Large-volume concrete cooling water adjusting method based on temperature difference between water temperature of water tank and concrete water

Abstract

The invention relates to the technical field of mass concrete temperature control, aims to overcome the defects in a traditional temperature control water circulation technology, and particularly relates to a mass concrete cooling water adjusting method based on the temperature difference between the water temperature of a water tank and concrete water. Comprising the following steps that S1, the highest temperature Tmax in concrete and the water inlet temperature Tin of a water tank are collected in real time, and the starting water temperature Tst is set; s2, whether the conditions that Tin is larger than Tst and Tmax-Tin is smaller than delta T are met at the same time or not is judged, wherein delta T is the target concrete-water temperature difference; if not, the automatic water supplementing and draining configuration is not started; if yes, continuing the next step; s3, expected water supplementing and draining duration is set, water is drained to the lowest water level of the water tank, and then water is supplemented to the highest water level of the water tank; and S4, returning to S2 for circulation. Temperature matching has timeliness, short-time, high-frequency and automatic water replenishing can be carried out according to the internal temperature field of the concrete, and the situation that the cooling effect of the concrete is affected due to cooling water temperature regulation hysteresis caused by manual water replenishing is avoided.

Description

Technical Field

[0001] This invention relates to the field of temperature control technology for large-volume concrete, specifically to a method for adjusting cooling water for large-volume concrete based on the temperature difference between the water in the water tank and the concrete water. Background Technology

[0002] In the process of temperature control of large-volume concrete, if the temperature difference between the cooling water and the concrete is too large, it will cause the concrete to experience cold shock, resulting in large tensile stress in the concrete around the water pipe, and even leading to cracks. If the temperature difference between the cooling water and the concrete is too small, the ideal cooling effect cannot be achieved. Therefore, during the water supply process, it is necessary to adjust the flow rate and water temperature of the cooling water in real time and accurately according to the temperature changes inside the concrete in order to achieve the best control effect.

[0003] Traditional temperature-controlled water circulation mainly relies on manual water replenishment. However, due to factors such as real-time fluctuations in cooling water temperature, changes in ambient temperature, and human operation, problems such as under- or over-adjustment of cooling water and significant lag in temperature control are easily caused, which cannot meet the timeliness requirement of matching cooling water temperature and flow rate with the internal temperature field of concrete.

[0004] To address this issue, existing patent application number "200910052803.0," entitled "Temperature Control Method for Mass Concrete," discloses a method for controlling the temperature of mass concrete using a phase change material (PCM) circulation process. The method involves three steps: first, adding solid PCM to cooling water, and then injecting the cooling water mixed with PCM into the inlet of the cooling water pipe of the mass concrete; second, separating the PCM from the water at the outlet of the cooling water pipe; and third, cooling the separated PCM back to a solid state and then recycling it. Adding PCM increases the heat capacity of the cooling circulating water medium, reduces the temperature gradient in the water pipe, and slows down the rate of temperature increase. This improves the temperature control efficiency of the circulating water system while making the internal temperature field of the mass concrete more uniform and harmonious.

[0005] However, this temperature control method, which involves adding phase change materials, increases the overall cost of the control system. Moreover, this method tends to make the internal temperature field of large-volume concrete more uniform, and does not significantly improve the timeliness of the temperature control.

[0006] Therefore, this invention aims to overcome the shortcomings of traditional temperature-controlled water circulation technology and proposes a method for regulating cooling water in large-volume concrete based on the temperature difference between the water tank and the concrete water, using cutting-edge intelligent temperature control technology. Summary of the Invention

[0007] To address the problems of under- or over-adjustment of cooling water and significant lag in temperature control in traditional large-volume concrete temperature-controlled water circulation systems, this invention proposes a method for regulating cooling water in large-volume concrete based on the temperature difference between the water tank and the concrete water. This method establishes a correspondence between the temperature control index—the temperature difference between the concrete water and the opening degree of the replenishment and drainage valves—and automatically adjusts the opening degree of the corresponding valves according to the target temperature to regulate the flow rate and temperature of the cooling water in real time and accurately.

[0008] To achieve the above objectives, a first aspect of the present invention provides a method for adjusting cooling water for large-volume concrete based on the temperature difference between the water tank and the concrete water, comprising the following steps:

[0009] S1: Real-time acquisition of the highest internal temperature T of the concrete max and the water inlet temperature T of the water tank in And set the water temperature T to start. st ;

[0010] S2: Determine T in >T st and T max -T in Does <ΔT satisfy the condition simultaneously, where ΔT is the target concrete water temperature difference;

[0011] If the conditions are not met, the automatic replenishment and drainage configuration will not be activated;

[0012] If satisfied, proceed to the next step;

[0013] S3: Set the expected replenishment and drainage time, drain water to the lowest water level in the tank, and then replenish water to the highest water level in the tank;

[0014] S4: Return to the S2 loop.

[0015] Preferably, in S3, the drainage flow rate Q dr for:

[0016]

[0017] Among them, t dr The duration of drainage, h max The maximum water level in the tank is S, the cross-sectional area of ​​the tank is S, and the density of water is ρ.

[0018] Preferably, in step 3, the water replenishment flow rate Q ad for:

[0019]

[0020] The second aspect of the present invention provides a large-volume concrete cooling water regulation system based on the temperature difference between the water tank and the concrete water, which is constructed based on the large-volume concrete cooling water regulation method based on the temperature difference between the water tank and the concrete water as described above.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention uses real-time monitoring of the internal temperature parameters of concrete to provide feedback on the deviation between the actual temperature and the set threshold. Based on the correspondence between the internal temperature of the structure and the cooling water temperature, it automatically and intelligently adjusts the cooling water temperature and the water supply flow rate in real time and accurately using a "small amplitude, high frequency, and automated" control method. This effectively solves the problem of the timeliness of matching the cooling water temperature and flow rate with the internal temperature field of the concrete.

[0023] Based on the actual application effect of a certain project, it was verified that the timeliness of the automatic water replenishment method is far superior to that of manual water replenishment. The temperature index—the temperature difference of concrete water—was monitored within a time range of 0 to 48 hours. A comparative method was used to verify the difference in timeliness between the automatic water replenishment method and manual water replenishment.

[0024] Compared with traditional manual water replenishment for large-volume concrete, this invention can dynamically adjust the cooling water temperature and replenishment flow rate in real time, significantly improving the uniformity of cooling water temperature during the temperature-controlled water circulation process, while achieving a perfect fit with the internal temperature field of the concrete.

[0025] 2. The method based on the present invention can achieve the purpose of saving water by accurately replenishing water according to the internal temperature field of concrete, thus avoiding the waste of water resources caused by excessive water replenishment.

[0026] 3. The method of the present invention has precise temperature matching and can adaptively and accurately replenish water according to the internal temperature field of concrete, avoiding the phenomenon of under- or over-adjustment of cooling water caused by manual water replenishment, which affects the cooling effect of concrete. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0028] In the attached diagram:

[0029] Figure 1 This is a flowchart of the method of the present invention;

[0030] Figure 2 For the software interface;

[0031] Figure 3 The graph shows the temperature changes under different water replenishment methods. Detailed Implementation

[0032] The following combination Figures 1-3 The preferred embodiments of the present invention will be described herein. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0033] Example 1:

[0034] like Figure 1 As shown, a method for regulating cooling water in large-volume concrete based on the temperature difference between the water in the tank and the concrete water includes the following steps:

[0035] S1: Real-time acquisition of the highest internal temperature T of the concrete max Water inlet temperature T in Water tank outlet temperature T out Water replenishment temperature T ad The water level in the tank is set to height h, and a minimum water level h is set in the tank. min The highest water level in the water tank is h. max Turn on water temperature T st The temperature difference ΔT between the target concrete water and the target concrete water. Note the minimum water level h in the water tank here. min The highest water level in the water tank is h. max It refers to the set water level, not the minimum and maximum water levels of the tank itself.

[0036] S2: Determine T in >T st and T max -T in Does <ΔT simultaneously satisfy:

[0037] If the conditions are not met, the automatic water replenishment and drainage configuration will not be activated, and both the water replenishment pump and the drainage valve will be closed.

[0038] If satisfied, proceed to the next step;

[0039] S3: Set the expected replenishment and drainage time. First, drain the water to the lowest water level in the tank, then replenish the water to the highest water level in the tank.

[0040] First, according to the principle of conservation of heat, the heat released by the hot water is equal to the heat absorbed by the cold water, that is:

[0041] m ad ×c×(T f -T ad )=m out ×c×(T out -T f )+m in ×c×(T in -T f )

[0042] Where, m ad For water replenishment quality, m out For the quality of the effluent, m in Where C is the mass of water entering the tank, T is the specific heat capacity of water, and T is the mass of water entering the tank. f This is the water inlet temperature of the tank after the water temperature has been neutralized.

[0043] According to the above principle of heat conservation, we can obtain:

[0044]

[0045] The water replenishment mass m ad effluent quality m out Combined with the flow Q, we get T. f The relationship between the flow rate Q and the flow rate Q is:

[0046]

[0047] Among them, Q ad To replenish water flow rate, Q out For the outflow rate, t ad The water replenishment time is S, the cross-sectional area of ​​the water tank is S, and the density of water is ρ.

[0048] Furthermore, in this invention, the target concrete water temperature difference ΔT is determined by consulting the specifications for different projects, i.e., ΔT = T max -T f Then T f =T max -ΔT.

[0049] T f Substitute T f The relationship between the water supply flow rate Q and the flow rate Q can be used to obtain the water replenishment flow rate Q. ad :

[0050]

[0051] Drainage flow rate Q dr for:

[0052]

[0053] Among them, t dr This refers to the duration of water replenishment.

[0054] One replenishment / drainage cycle has a duration of t:

[0055] t = t ad +t d

[0056] This means that the replenishment and drainage flow rate can be controlled by setting the expected replenishment and drainage time, thereby precisely controlling the temperature difference between the water tank and the concrete water.

[0057] The water replenishment time in the cycle should account for 1 / 2 to 2 / 3 of the entire cycle. The duration of the entire cycle can be set according to the temperature field inside the concrete at different times.

[0058] Furthermore, the expected replenishment and drainage time should be set according to the actual site conditions and should be matched with the water reserve. When the water source is sufficient, such as when water is directly pumped from a river or spring, there is no requirement for the circulation cycle. When the water source is scarce and water trucks are needed to transport water resources, the circulation cycle needs to be set according to the water truck's water transport time cycle to ensure that the remaining water in the current replenishment tank can meet the requirements of continuous replenishment and drainage circulation (the replenishment tank is an independent water tank connected to the replenishment valve to replenish external water resources). Even when water resources are scarce, the circulation cycle needs to be strictly controlled to ensure that the replenishment and drainage circulation cycle is uninterrupted.

[0059] Example 2:

[0060] This invention provides a large-volume concrete cooling water regulation system based on the temperature difference between the water tank and the concrete water, which is constructed based on the large-volume concrete cooling water regulation method based on the temperature difference between the water tank and the concrete water as described in Example 1.

[0061] Field verification:

[0062] 1. Set relevant parameters

[0063] Water replenishment capacity per truck: 10m³ 3

[0064] Water tank capacity: 36m³ 3 (6*4*1.5)

[0065] The water tank is set to the highest water level h. max 1.4m

[0066] Water tank set minimum water level h min 1.35m

[0067] Water replenishment temperature: 25℃

[0068] Start water temperature Tst: 20℃

[0069] Concrete water temperature difference ΔT control range: 15~20℃

[0070] Makeup and drainage cycle: 10 minutes

[0071] 2. Process

[0072] (1) Concrete pouring. The two tower bases are identical in size and volume, and C50 concrete is poured simultaneously at the same rate to ensure that the concrete is poured at the same time. This ensures that the internal temperature field of the concrete is similar (it is impossible to control it to be exactly the same, as there are many influencing factors).

[0073] (2) Determine the water replenishment method. Water replenishment is carried out according to the changes in the internal temperature field of the concrete. Automatic water replenishment is used for tower A, and manual water replenishment is used for tower B.

[0074] (3) Set the concrete water temperature difference and the replenishment / drainage cycle. This project is a railway bridge, and the concrete water temperature difference ΔT needs to be controlled between 15 and 20℃. To ensure that the concrete water temperature difference ΔT fluctuates within this range, the set value should be set to the midpoint of 17.5℃. When the real-time value of the concrete water temperature difference is less than 17.5℃, the automatic replenishment / drainage device will be activated. Since the water source is abundant in this project, the cycle is not strictly controlled; therefore, the replenishment / drainage cycle is defined as 10 minutes (drainage time: 4 minutes, replenishment time: 6 minutes).

[0075] (4) Judgment. As the internal temperature of the concrete continues to rise, the water tank temperature T... in As the temperature difference between the concrete and water gradually decreases, it is determined that Tin > Tst and Tmax - Tin < ΔT are simultaneously satisfied, and water replenishment begins.

[0076] (5) Manual water replenishment. When the temperature difference of the concrete water is found to be less than 15℃ by manual measurement, a water replenishment command is issued and the water truck starts to transport water. The water truck will arrive at the construction site after 30 to 60 minutes (this time is uncertain, 30 to 60 minutes is the ideal time, it is sometimes faster and sometimes slower, depending on the road conditions and vehicle condition, and the truck may even break down on the way).

[0077] 3. For example Figure 2 This is the program display interface for the control method of the present invention.

[0078] Water temperature sensor: measures the inlet water temperature of the water tank.

[0079] Drain valve: Used for drainage.

[0080] Water pump controller: Replenishes water.

[0081] Target temperature difference: Concrete water temperature difference (15℃~20℃) setting value.

[0082] Current water temperature: Real-time inlet water temperature of the water tank.

[0083] Since construction has been completed on site and the sensors have been removed, the current water temperature and water tank level display is 0.

[0084] 4. Experimental Data

[0085] Because a 48-hour dataset is too large, consisting of minute-level data, it cannot effectively represent actual changes. Therefore, we extract data from a specific time period, selecting 0-12 hours for analysis, and visualize the data, such as... Figure 3 As shown.

[0086] Within 1 to 3 hours, the temperature difference of the concrete water in tower bases A and B is similar, and the highest internal temperature of the concrete is similar.

[0087] Between 3 and 6 hours, as the highest internal temperature of the concrete continues to rise, the temperature difference between the concrete and water in tower B gradually decreases to below 15°C, while the temperature difference between the concrete and water in tower A, which uses automatic water replenishment, remains stable at 15°C to 20°C. At this point, the highest internal temperatures of the concrete in towers A and B are no longer close, and the highest internal temperature of the concrete in tower B rises faster.

[0088] Between 6 and 10 hours, after the water tank of tower B was artificially replenished in the 6th hour, the temperature difference between the concrete water of towers A and B became close again, and the highest internal temperature of the concrete of towers A and B began to remain close again.

[0089] Between 10 and 12 hours, as the highest internal temperature of the concrete continued to rise, the temperature difference between the concrete and water in tower B decreased steadily, gradually approaching 15°C. Meanwhile, the temperature difference in the concrete of tower A, which used automatic water replenishment, remained stable, between 15°C and 20°C. At this point, the highest internal temperatures of the concrete in towers A and B were no longer close, and the highest internal temperature of the concrete in tower B rose more rapidly.

[0090] The above variation patterns show that the maximum internal temperature of the concrete in tower B, which uses artificial water replenishment, rises faster and the temperature difference between the concrete and water fluctuates greatly. In contrast, the temperature difference between the concrete and water in tower A, which uses automatic water replenishment, fluctuates less and remains between 15℃ and 20℃, and the maximum internal temperature of the concrete rises more slowly.

[0091] Note: The highest internal temperature of the concrete and the inlet water temperature of the water tank were both measured using temperature sensors. The concrete-water temperature difference = highest internal temperature of the concrete - inlet water temperature of the water tank.

[0092] In addition, by Figure 2 It can be seen that, using the automatic water replenishment method of this invention, the concrete water temperature difference curve of Tower A shows that the concrete water temperature difference fluctuates at a high frequency and a small amplitude within the range of 15-20℃. That is, the difference between the water temperature in the water tank and the highest temperature inside the concrete is always stable within this range, and it fluctuates at a high frequency and a small amplitude, which is basically stable (of course, 15-20℃ is the control range for the concrete water temperature difference in this project; other projects may have different ranges, which can be represented by ΔT here). However, using the manual water replenishment method, the concrete water temperature difference curve of Tower B shows that the concrete water temperature difference fluctuates at a low frequency and a large amplitude, which significantly exceeds the control standard of 15-20℃ (ΔT) for the concrete water temperature difference. It is difficult to ensure that the water temperature in the water tank matches the highest temperature inside the concrete. That is, the difference between the water temperature in the water tank and the highest temperature inside the concrete does not meet the control range of the concrete water temperature difference, and the period of temperature difference fluctuation is very long, basically the period of water truck transportation.

[0093] Therefore, it can be seen that the automatic water replenishment method can ensure that the temperature difference between the water in the tank and the highest temperature inside the concrete remains stable within the specified range of concrete-water temperature difference, and that the fluctuations are frequent and small. In contrast, manual water replenishment is difficult to guarantee that the temperature difference between the water in the tank and the highest temperature inside the concrete remains stable within the specified range of concrete-water temperature difference, and the fluctuations are long and large. Therefore, the timeliness of the automatic water replenishment method is far superior to that of manual water replenishment.

[0094] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A mass concrete cooling water adjustment method based on the water tank water temperature and the concrete water temperature difference, characterized in that, Comprising the following steps: S1: Collect the highest temperature T inside the concrete in real time max and the water inlet temperature T of the water tank in , and set the opening water temperature T st ; S2: determine T in > T st and T max - T in < ΔT, where ΔT is the target concrete water temperature difference; If not satisfied, the automatic water replenishment and drainage configuration is not started; If satisfied, continue to the next step; S3: Set the expected water replenishment and drainage duration, drain to the lowest water level of the water tank, and then replenish water to the highest water level of the water tank to realize the regulation of cooling water; S4: Return to S2 for circulation.

2. The method for regulating the cooling water of mass concrete based on the temperature difference between the water tank and the concrete water according to claim 1, characterized in that, In S3, the drain flow rate Q dr is: where t dr is the duration of the replenishment, h max is the maximum water level in the tank, h min is the set minimum water level in the tank, S is the cross-sectional area of the tank, and p is the density of water.

3. The method for regulating the cooling water of mass concrete based on the temperature difference between the water tank and the concrete water according to claim 2, characterized in that, In step 3, the make-up flow Q ad is:

4. A mass concrete cooling water regulating system based on the difference between the water tank water temperature and the concrete water temperature, characterized in that: The mass concrete cooling water regulation method based on the water tank water temperature and concrete water temperature difference is constructed based on any one of claims 1-3.

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