Concrete pole steam curing waste heat cascade recovery and recycling system

Abstract

The present application belongs to the technical field of concrete pole maintenance waste heat recovery, and provides a concrete pole steam maintenance waste heat gradient recovery and recycling system, which comprises: by real-time monitoring of the temperature field distribution and pipeline temperature data in the maintenance pit and the pole body, calculating and identifying the preheating, constant temperature maintenance and cooling end three process stages, according to the waste heat recovery pipeline temperature data, dividing the recovered waste heat into high, medium and low grades, and using the partition wall heat exchange, uniform temperature and pressure heat exchange and heat pump upgrading conversion technology, storing into the corresponding heat storage unit, forming the cache heat source library, calling the cumulative heat storage and sustainable supply time of each grade heat source in the cache heat source library, carrying out grade matching and supply and demand verification, and according to the priority principle, coordinating the allocation, automatically generating the valve opening control instruction of the corresponding maintenance pit and issuing the actuator, realizing the automatic transportation and collaborative control of each grade heat source branch, and ensuring the stable control of the maintenance process temperature.

Description

Technical Field

[0001] This invention belongs to the field of waste heat recovery technology for concrete pole curing, specifically based on a cascade recovery and recycling system for waste heat from steam curing of concrete poles. Background Technology

[0002] The cascade recovery and recycling of waste heat from steam curing of concrete poles is essentially turning waste heat into resources. The heat from the steam and condensate that would otherwise be discharged after curing is used in stages for other stages of production, according to different temperature grades.

[0003] In actual production, steam curing of utility poles typically employs a multi-pile parallel operation method. Due to differences in mold placement time, pole specifications, and the number of molds installed, each pit is often at a different process stage—some pits are in the heating phase requiring significant additional heat, some are in the constant temperature phase requiring stability, and some have entered the cooling phase with residual heat that can be recovered. This multi-stage, parallel production organization mode results in a highly dynamic relationship between heat supply and demand in both time and space. However, existing waste heat recovery systems do not take this complex scenario of multiple operating conditions into account in their initial design. There is a lack of information sharing and unified scheduling mechanisms between the recovery side and the heat-consuming side. Each link relies on manual experience to judge the operating conditions and manually operate valves to complete steam distribution. It is impossible to synchronously track the real-time temperature changes and process progress of each pit, nor can it coordinate the heat supply and demand relationship between multiple sources and ends. As a result, at the same time, a large amount of waste heat in some curing pits in the cooling phase is discharged, while other curing pits in the heating phase are supplied with sufficient steam by external boilers. This serious mismatch between heat supply and demand leads to increased energy consumption and unstable temperature control. On the other hand, limited by a single heat recovery method, existing systems can usually only make simple use of the heat source in the high-temperature stage. As for the low-grade exhaust steam whose temperature gradually decreases during the cooling stage, it is directly discharged into the atmosphere due to the lack of recovery technology, which further aggravates the waste of heat energy.

[0004] Therefore, the present invention provides a cascade recovery and recycling system for waste heat from steam curing of concrete poles. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0006] The technical solution adopted by this invention to solve its technical problem is: a cascade recovery and recycling system for waste heat from steam curing of concrete poles, comprising the following modules:

[0007] Process Stage Determination Module: Real-time monitoring of temperature field distribution in the maintenance pit and on the pole body, temperature data of steam conveying and waste heat recovery pipelines, and calculation of temperature change rate and fitting temperature time sequence change curve to determine the process stage in the maintenance process.

[0008] The graded identification and analysis module uses temperature data collected from waste heat recovery pipelines to determine the heat energy grade of the currently recovered waste heat in real time. It then converts and stores waste heat of each grade according to its heat energy grade characteristics into the corresponding heat storage unit, forming a cached heat source library that can be directly accessed.

[0009] Supply and demand precise matching module: Based on the current process stage of each curing pit, identify the heat demand characteristics of each curing pit at the current stage, retrieve the available heat and sustainable supply duration of each grade of heat source in the cached heat source library, match each grade of heat source with the stage demand of each curing pit, and send the results to the system overall scheduling module.

[0010] System overall scheduling module: Based on the matching results of the supply and demand precision matching module, it automatically generates valve opening control commands for the corresponding maintenance pits and issues them to the actuators, realizing automatic distribution and coordinated control of heat source branches of various grades to the corresponding maintenance pits.

[0011] As a further aspect of the present invention: in the process stage determination module, the process of calculating the temperature change rate and fitting the temperature time-series change curve is as follows:

[0012] Collect the average temperature in the maintenance pit or the characteristic temperature of the pole body at the current moment, and the average temperature in the maintenance pit or the characteristic temperature of the pole body at the previous sampling moment; calculate the instantaneous temperature change rate and the stage average temperature change rate.

[0013] The temperature field of the maintenance pit and the temperature of the pole body are continuously sampled. Each time a sampling is completed, the corresponding time sequence and temperature are automatically bound to form a single set of time sequence data. The entire process covers the preheating, constant temperature maintenance and cooling and finishing conditions. All collected data are sorted and archived in chronological order, and finally a standard temperature time sequence dataset is generated.

[0014] Based on the collected standard temperature time series dataset, a polynomial fitting method was used to generate a temperature change characteristic curve for the entire maintenance process.

[0015] As a further aspect of the present invention: in the process stage determination module, the process of determining the process stage in the curing process is as follows:

[0016] The air temperature in the maintenance pit and the temperature of the pole body were collected. The instantaneous temperature change rate and the stage average temperature change rate were calculated respectively. At the same time, the temperature time series curve was fitted and the first derivative value at each sampling point was solved.

[0017] If both the instantaneous temperature change rate and the stage average temperature change rate are positive, and the stage average temperature change rate is within the range of the process standard heating rate, and the first derivative of the fitted curve at each sampling point is positive and there are no sampling points with a first derivative of zero or negative, then it is determined to be the preheating stage.

[0018] If the instantaneous temperature change rate and the stage average temperature change rate are both within the dead zone threshold range preset by the system, the first derivative of the fitting curve at each sampling point does not exceed the dead zone boundary, and all measured temperature values ​​are within the range defined by the upper and lower limits of the process constant temperature target value, then it is determined to be the constant temperature curing stage.

[0019] If both the instantaneous temperature change rate and the stage average temperature change rate are negative, the first derivative of the fitted curve at each sampling point is negative and there are no sampling points with a zero or positive first derivative, and the difference between the current temperature and the ambient temperature has reached the cooling termination judgment condition specified in the process procedure, then it is determined to be the cooling end stage.

[0020] As a further aspect of the present invention: the waste steam classification and analysis module determines the heat energy grade of the current waste heat recovery process in real time as follows:

[0021] Using a single curing pit as an independent monitoring unit, retrieve data on the rate of temperature change, the amplitude of temperature fluctuation, the trend of temperature time curve, the stability of the curve, and the inflection point of the process condition for each curing pit, distinguish the conditions of heating up to generate heat, constant temperature to generate heat, and cooling down to dissipate heat, and complete the qualitative screening of the source of waste heat.

[0022] The curing pit is in a constant temperature curing stage and is identified as high-grade waste heat.

[0023] The maintenance pit is in the preheating and heating stage, and is determined to be medium-grade waste heat.

[0024] The maintenance pit is in the final stage of cooling down and is classified as low-grade waste heat.

[0025] As a further aspect of the present invention, the process of forming a cache hotspot library that can be directly called is as follows:

[0026] After the waste heat energy grade is determined, the corresponding standardized thermal energy conversion technology and thermal storage carrier are matched to complete the differentiated energy conversion, energy level adaptation and graded thermal storage.

[0027] For high-grade waste heat, an efficient indirect heat exchange conversion method is adopted to complete the high-temperature preheating energy replacement. The high-temperature heat energy after heat exchange is stored in the high-temperature phase change heat storage area in the form of hot water energy storage.

[0028] For medium-grade waste heat, temperature fluctuation deviations are weakened by uniform temperature and pressure stabilization heat exchange, and the heat output energy level is unified. The heat is stored in the medium-temperature phase change heat storage area in the form of warm water energy storage.

[0029] For low-grade waste heat, heat pump upgrading and polymerization conversion technology is used to upgrade and collect scattered low-temperature residual waste heat, and store it in the form of low-temperature water storage and heat storage area.

[0030] As a further aspect of the present invention: in the precise supply and demand matching module, the process of identifying the heat demand characteristics of each maintenance pit at the current stage is as follows:

[0031] Obtain the current technological stage of each maintenance pit, the corresponding technological target parameters, and the current average temperature inside the maintenance pit and the characteristic temperature of the pole itself. For different stages, calculate the deviation between the actual temperature and the target temperature of each maintenance pit. Based on the deviation between the actual temperature and the target temperature, generate the heat demand characteristics for different stages, including:

[0032] Current demand types: heating demand, constant temperature demand, and cooling demand;

[0033] Heating intensity requirement: Based on the current demand type, the difference between the temperature change rate and the actual temperature change rate, and combined with inherent parameters such as the volume of the maintenance pit, the mass of the pole, and the heat capacity, determine the current required heating power.

[0034] Temperature target range: The temperature range that is expected to be maintained or reached at the current stage;

[0035] Duration characteristics: Based on the comparison between the current stage's running time and the total planned duration of the current stage, determine the remaining heating duration required and whether the demand needs to be replenished quickly in a short period or stably in a long period.

[0036] As a further aspect of the present invention: the process of calculating the available heat and sustainable supply duration of each grade of heat source in the buffer heat source library is as follows:

[0037] Based on the real-time temperature and pressure of the exhaust steam, the specific enthalpy of the exhaust steam is obtained by looking up the steam thermophysical property parameter table. Based on the collected return water temperature, the specific enthalpy of saturated water at the return water temperature is obtained.

[0038] Multiply the instantaneous mass flow rate of the exhaust steam by the specific enthalpy of the exhaust steam, and then subtract the difference between the corresponding specific enthalpy of the return water to obtain the instantaneous heating power.

[0039] Multiply the instantaneous heating power calculated at the current moment by the sampling period duration to obtain the newly added heat storage in this period;

[0040] The cumulative heat storage at the current moment is obtained by adding the newly added heat storage in this cycle to the cumulative heat storage at the previous moment, and then subtracting the heat consumed by the heat source coordination and execution module in this cycle.

[0041] Divide the cumulative heat storage in the thermal storage unit by the instantaneous heating power to obtain the duration of sustainable supply.

[0042] As a further aspect of the present invention, the process of obtaining the cumulative heat storage and the heat consumed by the heat source overall scheduling and execution module during the current cycle is as follows:

[0043] Obtain the internal temperature of the thermal storage unit and the ambient temperature, and calculate the difference between the internal temperature of the thermal storage unit and the ambient temperature;

[0044] Divide the difference between the internal temperature of the thermal storage unit and the ambient temperature by the total thermal resistance of the thermal storage unit wall and insulation layer to obtain the heat loss power per unit time.

[0045] Multiply the heat loss power by the sampling period duration to obtain the heat loss in this period;

[0046] The heat loss is deducted from the cumulative heat storage to obtain the cumulative heat storage at the current moment after deducting the heat loss.

[0047] As a further aspect of the present invention: the process of matching heat sources of different grades with the needs of each curing pit stage is as follows:

[0048] Obtain the current heat demand characteristics of each maintenance pit and the available information of each grade of heat source in the cached heat source library. Based on the heating demand level of the maintenance pit, initially screen the available heat source grades. If the demand is high-power heating, prioritize matching high-grade waste heat. If the demand is medium-power heating, prioritize matching medium-grade waste heat. If the demand is low-power or only requires intermittent supplementary heating, match low-grade waste heat. If the demand is no heating required, no heat source is allocated in this round.

[0049] The available heat and duration of the heat source obtained from the initial screening are compared with the needs of the maintenance pit.

[0050] As a further aspect of the present invention: in the system overall scheduling module, the process of automatically distributing heat source branches of each grade to the corresponding curing pits is as follows:

[0051] Based on the matching results of the supply and demand precise matching module, the target heat source grade, corresponding maintenance pit, required heat power, target temperature, and duration are obtained. The corresponding steam supply branch regulating valve equipment number is retrieved from the equipment ledger. The required heat power is divided by the rated heating capacity of the corresponding branch to obtain the valve opening percentage set value.

[0052] Using the current time as the starting point and the duration as the execution duration, a distribution scheduling instruction is generated, packaged into a control instruction frame according to a unified data structure, and sent to the field actuator controller of the corresponding maintenance pit via industrial Ethernet or fieldbus protocol. The actuator controller adjusts the valve position according to the received instruction.

[0053] The beneficial effects of this invention are as follows: By using a process stage determination module to monitor the rate of temperature field change and the time-series curve of temperature change characteristics in real time, the invention automatically identifies each stage of the curing process, including preheating, constant temperature curing, and cooling. Combined with the closed-loop linkage of the supply and demand precise matching wear and tear and system overall scheduling modules, the invention effectively solves the problems of low automation, lack of unified scheduling and coordination in each link, poor heat supply and demand matching, and unstable temperature control. At the same time, the waste heat is classified into high, medium, and low grades by the exhaust steam classification and analysis module and stored in the corresponding heat storage units to form a buffer heat source library that can be directly called. Based on this, according to the actual temperature deviation and heating power level of each curing pit, the invention prioritizes matching the corresponding grade heat source and verifies the available heat and sustainable supply duration. Finally, the system overall scheduling module automatically generates valve opening commands and sends them to the actuators to realize the automatic distribution and coordinated control of each grade heat source branch to the corresponding curing pit. This achieves the overall effect of full-grade waste heat cascade utilization, significantly improved energy utilization rate, and stable process operation. Attached Figure Description

[0054] The invention will now be further described with reference to the accompanying drawings.

[0055] Figure 1 This is a flowchart of a system for the cascaded recovery and recycling of waste heat from steam curing of concrete poles, as described in an embodiment of the present invention.

[0056] Figure 2 This is a flowchart illustrating the implementation steps of a waste heat cascade recovery and recycling system for steam curing of concrete poles, as described in an embodiment of the present invention.

[0057] Figure 3 This is a reference example diagram of the fitted temperature time series change curve in a cascade recovery and recycling system for waste heat from steam curing of concrete poles, as described in an embodiment of the present invention. Detailed Implementation

[0058] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0059] Example: Please refer to Figure 1-3 As shown in the embodiment of the present invention, a cascaded recovery and recycling system for waste heat from steam curing of concrete poles includes the following modules:

[0060] Process Stage Determination Module: Real-time monitoring of temperature field distribution in the maintenance pit and on the pole body, as well as temperature data of steam transport and waste heat recovery pipelines. By calculating the rate of temperature change and fitting the temperature time-series change curve, the module determines the process stage in the maintenance process.

[0061] In the process stage judgment module, real-time monitoring of the temperature field distribution within the curing pit and on the pole body, as well as the temperature data of the steam transport and waste heat recovery pipelines, is achieved by deploying sensors within the curing pit.

[0062] The sensors are deployed in a multi-layered distributed scheme within the maintenance pit, as detailed below:

[0063] Vertical stratification: The pit is divided into three layers along its depth: upper, middle, and lower. The upper layer is about 0.3m from the top of the pit, the middle layer is at half the depth of the pit, and the lower layer is about 0.3m from the bottom of the pit.

[0064] Horizontal distribution: One measuring point is arranged at each of the four corners and the center of each layer, that is, five measuring points per layer, and a total of fifteen measuring points for three layers. Among them, the measuring points at the four corners are used to capture the temperature boundary effect near the pit wall, and the measuring point at the center reflects the temperature level of the mainstream area inside the pit.

[0065] Temperature measurement of the pole body: Measurement points are evenly arranged along the length of the inner wall of the pole mold. Five measurement points are arranged at 1m from each end, 1 / 4 of the distance from each end, and the midpoint, respectively, to obtain the true temperature of different parts of the pole body.

[0066] Sensors were deployed on the main steam pipe, the steam branch pipes of each maintenance pit, the main waste heat recovery pipe, and each branch pipe, as follows:

[0067] Temperature sensors are deployed on the straight sections of each pipeline, and the installation is described above to ensure that the temperature probe is inserted into the center line of the pipeline to obtain the true temperature of the residual steam heat inside the pipeline.

[0068] It should be noted that all sensors inside the pit are stainless steel armored protective types with a protection rating of no less than IP67 to meet the long-term operational requirements of the high-temperature (up to 150℃), high-humidity (relative humidity above 95%), and weakly alkaline steam environment inside the pit. A porous metal protective cover is installed on the outside of the sensor probe to prevent condensate dripping from directly impacting the probe and causing measurement fluctuations. Pipeline temperature sensors use armored resistance thermometers or thermocouples with stainless steel probes, suitable for steam temperatures up to 200℃ inside the pipeline.

[0069] In the process stage determination module, the process of calculating the temperature change rate and fitting the temperature time series change curve is as follows:

[0070] Calculate the rate of temperature change:

[0071] Determine the sampling time interval (the system has a fixed sampling period, in seconds, preferably set to 1-5 seconds), subtract the temperature at the previous sampling time from the temperature at the current sampling time, and then divide by the sampling time interval to obtain the current instantaneous temperature change rate.

[0072] Subtract the stage start temperature from the stage end temperature, and then divide by the stage statistical duration to obtain the stage average temperature change rate.

[0073] It should be noted that a positive instantaneous rate of temperature change represents a temperature increase, a negative rate represents a temperature decrease, and zero represents a constant temperature.

[0074] Fitting the temperature time-series change curve:

[0075] B1, Sampling time interval: (The system has a fixed sampling period, in seconds).

[0076] B2, sampling time sequence: (The recording time of the i-th accurate sampling of the system is incremented sequentially according to the fixed sampling interval).

[0077] B3, corresponding temperature at that moment: (The average temperature of the maintenance pit and the characteristic temperature of the pole body at the corresponding time).

[0078] B4, Stage Statistics Duration: (Statistical period for a single process stage, unit: seconds, used to collect all continuous time-series sampling data within a single stage);

[0079] The complete data collection and generation process is as follows: the system starts timing from the moment the maintenance process begins, at fixed time intervals. The temperature field of the maintenance pit and the temperature of the pole body are continuously sampled without interruption. Each time a sampling is completed, it is automatically bound (time-corresponding temperature) to form a single set of time-series data. The entire process covers the preheating, constant temperature maintenance and cooling and finishing conditions. All collected data are automatically sorted and archived in chronological order, and finally a continuous, equally spaced, and highly regular standard temperature time-series dataset is generated.

[0080] Fitting method: Based on the collected real time-series dataset, a multinomial fitting algorithm is used to generate the temperature change characteristic curve of the entire maintenance process. See the example for the fitted temperature time-series change curve. Figure 3 The fitting formula is as follows:

[0081]

[0082] in, The fitted temperature value at time t; The curve fitting coefficients are adaptively solved based on real-time temperature data. Three core features can be extracted from the curve: curve slope (temperature change rate trend), curve inflection point (temperature change rate abrupt change node), and curve stability (constant temperature stability).

[0083] The process of determining the technological stage in the maintenance process is as follows:

[0084] The air temperature in the maintenance pit and the temperature of the pole body were collected. The instantaneous temperature change rate and the stage average temperature change rate were calculated respectively. At the same time, the temperature time series curve was fitted and the first derivative value at each sampling point was solved.

[0085] If both the instantaneous temperature change rate and the stage average temperature change rate are positive, and the stage average temperature change rate is within the range of the process standard heating rate, and the first derivative of the fitted curve at each sampling point is positive and there are no sampling points with a first derivative of zero or negative, then it is determined to be the preheating stage.

[0086] If the instantaneous temperature change rate and the stage average temperature change rate are both within the dead zone threshold range preset by the system, the first derivative of the fitting curve at each sampling point does not exceed the dead zone boundary, and all measured temperature values ​​are within the range defined by the upper and lower limits of the process constant temperature target value, then it is determined to be the constant temperature curing stage.

[0087] If both the instantaneous temperature change rate and the stage average temperature change rate are negative, the first derivative of the fitted curve at each sampling point is negative and there are no sampling points with a first derivative of zero or positive value, and the difference between the current temperature and the ambient temperature has reached the cooling termination judgment condition specified in the process procedure, then it is judged to be the cooling end stage.

[0088] It should be noted that the process standard heating rate range for steam curing concrete poles is a fixed process parameter.

[0089] The system's preset dead zone threshold is a statistical value of the inherent temperature fluctuation range during the constant temperature curing stage, that is, the range of natural temperature fluctuations in the curing pit caused by factors such as the opening and closing of steam valves, steam pressure fluctuations, and environmental heat dissipation during the constant temperature maintenance period.

[0090] The criteria for determining the termination of cooling are derived from the definition of the end point of the cooling final stage in the curing process specifications. The specific criteria include the following two:

[0091] Temperature threshold determination: When the temperature difference between the air temperature in the maintenance pit or the temperature of the pole body and the ambient temperature decreases to below the set value (e.g., 3℃), the cooling process is considered to be over.

[0092] Time threshold determination: Timing starts from the cooling stage and ends when the cooling duration reaches the specified process value;

[0093] Waste heat recovery classification and analysis module: Based on the temperature data collected by the waste heat recovery pipeline, the module determines the heat energy grade of the currently recovered waste heat in real time, converts waste heat of each grade according to its heat energy grade characteristics and stores it in the corresponding heat storage unit, forming a cached heat source library that can be directly called.

[0094] In the waste steam classification and identification analysis module, the process of determining the heat energy grade of the currently recovered waste heat in real time is as follows:

[0095] The real-time operating data was analyzed using a calculation model of the temperature change rate in a single maintenance pit and a temperature time-series curve fitting model. Combined with time-series temperature sampling data from the waste heat recovery pipeline, the waste heat energy grade was classified and determined. Specifically:

[0096] Using a single curing pit as an independent monitoring unit, retrieve data on the rate of temperature change, the amplitude of temperature fluctuation, the trend of temperature time curve, the stability of the curve, and the inflection point of the process condition for each curing pit, distinguish the conditions of heating up to generate heat, constant temperature to generate heat, and cooling down to dissipate heat, and complete the qualitative screening of the source of waste heat.

[0097] The curing pit is in a constant temperature curing stage, and the rate of temperature change is close to zero. The temperature of the waste heat recovery pipeline remains unchanged over time, which is determined to be high-grade waste heat.

[0098] The maintenance pit is in the preheating and heating stage, the temperature change rate is continuously positive, and the temperature time curve shows an increasing change, which is determined to be medium-grade waste heat.

[0099] The maintenance pit is in the final stage of cooling down. The temperature change rate is continuously negative and the temperature time series curve shows a decreasing change, which is determined to be low-grade waste heat.

[0100] In the waste steam classification and identification analysis module, the process of converting and storing waste heat of different grades according to their thermal energy grade characteristics into corresponding thermal storage units to form a cached heat source library that can be directly accessed is as follows:

[0101] After determining the waste heat energy grade, based on the temperature characteristics of high, medium, and low waste heat grades, and following the principle of gradient utilization of industrial waste heat, corresponding standardized thermal energy conversion technologies and thermal storage carriers are matched to complete differentiated energy conversion, energy level adaptation, and graded thermal storage. The specific execution process is as follows:

[0102] For high-grade waste heat, based on the characteristic that the temperature of the waste heat recovery pipeline remains constant over time, an efficient indirect heat exchange conversion method is adopted, using water circulation as the heat exchange medium to directly complete the high-temperature preheating energy replacement without the need for temperature quality improvement pretreatment. The high-temperature thermal energy after heat exchange is stored in the high-temperature phase change heat storage area in the form of hot water energy storage.

[0103] The high-efficiency indirect heat exchange conversion method is mainly: using a high-efficiency indirect heat exchanger to transfer the heat of one fluid (heat source) to another fluid (heat medium), thereby completing the transfer and quality improvement of heat energy and realizing the conversion and utilization process.

[0104] For medium-grade waste heat, based on the characteristic that the temperature of the waste heat recovery pipeline increases over time, the temperature fluctuation deviation is weakened by uniform temperature and pressure stabilization heat exchange, the heat output energy level is unified, and after the energy homogenization conversion is completed, it is stored in the medium-temperature phase change heat storage area in the form of warm water energy storage.

[0105] The main purpose of uniform temperature and stable pressure heat exchange regulation is to reduce adverse effects such as flow resistance by regulating fluid flow, and ultimately achieve the goal of uniform temperature and stable pressure operation.

[0106] For low-grade waste heat, based on the characteristic that the temperature of the waste heat recovery pipeline decreases over time, heat pump upgrading and polymerization conversion technology is adopted to upgrade and collect scattered low-temperature residual waste heat, complete the upgrading and conversion of low-quality heat energy, and store the upgraded heat energy in the form of low-temperature energy storage in the low-temperature water storage heat storage area.

[0107] The heat pump upgrading and polymerization conversion technology mainly involves: polymerizing dispersed heat sources, and then using heat pump technology to upgrade and convert them, ultimately achieving efficient and large-scale utilization of low-grade heat energy.

[0108] Supply and demand precise matching module: Based on the current process stage of each curing pit, identify the heat demand characteristics of each curing pit at the current stage, retrieve the available heat and sustainable supply duration of each grade of heat source in the cached heat source library, match each grade of heat source with the stage demand of each curing pit, and send the results to the system overall scheduling module.

[0109] In the precise supply and demand matching module, the process of identifying the heat demand characteristics of each curing pit at its current stage, based on the current technological stage of each curing pit, is as follows:

[0110] Obtain the current process stage, corresponding process target parameters, average temperature in the maintenance pit, and characteristic temperature of the pole body at the current moment for each maintenance pit;

[0111] The target parameters for the process are derived from the curing process specifications, including:

[0112] The target heating rate range during the preheating stage (e.g., 0.02–0.05°C per second) and the final target constant temperature value to be achieved;

[0113] The target temperature range and allowable fluctuation range during the constant temperature curing stage;

[0114] The upper limit of the allowable cooling rate during the final stage of cooling (usually a negative value, indicating slow cooling), and the termination conditions for finally approaching the ambient temperature;

[0115] For different stages, calculate the deviation between the actual temperature and the target temperature in each curing pit:

[0116] Preheating stage: Calculate the difference between the current temperature and the target constant temperature. The larger the difference, the more heat needs to be added. At the same time, calculate the actual heating rate and the standard heating rate. If the actual heating rate is lower than the standard heating rate, it means that the current heating is insufficient.

[0117] Constant temperature curing stage: Calculate the deviation of the current temperature from the target constant temperature value, and monitor the temperature fluctuation range at the same time. If the temperature shows a downward trend or the fluctuation range is large, it means that heat needs to be added to maintain stability.

[0118] Final cooling phase: Calculate the current actual cooling rate. If the actual cooling rate exceeds the allowable upper limit, a small amount of heat needs to be introduced to gradually cool down.

[0119] Generate heat demand characteristics at different stages, including:

[0120] Current demand types: heating demand, constant temperature demand, and cooling demand;

[0121] Heating intensity requirement: Based on the current demand type, the difference between the temperature change rate and the actual temperature change rate, and combined with inherent parameters such as the volume of the maintenance pit, the mass of the pole, and the heat capacity, determine the current required heating power.

[0122] Temperature target range: The temperature range that is expected to be maintained or reached at the current stage;

[0123] Duration characteristics: Based on the comparison between the current stage's running time and the total planned duration of the current stage, determine the remaining heating duration required and whether the demand needs to be replenished quickly in a short period or stably in a long period.

[0124] It should be noted that the volume of the curing pit is directly calculated from the actual drawings of the curing pit or by measuring the length, width, and height of the pit on site.

[0125] The mass of a utility pole can be calculated from the product specification sheet or by volume and density: Pole mass = Pole concrete volume × Concrete density;

[0126] The heat capacity of the pole is determined by the product of the pole's mass and the concrete's specific heat capacity. The specific heat capacity of concrete can be found in the table of thermophysical properties of building materials.

[0127] Heat capacity calculation: Pole heat capacity = Pole mass × concrete specific heat capacity;

[0128] In the precise matching module for heat energy supply and demand, the process of calculating the available heat and sustainable supply duration of each grade of heat source in the buffered heat source library is as follows:

[0129] Flow meters and pressure sensors are deployed on the waste heat recovery branch pipes to collect the mass flow rate and real-time pressure of the exhaust steam flowing through the pipes in real time. Waste heat recovery pipes of different grades are independent of each other, and the instantaneous mass flow rate corresponding to high-grade waste heat, medium-grade waste heat and low-grade waste heat is obtained respectively.

[0130] Temperature sensors are deployed on the return water pipes of each thermal storage unit to collect the temperature of the medium returning to the thermal storage unit in real time.

[0131] Temperature sensors are deployed on the internal walls of each thermal storage unit to collect the average temperature of the heat source inside the thermal storage unit in real time.

[0132] Deploy ambient temperature sensors in areas near the thermal storage unit that are not directly affected by the heat dissipation of the equipment to collect the ambient temperature around the thermal storage unit in real time.

[0133] Based on the real-time temperature and pressure of the exhaust steam, the specific enthalpy of the exhaust steam is calculated by looking up the steam thermal property parameter table. When the collected exhaust steam temperature and pressure values ​​fall between the points in the steam thermal property parameter table, the specific enthalpy of the exhaust steam is calculated using the bilinear interpolation method.

[0134] Based on the collected return water temperature, the specific enthalpy value of saturated water at the return water temperature is retrieved from the saturated hydrothermal property data subset;

[0135] It should be noted that the steam thermophysical property parameter table, also known as the water and steam thermodynamic property chart, is compiled according to the IAPWS-IF97 international standard. Among them, the specific enthalpy of the exhaust steam is obtained from the thermophysical property data subset of the steam superheated or saturated zone based on the real-time temperature and pressure of the exhaust steam. The specific enthalpy of the return water is obtained from the thermophysical property data subset of saturated water based on the return water temperature.

[0136] For example, refer to Table 1 below for charts illustrating the thermodynamic properties of water and water vapor;

[0137] Table 1: Reference Table of Thermodynamic Properties of Water and Water Vapor;

[0138]

[0139] The instantaneous heating power is obtained by multiplying the instantaneous mass flow rate of the exhaust steam by the difference between the exhaust steam specific enthalpy and the corresponding return water specific enthalpy.

[0140] Multiply the instantaneous heating power calculated at the current moment by the sampling period duration to obtain the newly added heat storage in this period;

[0141] Obtain the internal temperature of the thermal storage unit and the ambient temperature, and calculate the difference between the internal temperature of the thermal storage unit and the ambient temperature;

[0142] Divide the difference between the internal temperature of the thermal storage unit and the ambient temperature by the total thermal resistance of the thermal storage unit wall and insulation layer to obtain the heat loss power per unit time.

[0143] Multiply the heat loss power by the sampling period duration to obtain the heat loss in this period;

[0144] The heat loss is deducted from the cumulative heat storage to obtain the cumulative heat storage at the current moment after deducting the heat loss.

[0145] The cumulative heat storage at the current moment is obtained by adding the newly added heat storage in this cycle to the cumulative heat storage at the previous moment, and then subtracting the heat consumed by the heat source coordination and execution module in this cycle.

[0146] It should be noted that the initial cumulative heat storage capacity of each thermal storage unit is zero when the system starts up;

[0147] Divide the cumulative heat storage in the thermal storage unit by the instantaneous heating power to obtain the duration of sustainable supply;

[0148] In the precise supply and demand matching module, the process of matching heat sources of various grades with the needs of each maintenance pit stage is as follows:

[0149] Obtain the current heat demand characteristics of each maintenance pit, including:

[0150] Demand types: Heating demand, constant temperature maintenance demand, cooling control demand;

[0151] Required heating power level: High power, Medium power, Low power, No heating required;

[0152] Temperature target range: current temperature - target temperature;

[0153] Divide the effective cumulative heat storage of each grade of thermal storage unit by the instantaneous heating power for that grade to obtain the expected duration of continuous demand for that grade.

[0154] Obtain available information for each grade of heat source in the cached heat source library, including: the current cumulative heat storage of each grade of heat source, the instantaneous heating power of each grade of heat source, and the sustainable supply duration of each grade of heat.

[0155] Based on the heating demand level required by the maintenance pit, the available heat source grades are initially screened. If the demand is for high-power heating (such as during the preheating stage and the actual temperature rise is significantly delayed), high-grade waste heat is given priority.

[0156] If the demand is for medium-power heating (such as conventional heating or constant temperature maintenance), medium-grade waste heat should be matched first.

[0157] If the demand is low power or only requires intermittent supplemental heating (such as compensation for slight fluctuations during constant temperature), then low-grade waste heat should be matched.

[0158] If the demand is no heating required, no heat source will be allocated in this round;

[0159] The available heat and duration of the heat source obtained from the initial screening are compared with the requirements of the maintenance pit;

[0160] If the cumulative heat storage of the required grade of heat source is sufficient to support the pit to rise to the target temperature, and the sustainable supply duration is ≥ the remaining planned duration of the phase, then it is judged as a perfect match;

[0161] If the accumulated heat is sufficient but the duration of sustainability is insufficient, it is marked as requiring relay energy supply. That is, the current grade of heat source is used to supply the heat first, and then the heat source is switched to another grade or an external heat source is activated to compensate before it is exhausted.

[0162] If the accumulated heat is insufficient, it is determined that multiple sources of combined supply or external heat sources are needed to supplement it.

[0163] It should be noted that when multiple maintenance pits simultaneously make similar requests, they will be coordinated and allocated according to the priority principle. First, maintenance pits that are in the residual heat rising stage and have the largest temperature deviation will be given priority. Second, maintenance pits that show a clear cooling trend in the constant temperature stage will be given priority. Maintenance pits that are in the cooling end stage and have a normal cooling rate will be given the lowest priority.

[0164] System overall scheduling module: Based on the matching results of the supply and demand precision matching module, it automatically generates valve opening control commands for the corresponding maintenance pits and sends them to the actuators to realize automatic distribution and coordinated control of heat source branches of each grade to the corresponding maintenance pits;

[0165] In the system's overall scheduling module, the process of automatically distributing heat from each grade of heat source branch to the corresponding curing pit is as follows:

[0166] Based on the matching results of the supply and demand precise matching module, the target heat source grade, corresponding maintenance pit, required heat power, target temperature, and duration are obtained. The corresponding steam supply branch regulating valve equipment number is retrieved from the equipment ledger. The required heat power is divided by the rated heating capacity of the corresponding branch to obtain the valve opening percentage set value (limited to 0%-100%).

[0167] Using the current time as the starting point and the duration as the execution duration, a distribution scheduling instruction is generated, packaged into a control instruction frame according to a unified data structure, and sent to the field actuator controller of the corresponding maintenance pit via industrial Ethernet or fieldbus protocol. The actuator controller adjusts the valve position according to the received instruction.

[0168] 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 the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for the cascaded recovery and recycling of waste heat from steam curing of concrete utility poles, characterized in that: Includes the following modules: Process Stage Determination Module: Real-time monitoring of temperature field distribution in the maintenance pit and on the pole body, temperature data of steam conveying and waste heat recovery pipelines, and calculation of temperature change rate and fitting temperature time sequence change curve to determine the process stage in the maintenance process. The graded identification and analysis module uses temperature data collected from waste heat recovery pipelines to determine the heat energy grade of the currently recovered waste heat in real time. It then converts and stores waste heat of each grade according to its heat energy grade characteristics into the corresponding heat storage unit, forming a cached heat source library that can be directly accessed. Supply and demand precise matching module: Based on the current process stage of each curing pit, identify the heat demand characteristics of each curing pit at the current stage, retrieve the available heat and sustainable supply duration of each grade of heat source in the cached heat source library, match each grade of heat source with the stage demand of each curing pit, and send the results to the system overall scheduling module. System overall scheduling module: Based on the matching results of the supply and demand precision matching module, it automatically generates valve opening control commands for the corresponding maintenance pits and issues them to the actuators, realizing automatic distribution and coordinated control of heat source branches of various grades to the corresponding maintenance pits.

2. The system for cascade recovery and recycling of waste heat from steam curing of concrete poles according to claim 1, characterized in that: In the process stage determination module, the process of calculating the temperature change rate and fitting the temperature time series change curve is as follows: Collect the average temperature in the maintenance pit or the characteristic temperature of the pole body at the current moment, and the average temperature in the maintenance pit or the characteristic temperature of the pole body at the previous sampling moment; calculate the instantaneous temperature change rate and the stage average temperature change rate. The temperature field of the maintenance pit and the temperature of the pole body are continuously sampled. Each time a sampling is completed, the corresponding time sequence and temperature are automatically bound to form a single set of time sequence data. The entire process covers the preheating, constant temperature maintenance and cooling and finishing conditions. All collected data are sorted and archived in chronological order, and finally a standard temperature time sequence dataset is generated. Based on the collected standard temperature time series dataset, a polynomial fitting method was used to generate a temperature change characteristic curve for the entire maintenance process.

3. The system for cascaded recovery and recycling of waste heat from steam curing of concrete poles according to claim 2, characterized in that: In the process stage determination module, the process for determining the current process stage in the curing process is as follows: The air temperature in the maintenance pit and the temperature of the pole body were collected. The instantaneous temperature change rate and the stage average temperature change rate were calculated respectively. At the same time, the temperature time series curve was fitted and the first derivative value at each sampling point was solved. If both the instantaneous temperature change rate and the stage average temperature change rate are positive, and the stage average temperature change rate is within the range of the process standard heating rate, and the first derivative of the fitted curve at each sampling point is positive and there are no sampling points with a first derivative of zero or negative, then it is determined to be the preheating stage. If the instantaneous temperature change rate and the stage average temperature change rate are both within the dead zone threshold range preset by the system, the first derivative of the fitting curve at each sampling point does not exceed the dead zone boundary, and all measured temperature values ​​are within the range defined by the upper and lower limits of the process constant temperature target value, then it is determined to be the constant temperature curing stage. If both the instantaneous temperature change rate and the stage average temperature change rate are negative, the first derivative of the fitted curve at each sampling point is negative and there are no sampling points with a zero or positive first derivative, and the difference between the current temperature and the ambient temperature has reached the cooling termination judgment condition specified in the process procedure, then it is determined to be the cooling end stage.

4. The system for cascaded recovery and recycling of waste heat from steam curing of concrete poles according to claim 3, characterized in that: The waste steam classification and analysis module determines the heat energy grade of the current waste heat recovery process in real time as follows: Using a single curing pit as an independent monitoring unit, data on the rate of temperature change, the amplitude of temperature fluctuation, the trend of temperature time curve, the stability of the curve, and the inflection point of the process condition are retrieved for each curing pit. The conditions of heating and heat generation, constant temperature heat generation, and cooling and heat dissipation are distinguished to complete the qualitative screening of the source of waste heat. If the curing pit is in the constant temperature curing stage, it is determined to be high-grade waste heat. The curing pit is in the preheating and heating stage, and is determined to be medium-grade waste heat; the curing pit is in the cooling and finishing stage, and is determined to be low-grade waste heat.

5. A system for the cascaded recovery and recycling of waste heat from steam curing of concrete utility poles according to claim 4, characterized in that: The process of creating a cache hotspot library that can be directly called is as follows: After the waste heat energy grade is determined, the corresponding standardized thermal energy conversion technology and thermal storage carrier are matched to complete the differentiated energy conversion, energy level adaptation and graded thermal storage. For high-grade waste heat, an efficient indirect heat exchange conversion method is adopted to complete the high-temperature preheating energy replacement. The high-temperature heat energy after heat exchange is stored in the high-temperature phase change heat storage area in the form of hot water energy storage. For medium-grade waste heat, temperature fluctuation deviations are weakened by uniform temperature and pressure stabilization heat exchange, and the heat output energy level is unified. The heat is stored in the medium-temperature phase change heat storage area in the form of warm water energy storage. For low-grade waste heat, heat pump upgrading and polymerization conversion technology is used to upgrade and collect scattered low-temperature residual waste heat, and store it in the form of low-temperature water storage and heat storage area.

6. The system for cascaded recovery and recycling of waste heat from steam curing of concrete utility poles according to claim 3, characterized in that: In the precise supply and demand matching module, the process of identifying the heat demand characteristics of each maintenance pit at the current stage is as follows: The system obtains the current process stage of each maintenance pit, the corresponding process target parameters, the average temperature inside the maintenance pit at the current moment, and the characteristic temperature of the pole itself. For different stages, it calculates the deviation between the actual temperature and the target temperature of each maintenance pit. Based on the deviation between the actual temperature and the target temperature, it generates the heat demand characteristics of different stages, including: the current stage demand type, heating intensity demand, temperature target range, and duration characteristics.

7. A system for the cascaded recovery and recycling of waste heat from steam curing of concrete utility poles according to claim 6, characterized in that: The process of calculating the available heat and sustainable supply duration of each grade of heat source in the buffer heat source pool is as follows: Based on the real-time temperature and pressure of the exhaust steam, the specific enthalpy of the exhaust steam is obtained by looking up the steam thermophysical property parameter table. Based on the collected return water temperature, the specific enthalpy of saturated water at the return water temperature is obtained. Multiply the instantaneous mass flow rate of the exhaust steam by the specific enthalpy of the exhaust steam, and then subtract the difference between the corresponding specific enthalpy of the return water to obtain the instantaneous heating power. Multiply the instantaneous heating power calculated at the current moment by the sampling period duration to obtain the newly added heat storage in this period; The cumulative heat storage at the current moment is obtained by adding the newly added heat storage in this cycle to the cumulative heat storage at the previous moment, and then subtracting the heat consumed by the heat source coordination and execution module in this cycle. Divide the cumulative heat storage in the thermal storage unit by the instantaneous heating power to obtain the duration of sustainable supply.

8. A system for the cascaded recovery and recycling of waste heat from steam curing of concrete utility poles according to claim 7, characterized in that: The process of obtaining the cumulative heat storage and the heat consumed by the heat source overall scheduling and execution module during this cycle is as follows: Obtain the internal temperature of the thermal storage unit and the ambient temperature, and calculate the difference between the internal temperature of the thermal storage unit and the ambient temperature; Divide the difference between the internal temperature of the thermal storage unit and the ambient temperature by the total thermal resistance of the thermal storage unit wall and insulation layer to obtain the heat loss power per unit time. Multiply the heat loss power by the sampling period duration to obtain the heat loss in this period; The heat loss is deducted from the cumulative heat storage to obtain the cumulative heat storage at the current moment after deducting the heat loss.

9. A system for the cascaded recovery and recycling of waste heat from steam curing of concrete utility poles according to claim 7, characterized in that: The process of matching heat sources of different grades with the needs of each maintenance pit stage is as follows: Obtain the current heat demand characteristics of each maintenance pit and the available information of each grade of heat source in the cached heat source library. Based on the heating demand level of the maintenance pit, initially screen the available heat source grades. If the demand is high-power heating, prioritize matching high-grade waste heat. If the demand is medium-power heating, prioritize matching medium-grade waste heat. If the demand is low-power or only requires intermittent supplementary heating, match low-grade waste heat. If the demand is no heating required, no heat source is allocated in this round. The available heat and duration of the heat source obtained from the initial screening are compared with the needs of the maintenance pit.

10. A system for the cascaded recovery and recycling of waste heat from steam curing of concrete utility poles according to claim 9, characterized in that: In the system's overall scheduling module, the process of automatically distributing heat from each grade of heat source branch to the corresponding curing pit is as follows: Based on the matching results of the supply and demand precise matching module, the target heat source grade, corresponding maintenance pit, required heat power, target temperature, and duration are obtained. The corresponding steam supply branch regulating valve equipment number is retrieved from the equipment ledger. The required heat power is divided by the rated heating capacity of the corresponding branch to obtain the valve opening percentage set value. Using the current time as the starting point and the duration as the execution duration, a distribution scheduling instruction is generated, packaged into a control instruction frame according to a unified data structure, and sent to the field actuator controller of the corresponding maintenance pit via industrial Ethernet or fieldbus protocol. The actuator controller adjusts the valve position according to the received instruction.

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