JPH0826328B2 - High temperature pressure vessel for organic carbonization - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a high temperature pressure vessel for carbonization of organic matter.

[0002]

2. Description of the Related Art Organic substances, particularly solid organic substances such as wood, coal, pitch, resin, animal bones and their composites are heated in the substantial absence of air, decomposed and remain. The technology of recovering carbon substances and / or generated volatiles, gases, vapors, etc. as products, so-called carbonization, has been known for a long time.

Such a carbonization technique is also important in a recent industrial field, for example, a special field of chemical industry. Even if the same starting material is used, the physical properties (mechanical strength,
It is also well known that crystal forms, porosity, pore diameter, specific surface area, etc.) and chemical properties are different. Therefore, it is important to select the optimum raw material, set the optimum dry distillation conditions, and carry out the dry distillation according to the desired product and the properties desired for it.

[0004] For example, when producing activated carbon for adsorbing a specific substance, factors such as presence / absence of introduction of an inert gas atmosphere in the carbonization process, pressure, heating temperature, heating time, etc. are appropriately combined to obtain the target substance. It is desirable to obtain activated carbon having properties such as optimum porosity, pore diameter, and specific surface area for the adsorbent. It is also clear that it is desirable to purposefully set the carbonization conditions, for example when activated carbon is produced for use as a catalyst or catalyst support for certain reaction processes.

When the organic matter is carbonized, about 600 to 65 is used.
Temperatures of 0 ° C. or higher are commonly used. In some cases, it is desirable to apply dry distillation heating as a cycle consisting of preheating, main heating, and postheating. Recently, dry distillation is often carried out in a high-pressure inert gas atmosphere. In any case, the carbonization temperature value and its control are one of the most important factors in the carbonization process.

In the past, dry distillation was sometimes carried out using a pressure vessel of an internal heating type. However, since there is no suitable insulating material and insulation method, the dry distillation is not performed because the nichrome or kathal heater is not sealed against the atmosphere. It is exposed to volatile substances and gases generated inside, and chemical reaction occurs under high temperature and high pressure conditions, resulting in insulation failure due to accumulation of reaction products,
Corrosion of the heater wire or failure such as disconnection occurred, which was extremely inconvenient in practical use.

For the purpose of solving such a problem, an internal heating type pressure resistant container using a sheath heater as a heating source has been proposed. However, the conventional sheath heater is not satisfactory in heat resistance, and in a high-temperature atmosphere for carbonization (for example, at about 600 to 650 ° C.), a small amount of nichrome wire metal evaporates and the surrounding inorganic oxide insulating material is evaporated. It penetrates and diffuses into the layer to form a conductive path, significantly reducing its insulation resistance, and directing it from the nichrome wire to the sheath (sheath) metal material (for example, Incoloy) and further for the carbon material to be processed (for example, pitch, its There is a serious drawback that causes an accident of electric current leakage toward thermal decomposition residual products, etc.).

Thus, in order to avoid the problem, a high frequency heating method has been proposed, but it consumes a large amount of electricity and has not been used for anything other than a small capacity for practical use.

Therefore, conventionally, an external heating method has been generally adopted in which the dry distillation container is heated by an externally installed heat source. Since the use of high temperature and the use and generation of high pressure as described above are generally involved in the carbonization, the carbonization container is made of a material (for example, SUS316 stainless steel) that can withstand such severe conditions. However, the wall thickness must be increased. Furthermore, in the case of the external heating method, the outer wall is heated to a relatively high temperature over almost the entire surface, and the heat is transferred through the wall to the temperature required inside the container (for example, about 650 ° C). Must be achieved and maintained. Therefore, material selection and strength design must be performed in consideration of the temperature value inside and outside the container wall and the temperature difference (temperature gradient).

For example, as a small-sized container used for a research test, a container having an internal volume of 1.5 liter is SUS3.
When designing using 16 stainless steel material, the following can be mentioned as an example of the specifications that conform to the Type 1 Pressure Vessel Manufacturing Standard of the Labor Standards Bureau.

Inner volume 1.6 liters Inner diameter 80 mm Outer diameter 220 mm Wall thickness 70 mm Weight (container body + flange + lid) About 215 kg Internal pressure 300 atm Container outer wall temperature 750 ° C Inner wall temperature 650 ° C Wall center temperature 700 ° C

For reference, the allowable stress values of the SUS316 material at various temperatures are roughly as follows. 700 ° C. 3 kg / mm ² 110 ° C. 11 kg / mm ² 40 ° C. 13.1 kg / mm ²

In the case of the above-mentioned specification using the external heating method, the amount of the material used should be approximately four times or more as compared with the case of using the material at room temperature in terms of the safety factor of the material. Its high weight makes it inconvenient to handle. Under the above-mentioned use conditions, if the inner volume of the container is increased to 60 liters, which is practical, the total weight will exceed 2 tons.

It is also difficult to heat a container made of a large amount of metal material from the outside so that the internal temperature of the container reaches a predetermined value accurately and quickly, and it is difficult to maintain and control it, and it is also clear that its thermal efficiency is low. is there. For example, the SUS having an inner volume of 1.5 liters, an inner diameter of 80 mm, and a wall thickness of 70 mm as illustrated above.
It takes about 5 to 6 hours to heat the 316 stainless steel product container from the outside with a sheath heater having an output of 10 kW and to bring the inner wall surface to a temperature of 650 ° C. Further, it takes a long time of about 20 hours to cool the container to a temperature at which the contents can be safely taken out after the completion of the dry distillation, and the work efficiency is remarkably low.

[0015]

In view of the above-mentioned drawbacks of the high-temperature and high-pressure container conventionally used for carbonization, the present inventors have
Improved work efficiency, easier control of operating conditions, improved thermal efficiency,
The present invention has been completed by planning light weight of the device, reducing equipment installation cost and operating cost, extending equipment life, improving productivity, etc.

[0016]

The present invention adopts an internal heating system in which a sheath heater having excellent heat resistance is installed as a heat source inside a pressure vessel, and thereby a material to be carbonized is directly heated. The above-mentioned problems are solved or greatly reduced.

In the present invention, a sheath heater that withstands high temperatures is used in a high temperature pressure vessel for organic matter carbonization. A conventional sheath heater passes a nichrome wire through a cis (envelope tube) made of an oxidation-resistant and corrosive metal (for example, “Incoloy”), and an insulating material is provided in an annular space between the nichrome wire and the sheath. As described above, in such a sheath heater, a small amount of nichrome wire metal evaporates during use, penetrates into the insulating material layer, diffuses, and reaches the inner wall of the sheath to reach the nichrome wire and the sheath. In addition,
It is unsuitable for internal heating of high temperature pressure vessels for carbonization because of the risk of forming a current leakage path towards the material (eg pitch) during carbonization or the carbonized product.

However, when a special substance having a good metal vapor trapping property, for example, high-purity magnesium oxide (magnesia) is used as the insulating material, even if vapor of the nichrome wire metal is generated, the insulation adjacent to the insulating material on the spot. It is immediately captured by the material portion, does not penetrate deeply into the insulating material layer, does not diffuse, and cannot reach the inner wall surface of the sheath. Therefore, the current leakage problem frequently experienced in the use of conventional low heat resistant sheath heaters at high temperatures does not occur in the high heat resistant sheath heaters of the present invention. As such a high heat resistant sheath heater, for example, one having a nominal heat resistant temperature of 900 ° C. is commercially available, and it has been confirmed that this has a practical continuous heat resistant temperature of 750 ° C.

Therefore, the high heat resistant sheath heater used in the present invention is provided with an insulating material layer for quickly capturing the metal vapor generated from the nichrome wire, the kathal wire or the like at the time of heating in the vicinity thereof. It is possible to use it at temperature for a long time.

The term "dry distillation" in this specification means that a solid or semi-solid organic substance is heated in the substantial absence of oxygen in the presence or absence of an inert gas. It means a process of at least partially decomposing, and is not bound by the meaning of the classical term "carbonization" in a narrow sense.

An example of one embodiment of the high temperature pressure vessel according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view of a high temperature pressure vessel device according to the present invention, in which a suitable metal material such as SUS31 is used.
A cylindrical container body 1 made of 6 stainless steel is provided with a flange portion 2 and a lid 3 is bolted (not shown).
It is supposed to do. A highly heat-resistant coil-shaped sheath heater 4 is provided inside the container body. The sheath heater may have a shape other than the coil shape. In the illustrated example, an inner can 5 for accommodating an organic material to be carbonized is provided inside the coil-shaped sheath heater. This inner can may be omitted if the material is self-supporting under carbonization conditions. The inner wall surface of the container body 4 is preferably provided with a heat insulating material layer 6, which improves thermal efficiency, speeds up heating, protects the inner wall of the container body, and prevents overheating (change in high temperature) of the outer wall.

Preferably, such a container can be immersed in a suitable coolant (usually water) in the cooling bath 7 to keep the outside temperature of the container body low. The heat insulating material layer 6
In a specific example in which the operating temperature (the temperature inside the container) is 6
When the temperature of the inner wall portion, the wall center portion and the outer wall portion of the container body was measured at 50 ° C, it was about 120 ° C and about 11 ° C, respectively.
0 ° C and about 50 ° C. Such a temperature distribution is the above-mentioned example of the temperature distribution in the container wall portion in the case of the conventional external heating type (inner wall 650 ° C; wall center 700 ° C; outer wall 750 ° C).
This is in a range significantly lower than the above, and the safety factor of the material is improved by about four times, and consequently, the usage amount (weight) of the metal material can be drastically reduced.

FIG. 2 is a schematic cross-sectional view of an example of a conventional external heating type high temperature pressure vessel. In this figure, 1 is a container body, 2 is a flange portion, 3 is a lid, 4 is a sheath heater, 9
Is a material storage unit for carbonization.

In the case of a small-sized high temperature pressure vessel for test and research with an internal volume of 1.5 liters, an external heating type vessel is used when a vessel conforming to the Labor Standards Bureau Type 1 Pressure Vessel Manufacturing Standard is manufactured from SUS316 stainless steel material. The approximate weight of the internal heating container is as follows.

External heating type Internal heating type Container body 1 About 85 kg About 30 kg Flange 2 + Lid 3 About 130 kg About 50 kg Total about 215 kg About 80 kg

In the conventional external heating type, since the inside of the container must be heated through the thick container wall,
A heater with a relatively large output is required. However, in the internally heated container according to the present invention, it is sufficient to use a heater with a small output, and the time required for heating to the operating temperature (reaction temperature) and the time required for cooling before taking out the product are shortened.

An example of comparative data regarding heating and cooling of an externally heated and internally heated pressure vessel having an inner volume of 60 liters of a practical size is shown below.

External heating type Internal heating type Internal volume 60 liters 60 liters Container weight 2.5 tons 0.94 tons Used heater output 100 kW 25 kW Internal temperature 650 ° C. rise time Approx. 10 hours Approx. 3 hours Cooling (product can be taken out) time About 20 hours About 4-5 hours

Therefore, by adopting the internal heating type, it is possible to greatly reduce energy consumption and improve work efficiency.

Since the wall of the external heating type container is thick and has a high temperature, seals such as lead wires for various sensors inserted through the wall may be expanded or contracted by the wall or the influence of high temperature. However, since the internal heating container according to the present invention has a small wall thickness and the temperature conditions are not severe, such an accident is unlikely to occur, and the sensor can be appropriately used. Can be attached and used.

Further, when the external heating type container is repeatedly used, the inner wall surface thereof does not lose its luster, and moreover, there is a tendency of pitting corrosion. It turned out to be kept good.

In the case of the external heating type, since the inside is heated through the thick container wall, it is extremely difficult to control the internal temperature value quickly and accurately, but in the internal heating type, the heater is used as a material. Since they are installed close to each other, delicate temperature control can be performed quickly and accurately, which is extremely effective in quality control of products.

In the drawings, for simplification, a nitrogen gas (or other inert gas) inlet port and an exhaust port,
The lead leads for heaters, temperature and pressure sensors for monitoring and control, safety valves, etc. are omitted. For example, in the container of FIG. 1, the temperature sensor can be used for collecting data and controlling feedback by arranging the temperature sensor at an appropriate location of the refrigerant (water), the outer wall of the container, the center of the container wall, the inner wall of the container, the inner can, and the heat insulating material layer. .

[0035]

The high temperature pressure vessel for carbonization using the internal heating method according to the present invention is lighter in weight, operating cost is reduced, energy consumption is reduced, and operation control is performed, compared with the conventional external heating method. It has epoch-making effects in improving accuracy and shortening work time.

[0036]

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a high temperature pressure vessel for carbonization according to the present invention.

FIG. 2 is a schematic vertical sectional view of a conventional external heating type high temperature pressure vessel.

[Explanation of symbols]

 1 Container Main Body 2 Container Flange 3 Lid 4 Sheath Heater 5 Inner Can 6 Heat Insulation Layer 7 Cooling Tank 8 Refrigerant 9 Material Storage for Carbon Distillation

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masaru Kawahara 3-12-10 Totsukahigashi, Kawaguchi City, Saitama Prefecture (56) References JP-A-54-95033 (JP, A) Shoukai-6-129853 (JP, JP, U)

Claims (4)

[Claims] 1. A high temperature pressure vessel for carbonization of organic matter, comprising:
The above container, wherein a highly heat resistant sheath heater is installed inside the container. 2. The container according to claim 1, wherein the sheath heater has a coil shape, and an inner can for accommodating an organic material is provided inside the coil. 3. The container according to claim 1, wherein a heat insulating material layer is provided on at least a part of the inner wall of the container. 4. The container according to any one of claims 1 to 3, further comprising a cooling tank for accommodating a refrigerant for dipping and cooling the container at least partially.