Spray Drying Apparatus Sulfuric Acid Mist Collection

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Solution Overview

Problem

In air pollution control systems, sulfuric acid mist generated during the spray-drying of desulfurization wastewater can condense and cause corrosion or blockages, and is not efficiently collected, especially in coal combustion boiler flue gases with high sulfur content, leading to potential atmospheric release of fine sulfuric acid particles.

Innovation Solution

Increasing the powder concentration in the branch gas used for spray drying to adhere and collect sulfuric acid mist, using a powder supply apparatus to introduce materials like limestone, soot, or dust into the flue gas stream before it enters the spray drying apparatus, thereby adhering and removing the sulfuric acid mist.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If spray drying is performed using branch gas from flue gas, then desulfurization wastewater is dried and eliminated, but sulfuric acid mist condenses and causes corrosion or blockage

Engineering Contradiction:
Improvewastewater eliminationVSAvoidcorrosion and blockage from sulfuric acid mist
Core Design Contradiction:
Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary substance (powdered adsorbent material) into the branch gas stream to mediate the interaction between sulfuric acid mist and the drying process. The powder acts as a mediator that captures sulfuric acid mist through adsorption, preventing direct condensation and corrosion while maintaining the spray drying function for wastewater elimination

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If spray drying is performed using branch gas from flue gas, then desulfurization wastewater is dried, but fine sulfuric acid mist is released to atmosphere without collection

Engineering Contradiction:
Improvewastewater drying efficiencyVSAvoidatmospheric release of sulfuric acid mist
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The powdered adsorbent material serves as an intermediary that captures fine sulfuric acid mist particles during the spray drying process. The powder provides a large surface area for adsorption, enabling the system to both dry wastewater efficiently and capture harmful mist before atmospheric release

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If powder is added to branch gas to collect sulfuric acid mist, then collection efficiency increases, but device complexity increases

Engineering Contradiction:
Improvesulfuric acid mist collection efficiencyVSAvoidpowder supply system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system utilizes the existing flue gas flow and spray drying infrastructure to deliver and distribute the powdered adsorbent material throughout the branch gas stream. The flue gas itself serves as the transport medium for the powder, eliminating the need for complex dedicated powder delivery systems while maintaining effective mist collection

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Effectively reduces the amount of sulfuric acid mist in the flue gas and prevents corrosion and atmospheric release by ensuring the sulfuric acid mist adheres to the powder, enhancing the collection efficiency and preventing equipment damage.

Implementation Method 1

a powder supply apparatus for supplying powder into the branch gas

Methodology Applied
Scientific EffectParticle concentration:

Implementation Method 2

the SO3 gas reaches a dew point and is thus condensed. The condensed SO3 flies in the equipment on the rear stream side of the spray drying apparatus in the form of a sulfuric acid mist

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 3

the sulfuric acid mist adheres to the powder, and thus it is possible to collect the sulfuric acid mist

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Data Source

PatentEP2959959B1Exhaust gas treatment system
Publication Date: 2018.08.15 MITSUBISHI HITACHIPOWER SYST LTD
  • EP2959959B1 patent drawingFigure 1
  • EP2959959B1 patent drawingFigure 2
  • EP2959959B1 patent drawingFigure 3~4

AI summary

Provided is an air pollution control system including: a denitration apparatus 12 that is configured to remove nitrogen oxides in a flue gas 18 discharged from a boiler 11; an air heater 13 that is configured to recover heat of the flue gas 18 after denitration; a precipitator 14 that is configured to remove soot and dust contained in the flue gas after heat recovery in the form of collected dust ash 16; a desulfurization apparatus 15 that is configured to remove sulfur oxides contained in the flue gas 18 after dust removal using limestone slurry 20 which is an absorbent; a dehydrator 32 that is configured to remove gypsum 31 from absorber slurry discharged from the desulfurization apparatus 15; a spray drying apparatus 50 provided with a spray unit that is configured to spray dehydrated filtrate 33 as desulfurization wastewater supplied from the dehydrator 32; a flue gas introduction line L11 through which a branch gas 18a branched from the flue gas 18 is introduced to the spray drying apparatus 50; a flue gas supply line L12 through which flue gas 18b returns to a main flue gas duct, the flue gas 18b being obtained after the dehydrated filtrate is dried by the spray drying apparatus; and a powder supply apparatus 60 that is configured to supply a powder 61 to the flue gas introduction line L11.