CN-121978882-A - Direct safety interlocking method of combustible gas detector and fan without PLC

CN121978882ACN 121978882 ACN121978882 ACN 121978882ACN-121978882-A

Abstract

The invention belongs to the technical field of combustible gas safety protection, and discloses a direct safety interlocking method of a combustible gas detector and a fan without a PLC, which provides a direct safety interlocking system of the combustible gas detector and the fan without the PLC, comprising a combustible gas detection unit, a core control unit, a fan driving unit, a power supply guarantee unit and a state feedback unit; all units are directly connected through hard wires without an intermediate programmable control module, all logic judgment and action triggering are completed by a hardware circuit, and a core control unit adopts an analog signal comparator and relay logic combination design and is internally provided with a two-way signal processing channel and a fault signal identification circuit. The invention abandons the dependence of PLC, simplifies the control link, shortens the response time, improves the reliability through redundant design and fault self-detection, reduces the cost and maintenance difficulty, and adapts to the safety protection requirement of a small-sized scene.

Inventors

TIAN JIANBIN
ZHOU JINLONG
WANG JIANSHU
LI DONG
GONG JIA
MA LIN
WU WEIPENG

Assignees

山西国化能源有限责任公司

Dates

Publication Date: 20260505
Application Date: 20260206

Claims (10)

1. A direct safety interlocking system of a combustible gas detector and a fan without a PLC is characterized by comprising a combustible gas detection unit, a core control unit, a fan driving unit, a power supply guarantee unit and a state feedback unit, wherein the units are directly connected through hard wires, an intermediate programmable control module is not needed, all logic judgment and action triggering are completed by a hardware circuit, and the core control unit adopts a logic combination design of an analog signal comparator and a relay and is internally provided with a two-way signal processing channel and a fault signal identification circuit.
2. The system of claim 1, wherein the combustible gas detection unit adopts a two-way parallel catalytic combustion type gas sensor, a signal amplification and temperature and humidity compensation circuit is arranged in the sensor, 4-20mA analog signals or 24vDC are output, a fault self-checking function is integrated, abnormal signals can be output when a wire is broken and an element fails, and the two-way sensor forms double-point detection redundancy and is arranged corresponding to two detection points.
3. The system of claim 1, wherein the core element of the core control unit is a four-channel voltage comparator, the four-channel voltage comparator is matched with a precision potentiometer to set a gas concentration alarm threshold, the two-channel signal processing channels are respectively connected with sensor signals of two detection points in a butt joint mode, each channel comprises a signal conversion circuit and a logic judgment circuit, the signal conversion circuit converts 4-20mA analog signals into 0-5V voltage signals or directly controls 24vDC generated by flammable triggering, and the logic judgment circuit forms logic of 'any detection point is out of standard, namely triggering action'.
4. The system according to claim 1, wherein the fan driving unit adopts a combination structure of an alternating current contactor and a thermal overload protection relay, the alternating current contactor is adapted to a 380V three-phase or 220V single-phase exhaust fan, overload protection current set by the thermal overload protection relay is 1.2 times of rated current of the fan, and an auxiliary contact of the alternating current contactor is connected with the core control unit to form action closed loop verification.
5. The system according to claim 1, wherein the power supply guaranteeing unit adopts a two-way power supply design, the main power supply is AC220V commercial power, the main power supply is converted into DC24V through a switching power supply to supply power for the detecting unit and the control unit, the standby power supply is a lithium battery pack and is provided with an automatic switching module.
6. The system of claim 1, wherein the status feedback unit comprises an audible and visual alarm and a status indicator light, the audible and visual alarm comprises a high decibel buzzer and a red LED strobe light, and the status indicator light is divided into a power indicator light, a detection normal indicator light, a fan operation indicator light and a fault indicator light, which are all directly connected to the signal output end of the core control unit.
7. A method for directly and safely interlocking a flammable gas detector without a PLC with a fan, which is realized based on the system of any one of claims 1-6 and comprises the following steps: After the mains supply is connected, the power supply guarantee unit outputs stable DC24V voltage to supply power, the core control unit completes self-checking and signal calibration of the detection unit, the system enters a standby monitoring state after the calibration is completed, and the fan is in a stop state; The normal monitoring and leakage linkage starting comprises the steps that a two-way sensor detects the concentration of combustible gas in real time and transmits a signal, the signal is a 4-20mA analog signal or 24V DC, a core control unit processes the signal and then compares the signal with a preset threshold value, and when any sensor detects that the concentration exceeds the standard, the core control unit triggers an internal relay to act, controls a fan driving unit to start a fan, and simultaneously starts an audible and visual alarm; The operation closed loop verification and fault emergency treatment comprises the steps of detecting the running state of the fan through an auxiliary contact of an alternating current contactor, keeping running until the concentration reaches the standard after normal starting, delaying stopping, triggering a fault alarm when the fan is started, triggering a corresponding fault prompt by a system when the sensor fails or the mains supply is interrupted, and meanwhile forcedly starting the fan or switching a standby power supply to maintain monitoring and interlocking capability.
8. The method of claim 7, wherein the preset threshold voltage corresponds to 25% of the lower limit of the flammable gas explosion, and the core control unit delays the switching off of the blower power supply for 30 seconds or manually stops the blower after the personnel confirm the safety after the blower is started and the gas concentrations detected by the two sensors are lower than the threshold voltage.
9. The method of claim 7, wherein the fan start fault determination condition is that the auxiliary normally open contact of the alternating current contactor is not closed within 1 second after the core control unit triggers the relay to act, and the audible and visual alarm is switched to intermittent alarm at the moment, so that the fault indicator lamp is normally on.
10. The method according to claim 7, wherein the sensor fault is identified by detecting an analog signal exceeding a normal range of 4-20mA or a 24V DC abnormal signal, and the core control unit forcibly starts the fan when the fault occurs and simultaneously controls the audible and visual alarm to intermittently alarm, and the fault indicator lamp is normally on.

Description

Direct safety interlocking method of combustible gas detector and fan without PLC Technical Field The invention belongs to the technical field of combustible gas safety protection, and particularly relates to a direct safety interlocking method of a combustible gas detector and a fan without a PLC. Background In the scenes of chemical industry storage, kitchen, laboratory, gas transmission station generator, room boiler room and the like, the leakage of the combustible gas can cause safety accidents such as explosion and fire disaster, so that the linkage control is established with the fan through the combustible gas detector, the fan is started in time to discharge the leaked gas when the gas leaks, and the safety risk is reduced. The existing combustible gas detection and fan linkage system is multi-dependent on a Programmable Logic Controller (PLC) to realize signal processing, logic judgment and action triggering, and the PLC has the advantage of flexible programming and is suitable for complex control scenes. In a small-sized protection scene, however, the PLC has obvious disadvantages that firstly equipment purchase, programming debugging and later maintenance costs are high and exceed the cost bearing range of the small-sized scene, secondly, the PLC needs to be subjected to multiple links such as signal acquisition, program operation, instruction output and the like, a control link is long, so that the response time from gas leakage detection to fan starting is prolonged, the potential safety hazard is increased, thirdly, the PLC depends on software program operation and is easy to be influenced by electromagnetic interference and program faults, the reliability of a linkage system is reduced, fourthly, the requirement of the small-sized scene on control logic is simple, the complex function redundancy of the PLC is improved, and the system fault rate is improved. The existing PLC-free cascading scheme is controlled by adopting a single sensor and a simple relay, lacks redundancy design and fault self-checking capability, is easy to cause the problems of missing report, false report or incapability of triggering cascading actions normally after fault, and is difficult to meet the core requirements of safety protection. Therefore, a direct safety linkage scheme of the PLC-free flammable gas detector and the fan, which has the advantages of simple structure, low cost, rapid response and high reliability, is needed to adapt to the safety protection requirement of a small-sized scene. Disclosure of Invention In order to overcome the technical problems, the invention provides a direct safety interlocking method of a flammable gas detector without a PLC and a fan. The invention adopts the following technical scheme: A direct safety interlocking system of a combustible gas detector and a fan without a PLC comprises a combustible gas detection unit, a core control unit, a fan driving unit, a power supply guarantee unit and a state feedback unit, wherein the units are directly connected through hard wires, an intermediate programmable control module is not needed, all logic judgment and action triggering are completed by a hardware circuit, and the core control unit adopts an analog signal comparator and relay logic combination design and is internally provided with a two-way signal processing channel and a fault signal identification circuit. Preferably, the combustible gas detection unit adopts a two-way parallel catalytic combustion type gas sensor, a signal amplification and temperature and humidity compensation circuit is arranged in the sensor, 4-20mA analog signals or 24V DC are output, a fault self-checking function is integrated, abnormal signals can be output when a wire is broken and an element fails, and the two-way sensor forms double-point detection redundancy and is arranged corresponding to two detection points. Preferably, the core element of the core control unit is a four-channel voltage comparator matched with a precision potentiometer to set a gas concentration alarm threshold, the two-channel signal processing channels are respectively connected with sensor signals of two detection points in a butt joint mode, each channel comprises a signal conversion circuit and a logic judgment circuit, the signal conversion circuit converts 4-20mA analog signals into 0-5V voltage signals (or directly controls 24V DC generated through combustible triggering), and the logic judgment circuit forms logic of 'any detection point exceeds standard, namely triggering action'. Preferably, the fan driving unit adopts a combined structure of an alternating current contactor and a thermal overload protection relay, the alternating current contactor is adapted to a 380V three-phase (or 220V single-phase) exhaust fan, overload protection current set by the thermal overload protection relay is 1.2 times of rated current of the fan, and an auxiliary contact of the alternating current contactor is connected with th