Method and device for removing low-concentration sulfur dioxide in flue gas

Abstract

The invention belongs to the technical field of flue gas desulfurization, in particular to a method and device for removing low-concentration sulfur dioxide in flue gas, thereby solving the shortcomings in the existing flue gas desulfurization process. A citric acid-sodium citrate buffer solution is taken as an absorption solution, a rotary packed bed is taken as an absorption reactor, and the method comprises the steps of opening the rotary packed bed, leading the absorption solution and the flue gas containing the sulfur dioxide to enter into the rotary packed bed, leading a liquid phase and a gas phase to conduct the contact reaction, and leading the liquid phase after the reaction to enter into a desorption system for desorption. The device comprises the rotary packed bed, a gas inlet of the rotary packed bed is connected with a source of the flue gas containing the sulfur dioxide, a liquid inlet of the rotary packed bed is connected with the source of the absorption solution, and a liquid outlet of the rotary packed bed is connected with the desorption system. By adopting the method, the desulfurization efficiency is high, the absorption solution is renewable, and the method can be flexibly used in an acid-making system or systems for producing sulfur and the like; furthermore, the device can reduce scale formation and blockage of the device, be conductive to improving the absorption efficiency and the desorption rate of the absorption solution and reduce the investment and the operation cost.

Description

technical field [0001] The invention belongs to the technical field of flue gas desulfurization, and specifically relates to a method and a device for removing low-concentration sulfur dioxide in flue gas by using a citric acid-sodium citrate buffer solution as an absorbent and a high-gravity rotating packed bed as an absorption reactor. Background technique [0002] Sulfur dioxide in flue gas is extremely harmful to animals, plants and the ecological environment, especially for low-concentration sulfur dioxide. Due to its high content in flue gas and low treatment benefits, its effective treatment has become a major problem for a long time. Currently governing SO in the world 2 The main technical means of pollution is flue gas desulfurization. There are more than 200 kinds of flue gas desulfurization technologies researched, developed and used in various countries, of which about 20 kinds have been industrialized, and wet desulfurization is the main method. The principle is...

AI Technical Summary

Problems solved by technology

Currently governing SO in the world 2 The main technical means of pollution is flue gas desulfurization. There are more than 200 kinds of flue gas desulfurization technologies researched, developed and used in various countries, of which about 20 kinds have been industrialized, and wet desulfurization is the main method. The principle is mostly based on alkali Absorbents absorb sulfur dioxide in flue gas, such as lime / limestone / gypsum method, ammonia method, etc. Most of the absorption equipment in these processes is tower equipment, which has problems such as large equipment volume, large floor area, high operating costs, and desulfurization The post-desulfurization products cannot be effectively treated. Even if some products have certain utilization value, most of them need to go through a series of processing before they can be used, and the development of their sales has become a big burden, so most of the desulfurization products are discarded. It only converts gas pollution into solid pollution, and causes waste of sulfur resources

[0003] Sodium citrate method flue gas desulfurization process belongs to renewable flue gas desulfurization process. Its absorption liquid has low vapor pressure and is non-toxic, which can effectively absorb sulfur dioxide in flue gas. The rich liquid after absorbing sulfur dioxide can be desorbed by steam heating and other methods to produce High-concentration sulfur dioxide is used as other chemical raw materials. After desorption, the barren liquid is continued to be used in the absorption process, which not only avoids secondary pollution, but also saves sulfur resources. However, most of the existing sodium citrate flue gas desulfurization processes use tower equipment for absorption. Not only is it bulky, it increases the investment and operation costs, but also the side reaction of sulfite radical oxidation is serious during the absorption process, and it is easy to generate a large amount of sodium bisulfite or sodium sulfate, which is not only easy to scale, block the equipment, and affect the normal operation of the equipment. Moreover, the removal rate and desorption rate of the absorption liquid are reduced, the service life of the absorption liquid is shortened, and the operating cost is increased, thereby limiting its popularization and application.

[0004] Currently, some methods of removing sulfur dioxide by citrate method under the action of ultrasonic waves are disclosed. Chinese patent CN 1672775A discloses a device and method for removing sulfur dioxide in gas by combining ultrasonic waves and hollow fiber impregnated liquid membranes. The absorption of sulfur dioxide in the sodium citrate method flue gas desulfurization process has the characteristics of high absorption depth and high sulfur dioxide removal rate compared with conventional filler absorption and hollow fiber impregnated liquid membrane absorption; Chinese patent CN1660761A, patent CN100386303C and patent CN1736551A disclose respectively A method for removing sulfur dioxide in citrate solution, that is, applying ultrasonic separation technology, multiple frequency ultrasonic separation technology and microwave technology to the desorption process of sulfur dioxide in the sodium citrate flue gas desulfurization process, replacing the traditional steam heating desorption , aiming at reducing the desorption temperature, reducing the generation of sulfate radicals and the deterioration of the absorption liquid; although these devices and methods are improved compared with the traditional tower equipment, the absorption and desorption operation process is not completely continuous, and the absorption liquid absorbs after a certain period of time. This semi-continuous operation is not conducive to industrial control, and the flue gas treatment capacity of the hollow fiber membrane absorption method is also limited to a certain extent.

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