Fluidized Calciner Fuel Injection Positioning for Low-Quality Coal
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Solution Overview
Problem
The existing fluidized calciners face challenges in reducing the rate of unburned fuel at the outlet when using pulverized coal or coke with low combustion quality, leading to elevated temperatures and occlusion issues in the preheater, which hinders operation and refractory wear.
Innovation Solution
A fluidized calciner design with a pulverized coal blowing line connected to the side of the tubular furnace body, positioned below the suction port of the air introduction pipe and above the fluidizing air blowing port, optimizing the fuel supply to achieve improved combustion by impacting the fuel with introduced air in areas of low raw material concentration and high O2 concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pulverized coal with low combustion quality is used as fuel, then resource utilization is improved, but the rate of unburned fuel at the outlet increases and combustion occurs in the suspension preheater
Solution Approach 1:
The patent applies local quality by creating distinct zones within the fluidized calciner with different characteristics: a primary combustion zone near the fuel injection point and a secondary combustion zone in the free board area. The fuel injection port is positioned to inject fuel into a region with specific airflow patterns that promote complete combustion, while the free board area provides additional combustion zone with different temperature and oxygen conditions. This zonal differentiation allows efficient combustion of low-quality fuels by matching local conditions to fuel combustion requirements.
Solution Approach 2:
The patent utilizes the vertical dimension by positioning the fuel injection port at a specific height relative to the fluidized bed and free board. The fuel is injected into the upper region of the fluidized bed, utilizing the vertical airflow and temperature gradient to enhance combustion. The free board area above the fluidized bed provides an additional vertical zone for combustion, creating a multi-level combustion strategy that improves fuel utilization and reduces unburned fuel carryover.
2Use of energy by moving object
If combustion occurs in the suspension preheater, then fuel combustion is achieved, but the temperature in the preheater is elevated and attachment is generated in the cyclone or raw material chute
Solution Approach 1:
The patent extracts the combustion process from the suspension preheater by providing a dedicated combustion zone within the fluidized calciner. The fuel injection port is positioned to confine combustion to the calciner interior, specifically in the fluidized bed and free board areas, rather than allowing combustion to extend into the suspension preheater. This spatial separation removes the harmful effect of combustion-induced temperature elevation from the preheater while maintaining fuel energy utilization.
Solution Approach 2:
The fluidized bed acts as an intermediary zone between fuel injection and the suspension preheater. The fluidized bed provides a controlled environment for fuel combustion, absorbing the thermal energy and preventing direct transfer to the suspension preheater. The airflow patterns in the fluidized bed serve as a mediator, directing combustion products and heat within the calciner while protecting the preheater from excessive temperature rises.
3Reliability
If the blowing port of the pulverized coal blowing line is positioned to optimize combustion, then the rate of unburned fuel is reduced, but the device complexity increases
Solution Approach 1:
The fuel injection port is designed to serve multiple functions: it acts as a fuel delivery mechanism, a flow distributor, and a combustion initiator. By positioning the fuel injection port at the optimal location and designing it with appropriate geometry, the system achieves efficient combustion of low-quality fuels without requiring complex additional components. The single fuel injection port handles fuel supply, airflow generation, and combustion promotion, reducing overall device complexity while maintaining high combustion efficiency.
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 reduces the rate of unburned fuel at the outlet, maintains low preheater temperatures, prevents occlusion, and minimizes refractory wear, ensuring efficient calcination and operation even with low-quality fuels.
Implementation Method 1
high-pressure air is blown in through a fluidization air blowing port 13, an air chamber 13a, and an air dispersing plate 14 to form a fluidizing bed 15
Implementation Method 2
the high-pressure air causes combustion of a portion of fuel supplied through a pulverized supply pipe 16
Implementation Method 3
air from a hot clinker cooler 18 is sucked through a suction port 19 substantially in a tangential direction
Implementation Method 4
hot air generated in the clinker cooler 18 is sucked into the rotary kiln 20 and the fluidized calciner 11 by a suction force of an induction fan 23
Data Source
AI summary
A fluidized calciner is provided which allows a reduction in the rate of unburned fuel at an outlet of a fluidized calciner to enable sufficient calcination while preventing possible occlusion in a preheater, even when pulverized coal of coal or coke, which has low combustion quality, is used as fuel, based on calculations in accordance with computational fluid dynamics based on the shape of an actual furnace and operational conditions. The present invention provides a fluidized calciner including a tubular furnace body (2) in which an axial direction is an up-down direction, a pulverized coal blowing line (3) through which fuel is blown into the furnace body (2), a raw material chute (4) through which a cement raw material is loaded into the furnace body (2), at least one air introduction pipe (5) through which introduced air is sucked, the pulverized coal blowing line (3), the raw material chute (4), and the air introduction pipe (5) being connected to a side portion of the furnace body (2), and a fluidizing air blowing port (6) disposed at a bottom portion of the furnace body (2) and through which fluidizing air is blown into the furnace body (2), in which a blowing port of the pulverized coal blowing line (3) is disposed below a suction port of the air introduction pipe (5) and above the fluidizing air blowing port (6).