Power generating boiler main steam temperature control method and system based on multivariable decoupling

Abstract

The invention discloses a power generating boiler main steam temperature control method and system based on multivariable decoupling and belongs to the technical field of thermal power generation boiler combustion optimization. Specific to the problem that in the prior art, control over the main steam temperature is hardly applied and popularized in a practical industry field, the power generatingboiler main steam temperature control method based on multivariable decoupling is provided. A signal obtaining module is used for obtaining a hearth gas amount set flow signal, a low-temperature overheater outlet set temperature signal and a high-temperature overheater outlet set temperature signal, a decoupling module is used for decoupling the signals obtained by the signal obtaining module, decoupled output signals are adjusted and controlled through a feedforward-feedback composite controller, and the output signals can be controlled by adjusting a signal valve. The power generating boiler main steam temperature control method and system are suitable for a DCS distributed control system, stable control over the main steam temperature is achieved, the work intensity of field running persons can be relieved, the running economical efficiency of a unit is improved, and the system has high stability.

Description

technical field [0001] The invention relates to the technical field of thermal power boiler combustion optimization, in particular to a method and system for controlling the main steam temperature of a power boiler based on multivariable decoupling. Background technique [0002] The superheater of the power generation boiler operates in a high temperature and high pressure environment, and the temperature of the superheated steam at its outlet is one of the main parameters of the boiler operation, which has a significant impact on the safe and economical operation of the power plant. Excessive main steam temperature will reduce the operating safety of the unit. If the main steam temperature is too low, the thermal efficiency of the unit will be reduced, and the economy cannot be guaranteed. At the same time, low main steam temperature will increase the water content of the steam, thereby shortening the service life of the steam turbine. Therefore, the main steam temperatur...

AI Technical Summary

Problems solved by technology

The main feature of the optimized automatic control technology based on the main steam temperature model is that according to the temperature requirements of grade I and II, when the main steam temperature is the set value, feed-forward compensation is added to predict the change trend of the main steam temperature in advance, and the I The flow rate of the first-stage desuperheating water and the second-stage desuperheating water are adjusted without considering the increase in the furnace outlet temperature adjustment load. As the load increases, the water flow on the steam drum will increase correspondingly, and the outlet temperature of the furnace will also increase due to the increase in fuel. , because the main water supply pipe of the desuperheating water circuit and the water supply circuit of the steam drum is the same, the increase of the water flow of the steam drum will inevitably lead to a decrease in the pressure of the water pipe of the circuit supplying the desuperheating water, and the amount of desuperheating water required will also decrease at the same time. The temperature of grade I and grade II will also increase indirectly, causing the main steam temperature to not be adjusted in time

[0007] At present, although there are many advanced control technologies for main steam temperature, such as prediction technology, fuzzy technology, neural network technology, etc., the above-mentioned technologies are more theoretical, with many academic articles, mainly simulation verification, and poor engineering field applicability. Although there are on-site application examples, they are highly specific to individual cases and poor in popularization and promotion, which is not conducive to on-site commissioning of projects

Images