Objective of the internship: building environment and equipment engineering production internship, is an important practical teaching links, through the production internship can make students engaged in the field of professional and business, the professional engineering to establish a certain understanding of the situation, so that students are clear about the scope of their own profession, to understand the profession of some of the basic design, construction, maintenance and management, debugging and other aspects of the knowledge. For future professional learning to lay the necessary foundation. Second, the content of the internship: 1, part of the gas source familiar with the structure of the natural gas boiler, the principle of operation, the main parameters; familiar with the natural gas boiler process and equipment, station processes and equipment; natural gas boiler consists of three parts: combustion equipment, heat transfer equipment, automatic control and safety protection devices. Combustion equipment mainly consists of gas burners, ignition devices, combustion chambers, air supply and exhaust systems. At present, there are two kinds of internal heat exchanging equipment in the domestic boiler, one is the use of casing heat exchanger, that is, domestic hot water in the heating heat exchanger, directly heated by the fire; another structural form of domestic hot water is indirectly heated, i.e., through the plate heat exchanger to the heat exchanger. Automatic control and safety protection devices are mainly wind pressure switch, flow switch, flame failure protection, water shortage protection, overheating protection, temperature sensors and controllers and other components. Gas wall-hung boiler work can be simply seen by two processes: one is the combustion process, that is, the fuel and air mixed with the fire combustion process to release the heat of the chemical reaction; the other is the process of heat transfer, that is, the fuel combustion process to release the heat of the chemical reaction through the heated surface to the process of water transfer. When the gas supply valve is open, press the start button, gas wall-hung boilers will automatically complete the entire combustion and heat transfer process. First of all, the fan is started, the wind pressure switch works, the air into the 20 seconds before the blowing, and then the gas solenoid valve opens, the gas into the gas burner, at the same time the ignition transformer began to work, the 220V voltage into 6000V or more high voltage, the two ignition electrodes with each other to discharge (if an electrode is discharged to the ground) the formation of the gas to ignite the arc, the flame failure protection device to carry out the protective work to monitor the flame condition. The flame condition in the combustion chamber is monitored by the flame failure protection device. Gas combustion in the combustion chamber, the heat exchanger in the pot of water heating, pot of water temperature rises for heating or domestic hot water heating, water combustion of gas formed by the chemical reaction of the heat is effectively absorbed to complete the heat transfer process. 2, transmission and distribution of part of the city familiar with the pipeline network layout characteristics, the pressure level system and a variety of structures (gate station or storage and distribution station, regional regulator station) of the process, the principle of operation and the station's main equipment. . Familiar with the layout of the liquefied petroleum gas storage and distribution station, process flow and operating principles.
Natural gas transmission and distribution system includes one or more pressure levels of the pipeline network and the corresponding facilities, its task is to supply gas from the source of gas supply, such as the city gate station, gas storage facilities or gas production plant, economic, safe and reliable to the user gas supply. With the development and change of the city gas source in various countries, the different characteristics of urban planning, gas supply scale size and scientific and technological progress, the gas transmission and distribution system also has an evolutionary process. In the era of artificial gas, the gas supply scale is small, and the private users dominate, so the gas supply pressure is low, and the composition of the transmission and distribution system is also relatively simple. Since natural gas has become the main source of gas in cities, due to the fundamental changes in the user structure, the city gas transmission and distribution system has also undergone fundamental changes. The modern city gas distribution system is a complex integrated facility, usually consisting of gas pipeline networks with different pressure levels such as low pressure, medium pressure and high pressure, city gas distribution stations or pressure stations, pressure regulating and metering stations or regional pressure regulating stations, reserve stations, monitoring and scheduling centers, and maintenance and management centers. It is closely related to people's life and social production, and plays a great role. As a student of urban construction, you should be proud of the great value you can create in the future. The composition of the following gas transmission and distribution system can be seen in Figure 1-1. For the door station mentioned by Mr. Li, many students did not understand at that time, and now I briefly introduce. City gas gate station is usually called "regulator and metering station". Is a long-distance gas pipeline and city gas transmission and distribution system at the intersection of gas pressure measurement facilities, referred to as the city gate station. The gas from the long-distance pipeline is first filtered to remove mechanical impurities, and then passes through the regulator (see gas regulator) and the flow meter (see gas metering) into the city gas distribution system. If the gas needs to be odorized (so that the gas appliance has a distinct odor so that leaks can be easily detected), then the regulator, meter, and then the gas meter must pass through the odorizing device. Safety devices are automatically activated when the pressure of the gas entering or leaving the station exceeds the specified pressure. In case of station failure, the gas can be supplied through a bypass pipe. Long-distance pipelines If a pipe cleaner is used, the receiver of the pipe cleaner can be located in the gas gate station to facilitate centralized management. (See Figure) for the city network pressure level system from the master Guo's explanation and their own understanding of the situation, the pressure level system is mainly to determine the high-pressure gas transmission and medium-pressure gas distribution pressure. Reasonable pressure level system can not only ensure the needs of urban gas supply, but also can reduce the pipeline network and gas storage equipment investment. In general, the pressure of gas pipeline in medium-sized cities is 1.6Mpa, and the working pressure of medium-pressure pipeline network is generally stipulated at 0.4Mpa. After analyzing the composition of natural gas and considering the safety aspect, we know that the main component of natural gas is made up of more than 95% of methane, and some other hydrocarbons such as sulfur compounds and other hydrocarbons. Natural gas itself is not toxic. But it will burn, because natural gas itself is colorless, tasteless, flammable and explosive, in the use of the process, once the leak is difficult to be found, and add gas leakage warning odorant, even if there is a small amount of leakage, can be found in time. Therefore, in order to improve the safety of the use of civil natural gas, transmission and distribution companies in the gas distribution device are added to the odorant device, so that once the gas leakage occurs, it is easy for users to find in time to avoid major accidents. 3, combustion and application of part of the
Gas as a fuel, with easy to use, strong fire, high thermal efficiency, little pollution to the environment, easy to realize the production of automation and improve product quality, etc., but also has the advantages of easy to use, strong fire, high thermal efficiency, easy to achieve production automation and improve product quality. Advantages, but also flammable and explosive and toxic characteristics. In fact, over the years due to a variety of reasons, such as improper design, poor construction, production or use of the process of violation of operating procedures, leakage failure to timely and correctly deal with and so on and caused by explosions, combustion, poisoning has been commonplace to the country and the parties involved in unnecessary losses, so the application of gas must be used in the application of the necessary safety measures. 1, in order to prevent leakage of gas must be guaranteed as follows Conditions 1-1 pipe, valves using high-quality qualified materials, and should be installed before the use of technical inspection. 1-2 to strict construction, to ensure the quality of construction, especially in the welding, sealing of connectors and insulation and other aspects of the quality to be ensured. 1-3 of gas piping, pipe fittings and equipment components should be In accordance with safety and technical regulations for strength and tightness test, found that the problem should be dealt with in a timely manner. 1-4 in the production operation should be the use of scientific instruments, often check, especially in the basement piping, piping connections, valves, collector and other key parts of the leakage phenomenon, has been found that should be repaired quickly to eliminate the leakage of hidden dangers. 1-5 design and installation of gas equipment should comply with the safety and security requirements. When designing and installing gas equipments, safety regulations should be observed, and it is better to install gas leakage meter. Laying pipes as far as possible to arrange on the ground, which is conducive to the inspection, maintenance (
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