Asphalt Mixing Plant Startup Scrap Reduction
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Solution Overview
Problem
Asphalt mixing plants using drum dryers face issues with material segregation during startup and shutdown, leading to unacceptable recipe shifts and significant scrap asphalt production, making small quantities uneconomical and difficult to produce with acceptable quality.
Innovation Solution
A method involving the collection and mixing of start-up and shutdown hot mineral material with bitumen or other components in a mixer to maintain a consistent recipe, allowing for continuous production of quality asphalt without scrap material, using a drum dryer with a controller for automated operation and a mixer capable of continuous or batchwise mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If material flow is started up or shut down through a drum dryer, then the drum dryer can be operated continuously, but material segregation occurs leading to recipe shifts and scrap asphalt production
Solution Approach 1:
The patent applies preliminary action by collecting the start-up hot mineral material (with incorrect recipe) in a buffer silo before normal operation begins. This pre-collection prevents the segregated material from immediately contaminating the final asphalt product, allowing the system to transition from startup to steady-state operation while maintaining recipe consistency.
Solution Approach 2:
The patent recovers the start-up and shutdown hot mineral material that would otherwise be discarded as scrap. By collecting these materials in a buffer silo and re-introducing them during normal operation, the system recovers valuable mineral material and eliminates scrap asphalt production, turning a waste stream into a reusable resource.
2Loss of substance
If start-up hot mineral material with incorrect recipe is continuously added to maintain recipe consistency, then scrap asphalt is reduced, but relatively large quantities of asphalt must be produced before the collected material is processed
Solution Approach 1:
The buffer silo acts as an intermediary storage facility between the drum dryer and the mixer. It temporarily holds the start-up and shutdown hot mineral material, decoupling the drum dryer operation from the mixer operation. This allows the drum dryer to be shut down for maintenance or recipe changes while the mixer continues to produce asphalt using the stored hot mineral material, eliminating the need to produce large quantities of asphalt to process the collected material.
3Adaptability or versatility
If drum dryer material flow is shut down, then production can be stopped, but finer hot mineral material emerges until no more hot mineral material emerges, causing recipe shifts
Solution Approach 1:
The buffer silo enables continuity of useful action by storing hot mineral material during normal operation and supplying it during shutdown periods. This ensures that the mixer can continue producing asphalt with consistent recipe even when the drum dryer is shut down for maintenance, recipe changes, or low-demand periods, maintaining material composition consistency while providing production flexibility.
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
Significantly reduces or eliminates scrap asphalt production, enabling economic production of small quantities with tightly tolerated recipes, maintaining quality and reducing waste.
Implementation Method 1
the mineral material is transported by a hot gas stream generated therein, it being repeatedly lifted and guided through the hot gas stream in the form of a trickle curtain
Data Source
Figure 1A~1C
AI summary
The invention relates to a method for operating an asphalt mixing plant, comprising a drum dryer (1) for drying and heating the mineral material and a mixer (2) for blending the heated mineral material with a binder. As the material flow starts to pass through the drum dryer (1) at the start of an operating phase the mineral material emerging from the drum dryer (1) is collected. In normal operation the emerging mineral material is blended in the mixer (2) with the binder to form asphalt. As the material flow moves down through the drum dryer (1) at the end of the operating phase the mineral material emerging from the drum dryer (1) is also collected. After the material flow has moved down through the drum dryer (1), the collected mineral material is blended in a mixer (2) with binder to form asphalt. Said method enables the amount of waste asphalt generated in continuous asphalt mixing plants to be appreciably reduced or eliminated, without compromising the formulation. In addition, even small amounts of quality asphalt having a formulation subject to strict tolerance requirements can be produced economically.