JPS60248791A - Moving bed type dry distiller - Google Patents

Abstract

PURPOSE:A gas of low oxygen content is introduced, as an oxidizing agent, into the moving bed to combust a part of coal so that heating is effected up to the temperature necessary for dry distillation, whereby high efficiency of dry distillation, especially of low-grade coal becomes possible with a small-sized moving bed reactor. CONSTITUTION:A gas distributor 2 is set at the middle in the vertical direction in the dry distillator and a gas of low oxygen content such as an air diluted with inert gas or exhaust gas containing appropriately lowered oxygen content is fed from the distributor to combust a small amount of coal, as the temperature is measured with a thermocouple 3 set right above the distributor 2 to avoid the excessive rise of the temperature. And the combustion heat is utilized to raise the temperature up to the level necessary for dry distillation of coal to activate coal particles, thus enabling stabilized dry distillation.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an apparatus for carbonizing coal, and particularly for reducing the water absorption of low-grade coals with high water content such as lignite and lignite by low-temperature carbonization. The present invention relates to a moving bed type carbonization apparatus used in this process.

[Background of the invention]

Coal is generally used for various purposes as fuel and for the chemical industry, but most of them are high-grade coal called bituminous coal. On the other hand, low-grade coal such as sub-bituminous coal and lignite accounts for more than half of the coal existing on the earth. However, low-rank coal has a high moisture content of 20% to 70%, which causes a decrease in the thermal efficiency of the combustor and in the transportation efficiency. Furthermore, if stored dry, it is likely to reabsorb moisture and spontaneously ignite, so it is not widely used at present. In other words, in order to widely use low-grade coal as fuel and for chemical industry purposes, it is necessary to perform appropriate treatments such as dehydration and prevention of re-absorption, and reform it into coal that absorbs less water after transportation and storage. be.

When low-rank coal is carbonized at a low temperature of about 600° C. or lower, the woody groups in the low-rank coal can be thermally decomposed, and as a result, water absorption can be permanently reduced. As a method for realizing this, for example, a technique disclosed in Japanese Patent Publication No. 57-115965 has already been proposed. This invention has a heating temperature increase rate of 100℃/
Final heating temperature 300℃ to 500℃ for 11in or more
Rapidly heat up to
Rapidly cooling the coal to 250°C or less at temperatures above 100°F to solidify and close the pores in the coal without volatilizing the liquid tar substance that oozes out onto the surface of the coal during thermal decomposition of the coal.
It lowers the specific surface area of coal and reduces the amount of moisture absorbed by the coal.

In a fluidized bed carbonization apparatus suitable for carrying out the above-mentioned invention, it is necessary to adjust the particle size of one coal to about 10 mm or less,
In addition, a part of the coal particles is discharged from the carbonization apparatus before being thermally decomposed, so that uniform carbonization cannot be carried out.

On the other hand, in a moving bed type carbonization device, there is no need to make the coal particles finer, and the flow of particles is similar to the extrusion flow, allowing for more uniform carbonization, but the heat transfer rate is relatively small and the size of the carbonization device is large. There are drawbacks to doing so.

[Purpose of the invention]

The purpose of the present invention is to burn a small amount of coal in a moving bed carbonization apparatus while suppressing excessive temperature rise, and use the heat generated at this time to raise the temperature to the temperature required for carbonization of the coal. The goal is to efficiently carbonize coal using a small moving bed type device.

[Summary of the invention]

The present invention has confirmed that coal particles are activated in the initial process of carbonization, and stable combustion progresses even with low concentration oxygen-containing gas, and that the temperature rise at this time can be controlled within a temperature range suitable for carbonization of coal. However, by burning a portion of the coal to be carbonized in the moving bed and heating it internally, the moving bed carbonization device can be downsized and the structure simplified.

[Embodiments of the invention]

The figure shows an embodiment of the invention. Coal is supplied through particle supply pipe 11
The particles are supplied to the upper part of the moving bed type carbonization device 1, carbonized while falling through the carbonization device 1, and taken out from the system through a particle extraction pipe 12 provided at the bottom of the carbonization device 1. Particle extraction pipe 1
2 is connected to a known particle flow rate adjusting device such as a rotary valve or a screw to keep the height of the particle layer in the carbonizer 1 almost constant.

A gas distributor 2 is installed at the middle stage in the height direction of the carbonizer 1, and combustible gas with a low oxygen concentration is supplied from there. A thermocouple 3 is installed directly above the gas distributor 2 and is used as a control index for the combustible gas supplied from the gas distributor 2. Thermocouple 3 may be any other suitable temperature sensing end. Gas generated during carbonization.

Tar vapor and the like are taken out of the thread through the gas extraction pipe 4.

In the present invention, combustible gas with a low oxygen concentration means an oxygen-containing gas with a concentration lower than the oxygen concentration in the air, and specifically refers to air diluted with a gas containing only a lower concentration of oxygen or an appropriate amount of residual oxygen. This includes combustion exhaust gas, etc. The required oxygen concentration varies depending on the reactivity of the coal to be carbonized, the gas temperature at the time of supply, and the carbonization temperature.

A moving bed reactor with a cross section of 500 + IIoX 500 mm and a height of approximately 2 m was used as a carbonization vessel, and subbituminous coal having the properties shown in Table 1 was pre-dried at 110°C from the particle supply pipe.
It was supplied at a flow rate of kg/h.

Table 1 When kerosene combustion exhaust gas with a residual oxygen concentration of 10% and a temperature of 150°C was supplied from the gas distributor 2 at a rate of 3 Onf/h, the thermocouple 3 indicated a maximum temperature of 4 at 70 m+n above the gas distributor.
The temperature was 20°C, which was stable over time. At this time, carbonized carbon having the properties shown in Table 2 was obtained from the particle extraction pipe 12.

Table 2 For comparison, when room temperature air was supplied from a gas distributor at IOJ/h using the same device as above, the thermocouple 3 showed a reading of 300 to 130°C, which varied over time. At this time, particles that could be considered to be almost completely burned ash were obtained from the particle extraction pipe 12 mixed with carbonized coal.

Furthermore, the gas distributor 2 is removed from the above device, and the outer diameter 3
Two rows of 4mm tubes separated by 200mm horizontally, and 10 rows vertically.
011! A tubular heat exchanger consisting of 10 rows separated by I was inserted into the moving bed, and kerosene combustion exhaust gas at about 700°C was passed through the pipes and indirectly heated with the same coal flow rate as in the above example. The coal particles inside were heated to a high temperature only around the heating tube, and uniform carbonized coal could not be obtained.

〔Effect of the invention〕

According to the present invention, uniform carbonization of coal becomes possible with a smaller moving bed carbonization apparatus.

[Brief explanation of drawings]

The figure is a schematic diagram of an embodiment of the invention.

Claims (1)

[Claims] 1. In a moving bed reactor for carbonizing coal, a gas containing oxygen lower in concentration than that of air is introduced into the moving bed as an oxidizing agent, and a part of the coal is A moving bed carbonization apparatus characterized by burning and heating the coal to a temperature required for carbonization. 2. In claim 1, a temperature detection end of coal or combustion gas is provided near the introduction part of the low oxygen-containing gas, and the flow rate of the low oxygen-containing gas is determined. A moving bed carbonization apparatus characterized in that the temperature detected at the detection end is controlled by preheating temperature and oxygen concentration.