A method and system for controlling the main steam temperature of a power generation boiler based on multivariable decoupling

Abstract

The invention discloses a method and system for controlling the main steam temperature of a power generation boiler based on multivariable decoupling, and belongs to the technical field of thermal power generation boiler combustion optimization. Aiming at the problem that the control of the main steam temperature in the prior art is difficult to be popularized and applied in the actual industrial field, the present invention provides a method for controlling the main steam temperature of a power generation boiler based on multivariable decoupling. The signal acquisition module acquires the set flow rate of the furnace gas signal, low-temperature superheater outlet set temperature signal and high-temperature superheater outlet set temperature signal, the decoupling module decouples the signal obtained by the signal acquisition module, and the decoupled output signal is processed by a feedforward-feedback composite controller Regulating control, to realize controlling the output signal by adjusting the signal valve. The invention is applicable to the DCS distributed control system, realizes the stable control of the main steam temperature, can reduce the work intensity of field operators, improves the operating economy of the unit, and makes the system have strong stability.

Description

Technical field [0001] The present invention relates to the field of combustion optimization technology for thermal power generation boilers, in particular to a method and system for controlling the main steam temperature of a power generation boiler based on multivariate decoupling. Background [0002] The superheater of the power generation boiler is operated in an environment of high temperature and high pressure, and the superheated steam temperature of its outlet is one of the main parameters of the boiler operation, which has a significant impact on the safe and economic operation of the power plant. Excessive main steam temperature will reduce the operational safety of the unit. If the main steam temperature is too low, the thermal efficiency of the unit will be reduced, and the economy will not be guaranteed. At the same time, the low temperature of the main steam will increase the moisture content of the steam, thereby shortening the service life of the steam turbine. Th...

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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

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