JP6269099B2 - Cement cooling system and cement cooling method - Google Patents

Description

  The present invention relates to a cement cooling system and a cement cooling method.

  In concrete after placing, the temperature rises due to heat of hydration. As this temperature rise increases, the temperature stress due to the temperature difference between the inside and outside of the concrete also increases, and so-called temperature cracking may occur. These concerns are particularly strong in the construction of mass concrete that tends to increase the internal temperature due to its large thickness, and concrete in the heat, such as pre-cooling for the purpose of reducing the driving temperature and post-cooling for the purpose of reducing the temperature increase after setting. Various temperature control techniques have been proposed. Among these, the following techniques have been proposed as conventional techniques related to precooling.

  That is, there has been proposed a cement cooling device (Patent Document 1) that cools the cement that is being conveyed by cooling the surface of the outer wall of the cylindrical body that contains the screw mechanism for conveying the cement with cooling water. In addition, a temperature adjustment method (Patent Document 2) is also proposed in which concrete mixed material is supplied through a supply pipe whose inner wall surface is maintained at a predetermined low temperature to ensure a required material temperature.

JP 2010-214707 A JP-A-3-173609

  In the prior art, the inside of the transfer space is cooled by cooling the wall surface of the transfer path, and the cement moving in the transfer space is cooled. However, the time during which the cement being transported can exchange heat with the air in the transport space is short, and the heat exchange efficiency for gas is limited, so the cooling method according to the prior art is sufficient to cool the cement. Difficult to do. On the other hand, cooling by watering is not preferable in terms of water content management during concrete production because the cement gets wet before kneading with other materials such as aggregates.

  Therefore, an object of the present invention is to provide a technique that enables efficient cooling of cement and enables effective reduction of concrete kneading temperature.

A cement cooling system that solves the above problems includes a refrigerant circulation mechanism that circulates refrigerant inside the shaft center of a screw feeder that conveys cement stored in a cement storage facility obliquely upward to a storage bin of a concrete manufacturing plant. It is characterized by providing.

  This makes it possible to directly cool the cement, which is the hottest concrete material, through a wide range of contact surfaces such as screw feeder shafts and blades, and reduce the temperature of the cement during a limited transport time. It can be reduced efficiently.

  Moreover, the cement cooling in the path | route which connects between a cement silo and a cement storage bin is attained, and the cement stored in a cement storage bin can be made into a low-temperature state conventionally. Therefore, the cooled cement can be supplied from the storage bin to the measurement bin, and the cooling loss in the concrete manufacturing process can be suppressed as much as possible to increase the cooling efficiency. Accordingly, it is possible to efficiently cool the cement, and it is possible to efficiently reduce the concrete kneading temperature. In addition, it is possible to cool the cement during the conveying process, and it is not necessary to provide a special process for cooling the cement separately, so that the cost and efficiency of installation and operation of the equipment can be improved.

  Further, in the cement cooling system of the present invention, the shaft center has a double pipe structure including an outer pipe and an inner pipe inside the outer pipe, and the refrigerant circulation mechanism is the inner pipe of the double pipe structure. It is also possible to circulate the refrigerant by pumping the refrigerant to either the inner side or between the inner pipe and the outer pipe and recovering the refrigerant from the other.

  According to this, in the screw feeder that performs rotational driving, it is possible to efficiently cool the cement with a configuration that does not have external projections, bends, or the like that hinder the operation.

In the cement cooling method of the present invention, the coolant stored in the cement storage facility is transferred to the storage bin of the concrete manufacturing plant obliquely upward by a predetermined coolant circulation mechanism inside the shaft center of the screw feeder. The cement is cooled by being circulated.

  According to the present invention, it is possible to efficiently cool the cement, and it is possible to efficiently reduce the concrete kneading temperature.

It is a figure which shows the structural example of the batcher plant containing the cement cooling system of this embodiment. It is a figure which shows the structural example of the cement cooling system in this embodiment. It is sectional drawing which shows the structural example of the cement cooling system in this embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a batcher plant 10 including a cement cooling system 1 of the present embodiment. The cement cooling system 1 in the present embodiment is applied to a screw feeder 30 that connects between the cement silo 12 and the cement storage bin 17 in the batcher plant 10, and cools the cement 18 that is conveyed by the screw feeder 30. System.

  The batcher plant 10 using the cement 18 cooled by the above-described cement cooling system 1 uses various aggregates such as the fine aggregate 2 and the coarse aggregate 3 supplied from the aggregate storage place 11 as concrete materials other than the cement 18. It is received via the belt conveyor 6. The accepted aggregate is put into a section corresponding to the aggregate type in the aggregate storage bin 8 by the selector 7 controlled by a predetermined management system. The aggregate storage bin 8 is provided with level meters 24 and 25 for measuring the storage volume of the aggregate. The level meters 24 and 25 detect an event that the storage volume is below a predetermined level and detect a predetermined signal to the management system. As a result, the aggregate is automatically replenished from the aggregate storage place 11. The fine aggregate 2 and the coarse aggregate 3 stored in the aggregate storage bin 8 fall, for example, every predetermined time, and are supplied to the aggregate measurement bin 9 immediately below to measure the weight, and the predetermined amount is fed to the mixer 21. Will be thrown in.

  Further, the cement 18 constituting the concrete material together with the fine aggregate 2 and the coarse aggregate 3 described above is conveyed from the cement silo 12 to the cement storage bin 17 by the screw feeder 30. The cement 18 thus transported is already cooled by the cement cooling system 1 of the present embodiment when stored in the cement storage bin 17. Therefore, the screw feeder 30 is connected to a refrigerant circulation mechanism 40 that supplies the refrigerant 35 to the inner space 32 of the shaft center 31 of the screw feeder.

  The above-described screw feeder 30 includes an axis 31 that is rotationally driven by a predetermined drive mechanism, and blades 33 that are arranged on the axis 31 at predetermined intervals. In the screw feeder 30, the cement 18 of the cement silo 12 is scooped by the blades 33 that rotate with the drive of the shaft 31, and the scooped cement 18 is sequentially transferred by passing between the blades 33 adjacent to each other. Eventually, the cement 18 is transported to the cement storage bin 17.

  The inner space 32 of the shaft center 31 in the screw feeder 30 has a double tube structure in which the inner tube 34 is accommodated, and the refrigerant circulation mechanism 40 circulates the refrigerant 35 using the double tube structure. The axial center 31 regards the inner tube 34 as an outer tube accommodated in the inner space 32 (hereinafter the same). In this case, in the axial center 31 of the screw feeder 30, either the region between the axial center 31 that is the outer tube and the inner tube 34, or the inside of the inner space 32 is fed by the refrigerant 35 from the refrigerant circulation mechanism 40. The other is connected to the refrigerant pressure feed pipe 32 </ b> A, and the other is connected to the refrigerant recovery pipe 32 </ b> B that sends back the refrigerant 35 that has absorbed heat from the cement 18 around each of the shaft center 31 and the blades 33 to the refrigerant circulation mechanism 40. A detailed configuration example of the screw feeder 30 and the refrigerant circulation mechanism 40 will be described later.

  The cooled cement 18 supplied from the cement silo 12 through the screw feeder 30 is stored in the cement storage bin 17. The cement storage bin 17 is also provided with a level meter 19 similar to the aggregate storage bin 8, and when the storage volume of the cement 18 falls below a predetermined level, the level meter operates to transmit a signal from the cement silo 12. The cement 18 is automatically replenished.

  A cement weighing bottle 20 is disposed below the cement storage bin 17, and a predetermined amount of the cooled cement 18 discharged from the cement storage bin 17 is put into the mixer 21. In addition, a predetermined amount of kneading water containing an admixture is fed into the mixer 21 from the kneading water metering bottle 15. The kneading water is supplied from the admixture tank 13, and a predetermined amount of the admixture measured by the admixture measuring bottle 15 is mixed with a predetermined amount of water supplied from the kneading water tank 14.

  Each concrete material such as the fine aggregate 2 and the cooled cement 18 put into the mixer 21 is kneaded by the mixer 21 for a predetermined time to form a green concrete. The ready-mixed concrete obtained by the mixer 21 is discharged to the hopper 22 and loaded into the ready-mixed vehicle 23 through the hopper 22.

  Next, details of the screw feeder 30 and the refrigerant circulation mechanism 40 in the present embodiment will be described. FIG. 2 is a diagram showing a configuration example of the cement cooling system 1 in the present embodiment, and FIG. 3 is a sectional view thereof. As described above, the screw feeder 30 has a double tube structure in which the inner tube 34 is inserted into the inner space 32 of the shaft 31, and the shaft center through which the refrigerant 35 circulates including the inner space 34 a of the inner tube 34. It corresponds to the inner sky 32. In the double pipe structure, the inner pipe 34 is connected with a refrigerant pressure feeding pipe 32A to which the refrigerant 35 is pressure fed from the refrigerant circulation mechanism 40. The refrigerant 35 pumped from the refrigerant pumping pipe 32 </ b> A toward the inner pipe 34 is cooled by the refrigerant circulation mechanism 40, and at least sufficiently cooler than the cement 18 being stored in the cement silo 12. Further, in the inner space 32 of the shaft center, the region 31 a between the shaft center 31 as the outer tube and the inner tube 34 absorbs heat from the cement 18 around the screw feeder 30, that is, the shaft 31 and the blade 33. A refrigerant recovery pipe 32B that returns the refrigerant 35 to the refrigerant circulation mechanism 40 is connected.

  On the other hand, the refrigerant circulation mechanism 40 pumps the refrigerant 35 to the inner space 34a of the inner pipe 34 of the screw feeder 30 via the above-described refrigerant pressure feeding pipe 32A. The refrigerant 35 that has reached the inner pipe 34 from the refrigerant pressure feeding pipe 32A flows through the inner space 34a of the inner pipe 34 to the inner pipe end 34b, and flows from the inner pipe end 34b into the end 32a of the axial inner space 32. . The refrigerant 35 that has flowed into the end portion 32a of the axial inner space 32 flows toward the other end portion 32b through a region 31a between the axial center 31 and the inner tube 34 serving as the outer tube in the inner axial space 32. The refrigerant flows into the refrigerant recovery pipe 32B through the other end 32b. The refrigerant 35 that has flowed into the refrigerant recovery pipe 32B is recovered by the refrigerant circulation mechanism 40, cooled to a predetermined temperature, and sent again to the refrigerant pressure feed pipe 32A.

  Each surface of the shaft 31 through which the refrigerant 35 flows and the surfaces of the blades 33 supported by the shaft 31 are in contact with the cement 18 being conveyed by the screw feeder 30. The cement 18 that has just been scooped by the screw feeder 30 from the cement silo 12 has a relatively high temperature that is not significantly different from the temperature at the time of supply from the cement transporter to the cement silo 12, while the refrigerant 35 that is sufficiently cooler than the cement 18 The flowing shaft 31 and the blades 33 supported by the shaft 31 are maintained at a temperature lower than that of the cement 18 at least. Therefore, the heat of the cement 18 being conveyed by the screw feeder 30 is absorbed by the refrigerant 35 flowing through the inner space 32 through the shaft center 31 and the blades 33 with which the cement 18 comes into contact. Thus, the refrigerant 35 that has absorbed the heat of the cement 18 is recovered by the refrigerant circulation mechanism 40 through the refrigerant recovery pipe 32B.

  As the refrigerant circulation mechanism 40, an appropriate device such as a chiller or a cooling tower may be adopted according to the situation of the site where the batcher plant 10 is placed and the required specifications, but in this embodiment, an example using a chiller is shown. (Hereafter, chiller 40). The chiller 40 has a function of keeping the temperature of the object, that is, the axis 31 of the screw feeder 30 (and the blade 33 supported by the object) at a constant low temperature by managing and circulating the liquid temperature of the refrigerant 35 described above. The chiller 40 includes a heat exchanger 41 that performs heat exchange with the refrigerant 35 recovered from the refrigerant recovery pipe 32B and cools it, a water tank 42 that stores the refrigerant 35 cooled by the heat exchanger 41, and a refrigerant that is stored in the water tank 42. And a pump 43 that pumps 35 to the refrigerant pumping pipe 32A.

  The refrigerant 35 circulated in the axial center space 32 of the screw feeder 30 may appropriately employ water, antifreeze, air, various gases, etc., depending on the required cooling capacity. Further, not only a mechanism that continues to reuse the refrigerant, such as a chiller or a cooling tower, but also, for example, the river water around the batcher plant 10 is used as the refrigerant 35 to flow through the axial center space 32 of the screw feeder 30 only once. Alternatively, a mechanism may be employed in which heat is absorbed from the cement 18 by circulating through the axial center space 32 of the screw feeder 30 only a predetermined number of times, and the water after the heat absorption is discharged into the water source river.

  As described above, the shaft inner space 32 in the screw feeder 30 that is transporting the cement 18 and the refrigerant 35 are circulated in the shaft center inner space 32, and heat absorption from the cement 18 and heat radiation from the heat exchanger 41 are repeated. By cooperating with the chiller 40, it is possible to efficiently absorb heat from the cement 18 and reliably cool it, and to cool the entire concrete material efficiently. Further, the heat absorption from the cement 18 by the refrigerant 35 is due to heat exchange through the surfaces of the shaft center 31 and the blades 33 in the screw feeder 30, so that the cement 18 can be cooled without being directly wetted.

  According to this embodiment, the cement can be efficiently cooled, and the concrete kneading temperature can be effectively reduced.

  In addition, although this invention was concretely demonstrated based on the one embodiment, it is not limited to this, A various change is possible in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 Cement cooling system 2 Fine aggregate 3 Coarse aggregate 6 Belt conveyor 7 Selector 8 Aggregate storage bin 9 Aggregate measurement bin 10 Batcher plant 11 Aggregate storage place 12 Cement silo 13 Admixture tank 14 Mixing water tank 15 Admixture measurement Bin 16 Kneading water metering bin 17 Cement storage bin 18 Cement 19 Level meter 20 Cement metering bin 21 Mixer 22 Hopper 23 Ready-mix vehicle 24, 25 Level meter 30 Screw feeder 31 Axle (outer tube)
32 Inner shaft space 33 Blade 34 Inner tube 32A Refrigerant pressure feed tube 32B Refrigerant recovery tube 35 Refrigerant 40 Refrigerant circulation mechanism (chiller)
41 Heat exchanger 42 Water tank 43 Pump

Claims (3)

A cement cooling system comprising a refrigerant circulation mechanism for circulating a refrigerant inside an axis of a screw feeder for conveying cement stored in a cement storage facility obliquely upward to a storage bin of a concrete manufacturing plant.   The shaft center has a double tube structure including an outer tube and an inner tube inside the outer tube, and the refrigerant circulation mechanism is located inside the inner tube or the inner tube and the outer tube in the double tube structure. 2. The cement cooling system according to claim 1, wherein the refrigerant is pumped to either of the two and the refrigerant is recovered from the other to circulate the refrigerant. The cement is cooled by circulating a refrigerant by a predetermined refrigerant circulation mechanism inside the shaft center of a screw feeder that conveys the cement stored in the cement storage facility obliquely upward to a storage bin of a concrete manufacturing plant. Cement cooling method characterized by the above-mentioned.

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