JPH0642939B2 - Parallel flow type gas-liquid contactor and gas-liquid reactor - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a co-current type gas-liquid contactor for uniformly dispersing and contacting a gas in a liquid in a cocurrently rising flow, and a co-current type catalyst-filled co-current type applying its principle. The present invention relates to a gas-liquid reactor.

[Prior art]

For example, in the hydrogenation of unsaturated hydrocarbons such as dienes and acetylene, and the hydrogenation of unsaturated components in fats and oils and high molecular weight substances, a parallel flow type gas is used in which catalytic reaction is carried out while raising the gas and liquid in parallel flow. This is often done using a liquid contact device.
This gas-liquid contactor is basically composed of a cylindrical reaction container having a liquid inlet and a gas inlet at the bottom, and a gas disperser. Gas dispersion is often performed using a gas disperser, commonly known as a "sparger." The sparger is an annular or radial gas pipe having a large number of holes formed in the lower part of the apparatus, and the gas is distributed and supplied from the holes. The holes in the sparger are very small, because the velocity of the passing gas must be increased to increase the pressure loss in order to achieve uniform distribution of the gas.
Therefore, if foreign matter is mixed in the gas, it will cause clogging immediately. The larger holes not only make it difficult to uniformly disperse the gas, but also pose a problem of liquid flowing into the sparger. Moreover, since the pores of the sparger are not arranged uniformly on the cross section of the gas-liquid contactor, there is a natural limit to the uniformity of gas dispersion. Various perforated plates have been devised as gas dispersers other than spargers, but with conventional perforated plates, it was difficult to make the gas dispersion uniform due to uneven flow of gas. Whether using a sparger or a perforated plate, particularly in a co-current gas-liquid reaction apparatus of the type having a catalyst packed bed for gas-liquid reaction, the reaction rate is low due to the above-mentioned non-uniform dispersion of gas, The improvement was demanded.

[Problems to be Solved by the Invention]

The object of the present invention is to remedy the above-mentioned drawbacks of the prior art,
It is an object of the present invention to provide a co-current type gas-liquid contactor in which gas is evenly dispersed in a liquid. Another object of the present invention is to provide a co-current gas-liquid reaction device having an improved reaction rate.

[Means for Solving the Problems]

The first embodiment of the co-current type gas-liquid contactor of the present invention supplies a gas (8) and a liquid (9) from the lower part of a container (1), as shown in FIGS. 1 and 2. In a co-current type gas-liquid contactor for contacting gas-liquid while rising in co-current, a perforated plate (2A) through which a large number of pores (5A) are evenly formed in a plate that divides the container into upper and lower parts. In addition, a gas disperser provided with a liquid flow pipe (3A) for allowing only liquid to pass therethrough is arranged in the porous plate, and the pores (5A) of the porous plate are arranged.
The opening ratio is selected so that a gas retention layer (7) is formed on the lower side of the perforated plate as shown in FIG. A first aspect of the co-current gas-liquid reaction device of the present invention is the above first co-current gas-liquid contactor, wherein a catalyst packed bed (10) is provided above the gas disperser in the container (1). This layer is configured to carry out gas-liquid catalytic reaction. Although not essential for the perforated plate (2A), as shown in FIG. 1, a cylindrical skirt (4) extending downward from its edge is provided.
A) should be provided. This is a recommended aspect because the provision of the skirt allows the present invention to be carried out without modification by simply adding the gas disperser described above to the existing gas-liquid contactor. The second embodiment of the co-current type gas-liquid contact device of the present invention supplies the liquid (8) and the gas (9) from the lower part of the container (1) as shown in FIGS. 3 and 4. In a co-current type gas-liquid contactor in which gas and liquid are brought into contact with each other while rising in co-current, a perforated plate (3A) through which a large number of pores (5B) are evenly formed in a plate that divides the container into upper and lower parts. ) And a cylindrical skirt (4B) extending downwardly is provided on this perforated plate, and a plurality of slits (3B) are provided at equal intervals in the lower part of the skirt.
A gas disperser having a liquid flow path formed therein is arranged so that the aperture ratio of the pores (2A) of the perforated plate is such that a gas retention layer (7) is formed below the perforated plate. It is characterized by being selected in. A second aspect of the co-current gas-liquid reaction device of the present invention is the above-mentioned second co-current gas-liquid contactor, wherein a contact packing layer (10) is provided above the gas disperser in the container (1). It is configured to perform a gas-liquid contact reaction in this layer. The diameters and aperture ratios of the pores (5A, 5B) provided in the perforated plates (2A, 2B), and the flow passage cross-sectional area of the liquid flow passage pipe (3A) or slit (3B) through which only the liquid flows are the liquids to be contacted. And depending on the type of gas and their physical and chemical properties, select appropriately. Generally speaking, the diameter of the pores is in the range of 0.5 to 5 mm, and the aperture ratio of the pores to the area of the perforated plate excluding the liquid flow path tube is 0.05 to 5.0%.
From the above range, it is suitable to select the flow channel cross-sectional area of the liquid flow channel tube or slit from the range of 0.5 to 2 times the opening area of the pores. If the diameter of the pores is too small, it is difficult for the gas to pass therethrough and the thickness of the gas retention layer increases and there is a risk of overflow, and if it is too large the gas retention layer cannot be formed. The same applies to the aperture ratio. If the cross-sectional area of the liquid flow path is small, the flow velocity of the liquid passing therethrough becomes high, which causes uneven flow. As a result of the homogeneity, the gas distribution is still poor. The length of the liquid flow path pipe used in the first aspect must be longer than the height of the gas retention layer formed under the perforated plate, but is 1.3 times or more and about twice as long as the retention layer. Is suitable. The distance from the porous plate at the upper end of the slit used in the second aspect may be determined from the same viewpoint. The liquid and gas may be supplied to the device by any means, for example, gas and liquid may be mixed and supplied from one pipe, or gas and liquid may be supplied from different pipes. . The gas supply may be performed using a sparger (6) similar to the conventional device. In any case, it is necessary to consider that the gas does not directly enter the upper part of the perforations (2A, 2B) through the liquid flow pipe (3A) and the slit (3B). The co-current type gas-liquid contactor of the present invention includes a gas absorption device, an aeration and stirring device, an aeration device, a flotation apparatus, and a catalytic reaction device using a particulate catalyst (particle diameter of several hundreds of μm) in a fluidized bed. Can be used for INDUSTRIAL APPLICABILITY The parallel-flow gas-liquid contactor of the present invention can be applied to a catalytic reaction apparatus such as a hydrogenation reaction or a hydrodesulfurization reaction in which a granular or lumpy catalyst is used in a fixed bed.

[Work]

In the co-current type gas-liquid contactor of the present invention, whether the gas and the liquid are supplied from the same supply port or separately, as shown in FIG. To form a retention layer (7) under the perforated plate (2A) and move to the upper part of the container through the pores (5A) of the perforated plate, while the liquid flows in the liquid flow pipe (3A) or as indicated by the arrow. It flows through the slit into the upper part of the container separately from the gas. In this way, the gas and liquid are temporarily moved separately so that the liquid flow does not affect the gas flow, and a gas retention layer is formed under the perforated plate to form each pore. By making the gas passage conditions in the same, the gas flow through the pores of the perforated plate becomes uniform. Therefore, no appreciable drift occurs on the cross section of the perforated plate, and a uniform gas-liquid mixed flow rises in the container as indicated by the hatched arrow. Even when solids are mixed in the gas, most of them have a high sedimentation property such as iron rust, so there is no concern that they will rise above the gas retention layer and block the pores of the perforated plate. Since the co-current gas-liquid reaction apparatus of the present invention uses the above-mentioned gas-liquid mixing means and carries out the catalytic reaction under the condition that small bubbles are uniformly dispersed in the liquid, a large gas-liquid contact area can be obtained. There is less drift of the gas-liquid mixture through the catalyst layer and therefore the reaction efficiency is improved. Since this device can target liquids having a viscosity of 0.05 to 10,000 cps and a surface tension of 1 to 100 dyn / cm, practically all liquids can be handled. Specifically, they are various hydrocarbons such as LPG, gasoline, kerosene, light oil, and heavy oil, various organic compounds such as alcohols and fatty acids, water and aqueous solutions of various substances. These mixtures and emulsions and suspensions can also be processed with this device.

Comparative Examples 1 and 2 In order to examine the gas dispersion effect of a conventional sparger, as shown in FIGS. 6 and 8, a small-diameter ring sparger having a diameter of 250 mm or 70
A large diameter ring sparger of 0 mm was installed. The gas outlet of the sparger has a diameter of 2.5 mm, and the number of holes is 82 small diameter rings.
There are 100 large diameter rings. Water was introduced into this bubble column to a depth of 800 mm above the sparger, and air with a flow rate Q _G = 20 m ³ / hr (gas superficial velocity U _G = 0.7 cm / sec) was blown from the sparger to a height of 200 mm above the sparger. At the position of, the void fraction was measured over the diameter of the tower. "Void rate" means the ratio of air in a unit space of a mixed phase of water and air at a certain position in the tower. The value is calculated by arranging a gas detection electrode at that position, measuring the electrical resistance between the electrodes for a certain period of time, and utilizing the fact that the resistance value is different between gas passage and water passage. The results obtained were as shown in FIG. 7 for the small diameter ring in FIG. 6 and in FIG. 9 for the large diameter ring in FIG. These figures show that the gas rises strongly at the sparger blow position.

Comparative Example 3 Next, in order to examine the effect of the perforated plate, a perforated plate was added to the device of FIG. 8 to fabricate a gas-liquid contact device having the structure shown in FIG. The perforated plate is a disc having a diameter of 960 mm and 250 holes having a diameter of 4.0 mm. Air was supplied at a rate of Q _Q = 10 m ³ / hr (U _G = 0.35 m / sec), and the void fraction in the diametrical direction of the column was measured at a position of 200 mm in height on the perforated plate. The results shown in FIG. 11 were obtained. According to this, although there is no noticeable annular strong air blow-up as in FIG. 9, it is understood that annular drift is still occurring.

Example 1 Four holes each having a diameter of 150 mm are formed in a disk having a diameter of 900 mm at symmetrical positions from the center, and a pipe having a length of 17 mm is attached to each of them to form a liquid flow path pipe, and at the edge of the disc. Height 195
A mm skirt is provided. As a gas flow path, 769 pores having a diameter of 2.0 mm were formed in this disk at equal intervals. The cross-sectional area ratio of the liquid channel is 11%, and the aperture ratio of the pores is 0.22%. This gas disperser was attached to the lower part of a column having an inner diameter of 1000 mm, a porous plate was filled with water having a water depth of 800 mm, and air was supplied from below. As the gas flow rate increased, the height of the gas retention layer formed below the perforated plate increased. The situation is as shown in FIG. Gas flow rate of 6 to 32 m ³ /
The outflow of air from the perforated plate was uniform over the entire cross section in the range of the experiment performed by changing m ² · hr.

Second Embodiment A device having a shape similar to that of the device assembled in the above-described first embodiment but slightly smaller is manufactured. That is, four holes each having a diameter of 100 mm are formed in a disk having a diameter of 500 mm, a tube having a length of 120 mm is attached at a symmetrical position from the center to form a liquid flow path tube, and a hole having a diameter of 2.0 mm is formed in the remaining portion. A gas disperser was prepared by separating the pieces. The area ratio of the liquid channel is 13.2%, and the aperture ratio of the pores is 0.14%. The above gas disperser is placed in the lower part of the tower with an inner diameter of 600 mm,
Below that, the small diameter (200 mm) ring sparger used in Comparative Example 1 was attached. Water and air were supplied to this apparatus, and the air supply rate was changed as follows while the water supply rate was kept constant. The void fraction in the diameter direction of the tower was measured at a height of 250 mm on the porous plate. The results are shown in FIGS. 14, 15 and 16. It can be seen from this figure that uniform gas-liquid mixing is carried out over the entire cross section of the column regardless of the gas flow rate.

Example 3 In the apparatus assembled in Example 2, a packed bed of the following catalyst was provided above the gas disperser, and ethylbenzene was produced by hydrogenation of styrene under the following conditions. Reaction material: Styrene dissolved in light naphtha (initial distillation 38 ° C, end point 132 ° C (specific gravity 0.589) at a ratio of 7.5%) Hydrogen gas: supplied from a cylinder Temperature: 60 ° C Pressure: 5.5 kg / Cm ² G catalyst: 5% by weight of palladium supported on alumina,
160 kg of cylindrical catalyst (commercial product) with diameter and height of 3 mm each
Packing (packed bed height 88 cm) Liquid flow rate: 1.27 m ³ / hr Gas flow rate: 2.8 Nm ³ / hr After cooling the reaction liquid and separating the gas, check the amount of unreacted styrene by gas chromatography. The reaction rate of hydrogenation was calculated by The value is shown together with the elapsed time in comparison with the data when only the perforated plate was used according to the present invention.

【The invention's effect】

The gas disperser according to the invention is free from clogging, increases the load on the gas supply means and does not cause drift. The parallel-flow gas-liquid contactor of the present invention which employs this gas disperser has a more uniform dispersion of gas in the liquid as compared with the conventional apparatus, and causes almost no uneven flow on the cross section of the apparatus. Therefore, the contact area between the liquid and the gas is large and the efficiency is high. Further, in the gas-liquid reaction device in which the catalyst packed layer is provided in the parallel flow type gas-liquid contactor, the reaction efficiency is improved by improving the catalytic efficiency of the gas-liquid in the catalyst packed layer. Particularly when applied to an exothermic reaction such as a hydrogenation reaction, it is possible to suppress the generation of an unwanted by-product due to a part called a hot spot where the temperature rises partially.

[Brief description of drawings]

1 and 2 are views for explaining one example of the co-current gas-liquid contact device and the reaction device of the present invention. FIG. 1 is a longitudinal sectional view, and FIG. It is a transverse cross-sectional view of FIG. FIGS. 3 and 4 are views for explaining another example of the co-current gas-liquid contact device and the reaction device of the present invention, and FIG. 3 is a longitudinal sectional view similar to FIG. Fig. 4 is Fig. 2 and 3
FIG. 2 is a transverse sectional view taken along the line II-II. FIG. 5 is a cross-sectional view showing how gas is dispersed in the liquid in the apparatus of FIG. 1 in order to explain the operation of the present invention. FIG. 6 and FIG. 8 are vertical cross-sectional views of a device manufactured to examine the effect of the conventional gas disperser. FIG. 7 and FIG. 9 are graphs examining the state of gas-liquid mixing in the devices of FIGS. 6 and 8, respectively. FIG. 10 is a vertical cross-sectional view corresponding to FIGS. 6 and 8 of an apparatus manufactured to see the effect of the conventional gas disperser. FIG. 11 is a graph corresponding to FIGS. 7 and 9, which examines the state of gas-liquid mixing in the apparatus of FIG. FIG. 12 is a graph showing changes in the thickness of the gas retention layer formed under the perforated plate when the gas supply amount is changed in the apparatus of the present invention. FIG. 13 is a longitudinal sectional view of the device of the present invention, corresponding to FIGS. 6, 8 and 10. FIGS. 14, 15, and 16 are all shown in FIG.
It is a graph which shows the uniformity of gas-liquid mixing in the apparatus of a figure. DESCRIPTION OF SYMBOLS 1 ... Container, 2A, 2B ... Perforated plate 3A ... Liquid flow path tube, 3B ... Slit 4A, 4B ... Skirt 5A, 5B ... Pore 6 ... Sparger, 7 ... Gas retention layer 8 ...... Liquid, 9 ...... Gas 10 ...... Catalyst packed bed

Claims (6)

[Claims] 1. A co-current gas-liquid contactor for supplying gas and liquid from the lower part of a container to bring gas and liquid into contact with each other while ascending in a co-current manner. Is a perforated plate through which the gas flows out evenly, and a gas disperser provided with a liquid passage tube for passing only the liquid is arranged in the perforated plate. Is selected so that a gas retention layer is formed on the lower side of the perforated plate. 2. The diameter of the pores is in the range of 0.5-5 mm,
The aperture ratio of the pores with respect to the area of the perforated plate excluding the liquid flow path tube is in the range of 0.05 to 5%, and the cross-sectional area of the liquid flow path tube (when there are two or more tubes is small) The opening area of the hole is 0.
The gas-liquid contact device according to claim 1, which is 5 to 2 times. 3. The parallel flow gas-liquid reaction apparatus according to claim 1, wherein a catalyst-packed layer is provided on an upper portion of the container, and the gas-liquid catalytic reaction is carried out in this layer. 4. A parallel flow type gas-liquid contactor for supplying gas and liquid from the lower part of a container to bring gas and liquid into contact with each other while ascending in parallel flow. To form a perforated plate through which the gas flows out uniformly, and the perforated plate is provided with a cylindrical skirt extending downward, and a plurality of slits are formed under the skirt at equal intervals to form a liquid flow path. A gas-liquid contactor comprising a disperser, wherein the aperture ratio of the pores of the perforated plate is selected so that a gas retention layer is formed below the perforated plate. 5. The diameter of the pores is in the range of 0.5-5 mm,
The aperture ratio of the pores to the area of the perforated plate is 0.05 to 5.0.
%, And the total liquid channel cross-sectional area of the slit is 0.5 to 2 times the opening area of the pores. 6. The parallel flow type gas-liquid reaction apparatus according to claim 4, wherein a catalyst-filled layer is provided on the upper part of the container, and the gas-liquid catalytic reaction is carried out in this layer.