Flue gas heat energy utilization system and control method thereof

Abstract

The invention discloses a flue gas heat energy utilization system and a control method of the flue gas heat energy utilization system. The flue gas heat energy utilization system comprises an air preheater. The air preheater comprises an inner loop air bin, a flue gas branch bin communicating with a flue and air branch bins communicating with air ducts. An inlet of the inner loop air bin communicates with an outlet through an inner loop air duct. Inner loop air circulates between the inner loop air bin and the inner loop air duct. The flue gas heat energy utilization system further comprises aregenerative steam-water system and a first heat exchanger communicating with the regenerative steam-water system. A second heat exchanger is arranged on the inner loop air duct. When the flue gas heat energy utilization system is in a daily energy-saving mode, the second heat exchanger communicates with the regenerative steam-water system, and working medium water of the regenerative steam-watersystem enters the first heat exchanger and the second heat exchanger and exchanges heat with inner loop air in the two heat exchangers. In this way, flue heat is transmitted to the working medium water of the steam-water system in an indirect heat exchange manner, part of high-quality steam for heating the working medium water is squeezed out and returns back to a steam machine to do action, andthe function of lowering the power supply coal consumption is played.

Description

technical field [0001] The invention relates to the technical field of energy saving and environmental protection, in particular to a flue gas heat energy utilization system and a control method thereof. Background technique [0002] With the widespread use of SCR denitrification devices in coal-fired power plants, the SO in flue gas is caused by vanadium catalysts. 3 The large increase in emission concentration, and the escape of ammonia caused by the poor operation of the SCR denitrification device, etc., the two react to form ammonium bisulfate (ABS). The liquid temperature range of ammonium bisulfate is about 146°C to 207°C. When the flue gas flows above the conventionally designed cold end layer and below the middle layer of the air preheater, the strong adsorption of liquid ammonium bisulfate will cause a large amount of ash to settle Causes clogging on metal surfaces and gets stuck between layers. [0003] The deposition of ammonium bisulfate and ash in the air preh...

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Problems solved by technology

However, during its use, because the flue gas has not been dedusted, the dust concentration is very high, which will cause more wear and tear on the heat exchange surface and cause leakage; the fly ash in the flue gas will be deposited on the heat exchange surface to a greater extent. The heat transfer coefficient affects the heat transfer efficiency; the heat transfer tube bundle in the ammonium bisulfate liquid zone is also the same as the air preheater, which will cause ammonium bisulfate adhesion, fly ash deposition, low-temperature corrosion, etc., resulting in a decrease in heat transfer efficiency and flue gas problems such as increased resistance

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