JP2023009639A - Producing method of asphalt mixture - Google Patents

Abstract

To provide the producing method of an asphalt mixture instantaneously corresponding to shipping of an ordinary mixture and a medium temperature mixture, with a relatively simple constitution and while suppressing a setting space.SOLUTION: A room temperature sand storage bin 20 storing unheated room temperature sand is provided in a plant body 3, and an operation panel 4 calculates an adjusting heat quantity occupied by the sand by reducing a fixed heat quantity occupied by materials other than the sand from a total heat quantity required to produce a medium temperature mixture for one batch, and calculates a mixing ratio of the heated sand to the room temperature sand so that the heat quantity matches the adjusting heat quantity. When producing the medium temperature mixture, while materials other than sand are charged into a mixer 19 according to a blending ratio, the heated sand and the room temperature sand are charged into the mixer 19 on the basis of the mixing ratio. Moisture in the room temperature sand is evaporated while mixing each material, and the evaporation heat at that time is used to adjust the temperature to the desired shipping temperature.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an asphalt mixture that is a road paving material, and more particularly to a method for producing a warmed mixture.

In the asphalt plant, the aggregate, which is the material of the asphalt mixture, is dried by heating to about 160 ° C. in a dryer, then supplied to the vibrating sieve on the upper part of the adjacent plant body, sieved by the vibrating sieve, and the lower aggregate storage bin. A predetermined amount of aggregate of the desired particle size is discharged from the aggregate storage bin into a weighing tank so that the mixture is suitable for the type of asphalt mixture to be shipped, and weighed. It is put into the mixer at the bottom of the plant body together with the molten asphalt and stone powder, etc., and mixed and adjusted to produce the desired asphalt mixture.

By the way, in recent years, from the viewpoint of energy saving, reduction of CO2 emissions, etc., a medium-temperature mixture in which the heating temperature of the aggregate is kept lower than the temperature of a normal asphalt mixture by, for example, about 30 ° C. (about 130 ° C.) There is an increasing opportunity to produce asphalt mixtures called

In response to this, the present applicant also has a storage method for storing an asphalt mixture of about 160 ° C. produced in the asphalt plant near the main body of the asphalt plant, as shown in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-132131). A silo is separately provided, and a weighing tank and a mixer are provided below the storage silo in the same manner as the plant main body, while a surge bin for storing room temperature cold aggregate is further provided on the side of the storage silo. We have proposed a method and apparatus for producing an asphalt mixture.

In the above manufacturing method and manufacturing apparatus, cold aggregate having a desired particle size is stored in the surge bin according to the composition of the asphalt mixture to be shipped, and the asphalt mixture and the cold aggregate are transferred from the storage silo and surge bin. are charged and mixed in the mixer at a predetermined ratio, it is possible to adjust (lower) the temperature of the asphalt mixture to be shipped to a desired temperature (for example, about 130° C.).

Thus, according to the manufacturing method and manufacturing apparatus described above, even when heated aggregates of about 160° C. are stored in the aggregate storage bins of the plant body in order to manufacture ordinary asphalt mixtures, The warmed mixture at about 130° C. can be shipped immediately without extraction.

Japanese Patent Application Laid-Open No. 2006-132131

However, in the above-described asphalt mixture manufacturing method and manufacturing apparatus, a storage silo for the asphalt mixture is arranged separately from the plant main body, and a weighing tank and a mixer are installed below it like the plant main body. It is assumed that, in some cases, it is difficult to install because it requires a relatively large installation space and, in addition, it requires a relatively large installation space.

In view of the above points, it is an object of the present invention to provide a method for producing an asphalt mixture that has a relatively simple configuration and that allows immediate shipment of a normal mixture or a medium temperature mixture while suppressing the installation space. and

In order to solve the above problems, the method for producing an asphalt mixture according to claim 1 of the present invention comprises a dryer for heat-drying aggregates, and a plant body having screening, storage, weighing and mixing functions. An asphalt mixture for producing an asphalt mixture by adding heated aggregates of various particle sizes heated and dried to a predetermined temperature by the dryer into the mixer of the plant body at a predetermined ratio, and mixing while adding stone powder and molten asphalt. In the production method of 1, the plant body is provided with a room temperature sand storage bin for storing unheated room temperature sand, and from the shipping temperature of the asphalt mixture to be produced, the specific heat, and the mixing capacity for one batch of the mixer, 1 The total amount of heat required to produce the asphalt mixture for a batch is obtained, and the storage temperature of various heated aggregates other than sand, stone powder, and molten asphalt stored in the plant body, the specific heat of each material, and one batch The fixed heat quantity occupied by materials other than sand in the total heat quantity is obtained from the amount of each material in the asphalt mixture, and the adjusted heat quantity occupied by sand is obtained by subtracting the fixed heat quantity from the total heat quantity. , the storage temperature of the heated sand stored in the plant main body, the storage temperature and water content of the normal temperature sand stored in the normal temperature sand storage bin, the specific heat of the sand, and the amount of sand in the asphalt mixture for one batch. Therefore, the mixing ratio of the heated sand and the room-temperature sand is determined so that the heat quantity matches the adjusted heat quantity, and when the asphalt mixture is produced, the materials other than the sand are put into the mixer according to the composition. The sand is produced by putting heated sand and normal temperature sand into the mixer based on the mixing ratio, evaporating the moisture contained in the normal temperature sand while mixing in the mixer, and utilizing the heat of vaporization at that time. to condition the asphalt mixture to the desired shipping temperature.

The method for producing an asphalt mixture according to claim 2 is characterized in that the normal temperature sand to be stored in the normal temperature sand storage bin is preliminarily subjected to water treatment to adjust the water content ratio to a predetermined value.

According to the method for producing an asphalt mixture according to claim 1 of the present invention, the plant body is provided with a normal temperature sand storage bin for storing unheated normal temperature sand, and one batch of asphalt mixture having a desired shipping temperature is manufactured. Determine the total amount of heat required for the sand, determine the amount of fixed heat occupied by materials other than sand in the total amount of heat, subtract the amount of fixed heat from the total amount of heat to obtain the amount of adjustment heat occupied by sand, and obtain the amount of heat corresponding to the amount of adjustment heat. The mixing ratio of heated sand and normal temperature sand is determined as described above, and when producing the asphalt mixture, materials other than sand are put into the mixer according to the mixing ratio, and sand is mixed with heated sand based on the mixing ratio. Normal temperature sand is put into the mixer, and the water contained in the normal temperature sand is evaporated while being mixed in the mixer, and the heat of vaporization at that time is used to adjust the asphalt mixture to a desired shipping temperature. As a result of being able to effectively adjust the temperature of the asphalt mixture, it can be handled by simply installing a room temperature sand storage bin in the existing plant. Shipments of warmed mixtures can be immediately accommodated.

In addition, according to the method for producing an asphalt mixture according to claim 2, since the room-temperature sand stored in the room-temperature sand storage bin is previously treated with water to adjust the water content to a predetermined level, even if the amount of sand mixed is small. Even in such a case, it is possible to more effectively utilize the heat of vaporization and flexibly respond to shipment of the warmed mixture.

1 is a schematic illustration of a method for producing an asphalt mixture according to the present invention; FIG.

In the method for producing an asphalt mixture according to the present invention, a dryer that heats and dries aggregate and a plant body that has sieving, storage, weighing, and mixing functions are provided, and the dryer heats and dries the asphalt mixture to a predetermined temperature. A desired asphalt mixture can be produced by charging heated aggregates of various particle sizes into the mixer of the plant main body at a predetermined ratio and mixing while adding separately weighed stone powder and molten asphalt.

The plant body is provided with a molten asphalt storage tank, a stone powder storage silo, and an aggregate storage bin for storing heated aggregate by particle size, which has been heat-dried in the dryer, as in a normal plant. A normal temperature sand storage bin is provided for storing unheated normal temperature sand (a state containing a certain amount of moisture) that has not undergone heat treatment with a dryer.

Each storage bin (tank, silo) is equipped with a temperature sensor for detecting the storage temperature of each material such as aggregate, molten asphalt, and stone powder during storage. In addition to the sensor, a water content sensor is provided to detect the water content (water content ratio) contained in the cold sand during storage.

Also, an operation panel for operating and controlling the plant is provided near the main body of the plant, so that detected values from the temperature sensors and moisture sensors can be sequentially taken in. Further, in the operation panel, the specific heat of the asphalt mixture, the aggregate, stone powder, and molten asphalt that are the raw materials of the asphalt mixture, and the mixing capacity for one batch of the mixer are set and registered in advance.

Then, when the asphalt plant produces a medium temperature mixture whose shipping temperature is lower than that of the normal mixture, the operation panel pre-registers the shipping temperature (for example, 130 ° C.) of the asphalt mixture and the pre-registered specific heat and the mixing capacity of the mixer for one batch, the total amount of heat required to produce the warmed mixture for one batch is calculated.

Next, various heated aggregates other than sand (aggregate with a particle size of 2.5 mm or less) detected by each temperature sensor (for example, No. 5 crushed stone: aggregate with a particle size of 20 to 13 mm, No. 6 crushed stone : aggregate equivalent to 13 to 5 mm particle size, No. 7 crushed stone: aggregate equivalent to 5 to 2.5 mm particle size), stone powder, molten asphalt, each storage temperature, the specific heat of each material registered in advance, and 1 batch The amount of fixed heat occupied by materials other than sand in the total amount of heat is calculated from the compounded amount of each material in the medium temperature mixture, and the fixed amount of heat is subtracted from the total amount of heat to Calculate the adjustment heat quantity occupied by

Next, in the same manner as described above, the storage temperature of the heated sand stored in the aggregate storage bin of the plant body, the storage temperature of the normal temperature sand stored in the normal temperature sand storage bin, and the water content detected by the temperature sensors The heat of vaporization when the water evaporates is calculated from the water content ratio of the normal temperature sand detected by the sensor, the specific heat of the sand (aggregate) registered in advance, and the blending amount of sand in the medium temperature mixture for one batch. After taking into consideration, the mixing ratio of the heated sand and the normal temperature sand is calculated so that the amount of heat matches the adjustment amount of heat.

That is, by mixing hot sand in a dry state at a high temperature with warm sand at a low temperature and containing water at a predetermined ratio, the total amount of heat possessed by the sand after mixing is equal to the adjusted heat amount obtained in advance. The mixing ratio of both is obtained in advance so that it is approximately the same as.

After the above arithmetic processing, when actually producing the medium temperature mixture, materials other than sand are weighed according to the composition and put into the mixer, while sand is based on the mixing ratio obtained in advance. A predetermined amount of heated sand and normal temperature sand are put into the mixer by using the Then, while the materials are mixed in the mixer, the water contained in the normal temperature sand is evaporated, and the heat of vaporization at that time is used to lower the temperature of the asphalt mixture to the desired shipping temperature (about 130 ° C.). adjust (reduce) to

Preferably, the room-temperature sand storage bin is provided with watering (spraying) means, and the room-temperature sand stored in the room-temperature sand storage bin is appropriately watered (sprayed) so that the water content ratio can be adjusted to a predetermined value. should be As a result, even if the water content ratio in normal-temperature sand is originally low, or even if a medium-temperature mixture with a small amount of sand is produced, the heat of vaporization of water can be effectively used, and the desired amount can be obtained with a margin. can be adjusted (lowered) to the shipping temperature of

As described above, in the method for producing an asphalt mixture of the present invention, various aggregates other than sand, molten asphalt, etc. are kept at the temperature (about 160° C.) at the time of producing the mixture and placed in the mixer according to the composition. On the other hand, as for the sand, prepare heated sand (approximately 160°C) that has been heated and dried with a dryer, and room-temperature sand (for example, approximately 15°C) that has not been subjected to heat-drying and contains some moisture. In the case of producing the medium temperature mixture, the mixing ratio of the heated sand and the normal temperature sand is appropriately adjusted, and the sand is put into the mixer and mixed to adjust (lower) the desired shipping temperature. It is possible.

At this time, by focusing on sand, which contains a little more water than other aggregates, and effectively utilizing the heat of vaporization when the water contained in the sand evaporates, the shipping temperature of the mixture (approximately 160°C) is reduced. It is possible to effectively adjust (lower) the shipping temperature (approximately 130 ° C) of the warmed mixture from the temperature of the existing asphalt plant. It is possible to provide an easy-to-use plant that has a simple configuration and can respond immediately to shipping requests for either a normal mixture or a medium temperature mixture while reducing the installation space.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, 1 is an asphalt plant for producing an asphalt mixture according to the present invention, a dryer 2 with a rotary kiln structure that heats and dries aggregates of various particle sizes, and heats aggregates that have undergone heat drying treatment in the dryer 2. It mainly consists of a plant main body 3 for sieving, storage, weighing, and mixing, and an operation panel 4 for operating and controlling various devices and devices in the plant.

On the upstream side of the dryer 2, a plurality of aggregate hoppers 5 for storing aggregate, which is the material of the asphalt mixture, are provided for each particle size. While the material is fed into the cylindrical drum body 7 of the dryer 2 via a belt conveyor 6, a burner 8 provided at one end of the drum body 7 is located downstream of the dryer 2. A vertical conveying device 10 is provided for supplying heated aggregates heated and dried to a predetermined temperature (for example, about 160° C.) by contact with hot air supplied from the plant to the vibrating sieve 9 on the upper part of the plant body 3 .

The plant body 3 includes the vibrating sieve 9 for sieving the heated aggregate, aggregate storage bins 11 for storing the heated aggregate sieved by the vibrating sieve 9 by particle size, and the aggregate storage bin 11 for storing the aggregate. An aggregate weighing tank 12 for cumulatively weighing heated aggregates of various particle sizes, an asphalt tank 13 for storing molten asphalt, an asphalt weighing tank 15 for weighing molten asphalt supplied from the asphalt tank 13 by a supply pump 14, It is equipped with a stone powder silo 16 for storing stone powder, a stone powder measuring tank 18 for measuring the stone powder supplied from the stone powder silo 16 through a screw feeder 17, and a mixer 19 for stirring and mixing the above materials.

Further, at the side of the aggregate storage bin 11, a room temperature sand storage bin 20 is provided for storing unheated (with a certain amount of moisture) room temperature sand that has not been heated and dried by the dryer 2. there is 21 in the figure is an aggregate hopper for normal temperature sand that temporarily stores the normal temperature sand. The sand storage bin 20 can be supplied. The aggregate hopper 21 does not necessarily need to be provided separately, and the hopper for storing sand in the aggregate hopper 5 may also be used.

The aggregate storage bin 11 is provided with a plurality of compartments 11a to 11d for storing the heated aggregate sieved by the vibrating sieve 9 by particle size. Aggregate input side) Sand (heated sand) is stored in the lower compartment 11a, and crushed stone No. 7, crushed stone No. 6, and crushed stone No. 5 are stored in the compartments 11b to 11d located downstream thereof, respectively. and

Temperature sensors 24a to 24d for detecting the storage temperature of the stored heated aggregates are provided in the compartments 11a to 11d of the aggregate storage bin 11, respectively. In addition to a temperature sensor 25 for detecting the storage temperature of the unheated normal temperature sand, a moisture sensor 26 for detecting the water content ratio of the normal temperature sand is provided.

The asphalt tank 13 and the stone dust silo 16 are similarly provided with temperature sensors 27 and 28 for detecting the storage temperatures of the stored molten asphalt and stone dust, respectively. Since the room-temperature sand and stone powder are both stored at room temperature, they can be set appropriately according to, for example, the outside temperature of the day. .

The operation panel 4 can sequentially take in detected values from the temperature sensors 24a to 24d, 25, 27, 28 and the moisture sensor 26 via signal lines (not shown) or the like. Further, in the operation panel 4, the specific heat of the asphalt mixture, various aggregates, stone powder, and molten asphalt that are the materials of the asphalt mixture, and the mixing capacity for one batch of the mixer 19 are preset and registered. In addition, the well-known heat of vaporization per unit weight of water at 100.degree.

When an asphalt mixture is produced in the asphalt plant 1 configured as described above, aggregates of various particle sizes cut out from the aggregate hoppers 5 are heated and dried at about 160° C. in the dryer 2, and then The aggregate is supplied to the vibrating screen 9 on the upper part of the plant body 3, sieved by the vibrating screen 9, and stored in compartments 11a to 11d in aggregate storage bins 11 below according to particle size. Further, the room temperature sand cut out from the aggregate hopper 21 for storing room temperature sand is supplied to the room temperature sand storage bin 20 of the plant body 3 and stored in an unheated state (containing a certain amount of moisture).

In the case of producing a normal mixture with a shipping temperature of about 160° C., a predetermined amount of each of the compartments 11a to 11d of the aggregate storage bin 11 is fed into the lower aggregate weighing tank 12 in accordance with the composition as before. The heated aggregates that have been dispensed, cumulatively weighed, and weighed are further put into the lower mixer 19, and a predetermined amount of molten asphalt and stone powder weighed in the asphalt weighing tank 15 and the stone powder weighing tank 18 are added to the mixer 19. The mixer 19 stirs and mixes the charged materials to produce and ship a normal mixture of a desired composition at about 160°C.

On the other hand, when producing a warmed mixture whose shipping temperature is lower than the normal mixture, for example, about 130 ° C., the operation panel 4 preliminarily mixes the warmed mixture to be produced, the shipping temperature, Based on the preset registered specific heat and the mixing capacity of the mixer 19 for one batch, the total amount of heat required to produce one batch of the medium temperature mixture is calculated and obtained.

Next, various heated aggregates other than sand detected by the temperature sensors 24b to 24d, 27, and 28 provided in the compartments 11b to 11d of the aggregate storage bin 11, the asphalt tank 13, and the stone powder silo 16, Based on the respective storage temperatures of molten asphalt and stone powder, the specific heat of each material set and registered in advance, and the blending amount of each material in the medium temperature mixture for one batch, materials other than sand account for the total heat amount. While the fixed heat quantity is calculated and obtained, the fixed heat quantity is subtracted from the total heat quantity, and the adjustment heat quantity occupied by the sand in the total heat quantity is calculated and obtained.

Next, the respective storage temperatures of the heated sand and the normal temperature sand detected by the temperature sensors 24a and 25 provided in the heated sand storage compartment 11a of the aggregate storage bin 11 and the normal temperature sand storage bin 20; Based on the water content ratio of the normal temperature sand detected by the moisture sensor 26, the specific heat of the sand (aggregate) set and registered in advance, and the blending amount of sand in the medium temperature mixture for one batch, the normal temperature sand The mixing ratio of the heated sand and the room-temperature sand is calculated and obtained so that the amount of heat corresponding to the amount of heat to be adjusted is taken into consideration the heat of vaporization when the contained water evaporates.

After the above arithmetic processing, when actually producing the medium temperature mixture, the materials other than sand are weighed according to the composition and put into the mixer 19, while the sand is mixed at the previously obtained mixing ratio. Based on , a predetermined amount of heated sand and normal temperature sand are weighed and charged into the mixer 19, and the mixer 19 stirs and mixes the charged materials.

At this time, in the mixer 19, while the materials are being mixed, the water contained in the room-temperature sand is evaporated, and the heat of vaporization at that time is used to change the temperature of the asphalt mixture to the desired medium-temperature mixture. Adjust (lower) to the shipping temperature (approximately 130°C) before shipping.

Further, preferably, an appropriate watering device (water adding means) is provided in the upper part of the normal temperature sand storage bin 20, and the normal temperature sand stored in the normal temperature sand storage bin 20 is watered (watered) by the watering device. The water content may be adjusted (increased) to a predetermined value by treatment. As a result, even if the water content ratio in normal-temperature sand is originally low, or even in the case of producing a medium-temperature mixture with a small amount of sand, the heat of vaporization of water can be effectively used, and the desired amount can be obtained with a margin. can be adjusted (lowered) to the shipping temperature of

At this time, if the watering (adding water) process is performed while referring to the detected value of the moisture sensor 26, unnecessary excessive watering of the room temperature sand (moisture remaining in the asphalt mixture at the time of shipment) can be prevented. It is possible to prevent such troubles), which is more preferable.

In a test conducted by the present inventor, the operation panel 4 has specific heat of each material, such as asphalt mixture: 0.21 kcal/kg ° C., various aggregates (No. 5 to 7 crushed stone, sand) and Stone powder: 0.20 kcal/kg°C, molten asphalt: 0.45 kcal/kg°C, respectively. Also, the mixing capacity for one batch of the mixer 19 was set at 1,000 kg, and the heat of vaporization of water at 100° C. was set at 539 kcal/kg.

Then, under the above settings, for example, 1,000 kg of a mixture warmed to 130 ° C. with a desired composition (No. 5 to 7 crushed stone (total): 252 kg, stone powder: 45 kg, molten asphalt: 85 kg, sand: 618 kg) is produced. In this case, the total amount of heat required was about 27,300 kcal (130°C x 1,000 kg x 0.21 kcal/kg°C), of which the amount of fixed heat occupied by materials other than sand was about 14,300 kcal. Therefore, from the difference between them, the adjusted heat quantity occupied by sand was about 13,000 kcal.

Then, after considering the heat of vaporization when the water contained in the normal temperature sand evaporates, the heated sand of about 160 ° C. and the water content ratio of 0% and the heated sand of about 10 ° C. (on the day) When calculating the mixing ratio of normal temperature sand with a moisture content of about 10%, the mixing ratio of heated sand: normal temperature sand = 0.83:0.17 was obtained. Then, 515 kg (618 kg x 0.83) of hot sand and 105 kg (618 kg x 0.17) of normal temperature sand were charged into the mixer 19 according to the mixing ratio of the sand, and the materials other than sand were mixed according to the composition. As a result of mixing, a medium-temperature mixture having a target shipping temperature of about 130° C. was obtained.

The present invention is applicable not only to the production of asphalt mixtures using new aggregates, but also to the production of asphalt mixtures using asphalt pavement waste excavated by road construction etc. as part of the raw material. can do.

DESCRIPTION OF SYMBOLS 1... Asphalt plant 2... Dryer 3... Plant main body 4... Operation panel 5... Aggregate hopper 11... Aggregate storage bin 11a... Compartment for storing heated sand 12... Aggregate weighing tank 13... Asphalt tank 15... Asphalt weighing tank DESCRIPTION OF SYMBOLS 16... Stone powder silo 18... Stone powder weighing tank 19... Mixer 20... Normal temperature sand storage bin 21... Aggregate hopper (for normal temperature sand)
24a to 24d, 25, 27, 28... Temperature sensor 26... Moisture sensor

Claims (2)

Equipped with a dryer that heats and dries aggregates, and a plant body that has functions of sieving, storage, weighing, and mixing. In a method for producing an asphalt mixture, in which the asphalt mixture is produced by adding stone powder and molten asphalt at a predetermined ratio and mixing while adding, the plant body is provided with a room temperature sand storage bin for storing unheated room temperature sand, From the shipping temperature, specific heat, and mixing capacity of the mixer for one batch of the asphalt mixture to be produced, the total amount of heat required to produce one batch of the asphalt mixture is obtained, and the amount of heat other than the sand stored in the plant main body is calculated. From the storage temperature of various heated aggregates, stone powder, molten asphalt, the specific heat of each material, and the amount of each material in the asphalt mixture for one batch, materials other than sand among the total heat amount The fixed heat quantity occupied by is obtained, the fixed heat quantity is subtracted from the total heat quantity to obtain the adjusted heat quantity occupied by the sand, the storage temperature of the heated sand stored in the plant main body, and the temperature of the normal temperature sand stored in the normal temperature sand storage bin From the storage temperature and water content ratio, the specific heat of sand, and the blending amount of sand in the asphalt mixture for one batch, the mixing ratio of the heated sand and the normal temperature sand is determined so that the heat amount corresponds to the adjustment heat amount. When the asphalt mixture is produced, materials other than sand are put into the mixer according to the composition, while hot sand and normal temperature sand are put into the mixer based on the mixing ratio, and the mixer is mixed. A method for producing an asphalt mixture, characterized by evaporating the moisture contained in the cold sand during mixing inside and adjusting the asphalt mixture to a desired shipping temperature by utilizing the heat of vaporization at that time. 2. The method for producing an asphalt mixture according to claim 1, wherein the normal temperature sand to be stored in the normal temperature sand storage bin is previously treated with water to adjust the water content to a predetermined water content.

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