CN-117772294-B - SCR catalyst in-situ regeneration system and method

CN117772294BCN 117772294 BCN117772294 BCN 117772294BCN-117772294-B

Abstract

The invention discloses an SCR catalyst in-situ regeneration system and method, and relates to the technical field of flue gas purification. According to the invention, the existing denitration tower is modified, and the reverse blowing system, the cleaning system, the flue gas heating system and the cleaning solution recovery system are respectively arranged in the denitration tower, the reverse blowing system cleans deposited ash on the surface of the catalyst module and in the pore canal through high-pressure blowing, the regenerated liquid cleaning system cleans dirt in the catalyst through different cleaning solutions, and the flue gas heating system promotes the evaporation of water of the cleaned catalyst and the decomposition of a precursor of a catalyst surface active component, so that catalyst regeneration is realized. The method has the advantages of less time consumption and low cost, can utilize the time of routine maintenance of the system to complete the regeneration of the catalyst, has good regeneration effect, can thoroughly remove fly ash, alkali metal, alkaline earth metal and heavy metal on the catalyst, and solves the problem of catalyst poisoning caused by the method.

Inventors

LU LIJUN
ZHANG LUJUN
FU BENQUAN
LUO YONG

Assignees

武汉钢铁有限公司

Dates

Publication Date: 20260505
Application Date: 20231116

Claims (6)

1. The SCR catalyst in-situ regeneration system is characterized by being arranged between an air inlet and an air outlet of a denitration tower and comprising a back blowing system, a cleaning system, a flue gas heating system and a cleaning liquid recycling system, wherein the back blowing system is used for removing deposited ash on the surface and in the interior of a catalyst; the cleaning system is used for cleaning the catalyst, the flue gas heating system is used for promoting the evaporation of water in the cleaned catalyst and the decomposition of a precursor of a catalyst surface active component to realize the regeneration of the catalyst, and the cleaning liquid recycling system is connected with the cleaning system and is used for recycling the cleaning liquid; the cleaning system comprises a plurality of cleaning units which are connected in parallel, a regeneration pump and a cleaning nozzle, wherein the cleaning units, the regeneration pump and the cleaning nozzle are connected through cleaning pipelines, and the cleaning nozzle is opposite to the catalyst; The cleaning units in parallel connection comprise a water washing unit, an acid washing unit, an alkali washing unit and an active restoration unit which are connected in parallel, wherein the water washing unit is used for removing accumulated ash and water-soluble pollutants in the catalyst; The washing unit comprises a washing tank, wherein deionized water and a surfactant are contained in the washing tank, the acid washing unit comprises an acid washing tank, a sulfuric acid solution is contained in the acid washing tank, the alkaline washing unit comprises an alkaline washing tank, an ammonia water solution and ammonium carbonate are contained in the alkaline washing tank, the activity repairing unit comprises an activity repairing tank, and ammonium metavanadate and ammonium paratungstate are contained in the activity repairing tank; The washing tank, the pickling tank, the alkaline washing tank and the active repair tank are respectively provided with an inlet valve and an outlet valve at the front and back, the inlet valves are connected with the discharge port of the cleaning liquid recycling system through pipelines, and the outlet valves are connected with the regeneration pump; The circulating recovery system comprises an inclined plate and a discharge port, the discharge port is arranged at the bottom of the denitration tower, one end of the inclined plate is arranged at the bottom of the catalyst, and the other end of the inclined plate is close to the discharge port and is positioned 1 cm-3 cm below the discharge port; the regeneration system also includes an ultrasonic generator disposed at the catalyst end.
2. The SCR catalyst in situ regeneration system of claim 1, wherein the catalyst comprises n denitration units, the back-blowing system comprises a high pressure fan and n back-blowing nozzles connected to the high pressure fan, the back-blowing nozzles facing the denitration units.
3. The SCR catalyst in situ regeneration system of claim 1, wherein the cleaning nozzle employs an atomizing nozzle.
4. An SCR catalyst in-situ regeneration method, which is realized by the SCR catalyst in-situ regeneration system according to any one of claims 1-3, comprising the following steps: closing an air inlet air door and an air outlet air door of the denitration tower, and sweeping the catalyst by adopting a back blowing system; the catalyst is cleaned by a cleaning system, and a cleaning liquid recycling system is adopted to recycle the cleaning liquid; Opening a flue gas heating system, drying the catalyst, and activating the catalyst; And (3) completing the in-situ regeneration process of the SCR catalyst, and opening an air inlet air door and an air outlet air door of the denitration tower.
5. The method for in-situ regeneration of the SCR catalyst according to claim 4, wherein the step of purging the catalyst by a back-blowing system comprises the steps of turning on a back-blowing high-pressure fan, adjusting the blowing pressure, and turning off the back-blowing fan after the catalyst is purged for a preset time by a back-blowing nozzle; the method comprises the steps of cleaning a catalyst by using a cleaning system and recovering the cleaning solution by using a cleaning solution circulating recovery system, and specifically comprises the steps of opening an inclined plate and a drain, and cleaning and repairing the catalyst by sequentially adopting a water washing unit, an acid washing unit, an alkali washing unit and an activity repairing unit; The method comprises the steps of starting a heater, controlling the temperature to be the drying temperature, drying the moisture of the catalyst, controlling the temperature to be the activation temperature, and activating the catalyst.
6. The SCR catalyst in-situ regeneration method of claim 5, wherein the sonicator is turned on before the catalyst is washed and repaired using a water wash unit, an acid wash unit, an alkaline wash unit, and an active repair unit in sequence.

Description

SCR catalyst in-situ regeneration system and method Technical Field The invention relates to the technical field of flue gas purification, in particular to an SCR catalyst in-situ regeneration system and method. Background The SCR selective catalytic reduction denitration technology has the advantages of high denitration efficiency, mature technology and reliable performance, and is the mainstream technology for removing NOx from industrial flue gas at present. At present, the catalyst deactivation is a main problem in the operation process of the SCR denitration technology, the catalyst cost is about 50% of the total engineering cost, and the theoretical service life of the common vanadium-titanium catalyst is generally less than 3 years, so that tens of thousands of tons of waste denitration catalysts can be produced every year throughout the country. The recycling of deactivated denitration catalyst is therefore the main solution. The main causes of catalyst deactivation are plug deactivation, high temperature sintering deactivation, poisoning deactivation and active component loss. The common catalyst regeneration methods include negative pressure ash absorption, compressed air purging, high-pressure water flushing, ultrasonic cleaning, chemical cleaning, active component impregnation and the like. The regeneration process is divided into in-situ regeneration and ex-situ regeneration. Wherein the ex-situ regeneration requires that spent catalyst be removed from the system and sent to a professional regeneration company for processing, which is time consuming, costly, and affects the continuous operation of the SCR system. The in-situ regeneration technology well avoids the defects and represents the development direction of the SCR catalyst regeneration technology. Several methods and systems for flue gas treatment of an on-line SCR catalyst have been disclosed in some in-situ regeneration technologies, such as patent CN112169581a, to realize synchronous thermal regeneration and denitration of the SCR catalyst, and the system can operate normally without stopping. Patent (CN 216630873U) is an on-line regeneration device for SCR catalyst of coal-fired power plant, comprising an SCR catalyst mounting frame, a dry ice preparation system, an air injection system, a regeneration liquid injection device, a heating device and an ultrasonic device, wherein the regeneration device can realize the regeneration of catalyst only by refitting an on-site flue. In the prior art, either the thermal regeneration is adopted or the existing SCR flue refitting method is adopted, and the problems that the regeneration effect is poor and the continuous operation of the SCR system is affected are all existed. Disclosure of Invention The application provides an in-situ regeneration system and method of an SCR catalyst, which aim to solve the technical problems that the in-situ regeneration effect of the existing SCR catalyst is poor and the continuous operation of the SCR system is influenced. The application provides an SCR catalyst in-situ regeneration system which is arranged between an air inlet and an air outlet of a denitration tower and comprises a back blowing system, a cleaning system, a flue gas heating system and a cleaning liquid recycling system, wherein the back blowing system is used for cleaning deposited ash on the surface and in the catalyst, the cleaning system is used for cleaning the catalyst, the flue gas heating system is used for promoting the evaporation of water of the cleaned catalyst and the decomposition of a precursor of a catalyst surface active component to realize catalyst regeneration, and the cleaning liquid recycling system is connected with the cleaning system and is used for realizing cleaning liquid recycling. Optionally, the flue gas heating system comprises a heater, the heater being disposed at an end of the catalyst. Optionally, the catalyst comprises n denitration units, the back-blowing system comprises a high-pressure fan and n back-blowing nozzles connected to the high-pressure fan, and the back-blowing nozzles are opposite to the denitration units; the cleaning system comprises a plurality of cleaning units which are connected in parallel, a regenerating pump and a cleaning nozzle, wherein the cleaning units, the regenerating pump and the cleaning nozzle are connected through cleaning pipelines, and the cleaning nozzle is opposite to the catalyst. Optionally, the back-blowing nozzle is 10 cm-20 cm away from the catalyst, and the cleaning nozzle is 5 cm-15 cm away from the catalyst. Optionally, the plurality of parallel cleaning units comprise a water washing unit, an acid washing unit, an alkali washing unit and an active repair unit which are connected in parallel, wherein the water washing unit is used for removing dust deposit and water-soluble pollutants in the catalyst, the acid washing unit and the alkali washing unit are used for removing water-insoluble dirt in the cataly