Corrosion protection method for supercritical generator set

Abstract

The invention provides a corrosion protection method for a supercritical generator set, and relates to the technical field of corrosion protection of generator sets. The corrosion protection method comprises the following steps of: preheating the supercritical generator set, wherein the supercritical generator set adopts TP347H steel; introducing oxygen into the preheated supercritical generator set, and preparing a first oxide layer on the inner wall of the supercritical generator set; and introducing ozone into the treated supercritical generator set, and preparing a second oxide layer on the inner wall of the supercritical generator set, thereby obtaining the supercritical generator set with double oxide layers on the inner wall. According to the corrosion protection method provided by the invention, a layer of oxide film is pre-oxidized on the surface of the TP347H heat-resistant steel of the supercritical generator set, and a relatively thick oxide layer is generated around Cr ions of the TP347H boiler steel, so that intergranular corrosion of the TP347H boiler steel is powerfully prevented, and therefore, the service life of equipment is prolonged, and the danger of red tubes and explosion of the boiler is effectively prevented.

Description

technical field [0001] The invention relates to the technical field of corrosion protection for generator sets, in particular to a corrosion protection method for supercritical generator sets. Background technique [0002] Most of the existing thermal power plant units use supercritical units, and the temperature of the boiler, reheater, and superheater reaches 650°C or more. This temperature is called supercritical temperature, and this kind of generating unit is called supercritical power generation. Unit, at such a high temperature, water vapor corrosion of the generator set often occurs. Corrosion not only reduces the service life of the equipment, but also reduces the heat transfer efficiency of the generator set equipment by the oxides produced by corrosion. What is more serious is the corrosion product During the operation of the equipment, large pieces will fall off, and the fallen oxides will accumulate together, blocking the furnace tube of the boiler of the genera...

AI Technical Summary

Problems solved by technology

[0002] Most of the existing thermal power plant units use supercritical units, and the temperature of the boiler, reheater, and superheater reaches 650°C or more. This temperature is called supercritical temperature, and this kind of generating unit is called supercritical power generation. Unit, at such a high temperature, water vapor corrosion of the generator set often occurs. Corrosion not only reduces the service life of the equipment, but also reduces the heat transfer efficiency of the generator set equipment by the oxides produced by corrosion. What is more serious is the corrosion product During the operation of the equipment, large pieces will fall off, and the fallen oxides will accumulate together, blocking the furnace tube of the boiler of the generator set

Once corrosion oxides are accumulated in the furnace tube of the boiler, the "red tube" of the boiler will appear in the lighter case. The red tube indicates that the local heat transfer efficiency of the furnace tube is low, the temperature of the furnace tube is higher than the design temperature, and the strength of the boiler tube is greatly reduced, which may happen at any time. explosion hazard

With the requirement of flexible operation of thermal power generation units according to the power consumption, thermal power boilers are shut down more frequently. During the conversion process of boiler shutdown, oxides in the furnace tubes of power generation units are more likely to fall off, which seriously affects the safe operation of boilers.

What is more serious is that the currently used TP347H boiler steel has added elements such as Cr, Ni, Si, Mn, etc. These elements are very effective in improving the heat resistance and yield strength of boiler steel, but the addition of Cr makes the steel Cr is easily formed at high temperature 23 C 6 The intermediate phase will form a Cr-poor area around the intermediate phase, and the Cr-poor area will preferentially corrode, resulting in a decrease in the strength of the steel, which is prone to corrosion and explosion accidents. figure 1 Metallographic photographs of corrosion in Cr-depleted areas for boiler steels, such as figure 1 The prevention of corrosion in the Cr-poor area is also the key to the corrosion protection of boiler steel.

Images