Heat exchanger for waste heat recovery of coal-fired boiler

Abstract

The invention discloses a heat exchanger for waste heat recovery of a coal-fired boiler. The design concept combining a section-separated heat transfer enhancement principle and a technology for flexibly adjusting the tube wall temperature through graded water supply is adopted, the heat exchanger is divided into a high-temperature section adopting carbon steel and a low-temperature section adopting ND steel, tube bundles are staggered, media inside and outside tubes are in a counter-flow type, the tube wall temperature of the high-temperature section and the low-temperature section is adjusted precisely in a graded water supply manner, so that the tube wall temperature is higher than the acid dew point temperature of flue gas throughout, and a low-temperature corrosion relieving effect is realized. The technical problems of low heat transfer temperature pressure and serious low-temperature acid-dew-point corrosion in low-temperature flue gas waste heat recovery of the coal-fired boiler are solved very well, by means of combination of section-separated heat transfer enhancement and flexible adjustment of the tube wall temperature through graded water supply, the heat exchange performance and the anti-corrosion effect of the low-temperature heat exchanger are improved obviously, the efficiency and the economical efficiency of the low-temperature flue gas waste heat recovery of the coal-fired boiler are improved substantially, and the heat exchanger has good social and economic benefit and great industrial application and popularization potential.

Description

technical field [0001] The invention relates to a heat exchanger for waste heat recovery of a coal-fired boiler, which is suitable for the field of low-temperature waste heat recovery and utilization. Background technique [0002] During the operation of coal-fired industrial boilers, the heat loss of exhaust flue gas is the largest of all heat losses. During long-term operation of domestic boiler units, the exhaust gas temperature is generally higher than the design value, generally between 160 and 180 °C. Emissions take away a lot of waste heat. Most industrial boilers do not make full use of these waste heat resources in the production process. If this part of waste heat can be recovered, the energy saving effect will be very considerable. For every 15℃ decrease in exhaust gas temperature, the boiler efficiency increases by about 1%. Low-temperature waste heat recovery is an energy-saving technology widely used in the coal-fired power generation industry at home and abro...

AI Technical Summary

Problems solved by technology

Boiler exhaust heat is a low-grade waste heat resource. There are two major problems in recycling and utilization: poor heat transfer performance and low-temperature dew point corrosion. These two problems make the recovery and utilization of boiler exhaust heat difficult and increase the cost of renovation and maintenance. Limit the popularization and use of cryogenic heat exchangers to a great extent

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