Phosphorus Ash from Biomass Pyrolysis Decarbonization
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Solution Overview
Problem
Current methods for producing phosphorus-containing fertilizers from sewage sludge and other phosphorus-rich biomass are energy-intensive, inefficient, and result in low concentrations of plant-available phosphorus, leading to inadequate fertilizer quality and high production costs.
Innovation Solution
A process involving pyrolysis of phosphorus-containing biomass at up to 800°C without oxygen, followed by decarbonization with oxygen supply between 300°C to 600°C to produce phosphorus-containing ash, which is then used as a fertilizer or fertilizer additive, allowing for efficient energy recovery and high phosphorus availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pyrolysis is performed at high temperatures to convert phosphorus-containing biomass, then energy content is recovered, but phosphorus becomes bound in the carbon matrix of coke and is not sufficiently released in plant-available form
Solution Approach 1:
The process is divided into two distinct stages: (a) pyrolysis at temperatures of 300-800°C without oxygen to recover energy and produce pyrolysis coke, followed by (b) decarbonization of the pyrolysis coke with oxygen addition at temperatures of 300-800°C to release phosphorus. This segmentation allows optimal conditions for each function - energy recovery in the first stage and phosphorus release in the second stage.
Solution Approach 2:
The pyrolysis step (a) is performed as a preliminary action before decarbonization. By first converting the biomass to pyrolysis coke without oxygen, the phosphorus is concentrated in a form that can be efficiently released in the subsequent decarbonization step with oxygen addition, maximizing plant-available phosphorus yield.
2Power
If incineration is performed at high combustion temperatures, then energy yield is achieved, but phosphorus compounds sinter and are no longer retained in plant-available form
Solution Approach 1:
The process separates incineration into two stages: (a) pyrolysis without oxygen at 300-800°C to avoid sintering, and (b) controlled decarbonization with oxygen at 300-800°C to release phosphorus. This prevents the high-temperature sintering that occurs in conventional single-stage incineration while still achieving energy recovery and phosphorus release.
Solution Approach 2:
The process controls the temperature parameter to remain below 800°C throughout both pyrolysis and decarbonization stages, preventing the sintering of phosphorus compounds. Additionally, the oxygen concentration is controlled - absent during pyrolysis and added during decarbonization - to achieve phosphorus release without high-temperature sintering.
3Productivity
If sewage sludge is dried before incineration or pyrolysis, then processing efficiency is improved, but the gel-like substance binds water strongly and hinders the drying process
Solution Approach 1:
The process separates water removal from thermal conversion by performing pyrolysis on wet or partially dried biomass. The anaerobic conditions of pyrolysis allow water to be driven off without forming the problematic glue phase that occurs during aerobic drying, eliminating the need for extensive pre-drying.
Solution Approach 2:
Pyrolysis is performed in an inert atmosphere without oxygen, which prevents the formation of the gel-like glue phase that binds water strongly. This allows efficient water removal during the pyrolysis process itself, eliminating the need for separate costly drying operations with extruders or belt dryers.
4Quantity of substance
If acid digestion is performed to increase phosphorus availability, then plant-available phosphorus increases, but production costs increase significantly
Solution Approach 1:
The process extracts phosphorus from the biomass through controlled decarbonization of pyrolysis coke with oxygen addition at 300-800°C. This thermal extraction method releases phosphorus in plant-available form without requiring expensive acid digestion, achieving the same goal at lower cost.
Solution Approach 2:
The process uses inexpensive thermal energy and oxygen to achieve phosphorus release, replacing the expensive acid digestion step. The pyrolysis coke serves as an intermediate that can be easily converted to release phosphorus without requiring costly chemical reagents like acids.
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 process achieves a high percentage of plant-available phosphorus in the ash, making it suitable for immediate use as a fertilizer, while also being energy-efficient and reducing the need for costly acid digestion steps.
Implementation Method 1
pyrolysis of the at least one phosphorus-containing substrate at a temperature of up to a maximum of 800°C without the addition of oxygen
Implementation Method 2
decarbonization of the pyrolysis coke obtained after step (a) with the addition of oxygen at a temperature in a range from 300°C to 600°C
Data Source
AI summary
The present invention relates to a process for producing phosphorus-containing ash from at least one phosphorus-containing substrate selected from the group consisting of phosphorus-containing biomass, comprising at least steps (a) and (b), namely pyrolysis of the at least one phosphorus-containing substrate at a temperature of up to 800°C without the supply of oxygen to obtain a pyrolysis coke (step (a)) and decarbonization of the pyrolysis coke obtained after step (a) with the supply of oxygen at a temperature in the range of 300°C to <600°C to obtain a phosphorus-containing ash (step (b)), and the phosphorus-containing ash obtainable by this process, as well as the use of this phosphorus-containing ash as a fertilizer or fertilizer additive and/or for the production of fertilizers.