Spray Drying Lance Cleaning via Valve Sequencing
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Solution Overview
Problem
The existing methods for cleaning spray drying systems, particularly in the dairy industry, fail to reliably prevent contamination of tower powders by enterobacteria due to residual product and air penetration through valves in the compressed air line, leading to clogging and potential fires.
Innovation Solution
A method involving a specific sequence of opening and closing valves to ensure thorough cleaning, including the use of multi-way and three-way valves to meter cleaning liquids and compressed air, and a temperature treatment to prevent germ growth, ensuring no residual water or air remains in the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single flushing process is used to clean the pipeline, then the cleaning process is simple and quick, but product residue remains in the lances causing contamination
Solution Approach 1:
The cleaning process is divided into multiple sequential steps: initial flushing with water, draining, compressed air blowing, and final draining. Each step targets different aspects of residue removal, with water flushing removing bulk residue and compressed air removing remaining moisture and particles from the lances.
Solution Approach 2:
The system performs preliminary cleaning actions automatically before manual lance removal is needed. The coordinated valve operations and sequential flushing/compressed air steps prepare the lances in advance, reducing the need for extensive manual cleaning and preventing contamination before it occurs.
2Reliability
If compressed air is used to blow out the lances, then residual water is removed, but air penetration through valves introduces contamination
Solution Approach 1:
The compressed air connection is temporarily disconnected from the lance system during the blowing step by closing valve V6. Compressed air is introduced through valve V2 to blow out the lances, then the air connection is shut off. This extracts the compressed air function from the continuous system, preventing air penetration contamination while maintaining drying effectiveness.
Solution Approach 2:
The valve configurations dynamically change during the cleaning cycle to control air flow paths. Valves V2, V5, and V6 are coordinated to introduce compressed air only when needed and to seal off the air connection afterward, adapting the system's air permeability to the specific cleaning stage.
3Reliability
If multiple valve operations are performed for thorough cleaning, then contamination is prevented, but the cleaning process becomes complex and time-consuming
Solution Approach 1:
Valve V1 serves multiple functions: it controls water flow during flushing, controls compressed air flow during the blowing step, and participates in sealing the system during draining. This multi-functionality reduces the total number of valves needed while maintaining the complex cleaning sequence.
Solution Approach 2:
The system uses its own resources for cleaning: process water is reused for flushing, and compressed air from the existing supply system is used for blowing. The valve system automatically sequences the operations, reducing the need for external intervention and simplifying operation despite the multiple steps.
4Reliability
If lances are removed by hand for cleaning, then thorough cleaning is achieved, but contamination risk increases and productivity decreases
Solution Approach 1:
The automated flushing and compressed air blowing steps are performed in advance to remove the majority of residue and moisture from the lances. This preliminary action reduces the extent of manual cleaning needed, allowing lances to be quickly inspected and minimized handled rather than thoroughly disassembled and cleaned by hand.
Solution Approach 2:
Manual mechanical cleaning operations are replaced with automated fluid-based cleaning: water flushing replaces manual scrubbing, and compressed air blowing replaces manual drying. This substitution maintains cleaning thoroughness while significantly improving efficiency and reducing contamination risk from manual handling.
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 method effectively prevents contamination by ensuring complete drainage and sterilization of the system, resulting in germ-free tower powders with no detectable enterobacteria in 10 and 1g of powder.
Implementation Method 1
the lances are subsequently blown out with compressed air
Implementation Method 2
the pipeline is pushed out via the nozzles and reaches a collecting tray through which the liquid can be drained and removed again
Data Source
Figure 1
AI summary
A method is proposed for cleaning the feed side of a spray drying plant, in which contamination in the supply pipelines is prevented by a special sequence of opening and closing valves, which introduce cleaning fluid and compressed air into the system.