Valmet Technologies Oy

Mikko Varonen

Matti Nieminen

Pekka Lehtonen

Tero Luomaharju

Juha Hiljanen

Pertti Tapiainen

The solution comprises a method of and a system for maintaining steam temperature and therefore electricity production efficiency with decreased loads of a steam turbine power plant comprising a fluidized bed boiler () and a fluidized bed superheater () adapted to superheat steam supplied to a steam turbine (). According to the solution, the steam temperature may be maintained by providing, outside a furnace (), additional heating to the fluidized bed material in its outer circulation, thereby increasing the amount of thermal energy available in the fluidized bed material to be transferred in the fluidized bed superheater () to the steam supplied to the steam turbine (). Such additional heating may be performed by selectably supplying combustible gas with nozzles () into and/or burned with a burner in or in the vicinity of the fluidized bed material outside the furnace (). As an additional aspect of the disclosed solution, the combustible gas may be produced with a gasifier ().

Method and a system for maintaining steam temperature with decreased loads of a steam turbine power plant comprising a fluidized bed boiler

A method and an arrangement for optimizing combustion conditions in a fluidized-bed boiler, in which combustion gas is fed at two or more height levels, the first of which is a primary level (P) which is located at the height of a furnace bottom and the second is a secondary level (S) which is located above fuel feed height (F), above which secondary level (S) there can be still other combustion gas feed levels (T, . . . ). At least one combustion gas feed level (P, S, T, . . . ) is fed at different points of the furnace () in its horizontal direction with combustion gases having different oxygen contents such that zones of different oxygen content can be formed in the horizontal direction of the furnace ().

Growing community of inventors

Tampere, Finland

Mikko Varonen