JP5358498B2 - Catalyst filling method - Google Patents

Description

  The present invention relates to a method for filling a catalyst in each reaction tube of a fixed bed multitubular reactor used on an industrial scale.

  As a method of filling a solid bed such as a catalyst into a fixed bed multitubular reactor, a method of dropping and filling solid particles from the upper end opening of each reaction tube is common. In addition, the fixed-bed multitubular reactor used on an industrial scale has hundreds to tens of thousands of reaction tubes, and the catalyst filling method for each reaction tube is simpler and easier for each reaction tube. There are demands for a small filling height of the catalyst layer and variations in pressure loss, and simplification of the filling operation.

In Patent Document 1, when the unsaturated aldehyde production catalyst or unsaturated carboxylic acid production catalyst produced multiple times is filled in each reaction tube of a fixed bed multitubular reactor, it does not depend on the bulk density of the catalyst. The catalyst is placed in the reaction tube so that the filling weight of the catalyst filling one reaction tube is within a range of 99 to 101% with respect to the average value of the filling weights of the catalyst filling each reaction tube. After weighing each time, the catalyst is added to each catalyst so that the rate at which the catalyst is filled into one reaction tube is within a range of 80 to 120% with respect to the average value of the rates at which each reaction tube is filled. A method is described in which, by filling each reaction tube, the variation in pressure loss in each reaction tube after filling the catalyst is satisfactorily suppressed, and the catalyst is filled more simply.
Further, in Patent Document 2, a catalyst can be supplied to each reaction tube at a constant supply speed by a conveyor, so that the time for supplying the catalyst to the reaction tube can be shortened and the labor of the operator can be reduced. A catalyst filling machine that can suppress variations in catalyst layer pressure loss is described.

JP 2009-82865 A JP-A-11-333282

  However, the above-described conventional methods have a problem that the catalyst filling amount must be measured for each reaction tube, and it is difficult to adjust the height of the catalyst packed bed in each reaction tube to a predetermined height. It has been difficult to solve problems such as shortening the time for supplying the catalyst to the pipe, reducing the labor of the worker, and variations in catalyst layer pressure loss.

  An object of the present invention is a catalyst mainly used in a fixed bed multi-tubular reactor that shortens the time for supplying a catalyst to a reaction tube, reduces the labor of an operator, and suppresses variations in catalyst layer pressure loss. It is to provide a filling method.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have used a diffusion-reflective photoelectric sensor up to a predetermined height in a reaction tube when filling a catalyst in each reaction tube of a fixed bed multitubular reactor. Inserting, detecting the catalyst height with the photoelectric sensor, and finding that the above object can be achieved by filling each reaction tube with the catalyst so as to stop the filling at a predetermined height, The present invention has been completed.

That is, the catalyst filling method of the present invention has the following configuration.
(1) A method of filling from above the reaction tube a solid catalyst in the reaction tube, the White paper as a standard detected object, have a detection distance range of 90～1000Mm, was and covered with a protective tube Filling the catalyst with a diffuse reflection type photoelectric sensor inserted in the reaction tube, the photoelectric sensor detects the catalyst filling height, and stops filling the catalyst when the catalyst filling height reaches the set value It is allowed, and the air from above the protective tube, an inert gas or filling a catalyst, wherein you route these mixed gases.
(2) The catalyst filling method according to (1), further comprising control means for stopping filling of the catalyst into the reaction tube based on the detection signal output from the photoelectric sensor.
(3) Stop filling the reaction tube with the catalyst when the amount of light received by the photoelectric sensor reflected downward from the photoelectric sensor is reflected by the surface of the catalyst and returns to the light receiving unit exceeds a threshold value. The catalyst charging method according to any one of (1) and (2), comprising a control means for controlling the catalyst .

According to the present invention, when filling a catalyst in each reaction tube of a fixed-bed multitubular reactor used on an industrial scale, the catalyst layer height in each reaction tube after filling the catalyst is not measured without measuring the weight of the catalyst in advance. The height can be set to a predetermined height, and the catalyst can be filled more easily. As a result, variations in pressure loss are well suppressed, and the catalyst distribution in each reaction tube is likely to be the same, preventing reaction states from differing from one reaction tube to another and facilitating temperature adjustment for the reaction tubes. Therefore, there is an effect that the cost required for the catalyst can be reduced by using the catalyst in each reaction tube until it reaches the end of its life.
Further, as described in (4) above, when the photoelectric sensor in the reaction tube is covered with a protective tube and air, an inert gas, or a mixed gas thereof is sent into the protective tube from above, The dust rising in the reaction tube can prevent the detection light of the photoelectric sensor and the sensitivity of the light receiving unit from being lowered, so that there is an effect that a stable catalyst filling operation can be performed over a long period of time.

It is explanatory drawing which shows one Embodiment of this invention. It is sectional drawing which shows an example of the protective tube in this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

  As shown in the figure, in the catalyst filling method of the present invention, a diffuse reflection type photoelectric sensor 1 is inserted or installed from above into a cylindrical reaction tube 10 of a fixed bed multitubular reactor, and is also solid from above. The catalyst 3 is conveyed by the belt conveyor 4 and dropped below the reaction tube 10 to be filled. When the catalyst 3 reaches the set catalyst filling height, the photoelectric sensor 1 detects the catalyst filling height and stops the catalyst filling.

  The photoelectric sensor 1 in the present invention uses light such as visible light and infrared light as a light source, emits this as signal light from a detection unit (light projecting unit), and detects light reflected from a detection object by a light receiving unit. A diffuse reflection photoelectric sensor.

  By using such a photoelectric sensor 1, detection can be performed without contacting the catalyst, so that neither the catalyst nor the sensor itself is damaged. Moreover, since it detects by the surface reflection to a catalyst, there exists an advantage that the filling height of a catalyst can be detected correctly. Further, the sensor 1 has an advantage that it has a long life and requires little maintenance.

  As a method for filling the catalyst, the photoelectric sensor 1 is inserted to a predetermined height of the reaction tube 10 with the detection unit and the light receiving unit facing downward in the reaction tube 10, and then filling of the catalyst 3 is started. The filling height of the catalyst 3 filled with is detected, and when the catalyst 3 reaches the filling height provided in advance, the filling of the catalyst is stopped.

  In the photoelectric sensor 1, the amount of light (amount of received light) that the detection light projected from the sensor 1 reflects on the surface of the detection object (catalyst) and returns to the light receiving portion of the sensor 1 is quantified. This numerical value increases / decreases by increasing / decreasing the amount of received light, and the distance between the sensor 1 and the detected object can be detected. That is, when the distance between the sensor 1 and the detected object is long, the amount of received light is small, and therefore, a small numerical value is shown. It grows gradually. By measuring in advance the relationship of the actual distance between the sensor 1 and the detected object with respect to the numerical value of the received light amount, the distance between the sensor 1 and the detected object can be detected from the numerical value of the received light amount. Then, by setting a threshold value for the numerical value of the amount of light received by the sensor 1, the catalyst filling height can be adjusted in the catalyst filling. That is, the insertion position (L1) of the sensor 1 is determined, and after the threshold value is set to the numerical value of the received light amount of the sensor 1 from the distance between the catalyst and the sensor 1 at the target catalyst filling height, the filling of the catalyst is started. Then, the filling height of the catalyst is detected by the numerical value of the amount of light received by the sensor 1, and when the filling height of the catalyst reaches a set value, the filling height of the catalyst is adjusted by stopping the filling of the catalyst. be able to. The threshold value can be arbitrarily set according to the filling height of the catalyst.

  In the photoelectric sensor 1, a signal can be output from the photoelectric sensor 1 when a predetermined threshold value is exceeded according to the filling height of the catalyst 3 described above. By this signal, for example, a blinking light or a warning sound may be sent to notify the operator of the completion of catalyst filling, and the catalyst filling may be stopped manually or from the photoelectric sensor 1 via the control means. Alternatively, a stop signal may be sent to the belt conveyor 4 that conveys the catalyst 3 to stop the filling.

The detection distance between the photoelectric sensor 1 and the detection object indicates a distance when the detection unit of the photoelectric sensor 1 is brought close to the detection object and detected, that is, when the amount of received light starts to increase.
When the standard detection object is used as the detection object, the detection distance by the photoelectric sensor 1 is usually 90 to 1000 mm, preferably 100 to 500 mm, and more preferably 100 to 300 mm. For example, white paper can be used as the standard detection object.

  As the above-described diffuse reflection type photoelectric sensor 1, for example, an optical fiber type photoelectric sensor (E32 series) manufactured by OMRON Corporation or a photoelectric sensor (PS / PZ series) manufactured by Keyence Corporation is appropriately selected. And use it. The photoelectric sensor 1 may be either an amplifier built-in type or an amplifier separated type.

(Reaction tube)
The reaction tube 10 used in the present invention is a general fixed-bed multi-tube type used industrially, and usually has several thousand to several tens of thousands of reaction tubes. The outer diameter of the reaction tube is usually about 10 to 60 mm, the thickness of the reaction tube is usually about 1 to 5 mm, and the length of the reaction tube is usually about 0.3 to 10 m.

(catalyst)
In the present invention, the catalyst filled in the reaction tube 10 is not particularly limited as long as it is a catalyst for a reaction performed using a fixed bed multitubular reactor. Examples include catalysts for producing unsaturated aldehydes and unsaturated carboxylic acids, catalysts for producing unsaturated carboxylic acids, catalysts for producing unsaturated nitriles, hydrotreating catalysts, catalysts for producing chlorine, and the like. Among these, unsaturated aldehydes and unsaturated carboxylic acid production catalysts and unsaturated carboxylic acid production catalysts are preferred. Examples of the unsaturated aldehyde and unsaturated carboxylic acid production catalyst include, for example, a catalyst for producing acrolein and acrylic acid by vapor-phase catalytic oxidation of propylene with molecular oxygen, and isobutylene and tertiary butyl alcohol in molecular form. Examples include a catalyst for producing methacrolein and methacrylic acid by gas phase catalytic oxidation with oxygen. Examples of the unsaturated carboxylic acid production catalyst include a catalyst for producing acrylic acid by vapor-phase catalytic oxidation of propane with molecular oxygen, and an acrylic acid obtained by vapor-phase catalytic oxidation of acrolein with molecular oxygen. Examples thereof include a catalyst for production and a catalyst for producing methacrylic acid by gas phase catalytic oxidation of methacrolein with molecular oxygen. Examples of the unsaturated nitrile production catalyst include a catalyst for producing acrylonitrile by vapor phase catalytic ammoxidation of propylene or propane with molecular oxygen and ammonia, and isobutylene and tertiary butyl alcohol with molecular oxygen and ammonia. And a catalyst for producing methacrylonitrile by gas phase catalytic ammoxidation. Examples of the hydrotreating catalyst include a catalyst for reacting a sulfur compound and / or nitrogen compound contained in a petroleum fraction with hydrogen to remove or reduce the concentration of the sulfur compound and / or nitrogen compound in the product. Alternatively, a hydrocracking catalyst for lightening heavy oil can be used. Examples of the catalyst for producing chlorine include a catalyst for producing chlorine from hydrogen chloride and oxygen.
There is no restriction | limiting in particular about the shape of the catalyst 3, For example, you may shape | mold in cylindrical shape, spherical shape, ring shape, etc. The bulk density of the catalyst is usually 0.8 to 1.5 g / ml, preferably 0.8 to 1.3 g / ml.

(Catalyst conveying means)
In FIG. 1, the present invention adopts a method in which the catalyst 3 is transported by the Velcot conveyor 4 and dropped from the upper side of the reaction tube 10 to be filled, but there is no particular limitation. For example, vibration is applied to the transport lane. An apparatus such as a device for transporting the catalyst, a device such as a lift or a crane can be substituted, or may be performed manually. Among these, a method using an apparatus provided with the belt conveyor 4 or an apparatus that conveys the catalyst by applying vibration to the conveyance lane is preferable in terms of easy control of the filling speed in the catalyst filling into each reaction tube 10. Each reaction tube is filled with a catalyst so that the filling rate of the catalyst in each reaction tube of the fixed bed multitubular reactor is constant, and the height of catalyst filling in each reaction tube is set uniformly by the photoelectric sensor 1. To do. In this way, by filling the catalyst so that the filling speed of each reaction tube is constant and setting the catalyst filling height uniformly, variation in pressure loss in each reaction tube after filling the catalyst is well suppressed. be able to.
In the catalyst filling by the apparatus provided with the Berkoto conveyor 4 or the apparatus for conveying the catalyst by applying vibration to the transportation lane, the filling speed is usually 5 to 60 g / second, preferably 5 to 40 g / second.

(Photoelectric sensor protection tube)
As shown in FIG. 2, the photoelectric sensor 1 may be inserted into the protective tube 5 and used as necessary. In the gap between the inside of the protective tube 5 and the outside of the photoelectric sensor 1, dry air, inert gas, or a mixed gas thereof branches from the tube 6 branched from the side surface of the protective tube 5, below the protective tube 5, that is, photoelectric. It is sent toward the sensor 1. Examples of the inert gas include nitrogen, helium, and argon. The photoelectric sensor 1 may be inserted in the center of the reaction tube 5 or near the wall of the reaction tube 5. The shape of the protective tube 5 is not particularly limited.
The material of the protective tube 5 is not particularly limited, and examples thereof include a stainless steel tube, a plastic tube, an aluminum tube, and a rubber tube. Also, the dimensions of the protective tube 5 are not particularly limited, but the inner diameter has the above-mentioned gap to the extent that dry air, inert gas, or a mixed gas thereof circulates, and the outer diameter is filled with the catalyst. In order not to inhibit, a smaller one than the inner diameter of the reaction tube is preferable.

When the falling distance of the catalyst 3 into the reaction tube 10 is long, the inside of the reaction tube 10 becomes an environment with much dust.
The protective tube 5 described above is inserted or installed in the reaction tube 10 in a state where the photoelectric sensor 1 is included, and the protective tube 5 protects the photoelectric sensor 1 from dust that occurs when the catalyst 3 is filled. At the same time, the photoelectric sensor 1 can be used without maintenance for a long time.

  Although not particularly limited, the photoelectric sensor 1 is preferably inserted from above the reaction tube 10 without contacting the reaction tube 10 in order to maintain the accuracy of the detection light and the light receiving unit.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

(Reference example)
<Manufacture of catalyst>
As a catalyst, based on the method described in JP-A No. 2004-188231, an acid salt of a Keggin type heteropolyacid containing phosphorus, molybdenum and vanadium (a cylindrical extruded product having a diameter of 5 mm and a height of 5 mm) was measured. Produced 20 times. When the bulk density of the catalyst was measured for each production lot, the average bulk density was 1.15 g / ml, the maximum value was 1.20 g / ml, and the minimum value was 1.09 g / ml.
The bulk density was measured by the following method. That is, about 190 ml of the catalyst was weighed, and the weight at this time was defined as W (g). Next, after filling the weighed catalyst into a glass graduated cylinder having an inner diameter of 31 mm and a volume of 200 ml, the graduated cylinder was tapped 40 times from a height of 20 mm on a rubber mat with a thickness of 2.5 mm to fill the catalyst. The volume was read with an accuracy of 0.5 ml and this was taken as V (ml). The bulk density (g / ml) was calculated by dividing W (g) by V (ml).

Example 1
E32-D32L as a diffuse reflection photoelectric sensor 1 with a threshold value of 3000 (Omron Co., Ltd., reflection type: special beam type, detection distance in standard mode when white paper is a standard detection object = 150 mm) Using E3X-DA-21S (manufactured by OMRON Corporation) as an amplifier unit, a catalyst filling test was performed in a standard mode and a threshold value of 3000. Other conditions are as follows.
In addition, the photoelectric sensor 1 used in the embodiment can perform measurement in three modes: a high speed mode, a standard mode, and a high accuracy mode. At this time, the delay time from when the optical input is interrupted until the control output operates or recovers is called response time. The response time differs in each mode, and is 250 μs in the high speed mode, 1 ms in the standard mode, and 4 ms in the high accuracy mode.
Reaction tube length = 1m
Reaction tube inner diameter = 25mmφ
Sensor insertion length (L1) = 300mm
The photoelectric sensor is inserted into a protection tube 5 (outer diameter 8 mm, inner diameter 6 mm) made of stainless steel (SUS304), and the photoelectric sensor tip is detected from the upper part of the protection tube in the gap between the photoelectric sensor and the inner wall of the protection tube. Dry air was blown toward the part at a constant flow rate.
Then, the catalyst is dropped from above the reaction tube 10 by the belt conveyor 4 at a speed of 20 g / s, and the catalyst is filled. The stop signal output from the photoelectric sensor 1 exceeding the threshold value is output from the belt conveyor 4. The distance L2 when the catalyst supply was stopped and the distance (L2-L1) between the photoelectric sensor and the catalyst were measured. Table 1 shows the results.

(Example 2)
The same conditions as Example 1 except that E32-D22L (Omron Co., Ltd., reflection type: special beam type, detection distance in standard mode when white paper is used as a standard detection object = 130 mm) was used as a photoelectric sensor. The catalyst was charged at.

(Example 3)
The same conditions as in Example 1 were used except that E32-D12R (manufactured by OMRON Corporation, reflection type: standard type, detection distance in standard mode when white paper was used as a standard detection object = 170 mm) was used as the photoelectric sensor. The catalyst was charged.

(Comparative Example 1)
The same conditions as in Example 1 were used except that E32-D22 (Omron Co., Ltd., reflection type: standard type, detection distance in standard mode when white paper was used as a standard detection object = 80 mm) was used as the photoelectric sensor. The catalyst was charged.

(Comparative Example 2)
The same conditions as in Example 1 except that E32-D32 (Omron Co., Ltd., reflection type: special beam type, detection distance in standard mode when white paper is used as a standard detection object = 75 mm) was used as the photoelectric sensor. The catalyst was charged at.

表１から明らかなように、実施例１〜３では、触媒に光電センサが埋もれることなく、正確に反応管の所定の高さまで触媒を充填することができた。これに対して、比較例１，２では、センサがしきい値を検出できず埋まってしまった。 The test results are shown in Table 1.

As is clear from Table 1, in Examples 1 to 3, the catalyst could be accurately filled up to a predetermined height of the reaction tube without the photoelectric sensor being buried in the catalyst. On the other hand, in Comparative Examples 1 and 2, the sensor could not detect the threshold value and was buried.

Example 4
The catalyst was charged in the same manner as in Example 1 except that the following conditions were used.
Photoelectric sensor: E32-D12R (supra) (detection distance in high-accuracy mode when white paper is used as standard detection object = 300 mm)
Mode: High-precision mode threshold: 3000
When filling was performed one by one by hand, the threshold value was exceeded at a position 10 mm (L2-L1) from the tip of the sensor.

(Example 5)
The catalyst-filling was carried out in the same manner as in Example 1 except that a silica-alumina catalyst having the following shape (molded product of silica-alumina porous ceramics manufactured by Iwao Porcelain Co., Ltd.) was used and the following conditions were used. Went.
(1) Spherical shaped body (diameter 6.35 mm)
(2) Ring-shaped molded body (outer diameter 6.5 mm, inner diameter 3.5 mm, length 6.4 mm)
Photoelectric sensor: E32-D12R (supra)
Mode: Standard mode Threshold: 3000
The filling was performed by hand filling one by one.
As a result, the catalyst of (1) exceeded the threshold at a position 10 mm (L2-L1) from the tip of the sensor. The catalyst of (2) exceeded the threshold at a position 8 mm (L2-L1) from the tip of the sensor.
In the above embodiment, a single-lane belt conveyor is used as the belt conveyor 4. The flow rate of dry air into the protective tube was 3 L / min.

1: photoelectric sensor, 2: signal, 3: catalyst, 4: belt conveyor, 5: protective tube, 6: branch tube, 10: reaction tube

Claims (3)

A method of filling a reaction tube with a solid catalyst from above the reaction tube,
The White paper as a standard detected object, have a detection distance range of 90～1000Mm, the catalyst was filled in and the state in which the photoelectric sensor of the diffuse reflection type which is covered with a protective tube inserted into the reaction tube, said photoelectric sensor detecting the filling height of the catalyst, when the filling height of the catalyst has reached the set value, the filling of the catalyst is stopped, that and sending the air from above the protective tube, an inert gas or a mixed gas thereof, A catalyst filling method characterized by the above.   The catalyst filling method according to claim 1, further comprising control means for stopping filling of the catalyst into the reaction tube based on a detection signal output from the photoelectric sensor.   Control means for stopping the filling of the catalyst into the reaction tube when the magnitude of the amount of light received by the detection light irradiated downward from the photoelectric sensor is reflected on the surface of the catalyst and returned to the light receiving unit exceeds a threshold value The catalyst filling method according to claim 1 or 2, wherein

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