Variable-Pitch Resistance Coil Heater for Fouling Reduction
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Solution Overview
Problem
Tubular heaters used in heat exchangers face issues with increased hydrocarbons and severe fouling due to overheating, leading to performance problems and bulky structures, as they provide uniform heat generation that does not account for temperature gradients or heat sinks, resulting in inefficient heating and potential failure.
Innovation Solution
The use of resistance coils with varying pitches along their length, allowing for a variable watt density that creates a predetermined temperature profile along the sheath, which can be tailored to match heat requirements, reducing overheating and improving heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform heat generation is provided by constant pitch resistance coils, then the heater structure is simple and easy to manufacture, but overheating occurs leading to increased hydrocarbons and severe fouling
Solution Approach 1:
The resistance coil is designed with variable pitch along its length, creating zones with different pitch values (first zone with pitch P1, second zone with pitch P2, third zone with pitch P3 where P1 < P2 < P3). This local variation in pitch creates corresponding zones with different watt densities, allowing the heater to provide non-uniform heat distribution that matches the thermal requirements of different locations, preventing overheating and fouling while maintaining manufacturing feasibility.
2Power
If more tubular heaters are provided to increase heat capacity rate, then the heat generation capability increases, but the structure becomes bulky
Solution Approach 1:
The pitch of the resistance coil is varied along its length to create zones with different pitch values, which directly changes the watt density parameter in different regions. This parameter change allows a single tubular heater to provide variable heat generation capability along its length, effectively increasing the overall heat capacity rate without adding more heaters or increasing the structure volume.
3Ease of manufacture
If uniform watt density is provided along the resistance coil, then the manufacturing process is simple, but temperature profile cannot be optimized for heat transfer efficiency
Solution Approach 1:
The resistance coil is divided into multiple zones with different local pitch characteristics. The first zone has pitch P1, the second zone has pitch P2, and the third zone has pitch P3, creating local variations in watt density. This local quality variation allows optimization of the temperature profile along the sheath, improving heat transfer efficiency to the process fluid while maintaining a relatively simple manufacturing process through standardized coil winding techniques.
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 approach enhances heat exchanger performance by reducing overheating, minimizing fouling, and enabling a more compact design, thus improving durability and reducing manufacturing costs by optimizing heat transfer and distribution.
Implementation Method 1
The resistance coil generates heat, which is transferred to the tubular sheath, which in turn heats a surrounding environment or part
Data Source
AI summary
A heater is provided that includes a resistance coil assembly defining a first end portion having a first conducting pin and a second end portion having a second conducting pin, and a resistance coil disposed between the first end portion and the second end portion, the resistance coil defining a plurality of different pitches between the first end portion and the second end portion. An insulating material surrounds the resistance coil assembly, and a sheath surrounds the insulating material. The plurality of different pitches provide a variable watt density such that a predetermined temperature profile is provided along the sheath.