Asphalt Drying Drum Control for Independent Gas and Aggregate Temperatures

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Solution Overview

Problem

Existing asphalt mixing plants face challenges in controlling the drying and heating of materials in drying drums due to complex interdependencies between process parameters, making it difficult to maintain consistent material and raw gas temperatures without manual intervention.

Innovation Solution

Implementing independent controllers for each control loop to manage aggregate and raw gas temperatures in drying drums, using predictive and proportional-integral controllers with dead-time compensation, allowing automated control of both temperatures independently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If manual control of drying drum rotational frequency is used to adapt raw gas temperature, then raw gas temperature can be adjusted, but material temperature control becomes difficult due to complex interdependencies between process parameters

Engineering Contradiction:
Improveraw gas temperatureVSAvoidmaterial temperature control
Core Design Contradiction:
TemperatureVSEase of operation

Solution Approach 1:

The control system is segmented into two independent controllers: a first controller that manages material temperature by controlling burner load, and a second controller that manages raw gas temperature by controlling drying drum rotational frequency. This segmentation resolves the contradiction by separating the coupled control tasks into independent control loops, allowing each parameter to be controlled without interfering with the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control system implements feedback mechanisms where both controllers receive real-time temperature measurements and automatically adjust their respective control parameters (burner load and rotational frequency) to maintain target temperatures. This feedback approach eliminates the need for manual intervention and resolves the complexity of coordinating multiple process parameters.

Inventive Principle:
Principle #23Feedback

2Extent of automation

If independent controllers are implemented for each control loop, then automated control of material and raw gas temperatures is achieved, but system complexity increases

Engineering Contradiction:
Improveautomated temperature controlVSAvoidcontrol system complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

By segmenting the control system into two independent controllers with distinct control loops, the patent achieves automated control while managing complexity through modular design. Each controller handles a specific temperature parameter independently, avoiding the complexity of coordinating multiple parameters in a single controller.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a central control unit that coordinates the two independent controllers, serving as an intermediary that manages communication and data exchange between controllers. This intermediary structure enables automated control while keeping individual controller complexity manageable.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Achieves efficient and automated control of aggregate and raw gas temperatures, reducing complexity and improving the quality of asphalt production while maintaining ecological benefits.

Implementation Method 1

The first controller (41) is configured to control a first aggregate temperature (TA1) of the first aggregate (A1) by controlling or in other words adapting the burner load or in other words the thermal output power of the first burner (31)

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

The second controller (42) is configured to control a first raw gas temperature (TG1) of a first raw gas (G1) of the first drying drum (11) by controlling or in other words adapting the first rotational speed (RPM1) of the first drying drum (11)

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4388156B1Control of an asphalt mixing plant
Publication Date: 2025.08.20 AMMANN SCHWEIZ AG
  • EP4388156B1 patent drawingFigure 1~2
  • EP4388156B1 patent drawingFigure 3~4
  • EP4388156B1 patent drawingFigure 5~6

AI summary

According to an embodiment of a first aspect of the invention, there is provided an asphalt mixing plant (700) comprising a first drying drum (11) for drying and heating a first aggregate to a first aggregate temperature. The first drying drum (11) comprises a first burner (31) and a first controller (41) configured to control by a first control loop (51) the first aggregate temperature of the first aggregate. The asphalt mixing plant (700) further comprises a second controller (42) configured to control by a second control loop (52) a first raw gas temperature of a first raw gas of the first drying drum (11). The first controller (41) and the second controller (42) are configured to operate independently from each other. Further aspects relate to a corresponding method and a corresponding computer program product.