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Delivery: <= 13 days. True-PDF full-copy in English will be manually translated and delivered via email. GB 50648-2011: Code for design of recirculating cooling water system in chemical plant Status: Valid
Basic dataStandard ID: GB 50648-2011 (GB50648-2011)Description (Translated English): Code for design of recirculating cooling water system in chemical plant Sector / Industry: National Standard Classification of Chinese Standard: P72 Classification of International Standard: 71.010 Word Count Estimation: 96,924 Date of Issue: 2010-12-24 Date of Implementation: 2011-12-01 Quoted Standard: GB 50050; GB 50013; GBJ 87 Regulation (derived from): Ministry of Housing and Urban Notice No. 878 Issuing agency(ies): Ministry of Housing and Urban-Rural Development of the People's Republic of China; General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Summary: This Chinese standard applies to new construction, expansion, renovation projects in chemical engineering circulating cooling water systems engineering design. GB 50648-2011: Code for design of recirculating cooling water system in chemical plant---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.1 General 1.0.1 In order to make the design of the circulating cooling water system in the chemical industry comply with national guidelines, policies, laws and regulations, unify the technical requirements for system design, achieve safety, reliability, advanced technology, reasonable economy, convenient management, and maintenance, and meet water-saving requirements, energy saving and environmental protection, labor safety and sanitation protection and other requirements, formulate this specification. 1.0.2 This code is applicable to the design of circulating cooling water system engineering of new construction, expansion and reconstruction of chemical engineering projects. 1.0.3 The design of the circulating cooling water system in the chemical industry should actively and steadily adopt effective new processes, new technologies, new equipment and new materials on the basis of continuously absorbing domestic and foreign advanced technologies, summarizing production practice experience and scientific experiments. 1.0.4 The design of the chemical industry circulating cooling water system project shall not only implement this specification, but also comply with the current relevant national standards. 2 terms 2.0.1 recirculating cooling water system A water supply system that uses water as the cooling medium and circulates, consisting of heat exchange equipment, cooling facilities (equipment), treatment facilities, water pumps, pipelines and other related facilities. 2.0.2 indirect open recirculating cooling water system indirect open recirculating cooling water system A circulating cooling water system in which the circulating cooling water and the cooled medium indirectly transfer heat and the circulating cooling water directly contacts the atmosphere to dissipate heat. 2.0.3 Indirect closed recirculating cooling water system indirect closed recirculating cooling water system Circulating cooling water and cooling medium indirect heat transfer and circulating cooling water and cooling medium are also indirect heat transfer circulating cooling water system. 2.0.4 direct open recirculating cooling water system The circulating cooling water system is a circulating cooling water system in which the circulating cooling water is in direct contact with the cooled medium to exchange heat and the circulating cooling water is in direct contact with the atmosphere to dissipate heat. 2.0.5 secondary water secondary water After the first use, the water quality can meet the water reuse without treatment. 2.0.6 wet cooling tower wet cooling tower A cooling tower in which water and air are in direct contact, and heat and mass exchange are performed simultaneously to lower the water temperature. 2.0.7 dry-wet cooling tower A cooling tower that combines the functions of air cooling and wet cooling towers. 2.0.8 natural draft cooling tower natural draft cooling tower The cooling tower that provides the air flow power in the tower by the draft force formed by the difference in air density inside and outside the tower. 2.0.9 Mechanical ventilation cooling tower The power of the air flow in the tower is the cooling tower provided by the ventilation machinery (fan). 2.0.10 counter-flow cooling tower The air enters the tower from the air inlet at the lower part of the tower, and exchanges heat with the water flowing from the upper part of the tower to reduce the water temperature. 2.0.11 Cross-flow cooling tower cross-flow cooling tower The air enters the tower horizontally from the air inlet of the tower, and passes through the packing perpendicular to the water flow direction to reduce the water temperature of the cooling tower. 2.0.12 Water spray packing It is installed in the cooling tower, so that there is sufficient contact time and area between water and air, which is conducive to the filling material of heat and mass exchange. 2.0.13 net area of water drenching The cross-sectional area of the beam and column area deducted from the top of the cooling tower spray fill. 2.0.14 water eliminator drift eliminator It is a device installed in the cooling tower to recover the liquid water (water droplets, water mist) entrained in the tower airflow. 3 circulating cooling water system3.1 General provisions 3.1.1 The design of the circulating cooling water system shall include the division of the system and the layout of the circulating cooling water device area, the design of the circulating water cooling facilities, the design of the circulating cooling water water quality treatment, the design of the circulating cooling water pumping station, the design of the water transmission and distribution pipe network and the design of supporting facilities. 3.1.2 The design of the circulating cooling water system should be based on the water balance plan of the whole plant, making full use of reclaimed water and reducing the consumption of water resources. 3.1.3 The design of circulating cooling water system shall meet the following requirements. 1 It shall meet the requirements of the heat exchange working condition of the production device; 2 For process heat exchange equipment with large differences in water temperature, water quality or water pressure requirements, circulating cooling water systems should be installed separately; for individual heat exchange equipment with high water pressure requirements, local pressure boosting measures should be adopted; 3 The production process requires that the devices or units that cannot interrupt the circulating cooling water supply shall have safe water supply guarantee measures. 3.1.4 The design water volume of the circulating cooling water system shall be calculated according to the normal hourly water consumption of process production equipment and auxiliary production equipment, and shall be checked by the maximum hourly water consumption. 3.1.5 The design water supply temperature of the indirect cooling open type and direct cooling open type circulating cooling water system shall be determined by thermodynamic calculation according to the water supply temperature allowed by the production process and combined with the meteorological conditions of the plant construction area. 3.1.6 The water supply temperature of the intercooled closed circulation cooling water shall be determined according to the requirements of the production process and combined with the temperature of the cooling medium. 3.1.7 The expansion tank of the intercooled closed system shall have functions such as nitrogen automatic pressure regulation, water level detection, automatic water replenishment and discharge, and prevention of air entering the system. 3.1.8 The pressure of the return water of the intercooled open circulating cooling water system should be fully utilized. 3.1.9 The collecting pool and suction pool under the cooling tower of the circulating cooling water system should not be used as a fire fighting pool. 3.2 Basic information 3.2.1 The multi-year meteorological statistical data of the plant construction area or adjacent areas selected for the design of the circulating cooling water system shall meet the following requirements. 1 Meteorological data such as dry and wet bulb temperature and atmospheric pressure should be calculated based on the daily average wet bulb temperature, and the average number of hottest days in the hottest period in the past five years in the factory area should not exceed 5d-10d. The daily average wet-bulb temperature shall be used as the design wet-bulb temperature, and the corresponding daily average dry-bulb temperature and atmospheric pressure shall be used as the design dry-bulb temperature and atmospheric pressure; 2 For the dust content data in the atmosphere, the average value of the maximum daily dust content in the past 5 years should be used as the design basic data; 3 It is advisable to use the wind direction and wind frequency throughout the year as the basic data for design; 4 When the circulating cooling water device is located in the existing factory area or adjacent to other buildings (structures) and devices that may emit moisture and heat sources, attention should be paid to the influence of the surrounding environment on the circulating cooling water cooling facility;, attention should be paid to the influence of regional microclimate. 3.2.2 The data collection of the heat transfer conditions of the production process shall include the following contents. 1 The structural form and material of the heat exchanger; 2 The process medium and properties to be cooled; 3 Process operating conditions of the heat exchanger. 3.2.3 The supplementary water source and water quality data collection shall include the following contents. 1 The supply conditions of surface water, groundwater and available recycled water sources; 2 The surface water source should not be less than the monthly water quality analysis data of the past year; 3 The groundwater source should not be less than the quarterly water quality analysis data of the past year; 4 The reclaimed water source should not be less than the full water quality analysis data of the reclaimed water treatment system that has been running stably month by month for the past year. 3.2.4 The collection of basic data in the factory construction area shall include the following contents. 1 The types and supply conditions of biocides that can be used to control the reproduction of microorganisms in the factory construction area and surrounding areas; 2 Engineering geology, hydrogeology and other data of the plant construction area. 3.3 System division 3.3.1 The circulating cooling water system shall determine centralized or partitioned settings based on the following factors. 1 Requirements of the production process on the water quality, water quantity, water temperature and water pressure of circulating cooling water; 2 The plane position and elevation of each production device; 3 Requirements for the overall planning of the factory and phased construction; 4 Open and stop operation cycle. 3.3.2 The cooling water for indirect heat exchange with process materials in the production process should adopt an indirect open-type circulating cooling water system. 3.3.3 The process requires high heat transfer conditions, and the circulating cooling water system that requires demineralized water or desalinated water as the cooling medium should adopt an intercooled closed circulating cooling water system. 3.3.4 For the circulating cooling water that is in direct contact with the process materials and is polluted during the production process, an independent direct-cooling open-type circulating cooling water system should be set up. 3.3.5 When the supplementary water of the circulating cooling water system comes from various water sources and the water quality differs greatly, different circulating cooling water systems should be divided according to the water quality and water supply of the supplementary water source. 3.3.6 The scale of the intercooled open circulating cooling water system can be divided according to the following ranges. 1 When the system capacity is greater than or equal to 15000m3/h, it shall be large; 2 When the system capacity is greater than or equal to 3000m3/h and less than 15000m3/h, it shall be medium-sized; 3 When the system capacity is less than 3000m3/h, it shall be small. 3.4 Location selection 3.4.1 The position of the circulating cooling water device shall be determined by comprehensive comparison of the following factors. 1 Close to the main water use device or workshop of circulating cooling water; 2 Keep away from open-air heat sources, dust pollution sources, flue gas outlets, chemical storage yards, bulk warehouses and noise-sensitive areas in the factory; 3 The air flow is smooth, and the influence of hot and humid air backflow is small; 4 There are sufficient convenient conditions for site layout and development and expansion; 5 Engineering geological conditions of the site. 3.4.2 The circulating cooling water device should be built on the windward side of the annual minimum frequency wind direction adjacent to buildings (structures) and power transformation (distribution) devices. 3.4.3 The circulating cooling water device should be installed outside the explosion-proof area divided by the production equipment. When it is located in the explosion-proof area, the selection and installation design of its electrical and instrumentation equipment should comply with the relevant current national explosion-proof standards. 3.4.4 The intercooled closed circulating cooling water device should be arranged in the production process area, or it can be combined with the intercooled open circulating cooling water device. 3.5 Device layout 3.5.1 The layout of the circulating cooling water device shall make full use of the topography, and be reasonably arranged in consideration of factors such as the relationship between individual buildings (structures) and the integration of pipelines in the device. 3.5.2 Buildings (structures) such as substation (distribution) room, water quality treatment room, and chemical room in the circulating cooling water device should be adjacent to the pumping station. 3.5.3 Circuits, inspection and transportation passages should be set up between the buildings (structures) in the circulating cooling water device. 3.5.4 The ground around the buildings (structures) in the circulating cooling water device should be paved. 3.5.5 When the environmental conditions permit, the equipment and facilities such as the pumping station and side filter in the circulating cooling water device should be arranged in the open air. 3.5.6 For the open circulating cooling water system adopting gravity self-flow return water, the water suction pool of the hot water lift pump set and the water suction pool of the circulating feed water pump set should be arranged next to each other, and the top overflow connection should be provided. 3.5.7 The return water sedimentation treatment tank of the direct cooling open-type circulating cooling water system should be close to the production process area, and sediment removal facilities and temporary storage yards should be set up.4 System water balance4.1 General provisions 4.1.1 The circulating cooling water system should determine a reasonable concentration factor based on the supplementary water quality, circulating cooling water quality, and environmental requirements. The concentration factor of the intercooled open-type circulating cooling water system should not be less than 5.0, and should not be less than 3.0. 4.1.2 The circulating cooling water system shall carry out water balance calculation according to the design water volume and heat transfer conditions, regional meteorological conditions and concentration multiple, and shall determine the system's evaporation water loss, wind blowing water loss, sewage loss water loss and system replenishment water volume. 4.1.3 Under the conditions allowed by the production process, the intercooling circulating cooling water should be used in cascade. 4.2 Calculation of water balance 4.2.1 The evaporation loss of the intercooled open circulating cooling water system should be calculated according to the following formula. 4.2.2 The wind blowing water loss of the cooling tower should be calculated according to the following formula. 4.2.3 The sewage discharge volume of the intercooled open circulating cooling water system should be calculated according to the following formula. 4.2.4 The supplementary water volume of the intercooled open circulating cooling water system can be calculated according to the following formula. 4.2.5 The design concentration factor of the intercooled open circulating cooling water system can be calculated according to the following formula. 4.2.6 The supplementary water volume of the intercooled closed circulating cooling water system should be 1‰ of the circulating cooling water volume. 4.2.7 The sewage of the intercooled open circulating cooling water system should be controlled uniformly, and should be discharged in a concentrated manner in the area of the circulating cooling water device, and the total sewage volume should be controlled within the allowable sewage volume range of the circulating cooling water system. 4.3 Water quality balance 4.3.1 When it is necessary to remove suspended solids in the water during the operation of the intercooled open-type circulating cooling water system, side-flow filtration should be used, and the amount of side-filtration water can be calculated according to the following formula. 4.3.2 When the circulating cooling water system adopts side flow water treatment to remove alkalinity, hardness, certain ions or other impurities, the amount of side flow treatment water should be based on the concentrated or polluted water quality components, circulating cooling water water quality indicators and side flow treatment After the water quality requirements are determined, it can be calculated according to the following formula. 4.3.3 When multiple water sources are used as supplementary water or reclaimed water is used as supplementary water source, water quality balance calculation shall be carried out, the proportion of supplementary water from various water sources shall be reasonably allocated, and the corresponding concentration multiple shall be determined. 4.3.4 The direct-cooling open-type circulating cooling water system shall carry out water quality balance calculation according to the control requirements of the system water quality index, and shall determine a reasonable amount of discharged sewage and corresponding treatment measures. 4.4 System volume 4.4.1 The designed residence time of the intercooled open circulating cooling water system should not exceed the allowable residence time of the agent. The design residence time can be calculated as follows. 4.4.2 The volume of the intercooled open circulating cooling water system can be calculated according to the following formula. 4.4.3 The water volume of the intercooled closed circulation cooling water system can be calculated according to the following formula.5 cooling facilities5.1 General provisions 5.1.1 The capacity of the cooling facility should match the heat load required by the production unit, and it may not be used. 5.1.2 The thermodynamic calculation of the cooling tower should adopt the enthalpy difference method, and the segmental integral method can also be used. 5.1.3 The water spraying area of the cooling tower shall be the effective water spraying area of the filler. 5.1.4 The number of mechanical ventilation cooling towers should not be less than 2; the sump under the tower of multiple combined cooling towers should be combined with necessary separation measures for tower body maintenance, management, overhaul, etc. 5.1.5 The cooling facilities in dusty areas should be equipped with sand prevention and sand discharge measures. 5.1.6 The design of the cooling tower shall meet the requirements of operation, maintenance and safety protection. 5.1.7 Cooling towers in cold regions should be equipped with antifreeze facilities. 5.2 Selection of cooling facilities 5.2.1 The selection of cooling facilities should be determined according to the working conditions of the production unit and the local meteorological conditions. 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