High-reliability graphite furnace and power supply system thereof

Abstract

The invention discloses a high-reliability graphite furnace and a power supply system thereof. The graphite furnace power supply system comprises a main control module, a power supply control module, a voltage reduction module and a detection module, the main control module is respectively connected with the power supply control module, the voltage reduction module, the detection module and the graphite furnace; the power supply control module, the voltage reduction module, the graphite furnace and the detection module are connected in sequence; the power supply control module comprises an alternating current contactor, a first current transformer and a thyristor; the voltage reduction module comprises a transformer and a temperature sensor; the detection module comprises a detection circuit and a direct current contactor. According to the high-reliability graphite furnace and the power supply system thereof, the graphite furnace can be ensured to work stably and controllably, and high reliability of a graphite furnace power supply is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of graphite furnaces and relates to a graphite furnace, in particular to a high-reliability graphite furnace and a power supply system thereof. Background Art

[0002] Atomic absorption spectrometry, also known as atomic absorption spectrophotometry, is a modern instrumental analysis method based on the determination of element content by the degree of radiation attenuation, in which the characteristic radiation of the element being measured, emitted from a light source, is absorbed by the ground state atoms of the element when passing through the atomic vapor of the element. It has the advantages of low detection limit, good selectivity, high precision, strong anti-interference ability, fast analysis speed, wide application range, and small sample amount. It is widely used in geology, metallurgy, chemical industry, petroleum, food, environment, medicine and other fields.

[0003] When using atomic absorption spectrometry to determine elements, sample atomization is a very critical step. Commonly used methods include: flame atomization, electric graphite furnace atomization, quartz tube atomization, low-temperature atomization, etc. Among them, electric graphite furnace atomization is one of the most important atomization methods. Compared with flame atomization, graphite furnace atomization eliminates the interference of flame, and the detection limit can be as low as 10^-14g. It is safer than the flame method and can be used for the analysis of radioactive and toxic substances.

[0004] The electric heating graphite furnace atomization method actually applies a current of up to several hundred amperes to a graphite tube with an internal resistance of only tens of milliohms. The temperature of the graphite tube can instantly reach several thousand degrees to atomize the sample. The power supply power of this process may reach 5000W, and the highest point temperature exceeds 3000℃, which is prone to danger and even fire.

[0005] In view of this, there is an urgent need to design a new graphite furnace power supply system so as to overcome at least part of the above-mentioned defects of the existing graphite furnace power supply system. Summary of the invention

[0006] The invention provides a high-reliability graphite furnace and a power supply system thereof, which can ensure the stability and controllability of the graphite furnace during operation and realize the high reliability of the graphite furnace power supply.

[0007] To solve the above technical problem, according to one aspect of the present invention, the following technical solution is adopted:

[0008] A high-reliability graphite furnace power supply system, the graphite furnace power supply system comprising: a main control module, a power control module, a voltage reduction module and a detection module;

[0009] The main control module is connected to the power control module, the voltage reduction module, the detection module and the graphite furnace respectively; the power control module, the voltage reduction module, the graphite furnace and the detection module are connected in sequence;

[0010] The power supply control module includes an AC contactor, a first current transformer, and a thyristor; the AC contactor is closed by default, and is disconnected when the main control module detects that the back-end circuit has overtemperature, overcurrent, or abnormality in the graphite furnace, and also serves as a circuit breaker protection after the thyristor fails;

[0011] The first current transformer is used to monitor the current on the high-voltage side of the graphite furnace when it is working, and provide it to the main control module to determine whether it is an abnormal situation; when the main control module receives a current exceeding the preset range, it directly controls the thyristor and the AC contactor to disconnect;

[0012] The thyristor is one of the core components for controlling the heating of the graphite furnace. The main control circuit output controls the opening duty cycle, thereby controlling the power output to the subsequent stage, and the heating rate of the graphite furnace is determined by this;

[0013] The step-down module includes a transformer and a temperature sensor; the temperature sensor is embedded in the coil of the transformer to monitor the temperature rise ΔT (=working temperature-standby temperature) of the transformer in real time. If the temperature rise ΔT is too large or too small, the current size of the graphite furnace when working will exceed the preset range, and the main control module will disconnect the thyristor and AC contactor and issue an alarm;

[0014] The detection module includes a detection circuit and a DC contactor; the DC contactor is used to disconnect the low-voltage side circuit of the transformer when idle, so as to prevent the detection circuit from being affected by the transformer winding when measuring the internal resistance of the graphite furnace.

[0015] As an implementation mode of the present invention, the detection circuit includes a third operational amplifier U3, a fourth operational amplifier U4, a fifth operational amplifier U5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9;

[0016] The non-inverting input terminal of the third operational amplifier U3 is respectively connected to the second end of the first resistor R1 and the second end of the second resistor R2; the inverting input terminal of the third operational amplifier U3 is respectively connected to the output terminal of the third operational amplifier U3 and the first end of the third resistor R3; the second end of the third resistor R3 is respectively connected to the first end of the first capacitor C1, the non-inverting input terminal of the fourth operational amplifier U4, the second end of the third capacitor C3, and the first end of the seventh resistor R7; the first end of the first resistor R1 is connected to the first power supply voltage, and the first end of the second resistor R2 is grounded;

[0017] The inverting terminal of the fourth operational amplifier U4 is respectively connected to the second end of the fourth resistor R4, the first end of the second capacitor C2, and the first electrode block of the graphite furnace; the first end of the fourth resistor R4 is grounded; the output end of the fourth operational amplifier U4 is respectively connected to the second electrode block of the graphite furnace and the first end of the fifth resistor R5;

[0018] The second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the first end of the third capacitor C3; the second end of the sixth resistor R6 is connected to the non-inverting input end of the fifth operational amplifier U5, and the inverting input end of the fifth operational amplifier U5 is respectively connected to the second end of the seventh resistor and the first end of the eighth resistor R8; the output end of the fifth operational amplifier U5 is respectively connected to the second end of the eighth resistor R8 and the first end of the ninth resistor R9; the second end of the ninth resistor R9 is connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

[0019] As an implementation mode of the present invention, the third operational amplifier U3 sets a reference voltage Vref, and the two electrode blocks of the graphite furnace are connected to the constant current source circuit formed by the fourth operational amplifier U4. According to the virtual short and virtual open of the operational amplifier, the current flowing through the first resistor R1 is Vref / R1, which is the current flowing through the graphite furnace; the voltage output by the fourth operational amplifier U4 = Vref + Vgraphite furnace, and Vref is deducted by the differential fifth operational amplifier U5, so that the internal resistance of the graphite furnace R = graphite furnace voltage * R1 / Vref can be calculated; the fifth operational amplifier U5 is a differential operational amplifier;

[0020] The calculated internal resistance of the graphite furnace can be used to determine the service life of the graphite furnace, thereby warning of early replacement; after replacing the graphite furnace, it can be used to determine whether it is installed in place; through the combined processing of the internal resistance of the graphite furnace with the previously measured current and graphite furnace temperature data, it can be used to determine whether the entire system is working normally and make appropriate adjustments.

[0021] As an embodiment of the present invention, the graphite furnace includes a first electrode block, a second electrode block, a graphite cone, a graphite tube, an external cooling circulating water, an electrode block temperature measurement module, and an infrared sensor;

[0022] The graphite tube is the furnace body for atomizing the sample to be tested. The low-voltage high current output by the transformer flows through the graphite tube to generate a large amount of heat, atomizing the sample to be tested, and the graphite tube itself will form losses; the graphite cone is mainly used to connect the graphite tube and the electrode block; the electrode block is made of a hollow copper block, which serves as a wire connecting the graphite furnace and the transformer output, and at the same time isolates the high temperature of the graphite furnace when it is working;

[0023] The high temperature generated when the graphite furnace is working will be transferred to the electrode block, and cooling circulating water is required to dissipate the heat for it continuously. By setting a flow sensor to monitor the cooling water flow, the state of liquid shortage and pipeline blockage can be sensed. The electrode block temperature measurement module embedded in the electrode block is used to detect the temperature of the electrode block in real time, sense the actual heat dissipation of the electrode block, and avoid thermal runaway. The temperature of the graphite furnace is detected by the infrared sensor measuring the intensity of infrared rays emitted under high temperature state when the graphite furnace is working to measure the actual temperature. After obtaining the temperature data, the main control module adjusts the duty cycle of the thyristor to realize closed-loop control, so that the temperature of the graphite furnace is stabilized within the set range.

[0024] As an embodiment of the present invention, the graphite furnace power supply system further includes a power input protection module, and the power input protection module includes a circuit breaker protection module and a lightning protection module;

[0025] The circuit breaker protection module is used to ensure that the power supply is disconnected in the extreme case of internal power short circuit and protection circuit failure, thereby effectively preventing the internal circuit from burning out and catching fire; the lightning protection module is used to prevent the external mains power from being damaged by lightning surges and internal circuits.

[0026] According to another aspect of the present invention, the following technical solution is adopted: a high-reliability graphite furnace, the high-reliability graphite furnace comprises a graphite furnace and a graphite furnace power supply system; the graphite furnace power supply system comprises: a main control module, a power supply control module, a voltage reduction module and a detection module;

[0027] The main control module is connected to the power control module, the voltage reduction module, the detection module and the graphite furnace respectively; the power control module, the voltage reduction module, the graphite furnace and the detection module are connected in sequence;

[0028] The power supply control module includes an AC contactor, a first current transformer, and a thyristor; the AC contactor is closed by default, and is disconnected when the main control module detects that the back-end circuit has overtemperature, overcurrent, or abnormality in the graphite furnace, and also serves as a circuit breaker protection after the thyristor fails;

[0029] The first current transformer is used to monitor the current on the high-voltage side of the graphite furnace when it is working, and provide it to the main control module to determine whether it is an abnormal situation; when the main control module receives a current exceeding the preset range, it directly controls the thyristor and the AC contactor to disconnect;

[0030] The thyristor is one of the core components for controlling the heating of the graphite furnace. The main control circuit output controls the opening duty cycle, thereby controlling the power output to the subsequent stage, and the heating rate of the graphite furnace is determined by this;

[0031] The step-down module includes a transformer and a temperature sensor; the temperature sensor is embedded in the coil of the transformer to monitor the temperature rise ΔT (=Tworking-Tstandby) of the transformer in real time. If the temperature rise ΔT is too large or too small, the current size of the graphite furnace when working will exceed the preset range, and the main control module will disconnect the thyristor and AC contactor and issue an alarm;

[0032] The detection module includes a detection circuit and a DC contactor; the DC contactor is used to disconnect the low-voltage side circuit of the transformer when idle, so as to prevent the detection circuit from being affected by the transformer winding when measuring the internal resistance of the graphite furnace.

[0033] As an implementation mode of the present invention, the detection circuit includes a third operational amplifier U3, a fourth operational amplifier U4, a fifth operational amplifier U5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9;

[0034] The non-inverting input terminal of the third operational amplifier U3 is respectively connected to the second end of the first resistor R1 and the second end of the second resistor R2; the inverting input terminal of the third operational amplifier U3 is respectively connected to the output terminal of the third operational amplifier U3 and the first end of the third resistor R3; the second end of the third resistor R3 is respectively connected to the first end of the first capacitor C1, the non-inverting input terminal of the fourth operational amplifier U4, the second end of the third capacitor C3, and the first end of the seventh resistor R7; the first end of the first resistor R1 is connected to the first power supply voltage, and the first end of the second resistor R2 is grounded;

[0035] The inverting terminal of the fourth operational amplifier U4 is respectively connected to the second end of the fourth resistor R4, the first end of the second capacitor C2, and the first electrode block of the graphite furnace; the first end of the fourth resistor R4 is grounded; the output end of the fourth operational amplifier U4 is respectively connected to the second electrode block of the graphite furnace and the first end of the fifth resistor R5;

[0036] The second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the first end of the third capacitor C3; the second end of the sixth resistor R6 is connected to the non-inverting input end of the fifth operational amplifier U5, and the inverting input end of the fifth operational amplifier U5 is respectively connected to the second end of the seventh resistor and the first end of the eighth resistor R8; the output end of the fifth operational amplifier U5 is respectively connected to the second end of the eighth resistor R8 and the first end of the ninth resistor R9; the second end of the ninth resistor R9 is connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

[0037] As an implementation mode of the present invention, the third operational amplifier U3 sets a reference voltage Vref, and the two electrode blocks of the graphite furnace are connected to the constant current source circuit formed by the fourth operational amplifier U4. According to the virtual short and virtual open of the operational amplifier, the current flowing through the first resistor R1 is Vref / R1, which is the current flowing through the graphite furnace; the voltage output by the fourth operational amplifier U4 = Vref + Vgraphite furnace, and Vref is deducted by the differential fifth operational amplifier U5, so that the internal resistance of the graphite furnace R = graphite furnace voltage * R1 / Vref can be calculated; the fifth operational amplifier U5 is a differential operational amplifier;

[0038] The calculated internal resistance of the graphite furnace can be used to determine the service life of the graphite furnace, thereby warning of early replacement; after replacing the graphite furnace, it can be used to determine whether it is installed in place; through the combined processing of the internal resistance of the graphite furnace with the previously measured current and graphite furnace temperature data, it can be used to determine whether the entire system is working normally and make appropriate adjustments.

[0039] As an embodiment of the present invention, the graphite furnace includes a first electrode block, a second electrode block, a graphite cone, a graphite tube, an external cooling circulating water, an electrode block temperature measurement module, and an infrared sensor;

[0040] The graphite tube is the furnace body for atomizing the sample to be tested. The low-voltage high current output by the transformer flows through the graphite tube to generate a large amount of heat, atomizing the sample to be tested, and the graphite tube itself will form losses; the graphite cone is mainly used to connect the graphite tube and the electrode block; the electrode block is made of a hollow copper block, which serves as a wire connecting the graphite furnace and the transformer output, and at the same time isolates the high temperature of the graphite furnace when it is working;

[0041] The high temperature generated when the graphite furnace is working will be transferred to the electrode block, and cooling circulating water is required to dissipate the heat for it continuously. By setting a flow sensor to monitor the cooling water flow, the state of liquid shortage and pipeline blockage can be sensed. The electrode block temperature measurement module embedded in the electrode block is used to detect the temperature of the electrode block in real time, sense the actual heat dissipation of the electrode block, and avoid thermal runaway. The temperature of the graphite furnace is detected by the infrared sensor measuring the intensity of infrared rays emitted under high temperature state when the graphite furnace is working to measure the actual temperature. After obtaining the temperature data, the main control module adjusts the duty cycle of the thyristor to realize closed-loop control, so that the temperature of the graphite furnace is stabilized within the set range.

[0042] As an embodiment of the present invention, the graphite furnace power supply system further includes a power input protection module, and the power input protection module includes a circuit breaker protection module and a lightning protection module;

[0043] The circuit breaker protection module is used to ensure that the power supply is disconnected in the extreme case of internal power short circuit and protection circuit failure, thereby effectively preventing the internal circuit from burning out and catching fire; the lightning protection module is used to prevent the external mains power from being damaged by lightning surges and internal circuits.

[0044] The beneficial effect of the present invention is that the high-reliability graphite furnace and its power supply system proposed by the present invention can ensure the stability and controllability of the graphite furnace during operation, and achieve high reliability of the graphite furnace power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The figure is a schematic diagram of the composition of a high-reliability graphite furnace power supply system in one embodiment of the present invention.

[0046] Figure 2 FIG. 4 is a circuit diagram of a detection circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0048] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0049] The description in this section is only for several typical embodiments, and the present invention is not limited to the scope of the embodiments. The same or similar prior art means and some technical features in the embodiments are mutually replaced within the scope of the present invention.

[0050] The description of the steps in each embodiment in the specification is only for the convenience of explanation, and the implementation method of the present application is not limited by the order of implementation of the steps.

[0051] The term "connection" as used in the specification includes both direct connection and indirect connection, such as connection through some active devices, passive devices or electrically conductive media; it may also include connection through other active devices or passive devices known to those skilled in the art on the basis of achieving the same or similar functional purposes, such as connection through circuits or components such as switches and follower circuits.

[0052] The present invention discloses a high-reliability graphite furnace power supply system. Figure 1 This is a schematic diagram of the composition of a high-reliability graphite furnace power supply system in one embodiment of the present invention; please refer to Figure 1 The graphite furnace power supply system includes: a main control module 1, a power control module 2, a voltage reduction module 3 and a detection module 4. The main control module 1 is connected to the power control module 2, the voltage reduction module 3, the detection module 4 and the graphite furnace 5 respectively; the power control module 2, the voltage reduction module 3, the graphite furnace 5 and the detection module 5 are connected in sequence.

[0053] The power control module 2 includes an AC contactor 21, a first current transformer 22, and a thyristor 23; the AC contactor 21 is energized by default, and is disconnected when the main control module 1 detects that the back-end circuit has overtemperature, overcurrent, or graphite furnace abnormality, and also serves as a circuit breaker protection after the thyristor 23 fails; at the same time, it can serve as the main switch of the following power input protection circuit.

[0054] The first current transformer 22 is used to monitor the current on the high-voltage side of the graphite furnace when it is working. The maximum current during normal operation can be about 20A, which is provided to the main control module to determine whether there is an abnormal situation. If the current is too large, it may be a fault such as device damage or short circuit. If the current is too small, it may be an open circuit or the graphite furnace is disconnected. When the main control module receives a current that exceeds the preset range, it directly controls the thyristor and the AC contactor to disconnect.

[0055] The thyristor 23 is one of the core components for controlling the heating of the graphite furnace. The main control circuit output controls the opening duty cycle, thereby controlling the power output to the subsequent stage, and the heating rate of the graphite furnace is determined by this;

[0056] The step-down module 3 includes a transformer 31 and a temperature sensor 32; the temperature sensor 32 is embedded in the coil of the transformer 31, and monitors the temperature rise ΔT (which can be the working temperature-T standby temperature) of the transformer 31 in real time. If the temperature rise ΔT is too large or too small, the current size of the graphite furnace when working will exceed the preset range, and the main control module 1 will disconnect the thyristor and the AC contactor 21 and issue an alarm;

[0057] The detection module 4 includes a detection circuit and a DC contactor; the DC contactor is used to disconnect the low-voltage side circuit of the transformer when idle, so as to prevent the detection circuit from being affected by the transformer winding when measuring the internal resistance of the graphite furnace.

[0058] In one embodiment of the present invention, the graphite furnace 5 includes a first electrode block 51 , a second electrode block 52 , a graphite cone 53 , a graphite tube 54 , an external cooling circulating water 55 , an electrode block temperature measuring module 56 , and an infrared sensor 57 .

[0059] The graphite tube 54 is the furnace body for atomizing the sample to be tested, and has an internal resistance of about tens of milliohms. The low-voltage high current output by the transformer 31 flows through the graphite tube 54 to generate a large amount of heat, atomizing the sample to be tested, and at the same time, the graphite tube 54 itself will cause losses; the graphite cone 53 is mainly used to connect the graphite tube 54 and the electrode block (including the first electrode block 51 and the second electrode block 52); the electrode block is made of a hollow copper block, which serves as a wire connecting the graphite furnace 5 and the output of the transformer 31, and at the same time isolates the high temperature when the graphite furnace is working. When the graphite furnace is working, the high temperature of 2000 to 3000 degrees will be transferred to the electrode block, and cooling circulating water is required to dissipate the heat continuously. By setting a flow sensor 58 to monitor the cooling water flow, the state of lack of liquid, pipeline blockage, etc. is sensed. The electrode block temperature measurement module 56 embedded in the electrode block is used to detect the temperature of the electrode block in real time, sense the actual heat dissipation of the electrode block, and avoid thermal runaway; the graphite furnace temperature detection is measured by the infrared sensor 57 to measure the actual temperature by measuring the intensity of infrared rays emitted under the high temperature state when the graphite furnace is working. After obtaining the temperature data, the main control module adjusts the duty cycle of the thyristor to realize closed-loop control, so that the temperature of the graphite furnace is stabilized within the set range.

[0060] In one embodiment of the present invention, the graphite furnace power supply system further includes a power input protection module, which includes a circuit breaker protection module and a lightning protection module. The circuit breaker protection module is used to ensure that the power supply is disconnected in the extreme case of internal power short circuit and protection circuit failure, thereby effectively preventing the internal circuit from burning out and catching fire; the lightning protection module is used to prevent the external mains from being damaged by lightning surge and damaging the internal circuit.

[0061] Figure 2 is a circuit diagram of a detection circuit in an embodiment of the present invention; please refer to Figure 2 In one embodiment of the present invention, the detection circuit includes a third operational amplifier U3, a fourth operational amplifier U4, a fifth operational amplifier U5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9.

[0062] The positive phase input terminal of the third operational amplifier U3 is respectively connected to the second end of the first resistor R1 and the second end of the second resistor R2; the negative phase input terminal of the third operational amplifier U3 is respectively connected to the output terminal of the third operational amplifier U3 and the first end of the third resistor R3; the second end of the third resistor R3 is respectively connected to the first end of the first capacitor C1, the positive phase input terminal of the fourth operational amplifier U4, the second end of the third capacitor C3, and the first end of the seventh resistor R7; the first end of the first resistor R1 is connected to the first power supply voltage, and the first end of the second resistor R2 is grounded. The negative phase input terminal of the fourth operational amplifier U4 is respectively connected to the second end of the fourth resistor R4, the first end of the second capacitor C2, and the first electrode block of the graphite furnace; the first end of the fourth resistor R4 is grounded; the output terminal of the fourth operational amplifier U4 is respectively connected to the second electrode block of the graphite furnace and the first end of the fifth resistor R5. The second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the first end of the third capacitor C3; the second end of the sixth resistor R6 is connected to the non-inverting input end of the fifth operational amplifier U5, and the inverting input end of the fifth operational amplifier U5 is respectively connected to the second end of the seventh resistor and the first end of the eighth resistor R8; the output end of the fifth operational amplifier U5 is respectively connected to the second end of the eighth resistor R8 and the first end of the ninth resistor R9; the second end of the ninth resistor R9 is connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

[0063] In one embodiment of the present invention, the third operational amplifier U3 sets a reference voltage Vref, and the two electrode blocks of the graphite furnace are connected to the constant current source circuit formed by the fourth operational amplifier U4. According to the virtual short and virtual open of the operational amplifier, the current flowing through the first resistor R1 is Vref / R1, which is the current flowing through the graphite furnace; the voltage output by the fourth operational amplifier U4 = Vref + Vgraphite furnace, and Vref is deducted by the differential fifth operational amplifier U5, so that the internal resistance of the graphite furnace R = graphite furnace voltage * R1 / Vref can be calculated; the fifth operational amplifier U5 is a differential operational amplifier. The calculated internal resistance of the graphite furnace can be used to determine the service life of the graphite furnace, thereby warning of early replacement; after replacing the graphite furnace, it can be used to determine whether it is installed in place; through the joint processing of the internal resistance of the graphite furnace with the previously measured current and graphite furnace temperature data, it can be used to determine whether the entire system is working normally and make appropriate adjustments. For example: the internal resistance of the graphite furnace increases due to the increase in the number of uses. At this time, the measured current should decrease accordingly, and the heating temperature will also decrease. At this time, the conduction duty cycle of the thyristor can be appropriately increased, and the power supply power can be increased so that the heating temperature can achieve the expected effect.

[0064] The present invention further discloses a high reliability graphite furnace, such as Figure 1As shown, the high-reliability graphite furnace includes a graphite furnace 5 and a graphite furnace power system; the graphite furnace power system includes: a main control module 1, a power control module 2, a voltage reduction module 3 and a detection module 4. The main control module 1 is respectively connected to the power control module 2, the voltage reduction module 3, the detection module 4 and the graphite furnace 5; the power control module 2, the voltage reduction module 3, the graphite furnace 5 and the detection module 4 are connected in sequence. The specific composition of the high-reliability graphite furnace of the present invention can refer to the above description of the graphite furnace power system.

[0065] In summary, the high-reliability graphite furnace and its power supply system proposed in the present invention can ensure the stability and controllability of the graphite furnace during operation, and achieve high reliability of the graphite furnace power supply.

[0066] It should be noted that the present application can be implemented in software and / or a combination of software and hardware; for example, it can be implemented using an application-specific integrated circuit (ASIC), a general-purpose computer, or any other similar hardware device. In some embodiments, the software program of the present application can be executed by a processor to implement the above steps or functions. Similarly, the software program of the present application (including related data structures) can be stored in a computer-readable recording medium; for example, a RAM memory, a magnetic or optical drive or a floppy disk and the like. In addition, some steps or functions of the present application can be implemented in hardware; for example, as a circuit that cooperates with a processor to perform various steps or functions.

[0067] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The description and application of the present invention here are illustrative, and it is not intended to limit the scope of the present invention to the above-mentioned embodiments. The effects or advantages involved in the embodiments may not be embodied in the embodiments due to interference from various factors, and the description of the effects or advantages is not used to limit the embodiments. The deformation and change of the embodiments disclosed here are possible, and the replacement of the embodiments and the various equivalent parts are well known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential features of the present invention. Other deformations and changes can be made to the embodiments disclosed here without departing from the scope and spirit of the present invention.

Claims

1. A high reliability graphite furnace power supply system, characterized in that: The graphite furnace power supply system includes: a main control module, a power control module, a voltage reduction module and a detection module; The main control module is connected to the power control module, the voltage reduction module, the detection module and the graphite furnace respectively; the power control module, the voltage reduction module, the graphite furnace and the detection module are connected in sequence; The power supply control module includes an AC contactor, a first current transformer, and a thyristor; the AC contactor is closed by default, and is disconnected when the main control module detects that the back-end circuit has overtemperature, overcurrent, or abnormality in the graphite furnace, and also serves as a circuit breaker protection after the thyristor fails; The first current transformer is used to monitor the current on the high-voltage side of the graphite furnace when it is working, and provide it to the main control module to determine whether it is an abnormal situation; when the main control module receives a current exceeding the preset range, it directly controls the thyristor and the AC contactor to disconnect; The thyristor is one of the core components for controlling the heating of the graphite furnace. The main control circuit output controls the opening duty cycle, thereby controlling the power output to the subsequent stage, and the heating rate of the graphite furnace is determined by this; The step-down module includes a transformer and a temperature sensor; the temperature sensor is embedded in the coil of the transformer to monitor the rising temperature of the transformer in real time. If the rising temperature is too large or too small, the current size of the graphite furnace when working will exceed the preset range, and the main control module will disconnect the thyristor and AC contactor and issue an alarm; The detection module includes a detection circuit and a DC contactor; the DC contactor is used to disconnect the low-voltage side circuit of the transformer when idle, so as to prevent the detection circuit from being affected by the transformer winding when measuring the internal resistance of the graphite furnace.

2. The high reliability graphite furnace power supply system according to claim 1, characterized in that: The detection circuit includes a third operational amplifier U3, a fourth operational amplifier U4, a fifth operational amplifier U5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9; The non-inverting input terminal of the third operational amplifier U3 is respectively connected to the second end of the first resistor R1 and the second end of the second resistor R2; the inverting input terminal of the third operational amplifier U3 is respectively connected to the output terminal of the third operational amplifier U3 and the first end of the third resistor R3; the second end of the third resistor R3 is respectively connected to the first end of the first capacitor C1, the non-inverting input terminal of the fourth operational amplifier U4, the second end of the third capacitor C3, and the first end of the seventh resistor R7; the first end of the first resistor R1 is connected to the first power supply voltage, and the first end of the second resistor R2 is grounded; The inverting terminal of the fourth operational amplifier U4 is respectively connected to the second end of the fourth resistor R4, the first end of the second capacitor C2, and the first electrode block of the graphite furnace; the first end of the fourth resistor R4 is grounded; the output end of the fourth operational amplifier U4 is respectively connected to the second electrode block of the graphite furnace and the first end of the fifth resistor R5; The second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the first end of the third capacitor C3; the second end of the sixth resistor R6 is connected to the non-inverting input end of the fifth operational amplifier U5, and the inverting input end of the fifth operational amplifier U5 is respectively connected to the second end of the seventh resistor and the first end of the eighth resistor R8; the output end of the fifth operational amplifier U5 is respectively connected to the second end of the eighth resistor R8 and the first end of the ninth resistor R9; the second end of the ninth resistor R9 is connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

3. The high reliability graphite furnace power supply system according to claim 2, characterized in that: The third operational amplifier U3 sets a reference voltage Vref, and the two electrode blocks of the graphite furnace are connected to the constant current source circuit formed by the fourth operational amplifier U4. According to the virtual short and virtual open of the operational amplifier, the current flowing through the first resistor R1 is Vref / R1, which is the current flowing through the graphite furnace; the voltage output by the fourth operational amplifier U4 = Vref + Vgraphite furnace, and Vref is deducted by the differential fifth operational amplifier U5, so that the internal resistance of the graphite furnace R = graphite furnace voltage * R1 / Vref can be calculated; the fifth operational amplifier U5 is a differential operational amplifier; The calculated internal resistance of the graphite furnace can be used to determine the service life of the graphite furnace, thereby warning of early replacement; after replacing the graphite furnace, it can be used to determine whether it is installed in place; through the combined processing of the internal resistance of the graphite furnace with the previously measured current and graphite furnace temperature data, it can be used to determine whether the entire system is working normally and make appropriate adjustments.

4. The high reliability graphite furnace power supply system according to claim 1, characterized in that: The graphite furnace comprises a first electrode block, a second electrode block, a graphite cone, a graphite tube, an external cooling circulating water, an electrode block temperature measuring module, and an infrared sensor; The graphite tube is the furnace body for atomizing the sample to be tested. The low-voltage high current output by the transformer flows through the graphite tube to generate a large amount of heat, atomizing the sample to be tested, and the graphite tube itself will form losses; the graphite cone is mainly used to connect the graphite tube and the electrode block; the electrode block is made of a hollow copper block, which serves as a wire connecting the graphite furnace and the transformer output, and at the same time isolates the high temperature of the graphite furnace when it is working; The high temperature generated when the graphite furnace is working will be transferred to the electrode block, and cooling circulating water is required to dissipate the heat for it continuously. By setting a flow sensor to monitor the cooling water flow, the state of liquid shortage and pipeline blockage can be sensed. The electrode block temperature measurement module embedded in the electrode block is used to detect the temperature of the electrode block in real time, sense the actual heat dissipation of the electrode block, and avoid thermal runaway. The temperature of the graphite furnace is detected by the infrared sensor measuring the intensity of infrared rays emitted under high temperature state when the graphite furnace is working to measure the actual temperature. After obtaining the temperature data, the main control module adjusts the duty cycle of the thyristor to realize closed-loop control, so that the temperature of the graphite furnace is stabilized within the set range.

5. The high reliability graphite furnace power supply system according to claim 1, characterized in that: The graphite furnace power supply system further includes a power input protection module, and the power input protection module includes a circuit breaker protection module and a lightning protection module; The circuit breaker protection module is used to ensure that the power supply is disconnected in the extreme case of internal power short circuit and protection circuit failure, thereby effectively preventing the internal circuit from burning out and catching fire; the lightning protection module is used to prevent the external mains power from being damaged by lightning surges and internal circuits.

6. A high reliability graphite furnace, characterized in that: The high-reliability graphite furnace includes a graphite furnace and a graphite furnace power system; the graphite furnace power system includes: a main control module, a power control module, a voltage reduction module and a detection module; The main control module is connected to the power control module, the voltage reduction module, the detection module and the graphite furnace respectively; the power control module, the voltage reduction module, the graphite furnace and the detection module are connected in sequence; The power supply control module includes an AC contactor, a first current transformer, and a thyristor; the AC contactor is closed by default, and is disconnected when the main control module detects that the back-end circuit has overtemperature, overcurrent, or abnormality in the graphite furnace, and also serves as a circuit breaker protection after the thyristor fails; The first current transformer is used to monitor the current on the high-voltage side of the graphite furnace when it is working, and provide it to the main control module to determine whether it is an abnormal situation; when the main control module receives a current exceeding the preset range, it directly controls the thyristor and the AC contactor to disconnect; The thyristor is one of the core components for controlling the heating of the graphite furnace. The main control circuit output controls the opening duty cycle, thereby controlling the power output to the subsequent stage, and the heating rate of the graphite furnace is determined by this; The step-down module includes a transformer and a temperature sensor; the temperature sensor is embedded in the coil of the transformer to monitor the rising temperature of the transformer in real time. If the rising temperature is too large or too small, the current size of the graphite furnace when working will exceed the preset range, and the main control module will disconnect the thyristor and AC contactor and issue an alarm; The detection module includes a detection circuit and a DC contactor; the DC contactor is used to disconnect the low-voltage side circuit of the transformer when idle, so as to prevent the detection circuit from being affected by the transformer winding when measuring the internal resistance of the graphite furnace.

7. The high reliability graphite furnace according to claim 6, characterized in that: The detection circuit includes a third operational amplifier U3, a fourth operational amplifier U4, a fifth operational amplifier U5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9; The non-inverting input terminal of the third operational amplifier U3 is respectively connected to the second end of the first resistor R1 and the second end of the second resistor R2; the inverting input terminal of the third operational amplifier U3 is respectively connected to the output terminal of the third operational amplifier U3 and the first end of the third resistor R3; the second end of the third resistor R3 is respectively connected to the first end of the first capacitor C1, the non-inverting input terminal of the fourth operational amplifier U4, the second end of the third capacitor C3, and the first end of the seventh resistor R7; the first end of the first resistor R1 is connected to the first power supply voltage, and the first end of the second resistor R2 is grounded; The inverting terminal of the fourth operational amplifier U4 is respectively connected to the second end of the fourth resistor R4, the first end of the second capacitor C2, and the first electrode block of the graphite furnace; the first end of the fourth resistor R4 is grounded; the output end of the fourth operational amplifier U4 is respectively connected to the second electrode block of the graphite furnace and the first end of the fifth resistor R5; The second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the first end of the third capacitor C3; the second end of the sixth resistor R6 is connected to the non-inverting input end of the fifth operational amplifier U5, and the inverting input end of the fifth operational amplifier U5 is respectively connected to the second end of the seventh resistor and the first end of the eighth resistor R8; the output end of the fifth operational amplifier U5 is respectively connected to the second end of the eighth resistor R8 and the first end of the ninth resistor R9; the second end of the ninth resistor R9 is connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

8. The high reliability graphite furnace according to claim 7, characterized in that: The third operational amplifier U3 sets a reference voltage Vref, and the two electrode blocks of the graphite furnace are connected to the constant current source circuit formed by the fourth operational amplifier U4. According to the virtual short and virtual open of the operational amplifier, the current flowing through the first resistor R1 is Vref / R1, which is the current flowing through the graphite furnace; the voltage output by the fourth operational amplifier U4 = Vref + Vgraphite furnace, and Vref is deducted by the differential fifth operational amplifier U5, so that the internal resistance of the graphite furnace R = graphite furnace voltage * R1 / Vref can be calculated; the fifth operational amplifier U5 is a differential operational amplifier; The calculated internal resistance of the graphite furnace can be used to determine the service life of the graphite furnace, thereby warning of early replacement; after replacing the graphite furnace, it can be used to determine whether it is installed in place; through the combined processing of the internal resistance of the graphite furnace with the previously measured current and graphite furnace temperature data, it can be used to determine whether the entire system is working normally and make appropriate adjustments.

9. The high reliability graphite furnace according to claim 6, characterized in that: The graphite furnace comprises a first electrode block, a second electrode block, a graphite cone, a graphite tube, an external cooling circulating water, an electrode block temperature measuring module, and an infrared sensor; The graphite tube is the furnace body for atomizing the sample to be tested. The low-voltage high current output by the transformer flows through the graphite tube to generate a large amount of heat, atomizing the sample to be tested, and the graphite tube itself will form losses; the graphite cone is mainly used to connect the graphite tube and the electrode block; the electrode block is made of a hollow copper block, which serves as a wire connecting the graphite furnace and the transformer output, and at the same time isolates the high temperature of the graphite furnace when it is working; The high temperature generated when the graphite furnace is working will be transferred to the electrode block, and cooling circulating water is required to dissipate the heat for it continuously. By setting a flow sensor to monitor the cooling water flow, the state of liquid shortage and pipeline blockage can be sensed. The electrode block temperature measurement module embedded in the electrode block is used to detect the temperature of the electrode block in real time, sense the actual heat dissipation of the electrode block, and avoid thermal runaway. The temperature of the graphite furnace is detected by the infrared sensor measuring the intensity of infrared rays emitted under high temperature state when the graphite furnace is working to measure the actual temperature. After obtaining the temperature data, the main control module adjusts the duty cycle of the thyristor to realize closed-loop control, so that the temperature of the graphite furnace is stabilized within the set range.

10. The high reliability graphite furnace according to claim 6, characterized in that: The graphite furnace power supply system further includes a power input protection module, and the power input protection module includes a circuit breaker protection module and a lightning protection module; The circuit breaker protection module is used to ensure that the power supply is disconnected in the extreme case of internal power short circuit and protection circuit failure, thereby effectively preventing the internal circuit from burning out and catching fire; the lightning protection module is used to prevent the external mains power from being damaged by lightning surges and internal circuits.

Images