On-line monitoring of steam turbine performance

Claim 1

A method for accurately detecting the operating conditions of a steam turbine system having a plurality of sections, comprising the steps of: operating at least a portion of the plurality of sections of the turbine system under substantially similar conditions; monitoring corresponding parameters representative of the operation of the plurality of sections operating under similar conditions; generating electrical signals representative of the parameters monitored; determining electrically the difference between the largest and smallest values of the corresponding monitoring signals; comparing electrically this difference with a predetermined first design figure; comparing electrically the difference between each of the signals and a bogie figure when the difference between the largest and smallest value exceeds the first design figure; tagging electrically all monitoring signals which differ from the bogie figure by more than a second predetermined design figure; and displaying, in real time, upon command, the tagged signal and an indication of the associated monitoring sensor as being unreliable.

Claim 2

A method for accurately detecting the operating conditions of a steam turbine system having a plurality of sections, comprising the steps of: operating at least a portion of the plurality of sections of the turbine system under substantially similar conditions; monitoring corresponding parameters representative of the operation of the plurality of sections operating under similar conditions; generating electrical signals representative of the parameters monitored; determining electrically the difference between the largest and smallest values of the corresponding monitoring signals; comparing electrically this difference with a predetermined first design figure; comparing electrically the difference between each of the signals and a bogie figure when the difference between the largest and smallest value exceeds the first design figure; tagging electrically all monitoring signals which differ from the bogie figure by more than a second predetermined design figure; and displaying, in real time, upon command, the tagged signal and an indication of the associated monitoring sensor as being unreliable.

Claim 5

A method of operating a steam turbine system in the wet steam region to obtain selected calculated performance variables including the steps of: operating the steam turbine with wet steam; monitoring the operation of tHe turbine to obtain corresponding signals representative of parameters on which the selected performance variables depend; generating electrical signals representative of the monitored parameters; providing an electrical representation of an assumed moisture content for the wet steam; calculating electrically a first performance variable as a function of the assumed moisture content; determining electrically a calculated value of the moisture content as a function of the calculated performance variable and an independently calculated performance variable dependent upon the monitoring signals; comparing electrically the calculated value of moisture content with the assumed value and repeating the calculations substituting a function of the calculated moisture content for the assumed moisture content until the assumed and calculated values of the moisture content are within predetermined limits; and displaying, in real time, upon command, the calculated value of the moisture content within the predetermined limits.

Claim 6

A method of operating a steam turbine system in the wet steam region to obtain selected calculated performance variables including the steps of: operating the steam turbine with wet steam; monitoring the operation of tHe turbine to obtain corresponding signals representative of parameters on which the selected performance variables depend; generating electrical signals representative of the monitored parameters; providing an electrical representation of an assumed moisture content for the wet steam; calculating electrically a first performance variable as a function of the assumed moisture content; determining electrically a calculated value of the moisture content as a function of the calculated performance variable and an independently calculated performance variable dependent upon the monitoring signals; comparing electrically the calculated value of moisture content with the assumed value and repeating the calculations substituting a function of the calculated moisture content for the assumed moisture content until the assumed and calculated values of the moisture content are within predetermined limits; and displaying, in real time, upon command, the calculated value of the moisture content within the predetermined limits.

Claim 9

A method of operating a steam turbine to obtain on-line measurement of steam turbine wet steam group outlet enthalpies comprising the steps of: operating the steam turbine in the wet steam region; monitoring group inlet and outlet pressures; generating electrical signals corresponding to the group inlet and outlet pressures monitored; calculating electrically the change in enthalpy ( h) for isentropic expansion in a selected group as a function of the group inlet enthalpy and the group inlet and outlet pressures monitored; providing an electrical representation of an assumed moisture content for the outlet steam; calculating electrically the outlet steam enthalpy as a function of h and the assumed moisture content; calculating electrically the moisture content of the outlet steam as a function of the calculated outlet enthalpy; comparing electrically the calculated moisture content with the assumed moisture content; electrically iteratively recalculating the calculated wet steam enthalpy using a function of the calculated moisture content as the assumed moisture content until the deviation between the calculated moisture content and the assumed moisture content is within predetermined limits; and displaying, in real time, upon command, the calculated moisture content within the predetermined limits.

Claim 10

A method of operating a steam turbine to obtain on-line measurement of steam turbine wet steam group outlet enthalpies comprising the steps of: operating the steam turbine in the wet steam region; monitoring group inlet and outlet pressures; generating electrical signals corresponding to the group inlet and outlet pressures monitored; calculating electrically the change in enthalpy ( h) for isentropic expansion in a selected group as a function of the group inlet enthalpy and the group inlet and outlet pressures monitored; providing an electrical representation of an assumed moisture content for the outlet steam; calculating electrically the outlet steam enthalpy as a function of h and the assumed moisture content; calculating electrically the moisture content of the outlet steam as a function of the calculated outlet enthalpy; comparing electrically the calculated moisture content with the assumed moisture content; electrically iteratively recalculating the calculated wet steam enthalpy using a function of the calculated moisture content as the assumed moisture content until the deviation between the calculated moisture content and the assumed moisture content is within predetermined limits; and displaying, in real time, upon command, the calculated moisture content within the predetermined limits.

Claim 17

A method of operating a steam turbine system in the wet steam region including extracting a portion of the wet steam and liquid moisture between turbine groups in a mixed flow and on-line monitoring of turbine performance with the mixed flow extraction, comprising the steps of: monitoring the pressure of the mixed flow extracted; generating a signal representative of the monitored pressure; determining the combined enthalpy and mixed flow of the wet steam and liquid extracted; providing an electrical representation of an assumed moisture content of the steam prior to extraction; calculating electrically the flow of removed moisture as a function of the assumed moisture content; determining electrically the enthalpy of the extracted liquid as a function of the extraction pressure monitored; determining electrically the enthalpy of the extracted steam from the enthalpy and flows of the liquid removed and the total extraction flow; calculating electrically the enthalpy of the wet steam prior to extraction from a heat balance dependent in part on the monitored pressure around the extraction point; calculating electrically the moisture content of wet steam prior to extraction as a function of the enthalpy of the steam prior to extraction; comparing electrically the calculated moisture content with the assumed moisture content and to iteratively recalculate the enthalpies of the extracted steam and the steam prior to extraction until the deviation between the calculated moisture content and the assumed moisture content is within predetermined limits; and displaying, in real time, upon command, the calculated moisture content within the predetermined limits.

Claim 18

A method of operating a steam turbine system in the wet steam region including extracting a portion of the wet steam and liquid moisture between turbine groups in a mixed flow and on-line monitoring of turbine performance with the mixed flow extraction, comprising the steps of: monitoring the pressure of the mixed flow extracted; generating a signal representative of the monitored pressure; determining the combined enthalpy and mixed flow of the wet steam and liquid extracted; providing an electrical representation of an assumed moisture content of the steam prior to extraction; calculating electrically the flow of removed moisture as a function of the assumed moisture content; determining electrically the enthalpy of the extracted liquid as a function of the extraction pressure monitored; determining electrically the enthalpy of the extracted steam from the enthalpy and flows of the liquid removed and the total extraction flow; calculating electrically the enthalpy of the wet steam prior to extraction from a heat balance dependent in part on the monitored pressure around the extraction point; calculating electrically the moisture content of wet steam prior to extraction as a function of the enthalpy of the steam prior to extraction; comparing electrically the calculated moisture content with the assumed moisture content and to iteratively recalculate the enthalpies of the extracted steam and the steam prior to extraction until the deviation between the calculated moisture content and the assumed moisture content is within predetermined limits; and displaying, in real time, upon command, the calculated moisture content within the predetermined limits.

Claim 19

A method of operating a steam turbine system to obtain on-line measurement of turbine expansion line points for a steam turbine having extraction lines for each of a plurality of groups comprising the steps of: extracting a portion of the wet steam and liquid moisture in a mixed flow at each of the turbine groups; monitoring the extraction pressures of the mix flow at each of the extraction points; monitoring the total extraction flow for the plurality of groups; generating electrical signals representative of respective pressures and total flow monitored; calculating electrically the expansion line points for each extraction at each group as a function of the extraction pressure monitored; calculating electrically the extraction flows as a function of the expansion line points; calculating electrically a correction factor as a function of the ratio of the measured total extraction flow monitored to the sum of the calculated group extraction flows; and applying the correction factor to the extraction flows and then recalculating the expansion line points as a function of the corrected extraction flows.

Claim 20

A method of operating a steam turbine system to obtain on-line measurement of turbine expansion line points for a steam turbine having extraction lines for each of a plurality of groups comprising the steps of: extracting a portion of the wet steam and liquid moisture in a mixed flow at each of the turbine groups; monitoring the extraction pressures of the mix flow at each of the extraction points; monitoring the total extraction flow for the plurality of groups; generating electrical signals representative of respective pressures and total flow monitored; calculating electrically the expansion line points for each extraction at each group as a function of the extraction pressure monitored; calculating electrically the extraction flows as a function of the expansion line points; calculating electrically a correction factor as a function of the ratio of the measured total extraction flow monitored to the sum of the calculated group extraction flows; and applying the correction factor to the extraction flows and then recalculating the expansion line points as a function of the corrected extraction flows.

Claim 25

A method of operating a steam turbine system in the wet steam region to analyze the performance of the last group of the high pressure turbine in a Rankine regenerative steam turbine cycle including the steps of: operating the last group of the high pressure turbine with wet steam; monitoring the temperature and pressure of the exhaust steam exiting from the reheaters associated with the Rankine cycle; generating an electrical signal representative of the pressures and temperatures monitored; providing an electrical representation of an assumed relative proportion of last group steam flow which is directed to the reheater of the Rankine regenerative cycle as exhaust steam and the proportion which is directed to the feedwater heater of the regenerative cycle as extraction steam; determining electrically the enthalpy of the reheated exhaust steam as a function of the temperature and pressure monitored; providing an electrical representation of a heat balance around the reheater using the assumed proportion of reheated exhaust steam to calculate the enthalpy of the exhaust steam; performing electrically a heat balance around the heater to determine the calculated extraction flow using the calculated enthalpy of the exhaust steam for that of the extraction steam; and comparing electrically the calculated and assumed values of the extraction flow and iteratively electrically performing the heat balances substituting a function of the calculated extraction flow for the assumed extraction flow until the difference between the calculated value and assumed value is within predetermined limits.

Claim 26

A method of operating a steam turbine system in the wet steam region to analyze the performance of the last group of the high pressure turbine in a Rankine regenerative steam turbine cycle including the steps of: operating the last group of the high pressure turbine with wet steam; monitoring the temperature and pressure of the exhaust steam exiting from the reheaters associated with the Rankine cycle; generating an electrical signal representative of the pressures and temperatures monitored; providing an electrical representation of an assumed relative proportion of last group steam flow which is directed to the reheater of the Rankine regenerative cycle as exhaust steam and the proportion which is directed to the feedwater heater of the regenerative cycle as extraction steam; determining electrically the enthalpy of the reheated exhaust steam as a function of the temperature and pressure monitored; providing an electrical representation of a heat balance around the reheater using the assumed proportion of reheated exhaust steam to calculate the enthalpy of the exhaust steam; performing electrically a heat balance around the heater to determine the calculated extraction flow using the calculated enthalpy of the exhaust steam for that of the extraction steam; and comparing electrically the calculated and assumed values of the extraction flow and iteratively electrically performing the heat balances substituting a function of the calculated extraction flow for the assumed extraction flow until the difference between the calculated value and assumed value is within predetermined limits.

Claim 28

A method of operating a steam turbine to provide on-line monitoring of the exhaust enthalpy of the turbine system operating in the wet steam region including the steps of: operating the turbine with wet steam; monitoring the temperature and pressure around the condensers receiving the exhaust steam from the turbine; generating an electrical signal representative of the temperature and pressure monitored; providing an electrical representation of an assumed exahust steam moisture content; calculating electrically the exhaust enthalpy as a function of the assumed moisture content; calculating electrically the condenser steam inlet enthalpy from the monitored condenser temperature and pressure signal; and comparing electrically the values of the exhaust enthalpy and the condenser inlet enthalpy and iteratively electrically recalculating the exhaust enthalpy by adjusting the assumed moisture content as a function of the difference between the exhaust enthalpy and the condenser inlet enthalpy until this difference is within predetermined limits.

Claim 29

A method of operating a steam turbine to provide on-line monitoring of the exhaust enthalpy of the turbine system operating in the wet steam region including the steps of: operating the turbine with wet steam; monitoring the temperature and pressure around the condensers receiving the exhaust steam from the turbine; generating an electrical signal representative of the temperature and pressure monitored; providing an electrical representation of an assumed exahust steam moisture content; calculating electrically the exhaust enthalpy as a function of the assumed moisture content; calculating electrically the condenser steam inlet enthalpy from the monitored condenser temperature and pressure signal; and comparing electrically the values of the exhaust enthalpy and the condenser inlet enthalpy and iteratively electrically recalculating the exhaust enthalpy by adjusting the assumed moisture content as a function of the difference between the exhaust enthalpy and the condenser inlet enthalpy until this difference is within predetermined limits.