Anti-backfire device for gas boiler

Abstract

The utility model relates to a backfire prevention device technical field, concretely relates to a backfire prevention device of gas boiler, including gas main pipe, gas main pipe is linked with one end of a plurality of gas branch pipe respectively, the other end of each gas branch pipe is connected with the burner, and the gas inlet end of gas main pipe is equipped with temperature sensor no.

Description

Technical Field

[0001] This utility model relates to the technical field of backfire prevention devices, specifically to a backfire prevention device for a gas-fired boiler. Background Technology

[0002] Gas-fired boilers generally adopt a mixed combustion mode of blast furnace and coke oven gas. The gas burners are double swirl gas burners, which are arranged in layers on the front and rear walls of the combustion chamber in the lower part of the boiler furnace.

[0003] Backfire refers to the reverse propagation of a flame into a gas branch pipe or main pipe. Its occurrence is usually closely related to factors such as gas supply conditions, combustion conditions, and equipment structure. For example, insufficient mixing of gas and air before the burner can lead to abnormal concentrations (too high or too low) in localized areas, potentially causing localized backfire. A sudden drop in gas pressure can cause a rapid decrease in pressure within the gas branch pipe, reducing the flow rate below the flame propagation speed, allowing the flame to propagate backward into the pipe. A malfunctioning quick-closing valve (such as a stuck solenoid valve or a leaking pneumatic pipeline) can prevent complete closure, resulting in continuous flame backfire. Backfire can damage gas burners, gas pipelines, and nearby instruments, and may even cause gas pipeline explosions.

[0004] To address backfire issues, current technologies typically involve either closing the quick-cut valve, directly introducing nitrogen for extinguishing, or simultaneously closing the quick-cut valve and introducing nitrogen. However, closing only the quick-cut valve may fail to suppress backfire if it cannot close effectively. Introducing nitrogen directly for extinguishing, or simultaneously closing the quick-cut valve, could lead to nitrogen misuse. For example, if a branch pipe shows only a very brief backfire and the gas quick-cut valve closes normally, nitrogen injection is unnecessary and violates energy-saving principles. Utility Model Content

[0005] To address the technical problem that existing technologies typically employ methods such as simply closing the quick-closing valve, directly introducing nitrogen, or introducing nitrogen while closing the quick-closing valve to resolve backfire issues, but where simply closing the quick-closing valve is insufficient to solve the backfire problem when it cannot be effectively closed, and directly introducing nitrogen or introducing nitrogen while closing the quick-closing valve leads to nitrogen abuse and violates energy-saving principles, this utility model provides a backfire prevention device for a gas-fired boiler.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A backfire prevention device for a gas-fired boiler includes a main gas pipe, which is connected to one end of a plurality of gas branch pipes. Each gas branch pipe is connected to a burner at the other end. A temperature sensor 1 is installed at the gas inlet end of the main gas pipe. Each gas branch pipe is equipped with a gas quick-cut valve and a temperature sensor 2. Each gas branch pipe is connected to a separate nitrogen pipeline. The connection between the nitrogen pipeline and the gas branch pipe is located between the gas quick-cut valve and the burner. Each nitrogen pipeline is equipped with a fire extinguishing solenoid valve. The temperature sensor 1, the gas quick-cut valve, the temperature sensor 2, and the fire extinguishing solenoid valve are all electrically connected to a controller. The controller is electrically connected to a timer.

[0008] Using the above technical solution, temperature sensor 1 can monitor the temperature of the main gas pipe in real time, and each temperature sensor 2 can monitor the temperature of the corresponding gas branch pipe in real time. The gas quick-cut valve is a switch that controls the gas flow in and out of the corresponding gas branch pipe, and the fire extinguishing solenoid valve is a switch that controls the flow of nitrogen in and out of the corresponding nitrogen pipeline connected to the gas branch pipe. The controller can receive signals from temperature sensor 1, temperature sensor 2 and timer, and determine whether backfire has occurred, whether the gas quick-cut valve has failed, and whether the backfire has stopped according to preset logic. Then, it issues action commands to the gas quick-cut valve and the fire extinguishing solenoid valve.

[0009] During normal combustion at the burner, the difference between temperature sensor 2 and temperature sensor 1 is small. When backfire occurs, the reverse flame propagation causes a sudden rise in the temperature of the gas branch pipe, and the difference between temperature sensor 2 and temperature sensor 1 exceeds a critical value (e.g., 100°C). After the backfire problem is resolved, the temperature of the gas branch pipe should decrease, and the difference between temperature sensor 2 and temperature sensor 1 should gradually decrease. Therefore, when the difference between temperature sensor 2 and temperature sensor 1 exceeds the critical value 1, the controller determines that backfire has occurred in the gas branch pipe corresponding to temperature sensor 2, immediately controls the corresponding gas quick-cut valve to close and starts a timer. If the timer exceeds a preset duration 1 and the difference between temperature sensor 2 and temperature sensor 1 has not decreased to the preset value, the gas quick-cut valve is considered to have failed. The controller then controls the corresponding fire extinguishing solenoid valve to open, injecting nitrogen into the gas branch pipe where backfire has occurred to prevent continued backfire from causing an explosion. After nitrogen is introduced, when the difference between temperature sensor 2 and temperature sensor 1 is less than the critical value 2, the controller controls the timer to start timing again. After a preset time of 2, if the difference between temperature sensor 2 and temperature sensor 1 is still less than the critical value 2, the controller determines that the backfire phenomenon has stopped and controls the fire extinguishing solenoid valve to close. This can prevent premature stopping of nitrogen supply and thus avoid reignition, as well as avoid wasting nitrogen.

[0010] This invention establishes a distributed monitoring and tiered fire suppression system by installing a temperature sensor 1 on the main gas pipe and a gas quick-cut valve and a temperature sensor 2 on each gas branch pipe, along with an independent nitrogen pipeline and a fire suppression solenoid valve. All components are electrically connected to a controller with a timer. Specifically, the system accurately identifies backfire by measuring the temperature difference between temperature sensors 1 and 2, avoiding misjudgments caused by environmental interference. The independent nitrogen pipeline enables directional control, injecting nitrogen only into the gas branch pipe where backfire occurs, without affecting the normal combustion of other burners. The gas quick-cut valve is used as the primary protection to prioritize fuel cut-off, and the timer, combined with continuous temperature monitoring, determines valve failure, activating the fire suppression solenoid valve to inject nitrogen only in case of failure. This system prevents nitrogen misuse, balances safety and energy saving, and effectively solves the technical problems of fire suppression failure due to quick-cut valve failure and nitrogen waste by preventing continuous backfire.

[0011] As a preferred implementation of a backfire prevention device for a gas-fired boiler, the second temperature sensor is located on the side of the gas quick-cut valve near the burner.

[0012] With the above-mentioned structural design, the second temperature sensor is located on the side of the gas quick-cut valve close to the burner. It can monitor the temperature changes near the burner in real time, quickly capture the temperature anomalies in the early stage of backfire, shorten the detection response time, give the valve a head start in closing and nitrogen injection, and reduce the risk of backfire damage to the branch pipe.

[0013] In a preferred implementation of a backfire prevention device for a gas-fired boiler, the second temperature sensor is located on the side away from the burner at the connection between the nitrogen pipeline and the gas branch pipe.

[0014] By adopting the above structural design, it is ensured that the temperature sensor 2 accurately reflects the true flashback state, preventing the false judgment that the flashback has been eliminated due to the cooling effect during nitrogen injection, which could lead to the valve not being closed or the nitrogen injection stopping prematurely, thus improving the reliability of fire extinguishing.

[0015] In a preferred implementation of a backfire prevention device for a gas-fired boiler, the main gas pipe and each gas branch pipe are installed vertically, and each nitrogen pipeline is installed parallel to the main gas pipe.

[0016] The above structural design creates a compact spatial layout and reduces the energy consumption of gas flow.

[0017] As a preferred implementation method for a backfire prevention device for a gas-fired boiler, the controller is a DCS controller or a PLC controller.

[0018] Using the above structural scheme, the DCS controller or PLC controller can realize complex logic operations and linkage control through programming.

[0019] As a preferred implementation of a backfire prevention device for a gas-fired boiler, the gas quick-cut valve is an electromagnetic quick-cut valve or a pneumatic quick-cut valve with an electromagnetic valve.

[0020] With the above structural design, the electromagnetic quick-cut valve or the pneumatic quick-cut valve with electromagnetic valve can be opened and closed quickly under the controller command, ensuring that the gas quick-cut valve can quickly cut off the gas supply in the early stage of backfire and reduce the flame backlash distance.

[0021] In a preferred implementation of a backfire prevention device for a gas-fired boiler, temperature sensor one and / or temperature sensor two are thermocouple temperature sensors.

[0022] With the above structural design, the thermocouple temperature sensor has a wide measurement range, fast response speed, and can adapt to high-temperature gas environments, accurately capturing the temperature change during backfire.

[0023] As a preferred implementation of a backfire prevention device for a gas-fired boiler, the controller is electrically connected to an audible and visual alarm.

[0024] With the above structural design, when backfire or valve failure is detected, the audible and visual alarm will sound simultaneously to remind operators to intervene in a timely manner, especially when the control room is unattended, to avoid the accident from escalating due to delays in manual inspection.

[0025] As a preferred implementation of the backfire prevention device for a gas-fired boiler, each nitrogen pipeline is equipped with a one-way valve, which only allows nitrogen to flow from the nitrogen pipeline to the gas branch pipe.

[0026] With the above structural design, when nitrogen is injected into the gas branch pipe through the nitrogen pipeline, the one-way valve opens normally, ensuring that nitrogen enters smoothly for fire extinguishing or inerting. If high-pressure gas backflows into the nitrogen pipeline due to backfire in the gas branch pipe, the one-way valve prevents the gas from flowing back into the nitrogen pipeline, avoiding contamination of the nitrogen system or secondary hazards. The one-way valve and the solenoid valve form a dual safety guarantee: the solenoid valve controls the nitrogen flow, and the one-way valve blocks reverse flow.

[0027] As a preferred implementation of a backfire prevention device for a gas-fired boiler, the outer wall of the gas main pipe is provided with an insulation layer.

[0028] By adopting the above structural design, the insulation layer reduces heat exchange between the gas main and the external environment, making the main pipe temperature detected by temperature sensor one more stable and avoiding errors in temperature difference judgment caused by ambient temperature fluctuations. When backfire occurs, temperature sensor two on the burner side will heat up rapidly, while the insulation layer ensures that the reading of main pipe temperature sensor one is not disturbed by external factors, improving the accuracy of the controller's backfire judgment.

[0029] The beneficial effects of this utility model include:

[0030] By installing temperature sensor 1 on the main gas pipe and gas quick-cut valves and temperature sensor 2 on each gas branch pipe, along with independent nitrogen pipelines and fire extinguishing solenoid valves, and electrically connecting all components to a controller with a timer, a distributed monitoring and graded fire extinguishing collaborative system is formed. Specifically: backfire is accurately identified through the temperature difference between temperature sensors 1 and 2, avoiding misjudgments caused by environmental interference; the independent nitrogen pipeline enables directional control, injecting nitrogen only into the gas branch pipe where backfire occurs, without affecting the normal combustion of other burners; the gas quick-cut valve is used as the primary protection to prioritize fuel cut-off, and the timer, combined with continuous temperature monitoring, determines whether the valve has failed, activating the fire extinguishing solenoid valve to inject nitrogen only when failure occurs. This not only prevents nitrogen misuse and balances safety and energy saving, but also effectively solves the technical problems of fire extinguishing failure and nitrogen waste by preventing continuous backfire. Attached Figure Description

[0031] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a backfire prevention device for a gas-fired boiler in a specific embodiment of this utility model.

[0033] List of components and reference numerals:

[0034] 1. Gas main pipe; 2. Gas branch pipe; 3. Burner; 4. Temperature sensor one; 5. Gas quick-cut valve; 6. Temperature sensor two; 7. Nitrogen pipeline; 8. Fire extinguishing solenoid valve; 9. Check valve. Detailed Implementation

[0035] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] Reference Figure 1This embodiment proposes a backfire prevention device for a gas-fired boiler, including a gas main pipe 1 with an insulation layer on its outer wall. The gas main pipe 1 is connected to one end of a plurality of gas branch pipes 2, and the gas main pipe 1 and each gas branch pipe 2 are arranged perpendicularly. The other end of each gas branch pipe 2 is connected to a burner 3. The gas inlet end of the gas main pipe 1 is equipped with a temperature sensor 4, which is a thermocouple temperature sensor. Each gas branch pipe 2 is equipped with a gas quick-cut valve 5 and a temperature sensor 6. The gas quick-cut valve 5 is an electromagnetic quick-cut valve or a pneumatic quick-cut valve with a solenoid valve, and the temperature sensor 6 is a thermocouple temperature sensor. Each gas branch pipe 2 is connected to a separate nitrogen pipeline 7. Each nitrogen pipeline 7 is arranged parallel to the main gas pipeline 1. The connection between the nitrogen pipeline 7 and the gas branch pipe 2 is located between the gas quick-cut valve 5 and the burner 3. Temperature sensor 6 is located on the side of the gas quick-cut valve 5 closer to the burner 3 and on the side of the connection between the nitrogen pipeline 7 and the gas branch pipe 2 away from the burner 3. Each nitrogen pipeline 7 is equipped with a fire extinguishing solenoid valve 8 and a one-way valve 9. The one-way valve 9 only allows nitrogen to flow from the nitrogen pipeline 7 to the gas branch pipe 2. Temperature sensor 4, gas quick-cut valve 5, temperature sensor 6, and fire extinguishing solenoid valve 8 are all electrically connected to a controller, which is a DCS controller or a PLC controller. The controller is electrically connected to a timer and also to an audible and visual alarm.

[0037] In this embodiment, temperature sensor 4 can monitor the temperature of the main gas pipe 1 in real time, and temperature sensors 6 can monitor the temperature of the corresponding gas branch pipe 2 in real time. Gas quick-cut valve 5 is a switch that controls the gas flow in and out of the corresponding gas branch pipe 2. Fire extinguishing solenoid valve 8 is a switch that controls the flow of nitrogen in the corresponding nitrogen pipeline 7 connected to the gas branch pipe 2. The controller can receive signals from temperature sensor 4, temperature sensor 6 and timer, and determine whether backfire has occurred, whether gas quick-cut valve 5 has failed, and whether backfire has stopped according to preset logic. Then, it issues action commands to gas quick-cut valve 5 and fire extinguishing solenoid valve 8.

[0038] Work process:

[0039] Under normal operating conditions, the mixed blast furnace and coke oven gas supplied by the main gas pipe 1 is delivered to the corresponding burners 3 through the gas branch pipes 2. The gas quick-cut valve 5 is in the open state, and the flameout solenoid valve 8 is in the closed state. Temperature sensor 4 monitors the temperature in the main gas pipe 1 in real time, and each temperature sensor 6 monitors the temperature in its corresponding gas branch pipe 2 in real time, continuously transmitting the temperature signal to the controller. At this time, the temperature difference between temperature sensor 6 and temperature sensor 4 is within a small normal range (e.g., 30-50℃), and the controller determines that each gas branch pipe 2 is burning normally, and the system is operating stably.

[0040] When a backfire occurs in a gas branch pipe 2, the reverse propagation of the flame causes the temperature of the branch pipe to rise sharply. The temperature monitored by temperature sensor 2 6 rises rapidly accordingly, and the difference between the temperature sensor 1 6 and temperature sensor 4 exceeds the critical value 1 (e.g., 100℃). The controller determines that a backfire has occurred in the gas branch pipe 2, quickly controls the corresponding gas quick-cut valve 5 to close, cuts off the gas supply to the branch pipe, starts the timer, and triggers the audible and visual alarm to alert the operator.

[0041] If the gas quick-cut valve 5 closes normally, the backfire in the gas branch pipe 2 will gradually extinguish as the gas supply is cut off, the temperature monitored by temperature sensor 2 6 will gradually decrease, and the difference between the temperature sensor 1 4 and the temperature sensor 2 4 will also decrease.

[0042] If the gas quick-closing valve 5 fails to close effectively due to a malfunction, and the timer exceeds the preset duration (e.g., 5 or 10 seconds), and the difference between temperature sensor 2 (6) and temperature sensor 4 (4) does not decrease to the preset value (e.g., 70°C or 60°C), the controller determines that the gas quick-closing valve 5 has failed. At this time, the controller controls the corresponding fire extinguishing solenoid valve 8 to open, and nitrogen gas is injected into the backfired gas branch pipe 2 through nitrogen pipeline 7 and one-way valve 9. The inertia of nitrogen gas suppresses flame combustion, preventing continued backfire from causing an explosion. During this process, one-way valve 9 prevents gas backflow into nitrogen pipeline 7, ensuring the safety of the nitrogen system.

[0043] After nitrogen is introduced, as the fire extinguishing process progresses, the temperature monitored by temperature sensor 26 continuously decreases, and the difference between it and temperature sensor 4 gradually decreases. When this difference is less than a critical value 2 (e.g., 50°C), the controller controls the timer to restart. After a preset duration 2 (e.g., 10 or 15 seconds), if the difference between temperature sensor 26 and temperature sensor 4 is still less than the critical value 2, the controller determines that the backfire has completely stopped and then controls the fire extinguishing solenoid valve 8 to close, stopping the nitrogen injection. This avoids premature stopping of nitrogen supply, which could lead to backfire and also prevents unnecessary waste of nitrogen.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A backfire prevention device for a gas-fired boiler, comprising a main gas pipe (1), wherein the main gas pipe (1) is connected to one end of a plurality of gas branch pipes (2), and the other end of each gas branch pipe (2) is connected to a burner (3), characterized in that, Temperature sensor 1 (4) is provided at the gas inlet end of the main gas pipe (1). Each gas branch pipe (2) is provided with a gas quick-cut valve (5) and a temperature sensor 2 (6). Each gas branch pipe (2) is connected to a separate nitrogen pipeline (7). The connection between the nitrogen pipeline (7) and the gas branch pipe (2) is located between the gas quick-cut valve (5) and the burner (3). Each nitrogen pipeline (7) is provided with a fire extinguishing solenoid valve (8). Temperature sensor 1 (4), gas quick-cut valve (5), temperature sensor 2 (6) and fire extinguishing solenoid valve (8) are all electrically connected to the controller. The controller is electrically connected to the timer.

2. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, Temperature sensor 2 (6) is located on the side of the gas quick-cut valve (5) near the burner (3).

3. The backfire prevention device for a gas-fired boiler according to claim 2, characterized in that, Temperature sensor 2 (6) is located on the side away from the burner (3) at the connection between nitrogen pipeline (7) and gas branch pipe (2).

4. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, The main gas pipe (1) and each gas branch pipe (2) are set vertically, and each nitrogen pipeline (7) is set parallel to the main gas pipe (1).

5. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, The controller is either a DCS controller or a PLC controller.

6. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, The gas quick-cut valve (5) is an electromagnetic quick-cut valve or a pneumatic quick-cut valve with an electromagnetic valve.

7. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, Temperature sensor one (4) and / or temperature sensor two (6) are thermocouple temperature sensors.

8. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, The controller is electrically connected to the audible and visual alarm.

9. The backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, Each nitrogen pipeline (7) is equipped with a one-way valve (9), which only allows nitrogen to flow from the nitrogen pipeline (7) to the gas branch pipe (2).

10. A backfire prevention device for a gas-fired boiler according to claim 1, characterized in that, The outer wall of the main gas pipe (1) is provided with an insulation layer.

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