JPH06218269A - Horizontal type fluidized bed catalyst reactor - Google Patents

Abstract

(57) [Summary] [Constitution] Pipe diameter 12 fixed by vertical baffle plate
Horizontal fluidized bed catalytic reactor that has a horizontal U-shaped heat transfer tube of ~ 40mm and recovers the reaction heat as high-pressure steam. [Effect] Since a thin heat transfer tube can be used, heat transfer per unit volume The area is increased, higher pressure vapor is recovered, the cost of the reactor is reduced, and it is advantageously used in a large apparatus. Also, since the superficial velocity (LV) in the fluidized catalyst bed is small, wear and damage of catalyst particles,
And wear inside the reactor is prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fluidized bed catalytic reactor suitable for ultra-large equipment. The fluidized bed catalytic reactor of the present invention is
It is used in an exothermic reaction such as a methanol synthesis reaction or a Fischer synthesis reaction from a synthesis gas containing hydrogen, carbon monoxide and carbon dioxide as active ingredients.

[0002]

2. Description of the Related Art A fluidized bed catalytic reactor has good heat transfer in a catalyst bed and a uniform temperature distribution. Therefore, side reaction products can be suppressed to a low level, and high conversion and high selectivity can be obtained. It has characteristics such as that the heat of reaction can be recovered at a high level, and reactors using fluidized catalysts have been developed in various reactions.

Since methanol is used in large quantities as an inexpensive fuel that is low in pollution and easy to transport, it has a capacity of 5000 T / D or 1000
Development of ultra-large equipment with a capacity of 0 T / D or more is required. In recent years, a fluidized bed catalytic reactor has been developed as a response to an ultra-large-sized apparatus for producing such fuel methanol. For example, JP-A-60-84142 and JP-A-60-84142
-122040 and JP-A-60-106534 describe a method for producing a fluidized catalyst for methanol synthesis, and JP-A-63-106534.
-211246 describes the catalyst and reaction conditions when carrying out methanol synthesis using a fluidized bed catalyst.

[0004]

Since a large amount of heat is generated in the methanol synthesis reaction, a large number of heat transfer tubes are generally arranged in a vertical reactor in order to recover the reaction heat and control the reaction temperature. Then, a method of recovering high-pressure steam is adopted. When a large number of heat transfer tubes are arranged in the reactor as described above, vibration of the heat transfer tubes is likely to occur in a fluidized bed catalytic reactor, since the gas passes through the reactor at a high speed. When the ratio (L / D) of length to diameter of heat transfer tube exceeds 30, vibration occurs,
Especially, when L / D exceeds 50, vibration is significant along with resonance and sometimes the heat transfer tube is damaged.

Therefore, in designing a vertical fluidized bed catalytic reactor, it is necessary to suppress L / D to 30 to 50 or less, and it is practically impossible to use a heat transfer tube having a small tube diameter, and a 3 to 4 inch tube is used. It is in a state where it cannot help being used. As a result, the volume of the heat transfer tube is large and the reactor becomes large, which increases the cost of the reactor and exceeds the manufacturing limit of the reactor in the above-mentioned ultra-large-sized methanol production apparatus. Moreover, since a sufficient heat transfer area cannot be obtained in the reactor, the pressure of the steam to be recovered must be reduced in order to increase the temperature difference, and energy recovery cannot be performed effectively.

Further, in order to obtain a high reaction rate in a fluidized bed catalytic reactor, it is necessary to make the fluidized catalyst bed as uniform as possible. In a large-scale apparatus, even in a fluidized catalyst bed, a high-concentration part and a low-concentration part are likely to occur, the reaction temperature rises in the high-concentration part and the side reaction amount increases, and a gas with a low reaction rate passes in the low-concentration part Therefore, it becomes difficult to obtain a high reaction rate as a whole. An object of the present invention is to increase the heat transfer area per unit volume of a reactor in an exothermic reactor using a fluidized catalyst so that it can be applied to an ultra-large-sized device, efficiently recover heat, and obtain a high reaction rate. To provide a reactor that can be used.

[0007]

As a result of intensive studies on the fluidized bed catalytic reactor having the above-mentioned problems, the present inventor has made the reactor horizontal to reduce the gas flow rate and uses a U-shaped heat transfer tube. By fixing with a baffle plate, vibration of the heat transfer tube is suppressed and a heat transfer tube with a small diameter can be used, and the heat transfer area per unit volume is significantly increased, reducing reactor cost and higher pressure steam. The present invention has been found to be effective in that the recovery can be performed and the thermal efficiency of the methanol production apparatus can be improved, and that the abrasion of the catalyst particles and the inside of the reactor can be prevented.

That is, the present invention relates to a horizontal cylindrical reactor using a fluidized catalyst, in which (a) a horizontal cylindrical steam-water drum is provided at the center of a side end plate of the reactor, and (b) a fluidized catalyst is provided inside the reactor. Bed, (c) a plurality of horizontal U-shaped heat transfer tubes having a tube diameter of 12 to 40 mm for supplying steam to the boiler in the fluidized catalyst layer from a water / water drum to recover steam, and (d) a tube bundle of the heat transfer tubes. A plurality of vertical baffle plates, (e) a separation device for separating the fluidized catalyst and the reaction gas above the fluidized catalyst layer, (f) a gas blower installed below the fluidized catalyst layer, and below the gas blower. The horizontal fluidized bed catalytic reactor is characterized in that the raw material gas is further introduced and the reaction gas is discharged from the upper part of the separation device.

The reaction for synthesizing methanol from hydrogen, carbon monoxide and carbon dioxide using the fluidized bed catalytic reactor of the present invention is carried out according to the following reaction formula. CO + 2H ₂ → CH ₃ OH + 21.6 kcal / mol CO ₂ + H ₂ → CO + H ₂ O − 9.8 kcal / mol CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O +11.8 kcal / mol

A copper catalyst is usually used in the methanol synthesis reaction, and the reaction is carried out at a temperature of 200 to 300 ° C. and a pressure of 50 to 150 atm. As a fluidized catalyst for a methanol synthesis reaction, a catalyst in which a catalyst component is supported on a strong carrier such as silica, alumina or zirconium is usually used, and the particle size of the catalyst is
It is 1 to 250 μm.

In the present invention, a horizontal cylindrical reactor is used, and a horizontal cylindrical steam drum is installed at the center of the side end plate of the reactor. The function of the steam drum is obtained by supplying boiler water for collecting reaction heat and distributing it to a plurality of horizontal U-shaped heat transfer tubes, and collecting reaction heat in the fluidized catalyst bed. It is to introduce a mixture of steam and boiler water from a plurality of heat transfer tubes to separate generated steam and boiler water.For this reason, in the steam drum, the mixture from the supply boiler water and the heat transfer tubes is Is provided with a partition wall, and a liquid level gauge and a mist separator for separating generated steam and boiler water from the mixture are installed.

The shape of the tube plate of the water / water drum to which the heat transfer tube is attached is not particularly limited, and a flat plate type or a hemispherical type is generally used. For example, in order to secure a necessary surface area for fixing a large number of heat transfer tubes, a device such as a hemispherical tube plate is used. A plurality of U-shaped heat transfer tubes are attached to the steam drum to collect high-pressure steam from the fluidized catalyst layer. As described above, a vertical baffle plate is installed to prevent vibration of the heat transfer tubes. It It is preferable to make the gap between the baffle plate and the heat transfer tube as small as possible, but there is a limit in manufacturing, and in practice, this gap is 0.15 to 0.25 mm on one side. By making the gap with respect to the heat transfer tube small in this way, the heat transfer tube has the same effect as being fixed by the baffle plate, and vibration of the heat transfer tube is prevented.

In the present invention, the diameter of the heat transfer tube is determined by the distance between the baffle plates in order to prevent vibration of the heat transfer tube. Baffle plate spacing is 300 to 10
You can choose from a wide range of 00 mm. In order to prevent vibration of the heat transfer tube, it is necessary to set L / D (ratio of the length and diameter of the heat transfer tube) to 50 or less, so the diameter of the heat transfer tube is 6 to 20.
mm or more. In the present invention, the heat transfer tube diameter (outer diameter) is 12 to
40 mm, preferably 15-25 mm, for which a suitable baffle plate spacing is selected.

In the conventional fluidized bed catalytic reactor, a heat transfer tube of 3 to 4 inches is used. In the present invention, the baffle plate as described above is installed on the heat transfer tube to transfer heat of about 15 to 25 mm. Since heat tubes can be used, the heat transfer area per unit volume is 88 to 120 m ² / m ³ , which is about 3.0 to 4.1 times that of the conventional 3-inch type. As a result, the reactor can be downsized, and the temperature difference between the fluidized catalyst bed and the fluid inside the heat transfer tube can be reduced, so that the pressure of the recovered vapor can be increased.

In the present invention, a gas blower having a large number of nozzles is installed below the fluidized catalyst bed, and the raw material gas is blown out uniformly to the fluidized catalyst bed. The reactor is one in which a gas is allowed to flow through the fluidized catalyst bed from the bottom to the top at a slow speed to carry out the reaction. This type of high pressure fluidized reactor is usually designed with a superficial velocity (LV) of 0.3 to 0.7 m / sec.
The reactor can be designed at about 0.10 to 0.25 m / sec.

The feature of the present invention is that the diameter of the heat transfer tube can be reduced in this way, and in addition, since the tube bundle axis and the gas flow direction are perpendicular to each other, it is advantageous in terms of the heat transfer effect. The decrease in heat transfer efficiency can be compensated. Further, the reduction of LV is also effective for avoiding internal mechanical abrasion and abrasion / destruction of the catalyst.

Inside the reactor, the reaction gas rises between the flowing catalysts between the tube bundles, and the catalysts are in balance with gravity, so that the interface of the fluidized catalyst layer is obtained. The gas from this interface also contains some fine catalyst and is therefore referred to as the dilute layer, and the layers below the interface are referred to as the rich layer. Most of the catalyst particles settle in this dilute layer and collide with the outer grain wall surface, fall to the interface and return to the rich layer. The reaction gas from the dilute layer is finally sent to the next step outside the reactor through the separator.
A cyclone is generally used in this separation device, and the separated catalyst is returned to the rich layer through a trickle valve.

In the present invention, since the U-shaped heat transfer tube is used to recover the reaction heat and is horizontal, it is necessary to circulate the boiler water forcibly, and the boiler water separated from the steam drum is circulated. It is circulated using a pump. In order to avoid the concentration of impurities in the boiler water, part of the boiler water is discharged outside the system.

In the reactor of the present invention, since a heat transfer tube having a small tube diameter is used, the heat transfer area per unit volume becomes large, so that the reactor becomes small, and it becomes easy to cope with a large apparatus. Furthermore, since the temperature difference between the catalyst layer and the boiler water becomes small, high pressure steam can be recovered. Further, since the reactor of the present invention is horizontal, the burden on wind pressure and earthquake in the design of the foundation is significantly reduced, which is also advantageous from the viewpoint of construction cost.

[0020]

EXAMPLES Next, the present invention will be described more specifically by way of examples. However, the present invention is not limited to this embodiment. FIG. 1 is a structural diagram of an example of a fluidized bed catalytic reactor according to the present invention, showing a case of a large reactor used in a fuel methanol production apparatus.

CO, CO ₂ , H ₂ as main components and a small amount of C
The synthetic raw material gas containing H ₄ and N ₂ is introduced from the flow path 1 into the empty chamber 2 partitioned from the fluidized catalyst layer. Since the reactor is operated at a pressure of about 50 to 150 atm in the methanol synthesis reaction as described above, the outer grain 3 is made of a strong steel material and thick. The raw material gas is then introduced into the wind box chamber 4 at the bottom of the fluidized catalyst bed. It is introduced into the fluidized catalyst bed 6 (concentrated bed) through the gas blower 5. The fluidized catalyst layer is filled with a fluidized catalyst for methanol synthesis, and the above-mentioned methanol synthesis reaction is performed.

A large number of horizontal U-shaped heat transfer tubes 7 are provided in the fluidized catalyst bed to recover the reaction heat. The heat transfer tube is filled with boiler water, and the absorbed reaction heat is recovered as high-pressure saturated steam. The heat transfer tube is supported and fixed to the tube plate 8, and the reaction gas side and the boiler water side are sealed by the tube plate portion. The tube plate 7 is installed in a horizontal cylindrical steam water drum 9 fixed to the center of the side end plate of the reactor, and the inside is divided into a steam water chamber 10 and a water supply chamber 11 of the boiler. Water supply room 11
A boiler water supply channel 12 is provided in the steam water chamber 10, and a separate circulating water channel 13 is provided in the steam chamber 10.

The heat transfer tube 7 is provided with a plurality of vertical baffle plates 14 to suitably fix the heat transfer tube.
As a result, a heat transfer tube having a small tube diameter can be used, the heat transfer area per unit volume is increased, and a uniform flow of the fluidized catalyst layer can be obtained. The reaction gas and the fluidized catalyst become a dilute layer through the interface of the fluidized catalyst layer in which the catalyst is in balance with gravity at the upper part of the reactor, and are introduced into the cyclone 15 to separate the catalyst particles, and the reactor from the flow path 16 to the reactor. And sent to the next step. The separated catalyst is discharged from the trickle valve 17 below the cyclone and circulated in a rich layer.

On the other hand, the high-pressure steam generated by the recovery of the reaction heat is discharged from the flow path 18 and used as process steam in the synthesis gas manufacturing apparatus, as a heat source and a power source at various places. In addition, the boiler water separated in the steam drum is in the flow path.
It is discharged from 12, is pressurized by a circulating water pump, is supplied from the flow path 11 together with boiler feed water, and is circulated for use. Since the reactor of the present invention is horizontal, it is supported by the support rack 19 and further fixed to the foundation.

[0025]

The fluid catalytic reactor of the present invention has the following advantages by adopting a horizontal type and a structure in which the U-shaped heat transfer tube is fixed to the baffle plate. (1) Not used in conventional fluid catalytic reactors 15
Since a thin heat transfer tube of about 25 mm can be used, the heat transfer area per unit volume is increased, the volume of the reactor can be reduced, and the cost of the reactor is reduced. (2) Since the temperature difference between the fluidized catalyst layer and the fluid in the heat transfer tube becomes small, the high-pressure steam can be recovered more and the thermal efficiency of the process can be improved. Further, this also makes the temperature distribution of the fluidized catalyst bed uniform. (3) Since U-shaped heat transfer tubes are used, thermal stress due to reaction temperature is avoided. Further, since the volume of the reactor is reduced, it is possible to support a larger apparatus. (4) Since the superficial velocity (LV) in the fluidized catalyst bed is low in the horizontal reactor, abrasion and breakage of catalyst particles and abrasion inside the reactor can be prevented. (5) Since it is a horizontal reactor, the burden on wind pressure and earthquakes is greatly reduced, and construction costs are reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a sectional view showing the structure of a horizontal fluidized bed catalytic reactor according to the present invention.

[Explanation of symbols]

 1 Raw material gas supply flow path 3 Outer grains of horizontal fluidized bed catalytic reactor 5 Raw material gas blower 7 U-shaped tube heat transfer tube 9 Steam drum 10 Steam room 11 Water supply room 14 Baffle plate 15 Cyclone 16 Reaction gas discharge path

Claims (1)

[Claims] 1. A horizontal cylindrical reactor using a fluidized catalyst, comprising: (a) a horizontal cylindrical air-water drum at the center of a side end plate of the reactor, (b) a fluidized catalyst layer inside the reactor, c) a plurality of horizontal U-shaped heat transfer tubes having a tube diameter of 12 to 40 mm for supplying boiler water from a steam drum to recover steam in the fluidized catalyst bed, (d) a plurality of tube bundles of the heat transfer tube. A vertical baffle plate, (e) a separation device for separating the fluidized catalyst and the reaction gas above the fluidized catalyst layer, and (f) a gas blower installed below the fluidized catalyst layer. And a reaction gas is discharged from the upper part of the separation device.