JP2003340471A - Wet catalytic oxidation column - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new wet catalytic oxidation column in which clogging and enlargement of pressure loss can be avoided effectively. <P>SOLUTION: An oxidation catalyst 3 for oxidatively decomposing organic matter contained in hydrothermally treated waste liquid is housed in a column body 2 where the hydrothermally treated waste liquid is introduced from the bottom 4 together with oxygen and made to flow upward and the organic matter-decomposed waste liquid is discharged from the top 5. The catalyst 3 is formed into a honeycombed shape extending continuously from the bottom 4 to the top 5. As a result, the enlargement of pressure loss and the clogging phenomenon can be avoided surely in this catalytic oxidation column. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet catalytic oxidation tower used in an organic waste hydrothermal treatment system for hydrothermally treating organic waste liquid, sewage sludge and the like.

[0002]

2. Description of the Related Art FIG. 4 shows such a conventional organic waste hydrothermal treatment system, in which waste liquid such as harmful organic waste liquid and sewage sludge stored in a waste liquid tank a is transferred to a hydrothermal tower b.
The hydrothermal reaction treatment is carried out at 1, and the oxidation treatment is carried out at the oxidation tower c so as to be decomposed into harmless water and gas.

That is, the waste liquid containing organic substances discharged from a factory or the like is first temporarily stored in the waste liquid tank a and then sequentially withdrawn from the waste liquid tank a by the high-pressure pump d and simultaneously pressurized to a high pressure. Is sent to a preheater e, where it is heated to a high temperature by an electric heater f while being heated by a water heat tower b.
Sent to. The waste liquid sent to the hydrothermal tower b is in a subcritical state, and the organic matter contained therein is completely dissolved in the solution, and then the waste liquid is oxidized together with oxygen (air) sent from the oxygen supply line g. The organic matter, which is sent into the column c and dissolved under an oxidation catalyst such as a titania-supported catalyst or an α-alumina-supported catalyst, reacts with oxygen to be decomposed into water and harmless gases such as CO ₂ and N ₂ . The mixture of water and gas exits the oxidation tower c and then passes through a cooler h to be cooled, and then passes through a pressure regulating valve i and a gas-liquid separator j to be gas-liquid separated, and the gas remains as it is. The water is released into the atmosphere and is sequentially stored in the treatment liquid tank k. The oxygen supply line g is composed of an air cylinder 1, a pressure reducing valve m, a flow rate controller n, a check valve o, etc., and can supply an optimum amount of oxygen into the waste liquid according to the flow rate of the waste liquid. It is like this.

[0004]

By the way, the oxidation tower c for oxidizing the waste liquid which has undergone the hydrothermal reaction has a particle size of about 1 to 5 mm in a vertical tower main body p. Of the granular catalyst q, and the waste liquid introduced from the lower end in the tower body p is subjected to an oxidation treatment while flowing in an upward flow, and then is discharged from the top portion thereof, so that it is dissolved in the waste liquid to be treated. When a large amount of suspended organic matter or inorganic matter is contained as a suspension (solid matter), it becomes clogged in the gaps of the granular catalyst q, leading to an increase in pressure loss and clogging, resulting in liquid or gas. There is a problem that the flow of is significantly deteriorated.

Therefore, it is possible to avoid an increase in pressure loss and clogging by increasing the particle size of the granular catalyst q and increasing the gap between them, but in that case, the contact area between the waste liquid and the catalyst q is reduced and oxidation is performed. Since the efficiency is lowered, a new problem arises that the oxidation tower c has to be made larger than before by that amount.

Therefore, the present invention has been devised in order to effectively solve such a problem, and its purpose is to provide a novel wet method capable of effectively avoiding clogging and increase in pressure loss. A catalytic oxidation tower is provided.

[0007]

In order to solve the above-mentioned problems, the wet catalytic oxidation tower according to the present invention, as shown in claim 1, introduces a waste liquid containing a hydrothermally treated organic substance together with oxygen, and In a wet catalytic oxidation tower that oxidizes and decomposes under a catalyst and flows out, the waste liquid is introduced together with oxygen from the bottom, flows in an upward flow, and flows out from the top. In addition to accommodating, at least a part of the oxidation catalyst is formed of a honeycomb catalyst having a honeycomb shape in cross section. Specifically, as described in claim 2, an oxidation catalyst for oxidatively decomposing the organic matter is accommodated in a tower main body in which the waste liquid is introduced together with oxygen from the bottom, flows in an upward flow and flows out from the top. At the same time, the oxidation catalyst is made of a honeycomb catalyst having a honeycomb-shaped cross section that continuously extends from the bottom to the top.

As a result, not only the waste liquid but also the suspension (solid matter) contained in the waste liquid can smoothly flow through the inside thereof, so that an increase in pressure loss and a clogging phenomenon can be effectively avoided. Is possible.

If the honeycomb catalyst is composed of a plurality of divided bodies in the longitudinal direction of the tower body as described in claim 3, the honeycomb catalyst can be easily stored and replaced in the tower body. be able to.

The wet catalytic oxidation tower according to the present invention comprises:
In a wet catalytic oxidation tower in which a waste liquid containing a hydrothermally treated organic substance is introduced together with oxygen, and is oxidatively decomposed under a catalyst to flow out, the waste liquid is introduced together with oxygen from the bottom, and the upward flow In the main body of the tower flowing out from the top, while containing an oxidation catalyst that oxidatively decomposes the organic matter, the oxidation catalyst, the honeycomb catalyst having a cross-section honeycomb shape accommodated on the bottom side, and above the honeycomb catalyst. And a granular catalyst filled in.

That is, the inventors of the present invention have studied in detail the increase of pressure loss and the clogging phenomenon in the conventional wet catalytic oxidation tower, and as a result, the place where the phenomenon occurs is not the entire oxidation tower but mainly the bottom of the oxidation tower. That is, it turned out to be the inlet part of the waste liquid. Therefore, the present invention uses a honeycomb catalyst having a honeycomb cross-section instead of the conventional granular catalyst as the catalyst located at the bottom of the oxidation tower as described above, thereby sacrificing the original oxidation efficiency. It is possible to effectively avoid an increase in pressure loss and a clogging phenomenon.

More specifically, when the ratio of the honeycomb catalyst to the granular catalyst in the height direction is set in the range of 1: 9 to 3: 7, the above effect can be obtained. It becomes possible to exert outstandingly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

Wet catalytic oxidation tower 1 according to the first embodiment
1 is a schematic vertical sectional view of the honeycomb catalyst of the wet catalytic oxidation tower in FIG. 1, and FIG. 3 is a vertical sectional view of another example of the honeycomb catalyst in FIG. ,
FIG. 4 is a sectional view showing a modification of the honeycomb shape of the honeycomb catalyst shown in FIG.

As shown in FIG. 1, the wet catalytic oxidation tower 1 of the present embodiment has an oxidation catalyst 3 in a cylindrical tower body 2 made of corrosion-resistant metal (stainless steel or the like) which is vertically installed. The waste liquid discharged from the hydrothermal tower b is introduced from the waste liquid inlet 4 provided at the bottom of the tower main body 2, and the waste liquid outlet 5 is provided at the top of the inside while flowing in the upward flow. It is supposed to flow out from. Here, the size of the tower main body 2 is not particularly limited because it varies depending on the size of the area to be installed, the amount of waste liquid to be treated, etc., but is shown in order to increase the contact time between the waste liquid and the oxidation catalyst 3. For example, height 1000mm, inner diameter 36mm
A long and narrow pipe body has been widely used conventionally. Further, the tower main bodies 2 are usually provided by connecting several to several tens of them in series in a connected state (four in the present embodiment).

On the other hand, as shown in FIG. 2, the oxidation catalyst 3 is composed of a honeycomb catalyst having a honeycomb-shaped cross section which continuously extends from the bottom to the top. That is, as shown in the figure, the honeycomb catalyst 3 has a large number of linear channels 7 having a rectangular cross section in a honeycomb shape in a tubular catalyst body 6 whose outer diameter is slightly smaller than the inner diameter of the tower body 2. It is made to pass through, and the waste liquid that has flowed in from one end face thereof can be passed through the respective flow paths 7, 7 ... And discharged from the other end face. The catalyst body 6 itself is made of a porous material having fine pores. For example, mix titania powder and acid clay with an appropriate amount of binder, plasticizer, lubricant, water, etc.
The kneaded clay is extruded into a honeycomb section and fired.
By supporting ruthenium metal having an oxidation catalyst function on this fired body, the catalyst body 6 can be easily obtained.

In the wet catalytic oxidation tower 1 having such a structure, the waste liquid introduced from the waste liquid supply line L1 extending from the side of the hydrothermal tower b is supplied with the oxygen supplied from the oxygen supply line g. It is introduced together with (air) from the waste liquid inlet 4 at the bottom thereof, and while flowing through the inside thereof in an upward flow, the organic matter contained by the oxidation catalyst 3 is decomposed into harmless water and gas by the oxidation catalytic reaction, and then the Waste liquid outlet 5
It flows out to the drain line L2 side from this, but in the present embodiment, since a honeycomb catalyst having a honeycomb cross section is used as the oxidation catalyst 3 instead of the conventional granular catalyst, it has flowed in. Since not only the waste liquid but also the suspension contained in the waste liquid flows smoothly, it is possible to avoid an increase in pressure loss due to clogging.

That is, as described above, the phenomenon of increase in pressure loss due to clogging is caused by the fact that some of the organic substances that cannot be completely dissolved in the hydrothermal tower b and inorganic substances that are not dissolved in the hydrothermal reaction in the first place are solid (suspension). ) As it is, the tower body 2
After being sent into the column, a part of it does not survive the flow of the waste liquid and stays in the gaps of the granular catalyst as it is to cause clogging. By providing the honeycomb catalyst 3 having a honeycomb shape in cross section, the flow of the waste liquid at the bottom of the tower main body 2 becomes smooth, and the suspension that could not be completely discharged together with the waste liquid also passes through the tower main body 2 as it is and flows out. Is possible.

As a result, an increase in pressure loss and a clogging phenomenon can be effectively avoided, and long-term stability and reliability are greatly improved.

In this embodiment, the honeycomb catalyst used as the oxidation catalyst 3 is formed by one rod continuously extending from the bottom to the top of the tower body 2.
As shown in FIG. 3 (B), this rod may be formed of a plurality of divided bodies 3a, 3a ... In the longitudinal direction. That is, in the above embodiment, FIG.
As shown in Fig. 4, when accommodating and exchanging this in the tower body 2, a space more than the length is required at the upper part or the lower part, but this rod is divided into a plurality of pieces in the longitudinal direction. 3a, 3a ... As shown in FIG. 3 (B), since it is possible to carry out the accommodation / replacement work for each one of the divided bodies 3a, the work can be performed easily even in a narrow space. Is possible. Moreover, usually, the clogging phenomenon that causes the increase of the pressure loss often occurs in a part of the tower body 2, especially in the vicinity of the waste liquid inlet 4, so that even if the clogging occurs, that part is divided. Only the body 3a needs to be replaced, and efficient catalyst utilization can be achieved. Also, in terms of manufacturing, it is cheaper and more costly to configure the divided bodies 3a, 3a ...
It can be easily manufactured.

In the present embodiment, the honeycomb catalyst 3 having the flow passage 7 having a rectangular cross section is used, but the flow passage shape is, for example, as shown in FIG. 4, a hexagonal cross section and other polygonal shapes. Of course, the cross section may be circular. Also, the size of the flow path 7 is, for example, 50 to
It is considered that the one with about 100 mesh is often used.

Next, another embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 5 is a schematic vertical sectional view of a wet catalytic oxidation tower according to the second embodiment, and FIG. 6 is a partially cutaway perspective view showing a honeycomb catalyst of the wet catalytic oxidation tower in FIG. still,
The same members as those in FIGS. 1 to 4 are denoted by the same reference numerals, and the description of the same members will be omitted.

As shown in FIG. 5, the wet catalytic oxidation tower 51 of this embodiment has an oxidation catalyst 53 accommodated in the tower main body 2, and the waste liquid discharged from the hydrothermal tower b is converted into a tower. It is adapted to be introduced from a waste liquid inlet 4 provided at the bottom of the main body 2, flow upward in the tower main body 2, and flow out from a waste liquid outlet 5 provided at the top thereof.

On the other hand, the oxidation catalyst 53 comprises a honeycomb catalyst 57 having a honeycomb-shaped cross section made of a titania carrier or α-alumina carrier, and a granular catalyst 58 having a particle size of about 1 to 5 mm. Is housed in the waste liquid inlet 4 portion in the tower body 2, and the granular catalyst 58 is housed so as to be filled from the upper portion to the waste liquid outlet 5.

For example, as shown in FIG. 6, the honeycomb catalyst 57 has a straight channel 69 having a rectangular cross section in a tubular catalyst body 56 having an outer diameter slightly smaller than the inner diameter of the tower body 2. A large number of honeycombs are passed through, and the waste liquid flowing in from one end face of each of the channels 69, 69
It can be discharged from the other end surface after passing through. still,
The catalyst body 56 itself is made of a porous body having fine pores. For example, a cup clay obtained by mixing and kneading titania powder having an oxidation catalyst function and acid clay with an appropriate amount of a binder, a plasticizer, a lubricant, water, etc. is extruded into a honeycomb shape in cross section and fired. By supporting a ruthenium metal having a function, the catalyst main body 56 can be easily obtained.

Further, as shown in FIG. 5, the length of the honeycomb catalyst 57 is about 1/10 of the tower body 2 and is about 100 m.
It is about m, and the ratio is in the range of 9: 1 to 7: 3 with respect to the granular catalyst 7 above it. That is,
When the ratio of the honeycomb catalyst 4 is less than 1/9, the effect of preventing clogging is poor as described later, and when the ratio is more than 3/7, the contact area between the entire catalyst and the waste liquid decreases. This is because the oxidation efficiency may deteriorate.

In the wet catalytic oxidation tower 51 having such a structure, the waste liquid introduced from the waste liquid supply line L1 extending from the side of the hydrothermal tower b is supplied with the oxygen supplied from the oxygen supply line g. It is introduced together with (air) from the waste liquid inlet 4 at the bottom thereof, and while flowing through the inside thereof in an upward flow, the organic substances contained by the oxidation catalyst 53 are decomposed into harmless water and gas by the oxidation catalytic reaction, and then the Although it flows out from the waste liquid outlet 5 to the drain line L2 side, in the present embodiment, since the honeycomb catalyst 57 having a honeycomb shape in cross section is used as the oxidation catalyst 53 near the waste liquid inlet 4, clogging occurs. The waste liquid can be smoothly passed over a long period of time without causing an increase in pressure loss due to.

That is, as described above, the phenomenon such as an increase in pressure loss due to clogging is caused by the fact that a part of the organic matter which could not be completely dissolved in the hydrothermal tower b or the inorganic matter which is not dissolved in the hydrothermal reaction in the first place is solid (suspended After being sent as it is into the tower main body 2, a part of it is not collected in the flow of the waste liquid and remains at the bottom of the tower main body 2 as it is. However, like this embodiment,
By providing the honeycomb catalyst 57 having a large number of linear flow paths 69 at the bottom of the tower body 2, the flow of the waste liquid at the bottom of the tower body 2 becomes smooth, and the suspended matter that cannot be completely discharged together with the waste liquid remains as it is. It becomes possible to pass through the tower main body 2 and flow out.

As a result, the increase in pressure loss and the clogging phenomenon can be effectively avoided without sacrificing the original oxidation efficiency, and the long-term stability and reliability are significantly improved. Become.

In the present embodiment, the honeycomb catalyst 53 having the flow passage 69 having a rectangular cross section is used, but the flow passage shape is, for example, as shown in FIG. 4, a hexagonal cross section and other polygonal shapes. Of course, the cross section may be circular. Further, the size of the flow path 69 may be any size as long as the granular catalyst 58 does not enter as it is, and it is considered that, for example, a size of about 50 to 100 mesh is often used.

[0032]

EXAMPLES Specific examples and comparative examples of the present invention will be described below.

(Example 1) In a tower body having a height of about 1000 mm, a 100-mesh Ru-supported TiO ₂ honeycomb catalyst was placed all over, and sewage sludge containing 6% solids was added at 280 ° C. The solid content was solubilized by hydrothermal treatment at 9 MPa for 10 minutes. In this waste liquid that has been hydrothermally treated,
A suspension of inorganic substances and organic substances that was not decomposed by the hydrothermal reaction remained at 10000 mg / L. Next, from the bottom of the tower main body, this waste liquid was heated at 220 ° C. and 3 MPa for 0.5 minutes per minute.
At the same time, air was flown at L / min and 80 L / min, and changes in pressure loss between the waste liquid inlet and the outlet were examined.

As a result, there was no change in the pressure loss (0.3 Kg / cm ² ) between the waste liquid inlet and the outlet. Also,
After dismantling the wet catalytic oxidation tower after measuring the pressure loss,
No clogging was found in the honeycomb catalyst.

(Embodiment 2) T supported on Ru of 50 mesh
The pressure loss between the waste liquid inlet and the outlet was the same as in Example 1 except that the iO ₂ honeycomb catalyst was used and the waste liquid after the hydrothermal treatment was simultaneously flowed at 1.0 L / min and air at 160 L / min. I examined the change of. As a result, similar to Example 1, no change was seen in the pressure loss between the waste liquid inlet and the outlet. Further, as a result of actually dismantling the wet catalytic oxidation tower after measuring the pressure loss, no clogging was observed.

(Example 3) A TiO ₂ honeycomb catalyst having a height of about 100 mm and 100 mesh and carrying Ru was placed in the waste liquid inlet portion of a tower body having a height of about 1000 mm, and the upper space thereof had a diameter of about 2 mm. A wet catalytic oxidation tower filled with Ru-supported TiO ₂ granular catalyst was prepared. Next, from the bottom of the tower body, the same waste liquid as in Example 1 was added at 220 ° C. and 3 MP.
a at 0.5 L / min and air at 80 L / m
In, the mixture was poured at the same time and the change in pressure loss between the waste liquid inlet and the outlet was examined.

As a result, there was no change in the pressure loss (1 Kg / cm ² ) between the waste liquid inlet and the outlet. When the wet catalytic oxidation tower was disassembled after the pressure loss measurement, neither the honeycomb catalyst nor the granular catalyst was found to be clogged.

(Example 4) Ru-supported T of 50 mesh
R2 with a diameter of about 4 mm is used with an iO ₂ honeycomb catalyst
Using a TiO ₂ granular catalyst supported by u, the waste liquid after hydrothermal treatment was 1.0 L / min, and the air was 160 L / min.
The change in pressure loss between the waste liquid inlet and the outlet was examined under the same conditions as in Example 3 except that they were simultaneously poured in. as a result,
Similar to Example 3, there was no change in the pressure loss between the waste liquid inlet and the outlet. In addition, as a result of actually dismantling the wet catalytic oxidation tower after measuring the pressure loss, no clogging was observed in either the honeycomb catalyst or the granular catalyst.

(Comparative Example 1) The same conditions as in Example 1 except that a wet catalytic oxidation tower was prepared by filling the entire tower body shown in Example 1 with a TiO ₂ granular catalyst having a diameter of about 2 mm and carrying Ru. The waste liquid was poured in and the change in pressure loss between the waste liquid inlet and the outlet was examined. As a result, after 15 minutes, a pressure loss of 5 kg / cm ² or more occurred at the waste liquid inlet and the waste liquid outlet. In addition, as a result of actually dismantling the wet catalytic oxidation tower after measuring the pressure loss, clogging due to the suspended matter occurred mainly between the granular catalysts near the waste liquid inlet.

[0040]

In summary, according to the present invention, since the honeycomb catalyst is arranged in at least a part of the tower body, the flow of the waste liquid in the tower body becomes smooth, and the increase of the pressure loss and the clogging phenomenon are effectively prevented. It has an excellent effect that it can be avoided.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a wet catalytic oxidation tower according to a first embodiment.

FIG. 2 is a partially cutaway perspective view showing a honeycomb catalyst of the wet catalytic oxidation tower in FIG.

FIG. 3 is a vertical cross-sectional view showing another example of the honeycomb catalyst shown in FIG.

FIG. 4 is a cross-sectional view showing a modification of the honeycomb shape of the honeycomb catalyst shown in FIG.

FIG. 5 is a schematic vertical sectional view of a wet catalytic oxidation tower according to a second embodiment.

6 is a partially cutaway perspective view showing a honeycomb catalyst of the wet catalytic oxidation tower in FIG.

FIG. 7 is an overall configuration diagram showing an example of a conventional organic waste hydrothermal treatment system.

[Explanation of symbols]

1,51 Wet catalytic oxidation tower 2 tower body 3,53 Oxidation catalyst (Honeycomb catalyst) 3a division 4 Waste liquid inlet (bottom) 5 Waste liquid outlet (top) 57 Honeycomb catalyst 58 Granular catalyst

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiichi Miwa             Stone, Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa             Kawashima Harima Heavy Industries Co., Ltd. Machinery and plant opening             In the departure center F term (reference) 4D050 AA12 AB11 BB01 BC06 BD02                       BD03 BD06 CA01 CA20                 4D059 AA03 BC01 DA47 DA70                 4G069 AA03 AA11 BA04A BA04B                       BB02A BB02B BC70A BC70B                       CA05 CA07 DA06 EA02X                       EA02Y EA18 EB14Y EB18Y                       EE08

Claims (5)

[Claims] 1. In a wet catalytic oxidation tower in which a waste liquid containing a hydrothermally treated organic substance is introduced together with oxygen, and this is oxidatively decomposed under a catalyst to flow out, the waste liquid is introduced together with oxygen from the bottom, and this is flowed upward. Wet catalytic oxidation characterized by accommodating an oxidation catalyst for oxidatively decomposing the organic matter in the tower body flowing at the top and flowing at the top, and at least a part of the oxidation catalyst is formed by a honeycomb catalyst having a honeycomb shape in cross section. Tower. 2. In a wet catalytic oxidation tower in which a waste liquid containing a hydrothermally treated organic substance is introduced together with oxygen, and this is oxidatively decomposed under a catalyst to flow out, the waste liquid is introduced together with oxygen from the bottom, and this is flowed upward. In the tower body flowing at the top and flowing out from the top, while accommodating the oxidation catalyst for oxidative decomposition of the organic matter, the oxidation catalyst is composed of a honeycomb catalyst having a cross-section honeycomb shape continuously extending from the bottom to the top. A wet catalytic oxidation tower characterized by: 3. The wet catalytic oxidation tower according to claim 2, wherein the honeycomb catalyst is formed of a plurality of divided bodies divided in the longitudinal direction. 4. In a wet catalytic oxidation tower in which a waste liquid containing a hydrothermally treated organic substance is introduced together with oxygen, and is oxidatively decomposed under a catalyst to flow out, the waste liquid is introduced together with oxygen from the bottom portion, and the waste liquid is upwardly flowed. In the main body of the tower flowing out from the top, while containing an oxidation catalyst that oxidatively decomposes the organic matter, the oxidation catalyst, the honeycomb catalyst having a cross-section honeycomb shape accommodated on the bottom side, and above the honeycomb catalyst. 1. A wet catalytic oxidation tower comprising a granular catalyst filled in 5. The wet catalytic oxidation tower according to claim 4, wherein the ratio of the honeycomb catalyst and the granular catalyst in the height direction is in the range of 1: 9 to 3: 7.