Heat Engine Waste Heat Recovery for Salt Drying
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Solution Overview
Problem
Current drying processes for salt and similar materials, such as sulfate of potash and magnesium chloride, are inefficient, with direct fired heating losing 35-40% energy and indirect heating methods having efficiency limits, as heat energy passes through multiple steps without optimal utilization.
Innovation Solution
A method utilizing hot waste gases from a heat engine to dry materials in rotary kiln, fluidized bed, or dispersion dryers, where the waste gases with temperatures above 100°C are introduced into the dryers to reduce the moisture content of materials like sodium chloride, potassium chloride, and magnesium chloride to 90% or lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct fired natural gas heating is used to dry salt and similar materials, then the drying process is effective, but energy efficiency deteriorates with 35-40% energy loss to the environment
Solution Approach 1:
The patent captures waste heat from heat engine exhaust gases that would otherwise be lost to the environment and uses it as a drying medium. This converts the harmful energy loss into a beneficial resource, achieving effective drying while eliminating the 35-40% energy waste associated with direct fired heating.
Solution Approach 2:
The system recovers thermal energy from heat engine exhaust gases that would normally be discarded into the environment. By capturing and utilizing this waste heat for drying operations, the system prevents energy loss while maintaining drying effectiveness.
2Reliability
If indirect heating through heat exchangers with steam or hot oil is used, then the drying process is effective, but energy efficiency deteriorates due to multiple heat transfer steps
Solution Approach 1:
The patent extracts the heat transfer medium (exhaust gases) directly from the heat engine system and uses it as the drying medium in the dryer. This eliminates the intermediate heat exchanger steps required in conventional indirect heating, reducing energy loss through multiple heat transfer interfaces while maintaining drying effectiveness.
Solution Approach 2:
The exhaust gases from the heat engine serve multiple functions: they provide process heating for drying materials and simultaneously utilize the waste thermal energy that would otherwise be lost. This multi-functional use of the same thermal resource improves overall energy efficiency while maintaining effective drying.
3Loss of energy
If waste heat from heat engines is used to dry materials, then energy efficiency improves above 75%, but the system requires integration with existing heat engine infrastructure
Solution Approach 1:
The patent merges the heat engine system with the drying operation by directly connecting the exhaust gas stream to the dryer. This integration combines two previously separate processes (heat generation and material drying) into a unified system, achieving high energy efficiency while managing complexity through process consolidation rather than adding separate systems.
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 significantly improves energy efficiency by utilizing waste heat, achieving drying with a final moisture content reduction of 50% or more, while also utilizing excess electrical power for plant operations.
Implementation Method 1
the hot waste gas causes the material to exit the dryer at a final moisture content that is about 90% or lower than the initial moisture content
Implementation Method 2
introducing that hot waste gas into a dryer... the hot waste gas dries the material
Data Source
AI summary
The present invention provides a method and system for generating electricity using a drive for the electrical generator that is powered by an engine (e.g., turbine). The method and system uses high pressure hot gases produced by combustion of a fuel and an oxygen-bearing gas, using at least a portion of the electricity generated to power manufacturing plant equipment. Additionally, hot waste gases from the heat engine are transported to a process dryer (e.g., rotary kiln dryers) to dry minerals, salt, pigments, sands, and clay.