Practice report of boiler room Practice report Practice purpose: to form a preliminary understanding and general understanding of future study and work, and lay a preliminary foundation for future systematic theoretical study. Internship task: understand the principle, composition and function of each equipment of the heat collection system; Understand the principle, composition and function of various air conditioning systems; Understand the structure and principle of fuel medium, fuel and gas boilers; Understand the principle, composition and function of refrigeration system; Understand the structure and principle of piston compressor, centrifugal compressor and screw compressor; Understand the refrigeration principle and system composition; Understand the composition and working principle of cold storage; Understand the structure and working principle of cooling tower. Visiting places can be divided into the following six aspects: air conditioning system, ventilation system, boiler room system, refrigeration system, heating part and gas part. According to these six aspects, the teacher took us to visit Yunfeng Pharmaceutical Factory, Dongshan Storage and Distribution Station, Zhangjiakou Hercules Boiler Manufacturing Co., Ltd., Shenghua Thermal Power Plant, Xinhua Building, Zhangjiakou Food Company, the First Affiliated Hospital of Hebei North University and Jin Feng Building. Definition of boiler room system: equipment that uses heat energy or other heat energy released by fuel combustion to heat water or other working fluids to generate steam, hot water or other working fluids with specified parameters and quality. Boiler is a kind of energy conversion equipment. The energy input to the boiler is chemical energy, electric energy and heat energy of high temperature flue gas. After the boiler is converted, steam, high-temperature water or organic heat carrier with certain heat energy is output. The furnace, drum, burner, water wall superheater, economizer, air preheater, frame and furnace wall in the boiler constitute the core part of steam production, which is called boiler body. Boiler body: The boiler body consists of two parts: a pot and a furnace. "Boiler" refers to various components that bear internal or external pressure and form a closed system, including boiler shell, drum, water wall, slag cooling pipe, boiler tube bundle, steam superheater, economizer, header, downcomer, steam-water separation device, blowdown device, air temperature regulating device, etc. "Furnace" refers to various components that constitute a fuel burning place, including combustion equipment consisting of a furnace, a coal hopper in front of the furnace, a coal valve, a grate, a slag discharge plate and an air distribution and supply device. The two most important parts in the boiler body are the furnace and the drum. Internal structure diagram of steam boiler Rice husk burning furnace is also called combustion chamber, which is the space for fuel combustion. The hearth where solid fuel is put on the grate to burn the fire bed is called layer burning furnace, also called fire bed furnace; A furnace that injects liquid, gas or powdery solid fuel into a fire chamber for combustion is called a chamber furnace, also known as a chamber furnace; Air lifts coal particles and makes them burn in boiling state. The furnace suitable for burning inferior fuel is called boiling furnace, also known as fluidized bed furnace. A cylindrical furnace that uses airflow to make coal particles rotate at high speed and burn strongly is called a cyclone furnace. In the understanding of the boiler, I mainly visited Zhangjiakou Hercules Boiler Co., Ltd. and Dongyuan Thermal Power, and learned the structure and usage of the boiler in practice. Operation process and principle of boiler: In the aspect of water vapor system, feed water is heated to a certain temperature in the heater, then enters the economizer through the feed water pipeline, is further heated and sent to the boiler drum, and then descends to the inlet header of the water wall along the downcomer after being mixed with boiler water. Water absorbs the radiant heat of the furnace in the water wall tube, forming a steam-water mixture, which reaches the boiler drum through the riser tube, and the steam-water separation device separates the water from the steam. The separated saturated steam flows from the upper part of the drum to the superheater, continues to absorb heat, becomes superheated steam at 450℃, and then is sent to the turbine. In the combustion and flue gas system, the blower sends air into the air preheater to heat it to a certain temperature. A certain fineness of pulverized coal in the coal mill is carried by a part of hot air from the air preheater and injected into the furnace through the burner. The mixture of pulverized coal and air sprayed by the burner is mixed with the remaining hot air in the furnace to burn, releasing a lot of heat. The hot flue gas after combustion flows through the furnace, slag tube bundle, superheater, economizer and air preheater in turn, and then passes through the dust removal device to remove fly ash, and finally is sent to the chimney by the induced draft fan and discharged into the atmosphere. The following figure shows the overall operation flow chart of Dongyuan Thermal Power Plant: Working principle of refrigeration system: The air conditioning refrigeration system consists of four main components: evaporator, compressor, condenser and capillary. According to the working sequence of refrigeration cycle, they are connected into a whole by pipes in turn. When the system works, the refrigerant in the evaporator absorbs the heat of indoor air and evaporates into low-pressure and low-temperature steam. After the refrigerant is sucked and compressed by the compressor, the pressure and temperature rise, and then it is discharged into the condenser. By releasing heat to outdoor air in the condenser, refrigerant vapor is condensed into liquid with higher pressure. The refrigerant liquid is throttled by capillary tube, the pressure and temperature are reduced, and then it enters the evaporator to evaporate, so it works circularly, thus reducing the indoor temperature. The refrigeration system consists of compressor, condenser, expansion valve (throttle valve) and evaporator, which are connected in turn through pipes to form a closed system. In order to ensure the normal operation of the system, some auxiliary equipment is needed, including oil separator, accumulator, non-condensable gas separator, filter and automatic controller. In Zhangjiakou Food Company, we visited the refrigeration technology and the company's refrigeration equipment. Refrigeration equipment Different refrigeration methods use different equipment. At present, the most widely used is vapor compression refrigeration, and the main equipment includes compressor (see fluid conveying machinery), condenser, evaporator and throttle valve. Compressors are used to compress and transport refrigerant vapor, among which piston and centrifugal are the most widely used. Articles will release a certain amount of heat when they are cooled or frozen, and the enclosure structure of refrigeration device will also introduce a certain amount of heat when it is used. Therefore, in order to maintain the low temperature condition in the refrigeration device, it is necessary to install a refrigerator to continuously remove this heat, or to absorb this heat through sublimation of melted ice or dry ice. The industrial flow chart of Zhangjiakou Food Company is as follows: compressor exhaust-oil ammonia separator-condenser-high pressure storage tank-expansion valve-low pressure circulating storage tank. Direct cooling is to install the evaporator of the refrigerator in the box or building of the refrigeration device, use the evaporation of refrigerant to directly cool the air in it, and use cold air to cool the objects that need to be cooled. This cooling method has the advantages of fast cooling speed, small heat transfer temperature difference and simple system, so it is widely used. The condenser is used to condense the high-pressure and high-temperature refrigerant vapor sent by the compressor into liquid. There are three kinds of commonly used condensers: water-cooled condensers. With water as coolant, there are tube condenser, sleeve condenser and spiral plate condenser. Spray type. At the same time, water and air are used as coolants, including spray condenser (air is natural convection) and evaporative condenser (air is forced convection). Air cooled type. Air is used as refrigerant, that is, air-cooled refrigeration equipment: evaporator, also known as heat absorber, is a heat transfer equipment that cools refrigerant or cooled object by boiling and vaporizing liquid refrigerant. Evaporators are divided into two types: one is liquid-cooled type, which is used to cool liquid coolant, and there are shell-and-tube evaporators and various submerged evaporators (such as vertical tubes, spiral tubes and snake tubes). Immersed evaporator is to immerse the whole heat exchange surface in a tank filled with cooling liquid and stir it in the tank to strengthen heat exchange. The other is the cooling air type, which is used to cool the air as a coolant, and is divided into two types: tube row type and air cooler type. The tube bundle consists of vertical tubes, horizontal tubes or coils. The refrigerant boils in the tube, and the air outside the tube naturally convects. The air cooler is composed of tube bundle and fan, which makes the air outside the tube produce forced convection. According to the working principle, refrigerators can be divided into compression refrigerators. Depending on the compressor, the pressure of the refrigerant can be increased to realize the refrigeration cycle. According to the types of refrigerants, it can be divided into vapor compression refrigerator (based on hydraulic evaporation refrigeration, the refrigerant will undergo periodic gas-liquid phase change) and gas compression refrigerator (based on high-pressure gas expansion refrigeration, the refrigerant is always in a gas state). Absorption refrigerator. The refrigeration cycle is completed by the absorber-generator group (thermochemical compressor), which is divided into three types: ammonia absorption, lithium bromide absorption and absorption diffusion. Steam jet refrigerator. The refrigeration cycle is completed by the action of steam ejector (jet compressor). Semiconductor refrigerator. Using thermoelectric effect of semiconductor to produce cold energy. Ventilation system ventilation, also known as ventilation, is to send enough fresh air into the indoor space by mechanical or natural methods, and at the same time discharge the dirty air that does not meet the sanitary requirements, so that the indoor air can meet the sanitary requirements and the needs of production technology. The facilities that complete the ventilation work in the building are collectively called ventilation equipment. Ventilation can be divided into whole ventilation and local ventilation according to the scope. Total ventilation, also known as dilution ventilation, is to ventilate the whole space. Local ventilation is to directly collect the polluted air from the place where pollutants are produced and discharge it to the outside, or directly supply fresh air to the local space. The advantages of local ventilation are good ventilation effect and saving air volume. Ventilation is divided into natural ventilation and mechanical ventilation according to the power on which airflow depends. Natural ventilation: the power of ventilation is the "hot pressure" caused by the temperature difference between indoor and outdoor air and the "wind pressure" caused by outdoor wind. These two factors sometimes exist independently and sometimes at the same time. Mechanical ventilation is the air flow caused by fans. Mechanical ventilation is not limited by natural conditions, and air supply and exhaust can be carried out as needed to obtain stable ventilation effect. In some fields, mechanical ventilation and natural ventilation are often used at the same time. Some rooms have high requirements for air environment, and ambient air is not allowed to flow in (such as operating rooms in hospitals and precision instrument rooms in experimental buildings). ). The mechanical air supply volume of these rooms should be greater than the mechanical air exhaust volume, so that the indoor pressure is greater than atmospheric pressure. Excess air in the room will flow to the outside through gaps such as doors and windows. In some heavily polluted rooms (such as bathrooms, kitchens, etc.). ), in order to prevent dirty air from flowing into the surrounding space, the indoor pressure should be less than atmospheric pressure, so that the dirty air in the room will not flow outside. This is the sign of mechanical ventilation system. Outdoor air enters the air supply room through shutters, and the air supply room is provided with an air filter for purifying air and an air heater for heating air. After purification and heating, the air is pressurized by the fan, transported to the air supply grille (air outlet) in the room through the air duct, and then distributed to each room to mix with the indoor air. Sometimes, the exhausted air is sucked back into the air duct through the lower exhaust port, returned to the air supply room, and mixed with outdoor fresh air for continuous use. The purpose of adopting circulating air is to ensure the relatively uniform distribution of indoor temperature and wind speed under the premise of energy saving. The magnitude of air supply and exhaust volume and the arrangement of air supply and exhaust outlets have great influence on the distribution of air temperature, humidity, speed and pollutant concentration in ventilated rooms. Reasonable arrangement of air supply and exhaust ports and distribution of air supply and exhaust volume are called indoor air distribution. In Xinhua Building, we watched the ventilation system of the underground garage. The ventilation system of underground garage is an independent fire prevention and smoke exhaust system, which consists of air supply system and exhaust system. Air supply means air supply on both sides and air exhaust in the middle, forming convection from both sides to the middle. The air supply frequency on both sides is 10 hour, and the air exhaust frequency is 6 times per hour. With the cooperation of other systems, the garage is always in a negative pressure state, thus ensuring smooth ventilation. Air conditioning system process air conditioning: the purpose is to meet the needs of production technology and scientific research. At this time, air conditioning design is to ensure the technological requirements, and the comfort of indoor personnel is secondary. Air conditioning in computer room, telephone switchboard room, precision electronics workshop and some special laboratories and museums. Visit Yunfeng Pharmaceutical's basement air-conditioning and refrigeration system, read related books and learn about the air-conditioning system. Composition of air conditioning system Central air conditioning system usually consists of the following five parts: air handling equipment, cold and heat sources, air conditioning system, air conditioning water system and control and detection system. Air conditioning system can be divided into all-air system, air-water system, all-water system and refrigerant direct evaporation system according to the medium used to bear indoor heat and temperature load. According to the setting of air handling equipment, it can be divided into centralized, semi-centralized and fully decentralized air conditioning systems. The centralized system integrates all air handling equipment (including fans, surface coolers, heaters, humidifiers and filters, etc.). ) In the air-conditioned room. The temperature and humidity of the air to be treated are centrally adjusted in the air processor, and then transported to the air-conditioned room through the air duct (air duct). According to the season and the change of indoor heat and humidity load, it can be switched and adjusted in time in the air processor. Air treatment equipment of air conditioning system Air treatment equipment includes air purification equipment and air heat and humidity treatment equipment. Air purification treatment equipment Air purification treatment equipment: For the air entering the air-conditioned room, in addition to meeting the temperature, humidity and airflow speed, it also needs to meet the requirements of air purification, that is, removing suspended pollutants such as dust, fog and microorganisms in the air and eliminating various odors. It is best to have enough negative ion content. The air handled by air conditioning system usually consists of outdoor fresh air and return air. Suspended pollutants in the air come from fresh air and return air. The purpose of air purification is to remove the above two aspects of pollution. According to the existing state of indoor pollutants, air purification equipment can be divided into two types: dust removal type to deal with suspended particles and degassing type to deal with gaseous pollutants. In the dust removal air purification treatment equipment, fiber filter is the core, and electret electrostatic filter is also available. Characterized in that the suspended particles are mainly treated by fiber filtration technology or electrostatic filtration technology. Among the degassed air treatment equipment, there are mainly activated carbon filters, photocatalytic filters and air purifiers. Its main feature is to treat gaseous pollutants by adsorption technology, photocatalysis technology and ionization technology. Commonly used air filter 1) coarse filter: the filter object is 10~ 100um large particle dust, which is used for primary filtration of air conditioning system and protection medium filtration. 2) Intermediate filter: the filter object is 1~ 10um, which is used for intermediate filtration of air conditioning system to protect the final filter. 3) High-efficiency air filter: the filter object is 1~5um dust, which is used for final filtration of clean room air supply greater than 10 or intermediate filtration in occasions with high cleanliness requirements. 4) HEPA filter: the filtering object is dust less than 1um, which is used for the final filtering of clean room air supply above 100. Air purifier is an air purification equipment integrating fiber filtration technology, electrostatic filtration technology, activated carbon filtration technology, negative ion technology and ozone technology. Its working principle is that the high-speed rotating centrifugal fan generates negative pressure in the machine body, and the polluted air is sucked into the machine, which passes through the coarse filter screen with sterilization function, the filter layer filled with high-efficiency air filter material and the high-efficiency catalytic activated carbon filter layer in turn, so that the clean air is sent out from the air outlet after triple filtration and purification. Air heat and humidity treatment equipment can be divided into direct contact type and indirect contact type. Direct contact heat and moisture exchange includes water spraying chamber, steam humidifier, local supplementary humidification device and device using liquid hygroscopic agent. Its characteristic is that the medium that exchanges heat and moisture with air is in direct contact with air. Indirect heat and moisture exchange includes smooth tube, finned tube and ribbed tube air humidifier and air cooler. It is characterized in that the medium that exchanges heat and moisture with air is not in direct contact with air, and the heat exchange medium (hot water, steam, cold water and refrigerant) flows in the baffle heat exchange tube, and the treated air flows out of the tube, and the two exchange heat or heat and moisture through the solid arm surface. Air-conditioning cooling water system Air-conditioning cooling water system refers to a system that uses cooling towers to provide circulating cooling water to the condenser of water chillers. It consists of cooling tower, cooling water tank, cooling water pump, chiller condenser and other equipment and their connecting pipes. Condensed water system. Condensed water system. No matter whether the condensation tray of air conditioning terminal equipment is located in the positive pressure section or negative pressure section of the unit, a water seal must be set at the outlet of the condensation tray, and the height of the water seal should not be greater than the positive pressure or negative pressure value at the condensation tray. The positive pressure section is to prevent air leakage, and the negative pressure section is to discharge condensate smoothly. Flow chart of air conditioning system: The gas system mainly visits Dongfang storage and distribution station, which belongs to Class A fire and explosion prevention part. I see a huge gas tank. The gas holder consists of a 10-meter base and three 8-meter sections, with a height of 32 meters. Adjacent parts are connected by reverse pulleys. The gas holder rises and falls freely with the air pressure. When a large amount of gas is used, the air pressure decreases and the gas holder becomes shorter. The pressure of supplying gas to users will also change. For example, during the Chinese New Year holiday, every household has increased the use of gas, which requires more pressure than usual to meet the normal use. Daily stress has also changed, and cooking time is more stressful than usual. The site selection of gas storage and distribution station should consider the requirements of technology, power, water supply and drainage, civil installation, fire prevention and explosion protection, environmental protection and their impact on investment and operating costs, and coordinate with the overall urban planning. The process layout of gas storage and distribution station should ensure reliable work, safe production and convenient operation and management. Buildings and structures should meet the requirements of safe fire prevention spacing, and fire roads should be set around the whole station. Electrical equipment in production workshops, such as pressure transmission and voltage regulation, should consider the requirements of fire prevention and explosion protection. The gas pipeline in the station should be connected in a ring shape, and equipped with bypass pipeline for maintenance and accident. The process flow of gas storage and distribution station should be determined by technical and economic comparison according to the nature of gas source plant, city scale, load distribution and pressure grade system of pipe network. The function of the primary regulator is to reduce the pressure of high-pressure gas to the working pressure of high-pressure gas storage tank and store it in the gas storage tank. The function of the secondary pressure regulator is to adjust the gas pressure to the working pressure of the export pipeline. According to different needs, the gas storage and distribution station is equipped with auxiliary production facilities, living facilities and fire-fighting facilities in addition to the main process equipment such as gas storage, pressure transmission and pressure regulation. The picture below shows the gas supply system. The heating part is mainly based on visiting Shenghua Thermal Power Plant, which works in cogeneration mode, which is a joint production mode of thermal power plant producing electric energy and available heat energy at the same time. The heating system with thermal power plant as heat source is called central heating system of thermal power plant. The comprehensive energy supply mode in which both electric energy and thermal energy are provided by thermal power plants is called cogeneration. Thermal power plant is a power plant that jointly produces electric energy and thermal energy. The heating system of thermal power plant is a cogeneration system which uses steam turbine as heat source to generate electric energy and heat energy at the same time. Using thermal power plant as heat source to realize hot spot co-production is not only efficient in heat utilization, but also beneficial to environmental protection. The heat medium system (the first circulating system) consists of heat source, heat exchanger and heat medium pipe network. The steam generated by the boiler is sent to the heat exchanger to heat cold water through the heat medium pipe network, and is turned into high-temperature water for heating through the heat medium pipe network. The steam after heat exchange becomes condensed water, and most of the newly replenished softened water is sent back to the boiler through the condensing circulating pump to be heated into steam, thus completing the heat transfer process. The hot water supply system (second circulation system) consists of hot water distribution pipe network and backwater pipe network. The cold water heated to a certain temperature comes out of the heat exchanger and is sent to each hot water distribution point through the water distribution pipe network, and the cold water of the heat exchanger is supplemented by the high-level water tank or water supply pipe network. After heating, a certain amount of hot water flows back to the heat exchanger through the return pipe through the circulating water pump. The heat exchange station of thermal power plant has special remote control room and console. Through the remote control station, the pressure and temperature of steam and hot water everywhere can be clearly grasped and adjusted by the controller. At school, we also visited the school's heating paper network equipment, mainly radiators. We visited the canteen, dormitory, library and classroom respectively. In the process of watching radiators, the first floor of the library and comprehensive building is dominated by airfoil radiators, supplemented by column radiators, and other places are dominated by column radiators. Radiator, as a final device to transfer the heat of heating medium to the room, has become an indispensable part of life. Its quality, performance and ugly appearance are directly related to the safety, economy and decoration of use. Therefore, paying attention to radiators means paying attention to their own quality of life. The following figure shows the flow chart of the heating system. The internship experience is intense and full of fun. The internship passed before you knew it. Understanding practice is the foundation of our professional courses, and we can learn many things that books can't. We have only a little knowledge about the common water supply, drainage, heating and fire fighting pipes inside and outside buildings, and we are not very clear about why they are installed this way and not that way, what their working principle is, what they rely on to provide power and so on. I have been interested in HVAC engineering since I received the admission notice. We have only studied basic courses since we entered the university for one year, and have never been exposed to professional courses. Through this internship, I learned the main contents of our major, deepened my understanding of the major, and improved my professional interest and subjective initiative in professional learning; The perceptual knowledge of process flow, system principle and equipment was established, and the operation steps and methods of the system and equipment were preliminarily understood, which improved the practical ability and laid a good foundation for the subsequent professional basic courses and specialized courses. Understand the basic methods of studying and solving practical engineering problems, and cultivate correct engineering consciousness and viewpoint. Through this internship, I have deepened my understanding of the major and the research content of this major, which is still very promising, increased my confidence in learning this major well, and made clear my future development goals.