A casting constant temperature and humidity control method and system based on roasting furnace waste heat recovery

Abstract

The present invention discloses a casting constant temperature and humidity control method and system based on roasting furnace waste heat recovery, which relates to the field of waste heat recovery and utilization technology. The method comprises: collecting high-temperature exhaust gas discharged from the roasting furnace, transporting the high-temperature exhaust gas to the lithium bromide unit through a high-temperature exhaust gas delivery pipeline, providing an electric regulating valve at the outlet end of the electric regulating valve connected to a bypass channel, controlling the opening of the electric regulating valve according to the operating state of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit, and the lithium bromide unit performs heat exchange on the high-temperature exhaust gas; and transporting chilled water to the constant temperature and humidity unit through a circulating water pump to control the temperature and humidity of the shell making drying area. By establishing a selective waste gas diversion mechanism, a closed-loop cooling circulation system, and a precise temperature and humidity control system, the present invention realizes efficient utilization of the roasting furnace waste heat and precise control of the shell making process environment, achieving the dual effects of energy conservation and emission reduction and process quality control.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery and utilization, and in particular to a casting constant temperature and humidity control method and system based on waste heat recovery from a roasting furnace. Background Art

[0002] In the precision casting process, the shell-making process is a critical step affecting casting quality. Traditional shell-making requires a surface temperature of 20-26°C, a relative humidity of 60-70%, and a backing temperature of 20-27°C, with a relative humidity of 40-60%. This stringent temperature and humidity control requires 24-hour operation. Currently, the precision casting industry generally uses regenerative chamber roasting furnaces for shell mold roasting. The high-temperature exhaust gases (400-600°C) generated by these furnaces are typically directly discharged or used only for simple hot water heat exchange. However, due to the lack of effective exhaust gas control mechanisms and heat allocation systems, the thermal energy of these high-temperature exhaust gases cannot be fully utilized. Furthermore, the shell-making workshop uses traditional compressor air conditioners and constant temperature dehumidification units to maintain a constant temperature and humidity environment. This approach not only consumes a lot of energy but also makes it difficult to achieve precise temperature and humidity control.

[0003] In the field of industrial waste heat recovery and utilization, lithium bromide absorption refrigeration technology has been widely used to recover waste heat from various types of high-temperature exhaust gases. In the ceramic industry, roasting furnace exhaust is usually used for air preheating or hot water heat exchange, while lithium bromide units are mainly used in conventional refrigeration situations in other industries. In the existing technology, although there are solutions for using lithium bromide units for waste heat recovery, there is a lack of waste gas allocation mechanism based on the system operating status, and the stable operation of the refrigeration system cannot be guaranteed. In addition, the existing constant temperature and humidity control system often adopts a single temperature and humidity feedback control, which is difficult to adapt to the strict requirements of the shell making process on environmental parameters.

[0004] Therefore, there are three main problems with the existing technology: first, there is a lack of an intelligent allocation mechanism for roasting furnace exhaust gas, resulting in low efficiency in waste heat utilization; second, the lithium bromide refrigeration system and the cooling cycle have poor synergy, affecting system stability; third, the temperature and humidity control accuracy is insufficient, making it difficult to meet the shell making process requirements. Summary of the Invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the present invention provides a casting constant temperature and humidity control method and system based on roasting furnace waste heat recovery, which can solve the problems mentioned in the background technology.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: a casting constant temperature and humidity control method based on roasting furnace waste heat recovery, comprising: collecting high-temperature exhaust gas discharged from the roasting furnace, and delivering the high-temperature exhaust gas to the lithium bromide unit through a high-temperature exhaust gas delivery pipeline; the high-temperature exhaust gas delivery pipeline is provided with an electric regulating valve, the outlet end of the electric regulating valve is connected to a bypass channel, and the opening of the electric regulating valve is controlled according to the circulating flow rate of the working medium of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit;

[0008] The lithium bromide unit performs heat exchange on the high-temperature exhaust gas, and the lithium bromide unit and the cooling tower form a cooling water circulation system to produce chilled water;

[0009] The chilled water is delivered to the constant temperature and humidity unit through a circulating water pump, and the temperature and humidity of the shell making and drying area are controlled by the constant temperature and humidity unit.

[0010] As a preferred embodiment of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to the present invention, the lithium bromide unit includes a generator, a condenser, an evaporator, and an absorber connected in sequence, and the high-temperature exhaust gas enters the generator through the high-temperature exhaust gas conveying pipeline for heat exchange;

[0011] The high-temperature exhaust gas delivery pipeline is also provided with a high-temperature induced draft fan, the outlet end of the high-temperature induced draft fan is connected to the inlet end of the electric regulating valve; a flow detection system is provided on the pipe wall of the high-temperature exhaust gas delivery pipeline.

[0012] As a preferred solution of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery described in the present invention, wherein: the working medium circulation flow includes the refrigerant circulation flow and the cooling water circulation flow; the flow detection system includes a first flow detection device for detecting the refrigerant circulation flow and a second flow detection device for detecting the cooling water circulation flow, and the opening of the electric regulating valve is controlled according to the detection results of the first flow detection device and the second flow detection device, so that the high-temperature exhaust gas selectively enters the bypass channel or the generator of the lithium bromide unit.

[0013] As a preferred embodiment of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to the present invention, the opening of the electric regulating valve is controlled according to the detection results of the first flow detection device and the second flow detection device, including:

[0014] Establishing a cooling capacity function per unit time based on the refrigerant circulation flow rate, establishing a heat dissipation function per unit time based on the cooling water circulation flow rate, and calculating a relationship between the cooling capacity function and the heat dissipation function to obtain a waste heat utilization index;

[0015] If the waste heat utilization index meets a first set condition and the cumulative value of the cooling capacity function is greater than the cumulative value of the heat dissipation function, the electric regulating valve is controlled to open to a first opening, so that the high-temperature exhaust gas enters the generator of the lithium bromide unit for heat exchange;

[0016] If the waste heat utilization index satisfies a second set condition and the cumulative value of the cooling capacity function is less than the cumulative value of the heat dissipation function, controlling the electric regulating valve to open to a second opening degree so that the high-temperature exhaust gas is partially discharged through the bypass channel;

[0017] In other cases, the electric regulating valve is controlled to be fully closed so that the high-temperature exhaust gas is completely discharged through the bypass channel.

[0018] As a preferred embodiment of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to the present invention, the cooling capacity function is established according to the changing trend and fluctuation amplitude of the refrigerant circulation flow rate, the heat dissipation function is established according to the changing trend and fluctuation amplitude of the cooling water circulation flow rate, and there is a phase difference between the cooling capacity function and the heat dissipation function;

[0019] The waste heat utilization index includes the fluctuation characteristic value of the cooling capacity function and the fluctuation characteristic value of the heat dissipation function;

[0020] The first setting condition is that the ratio of the fluctuation characteristic value of the cooling capacity function to the fluctuation characteristic value of the heat dissipation function jumps, and the distortion rate of the fluctuation characteristic value is greater than the steady-state value;

[0021] The second setting condition is that the waveform of the fluctuation characteristic value of the heat dissipation function is distorted, and the distortion rate of the fluctuation characteristic value is less than the steady-state value; wherein the fluctuation characteristic value is determined by the peak-to-valley ratio, period stability and distortion rate of the waveform;

[0022] The other conditions include that the phase difference between the cooling capacity function and the heat dissipation function exceeds the working cycle, or the change of the fluctuation characteristic value does not meet the monotonicity condition; wherein the monotonicity condition means that the distortion rate of the fluctuation characteristic value maintains a unidirectional change within a complete working cycle;

[0023] The first opening is proportional to the phase difference, the second opening is inversely proportional to the difference between the fluctuation characteristic values, and the adjustment rate of the first opening and the second opening is related to the change rate of the fluctuation characteristic value; wherein, the adjustment rate decreases as the distortion rate of the fluctuation characteristic value increases.

[0024] As a preferred solution of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to the present invention, the step of heat exchanging the high-temperature exhaust gas by the lithium bromide unit includes:

[0025] After the generator of the lithium bromide unit receives the high-temperature exhaust gas, the concentrated lithium bromide solution absorbs heat to generate a vapor pressure difference, which drives the refrigerant to circulate between the condenser, evaporator and absorber, and the circulating flow of the refrigerant produces a refrigeration effect;

[0026] The heat absorption process of the concentrated lithium bromide solution is controlled by a solution concentration gradient determined by the ratio of the refrigerant circulation flow rate to the cooling water circulation flow rate;

[0027] The cooling water circulation system formed by the lithium bromide unit and the cooling tower includes: a main cooling water circulation and an auxiliary cooling water circulation. The cooling water of the main cooling water circulation enters the absorber of the lithium bromide unit after being cooled by the cooling tower. The cooling water of the auxiliary cooling water circulation enters the condenser of the lithium bromide unit after being cooled by the cooling tower.

[0028] wherein the flow rate ratio of the main cooling water cycle to the auxiliary cooling water cycle is determined by the temperature difference of the refrigerant in the absorber and the condenser;

[0029] The circulating flow of the refrigerant produces a refrigeration effect, including:

[0030] When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is less than a first critical value, increasing the flow rate of the main cooling water circulation;

[0031] When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is greater than a second critical value, increasing the flow rate of the auxiliary cooling water circulation;

[0032] The fluctuation characteristic value is determined by waveform characteristics of the refrigerant circulation flow rate and the cooling water circulation flow rate.

[0033] As a preferred embodiment of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to the present invention, the step of controlling the temperature and humidity of the shell making drying area by the constant temperature and humidity unit includes:

[0034] Calculating the supply capacity of the chilled water according to the fluctuation characteristic values ​​of the refrigerant circulation flow rate and the cooling water circulation flow rate, adjusting the speed of the circulating water pump according to the supply capacity, and returning the chilled water to the lithium bromide unit after heat exchange through the constant temperature and humidity unit to form a circulation;

[0035] The supply capacity is determined by a phase relationship between a fluctuation characteristic value of the refrigerant circulation flow rate and a fluctuation characteristic value of the cooling water circulation flow rate.

[0036] To further solve the above technical problems, the present invention provides the following technical solutions: a casting constant temperature and humidity control system based on roasting furnace waste heat recovery, comprising: an exhaust gas allocation module for collecting high-temperature exhaust gas discharged from the roasting furnace, the high-temperature exhaust gas being transported to the lithium bromide unit through a high-temperature exhaust gas delivery pipeline, the high-temperature exhaust gas delivery pipeline being provided with an electric regulating valve, the outlet end of the electric regulating valve being connected to a bypass channel, the opening of the electric regulating valve being controlled according to the working medium circulation flow rate of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit;

[0037] A heat energy conversion module is used to control the lithium bromide unit to perform heat exchange on the high-temperature exhaust gas, and the lithium bromide unit and the cooling tower form a cooling water circulation system to generate chilled water;

[0038] The environmental control module is used to transport the chilled water to the constant temperature and humidity unit through a circulating water pump, and control the temperature and humidity of the shell making and drying area through the constant temperature and humidity unit.

[0039] A computer device includes a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery are implemented as described above.

[0040] A computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery as described above are implemented.

[0041] Beneficial effects of the present invention: The present invention solves the problem of the inability to adjust the waste gas supply according to the actual needs of the refrigeration system in the utilization of waste heat from traditional roasting furnaces through a waste gas diversion mechanism based on the working fluid circulation flow rate, and avoids the technical difficulty that the operating conditions of the roasting furnace are affected by the refrigeration system. In particular, through the detection of dual working fluid circulation flow rates and waveform characteristic analysis, the prediction and precise control of the system operating status are achieved, overcoming the hysteresis existing in the traditional temperature detection method. In the heat energy conversion link, a main and auxiliary dual-circulation cooling water system is adopted to solve the technical problem of fluctuations in the cooling effect of the lithium bromide unit when facing an unstable heat source, and ensure the reasonable distribution of cooling capacity. By associating the dynamic characteristics of the refrigerant cycle with the cooling water cycle, the present invention realizes the organic combination of the waste heat recovery of the roasting furnace and the shell making process, which not only ensures the stable operation of the roasting furnace, but also meets the strict requirements of the shell making process for a constant temperature and humidity environment, and improves the energy utilization efficiency while ensuring the process quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 This is a schematic diagram of the overall process of a casting constant temperature and humidity control method based on roasting furnace waste heat recovery proposed by the present invention;

[0044] Figure 2 This is a working diagram of the waste heat refrigerator in a casting constant temperature and humidity control method based on roasting furnace waste heat recovery proposed by the present invention;

[0045] Figure 3 This is a schematic diagram of the overall structure of a casting constant temperature and humidity control system based on roasting furnace waste heat recovery proposed by the present invention;

[0046] Figure 4 This is a diagram of the computer equipment used in the casting constant temperature and humidity control method based on roasting furnace waste heat recovery proposed by the present invention. DETAILED DESCRIPTION

[0047] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0048] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0049] Example 1, reference Figure 1 and Figure 2 , which is an embodiment of the present invention, provides a casting constant temperature and humidity control method based on roasting furnace waste heat recovery.

[0050] Figure 1 The figure shows the overall process of a casting constant temperature and humidity control method based on roasting furnace waste heat recovery, which includes the following steps:

[0051] S1: High-temperature exhaust gas discharged from the roasting furnace is collected and transported to the lithium bromide unit through a high-temperature exhaust gas delivery pipeline; the high-temperature exhaust gas delivery pipeline is provided with an electric regulating valve, the outlet end of the electric regulating valve is connected to a bypass channel, and the opening of the electric regulating valve is controlled according to the working medium circulation flow of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit.

[0052] Specifically, the lithium bromide unit includes a generator, a condenser, an evaporator, and an absorber connected in sequence. The high-temperature exhaust gas enters the generator of the lithium bromide unit through a high-temperature exhaust gas transmission pipeline for heat exchange. After the heat exchange, the exhaust gas temperature is reduced to 80℃~200℃.

[0053] In an optional embodiment, if Figure 2 As shown in the figure, it is the working route map of the waste heat refrigeration machine.

[0054] In this embodiment, the high-temperature exhaust gas pipeline serves as the primary channel for recovering waste heat from the roaster. It comprises not only the pipeline itself, which transports the high-temperature exhaust gas, but also an electrically controlled valve integrated within the pipeline. This valve, an integral component of the pipeline, controls the amount of exhaust gas entering the lithium bromide unit. Specifically, the pipeline is equipped with an electrically controlled valve, which controls the flow of the high-temperature exhaust gas by adjusting its opening. The valve's opening is adjusted based on the measured flow rate of the working fluid circulation, allowing the high-temperature exhaust gas to selectively enter the lithium bromide unit or be discharged through a bypass channel, achieving efficient utilization of the roaster's waste heat.

[0055] Specifically, the high-temperature exhaust gas delivery pipeline is further equipped with a high-temperature induced draft fan, the outlet of which is connected to the inlet of the electric control valve. Specifically, the high-temperature induced draft fan and the electric control valve are sequentially connected. The outlet of the electric control valve is connected to a bypass channel. A flow detection system is installed on the wall of the high-temperature exhaust gas delivery pipeline. The flow detection system includes a first flow detection device for detecting the refrigerant circulation flow rate of the lithium bromide unit and a second flow detection device for detecting the cooling water circulation flow rate. The opening of the electric control valve is controlled based on the detection results of the first and second flow detection devices, allowing the high-temperature exhaust gas to selectively enter the bypass channel or the generator of the lithium bromide unit.

[0056] Furthermore, controlling the opening of the electric regulating valve according to the detection results of the first flow detection device and the second flow detection device includes:

[0057] First, a cooling capacity function per unit time is established based on the fluctuation characteristic values ​​of the refrigerant circulation flow rate, and a heat dissipation function per unit time is established based on the fluctuation characteristic values ​​of the cooling water circulation flow rate. The relationship between the cooling capacity function and the heat dissipation function is calculated to obtain the waste heat utilization index. The fluctuation characteristic values ​​are determined by the peak-to-valley ratio, cyclic stability, and distortion rate of the waveform. Specifically, the peak-to-valley ratio characterizes the amplitude characteristics of the flow fluctuation, the cyclic stability characterizes the time characteristics of the flow fluctuation, and the waveform distortion rate characterizes the degree of deviation of the flow fluctuation. There is a phase difference between the cooling capacity function and the heat dissipation function.

[0058] In a preferred embodiment of the present invention, the fluctuation characteristic value is determined by calculating the peak-to-valley ratio, cyclic stability, and distortion rate of the waveform, specifically including the following method:

[0059] The first method: continuously collect flow data within a complete working cycle. First, calculate the peak-to-valley ratio: find all the peak points and valley points in the cycle, divide the average value of all peak values ​​by the average value of all valley values ​​to obtain the peak-to-valley ratio. Secondly, calculate the cycle stability: determine it by calculating the change in the time interval between two adjacent peaks. The smaller the change in these time intervals, the more stable the cycle and the higher the cycle stability. Finally, calculate the distortion rate: compare the actual flow waveform with the standard waveform under ideal working conditions, and calculate the degree to which the actual waveform deviates from the standard waveform. The system performs weighted calculations on these three parameters according to the preset weights to obtain the final fluctuation characteristic value.

[0060] The second method first establishes an ideal flow waveform model under standard operating conditions. During actual operation, flow data is continuously collected and three characteristics are calculated: the peak-to-valley ratio is determined by real-time monitoring and calculating the ratio of the waveform's highest to lowest points; the cyclic stability is determined by analyzing the consistency of the waveform's recurring time intervals; and the distortion rate is determined by calculating the deviation between the actual waveform and the ideal waveform. The system uses the changing trends of these three characteristics as the basis for adjusting control parameters.

[0061] The third method is to determine the fluctuation characteristic value through real-time data analysis. Specifically, the peak-to-valley ratio reflects the amplitude characteristics of flow fluctuations and is determined through statistical analysis; the cyclic stability characterizes the temporal characteristics of flow fluctuations and is determined by analyzing the repeatability of the waveform; and the waveform distortion rate characterizes the degree of deviation of flow fluctuations and is determined by comparing actual operating data with standard operating conditions. These three parameters together constitute the fluctuation characteristic value, which is used to guide system regulation and control.

[0062] In practical applications, the appropriate implementation method can be selected based on the operating status of the roaster and the operating characteristics of the lithium bromide unit. Changes in these characteristic values ​​can be monitored in real time, and the opening of the electric regulating valve can be controlled accordingly to ensure the rational distribution of high-temperature exhaust gas and achieve efficient utilization of the roaster's waste heat.

[0063] Secondly, if the waste heat utilization index meets the first set condition and the cumulative value of the cooling capacity function is greater than the cumulative value of the heat dissipation function, the electric regulating valve is controlled to open to the first opening, so that the high-temperature exhaust gas enters the generator of the lithium bromide unit for heat exchange;

[0064] If the waste heat utilization index meets the second set condition and the cumulative value of the cooling capacity function is less than the cumulative value of the heat dissipation function, the electric regulating valve is controlled to open to the second opening, so that the high-temperature exhaust gas is partially discharged through the bypass channel;

[0065] In other cases, the electric control valve is fully closed, allowing the high-temperature exhaust gas to be discharged completely through the bypass channel. It should be noted that in this implementation, other cases include, but are not limited to: the phase difference between the cooling capacity function and the heat dissipation function exceeds the operating cycle, or the change in the fluctuation characteristic value does not meet the monotonicity condition; the monotonicity condition refers to the distortion rate of the fluctuation characteristic value maintaining a unidirectional change within a complete operating cycle.

[0066] It should be noted that the first setting condition is that the ratio of the fluctuation characteristic value of the cooling capacity function to the fluctuation characteristic value of the heat dissipation function jumps, and the distortion rate of the fluctuation characteristic value is greater than the steady-state value.

[0067] The second setting condition is that the waveform of the fluctuation characteristic value of the heat dissipation function is distorted, and the distortion rate of the fluctuation characteristic value is less than the steady-state value; wherein the fluctuation characteristic value is determined by the peak-to-valley ratio, period stability and distortion rate of the waveform.

[0068] The first opening is proportional to the phase difference, the second opening is inversely proportional to the difference in the fluctuation characteristic values, and the adjustment rates of the first opening and the second opening are related to the change rates of the fluctuation characteristic values; wherein the adjustment rate decreases as the distortion rate of the fluctuation characteristic values ​​increases.

[0069] Preferably, in this embodiment, the high-temperature exhaust gas delivery pipeline serves as the main delivery channel for waste heat recovery of the roasting furnace, and includes not only a pipeline body for delivering high-temperature exhaust gas, but also an electric regulating valve integrated in the pipeline. As an integral part of the high-temperature exhaust gas delivery pipeline, the electric regulating valve's opening adjustment directly affects the flow direction control of the high-temperature exhaust gas. The regulation mechanism is implemented by a flow detection system installed on the pipe wall, which includes a first flow detection device for detecting the refrigerant circulation flow and a second flow detection device for detecting the cooling water circulation flow. This dual flow detection design enables the system to monitor the operating status of the lithium bromide unit in real time, thereby achieving precise control of the exhaust gas flow direction. Compared with the traditional single temperature detection, this control method based on the working fluid circulation flow can respond to changes in the system state more quickly, avoids the lag of temperature detection, and is of great significance for maintaining 24-hour uninterrupted operation of the roasting furnace.

[0070] The present invention characterizes the system's operating status through the waveform characteristics of the cooling capacity and heat dissipation functions. The number of peaks reflects the frequency characteristics of the working fluid cycle, the spacing between troughs reflects the cycle's stability, and the waveform distortion rate indicates the degree to which the system deviates from normal operating conditions. This waveform analysis-based control method can predict the system's operating trends before the exhaust gas enters the lithium bromide unit, enabling preventive adjustments. For example, waveform distortion indicates an abnormality in the working fluid cycle. Adjusting the opening of the electric control valve can timely adjust the amount of exhaust gas entering the lithium bromide unit, preventing a decrease in refrigeration efficiency due to improper heat input. This predictive control not only improves system stability but also allows for flexible adjustment of heat input according to process requirements, playing a crucial role in maintaining the constant temperature and humidity required for the shell production process. By real-time monitoring of the working fluid circulation flow and waveform analysis, the system maximizes waste heat utilization while ensuring the normal operation of the roasting furnace, significantly improving energy efficiency.

[0071] S2: The lithium bromide unit performs heat exchange on the high-temperature exhaust gas. The lithium bromide unit and the cooling tower form a cooling water circulation system to produce chilled water.

[0072] The steps for heat exchange of high-temperature exhaust gas by lithium bromide unit include:

[0073] After the generator of the lithium bromide unit receives high-temperature exhaust gas, the concentrated lithium bromide solution absorbs heat to generate a vapor pressure difference, which drives the refrigerant to circulate between the condenser, evaporator and absorber. The circulating flow of the refrigerant produces a cooling effect;

[0074] The heat absorption process of the concentrated lithium bromide solution is controlled by the solution concentration gradient determined by the ratio of the refrigerant circulation flow rate to the cooling water circulation flow rate.

[0075] The cooling water circulation system formed by the lithium bromide unit and the cooling tower includes: a main cooling water circulation and an auxiliary cooling water circulation. The cooling water of the main cooling water circulation enters the absorber of the lithium bromide unit after being cooled by the cooling tower, and the cooling water of the auxiliary cooling water circulation enters the condenser of the lithium bromide unit after being cooled by the cooling tower.

[0076] The flow rate ratio of the main cooling water cycle to the auxiliary cooling water cycle is determined by the temperature difference between the refrigerant in the absorber and the condenser.

[0077] The circulation of refrigerant produces a cooling effect, including:

[0078] When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is less than a first critical value, increasing the flow rate of the main cooling water circulation;

[0079] When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is greater than a second critical value, increasing the flow rate of the auxiliary cooling water circulation;

[0080] It should be noted that in the present invention, the first critical value and the second critical value are important parameters for controlling the refrigeration effect. These two critical values ​​essentially reflect the dynamic equilibrium state of the lithium bromide unit working medium circulation system. The first critical value is mainly used to judge whether the matching degree of the refrigerant circulation and the cooling water circulation is in an ideal state. Its numerical value comes from the statistical analysis of the system's long-term operation data. Specifically, by statistically analyzing the difference between the fluctuation characteristic value of the refrigerant circulation flow and the fluctuation characteristic value of the cooling water circulation flow when the roasting furnace is running under standard operating conditions, the fluctuation characteristic value difference range under the system's optimal operating state is determined. When the fluctuation characteristic value difference of the two working medium circulations is less than the first critical value, it shows that the coordination of the system's refrigerant circulation and the cooling water circulation is relatively ideal. At this time, the refrigeration efficiency can be improved by increasing the main cooling water circulation flow. Practice shows that the first critical value is preferably between 0.15 and 0.25. This range can better balance the stability and responsiveness of the system.

[0081] The second critical value is mainly used to determine whether the system needs additional cooling capacity support, and its numerical value is set based on a comprehensive consideration of the refrigeration capacity limit of the lithium bromide unit and the utilization efficiency of the waste heat of the roasting furnace exhaust gas. When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is greater than the second critical value, it means that the matching relationship between the refrigerant circulation and the cooling water circulation has exceeded the optimal working range, and the system needs to provide additional cooling capacity by increasing the auxiliary cooling water circulation flow rate to prevent the lithium bromide solution from crystallizing or the refrigeration effect from decreasing. Based on the roasting furnace exhaust gas temperature variation range (400-600℃) and the design parameters of the lithium bromide unit in the present invention, the second critical value is preferably between 0.35-0.45. The setting of this range can ensure that the system has sufficient adjustment margin without affecting the overall efficiency of the system due to over-adjustment.

[0082] In this embodiment, a dual-circulation control mechanism is designed for the heat exchange process of the lithium bromide unit, including a main cooling water cycle and an auxiliary cooling water cycle. This dual-circulation structure allows the cooling water to enter the absorber and condenser respectively, thereby achieving precise temperature control of the refrigerant at different stages. Compared with the traditional single cooling water cycle, this graded cooling method can better adapt to the fluctuation of the exhaust gas temperature of the roasting furnace. For example, when the temperature of the high-temperature exhaust gas fluctuates, the main cooling water cycle can prioritize the cooling capacity of the absorber to ensure the absorption effect of the lithium bromide solution; while the auxiliary cooling water cycle can independently adjust the cooling intensity of the condenser to maintain the condensation effect of the refrigerant. This dynamic adjustment mechanism not only improves the adaptability of the system, but also solves the problem of unstable cooling effect of traditional lithium bromide units when facing unstable heat sources.

[0083] Specifically, this invention introduces the concept of a fluctuation characteristic value to control the coordinated operation of the dual-circulation system. The fluctuation characteristic value reflects the dynamic characteristics of the refrigerant and cooling water circulation flows, and its value is determined by the waveform characteristics of the flow rates. When the difference between the fluctuation characteristic value of the refrigerant and cooling water circulation flows is small, the system is operating smoothly, and basic cooling requirements are maintained primarily by adjusting the primary cooling water circulation. When the difference is large, it indicates a significant change in system load, and additional cooling capacity is provided by increasing the auxiliary cooling water circulation flow. This control strategy based on the fluctuation characteristic value achieves precise cooling capacity allocation, avoiding the energy waste caused by uneven cooling capacity distribution in traditional control methods. Practice has demonstrated that, under 24-hour continuous operation of the roasting furnace, this control method can improve the coefficient of performance (COP) of the lithium bromide unit by over 15%, while simultaneously controlling temperature fluctuations within ±0.5°C, providing a stable temperature and humidity environment for the shell production process.

[0084] S3: The chilled water is transported to the constant temperature and humidity unit through the circulating water pump, and the temperature and humidity of the shell making and drying area are controlled by the constant temperature and humidity unit.

[0085] Specifically, the steps of controlling the temperature and humidity of the shell making drying area by a constant temperature and humidity unit include:

[0086] The chilled water supply capacity is calculated based on the fluctuation characteristic values ​​of the refrigerant circulation flow rate and the cooling water circulation flow rate. The speed of the circulating water pump is adjusted according to the supply capacity. The chilled water is returned to the lithium bromide unit after heat exchange in the constant temperature and humidity unit to form a cycle.

[0087] Exemplarily, the specific steps of the system operation include:

[0088] Step 1: System startup. First, check the environmental parameters of the shell drying area. When the temperature exceeds the range of 20-27°C or the humidity exceeds the range of 40-70%, start the system. During startup, the circulating water pump runs at the minimum speed and gradually increases to the reference speed. At the same time, monitor whether the supply temperature and flow of the chilled water reach the set value.

[0089] Step 2: Stable operation stage. Determine the chilled water supply capacity based on the phase relationship between the fluctuation characteristic value of the refrigerant circulation flow and the fluctuation characteristic value of the cooling water circulation flow. When the phase difference is within the preset range, maintain the base speed of the circulating water pump; when the phase difference exceeds the preset range, dynamically adjust the water pump speed according to the preset adjustment curve;

[0090] Step 3: Temperature and humidity control. Use constant temperature and humidity units to control the surface layer area and the back layer area separately:

[0091] For the surface area, the temperature is controlled within the range of 20-26°C and the humidity is controlled within the range of 60-70%;

[0092] For the dorsal area, the temperature is controlled within the range of 20-27°C and the humidity is controlled within the range of 40-60%;

[0093] When the temperature and humidity fluctuate, the system first adjusts the supply air temperature, then the fresh air ratio, and finally the humidification amount;

[0094] Step 4: Handling abnormal situations:

[0095] 1) When insufficient supply capacity is detected, the system automatically switches to the backup cooling source;

[0096] 2) When the temperature and humidity are detected to be out of the control range, the system will issue an alarm signal and record abnormal data;

[0097] 3) When abnormal chilled water temperature is detected, the system automatically adjusts the pump speed and limits the maximum load;

[0098] Step 5: System Stop: When the system needs to be stopped, first reduce the cooling load. When the system load drops below 30%, gradually reduce the water pump speed and finally turn off the circulating water pump.

[0099] In summary, the present invention solves the problem of the inability to adjust the waste gas supply according to the actual needs of the refrigeration system in the utilization of waste heat from traditional roasting furnaces through a waste gas diversion mechanism based on the working fluid circulation flow rate, and avoids the technical difficulty of the roasting furnace operating conditions being affected by the refrigeration system. In particular, through dual working fluid circulation flow detection and waveform feature analysis, the system operating status is predicted and accurately controlled, overcoming the hysteresis existing in traditional temperature detection methods. In the heat energy conversion link, a main and auxiliary dual-circulation cooling water system is adopted to solve the technical problem of fluctuations in the cooling effect of the lithium bromide unit when facing an unstable heat source, and ensure the reasonable distribution of cooling capacity. By associating the dynamic characteristics of the refrigerant cycle with the cooling water cycle, the present invention realizes the organic combination of the waste heat recovery of the roasting furnace and the shell making process, which not only ensures the stable operation of the roasting furnace, but also meets the strict requirements of the shell making process for a constant temperature and humidity environment, while ensuring the process quality and improving the energy utilization efficiency.

[0100] Example 2, reference Figure 3 , which is an embodiment of the present invention, provides a casting constant temperature and humidity control system based on roasting furnace waste heat recovery, comprising:

[0101] The exhaust gas distribution module is used to collect the high-temperature exhaust gas discharged from the roasting furnace. The high-temperature exhaust gas is transported to the lithium bromide unit through the high-temperature exhaust gas delivery pipeline. The high-temperature exhaust gas delivery pipeline is provided with an electric regulating valve. The outlet end of the electric regulating valve is connected to a bypass channel. The opening of the electric regulating valve is controlled according to the working medium circulation flow of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit;

[0102] The heat energy conversion module is used to control the lithium bromide unit to perform heat exchange on the high-temperature exhaust gas. The lithium bromide unit and the cooling tower form a cooling water circulation system to produce chilled water;

[0103] The environmental control module is used to transport chilled water to the constant temperature and humidity unit through a circulating water pump, and control the temperature and humidity of the shell making and drying area through the constant temperature and humidity unit.

[0104] Example 3, reference Figure 4 , which is an embodiment of the present invention, differs from the previous embodiment in that: if the functions described are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or the portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0105] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0106] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, and then editing, interpreting, or processing in another suitable manner as necessary, and then storing it in a computer memory.

[0107] It should be understood that various components of the present invention may be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof may be used: a discrete logic circuit having logic gate circuits for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0108] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A casting constant temperature and humidity control method based on roasting furnace waste heat recovery, characterized in that: include: High-temperature exhaust gas discharged from the roasting furnace is collected and transported to the lithium bromide unit through a high-temperature exhaust gas delivery pipeline; the high-temperature exhaust gas delivery pipeline is provided with an electric regulating valve, the outlet end of the electric regulating valve is connected to a bypass channel, and the opening of the electric regulating valve is controlled according to the circulating flow rate of the working medium of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit; The lithium bromide unit performs heat exchange on the high-temperature exhaust gas, and the lithium bromide unit and the cooling tower form a cooling water circulation system to produce chilled water; The chilled water is delivered to the constant temperature and humidity unit through a circulating water pump, and the temperature and humidity of the shell making and drying area are controlled by the constant temperature and humidity unit; The working medium circulation flow rate includes the refrigerant circulation flow rate and the cooling water circulation flow rate; a flow detection system is provided on the pipe wall of the high-temperature exhaust gas transmission pipeline; the flow detection system includes a first flow detection device for detecting the refrigerant circulation flow rate and a second flow detection device for detecting the cooling water circulation flow rate. The opening of the electric regulating valve is controlled based on the detection results of the first flow detection device and the second flow detection device, so that the high-temperature exhaust gas selectively enters the bypass channel or the generator of the lithium bromide unit; Controlling the opening of the electric regulating valve according to the detection results of the first flow detection device and the second flow detection device includes: Establishing a cooling capacity function per unit time based on the fluctuation characteristic value of the refrigerant circulation flow rate, establishing a heat dissipation function per unit time based on the fluctuation characteristic value of the cooling water circulation flow rate, and calculating a relationship between the cooling capacity function and the heat dissipation function to obtain a waste heat utilization index; If the waste heat utilization index meets a first set condition and the cumulative value of the cooling capacity function is greater than the cumulative value of the heat dissipation function, the electric regulating valve is controlled to open to a first opening, so that the high-temperature exhaust gas enters the generator of the lithium bromide unit for heat exchange; If the waste heat utilization index satisfies a second set condition and the cumulative value of the cooling capacity function is less than the cumulative value of the heat dissipation function, controlling the electric regulating valve to open to a second opening degree so that the high-temperature exhaust gas is partially discharged through the bypass channel; In other cases, the electric regulating valve is controlled to be fully closed so that the high-temperature exhaust gas is completely discharged through the bypass channel; There is a phase difference between the cooling capacity function and the heat dissipation function; The first setting condition is that the ratio of the fluctuation characteristic value of the cooling capacity function to the fluctuation characteristic value of the heat dissipation function jumps, and the distortion rate of the fluctuation characteristic value is greater than the steady-state value; The second setting condition is that the waveform of the fluctuation characteristic value of the heat dissipation function is distorted, and the distortion rate of the fluctuation characteristic value is less than the steady-state value; wherein the fluctuation characteristic value is determined by the peak-to-valley ratio, period stability and distortion rate of the waveform; The other conditions include that the phase difference between the cooling capacity function and the heat dissipation function exceeds the working cycle, or the change of the fluctuation characteristic value does not meet the monotonicity condition; wherein the monotonicity condition means that the distortion rate of the fluctuation characteristic value maintains a unidirectional change within a complete working cycle; The first opening is proportional to the phase difference, the second opening is inversely proportional to the difference between the fluctuation characteristic values, and the adjustment rate of the first opening and the second opening is related to the change rate of the fluctuation characteristic value; wherein, the adjustment rate decreases as the distortion rate of the fluctuation characteristic value increases.

2. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 1 is characterized in that: The lithium bromide unit includes a generator, a condenser, an evaporator, and an absorber connected in sequence, and the high-temperature exhaust gas enters the generator through the high-temperature exhaust gas delivery pipeline for heat exchange; The high-temperature exhaust gas delivery pipeline is further provided with a high-temperature induced draft fan, and the outlet end of the high-temperature induced draft fan is connected to the inlet end of the electric regulating valve.

3. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 2 is characterized in that: The step of heat exchanging the high-temperature exhaust gas by the lithium bromide unit includes: After the generator of the lithium bromide unit receives the high-temperature exhaust gas, the concentrated lithium bromide solution absorbs heat to generate a vapor pressure difference, which drives the refrigerant to circulate between the condenser, evaporator and absorber, and the circulating flow of the refrigerant produces a refrigeration effect; The heat absorption process of the concentrated lithium bromide solution is controlled by a solution concentration gradient determined by the ratio of the refrigerant circulation flow rate to the cooling water circulation flow rate; The cooling water circulation system formed by the lithium bromide unit and the cooling tower includes: a main cooling water circulation and an auxiliary cooling water circulation. The cooling water of the main cooling water circulation enters the absorber of the lithium bromide unit after being cooled by the cooling tower. The cooling water of the auxiliary cooling water circulation enters the condenser of the lithium bromide unit after being cooled by the cooling tower. wherein the flow rate ratio of the main cooling water cycle to the auxiliary cooling water cycle is determined by the temperature difference of the refrigerant in the absorber and the condenser; The circulating flow of the refrigerant produces a refrigeration effect, including: When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is less than a first critical value, increasing the flow rate of the main cooling water circulation; When the difference between the fluctuation characteristic value of the refrigerant circulation flow rate and the fluctuation characteristic value of the cooling water circulation flow rate is greater than a second critical value, increasing the flow rate of the auxiliary cooling water circulation; The fluctuation characteristic value is determined by waveform characteristics of the refrigerant circulation flow rate and the cooling water circulation flow rate.

4. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 3 is characterized in that: The steps of controlling the temperature and humidity of the shell making and drying area by the constant temperature and humidity unit include: The supply capacity of the chilled water is calculated based on the fluctuation characteristic values ​​of the refrigerant circulation flow rate and the cooling water circulation flow rate, and the speed of the circulating water pump is adjusted according to the supply capacity. The chilled water is returned to the lithium bromide unit after heat exchange through the constant temperature and humidity unit to form a cycle.

5. A casting constant temperature and humidity control system based on roasting furnace waste heat recovery, based on the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to any one of claims 1 to 4, characterized in that: include, An exhaust gas distribution module is used to collect high-temperature exhaust gas discharged from the roasting furnace. The high-temperature exhaust gas is transported to the lithium bromide unit through a high-temperature exhaust gas delivery pipeline. The high-temperature exhaust gas delivery pipeline is provided with an electric regulating valve. The outlet end of the electric regulating valve is connected to a bypass channel. The opening of the electric regulating valve is controlled according to the circulating flow rate of the working medium of the lithium bromide unit, so that the high-temperature exhaust gas selectively enters the bypass channel or the lithium bromide unit; A heat energy conversion module is used to control the lithium bromide unit to perform heat exchange on the high-temperature exhaust gas, and the lithium bromide unit and the cooling tower form a cooling water circulation system to generate chilled water; The environmental control module is used to transport the chilled water to the constant temperature and humidity unit through a circulating water pump, and control the temperature and humidity of the shell making and drying area through the constant temperature and humidity unit.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to any one of claims 1 to 4 are implemented.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to any one of claims 1 to 4 are implemented.

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