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

Abstract

The invention discloses a casting constant-temperature and constant-humidity control method and system based on roasting furnace waste heat recovery, and relates to the technical field of waste heat recycling. The casting constant-temperature and constant-humidity control method comprises the steps that high-temperature waste gas discharged by a roasting furnace is collected and conveyed to a lithium bromide unit through a high-temperature waste gas conveying pipeline, and the high-temperature waste gas conveying pipeline is provided with an electric control valve; the outlet end of the electric control valve is connected with a bypass channel, and the opening degree of the electric control valve is controlled according to the running state of the lithium bromide unit, so that the high-temperature waste gas selectively enters the bypass channel or the lithium bromide unit to perform heat exchange on the high-temperature waste gas; chilled water is conveyed to the constant-temperature and constant-humidity unit through the circulating water pump so as to control the temperature and the humidity of the shell-making drying area. By establishing a waste gas selective shunting mechanism, a closed-loop cooling circulation system and an accurate temperature and humidity control system, efficient utilization of waste heat of the roasting furnace and accurate control over the shell making process environment are achieved, and the dual effects of energy conservation and emission reduction and process quality control are achieved.

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 key link that affects the quality of castings. The traditional shell making process requires that the surface layer temperature be maintained at 20-26°C and the relative humidity be 60-70%, and the back layer temperature be maintained at 20-27°C and the relative humidity be 40-60%. This strict temperature and humidity control requires 24-hour uninterrupted operation. At present, the precision casting industry generally uses a regenerative box roasting furnace for shell mold roasting. The high-temperature exhaust gas (400-600°C) generated by the roasting furnace is usually directly discharged or only used for simple hot water heat exchange. However, due to the lack of an effective exhaust gas control mechanism and heat allocation system, the heat energy of these high-temperature exhaust gases cannot be fully utilized. At the same time, the shell making workshop uses traditional compressor air conditioners and constant temperature dehumidification units to maintain a constant temperature and humidity environment. This method 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 in the recovery of waste heat from various types of high-temperature exhaust gases. In the ceramic industry, roasting furnace exhaust gas is usually used for air preheating or hot water heat exchange, while lithium bromide units are mainly used in conventional refrigeration occasions in other industries. In the prior art, 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 systems often use 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 in the existing technology: first, there is a lack of intelligent allocation mechanism for roasting furnace exhaust gas, resulting in low efficiency of waste heat utilization; second, the synergy between the lithium bromide refrigeration system and the cooling cycle is poor, affecting the stability of the system; third, the temperature and humidity control accuracy is insufficient, which makes 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 waste heat recovery from a roasting furnace, which can solve the problems mentioned in the background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a casting constant temperature and humidity control method based on waste heat recovery of a roasting furnace, 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, and 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; 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 generate chilled water; The chilled water is transported 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.

[0008] 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 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 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.

[0009] 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.

[0010] 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: 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 refrigerant circulation flow rate, establishing a heat dissipation function per unit time based on the cooling water circulation flow rate, and calculating the 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 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 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 meets the second setting 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 a second opening, 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.

[0011] 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 cooling capacity function is established according to the change trend and fluctuation amplitude of the refrigerant circulation flow rate, the heat dissipation function is established according to the change 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; The waste heat utilization index includes a fluctuation characteristic value of the cooling capacity function and a fluctuation characteristic value of 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 situations 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 refers to 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 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.

[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, the step of heat exchange of 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, driving the refrigerant to circulate between the condenser, the evaporator and the absorber, and the circulating flow of the refrigerant generates 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, wherein 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; 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.

[0013] As a preferred solution of the casting constant temperature and humidity control method based on the waste heat recovery of the roasting furnace described in 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: The supply capacity of the chilled water is calculated according to 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, and the chilled water is refluxed to the lithium bromide unit after heat exchange by the constant temperature and humidity unit to form a cycle; 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.

[0014] 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 waste heat recovery of a roasting furnace, comprising: a waste gas allocation module, used to collect high-temperature waste gas discharged from the roasting furnace, the high-temperature waste gas is transported to the lithium bromide unit through a high-temperature waste gas delivery pipeline, the high-temperature waste 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 waste gas selectively enters the bypass channel or the lithium bromide unit; A heat energy conversion module, used to control the lithium bromide unit to perform heat exchange on the high-temperature exhaust gas, wherein the lithium bromide unit and the cooling tower form a cooling water circulation system to generate chilled water; The environment 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.

[0015] A computer device comprises 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 as described above are implemented.

[0016] 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.

[0017] Beneficial effects of the present invention: The present invention solves the problem that the waste gas supply cannot be adjusted 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 feature analysis, the prediction and precise control of the system operating status are achieved, overcoming the lag 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 refrigeration effect of the lithium bromide unit when facing an unstable heat source, and ensure the reasonable allocation 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

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0019] 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; Figure 2 A working route map of a waste heat refrigerator in a casting constant temperature and humidity control method based on waste heat recovery from a roasting furnace proposed by the present invention; 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; Figure 4 This is a computer equipment diagram of a casting constant temperature and humidity control method based on roasting furnace waste heat recovery proposed by the present invention. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and 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.

[0022] 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.

[0023] Figure 1 The overall process diagram of a casting constant temperature and humidity control method based on the waste heat recovery of the roasting furnace is shown, which includes the following steps: S1: The high-temperature exhaust gas discharged from the roasting furnace is collected and 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, and 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.

[0024] 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 delivery pipeline for heat exchange. The exhaust gas temperature after the heat exchange is reduced to 80°C~200°C.

[0025] In an optional embodiment, if Figure 2 As shown in the figure, it is the working route map of the waste heat refrigerator. In this embodiment, the high-temperature exhaust gas delivery pipeline serves as the main delivery channel for the waste heat recovery of the roasting furnace. It not only includes a pipeline body for delivering high-temperature exhaust gas, but also includes an electric regulating valve integrated in the pipeline. The electric regulating valve is an integral part of the high-temperature exhaust gas delivery pipeline and is used to control the amount of exhaust gas entering the lithium bromide unit. Specifically, the high-temperature exhaust gas delivery pipeline is provided with an electric regulating valve, and the flow direction of the high-temperature exhaust gas is controlled by adjusting the opening of the electric regulating valve. The electric regulating valve is adjusted according to the detection result of the working medium circulation flow rate, so that the high-temperature exhaust gas can selectively enter the lithium bromide unit or be discharged through the bypass channel, so as to realize the efficient utilization of the waste heat of the roasting furnace.

[0026] Specifically, the high-temperature exhaust gas delivery pipeline is also 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, that is, the high-temperature induced draft fan and the electric regulating valve are connected in sequence. Among them, the outlet end of the electric regulating valve is connected to the bypass channel, and a flow detection system is provided on the pipe 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 of the lithium bromide unit and a second flow detection device for detecting the cooling water circulation flow. 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.

[0027] Further, 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: First, the cooling capacity function per unit time is established based on the fluctuation characteristic value of the refrigerant circulation flow, and the heat dissipation function per unit time is established based on the fluctuation characteristic value of the cooling water circulation flow, and the relationship between the cooling capacity function and the heat dissipation function is calculated to obtain the waste heat utilization index. Among them, the fluctuation characteristic value is determined by the peak-to-valley ratio, periodic stability and distortion rate of the waveform; specifically, the peak-to-valley ratio of the waveform represents the amplitude characteristics of the flow fluctuation, the periodic stability represents the time characteristics of the flow fluctuation, and the waveform distortion rate represents the degree of deviation of the flow fluctuation. There is a phase difference between the cooling capacity function and the heat dissipation function.

[0028] In a preferred embodiment of the present invention, the fluctuation characteristic value is determined by calculating the peak-to-valley ratio, period stability and distortion rate of the waveform, specifically including the following method: The first method is to continuously collect flow data within a complete working cycle. First, calculate the peak-to-valley ratio: find all the peak points and valley points within 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 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.

[0029] The second method is to first establish an ideal flow waveform model under standard working conditions. During the actual operation, the flow data is continuously collected and three characteristics are calculated: the peak-to-valley ratio is obtained by real-time monitoring and calculating the ratio of the highest point to the lowest point of the waveform; the periodic stability is determined by analyzing the consistency of the time interval of the repeated waveform; the distortion rate is determined by calculating the degree of deviation between the actual waveform and the ideal waveform. The system uses the change trend of these three characteristic values ​​as the basis for adjusting the control parameters.

[0030] 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 periodic stability characterizes the time characteristics of flow fluctuations and is determined by analyzing the repeatability of the waveform; the waveform distortion rate characterizes the degree of deviation of flow fluctuations and is determined by comparing the difference between actual operating data and standard operating data. These three parameters together constitute the fluctuation characteristic value, which is used to guide the regulation and control of the system.

[0031] In practical applications, the appropriate implementation method can be selected according to the operating status of the roaster and the working characteristics of the lithium bromide unit. The 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 reasonable distribution of high-temperature exhaust gas and achieve efficient utilization of the waste heat of the roaster.

[0032] 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; If the waste heat utilization index meets the second setting 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 part of the high-temperature exhaust gas is 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. 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 working cycle, or the change of the fluctuation characteristic value does not meet the monotonicity condition; wherein the monotonicity condition refers to the distortion rate of the fluctuation characteristic value maintaining a unidirectional change within a complete working cycle.

[0033] 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.

[0034] 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, periodic stability and distortion rate of the waveform.

[0035] 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.

[0036] 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 opening adjustment of the electric regulating valve directly affects the flow direction control of the high-temperature exhaust gas. The regulation mechanism is realized by a flow detection system installed on the pipeline 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 realizing 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 system state changes more quickly, avoid the lag of temperature detection, and is of great significance for maintaining 24-hour uninterrupted operation of the roasting furnace.

[0037] The present invention characterizes the system operation state through the waveform characteristics of the cooling capacity function and the heat dissipation function, wherein the number of peaks reflects the frequency characteristics of the working medium cycle, the trough spacing reflects the stability of the cycle, and the waveform distortion rate indicates the degree to which the system deviates from the normal working state. This control method based on waveform analysis can predict the operation trend of the system before the waste gas enters the lithium bromide unit, and realize preventive adjustment. For example, when the waveform is distorted, it means that the working medium cycle is abnormal. At this time, by adjusting the opening of the electric regulating valve, the amount of waste gas entering the lithium bromide unit can be adjusted in time to avoid the decrease in refrigeration efficiency caused by improper heat input. This predictive control not only improves the stability of the system, but also can flexibly adjust the heat input according to the process requirements, which plays an important role in ensuring the constant temperature and humidity environment required for the shell making process. Through real-time monitoring and waveform analysis of the working medium circulation flow, the system can maximize the use of waste heat from the waste gas while ensuring the normal operation of the roasting furnace, significantly improving the energy utilization efficiency.

[0038] S2: 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.

[0039] The steps of heat exchange of high temperature exhaust gas by lithium bromide unit include: 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. The circulating flow of the refrigerant produces a refrigeration effect. 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.

[0040] 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. 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.

[0041] The circulation of refrigerant produces a cooling 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; 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, and these two critical values ​​essentially reflect the dynamic equilibrium state of the working medium circulation system of the lithium bromide unit. 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, and its value comes from the statistical analysis of the long-term operation data of the system. 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 working conditions, the fluctuation characteristic value difference range under the optimal operation state of the system 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 refrigerant circulation and the cooling water circulation is relatively ideal, and the refrigeration efficiency can be improved by increasing the main cooling water circulation flow. Practice shows that the first critical value is preferably between 0.15-0.25, and this range can better balance the stability and responsiveness of the system.

[0042] The second critical value is mainly used to determine whether the system needs additional cooling capacity support, and its numerical setting is based on the 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 temperature variation range of the roasting furnace exhaust gas in the present invention (400-600°C) and the design parameters of the lithium bromide unit, 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.

[0043] 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 the 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 preferentially adjust 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.

[0044] In particular, the present invention controls the coordinated work of the dual circulation system by introducing the concept of fluctuation characteristic value. The fluctuation characteristic value reflects the dynamic change characteristics of the refrigerant circulation flow and the cooling water circulation flow, and its value is determined by the waveform characteristics of the flow. When the difference between the fluctuation characteristic value of the refrigerant circulation flow and the fluctuation characteristic value of the cooling water circulation flow is small, it means that the system operates smoothly, and the basic refrigeration demand is mainly maintained by adjusting the main cooling water circulation; when the difference is large, it means that the system load has changed significantly, and additional cooling capacity is provided by increasing the auxiliary cooling water circulation flow. This control strategy based on fluctuation characteristic value can realize the precise allocation of cooling capacity and avoid the energy waste caused by uneven distribution of cooling capacity in traditional control methods. Practice has proved that under the condition of 24-hour continuous operation of the roasting furnace, this control method can increase the coefficient of refrigeration (COP) of the lithium bromide unit by more than 15%, and at the same time control the temperature fluctuation within the range of ±0.5℃, providing a stable temperature and humidity environment for the shell making process.

[0045] S3: The chilled water is transported 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.

[0046] Specifically, the steps of controlling the temperature and humidity of the shell making drying area by a constant temperature and humidity unit include: The supply capacity of 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 refluxed to the lithium bromide unit after heat exchange through the constant temperature and humidity unit to form a cycle; Exemplarily, the specific steps of the system operation include: Step 1: System startup phase. First, detect the environmental parameters of the shell drying area. When the temperature is detected to be outside the range of 20-27°C or the humidity is outside the range of 40-70%, start the system. When starting, 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 rate of the chilled water have reached the set value; 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; Step 3: Temperature and humidity control. Use constant temperature and humidity units to control the surface layer area and the back layer area separately: 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%; For the back layer area, the temperature is controlled within the range of 20-27°C and the humidity is controlled within the range of 40-60%; When the temperature and humidity fluctuate, the system first adjusts the supply air temperature, then the fresh air ratio, and finally the humidification amount; Step 4: Handling abnormal situations: 1) When insufficient supply capacity is detected, the system automatically switches to the backup cooling source; 2) When it is detected that the temperature and humidity are out of the control range, the system will send out an alarm signal and record abnormal data; 3) When abnormal chilled water temperature is detected, the system automatically adjusts the pump speed and limits the maximum load; Step 5: System stop. When the system needs to be stopped, first reduce the refrigeration load. When the system load drops below 30%, gradually reduce the water pump speed and finally turn off the circulating water pump.

[0047] In summary, the present invention solves the problem that the waste gas supply cannot be adjusted 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 feature analysis, the prediction and precise control of the system operating state are achieved, overcoming the lag 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 allocation 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.

[0048] 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: The waste gas distribution module is used to collect the high-temperature waste gas discharged from the roasting furnace. The high-temperature waste gas is transported to the lithium bromide unit through the high-temperature waste gas delivery pipeline. The high-temperature waste 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 waste gas selectively enters the bypass channel or the lithium bromide unit; 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; 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 drying area through the constant temperature and humidity unit.

[0049] Example 3, reference Figure 4, is an embodiment of the present invention, which is different from the previous embodiment in that: if the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0050] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0051] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), 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 disk read-only memory (CDROM). In addition, the computer-readable medium may even be a 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, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0052] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0053] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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: The 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; 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 generate chilled water; The chilled water is transported 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.

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 comprises 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 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.

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 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.

4. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 3 is characterized in that: 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: A cooling capacity function per unit time is established based on the fluctuation characteristic value of the refrigerant circulation flow rate, a heat dissipation function per unit time is established based on the fluctuation characteristic value of the cooling water circulation flow rate, and a relationship between the cooling capacity function and the heat dissipation function is calculated to obtain a waste heat utilization index; 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 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 meets the second setting 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 a second opening, 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.

5. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 4 is characterized in that: 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 situations 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 refers to 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 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.

6. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 5 is characterized in that: The step of heat exchanging the high-temperature exhaust gas by the lithium bromide unit comprises: 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, driving the refrigerant to circulate between the condenser, the evaporator and the absorber, and the circulating flow of the refrigerant generates 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, wherein 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; 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.

7. The casting constant temperature and humidity control method based on roasting furnace waste heat recovery according to claim 6, characterized in that: The steps of controlling the temperature and humidity of the shell making drying area by the constant temperature and humidity unit include: The supply capacity of the chilled water is calculated according to the fluctuation characteristic values ​​of the refrigerant circulation flow rate and the cooling water circulation flow rate, and the rotation speed of the circulating water pump is adjusted according to the supply capacity. The chilled water flows back to the lithium bromide unit after heat exchange through the constant temperature and humidity unit to form a circulation.

8. A casting constant temperature and humidity control system based on the recovery of waste heat from a roasting furnace, based on the casting constant temperature and humidity control method based on the recovery of waste heat from a roasting furnace according to any one of claims 1 to 7, 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 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; A heat energy conversion module, used to control the lithium bromide unit to perform heat exchange on the high-temperature exhaust gas, wherein the lithium bromide unit and the cooling tower form a cooling water circulation system to generate chilled water; The environment 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.

9. 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 7 are implemented.

10. 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 7 are implemented.

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