522 / 2019-01-02 18:39:53

Flexibility Upgrading Scheme of Industrial Heating Steam Supply for Cogeneration Units and Peak Load Regulating Capability Analysis

Cogeneration Unit; Peak Load; Regulating Capability; Industrial Heating Steam, 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, very little attention has been paid to the flexibility upgrading schemes of the industrial heating steam supply for the existing cogeneration units. Typically the reheat steam source is selected for the high pressure industrial heating steam supply. This kind of system configuration will cause the close coupling of the heating supply and power output and seriously influence the peak load regulating capability of the cogeneration unit. The objectives of the study in this paper including: (1). to propose a upgrading scheme for a cogeneration unit with double industry steam supply configuration; (2). to analyze the peak load regulating capability improvement and the economic cost for the proposed method.
One flexibility upgrading scheme using the main steam as the high pressure industrial heating steam supply source is suggested. 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 350MW supercritical cogeneration unit performance under various industrial steam supply conditions, and detailed comparison is made for the performance improvement accomplished using the proposed scheme.
It is shown from the calculation results that under same HP turbine exhaust temperature set limit, the decoupling of the heating supply and power output can be realized under single stage steam supply conditions (higher pressure stage), and the minimum power output of the cogeneration unit can be decreased around 137MW using the proposed scheme; under double stages industrial steam supply conditions, the minimum power output of the cogeneration unit can be decreased around 50MW and 124MW in different scenarios using the proposed scheme. In addition, in spite of the lower power output gain in peak load regulating under same heating steam supply condition, poorer heat rate and less profitable total economic benefit of the cogeneration unit are expected in upgrading scheme operation than in original scheme based on the calculation results, which will significantly influence the application of the proposed upgrading scheme in the future.