INTERGRATION CONSTRUCTION BETWEEN A BOILER AND A STEAM TURBINE AND METHOD IN PREHEATING OF THE SUPPLY WATER FOR A STEAM TURBINE AND IN ITS CONTROL

摘要

The present invention concerns an integration construction between a steamboiler provided with a combustion chamber and a steam turbine. The steam isconducted from the steam boiler (10) along a connector to the steam turbine(11) for rotating an electric generator (K) producing electricity. The supplywater circulated via the steam boiler (10) is vaporized in a vaporizer (190)located in the steam boiler (10) and superheated in a superheater (120). Thesupply water is conducted into the boiler through an economizer (20) acting asa heat exchanger, where heat is transferred from the flue gases of the boilerinto the supply water. The economizer (20) is provided with at least twosections, comprising at least one first economizer section (20a1) and at leastone second economizer section (20a2). The supply water is conducted from thefirst economizer section (20a1) to a supply water preheater formed from a heatexchanger (14), where thermal energy is transferred from bled steams of thesteam turbine either directly or via a medium, advantageously water, into thesupply water. The supply water preheated with bled steams of the steam turbineis conducted in the steam boiler (10) to the second economizer section (20a2)and further to the vaporizer (190) and the superheater (120) and therethrough,in the form of steam, to the steam turbine. In the integration construction,the temperature of the supply water is raised continuously as the supply wateris flowing in the first economizer section (20a1) and from the firsteconomizer section (20a1) to the supply water preheater (14) and threthrough,to the second economizer section (20a2). The connector (13a1.1) leading to thesupply water preheater (14) comprises a valve (21) for controlling the bled-steam flow to the preheater (14). The present invention concerns also a methodin the preheating of the supply water for a steam turbine and in its control.