System for readying sub-critical and super-critical steam generator, servicing method of said sub-critical and super-critical steam generator and method of operation of sub-critical and super-critical steam generator

A method of operating of a steam generator,

• wherein the steam generator includes:
• at least one water-steam separator,
• an economizer,
• an auxiliary fuel combustor for warming up the steam generator using auxiliary fuel,
• a waterwall inlet header,
• a heating system comprising a deaerator connected to the economizer for providing at least partially degassed water to the economizer, and
• a furnace, wherein the furnace includes waterwall tubes, and
• wherein the waterwall tubes are connected to said at least one water-steam separator with furnace top-end piping, and
• wherein the method includes:
• installing of a system for readying the steam generator, wherein the system comprises:
• a first auxiliary heating device disposed on said at least one water-steam separator for heating said at least one water-steam separator,
• a second auxiliary heating device disposed at least on a part of the furnace top-end piping for heating the furnace top-end piping,
• a third auxiliary heating device disposed on the deaerator for heating the deaerator,
• a fourth auxiliary heating device disposed on the economizer for heating the economizer,
• a controller for controlling the steam generator and the auxiliary heating devices, and
• a measurement system including pressure and/or temperature sensors, wherein the measurement system provides pressure and temperature measurements of the steam generator and temperature measurements of the system for readying the steam generator to the controller, and
• starting up of the steam generator and/or shutting down of the steam generator,
• wherein the step of starting up of the steam generator includes the following substeps:
• using at least one of the first auxiliary heating device, the second auxiliary heating device, the third auxiliary heating device, the third auxiliary heating device, and the fourth auxiliary heating device to start heating the steam generator while recirculating the water through the steam generator, and
• wherein the step of shutting down of the steam generator includes:
• keeping said at least one water-steam separator filled with water and blanketing said at least one water-steam separator with nitrogen or keeping the deaerator bottled up together with the third auxiliary heating device,
• keeping the economizer bottled up together with the fourth auxiliary heating device,
• keeping said at least one water-steam separator at least at the temperature in which materials making said at least one water-steam separator are no longer brittle with the first auxiliary heating device, and
• keeping the furnace top-end piping at least at the temperature in which materials making the furnace top-end piping are no longer brittle with the second auxiliary heating device, and
• wherein keeping the deaerator and the economizer bottled up includes limiting of gas diffusion into the water stored in the deaerator and the economizer.