Infrared thermal imaging technology is a technology that converts invisible infrared radiation energy into visible temperature field images, and uses different colors to represent different temperatures. Since the 1970s, after decades of development, it has rapidly extended from the military field to the civilian field. Due to the rapid development and popularization of this technology, the cost of the instrument has been greatly reduced, and the infrared thermal imager is no longer a "noble" device. Infrared thermal imaging technology has become the most widely used testing technology in addition to the five conventional nondestructive testing of ultrasonic, ray, eddy current, magnetic particle and penetrant testing. Its rapid popularization also benefits from the following characteristics:

• Non contact remote sensing detection does not affect the measured object and is safe to use
• The detection is real-time and convenient, and the measured objects can be scanned and imaged in real time without leakage one by one
• The detection requirements are low, and it can detect objects in the environment of motion, strong magnetism, chemical atmosphere and easy corrosion
• The detection results are objective and intuitive, and the two-dimensional infrared thermal image visually shows the temperature field of each point of the tested object

With the development of society, the requirements for production safety and production process optimization have increased. For important equipment and facilities, fire fighting (FF) management mode is no longer adopted, and preventive maintenance (PM) and preventive predictive maintenance (PPM) are gradually introduced, Predictivemaintenance (PDM) recently, major international companies began to adopt proactive maintenance (PAM). Infrared thermography is one of the most effective tools from FF to PM, ppm, PDM and PAM. In recent years, infrared thermal imaging technology is increasingly used in equipment condition monitoring and fault diagnosis, and has achieved good results. Whether in the United States or China, infrared thermal imagers are used in all walks of life for thermal fault inspection and thermal state measurement, mainly including equipment pre maintenance testing, fault diagnosis, nondestructive testing, energy-saving testing, nuclear power plant safety inspection, building insulation, structural defect detection and leakage moisture detection. The main application fields include pre maintenance and condition monitoring of electric power, metallurgy, petrochemical, construction, boilers and pressure vessels, as well as research and development, quality control and process monitoring, medical treatment, public safety monitoring and military applications. The development of infrared diagnostic technology in China began in the 1980s. The first batch of infrared thermal imagers were used as an important measure of safety production in electric power, petrochemical, metallurgical and other industrial departments, so that it developed rapidly. In the special inspection and petrochemical industry, the national key scientific instrument project "thermoelastic infrared image security detection system" developed by the Institute of metals of the Chinese Academy of Sciences in cooperation with the General Administration of quality supervision, inspection and quarantine and other units has passed the achievement appraisal and the acceptance of the Ministry of science and technology. So far, infrared thermal imaging technology has carried out a large number of tests and achieved fruitful results in many domestic special equipment supervision and inspection units and petrochemical production and testing units.

2.Application in special inspection and chemical industry

Pressure vessels are special pressure equipment with explosion risk. They are responsible for many environmental factors such as high temperature, high pressure, flammable, explosive, highly toxic and strongly corrosive media. Thermoelastic pressure vessels are widely used in all sectors of aerospace and national economy. For the actual stress distribution of pressure vessels under working conditions and the early prediction of potential defects, various conventional methods are powerless, so the safety monitoring and prevention technology of pressure vessels has always been a hot topic in the international research. The thermoelastic effect has been studied tentatively in Britain and the United States, but it is still limited to experimental research. Whether in the special inspection industry or the petrochemical field, temperature control and monitoring can be found everywhere: such as equipment wear, fatigue, crack, fracture, deformation, corrosion, peeling, leakage, blockage, looseness, melting, insulation aging, oil deterioration, adhesion pollution, abnormal vibration, etc. most of these states are directly or indirectly related to temperature changes, many of which cannot be monitored by conventional contact temperature measurement methods, The problem can be solved by using infrared thermal imaging detection technology. The petrochemical industry is an industrial system that carries out extensive work on infrared diagnosis technology. From the 1970s, the Petrochemical Corporation organized the implementation of nondestructive testing to the 1980s, carried out equipment condition monitoring, established a three-level condition monitoring organization based on the head office, the company or the head office and branches, implemented hierarchical management, and first established a first-level organization for rotary machinery diagnosis. Since the 1990s, the development and research of infrared diagnosis technology have been gradually carried out, such as the fault diagnosis of electrical equipment, catalytic cracking unit lining damage and industrial furnaces and kilns; From the initial determination of heat loss in the factory, the scope of its application of infrared detection has been expanding, from infrared detection to infrared diagnosis, from simple diagnosis to precision diagnosis, trend analysis and life prediction. Many units have achieved practical results, among which the more prominent ones are Sichuan general chemical plant, Fushun Petrochemical Company, Changling refinery, Liaoyang Petrochemical Company, Yangzi Petrochemical Company, Daqing Oilfield, Fujian Refining and chemical company, Qilu Petrochemical Company, Tianjin Petrochemical Company, etc. The former Ministry of chemical industry also established an infrared thermal imaging temperature measurement technology center, established a professional group of condition monitoring and fault diagnosis, including infrared thermal imaging technology, formulated the use of infrared thermal imagers to carry out planned and step-by-step regular and fixed-point detection of production equipment, for important and key equipment, set up precision detection points, and establish equipment detection files, so as to make correct judgments and analyze the deterioration trend in case of equipment failure.

3.Application case analysis

In petrochemical special inspection enterprises, usually due to production needs, there are many pipelines, such as steam, hot water and various industrial solutions, which are usually covered with various insulation materials to ensure the requirements of energy conservation. However, because these pipelines are usually erected on the upper part of the plant or outdoors without any maintenance measures, with the passage of time, the insulation layer and even its pipe wall may be damaged or thinned. Through the infrared thermal imager, It is very easy to find hot spots, so as to take measures to reduce energy waste and ensure the correct process temperature. At the same time, the damaged state of the insulation layer can be understood, so as to accurately calculate the required human and material resources, so as to greatly shorten the workload and time of maintenance. A large number of chemical reactions are usually involved in production, especially in various reaction furnaces, which are accompanied by a certain temperature, resulting in varying degrees of corrosion, especially in some valves, plate heat exchangers, end cover linings, etc. in the early stage, simple leakage is often invisible to the naked eye. Through the infrared thermal imager, we can judge through subtle temperature changes, so as to avoid damage to the environment and personnel.

There will also be many kinds of liquid storage equipment in the factory, which will generally control the materials through a liquid level sensor. Sometimes the liquid level sensor will fail, which will often lead to overflow or cut-off, resulting in production interruption and stagnation. This can also be detected by the infrared thermal imager. Because the materials and these storage devices are different materials, their thermal capacity is different. The liquid level can be clearly reflected on the infrared thermal image. Sometimes, this is also a simple method to detect the liquid level, avoiding many potential dangers.

For the leakage of liquefied natural gas, liquefied petroleum gas and liquefied ethylene, it is colorless and tasteless, and it often needs special instruments to detect it. If it cannot be handled in time, fire, explosion and other accidents may occur. However, using gas sensors to detect gas can only detect at fixed points, while thermal imagers can detect a large area, This is to detect the leakage of gas according to the change of ambient temperature generated in the outside world when the gas is discharged. When the liquefied gas flows out, there is an abnormal temperature around. The location and scale of the gas leakage can be determined by observing with a thermal imager.

Petrochemical enterprises have so many equipment, especially most of them are often under the harsh working conditions of high temperature, high pressure, corrosion and oxidation, with the characteristics of long working cycle and short maintenance time. Especially, once they are in operation, they will be uninterrupted for a long time. Usually, they need to grasp the operating status of all these equipment at the same time, so that they can work out a maintenance plan according to the actual situation. Using infrared thermography technology can clearly Visually and comprehensively discover the damage of the tested object, and a relatively obvious temperature abnormal area will often be formed where there is damage.

Through the infrared thermal imager equipment, we can clearly understand the distribution, size and specific situation of hot spots, and even understand the cause and severity of the problem according to the past status files of these equipment, and take timely actions to maximize the service life of the equipment. This is a dynamic maintenance process, which can formulate the most economical maintenance schedule according to the different use conditions of the equipment. On the other hand, the infrared thermal image can comprehensively reflect the temperature distribution of the tested area, find out the weak links of insulation, and comprehensively and quantitatively evaluate the insulation performance of the tested object. The insulation of all parts of the pipeline can be visually displayed through the infrared thermal image.

Applicable Machine

1. Detection of coke deposition at the bottom of Cracking Fractionator: coke deposition at the bottom of Cracking Fractionator is the key to the long-term operation of Eureka unit. When the thermal imager is used to measure the coke deposition at the bottom of the tower, the thermal image characteristics of the outer wall can determine the degree of coke deposition in each part of the tower, and guide the process adjustment and determine the best operation scheme according to the results. The practice shows that after the combination of the detection method and the process, the operation cycle of cracking and fractionation is extended from the original average of 30 days to 268 days, and obvious economic benefits are obtained.

2. Evaluate the lining damage of acetaldehyde acetate device: in petrochemical equipment, there are multiple lining materials inside the key equipment of acetaldehyde acetate device (catalytic regenerator, reactor, demister, etc.). Using the thermal imager to detect the temperature field of its outer wall, and then combined with the heat transfer theory to calculate the thickness of its internal insulation layer, we can understand the lining damage degree under the operation of the device, so as to provide a reference for formulating the maintenance plan.

3. Detect the local "hot spot" of the cracking furnace tube: the cracking furnace is the heart of ethylene production, and the coking in the furnace tube will seriously affect its service life. The infrared thermal imager can be used to test the furnace tube in the furnace through the peephole, and the thermal image characteristics of the hot spot can be obtained, which is the implementation method of maintaining the furnace tube.

4. Detection of catalytic cracking unit: catalytic cracking unit is an important unit in kerosene plant. The lining condition of its core devices (catalytic regenerator and settler) in production and operation is directly related to the safety of the cylinder wall, so it needs to be detected and diagnosed at any time. Carry out regular wall temperature detection on them with a thermal imager, analyze the lining condition, possible fault location, degree and development trend, and provide basis for maintenance.

5. Measurement of the outer wall temperature of the thermal pipeline: the steam thermal pipeline is crisscrossed and widely distributed in the refinery. The insulation material of the outer wall of the pipeline will be gradually damaged and dropped during the production process, and the outer wall temperature of the pipeline will rise at any time, causing a lot of heat loss. Use the thermal imager to scan and measure the temperature of the outer wall of the thermal pipeline. According to the measured data, calculate the heat loss of the outer wall of the thermal pipeline and take measures.

In a word, the real-time monitoring and early fault diagnosis of the operation status of production equipment in the petroleum and petrochemical industry by using infrared thermal imager is one of the main means to ensure safe production. The online infrared thermal imaging thermometer is used to monitor the above parts in real time, and the image temperature data is uploaded to the command center in real time through the transmission network for analysis and early warning on the background monitoring software.

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 UDP protocol and interconnected through Gigabit Ethernet to build a CS architecture system, which is stable and easy to expand.

System diagram

Monitoring front end

1. Use 640 × 480 high pixel infrared camera, with a customized 5mm-35mm special temperature measuring lens, the maximum field angle can reach 95 ° × 78 °, the farthest monitoring distance can reach 30m;
2. Accurate temperature measurement algorithm, temperature measurement accuracy ± 2 ℃ or ± 2%, full screen temperature measurement, high consistency;
3. The air-cooled explosion-proof cover enables the equipment to work normally at a high temperature of 80 ℃;
4. Multi screen analysis software, multiple pictures are displayed at the same time, temperature measurement analysis and temperature warning are carried out at the same time;
5. Gigabit network interface standard, 50Hz high frame rate, real-time detection of each high-temperature abnormal point, eliminate hidden dangers.

Background monitoring interface

Equipped with multi split screen monitoring software, it can monitor and display the maximum temperature and minimum temperature of each part in real time, set the alarm threshold and store the temperature data.

System description of thermal imaging fire alarm monitoring system

（1）Accurate temperature monitoring

The core of this system is to monitor the temperature of the transmission pipeline. How to obtain the accurate temperature has become the core. In the field of infrared thermography, there are many factors that affect the accurate temperature measurement. For the application object of this system, a unique processing technology is adopted to compensate the influence of different media on the received infrared radiation, so as to accurately measure the temperature and prevent false alarm.

(2) 24x7 real-time monitoring

Advanced equipment is used to collect the temperature on the synchronous surface, with clear imaging and 24-hour real-time monitoring. Adopt protective cover according to the environment to prevent corrosion and dust, and effectively protect the normal operation of the equipment itself.

(3) Intelligent alarm for blast furnace
The thermal imaging front-end temperature measurement unit is set according to the area of the furnace body and installed on the upper Packway enclosure of the warehouse. The thermal imagers are evenly distributed at a certain angle to eliminate the blind area of thermal imaging monitoring. When the temperature of furnace skin rises, panoramic monitoring and active alarm can be carried out.

（4）Intelligent analysis method
Based on the intelligent analysis method of temperature threshold and thermal image characteristics, the monitoring system can find hot spots and capture them in time.
       (5) Professional analysis software

This system is equipped with professional analysis software with powerful functions. It can analyze images in the form of points, lines, surfaces and various areas to find problem points. Temperature data can be stored for later analysis.

Applicable Machine