Full-graded precooled concrete production device and production method

Abstract

The invention relates to a production device and a production method for fully graded precooled concrete. The device comprises a coarse aggregate tank, a fine aggregate tank, a coarse aggregate cooling device, a fine aggregate cooling device and a concrete mixing plant. The device can reduce the outlet temperature of each graded concrete to an ideal temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy engineering concrete, and in particular relates to a full-graded precooled concrete production device and a production method. Background Art

[0002] Concrete production equipment is an essential facility in the production of pre-cooled concrete. The pre-cooling of concrete is mainly achieved by cooling one or more of the concrete materials in the operation line of the concrete production equipment. In water conservancy projects, large-volume concrete is widely used. For large-volume concrete, temperature stress is a very important load. In order to prevent the occurrence of temperature cracks and ensure the safe operation of water conservancy project buildings, the temperature change of concrete must be controlled. Pre-cooling concrete is a very effective control method. When producing pre-cooled concrete, the concrete production equipment controls the temperature change of concrete within the allowable range by lowering the concrete production temperature (outlet temperature) to reduce the probability of cracks.

[0003] Since the 1970s, foreign precooling concrete production has mainly adopted the comprehensive cooling form of "precooling coarse aggregate + ice mixing". When the ambient temperature is around 20℃, the outlet temperature of the four-grade concrete can be reduced to 7.2℃. Since the Three Gorges Project in the 1990s, China has begun to adopt new technologies for secondary air-cooled aggregates, patented technologies for high-efficiency air coolers, large-scale flake ice making equipment, ice storage and flake ice transportation and weighing equipment. When the ambient temperature is around 20℃, the outlet temperature of the four-grade concrete can be controlled at 7℃. However, as shown in Table 1, the proportion of fine aggregate (sand) in the four-grade concrete and the three-grade concrete is only 25% and 28%, respectively. Even if only the coarse aggregate is precooled, the outlet temperature can be controlled at 7℃. However, the two-grade and the first-grade concrete are different. As shown in Table 1, the proportion of fine aggregate (sand) is about 40%. It is difficult to achieve the requirement of 5℃ to 8℃ for the concrete outlet temperature only by precooling the coarse aggregate and adding ice and cold water. Therefore, improving the concrete production system and adding a device to precool the sand are necessary and essential in the field of precooling concrete, especially for low-grade precooling concrete.

[0004] Table 1: Mix ratios of various graded concretes in a large hydropower station

[0005] water cement coal ash sand Xiaoshi Zhongshi Dashi Extra large stone The proportion of sand in aggregate Four-level matching 90 130 70 552 314 304 471 471 25.30％ Three-level matching 99 143 77 604 296 444 739 27.96％ Secondary distribution 150 251 84 729 663 442 38％ First level matching 160 294 90 530 720 42.4％

[0006] In the prior art, patent application 201510318869.5 discloses a special cooling system for fine aggregate, which includes a chiller, sand pre-cooling equipment, a mechanical vibrating screen and a sedimentation tank. The fine aggregate (sand) is dehydrated after being cooled by cold water and enters the concrete mixing plant to participate in the preparation of concrete. When the ambient temperature is lower than 20°C, the sand temperature can be controlled not to exceed 6°C by using the special cooling system for fine aggregate, and the outlet temperature of the secondary concrete can be reduced to about 7°C. However, when the ambient temperature is higher than 20°C, the temperature of the fine aggregate (sand) is difficult to reduce, resulting in a high outlet temperature of the secondary concrete; in addition, the special cooling system for fine aggregate does not take into account the primary concrete, so its scope of application is also very limited. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems existing in the prior art and provide a full-grade pre-cooled concrete production device, which can reduce the outlet temperature of each grade of concrete to an ideal temperature.

[0008] The fully graded precooled concrete production device of the present invention comprises a coarse aggregate tank, a fine aggregate tank, a coarse aggregate cooling device, a fine aggregate cooling device and a concrete mixing plant;

[0009] The coarse aggregate cooling equipment is composed of a double-layer screen and a first air-cooled aggregate bin connected in sequence, the double-layer screen is connected to the coarse aggregate tank, and the first air-cooled aggregate bin is connected to the concrete mixing plant;

[0010] The fine aggregate cooling equipment is composed of a chiller, a precooling sand tank, a mechanical vibrating screen and a second air-cooled aggregate bin connected in sequence. The precooling sand tank is connected to the fine aggregate tank, and the second air-cooled aggregate bin or the dewatering screen is connected to the concrete mixing plant.

[0011] Furthermore, the above-mentioned pre-cooling sand tank is replaced by a sand washing machine.

[0012] Furthermore, the fine aggregate cooling equipment is replaced by a chiller, a precooling sand tank, a cooling sand tank and a dewatering screen connected in sequence, the precooling sand tank is connected to the fine aggregate tank, and the dewatering screen is connected to the concrete mixing plant.

[0013] Furthermore, the pre-cooling sand tank and / or the cooling sand tank may be replaced by a sand washer.

[0014] Furthermore, when the ambient temperature is lower than 2°C, the chiller is replaced by a hot water unit.

[0015] The present invention also provides a method for producing fully graded precooled concrete, which specifically comprises the following steps:

[0016] (1) Add coarse aggregate into the coarse aggregate tank, add fine aggregate into the fine aggregate tank, and start the chiller;

[0017] (2) The coarse aggregate is transported to the double-layer screen by a belt conveyor for secondary screening, and then transported to the first air-cooled aggregate bin by a belt conveyor for primary air cooling; at the same time, the fine aggregate is transported to the pre-cooling sand tank by a belt conveyor for spraying, leaching or soaking with cold water, and then screened by a mechanical vibrating screen to remove moisture, and finally transported to the second air-cooled aggregate bin by a belt conveyor for primary air cooling;

[0018] (3) The cooled coarse aggregate and the cooled fine aggregate are transported to the concrete mixing plant for production via belt conveyors.

[0019] The present invention also provides another method for producing fully graded precooled concrete, which specifically comprises the following steps:

[0020] (1) Add coarse aggregate into the coarse aggregate tank, add fine aggregate into the fine aggregate tank, and start the chiller;

[0021] (2) The coarse aggregate is transported to the double-layer screen by a belt conveyor for secondary screening, and then transported to the first air-cooled aggregate bin by a belt conveyor for primary air cooling; at the same time, the fine aggregate is transported to the pre-cooling sand tank by a belt conveyor for spraying or soaking with cold water, and then transported to the cold sand tank by a belt conveyor for secondary water cooling, and finally transported to the dehydration screen by a belt conveyor for dehydration;

[0022] (3) The cooled coarse aggregate and the cooled fine aggregate are transported to the concrete mixing plant for production via belt conveyors.

[0023] Furthermore, in step (1), the temperature of the cold water generated by the chiller is in the range of 2°C to 6°C.

[0024] Beneficial effects of the present invention:

[0025] The fully-graded precooled concrete production device provided by the present invention is applicable to the production of four-graded, three-graded, two-graded and one-graded concrete, and comprises a coarse aggregate cooling device and a fine aggregate cooling device. The two separately cooled aggregates can be mixed to control the concrete outlet temperature to be 5°C to 8°C.

[0026] The fully graded precooled concrete production device of the present invention can replace most existing concrete production devices, solve the problem that the coarse aggregate and the fine aggregate have a large temperature difference due to the inability to precool synchronously, thereby seriously affecting the aggregate outlet temperature, and has great significance for the construction of water conservancy and hydropower projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the fully graded precooled concrete production device A described in Example 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of a fully graded precooled concrete production device B according to Example 2 of the present invention;

[0029] In the figure, a coarse aggregate tank 100, a fine aggregate tank 200, a coarse aggregate cooling device 300, a double-layer screen 301, a first air-cooled aggregate bin 302, a fine aggregate cooling device 400, a chiller 401, a pre-cooling sand tank 402, a vibrating screen 403, a second air-cooled aggregate bin 404, a cold sand tank 405, a dewatering screen 406, and a concrete mixing plant 500. DETAILED DESCRIPTION

[0030] The following is a detailed description of the implementation of the present invention in conjunction with the accompanying drawings, but they do not constitute a limitation of the present invention and are only given as examples. At the same time, the advantages of the present invention are made clearer and easier to understand through the description.

[0031] Example 1

[0032] The fully graded precooled concrete production device A comprises a coarse aggregate tank 100, a fine aggregate tank 200, a coarse aggregate cooling device 300, a fine aggregate cooling device 400 and a concrete mixing plant 500. The coarse aggregate cooling device 300 is composed of a double-layer screen 301 and a first air-cooled aggregate bin 302. After the coarse aggregate is added to the coarse aggregate tank 100, it is first transported to the double-layer screen 301 by a belt conveyor for secondary screening, and then transported to the first air-cooled aggregate bin 302 by a belt conveyor for primary air cooling. The fine aggregate cooling device 400 is installed within a radius of no more than 50m around the concrete mixing plant 500. The fine aggregate cooling equipment 400 is composed of a chiller 401, a pre-cooling sand tank 402, a mechanical vibrating screen 403 and a second air-cooled aggregate bin 404. After the fine aggregate is added to the fine aggregate tank 200, the chiller 401 is started, and the fine aggregate is first transported to the pre-cooling sand tank 402 by a belt conveyor for leaching, then dehydrated by the mechanical vibrating screen 403, and finally transported to the second air-cooled aggregate bin 404 by a belt conveyor for a first air cooling.

[0033] The first air-cooled aggregate bin 302 and the second air-cooled aggregate bin 404 are both connected to the concrete mixing plant 500, so the cooled coarse aggregate and fine aggregate can be transported to the concrete mixing plant for production via belt conveyors.

[0034] Concrete is produced according to the proportion of the secondary distribution corresponding to Table 1, wherein the coarse aggregate is treated by the coarse aggregate cooling device 300 to keep the temperature at 6°C after cooling, and the fine aggregate is treated by the fine aggregate cooling device 400. Table 2 lists the outlet temperature of the secondary distribution concrete under different fine aggregate initial temperatures (which can be regarded as ambient temperature) and different cold water temperatures (generated by the chiller 401).

[0035] Table 2: Exit temperature of secondary concrete production

[0036] Initial temperature of fine aggregate Cold water temperature Outlet temperature 20℃ 0℃ 4.63℃ 30℃ 0℃ 5.09℃ 10℃ 2℃ 5.35℃ 20℃ 2℃ 5.72℃ 30℃ 2℃ 6.25℃ 10℃ 4℃ 6.57℃ 20℃ 4℃ 6.96℃ 30℃ 4℃ 7.41℃ 10℃ 6℃ 7.07℃ 20℃ 6℃ 7.32℃ 30℃ 6℃ 7.71℃ 10℃ 8℃ 7.59℃ 20℃ 8℃ 8.38℃ 30℃ 8℃ 8.74℃

[0037] It can be seen from Table 2 that when the initial temperature of fine aggregate is between 10℃ and 30℃, the cold water temperature is controlled between 2℃ and 6℃, and the cooling temperature of coarse aggregate is controlled at the same time, and the secondary concrete with the outlet temperature between 5℃ and 8℃ can be obtained.

[0038] According to the corresponding proportions in Table 1, the fully graded precooled concrete production device A described in this embodiment is used to produce four-graded, three-graded, two-graded and one-graded concrete, wherein the fine aggregate is kept at a temperature of 5°C by the fine aggregate cooling device 400, and the coarse aggregate is processed by the coarse aggregate cooling device 300 and controlled at 6°C to 9°C. Table 3 lists different coarse aggregate temperatures (temperatures after cooling) and concrete outlet temperatures of different gradations.

[0039] Table 3: Temperature of each level of the dispenser in this embodiment

[0040] Coarse aggregate temperature Four-level matching Three-level matching Secondary distribution First level matching 6℃ 6.12℃ 5.79℃ 5.65℃ 5.32℃ 7℃ 6.74℃ 6.21℃ 6.06℃ 5.77℃ 8℃ 7.29℃ 6.87℃ 6.43℃ 5.94℃ 9℃ 8.08℃ 7.86℃ 6.64℃ 6.27℃

[0041] It can be seen from Table 3 that the full-graded precooling concrete production device A can cool the coarse aggregate and the fine aggregate at the same time, and conveniently prepare four-graded, three-graded, two-graded and one-graded concrete with an outlet temperature of 5°C to 8°C.

[0042] In this embodiment, the pre-cooling sand tank 402 can be replaced by a sand washer. When the ambient temperature is lower than 2°C, the chiller 401 is replaced by a hot water unit.

[0043] Example 2

[0044] The fully graded precooled concrete production device B comprises a coarse aggregate tank 100, a fine aggregate tank 200, a coarse aggregate cooling device 300, a fine aggregate cooling device 400 and a concrete mixing plant 500. The coarse aggregate cooling device 300 is composed of a double-layer screen 301 and a first air-cooled aggregate bin 302. After the coarse aggregate is added to the coarse aggregate tank 100, it is first transported to the double-layer screen 301 by a belt conveyor for secondary screening, and then transported to the first air-cooled aggregate bin 302 by a belt conveyor for primary air cooling. The fine aggregate cooling device 400 is installed within a radius of no more than 50m around the concrete mixing plant 500. The fine aggregate cooling equipment 400 is composed of a chiller 401, a pre-cooling sand tank 402, a cold sand tank 405 and a dehydration screen 406. After the fine aggregate is added into the fine aggregate tank 200, the chiller 401 is started, and the fine aggregate is first transported to the pre-cooling sand tank 402 by a belt conveyor for immersion, then rinsed by the cold sand tank 405, and finally transported to the dehydration screen 406 by a belt conveyor for dehydration.

[0045] The first air-cooled aggregate bin 302 and the dewatering screen 406 are both connected to the concrete mixing plant 500, so the cooled coarse aggregate and fine aggregate can be transported to the concrete mixing plant for production via belt conveyors.

[0046] According to the corresponding proportions in Table 1, the fully graded precooled concrete production device B described in this embodiment is used to produce four-graded, three-graded, two-graded and one-graded concrete, wherein the fine aggregate is kept at a temperature of 4°C by the fine aggregate cooling device 400, and the coarse aggregate is processed by the coarse aggregate cooling device 300 and controlled at 6°C to 9°C. Table 4 lists different coarse aggregate temperatures (temperatures after cooling) and concrete outlet temperatures of different gradations.

[0047] Table 4: Temperature of each level of the dispenser in this embodiment

[0048] Coarse aggregate temperature Four-level matching Three-level matching Secondary distribution First level matching 6℃ 6.06℃ 5.62℃ 5.53℃ 5.26℃ 7℃ 6.63℃ 6.18℃ 5.96℃ 5.61℃ 8℃ 7.16℃ 6.79℃ 6.32℃ 5.82℃ 9℃ 7.86℃ 7.14℃ 6.51℃ 5.98℃

[0049] It can be seen from Table 4 that the full-graded precooling concrete production device B can also cool the coarse aggregate and the fine aggregate at the same time, and conveniently prepare four-graded, three-graded, two-graded and one-graded concrete with an outlet temperature of 5°C to 8°C.

[0050] In this embodiment, the pre-cooling sand tank 402 and the cooling sand tank 405 can be replaced by a sand washer. When the ambient temperature is lower than 2° C., the chiller 401 is replaced by a hot water unit.

[0051] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. Full-graded precooled concrete production device, characterized by: It comprises a coarse aggregate tank (100), a fine aggregate tank (200), a coarse aggregate cooling device (300), a fine aggregate cooling device (400) and a concrete mixing plant (500); The coarse aggregate cooling device (300) is composed of a double-layer screen (301) and a first air-cooled aggregate bin (302) connected in sequence, the double-layer screen (301) is connected to the coarse aggregate tank (100), and the first air-cooled aggregate bin (302) is connected to the concrete mixing plant (500); The fine aggregate cooling equipment (400) is composed of a chiller (401), a pre-cooling sand tank (402), a mechanical vibrating screen (403) and a second air-cooled aggregate bin (404) connected in sequence, wherein the pre-cooling sand tank (402) is connected to the fine aggregate tank (200), and the second air-cooled aggregate bin (404) is connected to the concrete mixing plant (500); the temperature of the cold water generated by the chiller (401) is in the range of 2°C to 6°C; The fully-graded precooled concrete production device is applicable to the production of four-graded, three-graded, two-graded and one-graded concrete, and includes a coarse aggregate cooling device and a fine aggregate cooling device. The two types of separately cooled aggregates can control the concrete outlet temperature to be 5°C to 8°C after mixing.

2. The fully graded precooled concrete production device according to claim 1, characterized in that: The fine aggregate cooling device (400) is replaced by a chiller (401), a pre-cooling sand tank (402), a cooling sand tank (405) and a dewatering screen (406) connected in sequence, wherein the pre-cooling sand tank (402) is connected to the fine aggregate tank (200), and the dewatering screen (406) is connected to the concrete mixing plant (500).

3. The fully graded precooled concrete production device according to claim 1, characterized in that: The pre-cooling sand tank (402) is replaced by a sand washer.

4. The fully graded precooled concrete production device according to claim 2, characterized in that: The pre-cooling sand tank (402) and / or the cooling sand tank (405) are replaced by a sand washer.

5. The fully graded precooled concrete production device according to claim 1 or 2, characterized in that: When the ambient temperature is lower than 2°C, the chiller (401) is replaced by a hot water unit.

6. A method for producing fully graded precooled concrete, characterized in that: The method is carried out using the fully graded precooled concrete production device according to claim 1, which specifically comprises the following steps: (1) Adding coarse aggregate into a coarse aggregate tank (100), adding fine aggregate into a fine aggregate tank (200), and starting a chiller (401); the chiller (401) generates cold water at a temperature ranging from 2° C. to 6° C.; (2) The coarse aggregate is transported to the double-layer screen (301) by a belt conveyor for secondary screening, and then transported to the first air-cooled aggregate bin (302) by a belt conveyor for primary air cooling; at the same time, the fine aggregate is transported to the pre-cooling sand tank (402) by a belt conveyor for spraying, leaching or soaking with cold water, and then screened by a mechanical vibrating screen (403) to remove moisture, and finally transported to the second air-cooled aggregate bin (404) by a belt conveyor for primary air cooling; (3) The cooled coarse aggregate and the cooled fine aggregate are transported to the concrete mixing plant (500) for production via belt conveyors.

7. A method for producing fully graded precooled concrete, characterized in that: The method is carried out using the fully graded precooled concrete production device according to claim 2, which specifically includes the following steps: (1) Adding coarse aggregate into a coarse aggregate tank (100), adding fine aggregate into a fine aggregate tank (200), and starting a chiller (401); the chiller (401) generates cold water at a temperature ranging from 2° C. to 6° C.; (2) The coarse aggregate is transported to the double-layer screen (301) by a belt conveyor for secondary screening, and then transported to the first air-cooled aggregate bin (302) by a belt conveyor for primary air cooling; at the same time, the fine aggregate is transported to the pre-cooling sand tank (402) by a belt conveyor for spraying, leaching or soaking with cold water, and then transported to the cold sand tank (405) by a belt conveyor for secondary water cooling, and finally transported to the dewatering screen (406) by a belt conveyor for dehydration; (3) The cooled coarse aggregate and the cooled fine aggregate are transported to the concrete mixing plant (500) for production via belt conveyors.

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