Ultralow emission process for catalytic cracking smoke

Abstract

The invention provides an ultralow emission process for catalytic cracking smoke, comprising the following steps of: introducing an addition agent in a catalytic cracking catalyst, reducing Sox and NOx content in the catalytic smoke in a lower cost maximally, wherein the maximum concentration of NOx in the smoke does not exceed 400mg / m3; high temperature flue gas from a heat recovery boiler of a catalytic cracking device contacts with a circulation slurry in an urgent cooling desulfurizing tower to cool, dedust and desulfurize; the maximum concentration of the desulfurized smoke Sox does not exceed 150mg / m3; the desulfurized smoke enters the bottom ofa denitrating tower by a dustproof defroster to be in reverse contact with a denitrating solution; the denitrated smoke is evacuated after being removal of the fog; Soxin the smoke basically realizes zero emission; and when NOx content is below 30mg / Nm3, the purpose of ultralow emission is realized.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a catalytic cracking flue gas ultra-low emission process. Background technique [0002] FCC (catalytic cracking) unit is one of the largest sources of pollutant emissions in refineries. In order to meet the requirements of environmental protection control indicators and emission reduction targets, the emissions of SOx and NOx from catalytic cracking flue gas must be strictly controlled. At present, the main method for refineries to control the emission of harmful gases such as SOx and NOx in catalytic cracking flue gas is flue gas purification. FCC flue gas desulfurization technologies that have been industrialized in China include sodium-alkali desulfurization, renewable wet flue gas desulfurization, and denitrification technologies include SCR denitrification and ozone oxidation absorption denitrification. [0003] Sodium-alkali desulfurization is currently the most ...

AI Technical Summary

Problems solved by technology

SCR denitrification technology has been successfully applied to flue gas denitrification of catalytic cracking units, but the problem of low sulfur resistance of low-temperature SCR catalysts has not been solved, so medium-temperature SCR technology is currently used for flue gas denitrification of catalytic cracking units

The catalytic cracking unit designed in the 20th century basically did not reserve the position of the flue gas denitrification unit, and the flue gas temperature at the outlet of the waste heat boiler of the catalytic cracking unit is generally 180-230 ° C. It is necessary to put the denitrification part into the catalytic waste heat boiler, which increases the engineering implementation. Difficulty, which has a great influence on the structure of the catalytic waste heat boiler

However, the desulfurization and denitrification efficiency of the auxiliary method is low, unstable, poor adaptability to raw materials, and the SOx and NOx contents in the catalytic flue gas are difficult to meet the emission standards at the same time. , NOx emission standards at the same time become more difficult to achieve

Images