Power loss index

from Wikipedia, the free encyclopedia

The current loss code or current loss coefficient β in describing CHP plants with variable current measure the loss of electric power when a higher thermal capacity is coupled. As a rule, this refers to extraction steam turbines which, in thermal power plants, direct part of the steam that is still capable of working into a heating condenser to generate useful heat, instead of performing mechanical work in the low-pressure part of the steam turbine.

Loss of power in an extraction steam turbine

The picture on the right shows the principle of removal in a simplified manner in the left part. After the medium pressure part (MD) of the turbine, i.e. before the low pressure part (LP), steam is branched off and flows into the heating condenser (HK), where it gives off heat to the heating circuit (temperature level T H approx. 100 ° C) and liquefies in the process. The remaining steam works in the low-pressure part and is then liquefied in the condenser (Ko) at approx. 30 ° C and fed to the feed water circuit via the condensate pump (KoP) . The partial flow of steam that flows into the heating condenser at a high temperature can no longer do any work in the LP section and is responsible for the loss of electricity.

The right side of the picture shows the associated idealized Ts diagram (cf. Clausius-Rankine process ) for an operating state in which half of the waste heat is used for heating purposes. To the left of the red area, the white area below the red line corresponds to the waste heat (q ab ) that is given off to the environment (temperature level T U ) via the condenser . The entire red area corresponds to the useful heat (q heiz ), the upper hatched part of this area corresponds to the power loss in the low-pressure stage.

Modern thermal power stations have power loss ratios of approx. 1/5 to 1/6, i.e. H. exchanging one kWh of electrical energy yields 5 to 6 kWh of useful heat.

Based on the equivalence of power loss and heat gain, according to AGFW FW 309 Part 6, the CO 2 emissions of the fuel are allocated to useful heat and electrical energy.

swell

Individual evidence

  1. ↑ NN: Energetic evaluation of district heating - determination of the specific primary energy factors for district heating supply systems (FW 309-1: 2014-05). In: AGFW worksheets. AGFW, May 2014, accessed July 26, 2018 .