Boiler exhaust smoke waste-heat utilization system and control method thereof

Abstract

The invention discloses a power station boiler exhaust smoke waste-heat utilization system and a control method thereof. A composite phase-changing heat exchanger and auxiliary facilities of the composite phase-changing heat exchanger are utilized for recycling exhaust smoke waste heat of a power station boiler, the recycled heat is used for heating condensed water, supplemental water, secondary air, heating return water and the like of the boiler, different working condition control methods are adopted according to various cold source supplying situations at different seasons, working conditions can be generally divided into a self-circulation working condition, a winter working condition and a summer working condition, the closed-loop control over different lowest wall temperatures which possibly appear in the whole phase-changing heat exchanger can be achieved, the wall temperature of the phase-changing heat exchanger is kept constant or is controllable and adjustable so as to be suitable for types of fuel and changes of the working conditions, and therefore the energy-saving aim of greatly recycling smoke waste heat is achieved.

Description

technical field [0001] The present invention relates to the field of exhaust heat utilization of boilers, in particular to a utility boiler exhaust heat utilization system and its control method, which utilizes composite phase change heat exchangers and supporting facilities to recover the exhaust heat of power plant boilers, and the recovered heat is used To heat boiler condensate, supply water, secondary air, heating return water, etc., can achieve the purpose of rational use of heat, energy saving and consumption reduction, and reduction of pollutant emissions; using this control method, the entire phase-change heat exchanger equipment can be realized The closed-loop control of different minimum wall temperatures that may occur ensures that the wall temperature of the phase change heat exchanger is constant or controllable and adjustable, so as to adapt to changes in fuel types and working conditions, and achieve the energy-saving goal of greatly recovering waste heat from f...

AI Technical Summary

Problems solved by technology

[0005] However, the existing boiler exhaust waste heat utilization system and its control system or control method cannot realize the effective utilization of boiler exhaust waste heat while maintaining the combined phase conversion heat exchanger to keep the wall temperature of the metal heating surface at a relatively high temperature level. In order to achieve the goal of corrosive areas far away from the acid dew point, it is impossible to fundamentally avoid dew condensation corrosion and the resulting ash plugging, so the maintenance cost of the existing boiler exhaust waste heat utilization system is relatively high

Another shortcoming of the prior art is that the minimum wall temperature of the metal heating surface of the heat exchanger cannot be controlled and adjustable, the adjustment ability of the composite phase change heat exchanger is limited, the exhaust gas temperature and the wall temperature cannot be kept relatively stable, and cannot adapt to Boiler fuel types and load changes

The above shortcomings make the phase change heat exchanger prone to aging problems, and the service life of the equipment is limited

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