Supercritical Water Oxidation System for Sludge Treatment
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Solution Overview
Problem
Conventional supercritical water oxidation (SCWO) technology for treating petrochemical sludge faces high costs due to stringent reaction conditions, material requirements, and issues with coking and heat control, necessitating a more economical and efficient treatment method.
Innovation Solution
A near-zero-release treatment system comprising a wastewater transport unit, reaction unit, oxygen supplying unit, and reprocessing unit, which includes a sludge grinder, high-pressure variable-frequency plunger pump, tubular reactor, self-cleaning filter, MVR crystallization unit, and advanced treatment unit, allowing for effective oxidation and separation of organic substances under controlled conditions, reducing material costs and preventing coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SCWO technology is used to achieve high removal rate of organic substances, then the theoretical removal rate reaches over 99.9%, but the cost increases extremely high due to stringent reaction conditions and material requirements
Solution Approach 1:
The patent changes the reaction parameters by using a tubular reactor design that enables rapid heating and cooling, achieving supercritical conditions (temperature above 374°C and pressure above 22.1 MPa) for efficient oxidation while reducing the need for expensive nickel-based alloys through controlled parameter management
Solution Approach 2:
The patent replaces expensive nickel-based alloys with stainless steel or other cost-effective materials that can withstand the reaction conditions, accepting that these materials may have limited service life but significantly reducing initial investment and operational costs
2Temperature
If preheating is done by heating furnace, then the sludge is heated to reaction temperature, but the temperature in pipes becomes extremely high causing coking and tube burst
Solution Approach 1:
The patent uses a tubular reactor with rapid heating capability that quickly brings the sludge to supercritical conditions and maintains it for a very short residence time (0.5-5 seconds), skipping the prolonged high-temperature exposure that causes coking
Solution Approach 2:
The patent performs preliminary grinding of sludge to reduce particle size before injection, preventing coking by ensuring uniform heat distribution and rapid reaction, eliminating the need for extended high-temperature heating
3Temperature
If gas heating furnace is used for temperature compensation, then heating can be provided, but the heating amount becomes uncontrollable
Solution Approach 1:
The patent implements a feedback control system with temperature sensors and variable frequency drives that continuously monitor reaction conditions and adjust the injection rate and heating power to maintain optimal supercritical conditions, enabling precise temperature control
4Temperature
If electric heating furnace is used for temperature compensation, then heating can be provided, but the heating startup time becomes long and thermal inertia is strong
Solution Approach 1:
The patent replaces traditional electric heating furnaces with a tubular reactor design that uses the exothermic oxidation reaction itself to maintain temperature, supplemented by localized electric heating elements with rapid response time, eliminating thermal inertia and enabling instant temperature adjustment
5Reliability
If nickel-based alloys are used for reactor devices, then corrosion resistance is improved, but the initial investment becomes extremely high
Solution Approach 1:
The patent changes the material selection based on modified reaction parameters achieved through rapid heating and cooling in a tubular reactor, which reduces the severity and duration of corrosive conditions, allowing the use of stainless steel or other cost-effective materials instead of nickel-based alloys
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 system achieves near-zero-release of industrial wastewater and sludge by efficiently oxidizing organic substances, reducing material costs, and preventing coking, while allowing for stable landfill and recovery of inorganic salts, with carbon dioxide and nitrogen being the primary byproducts.
Implementation Method 1
the oxidizing agent and organic substances fully dissolve in the supercritical water and carry out homogeneous oxidation reaction to rapidly, thoroughly transfers organic substances into harmless small molecule compound such as carbon dioxide, Nitrogen, water and etc.
Implementation Method 2
The supercritical water is refers to water with a temperature and a pressure higher than the critical point (374.15° C., 22.1 MPa). The properties of the supercritical water changes significantly that the density, dielectric constant, diffusion coefficient and thermal conductivity is different to the normal water.
Implementation Method 3
one end of the heat exchange tube is communicated with the inside of the reaction kettle, and the other end of the heat exchange tube is communicated with the inside of the water tank; the water tank is used for storing the wastewater to be treated
Implementation Method 4
a high-pressure variable-frequency plunger pump is located on a pipeline between the sludge buffer tank and the heat exchanger
Data Source
AI summary
A near-zero-release treatment system and method for high concentrated organic wastewater is in the chemical engineering and environment protection field, whose core technology is SCWO. The wastewater and sludge are grinded by the homogeneous pump, pressurized by high-pressure plunger pump, transported to successive pipeline for preheating and mixing with the oxygen and undergoes SCWO reaction in the reactor. After pressure release in the pressure relief device, the reacted fluid passes through the self-cleaning filter and gas liquid separator for insoluble solid and gas separation; then enters the MVR for crystallization of the soluble salts to realize near-zero-release of the feeding. The regular water treatment technology (coagulation sedimentation, membrane biotechnology, membrane technology, etc.) is adopted to complement SCWO, which lowers the operating parameters of the reactor and cuts the operating cost by treating the remaining COD with regular water treatment technology.