A method and system for thermostatic control of a chromatograph heating jacket

Abstract

This invention belongs to the field of oil exploration logging equipment control technology, and discloses a method and system for isothermal control of a chromatograph heating kit. The method includes: acquiring the initial ambient temperature and the initial sample gas temperature; determining the operating condition type based on the initial ambient temperature and the initial sample gas temperature; matching corresponding initial control parameters according to the operating condition type during the heating and isothermal phases; and controlling the heating power of the heater based on a PID control algorithm, using the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters. During the heating phase, the heater temperature is raised to the target temperature within a set time; during the isothermal phase, the heater temperature is maintained at the target temperature, achieving adaptive isothermal adjustment. This invention solves the problems of slow heating, large isothermal fluctuations, and poor analytical stability under extreme operating conditions such as low temperatures in winter and high temperatures in summer, meeting the high-precision requirements of FID (Focused Identification and Diagnostics).

Description

Technical Field

[0001] This invention belongs to the field of oil exploration logging equipment control technology, and specifically relates to a constant temperature control method and system for a chromatograph heating kit. Background Technology

[0002] In oil exploration logging, flame chromatograph (FID) is the core equipment for detecting oil and gas shows, and its operational stability directly affects the efficiency of oil and gas show detection and the progress of rapid drilling. The normal operation of the FID relies on a heating kit to provide a stable, constant temperature environment (typically 150℃±3℃), but existing chromatograph heating kits have the following technical shortcomings: 1. Defects in heating kit: The temperature probe is exposed and easily falls off and is damaged; the entry of high-temperature gas or condensate can easily cause a short circuit; the overheat protector threshold is unreasonable, and the overheat protection accuracy for core components such as FID is insufficient; the heater resistance error is large, making it difficult to guarantee constant temperature accuracy; and the heating components are disposable parts that cannot be repaired, making procurement difficult, and the equipment needs to be shut down for a long time to wait for replacement after damage.

[0003] 2. Temperature control circuit defects: The temperature control integrated circuit board lacks a specific protection mechanism for the heating component to malfunction. When the heating component fails, it is easy to burn out the circuit board as well, further expanding the scope of equipment damage.

[0004] 3. Control logic defects: The original control program has a fixed temperature monitoring frequency and does not consider the influence of ambient temperature and sample gas temperature; the logic design for temperature measurement, heating time, and heating interval is unreasonable, the temperature control range is wide (±3℃), and there is no differentiated adjustment of heating rate between the heating and isothermal stages, which easily leads to slow heating or excessive isothermal fluctuations; moreover, there is no emergency protection logic for the heating component failure, especially in extreme conditions such as low ambient temperature and low sample gas temperature in winter or high sample gas temperature in summer. The fixed control strategy cannot adapt to the temperature change requirements, resulting in poor analytical stability of the chromatograph and large data deviations.

[0005] The aforementioned defects result in a high failure rate of existing heating kits and frequent equipment downtime. In particular, it is difficult to guarantee constant temperature accuracy and analytical stability under extreme temperature conditions, which not only increases maintenance and procurement costs but also seriously affects the accuracy of oil and gas display detection data and drilling efficiency. Summary of the Invention

[0006] To address the above problems, the present invention provides a method for temperature control of a chromatograph heating kit, comprising the following steps: Obtain the initial ambient temperature and the initial sample gas temperature; The operating condition type is determined based on the initial ambient temperature and the initial sample gas temperature. The operating condition types include low temperature operating condition, normal temperature operating condition, and high temperature operating condition. During the heating and isothermal phases, corresponding initial control parameters are matched according to the operating condition type. Based on the PID control algorithm, the heating power of the heater is controlled according to the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters. During the heating phase, the heater temperature is raised to the target temperature within a set time. During the isothermal phase, the heater temperature is maintained at the target temperature, achieving isothermal adaptive regulation. The initial control parameters include heating power, temperature monitoring frequency, PID parameter combination, and adjustment frequency.

[0007] Furthermore, the PID parameter combination includes the proportional coefficient, integral time constant, and derivative time constant.

[0008] Furthermore, matching the corresponding initial control parameters according to the operating condition type includes the following steps: Establish a working condition-control parameter mapping database and store the initial control parameters corresponding to low temperature, normal temperature, and high temperature working conditions in different storage registers; After determining the operating condition, a fetch instruction is sent to the register to read all the initial control parameters corresponding to the current operating condition; The initial control parameters are automatically assigned to the control variables for each operating condition during the heating and constant temperature stages, thus completing parameter matching.

[0009] Furthermore, the proportional coefficient corresponding to each working condition is determined based on the working condition correction coefficient.

[0010] Furthermore, the operating condition correction factor is determined based on the ambient temperature correction factor, the difference between the ambient temperature and the normal temperature reference value, the sample gas temperature correction factor, and the difference between the sample gas temperature and the normal temperature reference value.

[0011] Furthermore, based on the PID control algorithm, the heating power of the heater is controlled according to the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters, including the following steps: The initial control parameters are adjusted based on the real-time ambient temperature and sample gas temperature. The real-time heater temperature and the adjusted control parameters are input into the PID control algorithm to determine the control voltage output to the heater. The control voltage is dynamically corrected by a temperature change rate correction coefficient, and the corrected control voltage is sent to the heater to control the heating power of the heater.

[0012] Furthermore, the read initial control parameters are automatically assigned to the control variables for each operating condition during the heating and isothermal stages, including: During the heating phase, the heating power gradually decreases under low temperature, normal temperature, and high temperature conditions, the proportional coefficient gradually decreases, and the integral time constant gradually increases; the differential time constant under high temperature conditions is greater than that under low temperature conditions; and the temperature monitoring frequency under low temperature conditions is greater than that under normal temperature and high temperature conditions. During the constant temperature stage, the adjustment frequency gradually decreases under low temperature, normal temperature, and high temperature conditions, the proportional coefficient gradually decreases, and the integral time constant gradually increases; the differential time constant under high temperature conditions is greater than that under low temperature conditions.

[0013] Furthermore, it also includes the following steps: A system fault is determined when any of the following conditions are met: power supply to the heater is cut off, an alarm is activated, and fault data is recorded: The first condition includes the overheat protector's temperature exceeding the threshold; the second condition includes the heater temperature monitored by the first temperature sensor exceeding the alarm threshold for a set time; the third condition includes the heater temperature change rate exceeding the preset value; and the fourth condition includes the ambient temperature or sample gas temperature exceeding the sensor's range.

[0014] Furthermore, it also includes the following steps: After confirming that the fault has been cleared, the ambient temperature and sample gas temperature are collected again to determine the operating condition type and match the control parameters for the corresponding operating condition before entering the preheating mode.

[0015] The present invention also provides a constant temperature control system for a chromatograph heating kit, including a heating kit, a temperature acquisition module and a temperature control integrated circuit board. The heating kit includes a heater and a first temperature sensor, the temperature acquisition module includes a second temperature sensor and a third temperature sensor, and the temperature control integrated circuit board includes a PLC. The second temperature sensor is used to obtain the initial ambient temperature, and the third sensor is used to obtain the initial sample gas temperature. The PLC is used to determine the operating condition type based on the initial ambient temperature and the initial sample gas temperature. The operating condition types include low temperature operating condition, normal temperature operating condition and high temperature operating condition. The first temperature sensor is used to send the acquired heater temperature to the PLC; The PLC is also used to match the corresponding initial control parameters according to the operating condition type during the heating and isothermal stages. Based on the PID control algorithm, it controls the heating power of the heater according to the real-time acquired heater temperature, ambient temperature, sample gas temperature and initial control parameters. During the heating stage, the heater temperature is raised to the target temperature within a set time. During the isothermal stage, the heater temperature is maintained at the target temperature, realizing isothermal adaptive regulation. The initial control parameters include heating power, temperature monitoring frequency, PID parameter combination and adjustment frequency.

[0016] Furthermore, the heating kit also includes a housing, an overheat protector, and an interface module; The heater, the first temperature sensor, the overheat protector, and the interface module are encapsulated in the housing and are all detachably connected to the housing.

[0017] Furthermore, the temperature control integrated circuit board also includes an LTC power module, a PLD, a signal amplification circuit, and a CAN bus communication interface; The LTC power module is electrically connected to the PLC, PLD, and signal amplifier circuit respectively; one end of the signal amplifier circuit is electrically connected to the first temperature sensor, the second temperature sensor, and the third temperature sensor, and the other end is connected to the PLC; the PLC and PLD are interconnected; one end of the CAN bus communication interface is connected to the PLC and PLD signals, and the other end is connected to the control terminal signal; the PLD is electrically connected to the heater.

[0018] The beneficial effects of this invention are: 1. This invention solves the problems of slow heating, large temperature fluctuations, and poor analytical stability under extreme conditions such as low temperatures in winter and high temperatures in summer by dynamically adjusting the heating power, monitoring frequency, and PID parameters based on ambient temperature and sample gas temperature. The temperature control range has been reduced from ±3℃ to ±1℃, and it can stably maintain constant temperature accuracy within the range of -40℃ to 85℃ ambient temperature and -20℃ to 100℃ sample gas temperature, meeting the high-precision working requirements of FID.

[0019] 2. This invention reduces the failure rate of the heating kit through hardware packaging optimization, dual fault protection, and adaptive control logic.

[0020] 3. The heating kit of the present invention has a fast response speed. Under low temperature conditions, it can heat up to the target temperature within 5 minutes, which is 30% shorter than the original solution. It can avoid overshoot and inefficient heating under normal temperature and high temperature conditions.

[0021] 4. The heating kit of the present invention has a simple structure and low cost.

[0022] 5. The heating kit of the present invention has strong compatibility, does not change the original working principle, installation specifications and measurement accuracy of the chromatograph, and can be directly adapted to existing related logging instruments, making it convenient for promotion and application.

[0023] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of a temperature control system for a chromatograph heating kit according to an embodiment of the present invention is shown. Figure 2 A schematic flowchart of a temperature control method for a chromatograph heating kit according to an embodiment of the present invention is shown. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," "longitudinal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings.

[0028] This invention provides a method and system for temperature control of a chromatograph heating kit, applicable to precise temperature control of the heating kit in a flame chromatograph (FID). By optimizing the heating kit parameters, designing a redundant protection temperature control circuit, and implementing adaptive adjustment control logic based on ambient temperature and sample gas temperature, high-precision temperature control of the heating kit is achieved. This solves problems such as the fragility of existing heating kits, low temperature control accuracy, difficulty in procurement, frequent equipment downtime, and poor analytical stability under extreme temperature conditions. It ensures stable operation of the chromatograph under different environmental and sample gas temperature conditions, and improves the reliability of oil and gas display detection.

[0029] like Figure 1 As shown, a constant temperature control system for a chromatograph heating kit includes a heating kit, a temperature acquisition module, a temperature control integrated circuit board, and a control terminal.

[0030] The heating kit features a modular design, including a heater encapsulated in a high-temperature resistant, heat-insulating shell, a first temperature sensor, an overheat protector, and an interface module. Each module is independently detachable and can be replaced individually if damaged, eliminating the need for a complete replacement.

[0031] The four modules of the heating kit in this embodiment of the invention are connected by internal wiring terminals instead of welding. If damaged, the first temperature sensor, heater and overheat protector can be replaced individually by disassembling the wiring terminals. The repair cost is only 1 / 5 of that of existing disposable kits.

[0032] The temperature acquisition module includes a second temperature sensor and a third temperature sensor. The temperature control integrated circuit board includes an LTC power supply module, a PLC (Programmable Logic Controller), a PLD (Programmable Logic Device), a signal amplification circuit, and a CAN bus communication interface. The PLC model is PIC16F84, and the PLD model is EPM7032LC44-15.

[0033] The signal output terminals of the heater, the first temperature sensor, and the overheat protector are all electrically connected to the temperature control integrated circuit board, and the output terminals of the second temperature sensor and the third temperature sensor are also electrically connected to the temperature control integrated circuit board.

[0034] The second temperature sensor is an ambient temperature sensor (temperature measurement range -40℃ to 85℃, accuracy ±0.5℃), and the third temperature sensor is a sample gas temperature sensor (temperature measurement range -20℃ to 100℃, accuracy ±0.3℃). These sensors collect data on the operating ambient temperature of the chromatograph. Temperature of the sample gas entering the chromatograph The sensor signal is preprocessed by the signal amplification circuit and then transmitted to the PLC.

[0035] The LTC power module is electrically connected to the PLC, PLD, and signal amplifier circuit to provide stable power to each unit. One end of the signal amplifier circuit is electrically connected to the first, second, and third temperature sensors, and the other end is connected to the PLC. The PLC and PLD are interconnected. One end of the CAN bus communication interface is connected to the PLC and PLD signals, and the other end is connected to the control terminal signal. The PLD is electrically connected to the heater.

[0036] The signal transmission path of this invention embodiment is as follows: the temperature signal collected by the temperature sensor (heating kit temperature sensor, ambient temperature sensor, sample gas temperature sensor) is preprocessed by the signal amplification circuit and then transmitted to the PLC. The PLC communicates with the computer via the bus. At the same time, the PLC communicates with the PLD, and the PLD executes the on / off control of the heater.

[0037] For example, the heating kit's outer shell is made of high-temperature resistant polytetrafluoroethylene heat insulation shell, and its overall size is consistent with the original chromatograph heating kit (compatible with the original installation position). The shell thickness is 5mm, and it has built-in heat insulation cotton to reduce heat loss during the heating process.

[0038] The outer casing features a snap-fit ​​and threaded fixing structure that matches the original chromatograph, eliminating the need for additional drilling and allowing direct replacement of the original heating kit. Installation takes ≤10 minutes.

[0039] For example, the heater is a DC24V heater, which includes a ceramic heating element and a metal heat sink structure, providing uniform heating and high heat transfer efficiency.

[0040] The heater is located in the middle of the housing, and the heat sink is wrapped around the ceramic heating element. The first temperature sensor probe is embedded into the center of the heat sink from the side of the housing (10mm deep) and makes close contact with the heat sink. The overheat protector is installed on one side of the heater and makes direct contact with the metal housing of the heater to ensure that the heater temperature can be detected quickly.

[0041] The heater in this embodiment of the invention controls the resistance error to 12Ω±0.3Ω, reducing the impact of resistance fluctuations on heating power and providing hardware assurance for constant temperature accuracy.

[0042] The first temperature sensor is encapsulated in a Φ3mm×200mm stainless steel tube, is a PT100 type, and has a measurement range of 0~300℃. The probe of the first temperature sensor is embedded in the center of the heater's heat sink to ensure accurate temperature measurement.

[0043] The first temperature sensor in this embodiment of the invention has waterproof and corrosion-resistant properties, and its temperature measurement range is extended to 0-300℃, improving the stability and range coverage of temperature measurement.

[0044] The overheat protector is a normally closed NC1 type with a threshold temperature of 165℃, which forms a reasonable protection range with the optimal operating temperature of FID (150℃), improving the overheat protection response accuracy. The overheat protector is connected in series with the heater, realizing overheat power-off protection at the hardware level.

[0045] The interface module includes a power interface (DC24V), a signal output interface (485 bus), and a circuit protection interface (fuse). The interface module is quick-plugged into the temperature control integrated circuit board.

[0046] All interfaces of the interface module use waterproof and sealed connectors, and the seams of the outer shell are sealed with sealant. The first temperature sensor is fully encapsulated in stainless steel to meet the requirements of the humid and corrosive working conditions at the drilling site.

[0047] The heater, first temperature sensor, and overheat protector in this embodiment of the invention are all standardized industrial parts with wide procurement channels, which solves the problem of difficulty in procuring special parts for existing kits.

[0048] The heating kit of this application has an integrated modular structure, which realizes the integrated design of heating, temperature measurement, protection and signal transmission without changing the original chromatograph installation specifications. It is compact, easy to replace and repairable, and solves the problems of existing heating kits being disposable and difficult to procure.

[0049] The sensor and temperature control integrated circuit board in this embodiment of the invention adopt a point-to-point connection method of "standardized bus + dedicated signal port", which follows the principle of "independent power supply, separate signal transmission, and separation of digital / analog signals". The connection method is standardized, has strong anti-interference ability, and is suitable for the complex electromagnetic environment of the chromatograph.

[0050] The temperature control integrated circuit board has a dedicated interface area, and all ports are designed to prevent incorrect insertion: the temperature control integrated circuit board includes a power port, a temperature sensor port, a control signal port, a communication port, and a protection circuit port.

[0051] The power supply ports include DC24VIN, DC5VOUT, and DC3.3VOUT. DC24VIN is connected to the LTC power module and is powered by the LTC power module. DC5VOUT is connected to the first temperature sensor, the second temperature sensor, the third temperature sensor, and the signal amplification circuit, and is used to power the sensors and the signal amplification circuit. DC3.3VOUT is connected to the PLC and PLD and is used to power the PLC / PLD.

[0052] The temperature sensor ports include analog signal ports (AI) and digital signal ports (DI), each adapted to different types of sensors. Control signal ports include a PLC-PLD communication port (SPI bus) and a heating circuit control port (OUT), with a CAN bus interface included in the communication port. Protection circuit ports include a heating circuit current monitoring port (AI) and a fault alarm output port (DO).

[0053] The first temperature sensor (RT1, PT100 type, analog output) of the heating kit is connected to the analog signal port (AI1) (three-wire system). The connection method is as follows: the red, black, and white leads of the first temperature sensor are connected to the +V, GND, and SIG ports of the analog signal port (AI1) respectively, and a 100Ω current-limiting resistor is connected in series. The signal is input through this port to the signal amplification circuit (IRFR9024N transistor) for preprocessing, and then transmitted to the A / D conversion module of the PLC. The first temperature sensor is powered by the DC5VOUT port.

[0054] The second temperature sensor (DS18B20, digital output) is connected to the digital signal port (DI). The connection method is as follows: the VCC and GND leads of the second temperature sensor are connected to the +5V and GND ports of the digital signal port (DI), and the DATA lead is connected to the SIG port of the digital signal port (DI). It communicates directly with the PLC's digital I / O module through the single bus protocol without signal amplification.

[0055] The third temperature sensor (PT100 type, analog output) is connected to the analog signal port (AI2) (three-wire system). The connection method is as follows: the red, black and white leads of the third temperature sensor are connected to the +V, GND and SIG ports of the analog signal port (AI2) respectively. After being connected in series with a 100Ω current limiting resistor, the signal is input to the signal amplification circuit, pre-processed and then transmitted to the A / D conversion module of the PLC.

[0056] The third temperature sensor is powered by the DC5VOUT port, which is separate from the power supply of the first temperature sensor to avoid mutual interference.

[0057] The heater is connected to the PLD via the heating circuit control port (OUT) of the temperature control integrated circuit board. The output pin of the PLD controls the on / off state of the heater. This port is also connected to the heating circuit current monitoring port (AI) to collect the heating circuit current in real time.

[0058] After the overheat protector is connected in series with the heater, one end is connected to the power interface (DC24V) of the interface module, and the other end is connected to the heating circuit control port (OUT). When the overheat protector is disconnected, the heating circuit is de-energized and a fault signal is sent to the DI2 port of the PLC.

[0059] The PLC and PLD communicate bidirectionally through the PLC-PLD communication port (SPI bus) (SCLK / MOSI / MISO / CS). The PLC sends heating control commands, and the PLD provides feedback on the heater's on / off status. The PLC connects to the control terminal via the CAN bus communication interface (CAN_H / CAN_L / GND) of the temperature control integrated circuit board to achieve data exchange and remote control. The output of the signal amplifier circuit is connected to the A / D conversion module port of the PLC, and the input of the signal amplifier circuit is connected to the analog signal port (AI1) and the analog signal port (AI2) to complete the amplification and filtering of the analog signal.

[0060] All temperature sensor leads in this embodiment of the invention use shielded twisted-pair cables with the shielding layer grounded to reduce electromagnetic interference on site; an opto-isolator is installed between the analog signal port and the digital signal port to avoid interference of the digital signal to the analog temperature measurement signal; all ports are equipped with varistors and fuses to prevent overvoltage and overcurrent from damaging the circuit board and the sensor.

[0061] like Figure 2 As shown, a method for temperature control of a chromatograph heating kit includes the following steps: S1. Initialization Phase: After the program starts, it performs self-checks on the PLC, first temperature sensor, second temperature sensor, third temperature sensor, and heater. After confirming that there are no faults, it synchronously acquires the initial ambient temperature through the second and third temperature sensors respectively. relative to the initial sample gas temperature .

[0062] S2, PLC based on initial ambient temperature relative to the initial sample gas temperature Determine the operating condition type, which includes low temperature operating condition, normal temperature operating condition, and high temperature operating condition.

[0063] The operating condition determination criteria include: Low temperature operating conditions: ambient temperature or sample gas temperature (e.g., in winter environments and when the sample gas temperature is low). Normal temperature operating conditions: and ; High-temperature operating conditions: or (e.g., in summer when the sample gas temperature is high).

[0064] S3. During the heating and isothermal phases, the PLC matches the corresponding initial control parameters according to the operating condition type. Based on the PID control algorithm, and using the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters, it controls the heater's heating power. During the heating phase, the heater temperature rises to the target temperature within a set time; during the isothermal phase, the heater temperature is maintained at the target temperature, achieving adaptive isothermal regulation. The initial control parameters include heating power, temperature monitoring frequency, PID parameter combination, and adjustment frequency. The PID parameter combination includes a proportional coefficient. Integral time constant and differential time constant .

[0065] After the PLC completes the working condition (low temperature / normal temperature / high temperature) determination, it realizes the automatic matching of control parameters through the pre-stored parameter mapping table and register assignment. The core is "one-click retrieval and direct assignment", which does not require additional calculation and ensures the initialization response speed.

[0066] The PLC matches the corresponding initial control parameters according to the operating condition type, including the following steps: S31. Establish a working condition-control parameter mapping database in the PLC program, and store the initial control parameters corresponding to low temperature, normal temperature and high temperature working conditions in different storage registers.

[0067] S32. After determining the operating condition, send a fetch instruction to the register to directly read all the initial control parameters corresponding to the current operating condition into the PLC calculation module. S33 and PLC will automatically assign the read initial control parameters to the control variables of each working condition in the heating and constant temperature stages to complete parameter matching. The matching process is completed within 0.1 seconds after the program initialization self-test is completed, without affecting the equipment startup efficiency.

[0068] For example, if the condition is determined to be a low-temperature condition, the PLC directly retrieves the low-temperature condition parameters from the register: heating power DC24V full load, monitoring frequency 0.2s / time, and heating stage. , After the value is assigned, the heating phase begins immediately. This represents the overall operating condition correction factor, used to dynamically adjust PID parameters.

[0069] The PID control algorithm is as follows:

[0070] In the formula, This indicates the control voltage (V) output from the PLC to the heater, with a value range of 0 to 24V; This represents the temperature deviation value, i.e., the target temperature. (150℃) and heater temperature (real-time measurement value of the first temperature sensor) The difference, ; This represents the scaling factor, with an initial calibration value of 1.2 to 1.5 (standard value 1.3). This represents the integration time constant, initially set to 20–30 s (standard value 25 s), used to eliminate steady-state error; This represents the differential time constant, initially set to 5–8 s (standard value 6 s), used to suppress temperature overshoot; The integral term representing the temperature deviation reflects the cumulative deviation; The differential term representing the temperature deviation reflects the rate of change of the deviation.

[0071] Existing PID temperature control technology only applies the basic PID algorithm to the temperature control of the chromatograph without any condition-adaptive adjustment. This application has made innovative improvements on the basic PID framework. The core is to make the PID algorithm strongly coupled with the environment and sample gas temperature to achieve "condition-adaptive PID", which is different from the "fixed parameter PID" of the existing technology.

[0072] This invention provides an additional operating condition correction coefficient. This enables dynamic quantitative adjustment of the core parameters of the PID controller, where the proportional coefficient corresponds to each operating condition. Based on the working condition correction factor Confirmed, details are as follows: = x

[0073] In the formula, x Represents the coefficient.

[0074] The embodiments of the present invention are as follows: The coefficient converts the deviation of the ambient / sample gas temperature into a correction value for the PID parameters, which increases under low-temperature conditions. Compensates for heat loss and reduces heat loss under high-temperature conditions. Increase Suppressing overshoot allows the PID algorithm to make precise adjustments across the entire ambient temperature range of -40℃ to 85℃.

[0075] Existing technologies separate the PID algorithm from the hardware control logic; this invention binds the PID parameter adjustment to the temperature monitoring frequency and heating power output, such as increasing the frequency under low-temperature conditions. At the same time, by increasing the monitoring frequency (0.2s / time) and outputting full-load power, the software adjustment of the PID algorithm and the hardware response are coordinated to achieve "software-hardware collaborative PID control", which is an improvement that has not been addressed by existing purely software PID algorithms.

[0076] The operating condition correction factor is determined based on the ambient temperature correction factor, the difference between the ambient temperature and the ambient temperature reference value, the sample gas temperature correction factor, and the difference between the sample gas temperature and the ambient temperature reference value, as detailed below:

[0077] In the formula, This represents the operating condition correction factor, used to dynamically adjust PID parameters; This represents the ambient temperature correction factor, with a value of 0.02 / ℃. Take the right time. When the time is negative; This indicates the difference between the ambient temperature and the normal temperature reference value (20℃). ; This represents the sample gas temperature correction factor, with a value of 0.03 / ℃. Take the right time. When the time is negative; This indicates the difference between the sample gas temperature and the normal temperature reference value (25℃). .

[0078] For example, piecewise adaptive PID parameter combination adjustment (combined with operating condition correction coefficients) is as follows: During the heating phase, the low-temperature operating condition is as follows: , , Normal temperature operating conditions: , , High-temperature operating conditions: , , .

[0079] During the constant temperature phase, low temperature operating conditions: , , Adjust frequency once per second; normal temperature operating conditions: , , Adjust the frequency once every 2 seconds; High-temperature operating conditions: , , Adjust the frequency once every 3 seconds.

[0080] PID proportional coefficient in existing technology Integral time constant Differential time constant Since the values ​​are fixed, they cannot adapt to temperature changes; this application calculates the overall operating condition correction factor based on the deviations of ambient temperature and sample gas temperature. and with By performing multiplicative coupling, the PID proportional coefficient changes in real time with the ambient / sample gas temperature, enabling condition-based quantitative correction of the PID parameters, rather than simple step-by-step adjustment.

[0081] Existing technologies do not distinguish between the heating and isothermal stages, using the same set of PID parameters throughout. This application divides PID control into heating and isothermal stages, and each stage is designed with differentiated PID parameter combinations based on low / normal / high temperature operating conditions (e.g., heating low temperature Ti=20s, isothermal low temperature Ti=23s; high temperature operating conditions introduce 2...). Kcorr correction factor (suppresses overshoot) enables dual matching of PID parameters with equipment operation stage and field conditions, solving the problems of "temperature rise overshoot and constant temperature fluctuation" in existing technologies.

[0082] The heating power of the heater is controlled based on the PID control algorithm, according to the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters. This includes the following steps: S34. Adjust the initial control parameters based on the real-time ambient temperature and sample gas temperature.

[0083] S35. Input the real-time heater temperature and the adjusted control parameters into the PID control algorithm to determine the control voltage output to the heater.

[0084] S36. The control voltage is dynamically corrected using a temperature change rate correction coefficient, and the corrected control voltage is then sent to the heater to control the heater's heating power, as detailed below:

[0085] In the formula, This indicates the corrected control voltage; This represents the temperature change rate correction coefficient, with a value ranging from 0.05 to 0.1 (optimal value 0.08). It is used to reduce the control voltage when the temperature changes too quickly, thus avoiding overshoot.

[0086] The initial control parameters read are automatically assigned to the control variables for each operating condition during the heating and isothermal stages, including: During the heating phase, the heating power gradually decreases under low temperature, normal temperature, and high temperature conditions, the proportional coefficient gradually decreases, and the integral time constant gradually increases; the differential time constant under high temperature conditions is greater than that under low temperature conditions; and the temperature monitoring frequency under low temperature conditions is greater than that under normal temperature and high temperature conditions.

[0087] For example, during the heating phase, the PLC outputs corresponding power according to the operating condition to achieve differentiated rapid heating: Low temperature condition: outputs maximum power (DC24V full load), and the temperature monitoring frequency is increased to once every 0.2 seconds to ensure that the temperature rises to the target temperature (150℃) within 5 minutes; Normal temperature condition: outputs 80% power, and the temperature monitoring frequency is once every 0.5 seconds to ensure that the temperature rises to the target temperature within 6 minutes; High temperature condition: outputs 60% power, and the temperature monitoring frequency is once every 0.5 seconds to avoid overshoot due to excessively rapid heating, and the temperature rises to the target temperature within 7 minutes.

[0088] During the constant temperature stage, the adjustment frequency gradually decreases under low temperature, normal temperature, and high temperature conditions, the proportional coefficient gradually decreases, and the integral time constant gradually increases; the differential time constant under high temperature conditions is greater than that under low temperature conditions.

[0089] For example, during the constant temperature phase, when the temperature reaches 149℃, it switches to constant temperature regulation mode, and the PLC adjusts the temperature based on real-time monitoring. and The heating power output frequency and PID parameters are dynamically adjusted to maintain the temperature within the range of 150℃±1℃.

[0090] Low temperature conditions: Increase the heating power output frequency (adjust once every 1 second), increase the proportional coefficient, and compensate for heat loss in low temperature environments; Normal temperature operation: The heating power output frequency is adjusted once every 2 seconds, using a standard proportional coefficient; High-temperature conditions: Reduce the heating power output frequency (adjust once every 3 seconds), reduce the proportional coefficient, and suppress temperature overshoot under high-temperature conditions.

[0091] Existing technologies only suppress overshoot through the derivative term of the PID controller, resulting in limited correction. This application adds a temperature change rate correction term to the basic PID output control voltage. By performing a secondary adjustment to the output voltage, when the temperature change rate is too fast (e.g., ...), the overshoot can be corrected. When the temperature exceeds 5℃ / s, the control voltage is automatically reduced to suppress overshoot directly from the output, thus compensating for the lag in the traditional PID differential term correction and achieving dual overshoot suppression through "algorithm calculation + output calibration".

[0092] S4. When any of the following conditions are met, a system fault is determined, the PLC immediately cuts off the heater power supply, activates the alarm, and records the fault data: The first condition includes the temperature of the overheat protector exceeding the threshold (e.g., 165°C), the second condition includes the heater temperature monitored by the first temperature sensor exceeding the alarm threshold (e.g., 151°C) for a set time (e.g., 3s), the third condition includes the heater temperature change rate exceeding the preset value (5°C / s), and the fourth condition includes the ambient temperature or sample gas temperature exceeding the sensor range (determined as sensor malfunction).

[0093] S5. After confirming that the fault has been cleared, the system will automatically restart and re-collect the ambient temperature. With sample gas temperature The system determines the operating condition type, matches the corresponding control parameters, enters the preheating mode, and can resume normal operation without manual intervention.

[0094] The core of the control strategy after the fault is cleared in this embodiment of the invention is "preheating transition + step-by-step loading + dynamic parameter correction", which is different from the direct temperature rise during the first start-up. This avoids damage to components caused by a sudden temperature rise after the fault is cleared, while ensuring constant temperature accuracy.

[0095] The process of determining fault clearance includes: when the PLC detects that the heater temperature has dropped to the safe threshold (≤140℃), the sensor signal has returned to normal, and the heater current is normal, the fault is determined to be cleared, the fault alarm is automatically reset and the fault record is cleared (only the ledger is kept).

[0096] The preheating mode includes: starting a low-power preheating stage, outputting 50% of the heating power for this operating condition, with a preheating time of 3 minutes. The temperature monitoring frequency during this stage is 1.5 times that of the heating stage for this operating condition (e.g., the preheating monitoring frequency for low-temperature operating conditions is 0.13s / time). The purpose is to ensure that the heating components are heated evenly and to avoid thermal shock.

[0097] Formal phase switching: After the preheating is completed, the PLC detects whether the temperature of the heating kit has reached the preheating threshold (80℃). If it has, it automatically switches to the normal heating phase of this condition and outputs the corresponding power, monitoring frequency and PID combination parameters according to the original control logic until the target temperature is reached and then enters the constant temperature phase. If it has not reached the target temperature, the preheating is extended by 1 minute. If it still has not reached the target temperature, the alarm is triggered again.

[0098] Constant temperature stage adaptation: After entering the constant temperature stage, the PID combination parameters and heating power adjustment frequency are dynamically adjusted according to the constant temperature control logic of the re-judgment working condition to maintain the temperature at 150℃±1℃.

[0099] Key features: No manual intervention is required throughout the process, and a "soft start" is achieved through a preheating mode, ensuring both equipment protection and control continuity.

[0100] This invention achieves temperature control accuracy of 150℃±1℃ within an environmental temperature range of -40℃ to 85℃ and a sample gas temperature range of -20℃ to 100℃. Through a three-layer technical system of "hardware foundation support + software adaptive adjustment + real-time fault suppression," it achieves high-precision temperature control over a wide temperature range, overcoming the limitation of existing technologies that can only achieve ±3℃ accuracy in a narrow temperature range. The specific implementation method is as follows: First layer: Eliminate hardware errors.

[0101] Sensor precision: The first temperature sensor of the heating kit is encapsulated in stainless steel, with a range extended to 0~300℃ and no dead zone in temperature measurement; the second temperature sensor (monitoring ambient temperature) and the third temperature sensor (monitoring sample gas temperature) are high-precision models (DS18B20±0.5℃, PT100±0.3℃), covering a wide range of -40℃~85℃ / -20℃~100℃, reducing errors from the source of temperature acquisition.

[0102] Low heater error: The heater resistance error is controlled within 12Ω±0.3Ω to avoid fluctuations in resistance that cause the heating power to fluctuate, thus ensuring the stability of the heating power.

[0103] Power supply stabilization: A stable DC24V power supply is adopted to avoid the impact of grid voltage fluctuations on heating power and provide a stable power input for constant temperature.

[0104] The second layer: Adaptive control logic dynamically compensates for heat loss / overshoot caused by temperature range.

[0105] Condition-based temperature control: Based on the ambient temperature and sample gas temperature, three major operating conditions are defined, and the heating power and monitoring frequency are designed differently to avoid slow heating in low temperature conditions and overshooting in high temperature conditions, so that the temperature can be stably reached to the target value, laying the foundation for the constant temperature stage. Wide-temperature-range dynamic correction of PID parameters: through The coefficient converts the deviations of ambient temperature and sample gas temperature into correction values ​​for PID parameters, increasing the correction value under low-temperature conditions. Compensates for heat loss and reduces heat loss under high-temperature conditions. Increase Suppressing overshoot allows the PID algorithm to make precise adjustments across the entire ambient temperature range of -40℃ to 85℃.

[0106] High-frequency / differentiated adjustment during constant temperature stage: heating power is adjusted every 1 second in low-temperature conditions to quickly compensate for heat loss in low-temperature environments; adjustment is made every 3 seconds in high-temperature conditions to avoid overheating and overshoot; adjustment is made every 2 seconds in normal-temperature conditions to balance efficiency and stability, achieving wide-range constant temperature by adjusting the frequency.

[0107] The third layer: real-time monitoring + threshold control to eliminate the accumulation of minor errors.

[0108] High-frequency temperature monitoring: Even in the high-temperature constant temperature stage with the slowest adjustment frequency, the temperature monitoring is still maintained at 0.5s / time, consistent with the heating stage, which can capture small temperature fluctuations in real time (within ±0.5℃) and avoid error accumulation. Dual temperature threshold control: The software sets an alarm threshold of 160℃, and the hardware sets an overheat protection of 165℃. When the temperature exceeds 151℃ (the upper limit of constant temperature) for 3 seconds, the heating circuit is immediately cut off to prevent temperature deviation from the source. Sensor fault detection: When the ambient temperature and sample gas temperature exceed the sensor's range, the sensor is immediately identified as faulty and the system is shut down to avoid incorrect temperature data causing the PID algorithm to be misadjusted, resulting in deviations in constant temperature accuracy.

[0109] This invention achieves rapid heating (from low temperature to 150°C in 5 minutes) not by simply increasing heating power, but through a collaborative design of "hardware power guarantee + software control optimization + heat loss compensation," as detailed below: 1. Hardware level: Providing full-load power is a fundamental guarantee for rapid heating. It adopts a stable DC24V power supply and outputs full-load heating power under low-temperature conditions (heater 12Ω±0.3Ω, full-load power). This provides the maximum heat input to the heating components, solving the problem of slow heating caused by insufficient power in existing technologies. However, full load power alone cannot achieve accurate and rapid heating (which can easily lead to local overheating and component damage).

[0110] 2. High-frequency monitoring and precise PID control enable "linear and rapid temperature rise" without any wasted time.

[0111] Ultra-high frequency temperature monitoring: The temperature monitoring frequency under low temperature conditions is increased to 0.2s / time, which is 2.5 times that under normal / high temperature conditions. It can capture the temperature changes of the heating kit in real time, allowing the PLC to adjust the control strategy in time and avoid the reduction in heating efficiency caused by "heating lag".

[0112] Adaptability PID parameters: Setting during the heating phase in low-temperature operating conditions (Maximum proportional coefficient) (Minimum integral time constant) The PID algorithm has the fastest adjustment response speed, which can quickly convert temperature deviation into heating power adjustment command, so that the temperature rises rapidly in a linear trend without fluctuation and time consumption.

[0113] Direct heating without preheating: There is no preheating stage in the low-temperature operation during the first start-up. After the fault is recovered, the low-temperature operation only requires 3 minutes of low-power preheating (far shorter than existing technologies). After the preheating is completed, the temperature is directly increased to full load, reducing the time for ineffective heating.

[0114] 3. Heat loss aspect: The operating condition correction coefficient compensates for low-temperature heat loss, allowing for effective utilization of heat input. In low-temperature environments, the heating element dissipates heat quickly, and existing fixed-power heating technologies suffer significant heat loss. This application passes... Increasing the PID proportional coefficient allows the output of heating power to compensate for heat loss in real time, ensuring that most of the input heat power is used to heat up the heating components rather than for heat dissipation from the environment, thereby improving heat utilization efficiency and indirectly accelerating the heating rate.

[0115] The temperature control system of the chromatograph heating kit in this embodiment of the invention includes steps of program burning and debugging / calibration before applying the high-precision temperature control of the heating kit.

[0116] Programming: The PLC program based on the above control method and PID calculation model is programmed into the PLC chip of the temperature control circuit board, setting the target temperature to 150℃, the alarm threshold to 160℃, the initial values ​​of PID parameters, and the operating condition judgment threshold. Debugging and calibration: Low-temperature operating condition simulation: The environmental test chamber was set to -20℃, and the sample gas temperature was 10℃. A 24-hour static test was conducted, monitoring the heating rate and temperature fluctuations, and adjustments were made accordingly. and The coefficient ensures that temperature fluctuations are within 150℃±1℃; it should be noted that the temperature parameter is not limited to 150℃±1℃, and the temperature can be set as needed.

[0117] Simulation of ambient temperature conditions: ambient temperature 25℃, sample gas temperature 30℃, to verify heating efficiency and isothermal stability; High-temperature operating condition simulation: ambient temperature 40℃, sample gas temperature 50℃, test the overshoot suppression effect to ensure no risk of temperature runaway; Field application: The assembled heating kit is installed on the relevant chromatograph and actual tests are conducted at the drilling site, covering different working conditions such as low temperature in winter and high temperature in summer, to verify the heating rate, temperature control accuracy, fault protection function and gas measurement data accuracy.

[0118] Operation monitoring: Real-time data collection of ambient temperature, sample gas temperature, heating kit temperature, operating time, and fault records via computer to create an equipment operation log and ensure traceability of abnormal situations.

[0119] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for temperature control of a chromatograph heating kit, characterized in that, Includes the following steps: Obtain the initial ambient temperature and the initial sample gas temperature; The operating condition type is determined based on the initial ambient temperature and the initial sample gas temperature. The operating condition types include low temperature operating condition, normal temperature operating condition, and high temperature operating condition. During the heating and isothermal phases, corresponding initial control parameters are matched according to the operating condition type. Based on the PID control algorithm, the heating power of the heater is controlled according to the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters. During the heating phase, the heater temperature is raised to the target temperature within a set time. During the isothermal phase, the heater temperature is maintained at the target temperature, achieving isothermal adaptive regulation. The initial control parameters include heating power, temperature monitoring frequency, PID parameter combination, and adjustment frequency.

2. The method for constant temperature control of the chromatograph heating kit according to claim 1, characterized in that, PID parameter combinations include proportional coefficient, integral time constant, and derivative time constant.

3. The method for constant temperature control of the chromatograph heating kit according to claim 1, characterized in that, Matching the corresponding initial control parameters according to the operating condition type includes the following steps: Establish a working condition-control parameter mapping database and store the initial control parameters corresponding to low temperature, normal temperature, and high temperature working conditions in different storage registers; After determining the operating condition, a fetch instruction is sent to the register to read all the initial control parameters corresponding to the current operating condition; The initial control parameters are automatically assigned to the control variables for each operating condition during the heating and constant temperature stages, thus completing parameter matching.

4. The method for constant temperature control of the chromatograph heating kit according to claim 2, characterized in that, The proportional coefficient corresponding to each working condition is determined based on the working condition correction coefficient.

5. The method for constant temperature control of the chromatograph heating kit according to claim 4, characterized in that, The operating condition correction factor is determined based on the ambient temperature correction factor, the difference between the ambient temperature and the normal temperature reference value, the sample gas temperature correction factor, and the difference between the sample gas temperature and the normal temperature reference value.

6. The method for constant temperature control of the chromatograph heating kit according to claim 1, characterized in that, Based on the PID control algorithm, the heating power of the heater is controlled according to the real-time acquired heater temperature, ambient temperature, sample gas temperature, and initial control parameters, including the following steps: The initial control parameters are adjusted based on the real-time ambient temperature and sample gas temperature. The real-time heater temperature and the adjusted control parameters are input into the PID control algorithm to determine the control voltage output to the heater. The control voltage is dynamically corrected by a temperature change rate correction coefficient, and the corrected control voltage is sent to the heater to control the heating power of the heater.

7. The method for constant temperature control of the chromatograph heating kit according to claim 5, characterized in that, The read initial control parameters are automatically assigned to the control variables for each operating condition during the heating and isothermal stages, including: During the heating phase, the heating power gradually decreases under low temperature, normal temperature, and high temperature conditions, the proportional coefficient gradually decreases, and the integral time constant gradually increases; the differential time constant under high temperature conditions is greater than that under low temperature conditions; and the temperature monitoring frequency under low temperature conditions is greater than that under normal temperature and high temperature conditions. During the constant temperature stage, the adjustment frequency gradually decreases under low temperature, normal temperature, and high temperature conditions, the proportional coefficient gradually decreases, and the integral time constant gradually increases; the differential time constant under high temperature conditions is greater than that under low temperature conditions.

8. The method for temperature control of the chromatograph heating kit according to any one of claims 1-7, characterized in that, It also includes the following steps: A system fault is determined when any of the following conditions are met: power supply to the heater is cut off, an alarm is activated, and fault data is recorded: The first condition includes the overheat protector's temperature exceeding the threshold; the second condition includes the heater temperature monitored by the first temperature sensor exceeding the alarm threshold for a set time; the third condition includes the heater temperature change rate exceeding the preset value; and the fourth condition includes the ambient temperature or sample gas temperature exceeding the sensor's range.

9. The method for constant temperature control of the chromatograph heating kit according to claim 8, characterized in that, It also includes the following steps: After confirming that the fault has been cleared, the ambient temperature and sample gas temperature are collected again to determine the operating condition type and match the control parameters for the corresponding operating condition before entering the preheating mode.

10. A temperature control system for a chromatograph heating kit, characterized in that, It includes a heating kit, a temperature acquisition module, and a temperature control integrated circuit board. The heating kit includes a heater and a first temperature sensor. The temperature acquisition module includes a second temperature sensor and a third temperature sensor. The temperature control integrated circuit board includes a PLC. The second temperature sensor is used to obtain the initial ambient temperature, and the third sensor is used to obtain the initial sample gas temperature. The PLC is used to determine the operating condition type based on the initial ambient temperature and the initial sample gas temperature. The operating condition types include low temperature operating condition, normal temperature operating condition and high temperature operating condition. The first temperature sensor is used to send the acquired heater temperature to the PLC; The PLC is also used to match the corresponding initial control parameters according to the operating condition type during the heating and isothermal stages. Based on the PID control algorithm, it controls the heating power of the heater according to the real-time acquired heater temperature, ambient temperature, sample gas temperature and initial control parameters. During the heating stage, the heater temperature is raised to the target temperature within a set time. During the isothermal stage, the heater temperature is maintained at the target temperature, realizing isothermal adaptive regulation. The initial control parameters include heating power, temperature monitoring frequency, PID parameter combination and adjustment frequency.

11. The temperature control system for the chromatograph heating kit according to claim 10, characterized in that, The heating kit also includes a housing, an overheat protector, and an interface module; The heater, the first temperature sensor, the overheat protector, and the interface module are encapsulated within the housing and are all detachably connected to the housing.

12. The temperature control system for the chromatograph heating kit according to claim 10, characterized in that, The temperature control integrated circuit board also includes an LTC power module, a PLD, a signal amplification circuit, and a CAN bus communication interface. The LTC power module is electrically connected to the PLC, the PLD, and the signal amplification circuit. One end of the signal amplification circuit is electrically connected to the first temperature sensor, the second temperature sensor, and the third temperature sensor, and the other end is connected to the PLC. The PLC and the PLD are interconnected. One end of the CAN bus communication interface is connected to the PLC and the PLD, and the other end is connected to the control terminal. The PLD is electrically connected to the heater.

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