A method for adjusting reheated steam temperature by steam soot blowing for tower type once-through boilers in thermal power plants

Abstract

The invention discloses a method for adjusting reheated steam temperature through steam soot blowing for a thermal power plant tower type concurrent boiler. The method specifically comprises the first step that steam is guided into a soot lance, the second step that soot blowing is carried out on the heating face of a superheater and the heating face of a reheater in the tower type concurrent boiler through the steam in the soot lance to change the soot formation degree of the surface of the superheater and the soot formation degree of the surface of the reheater, and the third step that whether the steam temperature of an outlet of the reheater meets a preset requirement or not is judged; if the steam temperature needs to be improved, the strength of the soot blowing on the heating face of the superheater is reduced and / or the strength of the soot blowing on the heating face of the reheater is increased at the second step; if the steam temperature needs to be lowered, the strength of the soot blowing on the heating face of the superheater is increased and / or the strength of the soot blowing on the heating face of the reheater is reduced at the second step. The method can effectively improve the reheated steam temperature in the operation of a unit, improve the operating economy of the unit and improve the operating safety of the unit.

Description

technical field [0001] The invention relates to a method for adjusting the temperature of reheated steam by steam soot blowing, in particular to a method for adjusting the temperature of reheated steam by steam soot blowing used in a tower type once-through boiler of a thermal power plant. Background technique [0002] Steam temperature is an important detection and control parameter in the production and operation of thermal power plants. If it is too high or too low, it will affect the safety and economy of unit operation. Therefore, the control of main steam temperature and reheat steam temperature is the main task of thermal power plant operation one. For once-through boilers, since the main steam temperature can be controlled within a reasonable range by means of coal-water ratio and spray water desuperheating, the control of the main steam temperature is not the main problem encountered by operators. But for the control of reheat steam temperature, since the tower typ...

AI Technical Summary

Problems solved by technology

[0005] (1) In the reheating steam temperature adjustment, the desuperheating water can only be used as accident spray water to reduce the temperature. When the desuperheating water of the reheater is running, the steam flow rate of the medium and low pressure cylinders of the steam turbine will increase, and the medium and low pressure cylinders will increase accordingly. Power, which is equivalent to adding a medium-pressure (Rankine) cycle to the ultra-supercritical reheat cycle of the unit, resulting in a decline in the economy of the entire unit;

[0006] (2) The method of adjusting the steam temperature by the swing angle of the burner is to change the reheat steam temperature by adjusting the position of the center of the furnace flame. It is prone to accelerated wear and even burning, which is not conducive to the safe operation of the equipment. Moreover, the center of the flame is too high, and the residence time of the pulverized coal in the furnace is too short, which will lead to an increase in the carbon content of the fly ash and reduce the efficiency of the boiler. In addition, the adjustment range of this method It is also limited, some boilers even when the burner swing angle is adjusted upward to the limit, the reheat steam temperature is still low;

[0007] (3) The trapezoidal distribution of the coal feed is also equivalent to adjusting the furnace flame center, which will also have an impact on the combustion of the boiler, resulting in an increase in the carbon content of the fly ash. In addition, this method is also limited by the load during operation and the upper coal pulverizer Output, adjustment means and range are limited;

However, for the main steam temperature, it can always be adjusted to the rated value by adjusting the coal-water ratio under normal circumstances, but for the reheat steam temperature, there is often a lack of key adjustment means

[0012] In addition, because many power plants include the main steam temperature and reheat steam temperature in the assessment scope, the operating personnel increase the number of soot blowing in order to avoid being assessed

This will cause too much consumption of soot blowing steam, which will reduce the economic efficiency of the unit. At the same time, frequent soot blowing will easily cause damage to the heating surface and cause the unit to stop operating.