JPS6371311A - Manufacture of low-temperature concrete, etc. - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for producing low-temperature concrete, etc., which can produce excellent low-temperature concrete and low-temperature mortar in an efficiently cooled state.

(b) Prior art The present applicant has developed a method for producing low-temperature concrete, etc., in which low-temperature concrete, etc., is obtained by cooling concrete or mortar as a final product in the mixer by supplying cryogenic liquid nitrogen into the mixer. A separate proposal was made regarding the manufacturing method.

According to this method, the liquid nitrogen supplied into the mixer evaporates and lowers the surrounding temperature, and at the same time, the extremely low temperature nitrogen gas created by the evaporation of liquid nitrogen absorbs heat from the air inside the container. As the temperature of the atmosphere inside the container is lowered, the concrete etc. are rapidly cooled. In other words, concrete etc. have the properties of liquid nitrogen, which has a low boiling point (-496°C) and a high latent heat of vaporization (48 Kcal/Kg), and a high specific heat (0,248 Kcal 17 Kg"C).
Due to the properties of nitrogen gas, it will be rapidly cooled. Therefore, there are advantages such as being able to arbitrarily set the temperature of concrete, etc. within a wide range.

(c) Disadvantages that the invention is trying to solve However, when using the above method, much of the extremely low temperature nitrogen gas produced by evaporation of liquid nitrogen is atomized into the atmosphere from inside the mixer and discharged. There are disadvantages such as a decrease in thermal efficiency and an uneconomical increase in the amount of liquid nitrogen that must be used when cooling concrete or the like to a desired temperature.

In view of the above-mentioned problems, the present invention provides a method for producing low-temperature concrete, etc., which makes it possible to efficiently cool concrete, etc. to be produced, that is, to suitably cool down to a desired temperature range using a small amount of liquid nitrogen. This is what I am trying to do.

(d) Means for Solving the Problems The means adopted by the present invention are as follows, and will be explained by referring to the reference numerals in the figures in the embodiments: Each storage bin 3 and 6 stores each material separately. - When supplying materials such as concrete from 7 to the mixers 13 and 13 to produce concrete, etc., the material A such as concrete in the mixers 13 and 13 is supplied by supplying liquid nitrogen to the mixers 13 and 13.
Alternatively, while cooling the kneaded material of material A, mixer 13
- The cryogenic nitrogen gas vaporized in the storage bin 13 is discharged into any of the storage bins 3, 6, and 7, and is reused for cooling the material in the storage bin.

(e) Material A such as concrete or the kneaded material of material A in the working mixers 13 is cooled by cryogenic liquid nitrogen and cryogenic nitrogen gas.

The nitrogen gas in the mixers 13 and 13 cools the material in any of the storage bins 3, 6, 7, etc., without being atomized to the outside air and exhausted at a low temperature, and then atomized to the outside air. I will do it.

The cooled material is later fed into mixers 13, 13,
It is cooled again with liquid nitrogen and nitrogen gas as described above. In this case, since the material has already been cooled, the amount of liquid nitrogen required to cool the concrete etc. to the desired temperature range is reduced by 6'.

(f) Example Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway front view of the forced two-shaft mixer. The mixer 13a has two stirring devices 31 arranged in parallel therein, and is composed of a kneading tank section 32 and a cover section 33. 34 is a cement supply chute disposed at the center of the top surface of the cover portion 33, and 35 and 36 are a gravel supply chute and a sand supply chute disposed on each side of the cement supply chute 34. Which shoot 34
- Both 35 and 36 penetrate the top surface of the cover part 33, and each tip extends above the stirring devices 31 and 31 in the mixer 13a.

37 is a main pipe for supplying water, a water stop valve 38 is interposed in the middle, and a branch pipe 39 is branched from the upstream side of the water stop valve 38. This branch pipe 39 branches into two on the downstream side of a water stop valve 39a interposed in the middle, and each tip communicates with water injection nozzles 40 and 40 arranged below the top surface of the cover part 33. ing. The water injection nozzles 40 are directed downward, and are formed to atomize water into a mist or raindrop shape and spray the water so as to enlarge its surface.

41 is liquid nitrogen (pressure around 9 kg/ci)
It is a main pipe for water to pass through, and it branches into two on the downstream side of the valve 42, and each tip has a respective water injection nozzle 40.
・Each nitrogen injection nozzle 43, 43 arranged near 40
It communicates with This injection direction intersects with the injection direction of the water injection nozzle 40, and the water further atomized by liquid nitrogen is spread as uniformly as possible within the kneading tank section 32.

Using the above-mentioned apparatus, it is carried out as follows.

First, the mixer 13 is
Material A such as concrete is stored in a. In this case, there is no problem in answering whether the material A for concrete or the like is only aggregate such as gravel and/or sand, or if it is aggregate with cement, water, and additives added. However, when mixing water with material A such as concrete, it is important to set the amount of water to be less than the planned mixing amount.

Next, the water is atomized in the mixer 13a and the liquid nitrogen is vaporized. For this purpose, the water stop valve 39a is opened to inject water from the water injection nozzles 40, and the valve 42 is opened and cryogenic liquid nitrogen is injected from the nitrogen injection nozzles 43.

Then, the liquid nitrogen will vigorously interact with the water in the form of mist or raindrops.This will promote the atomization of the water and expose it to an atmosphere with an extremely low temperature. As a result, the water has an increased surface area and is surrounded by an atmosphere with a significant temperature difference.Therefore, rapid heat exchange takes place within this atmosphere, and the water is cooled to an extremely low temperature in a short period of time. Partly becomes ice-like.

When the above action is performed above material A such as concrete, cryogenic water and/or thin ice falls onto material A such as concrete that has been stirred by the stirring devices 31 in advance, or It falls onto the material A, such as concrete, which is being stirred by the stirring devices 31, 31, and is uniformly mixed or permeated into the material A, such as concrete.

Therefore, the material A such as concrete is simply mixed with the mixer 13a.
Not only is it cooled by contact with the nitrogen gas in the tank, but it is also strongly kneaded by the stirring devices 31 and 31 to produce extremely low-temperature liquid nitrogen, micronized low-temperature water, and/or fine ice. It is also cooled from within.

Figure 2 shows a schematic diagram of a batcher plant that embodies the above embodiment, and 1 shows each material such as concrete excluding water and admixtures, that is, fine aggregate (sand), coarse aggregate (gravel), and cement. A material storage section for storing each material separately.In the center, there is a cement storage bin 3 for storing cement conveyed from the screw conveyor 2, and on each side of this, there is a cement storage bin 3 for storing cement conveyed from the screw conveyor 2. A fine aggregate storage bin 6 and a coarse aggregate storage bin 7 are provided for separately storing the fine aggregate and coarse aggregate that are transported through the turn head 5. Each storage bin 3, 6, and 7 Below are a cement weighing hopper 10, a fine aggregate weighing hopper 9, and a coarse aggregate weighing hopper 11.
The materials from these hoppers 9, 10, and 11 are received by a collecting hopper 12 and can be supplied to tiltable mixers 13 and 13 of gravity kneading type arranged on each side of the lower part. be. Reference numeral 14 denotes a water tank, and a water measuring hopper 15 is provided below the water tank, so that measured water can be supplied into the mixers 13. 16 is a hopper for supplying concrete etc. to the mixer truck, 17 is a weighing display panel,
18 is an admixture measuring hopper.

Furthermore, 19 is a cylinder (pressure 9k) of the liquid nitrogen storage section 20.
g/Ci) and each mixer 13.13
Two closing valves 19a-193 are interposed in the middle of the nitrogen supply pipe for communicating with the nitrogen supply pipe. In each figure, a duct 21 with a considerably large cross section is erected from the top of the mixers 13, 13 in order to guide the nitrogen gas vaporized in the mixers 13, 13 into the coarse aggregate storage bin 7. The mixers 13, 13 and the coarse aggregate storage bin 7 can be communicated with each other.

Reference numeral 22 denotes a switching damper for selectively communicating the mixers 13 and 13 with the coarse aggregate storage bin 7.

Note that, if necessary, the mixers 13, 13, duct 21, coarse aggregate storage bin 7, etc. are covered with a heat insulating material.

Using the above device, the present invention is implemented as follows. Each material such as concrete is taken out from each storage bin 3, 6, 7 and water tank 14, etc., and placed in each weighing hopper 9, 10, 11.
After measuring the amount using a method such as the above, it is supplied into either one of the mixers 13. Next, while the mixer 13 is operating or stopped, the closing valve 19a is opened to supply cryogenic liquid nitrogen into the mixer 13. The supplied liquid nitrogen is passed through the mixer 13 in a liquid state or in a vaporized state as described above.
The material A inside is cooled by its low heat and latent heat of vaporization, and the concrete, etc. to be manufactured is made into a cooled state.

Then, by appropriately adjusting the supply amount of liquid nitrogen, the concrete to be manufactured, that is, concrete or mortar, is cooled to a desired temperature range.

On the other hand, the low-temperature nitrogen gas produced by vaporizing the liquid nitrogen in the mixer 13 passes through the appropriately switched damper 22 and reaches the coarse aggregate storage bin 7 to cool the coarse aggregate. Since the cooled coarse aggregate is later supplied again to the mixer 13 and made into a part of concrete, etc.,
The low heat of the coarse aggregate cools the material A, such as concrete, and reduces the amount of liquid nitrogen required to cool the concrete, etc. to be manufactured to a desired temperature range. Then, the more the mixer 13 is operated continuously (the more the coarse aggregate is cooled by the nitrogen gas, the more the coarse aggregate is cooled by the nitrogen gas, the more the concrete etc. per unit amount of concrete etc. The amount of liquid nitrogen required will decrease.

In addition, in the above-mentioned example, only the coarse aggregate was cooled by the nitrogen gas vaporized in the mixer 13, but it may be possible to cool some of the fine aggregate (and an appropriate configuration may be adopted). This makes it possible to cool even cement, water, etc.

Furthermore, the liquid nitrogen used in this example is not an absolute medium, and other media may be used within the scope of the technology of the present invention.

Further, in order to improve water jetting, it is preferable to provide a pressurizing device for increasing water pressure in the middle of the water piping.

Furthermore, in order to effectively guide the cryogenic nitrogen gas deep into the material in the storage bin, it is preferable to provide a blower in the middle of the duct 21 to forcefully blow the air.

(G) Effects of the Invention According to the present invention as described above, the low heat of the nitrogen gas that was not effectively utilized due to exhaustion can be replaced by the nitrogen gas produced by vaporizing liquid nitrogen in the mixer 13. Low heat in at least one of storage bins 3, 6, 7...
Since the material in the mixer 13 is cooled, concrete, etc. in a cooled state can be produced more efficiently than when the material A, such as concrete, is simply cooled in the mixer 13 with liquid nitrogen. Therefore, the amount of liquid nitrogen to be used to cool the material A, such as concrete, is reduced, and there is an advantage that low-temperature concrete, etc., which has been cooled to a desired temperature range, can be produced economically.

Also, instead of cooling the finished concrete, etc. with liquid nitrogen, material A, such as concrete, during the manufacturing process is cooled with liquid nitrogen, so the finished concrete, etc. will be partially frozen. This has the advantage of being able to avoid this at will.

[Brief explanation of the drawing]

FIG. 1 is a front view of a forced two-shaft mixer for implementing the present invention, and FIG. 2 is a schematic diagram showing an example of a batcher plant. (Symbol) A: Materials such as concrete in the mixer 3.6.7.
...Storage bin 13, 13a...Mixer

Claims (1)

[Claims] When supplying materials such as concrete to a mixer from each storage bin that stores each material separately to produce concrete, etc., by supplying liquid nitrogen into the mixer, the material such as concrete or this material is supplied inside the mixer. A low-temperature concrete characterized in that the kneaded material is cooled, and the extremely low temperature nitrogen gas produced by vaporization in the mixer is guided to any of the storage bins and reused for cooling the materials in the storage bins. etc. manufacturing method.