Central air conditioning overhaul plan

Chapter 1 Maintenance of Central Air-conditioning System Daily maintenance: including on-duty operation, patrol inspection, timely alarm treatment and cleaning treatment when faults are found. Preventive inspection (refrigeration unit, condenser, evaporator, cooling chilled water circulating pump, cooling tower, fresh air unit, fan coil unit): preventive inspection is carried out on various equipment and its accessories, so as to prepare for early fault detection, cause finding and maintenance. Including: operators check once per shift, maintenance personnel patrol once a month, and maintenance personnel overhaul once a year. Unit repair is divided into major repair, medium repair and minor repair, and the cycle is as follows: major repair → minor repair → minor repair → minor repair → minor repair → major repair. Each overhaul cycle basically includes six minor repairs and two medium repairs. Maintenance time reference: overhaul in 5 ~ 7 years, medium repair in 2 years, minor repair in 12 months, and regular inspection every month. 1, refrigeration unit: (Take the water-cooled screw chiller as an example) The unit operators check once per shift and record 1) Check the oil quantity of the compressor oil mirror; 2) Check the high and low pressure equilibrium pressure of the unit refrigerant; 3) Run the unit and check the abnormal sound, vibration and temperature; 4) check the condensation pressure and evaporation pressure; 5) Check the valve opening; 6) Check the water temperature and pressure at the inlet and outlet of chilled water of the unit; 7) Check the inlet and outlet water temperature and pressure of the cooling water of the unit; 8) Check whether the instruments and meters are damaged; 9) If there is any fault in the above items, report to the maintenance personnel in time. Unit maintenance personnel patrol once a month and record 1) check the set parameters and control loop of the unit, and adjust various operation parameters according to actual needs. 2) Check the operation of the refrigeration system, and adjust the superheat if necessary to make the equipment in the best operation state. 3) Check and correct the high and low pressure sensors in the condensing and evaporating parts of the unit. 4) Check and correct the inlet and outlet water temperature sensors of the chilled water system of the unit. 5) Check the power supply voltage of the unit and the balance of three-phase power supply, and suggest adjusting the power supply when necessary. 6) Check the running current value and insulation resistance value of the refrigeration compressor. 7) Check the contactor, thermal relay, solenoid valve and target flow switch, and repair or replace them if necessary. 8) Check the refrigerant liquid mirror, replenish liquid or replace the drying filter properly. 9) Check the oil quality of compressor lubricating oil, and fill and replace the lubricating oil when necessary. Maintenance records of unit maintenance personnel 1) Check monthly maintenance project records every year; 2) Check or replace the refrigerant drying filter and compressor oil; 3) Check the insulation resistance of the compressor motor; 4) Check the safety protection elements; 5) Check and clean the electrical control center; 6) Check the operation of the operation unit; 7) Check abnormal sound, vibration and temperature; 8) Check and adjust the control circuit components; 9) Provide daily operation records and monthly operation records of the unit for maintenance; 10) check the corrosion and insulation of the power supply and control circuit of the refrigeration unit, and suggest replacing it if necessary; 1 1) Check the oil quality of compressor lubricating oil, and fill and replace the lubricating oil if necessary; 12) check the damage of equipment parts and replace them in time to ensure the normal operation of the equipment; 13) Waterway cleaning and start-up debugging are carried out before startup every year, and water discharge inspection is carried out after shutdown; 2. Cooling chilled water circulating pump: operators check and record it once per shift; 1) Check and adjust the shaft seal; 2) Bearing pressurization; 3) Check the abnormal sound 4) Check the rust-proof part; 5) Clean the filter screen of the water pipe filter; 6) check the running current and voltage; The maintenance personnel shall check it once a month and once a year, and the record is: 1) First, check it once a month (the same as the annual inspection); 2) Check the electrical devices and overload protection, and make proper cleaning or adjustment; 3) Check the linkage between water pump and motor; 4) Check the current impulse insulation resistance of the motor; 5) Check all relevant control systems and protection components; 6) Check and replace the shaft seal (mechanical seal); 7) Check the bearings of water pump and motor, and refuel or replace them when necessary; 3, cooling tower operators check and record once per shift (1) to check and clean the tray; 2) Check the water distribution of the water distributor; 3) Check the running current of the cooling fan motor; 4) Check the noise and vibration sources; 5) Check and clean the filter screen and filter of water system; Maintenance personnel check records once a month and once a year: 1) Check daily and monthly maintenance items; 2) Check the scaling of water distributor and filler; 3) Turn on the fan motor, check the rotor or bearing of the motor, and refuel or replace it if necessary; 4. Heat exchangers (condensers, evaporators): the operators shall check and record once per shift: (generally, before the unit runs and stops) 1) Record the inlet and outlet water temperatures and pressures; 2) Check whether there is water leakage; Maintenance personnel shall check the records once a month and once a year: (generally before the unit changes seasons) 1) Check the records of daily and monthly maintenance items; 2) Check and clean the inside of the startup assembly, and replace it if necessary; 5. Humidifier: the operator shall check and record it once per shift: (generally before the unit is running and stopped) 1) Check and clean the filter screen; 2) Check and control the operation of electrical appliances; Maintenance personnel shall check the records once a month and once a year: (generally before the unit changes seasons) 1) Check the records of daily and monthly maintenance items; 2) Open the water outlet box for cleaning 3) Check the protection element 4) Check the insulation resistance of the heating wire; 5) Clean up the electrical control center; The second chapter introduces the cleaning content of central air conditioning system. The central air conditioning system is a whole, and its cleaning and disinfection operations must be comprehensive. 1. Water system 1. Air-cooled cold (hot) water unit: the main cleaning and disinfection parts are the cooling fins (fins) of the condenser and the freezing/heating water side. 2. Water-cooled chiller: the main cleaning and disinfection part is the chilled water/cooling water side. 3. Cooling tower: The main cleaning and disinfection parts are filler, water tray and cooling water side. 4. Water pipes: the main cleaning and disinfection part is its inner wall, but this work must be carried out simultaneously with the water quality treatment and water quality maintenance of the central air conditioning system. 2. Air system 1, fresh air preprocessor (box): The main cleaning and disinfection parts are the radiator of evaporator, the inside of equipment (box) and the frozen/heated water side. 2. Air conditioning box: the main cleaning and disinfection parts are the radiator of evaporator, the inside of the box and the frozen/heated water side. 3. Fan coil unit: The main cleaning and disinfection components are the radiator, condensing plate and freezing/heating water side of evaporator. 4. Air duct: the main cleaning and disinfection part is its inner wall. Chapter III Cleaning of Central Air Conditioning System. Cleaning of central air conditioning water system 1. Central air conditioning plays an important role in regulating temperature. After long-term operation of air conditioners, problems such as scale, rust and dust will inevitably occur in chilled water, cooling water system, refrigeration main engine and fan cooling coils. The specific analysis is as follows: Corrosion: The cooling water and chilled water of air conditioning system are extremely corrosive without treatment. If ordinary steel sheets or nails are put into water, corrosion will occur after a few days, and the longer they are placed, the more serious the corrosion will be. Rust often falls off or even pierces the inner wall of the equipment due to corrosion, which will block the coil and reduce the refrigeration effect; At the same time, the existence of corrosion greatly shortens the service life of the equipment. Scaling: after the inorganic salt dissolved in water in the pipeline is crystallized, scale forms on the wall of heat exchange surface such as condenser, which leads to the decrease of heat exchange efficiency and refrigeration effect, which can reach 30% in severe cases. At the same time, with the increase of scale, electricity consumption or oil consumption will also increase, and it will increase by 35% in severe cases. Biological slime: due to the dirt formed by soil, sediment and humus in water, and the biological slime formed by microorganisms such as bacteria and algae and their secretions, the pipeline will be blocked in severe cases; However, dirt and mud will affect the heat exchange efficiency, consume more energy, cause high-pressure operation, and even cause overpressure shutdown in serious cases. These have seriously affected the normal operation of the air conditioning system. Therefore, the scale, rust, sediment, bacteria, algae and other problems of central air conditioning system will directly lead to the weakening of refrigeration capacity, shortening service life, reducing operational reliability and increasing energy consumption, thus leading to the increase of operating costs. In order to make the central air-conditioning system run in the best condition, it is necessary to carry out special chemical treatment on the cooling water and chilled water system of the air-conditioning system: descaling, derusting, desliming, sterilization and anticorrosion. The significance lies in saving energy and reducing operating costs. In the heat transfer process of evaporator and condenser of central air conditioning, dirt directly affects the heat transfer efficiency and the normal operation of equipment. The operation results of the central air-conditioning unit show that the power consumption or fuel consumption will increase by 10-30% after the unwashed air-conditioning unit runs for a period of time, which will prolong the service life and reduce the depreciation and usage fee of the equipment. Reduce unexpected shutdown and improve refrigeration effect. Cleaning can remove sludge, make the pipeline unblocked and the water quality clear. At the same time, descaling and scale prevention are carried out, which improves the thermal efficiency of condenser and evaporator, thus avoiding the phenomenon of overpressure shutdown during high-pressure operation, increasing the flow of chilled water, improving the refrigeration effect and making the system run safely and efficiently. Save a lot of maintenance costs for users: untreated central air conditioning will cause pipeline blockage, scaling and corrosion, and will stop due to overpressure until an accident occurs. If the main engine leaks due to corrosion and the solution is polluted, it is necessary to replace the copper tube, replace the solution and maintain the main engine. The general maintenance cost is 200,000-500,000 yuan. After treatment, it can not only reduce the maintenance cost, but also prolong the service life of the equipment, and reduce the loss of hundreds of thousands of millions for the owners. Improve the working environment. Rust water, sewage, sludge, bacteria and algae will all have adverse effects on the surrounding environment. Cleaning can effectively solve these problems, thus improving the surrounding environment and protecting the ecological environment. At the same time, the cold and warm air supplied by the air conditioning system is fresh and high quality, which is beneficial to the health of users. 2. Water system cleaning process and steps: first clean the cooling tower and machine room (evaporator and condenser) of the central air conditioner, and then clean the end water pipe. Sterilization and algaecide cleaning-cleaning system-prefilming-corrosion and scale inhibition cold and warm water system (1) Step 1 sterilization and algaecide cleaning: clean the expansion water tank, then add sterilization and algaecide into the water tank, start the pump circulation 16-24 hours, and carry out whole-system sterilization and algaecide stripping and domestic sludge treatment. (2) Step 2: The cleaning system discharges the chilled water at the lowest gate valve of the chilled water system, then adds the system cleaning agent to the expansion tank, and starts the pump circulation for 24 hours, so that the floating rust and oil stains in the system can penetrate and peel off. (3) The third step is the pre-film discharge of chilled water, and the cleaned rust residue and sludge are discharged from the refrigeration system. Dismantle the Y-shaped filter screen of the refrigeration system, remove impurities on the filter screen, reseal the filter, fill the system with water and exhaust until the chilled water is full. Then add the prefilming agent into the expansion tank, start the refrigeration pump to circulate for half to 48 hours, and discharge 2/3 of the water for the fourth step. (4) The fourth step is corrosion and scale inhibition. Add corrosion inhibitor into the expansion tank, and start the pump for 2 hours to make the drugs evenly distributed in the system. Try to measure the PH value. If the PH value is normal, the impregnation test shall be conducted at 8- 10. Under the condition that the system does not leak, the agent can maintain the antirust effect for one year. The first step of cooling water system (1) is to clean the cooling tower plate, packing, etc. Clean its dust, sludge and moss with a high-pressure water gun. (2) Step 2, add the sterilization and algaecide into the tower, and start the pump cycle for 16-24 hours to carry out the whole system sterilization and algaecide treatment. (3) Step 3: Add the system cleaning agent into the tower, and start the pump cycle for 16-24 hours to make the floating oil in the cooling system permeate and peel off. (4) Step 4: Drain the cooling water, clean the cooling tower, remove the Y-type filter of the cooling water system, clean the impurities in the filter screen and top it up. (5) Step 6: Add the prefilming liquid into the cooling tower and start the pump circulation for 48 hours. This agent can cover the metal surface with a film to prevent the dissolved oxygen in water from being adsorbed on the pipe wall. 2. Cleaning of central air conditioning air system 1. Cleaning steps of the branch air duct: a, the robot inspects and videos the inside of the air duct; Put the robot into the air duct to be detected from the detection port to detect the internal pollution of the air duct. By monitoring the camera unit, you can see the pollution inside the air duct and the tracking video of the whole detection process on the display screen, and you can also fill in some relevant records at any time. B, that suction pipe of the dust suction box is connecte with the dust suction port on the main air duct; The opening on the air duct is used as the suction pipe interface of the vacuum cleaner equipment, and the connector connects the ventilation pipe and the vacuum cleaner through a special hose (the opening is close to the air supply outlet, and the existing air outlet can be used as the suction pipe interface of the vacuum cleaner). C, removing the diffuser and the air return opening on the branch air duct, cleaning and disinfecting, and then drying; Remove all diffusers and put them in designated places for centralized cleaning. If the dust is soft and easy to blow off, it can be cleaned with high-pressure air. If it is stained with oil, spray a special cleaning agent on its surface for 5 minutes-10 minutes, then clean it with clear water, and dry it (blow dry) after cleaning. D, clean the branch air duct with soft brushes, nozzles, electric universal brushes and other tools, so that the fire damper at the joint of the uncleaned branch air duct and the main air duct is in a closed state, and the dust box is in an open state during cleaning; When cleaning, use the electric universal brush to clean the small air duct of the central air conditioning ventilation system, and use the air soft brush or air nozzle to clean the curved ventilation pipe section and riser. E, check the cleaning effect until visual cleaning is achieved; During inspection, the inspection robot enters the pipeline for inspection and observation, and it is qualified if it is clean with the naked eye. 2. Cleaning steps of the main air duct: a. Fire dampers at the fresh air outlet and the joint of the main and branch air ducts. If necessary, both ends of the cleaning section are blocked with air bags, and the dust box is opened; B, distinguish air ducts with different specifications, clean and blow pollutants with cleaning robots, electric universal brushes, air nozzles and other tools, and collect pollutants with negative pressure generated by vacuum boxes; Put the cleaning robot into the cleaned central air conditioning duct for cleaning operation, and clean the inner wall of the duct from near to far. When cleaning, the brush head or robot enters the pipeline along the operation port to peel off the pollutants attached to the inner wall of the pipeline, so that they are transported to the vacuum cleaner by the airflow made by the vacuum cleaner and absorbed. Through the monitored camera unit, you can see the cleaning situation in the air duct and the working situation of the equipment on the display, so as to control the lifting height and walking direction of the mechanical arm and roller brush by operating the buttons. When the air nozzle is used for purging operation, the purging equipment enters the air duct along the operation port for high-pressure air purging, and pollutants are transported by compressed air flow. If necessary, it can be used with a cleaning robot to completely suck out the dust in the air duct. C, after cleaning, take out the tools, use the inspection robot for effect inspection and video recording, install the diffuser and air return port, install the valve and close it, open the fire valve, and fill in the records. 3. Cleaning steps of vertical or sloping air ducts with a drop of more than 38o: a. Vertical air ducts are generally only in air-conditioning machine rooms or ventilation shafts. In view of this situation, the interface of the vacuum cleaner should be opened at the bottom of the air duct. At the highest point, the air duct with gradient and drop greater than 38o should be repeatedly blown into the air duct with high-pressure blowing device. B for the air duct with gradient and drop greater than 38O, the high-pressure air blower should be used to blow air into the air duct repeatedly according to the above method. 4. Cleaning steps of air duct accessories: the air duct accessories are opened nearby, and cleaned with small negative pressure cleaning dust collection equipment (Note: the air duct detection device is generally connected with the fire alarm device, and then the air duct detection device is moved or removed after the fire alarm device is turned off. 5. Cleaning steps of the filter screen: a. When removing the filter screen of the air conditioner, do not touch the metal part of the unit to prevent scratches. After removing the air filter, gently pat the bomb or use an electric vacuum cleaner to remove dust. B, if the filter dust is too much, you can use water or neutral detergent, but you can't use hot water above 50 degrees to avoid deformation, and don't use sponge to clean it, otherwise it will damage the surface of the filter. C, rinse with clear water, and put it in a cool place to dry. Never expose it to the sun or bake it with fire, because it will lead to the deformation of the filter element. D, install the dried filter screen to the original position of the unit, and the whole filter screen maintenance process ends. 6. Cleaning steps of outdoor air inlet: A, check the external conditions of air inlet, check the external skylight, and check whether the glass and paint are complete. Remove all debris and paint to prevent them from falling into the central air conditioning system. B, clean the inside of the air inlet, and check the firmness and integrity of the sunroof regulator, sunroof blades and window frames. Remove all debris, dirt and falling paint with a nozzle or brush. When cleaning, it should be opposite to the air flow direction. Make sure there are adequate drainage facilities. If not, you need a wet and dry vacuum cleaner to remove all the remaining water. C if the metal surface is corroded, it needs to be scraped off and repainted to prevent further corrosion. (Note: If water is needed in the cleaning process, all electrical boxes, sensors and appropriate sensing devices need to be covered and protected before they can be cleaned. 7. Cleaning steps of the mixing box: a. Open the mixing box, first remove the panel of the central air conditioner, or use the existing opening. It should be noted that if the panel is opened, it is necessary to leave an air plug or gasket in order to resume use. Check the mixing box wall, find out its internal pollution, and put forward cleaning suggestions. At the same time, it is also necessary to check the corrosion of metal and whether its structure is complete. The initial cleaning of the mixing box is to remove the floating soil. Using portable negative pressure vacuum cleaning equipment to clean the mixing box can effectively remove all debris and dust in the air. The tools equipped with the vacuum cleaner should be used according to the actual situation on site. If water washing is needed, please make sure that the drainage device is ready before cleaning. If the metal has been corroded, surface treatment is needed. Scrape off the corroded surface and paint it to prevent the metal surface from further corrosion and prevent pollutants from entering the first filter plate. The paint used for spraying shall conform to local standards and be the same as that used in the original central air conditioner. C, after preliminary cleaning, check the mixing box. If there is insulation in the box, check whether it is complete. If the insulation layer falls off, stick it with glue and clean up the fallen debris. Press the insulating layer by hand to see if it is complete. If the insulation layer is damaged and falls off, pay attention to record it in the inspection report. D after cleaning, put away all cleaning equipment, restore the opening of the panel, and apply necessary sealant. 8. Cleaning steps of the diffuser: a. Seal the mouth where the diffuser is connected with the pipeline to prevent the dirt sprayed by the nozzle from spreading outward. Seal with wide tape or something similar (make sure the tape won't stick to the paint). Or may be sealed with a filter medium. B, don't close the diffuser farthest from the pipeline operation port, to ensure that there is air supplement in the pipeline, and the maximum air volume can flow to the debris collection equipment. Other inaccessible parts of the diffuser need to be cleaned manually. Please refer to the operation manual for more detailed introduction. 9. Cleaning steps of the static pressure box: When cleaning the static pressure box, firstly, one end of the static pressure box needs to be perforated (according to the on-site formula), and the dust on the inner surface of the cavity is removed by portable negative pressure dust suction equipment, and then the noise elimination equipment (fiber cotton) in the cavity and micro-holes is repeatedly blown and washed by an air negative pressure machine, so that the fiber cotton is loosely activated, thus playing a better role in noise elimination. After that, the portable negative pressure vacuum cleaning equipment is used to repeatedly vacuum clean the cavity. Finally, disinfect with disinfectant. 10. Cleaning steps of the air-conditioning host: a. Cleaning the air-conditioning unit should be carried out after cleaning the return air pipeline, and the air valves on the supply and return air pipelines should be closed. If it is an electric valve, please ask the property department to help close it. B, take out the air filter on the return air section, clean it with water in the water room and put it in a well-ventilated place to dry. C, use the suction vacuum cleaner to clean the dust on the four walls and the box of the heat exchange coil in the return air section of the unit, and use compressed air to blow clean the dust in the inner gap of the heat exchange coil. During operation, the fins of the coil should be prevented from bending and deformation, and dust should be collected with a vacuum cleaner while blowing. D, after the dust collection, wash the wall and heat exchange coil with water, and drain the sewage into the floor drain of the computer room through the drain pipe. After cleaning, blow dry with compressed air. E, in the air supply section of the unit, it is strictly prohibited to wash directly with water because of the motor and junction box. First, wrap the fan and wire box tightly with a cover to prevent water from entering. Use a vacuum cleaner to clean the dust on the four walls of the heat exchange coil and the air supply section box, and use compressed air to spray the dust in the gap in the inner layer of the heat exchange coil. During operation, the fins of the coil should be prevented from bending and deformation, and dust should be collected with a vacuum cleaner during spraying. F, remove the plastic bag wrapped around the fan and junction box, and check whether the fan and junction box are flooded, otherwise it should be handled in time. 1 1. On-site recovery Step A: Turn off the power supply of the cleaning equipment, clean up the pollutants on the cleaning equipment and box them, and move the equipment to the next working area. B, clean up the site, remove and replace the filter in the dust box, and collect and concentrate pollutants. C, restore the order of the site, and ensure that the site equipment and facilities are not polluted. D, go to the next workspace for cleaning, and the operation procedure is as above.