Coaxial Oxygen Lance for High-Pressure Fluidized Bed Gasification
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Solution Overview
Problem
The existing oxygen lances used in high-temperature Winkler process gasification reactors fail at pressures above 8 to 10 bar due to condensation issues when preheated oxygen is introduced, leading to a loss of the protective steam veil and potential caking, which compromises the operation and safety of the fluidized bed gasification process.
Innovation Solution
A coaxially arranged oxygen lance with three tubes, where the outermost tube carries superheated steam, the middle tube is for dry gas, and the innermost tube for oxygen at 180°C, ensuring a temperature-controlled gas mixture that prevents condensation and maintains a vapor veil around the oxygen jet, even at elevated pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If preheated oxygen is introduced into the oxygen lance at high pressure, then the oxygen injection efficiency is improved, but condensation occurs on the steam side of the oxygen-carrying tube leading to failure of the oxygen lance
Solution Approach 1:
The oxygen lance is divided into three separate coaxial tubes: an outermost tube for superheated steam, a middle tube for dry gas, and an innermost tube for preheated oxygen. This segmentation allows each tube to handle its specific medium independently, preventing condensation issues in the oxygen tube while maintaining efficient oxygen injection through the innermost tube at the center
Solution Approach 2:
Superheated steam is introduced as an intermediary substance in the outermost tube to create a protective vapor veil around the oxygen jet. This steam barrier prevents direct contact between the preheated oxygen and cooler external environments, eliminating condensation on the oxygen tube while enabling high-pressure oxygen injection
2Productivity
If the oxygen temperature is increased to improve injection performance, then the oxygen reaction efficiency is improved, but the temperature exceeds safety limits damaging standard industrial equipment
Solution Approach 1:
The oxygen temperature is optimized to exactly 180°C, which is the maximum safe temperature for standard industrial equipment. At this temperature, the oxygen achieves sufficient reaction efficiency while remaining below the damage threshold for seals and other equipment components
3Reliability
If steam is introduced at high pressure to maintain vapor veil, then the protective effect is improved, but condensates form on the steam side above 8 to 10 bar pressure
Solution Approach 1:
The steam in the outermost tube is superheated to a temperature significantly higher than the oxygen temperature (e.g., 400-500°C vs 180°C). This local quality difference ensures that even at high pressures above 10 bar, the steam remains in a superheated state and does not condense on the steam tube walls, maintaining the protective vapor veil function
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 design allows for safe and efficient oxygen injection at pressures above 10 bar, preventing caking and ensuring continuous operation by maintaining a stable vapor curtain around the oxygen lance, thus enhancing the reliability and safety of the gasification process.
Implementation Method 1
the innermost pipe is designed for the passage of oxygen hot at a temperature of a maximum of 180 °C
Implementation Method 2
superheated water vapor is introduced into a cladding tube
Implementation Method 3
The turbulence that forms in the emerging gas jet has a very high steam content
Implementation Method 4
a temperature probe is arranged in the innermost tube, which extends to just before the mouth of the innermost tube
Implementation Method 5
the innermost tube tapers like a nozzle in front of its mouth
Data Source
Figure 1
Figure 2
AI summary
The invention relates to an oxygen lance that has at least three mutually coaxial pipes, each of which delimits at least one annular gap. The outermost pipe is designed to conduct superheated steam and has a steam supply point, the central pipe is designed as an annular gap, and the innermost pipe is designed to conduct oxygen at a temperature of no higher than 180 °C and has an oxygen supply point. A temperature sensor is arranged within the innermost pipe, said temperature sensor extending to just in front of the opening of the innermost pipe. The innermost pipe tapers in the form of a nozzle before opening; the innermost pipe opens into the central pipe; and the opening of the central pipe protrudes farther relative to the opening of the outermost pipe.