JPS60255651A - Pyrolytic process and apparatus for lime stone or like - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method and apparatus for thermally decomposing ores such as limestone, ie, limestone and dolomite, which undergo a thermal decomposition reaction when heated to produce carbon dioxide gas (carbon dioxide). Regarding improvements.

[Background of the Invention] As is well known, when limestone, dolomite, magnesite, etc. are heated above a predetermined temperature, they are thermally decomposed into calcined material and carbon dioxide gas. For example, if limestone is heated to cause pyrolysis, quicklime (C
ab) and carbon dioxide gas. In the case of dolomite and magnesite, calcined dolomite (CaO-MgO
) and carbon dioxide gas.

It decomposes into magnesia (MgO) and carbon dioxide gas.

However, since conventional limestone and dolomite calcining equipment used a direct heating method, it was not possible to directly recover the carbon dioxide gas produced by thermal decomposition.

That is, conventionally, limestone or dolomite ore is calcined (pyrolyzed).
To do this, fill a vertical furnace with limestone or put limestone in a rotary kiln, burn fuel in the furnace, or blow heated gas into the furnace to convert the raw material ore. It was heated by convection or radiant heat transfer.

According to this direct heating method, mixing of carbon dioxide gas generated by decomposition of ore and heating gas such as fuel combustion gas is inevitable. The concentration of carbon dioxide in the mixed gas of carbon dioxide produced by thermal decomposition and heating gas such as combustion gas is 25 to 40 vol.

% and has low industrial utility value.
The current situation is that it is released into the atmosphere and disposed of.

[Object of the Invention] The object of the present invention is to solve the problems of the above-mentioned prior art, and to provide a limestone that can recover carbon dioxide gas generated by a thermal decomposition reaction as it is, that is, without mixing heating gas such as combustion gas. The purpose of the present invention is to provide a thermal decomposition method and apparatus such as the following.

Another object of the present invention is to provide a method and apparatus for thermally decomposing limestone, etc., which can be decomposed at a lower temperature than before.

[Structure of the Invention] In order to achieve this object, the present invention places raw materials such as limestone and dolomite in a reaction vessel and indirectly heats them, so that the heated gas such as fuel combustion gas is thermally decomposed in the reaction vessel. In the method of heating limestone etc. to thermally decompose it into quicklime etc. and carbon dioxide gas, raw materials are placed in a container and the raw materials are passed through the container wall. A method for thermally decomposing limestone, etc. characterized by heating indirectly, and having an inlet for limestone, etc., an outlet for quicklime, etc., and an outlet for generated gas, and at least a part of the wall surface thereof. A reactor main body comprising a reaction vessel with a heat transfer surface made of a thermally conductive material, an outer shell installed on the outside of the heat transfer surface, and a heated gas passage provided between the outer shell and the wall surface. The gist of the present invention is an apparatus for thermally decomposing limestone, etc., which is characterized by comprising:

In the present invention, limestone, etc. refers to limestone, dolomite, magnesite, etc., which is heated to form a solid such as quickstone/ash, calcined dolomite, magnesia, etc. (in the present invention, this solid is referred to as quicklime etc.) and carbon dioxide gas. An ore that decomposes.

[Embodiments of the Invention] Hereinafter, embodiments will be described with reference to the drawings, and the present invention will be explained in further detail.

FIG. 1 is a diagram showing the basic configuration of the pyrolysis apparatus of the present invention. Reference numeral 10 denotes a reactor main body, which includes a cylindrical reaction vessel 12 made of heat-resistant steel or other material with heat resistance and thermal conductivity, and is installed so as to surround the outer periphery of the reaction vessel 12, and is connected to the side circumferential surface of the vessel 12. an outer shell 16 defining a heated gas passageway 14 therebetween. In the figure, 20 indicates the pipe 1 to the passage 14.
This is a high-temperature heating gas generator that supplies high-temperature heating gas through 8.

At the top of the container 12 are a raw material inlet, a raw material introducing device 22 installed at this inlet, and an outlet 2 for the generated carbon dioxide gas.
4 is provided at the bottom of the container 12, and an extraction device 2 is provided at the bottom of the container 12 for removing quicklime, etc. that has undergone a thermal decomposition reaction.
6 is provided. 28 is an inlet for high temperature heating gas, 3
o is an outlet for high-temperature heating gas. Further, 32 is a heat insulating material. Note that the introduction device 22 and the extraction device 26 are each configured to be able to be sealed.

To produce quicklime using the apparatus configured as shown in FIG. The heat of the high-temperature heated gas is transmitted to the limestone in the container 12 through the wall surface of the container 12, heating it and pyrolyzing it.

The generated carbon dioxide gas is taken out of the container 12 from the carbon dioxide gas outlet 24, and quicklime is taken out from the outlet 26.

In this way, the carbon dioxide gas generated by thermal decomposition is taken out from the outlet 24 without mixing with the heated gas, and thus is recovered as highly pure carbon dioxide gas.

FIG. 2 is a longitudinal sectional view of another embodiment of the present invention, and FIG. 3 is a sectional view taken along the line II--II in FIG.

In the device of this embodiment, two tower main bodies 10a, 10
b is installed, and heated gas inlet/outlet 18a at the bottom of each device main body is installed.
, 18b are connected to the high temperature heating gas generator 20 via pipes 13a and 18b, respectively. Further, the heated gas inlets and outlets 30a and 30b at the top of each device main body are connected to each other, so that the heated gas discharged from one device main body can be used for preheating the other device main body.

The other parts of the device main body 10a and iob have the same configuration as the device main body 10 in FIG. 1, and the same members or parts in FIG. 2 as those in FIG.
Each is shown with a or b added to the reference numeral in FIG. 1,
The numerals appended with a refer to the apparatus main body 10a, and the numerals appended with b refer to the apparatus main body 10b.

In addition, in Figure @2, there is a hopper 3 in the upper part of the device main body.
4. A raw limestone supplying device 40 consisting of a feeder 36 and a belt conveyor 38 that can rotate in forward and reverse directions is installed, and the lower part of the device body receives the product (quicklime) taken out from the device bodies 10a and 10b. A tank 41 is provided for storing the water and, if necessary, providing cooling equipment for cooling the water.

Further, gas coolers 44a, 44 are connected to gas outlet ports 24a, 24b of containers 12a, 12b via piping 42a, 42b.
b is connected, and furthermore, the pipes 48a, 48b, 50
It is connected to a vacuum pump 52 via. 46a in the figure
, 46b, 54a, and 54b are the pipes 48a and 48, respectively.
b, 18a, and 18b.

In this device, piping 18'a, 1 between the valve 54a and the gas inlet/outlet 28a and between the valve 54b and the gas inlet/outlet 2.8b.
From 8b, pipes 56a, 56 with valves 58a, 58b
b is branched. Note that the raw material introduction devices 22a, 22b,
The quicklime extraction devices 6a and 26b are configured to seal the insides of the containers 12a and 12b, respectively, similarly to the device shown in FIG.

Next, the operation of this embodiment device will be explained.

The raw limestone is supplied into the containers 12a and 12b via the hopper 34, feeder 36, and belt conveyor 38, and is filled into the containers 12a and 12b, resulting in the state shown in FIG.

In FIG. 2, the thermal decomposition of the raw limestone in the container 12/a
Preheating is then performed within the container 12b. That is, valve 5
4a and 58b are opened, and 54b and 58a are closed, and the high-temperature heated gas generated in the high-temperature heated gas generator 20 is first passed through the pipe 18.
a into the gas passage 14a of the device main body 10a and the container 1
The raw limestone in 2a is heated to thermally decompose it into quicklime C and carbon dioxide gas. Then, the gas whose temperature has become low after passing through the passage 14a is sent to the main body of the device from the gas inlets and outlets 30a and 30b.
The gas is introduced into the gas passage 14b of Ob. This gas is in the passage 14
After passing downward through the inside of the container 12b and preheating the raw limestone in the container 12b, the gas is discharged from the gas inlet/outlet 28b via the pipe 56b.

On the other hand, the inside of the container 12a is depressurized by a vacuum pump 52, and the carbon dioxide gas generated by the thermal decomposition reaction inside the container 12a is introduced into the cooler 44a from the piping 42a and cooled, and then passes through the pump 52 to produce a product gas. recovered as °.

Note that the raw material supply device 40 is provided with a raw material drying device, pipes 56a and 56b are connected to this drying device, and the gas that has passed through the passages 14a and 14b is further introduced into this drying device.
The raw material may be dried and preheated.

When the thermal decomposition in the container 12a is completed after a predetermined period of time has elapsed, the valves 54a and 58b are closed.
is opened so that the high-temperature heated gas from the high-temperature heated gas generator 20 first passes through the passage 14b of the apparatus main body 12b from the pipe 18b, and then passes through the passage 14a of the apparatus main body 12a. Further, in the carbon dioxide gas recovery system, the valve 46a is opened and the valve 46b is closed. Then, open the quicklime removal device 26a and remove the container 1.
The quicklime C in 2a is discharged to the tank 41. At this time, as shown in FIG. 4, the quicklime C
a small amount remains in the container 12a. This is the container 12a
This is because heat is not necessarily sufficiently transmitted to a portion at a lower level than the waste inlet/outlet 28a, and there is a possibility that baking in this portion may be insufficient.

After the quicklime extraction work from the container 12a is completed, the raw material supply device 40 is operated to fill new raw material limestone into the container 12a. Then, as mentioned above, after the high-temperature heated gas passes through the passage 14b, the valve is opened and closed so that it flows through the passage 12b, so the limestone is thermally decomposed in the container 12b, and the limestone is decomposed in the container 12a. Preheating is performed. The heating gas discharged from the container 12a is passed through the pipe 56.
It is either discharged into the atmosphere from a or, if a drying device is installed in the raw material supply device 40, introduced into the drying device.

Further, the carbon dioxide gas generated in the container 12b is cooled by the cooler 44b, and then passed through the pump 52 and recovered as a product.

After the thermal decomposition is completed in the container 12b, the valves are opened and closed so that the high-temperature heated gas flows through the passages 14a and 14b again in this order, and the valve 48a of the carbon dioxide recovery system is opened and the valve 48b is closed. Let's do it. Next 1. Open the outlet 26b with N and discharge the quicklime in the container 12b to the tank 41 (at this time, make sure that the quicklime remains at a lower level than the gas inlet/outlet 28b in the same way as above). , and return to the state shown in Figure 2.

By repeating the above steps, the raw limestone can be thermally decomposed efficiently, and the containers 12a, 12
The carbon dioxide gas produced by thermal decomposition of limestone in b can be recovered without mixing with the heating gas.

Furthermore, in the embodiment described above, since the vacuum pump 52 reduces the pressure in the container 12a or 12b in which the pyrolysis reaction is taking place, the pyrolysis reaction of the limestone proceeds at a lower temperature than usual. That is, as shown in Figure 6, which is a graph showing the decomposition equilibrium pressure of CaCO3, normal pressure (760 mm Hg
), the thermal decomposition reaction of limestone does not proceed unless it is heated to about 880°C or lower, but it decomposes at a much lower temperature under reduced pressure. For example, if the pressure is reduced to 100 mmHg, it decomposes at about 720°C. will be carried out. Therefore, the temperature of the high-temperature heating gas can be lowered, and fuel costs can be reduced accordingly.

Note that if the pressure inside the containers 12a, 12b is not reduced or if the degree of pressure reduction is small, a normal suction device such as an axial fan with low suction pressure can be used instead of the vacuum pump.

Although a cylindrical container is used in the above embodiment, a container with a polygonal cross section may also be used. If the diameter of the container is large, a tube may be provided at the axial center of the container and the heated gas may flow through this tube. Accordingly, it is also possible to perform sufficient heating even at the axial center of the container.

Furthermore, in the above description, limestone is used as a raw material, but the present invention can generally be applied to the thermal decomposition of substances that dissociate carbon dioxide gas by heating, such as dolomite and magnesite.

[Effects of the Invention] As detailed above, the present invention heats the raw material indirectly, and the carbon dioxide gas generated by thermal decomposition is recovered without mixing with other gases. , it is possible to recover and reuse carbon dioxide gas that was previously released into the atmosphere. It is also possible to perform the thermal decomposition reaction under reduced pressure to lower the thermal decomposition temperature and reduce fuel costs.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views of the embodiment device, FIG. 3 is a sectional view taken along line nI-m in FIG. 2, FIGS. 4 and 5 are partial views of the embodiment device, and FIG. The figure is a graph showing the decomposition pressure of limestone. 10, loa, 10b--reactor main body, 12.12
a, l 2 b - Reaction vessel, 14.14a, 14
b... Heating gas passage, 16.16a, 16bi... Outer shell, 18a, 18b, 42a, 42b, 48a,
48b, 50.56a, 56b...Piping, 20.
...High temperature heated gas generator, 22.22a, 22b...Raw material introduction device, 24.
24a, 24b... Carbon dioxide gas outlet, 26.26
a, 26 b...quicklime extraction device, 32.32a,
32 b - Heat insulation material, 46a, 46b, 54a, 5
4b, 58a, 58b...Valve. Agent Patent Attorney Tsuyoshi Shigeno Figure 1

Claims (5)

[Claims] (1) A method of thermally decomposing limestone etc. into quicklime etc. and carbon dioxide gas, characterized in that the raw material is placed in a container and the raw material is indirectly heated through the wall of the container. A method of thermal decomposition of limestone, etc. (2) Claim 1 states that the pressure inside the container is reduced and the material is thermally decomposed at a temperature lower than the decomposition temperature of the raw material at normal pressure.
The pyrolysis method described in section. (3) Equipped with a reaction vessel having an inlet for limestone, etc., an outlet for quicklime, etc., and an outlet for generated gas, and having at least a portion of its wall surface as a heat transfer surface made of a thermally conductive material, and
An apparatus for pyrolyzing limestone, etc., comprising a reactor main body in which an outer shell is installed outside the heat transfer surface and a heated gas passage is provided between the outer shell and the heat transfer surface. (4) Installing a plurality of the reactor bodies and connecting the heated gas passages of each body, so that the heated gas discharged from the heated gas passage of one reactor body is transferred to the heated gas passage of the other reactor body. The apparatus for thermally decomposing limestone, etc. according to claim 3, characterized in that the apparatus is capable of being introduced. (5) Claim 3, characterized in that a pump for reducing the pressure inside the reaction vessel is connected to the gas outlet of the reaction vessel.
The apparatus for thermally decomposing limestone, etc., according to item 1 or 4.