Full-automatic safety type natural gas kiln drying system

Abstract

The invention relates to a full-automatic safety type natural gas kiln drying system. Comprising a PLC control unit, a combustion control module, a multi-type sensor assembly, a high-energy ignition device, a safety relief valve, a main control electromagnetic valve, an emergency cut-off valve, a pressure protection module, an alarm unit, a flow monitoring device, a manual adjusting valve, a manual throttling valve, a flexible connecting assembly, a gas injection pipe, an air supply unit and a rotary kiln body. Multi-sensor linkage control is integrated through a PLC intelligent center, a main and standby double-gas-supply redundant pipeline structure is innovatively adopted, a high-pressure / low-pressure double-protection mechanism and a flexible expansion joint design are combined, and full-closed-loop automatic control over the natural gas combustion process is achieved. An active safety system with flame detection interlocking ignition, pressure abnormity emergency cut-off and air volume dynamic matching is mainly constructed.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas drying kilns, and particularly relates to a fully automatic safety type natural gas drying kiln system. Background Art

[0002] As the core equipment for industrial high-temperature treatment, natural gas drying kiln systems are widely used in fields such as ceramics, metallurgy, building materials, and chemical engineering. They provide stable heat energy for rotary kilns through natural gas combustion to achieve the calcination, drying, or chemical reaction of materials. Traditional systems usually consist of a basic gas supply pipeline, a burner, an ignition device, and a simple control unit. They rely on manual experience to adjust the gas-to-air ratio and are supplemented by mechanical safety valves and single-point monitoring instruments to achieve basic operation. However, with the upgrade of industrial intelligence and the improvement of safety and environmental protection standards, the following technical problems have gradually emerged in the existing technology: insufficient automation control ability and poor process stability. The traditional system relies on manual inspection and manual adjustment for monitoring key parameters such as flame state, gas supply pressure, and kiln temperature, resulting in a lag in response and low accuracy; weak safety protection system and insufficient risk prevention and control ability. The existing system has a low redundancy in safety design and mostly relies on a single safety relief valve for overpressure protection, but the relief threshold is fixed and lacks linkage control with the pressure feedback unit; single monitoring dimension and lack of equipment health management. The traditional system has limited monitoring ability for the temperature field distribution in the kiln, overheating of the outer wall of the gas injection pipe, and pipeline pressure fluctuations; low structural reliability and high maintenance costs. The manual control valves and throttle valves in the gas supply pipeline are in a high-temperature and high-vibration environment for a long time, and problems such as spool wear and actuator jamming occur frequently. The traditional design does not adopt modular redundant interfaces, and the whole machine needs to be shut down and disassembled for maintenance, seriously affecting production efficiency. In addition, a flange rigid connection is used between the gas distribution component and the injection pipe, which is prone to misalignment stress during the thermal deformation of the kiln body or the settlement of the foundation, accelerating the aging of the sealing material and leading to an accumulation of leakage risks.

[0003] In summary, the existing natural gas drying kiln systems have significant defects in aspects such as automation control accuracy, safety redundancy design, multi-parameter collaborative monitoring, dynamic energy efficiency optimization, and structural reliability, resulting in low production efficiency, prominent safety hazards, and rising operation and maintenance costs. The industry urgently needs a fully automatic safety type natural gas drying kiln system integrating an intelligent sensing network, multi-level safety protection, adaptive control algorithms, and a highly reliable structure. Through real-time closed-loop control, main and standby gas supply redundant switching, multi-dimensional state perception, and flexible anti-vibration design, it can improve combustion stability, safety protection level, and equipment life, while reducing energy consumption and operation and maintenance costs, providing key technical support for the transformation of the industrial kiln furnace field towards intelligence and greenness, and promoting the sustainable development of the industry.

[0004] Content of the Invention Patent

[0005] The present invention patent provides a fully automatic safety type natural gas drying kiln system.

[0006] The innovation of this invention patent lies in the integrated multi-sensor linkage control through the PLC intelligent center, the innovative adoption of the main and standby dual gas supply redundant pipeline structure, combined with the high-pressure / low-pressure dual protection mechanism and the flexible expansion joint design, to achieve the full-closed-loop automatic control of the natural gas combustion process. An active safety system focusing on flame detection interlock ignition, abnormal pressure emergency cut-off, and dynamic air volume matching has been constructed.

[0007] To achieve the above-mentioned purpose of the invention patent, the technical solution of this invention patent is: a fully automatic safety-type natural gas drying kiln system, which is characterized by including: a PLC control unit, a combustion control module, a multi-type sensor assembly, a high-energy ignition device, a safety relief valve, a main control solenoid valve, an emergency cut-off valve, a pressure protection module, an alarm unit, a flow monitoring device, a manual regulating valve, a manual throttle valve, a flexible connection assembly, a gas injection pipe, a blower unit, and a rotary kiln main body. The multi-type sensor assembly includes a flame detection unit and a pressure feedback unit. The PLC control unit is electrically connected to the combustion control module, the multi-type sensor assembly, the safety relief valve, the main control solenoid valve, the pressure protection module, the alarm unit, and the flow monitoring device. The combustion control module is electrically connected to the high-energy ignition device. The natural gas input port is sequentially connected to a first shunt assembly, a second shunt assembly, and a gas distribution assembly through a gas supply pipeline. The input end of the first shunt assembly is connected to the natural gas input port, and its first output end is connected to the top interface of the second shunt assembly through a main gas supply branch, and the second output end is connected to the side interface of the second shunt assembly through a standby gas supply branch. Along the natural gas flow direction on the main gas supply branch, there are sequentially arranged the main flowmeter in the flow monitoring device, the main control solenoid valve, and the emergency cut-off valve. Along the natural gas flow direction on the standby gas supply branch, there are sequentially arranged the standby flowmeter in the flow monitoring device and the manual regulating valve. The bottom interface of the second shunt assembly is connected to the input end of the gas distribution assembly through a transition pipeline. Along the natural gas flow direction on the transition pipeline, there are sequentially arranged the high-pressure protector in the pressure protection module, the manual throttle valve, and the pressure feedback unit. The top interface of the gas distribution assembly is connected to the exhaust port through a pressure relief branch, and the safety relief valve is installed on the pressure relief branch. The output end of the gas distribution assembly is connected to the gas injection pipe through a gas transmission pipeline, and the flexible connection assembly is installed on the gas transmission pipeline. The outlet end of the gas injection pipe extends into the rotary kiln main body, and the high-energy ignition device and the flame detection unit are arranged at its outlet. The primary air inlet at the kiln head of the rotary kiln main body is connected to the blower unit through an air supply pipeline, and the air volume monitor in the flow monitoring device is arranged on the air supply pipeline. The PLC control unit is configured to control the start and stop of the high-energy ignition device based on the signal of the flame detection unit, and trigger the rapid closing of the emergency cut-off valve through the signal of the pressure feedback unit.

[0008] Furthermore, the multi-type sensor assembly also includes a temperature monitoring unit, which is arranged on the inner wall of the rotary kiln body and the outer wall of the gas injection pipe and is connected to the PLC control unit.

[0009] Furthermore, the pressure protection module includes a low pressure protector, which is set to a threshold value 20% lower than the system rated pressure. When a pressure abnormality is detected, the PLC control unit triggers the alarm unit to output an audible and visual alarm and links the manual regulating valve to open.

[0010] Furthermore, the air supply unit is a variable frequency fan, and its rotation speed is dynamically adjusted by the PLC control unit according to real-time flow data of the air volume monitor.

[0011] Furthermore, the flexible connection assembly is a bellows-type expansion joint for absorbing thermal expansion stress of the pipeline and reducing vibration transmission.

[0012] Beneficial effects:

[0013] 1. The PLC unit controls the start and stop of the high-energy ignition device in real time through the flame detection signal, and dynamically adjusts the speed of the variable frequency fan in combination with the air volume monitor data to achieve precise control of the air-fuel ratio. The temperature sensor monitors the thermal field distribution of the kiln body and the nozzle, and cooperates with the flow meter to build a combustion optimization model, which improves the thermal efficiency by more than 15% and reduces the unit energy consumption by 12% compared with the traditional system.

[0014] 2. The main and standby dual-branch gas supply design adopts a combination of main flow meter + solenoid valve and standby flow meter + manual valve. When the main line fails, the standby pipeline can be switched in seconds. The transition pipeline is equipped with a high-pressure / low-pressure protector. When a 20% pressure deviation is detected, an audible and visual alarm is triggered. With the emergency shut-off valve, a three-level protection is formed. The continuous operation rate of the system is increased to 99.8%, and the shutdown maintenance cycle is extended by 3 times.

[0015] 3. The flexible connection of the bellows expansion joint effectively absorbs the thermal stress deformation of the pipeline and reduces the vibration transmission rate by 60%. The gas distribution component integrates a safety pressure relief valve, which automatically opens the exhaust branch when overpressure occurs, and cooperates with the kiln temperature gradient monitoring to eliminate the hidden danger of structural deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the subject of the present invention.

[0017] Figure 2 It is a schematic diagram of the structure of the present invention. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings.

[0019] Embodiment 1: The specific implementation of a fully automatic safety type natural gas drying kiln system is as follows: The rotary kiln body selects a high-temperature resistant stainless steel cylinder with a model of HY-5.0×80, an inner diameter of 5.0 meters, a length of 80 meters, and an inclination angle designed to be 3.5%. The rotation speed is steplessly adjusted within the range of 0.5 to 4 revolutions per minute by a variable frequency motor with a power of 75 kilowatts. 8 groups of gas injection pipes made of 06Cr19Ni10 are evenly arranged in the kiln head combustion chamber. The outer diameter of a single pipe is 108 millimeters and the wall thickness is 6 millimeters. The center distance between adjacent injection pipes is 500 millimeters, and the tolerance is controlled within plus or minus 5 millimeters. The outlet end of each group of injection pipes is integrated with a high-energy ignition device with a model of HND-20S, whose ignition energy output range is 50 to 80 millijoules, and the spark generation frequency is 2 hertz. At the same time, an infrared flame detection unit with a model of TSL260R is equipped. The response time of this sensor does not exceed 0.1 second, the detection wavelength is accurately locked at 4.35 micrometers, and the allowable deviation range is plus or minus 0.1 micrometer.

[0020] The main natural gas supply branch uses a seamless stainless steel pipe with a nominal diameter of 150 millimeters, a wall thickness of 6 millimeters and a pressure bearing capacity of 1.6 megapascals. The main flowmeter selects an LUXZ-150 type instrument with an accuracy class of 0.5, a measuring range covering 0 to 2000 standard cubic meters per hour, and outputs a 4 to 20 mA current signal. The standby flowmeter adopts the same model for redundant configuration to form a dual metering system. The main control solenoid valve is powered by DC 24 volts, the action time is less than 1 second and the protection level reaches IP67. A pneumatic emergency cut-off valve with a model of SMC VFS5120-5DZ is connected in series downstream of it. This valve can complete the closing action within 0.5 seconds after losing power. The standby gas supply branch uses a pipe with a nominal diameter of 100 millimeters and is equipped with a Q41F-16P type ball valve as a manual regulating valve. The valve opening has a linearly adjustable function from 30% to 100% and is equipped with a scale indicating device. The transition pipe selects a specification with a nominal diameter of 200 millimeters, installs a YTX-150 type electric contact pressure gauge as a high-pressure protector, sets the threshold value at 0.5 megapascals and allows a plus or minus 2% deviation. At the same time, an SNS-B20 type pressure switch is configured as a low-pressure protector, the trigger threshold is 0.32 megapascals and it has an accuracy of plus or minus 1.5%. The pressure feedback unit uses an MPX5700AP type piezoelectric sensor, with a measuring range of 0 to 0.6 megapascals and the full-scale error does not exceed plus or minus 0.5%.

[0021] The air blower unit adopts a Y5-48-12.5D type variable-frequency centrifugal fan, with a motor power of 55 kilowatts. The drive frequency can be continuously adjusted between 15 and 50 hertz. The output air volume range is 2000 to 8000 cubic meters per hour, and the total wind pressure reaches 4500 pascals. The air volume monitor selects an FMG-300 type ultrasonic flowmeter with a measurement accuracy of plus or minus 1.5%. The real-time data is connected to a Siemens S7-1200 type PLC control unit. This unit is configured with an SM1231 analog input module and an SM1222 digital output module, and has a PID control algorithm with a proportional coefficient of 1.2 and an integral time of 60 seconds, dynamically adjusting the fan speed to keep the air-fuel ratio stable at an ideal value of 10 to 1, with an allowable fluctuation range of plus or minus 0.5. The flexible connection component selects a JZW-DN200 type multi-layer stainless steel bellows expansion joint, with an axial compensation amount of plus or minus 15 millimeters, a pressure resistance of 1.0 megapascal, and a fatigue life exceeding 5000 cycles. The gas distribution component is a distribution cylinder made of Q345R material, with a volume of 2 cubic meters, a design pressure of 0.6 megapascal, and 8 air outlets evenly distributed on the top. A spring-type safety relief valve of type A41H-16C is installed on the pressure relief branch, and its opening pressure is set at 0.48 megapascal and allows a deviation of plus or minus 3%. The reseating pressure difference is controlled within 10% of the opening pressure.

[0022] During the operation of the system, the PLC collects temperature data through 6 K-type thermocouples with a measuring range of 0 to 1300 degrees Celsius in the kiln head area, 4 thermocouples with a range of 0 to 1000 degrees Celsius in the kiln middle area, and 2 thermocouples with a range of 0 to 500 degrees Celsius in the kiln tail area. Combining with the monitoring values of the PT100 temperature sensors on the outer wall of the gas injection pipe, it calculates the combustion intensity in real time and outputs control signals. The opening of the main control solenoid valve is linearly adjusted from 0 to 100% with a resolution of 0.1%, and the air supply frequency is synchronously adjusted to match the heat load demand. When the flame detection unit fails to detect the flame characteristic spectrum for 200 milliseconds continuously, or the pressure sensor monitors that the high pressure exceeds 0.5 megapascal, the low pressure is lower than 0.32 megapascal, and the abnormal state lasts for 5 seconds, the PLC immediately triggers the emergency cut-off valve closing procedure, completes the standby pipeline switching within 3 seconds, and at the same time starts a HAD-102B type audible and visual alarm with a sound pressure level above 85 decibels, outputting a fault code of E01 pressure abnormality or E02 flame failure. After being verified by the national standard GB / T 10180, the system thermal efficiency reaches 92.3%, the gas consumption is reduced by 18.7% compared with traditional equipment. After continuous operation for 1000 hours, the performance indicators of the key components show that the axial displacement of the bellows expansion joint is less than 8 millimeters, and the zero drift of the main flowmeter is lower than 0.2% of the full scale, fully meeting the requirements of fully automated and safe operation.

[0023] In summary, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the claims of the present invention.

Claims

1. A fully automatic and safe natural gas kiln drying system, characterized in that: include: PLC control unit, combustion control module, multi-type sensor components, high-energy ignition device, safety pressure relief valve, main control solenoid valve, emergency shut-off valve, pressure protection module, alarm unit, flow monitoring device, manual regulating valve, manual throttle valve, flexible connection component, gas injection pipe, air supply unit and rotary kiln body, the multi-type sensor components include flame detection unit and pressure feedback unit, the PLC control unit is electrically connected with the combustion control module, multi-type sensor components, safety pressure relief valve, main control solenoid valve, pressure protection module, alarm unit and flow monitoring device, the combustion The control module is electrically connected to the high-energy ignition device, and the natural gas input port is connected to the first flow diversion component, the second flow diversion component and the gas distribution component in sequence through the gas supply pipeline. The input end of the first flow diversion component is connected to the natural gas input port, and its first output end is connected to the top interface of the second flow diversion component through the main gas supply branch, and the second output end is connected to the side interface of the second flow diversion component through the backup gas supply branch. The main flow meter in the flow monitoring device, the main control solenoid valve and the emergency shut-off valve are arranged in sequence along the natural gas flow direction on the main gas supply branch, and the backup gas supply branch is connected to the top interface of the second flow diversion component through the backup gas supply branch. The backup flow meter and the manual regulating valve in the flow monitoring device are sequentially arranged along the natural gas flow direction, the bottom interface of the second flow diversion component is connected to the input end of the gas distribution component through a transition pipeline, the high-pressure protector in the pressure protection module, the manual throttle valve and the pressure feedback unit are sequentially arranged on the transition pipeline along the natural gas flow direction, the top interface of the gas distribution component is connected to the exhaust port through a pressure relief branch, the safety pressure relief valve is installed on the pressure relief branch, the output end of the gas distribution component is connected to the gas injection pipe through a gas delivery pipeline, the flexible connection component is installed on the gas delivery pipeline, the outlet end of the gas injection pipe extends to the inside of the rotary kiln body, and the high-energy ignition device and the flame detection unit are arranged at its outlet, the kiln head primary air inlet of the rotary kiln body is connected to the air supply unit through an air supply pipeline, the air supply pipeline is provided with the air volume monitor in the flow monitoring device, and the PLC control unit is configured to control the start and stop of the high-energy ignition device based on the signal of the flame detection unit, and trigger the rapid closing of the emergency shut-off valve through the signal of the pressure feedback unit.

2. The fully automatic and safe natural gas kiln drying system according to claim 1 is characterized in that: The multi-type sensor assembly further includes a temperature monitoring unit, which is arranged on the inner wall of the rotary kiln body and the outer wall of the gas injection pipe and is connected to the PLC control unit.

3. The fully automatic and safe natural gas kiln drying system according to claim 1 is characterized in that: The pressure protection module includes a low-pressure protector, which is set to a threshold value that is 20% lower than the system rated pressure. When a pressure abnormality is detected, the PLC control unit triggers the alarm unit to output an audible and visual alarm and links the manual regulating valve to open.

4. The fully automatic and safe natural gas kiln drying system according to claim 1 is characterized in that: The air supply unit is a variable frequency fan, and its rotation speed is dynamically adjusted by the PLC control unit according to the real-time flow data of the air volume monitor.

5. The fully automatic and safe natural gas kiln drying system according to claim 1 is characterized in that: The flexible connection assembly is a bellows-type expansion joint for absorbing pipeline thermal expansion stress and reducing vibration transmission.

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