A low-pressure cylinder zero-output cooling effect evaluation method suitable for wet cooling 300mw unit

Abstract

A method for evaluating the cooling effect of a low-pressure cylinder with zero output suitable for a wet-cooled 300MW unit of the present invention includes: 1) for the wet-cooled 300MW unit, through the test method, respectively obtain: cooling steam flow rate, cooling steam temperature, unit back pressure, low-pressure cylinder The correction curve of the desuperheating water flow to the temperature of the secondary and final stages of the low-pressure cylinder. 2) Combined with each correction curve, respectively obtain: the correction value of cooling steam flow, cooling steam temperature, unit back pressure, and low-pressure cylinder desuperheating water flow to the temperature of the second and final stages of the low-pressure cylinder. 3) Combining the correction values, obtain: comprehensive correction value. 4) According to the comprehensive correction value in step 3), obtain: the corrected temperature of the second and last stage of the low-pressure cylinder and the last stage. During the actual zero-output operation, when the temperature, pressure, flow rate of the cooling steam and the back pressure of the unit deviate from the design value, the cooling effect of the cooling steam on the second and last stage blades and the last stage blades can be directly evaluated qualitatively and quantitatively. design value.

Description

technical field [0001] The invention belongs to the technical field of steam turbine operation, and in particular relates to a low-pressure cylinder zero-output cooling effect evaluation method suitable for a wet-cooled 300MW unit. Background technique [0002] In recent years, the low-pressure cylinder zero-output technology has greatly improved the unit’s heating capacity and electrical peak-shaving capacity, enabling flexible switching between the extraction and condensing steam extraction and the low-pressure cylinder zero-output operation mode of the heating unit. has been widely used. During the zero-output operation of the low-pressure cylinder, the steam entering the low-pressure cylinder from the medium and low-pressure connecting pipes is completely blocked, and only a small amount of steam enters the low-pressure cylinder through the cooling steam pipeline in the form of cooling steam, and maintains the secondary and final stage together with the desuperheating wa...

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Problems solved by technology

[0003] However, in the actual operation process, the unit load and ambient temperature cannot always be at the design value, and the temperature, pressure, flow rate and unit back pressure of the cooling steam also have certain deviations from the design value, so it is impossible to directly and quantitatively evaluate the impact of the cooling steam on the sub-final stage, The cooling effect of the final blade, so it is necessary to propose a new method to correct the temperature of the last stage and the final stage of the low-pressure cylinder to evaluate the cooling effect of the cooling steam and whether it reaches the design value

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