Infrared monitoring of bunker temperature in coal industry

2021/06/28 category：Furnace Metallurgy Energy & Chemical 资讯中心 2579

Project background

The periodic static storage of coal bunker is easy to cause the accumulation of temperature, CH4, CO gas concentration and so on, resulting in spontaneous combustion. When these gases gathered in the coal dust are raised at the discharge port and encounter oxygen in the air, they will aggravate spontaneous combustion and even explosion. If there is a fire in the storage place, it will cause great harm to human body and the environment, and pollute the water source, atmosphere and soil. The traditional fire-fighting equipment cannot always contact the flammable and dangerous fire source in the large and deep bunker.

1.The spontaneous combustion of coal in coal bunker brings a series of problems and hazards to the safety production of the factory

1) The temperature of spontaneous combustion coal exceeds 350 degrees Celsius, which is enough to ignite the belt unit during transmission, or it is transported to the raw coal bunker of the boiler. The pulverized coal accumulated in the bunker causes a fire, which threatens the normal and safe operation of the unit.

2) The surface layer of the side wall of the annular steel structure in the coal yard was burned and peeled off by spontaneous combustion, which caused the exposure of the hoop bearing reinforcement for a long time, reduced the bearing capacity of the wall, and made the wall of the storage yard have serious safety hazards such as fracture and collapse.

3) Spontaneous combustion produces a large amount of acid oxide toxic gas, which pollutes the air in and around the plant. It is easy to cause physical injury for on-site operators to work in such an environment for a long time.

4) The calorific value loss is serious. The spontaneous combustion and oxidation of stored coal will cause serious coal ashing, hinder the energy conservation and emission reduction work of the factory, and affect the production and operation benefits of the factory.

Infrared application

1. Fire prevention

Preferred tool for fire prevention infrared thermal imager

Infrared images show hot spots in waste. This means that there is a risk of spontaneous combustion and fire.

2. Application of infrared thermal imager in coal bunker industry

The infrared thermal imaging coal bunker anti spontaneous combustion monitoring, early warning and alarm system has the characteristics of non-contact temperature measurement, which can detect the abnormal temperature rise before the fire in advance. At the same time, monitor the fire coal in the feed, judge and alarm to avoid causing greater losses. The system has fast response and accurate temperature measurement. It can monitor the coal bunker all day and prevent fire in advance.

The monitoring system mainly adopts the infrared thermal imager as the temperature acquisition sensor and the PTZ as the operation carrier, so that it can fully monitor the temperature changes on the surface of the whole strip bunker. When the temperature reaches the preset temperature threshold, the system software displays the alarm temperature and the location image of high temperature, so as to prevent the spontaneous combustion of coal from causing economic losses and safety accidents.

3. The coal bunker industry uses infrared thermal imager for non-contact temperature measurement

The monitoring front end is installed on the berm of the strip coal bunker, and the whole stockyard realizes continuous temperature measurement without blind spots, ensuring the safety and reliability of the system structure. Under the condition that the normal operation of other equipment in the strip dry coal shed is not affected, especially the normal operation of the stacker reclaimer, the temperature change of the strip coal bunker can be monitored autonomously and all-weather. The pan tilt can automatically preset the position for cruise detection, reduce manual intervention, and automatically analyze the temperature rise trend of the whole picture or specific areas, so as to discover the natural hidden danger areas of coal materials in advance.

When the network of the system is interrupted, the front-end monitoring probe can still work normally. If the equipment is abnormal at this time, the monitoring probe can store the alarm information, and automatically send the alarm information back to the console after the network is restored.

The system shall be able to automatically scan the heat distribution status of coal in real time and generate visual images, so as to display the heat distribution image in real time for 365 days and 24 hours, automatically capture the highest temperature point, discover and automatically identify the fire source, accurately locate the ignition point, realize early warning, and help the personnel on duty to quickly extinguish the fire and suppress the occurrence of dangerous situations.

The thermal imaging information is transmitted to the control room in real time and processed by the supporting background system of this system, so as to provide the coal bunker temperature change information to the personnel on duty at any time, so as to facilitate the personnel on duty to deal with it accordingly. The signal transmission from the thermal imager to the control room requires optical cable transmission.

Case analysis

1. Objectives achieved by the system

The system realizes the whole process fire prevention monitoring of the silo, coal storage, transportation and transportation, minimizes the fire hazards, and provides the basis for the calorific value analysis of raw materials.

1) Fire prevention lies in unburned, and the combustion of solid waste and coal is mostly caused by spontaneous combustion. The system can carry out early warning before the coal temperature reaches the ignition point to minimize the loss of spontaneous combustion.

2) Large space non-contact fire prevention: just a few probes can complete the real-time fire prevention monitoring of large space. There is no need to contact the working surface during the monitoring process, which is very convenient for installation and daily maintenance.

）Automatic monitoring and alarm: make the most of the intelligent operation of electrical automation system and computer system, and automatically monitor and alarm without supervision. 365 days * 24 hours real-time display of heat distribution images and videos. Users can conduct real-time temperature analysis of points and areas of interest according to their needs, and automatically capture the highest temperature points.

4) Accurately locate the ignition point. The system can penetrate the thick smoke caused by combustion. Even in the environment without light, it can still accurately locate the ignition point and help the personnel on duty to quickly extinguish the fire.

5) Automatic shutdown and fire linkage: when the temperature is detected to be too high and exceeds the preset threshold, an alarm message is automatically generated to inform relevant personnel to take action in time; If necessary, output signals to the conveyor belt control system and automatic fire spray system, stop the conveyor belt operation and start the automatic sprinkler to extinguish the fire.

6) Alarm log management and viewing: the alarm event system of different levels automatically stores and captures the full radiation thermal image video image at that time for subsequent analysis by customers.

7) Email and SMS alarm: when the alarm is confirmed, the system can send alarm email and SMS to the management personnel so that the alarm can be handled in time.

8) Automatic fault early warning: when the monitoring system itself fails, it will automatically generate error alarm information and automatically notify relevant personnel to eliminate the faults of the monitoring system and prevent the monitoring failure due to the system failure.

2. System advantages

1) Fire alarm and early warning, alarm without delay.

2) The detector and visible light camera (optional) are installed in the same protective cover, monitored from the same angle, displayed on the same screen, and visualized for fire monitoring.

3) The detector has built-in intelligent fire alarm algorithm, combined with multiple alarm methods such as temperature threshold, temperature rise rate and alarm area sensitivity, which can accurately detect fire hazards and make different levels of alarm output even in complex environments, and effectively avoid false alarms.

4) User defined alarm threshold and level: the system can define four different alarm threshold values and levels, and support i/o output for linkage with fire protection, broadcasting and other systems.

5) It can shield and monitor the interference heat sources such as lighting lamps on the site. When the temperature of the interference heat source is abnormal and may become a fire hazard, the system can automatically give an early warning.

6) The system has the function of fault self diagnosis, automatic saving and recovery after power failure.

7) The protective cover can be equipped with dust-proof, heating and cooling devices to adapt to extreme weather conditions and ensure the reliable operation of the system.

8) Automatically record the scene of the first fire (the first fire alarm point), and the system assigns the corresponding infrared thermal imaging probe to record the video for accident investigation.

9) Detect abnormally hot objects invaded by outsiders, and intelligently identify whether they are dangerous sources to avoid false positives.

10) It supports ONVIF protocol and can be directly connected to the standard security platform.

11) Multiple interfaces are flexibly connected to the alarm system and fire extinguishing system, with simple wiring, low construction cost, maintenance free, and low life cycle cost.

3. System architecture

The system is composed of monitoring front end, transmission network and monitoring background (power supply follows the principle of proximity); If necessary, it can be linked with alarm broadcasting, fire protection and other systems. The system is based on TCP/IP protocol and interconnected through Gigabit Ethernet to build a CS architecture system, which is stable and easy to expand.