Integrated flue gas treatment device based on hollow fiber membrane

Abstract

According to the integrated flue gas treatment device based on the hollow fiber membrane, in the first stage, flue gas dust is treated to the microgram level through the hollow fiber membrane, in the second stage, adsorption and catalytic reduction or catalytic oxidation are conducted through a boiling bed, and in the third stage, further treatment is conducted through a replaceable powdery catalyst, an adsorbent fixed bed and a fixed catalyst bed embedded with membrane wires. The advantages of large specific surface area of the powdery material and accurate blocking of the hollow fiber membrane on the powdery material are fully exerted, and integrated treatment of various pollutants is realized.

Description

Technical Field

[0001] Integrated flue gas treatment device based on hollow fiber membrane. Background Art

[0002] The latest integrated dust removal, sulfur, nitrogen, mercury, and dioxin systems typically have two types: one uses a film-coated dust bag with a layer of felt containing a catalyst. This removes dust while also reducing nitrogen oxides with the synergistic effect of ammonia; the other uses a ceramic fiber filter tube made by mixing ceramic fiber and catalyst slurry and sintering it into a blank. However, both filter media share the following drawbacks: 1. They cannot remove sulfur; 2. Their dust filtration accuracy can only reach 2-10 mg / m³. While this may seem to meet "ultra-low emission" requirements, for steel mills located in close proximity to urban areas, tens of thousands of tons of dust still drift into cities annually. Only a filter with a density of 0.1-0.001 mg / m³ can meet these requirements.

[0003] Since Guo Shaohua and others invented hollow fiber membranes for treating heavily polluted flue gas dust, they have consistently achieved dust treatment accuracy down to the microgram level, even reaching 0.2 micrograms / m³, without increasing costs or wind resistance. Heavy metal levels in flue gas chimney outlets are superior to atmospheric background indicators. This technology has been included in the 2023 edition of the "National Catalogue of Major Environmental Protection Technologies and Equipment Encouraged for Development." Completely removing dust from flue gas has become a reality. Simultaneously, technologies based on these hollow fiber membranes for desulfurization, denitrification, mercury removal, and VOC treatment are also rapidly developing. Summary of the Invention

[0004] The present invention aims to leverage the technological advantages of hollow fiber membranes, beyond microgram-level dust removal, and apply them to the removal of gaseous pollutants from flue gas. This approach utilizes a combination of adsorption and catalysis, utilizing powdered materials to achieve integrated treatment of gaseous pollutants such as sulfur, nitrogen, mercury, and dioxins. This invention proposes an integrated flue gas treatment device based on hollow fiber membranes, aiming to address flue gas pollution with greater efficiency, precision, and cost-effectiveness. The integrated flue gas treatment device based on hollow fiber membrane consists of a trace dust treatment section; a fluidized bed flue gas treatment section; a fixed bed flue gas treatment section; a catalyst and adsorbent regeneration section; and an acid recovery section, and is characterized in that: the trace dust treatment section is a dust collector using hollow fiber membrane as the filter material; the fluidized bed flue gas treatment section is composed of 1 or 2 to 10 tubular fluidized bed towers connected in series; the fixed bed flue gas treatment section is equipped with a hollow fiber membrane filament array containing a catalyst, and the membrane filament has a powdered catalyst embedded in its membrane filament wall during the manufacture of the membrane filament to form a fixed bed that does not need to be replaced; the outer surface of the membrane filament is adsorbed by negative pressure A layer of powdered catalyst and adsorbent material is formed as a replaceable fixed bed; the fixed bed flue gas treatment section is equipped with a back-flushing system to blow off the saturated catalyst and adsorbent adsorbed on the surface of the membrane wire; the catalyst and adsorbent regeneration section is connected to the lower part of the fixed bed flue gas treatment section at the inlet end, receives the adsorption saturated powdered catalyst and adsorbent, heats it to 400 degrees in a nitrogen environment, and the evaporated sulfur is sent to the acid recovery section through a small dust collector. The outlet end is sent to the powdered catalyst and adsorbent silo through the powder conveying system, and the regenerated and newly replenished powdered catalyst and adsorbent are sent to the boiling bed flue gas treatment section through the conveying channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Attachment Figure 1 This is a schematic diagram of an integrated flue gas treatment device based on hollow fiber membranes. In the diagram, (011) is the trace dust treatment section; (012) is the ammonia supply system; (013) is the mixer; (014) is the fluidized bed flue gas treatment section; (015) is the fixed bed flue gas treatment section; (018) is the desorption and analysis device for the catalyst and adsorbent regeneration section; (019) is the powdered catalyst and adsorbent silo; (017) is the small dust collector; and (016) is the acid recovery section.

[0006] Attachment Figure 2 It is a cross-sectional schematic diagram of a hollow fiber membrane containing a catalyst, in which (021) is the wall of the hollow fiber membrane, in which catalyst particles are embedded; (022) is a replaceable fixed bed formed by the catalyst and adsorbent adsorbed on the outer surface of the membrane by negative pressure; (023) represents the flue gas containing various gaseous pollutants; (024) represents the reducing agent such as ammonia added to the system; (025) represents the oxidizing agent such as ozone added to the system; and (26) represents the clean flue gas after treatment. DETAILED DESCRIPTION

[0007] After the flue gas enters this device, it first passes through the (011) trace dust treatment section to completely remove the dust in the flue gas. According to previous experience, the purification level can reach 1ug / m³, creating excellent conditions for the subsequent treatment of gaseous pollutants.

[0008] The flue gas after dust removal enters the fixed bed flue gas treatment section (014) through the (013) mixer. At the same time, the reducing agent provided by the (012) ammonia supply system and the catalyst and adsorbent sent from the (019) powdered catalyst and adsorbent silo also enter the (013) mixer. These catalysts can usually be selected from vanadium, manganese, cerium, lanthanum, or perovskite powder materials, and the adsorbent can be selected from activated carbon, zeolite, activated coke and other powder materials, or a mixture of these materials. For example, through the two stages of fluidized bed and fixed bed, only powdered activated carbon can be used as the adsorbent for desulfurization. Under certain temperature conditions, the catalytic effect of the activated carbon and the reducing agent can work together to reduce nitrogen oxides at the same time.

[0009] Since the membrane fibers used in the (015) fixed bed flue gas treatment section have been added with catalysts during manufacturing, an internal catalytic fixed bed is formed, which has the dual functions of catalysis and dust interception. When the flue gas passes through the membrane fiber wall, it can cooperate with the reducing agent to further play a denitrification role, while effectively intercepting powdered materials to prevent them from being lost.

[0010] (014) The fluidized bed flue gas treatment section is equipped with a back-flushing system. When too much catalytic and adsorbent materials accumulate on the membrane wire, causing excessive wind resistance, back-flushing is performed to blow off the powdered materials and re-apply the powder.

[0011] The adsorbent that has been saturated with adsorption and the catalyst that has generated intermediates on its surface are sent to the desorption and analysis device of the catalyst and adsorbent regeneration section (018) for regeneration. The regenerated powdered material is sent to the powdered catalyst and adsorbent silo (019) for reuse through the conveying system. A direct conveying path can also be established between the mixer (013) at the bottom of the fixed bed flue gas treatment section (015) to directly recycle and reuse the material that has not yet been fully saturated.

[0012] The desorbed acid gas is condensed and recovered.

[0013] Powdered materials have a specific surface area thousands of times greater than honeycomb-shaped and granular materials, resulting in higher adsorption and desorption efficiencies. The air velocity ratio has dramatically increased from 300-500 to 10,000-20,000, saving significant material. Previously, this method was not widely adopted due to the difficulty in intercepting powdered materials. However, with the maturity of hollow fiber membrane dust removal technology, these technical barriers have been overcome, allowing the advantages of powdered materials to be fully utilized.

Claims

1. The integrated flue gas treatment device based on hollow fiber membrane consists of a trace dust treatment section; an ebullating bed flue gas treatment section; a fixed bed flue gas treatment section; a catalyst and adsorbent regeneration section; and an acid recovery section, characterized by: The trace dust treatment section is a dust collector with hollow fiber membrane as filter material; the fluidized bed flue gas treatment section is composed of 1 or 2 to 10 tubular series-connected fluidized bed towers; the fixed bed flue gas treatment section is equipped with a hollow fiber membrane array containing catalyst, and the membrane fibers have been embedded with powdered catalyst in their walls during the manufacture of the membrane fibers, forming an internal fixed bed that does not need to be replaced; a layer of powdered catalyst and adsorption material is adsorbed on the outer surface of the membrane fibers by negative pressure, serving as a replaceable external fixed bed; the flue gas treatment section is equipped with There is a backflush system to blow off the saturated catalyst and adsorbent adsorbed on the surface of the membrane fiber; the catalyst and adsorbent regeneration section, with its inlet connected to the lower part of the fixed bed flue gas treatment section, receives the adsorption-saturated powdered catalyst and adsorbent, heats it to 400 degrees in a nitrogen environment, and the evaporated sulfur is sent to the acid recovery section through a small dust collector. The outlet is sent to the powdered catalyst and adsorbent silo through a powder conveying system, and the regenerated and newly replenished powdered catalyst and adsorbent are sent to the fluidized bed flue gas treatment section through a conveying channel.

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