The main reason for the generation of BOG (boil-off gas) is the introduction of external heat, causing low-temperature liquids (such as LNG, LPG, etc.) to evaporate. In addition, pressure changes during storage and transportation, improper operation and other factors can also promote the generation of BOG. In order to reduce the generation of BOG, you can start from the following aspects:
Optimize storage devices
Improve thermal insulation performance
Choose high-quality insulation materials: In the construction of LNG storage tanks, high-efficiency insulation materials such as polyurethane foam and perlite are selected. These materials have low thermal conductivity, which can effectively prevent external heat from entering the tank, reduce the evaporation of LNG, and thereby reduce the production of BOG.
Increase the thickness of the insulation layer: Appropriately increasing the thickness of the insulation layer of the storage tank can further improve the insulation effect. For example, for large LNG storage tanks, increasing the thickness of the insulation layer from the conventional 200 mm to 250 mm can significantly reduce the heat transferred into the tank, thereby reducing the BOG generation rate.
Improve the sealing structure
Use high-performance sealing materials: Use high-performance sealing materials such as fluorine rubber and silicone rubber in the inlet and outlet pipes, valves, and manholes of the storage tank. These materials have good low-temperature resistance and aging resistance, can maintain a reliable sealing effect during long-term use, prevent leakage of low-temperature liquids and outside air from entering the tank, thereby reducing the generation of BOG.
Regular inspection and maintenance of the sealing structure: Establish a complete sealing structure inspection and maintenance system, and regularly inspect the sealing parts of the storage tank. For example, visual inspections of valve seals are performed monthly, and leak detection of the sealing conditions of pipe connections is performed quarterly. Once problems such as aging, damage or loose sealing of seals are discovered, they should be replaced or repaired in time to ensure that the sealing structure is always in good working condition and effectively reduce the generation of BOG.
Improve transportation links
Strengthen the insulation of transportation equipment
Upgrade the insulation of LNG carriers: Add a layer of high-performance insulation material, such as airgel felt, to the outside of the cargo tank of the LNG carrier. Airgel felt has extremely low thermal conductivity and good flexibility, and can effectively wrap the cargo tank and reduce the introduction of external heat. At the same time, the support structure and pipe connection parts of the cargo tank are optimized and materials with good thermal insulation properties are used to reduce the heat transfer path and further reduce the generation of BOG.
Improve the insulation performance of LNG tank trucks: For LNG tank trucks, use better quality and thicker insulation materials, such as polyurethane sandwich panels, to fully wrap the tank body of the tank truck. At the same time, the sealing treatment of the tank truck body is strengthened, and advanced sealing technology and materials are used to ensure that the tank is in a good sealing state during transportation, prevent outside air from entering the inside of the tank, and reduce the risks caused by the contact between air and low-temperature LNG. evaporation, thereby reducing the production of BOG.
Optimize transportation operation process
Reasonably arrange transportation plans: Reasonably arrange transportation plans based on LNG demand and transportation distance. Try to transport during periods when the temperature is lower, such as at night or early in the morning, to reduce the impact of external environmental heat on the LNG in the transportation equipment and reduce the generation rate of BOG. At the same time, the transportation route should be optimized to avoid long waiting or congestion during transportation, reduce the residence time of LNG in the transportation equipment, and thereby reduce the amount of BOG produced.
Standardize loading and unloading operations: Develop strict operating procedures for LNG loading and unloading, requiring operators to strictly follow the specifications during the loading and unloading process. Before loading and unloading, conduct a comprehensive inspection of the transportation equipment and loading and unloading facilities to ensure that the equipment is in good operating condition and the sealing performance is reliable. During the loading and unloading process, the loading and unloading speed should be controlled to avoid violent shaking of LNG in the transportation equipment due to too fast loading and unloading speed, which will increase the exchange of heat between LNG and the outside world, thereby promoting the generation of BOG. At the same time, we will strengthen the management of the loading and unloading site to ensure that there is no leakage during the loading and unloading process and reduce the generation of BOG caused by LNG leakage.
Precisely control storage conditions
Stable storage pressure
Install a pressure control system: Install an advanced pressure control system on the LNG storage tank, which consists of pressure sensors, controllers and regulating valves. The pressure sensor monitors the pressure changes in the tank in real time and transmits the pressure signal to the controller. The controller analyzes and processes the pressure signal according to the preset pressure range, and then issues control instructions to adjust the opening of the inlet and outlet valves of the storage tank, thereby achieving precise control of the pressure in the storage tank. For example, when the pressure in the storage tank rises close to the preset upper limit, the controller issues instructions to gradually open the gas phase outlet valve of the storage tank to discharge excess gas in the storage tank, reducing the pressure in the storage tank to Within normal range. In this way, the pressure in the storage tank is effectively stabilized, reducing LNG evaporation caused by pressure fluctuations, thereby reducing the generation of BOG.
Regular maintenance of pressure control equipment: Establish a complete maintenance system for pressure control equipment, and regularly inspect, calibrate and maintain pressure sensors, controllers, regulating valves and other equipment. For example, the pressure sensor is calibrated every quarter to ensure that its measurement accuracy is accurate and reliable; the controller is comprehensively inspected once a year to clean the internal dust and check the working status of the electronic components to ensure the normal operation of the controller; the regulating valve is inspected every month A visual inspection to check the sealing performance and movement flexibility of the valve. If there are any problems, repair or replace them in time. Regular maintenance of pressure control equipment ensures the stable and reliable operation of the pressure control system, thereby effectively stabilizing the pressure in the storage tank and reducing the generation of BOG.
Control storage temperature
Adopt a temperature adjustment system: Set up a temperature adjustment system in the LNG storage tank, which is mainly composed of refrigeration equipment, heating equipment, temperature sensors and control systems. The temperature sensor monitors the temperature changes of the LNG in the storage tank in real time and transmits the temperature signal to the control system. The control system analyzes and processes the temperature signal according to the preset temperature range, and then issues control instructions to start the refrigeration equipment or heating equipment to adjust the temperature of the LNG in the storage tank. For example, when the temperature of LNG in the storage tank rises close to the preset upper limit, the control system issues an instruction to start the refrigeration equipment, and removes the excess heat in the storage tank through the refrigeration cycle, reducing the temperature of the LNG to normal. Within the range; when the temperature of the LNG in the storage tank drops close to the preset lower limit, the control system issues an instruction to start the heating equipment to heat the LNG in the tank so that the temperature rises to within the normal range. By adopting a temperature adjustment system, the temperature of LNG in the storage tank is effectively controlled, reducing LNG evaporation caused by temperature fluctuations, thereby reducing the generation of BOG.
Utilize cold energy recovery system: Set up a cold energy recovery system in LNG receiving stations or related enterprises. This system can recycle and utilize the cold energy released during the storage and gasification process of LNG, thereby indirectly controlling the storage temperature of LNG and reducing BOG. of production. The working principle of the cold energy recovery system mainly includes the following aspects: First, the low-temperature LNG in the LNG storage tank is transported to cold energy utilization equipment through pipelines, such as low-temperature cold storage, air separation equipment, etc. In these devices, low-temperature LNG exchanges heat with the material that needs to be cooled, transferring its own cold energy to the other party, lowering the other party's temperature, thereby realizing the utilization of cold energy. For example, in a low-temperature cold storage, low-temperature LNG exchanges heat with the air in the cold storage through the evaporator, so that the temperature of the air in the cold storage is lowered, thereby achieving the purpose of refrigerated goods. Secondly, the temperature of the LNG after heat exchange increases and becomes a gaseous state or a gas-liquid mixed state, and then it is transported back to the LNG storage tank or gasification device through pipelines for subsequent processing. Finally, the cold energy recovery system is also equipped with corresponding control systems and monitoring equipment to monitor the operating status of the system in real time, such as temperature, pressure, flow and other parameters, and automatically adjust and control the system based on the monitoring results to ensure that the system Stable and reliable operation to achieve efficient recycling of cold energy. By using the cold energy recovery system, it can not only effectively recover the cold energy released by LNG, realize cascade utilization of energy, and improve energy utilization efficiency, but also indirectly control the storage temperature of LNG, reducing LNG evaporation caused by temperature rise, thereby reducing The amount of BOG produced has significant economic and environmental benefits.
Strengthen personnel training and management
Improve operator skills
Carry out professional skills training: Enterprises should regularly organize professional skills training for operators involved in BOG processing. The training content covers the basic principles of cryogenic liquid storage and transportation, the causes and mechanisms of BOG generation, the operation methods and maintenance points of various storage and transportation equipment, the process flow and operation control of BOG treatment systems, etc. For example, industry experts are invited to give lectures to explain in detail the physical and chemical properties of LNG, the structure and working principles of LNG storage tanks, operating specifications of BOG compressors and common troubleshooting methods. At the same time, through on-site practical demonstrations, operators can personally experience the operation process of the equipment, become familiar with the functions of various parts of the equipment and operating buttons, and master the correct operating methods and techniques. In addition, simulation drills can also be organized to set up various working conditions and fault scenarios, allowing operators to conduct emergency handling and troubleshooting drills in a simulated environment, thereby improving operators' ability to respond to emergencies and solve problems in actual work. ability.
Encourage operators to participate in skills competitions: Enterprises should actively encourage operators to participate in various industry skills competitions. The skills competition is not only a platform for testing and displaying the skill level of operators, but also provides operators with opportunities to communicate and learn from other outstanding players in the same industry, broaden operators' horizons, and understand the latest technological development trends and trends in the industry. operating methods, thereby promoting the improvement of the operator's own skill level. For example, companies can organize internal selection activities to select operators with higher skill levels to represent the company in industry skills competitions. Before the competition, provide professional training and guidance to the contestants to help them become familiar with the competition rules and procedures, conduct targeted training and simulation drills for the competition items, and improve the contestants' competition level and coping ability. At the same time, contestants are encouraged to actively communicate and learn from other contestants during the competition, learn from others' strengths and experiences, and continuously improve their own operating methods and skill levels. After the competition, organize contestants to conduct experience sharing and summary activities, and share the gains and experiences during the competition with other operators, so that more operators can benefit from it and jointly improve the overall operator skill level of the enterprise.
Improve personnel management system
Establish strict operating specifications and processes: Enterprises should develop a set of strict, detailed and operable operating specifications and processes involving BOG treatment-related equipment based on relevant national standards and industry specifications, combined with their own actual production conditions. Operating specifications and procedures should cover all aspects of equipment such as daily inspection, start-up, operation, stop, maintenance and emergency response, and clarify the specific operating steps, operating methods, operating requirements and precautions for each link. For example, the operating specifications and procedures for LNG storage tanks should be stipulated in detail. During the daily inspection of the storage tank, it is necessary to check whether the appearance of the storage tank is deformed, corroded, cracked, etc., and to check whether the inlet and outlet pipes and valves of the storage tank are in good condition. In normal working condition, whether there is any leakage, check whether the safety accessories of the storage tank, such as safety valves, pressure gauges, liquid level gauges, etc. are accurate and reliable, and whether they are within the validity period; during the startup process of the storage tank, it should be clearly stipulated that the safety accessories need to be followed Open the inlet and outlet valves of the storage tank in a certain sequence and slowly introduce LNG liquid. At the same time, pay close attention to changes in the pressure, liquid level, temperature and other parameters of the storage tank to ensure the safe and stable operation of the storage tank during the startup process; During the operation of the storage tank, it should be stipulated that the operator needs to regularly record and analyze various parameters of the storage tank, such as recording the pressure, liquid level, temperature and other parameters of the storage tank once an hour, and analyzing the recorded data every day to judge whether Whether the storage tank is in normal operation, if there is any abnormal situation, corresponding measures should be taken promptly to deal with it, etc.; during the stop process of the storage tank, it should be clearly stipulated that the inlet and outlet valves of the storage tank need to be closed in a certain order, and the storage tank should be Empty the LNG liquid in the tank, purge and replace the tank at the same time to ensure that there is no residual LNG liquid and gas in the tank, then close all valves and power supply of the tank, and make a stop record of the tank, etc. ; During the maintenance process of storage tanks, it should be stipulated that the storage tanks need to be comprehensively inspected and maintained regularly. For example, a comprehensive visual inspection and non-destructive inspection of the storage tanks should be carried out every year to check whether the main structure of the storage tank is damaged or deformed. According to the situation, the inlet and outlet pipes and valves of the storage tank should be disassembled, cleaned, inspected and repaired, and the safety accessories of the storage tank should be verified, repaired or replaced; during the emergency treatment of the storage tank, a detailed emergency plan should be formulated , clearly stipulates the emergency measures that operators need to take immediately in the event of LNG leakage, fire, explosion and other emergencies, such as immediately stopping the operation of relevant equipment, closing the inlet and outlet valves of storage tanks, and starting emergency rescue equipment, such as fire pumps, Foam generators, fire extinguishers, etc. are used for fire extinguishing and rescue and rescue work. At the same time, accidents are reported to superior leaders and relevant departments in a timely manner, and personnel are organized for evacuation and evacuation. By establishing strict operating specifications and procedures, clear operating guidelines and standards are provided for operators to ensure that operators can strictly follow the operating specifications and procedures during operations involving BOG treatment-related equipment to avoid improper operation. This can lead to safety accidents such as equipment damage and BOG leakage, thereby ensuring the safe and stable operation of the enterprise's production process.
Implement performance appraisal and reward and punishment mechanism: Enterprises should establish a complete performance appraisal and reward and punishment mechanism for operators involved in BOG processing. The performance appraisal mechanism should formulate a scientific, reasonable, comprehensive, objective and operational performance appraisal indicator system based on the job responsibilities and tasks of the operators. The performance appraisal indicator system should cover multiple aspects such as work performance, work attitude, work ability, etc. Among them, work performance indicators mainly include the task completion, work quality, work efficiency, cost control and other contents of operators in work related to BOG processing. For example, assess whether the operator completes the daily inspection tasks of the BOG processing system in accordance with the prescribed time and quality requirements, whether the faults that occur during the operation of the equipment are discovered and handled in a timely manner, and whether the generation and emission of BOG are effectively controlled to reduce production costs. Work attitude indicators mainly include the operator's work responsibility, professionalism, teamwork spirit, work enthusiasm, initiative and other contents. For example, assess whether the operator is Whether they are serious and responsible, whether they strictly abide by work discipline and operating procedures, whether they actively participate in teamwork, whether they have good professionalism and work enthusiasm, etc.; work ability indicators mainly include the operator's professional knowledge level, skill operation ability, problem-solving ability, learning ability, communication and coordination ability, etc. For example, whether the operator has solid professional knowledge related to BOG treatment, whether he is proficient in the operation skills and maintenance methods of various equipment, whether he can solve various problems in the work process in a timely and effective manner, whether he has strong learning ability and communication and coordination ability, can continuously learn new knowledge and new skills, and communicate and collaborate well with colleagues and superiors. By establishing a scientific and reasonable performance appraisal indicator system, the work performance of operators is comprehensively, objectively and fairly evaluated, which provides an accurate basis for the implementation of the reward and punishment mechanism. The reward and punishment mechanism should give corresponding rewards to operators with excellent performance and impose corresponding penalties on operators with poor performance based on the performance appraisal results. Reward measures can include material rewards, such as bonuses, prizes, promotion wages, etc., as well as spiritual rewards, such as honorary certificates, commendation conferences, public praise, etc. For example, for operators who have outstanding work performance, a serious and responsible work attitude, and strong work ability in the performance appraisal, the company can give a certain amount of bonus as a material reward, issue a certificate of honor, and publicly praise them at the company's internal commendation conference as a spiritual reward to encourage operators to continue to maintain excellent work performance, and also set an example for other operators to promote the improvement of the company's overall work level. Punishment measures may include criticism and education, warnings, fines, demotions, dismissals, etc. For example, for operators who have poor work performance, a careless work attitude, insufficient work ability, and no obvious improvement after training and guidance in the performance appraisal, the company can first criticize and educate them and warn them, urging them to recognize their own problems and improve them; if the operator still does not correct himself after being criticized and warned, the company can impose fines, demotions, and other punishment measures on him according to his specific circumstances; if the operator's behavior seriously violates the company's rules and regulations or causes significant losses to the company, the company can dismiss him according to law. By implementing the performance appraisal and reward and punishment mechanism, the enthusiasm and initiative of operators are stimulated, their sense of responsibility and professionalism are improved, and operators are encouraged to continuously improve their professional knowledge and skills, thereby effectively improving the quality and efficiency of work related to BOG processing and ensuring the safe and stable operation of the company's production process.
