4　Heating（Cooling）and Electrical Load

4.1　Heating（Cooling）Load and Heating（Cooling）Medium

4.1.1　The heating load of thermal power plants shall be determined through verification based on the urban heat planning.The heating load of an enterprise's self-supply thermal power plants shall be determined according to the heat supply amount shown in the enterprise planning.

4.1.2　The planned capacity and construction scale at each stage of thermal power plants shall be determined according to the short-term and long-term heat loads as verified through investigation and the cogeneration planning of the local region.

4.1.3　The cost effective and reasonable heat supply scope of thermal power plants shall be determined through techno-economic comparison based on such factors as the characteristics and distribution of heating loads，the cost of heat source，construction cost of heat supply network and the parameters of heating medium.The transmission distance of steam piping network and hot water piping network should not be longer than 8 km and 20 km respectively.

4.1.4　The design heating load shall be determined according to the general conditions and distribution of heat sources，heat supply capacity and steam parameters within the heat supply scope，and shall comply with the following requirements:

1　To determine the industrial heating load，the nature，steam parameters，steam consumption mode，heat consumption mode，return water condition，and monthly mean steam consumption and steam utilization hours in the last year of the existing and planned heating loads of heat customers shall be investigated and collected，and the maximum，minimum and mean hourly steam consumption during winter and summer shall be determined based on the hourly steam consumption of heat customers on typical days during different seasons.For main heat customers，the typical daily heat load curve during different seasons and the annually continuous heat load curve shall be plotted.

2　To determine the heat load for heating purpose，the type of heat customers in both short term and long term within the range of heat supply shall be collected，and the heating area and heating load index shall be respectively calculated.The heat load shall comply with the following requirements:

1）Based on the local meteorological data，the hourly heat loads corresponding to various specified outdoor design temperatures from the initial temperature（i.e.，the temperature at which heating is started）to the heating outdoor calculation temperatures as well as the mean heat load during heating period shall be calculated，the annual load curve during heating period shall be plotted，and the utilization hours of the maximum and mean heating loads shall be calculated.

2）If a heated building requires ventilation and air conditioning heating loads，the heating load required to heat the ventilated fresh air and air conditioning for the building shall be added to the calculated heating load.

3）The heating index shall comply with applicable requirements of the current industrial standard CJJ 34 Design Code of District Heating Network.

3　To determine the hot water heating load，the area of residential houses and public buildings and the hot water heating load index shall be collected，and the average and maximum heat loads of domestic hot water shall be calculated.

4.1.5　In summer，the heat load used for heat-operated refrigerating systems should be developed.The heat load for heat-operated refrigerating system shall be determined based on the area and thermal characteristics of the cooled building，the meteorological data and the requirements of cooling process on heating medium.

4.1.6　The maximum，minimum，and average steam consumption and steam parameters of heat customers during different seasons as verified through investigation shall be converted into the steam supply parameters，steam supply flow and heat supply of the thermal power plant based on the enthalpy and the pressure drop and temperature drop of pipes.When the heat load for heating purpose and domestic hot water are calculated based on the relevant design indices，the load loss through hot water pipe network shall not be considered.

4.1.7　When the heat loads of heat customers are added up，the simultaneity factor shall be selected in accordance with the following requirements:

1　For major heat customers which require stable heat load for production purpose，when adding up their heat loads，the simultaneity factor shall not be considered if their typical daily heat load curves during different seasons have been obtained.

2　For minor heat customers which require less heat loads or require no stable heat load for production purpose，when adding up their maximum heat loads，the simultaneity factor shall be considered.

3　When the heat loads for heating purpose，air conditioning and refrigeration，and domestic hot water are added up，the simultaneity factor shall not be considered.

4　The simultaneity factor should be taken as 0.7-0.9.In regions with a stable demand for heat loads，a larger simultaneity factor shall be taken；otherwise，a less value shall be taken.

4.1.8　The type of cogeneration units shall be selected and the heat economic index of power plants be calculated according to the typical daily load curve of steam and hot water during heating and non-heating periods of the power plant and the yearly heat load duration curve.

4.1.9　The heating（cooling）medium of thermal power plants shall be determined according to the following principles:

1　If the customers'main production process requires steam for heat supply purpose，steam shall be used as the heating medium.

2　If a majority of the customers require hot water medium for their production process while other customers require steam converted from hot water，then hot water medium should be used for heat supply if justified through techno-economic comparison.

3　The heat load supplied to residential buildings just for heating，ventilation，air conditioning and domestic hot water use purpose shall be through hot water supply.

4　If the main production process of the customers must rely on steam supply while a large number of residential buildings require hot water supply for heating，ventilation，air conditioning and hot water use purpose，a combination of steam and hot water medium shall be used for heat supply.However，if just a small amount of heat load is required for heating，ventilation，and air conditioning purpose，then only steam medium may be supplied if justified through techno-economic comparison.

5　Cold water is generally used as the cooling medium.

4.1.10　The parameters of heating（cooling）medium shall be selected in accordance with the following requirements:

1　The steam parameters required by the production process of the customers shall be used to determine the steam supply parameters of the thermal power plant after allowing for the steam enthalpy as well as pressure drop and temperature drop across the piping，which constitutes the basis for determining the optimum steam exhaust or extraction parameters of turbines through techno-economic comparison.

2　The optimum design water supply and return temperature of hot-water heat supply network shall be determined according to the project-specific conditions in conjunction with the conditions of the secondary heat supply systems of thermal power plant，piping network，heating station and heat customers through techno-economic analysis.When it is not practicable to make techno-economic comparison in terms of the water supply and return temperature of hot-water heat supply network，they may be determined according to the following principles:

1）For the heat supply network connected to customers through heating stations，the water supply temperature of thermal power plants may be taken as 110℃-150℃.If base load heaters are used，a smaller value may be taken；if base load heaters in serial connection with peak load heaters（including peak load boilers）are used，a larger value may be taken.The water return temperature may be taken as 60℃-70℃.

2）For the heat supply network directly supplying hot water to customers，the water supply and return temperature may be taken as about 95℃and 65℃-70℃respectively.

3）The cooling water supply temperature medium shall be 5℃-9℃，preferably 7℃.And the cooling water return temperature shall be 10℃-14℃，preferably 12℃.

4.1.11　If indirect heating is involved at the customer end of steam supply network，the condensate recovery rate shall be higher than 80%.The condensate recovery mode and recovery rate at the customer end shall be determined based on the condensate quality，condensate flow，transmission distance，and condensate piping investment through comprehensive techno-electric comparison.