8　Boiler Equipment and System

8.1　Boiler Equipment

8.1.1　Boiler equipment shall comply with relevant specifications in the current industrial standards DL 612 Supervision Code for Boiler and Pressure Vessel of the Power Industry and DL 647 Inspection Code for Boiler and Pressure Vessel of the Power Industry.

8.1.2　The pressure drop and temperature drop of the superheat steam system and reheat steam system shall comply with the following requirements:

1　The pressure drop from boiler superheater outlet to turbine steam inlet should not be larger than 5%of the rated inlet steam pressure of the turbine.

2　For units with subcritical and below parameters,the rated steam temperature at the superheater outlet should be 3℃higher than the rated inlet steam temperature of the turbine；for unit with supercritical and ultra supercritical parameters,the rated steam temperature at the superheater outlet should be 5℃higher than the rated inlet steam temperature of the turbine.

3　For units with subcritical and below parameters,the total pressure drop across reheat steam system should be determined to be 10%of the steam exhaust pressure of high-pressure cylinder at rated condition of the turbine,specially,the pressure drop across the cold reheat steam piping,reheater and hot reheat steam piping should be 1.5%-2.0%,5%,3.5%-3.0%respectively.For units with ultra supercritical parameters,the total pressure drop across reheat steam system should be determined in the range of 7%to 9%of the steam exhaust pressure of high-pressure cylinder at rated condition of the turbine,specially,the pressure drop across the cold reheat steam piping,reheater and hot reheat steam piping should be 1.3%-1.7%,3.5%-4.5%and 2.2%-2.8%respectively.

4　The rated steam temperature at reheater outlet shall be 2℃higher than the rated inlet steam temperature of the intermediate pressure cylinder of the turbine.

8.1.3　The configuration of safety valves of boiler shall conform to the following requirements:

1　In addition to the provisions in item 2 of this clause,sufficient number of safety valves shall be installed at boiler drum,superheater outlet,reheat system and external startup separator of once-through boiler（provided with isolation valves）according to the relevant provisions in the current industrial standard DL/T 959 Guide of Safety Valves for Power Station Boilers.

2　If 100%three-use-valve high pressure bypass with safety valve function is adopted,if the high pressure bypass owns independent safety protection function control circuit and is up to the relevant standards,the safety valve of the boiler superheater system may be replaced with the high pressure bypass valve.The reheater safety valve may be provided with tracing and partial overflow function.

8.1.4　The design of coal pulverizing system and air and flue gas system shall meet the requirements of overall performance design of boiler and comply with the relevant provisions in the current industrial standards DL/T 5145 Technical Code for Design and Calculation of Pulverized Coal Preparation System of Fossil-fired Power Plant and DL/T 5240 Technical Code for Design and Calculation of Combustion System of Fossil-fired Power Plant.