Low-energy-consumption evaporative crystallization control system for iron phosphate wastewater

Abstract

The invention relates to the technical field of evaporative crystallization control, in particular to an iron phosphate wastewater low-energy-consumption evaporative crystallization control system which comprises a preheating module, an evaporation concentration module, a steam circulation module, a steam detection module, a salt separation and recovery module and a low-energy-consumption control module. The evaporation and concentration module realizes water gradient evaporation and feed liquid concentration through evaporation units which are connected in series in multiple stages; the steam circulation module integrates a steam compressor and a steam ejector, leading equipment can be intelligently switched according to system requirements, and dual-mode operation of mechanical compression and thermal compression is achieved. The steam detection module judges the equipment state in real time by analyzing the rotating shadow and vibration waveform of the compressor and the audio waveform of the ejector; the salt separation and recovery module is used for continuously separating ammonium sulfate and monoammonium phosphate, recovering crystals and recovering condensed water for preheating; the low-energy-consumption control module dynamically adjusts the operation mode and steam parameters, and energy-saving optimization and stable control of the whole process are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of evaporation crystallization control, and particularly relates to a low-energy-consumption evaporation crystallization control system for iron phosphate wastewater. BACKGROUND

[0002] In the field of iron phosphate wastewater treatment, the traditional evaporation crystallization technology mainly relies on a single mode of energy recovery system. Among them, multiple effect evaporation (MEE) and mechanical vapor recompression (MVR) are two most common existing technical solutions.

[0003] The multiple effect evaporation system is usually composed of three or four effect evaporators in series. Its working principle is to use the secondary steam generated by the previous effect as the heat source of the next effect, and by gradually reducing the operating pressure of each effect, the boiling point of the wastewater in the corresponding effect is lowered in turn, so as to realize the multiple use of steam heat energy. The mechanical vapor recompression technology compresses all the secondary steam generated by the evaporator through a centrifugal steam compressor, and then returns to be used as the heat source of the evaporator after improving its temperature and pressure. This process only needs to input live steam when the system starts, and mainly relies on the electric drive compressor to maintain the circulation during normal operation, which can greatly reduce the dependence on external live steam in theory. However, the MVR system has very high performance requirements for the steam compressor, and its power consumption cost is high. When treating the iron phosphate wastewater which is easy to scale and corrosive, the compressor impeller and heat exchange surface are easy to scale and corrode, which leads to the decrease of system efficiency, and increases the maintenance frequency and cost. SUMMARY

[0004] Therefore, the present application provides a low-energy-consumption evaporation crystallization control system for iron phosphate wastewater, which overcomes the problem that the equipment in the prior art cannot be adaptively operated and switched, and the evaporation efficiency is easily affected under complex operating conditions, thereby reducing the recovery efficiency of the final salt content and the product quality.

[0005] To achieve the above-mentioned purpose, the present application provides a low-energy-consumption evaporation crystallization control system for iron phosphate wastewater, which comprises: a preheating module, which is used to preheat and warm the iron phosphate wastewater liquid by condensate water, and is connected to the liquid inlet of the evaporation concentration module; an evaporation concentration module, which comprises a plurality of series-connected evaporation concentration units, each of which comprises a heater and an evaporator, so as to realize the evaporation of wastewater and the output of concentrated liquid through multi-stage steam heat exchange, and the liquid outlet of the evaporation concentration module is connected to the inlet of the salt separation and recovery module; a steam cycle module, which comprises a steam compressor and a steam ejector, and selects a dominant device according to a steam inlet temperature of the evaporation and concentration module, wherein the steam compressor is used to compress secondary steam and return to the heater to realize recycling, and the steam ejector is used to mix the secondary steam with high-pressure steam to form a mixed heat source; a steam detection module, which is used to detect rotation shadow information and vibration amplitude of the steam compressor and construct a vibration amplitude time-domain waveform diagram, detect audio amplitude of the steam ejector and construct an audio amplitude time-domain waveform diagram, and determine the existence of an inefficient crystallization waveform segment according to fluctuation discrete parameters corresponding to each time-domain waveform image; a salt separation and recovery module, which is used to separate and collect ammonium sulfate crystals and monoammonium phosphate crystals, condense steam discharged from the evaporation and concentration module into condensed water, and store part of the condensed water for preheating operation of the preheating module; a low-energy consumption control module, which is used to adjust a low-consumption cycle control mode in an evaporation crystallization process according to a judgment result of the existence determination, obtain the rotation shadow information to determine whether to switch the dominant device, or directly switch the dominant device and adjust steam input parameters of the cycle evaporation and concentration module.

[0006] As the preferred technical solution of the low-energy consumption evaporation crystallization control system for the iron phosphate wastewater, the above-mentioned ammonium sulfate salt separation unit is sequentially provided with a first thickener, a first centrifuge and a first semi-automatic packing machine along a material flow direction, the first thickener inlet receives concentrated liquid output from the evaporation and concentration module, and the first centrifuge outlet is connected to the first semi-automatic packing machine inlet. The ammonium sulfate salt separation unit comprises a cooling crystallizer, a second thickener, a second centrifuge and a second semi-automatic packing machine, the cooling crystallizer inlet receives mother liquor output from the ammonium sulfate salt separation unit, the second thickener inlet is connected to the cooling crystallizer outlet, and the second centrifuge outlet is connected to the second semi-automatic packing machine inlet. The units in the salt separation and recovery module are directly connected through pipes without intervention of an intermediate storage container, and the material is subjected to salt separation treatment in a continuous flow mode.

[0007] As the preferred technical solution of the low-energy consumption evaporation crystallization control system for the iron phosphate wastewater, the steam cycle module determines the dominant device according to a steam inlet temperature of a first evaporation and concentration unit in the evaporation and concentration module. According to a judgment result that the steam inlet temperature is greater than or equal to a preset cycle temperature, the dominant device is determined to be the steam ejector. According to a judgment result that the steam inlet temperature is less than the preset cycle temperature, the dominant device is determined to be the steam compressor.

[0008] As the preferred technical scheme of the low-energy evaporation crystallization control system of the ferric phosphate wastewater, the steam detection module periodically acquires an image generation parameter peak value in each amplitude-time waveform graph of the leading equipment, calculates an average value and a standard deviation of the image generation parameter peak value, and determines a fluctuation discrete parameter of the leading equipment according to a ratio of the standard deviation to the average value. The generation parameter of the audio amplitude-time waveform graph is an audio amplitude of the steam ejector, and the generation parameter of the vibration amplitude-time waveform graph is a vibration amplitude of the steam compressor.

[0009] As the preferred technical scheme of the low-energy evaporation crystallization control system of the ferric phosphate wastewater, the steam detection module determines whether there is an inefficient crystallization waveform segment in the current leading equipment according to the fluctuation discrete parameter, including: According to a determination result that the fluctuation discrete parameter is greater than or equal to a standard discrete parameter of the corresponding leading equipment, it is determined that there is the inefficient crystallization waveform segment. According to a determination result that the fluctuation discrete parameter is less than the standard discrete parameter of the corresponding leading equipment, it is determined that there is no inefficient crystallization waveform segment.

[0010] As the preferred technical scheme of the low-energy evaporation crystallization control system of the ferric phosphate wastewater, the low-energy control module adjusts a low-energy cycle control mode in the evaporation crystallization process according to a determination result of the existence determination, including: According to a determination result that there is no inefficient crystallization waveform segment, it is determined that the low-energy cycle control mode is not adjusted. According to a determination result that there is the inefficient crystallization waveform segment, it is determined that a corresponding low-energy cycle control mode is selected based on the current leading equipment, wherein, In response to the current leading equipment being the steam compressor, it is determined whether to perform leading equipment switching according to the rotation shadow information. In response to the current leading equipment being the steam ejector, the leading equipment is directly switched and the steam input parameter of the cycle evaporation concentration module is adjusted.

[0011] As the preferred technical scheme of the low-energy evaporation crystallization control system of the ferric phosphate wastewater, the low-energy control module determines whether to perform leading equipment switching according to the rotation shadow information, including: According to a determination result that the rotation shadow information does not meet a normal rotation shadow condition, it is determined that the leading equipment needs to be switched to the steam ejector. The normal rotation shadow condition is that the width and the depth of the rotation shadow are both in a corresponding standard interval.

[0012] As a preferred technical solution of the low-energy consumption evaporation crystallization control system for iron phosphate wastewater, the low-energy consumption control module adjusts the steam input parameter of the steam circulation module to match the working interval of the dominant device in response to the direct switching dominant device.

[0013] The evaporation concentration module comprises three evaporation concentration units connected in series.

[0014] Compared with the prior art, the beneficial effects of the present application are that the system automatically selects the high-temperature section of the dominant device to enable the TVR mode according to the first-effect steam entering temperature of the evaporation concentration unit, uses the mixed heat source of high-pressure new steam and secondary steam to reduce external steam demand, switches to the MVR mode in the low-temperature section, and circulates and utilizes the secondary steam by compression to avoid heat energy waste, and real-time monitors the device state through vibration amplitude, audio amplitude and rotating shadow parameters, triggers switching to the ejector when the compressor impeller fouling or dynamic imbalance risk exceeds the standard, determines based on the radar rotating shadow width and depth standard interval, directly switches the mode when the ejector flow field is unstable and synchronously adjusts the working parameters to ensure accurate matching of heat energy supply and demand, realizes efficient utilization and dynamic balance of heat energy through two-dimensional intelligent switching, saves energy compared with the traditional fixed mode system, reduces the risk of equipment over-temperature operation, mechanical wear and tear and unplanned downtime.

[0015] Especially, in the present application, the dominant device is automatically selected according to the steam entering temperature of the first evaporation concentration unit, efficient utilization of heat energy is realized, over-temperature operation risk of the equipment is avoided through temperature threshold control, and the balance of heat energy supply and demand of the evaporation concentration and salt recovery module is ensured through the dynamic steam temperature adjustment strategy, and finally the effects of low energy consumption, high stability and long equipment life are achieved.

[0016] Especially, in the present application, the vibration amplitude and audio amplitude of the steam compressor and the steam ejector are periodically monitored, the time-domain waveform parameters are compared based on the standard discrete parameters, the running state of the dominant device is accurately diagnosed, and when the vibration / audio fluctuation discrete parameter exceeds the threshold, it is determined that there is an inefficient crystallization waveform section, thereby triggering predictive maintenance or mode switching. This mechanism not only realizes early warning of equipment failure through dynamic balance monitoring of the impeller and analysis of the acoustic characteristics of the flow field, avoids the decrease in efficiency and the increase in energy consumption caused by fouling, wear or flow field instability, but also adapts to different equipment characteristics through independent determination of two parameters, ensures stable and efficient operation of the core power unit, and finally achieves the comprehensive beneficial effects of improving system reliability, prolonging equipment life, reducing maintenance cost and optimizing energy consumption.

[0017] Especially, in the present application, through the intelligent judgment of the low-efficiency crystallization waveform segment and the cooperative optimization of the leading device response strategy, the dynamic low-consumption control of the evaporation crystallization process is realized. When a low-efficiency crystallization waveform segment is detected, the system differentiates the control strategy according to the current leading device type: for the steam compressor, a rotating shadow information secondary verification mechanism is adopted to accurately identify the risk of impeller fouling or dynamic imbalance, thereby avoiding false switching; for the steam ejector, mode switching is directly triggered, and the steam temperature, pressure and flow parameters are simultaneously adjusted to ensure the balance of heat energy supply and demand and the safe operation of the device after TVR / MVR mode switching. The present application not only reduces the invalid energy consumption, but also improves the system anti-interference ability and operation stability through device-level fault isolation and parameter adaptive matching, ultimately achieving the multi-dimensional beneficial effects of energy saving, reducing consumption, prolonging device life, reducing unplanned downtime and optimizing salt separation efficiency.

[0018] Especially, in the present application, through the linear frequency modulation continuous wave radar real-time monitoring of the width and depth of the rotating shadow of the steam compressor impeller, combined with the historical data confidence interval setting of the normal condition threshold, accurate device state diagnosis and intelligent response are realized. When the rotating shadow is abnormal, it is automatically switched to the steam ejector mode to avoid efficiency decay and device damage caused by impeller fouling and dynamic imbalance; when the state is normal, the secondary steam temperature is dynamically optimized according to the fluctuation discrete parameter to reduce droplet carrying, suppress salt analysis and liquid impact risk, improve compression efficiency and block the efficiency decline caused by fouling, so as to break the vicious cycle of rising energy consumption. The present application not only realizes early warning and fault isolation of the impeller state through non-contact radar technology, but also ensures the safe operation of the device through temperature parameter cooperative optimization, ultimately achieving the effects of energy saving, reducing consumption, prolonging device life, reducing unplanned downtime and improving salt separation quality. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a structural schematic diagram of the low-energy evaporation crystallization control system for iron phosphate wastewater in the embodiment of the present application; Figure 2 FIG. 2 is a structural schematic diagram of the salt separation recovery module in the embodiment of the present application; Figure 3 FIG. 3 is a logic diagram of adjusting the low-consumption circulation control mode in the evaporation crystallization process in the embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the purpose and advantages of the present application clearer and more apparent, the present application will be further described below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0021] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and do not limit the protection scope of the present application.

[0022] It should be noted that in the description of the present application, the terms indicating the direction or positional relationship of "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0023] In addition, it should also be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] Please refer to Figure 1 The figure is a structural schematic diagram of the low-energy evaporation crystallization control system for iron phosphate wastewater according to the embodiment of the present application. The present application provides a low-energy evaporation crystallization control system for iron phosphate wastewater, which comprises: A preheating module, which is used to preheat and warm up the iron phosphate wastewater feed liquid by condensate water, and is connected to the feed liquid inlet of the evaporation and concentration module; An evaporation and concentration module, which comprises a plurality of series-connected evaporation and concentration units, each of which comprises a heater and an evaporator, to realize the evaporation of wastewater moisture and the output of concentrated liquid through multi-stage steam heat exchange, and the feed liquid outlet of which is connected to the inlet of the salt separation and recovery module; A steam circulation module, which comprises a steam compressor and a steam ejector, and the main equipment is selected according to the steam inlet temperature of the evaporation and concentration module, wherein the steam compressor is used to compress secondary steam and return to the heater to realize recycling, and the steam ejector is used to form a mixed heat source by mixing high-pressure steam with secondary steam; A steam detection module, which is used to detect the rotation shadow information and vibration amplitude of the steam compressor and construct a vibration amplitude time-domain waveform diagram, detect the audio amplitude of the steam ejector and construct an audio amplitude time-domain waveform diagram, and make existence determination of low-efficiency crystallization waveform section according to the fluctuation discrete parameters corresponding to each time-domain waveform image; A salt separation and recovery module, which is used to separate and collect ammonium sulfate crystals and monoammonium phosphate crystals, condense the steam discharged from the evaporation and concentration module into condensate water, and store part of the condensate water for preheating operation of the preheating module; A low-energy consumption control module is used to adjust the low-energy consumption cycle control mode in the evaporation crystallization process according to the determination result of the presence determination, obtain the rotating shadow information to determine whether to switch the leading equipment, or directly switch the leading equipment and adjust the steam input parameter of the circulating evaporation concentration module.

[0025] The application automatically selects the leading equipment high-temperature section to start the TVR mode according to the primary effect steam inlet temperature of the evaporation concentration unit, uses the high-pressure new steam and secondary steam to mix to form a heat source, reduces the external steam demand, switches to the MVR mode in the low-temperature section, compresses and heats the secondary steam by the compressor for recycling, avoids the waste of heat energy, monitors the equipment state in real time through the vibration amplitude, audio amplitude and rotating shadow parameters, determines based on the radar rotating shadow width and depth standard interval when the compressor impeller is scaled or the dynamic imbalance risk exceeds the standard, triggers the switch to the ejector, directly switches the mode when the flow field of the ejector is unstable and synchronously adjusts the working parameters, and ensures the accurate matching of the heat energy supply and demand. The application realizes the efficient utilization and dynamic balance of the heat energy through the two-dimensional intelligent switching, saves energy compared with the traditional fixed mode system, reduces the risk of over-temperature operation, mechanical wear and tear and unplanned shutdown of the equipment.

[0026] Please refer to Figure 2 The salt separation and recovery module includes an ammonium sulfate separation unit and an ammonium phosphate separation unit. The first thickener receives the concentrated liquid output by the evaporation concentration module, and the outlet of the first centrifuge is connected to the inlet of the first semi-automatic packing machine. The ammonium phosphate separation unit includes a cooling crystallizer, a second thickener, a second centrifuge and a second semi-automatic packing machine, the inlet of the cooling crystallizer receives the mother liquor output by the ammonium sulfate separation unit, the inlet of the second thickener is connected to the outlet of the cooling crystallizer, and the outlet of the second centrifuge is connected to the inlet of the second semi-automatic packing machine. The units of the salt separation and recovery module are directly connected through pipes without intervention of intermediate storage containers, and the materials are processed in a continuous flow mode.

[0027] In the implementation, the concentrated liquid output by the evaporation concentration module enters the first thickener, and the ammonium sulfate crystals and the mother liquor are preliminarily separated through gravity settling. The concentrated slurry after the preliminary separation is transported to the first centrifuge for secondary solid-liquid separation, and the separated ammonium sulfate crystals are compressed and formed into solid products by the first semi-automatic packing machine. The mother liquor discharged from the centrifuge is directly transported to the ammonium phosphate separation unit through a pipe, and the monomethylamine precursor component is retained in the mother liquor.

[0028] The mother liquor discharged from the ammonium sulfate fractional separation unit enters a cooling crystallizer, and ammonium phosphate crystals are precipitated by cooling to the ammonium phosphate crystallization temperature range. The slurry containing the crystals is transported to a second thickener for secondary sedimentation concentration, and the thick slurry is subjected to solid-liquid separation in a second centrifuge. The separated ammonium phosphate crystals are shaped into solid products by a second semi-automatic packing machine, and the tail liquid discharged from the centrifuge is discharged through a pipeline discharge system or enters a subsequent wastewater treatment unit.

[0029] The concentrated liquid is subjected to ammonium sulfate crystal sedimentation in the first thickener, and the upper clear liquid is a mother liquor containing ammonium phosphate precursors. After the mother liquor is cooled in the cooling crystallizer, ammonium phosphate crystals are precipitated to form a solid-liquid mixed slurry. The slurry is further concentrated by sedimentation in the second thickener, and the upper clear liquid is a suspension containing a small amount of crystals. After the thick slurry output from the second thickener is separated by the second centrifuge, solid ammonium phosphate products and salt-containing tail liquid are obtained. The final products are ammonium sulfate solids and ammonium phosphate solids, and the tail liquid is wastewater containing a small amount of sodium sulfate and phosphate. The selection of the above equipment is not specifically limited.

[0030] Specifically, the steam circulation module determines the dominant equipment according to the steam inlet temperature of the first evaporation and concentration unit in the evaporation and concentration module; According to the determination result that the steam inlet temperature is greater than or equal to the preset circulation temperature, the dominant equipment is determined to be a steam ejector; According to the determination result that the steam inlet temperature is less than the preset circulation temperature, the dominant equipment is determined to be a steam compressor.

[0031] In implementation, the preset circulation temperature is 100-115℃. The MVR mode is a steam compressor dominant circulation mode, and the TVR mode is a steam ejector dominant circulation mode.

[0032] It can be understood that in the MVR mode, the secondary steam generated by the evaporator is only 60-90℃, and must be first subjected to work by the steam compressor to simultaneously increase the pressure and temperature, so that it can be sent back to the first heater, and therefore the steam temperature entering the heater is increased to about 100-110℃. In the TVR mode, the primary new steam sent by the boiler itself has 0.35-0.6 MPa and 140-160℃, and after mixing with part of the secondary steam in the ejector, the temperature is higher than that of the secondary steam. The mixed steam usually reaches 115-125℃ when entering the first heater, so there is a clear temperature difference of 5-15℃ at the inlet of the same heater in the two modes.

[0033] In the present application, the dominant device is automatically selected according to the steam inlet temperature of the first evaporation concentration unit, realizing high-efficiency utilization of thermal energy in stages, avoiding the risk of over-temperature operation of the device through temperature threshold control, and guaranteeing the balance between heat supply and demand of the evaporation concentration and salt separation recovery modules through a dynamic steam temperature adjustment strategy, ultimately achieving the effects of low energy consumption, high stability and long device life.

[0034] Referring to Figure 3 As shown in the logic diagram of the low-consumption cycle control mode in the evaporation crystallization process adjusted by the embodiment of the present application, the steam detection module periodically obtains the image generation parameter peak value in each amplitude time-domain waveform diagram of the dominant device, calculates the average value and standard deviation of the image generation parameter peak value, and determines the fluctuation dispersion parameter of the dominant device according to the ratio of the standard deviation to the average value. The generation parameter of the audio amplitude time-domain waveform diagram is the audio amplitude of the steam ejector, and the generation parameter of the vibration amplitude time-domain waveform diagram is the vibration amplitude of the steam compressor.

[0035] In implementation, the time interval corresponding to the time-domain waveform image is 1h. It can be understood that, as the core of the MVR mode, the steam compressor is prone to high-frequency vibration or local overheating due to thermal stress and lubrication failure of high-speed rotating components such as impellers and bearings. Monitoring every hour can capture early signs of failure and avoid equipment failure caused by bearing wear and gear fatigue. For example, when the bearing temperature exceeds 80℃, the viscosity of the lubricating oil decreases, and the risk of lubrication failure increases significantly, so the device needs to be shut down for maintenance immediately.

[0036] Analyzing at a time interval of hours can deal with sudden failures, realize emergency shutdown protection, prevent destructive damage to the device, avoid unnecessary loss of raw materials caused by subsequent production inefficiency, and reduce energy consumption of the remaining devices.

[0037] Specifically, the steam detection module determines whether there is an inefficient crystallization waveform segment in the current dominant device according to the fluctuation dispersion parameter, including: According to the determination result that the fluctuation dispersion parameter is greater than or equal to the standard dispersion parameter of the corresponding dominant device, it is determined that there is an inefficient crystallization waveform segment. According to the determination result that the fluctuation dispersion parameter is less than the standard dispersion parameter of the corresponding dominant device, it is determined that there is no inefficient crystallization waveform segment.

[0038] In implementation, the standard dispersion parameter includes an audio standard dispersion parameter and a vibration standard dispersion parameter, and the fluctuation dispersion parameter includes a vibration fluctuation dispersion parameter and an audio fluctuation dispersion parameter.

[0039] The vibration standard dispersion parameter is set for the steam compressor. As a high-speed rotating machine, the operation state of the steam compressor is closely related to the dynamic balance of the impeller. When the impeller is scaled, worn or unbalanced, the mass distribution of the impeller will change, and under high-speed rotation, a periodically changing centrifugal force is generated. This physical change will directly and sensitively reflect on the vibration signal of the machine body. The fluctuation dispersion parameter of the vibration time-domain waveform image is used to quantify the degree of deviation of the vibration signal from stability, so as to determine the state of the impeller in the steam compressor. The larger the parameter, the clearer it indicates that the scaling of the impeller has caused uneven mass distribution, or mechanical wear of the rotating parts such as the bearing, which has intensified the vibration of the whole machine, reduced the operation stability, and further led to reduced compression efficiency and increased energy consumption.

[0040] The vibration standard dispersion parameter is determined according to the average value of the vibration fluctuation dispersion parameter in the historical data of the steam compressor in the normal working state.

[0041] The audio standard dispersion parameter is set for the steam ejector. The steam ejector is a static device without moving parts, and its core is to generate a high-speed steam jet through a Laval nozzle to form a negative pressure. Its working state is mainly determined by the stability of the internal flow field. When the nozzle shape changes due to scaling or the size changes due to wear, it will disrupt the stable flow of steam, causing vortex, surge and other phenomena. These abnormal fluid dynamics cannot be effectively captured by vibration, but will directly change the acoustic characteristics of the device when it is running. The normal and smooth steam sound will become sharp, intermittent or dull. By constructing the time-domain waveform of the audio signal and calculating its fluctuation dispersion parameter, the degree of disorder of this acoustic characteristic can be accurately quantified. The larger the parameter, the more clearly it indicates that the internal flow field of the ejector is unstable, the nozzle efficiency is reduced or there is a blockage, which leads to a decrease in the mixing efficiency of the ejector and the inability to provide a stable and sufficient heat source steam for the system.

[0042] The audio standard dispersion parameter is determined according to the average value of the audio fluctuation dispersion parameter in the historical data of the steam ejector in the normal working state.

[0043] It can be understood that setting two independent standard dispersion parameters is essentially setting the most suitable judgment parameters for the fault characteristics of two different devices. By determining these two key parameters, the system can achieve comprehensive, accurate and early diagnosis of the operation state of the core power unit, thereby providing reliable data support for timely predictive maintenance and energy efficiency optimization.

[0044] In the present application, the vibration amplitude of the steam compressor and the audio amplitude of the steam ejector are periodically monitored to obtain time-domain waveform parameters, and the fluctuation discrete parameters are compared based on standard discrete parameters to accurately diagnose the running state of the dominant equipment. When the vibration / audio fluctuation discrete parameter exceeds the threshold, it is determined that there is an inefficient crystallization waveform segment, thereby triggering predictive maintenance or mode switching. This mechanism not only realizes early warning of equipment failure through impeller dynamic balance monitoring and flow field acoustic characteristic analysis, avoiding efficiency decline and energy consumption increase caused by scaling, wear or flow field instability, but also adapts to different equipment characteristics through independent judgment of two parameters, ensuring stable and efficient operation of the core power unit, and ultimately achieving the comprehensive benefits of improving system reliability, prolonging equipment life, reducing maintenance cost and optimizing energy consumption.

[0045] Specifically, the low-energy consumption control module adjusts the low-energy consumption cycle control mode during the evaporation crystallization process according to the judgment result of the existence determination, including: According to the determination result that the low-efficiency crystallization waveform segment does not exist, it is determined not to adjust the low-energy consumption cycle control mode; According to the determination result that the low-efficiency crystallization waveform segment exists, a corresponding low-energy consumption cycle control mode is selected based on the current dominant equipment, wherein, In response to the current dominant equipment being a steam compressor, it is determined whether to switch the dominant equipment according to the rotating shadow information; In response to the current dominant equipment being a steam ejector, the dominant equipment is directly switched and the steam input parameters of the circulating evaporation concentration module are adjusted.

[0046] In implementation, the low-energy consumption control module switches the steam circulation path between MVR mode and TVR mode, adjusts the steam compressor and steam ejector inlet pipeline on-off through the control valve, and adaptively coordinates the operating parameters of each equipment after mode switching, to ensure that the system stably realizes wastewater treatment and salt separation function in MVR or TVR mode.

[0047] In the present application, through the intelligent determination of the low-efficiency crystallization waveform segment and the cooperative optimization of the dominant equipment response strategy, dynamic low-energy consumption control of the evaporation crystallization process is realized. When the low-efficiency crystallization waveform segment is detected, the system differentiates the control strategy according to the current dominant equipment type: for the steam compressor, a rotating shadow information secondary verification mechanism is adopted to accurately identify the risk of impeller scaling or dynamic imbalance and avoid false switching; for the steam ejector, mode switching is directly triggered and the steam temperature, pressure and flow parameters are adjusted synchronously to ensure the balance of heat energy supply and demand and the safe operation of the equipment after TVR / MVR mode switching. The present application not only reduces invalid energy consumption, but also improves the system anti-interference ability and operation stability through equipment-level fault isolation and parameter adaptive matching, ultimately achieving the multi-dimensional benefits of energy saving, prolonging equipment life, reducing unplanned downtime and optimizing salt separation efficiency.

[0048] Specifically, the low-energy consumption control module determines that the leading device needs to be switched to the steam ejector according to a determination result that the rotation shadow information does not meet the normal rotation shadow condition. The normal rotation shadow condition is that the width and the depth of the rotation shadow are in corresponding standard intervals.

[0049] In implementation, the rotation shadow information is obtained by a linear frequency modulation continuous wave radar. The radar transmits a continuous wave with a linearly changing frequency. The instantaneous distance of the target object is accurately determined by calculating the frequency difference between the transmission and the received echo. For the rotating impeller, it can continuously measure the distance between the radar probe and each blade tip. A time-varying and accurate distance waveform is obtained. Each trough corresponds to the point where the blade tip is closest to the probe, and each waveform represents the rotation shadow generated by a blade, i.e., the rotation shadow information.

[0050] The rotation shadow width is obtained by the duration of the radar echo pulse, which is mainly affected by the effective reflection area of the blade tip when passing through the radar beam cross section. The accumulation of substances on the edge of the blade caused by impeller fouling increases the effective reflection area, thereby significantly increasing the pulse width.

[0051] The rotation shadow depth is reflected by the amplitude or intensity of the radar echo pulse, which mainly reflects the integrity and alignment of the blade tip reflection surface. When the blade is damaged, curled or severely contaminated, the reflected signal will weaken, and the pulse depth or / amplitude will decrease or show abnormal fluctuations.

[0052] The width standard interval and the depth standard interval are determined according to the confidence intervals of the corresponding shadow width interval and shadow depth interval when the steam compressor works normally according to historical working data.

[0053] If the rotation shadow information meets the normal rotation shadow condition, the low-energy consumption control module increases the temperature of the secondary steam. The increase is determined according to the difference between the fluctuation discrete parameter and the standard discrete parameter and the current temperature of the secondary steam, and the increased secondary steam will not cause damage to the equipment.

[0054] Increasing the temperature of the steam away from the saturation state can make the tiny droplets suspended in the steam evaporate into gas quickly, thereby reducing the number and size of the droplets from the source. The temperature rise ensures that the droplets evaporate before hitting the blade or evaporate immediately after hitting the blade, leaving no time for salt analysis.

[0055] It can be understood that if the imported secondary steam carries liquid droplets, liquid impact will occur, which will seriously damage the impeller, thereby causing the impeller to be scaled and affecting dynamic balance to cause severe vibration, blade notches or curling to reduce the steam flow area, change the angle of attack, cause the leakage in the compressor to increase, and the isentropic efficiency to decrease; under the same evaporation load, the required motor current increases, the energy consumption increases linearly, and the efficiency decreases, which means that the compression temperature rise is insufficient, the steam temperature of the primary heater is 3-8℃ lower than the design value, the evaporation capacity decreases, the system is forced to operate at a reduced load, and in severe cases, the three-effect gradient cannot be maintained, the discharge density decreases, the ammonium sulfate crystals become thin, the evaporation capacity is insufficient, the residence time of the concentrated liquid is prolonged, the supersaturation degree is increased, and the scaling of the inner wall of the heating pipe is accelerated; at the same time, the secondary steam quantity is reduced, the suction inlet pressure of the steam ejector is increased, and the injection ratio is decreased, and the system falls into a vicious cycle of more blocked and more rotating, and more rotating and more blocked, and finally the whole line is shut down for cleaning. In addition, the loss of balance of the impeller causes coaxial vibration, and long-term vibration will cause the raceway of the high-speed bearing to peel off and the graphite ring of the dry gas seal to break, and the maintenance cost increases from replacing the impeller to replacing the impeller, bearing and seal.

[0056] The radar probe continuously emits microwaves to the rotating impeller through the waveguide window and receives the echo. When each blade tip passes, a strongest echo signal is generated, forming a periodic pulse on the range-time graph, and the pulse is the radar shadow of the blade. If the depth, width and period of all pulses are highly consistent, it indicates that the blade of the steam compressor is normal, otherwise, if the blade is thickened due to scaling, the duration of the tip shadow on the radar, i.e. the pulse width, will be longer, and the change in the shape of the blade will cause the change in the shape of the pulse.

[0057] In the present application, the width and depth of the rotating shadow of the steam compressor impeller are monitored in real time by the linear frequency modulation continuous wave radar, the normal condition threshold is set by combining historical data confidence interval, precise diagnosis and intelligent response of the equipment state are realized, the steam ejector mode is automatically switched when the rotating shadow is abnormal, the efficiency decay and equipment damage caused by impeller scaling and dynamic imbalance are avoided; when the state is normal, the secondary steam temperature is dynamically optimized according to the fluctuation discrete parameter, the liquid droplet carrying, salt analysis and liquid impact risks are reduced, the compression efficiency is improved, and the vicious cycle of energy consumption increase caused by efficiency decline is blocked, the present application not only realizes early warning and fault isolation of the impeller state by the non-contact radar technology, but also ensures the safe operation of the equipment through temperature parameter cooperative optimization, and finally achieves the effects of energy saving and consumption reduction, prolonging the service life of the equipment, reducing unplanned shutdown and improving the quality of salt separation.

[0058] Specifically, the low-energy-consumption control module adjusts the steam input parameter of the steam circulation module to match the working interval of the dominant device in response to the direct switching dominant device.

[0059] In the implementation, the temperature of the condensed water generated by the preheating module is introduced into the valve group to mix with high-temperature steam at the inlet of the evaporator heater, and the flash evaporation effect is used to quickly reduce the steam temperature to below 110°C, thereby avoiding over-temperature at the inlet of the compressor. A temperature sensor is used to monitor the steam temperature at the inlet of the compressor in real time, and a feedback signal is fed back to the low-energy-consumption control module. If the temperature is still higher than 100°C, the opening of the compressor bypass valve is adjusted to divert part of the steam to the condenser for cooling, and then the steam is re-injected into the system to form a closed-loop cooling circuit.

[0060] Specifically, the evaporation concentration module comprises three evaporation concentration units connected in series.

[0061] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after the changes or replacements will fall within the protection scope of the present application.

[0062] The above description is only the preferred embodiments of the present application and is not intended to limit the present application; for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A low energy consumption evaporation crystallization control system for iron phosphate wastewater, comprising a preheating module and an evaporation concentration module comprising a plurality of evaporation concentration units, characterized in that, The application relates to a method for controlling the evaporation and concentration of a solution, and comprises the following steps: a steam circulation module, which comprises a steam compressor and a steam ejector, and the dominant device is selected according to the steam inlet temperature of the evaporation and concentration module, wherein the steam compressor is used to compress secondary steam and return to a heater to realize recycling, and the steam ejector is used to mix the secondary steam with high-pressure steam to form a mixed heat source; a steam detection module, which is used to detect the rotating shadow information and vibration amplitude of the steam compressor and construct a vibration amplitude time-domain waveform diagram, detect the audio amplitude of the steam ejector and construct an audio amplitude time-domain waveform diagram, and determine the existence of an inefficient crystallization waveform segment according to the fluctuation discrete parameter corresponding to each time-domain waveform image; a salt separation and recovery module, which is used to separate and collect ammonium sulfate crystals and monoammonium phosphate crystals, condense the steam discharged by the evaporation and concentration module into condensed water, and store part of the condensed water for preheating operation of a preheating module; a low-energy consumption control module, which is used to adjust the low-consumption circulation control mode in the evaporation and crystallization process according to the judgment result of the existence determination, obtain the rotating shadow information to determine whether the dominant device is switched or directly switch the dominant device and adjust the steam input parameters of the circulating evaporation and concentration module.

2. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 1, characterized in that, The salt separation and recovery module comprises an ammonium sulfate salt separation unit and an ammonium phosphate salt separation unit; The ammonium sulfate salt separation unit sequentially comprises a first thickener, a first centrifuge and a first semi-automatic packing machine along the material flow direction, the first thickener inlet receives concentrated liquid output by the evaporation and concentration module, and the first centrifuge outlet is connected with the first semi-automatic packing machine inlet; The ammonium phosphate salt separation unit comprises a cooling crystallizer, a second thickener, a second centrifuge and a second semi-automatic packing machine, the cooling crystallizer inlet receives mother liquor output by the ammonium sulfate salt separation unit, the second thickener inlet is connected with the cooling crystallizer outlet, and the second centrifuge outlet is connected with the second semi-automatic packing machine inlet; The units in the salt separation and recovery module are directly connected through pipelines without intervention of intermediate storage containers, and the material is separated and treated in a continuous flow mode.

3. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 1, characterized in that, The steam circulation module determines the dominant device according to the steam inlet temperature of the first evaporation and concentration unit in the evaporation and concentration module; According to the judgment result that the steam inlet temperature is greater than or equal to a preset circulation temperature, the steam ejector is determined as the dominant device; According to the judgment result that the steam inlet temperature is less than the preset circulation temperature, the steam compressor is determined as the dominant device.

4. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 3, characterized in that, The steam detection module periodically obtains the peak value of the image generation parameter in each amplitude time-domain waveform diagram of the dominant device, calculates the average value and the standard deviation of the peak value of the image generation parameter, and determines the fluctuation discrete parameter of the dominant device according to the ratio of the standard deviation to the average value. The generation parameter of the audio amplitude time-domain waveform diagram is the audio amplitude of the steam ejector, and the generation parameter of the vibration amplitude time-domain waveform diagram is the vibration amplitude of the steam compressor.

5. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 4, characterized in that, The steam detection module determines whether the current dominant device has an inefficient crystallization waveform segment according to the fluctuation discrete parameter, and the method comprises the following steps: According to the judgment result that the fluctuation discrete parameter is greater than or equal to the standard discrete parameter of the corresponding dominant device, it is determined that the inefficient crystallization waveform segment exists. According to the determination result of the fluctuation discrete parameter being less than the standard discrete parameter of the corresponding dominant device, it is determined that there is no low-efficiency crystallization waveform segment.

6. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 5, characterized in that, The low-energy consumption control module adjusts the low-consumption circulation control mode in the evaporation crystallization process according to the determination result of the existence determination, including: According to the determination result of the absence of the low-efficiency crystallization waveform segment, it is determined that the low-consumption circulation control mode is not adjusted; According to the determination result of the existence of the low-efficiency crystallization waveform segment, it is determined that the corresponding low-consumption circulation control mode is selected based on the current dominant device, wherein, In response to the current dominant device being a steam compressor, it is determined whether to perform dominant device switching according to the rotation shadow information; In response to the current dominant device being a steam ejector, the dominant device is directly switched and the steam input parameter of the circulation evaporation concentration module is adjusted.

7. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 6, characterized in that, According to the determination result of the rotation shadow information not meeting the normal rotation shadow condition, it is determined that the dominant device needs to be switched to a steam ejector; The normal rotation shadow condition is that the width and depth of the rotation shadow are within the corresponding standard interval.

8. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 6, characterized in that, In response to the direct switching of the dominant device, the low-energy consumption control module adjusts the steam input parameter of the steam circulation module to match the working interval of the dominant device.

9. The low energy consumption evaporation crystallization control system for iron phosphate wastewater according to claim 1, characterized in that, The evaporation concentration module includes three evaporation concentration units connected in series.

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