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.
Pursuant to the requirements of Notice of the National Energy Administration on issuing the plan 2014 for development (revision) of the first batch of professional standards in energy sector (NEA S&T [2014] No.298), the code development group has prepared this Code through extensive investigation, careful conclusion from indirect dry cooling system design experience, and wide consultation.
The main technical contents of this Code are as follows: general provisions, terms, basic requirements, meteorological parameter selection requirements of indirect dry cooling system, general layout of indirect dry cooling system, design parameter selection and calculation of indirect dry cooling system, indirect dry cooling process system and equipment, indirect dry cooling tower structure, operation and control requirements of indirect dry cooling system and test requirements of indirect dry cooling system.
Code for design of indirect dry cooling system for fossil-fired power plant
1 General provisions
1.0.1 This Code is formulated in order to make the design of indirect dry cooling system of fossil-fired power plant meet the requirements for safety, reliability, advanced technology, economy, rationality and environmental protection.
1.0.2 This Code is applicable to the design of indirect dry cooling system of fossil-fired power plants with single unit capacity of 125MW~1,000MW in newly built, renovated and expanded engineerings.
1.0.3 The design of indirect dry cooling system of fossil-fired power plants shall actively adopt advanced technologies, processes, equipment and materials proved by operation practice or industrial test.
1.0.4 The design life of indirect dry cooling process system shall be 30 years, and the design service life of the structure of indirect dry cooling tower shall be 50 years.
1.0.5 The design identification system of indirect dry cooling system shall be consistent with the identification system of the main work of fossil-fired power plant.
1.0.6 In addition to this Code, the design of indirect dry cooling system of fossil-fired power plant shall also comply with those specified in the current relevant standards of the nation.
2 Terms
2.0.1
indirect dry cooling system
cooling system indirectly exchanging the exhaust heat of steam turbine with air using air as the final cooling medium and circulating cooling water as the intermediate heat exchange medium, including indirect dry cooling system with surface condenser and indirect dry cooling system with jet condenser
2.0.2
indirect dry cooling system with surface condenser
indirect dry cooling system with the heat exchange between exhaust steam of steam turbine and circulating cooling water taking place in surface condenser
2.0.3
indirect dry cooling system with jet condenser
indirect dry cooling system with the heat exchange between exhaust steam of steam turbine and circulating cooling water taking place in mixing condenser
2.0.4
cooling column
column consisting of several groups of tube bundles and tube sheet cooling elements, with both ends connected with water chambers
2.0.5
louver
device for adjusting the air input of an dry cooling radiator, which consists of a frame and louver blades
2.0.6
cooling delta
triangular cooling unit composed of two cooling columns with the same length and a group of louvers with the same length
2.0.7
cooling sector
functional unit composed of several adjacent cooling deltas, with each operating under the control of a set of inlet valve, outlet valve, vent valve and exhaust device
2.0.8
initial temperature difference (ITD)
difference between indirect dry cooling radiator cooling water inlet temperature and radiator inlet air temperature
2.0.9
single flow pass
circulating cooling water entering from one end of the cooling column and directly flowing out from the other end of the cooling column without changing its direction
2.0.10
double flow pass
circulating cooling water flowing in from one half-side finned tube at one end of the cooling column and turning back to the other half-side finned tube through the water chamber at the other end of the cooling column, and flowing out from the same end of the cooling column as flowing in, with the water flow direction in the finned tube by which the circulating cooling water flows in opposite to that in the finned tube by which the circulating cooling water flows out
2.0.11
natural draught indirect dry cooling tower
facility cooling circulating cooling water in an dry cooling radiator by natural convection of air formed by air density difference between inside and outside the cooling tower
2.0.12
mechanical draught indirect dry cooling tower
facility cooling circulating cooling water in an dry cooling radiator by forced convection of air formed by a fan
2.0.13
indirect dry cooling tower with flue gas discharge
natural draught indirect dry cooling tower with flue gas discharge function as a chimney
2.0.14
widening platform
closed structure between the top of the cooling delta and the indirect dry cooling tower body when the cooling deltas are vertically arranged around the tower
2.0.15
design ambient wind velocity
average velocity of undisturbed ambient air for a period of 10min at an elevation 10m above the zero-meter ground outside the dry cooling tower
3 Basic requirements
3.0.1 Indirect dry cooling system should adopt natural draught indirect dry cooling tower and, if it is limited by the following conditions and it is verified by technical and economic comparison, may adopt mechanical draught indirect dry cooling tower:
1 It is difficult to arrange natural draught indirect dry cooling tower because of the limited land occupation of the plant site;
2 The temperature is low in winter or it is difficult to prevent freeze for heating unit by adopting natural draught indirect dry cooling tower.
3.0.2 The selection of indirect dry cooling system with surface condenser and indirect dry cooling system with jet condenser shall be determined by technical and economic comparison, comprehensively taking into account factors such as condenser terminal difference, control of circulating cooling water and condensate water quality, system power consumption, design and manufacturing level of mixing condenser and pressure regulating hydraulic turbine.
3.0.3 The exhaust steam cooling facility of steam turbine for auxiliary engine drive should be combined with main engine cooling facilities.
3.0.4 Special anti-freezing measures shall be taken when indirect dry cooling system is adopted in areas where the average temperature in the coldest month is less than or equal to -10℃; reasonable allocation scale and design measures for summer should be adopted if the indirect dry cooling system is used in areas with high temperature in summer; measures to prevent strong winds should be taken if the indirect dry cooling system is used in areas with high ambient wind velocity; the design of strengthening radiator cleaning system should be adopted if the indirect dry cooling system is used in areas with poor ambient air quality, including areas with more floating objects or dust in the air.
3.0.5 For units with single unit capacity of 600MW or above, each unit should be equipped with one natural draught indirect dry cooling tower.
3.0.6 The automation level of indirect dry cooling system shall be consistent with that of unit.
3.0.7 The indirect dry cooling system shall be brought under the monitoring and control of decentralized control system (DCS) of unit.
4 Meteorological parameter selection requirements of indirect dry cooling system
4.0.1 The meteorological data required for the design and design depth of indirect dry cooling system shall meet the relevant requirements of the current professional standard DL/T 5507 Regulation for basic data and depth of the hydraulic design for fossil-fired power plant.
4.0.2 The design air temperature of indirect dry cooling system shall be determined according to the meteorological data of the typical year of the reference meteorological station, and the selection of the typical year shall meet the relevant requirements of the current professional standard DL/T 5158 Technical code for meteorological survey in electric power engineering.
4.0.3 The statistics of accumulated hours of air temperature in typical years shall be arranged in descending order of air temperature from high to low, with the air temperature grading not greater than 2℃. The statistical table of accumulated hours of air temperature in typical years shall include the corresponding hours, accumulated hours and cumulative frequency of air temperatures at all grades.
4.0.4 The ambient wind data of indirect dry cooling system should meet the following requirements:
1 Statistical analysis of wind frequency, average wind velocity and maximum wind velocity of each wind direction in the whole year, every season and every month in recent 10 years;
2 Statistical analysis of the occurrence number, frequency and average wind velocity of each wind direction with wind velocity greater than 3m/s in the whole year and summer in recent 10 years;
3 Statistical analysis of the occurrence number, frequency and average wind velocity of each wind direction in recent 10 years when the ambient air temperature is greater than or equal to 26.0℃ and the average wind velocity for a period of 10min is greater than or equal to 4m/s and 5m/s.
4.0.5 If the altitude of the plant site is inconsistent with that of the meteorological station, the ambient air temperature and atmospheric pressure shall be corrected.
4.0.6 When designing the indirect dry cooling system, the representativeness of the selected reference meteorological station to the plant site shall be analyzed and demonstrated. If the representativeness of the reference meteorological station data to the plant site area cannot be analyzed accurately, an dry cooling meteorological observation station shall be set up in the plant site area for comparative analysis. The relevant technical requirements of the dry cooling meteorological observation station at the plant site shall meet those specified in the current professional standard DL/T 5158 Technical code for meteorological survey in electric power engineering.
4.0.7 For the design of indirect dry cooling system, the temperature inversion distribution data of the plant site area should be collected, and the relevant technical requirements should meet those specified in the current professional standard DL/T 5158 Technical code for meteorological survey in electric power engineering.
4.0.8 For the design of indirect dry cooling system, the ambient air quality near the plant site shall be subjected to the following analysis:
1 In areas with frequent sandstorms, analytic statistics shall be carried out for the season with frequent sandstorms, the longest duration of a sandstorm, the intensity of sandstorms, the dominant wind direction and the maximum wind velocity;
2 It is advisable to analyze the dirty environmental conditions such as dust and plant flocs that may affect the performance of indirect dry cooling radiator.
5 General layout of indirect dry cooling system
5.0.1 The position of indirect dry cooling tower relative to surrounding buildings shall meet the following requirements:
1 It should not be on the downwind side of the summer prevailing wind direction of the direct dry cooling platform;
2 It should not be on the downwind side of the winter prevailing wind direction of the mechanical draught wet cooling tower;
3 It should not be on the downwind side of the whole-year prevailing wind direction of the dust source;
4 It should be far away from the outdoor heat source, and should not be on the downwind side of the summer prevailing wind direction of the outdoor heat source.
5.0.2 If the radiators are horizontally arranged in the tower, the clear distance between the towers shall be calculated according to the distance between the centers of the tower pillars corresponding to the zero-meter elevation; if radiators are vertically arranged around towers, the clear distance between towers shall be calculated according to the distance between the outermost edges of radiators.
5.0.3 The clear distance between adjacent indirect dry cooling towers shall meet the following requirements:
1 For the towers with the radiators arranged horizontally inside, the clear distance between the towers should not be less than 4 times the height of the larger air inlet, and shall not be less than 0.5 times the diameter of the tower pillar center of the larger natural draught indirect dry cooling tower at zero meter;
2 For the towers with the radiators arranged vertically around them, the clear distance between the towers should not be less than 3 times the height of the higher radiator, and shall not be less than 0.5 times the diameter of the pillar center of the natural draught indirect dry cooling tower at zero meter;
3 The clear distance between the mechanical draught indirect dry cooling tower and the natural draught indirect dry cooling tower shall meet the following requirements:
1) If the radiators of the mechanical draught indirect dry cooling tower and the natural draught indirect dry cooling tower are vertically arranged, the clear distance between towers should not be less than 1.5 times of the sum of the heights of radiators of the two towers;
2) If the radiators of mechanical draught indirect dry cooling tower are arranged vertically and those of natural draught indirect dry cooling tower are arranged horizontally, the clear distance between towers should not be less than the sum of 1.5 times the height of radiator of mechanical draught indirect dry cooling tower and 2 times the height of air inlet of natural draught indirect dry cooling tower;
3) If the radiators of mechanical draught indirect dry cooling tower are arranged horizontally and those of natural draught indirect dry cooling tower are arranged vertically, the clear distance between towers should not be less than the sum of 2 times the height of air inlet of mechanical draught indirect dry cooling tower and 1.5 times the height of radiator of natural draught indirect dry cooling tower;
4) If the radiators of the mechanical draught indirect dry cooling tower and the natural draught indirect dry cooling tower are horizontally arranged, the clear distance between towers should not be less than 2 times of the sum of the heights of air inlets of the two towers.
5.0.4 The minimum clear distance between the indirect dry cooling tower and its surrounding buildings (structures) may be determined using the following equation:
Lmin≥0.4H＋h (5.0.4)
where,
Lmin——the minimum clear distance between the indirect dry cooling tower and its surrounding buildings (structures), m;
H——the effective height of the outermost air inlet surface of the indirect dry cooling tower, m;
h——the effective wind resistance height of buildings (structures) around the indirect dry cooling tower, m.
For particularly tall obstacles near the cooling tower, special research shall be conducted to evaluate their adverse effects on the thermal performance of the cooling tower.
5.0.5 If the location of the plant site has height limit requirements for the chimney, or it is proved that it is better in terms of the aspects of technique and economy to adopt the indirect dry cooling tower with flue gas discharge, the indirect dry cooling tower with flue gas discharge may be adopted after it is approved upon the environmental impact assessment.
5.0.6 If the zero-meter elevation difference between the indirect dry cooling towers of two units is greater than 2m, the unit system should be adopted.
5.0.7 The position of indirect dry cooling tower should not be at the lower point of circulating cooling water system.
5.0.8 Facilities that do not affect the heat dissipation performance and safe operation of the indirect dry cooling tower may be set in the indirect dry cooling tower in combination with the requirements of relevant process system layout and general layout.
5.0.9 If facilities with fire protection requirements are placed in the indirect dry cooling tower, fire fighting access and supporting fire fighting facilities shall be set according to the requirements of the current national standard GB 50229 Code for design of fire protection for fossil fuel power plants and substations.
5.0.10 The geometric dimension of the indirect dry cooling tower tube shall meet the thermal performance requirements of the indirect dry cooling tower and shall be determined through technical and economic comparisons in combination with factors such as reasonable structure and convenient construction. If a hyperbolic reinforced concrete tower tube is used, the geometric dimension of indirect dry cooling tower tube should be determined according to Table 5.0.10.
Table 5.0.10 Recommended geometric dimensions of shell of hyperbolic indirect dry cooling tower tube
Ratio of tower height to tower bottom (±0.00m) diameter Ratio of throat area to shell bottom area Ratio of throat height to tower height Diffusion angle at tower top
αt Meridian inclination of shell bottom
αD
1.00~1.50 0.40~0.60 0.75~0.85 3°~6° 14°~17°
5.0.11 The flue of natural draught indirect dry cooling tower with flue gas discharge should be arranged between two adjacent cooling sectors, and should be set in combination with the gate of indirect dry cooling tower.
5.0.12 The circulating water pump room of indirect dry cooling system with surface condenser should be arranged close to the indirect dry cooling tower, which may be built separately or jointly according to the number of units; the circulating water pump set of indirect dry cooling system with jet condenser should be arranged close to the steam condenser.
5.0.13 The electronic equipment room should be arranged near the indirect dry cooling tower or main equipment for the indirect dry cooling system.
6 Design parameter selection and calculation of indirect dry cooling system
6.1 General requirements
6.1.1 Each design condition of indirect dry cooling system shall correspond to each design condition of dry cooling steam turbine, and the design and calculation parameters shall be selected based on the parameters of corresponding working conditions of dry cooling steam turbine.
6.1.2 The design conditions of indirect dry cooling system should meet the requirements of back pressure and rating in maximum continue rating working condition of dry cooling steam turbine under the condition of design air temperature. For dry cooling units with the rating in maximum continue rating working condition as the unit plate rating, the calculated back pressure and rating in summer shall be checked according to the calculated air temperature in summer; for dry cooling units with the plate rating determined in accordance with the current national standard GB/T 5578 Fixed power plant turbine specifications, the requirements of back pressure and rating in plate rating working condition of dry cooling steam turbine under the condition of calculated air temperature in summer shall be met.
6.2 Design parameter selection of indirect dry cooling system
6.2.1 The design air temperature shall be calculated based on the hourly dry-bulb temperature of a typical year, and should be determined based on the annual weighted-average of air temperatures above 5℃, and temperatures below 5℃, if any, shall be regarded as 5℃.
6.2.2 The calculated air temperature in summer shall be reasonably determined according to the electric load requirements and characteristics of the generator set in summer, which may be selected from the hourly dry-bulb temperature statistics table of a typical year from the highest to the lowest corresponding ambient temperature for a cumulative period of not more than 200h.
6.2.3 The design ambient wind velocity shall be determined based on the statistical data of the reference meteorological station or the dry cooling meteorological observation station at the plant site, and the design ambient wind velocity should not be less than the maximum monthly average velocity.
6.2.4 The design atmospheric pressure and atmospheric pressure in summer should be determined based on the statistical data of the reference meteorological station or the dry cooling meteorological observation station at the plant site, and the former should be the average atmospheric pressure over the years, while the latter should be the average atmospheric pressure of the hottest month over the years.
6.2.5 The design relative humidity and the relative humidity in summer should be determined based on the statistical data of the reference meteorological station or the dry cooling meteorological observation station at the plant site, and the former should be average relative humidity over the years, while the latter should be the average relative humidity of the hottest month over the years.
6.2.6 The initial temperature difference shall be determined by technical and economic comparison and optimization calculation based on meteorological conditions, main engine selection, plant site layout and other conditions. The design initial temperature difference should be selected within the range of 25℃~35℃.
6.2.7 For power plants equipped with a condensation water refine treatment system, the saturated steam temperature corresponding to the calculated back pressure in summer shall match with the temperature resistance of the anion exchange resin of the condensation water refine treatment system.
6.3 Calculation of indirect dry cooling system
6.3.1 The thermodynamic calculation of the indirect dry cooling system shall meet the following requirements:
1 The heat exchange capacity of the indirect dry cooling radiator shall be calculated using the following equation:
Q1=K×S×Ft×tm (6.3.1-1)
(6.3.1-2)
(6.3.1-3)
t1=ts-(TTD)c (6.3.1-4)
t2=t1-t (6.3.1-5)
(6.3.1-6)
where,
Q1——the heat exchange capacity of indirect dry cooling radiator, W;
K——the total heat transfer coefficient, which is related to the water-side flow velocity and air-side wind velocity of the radiator, with the relational expression provided by the manufacturer or determined by test, [W/(m2·℃)];
S——the heat transfer area of the radiator, m2;
Ft——the correction factor of non-countercurrent heat transfer;
△tm——the average temperature difference of heat transfer, ℃;
ma——the face velocity of mass through radiator, [kg/(s·m2)];
v——the flow velocity at the water side of the radiator, m/s;
μ——the dynamic viscosity of air, Pa·s;
ts——the saturated steam temperature corresponding to the exhaust steam pressure of steam turbine, ℃;
t1——the inlet water temperature of radiator, ℃;
t2——the outlet water temperature of radiator, ℃;
∆t——the inlet and outlet temperature difference of circulating cooling water, ℃;
θ1——the air temperature at the inlet of the radiator, i.e., the ambient dry-bulb temperature, ℃;
θ2——the air temperature at the outlet of radiator, ℃;
(TTD)c——the steam condenser terminal difference, ℃;
Qk——the heat exhaust of the steam condenser, W;
W——the flow rate of circulating cooling water, kg/s;
cpw——the specific heat capacity of water, 4187[J/(kg·℃)].
2 The heat exhaust of the steam condenser shall be calculated using the following equation:
Qk=Dk(hk-hc)+∑Dki(hki-hci)+Qs (6.3.1-7)
where,
Qk——the heat exhaust of the steam condenser, W;
Dk——the exhaust volume of the steam turbine for main engine, kg/s;
hk——the exhaust enthalpy of the steam turbine for main engine, J/kg;
hc——the enthalpy of condensation water of main engine, J/kg;
Dki——the exhaust volume of steam turbine for each auxiliary engine, kg/s;
hki——the exhaust enthalpy of steam turbine for each auxiliary engine, J/kg;
hci——the enthalpy of condensation water of each auxiliary engine (j/kg);
Qs——the exhaust volume of the drainage, W.
3 The heat absorption of ambient air shall be calculated using the following equation:
Q2=∆θ×ma×Sn×cpa (6.3.1-8)
where,
Q2——the heat absorption of ambient air, W;
∆θ——the temperature rise of the air, ℃;
Sn——the windward area of the radiator, m2;
cpa——the specific heat of air at constant pressure, [J/(kg·℃)];
6.3.2 The suction force generated by the effective height of the air duct of a natural draught indirect dry cooling tower should be calculated using the following equation:
ND=He×g×(ρ1-ρ2) (6.3.2)
where,
ND——the suction force generated due to the effective height of the air duct of indirect dry cooling tower, Pa;
He——the effective draft height of the indirect dry cooling tower, which should be the height difference from the middle of the radiator to the top of the tower if the radiator is arranged vertically, or the height difference between the average value of the top of the radiator and the top of the tower if the radiator is arranged horizontally, m;
g——the gravitational acceleration, m/s2;
ρ1——the density of cold air outside the indirect dry cooling tower, kg/m3.
ρ2——the density of hot air inside the indirect dry cooling tower, kg/m3.
6.3.3 The ventilation resistance at each part of the natural draught indirect dry cooling tower shall be calculated in accordance with the following requirements:
1 The measured data of prototype towers identical or similar to the designed indirect dry cooling tower shall be adopted;
2 If the measured data mentioned above are not available, it may be calculated using the empirical methods specified in 6.3.4 and 6.3.5 of this Code.
6.3.4 The ventilation resistance of natural draught indirect dry cooling tower may be calculated using the following empirical methods:
1 The ventilation resistance of the louver may be calculated using the following equation:
(6.3.4-1)
where,
∆Pb——the ventilation resistance of the louver, Pa;
Cb——the coefficient, which is obtained by test;
m——the exponent, which is obtained by test;
vb——the face velocity of air flow passing through the louver, m/s.
2 The resistance at the inlet of the radiator may be calculated using the following equation:
(6.3.4-2)
Khi=51.601-1.335α+0.0094α2 (6.3.4-3)
where,
∆Phi——the resistance at the inlet of the radiator, Pa;
Khi——the resistance coefficient of the triangle inlet of the radiator;
vh——the air velocity through the windward side of the radiator, m/s;
α——the vertex angle of the cooling delta, 40º≤α≤70º, º.
3 The resistance at the outlet of the radiator may be calculated using the following equation:
(6.3.4-4)
Kho=14.015-0.2929α+0.0017α2 (6.3.4-5)
where,
∆Pho——the resistance at the outlet of the radiator, Pa;
Kho——the resistance coefficient of the triangle outlet of the radiator;
4 The resistance of the radiator may be calculated using the following equation:
(6.3.4-6)
where,
∆Ph——the resistance of air flow passing through the radiator, Pa;
Ch——the coefficient, which is obtained by test;
n——the exponent, which is obtained by test;
5 The resistance of the air flow passing through the tower pillar may be calculated using the following equation:
(6.3.4-7)
(6.3.4-8)
(6.3.4-9)
where,
∆Pd——the resistance of the air flow through tower pillar, Pa;
Cd——the resistance coefficient of tower pillar, which may be selected from those specified in Table 6.3.4-1;
ρ——the density of air flow passing through the section, kg/m3;
vd——the face velocity upstream of the tower pillar, m/s;
Ad——the total cross-sectional area of air inlet column, m2;
A——the total area of air inlet, m2;
b——the width of the tower pillar parallel to the direction of air flow, m;
d——the width of the tower pillar facing the direction of air flow, m;
Re——the Reynolds number (103
Foreword ii
1 General provisions
2 Terms
3 Basic requirements
4 Meteorological parameter selection requirements of indirect dry cooling system
5 General layout of indirect dry cooling system
6 Design parameter selection and calculation of indirect dry cooling system
6.1 General requirements
6.2 Design parameter selection of indirect dry cooling system
6.3 Calculation of indirect dry cooling system
6.4 Design margin of indirect dry cooling system
7 Indirect dry cooling process system and equipment
7.1 Indirect dry cooling radiator system
7.2 Steam condenser
7.3 Circulating water pump and piping system
7.4 Expansion water tank system
7.5 Underground water storage tank and water filling and drainage system
7.6 Radiator cleaning system
7.7 Water quality control of circulating water system
7.8 Condensation water refine treatment system
7.9 Testing and instrumentation, alarm
7.10 Insulation, painting and heat tracing
8 Indirect dry cooling tower structure
8.1 General requirements
8.2 Main structure of indirect dry cooling tower
8.3 Widening platform
8.4 Tower core structure of horizontal radiator arrangement
8.5 Accessory structure
9 Operation and control requirements of indirect dry cooling system
9.1 Startup and shutdown
9.2 Normal operation
9.3 Winter operation
9.4 Summer operation
10 Test requirements of indirect dry cooling system
10.1 Mathematical and physical model test of indirect dry cooling system
10.2 Performance test of indirect dry cooling system
Annex A Aerodynamic calculation resistance coefficient and correction factor of mechanical draught indirect dry cooling tower
Annex B Water resistance and correction factor of cooling radiator bundle
Explanation of wording in this code
List of quoted codes
Explanation of provisions
1 总则
1.0.1 为了使火力发电厂间接空冷系统设计安全可靠、技术先进、经济合理，并满足环境保护的要求，制定本标准。
1.0.2 本标准适用于新建、改扩建工程单机容量为125MW～1000MW级的火力发电厂间接空冷系统的设计。
1.0.3 火力发电厂间接空冷系统设计应积极采用经运行实践或工业试验证明的先进技术、工艺、设备和材料。
1.0.4 间接空冷工艺系统的设计寿命应为30年，间接空冷塔的结构设计使用年限应为50年。
1.0.5 间接空冷系统的设计标识系统应与火力发电厂主体工程的标识系统一致。
1.0.6 火力发电厂间接空冷系统的设计除应符合本标准的规定外，还应符合国家现行有关标准的规定。
2 术语
2.0.1 间接空冷系统 indirect dry cooling system
以空气作为最终冷却介质，利用循环冷却水作为中间换热介质，将汽轮机的排汽热量间接和空气进行热交换的冷却系统，包括表面式凝汽器间接空冷系统和混合式凝汽器间接空冷系统。
2.0.2 表面式凝汽器间接空冷系统 indirect dry cooling sys-tem with surface condenser
汽轮机的排汽与循环冷却水之间在表面式凝汽器中换热的间接空冷系统。
2.0.3 混合式凝汽器间接空冷系统 indirect dry cooling sys-tem with jet condenser
汽轮机的排汽与循环冷却水之间在混合式凝汽器中换热的间接空冷系统，又称喷射式凝汽器的间接空冷系统。
2.0.4 冷却柱 cooling column
由若干组管束、管板冷却元件组成，冷却柱两端各有水室相连。
2.0.5 百叶窗 louver
调节空冷散热器进风量的装置，由框架及窗叶组成。
2.0.6 冷却三角 cooling delta
由两片长度相同的冷却柱和一组同长度的百叶窗组成三角形的冷却单元。
2.0.7 冷却扇段 cooling sector
由若干相邻的冷却三角组成的一个功能单元，称为冷却扇段。每个冷却扇段由一组进水阀、出水阀、放空阀、排气装置等控制运行。
2.0.8 初始温差 initial temperature difference (ITD)
间接空冷散热器冷却水进口温度与散热器入口空气温度的差值。
2.0.9 单流程 single flow pass
循环冷却水从冷却柱一端进入，不改变方向直接从冷却柱的另一端流出。
2.0.10 双流程 double flow pass
循环冷却水从冷却柱一端的半侧翅片管流入，在冷却柱另一端通过水室折返到另半侧翅片管后流出，进水和出水在冷却柱同一端，流入翅片管和流出翅片管内的水流方向相反。
2.0.11 自然通风间接空冷塔 natural draught indirect dry cooling tower
利用冷却塔内外空气密度差形成的空气自然对流作用冷却空冷散热器内循环冷却水的设施。
2.0.12 机械通风间接空冷塔 mechanical draught indirect dry cooling tower
利用风机形成的空气强制对流作用冷却空冷散热器内循环冷却水的设施。
2.0.13 排烟间接空冷塔 indirect dry cooling tower with flue gas discharge
兼有烟囱排放烟气功能的自然通风间接空冷塔。
2.0.14 展宽平台 widening platform
冷却三角在塔周垂直布置时，冷却三角顶部与间接空冷塔塔体之间的封闭结构。
2.0.15 设计环境风速 design ambient wind velocity
在空冷塔外零米地面以上10m标高处未扰动环境空气的10min平均流速。
3 基本规定
3.0.1 间接空冷系统宜采用自然通风间接空冷塔，当有以下条件限制且经技术经济比较论证，可采用机械通风间接空冷塔：
1 厂址占地受限，布置自然通风间接空冷塔有困难；
2 冬季气温低或供热机组采用自然通风间接空冷塔防冻困难。
3.0.2 表面式凝汽器间接空冷系统和混合式凝汽器间接空冷系统的选择应综合凝汽器端差、循环冷却水和凝结水水质控制、系统耗电量以及混合式凝汽器和调压水轮机的设计制造水平等因素，经技术经济比较论证确定。
3.0.3 辅机驱动用汽轮机的排汽冷却设施宜与主机冷却设施合并设置。
3.0.4 在最冷月平均气温小于或等于－10℃的地区采用间接空冷系统时，应采取特殊的防冻措施；在夏季气温较高地区使用时，宜采取合理的配置规模和度夏设计措施；在高环境风速地区使用时，宜采取防大风措施；在环境空气质量较差地区，包括空气中飘浮物或沙尘较多地区使用时，宜采用加强散热器清洗系统的设计。
3.0.5 对于单机容量为600MW级及以上机组，每台机组宜配置1座自然通风间接空冷塔。
3.0.6 间接空冷系统的自动化水平应与单元机组的自动化水平相一致。
3.0.7 间接空冷系统应纳入单元机组分散控制系统(DCS)监视与控制。
4 间接空冷系统气象参数选择要求
4.0.1 间接空冷系统设计所需的气象资料和深度应符合现行行业标准《火力发电厂水工设计基础资料及其深度规定》DL／T 5507的有关要求。
4.0.2 间接空冷系统设计气温应按参证气象站典型年的气象资料确定，典型年的选择应符合现行行业标准《电力工程气象勘测技术规程》DL／T 5158的有关要求。
4.0.3 典型年气温累积小时数统计应按气温由高到低递减顺序排列，气温分级不宜大于2℃。典型年气温累积小时数统计表内容应包括各级气温对应出现的小时数、累计出现小时数、累积频率等统计资料。
4.0.4 间接空冷系统环境风资料宜符合下列规定：
1 统计分析最近10年全年、各季和逐月的各风向风频、平均风速、最大风速；
2 统计分析最近10年全年和夏季的风速大于3m／s的各风向出现次数、风频、平均风速；
3 统计分析最近10年当环境气温大于或等于26.0℃，且10min平均风速大于或等于4m／s及5m／s同时出现的各风向出现次数、风频、平均风速。
4.0.5 当厂址与气象站海拔高度不一致时，应对环境气温和大气压力进行修正。
4.0.6 间接空冷系统设计时应分析论证所选参证气象站对厂址的代表性，不能确切分析参证气象站资料对厂址区域的代表性时，应在厂址区域设立空冷气象观测站进行对比分析。厂址空冷气象观测站的相关技术要求应满足现行行业标准《电力工程气象勘测技术规程》DL／T 5158的规定。
4.0.7 间接空冷系统设计宜收集厂址区域的逆温分布资料，相关技术要求宜满足现行行业标准《电力工程气象勘测技术规程》DL／T 5158的规定。
4.0.8 间接空冷系统设计应对厂址附近的环境空气质量进行以下分析：
1 在沙尘暴频发地区，应对沙尘暴的频发季节、一次沙尘暴的最长持续时间、沙尘暴强度、主导风向、最大风速等进行分析统计；
2 宜对可能影响间接空冷散热器性能的粉尘、植物飞絮等脏污环境条件进行分析。
5 间接空冷系统总体布置
5.0.1 间接空冷塔与周围建筑物相对位置应符合下列要求：
1 不宜布置在直接空冷平台夏季主导风向下风侧；
2 不宜布置在机械通风湿冷塔的冬季主导风向的下风侧；
3 不宜布置在粉尘源的全年主导风向下风侧；
4 宜远离露天热源，并不宜布置在露天热源夏季主导风向下风侧。
5.0.2 散热器在塔内水平布置时，塔间净距应按零米标高对应塔简支柱中心之间距离计算；散热器在塔周垂直布置时，塔间净距应按散热器最外缘之间距离计算。
5.0.3 相邻间接空冷塔的塔间净距应符合下列规定：
1 散热器塔内水平布置的塔间净距不宜小于4倍较大的进风口高度，且不应小于0.5倍较大的自然通风间接空冷塔塔筒支柱中心零米处直径；
2 散热器塔周垂直布置的塔间净距不宜小于3倍较高的散热器高度，且不应小于0.5倍较大的自然通风间接空冷塔塔筒支柱中心零米处直径；
3 机械通风间接空冷塔与自然通风间接空冷塔的塔间净距宜符合下列规定：
1)机械通风间接空冷塔和自然通风间接空冷塔散热器垂直布置时，塔间净距不宜小于两塔散热器高度之和的1.5倍；
2)机械通风间接空冷塔散热器垂直布置、自然通风间接空冷塔散热器水平布置时，塔间净距不宜小于机械通风间接空冷塔散热器高度的1.5倍与自然通风间接空冷塔进风口高度2倍之和；
3)机械通风间接空冷塔散热器水平布置、自然通风间接空冷塔散热器垂直布置时，塔间净距不宜小于机械通风间接空冷塔进风口高度的2倍与自然通风间接空冷塔散热器高度1.5倍之和；
4)机械通风间接空冷塔和自然通风间接空冷塔散热器水平布置时，塔间净距不宜小于两塔进风口高度之和的2倍。
5.0.4 间接空冷塔与周围建(构)筑物之间的最小净距可按下式确定：
Lmin≥0.4H＋h (5.0.4)
式中：Lmin——间接空冷塔与周围建(构)筑物之间的最小净距(m)；
H——间接空冷塔最外围进风面有效高度(m)；
h——间接空冷塔周围建(构)筑物有效阻风高度(m)。
对于靠近冷却塔的特别高大的障碍物，应通过专项研究评估其对冷却塔热力性能的不利影响。
5.0.5 当厂址所在地对烟囱有限高要求或经论证采用排烟间接空冷塔技术经济更优时，经环境影响评价达标后可采用排烟间接空冷塔。
5.0.6 当两台机组的间接空冷塔零米标高差大于2m时，宜采用单元制。
5.0.7 间接空冷塔的位置不宜布置在循环冷却水系统较低点。
5.0.8 不影响间接空冷塔散热性能和安全运行的设施，可结合相关工艺系统布置及总平面布置的要求设置于间接空冷塔内。
5.0.9 当间接空冷塔内放置有防火要求的设施时，应根据现行国家标准《火力发电厂与变电站设计防火规范》GB 50229的要求设置消防通道及配套的消防设施。
5.0.10 间接空冷塔塔筒的几何尺寸应满足间接空冷塔的热力性能要求，并应结合结构合理、施工方便等因素通过技术经济比较确定。当采用双曲线型钢筋混凝土塔筒时，间接空冷塔塔筒的几何尺寸宜按表5.0.10的规定取值。
表5.0.10 双曲线型间接空冷塔塔筒壳体推荐几何尺寸表
塔高与塔底(±0.00m)直径的比 喉部面积与壳底面积的比 喉部高度与塔高的比 塔顶扩散角
αt 壳底子午线倾角
αD
1.00～1.50 0.40～0.60 0.75～0.85 3°～6° 14°～17°
5.0.11 自然通风排烟间接空冷塔烟道宜设在相邻两个冷却扇段之间，宜与间接空冷塔大门结合设置。
5.0.12 表面式凝汽器间接空冷系统循环水泵房宜靠近间接空冷塔布置，可根据机组台数分建或合建；混合式凝汽器间接空冷系统循环水泵组宜靠近凝汽器布置。
5.0.13 间接空冷系统宜在间接空冷塔或主设备附近设置电子设备间。
6 间接空冷系统设计参数选择和计算
6.1 一般规定
6.1.1 间接空冷系统各设计工况应与空冷汽轮机各设计工况相对应，设计和计算参数选择应以空冷汽轮机对应工况的参数为依据。
6.1.2 间接空冷系统的设计工况宜在设计气温条件下，达到空冷汽轮机最大连续出力工况背压和出力的要求。以最大连续出力工况出力作为机组铭牌出力的空冷机组，应根据夏季计算气温校核夏季计算背压和夏季出力；以现行国家标准《固定式发电用汽轮机规范》GB／T 5578确定铭牌出力的空冷机组，应在夏季计算气温条件下，达到空冷汽轮机铭牌出力工况背压和出力的要求。
6.2 间接空冷系统设计参数选择
6.2.1 设计气温应根据典型年的小时-干球温度统计，宜按5℃以上年加权平均法确定设计气温，5℃以下按照5℃计算。
6.2.2 夏季计算气温应根据发电机组夏季电力负荷需求和特点合理确定，可选取典型年的小时干球温度统计表由高至低取累计不大于200h对应的环境气温。
6.2.3 设计环境风速应根据厂址参证气象站或厂址空冷气象观测站统计资料确定，设计环境风速不宜小于最大月平均风速。
6.2.4 设计大气压力和夏季大气压力宜根据厂址参证气象站或厂址空冷气象观测站统计资料确定，设计大气压力宜采用多年平均大气压力，夏季大气压力宜采用多年最热月平均大气压力。
6.2.5 设计相对湿度和夏季相对湿度宜根据厂址参证气象站或厂址空冷气象观测站统计资料确定，设计相对湿度宜采用多年平均相对湿度，夏季相对湿度宜采用多年最热月平均相对湿度。
6.2.6 初始温差应根据气象条件、主机选型、厂址布置等条件通过技术经济比较优化计算确定。设计初始温差值宜在25℃～35℃范围内选择。
6.2.7 对设有凝结水精处理系统的电厂，夏季计算背压对应的饱和蒸汽温度应与凝结水精处理系统阴离子交换树脂的耐温程度相匹配。
6.3 间接空冷系统计算
6.3.1 间接空冷系统热力计算应符合以下规定：
1 间接空冷散热器的换热量应按下列公式计算：
Q1＝K×S×Ft×tm (6.3.1-1)
(6.3.1-2)
(6.3.1-3)
t1＝ts－(TTD)c (6.3.1-4)
t2＝t1－t (6.3.1-5)
(6.3.1-6)
式中：Q1——间接空冷散热器换热量(W)；
K——总传热系数[W／(m2·℃)]；与散热器水侧流速和空气侧风速有关，关系式由制造厂提供或通过试验给出；
S——散热器传热面积(m2)；
Ft——非逆流换热修正系数；
△tm——传热平均温差(℃)；
ma——通过散热器的迎面质量风速[kg／(s·m2)]；
υ——散热器水侧流速(m／s)；
μ——空气动力黏度(Pa·s)；
ts——对应于汽轮机排汽压力的饱和蒸汽温度(℃)；
t1——散热器进水温度(℃)；
t2——散热器出水温度(℃)；
∆t——循环冷却水进出水温差(℃)；
θ1——散热器入口空气温度，即环境干球温度(℃)；
θ2——散热器出口空气温度(℃)；
(TTD)c——凝汽器端差(℃)；
Qk——凝汽器的排热量(W)；
W——循环冷却水流量(kg／s)；
cpw——水的比热容，4187[J／(kg·℃)]。
2 凝汽器的排热量应按下式计算：
Qk＝Dk(hk－hc)＋∑Dki(hki－hci)＋Qs (6.3.1-7)
式中：Qk——凝汽器的排热量(W)；
Dk——主机汽轮机的排汽量(kg／s)；
hk——主机汽轮机的排汽焓(J／kg)；
hc——主机凝结水的烤(J／kg)；
Dki——各辅机汽轮机的排汽量(kg／s)；
hki——各辅机汽轮机的排汽焓(J／kg)；
hci——各辅机凝结水的焓(J／kg)；
Qs——疏水的排热量(W)。
3 环境空气的吸热量应按下式计算：
Q2＝∆θ×ma×Sn×Cpa (6.3.1-8)
式中：Q2——环境空气的吸热量(W)；
∆θ——空气温升(℃)；
Sn——散热器的迎风面面积(m2)；
cpa——空气定压比热容[J／(kg·℃)]。
6.3.2 自然通风间接空冷塔风筒有效高度产生的抽力宜按下式计算：
ND＝He×g×(ρ1－ρ2) (6.3.2)
式中：ND——间接空冷塔的风筒有效高度产生的抽力(Pa)；
He——间接空冷塔的有效抽风高度(m)；散热器垂直布置时宜采用散热器中部至塔顶的高差，散热器水平布置时宜采用散热器顶部的平均值至塔顶的高差；
g——重力加速度(m／s2)；
ρ1——间接空冷塔外冷空气密度(kg／m3)；
ρ2——间接空冷塔内热空气密度(kg／m3)。
6.3.3 自然通风间接空冷塔各部位通风阻力计算宜符合下列要求：
1 采用与所设计的间接空冷塔相同或相似的原型塔的实测数据；
2 当缺乏上述数据时，可按本规范第6.3.4条和第6.3.5条规定的经验方法计算。
6.3.4 自然通风间接空冷塔通风阻力可按下列经验方法计算：
1 百叶窗通风阻力可按下式计算：
(6.3.4-1)
式中：∆Pb——百叶窗通风阻力(Pa)；
Cb——系数，通过试验获得；
m——指数，通过试验获得；
υb——气流通过百叶窗的迎面风速(m／s)。
2 散热器进口阻力可按下列公式计算：
(6.3.4-2)
Khi＝51.601－1.335α＋0.0094α2 (6.3.4-3)
式中：∆Phi——散热器进口的阻力(Pa)；
Khi——散热器三角形进口阻力系数；
υh——通过散热器迎风面空气流速(m／s)；
α——冷却三角顶角(º)，40º≤α≤70º。
3 散热器出口阻力可按下列公式计算：
(6.3.4-4)
Kho＝14.015－0.2929α＋0.0017α2 (6.3.4-5)
式中：∆Pho——散热器出口阻力(Pa)；
Kho——散热器三角形出口阻力系数。
4 散热器阻力可按下式计算：
(6.3.4-6)
式中：∆Ph——气流通过散热器的阻力(Pa)；
Ch——系数，通过试验获得；
n——指数，通过试验获得。
5 气流通过塔筒支柱阻力可按下列公式计算：
(6.3.4-7)
(6.3.4-8)
(6.3.4-9)
式中：∆Pd——气流经过塔筒支柱阻力(Pa)；
Cd——塔筒支柱阻力系数；Cd可按表6.3.4-1的规定取值；
ρ——通过断面气流的密度(kg／m3)；
υd——塔筒支柱上游迎面风速(m／s)；
Ad——进风口柱体总横断面积(m2)；
A——进风口总面积(m2)；
b——塔筒支柱平行于空气流动方向的宽度(m)；
d——塔筒支柱迎空气流动方向的宽度(m)；
Re——雷诺数(103＜Re＜106)；
μ——通过塔筒支柱气流动力黏度(Pa·s)。
表6.3.4-1 塔筒支柱阻力系数的取值和适用范围表
支柱截面形式 塔筒支柱阻力系数Cd 适用范围
类似于椭圆形 按本标准式(6.3.4-8)计算 103＜Re＜106
圆形 1.2 104＜Re＜2×105
矩形 2 104＜Re＜2×105
6 自然通风间接空冷塔进风口至风筒底部截面之间阻力可按下列公式计算：
(6.3.4-11)
(6.3.4-11)
(6.3.4-12)
式中：∆Pi——空冷塔空气进口转弯向上及收缩阻力(Pa)；
Ki——空冷塔进口转弯向上及收缩阻力系数，可按表6.3.4-2的规定计算；
υe——进风口上缘风筒横截面平均空气流速(m／s)；
Di——进风口上缘塔筒直径(m)；
Hi——进风口高度(m)；
Sc——间接空冷塔有效利用系数，可近似为散热器沿塔周边的有效长度与塔周边长度之比。
表6.3.4-2 空冷塔进口转弯向上及收缩阻力系数计算公式和适用范围表
散热器布置形式 空冷塔进口转弯向上及收缩阻力系数Ki计算公式 适用范围
散热器水平布置 按本标准式(6.3.4-11)计算 ，
0.4≤Sc≤1，
19≤Ch≤50
散热器垂直布置 按本标准式(6.3.4-12)计算 ，
5≤Ch≤40
7 间接空冷塔出口阻力可按下式计算：
(6.3.4-13)
式中：∆Po——空冷塔出口阻力(Pa)；
υo——间接空冷塔出口空气流速(m／s)；
ρo——间接空冷塔出口热空气密度(kg／m3)。
8 空气通过自然通风间接空冷塔总阻力可按下式计算：
TPz＝∆Pb＋∆Phi＋∆Pho＋∆Ph＋∆Pd＋∆Pi＋∆Po (6.3.4-14)
式中：TPz——空气通过自然通风间接空冷塔总阻力(Pa)。
6.3.5 机械通风间接空冷塔通风阻力可按下列经验方法进行计算：
1 机械通风间接空冷塔进风口阻力可按下式计算：
(6.3.5-1)
式中：∆Pdj——机械通风间接空冷塔进风口阻力(Pa)；
υdj——机械通风间接空冷塔进风口断面的空气流速(m／s)。
2 机械通风间接空冷塔气流转弯阻力可按下式计算：
(6.3.5-2)
式中：∆Pz——机械通风间接空冷塔气流转弯阻力(Pa)；
Kz——气流转弯阻力系数，可取0.5。
3 支撑梁阻力可按下列公式计算：
(6.3.5-3)
(6.3.5-4)
式中：∆P1——支撑梁阻力(Pa)；
K1——支撑梁阻力系数；
υ1——通过支撑梁处的空气流速(m／s)；
A1——支撑梁处气流有效面积(m2)；
A0——塔体围护横截面积(m2)。
4 风筒圈梁进口阻力可按下式计算：
(6.3.5-5)
式中：∆Pq——风筒圈梁进口阻力(Pa)；
Kq——风筒圈梁进口阻力系数，可按本规范附录A.0.1的规定取值；
υq——风筒圈梁进口断面的空气流速(m／s)；
ε0——风筒圈梁进口面积比阻力修正系数，可按本规范附录A.0.2的规定取值。
5 风筒进口渐缩段阻力可按下列公式计算：
(6.3.5-6)
(6.3.5-7)
(6.3.5-8)
式中：∆Pc——风筒渐缩段阻力(Pa)；
Kc——风筒渐缩段阻力系数；
υf——风筒喉部截面积的空气流速(m／s)；
C——风筒进口逐渐缩小缓冲系数，可按本规范附录A.0.3的规定取值；
Af——风筒喉部截面积(m2)；
Ac——风筒渐缩段进口截面积(m2)；
ε——风筒进口渐缩段面积比阻力修正系数；
λ——摩擦系数，可采用0.03；
γ——风筒进口渐缩角(º)。
6 风筒出口扩散段阻力可按下列公式计算：
(6.3.5-9)
Ks＝(Ks1＋Ks2)×(1＋δ) (6.3.5-10)
(6.3.5-11)
(6.3.5-12)
式中：∆Ps——风筒出口扩散段阻力(Pa)；
Ks——风筒出口扩散段阻力系数；
Ks1——风筒扩散段阻力系数；
Ks2——风筒出口动能损失阻力系数；
δ——风筒内装风机造成风速分布不均匀的修正系数，可按本规范附录A.0.4的规定取值；
C＇——逐渐扩大缓冲系数，可按本规范附录A.0.5的规定取值；
As——风筒出口截面积(m2)；
γ＇——风筒出口渐扩角(º)。
7 空气通过抽风式机械通风间接空冷塔总阻力可按下式计算：
TPj＝∆Pb＋∆Phi＋∆Pho＋∆Ph＋∆Pdj＋∆Pz＋∆P1＋∆Pq＋∆Pc＋∆Ps (6.3.5-13)
式中：TPj——空气通过机械通风间接空冷塔总阻力(Pa)。
6.3.6 间接空冷散热器的水力计算宜采用与所设计的散热器相同的实测数据或与所设计的散热器相似的实测数据；当缺乏上述数据时，可按下列经验方法计算圆形管束间接空冷散热器水阻：
1 冷却管束内的水阻可按下式计算：
(6.3.6-1)
式中：RG——冷却管束的水阻(mH2O)；
υw——冷却管束内平均流速(m／s)；
d2——冷却管束内径(mm)；
R1——水温修正系数，可按本标准附录B.0.1的规定取值；
Li——全流程冷却管束总长度(m)。
2 冷却管束流入、流出管端水阻可按本规范附录B.0.2的规定取值，对应的流速为冷却管束内平均流速。
3 水室进口水阻和出口水阻可按本规范附录B.0.2的规定取值，对应的流速为与水室相接的循环冷却水进水管和出水管的流速。
4 间接空冷散热器总水阻可按下式计算：
RT＝RG＋RDi＋RDo＋RSi＋RSo (6.3.6-2)
式中：RT——间接空冷散热器总水阻(mH2O)；
RDi——冷却管束流入管端水阻(mH2O)；
RDo——管端流入冷却管束水阻(mH2O)；
RSi——水室入口水阻(mH2O)；
RSo——水室出口水阻(mH2O)。
6.3.7 间接空冷系统优化计算应符合下列规定：
1 间接空冷系统的优化计算应根据典型年小时气温条件，结合不同末级叶片的汽轮机特性和系统布置，确定最佳的汽轮机背压、凝汽器的型式和面积、空冷散热器型式和面积、冷却水量、循环水泵参数、循环水管管径及空冷塔的塔型等；
2 间接空冷系统的优化计算应按下列两阶段进行：
1) 在工程可行性研究阶段应进行初步优化，确定设计气温，优化间接空冷系统初始温差，确定汽轮机设计背压、空冷系统配置、凝汽器型式和面积；
2) 在工程初步设计阶段，应根据确定的空冷汽轮机特性、空冷设备特性和气象条件等因素进一步对空冷系统设计参数进行优化，确定合理的冷却水量、空冷散热器面积、空冷塔的塔型、主要循环水管管径及经济配置等。
3 间接空冷系统的优化计算宜根据工程具体条件，主要优化参数宜包含如下内容：
1) 冷却水量；
2) 凝汽器的换热面积、流程数、壳体与背压个数，凝汽器内冷却水管的管径、壁厚、根数和长度等；
3) 循环水泵的台数、运行方式；
4) 主要循环水管管径；
5) 空冷散热器型式、冷却三角顶角、高度和数量，空冷散热器面积；
6) 自然通风间接空冷塔零米直径、高度、出口直径、喉部直径等主要塔型参数；机械通风间接空冷塔的迎风面风速、单元数、轴流风机规格及所配电动机的规格、台数。
4 在满足热力性能和总平面布置要求的前提下，间接空冷塔的塔型宜满足本规范5.0.10条的规定；
5 循环水量可通过循环水泵的最佳运行台数进行选择，运行循环水量占总循环水量的百分数可按表6.3.7的规定选取；
表6.3.7 运行循环水量百分数
循环水泵台数 水量百分数(%)
运行1台 运行2台 运行3台 运行4台
2 60～65 100 — —
3 40～45 75～80 100 —
4 30～35 60～65 85～90 100
6 循环水管的流速范围宜按现行行业标准《火力发电厂水工设计规范》DL／T 5339的规定选取。
6.3.8 间接空冷系统优化计算宜采用年费用最小法，计算方法应符合现行行业标准《火力发电厂水工设计规范》DL／T 5339的规定。
6.3.9 水锤计算宜符合现行行业标准《火力发电厂水工设计规范》DL／T 5339的规定。
6.4 间接空冷系统设计裕量
6.4.1 散热器制造厂应提供间接空冷散热器管束传热系数，并宜同时提供试验室试验报告和冷却元件性能试验报告，必要时可提供工程应用测试报告。由试验室试验所得的传热系数，在实际工程应用计算时宜按乘以0.80～0.85的折减系数计算。
6.4.2 间接空冷系统宜留有适当的设计裕量，设计工况的冷却塔出水温度裕量宜为0.5℃～1.5℃，夏季计算工况的冷却塔出水温度裕量宜为1℃～3℃，以现行国家标准《固定式发电用汽轮机规范》GB／T 5578确定铭牌出力时，夏季冷却塔出水温度裕量宜取高值。
7 间接空冷工艺系统及设备
7.1 间接空冷散热器系统
7.1.1 间接空冷散热器宜采用塔周垂直布置，在沙尘暴频发地区散热器可采用塔内水平布置。
7.1.2 散热器型式应根据热负荷需求和环境条件等因素进行选择，宜选择传热效率高、空气阻力小、水力特性好、性能先进和强度能满足安装、运行、维修、清洗要求等的散热器。非钎焊式铝制管束的设计应符合现行行业标准《火力发电厂铝制间接空冷管束》DL/T 1672的有关要求。
7.1.3 散热器的流程形式、冷却柱长度或高度、冷却三角数量选择应结合热负荷需求、气象条件、防冻要求、散热器材质、总平面布置等因素，经技术经济比较论证确定，并宜符合下列规定：
1 钢制管束内水流速度宜为0.7m/s～2.0m/s，铝制管束内水流速度宜为0.7m/s～1.8m/s；
2 冷却柱的水阻不宜大于8m水柱；
3 钢质散热器的冷却柱长度或高度不宜大于15m；
4 铝制散热器的冷却柱高度宜选择散热器本体及其框架的制造成熟可靠的方案；
5 散热器三角数量和冷却柱高度的组合宜使自然通风间接空冷塔塔型符合本标准第5.0.10条的规定。
7.1.4 自然通风间接空冷塔的散热器迎面风速应综合环境风速、冷却水量、间接空冷塔塔型、间接空冷塔高度、空冷系统配置等因素，宜在1.0m/s～2.3m/s范围内选择；机械通风间接空冷塔的散热器迎面风速应综合环境风速、噪声要求、空冷系统配置、电动机电压等级等因素，迎面风速宜在1.5m/s～2.5m/s范围内选择。
