JPH0521373Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a chilled concrete mixing device for producing chilled concrete using liquid nitrogen.

[Conventional technology]

As a measure to suppress temperature cracking in mass concrete structures, the so-called pre-cooling method, which lowers the mixing temperature of concrete, is effective.
There are several methods for this pre-cooling, but
It has been proposed to use liquid nitrogen as a cooling medium.

For example, JP-A-62-74603 and JP-A-63-
Publication No. 4169 discloses an invention for pre-cooling concrete using liquid nitrogen.

[The problem that the idea attempts to solve]

For example, when supplying liquid nitrogen to concrete during mixing, as described in JP-A No. 63-4169, how can the sensible heat and latent heat of liquid nitrogen, which easily vaporizes, be used to mix material without wasting it? An important issue is how to communicate effectively. The present invention aims to solve this problem.

[Means to solve problems]

The present invention provides a cooling concrete mixing apparatus that includes a concrete mixer that brings liquid nitrogen into contact with the materials being mixed, and a water tank that stores mixing water to be supplied to the mixer. The present invention provides a cooling concrete kneading apparatus characterized in that a duct is installed to lead gas to the water tank, and the cooling concrete mixing apparatus supplies liquid nitrogen to the concrete being mixed and cools the material, and then the nitrogen gas is supplied to the concrete during mixing. By bringing it into contact with the kneading water from the next batch onwards, the cooling capacity of liquid nitrogen is fully utilized. Here, as a preferred embodiment when introducing the nitrogen gas generated in the mixer into the water tank, as shown in the example below, a gas discharge pipe having a discharge port below the water surface of the water stored in the water tank is used. A diff user is connected to the duct and diffuses nitrogen gas in multiple directions at the outlet of this gas discharge pipe, and the nitrogen gas bubbles discharged from the diff user below the water surface rise in the water. Finally, a configuration is adopted in which a water cooling support plate is installed inside the tank to guide these in the horizontal direction. In addition, as another embodiment, a gas discharge pipe having a discharge port in a space slightly above the water surface of the water stored in the water tank is connected to the duct, and the gas discharge pipe is connected to the tank above the discharge port of the gas discharge pipe. A perforated plate is stretched horizontally across the space, and water is supplied into the tank from above the perforated plate.

Embodiments of the present invention shown in the drawings will be described below.

〔Example〕

FIG. 1 shows an example of producing cooled concrete using liquid nitrogen in a normal batchyard plant. The illustrated batcher plant has a well-known structure in which a cement bin 2, a fine aggregate bin 3, and a coarse aggregate bin 4 are installed on the top of a mixer 1, and lightweight bins 5, 6, 7 for each material. Although this is a type kneading device, a pipe line 8 for supplying liquid nitrogen is connected to the mixer 1. Mixer 1 is chute 10, 11, 12
Once the materials have been added, it becomes a closed space. Nitrogen gas generated in this closed space is led through an exhaust duct 13 to a water tank 9 that stores kneading water. An exhaust fan 14 is interposed in the exhaust duct 13, and forced exhaust is forced from the mixer 1 to the water tank 9.

The mixer 1 is directly supplied from the liquid nitrogen source 15 by adjusting the flow rate adjustment valve 16 installed in the liquid nitrogen supply pipe 8, and the liquid nitrogen is supplied directly from the liquid nitrogen source 15 to ensure good contact with the material being stirred. To achieve this, a nozzle or inlet for discharging liquid nitrogen is placed near the surface of the material being stirred, or placed in the drum wall in contact with the material being stirred. In any case, the injection port is installed at a position away from the stirring shaft, thereby preventing mortar etc. from freezing on the stirring shaft. All of the liquid nitrogen supplied to the mixer 1 is vaporized in the mixer 1 and becomes nitrogen gas, but it is important to transfer the cold heat of this nitrogen gas to the materials being kneaded due to the structure and function of the mixer 1. There is a limit. In the present invention, this cold nitrogen gas is forcibly exhausted from the mixer 1, which is a closed space, through the duct 13 by driving the exhaust fan 14, and is led to the water tank 9 for kneading to be used for the next batch. Used for cooling water. An apparatus shown in FIG. 2 or 3 is used as an apparatus for simply and efficiently bringing the kneading water into contact with nitrogen gas.

In the device shown in FIG. 2, a water supply pipe 18 leading to a water source and a drain pipe 19 leading to the mixer 1 are attached to a water tank 9 consisting of a closed container, and a gas discharge pipe 20 is immersed below the surface of the water stored in this water tank 9. And this discharge pipe 2
A diff user 21 is attached to the discharge port below the water surface. The gas discharge pipe 20 is connected to the exhaust duct 13 from the mixer 1. Deaf user 2
1 is one in which discharge ports are arranged so that the discharged gas is diffused in all directions below the water surface. Further, a water cooling support plate 22 is attached so that gas bubbles discharged from the differential user 21 slowly rise in the water. In the illustrated example, the water cooling assisting plate 22 has a bottom surface that is gently sloped laterally from the lowest central part, and the differential user 21 is located in the central part. That is, the gas discharge pipe 20 is passed through the center of the water cooling support plate 22 from above to the bottom, and the differential user 21 is inserted into the discharge pipe 20 passing through the water cooling support plate 22.
It is located close to the bottom of 2. As a result, the gas bubbles discharged from the differential user 21 in the circumferential direction pass down the inclined lower surface of the water cooling aid plate 22 and slowly rise in the circumferential direction.
It emerges above the water surface through a gap provided between 2 and the inner wall of the aquarium. The gas released above the water surface is discharged to the outside of the system through the exhaust port 23. Even with this simple configuration, the nitrogen gas discharged from the mixer 1 and having a cooling capacity can undergo sufficient heat exchange with the kneading water.

FIG. 3 shows a water supply pipe 18 leading to a water source in a water tank 9 consisting of a closed container, and a drain pipe 19 leading to a mixer 1.
Attach it above the water tank 9 (water surface level 2).
A perforated plate 24 is arranged horizontally above the perforated plate 25, and water in a water tank is sprinkled above this perforated plate 25 by a circulation pump 26, and water droplets in the process of falling to the water surface 25 through this perforated plate 25. A gas discharge pipe 20 is provided so as to be in gas-liquid contact with. In the illustrated example, the discharge port 27 of the gas discharge pipe 20 is provided on the side wall of the water tank at a position slightly above the water surface 25 and sufficiently lower than the perforated plate 24. Further, a water spray nozzle 28 is used to efficiently spray water above the perforated plate 25 by the circulation pump 26. With this configuration, a water circulation path is formed in which a part of the circulating water stays on the perforated plate 25 and water droplets fall toward the water surface below, and the water on the perforated plate 25 and the falling water droplets are formed. On the other hand, the nitrogen gas discharged from the discharge port 27 comes into good gas-liquid contact, and although the configuration is simple, the cold heat of the nitrogen gas discharged from the mixer 1 is well transferred to the water.

In this way, according to the present invention, liquid nitrogen is introduced into the mixer during material kneading to directly cool the material during kneading, and the low-temperature nitrogen gas generated at that time is used to cool the kneading water for the next and subsequent batches. can be used efficiently and with a simple device configuration,
Overall, the cooling capacity of liquid nitrogen can be fully utilized. Therefore, pre-cooling of concrete to prevent temperature cracking can be easily and economically achieved.

[Brief explanation of drawings]

Fig. 1 is an equipment layout system diagram of the device of the present invention, Fig. 2 is a schematic cross-sectional view of the kneading water cooling device according to the present invention, and Fig. 3 is a schematic cross-sectional view showing another example of the kneading water cooling device according to the present invention. It is a diagram. 1...Mixer, 8...Liquid nitrogen supply pipe line,
9...Kneading water tank, 13...Exhaust duct, 14
... Exhaust fan, 18 ... Water supply pipe, 19 ... Drain pipe, 20 ... Gas discharge pipe, 21 ... Diff user, 22 ... Water cooling support plate, 23 ... Exhaust port, 2
4... Porous plate, 26... Circulation pump, 27... Gas discharge port.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A cooling concrete mixing device comprising a concrete mixer that brings liquid nitrogen into contact with the materials being mixed, and a water tank that stores mixing water to be supplied to the mixer, A duct is installed to guide the nitrogen gas generated in the mixer to the water tank, and a gas discharge pipe having a discharge port below the water surface of the water stored in the water tank is connected to the duct, and the discharge of this gas discharge pipe is A diff user is installed at the outlet to diffuse nitrogen gas in multiple directions, and a water cooling support plate is installed to guide the nitrogen gas bubbles discharged below the water surface from the diff user horizontally as they rise through the water. A cooling concrete mixing device characterized in that a cooling concrete mixing device is installed in a tank. (2) In a cooling concrete mixing device that includes a concrete mixer that brings liquid nitrogen into contact with the materials being mixed and a water tank that stores mixing water to be supplied to the mixer, the nitrogen gas generated in the mixer A duct leading to the water tank is installed, and a gas discharge pipe having a discharge port slightly above the water level of the water stored in the water tank is connected to the duct, and a gas discharge pipe above the discharge port of the gas discharge pipe is installed. A cooling concrete kneading device characterized in that a perforated plate is horizontally stretched in a tank space, and water is supplied into the tank from above the perforated plate. (3) The cooling concrete kneading apparatus according to claim 2, wherein water is supplied into the tank by a water supply pipe leading to a water source and a water spray nozzle that circulates and sprinkles water in the tank.