JP5128885B2 - Asphalt heating apparatus and method and paving material manufacturing equipment - Google Patents

Description

  The present invention relates to an asphalt heating apparatus and method, and a paving material manufacturing facility.

  Generally, an asphalt mixture obtained by mixing asphalt and aggregate is used as a pavement material for roads and the like. Here, for example, when asphalt exceeds 160 ° C., the deterioration occurs and the viscosity increases, so that workability at the time of laying deteriorates. On the other hand, if the asphalt mixture is heated in a temperature range in which the asphalt does not deteriorate, the core of the aggregate cannot be heated, so that a temperature drop (for example, 140 ° C. or less) is likely to occur. As a result, the asphalt mixture has a disadvantage that the viscosity becomes high and workability at the time of laying deteriorates.

In order to solve the above problem, a heating / drying method using a microwave has been proposed (for example, see Patent Document 1). Specifically, the asphalt mixture conveyed by the belt conveyor is heated by irradiating microwaves. Here, microwaves have higher thermal efficiency than normal external heat heating, and control of heating power is easy. Moreover, since it is excellent also in responsiveness, it has the characteristics that temperature control is comparatively easy.
Japanese Patent Laid-Open No. 2-183002

  However, in the above technique, asphalt is liable to be oxidized, and as a result, the viscosity of the asphalt mixture becomes high, so that there is a problem that workability at the time of laying deteriorates. Moreover, in order to heat an asphalt mixture with a microwave, there exists a problem that a long heating time and a lot of electric power are required, and an efficient heating cannot be performed.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an apparatus and method for efficiently heating asphalt while preventing deterioration of the asphalt due to heat and oxidation, and a paving material manufacturing facility. To do.

In order to solve the above problems, the present invention employs the following means.
That is, the present invention comprises a microwave irradiation means for irradiating microwaves and a low oxygen concentration gas supply means for supplying a low oxygen concentration gas, and the low oxygen concentration gas supplied by the low oxygen concentration gas supply means is used. An asphalt heating apparatus that heats asphalt by irradiating microwaves with the microwave irradiation means in an environment having a low oxygen concentration is employed.

  According to the present invention, the microwave is irradiated to the asphalt by the microwave irradiation unit in an environment in which the low oxygen concentration is set by the low oxygen concentration gas supply unit. Thereby, the viscosity of asphalt can be reduced and the workability | operativity at the time of laying asphalt mixture which mixed the said asphalt and aggregate can be improved. In addition, by setting the environment under a low oxygen concentration, it is possible to shorten the heating time of the asphalt by the microwave and reduce the cost required for the temperature increase. For example, an environment having an oxygen concentration of 5% or less is suitable as the environment having a low oxygen concentration.

In the above invention, the low oxygen concentration gas may be nitrogen gas.
By doing in this way, the viscosity of asphalt can be reduced effectively. In addition, since it is desirable to make the oxygen concentration in a heating apparatus into 5% or less with nitrogen gas, it is suitable that the density | concentration of nitrogen gas shall be 95% or more, for example.

  Further, the present invention includes the asphalt heating device described above, a storage tank that stores the asphalt, and a mixer that mixes the asphalt and aggregate stored in the storage tank, and the asphalt heating device includes the storage Pavement material manufacturing equipment provided either in the tank or the mixer or between the storage tank and the mixer is adopted.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to manufacture a pavement material with high workability | operativity at the time of laying by manufacturing a pavement material using the asphalt heated with the asphalt heating apparatus. By installing an asphalt heating device between the storage tank or the storage tank and the mixer, microwaves can be absorbed completely into the asphalt without being absorbed into the aggregate, so that the viscosity of the asphalt can be efficiently increased. It can be reduced.

  The present invention also includes a microwave irradiation step of irradiating microwaves and a low oxygen concentration gas supply step of supplying a low oxygen concentration gas, and the low oxygen concentration gas supplied by the low oxygen concentration gas supply step is used. An asphalt heating method is used in which the asphalt is heated by irradiating microwaves in the microwave irradiation step in an environment having a low oxygen concentration.

  According to the present invention, the microwave is irradiated to the asphalt by the microwave irradiation step in an environment where the low oxygen concentration is set by the low oxygen concentration gas supply step. Thereby, the viscosity of asphalt can be reduced and the workability | operativity at the time of laying asphalt mixture which mixed the said asphalt and aggregate can be improved. In addition, by setting the environment under a low oxygen concentration, it is possible to shorten the time for heating the asphalt by the microwave, and it is possible to reduce the cost required to raise the temperature of the asphalt.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that an asphalt can be heated efficiently, preventing the deterioration by the heat and oxidation of asphalt.

EMBODIMENT OF THE INVENTION Below, one embodiment of the asphalt heating apparatus which concerns on this invention, and a pavement material manufacturing apparatus provided with the same are described with reference to drawings.
As shown in FIG. 1, a pavement material manufacturing facility 100 according to this embodiment includes a pavement material drying device 101 that dries an asphalt reclaimed material that has been peeled off from a paved road, and an asphalt regenerated material that has been dried by the pavement material drying device 101. An asphalt recycled material tank 102 for storing, a softener tank 103 for storing a softener such as a resin, a storage tank 104 for storing straight asphalt, and an aggregate heating furnace 105 for heating virgin aggregate quarried from a mountain The asphalt recycled material supplied from the asphalt recycled material tank 102, the softener supplied from the softener tank 103, the straight asphalt supplied from the storage tank 104, and the virgin aggregate supplied from the aggregate heating furnace 105 are mixed. And a mixer 106.

  The storage tank 104 includes an asphalt heating device 150 that heats the asphalt with microwaves. The asphalt heating apparatus 150 includes a microwave irradiation unit 151 that irradiates microwaves, and a low oxygen concentration gas supply unit 152 that supplies a low oxygen concentration gas, and the low oxygen concentration gas supply unit 152 supplies the low oxygen concentration In an environment where the oxygen concentration is low by the concentration gas, the microwave irradiation unit 151 irradiates the microwave to heat the asphalt. Here, the low oxygen concentration gas supplied by the low oxygen concentration gas supply unit 152 will be described as nitrogen gas.

The manufacturing process of the paving material in the paving material manufacturing facility 100 having the above configuration will be described below.
The asphalt reclaimed material peeled off from the paved road is supplied to the pavement material drying device 101, and is slowly heated by hot air. Here, the temperature of the hot air supplied into the pavement material drying apparatus 101 is, for example, 600 ° C. at the entrance and 172 ° C. at the exit. In addition, the heating time of the asphalt recycled material is, for example, 10 minutes.

The asphalt recycled material heated by the pavement material drying apparatus 101 is supplied to the asphalt recycled material tank 102 and temporarily stored. The asphalt recycled material tank 102 is provided with a heating device such as an electric heater, for example, to keep the internal asphalt recycled material warm. The time for temporarily storing in the storage tank 102 is generally within 10 hours, and the temperature at that time is 160 ° C. to 170 ° C.
The asphalt recycled material temporarily stored in this way is supplied to the mixer 106 according to the required time and required amount of the paving material. The supply amount is generally 50% to 60% of the paving material which is the final product.

Further, in the storage tank 104, the straight asphalt is stored, and microwave irradiation is performed in an environment in which the oxygen concentration is, for example, 5% or less by the nitrogen gas supplied from the low oxygen concentration gas supply unit 152. Microwave is irradiated by the part 151, and the straight asphalt is heated.
The straight asphalt heated in this way is supplied to the mixer 106 according to the required time and required amount of the paving material.

  Further, the virgin aggregate quarried from the mountain is directly heated to 160 to 170 ° C. by the aggregate heating furnace 105 and supplied to the mixer 106 according to the required time and required amount of the pavement. In addition, the softener stored in the softener tank 103 is supplied to the mixer 106. Depending on the plant, a softening agent may be added at the entrance of the pavement material drying apparatus 101.

  The asphalt recycled material, virgin aggregate, straight asphalt, and softener supplied in this manner are mixed by the mixer 106. Then, the mixed product is shipped as a paving material. At this time, the quality of the pavement is determined by the penetration, that is, when the needle defined by JIS K 2530 standard conditions (temperature 25 ° C., load 100 g, penetration time 5 seconds) penetrates the material vertically. For example, when shipping to Tokyo, the mixing ratio and heating conditions of the above-mentioned various raw materials are determined so that the penetration is 40 to 50.

Next, the effects of the asphalt heating apparatus 150 according to the present embodiment and the paving material manufacturing facility 100 including the same will be described below using the test results shown in FIG.
The purpose of the test shown in FIG. 2 is to confirm the effect of microwave heating and the atmosphere during heating on the viscosity of asphalt.

  As a test method, as shown in FIG. 1 to No. Nine samples of 9 were heated by a drier or microwave in air or nitrogen atmosphere, naturally cooled to room temperature, then the temperature was raised again in an oil bath, and the viscosity under a plurality of temperature conditions was measured. . Here, the sample in the first test is new asphalt, the sample in the second test is a mixture of the samples after the first test, and the sample in the third test is the second The sample after the test is mixed.

FIG. 3 shows the results of the first test, where the vertical axis represents the viscosity of the asphalt and the horizontal axis represents the temperature of the asphalt when the viscosity is measured. A rotational viscometer is used to measure the viscosity, and the rotational speed and peripheral speed of the rotor are changed according to the viscosity to be measured.
Here, when the test results of BASE1 and OV_Air are compared, the viscosity of OV_Air is higher under all temperature conditions. This has shown that the viscosity of asphalt rises by heating in air atmosphere with a dryer.

  Moreover, when the test results of OV_Air and MW_Air are compared, the viscosity of MW_Air is lower under all temperature conditions. This is due to the difference in heating method between the dryer and the microwave. In other words, heating with a dryer heats the product while it is in contact with the atmosphere, which causes oxidative degradation and increases the viscosity of asphalt. This is because the rise can be suppressed.

  On the other hand, when the test results of MW_N2_1 and MW_Air are compared, the viscosity of MW_N2_1 is significantly lower particularly at 80 ° C. to 100 ° C. This indicates that the viscosity of asphalt can be reduced by using a nitrogen atmosphere when heating by microwaves.

  The same tendency appears in FIG. 4 showing the second test result and FIG. 5 showing the third test result. In FIG. 4, since there is no significant difference between the test results of MW_N2_170 and MW_N2_190, even if the heating temperature by microwave is changed between 170 ° C. and 190 ° C., the viscosity of asphalt is greatly affected. Not shown.

  FIG. 6 shows a line graph (BASE) connecting the viscosity of BASE1, BASE2, and BASE3 at a temperature condition of 120 ° C., and a line graph (MW_N2) connecting the viscosity of MW_N2_1, MW_N2_170, and MW_N2_4. Is shown. In FIG. 6, the viscosity of BASE2 and BASE3 is higher than that of BASE1 due to repeated heating. On the other hand, the viscosity of MW_N2_170 and MW_N2_4 is lower than the viscosity of MW_N2_1. This indicates that the viscosity of asphalt can be reduced by heating with a microwave in a nitrogen atmosphere even when the heating is repeated.

Next, the relationship between the temperature when each sample is heated to 170 ° C. and the elapsed time will be described with reference to FIGS.
FIG. 7 shows the relationship between the temperature and elapsed time when OV_Air (sample No. 2) is heated in an air atmosphere by a dryer, and a heating time of 200 minutes is required to raise the temperature to 170 ° C. doing.
FIG. 8 shows the relationship between the temperature and the elapsed time when MW_Air (sample No. 3) is heated in the atmosphere by microwave, and the heating time of 63 minutes and 32 seconds is required to raise the temperature to 170 ° C. Is needed.

  9 to 12 show a case where MW_N2_1 (sample No. 4), MW_N2_170 (sample No. 6), MW_N2_190 (sample No. 7), and MW_N2_4 (sample No. 9) are heated in a nitrogen atmosphere by microwaves. Shows temperature and elapsed time. In these tests, the heating time required to raise the temperature to 170 ° C. was 26 minutes 52 seconds, 19 minutes 46 seconds, 23 minutes 19 seconds, and 15 minutes 28 seconds, respectively. That is, the heating time when heated in a nitrogen atmosphere by microwaves is about 1/13 to about 1/8 of the test result when heated in an air atmosphere by the dryer shown in FIG. It is about 1/4 to about 2/5 of the test result when heated in an air atmosphere by the microwave shown. This shows that heating time of asphalt can be significantly shortened by heating in a nitrogen atmosphere by microwaves.

  As described above, according to the asphalt heating apparatus 150 and the pavement material manufacturing facility 100 including the asphalt heating apparatus 150 according to the present embodiment, the asphalt can be used in an environment in which the low oxygen concentration gas supply unit 152 has a low oxygen concentration. Microwaves are irradiated by the microwave irradiation unit 151. Thereby, the viscosity of asphalt can be reduced and the workability | operativity at the time of laying asphalt mixture which mixed the said asphalt and aggregate can be improved. In addition, by setting the environment under a low oxygen concentration, it is possible to shorten the heating time of the asphalt by the microwave and reduce the cost required for the temperature increase. For example, an environment having an oxygen concentration of 5% or less is suitable as the environment having a low oxygen concentration.

  Moreover, the viscosity of asphalt can be effectively reduced by using nitrogen gas as the low oxygen concentration gas. In addition, since it is desirable to make the oxygen concentration in a heating apparatus into 5% or less with nitrogen gas, it is suitable that the density | concentration of nitrogen gas shall be 95% or more, for example.

  In addition, by providing the asphalt heating device 150 in the storage tank 104, the microwave can be absorbed by the asphalt without being absorbed by the aggregate, so that the viscosity of the asphalt can be efficiently reduced.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention. .
For example, in the present embodiment, the asphalt heating device 150 has been described as being provided in the storage tank 104. However, the asphalt heating device 150 may be provided between the mixer 106 or the storage tank 104 and the mixer 106. . Further, the asphalt heating device 150 may be provided between the aggregate drying furnace 105 or the asphalt recycled material tank 102 or between the aggregate drying furnace 105 and the mixer 106. As a result, the viscosity of the asphalt adhered to the asphalt recycled material can also be reduced, and the laying property of the paving material can be further improved.

It is the composition schematic of the paving material manufacturing equipment shown as one embodiment of the present invention. It is a figure explaining the conditions of the test for confirming the effect of the paving material manufacturing equipment shown in FIG. It is a graph which shows the viscosity measurement result of the 1st time in the test shown in FIG. It is a graph which shows the viscosity measurement result of the 2nd time in the test shown in FIG. It is a graph which shows the viscosity measurement result of the 3rd time in the test shown in FIG. It is a graph which shows a viscosity measurement result in the test shown in FIG. It is a graph which shows the relationship between temperature and elapsed time in the test shown in FIG. It is a graph which shows the relationship between temperature and elapsed time in the test shown in FIG. It is a graph which shows the relationship between temperature and elapsed time in the test shown in FIG. It is a graph which shows the relationship between temperature and elapsed time in the test shown in FIG. It is a graph which shows the relationship between temperature and elapsed time in the test shown in FIG. It is a graph which shows the relationship between temperature and elapsed time in the test shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Pavement material manufacturing equipment 101 Pavement material drying apparatus 102 Asphalt recycling material tank 103 Softener tank 104 Storage tank 105 Aggregate heating furnace 106 Mixer 150 Asphalt heating apparatus 151 Microwave irradiation part 152 Low oxygen concentration gas supply part

Claims (4)

Microwave irradiation means for irradiating microwaves;
Low oxygen concentration gas supply means for supplying low oxygen concentration gas,
An asphalt heating apparatus that heats asphalt by irradiating microwaves with the microwave irradiating means in an environment having a low oxygen concentration by the low oxygen concentration gas supplied by the low oxygen concentration gas supplying means.   The asphalt heating apparatus according to claim 1, wherein the low oxygen concentration gas is nitrogen gas. Asphalt heating apparatus according to claim 1 or 2,
A storage tank for storing asphalt;
A mixer for mixing the asphalt and aggregate stored in the storage tank;
Pavement material manufacturing equipment in which the asphalt heating device is provided either in the storage tank, the mixer, or between the storage tank and the mixer. A microwave irradiation process for irradiating microwaves;
A low oxygen concentration gas supply step for supplying a low oxygen concentration gas,
An asphalt heating method of heating asphalt by irradiating microwaves in the microwave irradiation step in an environment having a low oxygen concentration by the low oxygen concentration gas supplied in the low oxygen concentration gas supply step.

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