Rotating Fluidized Bed Roaster Oxygen Injection for CO Mitigation

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Solution Overview

Problem

Achieving extra dark roast color for coffee beans at industrial scale is challenging due to unsafe roasting conditions caused by high concentrations of carbon monoxide, which can lead to over-roasting and hazardous situations, especially in drum and paddle roasters, where temperature control and uniformity are difficult to manage.

Innovation Solution

Injecting a stream of oxygen-containing gas into the flow of hot air after the burner in a rotating fluidized bed roaster, maintaining the injection until the end of the roasting process to mitigate carbon monoxide levels, ensuring safe roasting conditions and achieving extra dark roast color without the bitter taste associated with over-roasting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If roasting temperature is increased to achieve extra dark roast color, then roasting degree is improved, but carbon monoxide concentration increases to hazardous levels

Engineering Contradiction:

Improveroasting temperatureVSAvoidcarbon monoxide concentration

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The harmful carbon monoxide gas is extracted and removed from the roasting chamber environment through enhanced ventilation and gas extraction systems, allowing high-temperature roasting to proceed without accumulating hazardous CO levels

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Oxygen-enriched air is introduced into the roasting chamber to accelerate the oxidation and combustion of carbon monoxide, converting it to carbon dioxide and reducing hazardous CO concentrations while maintaining high roasting temperatures

Inventive Principle:

Principle #38Strong oxidants (Accelerated oxidation)

2Temperature

If roasting continues to achieve darker color, then roasting degree is improved, but safety conditions deteriorate due to fire risk

Engineering Contradiction:

Improveroasting temperatureVSAvoidsafety conditions

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

Real-time monitoring systems continuously measure temperature, gas concentrations, and roasting progress, providing feedback control that automatically adjusts ventilation, oxygen injection, and heating to maintain safe operating conditions while achieving desired roast levels

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Safety measures including enhanced ventilation, oxygen enrichment, and monitoring systems are activated before hazardous conditions can develop, cushioning against potential fire risks by preventing carbon monoxide accumulation and maintaining controlled combustion conditions

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If industrial scale roasting is used to increase productivity, then production volume is improved, but temperature control precision deteriorates

Engineering Contradiction:

Improveproduction volumeVSAvoidtemperature control precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The large-scale roasting chamber is divided into multiple zones with independent temperature control and monitoring, allowing precise temperature management across different regions of the chamber while maintaining high production volume

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple temperature sensors and control systems provide real-time feedback across the roasting chamber, enabling precise temperature regulation throughout the large volume to ensure uniform roasting quality at industrial scale

Inventive Principle:

Principle #23Feedback

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 method allows for the safe achievement of extra dark roast color at industrial scale by maintaining carbon monoxide levels below 8000 ppm, preventing hazardous conditions and ensuring the coffee beans retain a more aromatic flavor profile typically associated with lighter roasts.

Implementation Method 1

a stream of oxygen-containing gas is injected into the flow of hot air after the burner

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

U.S. Pat. No. 3,964,175 describes a roasting method for transferring efficiently heat from air to the coffee beans

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

transferring efficiently heat from air to the coffee beans

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

Significant amount of gases, including carbon dioxide (CO2) and carbon monoxide (CO), are generated during roasting as a result of Maillard reaction and pyrolysis

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Implementation Method 5

maintaining the injection of the stream of oxygen-containing gas until the end of the roasting process to mitigate the concentration of carbon monoxide in the roasting chamber

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS11812760B2Method for roasting coffee beans

Publication Date: 2023.11.14 SOCIETE DES PRODUITS NESTLE SA

AI summary

A method for roasting coffee beans comprising the steps of a) heating the coffee beans until the temperature of the coffee beans is at least 180° C.; b) injecting a stream of oxygen-containing gas into the flow of hot air after the burner; and c) maintaining the injection of the stream of oxygen-containing gas until the end of the roasting process to mitigate the concentration of carbon monoxide in the roasting chamber, and wherein the coffee beans are roasted in a rotating fluidized bed roaster.