Pyrolysis Char Separation for Heat Balance and Ash Control
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Solution Overview
Problem
In pyrolysis systems, there is a challenge in maintaining heat balance, managing ash accumulation, and controlling afterburning in the reheater, primarily due to excessive heat generation and ash production from combustible solids, which affects the efficiency and operation of the system.
Innovation Solution
The process involves segregating combustible solids (char) from the heat transfer medium and selectively removing a portion of it to control heat balance and ash accumulation, using dual stage cyclone separators or cyclone separators coupled with elutriation chambers to separate char from spent heat transfer medium, and then processing the segregated char to maintain heat balance and minimize afterburning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If combustible solids are combusted in the reheater to meet heat demand, then heat supply is improved, but excess heat generation and ash accumulation occur
Solution Approach 1:
The patent divides the combustible solids handling into two separate streams: one for combustion in the reheater to meet heat demand, and another for removal to control ash accumulation. The gas-solid separator segregates combustible solids from the heat transfer medium, allowing selective removal of a portion of combustible solids before they enter the reheater, thus preventing excessive ash accumulation while maintaining adequate heat supply.
Solution Approach 2:
The patent changes the parameter of combustible solids quantity by removing a portion of segregated combustible solids from the system before combustion. This parameter adjustment allows control over the amount of ash generated while maintaining sufficient heat supply for the pyrolysis reactor.
2Loss of substance
If segregated combustible solids are removed to control ash accumulation, then ash accumulation is reduced, but heat balance control becomes challenging
Solution Approach 1:
The patent implements feedback control by monitoring the heat balance and ash accumulation levels, and adjusting the amount of segregated combustible solids removed accordingly. The system dynamically balances heat supply requirements with ash accumulation control by modulating the removal rate of combustible solids based on system conditions.
3Power
If char is blown from dense bed into dilute phase, then afterburning occurs, but heat transfer efficiency decreases
Solution Approach 1:
The patent extracts combustible solids from the heat transfer medium using a gas-solid separator before they can be blown into the dilute phase and cause afterburning. By removing a portion of segregated combustible solids prior to reheater combustion, the system prevents afterburning events that would disrupt heat transfer efficiency while maintaining adequate combustion completeness.
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 effectively controls heat balance, reduces ash accumulation, and minimizes afterburning by removing excess char before combustion, thereby optimizing heat transfer and system efficiency in the pyrolysis process.
Implementation Method 1
using dual stage cyclone separators or cyclone separators coupled with elutriation chambers to separate char from spent heat transfer medium
Implementation Method 2
cyclone separators coupled with elutriation chambers to separate char from spent heat transfer medium
Implementation Method 3
The heat transfer medium is maintained as a fluidized dense bed in a lower portion of the reheater by the upward passage of an oxygen-containing regeneration gas stream through the fluidized dense bed
Implementation Method 4
combusting the non-condensable pyrolysis gases and the combustible solids produced in the pyrolysis reaction
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The present invention provides a process (10) for pyrolysis of a carbonaceous biomass feedstock in a pyrolysis system, the process comprising: i) pyrolyzing carbonaceous biomass feedstock using a heat transfer medium forming pyrolysis products and a spent heat transfer medium (12); ii) separating the spent heat transfer medium into segregated char and char-depleted spent heat transfer medium (70); iii) introducing the char-depleted spent heat transfer medium into a dense bed of heat transfer medium fluidized by a stream of oxygen-containing regeneration gas (80) to form heated heat transfer medium, said oxygen-containing regeneration gas introduced into a lower portion of the fluidized dense bed; and iv) combusting (90) the segregated char to heat the lower portion of the fluidized dense bed, wherein at least a portion of the segregated char is mixed with the oxygen-containing regeneration gas and at least partially combusted (100) in said gas prior to introduction to the fluidized dense bed.