9.4　Ignition and Combustion Supporting Oil System

9.4.1　Light diesel oil may be used as the ignition and combustion supporting fuel for CFB boilers，pulverized coal boilers and some other kind boilers.If coal gas or natural gas sources are available near the power plant，these gases may also be used.In this case，the design shall comply with relevant safety and technical rules and regulations.If heavy oil is readily available and has satisfactory quality，it may be used as well.Pulverized coal boilers shall use oil-saving ignition systems such as small oil guns，tiny/micro-oil ignition and plasma ignition.

9.4.2　The number and capacity of ignition and combustion supporting oil tank shall comply with the following requirements:

1　For power plants equipped with pulverized coal fired boilers rated below 220 t/h，one or two 50m3-100m3 oil tanks should be provided.

2　For power plants equipped with pulverized coal fired boilers rated 220t/h-410t/h，two 200m3-500m3 oil tanks should be provided.

3　If the pulverized coal fired boilers use oil-saving ignition systems such as plasma ignition，small oil guns，and tiny/micro-oil ignition，the capacity of oil tanks may be reduced by one or two levels accordingly.

4　The capacity of oil tanks for CFB boilers may be one or two levels less than that of the oil tanks for pulverized coal fired boilers with the same rated capacity.

9.4.3　The ignition and combustion supporting oil should be transported by trucks.If the power plant is located near oil source，the oil may be transported by pipelines.If the oil is to be transported by railway，an oil unloading station shall be designed to accommodate one or two oil tank wagons in accordance with the shunting requirements of the competent railway authority.If the fuel oil is to be transported by waterway，the wharf for fuel oil unloading should be constructed together with the wharf for ash handling，the wharf for handling large components and coal wharf.

9.4.4　The mode of fuel oil unloading shall be determined through techno-economic comparison taking into account the fuel oil characteristics，mode of transportation and oil tank conditions.The type，number，flow and head of unloading pumps shall comply with the following requirements:

1　The type of unloading pumps shall be selected according to the oil viscosity，unloading mode and fire protection regulations.

2　If the time limit for oil unloading is specified，the number of unloading pumps should not be less than two.When the largest pump is out of service，the rest pumps shall be able to unload the oil carried by vehicles or ships within the specified time.

3　The head of unloading pumps and the capacity of the associated electric motors shall be calculated based on the maximum viscosity of fuel oil to be delivered.The pressure margin should be 30%.

9.4.5　The type，output and number of oil supply pumps of ignition and combustion supporting oil system shall comply with the following requirements:

1　The type of oil transfer and supply pump shall be determined in accordance with the oil quality and oil supply parameters.Centrifugal pumps or screw pumps should be used.

2　The output of oil supply pump should be selected to accommodate 20%-30% of the fuel consumption of the largest boiler under BRL condition.

3　Two oil supply pumps should be provided，one for standby.

4　The flow margin of oil supply pumps should not be less than 10%，and the pressure margin should not be less than 5%.When calculating the head，the margin of total resistance of the fuel oil piping system（without regard to the atomizing oil pressure of oil guns and height difference）should not be less than 30%.

9.4.6　The oil transfer pump house should be located close to the oil tank area.Ventilation，hoisting facilities，necessary maintenance area and duty room shall be appropriately arranged in the fuel oil pump house.If the automatic control and fire fighting facilities allow unattended operation，the duty room may be eliminated.The electrical equipment provided in the fuel oil pump house shall be of anti-explosion type.

9.4.7　The oil supply and return piping connecting to boiler house should be designed in accordance with the following requirements:

1　One oil supply pipe and one oil return pipe should be provided.

2　Flow measuring devices shall be installed on the oil supply and return piping of each boiler，and may be installed on the main oil supply piping.

3　Fast cut-off valves and manual shutoff valves shall be installed on the oil supply piping of each boiler.Fast cut-off valves should be installed on the oil return piping of each boiler.

4　For fuel oil that is more viscous and prone to condensation，the oil unloading，storage and supply system shall be provided with heating and purging facilities.Steam or other medium tracing piping as well as steam or compressed air purging piping may be provided for the fuel oil piping.Measures shall be taken to prevent the backflow of fuel oil into the steam purging system.

9.4.8　Waste oil and waste water collection facilities and associated oily waste water treatment facilities shall be provided in the fuel oil system.

9.4.9　The design of oil system shall comply with the current national standard GB 50074 Code for Design of Oil Depot.The design of anti-explosion，fire prevention，anti-static and lightning protection measures for the fuel oil tanks and fuel oil delivery piping shall comply with relevant requirements in the current national standards GB 50058 Electrical Installations Design Code for Explosive Atmospheres and Fire Hazard and GB 50229 Code for Design of Fire Protection for Fossil Fuel Power Plants and Substations.

9.4.10　The ground or semi-ground metal fuel oil tanks should be provided with a mobile cooling water system or a combination of stationary and mobile cooling water system.