JP2007021471A - Heating apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover a vaporization product produced when vaporizing or pyrolyzing a solid organic matter under the under vacuum or inert atmosphere while suppressing the secondary decomposition to the minimum. <P>SOLUTION: A material organic matter, as a powder or a granular solid, is supplied on a movable flat plate in layers to be introduced to a heating part, and the product is deposited to a cooling plate immediately disposed to recover. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

Detailed Description of the Invention

The present invention is a method for recovering solid or liquid organic substances by heating them under an inert atmosphere to evaporate them or thermally decomposing them to vaporize them as volatile low molecular weight compounds while preventing these secondary thermal decompositions, and therefore Relating to the device.

  Wet decomposition (hydrolysis with mineral acids and enzymatic decomposition) has been widely used as a method for converting organic substances, particularly natural organic polymer substances present in large quantities into useful chemical substances. This has become a practical technique in the form of the production of glucose and ethanol from starch. However, for cellulose, which is an inexpensive biomass resource that exists in a larger amount than starch, the process of converting it into glucose has not been realized as an industrial technology because of its indegradability due to its crystallinity.

Dry pyrolysis has been investigated as an alternative to wet cracking. Glucose polymers such as starch and cellulose have long been known to give a compound called anhydrous sugar in a high yield by dry pyrolysis under an inert atmosphere. For example, when starch is pyrolyzed under vacuum, 1,6-anhydroglucose (commonly known as levoglucosan) is obtained as a main product, and the yield is typically 20 to 30% based on the raw starch (Non-patent Document 1). . When the same treatment is performed with high-purity cellulose, the levoglucosan yield reaches 50% or more. (Non-Patent Documents 2 and 3). These findings suggest that most of the primary product of pyrolysis of high purity starch and cellulose is levoglucosan.
R. B. Ward. Methods in Carbohydrate Chem. , 2, p. 394 (1963) M.M. Cerny and J.M. Stanek, Jr. , Adv. in Carbohydr. Chem. 34 (1977) p. 23-177 D. Radlein et al. , J .; Anal. Appl. Pyrolysis, 19 (1991) 41-63

However, there are major obstacles to using this reaction as an industrial process. That is, levoglucosan immediately undergoes secondary decomposition at the generation temperature (= decomposition temperature of starch and cellulose = 300 to 360 ° C.) to become small molecules such as furfurals, acetic acid, methanol, carbon dioxide and the like. For this reason, the yield of levoglucosan from pure cellulose is about 60% at maximum in a small-scale device, and it greatly decreases when scaled up. Also, all examples reporting high yields are batch processes and are not suitable for industrialization.
As a proposal for practical use as an industrial process, there is one that uses a fluidized bed reactor (Non-Patent Document 4), but the yield of levoglucosan is not high. In addition, there are Patent Documents 1 to 3 as recent proposals, and a considerably high yield is realized, but these are for treating cellulose or the like in an organic solvent at 200 to 400 ° C. and 200 to 750 atm. In addition to solvents, special heat and pressure resistant containers are required.
M.M. Miura et al. , J .; Wood Sci. (2001) 47: 502-506. Japanese Patent Laid-Open No. 2-101093 JP2001-205070 JP 2003-342289 A

  As a result of detailed examination of the behavior of the product in this type of thermal decomposition, the present inventors have made the present invention. Conventionally, in the dry pyrolysis method intended for industrialization, although importance is attached to the point of rapidly heating the raw material, the device for collecting the product has been insufficient. In the above fluidized bed process (Non-patent Document 3), the residence time of the product in the high temperature region is evaluated to be about 0.5 seconds. However, in the case of an organic substance once vaporized, secondary decomposition occurs for 0.5 seconds. It is enough time. By shortening the residence time, the recovery rate of the primary product can be remarkably increased, and the present invention realizes this. As described above, the present invention is mainly intended for the production of levoglucosan from cellulose and starch, but various natural and synthetic organic compounds can be used as target raw materials. In these, useful components other than levoglucosan, for example, cellobiosan, levoglucosenone, furanosan, which are analogs of levoglucosan, and extract components such as terpenes, alkaloids, phenols, etc. can be obtained.

The following method is adopted as a method for shortening the residence time in the high temperature region of the primary product of pyrolysis:
{Circle around (1)} Two flat plates (metal belts or rotating disks) that are movable in a plane are installed in a sealed container filled with an inert gas under reduced pressure or atmospheric pressure, almost horizontally and facing each other.
(2) A mechanism for supplying the raw material by coating or shaking off the upper surface of the non-heated portion of the lower flat plate is provided, and the raw material is introduced into the heating portion by in-plane movement of the flat plate to cause thermal decomposition. Heating is performed with an electric heater from the lower back of the flat plate.
(3) The portion of the upper flat plate facing the heating portion of the lower flat plate is cooled from the upper back surface, and the gas or aerosol generated from the raw material is condensed and captured in the cooling portion. At this time, the interval between the opposing surfaces of the two flat plates is adjusted in the range of 5 mm to 100 mm in accordance with the aspect of the sample and the behavior of thermal decomposition.
(4) The product adhering to the upper flat plate is carried out of the thermal decomposition region by the movement of the flat plate, and is scraped off and collected by a blade that is in close contact with the flat plate. Similarly, the residue remaining on the lower movable plate is removed by scraping with a blade installed outside the pyrolysis region.

  In the dry pyrolysis process, the raw material supply method strongly affects the performance. That is, since the raw material is heated from below in ordinary batch heating, the vaporized decomposition product is captured by the raw material layer present above and remains in the high temperature region, and the secondary decomposition proceeds. In order to avoid this, in the present invention, the raw material is supplied in the form of a thin layer, preferably 5 mm or less, as powder or granules. In this way, since the thin raw material layer is thermally decomposed in a short time, the capture of the product by the raw material itself is suppressed, and the product can be recovered with a high yield.

Means for solving the problem

The opposing horizontal plates in the apparatus described in 1 are constructed using two belt conveyors made of heat and corrosion resistant metal, preferably stainless steel, and the container is evacuated by a vacuum pump and operated. The present invention can be implemented. Or it can comprise with two rotation flat plates of the same material instead of a belt conveyor. The translation or rotation of these flat plates is driven by an electric motor installed in the sealed container via a controller provided outside the sealed container, and the speed is set to a linear speed according to the combination of the sample type and the heating temperature. In the range of 5 mm to 500 mm per minute, preferably 50 mm to 150 mm per minute. Heating is performed with an electric heater having a temperature control mechanism by feedback, and the upper surface temperature of the heating part is set to 350 ° C. to 550 ° C. In the case of cellulose, a range of 400 ° C. to 500 ° C. is preferable, and in the case of starch, from 350 ° C. A range of 450 ° C. is preferred. The cooling unit can be cooled to -15 ° C to 20 ° C by circulating water or water containing an antifreeze agent from an externally installed cooler, or air cooled (radiated cooling under reduced pressure) by a heat sink. good. The atmosphere in the sealed container is set to a high depressurization with a residual pressure of about 10 mmHg or less, or an inert gas is intentionally introduced in the range of 10 mmHg to 760 mmHg, preferably 20 mmHg to 50 mmHg to control thermal decomposition. In the latter case, an inert gas, preferably nitrogen or argon, is used as the gas.
Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to the examples.

ホッパ内残渣とは振落としきれなかった原料の量であり、実際の工程にあっては再使用できるものなので、原料消費量からは除去して収率を計算する。熱分解残渣とは下側平板から掻き落された炭化物であり、これは原料消費量に含める。また、レボグルコサンの収率は液体クロマトグラフィーによる検出量であり、精製単離量ではない。この項は以下の実施例においても同じである。Using the apparatus shown in FIG. 1, the lower belt conveyor B is continuously operated in the direction of the arrow at a speed of 50 mm / min under a reduced pressure of about 2.5 mmHg. The upper and lower belts are made of stainless steel with a thickness of 0.1 mm, and the width is 120 mm for the upper belt and 40 mm for the lower belt. The central part of B is heated by an electric heater C to 330-410 ° C. As a raw material, 5 g of corn starch (Wako Pure Chemical Industries) absolutely dried is put into hopper A, and it is continuously fed to belt conveyor B little by little by shaking it through a 40-mesh metal net installed underneath. The upper collecting belt conveyor D is continuously operated in the direction of the arrow, and the central portion thereof is cooled to below room temperature by the cooler E. The decomposition products adhering to the upper belt are scraped off by a metal blade G installed in close contact with the belt. The solid residue remaining in the lower belt shape is scraped off by the blade F. Table 1 shows the results of weighing substances collected by the blade G (hereinafter referred to as “syrup”) and analyzing them by liquid chromatography (ion exchange column, solvent = 70% acetonitrile aqueous solution).

The hopper residue is the amount of raw material that could not be shaken off, and can be reused in the actual process, so the yield is calculated by removing it from the raw material consumption. The pyrolysis residue is a carbide scraped off from the lower flat plate, and this is included in the raw material consumption. The yield of levoglucosan is the amount detected by liquid chromatography, not the amount of purified isolation. The same applies to the following examples.

In Example 1, Table 2 shows the results when treated at a heater temperature of 430 ° C. using 5 g of dry cellulose powder (Whatman CF11 and Avicel SF manufactured by Asahi Kasei) as raw materials.

In Example 1, Table 4 shows the results of treatment using Avicel SF and 5 g of corn starch absolutely dried as raw materials and introducing nitrogen from 2.3 mmHg to 60 mmHg into a sealed container.

It is a front sketch of the belt conveyor type device used in Example 1 and Example 2. The entire apparatus is installed in a sealed container that can be decompressed or replaced with an inert gas.

Explanation of symbols

A. Raw material supply hopper Lower belt conveyor C.I. Heating plate Upper belt conveyor Cold plate F. Undecomposed raw material and carbonized residue recovery unit Decomposition product recovery section

Claims (4)

  The sealed container is provided with two flat plates which are installed substantially horizontally opposite to each other and movable in the plane, that is, an upper plate and a lower plate, and a mechanism for heating a part of the lower plate from below, A heating apparatus including a mechanism for supplying a raw material to the upper surface of a non-heating portion of a flat plate, a mechanism for cooling a part of the upper flat plate from above, and a heating portion and a cooling portion that face each other. A heating apparatus in which one or both of the two movable flat plates of claim 1 are belt conveyors. A heating apparatus in which one or both of the two movable flat plates of claim 1 are rotating disks.   A method for collecting a solid or liquid raw material by pyrolysis or evaporation using the apparatus of claim 1 and attaching the vaporized material to the lower surface of the upper flat plate.

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