Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This code is revised by China Huanqiu Contracting & Engineering Co., Ltd. jointly with organizations concerned according to the requirements of "Notice on Printing and Distributing the Development and Revision Plan of National Engineering Construction Standards and Codes in 2014" (JIANBIAO [2013] No. 169) issued by the Ministry of Housing and Urban-Rural Development of the People’s Republic of China. This revision, following the state's guidelines and policies on basic construction, focuses on water saving, energy saving and environmental protection. This code is revised through in-depth investigation of new situations and problems in the engineering construction and difficult problems in the implementation of the code, careful study and reference to the experience of developed countries, relevant technical research and tests, and extensive consultation with relevant design, production, construction, scientific research and other units.
This code consists of 9 clauses and 3 appendixes, mainly including general provisions, terms and symbols, recirculating cooling water treatment, side stream treatment, makeup water treatment, reclaimed water treatment, blowdown treatment, storage and dosing of chemicals, monitoring, control and analysis, etc.
The items revised and added in this revision are as follows: terms, symbols, indirect (open and closed) and direct recirculating cooling water system, form of side filter, water quality index of reclaimed water and dosing method of chemicals.
The Ministry of Housing and Urban-Rural Development of the People’s Republic of China is in charge of the administration of this code; the Branch of Chemical Engineering, China Association for Engineering Construction Standardization is responsible for the routine management; China Huanqiu Contracting & Engineering Co., Ltd. is responsible for the explanation of specific technical contents. In case of any comment or suggestion during the implementation of this code, please send it to the management group of Code for design of industrial recirculating cooling water treatment of China Huanqiu Contracting & Engineering Co., Ltd. (Address: No.1, Chuangda Road 2, Laiguangying High-tech Park, Chaoyang District, Beijing; 100012) for future reference.
Chief development organization, participating development organizations, chief drafters and chief examiners of this code:
Chief development organization: China Huanqiu Contracting & Engineering Co., Ltd.
Participating development organizations: Nalco (China) Environmental Solutions Co., Ltd.
Capital Engineering & Research Incorporation Ltd.
North China Power Engineering Co., Ltd.
China Kunlun Contracting & Engineering Corporation
University of Science and Technology Beijing
Main drafters: Jin Bo, Sun Jitao, Pu Weixian, Huang Runde, Su Lei
Wang Jianjun, Liu Junmei, Ding Guizhi, Chen Xinquan, Zhang Hailin
Lin Qingzong, Sun Bixin, Tong Yinyin, Li Xiaogang, Liu Zhiyong
Chief examiners: Liu Lisheng, Ma Qiang, Li Bengao, Zhang Hong, Han Hongqi
Tang Anzhong, Jiang Xiaoming, Yu Xuefeng, Cai Guanping, Li Xuzhong
Yang Wenzhong, Yi Longxin
Contents
1 General provisions 1
2 Terms and symbols 1
2.1 Terms 1
2.2 Symbols 3
3 Recirculating cooling water treatment 5
3.1 General requirements 5
3.2 System design 10
3.3 Scale and corrosion inhibition 12
3.4 Sedimentation and filtration 14
3.5 Biological control 15
3.6 Cleaning and prefilming 16
4 Side stream treatment 17
5 Makeup water treatment 19
6 Reclaimed water treatment 20
6.1 General requirements 20
6.2 Treatment process 21
7 Blowdown treatment 22
8 Storage and dosing of chemicals 23
8.1 General requirements 23
8.2 Storage and dosing of acid and alkali 25
8.3 Dosing of scale and corrosion inhibition chemicals 25
8.4 Storage and dosing of biocide 26
9 Monitoring, control and analysis 27
Appendix A Data sheet of water quality analysis 31
Appendix B Verification of water quality analysis data 32
Appendix C Curves of pH and total alkalinity of recirculating cooling water 33
Explanation of wording in this code 34
List of quoted standards 35
1 General provisions
1.0.1 This code is developed in order to implement the national policies on water saving, energy saving and environmental protection, and to make industrial recirculating cooling water treatment such designed to be technologically advanced, economical and practical, safe and reliable.
1.0.2 This code is applicable to the design of industrial recirculating cooling water treatment for new construction, extension and renovation using surface water, groundwater and reclaimed water as makeup water.
1.0.3 Industrial recirculating cooling water treatment shall be such designed by drawing on advanced production practice experience and scientific research achievements at home and abroad that it meets the requirements of safe production, environmental protection, energy conservation and water conservation, and is convenient for construction, maintenance and operation management.
1.0.4 In addition to this code, the design of industrial recirculating cooling water treatment shall also meet the requirements of the current relevant standards of the nation.
2 Terms and symbols
2.1 Terms
2.1.1 recirculating cooling water system
water supply system that uses water as a cooling medium and will recirculate, and consists of heat exchange equipment, cooling device, treatment facility, water pump, pipeline and other related facilities
2.1.2 surface water
water, rivers, lakes, glaciers and swamps, etc. that exist on the land surface and are exposed to the atmosphere, excluding seawater
2.1.3 open system
generic term of indirect and direct open cooling systems
2.1.4 indirect open recirculating cooling water system
recirculating cooling water system that transfers heat indirectly between the recirculating cooling water and the cooled medium and radiates heat through direct contact between the recirculating cooling water and the atmosphere, hereinafter referred to as the indirect open cooling system
2.1.5 direct open recirculating cooling water system
recirculating cooling water system that transfers heat through direct contact between the recirculating cooling water and the cooled medium and radiates heat through direct contact between the recirculating cooling water and the atmosphere, hereinafter referred to as the direct cooling system
2.1.6 indirect closed recirculating cooling water system
recirculating cooling water system that transfers heat indirectly between the recirculating cooling water and the cooled medium and has the recirculating cooling water not in contact with the atmosphere, hereinafter referred to as the closed cooling system
2.1.7 chemicals
chemicals used in the treatment of recirculating cooling water.
2.1.8 count of aerobic heterotrophic bacteria
number of heterotrophic bacteria colonies per milliliter of water counted by the total bacterial plate count, in CFU/mL
2.1.9 slime
sticky substance mixing microbes and their mucus with other organic and inorganic impurities
2.1.10 slime content
volume of slime contained in recirculating cooling water determined by biological filtrating screen method, in mL/m3
2.1.11 fouling resistance
numerical value of the degree of heat transfer efficiency reduction caused by sediments on the heat transfer surface of heat exchange equipment, in m2·K/W
2.1.12 corrosion rate
annual average corrosion depth calculated by weight loss of metal corrosion, in mm/a
2.1.13 adhesion rate
monthly fouling growth amount on the unit heat transfer surface of the heat exchanger, in mg/(cm2·month)
2.1.14 system capacity volume
sum of total water volume in the recirculating cooling water system, in m3
2.1.15 cycle of concentration
ratio of the salt content of recirculating cooling water to that of makeup water
2.1.16 monitoring test coupon
standard metallic test coupon placed in heat exchange monitoring equipment, test tubes or tower tanks for monitoring corrosion
2.1.17 prefilming
process of circulating the prefilming liquid through the heat exchange equipment to form a uniform and compact protective film on the metal surface
2.1.18 side stream
portion of water that is diverted from the recirculating cooling water system and treated before returning to the system
2.1.19 permitted retention time of chemicals
effective time of chemicals in recirculating cooling water system
2.1.20 amount of makeup water
amount of water supplemented for loss during the operation of the recirculating cooling water system, in m3/h
2.1.21 amount of blowdown
amount of water that needs to be discharged from the recirculating cooling water system under certain cycle of concentration, in m3/h
2.1.22 reclaimed water
water derived from wastewater which, after being properly treated, reaches certain requirements for use
2.1.23 stability index
difference between the saturation pH value of 2 times of water and the actual pH value of water It is used to judge the corrosion or scaling tendency of water
2.1.24 scaling inhibition
process of inhibiting or delaying the formation and growth of scale in the recirculating cooling water system
2.1.25 corrosion inhibition
process of inhibiting or delaying metal corrosion in the recirculating cooling water system
2.2 Symbols
A——the air flow of cooling tower (m3/h);
Ac——the dosage of sulfuric acid (kg/h);
C——the dust content of air (g/m3);
Cmi——the content of an ingredient in makeup water (mg/L);
Cms——the suspended solid content of makeup water (mg/L);
Crs——the suspended solid content of recirculating cooling water (mg/L);
Cri——the content of an ingredient in recirculating cooling water (mg/L);
Csi——the content of an ingredient in water after side stream treatment (mg/L);
Css——the suspended solid content of filtered water (mg/L);
Gf——the first dosage (kg);
Go——the dosage of oxidizing biocide (kg/h);
Gr——the dosage during system operation (kg/h);
g——the dosage of recirculating cooling water per liter (mg/L);
go——the dosage of oxidizing biocide per liter of recirculating cooling water (mg/L);
Ks——the settlement coefficient of suspended solids;
k——the evaporation loss coefficient (1/℃);
Mm——the alkalinity of makeup water (mg/L, by CaCO3);
Mr——the controlled alkalinity of recirculating cooling water (mg/L, by CaCO3);
N——the cycle of concentration;
Qb——the amount of blowdown (m3/h);
Qb1——the amount of forced blowdown (m3/h);
Qb2——the amount of water loss during recirculating cooling water treatment, i.e. amount of natural blowdown (m3/h);
Qc——the water evaporation amount (m3/h);
Qm——the amount of makeup water (m3/h);
Qr——the amount of recirculating cooling water (m3/h);
Qsf——the amount of side-filtered water (m3/h);
Qsi——the amount of water subjected to side stream treatment (m3/h);
Qw——the amount of drift and blow-out water loss(m3/h);
RSI——the stability index;
Td——the designed retention time (h);
Δt——the temperature difference between cooling tower inlet and outlet of recirculating cooling water (℃);
V——the system capacity volume (m3);
Ve——the water capacity of recirculating cooling water pump, heat exchanger and other water treatment facilities (m3);
Vp——the water capacity of process production equipment (m3);
Vk——the water capacity of expansion tank or water tank (m3);
Vr——the recirculating cooling water pipeline capacity (m3);
Vt——the water capacity of water tank (m3).
3 Recirculating cooling water treatment
3.1 General requirements
3.1.1 The recirculating cooling water treatment scheme shall be determined through comprehensive technical and economic comparison according to the water balance scheme and salt balance scheme of the whole plant and in combination with the water treatment process of the whole plant. The design scheme shall include the following content:
1 Makeup water sources, amount, quality and treatment scheme;
2 Design cycle of concentration, scale and corrosion inhibition, cleaning and prefilming treatment scheme and control conditions;
3 System blowdown treatment scheme;
4 Side stream treatment scheme;
5 Biological control scheme.
3.1.2 The amount of recirculating cooling water shall be determined according to the maximum hourly water consumption of the production process.
3.1.3 Makeup water quality data collection should meet the following requirements:
1 When surface water is used as makeup water, there should be monthly complete water quality analysis data of not less than one year;
2 When groundwater is used as makeup water, there should be quarterly complete water quality analysis data of not less than one year;
3 When reclaimed water is used as makeup water, there should be monthly complete water quality analysis data of not less than one year, including reclaimed water source composition and treatment process;
4 Water quality analysis items should meet the requirements of Appendix A of this code, and water quality analysis errors should meet the requirements of Appendix B of this code.
3.1.4 The quality of makeup water shall be designed based on the average value of water quality analysis data, and the most unfavorable water quality is used to check the equipment capacity.
3.1.5 The control conditions and indexes of the recirculating cooling water heat exchange equipment of indirect open cooling system shall meet the following requirements:
1 The flow rate of recirculating cooling water tube side shall be greater than 1.0m/s;
2 The flow rate of recirculating cooling water shell side shall be greater than 0.3m/s;
3 The side wall temperature of cooling water on the heat transfer surface of the equipment should not be higher than 70℃. When the temperature of the heat transfer medium is higher than 115℃, the recirculating cooling water should be used for cooling after heat recovery measures are taken.
4 The water-side fouling resistance of the heat transfer surface of the equipment shall not be greater than 3.44×10-4 m2·K/W;
5 The water-side adhesion rate of the heat transfer surface of the equipment shall not be greater than 15mg/(cm2·month), which shall not be greater than 20mg/(cm2·month) in the oil refining industry;
6 The water-side corrosion rate of the heat transfer surface of carbon steel equipment shall be less than 0.075mm/a, and that of copper alloy and stainless steel equipment shall be less than 0.005 mm/a.
1 General provisions
2 Terms and symbols
2.1 Terms
2.2 Symbols
3 Recirculating cooling water treatment
3.1 General requirements
3.2 System design
3.3 Scale and corrosion inhibition
3.4 Sedimentation and filtration
3.5 Biological control
3.6 Cleaning and prefilming
4 Side stream treatment
5 Makeup water treatment
6 Reclaimed water treatment
6.1 General requirements
6.2 Treatment process
7 Blowdown treatment
8 Storage and dosing of chemicals
8.1 General requirements
8.2 Storage and dosing of acid and alkali
8.3 Dosing of scale and corrosion inhibition chemicals
8.4 Storage and dosing of biocide
9 Monitoring, control and analysis
Appendix A Data sheet of water quality analysis
Appendix B Verification of water quality analysis data
Appendix C Curves of pH and total alkalinity of recirculating cooling water
Explanation of wording in this code
List of quoted standards
