A fully automated two-stage sub-boiling acid purification system and method

Abstract

The present application relates to acidification reagent purification technical field, specifically to a kind of full-automatic two-stage sub-boiling acid purification system and method, including liquid level monitoring step: by setting weighing sensor to respective skin weight, the first, second net weight of first, second stage distillation cavity is obtained;When the first net weight or the second net weight is higher than the high limit threshold, the power supply of first stage heating device and second stage heating device is cut off simultaneously and sampling is stopped;When any one of the alarm signals of original acid bottle low liquid level switch, collection bottle high liquid level switch, leakage sensor is triggered, corresponding protection action is executed.Through the weighing sensor directly monitoring cavity mass change to judge liquid level, without penetrating cavity wall, fundamentally solve the cavity liquid level monitoring problem;Multiple sensors such as integrated weighing sensor, leakage sensor, liquid level switch, circulating water machine alarm signal, when any sensor triggers exception, system automatically executes corresponding protection action, eliminates dry burning, leakage and other security risks.

Description

Technical Field

[0001] This invention relates to the field of acidification reagent purification technology, specifically to a fully automated two-stage sub-boiling acid purification system and method. Background Technology

[0002] In semiconductor manufacturing, trace element analysis, life sciences, and cutting-edge research, the purity of the acid reagents used directly affects the accuracy of analytical results and the yield of products. Typically, the content of key metal impurities is required to be below 0.3 ppb. Sub-boiling distillation, which involves evaporation at a temperature 10-20°C below the acid's boiling point, effectively suppresses the entrainment of impurities by droplets and is the mainstream method for preparing ultra-high purity acids.

[0003] Currently, there are various acid purification devices on the market, such as the DuoPUR sub-boiling distillation system and the Aimer AP400 fully automated sub-boiling cascade acid purifier. The existing technologies that are closest to this invention mainly include the following categories: Such devices have a simple structure, consisting of a single distillation chamber, a heating element, and a condensation system. The evaporation process takes place at a temperature below the acid's boiling point, effectively suppressing droplet entrainment. However, the removal of impurities after a single distillation is limited, making it difficult to meet electronic-grade purity requirements. For example, patent application CN107441750A discloses a sub-boiling distillation device and its application, which uses the falling film evaporation principle for sub-boiling distillation. However, this device is a single-stage distillation structure, and impurities are not completely removed after a single distillation.

[0004] Patent application CN201910258472.X discloses a sub-boiling acid distillation purifier, comprising a crude acid reagent bottle for holding the crude acid solution to be purified and a pure acid reagent bottle for holding the purified pure acid solution. The crude acid reagent bottle is equipped with an adjustable temperature heating device. This device is a single-stage structure, relies on an external water source for cooling, and lacks liquid level monitoring and automatic control functions.

[0005] The Aimole AP400 fully automated sub-boiling cascade acid purifier employs cascade sub-boiling distillation technology, upgrading traditional single-stage distillation to a series-connected two-stage distillation. This equipment features automatic acid addition, pure acid collection, waste acid discharge, and pure water rinsing. However, this solution still has the following shortcomings: the liquid level sensor needs to penetrate the purification container wall for monitoring; there is no external cooling or the cooling effect is affected by the environment; and the automatic cleaning function is not clearly described.

[0006] In summary, the existing technology still has the following problems: First, the distillation chamber made of PTFE / PFA material suffers severe signal attenuation from non-contact liquid level sensors such as ultrasonic and radar sensors, while contact liquid level sensors need to penetrate the chamber wall or directly contact the acid, which poses a risk of sealing failure and contamination; Second, the safety monitoring measures are relatively simple, usually only equipped with a low liquid alarm. Once the sensor fails or a leak occurs, it is impossible to stop the machine in time, which poses a safety hazard of dry burning and leakage; Third, some devices use peristaltic pumps or transfer pumps for sample injection. The metal parts inside the pump body are easily corroded in the acidic environment, releasing metal ions that contaminate the acid. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the present invention aims to provide a fully automated two-stage sub-boiling acid purification system and method, which aims to achieve non-contact accurate liquid level detection through weighing liquid level monitoring, construct complete safety protection through a multi-sensor safety interlock system, and simultaneously realize two-stage series distillation and metal-free sample injection.

[0008] To achieve the above objectives, the present invention provides a control method for a fully automated two-stage sub-boiling acid purification system, comprising the following steps: S1. Liquid level monitoring steps: The first mass signal of the first distillation chamber is obtained in real time by the first weighing sensor set below the first distillation chamber, and the second mass signal of the second distillation chamber is obtained in real time by the second weighing sensor set below the second distillation chamber. The first net weight and the second net weight are obtained by subtracting their respective tare weights. S2. Safety Interlock Steps: The alarm signals from the first weighing sensor, the second weighing sensor, the low-level switch of the original acid bottle, the high-level switch of the collection bottle, the leakage sensor, and the circulating water machine are used as safety interlock input signals and connected to the control unit. The control unit executes the following interlock logic based on each input signal: When the first net weight is lower than the first minimum threshold, the power supply to the first-stage heating device is cut off; when the second net weight is lower than the second minimum threshold, the power supply to the second-stage heating device is cut off; when the first net weight or the second net weight is higher than the maximum threshold, the power supply to both the first-stage and second-stage heating devices is cut off and the sample injection is stopped; when any one of the low liquid level switch of the original acid bottle, the high liquid level switch of the collection bottle, the leakage sensor, or the alarm signal of the circulating water machine is triggered, the corresponding protection action is executed. S3. Injection control steps: When the first net weight is lower than the injection start threshold, the control unit controls the injection valve to open and uses air pressure to push the raw acid from the raw acid storage bottle to the first stage distillation chamber until the first net weight reaches the injection stop threshold and the injection valve is closed.

[0009] As a further improvement to this technical solution, the corresponding protection action in step S2 includes: When the low level switch of the original acid bottle is triggered, the control unit stops the sample injection and issues an alarm; When the high liquid level switch of the collection bottle is triggered, the control unit cuts off the power supply to the first-stage heating device and the second-stage heating device, stops the sample injection, and issues an alarm. When the leakage sensor is triggered, the control unit executes an emergency system stop and issues an alarm; When the low liquid alarm signal or high temperature alarm signal of the circulating water machine is triggered, the control unit cuts off the power supply to the first-stage heating device and the second-stage heating device and issues an alarm.

[0010] As a further improvement to this technical solution, a self-cleaning step is also included: in response to a one-button cleaning command, the control unit controls the cleaning pump to start, and simultaneously opens the first cleaning water inlet valve and the second cleaning water inlet valve to inject ultrapure water into the first-stage distillation chamber and the second-stage distillation chamber, respectively; after the water injection is completed, the cleaning pump and the cleaning water inlet valve are closed, the first cleaning drain valve and the second cleaning drain valve are opened, and the waste pump is started to drain the cleaning waste liquid. The control unit monitors the emptying progress in real time through the first weighing sensor and the second weighing sensor. When both the first net weight and the second net weight are lower than the emptying completion threshold and remain so for a predetermined time, the emptying is determined to be complete.

[0011] As a further improvement to this technical solution, the first lower threshold is 15g, the second lower threshold is 50g, the upper threshold is 650g, the injection start threshold is 50g, and the injection stop threshold is 700g.

[0012] On the other hand, the present invention provides a fully automatic two-stage sub-boiling acid purification system and a control method for the above-mentioned fully automatic two-stage sub-boiling acid purification system, including a movable trolley-type frame, the frame being divided into an upper layer and a lower layer; the lower layer has a raw acid storage bottle and a finished product collection bottle arranged side by side at the front. The purification unit is located at the rear of the frame and is staggered vertically. The purification unit includes a first-stage distillation chamber and a second-stage distillation chamber. The installation position of the first-stage distillation chamber is higher than that of the second-stage distillation chamber. The outlet of the first-stage distillation chamber is connected to the inlet of the second-stage distillation chamber through a pipeline, so that the distillate flows into the second-stage distillation chamber by gravity. The first weighing sensor is located below the single-leg support point of the first-stage distillation chamber and is used to monitor the mass change of the first-stage distillation chamber in real time. The second weighing sensor is located below the single-leg support point of the second-stage distillation chamber and is used to monitor the mass change of the second-stage distillation chamber in real time. The low-level switch for the raw acid bottle is located on the outside of the raw acid storage bottle wall; The high-level switch for the collection bottle is located on the outside of the finished product collection bottle wall; A leakage sensor is installed at the lowest point of the chassis of the frame; A circulating water machine is installed on the lower layer of the frame. The circulating water machine is connected to the cooling interfaces of the first-stage distillation chamber and the second-stage distillation chamber through cooling water pipes to form a fully enclosed circulating cooling loop. The circulating water machine has a liquid shortage alarm signal output terminal and a high temperature alarm signal output terminal. The control unit is connected to the signal input terminal of the first weighing sensor, the second weighing sensor, the low liquid level switch of the original acid bottle, the high liquid level switch of the collection bottle, the leakage sensor, and the alarm signal output terminal of the circulating water machine. The control output terminal of the control unit is connected to the first stage heating device, the second stage heating device, and the injection valve. The control unit is configured to execute the control method described above.

[0013] As a further improvement to this technical solution, a pneumatically driven sample injection system is also included: the original acid storage bottle is equipped with a quick-change cap, which includes an inner cap and an outer cap. The inner cap is fixedly connected to an air inlet pipe and a liquid inlet pipe, and the outer cap is threaded into the bottle mouth and can rotate independently relative to the inner cap; the air inlet pipe is connected in sequence to a gas purification component, a pressure reducing valve, and a sample injection valve before being connected to an external gas source; the liquid inlet pipe is connected to the liquid inlet of the first-stage distillation chamber; the entire sample injection path is made of only PFA material.

[0014] As a further improvement to this technical solution, the high liquid level switch of the collection bottle consists of two redundant liquid level sensors, and the collection bottle is determined to be full when either sensor is triggered.

[0015] As a further improvement to this technical solution, a self-cleaning subsystem is also included: the inlet of the cleaning pump is connected to an ultrapure water storage tank, and the outlet is connected to the top cleaning port of the first-stage distillation chamber and the top cleaning port of the second-stage distillation chamber via a first cleaning inlet valve and a second cleaning inlet valve, respectively; the inlet of the waste discharge pump is connected to the bottom drain port of the first-stage distillation chamber and the bottom drain port of the second-stage distillation chamber via a first cleaning drain valve and a second cleaning drain valve, respectively, and the outlet of the waste discharge pump is connected to a waste liquid collection tank; the first cleaning inlet valve, the second cleaning inlet valve, the first cleaning drain valve, and the second cleaning drain valve are all pneumatic diaphragm valves, and their control terminals are respectively connected to the control unit.

[0016] As a further improvement to this technical solution, both the first-stage heating device and the second-stage heating device are infrared radiation heating lamps, which are located below the bottom of the corresponding distillation chamber and do not contact the chamber.

[0017] As a further improvement to this technical solution, the purification host also includes a metal isolation chamber, the control unit is disposed inside the metal isolation chamber, and the metal isolation chamber is physically isolated from the pipeline space of the purification host; the cables extending from the metal isolation chamber to each actuator are all covered with PFA or PTFE sleeves.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This fully automated two-stage sub-boiling acid purification system and method uses a weighing sensor to directly monitor changes in the chamber mass to determine the liquid level. It does not require penetration of the PTFE / PFA chamber wall, is unaffected by acid mist interference, and offers high accuracy and long-term stability, fundamentally solving the problem of PTFE / PFA chamber liquid level monitoring. It integrates multiple sensors, including a weighing sensor, a leakage sensor, a liquid level switch, and a circulating water machine alarm signal, constructing a complete safety protection system. When any sensor triggers an abnormality, the system automatically executes the corresponding protection action, eliminating safety hazards such as dry burning and leakage. Its safety and reliability are far superior to existing solutions with single-protection mechanisms.

[0019] 2. This fully automated two-stage sub-boiling acid purification system and method uses pneumatically driven sample injection. The entire sample injection path contains no metal parts, eliminating metal contamination such as Fe and Cr from the source. The metal-free sample injection ensures ultra-high purity. The water injection and emptying process is automatically completed by a pneumatic diaphragm pump, eliminating the need for manual disassembly of the chamber, making the operation simple and efficient. Attached Figure Description

[0020] The accompanying drawings described herein are for illustrative purposes only. The shapes and proportions of the components in the drawings are merely schematic and intended to aid in understanding the invention. They are not intended to specifically limit the shapes and proportions of the components of the invention.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall internal structure of the present invention; Figure 3 This is a schematic diagram of the purification host assembly structure of the present invention; Figure 4 This is a schematic diagram of the infrared heating lamp housing structure of the present invention; Figure 5 This is one of the schematic diagrams showing the location of the cleaning pump in this invention; Figure 6 This is a second schematic diagram showing the location of the cleaning pump in this invention; Figure 7 This is a flowchart of the purification system control method of the present invention; The meanings of the labels in the diagram are as follows: 1. Frame; 1-2. Raw material tank; 1-3. Collection tank; 5. First-stage distillation chamber; 5-2. First infrared heating lamp; 6. Second-stage distillation chamber; 6-1. Second infrared heating lamp; 6-2. Second-stage liquid inlet; 6-3. Second-stage liquid outlet; 6-4. Second-stage top cleaning port; 8. First weighing sensor; 9. Second weighing sensor; 11. Control unit; 11-1. Touch screen; 14. Cleaning pump. Detailed Implementation

[0022] Under the guidance of this invention, any possible variations of this invention by those skilled in the art should be considered within its scope. The directional terms used herein are based on the orientations shown in the accompanying drawings and are for ease of description and simplification; therefore, they should not be construed as limitations on the invention. Furthermore, in the description of this invention, "several" means two or more, unless otherwise explicitly specified.

[0023] Please see Figures 1-7 As shown, the present invention provides a fully automatic two-stage sub-boiling acid purification system, including a movable trolley-type frame 1, which is divided into an upper layer and a lower layer; the lower layer has a raw acid storage bottle and a finished product collection bottle arranged side by side at the front. The purification unit is located at the rear of the frame 1 and is staggered vertically. The purification unit includes a first-stage distillation chamber 5 and a second-stage distillation chamber 6. The installation position of the first-stage distillation chamber 5 is higher than that of the second-stage distillation chamber 6. The outlet of the first-stage distillation chamber 5 is connected to the inlet of the second-stage distillation chamber 6 through a pipeline, so that the distillate flows into the second-stage distillation chamber 6 by gravity. The first weighing sensor 8 is located below the single-leg support point of the first-stage distillation chamber 5 and is used to monitor the mass change of the first-stage distillation chamber 5 in real time. The second weighing sensor 9 is located below the single-leg support point of the second-stage distillation chamber 6 and is used to monitor the mass change of the second-stage distillation chamber 6 in real time. The low-level switch for the raw acid bottle is located on the outside of the raw acid storage bottle wall; The high-level switch for the collection bottle is located on the outside of the finished product collection bottle wall; A leak sensor is installed at the lowest point of the chassis of frame 1; The circulating water machine is located on the lower layer of the frame 1. The circulating water machine is connected to the cooling interface of the first-stage distillation chamber 5 and the second-stage distillation chamber 6 through cooling water pipes to form a fully enclosed circulating cooling loop. The circulating water machine has a liquid shortage alarm signal output terminal and a high temperature alarm signal output terminal. The control unit 11, the first weighing sensor 8, the second weighing sensor 9, the low-level switch of the original acid bottle, the high-level switch of the collection bottle, the leakage sensor, and the alarm signal output terminal of the circulating water machine are all connected to the signal input terminal of the control unit 11. The control output terminal of the control unit 11 is connected to the first-stage heating device, the second-stage heating device, and the sample injection valve, respectively. Both the first-stage and second-stage heating devices are infrared radiation heating lamps, which are located below the bottom of the corresponding distillation chamber and do not contact the chamber.

[0024] The purification system also includes a pneumatically driven sample inlet system: the original acid storage bottle is equipped with a quick-change cap, which includes an inner cap and an outer cap. The inner cap is fixedly connected to the air inlet pipe and the liquid inlet pipe, and the outer cap is threaded to the bottle mouth and can rotate independently relative to the inner cap; the air inlet pipe is connected in sequence to the gas purification component, the pressure reducing valve and the sample inlet valve and then connected to an external gas source; the liquid inlet pipe is connected to the liquid inlet of the first-stage distillation chamber 5; the entire sample inlet flow path is made of only PFA material.

[0025] The high-level switch for the collection bottle consists of two redundant level sensors. The collection bottle is determined to be full when either sensor is triggered.

[0026] The purification system also includes a self-cleaning subsystem: the inlet of the cleaning pump is connected to an ultrapure water storage tank, and the outlet is connected to the top cleaning port of the first-stage distillation chamber 5 and the top cleaning port of the second-stage distillation chamber 6 via a first cleaning inlet valve and a second cleaning inlet valve, respectively; the inlet of the waste discharge pump is connected to the bottom drain port of the first-stage distillation chamber 5 and the bottom drain port of the second-stage distillation chamber 6 via a first cleaning drain valve and a second cleaning drain valve, respectively, and the outlet of the waste discharge pump is connected to a waste liquid collection tank; the first cleaning inlet valve, the second cleaning inlet valve, the first cleaning drain valve, and the second cleaning drain valve are all pneumatic diaphragm valves, and their control terminals are respectively connected to the control unit 11.

[0027] Furthermore, such as Figure 2 and Figure 5 As shown, the purification unit also includes a metal isolation chamber, and the control unit 11 is located inside the metal isolation chamber. The metal isolation chamber is physically isolated from the pipeline space of the purification unit. The cables extending from the metal isolation chamber to each actuator are all covered with PFA or PTFE sleeves to prevent metal contamination such as Fe and Cr from the source. The metal-free sample injection ensures ultra-high purity.

[0028] This invention also provides a control method for a fully automated two-stage sub-boiling acid purification system, which, based on the above-mentioned fully automated two-stage sub-boiling acid purification system, includes the following steps: S1. Liquid level monitoring steps: The first mass signal of the first distillation chamber 5 is obtained in real time by the first weighing sensor 8 located below the first distillation chamber 5, and the second mass signal of the second distillation chamber 6 is obtained in real time by the second weighing sensor 9 located below the second distillation chamber 6. The first net weight and the second net weight are obtained by subtracting their respective tare weights. S2. Safety Interlock Procedure: The alarm signals from the first weighing sensor 8, the second weighing sensor 9, the low-level switch of the original acid bottle, the high-level switch of the collection bottle, the leakage sensor, and the circulating water machine are used as safety interlock input signals and connected to the control unit 11. The control unit 11 executes the following interlock logic according to each input signal: When the first net weight is lower than the first minimum threshold, the power supply to the first-stage heating device is cut off; when the second net weight is lower than the second minimum threshold, the power supply to the second-stage heating device is cut off; when either the first or second net weight is higher than the maximum threshold, the power supply to both the first and second-stage heating devices is cut off and sample injection is stopped; when any one of the following is triggered: low level switch of the original acid bottle, high level switch of the collection bottle, leakage sensor, or alarm signal of the circulating water machine, the corresponding protection action is executed; the first minimum threshold is 15g, the second minimum threshold is 50g, and the maximum threshold is 650g.

[0029] S3. Injection control steps: When the first net weight is lower than the injection start threshold, the control unit 11 controls the injection valve to open and uses air pressure to push the raw acid from the raw acid storage bottle to the first-stage distillation chamber 5 until the first net weight reaches the injection stop threshold and the injection valve is closed. The injection start threshold is 50g and the injection stop threshold is 700g.

[0030] Furthermore, the corresponding protective actions in step S2 include: When the low level switch of the original acid bottle is triggered, the control unit 11 stops the injection and issues an alarm; When the high liquid level switch of the collection bottle is triggered, the control unit 11 cuts off the power supply to the first-stage heating device and the second-stage heating device, stops the sample injection, and issues an alarm. When the leak sensor is triggered, the control unit 11 executes an emergency stop of the system and issues an alarm; When the low liquid alarm signal or high temperature alarm signal of the circulating water machine is triggered, the control unit 11 cuts off the power supply to the first-stage heating device and the second-stage heating device and issues an alarm.

[0031] Furthermore, it also includes a self-cleaning step: in response to a one-button cleaning command, the control unit 11 controls the cleaning pump to start, and at the same time opens the first cleaning water inlet valve and the second cleaning water inlet valve to inject ultrapure water into the first-stage distillation chamber 5 and the second-stage distillation chamber 6 respectively; after the water injection is completed, the cleaning pump and the cleaning water inlet valve are turned off, the first cleaning drain valve and the second cleaning drain valve are opened, and the waste pump is started to drain the cleaning waste liquid. The control unit 11 monitors the emptying progress in real time through the first weighing sensor 8 and the second weighing sensor 9. When the first net weight and the second net weight are both lower than the emptying completion threshold and continue for a predetermined time, the emptying is determined to be completed.

[0032] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] Example 1: Overall System Structure; like Figure 1 As shown, the fully automated two-stage sub-boiling acid purification system provided by this invention includes a movable trolley-type frame 1, with casters equipped with brakes at the bottom. The frame 1 is divided into upper and lower layers: the lower layer houses the circulating water machine, and the upper layer houses the purification unit.

[0034] The purification unit is spatially divided into five independent functional areas: the system panel area, the raw material tank 1-2, the collection tank 1-3, the primary purification system, and the secondary purification system. The system panel area is located on the inner side of the front of the unit and vertically houses the cleaning pump 14, waste pump, gas purification components, injection valve, and various cleaning valves, among other fluid control components. The raw material tank 1-2 is located on the left side of the front of the unit and contains a PFA-material raw acid storage bottle. The collection tank 1-3 is located on the right side of the front of the unit and contains a PFA-material finished product collection bottle.

[0035] Example 2: Weighing-type liquid level monitoring system; like Figure 4 As shown, the first weighing sensor 8 is installed below the single-leg support point of the first-stage distillation chamber 5, and the second weighing sensor 9 is installed below the single-leg support point of the second-stage distillation chamber 6. Both weighing sensors are high-precision strain gauge sensors with an accuracy of 0.05% and a measuring range of 10 kg.

[0036] The sensor outputs a mV-level signal, which is converted into a standard signal by a transmitter and input to the control unit 11. A touchscreen 11-1 is located on the front of the control unit 11 for operator control. The control unit 11 obtains the net weight by subtracting the tare weight from the real-time mass readings of the two sensors. Since the sensor only measures the force on a single foot, approximately half of the total mass (i.e., the sensor reading when the cavity is fully loaded is approximately 375g, half of the total liquid weight of 750g), a sensor with a 10kg range is selected to achieve higher accuracy.

[0037] The control unit 11 presets the following threshold values: Level 1 Low Limit (Anti-dry burning): Turn off the first infrared heating lamp 5-2 when the net weight is <15g; Level 2 Low Limit (Anti-dry burning): Turn off the second infrared heating lamp 6-1 when the net weight is <50g; First-stage injection stop: Close the injection solenoid valve when the net weight is ≥700g; Level II upper limit (protection): When the net weight is >650g, turn off both infrared heating lamps and stop the injection; The weighing data is also used to determine the self-cleaning and emptying process: if the net weight is less than 5g and remains so for 10 seconds, the emptying process is considered complete.

[0038] Example 3: Multi-sensor safety interlock system; like Figure 1 , Figure 2 As shown, the safety interlocking system of the present invention integrates the following sensors: (1) Weighing sensor: monitors the liquid level in the primary and secondary distillation chambers to prevent dry burning and overfilling.

[0039] (2) Low level switch for raw acid bottle: Installed close to the outside of the raw acid storage bottle, it adopts non-contact level detection and triggers an alarm when there is no liquid. When the raw acid is exhausted, the control unit 11 stops the injection and alarms to prevent the heating chamber from burning dry.

[0040] (3) High level switch for collection bottle: Two redundant level sensors are installed on the outside of the finished product collection bottle. If either sensor is triggered, the collection bottle is considered full, the system automatically stops purification and alarms. The redundant design avoids the risk of acid overflow due to the failure of a single sensor.

[0041] (4) Leakage sensor: installed at the lowest point of the chassis 1, using conductive or optical leakage detection principle. Once acid leakage is detected, the control unit 11 executes system emergency stop, cutting off all heating and sample injection.

[0042] (5) Alarm signal of circulating water machine: The circulating water machine is equipped with a water tank, compressor, water pump and thermostat, and has the functions of liquid shortage detection and high temperature detection. When the circulating water machine is short of water or the water temperature exceeds the limit, the alarm signal is output to the control unit 11, and the control unit 11 cuts off the power supply to the heating device.

[0043] Control unit 11 uses "OR" logic for judgment: if any sensor triggers an alarm, the corresponding protection action will be executed. The specific interlocking logic is shown in Table 1.

[0044] Table 1

[0045] Example 4: Pneumatically driven sample introduction system; like Figure 6 As shown, the original acid storage bottle is equipped with a quick-change cap. The quick-change cap consists of an inner cap and an outer cap: the inner cap is fixedly connected to the air inlet pipe and the liquid inlet pipe; the outer cap is threaded into the bottle neck and can rotate independently relative to the inner cap. When changing bottles, only the outer cap needs to be rotated, while the inner cap and the connected tubing remain stationary, enabling quick replacement of reagent bottles.

[0046] The gas inlet pipeline is connected to an external gas source: nitrogen, air or argon provided by the user, with a pressure ≥0.7MPa. It is connected in sequence to: gas purification components: including oil and dust removal filter, deep dryer, PFA gas washing bottle → pressure reducing valve, adjusted to 0.5-0.6MPa → injection valve, using a pneumatic diaphragm valve → gas inlet port of the original acid bottle cap.

[0047] The inlet pipe is a PFA hose, which is led out from the outlet of the original acid bottle cap and connected to the first-stage inlet at the top of the first-stage distillation chamber 5.

[0048] When the injection valve is opened, clean pressurized gas enters above the liquid surface in the original acid bottle, pumping the acid to the first-stage distillation chamber 5. Throughout the injection process, the acid only comes into contact with the PFA tubing, without any metal parts.

[0049] Example 5: Two-stage sub-boiling distillation system; like Figure 3 As shown, the first-stage distillation chamber 5 is installed higher than the second-stage distillation chamber 6. The first-stage outlet of the first-stage distillation chamber is connected to the second-stage inlet 6-2 of the second-stage distillation chamber 6 via a PFA hose in a downward-sloping direction. Because the first-stage inlet is installed higher than the second-stage inlet 6-2, the distillate flows naturally into the second-stage distillation chamber 6 under gravity, without the need for any pumping device.

[0050] Both the first infrared heating lamp 5-2 and the second infrared heating lamp 6-1 are infrared radiation lamps with a power of 250W. They are directly installed below the bottom of the distillation chamber through a conical shell, without contact with the chamber. The heating lamps are controlled by solid-state relays. The infrared lamps heat at a constant power, and the evaporation rate increases with temperature. The system automatically stabilizes at the temperature point where the heat dissipation from evaporation equals the heating power, which is exactly 10-20°C below the boiling point of each acid. Different acids, such as nitric acid, hydrochloric acid, hydrofluoric acid, and water, have different boiling points and will automatically stabilize at their corresponding sub-boiling temperature, 10-20°C below their boiling point, without requiring user temperature setting.

[0051] Example 6: Self-cleaning system; like Figure 5 As shown, the self-cleaning subsystem adopts an architecture of "independent valve control and shared pump", and is fully integrated on the system panel.

[0052] The cleaning pump 14 is a pneumatic diaphragm pump. Its inlet is connected to the ultrapure water storage tank through a PFA pipe, and its outlet is divided into two paths: the first path is connected to the top cleaning port of the first-stage distillation chamber 5 through the first cleaning water inlet valve; the second path is connected to the top cleaning port 6-4 of the second-stage distillation chamber through the second cleaning water inlet valve.

[0053] The waste discharge pump is a corrosion-resistant diaphragm vacuum pump. Its inlet is connected to the first and second cleaning drain valves via a tee. The inlets of the first and second cleaning drain valves pass through the drain ports at the bottom of their respective heating lamps, and then connect to the drain ports at the bottom of the first and second stage distillation chambers 6. The waste discharge pump outlet is connected to a waste liquid collection tank.

[0054] All cleaning valves are pneumatic diaphragm valves, which are uniformly controlled by control unit 11.

[0055] The automatic cleaning process is as follows: (1) Water injection cleaning: The control unit 11 opens the first cleaning water inlet valve and the second cleaning water inlet valve, starts the cleaning pump 14, and injects ultrapure water into the two chambers for cleaning. The cleaning water volume is monitored by the corresponding weighing sensor, and stops after reaching the set value.

[0056] (2) Drainage: Control unit 11 opens the first cleaning drain valve and the second cleaning drain valve, starts the waste pump, and pumps out the waste liquid. At the same time, it monitors the corresponding weighing sensor. When the net weight is less than 5g and remains so for 10 seconds, it stops the waste discharge and closes the valve.

[0057] Example 7: Working Process; The system works as follows: (1) Power-on self-test: All sensors communicate normally and there is no alarm.

[0058] (2) Sample injection: The control unit 11 opens the injection valve, and the gas pressure forces the raw acid from the raw acid storage bottle into the first-stage distillation chamber 5 through the PFA injection pipeline. The first weighing sensor 8 stops the injection when the net weight reaches 700g.

[0059] (3) Heating and distillation: The control unit 11 turns on the first infrared heating lamp 5-2 and the second infrared heating lamp 6-1, and the acid solution automatically enters the sub-boiling state. The distillate produced in the first-stage distillation chamber 5 flows into the second-stage distillation chamber 6 by gravity through the PFA hose. After the second-stage sub-boiling distillation, the finished acid solution flows into the finished product collection bottle from the second-stage outlet 6-3.

[0060] (4) Automatic replenishment of sample: When the first net weight drops below 50g, the control unit 11 automatically re-injects the sample to 700g to achieve continuous operation.

[0061] (5) Shutdown when collection bottle is full: When either the first high level switch or the second high level switch is triggered, the system stops heating and sample injection and alarms. The user can continue to operate after replacing the collection bottle.

[0062] (6) One-click cleaning: After purification is complete, click the cleaning button and the system will automatically complete the water injection cleaning-draining process.

[0063] Example 8: Alternative Solution; The following alternatives exist for some of the technical features of this invention: Sample introduction drive method: It can be driven by a built-in micro diaphragm pump or by direct gas supply from an inert gas cylinder, both of which are variations of gas pressure driven sample introduction.

[0064] Gas purification components: can be integrated gas purification columns or two-stage purification including only filtration and drying, and the configuration can be adjusted according to the actual cleanliness of the gas source.

[0065] Two-stage distillation chamber layout: Two-stage chambers can be placed side by side, but the height difference can be adjusted by a bracket. As long as the liquid outlet of the first stage is higher than the liquid inlet of the second stage, gravity flow can be achieved.

[0066] Weighing sensor range: Different range sensors can be selected according to different cavity sizes and capacities, as long as the accuracy requirements are met.

[0067] Cooling method: It can be connected to a centralized laboratory circulating cooling water system or a semiconductor refrigeration cooling method.

[0068] Cleaning pump type: Corrosion-resistant peristaltic pump, electromagnetic diaphragm pump or injection pump can be used.

[0069] Control unit: A PLC or embedded industrial computer can be used instead of a microcontroller.

[0070] Shell material: ABS board or transparent acrylic shell can be used, and acid corrosion resistance must be ensured.

[0071] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A control method for a fully automated two-stage sub-boiling acid purification system, characterized in that, Includes the following steps: S1. Liquid level monitoring steps: The first mass signal of the first distillation chamber is obtained in real time by the first weighing sensor set below the first distillation chamber, and the second mass signal of the second distillation chamber is obtained in real time by the second weighing sensor set below the second distillation chamber. The first net weight and the second net weight are obtained by subtracting their respective tare weights. S2. Safety Interlock Steps: The alarm signals from the first weighing sensor, the second weighing sensor, the low-level switch of the original acid bottle, the high-level switch of the collection bottle, the leakage sensor, and the circulating water machine are used as safety interlock input signals and connected to the control unit. The control unit executes the following interlock logic based on each input signal: When the first net weight is lower than the first minimum threshold, the power supply to the first-stage heating device is cut off; when the second net weight is lower than the second minimum threshold, the power supply to the second-stage heating device is cut off; when the first net weight or the second net weight is higher than the maximum threshold, the power supply to both the first-stage and second-stage heating devices is cut off and the sample injection is stopped; when any one of the low liquid level switch of the original acid bottle, the high liquid level switch of the collection bottle, the leakage sensor, or the alarm signal of the circulating water machine is triggered, the corresponding protection action is executed. S3. Injection control steps: When the first net weight is lower than the injection start threshold, the control unit controls the injection valve to open and uses air pressure to push the raw acid from the raw acid storage bottle to the first stage distillation chamber until the first net weight reaches the injection stop threshold and the injection valve is closed.

2. The control method for the fully automated two-stage sub-boiling acid purification system according to claim 1, characterized in that, The corresponding protection action in step S2 includes: When the low level switch of the original acid bottle is triggered, the control unit stops the sample injection and issues an alarm; When the high liquid level switch of the collection bottle is triggered, the control unit cuts off the power supply to the first-stage heating device and the second-stage heating device, stops the sample injection, and issues an alarm. When the leakage sensor is triggered, the control unit executes an emergency system stop and issues an alarm; When the low liquid alarm signal or high temperature alarm signal of the circulating water machine is triggered, the control unit cuts off the power supply to the first-stage heating device and the second-stage heating device and issues an alarm.

3. The control method for the fully automated two-stage sub-boiling acid purification system according to claim 2, characterized in that, It also includes a self-cleaning step: in response to a one-button cleaning command, the control unit controls the cleaning pump to start, and simultaneously opens the first cleaning water inlet valve and the second cleaning water inlet valve to inject ultrapure water into the first-stage distillation chamber and the second-stage distillation chamber, respectively; after the water injection is completed, the cleaning pump and the cleaning water inlet valve are closed, the first cleaning drain valve and the second cleaning drain valve are opened, and the waste pump is started to drain the cleaning waste liquid. The control unit monitors the emptying progress in real time through the first weighing sensor and the second weighing sensor. When both the first net weight and the second net weight are lower than the emptying completion threshold and remain so for a predetermined time, the emptying is determined to be complete.

4. The control method for the fully automated two-stage sub-boiling acid purification system according to claim 3, characterized in that, The first lower threshold is 15g, the second lower threshold is 50g, the upper threshold is 650g, the injection start threshold is 50g, and the injection stop threshold is 700g.

5. A fully automated two-stage sub-boiling acid purification system, used in the control method of the fully automated two-stage sub-boiling acid purification system of claim 4, characterized in that, It includes a movable trolley-type frame, which is divided into an upper layer and a lower layer; the lower layer has a raw acid storage bottle and a finished product collection bottle arranged side by side at the front. The purification unit is located at the rear of the frame and is staggered vertically. The purification unit includes a first-stage distillation chamber and a second-stage distillation chamber. The installation position of the first-stage distillation chamber is higher than that of the second-stage distillation chamber. The outlet of the first-stage distillation chamber is connected to the inlet of the second-stage distillation chamber through a pipeline, so that the distillate flows into the second-stage distillation chamber by gravity. The first weighing sensor is located below the single-leg support point of the first-stage distillation chamber and is used to monitor the mass change of the first-stage distillation chamber in real time. The second weighing sensor is located below the single-leg support point of the second-stage distillation chamber and is used to monitor the mass change of the second-stage distillation chamber in real time. The low-level switch for the raw acid bottle is located on the outside of the raw acid storage bottle wall; The high-level switch for the collection bottle is located on the outside of the finished product collection bottle wall; A leakage sensor is installed at the lowest point of the chassis of the frame; A circulating water machine is installed on the lower layer of the frame. The circulating water machine is connected to the cooling interfaces of the first-stage distillation chamber and the second-stage distillation chamber through cooling water pipes to form a fully enclosed circulating cooling loop. The circulating water machine has a liquid shortage alarm signal output terminal and a high temperature alarm signal output terminal. The control unit is connected to the signal input terminal of the first weighing sensor, the second weighing sensor, the low liquid level switch of the original acid bottle, the high liquid level switch of the collection bottle, the leakage sensor, and the alarm signal output terminal of the circulating water machine. The control output terminal of the control unit is connected to the first stage heating device, the second stage heating device, and the injection valve. The control unit is configured to perform the control method according to any one of claims 1 to 4.

6. The fully automated two-stage sub-boiling acid purification system according to claim 5, characterized in that, It also includes a pneumatically driven sample inlet system: the original acid storage bottle is equipped with a quick-change cap, which includes an inner cap and an outer cap. The inner cap is fixedly connected to an air inlet pipe and a liquid inlet pipe, and the outer cap is threaded to the bottle mouth and can rotate independently relative to the inner cap; the air inlet pipe is connected in sequence to a gas purification component, a pressure reducing valve, and a sample inlet valve before being connected to an external gas source; the liquid inlet pipe is connected to the liquid inlet of the first-stage distillation chamber; the entire sample inlet path is made of only PFA material.

7. The fully automated two-stage sub-boiling acid purification system according to claim 6, characterized in that, The high liquid level switch for the collection bottle consists of two redundant liquid level sensors. When either sensor is triggered, the collection bottle is determined to be full.

8. The fully automated two-stage sub-boiling acid purification system according to claim 7, characterized in that, It also includes a self-cleaning subsystem: the inlet of the cleaning pump is connected to an ultrapure water storage tank, and the outlet is connected to the top cleaning port of the first-stage distillation chamber and the top cleaning port of the second-stage distillation chamber via a first cleaning inlet valve and a second cleaning inlet valve, respectively; the inlet of the waste discharge pump is connected to the bottom drain port of the first-stage distillation chamber and the bottom drain port of the second-stage distillation chamber via a first cleaning drain valve and a second cleaning drain valve, respectively, and the outlet of the waste discharge pump is connected to a waste liquid collection tank; the first cleaning inlet valve, the second cleaning inlet valve, the first cleaning drain valve, and the second cleaning drain valve are all pneumatic diaphragm valves, and their control terminals are respectively connected to the control unit.

9. The fully automated two-stage sub-boiling acid purification system according to claim 8, characterized in that, Both the first-stage heating device and the second-stage heating device are infrared radiation heating lamps, which are located below the bottom of the corresponding distillation chamber and do not contact the chamber.

10. The fully automated two-stage sub-boiling acid purification system according to claim 9, characterized in that, The purification unit also includes a metal isolation chamber, and the control unit is located inside the metal isolation chamber. The metal isolation chamber is physically isolated from the pipeline space of the purification unit. The cables extending from the metal isolation chamber to each actuator are all covered with PFA or PTFE sleeves.

Images