JPH05170494A - Improved vertical type lime calcination furnace and production of shell quick lime using this furnace - Google Patents

Abstract

PURPOSE:To enable the adjustment of a slaking speed at a stable temp. by adopting a construction hating no in-furnace insertion parts for the raw material charging pipe of the prescribed furnace and adopting a structure, such as double structures, for the rotating sealing part of an ore discharging machine. CONSTITUTION:The vertical type lime calcination furnace having a waste gas passage 7, calcination zone 4, etc., is produced by forming the raw material charging pipe 1 into the construction having no in-furnace insertion parts, forming the rotating sealing part of the ore discharging machine section 5 into the double structures, providing a damper 9 in a chuting section 6 and disposing a piping 10 for cooling having an adjusting mechanism for the quantity of the air to be blown in the ore discharging machine section 5. Shells, such as scallop shells and oyster shells, adjusted to 2 to 60mm grain sizes are charged from the charging pipe 1 and are deposited temporarily in a rack part 3; thereafter, the shells are dropped successively to the calcination zone 4. The shells are then calcined at 1050 to 1250 deg.C to obtain the shell quick lime; thereafter, this quick lime is cooled while the cooling rate is adjusted by blowing air from the piping 10 for cooling of the ore discharging machine section 5, by which the shell quick lime is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical lime calcination furnace having an improved structure suitable for calcination of shells and a method for producing shell quick lime using the same.

[0002]

2. Description of the Related Art A large amount of shells that are generated due to shellfish collection, cleaning of seawater collection systems, etc., have shellfish adhered to some shells, so that a bad odor is generated due to decay of the shellfish. Due to the shortage of landfill sites, there was a problem in direct landfill disposal. In addition, from the viewpoint of effective utilization of resources, shellfish as industrial waste is burned to be used as quick lime or slaked lime obtained by digesting (hydrating) it.

Conventionally, a rotary kiln has been widely used as a device for burning such a shell to obtain quicklime. However, while the rotary kiln has the advantage that a large amount of shells can be continuously processed as they are, on the other hand, the operation is difficult if the amount of shells inserted is not constant, so the rotary kiln can be processed. It is necessary to secure a large number of shells commensurate with the ability. Further, even if the amount of shells generated is almost constant, if the amount is not so large, it is often economically difficult to use a small rotary kiln. Further, since the rotary kiln cooling system is generally of a type in which the calcined product is rapidly cooled, many of the quicklime shells obtained by this method have a high digestion rate (hydration rate).

Further, some vertical lime calcination furnaces conventionally used for calcination of limestone are suitable for small-scale calcination, but it is difficult to smoothly supply the shell as a raw material, and the shell has Poor bulk density in the furnace due to unique shape and size irregularity, difficult to control firing due to low air resistance in the furnace, quick cooling of the fired product makes it difficult to obtain quick lime with slow digestion rate, etc. There was a problem.

[0005] Since quicklime lime uses biological raw materials and has no environmental problems, it is suitable for applications such as fertilizers, soil conditioners, and pH adjusters for rivers. When used for these purposes, if the rate of digestion of quick lime is too fast, it will disturb the ecosystem, and the effects will not last long and there is a risk of fever. Therefore, a method of adjusting the digestion rate of quicklime has been proposed. For example, calcium carbonate derived from aquatic ecosystem is used as a raw material, and after calcining it, crushing quicklime and coating the surface of quicklime with a surfactant in the presence of a surfactant in a single operation. There is known a method of adjusting the digestion rate of quick lime by adjusting (Japanese Patent Laid-Open No. 2-258656). However, in this method, in addition to the need for a step of coating a surfactant, a solution that is dissolved in a solvent that does not cause a digestion (hydration) reaction with a stock solution of surfactant or quicklime is used. It is necessary, and depending on the cost or the type of solvent used, there remain problems in the working environment during manufacturing.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the production of shell quick lime using a vertical lime calcination furnace, and a vertical lime calcination furnace capable of calcination at a stable temperature. An object of the present invention is to provide a method for producing shell quicklime whose digestion rate is adjusted using a baking furnace.

[0007]

Means for Solving the Problems The present inventor has diligently studied a method for producing quicklime shells using a spinning top lime calcination furnace which is a relatively small vertical lime calcination furnace. Calcination of a shell by facilitating the filling of a shell into the furnace, preventing outside air from entering the furnace, and improving the furnace by installing an air inlet for cooling the baked product at a specific position. It was found that the degree of freedom can be adjusted and shell quicklime with controlled digestion rate can be produced.
The present invention has been completed.

That is, according to the present invention, the raw material feeding pipe (1) is provided on the upper portion.
And a waste gas passage (7), and a raw material input in a vertical lime calcination furnace configured by a shelf part (3), a calcination zone (4), a mine discharger part (5) and a shunt part (6). The pipe (1) has a structure without the insertion part (2) in the furnace, the rotary seal part of the mining machine part (5) has a double structure, and the damper is installed at the shunt part (6). In addition, a vertical lime calcination furnace characterized by having a structure in which a cooling pipe (10) having a function of adjusting the amount of blown air is provided in the exhausting machine part (5), and an improved vertical liquor Type lime baking furnace, 2-60
The shell of which the particle size is adjusted to mm is fired in the temperature range of 1050 to 1250 ° C. to make the shell quick lime, and then air is blown from the cooling pipe (10) provided in the mining machine part (5) to adjust the cooling rate. It is a method for producing quicklime shells, which is characterized by cooling while cooling.

[0009] Since a certain amount of shells are generated in a specific area, the shells are transported to a distant place and collected.
There is a cost problem in producing shell quicklime. Therefore, if the amount of shells to be treated is less than the amount of rotary kiln suitable for large-scale treatment, it is necessary to use a baking furnace that has a treatment capacity according to the amount of shells produced in the area where the shells are produced. It is advantageous. As such a calcination furnace, a vertical lime calcination furnace, which has been used for calcination of limestone, has a relatively simple structure and is low in equipment cost, is suitable. There are several types of vertical lime calcination furnaces, from large-scale furnaces such as the Meltz furnace and Beckenbach furnace to relatively small furnaces such as the top-type lime calcination furnace. It is preferable to use a small top type lime calcination furnace (processing capacity: about 25 tons / day).

FIG. 1 is a schematic sectional view of a conventional vertical lime calcination furnace. The outline of the manufacturing process in the case of manufacturing quicklime shell using a vertical lime baking furnace is as follows. Raw material shells are charged into the furnace by the charging pipe 1, temporarily deposited on the shelf 3, and then sequentially dropped on the baking zone 4 and baked. The calcined shell enters the ore mining unit 5 while being cooled by the cooling air taken in from the shout 6 at the lower part of the furnace, and discharged as shell quicklime from the shout 6 to the outside of the vertical lime baking furnace.

FIG. 2 is a schematic cross-sectional view of the improved vertical lime calcination furnace of the present invention. The present invention is characterized by using a vertical lime calcination furnace having an improved structure to calcine shells and cooling them while adjusting the cooling rate. First, in the present invention, the grain size of the shell to be charged into the vertical lime baking furnace (hereinafter, simply referred to as a furnace) is preferably about 2 to 60 mm, and large ones such as scallop, oyster shell and abalone shell are suitable in advance. Use a crusher to adjust the particle size to the above range, preferably 30 to 50 m.
The particle size is adjusted by crushing to a size of about m. By adjusting the particle size of the shells in this way, it is easy to load them into the furnace, and the bulk density of the shells loaded in the furnace is increased, and the air resistance of the deposits in the furnace is increased to control the combustion air. Will be easier. If the size of the shell piece exceeds 60 mm, the bulk density in the furnace becomes small, and the air resistance becomes small, making it difficult to control firing, and if it is less than 2 mm, it tends to scatter.
It is not preferable because the amount of the exhaust gas flowing out of the furnace increases.

A shell whose particle size is adjusted (hereinafter, simply referred to as a shell) is charged from a charging pipe 1 and is temporarily deposited on a shelf 3 in the furnace. In the conventional furnace, since the tip of the charging pipe is inserted into the furnace, a gap is likely to be formed between the shells temporarily accumulated on the shelf 3 and the abraded portion 8 of the ceiling brick, which makes it easy for the combustion air to escape. was there. Therefore, in the vertical lime calcination furnace of the present invention, by removing the portion of the charging pipe inside the furnace, the shells can be loaded up to the ceiling of the shelf 3. This increases the air resistance of the shelf 3,
Combustion air in the furnace is prevented from easily escaping to the exhaust gas passage 7 provided on the outer side of the shelf, so that a stable firing atmosphere can be maintained.

The shells temporarily deposited on the shelf 3 are successively dropped on the baking zone 4 and baked, and then enter the ore discharger 5 while being cooled by the cooling air taken in from the lower part of the furnace, and the shoot 6 is converted into shell quicklime. Is discharged outside the furnace.

The firing of shells is usually performed by setting the temperature of the firing zone 4 to 1,
The temperature is maintained at about 100 ° C. to 1,250 ° C., but the fuel, the amount of combustion air, and the holding time may be appropriately set depending on the desired degree of baking of shell quicklime and the amount of baking per hour. Here, calcination is controlled mainly by controlling the amounts of fuel and combustion air used, but if external air enters the furnace, calcination becomes difficult, and variations in quality such as so-called uneven burning tend to occur. Quality control of quicklime becomes difficult.

The main entry path of outside air in the conventional furnace shown in FIG. 1 is the shunt section 6 and the rotary seal section of the mining machine section 5. In particular, the shunt portion 6 serves as an inlet for the main cooling air of the calcined shellfish quicklime, but it is difficult to control the amount of air to be taken in because it is open to the outside air. The structure was such that air was taken into the furnace. As described above, if there is a large amount of invasion of the outside air from the rotating seal portion of the shunt portion 6 and the mine discharger portion 5, it is difficult to control firing, and it is difficult to obtain the desired quality of shell quick lime. Therefore, it is necessary to prevent the invasion of outside air into the furnace as much as possible in order to control the burning and to stabilize the quality of the quicklime shell.

The vertical lime calcination furnace of the present invention has the following structure as means for preventing such invasion of outside air and taking in cooling air. First, as a means for preventing the invasion of outside air, as shown in FIG. 3, the rotary seal part of the conventional mining machine part 5 has a double seal structure as shown in FIG. Prevents outside air from entering from the rotary seal,
The shoe that is also the main inlet for conventional cooling air
A damper having a structure in which a damper 9 that is driven by an air cylinder as shown in FIG.
Are operated alternately to discharge the quicklime from the shell, and the shoe part 6
It prevents outside air from entering. Further, as a means for taking in cooling air, as shown in FIGS. 6 and 7,
The cooling pipe 10 for taking in cooling air is provided in the mining machine part 5, and the cooling air is sent into the mining machine part 5 while adjusting the cooling air according to the desired digestion rate of the shell, and the shell quicklime is supplied. I try to cool.

The digestion rate (hydration rate) of the shell quick lime can be adjusted by adjusting the cooling rate of the shell quick lime thus baked. The cooling rate may be adjusted according to the desired digestion rate of quicklime. To slow down the digestion rate of shell quicklime, slow the cooling rate (slow cooling),
Further, it is more effective if the firing temperature is set higher. The slow cooling slows the digestion rate of quicklime, and it is thought that the slow cooling slows the digestion rate due to coarsening of crystals.

[0018]

[Examples] Hereinafter, the method for producing shellfish quicklime according to the present invention will be described in detail with reference to Examples. In addition, in the production of shell quick lime, a vertical lime calcination furnace in which a conventional vertical lime calcination furnace was improved into a shape as shown in FIG. 2 was used. That is, while eliminating the insertion portion 2 of the raw shell shell charging pipe 1 into the furnace, the rotary seal part of the mining machine part 5 has a double seal structure, and the shoot part 5 is operated by an air cylinder. The damper 9 is double-attached, and the dampers are alternately operated to take out the quicklime from the shell to prevent the outside air from entering the furnace.
The pipe 10 for cooling the calcined shell quick lime was attached to the mining machine 5.

(Example 1) A scallop shell was crushed to have a particle size of 2 to 60 mm and an average size of about 40 mm was used as a raw material for producing shell quicklime. From this raw material input pipe 1,
The firing zone 4 is charged into the furnace at a supply rate of 510 kg / Hr.
Was fired at a temperature of 1,100 ° C (fuel consumption: 137 l
/ Ton). At this time, the temperature of the firing zone 4 is 1,050 to
The temperature was in the range of 1,150 ° C, and a very stable firing condition could be maintained. The residence time of the raw material in the furnace is about 9 hours from the charging of the raw material to the discharge of the shoot part 6. The degree of calcination (CaO content) of the obtained shellfish quicklime was 90.72.
%Met. Also, the calcined shell quicklime is 125 ° C.
The cooling rate was about / Hr. Next, in accordance with the above conditions, the raw material supply amount of 730 kg / Hr, the firing zone temperature of 1, 2
It was baked at 50 ° C. The residence time of the raw material in the furnace is about 7 hours. The transition of the calcination zone temperature was as stable as the above, and the calcination degree of the obtained shell quick lime was 95.42%. In addition, the calcined shell quicklime is 210 ℃ / H
It was cooled at a cooling rate of about r.

Comparative Example 1 An attempt was made to produce quicklime shells according to the conditions of Example 1 except that the conventional vertical lime calcination furnace having the structure shown in FIG. 1 was used. The temperature of the baking zone 4 is 1,100
Although the temperature was set to 0 ° C. and the amount of fuel and combustion air used was adjusted, the firing was performed, but the temperature of the firing zone 4 rose to only 1,000 ° C., and sufficient firing was not possible. The amount of fuel used at this time was 160 l / ton.

Example 2 Using the same raw material as in Example 1, the digestion time of the shell quick lime obtained by quenching or gradually cooling the calcined shell quick lime was investigated. Table 1 shows the setting conditions and the results. Here, the cooling rate is 2,000 in the case of rapid cooling.
It is 0 ° C./Hr and about 130 ° C./Hr in the case of slow cooling. It can be seen that the total digestion time of the slowly cooled product is twice as long as that of the rapidly cooled product, and the total temperature rise during digestion is low. The total digestion time was measured according to ASTM C110-76a defined by American Society for Standards of Material. The outline of this method is as follows. Using a digestion reactivity test device, put 76 g of quick lime in 380 ml of water having a water temperature of 40 ° C, read the temperature on the thermometer three times in succession until the change is within 0.5 ° C, and read the temperature of these three readings. The first time is the total digestion time, the temperature at this time is regarded as the final reaction temperature, and the initial temperature is subtracted from this final reaction temperature to obtain the total elevated temperature.

INDUSTRIAL APPLICABILITY In a vertical lime calcination furnace, an improvement for increasing the bulk density of filling shells in the furnace, an improvement for preventing outside air from entering, and a cooling system capable of controlling the cooling of the calcination product are provided to obtain a desired calcination degree. The quicklime of shell can be calcined at a stable temperature, and the digestion rate of the quicklime of shell obtained by selecting a cooling method can be made extremely slow. Therefore, it is possible to use a vertical lime calcination furnace, which had been difficult to operate stably in the past, for the production of shell quick lime, and it can be usefully used in fields such as agriculture, where neutralization of quick lime with a slow digestion rate is required, and water neutralization. ..

[Brief description of drawings]

FIG. 1 Schematic cross-sectional view of a conventional vertical lime baking furnace

FIG. 2 Schematic cross-sectional view of the entire improved vertical lime calcination furnace

[Fig. 3] Conventional mining machine rotating seal part

[Fig. 4] Schematic diagram of the improvement of the rotary seal of the mining machine

[Fig. 5] Schematic view of the improved shoe

FIG. 6 Schematic diagram of cooling piping

FIG. 7 is a schematic view of cooling pipes viewed from the shoot side.

[Explanation of symbols]

 1 Raw Material Input Pipe 2 Raw Material Input Pipe Inner Insertion Section 3 Shelf Section 4 Firing Zone 5 Exhaust Machine Section 6 Shut Section 7 Exhaust Gas Passage 8 Ceiling Brick Abrasion Section 9 Damper 10 Cooling Pipe

[Table 1]

Claims (2)

[Claims] 1. A raw material introduction pipe (1) and an exhaust gas passage (7) are provided at an upper part, and a shelf (3), a calcination zone (4), a demineralizer section (5) and a shunt section (6). In the vertical lime calcination furnace composed of the above, the raw material charging pipe (1) has a structure without the furnace insertion part (2), and the rotary seal part of the mining machine part (5) has a double structure. A vertical part is characterized in that a damper is installed in the toe part (6) and a cooling pipe (10) having a function of adjusting the amount of air blown into is provided in the mining machine part (5). Type lime firing furnace. 2. A method for producing shell quick lime in which a shell is fired using a vertical lime firing furnace, wherein a raw material charging pipe (1) has a structure without an insertion portion (2) in the furnace, and a mining machine section (5). The rotating seal part has a double structure, a damper is installed in the shunt part (6), and a cooling pipe (10) having a function of adjusting the amount of air blown into the mining machine part (5). ) Is provided in the vertical lime calcination furnace, the shell having a grain size adjusted to 2 to 60 mm is calcined in the temperature range of 1050 to 1250 ° C. to form shell quick lime, and then the mining machine part (5) A method for producing a quick lime shell, characterized in that air is blown from a cooling pipe (10) provided in the cooling pipe to cool it while adjusting a cooling rate.