had a COD (Cr) concentration of 25,000 mg / liter, and a pH of 7.5.
[0065]
As the reaction tower 7, a cylindrical one having an inner diameter of 400 mm and a length of 3,000 mm was used. The reaction tower 7 was filled with 250 liters of catalyst so that the catalyst packed layer length was 2,000 mm. In addition, as a catalyst, the catalyst (The shape is a pellet shape 5 mm in diameter and 5 mm in length) which supported platinum 0.3 mass% on the titanium- iron type oxide was used.
[0066]
A gas-liquid dispersion member as shown in FIGS. 2 and 3 and a gas-liquid separation part as shown in FIG. 7 are arranged above the catalyst packed bed in the reaction tower 7. However, the liquid holes of the gas-liquid dispersion member are circular with an inner diameter of 3 mm, and the number is 12 (95 / m²).
[0067]
The wastewater is fed from the drainage supply line 1 through the pump 2 at a flow rate of 250 liters / hr, while the oxygen-containing gas supply line 3 is supplied with 23 m of air as an oxygen-containing gas.^Three _NIt was introduced at a flow rate of / hr (1.1 times the theoretical oxygen demand), increased in pressure by the compressor 4, and mixed into the waste water. The obtained gas-liquid mixed fluid was heated with the heat exchanger 5 and further heated to 210 ° C. with the heater 6 and then introduced into the reaction tower 7 and subjected to wet oxidation at the same temperature. The processing fluid processed in the reaction tower 7 was cooled by the heat exchanger 5 and the cooler 8 and then introduced into the gas-liquid separator 9. The gas-liquid separator 9 keeps the liquid level constant by operating the liquid level control valve 10 while detecting the liquid level with the liquid level controller (LC) and also detects the pressure with the pressure controller (PC). By operating the pressure control valve 12, the pressure was maintained at 3.0 MPa, and the treatment liquid was discharged from the treated water discharge line 11.
[0068]
The COD (Cr) concentration of the treated water was 860 mg / liter, and the COD (Cr) treatment efficiency was 96.6%.
[0069]
Example 2
The gas-liquid dispersion member having the structure shown in FIGS. 4 and 5 and the gas-liquid separation part having the structure shown in FIG. 6 are installed on the upper part of the catalyst packed bed in the reaction tower 7. Similarly, wastewater from the chemical plant was treated. However, the overflow pipe of the gas-liquid dispersion member has a cylindrical shape with an inner diameter of 25 mm, and the number is 35 (279 / m²And the length was 150 mm from the upper surface of the dispersion plate. As a result, the COD (Cr) concentration of the treated water was 790 mg / liter, and the COD (Cr) treatment efficiency was 96.8%.
[0070]
Comparative Example 1
Exhaust treatment from the chemical plant was performed in the same manner as in Example 1 except that no gas-liquid dispersion member was installed above the catalyst packed bed in the reaction tower 7. As a result, the COD (Cr) concentration of the treated water was 11,900 mg / liter, and the COD (Cr) treatment efficiency was 52.4%.
[0071]
【The invention's effect】
The present invention is configured as described above, and when the waste water is wet-oxidized using a solid catalyst in a gas-liquid downward flow system, a gas-liquid dispersion member is provided above or further above the catalyst packed bed. Since the gas-liquid separation part is disposed in the catalyst and the fluid supplied in the direction of the catalyst packed bed is dispersed in the flow path width direction of the catalyst packed bed, the contact efficiency between the gas and the liquid can be increased. The contact efficiency between the oxygen contained in the liquid and the oxidizable substance contained in the liquid is improved, the contact efficiency between the gas-liquid and the catalyst is improved, and the wet oxidation efficiency of the waste water can be greatly increased. Thus, the facility cost and the operating cost can be reduced, and the durability of the solid catalyst can be improved.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of a wastewater treatment method according to the present invention.
FIG. 2 is an explanatory plan view showing an example of a gas-liquid dispersion member used in the present invention.
FIG. 3 is a longitudinal sectional view illustrating an example of a gas-liquid dispersion member used in the present invention.
FIG. 4 is an explanatory plan view illustrating another gas-liquid dispersion member used in the present invention.
FIG. 5 is an explanatory longitudinal cross-sectional view illustrating another gas-liquid dispersion member used in the present invention.
FIG. 6 is a perspective explanatory view showing an example of a gas-liquid separator used in the present invention.
FIG. 7 is an explanatory perspective view showing another example of the gas-liquid separator used in the present invention.
[Explanation of symbols]
1 Wastewater supply line
2 Pump
3 Oxygen-containing gas supply line
4 compressors
5 Heat exchanger
6 Heater
7 reaction tower
8 Cooler
9 Gas-liquid separator
10 Liquid level control valve
11 treated water discharge line
12 Pressure control valve
13 Exhaust gas emission line
14 Liquid hole
15 Gas conduction part
16 Dispersion plate
17 Overflow pipe
18 Dispersion plate
19 Gas-liquid inlet tube
20 trays
21 Liquid conduit
22 Gas-liquid inlet tube
23 Liquid conduit

Claims (4)

In wet oxidation treatment of wastewater containing oxidizable substances using a solid catalyst in a gas-liquid downflow system,
A gas-liquid dispersion member that performs dispersion supply by overflowing the liquid is installed on the upper part of the solid catalyst packed bed in the wet oxidation reaction tower,
A gas-liquid separation unit is provided on the gas-liquid dispersion member to previously separate the gas and liquid,
Supply the liquid from the gas-liquid separator to the gas-liquid dispersion member through the liquid conducting tube,
A wastewater wet oxidation method for dispersing wastewater in the flow path width direction of the packed bed at the top of the catalyst packed bed ,
The gas-liquid dispersion member consists of a dispersion plate and an overflow pipe that block the gas-liquid flow path,
The overflow pipe is formed by extending a pipe having the same cross-sectional shape as the hole above the hole drilled in the dispersion plate to a position higher than the lower end of the liquid conduction pipe,
The liquid forms a liquid pool on the dispersion plate,
A wet oxidation method for wastewater, characterized in that the liquid flows down along the inner wall of the overflow pipe to disperse and supply the liquid to the upper part of the solid catalyst packed bed .   The wet oxidation method according to claim 1, wherein the liquid-liquid separation unit enables liquid accumulation. An apparatus for wet-oxidizing wastewater containing oxidizable substances by a gas-liquid counter-current system using a solid catalyst,
A gas-liquid dispersion member is installed above the solid catalyst packed bed in the wet oxidation reaction tower,
The gas-liquid dispersion member is a gas-liquid dispersion member comprising a dispersion plate and an overflow pipe for blocking the gas-liquid flow path, and performing dispersion supply by overflowing the liquid,
A gas-liquid separation unit that separates the gas-liquid in advance on the gas-liquid dispersion member;
A liquid conduction pipe is provided on the lower surface of the gas-liquid separation part, and the liquid is supplied from the gas-liquid separation part through the liquid conduction pipe to the gas-liquid dispersion member ,
The overflow pipe is formed by extending a pipe having the same cross-sectional shape as the hole above the hole drilled in the dispersion plate to a position higher than the lower end of the liquid conducting pipe. Wastewater wet oxidation treatment equipment. The wet oxidation processing apparatus according to claim 3 , wherein the gas-liquid separation unit forms a liquid pool.

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