JP2006142288A - Fixed bed multitubular reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed bed multitubular reactor in which the pressure loss of each of reaction tubes is decreased and the work of packing a catalyst in each of reaction tubes and the work of adjusting the pressure loss of each of reaction tubes are facilitated to improve the working efficiency. <P>SOLUTION: This fixed bed multitubular reactor has a plurality of reaction tubes to be packed with a solid granular material. The inside surface of each of reaction tubes is made flat and smooth. In the concrete, the inside surface of any of the plurality of reaction tubes is made to have ≤3 μm arithmetic mean surface roughness (Ra) or ≤30 μm maximum height (Ry). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixed bed multitubular reactor such as a fixed bed multitubular heat exchange reactor applied to a gas phase catalytic oxidation reaction using a catalyst.

  Generally, in the production of chlorine, hydrogen chloride contained in the produced chlorine gas is subjected to catalytic oxidation in the presence of a catalyst using a gas containing oxygen. Since this oxidation reaction is an exothermic reaction, the reaction is performed using, for example, a fixed bed multitubular heat exchange reactor in which a plurality of reaction tubes are filled with a granular catalyst.

  In such a fixed bed multitubular reactor, if the amount of gas is small, excessive temperature rise or side reaction is likely to occur, so the gas flow in each tube should be filled as uniform as possible. is important. In order to make the gas flow uniform, it is desirable that the pressure loss Δp of the catalyst layer measured using an inert gas or the like be consistent in all the reaction tubes. Is within about 5%.

  Patent Document 1 discloses that a reaction tube having a pressure loss lower than the average value or a reaction tube having a higher value than the average value so that the pressure loss of each reaction tube after filling the catalyst becomes ± 20% of the average value. In addition, it is described that the pressure loss of each reaction tube is adjusted by extracting and refilling the catalyst.

  Patent Document 2 describes that the catalyst capacity of each reaction tube is measured to be uniform, and the catalyst is filled into the reaction tube with a filling time of 30 seconds or more per liter.

Japanese Patent Laid-Open No. 2003-252807 JP 2002-306953 A DOWDEN, D.N. ANDREW, S.P.S CAMPBELL, J.S.

  However, even if the above-described measures are taken, a normal multi-tubular reaction tube has several thousand to several tens of thousands of reaction tubes, so that the pressure loss of each reaction tube after filling the catalyst is made uniform. It was difficult to do. For this reason, the actual situation is that much attention is paid to the work of filling the catalyst into each reaction tube, and a great deal of effort is spent to uniformly adjust the pressure loss.

  Therefore, an object of the present invention is to reduce the pressure loss of each reaction tube, simplify the work of filling the catalyst into the reaction tube and the adjustment of the pressure loss of each reaction tube, and improve the work efficiency. It is to provide a tubular reactor.

  As a result of intensive studies to solve the above problems, the present inventors have found that when the surface roughness of the inner surface of the reaction tube to be used is large, even if the diameter of the reaction tube is the same, the packed catalyst, etc. It was found that the bulk density and the packing density of the solid particulates are likely to vary, and therefore the pressure loss is likely to vary, and the present invention has been completed.

That is, the fixed bed multitubular reactor of the present invention has a plurality of reaction tubes filled with solid particulate matter, and is characterized in that the inner surface of each reaction tube is smooth.
Specifically, each of the plurality of reaction tubes has an arithmetic average roughness (Ra) of an inner surface of 3 μm or less, or a maximum inner surface height (Ry) of 30 μm or less. Each of the plurality of reaction tubes preferably has an arithmetic mean roughness (Ra) of the inner surface of 3 μm or less and a maximum height (Ry) of the inner surface of 30 μm or less.

  According to the present invention, since the inner surface of each reaction tube is smooth and the surface roughness is small, the packing density (apparent bulk density) of the catalyst filled in the reaction tube is increased. Furthermore, the inner surface roughness of each reaction tube is uniform, that is, the arithmetic average roughness (Ra) of the inner surface is 3 μm or less, or the maximum height (Ry) is 30 μm or less. Variation in the pressure loss is reduced, and the pressure loss can be made uniform. Therefore, the work of filling the catalyst into each reaction tube and the operation of adjusting the pressure loss of each reaction tube are simplified, and the work efficiency can be improved.

  The fixed bed multitubular reactor of the present invention includes a plurality of reaction tubes filled with solid particulate matter such as a catalyst. While passing a predetermined raw material compound through the reaction tube, the raw material compound is oxidized by a gas phase contact reaction to obtain a target compound.

  The raw material compounds subjected to such a reaction include, for example, hydrogen chloride and oxygen for obtaining chlorine by a gas phase oxidation method, acrolein by a gas phase oxidation method, and propylene and oxygen for obtaining acrylic acid, gas phase oxidation Examples of the method include methacrolein, and isobutylene and oxygen for obtaining methacrylic acid.

  The reaction tube used may be coiled, but a straight straight tube is usually used. The straight pipe may be either a horizontal arrangement or a vertical arrangement, but is usually a vertical type which is arranged in the vertical direction and allows the raw material compound to pass in the vertical direction.

As the catalyst filled in the reaction tube, for example, in the gas phase oxidation method for obtaining chlorine from hydrogen chloride and oxygen, an oxidation catalyst mainly composed of ruthenium oxide and supported on rutile titanium oxide can be cited, and further propylene and oxygen In the case of the gas phase oxidation method for obtaining acrolein and further acrylic acid from gas, and the gas phase oxidation method for obtaining methacrolein and further methacrylic acid from isobutylene and oxygen, a predetermined oxidation catalyst is used.

  The catalyst may be diluted with an inert filler that is inert to the reaction. Further, the catalyst may be divided into a plurality of catalyst layers and filled in the reaction tube. In that case, an inert filler layer may be interposed between the catalyst layers.

  Examples of the shape of the catalyst include a spherical particle shape, a cylindrical pellet shape, a ring shape, and a granular shape obtained by pulverization and classification after molding, and are not particularly limited. In general, the catalyst preferably has a diameter of 10 mm or less, and if the catalyst diameter exceeds 10 mm, the activity may decrease. In addition, when the catalyst diameter is excessively small, the pressure loss in the reaction tube increases, and therefore the catalyst diameter is usually preferably 0.1 mm or more.

  Each reaction tube filled with a catalyst used in the present invention is usually a metal tube having substantially the same shape and having an inner diameter selected from a range of about 15 to 50 mm. Here, “substantially the same shape” means that the outer diameter, wall thickness, and length of the reaction tube are within the range of the design error. The design error is usually within ± 2.5%, preferably within ± 0.5%. Although it is preferable to determine the inner diameter of the reaction tube and the catalyst diameter so that the inner diameter of the reaction tube is four times or more the catalyst diameter, it is not particularly limited.

  The reaction tube used in the present invention needs to have a smooth inner surface, and specifically needs to have a small surface roughness. Thereby, the catalyst packing density in each reaction tube can be made high.

  The surface roughness is represented by arithmetic average roughness (Ra), maximum height (Ry), and the like. The arithmetic average roughness (Ra) and the maximum height (Ry) can be measured according to the method described in JIS B 0601-1994.

  In the present invention, the arithmetic mean roughness (Ra) of the inner surfaces of all reaction tubes of the reactor is 3 μm or less, preferably 1.5 μm or less, or the maximum height (Ry) of the inner surfaces of all reaction tubes is 30 μm. Hereinafter, it is preferably 15 μm or less. Thereby, the surface roughness of each reaction tube becomes uniform, the packing density of the catalyst becomes high, and the variation in packing density among the reaction tubes becomes small, so that the variation in pressure loss can be reduced. It is desirable that the arithmetic average roughness (Ra) and the maximum height (Ry) satisfy the above range at the same time.

  When the arithmetic average roughness (Ra) is greater than 3 μm, or when the maximum height (Ry) is greater than 30 μm, the packing density of the catalyst tends to be small due to the large surface roughness, and the packing density The variation of the is increased. For this reason, even if the catalyst filling operation is performed carefully, the pressure loss after the catalyst filling tends to vary.

  As such a reaction tube having a low surface roughness of the inner surface, for example, a seamless tube with no joint can be suitably employed. From such a seamless tube, a reaction tube whose surface roughness meets the above conditions may be selected. In order to increase the packing density and decrease the pressure loss, the surface roughness should be as low as possible.

  The method of filling the reaction tube with the catalyst is not particularly limited. For example, in the case of a vertical type, the catalyst may be charged and dropped into the tube while leaving a space in the upper part of the reaction tube. At this time, it is preferable that the filling rate into each tube is constant or as slow as possible.

  The fixed bed multitubular reactor of the present invention is usually used as a heat exchange reactor. This heat exchange type reactor has a jacket (shell) part outside the reaction tube filled with the catalyst, and the reaction heat generated by the reaction is removed by the heat medium of the jacket (shell). Specifically, a disk-and-doughnut-type multitubular reactor, a non-circular baffle-type multitubular reactor, and the like are preferably used. Examples of the heat medium include a molten salt, steam, an organic compound, and a molten metal. In particular, it is preferable to use a molten salt and steam from the viewpoint of thermal stability and handleability.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example.

The reactor is equipped with a jacket using molten salt (potassium nitrate / sodium nitrite = 1/1 weight ratio) as a heat medium, and consists of a plurality of reaction tubes (nickel seamless tube, inner diameter 21 mm, length 5 m) of the same quality. A fixed bed multi-tube heat exchange reactor was used.
The surface roughness (Ra, Ry) of the inner surface of the reaction tube was measured using a stylus type roughness measuring instrument (manufactured by Mitutoyo Corporation) according to JIS B 0601-1991 for the sample cut out from the reaction tube.
Each reaction tube was filled with 2620 g of a catalyst (a catalyst in which ruthenium oxide was supported on titanium oxide and aluminum oxide) used for the oxidation reaction of hydrogen chloride and an inert filler (inert ball). The catalyst used is a cylindrical granular material having a diameter of 3 mm and a length of 5 mm, and the inert filler is also a cylindrical granular material having the same dimensions. The catalyst packing density in each reaction tube had an average value of 1.326 g / cm ³ .
After filling, dry air was supplied from the upper part of the reactor at 4 liters / minute (absolute pressure 0.1 MPa (atmospheric pressure) conversion), and the pressure loss ΔP of each reaction tube was measured with a digital manometer.

表１から、反応管の表面粗さが該反応管の触媒充填かさ密度および圧力損失に影響しており、表面粗さが低いほど、反応管の触媒充填かさ密度が大きく、触媒がつまりやすく、圧力損失のばらつきが小さくなっていることがわかる。 Using a reaction tube having a surface roughness (Ra, Ry) different from that of Example 1, the catalyst was filled in the same manner as in Example 1, and the pressure loss ΔP of each reaction tube was measured. The catalyst packing density in each reaction tube was 1.341 g / cm ³ . These measurement results are shown in Table 1.

From Table 1, the surface roughness of the reaction tube affects the catalyst filling bulk density and pressure loss of the reaction tube. The lower the surface roughness, the larger the catalyst filling bulk density of the reaction tube and the easier the catalyst is to clog, It can be seen that the variation in pressure loss is small.

Claims (7)

  A fixed bed multitubular reactor having a plurality of reaction tubes filled with solid particulate matter, wherein the inner surface of each reaction tube is smooth.   The fixed-bed multitubular reactor according to claim 1, wherein the reaction tube is a seamless tube.   In the fixed bed multi-tubular reactor having a plurality of reaction tubes filled with solid particulate matter, the plurality of reaction tubes each have an arithmetic mean roughness (Ra) of an inner surface of 3 μm or less. Fixed bed multi-tube reactor.   The fixed bed multitubular reactor according to claim 3, wherein the arithmetic average roughness (Ra) is 1.5 μm or less.   A fixed bed multitubular reactor having a plurality of reaction tubes filled with solid particulate matter, wherein the plurality of reaction tubes each have a maximum inner surface height (Ry) of 30 μm or less. Floor multi-tube reactor.   The fixed bed multitubular reactor according to claim 5, wherein each of the maximum heights (Ry) is 15 μm or less. In the fixed bed multitubular reactor having a plurality of reaction tubes filled with solid particulate matter, each of the plurality of reaction tubes has an arithmetic mean roughness (Ra) of the inner surface of 3 μm or less and a maximum height of the inner surface. (Ry) is 30 μm or less.