Jet Mill Integrating Grinding and Drying

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Solution Overview

Problem

The existing process for obtaining a dry, finely ground product from a wet suspension is complex and costly, requiring separate steps for mechanical pre-dewatering and thermal drying before jet grinding, which increases equipment and time expenditure.

Innovation Solution

A method and jet mill design that integrate grinding and drying into a single process step, where operating parameters like pre-pressure, expansion pressure, and inlet temperature are optimized to achieve the desired final fineness and residual moisture, with the resource requirement for grinding being greater than or equal to that for drying, using gases or superheated vapors as the operating fluid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If separate processes (mechanical pre-dewatering, thermal drying, then jet grinding) are used to obtain dry finely ground product from wet suspension, then the desired residual moisture and final fineness are achieved, but the equipment expenditure and process complexity increase

Engineering Contradiction:
Improvefinal finenessVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines grinding and drying operations into a single integrated jet mill process. The jet mill simultaneously performs particle size reduction and moisture removal in one unit operation, eliminating the need for separate mechanical pre-dewatering and thermal drying equipment. This merging of functions directly reduces device complexity while maintaining the desired final fineness and residual moisture specifications.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The jet mill is designed to perform multiple functions: grinding, drying, and product discharge in a single device. By making the jet mill a multi-functional unit that can handle both size reduction and moisture control, the patent eliminates the need for multiple specialized equipment pieces, thereby simplifying the overall process configuration and reducing equipment expenditure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Manufacturing precision

If separate processes (mechanical pre-dewatering, thermal drying, then jet grinding) are used to obtain dry finely ground product from wet suspension, then the desired residual moisture and final fineness are achieved, but the time expenditure increases

Engineering Contradiction:
Improvefinal finenessVSAvoidprocess time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

By merging grinding and drying into one simultaneous operation within the jet mill, the patent eliminates the sequential time requirements of separate mechanical pre-dewatering, thermal drying, and grinding steps. The material undergoes both size reduction and moisture removal in a single continuous process flow, significantly reducing total process time while achieving the same final fineness and residual moisture targets.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If conventional separate processes are used for drying and grinding, then the desired residual moisture and final fineness are achieved, but the energy efficiency decreases

Engineering Contradiction:
Improvefinal finenessVSAvoidenergy efficiency
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The integration of drying and grinding in the jet mill creates synergistic energy utilization. The high-velocity gas stream that provides grinding force also serves as the drying medium, eliminating the need for separate thermal drying energy input. The kinetic energy of the gas particles simultaneously achieves size reduction and moisture evaporation, improving overall energy efficiency compared to sequential thermal drying followed by grinding.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes changes in gas parameters (pressure, temperature, velocity) to optimize both grinding and drying simultaneously. By controlling the inlet gas conditions and expansion characteristics, the system adjusts the energy distribution between particle acceleration for grinding and heat transfer for drying, achieving optimal energy efficiency for the combined process while maintaining the desired final fineness and residual moisture.

Inventive Principle:
Principle #35Parameter changes

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 approach simplifies and enhances energy efficiency, allowing for simultaneous grinding and drying in a single step, reducing overall process complexity and cost while achieving the desired product characteristics.

Implementation Method 1

The gas jets, preferably gases or superheated vapors, emerging from the grinding gas nozzles 4 form a material fluid bed (not shown) in the grinding chamber 3

Methodology Applied
Scientific EffectFluidisation: Fluidisation

Implementation Method 2

The accelerated particles meet in the gas jets and in the center of the grinding chamber and are comminuted in the process

Methodology Applied
Scientific EffectAdiabatic expansion: Adiabatic Cooling

Implementation Method 3

moist or wet material to be ground to obtain an end product with a predetermined final fineness and a predetermined residual moisture is simultaneously ground in the jet mill by grinding to the predetermined final fineness and dried by drying to the predetermined residual moisture

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP2754500B1Method for jet milling and jet mill for the same
Publication Date: 2021.10.13 NETZSCH TROCKENMAHLTECHNIK GMBH
  • EP2754500B1 patent drawingFigure 1
  • EP2754500B1 patent drawingFigure 2~3
  • EP2754500B1 patent drawing

AI summary

The method involves simultaneously milling damp or wet grist in a jet mill (1) to predetermined final degree of fineness and drying it to the predetermined final moisture content, by appropriate choice of the operating parameter. The end product with the predetermined final degree of fineness and the predetermined final moisture content is released from the jet mill. An independent claim is included for jet mill.