An onsite system for preparing a fumigant
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Solution Overview
Problem
Current fumigation methods using liquid ethyl formate (EtF) and carbon dioxide face issues such as inaccurate dosing, fluctuating concentrations, and environmental concerns due to the use of electric vaporizers, which lead to inefficient and costly fumigation processes with potential damage to stored foodstuffs.
Innovation Solution
An onsite system comprising a bulk source of EtF and CO2, with separate vaporizing stations and a mixing station that uses a heat exchanger and portable energy source to maintain consistent vaporization and mixing ratios, eliminating the need for pressurized cylinders and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid fumigant is vaporized using an electric vaporizer unit with oil bath, then the liquid fumigant can be converted to gas form, but the different specific heat capacities and expansion rates cause condensation on foodstuff surfaces and localized high concentrations
Solution Approach 1:
The system divides the vaporization process into two separate vaporization stations - one for the fumigant liquid and one for the diluent liquid. Each station independently vaporizes its respective liquid, and the vapors are then mixed in predetermined ratios. This segmentation eliminates the problems of condensation and concentration control that occur when vaporizing mixed liquids together in a single oil bath system.
Solution Approach 2:
The system introduces a diluent liquid as an intermediary substance that mixes with the fumigant liquid before vaporization. This diluent serves as a carrier that helps control the vaporization process and enables precise mixing ratios of the final fumigant gas composition, solving the concentration control problem.
2Productivity
If short bursts of fumigant gas are delivered, then the fumigation process can be completed quickly, but the proportion of EtF in CO2 becomes difficult to sustain resulting in localized high concentrations
Solution Approach 1:
The system maintains continuous vaporization of both fumigant and diluent liquids through separate heated vaporization stations, ensuring a steady and sustained supply of vapor mixture. This continuous action eliminates the concentration fluctuations that occur with intermittent or burst delivery methods, maintaining consistent predetermined ratios throughout the fumigation process.
Solution Approach 2:
The system incorporates flow controllers that monitor and adjust the liquid flow rates to maintain precise mixing ratios. This feedback mechanism ensures that the predetermined proportion of fumigant to diluent is sustained continuously, preventing localized high concentrations even during high-speed operation.
3Duration of action of moving object
If the concentration of EtF in CO2 changes as the cylinder empties, then the fumigation process continues, but stored foodstuff is exposed to negative effects of higher concentrations leading to inaccurate dosing
Solution Approach 1:
The system automatically maintains precise mixing ratios throughout the entire fumigation duration through continuous monitoring and adjustment by flow controllers. The system self-regulates the vaporization rates and mixing proportions, eliminating the need for manual intervention and ensuring consistent dosing accuracy from start to finish of the fumigation process.
Solution Approach 2:
The system replaces the simple pressure-driven delivery from pressurized cylinders with an actively controlled vaporization system using heated stations and electronic flow controllers. This substitution of passive mechanical delivery with active thermal and electronic control enables precise maintenance of fumigant concentrations throughout the entire operation duration.
4Object-generated harmful factors
If liquid fumigant constituents are used instead of pressurized cylinders, then environmental impact is reduced, but separate vaporization and mixing equipment is required increasing system complexity
Solution Approach 1:
The system merges the vaporization and mixing functions into an integrated setup where two vaporization stations feed into a common mixing chamber. While the functions are separate, their physical arrangement and control systems are combined to create a unified fumigation delivery system, managing the complexity through systematic integration rather than separate independent units.
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 system provides a consistent concentration of vaporized fumigant, reducing exposure risks to foodstuffs, lowering operational costs, and overcoming the limitations of traditional electric vaporizers by using a more efficient heat source and minimizing waste.
Implementation Method 1
a first vaporizing station for receiving and vaporizing a supply of the active liquid fumigant; a second vaporizing station interconnected to the first vaporizing station for vaporizing a supply of the liquid diluent
Implementation Method 2
a mixing station fluidly connected to the first and second vaporization stations, the mixing station adapted to receive incoming streams of the vaporized fumigant and diluent, wherein the mixing station includes a vapor control means to mix the incoming fumigant and diluent vapor streams in a predetermined ratio
Data Source
AI summary
An onsite system for generating a fumigant for use with foodstuffs comprising: an active fumigant vaporizing station comprising: a first water heater; a heat exchanger connectable to the first water heater to receive heated water therefrom, the heat exchanger being configured to receive, heat and vaporise active liquid fumigant entering into the heat exchanger via a fumigant inlet; and a fumigant outlet connected to the plate heat exchanger for delivering a stream of vaporised fumigant; a liquid diluent vaporizing station comprising: a second water heater; a shell and tube heat exchanger connectable to the second water heater to receive heated water therefrom, the shell and tube heat exchanger being configured to receive, heat and vaporise the liquid diluent entering into the shell and tube heat exchanger via a mixing liquid inlet; and a mixing liquid outlet connected to the shell and tube heat exchanger for delivering the vaporised diluent; and a mixing unit configured to receive and mix the vaporised fumigant from the fumigant outlet and the vaporized diluent liquid from the diluent liquid outlet; mixing of the vaporised fumigant and vaporised mixing liquid to deliver a vaporised fumigant mixture; and a mixing and control means at the mixing unit for mixing the vaporised fumigant and diluent at, or substantially at, a predetermined mixing ratio.