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System and method for avoiding low temperature corrosion of air preheater by using phase change heat

An air preheater, low temperature corrosion technology, applied in combustion methods, lighting and heating equipment, indirect carbon dioxide emission reduction, etc. High problems, to achieve the effect of reducing heat exchange area, reducing power consumption, and reducing investment

Active Publication Date: 2015-09-09
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention proposes a system and method for avoiding low-temperature corrosion of an air preheater by using phase-change heat. The preheater is subjected to high temperature and high pressure, the water pump consumes a lot of power, and the investment and operation costs are high, which is especially unfavorable to the biomass generator set

Method used

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  • System and method for avoiding low temperature corrosion of air preheater by using phase change heat

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specific Embodiment approach 1

[0018] Specific implementation mode one: as figure 1 As shown, the system for avoiding low-temperature corrosion of the air preheater by using phase-change heat, the system for avoiding low-temperature corrosion of the air preheater by using phase-change heat includes a flue gas cooler 1, a steam-water separator 2, and a steam drum 3 , steam-air heat exchanger 4, air preheater 5, boiler flue 6, low-pressure circulation pump 7, mixer 8 and safety valve 9, boiler flue 6 is arranged at the boiler flue gas outlet, and the flue gas The outlet of the steam and water mixture in the cooler 1 is connected to the inlet of the steam-water separator 2 arranged in the steam drum 3 through a pipeline, and a safety valve 9 is arranged above the steam drum 3, and the steam outlet of the steam drum 3 is connected to the steam-air The steam inlet of the heat exchanger 4 is connected, the condensed water outlet of the steam-air heat exchanger 4 and the downcomer 10 of the steam drum 3 are connec...

specific Embodiment approach 2

[0021] Specific implementation mode two: as figure 1 As shown, the method for avoiding low-temperature corrosion of the air preheater is realized by using the system described in the first embodiment, and the steps of the method are:

[0022] Step 1: The working medium water is heated in the flue gas cooler 1 to obtain a mixture of steam and water. The heating temperature is 102-120°C and the pressure is 0.11-0.20MPa. The steam-water mixture is separated into steam and water by the steam-water separator 2 Separation to obtain saturated steam with a pressure of 0.11-0.20Mpa and a temperature of 102-120°C. The saturated steam is sent into the steam-air heat exchanger 4 through the steam pipeline 11 to exchange heat with the air, and the air is heated to 80-90°C;

[0023] Step 2: On the one hand, the air heated in Step 1 is sent into the air preheater 5 to exchange heat with the hot flue gas to obtain high-temperature air at 200-220°C, and the high-temperature air is sent into th...

Embodiment 1

[0025] Such as figure 1Shown: Taking a 30MW biomass boiler as an example, when the flue gas dew point temperature is lower than 95°C: the working medium (water) is heated in the flue gas cooler 1 to obtain a mixture of steam and water, the heating temperature is 102°C, and the pressure is 0.11 MPa, the steam-water mixture is separated by steam-water separator 2 to obtain saturated steam and saturated water at the pressure and temperature, and saturated steam (pressure 0.11Mpa, temperature 102°C) is sent into steam- The air heat exchanger 4 exchanges heat with the air, and the air is heated to 87-90°C. The hot air is sent into the air preheater 5 to exchange heat with the hot flue gas to obtain high-temperature air at 215-220°C. The high-temperature air is sent to Putting it into the boiler for combustion support can save boiler fuel by 2.0-2.5%. Saturated steam (at a pressure of 0.11MPa and at a temperature of 102°C) undergoes phase-change heat in the steam-air heat exchanger ...

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Abstract

The invention discloses a system and a method for avoiding low-temperature corrosion of an air preheater by using phase-change heat exchange, and belongs to the field of biomass energy utilization. The system and the method aim to solve the problems that boiler high-temperature and high-pressure water supply is used as a heat source to preheat air, the air preheater occupies large area and bears high temperature and high pressure, a water pump consumes a large amount of electricity, and the investment and running cost are high. A fume cooler is connected with steam separators arranged in a steam drum; the steam drum is connected with a steam-air heat exchanger; the steam-air heat exchanger and the steam drum are connected with a mixer; the mixer is connected with the fume cooler via a low-pressure circulation pump; the steam-air heat exchanger is connected with the air preheater. Saturated water and thermal fume exchange heat in the fume cooler to obtain a steam water mixture, the fume exhausting temperature is lowered, the steam water mixture is separated via the steam separators to obtain saturated steam and the saturated steam is used as a steam-air exchanger heat source to preheat the air, as a result, the inlet air temperature of the air preheater is raised, and the low-temperature corrosion of the air preheater is avoided. The system and the method are applied to biomass-fired boilers or coal-fired (higher sulphur content) boilers.

Description

technical field [0001] The invention relates to a system and method for avoiding low-temperature corrosion of an air preheater, belonging to the field of biomass energy utilization. Background technique [0002] In the prior art, the air preheater is mostly installed in the tail flue of the boiler, and the flue gas and cold air are used to exchange heat. When biomass is used as fuel, the content of chlorine and alkali metals in the flue gas is high, so the air preheating The heating surface on the flue gas side of the boiler is prone to low-temperature corrosion and ash accumulation, the heat transfer effect is reduced, the boiler efficiency is reduced, and the power consumption and operating costs are increased, which seriously affects the normal operation of the biomass-fired boiler. In order to avoid the low-temperature corrosion of the air preheater, the Chinese patent announcement number is CN1619246, the publication date is May 25, 2005, and the patent application numb...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F23L15/00
CPCY02E20/34
Inventor 别如山宋兴飞纪晓瑜刘茜茜陈佩
Owner HARBIN INST OF TECH
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