Method for pretreating lime kiln tail gas and improving carbon dioxide concentration of tail gas

Abstract

The invention provides a method for pretreating lime kiln tail gas and improving carbon dioxide concentration of the tail gas. The method for pretreating the lime kiln tail gas comprises the following steps of choosing a selective catalytic reduction method to denitrating the lime kiln tail gas; carrying out cyclone dust removal on the denitrated tail gas; detarring the tail gas treated by cyclone dust removal through a tar removing device; carrying out spray dust removal on the detarred tail gas; sending the tail gas treated by spray dust removal into a desulfuration dust removal device through the bottom of the desulfuration dust removal device, simultaneously spraying CaCO3 dispersion liquid from the top to be contacted with the tail gas, and exhausting the tail gas from the top of the desulfuration dust removal device; sending the tail gas exhausted from the desulfuration dust removal device into a gas-water separator to remove moisture; and carrying out electric dust removal on the moisture-removed tail gas. The impurity content of the lime kiln tail gas treated by the method can meet processing requirements of a pressure swing adsorption system for CO2 purification. Furthermore, NOx is treated into nitrogen and water, equipment safety is improved, and equipment corrosion is avoided.

Description

technical field [0001] The invention relates to the field of hydrometallurgy and waste gas comprehensive utilization, in particular to a method for pretreating lime kiln tail gas and improving CO in lime kiln tail gas. 2 method of concentration. Background technique [0002] With the development of industrialization process, containing CO 2 The emission of harmful substances such as CO is increasing, which has brought great harm to the environment, especially CO 2 The impact of excess emissions on the global warming effect is well known. On the other hand, CO 2 It is a very valuable carbon resource. If it can be used effectively, it will not only reduce CO 2 The greenhouse effect caused by emissions can also make up for the "carbon source crisis" caused by the massive consumption of oil and natural gas, and realize the reduction of CO on the earth. 2 virtuous circle. Therefore, the emitted CO 2 Recycling, fixation, utilization and re-recycling have become a matter of ...

AI Technical Summary

Problems solved by technology

[0006] Due to the complex composition and high impurity content of lime kiln tail gas, the current research on the use of pressure swing adsorption technology to purify lime kiln tail gas and enrich CO 2 There are not many research reports, and there are no industrial success stories in the country

[0007] The process of lime kiln tail gas treatment that has been reported and applied is usually to remove lime kiln tail gas by cyclone first, then spray, activated carbon adsorption, electrostatic precipitator (bag dust removal), etc., for example, the authorized announcement number is CN201930680, and the name is The Chinese patent of "lime kiln gas purification system" discloses a combined process using cyclone dust collector + spray + coke filter + electric dust removal, but the disadvantage of this process is that the impurity treatment process is single and the depth is not enough, even if it can meet the atmospheric Emission standards, but can not meet the use of pressure swing adsorption to purify CO 2 process requirements

In addition, the Chinese patent with the authorized announcement number CN202460402 and the name "A Lime Kiln Gas Purification Tower" discloses a combined process using water tank + limestone filling layer + spray + wire mesh demister. The processing efficiency is higher, but for SO 2 The removal effect of tar and tar is not large; the patent No. is ZL200820016124.9, and the Chinese patent of " environmental protection and energy-saving lime kiln desulfurization dust remover " by name discloses a kind of technology that adopts multistage lime water to lime kiln gas treatment, although SO 2 The treatment efficiency is high, but it is difficult to remove small particles of dust and tar, and it will still cause environmental pollution when discharged into the atmosphere. During recycling, it will give subsequent tail gas CO 2 Difficulty using process

[0008] In order to improve environmental protection, the standards for nitrogen oxide emissions have been introduced, but the current lime kiln tail gas treatment technology does not involve the means to reduce and remove nitrogen oxides. Even if the lime kiln tail gas is treated according to the above technology, it is difficult Meet the emission requirements of nitrogen oxides

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