JP2002309266A - Horizontal fluidized-bed drying/cooling method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment method for coal for coke making in which for drying water attached to the coal with hot air, the coal is cooled to a temperature, to prevent the dust generation by evaporating of remaining water during the transport of the coal to a coke oven. SOLUTION: By blowing a gas from plenum chambers 2 (2a, 2b, 2c, 2d) arranged at the lower side through a dispersion plate 3 into a fluidizing section 4 and freeboard sections (5a, 5b, 5c, 5d) arranged at the upper side, coal particles supplied onto the dispersion plate 3 are fluidized and moved horizontally, thus being dried with hot air and cooled. In this apparatus, an intermediate cooling chamber (5c) is installed between drying chambers (5a, 5b) and a cooling chamber (5d). After the coal particles are dried in the drying chambers by supplying hot air, the particles are subjected to cooling in the intermediate cooling chamber while preventing the oxidation of the particles by supplying low-oxygen-concentration gas, e.g. a gas containing an exhaust gas from the freeboard section. In the cooling chamber, the coal particles are finally cooled by supplying air to the temperature at which the evaporation of remaining water does not cause a problem.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for drying moisture adhering to wet powder such as raw coal for a coke oven.

[0002]

2. Description of the Related Art It has been already practiced to reduce the amount of water adhering to raw coal charged in a coke oven by drying to shorten the carbonization time in the coke oven.

[0003] In particular, a fluidized bed is known as having a function of classifying simultaneously with moisture drying. As described in Japanese Patent Application Laid-Open No. 62-192486, this involves floating the entire particle layer while bubbling and bringing the gas and solid particles into contact with each other. The fluidization and drying are performed in accordance with the size relationship, and the small particle size portion is scattered to classify.However, there is no need to separate the drying device and the classification device, and equipment costs and space can be reduced. It is supposed to be. In addition, by using high-temperature exhaust gas from another facility as a hot-air source, it is excellent in that the load on a new heat source facility can be reduced and operation can be performed.

[0004] When coal particles charged into a coke oven are dried by supplying hot air in a fluidized bed, there is a problem in that the dried coal particles are conveyed to the coke oven and dust is generated. This is because the fine particles of the fine powder are destroyed during drying,
This fine powder mainly generates dust during transportation, but not only that, but also because the coal particles after drying are hot, residual moisture evaporates even during transportation, and the fine coal is entrained by this. It is also caused by dusting.

As a technique for eliminating the latter cause, Japanese Patent Application Laid-Open No. Hei 10-246573 discloses that a chamber provided with a fluidized bed is divided into two chambers, an upstream drying chamber and a downstream cooling chamber.
By cooling the raw material dried in the drying chamber in the cooling chamber, it is possible to prevent dust generation and dust adhesion due to evaporation of residual moisture in a processing step after drying with compact equipment.

Japanese Patent Application Laid-Open No. 9-194848 discloses that when a raw coal for a coke oven is fluidized and dried and classified while being moved in a lateral direction, a plenum chamber and a freeboard part are separated from a former part and a latter part by a partition plate. It is shown that it is divided into parts, dried and classified in the former part, and then cooled and classified in the latter part. It is said that this makes it possible to reduce dust generation at a compact site and at low cost.

[0007]

However, the coal particles after the heating and drying may be heated to about 100 ° C., and the coarse coal is particularly difficult to fluidize and stays in the drying chamber to be supplied from the lower part. In some cases, the coal may be heated to a temperature close to the temperature of the hot air, and when air for cooling is brought into contact with such coal, there is a danger of oxidation of the coal, that is, weathering or ignition. Japanese Patent Application Laid-Open No. 9-194848 states that in order to prevent this, a gas having an oxygen content of less than 5% or less than 1% may be supplied in a subsequent cooling step. Securing a large amount of gas having a low oxygen concentration enough to cover all the gas to be cooled to the temperature causes a high cost.

Accordingly, the present invention makes it possible to cool the dried coal while preventing the oxidation of the coal without supplying such a large amount of low oxygen concentration gas.

[0009]

The present invention for solving the above problems is as follows.

(1) A horizontal type in which a gas is blown from a lower plenum chamber to an upper fluidizing portion via a dispersion plate to fluidize particles supplied on the dispersion plate, and is dried after hot air while being moved in a lateral direction and then cooled. In the fluidized bed drying / cooling method, the plenum chamber and the freeboard section are moved in the moving direction of the particles to be dried by three.
And an intermediate cooling chamber is provided between the first drying chamber and the last cooling chamber. Hot air is supplied in the drying chamber to dry the particles to be dried. %. A horizontal fluidized bed drying / cooling method, comprising supplying a gas mainly composed of air in a cooling chamber after supplying a low oxygen concentration gas of not more than 10% to suppress the oxidation of particles and performing intermediate cooling.

(2) The method for drying and cooling a horizontal fluidized bed according to the above (1), wherein the low oxygen concentration gas includes a gas once discharged from a fluidized bed freeboard section.

(3) The horizontal fluidized bed drying / drying method according to the above (1) or (2), wherein a gas for drying or cooling is directly supplied to the fluidizing section and / or the free board section without using a dispersion plate. Cooling method.

(4) A gas is blown from the lower plenum chamber to the upper fluidizing section and the freeboard section via the dispersing plate, and the particles to be dried supplied on the dispersing plate are fluidized and moved laterally. In a horizontal fluidized bed drying / cooling device that cools after drying with hot air, the plenum chamber and freeboard section are divided into three or more chambers in the direction of particle movement, and an intermediate space is provided between the first drying chamber and the last cooling chamber. A horizontal fluidized bed drying / cooling apparatus, comprising: a cooling chamber; and a pipe capable of circulating and using an exhaust gas in an upper part of the fluidized bed at least in a gas pipe supplied to a plenum chamber corresponding to an intermediate cooling chamber.

(5) The horizontal fluidized bed according to (4), wherein a side pipe for directly supplying a drying or cooling gas is provided in the fluidizing section and / or the free board section without using a dispersion plate. Drying and cooling equipment.

(6) The horizontal fluidized-bed drying / cooling apparatus according to (4) or (5), wherein a water sprinkling device and / or an inert gas supply device are provided at least in a free board portion of the intermediate cooling chamber.

[0016]

DETAILED DESCRIPTION OF THE INVENTION FIG.
3 shows an example of a cooling device.

In the horizontal fluidized bed drying / cooling apparatus 1, the fluidizing section 4 and the free board section 5 in which the particles to be dried are fluidized are maintained while keeping the particles movable in the horizontal direction.
3 or more rooms, 4 rooms in this example (5a, 5b, 5c, 5d)
Partition. The plenum chamber 2 below the dispersion plate 3 also has three or more chambers in accordance with the partitioning position of the fluidizing section, and in this example, four chambers (2
a, 2b, 2c, 2d). The plenum 2 into which the hot air is blown is completely partitioned so that there is no gas mixing between the chambers.
The partition plate 6 was installed so that the free board part 5 above the coal fluidization part 4 was also almost completely partitioned. Here, gas having a higher temperature than normal temperature is referred to as “hot air”. Further, the fluidized bed and the fluidized bed are collectively referred to as “fluidized bed”.

What is important here is to provide an "intermediate cooling zone" before and after the main chamber to use air as a cooling gas in the drying chamber where the hot coal is cooled in two or more chambers. is there.

The heating and drying are performed in the two upstream chambers, and the downstream two chambers are heated and dried.
In a drying room, for example, 30
When a drying gas of 0 ° C. is supplied, the temperature of the exhaust gas discharged to the upper part is 130 ° C., and the temperature of the coal entering the cooling chamber from the drying chamber is 90 ° C. Therefore, a low-temperature gas is supplied to the cooling chamber to lower the coal temperature to, for example, 40 ° C., which does not cause the problem that the residual moisture evaporates from the dried product during transportation to the coke oven and generates dust. , And want to discharge it from the apparatus 1.

In order to lower the coal temperature to 40 ° C., it was considered advantageous to use air, which is the cheapest drying medium, in the final main cooling chamber (5d).
The choice of the gas to be supplied to the intermediate cooling chamber (5c) adjacent to (a, 5b) is an important issue. When the coal is dried in the drying chamber under the above-mentioned conditions, the temperature of the coal is raised to about 90 ° C on average. Temperature of gas supplied from 30
It is assumed that some particles rise to near 0 ° C. There is a risk of ignition if the hot particles come into contact with air, and direct contact with air must be avoided. Therefore, a room adjacent to the drying room is provided with an intermediate cooling room. It is necessary to supply a low-temperature and low-oxygen gas to this chamber, and a method of mixing air and gas discharged from the freeboard section above the fluidized bed is effective as a process and cost. is there. It is also effective to mix air and exhaust gas from other combustion equipment such as a coke oven supplied to the drying chamber. The allowable oxygen amount in the low oxygen concentration gas varies depending on the temperature and moisture of the coal moving from the drying chamber to the intermediate cooling chamber.
The oxygen concentration should be as follows, but is usually less than 18%. In the illustrated example, the upper exhaust gas of the drying chambers (5a, 5b) is mixed with air via the circulation pipe 7 so as to be supplied gas for the intermediate cooling chamber (5c).

The intermediate cooling chamber (5c) is provided with a drying chamber (5a, 5a).
5b) and the cooling chamber (5d), it is necessary to keep the atmosphere with a low oxygen concentration to prevent the oxidation of the coal supplied from the drying chamber, and when the coal moves to the final cooling chamber, air and This is very important because it needs to be cooled to a temperature where it does not ignite on contact.

The raw coal conveyed from the yard is 20 mm
When the above coarse particles are not included and there is no possibility of generating abnormally high-temperature coal, an operation of directly supplying air to the intermediate cooling chamber is also possible. In such a case, a water sprinkler and / or at least an upper part of the free board part of the intermediate cooling room should be prepared in case of fire.
Alternatively, it is necessary to provide an inert gas supply device. It is also effective to install a water sprinkling device and / or an inert gas supply device in a free board section of another room in case of emergency. As the inert gas, a nitrogen gas having an oxygen content of 1% or less or pressurized steam may be used.

It is very important in fluidized bed operation to properly maintain the fluidization of coal, but coal is likely to form quasi-particles or agglomerates in a wet state. Therefore, it is effective to directly supply the gas to the fluidizing part and / or the free board part in order to prevent the fluidized bed and / or the free board from adhering to the side wall of the fluidized bed or to the surface of the dispersion plate and stagnating. . This gas is preferably low in moisture and low in oxygen, but it is satisfactory if it has a gas property to be blown into the lower plenum chamber, for example, the same property as temperature, oxygen concentration and the like. Also, if a sprinkler and / or an inert gas supply is installed at the top of the freeboard for fire prevention or fire extinguishing, there is a possibility that coal particles may adhere to the nozzle. It is also effective to blow low oxygen gas into the vicinity of the nozzle in accordance with the nozzle position.
In this case, the pulse may be blown instead of the continuous blow.

[0024]

EXAMPLE A horizontal fluidized-bed drying / cooling apparatus shown in FIG. 1 was used as a drying apparatus for coal charged in a coke oven, since there was no heat source such as high-temperature steam or a high-temperature heating medium in the periphery. The amount of coal treated is 250t at 9% of attached moisture.
/ H, with the goal of drying to 6%, but the distance from the horizontal fluidized bed drying / cooling device to the coke oven is long, and the generation of dust due to water evaporation due to the sensible heat of the coal itself during transportation is suppressed. In order to do so, the coal temperature at the outlet of the fluidized bed was reduced to around 40 ° C. A device capable of mixing exhaust gas from a nearby coke oven stack with hot air generated by burning new fuel gas as hot air,
A dry gas at 00 ° C. was supplied to the plenum chamber of the fluidized bed to dry the coal moving on the dispersion plate. The fluidized bed is
The plenum chamber and the freeboard section are divided into four chambers in the direction of the movement of the coal particles, and the drying and cooling gas supplied to the plenum chamber are not mixed before passing through the dispersion plate, and the freeboard section also has a space. The structure is such that gas mixing does not occur.

In the two chambers near the coal input section, which is a drying chamber, 3
About 80,000 m ³ / h of gas at 00 ° C. was introduced. As a result, the temperature of the exhaust gas discharged to the upper part was 130 ° C., and the temperature of the coal entering the third intermediate cooling chamber from the drying chamber was 90 ° C. If the exhaust gas from the upper part of the drying chamber is discharged out of the system as a gas at 130 ° C., the energy loss is large. Therefore, this exhaust gas was mixed with the combustion exhaust gas of a coke oven and used for fluidization and drying gas. At this time, the intermediate cooling chamber (third chamber) and the cooling chamber (4
If the exhaust gas from the chamber (2) is also mixed, the temperature of the hot air becomes too low, so that these exhaust gases are discharged. When the upper exhaust gas from the drying chamber is directly circulated and mixed with the fluidized bed supply gas, there is a concern that fine dust contained in the gas may accumulate in the plenum chamber or adhere to the gas blowing holes of the dispersion plate. After discharging from the upper part, the solid-gas separator 9 is passed.

In the test operation, the water content of the coal fluctuates, and while the coal is stored in the yard, the water content becomes 8
% In some cases. In this case, since there is a restriction in reducing the supply gas amount from the viewpoint of securing the gas flow rate necessary for fluidization, an attempt was made to adjust the heat amount given to the fluidized bed by the supply gas temperature. In this case, it is effective to mix exhaust gas from the intermediate cooling chamber and the cooling chamber.
It was confirmed by a test that a method was also provided in which the gas 11 was merged after removing the contained dust, and about 20% of the gas 11 was used as a supply gas to the fluidized bed.

In order to reduce the coal temperature to 40 ° C., air was used for the cooling chamber. The upper exhaust gas from the drying chamber was mixed with air and supplied to the third intermediate cooling chamber.

The oxygen concentration of the gas supplied to the intermediate cooling chamber is 13
%, And the temperature was controlled at 60 ° C. By keeping the coal in the intermediate cooling chamber for about one minute, the temperature of the coal particles moving from the third chamber to the fourth chamber is reduced to 70 ° C., and at the same time, abnormally high-temperature coal particles exceeding 100 ° C. which existed about 3%. Was also able to be lowered. The coal was flowed into the cooling chamber and brought into contact with air, but the coal temperature was successfully controlled to the target of 40 ° C. and moisture of 6% without any trouble such as ignition. In this case, the moisture of the coal leaving the drying chamber and moving to the intermediate cooling chamber should be dried to about 7%, and the reduction of 1% to the target moisture can be achieved by adding a new heat source in the intermediate cooling chamber and the cooling chamber. It was confirmed that the drying degree could be increased by the exhaust gas and the air in the upper part of the fluidized bed without using. The dried coal discharged from the cooling chamber could be transported to the coke oven in a dusting state of a few hundred meters negligible.

This time, in order to supply air to the intercooling chamber and the cooling chamber, air blowers (12, 13) are installed separately from the gas blower to be supplied to the drying chamber. Was supplied after mixing. In order to control the supply gas temperature of the intermediate cooling chamber, a device that measures the temperature of the gas supplied to the plenum chamber of the intermediate cooling chamber, calculates and controls the amount of the exhaust gas circulating from the drying chamber and the amount of mixing with the air Was provided. Specifically, a solid-gas separator is provided in the upper exhaust gas duct of the drying chamber, a chimney is provided downstream of the drying chamber, a branch duct is provided between the solid-gas separator and the chimney, and a circulating gas amount adjustment device is installed here Then, a pipe for mixing this circulating gas into a supply gas pipe to the drying chamber and a pipe for mixing into the intermediate cooling chamber were provided, and a gas amount adjusting valve was also installed in the pipe to mix into the intermediate cooling chamber. The intermediate cooling chamber was provided with a function of controlling the supply gas amount to be substantially constant, and adjusting the exhaust gas and the air amount in the upper part of the drying chamber by oxygen concentration, temperature and / or moisture in the inside.

Further, in order to prevent coal particles from adhering to the side wall of the fluidized bed, etc., a gas at 300 ° C. is blown into the plenum chamber at a temperature of 300 ° C. below the intermediate position between the fluidizing section and the freeboard section of the drying chamber. % Equivalent. That is, height 6
0.8m above the dispersion plate in the freeboard section
Nozzles were provided on the side plate at a position of 0.5 m on the left and right sides to prevent stagnation on the wall surface. In the case of a dried material having a high moisture content, it is desirable to blow the fluidized material from a position close to the floor surface.
In the case of coal with a moisture content of 13%, it was confirmed that blowing from about 0.2 m above the dispersion plate was effective. As described above, since the fluidizing agent sometimes adheres to the upper part of the wall plate while being fluidized, it was considered that the blowing device and the gas amount should be determined based on the device characteristics and the properties of the material to be dried.

[0031]

According to the present invention, a material to be dried having a high moisture content, such as coal, is dried by heating in a horizontal fluidized bed, and then, while preventing oxidation of the coal, the fluidized bed is heated to a temperature at which it does not ignite even if it comes into contact with air. Then, it can be cooled with air to a temperature at which the effect of evaporating the residual moisture during the transport process can be neglected, and dust generation during transport to the coke oven can be prevented at low cost.

[Brief description of the drawings]

FIG. 1 is a view showing a horizontal fluidized bed drying / cooling apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Horizontal fluidized-bed drying / cooling apparatus 2 Plenum chamber 3 Dispersion plate 4 Fluidization part 5 Free board part 6 Partition plate 7 Circulation piping 8 Side piping 9 Solid-gas separator 10 Solid-gas separator 11 Gas 12,13 Air blower

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3L113 AA07 AB04 AC01 AC21 AC45 AC46 AC48 AC52 AC60 AC61 AC67 AC73 AC74 BA02 DA06 DA26 4H012 RA05

Claims (6)

[Claims] 1. A horizontal flow in which a gas is blown from a lower plenum chamber through a dispersion plate into an upper fluidizing section to fluidize particles supplied on the dispersion plate, and then moved in a lateral direction to be dried with hot air and then cooled. In the layer drying / cooling method, the plenum chamber and the freeboard section are partitioned into three or more chambers in the moving direction of the particles to be dried, and an intermediate cooling chamber is provided between the first drying chamber and the last cooling chamber, After the hot air is supplied in the drying chamber to dry the particles to be dried, a low oxygen concentration gas of 18% or less oxygen is supplied in the intermediate cooling chamber to perform intermediate cooling while suppressing the oxidation of the particles, and then the air is cooled in the cooling chamber. A horizontal fluidized bed drying / cooling method characterized by supplying a gas mainly comprising: 2. The horizontal fluidized bed drying / cooling method according to claim 1, wherein the low oxygen concentration gas includes a gas once discharged from a fluidized bed freeboard section. 3. The horizontal fluidized bed drying / drying method according to claim 1, wherein a gas for drying or cooling is directly supplied to the fluidizing section and / or the free board section without using a dispersion plate.
Cooling method. 4. A gas is blown from the lower plenum chamber to the upper fluidizing section and the freeboard section via the dispersion plate to fluidize the particles to be dried supplied on the dispersion plate and move the particles in the lateral direction. In a horizontal fluidized bed drying / cooling device that cools after hot air drying, the plenum chamber and freeboard section are divided into three or more chambers in the particle movement direction, and intermediate cooling is performed between the first drying chamber and the last cooling chamber. A horizontal fluidized bed drying / cooling apparatus, comprising: a gas pipe for supplying at least a gas to a plenum chamber corresponding to an intermediate cooling chamber; 5. A horizontal fluidized bed dryer according to claim 4, wherein a side pipe for directly supplying a drying or cooling gas is provided in the fluidizing section and / or the free board section without using a dispersion plate. ·Cooling system. 6. The horizontal fluidized-bed drying / cooling device according to claim 4, wherein a water sprinkling device and / or an inert gas supply device are provided at least in a free board portion of the intermediate cooling chamber.