A low-energy consumption centrifugal molding preparation process for a power distribution concrete pole
Patent Information
- Application Number
- CN202611298969.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-26
- Publication Date
- 2026-10-16
AI Technical Summary
[0003]但现有技术仍存在以下不足：其一，搅拌水化热、离心摩擦热、养护用热等各工序热量被孤立对待，未形成系统化统筹利用
[0023] 1. In this invention, the heat of hydration of the concrete mixing process is collected by the first heat exchange coil, the frictional heat and heat of hydration of the centrifugal molding process are absorbed by the phase change heat storage jacket, and the waste heat of steam from the steam curing process is collected by the second heat exchange coil. This constructs a three-level heat source collection system covering the entire process of "mixing, centrifugation and curing", which systematically recovers the heat from each process that was originally dispersed and dissipated, and helps to reduce the supplementary input of external heat sources.
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Figure CN122914355A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power distribution concrete pole preparation technology, specifically a low-energy centrifugal molding preparation process for power distribution concrete poles. Background Technology
[0002] In the centrifugal molding process of power distribution concrete poles, steam curing energy consumption accounts for more than 80% of the total production energy consumption. To reduce curing energy consumption, existing technologies have been improved in areas such as non-steam-cured concrete, waste heat recovery, and intelligent temperature control. For example, waste heat from steam curing is introduced into the steam curing tank to be heated, a preheating cavity is set on the steel mold, and solar heating is used.
[0003] However, existing technologies still have the following shortcomings: First, the heat generated in each process, such as the heat of hydration during stirring, the heat of centrifugal friction, and the heat used for curing, is treated in isolation and not utilized systematically. Second, the frictional heat and heat of hydration generated during the centrifugation stage are released during the centrifugation process, while steam curing needs to be carried out after centrifugation. This mismatch in time between heat generation and heat use means that the heat cannot be stored and is directly lost. Third, although phase change heat storage technology has been applied in fields such as temperature control of large-volume concrete, there is still no technical solution to integrate it into the outer wall of the steel formwork of the utility pole to bridge the time difference between the heat generated by centrifugation and the heat used for curing. Summary of the Invention
[0004] The purpose of this invention is to provide a low-energy centrifugal molding process for preparing power distribution concrete poles, so as to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-energy centrifugal molding process for preparing power distribution concrete poles, comprising the following steps:
[0006] Step 1: Concrete mixing: Mix the raw materials according to the mix proportion to obtain a concrete mixture. At the same time, the heat of hydration is recovered by the first heat exchange coil on the outer wall of the mixer and heated to form the first heat transfer medium inside.
[0007] Step 2, Steel Mold Preheating: The first heat transfer fluid is sent into the first heat exchange pipeline in the phase change heat storage interlayer of the outer wall of the pole steel mold to heat the phase change heat storage material inside to above the phase change temperature to store latent heat, and the steel mold wall is preheated simultaneously; the phase change heat storage interlayer is located between the outer wall of the steel mold and the external insulation layer, and is arranged continuously along the axial and circumferential directions.
[0008] Step 3, Reinforcing steel cage installation and placement: Place the precast reinforcing steel cage into the preheated steel mold, feed in the concrete mixture, place the concrete, and close the mold;
[0009] Step 4, Centrifugal molding: The steel mold after molding is placed in a centrifuge and rotated to make the concrete compacted. During the centrifugation process, the frictional heat of the steel mold and the hydration heat of the concrete are absorbed and stored by the phase change heat storage material. After centrifugation, a molded electric rod is obtained.
[0010] Step 5, Steam curing: The electric rod with mold is transferred into the curing kiln and steam is introduced for curing. When the kiln temperature is lower than the phase change temperature, the phase change heat storage material releases latent heat and transfers heat to the steel mold wall through the inner wall of the phase change heat storage jacket to assist in heat preservation curing, thereby reducing the amount of curing steam consumed and reducing temperature stress cracks in the concrete.
[0011] Step 6, Waste heat recovery: Collect the waste heat steam discharged from the curing kiln, pass it into the second heat exchange coil outside the kiln to heat the second heat exchange medium inside to form a second heat transfer fluid, and send the second heat transfer fluid into the second heat exchange pipeline of the phase change heat storage jacket to supplement heat storage, or send it into the first heat exchange coil of the next batch of poles as a preheating heat source.
[0012] Step 7: Demolding: After curing, remove the steel mold and demold to obtain the finished concrete pole for power distribution.
[0013] Preferably, the phase change temperature of the phase change heat storage material in step two is 45℃~60℃, the phase change heat storage material is an inorganic hydrated salt phase change material or a paraffin-based organic phase change material, and the filling volume ratio of the phase change heat storage material in the phase change heat storage interlayer is 75%~90% of the internal volume of the phase change heat storage interlayer.
[0014] Preferably, the external insulation layer in step two is a rock wool insulation layer or a polyurethane foam insulation layer, the thickness of the external insulation layer is 20mm to 50mm, the external insulation layer is covered and fixed to the outer wall of the phase change heat storage jacket by adhesive or mechanical fastening, and the external insulation layer is segmented along the axial direction of the pole steel mold, and a sealing strip is provided at the splice seam between adjacent segments.
[0015] Preferably, the centrifugation process in step four includes a slow spreading stage, a medium-speed transition stage, and a high-speed compaction stage; the rotation speed of the slow spreading stage is 100 r / min to 200 r / min, and the duration is 1 min to 3 min; the rotation speed of the medium-speed transition stage is 300 r / min to 500 r / min, and the duration is 2 min to 5 min; the rotation speed of the high-speed compaction stage is 600 r / min to 900 r / min, and the duration is 3 min to 8 min.
[0016] Preferably, in step two, the first heat exchange pipeline and in step six, the second heat exchange pipeline are arranged in a spiral or serpentine coil within the phase change heat storage jacket. The first heat exchange pipeline and the second heat exchange pipeline are stacked radially along the pole steel mold or arranged alternately circumferentially along the pole steel mold. Furthermore, the first heat exchange pipeline and the second heat exchange pipeline are independent of each other and are not connected to each other.
[0017] Preferably, the steam curing in step five includes a heating stage, a constant temperature stage, and a cooling stage; the heating stage raises the temperature inside the curing kiln to 60℃ to 80℃ at a heating rate of 15℃ / h to 25℃ / h; the constant temperature stage maintains the temperature at 60℃ to 80℃ for a duration of 4h to 8h; the cooling stage lowers the temperature inside the curing kiln to room temperature at a cooling rate of 10℃ / h to 20℃ / h; during the constant temperature stage and the cooling stage, the phase change heat storage material continuously releases latent heat.
[0018] Preferably, the temperature of the waste heat steam in step six is 40°C to 70°C, the second heat exchange medium is water or heat transfer oil, and when the second heat carrier fluid is transported to the second heat exchange pipeline to supplement heat storage, the temperature of the second heat carrier fluid is at least 5°C higher than the phase change temperature of the phase change heat storage material.
[0019] Preferably, in step two, a thermally conductive silicone grease layer is provided between the inner wall surface of the phase change heat storage interlayer and the outer wall surface of the pole steel mold. The thickness of the thermally conductive silicone grease layer is 0.5mm to 2mm, which is used to reduce the contact thermal resistance between the phase change heat storage interlayer and the pole steel mold. As an alternative, the thermally conductive silicone grease layer can be replaced with a graphite thermally conductive pad.
[0020] Preferably, the phase change thermal storage interlayer is equipped with a pressure relief valve and a temperature sensor. The pressure relief valve is located on the outer wall of the phase change thermal storage interlayer and extends through the external insulation layer to the outside. The inlet of the pressure relief valve is connected to the internal space of the phase change thermal storage interlayer, and the outlet of the pressure relief valve is open to the external environment. When the temperature sensor detects that the temperature inside the phase change thermal storage interlayer exceeds a preset safety threshold, the pressure relief valve automatically opens to release the internal pressure of the interlayer. The probe of the temperature sensor extends into the phase change thermal storage interlayer and is located in the phase change thermal storage material. The wire of the temperature sensor is led out from the probe, passes through the outer wall of the phase change thermal storage interlayer and the external insulation layer, and extends to the outside for connection to external temperature monitoring or control equipment. The pressure relief valve and the temperature sensor are respectively arranged at different circumferential positions of the phase change thermal storage interlayer to avoid interference.
[0021] Preferably, the first heat exchange pipeline and the second heat exchange pipeline are respectively connected to a circulating pump and a flow regulating valve. The circulating pump provides the power for the circulation of the heat medium, and the flow regulating valve adjusts the flow rate of the heat medium according to the real-time temperature of the phase change heat storage material.
[0022] Compared with the prior art, the beneficial effects of the present invention are:
[0023] 1. In this invention, the heat of hydration of the concrete mixing process is collected by the first heat exchange coil, the frictional heat and heat of hydration of the centrifugal molding process are absorbed by the phase change heat storage jacket, and the waste heat of steam from the steam curing process is collected by the second heat exchange coil. This constructs a three-level heat source collection system covering the entire process of "mixing, centrifugation and curing", which systematically recovers the heat from each process that was originally dispersed and dissipated, and helps to reduce the supplementary input of external heat sources.
[0024] 2. In this invention, by setting a phase change heat storage interlayer on the outer wall of the electric pole steel mold, the latent heat storage characteristics of the phase change heat storage material are utilized to store the frictional heat and hydration heat generated during the centrifugal molding stage. During the steam curing stage, when the temperature of the curing kiln is lower than the phase change temperature, the heat is automatically released, thereby alleviating to some extent the problem of the mismatch between the heat generated in the centrifugal process and the heat used in the curing process in terms of time.
[0025] 3. In this invention, the second heat transfer fluid formed by recovering the waste heat steam discharged from the curing kiln through the second heat exchange coil can be used to supplement the phase change heat storage material, or it can be transported to the stirring process of the next batch of electric poles as a preheating heat source, thereby realizing the partial recycling of heat and reducing the direct emission of heat energy.
[0026] 4. In this invention, by cascading heat recovery and cross-time storage and utilization in multiple processes, the amount of external steam replenishment during the steam curing stage can be reduced, thereby reducing the overall energy consumption of the preparation process. At the same time, since the phase change heat storage material continuously releases heat during the constant temperature and cooling stages of curing, it helps to reduce the temperature fluctuation range in the curing kiln and reduce concrete temperature stress cracks caused by drastic temperature changes. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the low-energy centrifugal molding process for preparing power distribution concrete poles according to the present invention.
[0028] Figure 2 This is a schematic cross-sectional view of the low-energy centrifugal molding process for preparing power distribution concrete poles according to the present invention.
[0029] Legend:
[0030] 1. Steel formwork for utility poles; 2. Phase change heat storage interlayer; 3. Phase change heat storage material; 4. External insulation layer; 5. First heat exchange pipeline; 6. Second heat exchange pipeline; 7. Thermally conductive silicone grease layer. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] Example 1
[0033] This embodiment provides a low-energy centrifugal molding process for preparing power distribution concrete poles, including the following steps:
[0034] Step 1: Concrete Mixing
[0035] Cement, aggregates, water, and admixtures are weighed according to the designed mix proportions and added to a mixer for mixing to obtain a concrete mixture. During the mixing process, the cement hydration reaction releases heat of hydration, and the temperature of the concrete inside the mixer gradually increases. In this embodiment, a first heat exchange coil is installed on the outer wall of the mixer, and the first heat exchange coil is filled with a first heat exchange medium (water in this embodiment). After absorbing the heat of hydration on the outer wall of the mixer, the temperature of the first heat exchange medium rises to approximately 45℃~55℃, forming a first heat-carrying fluid. The first heat exchange coil is connected to a circulation pump with a flow rate ≥3m³ / h, providing power for the circulation and transport of the first heat-carrying fluid.
[0036] Step 2: Preheating the steel mold
[0037] A phase change heat storage interlayer 2 is provided on the outer wall of the pole steel mold 1, located between the outer wall of the pole steel mold 1 and the external insulation layer 4. The phase change heat storage interlayer 2 is continuously arranged along the axial and circumferential directions of the pole steel mold 1. The phase change heat storage interlayer 2 is filled with a phase change heat storage material 3. In this embodiment, the phase change heat storage material 3 is a paraffin-based organic phase change material with a phase change temperature of 45℃~60℃. The filling volume ratio of the phase change heat storage material 3 in the phase change heat storage interlayer 2 is 80% of the internal volume of the phase change heat storage interlayer 2.
[0038] A first heat exchange pipe 5 is embedded inside the phase change heat storage jacket 2. The first heat exchange pipe 5 is arranged in a spiral shape inside the phase change heat storage jacket 2. The first heat transfer fluid (hot water at approximately 45°C to 55°C) obtained in step one is transported to the first heat exchange pipe 5 through a circulation pump. In this embodiment, the measured temperature of the first heat transfer fluid when it enters the first heat exchange pipe 5 is 48°C to 52°C. Since the phase change temperature range of the phase change heat storage material 3 is 45°C to 60°C, and the temperature of the first heat transfer fluid is in the lower middle part of this phase change temperature range, although the temperature gradient is limited, the phase change heat storage material 3 can still be gradually heated and undergo phase change heat storage through continuous flow heat exchange under the condition of continuous transportation by the circulation pump. Actual measurements show that, under the condition of a circulating pump flow rate of 3 m³ / h, the time required for the phase change heat storage material 3 to heat up from room temperature (approximately 20°C) to the phase change temperature (45°C) is approximately 25 to 35 minutes, which is well within the time window allowed by the process (the material feeding and molding process takes approximately 15 to 20 minutes, and the centrifugal molding process takes approximately 8 to 13 minutes, totaling approximately 23 to 33 minutes). Therefore, although the heat of hydration during stirring is of a relatively low grade, through the superposition of heat storage with the frictional heat and heat of hydration in the subsequent centrifugal stage, the phase change heat storage material 3 can still reach an effective heat storage state before the centrifugal molding is completed. If the temperature of the first heat transfer fluid measured on-site is lower than 45°C, an auxiliary electric heating device can be added to compensate for the heating of the first heat transfer fluid, ensuring that its temperature does not fall below the lower limit of the phase change temperature when it enters the first heat exchange pipeline 5.
[0039] When the first heat transfer fluid flows through the first heat exchange pipe 5, it transfers heat to the phase change heat storage material 3 filled in the phase change heat storage jacket 2, causing the phase change heat storage material 3 to heat up to above its phase change temperature (in this embodiment, the temperature is raised to about 55°C to 60°C), and the phase change heat storage material 3 undergoes a solid-liquid phase change to store latent heat. At the same time, the heat from the first heat transfer fluid is also transferred to the mold wall of the pole steel mold 1 through the first heat exchange pipe 5, preheating the pole steel mold 1 and raising the temperature of the mold wall to about 40°C to 50°C.
[0040] The external insulation layer 4 is a rock wool insulation layer with a thickness of 30mm. The external insulation layer 4 is covered and fixed to the outer wall of the phase change heat storage jacket 2 by adhesive bonding. The external insulation layer 4 is segmented along the axial direction of the pole steel mold 1, and sealing strips are provided at the splice joints between adjacent segments to prevent heat loss.
[0041] A thermally conductive silicone grease layer 7, with a thickness of 1 mm, is provided between the inner wall of the phase change heat storage interlayer 2 and the outer wall of the pole steel mold 1. This layer is used to reduce the contact thermal resistance between the phase change heat storage interlayer 2 and the pole steel mold 1, thereby improving heat transfer efficiency. Alternatively, the thermally conductive silicone grease layer 7 can be replaced with a graphite thermally conductive pad.
[0042] The phase change thermal storage jacket 2 is also equipped with a pressure relief valve and a temperature sensor. The pressure relief valve is located on the outer wall of the phase change thermal storage jacket 2 and extends through the outer insulation layer 4 to the outside. The inlet of the pressure relief valve is connected to the internal space of the phase change thermal storage jacket 2, and the outlet of the pressure relief valve is open to the external environment. When the temperature sensor detects that the temperature inside the phase change thermal storage jacket 2 exceeds a preset safety threshold, the pressure relief valve automatically opens to release the internal pressure of the jacket. The probe of the temperature sensor extends into the phase change thermal storage jacket 2 and is located in the phase change thermal storage material 3. The wire of the temperature sensor is led out from the probe, passes through the outer wall of the phase change thermal storage jacket 2 and the outer insulation layer 4, and extends to the outside for connection to external temperature monitoring or control equipment. The pressure relief valve and the temperature sensor are arranged at different circumferential positions of the phase change thermal storage jacket 2, without interfering with each other. In this embodiment, the preset safety threshold is determined based on the phase change temperature of the phase change heat storage material 3, which is 5°C to 10°C above the upper limit of the phase change temperature. That is, when the phase change temperature is 45°C to 60°C, the preset safety threshold is set to 65°C to 70°C.
[0043] In this embodiment, the probe of the temperature sensor extends into the phase change heat storage jacket 2. The signal output of the temperature sensor preferably uses a slip ring transmission method, where the signal line of the temperature sensor is connected to a conductive slip ring located at the end of the pole mold 1. The temperature signal is transmitted to external monitoring equipment through the sliding contact between the rotating end and the stationary end of the slip ring, ensuring the stability of signal transmission under high-speed rotation conditions. Alternatively, a wireless transmission method can be used, where the temperature sensor integrates an industrial-grade anti-interference wireless transmission module to wirelessly transmit the detected temperature signal to an external receiver. The flow regulating valve is located on the stationary component at the end of the pole mold 1, rather than on the rotating mold body. The second heat exchange pipeline 6 is connected to the flow regulating valve via a rotary joint. The rotating end of the rotary joint rotates synchronously with the pole mold 1, and the stationary end of the rotary joint is connected to the flow regulating valve, thereby enabling the stationary valve to regulate and control the flow of the heat medium in the rotating pipeline.
[0044] Step 3: Installation and placement of the reinforcing steel frame
[0045] The prefabricated steel reinforcement cage is placed into the pole mold 1, which has been preheated in step two. The concrete mixture prepared in step one is then fed into the pole mold 1, completing the placement and mold closing. Since the pole mold 1 has been preheated, the concrete mixture will not experience early temperature shock due to the low temperature of the mold during the placement process, which is beneficial for the uniform placement of concrete and the early hydration reaction.
[0046] Step 4: Centrifugal molding
[0047] The pole steel mold 1, after being molded in step three, is placed on a centrifuge and centrifuged according to the centrifugal rotation regime. The centrifugal rotation regime includes three stages: a slow spreading stage, a medium-speed transition stage, and a high-speed compaction stage.
[0048] Slow-speed material distribution stage: The rotation speed is 120 r / min, and the duration is 2 min, so that the concrete mixture is evenly distributed along the inner wall of the steel mold under the action of centrifugal force;
[0049] Medium-speed transition stage: The rotation speed is 400 r / min and the duration is 3 min, which realizes a smooth transition from slow speed to high speed and avoids impact damage to the concrete structure;
[0050] High-speed compaction stage: The rotation speed is 750 r / min and the duration is 5 min, so that the concrete mixture is fully compacted and formed under high centrifugal force.
[0051] During centrifugal molding, the high-speed rotation of the pole mold 1 generates frictional heat, while the hydration reaction of the concrete inside the mold continuously releases hydration heat. The phase change heat storage material 3 within the phase change heat storage interlayer 2 absorbs the frictional heat and hydration heat, continuing to store latent heat. The phase change heat storage material 3 continuously absorbs heat during the centrifugal stage, effectively storing the heat generated during centrifugation and preventing the steel mold and concrete from overheating due to heat accumulation. After centrifugal molding, a molded pole is obtained.
[0052] Step 5: Steam Curing
[0053] The molded electric rod obtained in step four is transferred to the curing kiln, and steam is introduced into the curing kiln for steam curing.
[0054] Steam curing includes a heating stage, a constant temperature stage, and a cooling stage:
[0055] Heating stage: The temperature inside the curing kiln is raised to 70℃ at a heating rate of 20℃ / h;
[0056] Constant temperature phase: Maintain a temperature of 70℃ for 6 hours;
[0057] Cooling stage: The temperature inside the curing kiln is reduced to room temperature at a cooling rate of 15℃ / h.
[0058] During steam curing, when the temperature inside the curing kiln is lower than the phase change temperature (45℃~60℃) of the phase change heat storage material 3, the phase change heat storage material 3 in the phase change heat storage jacket 2 releases the stored latent heat. This heat is then transferred to the mold wall of the pole steel mold 1 through the thermally conductive silicone grease layer 7 via the inner wall of the phase change heat storage jacket 2, thus providing auxiliary heat preservation and curing for the concrete inside the pole steel mold 1. Specifically:
[0059] During the heating stage, the temperature of the curing kiln rises from room temperature to 70℃. During this stage, the kiln temperature gradually exceeds the phase change temperature (45℃~60℃). In the early stage of the heating stage (when the kiln temperature is lower than the phase change temperature), the phase change heat storage material 3 continues to release heat to assist in the increase of the kiln temperature. When the kiln temperature exceeds the phase change temperature, the phase change heat storage material 3 stops releasing heat and begins to absorb heat to prevent the concrete from developing temperature stress cracks due to excessively rapid heating.
[0060] During the constant temperature stage (70℃), the curing kiln temperature is higher than the phase change temperature (45℃~60℃). The phase change heat storage material 3 is in a heat storage state, absorbing excess heat in the kiln and playing a temperature buffering role, making the concrete surface temperature more uniform.
[0061] During the cooling stage, the temperature of the curing kiln drops from 70℃ to room temperature. When the kiln temperature drops below the phase change temperature (45℃~60℃), the phase change heat storage material 3 releases the stored latent heat again, slowing down the cooling rate of the concrete and preventing temperature stress cracks from forming in the concrete due to excessive cooling.
[0062] By regulating the heat absorption and release of phase change heat storage material 3 at each stage of curing, this embodiment effectively reduces the consumption of curing steam and reduces the generation of temperature stress cracks in concrete.
[0063] Step Six: Waste Heat Recovery
[0064] The waste heat steam discharged from the curing kiln in step five is collected. The temperature of the waste heat steam is 50℃~65℃. The waste heat steam is introduced into a second heat exchange coil located outside the curing kiln. The second heat exchange coil is filled with a second heat exchange medium (water in this embodiment). After absorbing the heat from the waste heat steam, the temperature of the second heat exchange medium rises to approximately 55℃~70℃, forming a second heat transfer fluid.
[0065] The second heat exchange pipeline 6 is arranged in a spiral shape within the phase change heat storage jacket 2, and is stacked radially with the first heat exchange pipeline 5 along the pole steel mold 1. The first heat exchange pipeline 5 and the second heat exchange pipeline 6 are independent of each other and are not connected. The second heat exchange pipeline 6 is connected to a circulation pump and a flow regulating valve.
[0066] The second heat transfer fluid is pumped to the second heat exchange pipe 6 in the phase change heat storage jacket 2 via a circulating pump to supplement the heat storage of the phase change heat storage material 3. The temperature of the second heat transfer fluid (55℃~70℃) is at least 5℃ higher than the phase change temperature (45℃~60℃) of the phase change heat storage material 3, thus effectively driving the phase change heat storage material 3 to undergo phase change again to store latent heat. In actual production, the temperature of the waste heat steam discharged from the curing kiln may drop to 40℃~50℃ due to factors such as ambient temperature, the insulation performance of the curing kiln, and the steam flow rate. At this time, the temperature of the second heat transfer fluid may be lower than or close to the phase change temperature of the phase change heat storage material 3, and cannot effectively drive the phase change heat storage material 3 to supplement heat storage. In view of this situation, this embodiment provides the following two optional processing methods:
[0067] (1) When the temperature of the waste heat steam is lower than the lower limit of the phase change temperature (45°C), the second heat transfer fluid is not sent to the second heat exchange pipeline 6 of the phase change heat storage jacket 2, but is directly switched to the first heat exchange coil on the outer wall of the mixer of the next batch of electric poles as a preheating heat source. In this way, even if the waste heat steam is at a lower temperature, it can still be used to preheat the mixer and mixing water, reduce the heat loss during the mixing stage, and realize the direct utilization of waste heat across batches.
[0068] (2) A heat pump heating device is installed on the pipeline between the second heat exchange coil and the phase change heat storage jacket 2. When the temperature of the waste heat steam is lower than the phase change temperature, the heat pump is started to raise the temperature of the second heat transfer fluid to at least 5°C above the phase change temperature, and then it is transported to the second heat exchange pipeline 6 for supplementary heat storage. The energy consumption of the heat pump is much lower than the heat energy input required for steam curing, and the overall energy consumption is still controllable.
[0069] When the heat storage capacity of the phase change heat storage material 3 is sufficient, the second heat transfer fluid can also be transported to the first heat exchange coil on the outer wall of the mixer of the next batch of electric poles as a preheating heat source.
[0070] The control logic of the flow regulating valve is as follows: the opening degree of the flow regulating valve is negatively correlated with the real-time temperature of the phase change heat storage material 3. When the temperature sensor detects that the real-time temperature of the phase change heat storage material 3 is more than 5°C lower than the lower limit of the phase change temperature (45°C) (i.e., below 40°C), the opening degree of the flow regulating valve is adjusted to 100%, so that the heat medium passes through the second heat exchange pipeline 6 at the maximum flow rate, accelerating the reheating of the phase change heat storage material 3. When the real-time temperature is more than 5°C higher than the upper limit of the phase change temperature (60°C) (i.e., above 65°C), the opening degree of the flow regulating valve is adjusted to 20% to 40%, reducing the flow rate of the heat medium and preventing the phase change heat storage material 3 from overheating. When the real-time temperature is within the phase change temperature range of 45°C to 60°C, the opening degree of the flow regulating valve is linearly adjusted according to the relative position of the real-time temperature and the phase change temperature range.
[0071] Step 7: Demolding
[0072] After steam curing is completed in step five, the steel mold 1 of the power pole is removed from the curing kiln, and the mold is disassembled to obtain the finished power distribution concrete power pole.
[0073] Heat balance analysis (theoretical calculation) of this process:
[0074] The following is a theoretical calculation example of heat recovery and utilization in the process of this invention (taking a single 12m long, 190mm diameter concrete distribution pole as an example):
[0075] (1) Heat can be recovered during the centrifugation stage:
[0076] The heat of hydration of cement is calculated at 280 kJ / kg, the amount of cement used is 400 kg / m³, and the volume of concrete in the pole is about 0.35 m³. Therefore, the total heat of hydration is 280 × 400 × 0.35 = 39,200 kJ.
[0077] The total heat generated by centrifugal friction, Q_friction, is estimated using the formula Q=μ·F·v·t, where μ is the coefficient of friction, F is the normal force exerted by the steel mold on the support roller (i.e., the total weight of the steel mold, approximately 1500 kg, equivalent to 14,700 N), v is the linear velocity of the support roller, and t is the total centrifugal time. Taking the coefficient of friction μ as 0.12, the linear velocity of the support roller as 6.5 m / s, and the total centrifugal time as approximately 10 min (600 s), the total frictional heat is 0.12 × 14,700 × 6.5 × 600 = 6,879,600 J ≈ 6,880 kJ.
[0078] The total recoverable heat during the centrifugation stage is approximately 39,200 + 6,880 ≈ 46,080 kJ.
[0079] (2) Thermal storage capacity of phase change thermal storage interlayer 2:
[0080] The volume of the phase change heat storage interlayer 2 is calculated by multiplying the outer wall area of the steel mold (π×0.45m×12m≈16.96m²) by the interlayer thickness (0.01m), which is approximately 0.17m³. Assuming a phase change material filling volume fraction of 80%, the volume of the phase change material is 0.17×0.8=0.136m³. Assuming a density of 780kg / m³ and a latent heat of phase change of 200kJ / kg, the total heat storage capacity of the phase change material is approximately 0.136×780×200≈21,216kJ.
[0081] (3) Heat matching relationship:
[0082] The recoverable heat during the centrifugation stage (approximately 46,080 kJ) is greater than the heat storage capacity of the phase change material (approximately 21,216 kJ), indicating that the heat generated during the centrifugation stage is sufficient to completely melt the phase change material and store its latent heat. Excess heat (approximately 24,864 kJ) can be reduced through the insulation layer, and some of the heat can be directly preheated through the steel mold wall to aid in the early hydration of the concrete.
[0083] (4) Energy-saving effect estimation during the maintenance phase:
[0084] The latent heat released by the phase change material during the curing cooling stage is approximately 21,216 kJ. Assuming a 50% thermal efficiency of the steam in the curing kiln, this 21,216 kJ of latent heat is equivalent to a reduction of approximately 42,432 kJ of steam heat energy input, which translates to approximately 19 kg of steam (based on a latent heat of 2,200 kJ / kg). The total steam consumption for curing a single pole is approximately 60 kg to 80 kg, theoretically reducing steam consumption by approximately 24% to 32%. Therefore, the claim of "approximately 30% reduction in steam consumption" in the embodiments of the specification is supported by thermodynamic theory.
[0085] Verification of the beneficial effects of this embodiment
[0086] Based on the above heat balance calculations and small-batch trial production verification (50 poles), the low-energy centrifugal molding process for power distribution concrete poles in this embodiment, compared with poles prepared using a conventional steam curing process with molds (the outer wall of the steel mold is covered with rock wool insulation of the same thickness, but without a phase change heat storage interlayer 2 and waste heat recovery system) under the same production workshop, the same batch of raw materials, and the same pole specifications: steam consumption during the steam curing stage is reduced by approximately 30%; overall energy consumption (including centrifugal power consumption, curing steam consumption, etc.) is reduced by approximately 35%; the temperature fluctuation range inside the curing kiln is reduced from ±8℃ in the control process to ±3℃; the surface temperature stress crack rate of the finished poles is reduced by approximately 40%; and the 28-day compressive strength of the pole concrete is increased by approximately 5% to 8%. All data represent the comparison between the measured average values from the trial production and the measured average values from the control process.
[0087] Example 2
[0088] The difference between this embodiment and Embodiment 1 is that:
[0089] The phase change thermal storage material 3 is an inorganic hydrated salt phase change material with a phase change temperature of 50℃. Inorganic hydrated salt phase change materials have the advantages of high heat of fusion and high thermal conductivity. The filling volume of the phase change thermal storage material 3 in the phase change thermal storage jacket 2 is 85% of the internal volume of the phase change thermal storage jacket 2.
[0090] The external insulation layer 4 is a polyurethane foam insulation layer with a thickness of 40mm.
[0091] The thermal pads are made of graphite and have a thickness of 1.5mm.
[0092] In the centrifugation process: the slow feeding stage has a rotation speed of 150 r / min and a duration of 2.5 min; the medium-speed transition stage has a rotation speed of 450 r / min and a duration of 2 min; and the high-speed compaction stage has a rotation speed of 800 r / min and a duration of 6 min.
[0093] During steam curing: the heating stage is to raise the temperature to 75℃ at a rate of 18℃ / h; the constant temperature stage is to maintain the temperature at 75℃ for 5 hours; and the cooling stage is to lower the temperature to room temperature at a rate of 12℃ / h.
[0094] The remaining steps are the same as in Example 1.
[0095] Example 3
[0096] The difference between this embodiment and Embodiment 1 is that:
[0097] The first heat exchange pipe 5 and the second heat exchange pipe 6 are arranged alternately along the circumference of the electric pole steel mold 1 within the phase change heat storage jacket 2, rather than being arranged in radial stacks. This arrangement is beneficial for the two sets of heat exchange pipes to distribute heat evenly in the circumferential direction, making the temperature distribution of the phase change heat storage material 3 within the jacket more uniform.
[0098] The remaining steps are the same as in Example 1.
[0099] Example 4
[0100] The difference between this embodiment and Embodiment 1 is that:
[0101] In step six, the second heat transfer fluid (hot water at 55℃~70℃) is not transported to the second heat exchange pipe 6 of the phase change heat storage jacket 2 for supplementary heat storage, but is directly transported to the first heat exchange coil on the outer wall of the agitator of the next batch of electric poles as a preheating heat source. This method is suitable for situations where the heat storage capacity of the phase change heat storage material 3 is already saturated and no supplementary heat storage is needed, realizing the direct utilization of waste heat steam across batches.
[0102] The remaining steps are the same as in Example 1.
[0103] Example 5
[0104] The difference between this embodiment and Embodiment 1 is that:
[0105] The phase change thermal storage material 3 fills 75% of the internal volume of the phase change thermal storage interlayer 2. The wall thickness of the phase change thermal storage interlayer 2 is 15 mm. The external insulation layer 4 is a rock wool insulation layer with a thickness of 25 mm.
[0106] In the centrifugation process: the slow feeding stage has a rotation speed of 100 r / min and a duration of 3 min; the medium-speed transition stage has a rotation speed of 300 r / min and a duration of 5 min; and the high-speed compaction stage has a rotation speed of 600 r / min and a duration of 8 min.
[0107] During steam curing: the heating stage is to raise the temperature to 60℃ at a rate of 15℃ / h; the constant temperature stage is to maintain the temperature at 60℃ for 8 hours; and the cooling stage is to lower the temperature to room temperature at a rate of 10℃ / h.
[0108] The preset safety threshold is set to 8°C above the upper limit of the phase change temperature (i.e., 68°C).
[0109] The remaining steps are the same as in Example 1.
[0110] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A low-energy centrifugal molding process for preparing concrete distribution poles, characterized in that, Includes the following steps: Step 1: Concrete mixing: Mix the raw materials according to the mix proportion to obtain a concrete mixture. At the same time, the heat of hydration is recovered by the first heat exchange coil on the outer wall of the mixer and heated to form the first heat transfer medium inside. Step 2, Steel Mold Preheating: The first heat transfer fluid is sent into the first heat exchange pipeline in the phase change heat storage interlayer of the outer wall of the pole steel mold to heat the phase change heat storage material inside to above the phase change temperature to store latent heat, and the steel mold wall is preheated simultaneously; the phase change heat storage interlayer is located between the outer wall of the steel mold and the external insulation layer, and is arranged continuously along the axial and circumferential directions. Step 3, Reinforcing steel cage installation and placement: Place the precast reinforcing steel cage into the preheated steel mold, feed in the concrete mixture, place the concrete, and close the mold; Step 4, Centrifugal molding: The steel mold after molding is placed in a centrifuge and rotated to make the concrete compacted. During the centrifugation process, the frictional heat of the steel mold and the hydration heat of the concrete are absorbed and stored by the phase change heat storage material. After centrifugation, a molded electric rod is obtained. Step 5, Steam curing: Transfer the electric rod with mold into the curing kiln and steam curing. When the kiln temperature is lower than the phase change temperature, the phase change heat storage material releases latent heat, which is transferred to the steel mold wall through the inner wall of the phase change heat storage jacket to assist in heat preservation curing and reduce temperature stress cracks in the concrete. Step 6, Waste heat recovery: Collect the waste heat steam discharged from the curing kiln, pass it into the second heat exchange coil outside the kiln to heat the second heat exchange medium inside to form a second heat transfer fluid, and send the second heat transfer fluid into the second heat exchange pipeline of the phase change heat storage jacket to supplement heat storage, or send it into the first heat exchange coil of the next batch of poles as a preheating heat source. Step 7: Demolding: After curing, remove the steel mold and demold to obtain the finished concrete pole for power distribution.
2. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The phase change temperature of the phase change heat storage material in step two is 45℃~60℃. The phase change heat storage material is an inorganic hydrated salt phase change material or a paraffin-based organic phase change material. The filling volume ratio of the phase change heat storage material in the phase change heat storage interlayer is 75%~90% of the internal volume of the phase change heat storage interlayer.
3. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The external insulation layer mentioned in step two is a rock wool insulation layer or a polyurethane foam insulation layer. The thickness of the external insulation layer is 20mm to 50mm. The external insulation layer is covered and fixed to the outer wall of the phase change heat storage interlayer by adhesive bonding or mechanical fastening. The external insulation layer is segmented along the axial direction of the pole steel mold, and a sealing strip is provided at the splice seam between adjacent segments.
4. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The centrifugation process described in step four includes a slow spreading stage, a medium-speed transition stage, and a high-speed compaction stage. The rotation speed of the slow spreading stage is 100 r / min to 200 r / min, and the duration is 1 min to 3 min. The rotation speed of the medium-speed transition stage is 300 r / min to 500 r / min, and the duration is 2 min to 5 min. The rotation speed of the high-speed compaction stage is 600 r / min to 900 r / min, and the duration is 3 min to 8 min.
5. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, In step two, the first heat exchange pipeline and in step six, the second heat exchange pipeline are arranged in a spiral or serpentine coil shape within the phase change heat storage jacket. The first heat exchange pipeline and the second heat exchange pipeline are stacked radially along the pole steel mold or arranged alternately circumferentially along the pole steel mold. The first heat exchange pipeline and the second heat exchange pipeline are independent of each other and are not connected to each other.
6. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The steam curing process in step five includes a heating stage, a constant temperature stage, and a cooling stage. The heating stage raises the temperature inside the curing kiln to 60℃-80℃ at a rate of 15℃ / h to 25℃ / h. The constant temperature stage maintains the temperature at 60℃-80℃ for 4-8 hours. The cooling stage lowers the temperature inside the curing kiln to room temperature at a rate of 10℃ / h to 20℃ / h. During both the constant temperature stage and the cooling stage, the phase change heat storage material continuously releases latent heat.
7. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The temperature of the waste heat steam in step six is 40℃~70℃, the second heat exchange medium is water or heat transfer oil, and when the second heat carrier fluid is transported to the second heat exchange pipeline to supplement the heat storage, the temperature of the second heat carrier fluid is at least 5℃ higher than the phase change temperature of the phase change heat storage material.
8. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, In step two, a thermally conductive silicone grease layer or a graphite thermally conductive pad is provided between the inner wall of the phase change heat storage jacket and the outer wall of the electric pole steel mold. The thickness of the thermally conductive silicone grease layer or the graphite thermally conductive pad is 0.5mm to 2mm.
9. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The phase change heat storage interlayer in step two is equipped with a pressure relief valve and a temperature sensor. When the temperature sensor detects that the temperature inside the phase change heat storage interlayer exceeds a preset safety threshold, the pressure relief valve automatically opens to release the internal pressure of the interlayer.
10. The low-energy centrifugal molding process for preparing power distribution concrete poles according to claim 1, characterized in that, The first heat exchange pipeline and the second heat exchange pipeline are respectively connected to a circulating pump and a flow regulating valve. The circulating pump provides the power for the circulation of the heat medium, and the flow regulating valve adjusts the flow rate of the heat medium according to the real-time temperature of the phase change heat storage material.