Hydrocyclone Segmentation for Scrubber Water Heat Recovery
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Solution Overview
Problem
Current methods for cleaning and heat recovery from hot gases produced in thermal reactors, such as those from biomass or coal combustion, face inefficiencies in contaminant removal and energy recovery, particularly due to the high particle and salt content in scrubber water, which can lead to re-entrainment of contaminants and reduced heat exchanger lifespan.
Innovation Solution
The implementation of a system that includes hydrocyclones upstream of the heat exchanger to separate scrubber water into high and low particle load streams, with the high load stream recirculated to the thermal reactor or ash, and the low load stream used for energy recovery and air moisturization, combined with a double air moisturization system to reduce slagging and NOx formation, and membrane filters for cleaning excess condensate before disposal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If scrubber water is used directly for heat recovery, then heat recovery efficiency is improved, but heat exchanger lifespan is reduced due to high particle and salt content
Solution Approach 1:
The scrubber water stream is segmented into two separate streams using hydrocyclones: a particle-rich stream and a particle-poor stream. The particle-poor stream is directed to the heat exchanger for heat recovery, while the particle-rich stream is recirculated to the thermal reactor. This segmentation protects the heat exchanger from particle damage while maintaining heat recovery efficiency.
Solution Approach 2:
The hydrocyclones extract particles from the scrubber water stream by separating it into a particle-rich stream and a particle-poor stream. This extraction removes the harmful particles before the water enters the heat exchanger, extending its lifespan while preserving the heat recovery function.
2Device complexity
If scrubber water is discharged directly, then system complexity is reduced, but environmental contamination occurs due to high particle and salt content
Solution Approach 1:
The system uses its own scrubber water, after particle removal via hydrocyclones, to moisturize the air entering the thermal reactor. This self-service approach reuses the water internally, preventing environmental discharge and contamination while adding value by improving gasification properties.
Solution Approach 2:
Instead of discarding the scrubber water directly, the system recovers useful properties by removing particles first, then reusing the cleaned water for air moisturization. This recovery process prevents contamination while maintaining relatively simple system architecture.
3Productivity
If air is dried before entering thermal reactor, then combustion efficiency is improved, but slagging and NOx formation increase
Solution Approach 1:
The system changes the humidity parameter of the air by moisturizing it with scrubber water before it enters the thermal reactor. This parameter change reduces slagging and NOx formation while the hydrocyclone separation ensures particles don't compromise combustion efficiency.
Solution Approach 2:
The scrubber water acts as an intermediary substance that transfers moisture to the air stream. This intermediary approach allows controlled humidification of the air without directly introducing particles into the combustion zone, as particles are removed by hydrocyclones first.
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 the cleaning efficiency of the scrubber system, extends the lifetime of heat exchangers, improves energy recovery, and reduces emissions by effectively managing particle loads and utilizing moisturized air for improved gasification properties, leading to increased power output and system efficiency.
Implementation Method 1
The scrubber water is led through at least one hydro cyclone and/or centrifuge which separates the scrubber water into a first stream and a second stream
Implementation Method 2
injecting water into the gas at one or more injection zones in such an amount and in such a way that the gas temperature due to water evaporation is reduced
Implementation Method 3
at least some of the gas contents of water vapour are condensed, and the condensing heat can be utilized for heating of a stream of fluid
Implementation Method 4
The gas can then be led through a condensing heat exchanger unit, where at least some of the gas contents of water vapour are condensed, and the condensing heat can be utilized for heating of a stream of fluid
Data Source
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AI summary
Exhaust gas, produced in a thermal reactor (1) that is fed with solid fuel can be cooled and in a gas cooler (4) which produce a condensate that is further cooled in a condensate cooler (7) which produce energy. By using air moisturizing and particle separation technology the exhaust gas and the excess condensate can be clean and the energy efficiency of the plant can be increased. The method can be used for a broad spectrum of fuels and conversion technologies.