Nested Absorption Tower Structure for Low-Water NMP Recovery

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Solution Overview

Problem

Conventional NMP waste gas recovery processes face challenges such as high water content in recovered waste liquids, difficulty in meeting emission standards, complex subsequent treatment, and the need for multi-stage operations, which result in high costs and instability in product quality.

Innovation Solution

A miniaturized absorption tower design with separate inner and outer cylinders, each equipped with specific fillers, liquid distributors, and mist eliminators, allowing for efficient separation and treatment of gases, and a waste gas recovery system incorporating this tower with heat exchangers and fans to manage gas and liquid flows.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional water-washing process is used to satisfy emission standards, then exhaust gas treatment is achieved, but water content of recovered waste liquid becomes excessively high

Engineering Contradiction:
Improveemission standard satisfactionVSAvoidwater content of waste liquid
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The absorption tower is divided into inner and outer cylinders with separate filling zones. The inner cylinder contains first filler for primary absorption, while the outer cylinder contains second filler for secondary absorption. This segmentation allows staged treatment of waste gas, enabling emission standards to be met while reducing water content in recovered liquid by optimizing absorption efficiency at each stage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inner cylinder is nested within the outer cylinder, creating a compact concentric structure. The inner cylinder handles the first stage of absorption, and the outer cylinder handles the second stage. This nesting arrangement achieves multi-stage absorption in a compact form, reducing water content while meeting emission standards without requiring multiple separate towers.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If multi-stage circulation operations are used, then absorption effectiveness is improved, but device complexity and occupied area increase

Engineering Contradiction:
Improveabsorption effectivenessVSAvoidtower structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Multiple absorption stages that would traditionally require separate towers are merged into a single integrated absorption tower with inner and outer cylinders. The first filler in the inner cylinder and second filler in the outer cylinder work together in sequence, achieving multi-stage absorption effectiveness while simplifying the overall device structure and reducing occupied area.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The nested concentric cylinder structure allows two complete absorption stages to be housed within one tower. The inner cylinder with its filler and distributors is nested inside the outer cylinder with its own filler and distributors, enabling multi-stage operation without the complexity of multiple independent towers or complex internal mechanisms.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Productivity

If conventional two-tower structure is used, then recovery efficiency is achieved, but occupied space increases

Engineering Contradiction:
Improverecovery efficiencyVSAvoidtower occupied area
Core Design Contradiction:
ProductivityVSArea of stationary object

Solution Approach 1:

The absorption tower uses a nested concentric cylinder design where the inner cylinder is placed inside the outer cylinder. This allows two functional zones (first filler zone and second filler zone) to occupy the same footprint area, effectively doubling the absorption capacity within the same ground space, thereby maintaining recovery efficiency while halving the occupied area compared to two separate towers.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of expanding horizontally with two separate towers, the design transitions to vertical utilization by creating concentric zones within a single tower footprint. The inner and outer cylinders create radial zones that both contribute to absorption, effectively using the vertical and radial dimensions to achieve high recovery efficiency in a compact footprint.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The design ensures compliance with emission standards while minimizing water content in waste liquids, enabling continuous operation and stable product quality, reduces space requirements, and simplifies control, thereby improving recovery efficiency and reducing costs.

Implementation Method 1

a first filler (4) is accommodated in the inner cylinder (2), and a second filler (5) is accommodated in a gap between the inner cylinder (2) and the outer cylinder (1)

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

When a conventional water-washing process satisfies an emission standard of exhaust gas in NMP treatment

Methodology Applied
Scientific EffectMass transfer:

Implementation Method 3

a first liquid distributor (6) and a first mist eliminator (8) are disposed inside the inner cylinder (2), the first liquid distributor (6) is located above the first filler (4)

Methodology Applied
Scientific EffectFluid distribution:

Implementation Method 4

a first mist eliminator (8) is located above the first liquid distributor (6)

Methodology Applied
Scientific EffectMist elimination:

Data Source

PatentEP4570355B1Absorption tower and waste gas recovery system
Publication Date: 2026.04.29 GUANGDONG TIAN RUI DE NEW ENERGY TECH CO LTD
  • EP4570355B1 patent drawingFigure 1
  • EP4570355B1 patent drawingFigure 2~3
  • EP4570355B1 patent drawingFigure 4~5

AI summary

The present invention discloses an absorption tower and a waste gas recovery system. The absorption tower includes an outer cylinder and at least one inner cylinder disposed inside the outer cylinder. A filler support plate is disposed inside the outer cylinder, a gas inlet and a liquid discharge port are provided on the outer cylinder, and both the gas inlet and the liquid discharge port are located below the filler support plate. The bottom of the inner cylinder has an opening, and the inner cylinder is located above the filler support plate. A first filler is accommodated in the inner cylinder, and a second filler is accommodated in a gap between the inner cylinder and the outer cylinder. A first liquid distributor and a first mist eliminator are disposed inside the inner cylinder, the first liquid distributor is located above the first filler, and a first gas outlet is provided on an upper part of the inner cylinder. A second liquid distributor and a second mist eliminator are disposed inside the outer cylinder, the second liquid distributor is located above the second filler, and a second gas outlet is provided on an upper part of the outer cylinder. The absorption tower has a simple and novel structure, accompanied with high recovery benefit, simple control, stable product quality, and small space occupation.