Dry Powder Filter for Plastic Exhaust Acid Neutralization
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Solution Overview
Problem
The challenge lies in effectively separating and neutralizing acidic components in exhaust gases from thermal plastic processing, which can damage filter elements and reduce their operational life.
Innovation Solution
A method involving a dry powder mixture with at least 40% Ca(OH)2 and/or CaO is added to the exhaust gases, forming a filter cake where the acid reacts to form a salt, with controlled pressure and residence time to ensure complete chemical conversion, and a chamber with a larger cross-sectional area for cooling and particle retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a wet scrubber with sodium hydroxide/potassium hydroxide solution is used to remove acid gas components, then acid removal efficiency is improved, but device complexity and water consumption increase
Solution Approach 1:
The invention changes the physical state parameter of the alkaline substance from liquid (wet scrubber) to solid (dry powder mixture), transforming the acid removal process from wet scrubbing to dry absorption. This eliminates water consumption and simplifies the system while maintaining acid removal efficiency through the chemical reaction between acid components and alkaline substances in the filter cake.
Solution Approach 2:
The invention extracts and removes the harmful acid gas components from the exhaust gas stream by incorporating them into the filter cake during the filtration process. The acid components are taken out of the gas phase and converted to solid salt form in the filter cake, which is then removed with the spent filter medium, eliminating the need for separate wet scrubbing equipment.
2Manufacturing precision
If filter elements are used to separate particles from exhaust gas, then particle separation is improved, but filter element service life is reduced due to acid damage
Solution Approach 1:
The invention converts the harmful acid components into a beneficial protective layer within the filter cake. The acid reacts with alkaline substances to form salts that become part of the filter cake structure, neutralizing the corrosive effect and actually contributing to the filter cake's functionality. This transforms the harmful acid from a degradation agent into a component that maintains filter element integrity.
Solution Approach 2:
The filter cake acts as an intermediary substance between the exhaust gas and the filter element. It provides a protective barrier that prevents direct contact between acidic exhaust components and the filter element surface, thereby extending filter element service life while maintaining effective particle separation through the filter cake's porous structure.
3Object-generated harmful factors
If a dry powder mixture is added to form a filter cake for acid absorption, then acid neutralization is improved, but powder mixture consumption and handling complexity increase
Solution Approach 1:
The invention establishes a continuous process where the powder mixture is continuously added to the exhaust gas stream, forming a continuously updating filter cake that maintains optimal acid neutralization capacity. The spent filter cake containing neutralized acid is continuously removed with the spent filter medium, allowing for uninterrupted operation and consistent acid removal efficiency without periodic shutdowns for maintenance or replacement.
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
This method allows for efficient acid separation and extended filter element life by ensuring sufficient residence time for chemical conversion and preventing filter damage, enabling continuous operation and reducing environmental acid release.
Implementation Method 1
the acid reacts chemically with the Ca(OH)2 and/or CaO and a salt of Ca is formed
Implementation Method 2
exhaust gases released during thermal processing of plastic flow by means of a vacuum generator from a working area
Implementation Method 3
a filter cake is formed with the powder on the surface of the at least one first filter element
Implementation Method 4
the filter cake is cleaned with at least one pressure pulse of compressed gas which passes through the at least one first filter element
Data Source
Figure 1
AI summary
In this process, exhaust gas released from a working area is drawn into a filter chamber (2.1, 2.2) by means of a vacuum generator (4). The exhaust gas then flows through a first filter element (6.1, 6.2) located within the filter chamber (2.1, 2.2), and treated exhaust gas is discharged from the filter chamber (2.1, 2.2). Before entering the filter chamber (2.1, 2.2), a dry powder mixture containing at least 40% by mass of Ca(OH)₂ and/or CaO, with the remainder consisting of other oxides, is added to the exhaust gas. A filter cake forms on the first filter element (6.1, 6.2) with the powder. Acid contained in the exhaust gas is adsorbed by the powder mixture along with the Ca(OH)₂ and/or CaO, and then reacts chemically with the Ca(OH)₂ and/or CaO, forming a calcium salt. After reaching a second predetermined pressure in the filter clamp (2.2, 2.2), in front of the first filter element (6.1, 6.2) and/or reaching a second predetermined layer thickness of the filter cake, the filter cake is cleaned.Parts of the filter cake are detached from the surface of the first filter element (6.1, 6.2) and transferred to a collection container.