513 / 2019-01-02 18:40:40

Peak Load Regulating Capability Analysis of LP Turbine Outage Scheme for Cogeneration Units Flexibility Upgrading

Cogeneration Unit; Peak Load; Regulating Capability; Analysis; LP Turbine Outage upgrading scheme.

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With the increasing pressure of the strengthening the peak load regulating capability of the cogeneration units in North China, various flexibility upgrading schemes are suggested for the existing cogeneration units. Among these LP Turbine Outage Upgrading Scheme is one of the most attractive schemes and has won great attention from the utility users. The objectives of the study in this paper including: (1). to analyze the performance improvement attained by the proposed LP Turbine Outage Upgrading Scheme; (2). to analyze the economic cost and benefit achieved compared with the original unit by the proposed method.
Detailed information is described for the function and configuration of the proposed scheme, including the advantages and disadvantages of the system. Model-based software is utilized for the simulation of the one 300MW subcritical cogeneration unit performance and its LP Turbine Upgrading Scheme performance, and detailed comparison is made for the performance improvement accomplished. Based on the models simulation results, the unit performance improvement especially the unit load regulating capability under various heating load conditions is studied.
It is shown from the calculation results that under same steam inlet flow condition, the maximum heating steam supply capacity is increased by around 100t/h and unit power output is decreased by 14-15MW from the adopted upgrading scheme, therefore under the LP Turbine Outage operation mode, the cogeneration unit has significantly increased heating supply capacity compared with the original unit. Further analysis indicates that under same heating steam supply conditions, compared with the original cogeneration unit the unit minimum power output can be decreased by around 56MW using the upgrading scheme. However, the disadvantage of operating as a backpressure generation unit under LP Turbine Outage operation mode makes the unit impossible to adapt to external power demand. In addition, in spite of the lower power output and more economical heat rate under same heating steam supply condition, the total economic benefit of the cogeneration unit is less profitable in upgrading scheme operation than in original scheme based on the calculation results, which will significantly influence the decision-making of application of the LP Turbine Outage upgrading scheme.