Solid Fuel Burner Guide Members for Ash Prevention
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Solution Overview
Problem
Existing solid fuel burners face issues with preventing components from being burnt by furnace radiation, ash deposition, and maintaining stable ignition and flame stability, particularly when used with coal, due to inadequate cooling and interference with hot circulating flows.
Innovation Solution
The design incorporates a solid fuel burner with a fuel nozzle, secondary and tertiary combustion gas nozzles, and guide members that direct secondary combustion gas flows to prevent radiation damage and ash deposition, while maintaining stable ignition and flame stability by creating separate circulating flows that draw in hot gases without disturbing the flame stabilizing zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a guide plate is provided at the end of a partition between pulverized coal nozzle and secondary air nozzle to control jet direction of secondary air flow, then the jet angle of secondary air flow can be made larger than the jet angle of tertiary air flow, but the guide plate directly receives radiation from the furnace and may be burnt
Solution Approach 1:
A water-cooled guide plate is introduced as an intermediary component between the secondary air nozzle and the furnace environment. The guide plate includes a water supply passage that delivers cooling water to its outer surface, which directly receives radiation from the furnace. This mediator structure protects the guide plate from burning while maintaining its function of controlling the jet angle of secondary air flow.
Solution Approach 2:
The guide plate's thermal state is changed by introducing water cooling, transforming it from a dry, radiation-exposed component to a cooled, radiation-resistant component. The parameter change involves introducing a cooling medium (water) that alters the thermal parameters of the guide plate, enabling it to withstand furnace radiation while maintaining structural integrity.
2Temperature
If cooling air is ejected into the furnace from the flame stabilizing ring to cool it, then the flame stabilizing ring can be effectively cooled, but the cooling air may interfere with the formation of the circulating flow composed of hot air and pulverized coal in the vicinity of the flame stabilizing ring
Solution Approach 1:
The cooling air ejection is segmented into multiple discrete cooling holes distributed on the flame stabilizing ring, rather than a single large opening. This segmentation allows cooling air to be ejected in a controlled manner that minimizes interference with the circulating flow while still achieving effective cooling of the flame stabilizing ring.
Solution Approach 2:
The cooling function is applied locally at specific points on the flame stabilizing ring where cooling holes are provided, rather than cooling the entire structure uniformly. This local quality approach allows targeted cooling of critical areas while minimizing disruption to the overall circulating flow pattern.
3Stability of the object's composition
If a large circulation zone is formed downstream of the collar to stabilize flame, then the flame can be stabilized, but ash may easily deposit on the collar when the burner structure is employed for solid fuel such as coal
Solution Approach 1:
The harmful effect of ash deposition on the collar is extracted and addressed by providing a separate air passage that leads to the tapered part through the collar. This air passage enables cooling air to reach the collar and prevent ash deposition, separating the flame stabilization function (large circulation zone) from the ash prevention function (cooling air passage).
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 configuration effectively prevents component burning and ash deposition, maintains stable ignition and flame stability, and reduces NOx and unburned combustible contents in ash by optimizing the flow angles and cooling of guide members within the burner.
Implementation Method 1
a guide members that direct secondary combustion gas flows
Implementation Method 2
cooling of guide members within the burner
Implementation Method 3
creating separate circulating flows that draw in hot gases
Implementation Method 4
burning a solid fuel such as coal
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A first guide member (34) and, to the rear side thereof, a second guide member (35), for a secondary air flow (17), are provided in the outlet end part of a fuel nozzle (11) on a partition (29) which is the outer circumferential wall of the nozzle (11). The second guide member (35) is retained by a plurality of cooling fins (36) which are positioned uniformly around the entire circumference of the nozzle partition (29), and the first guide member (34) forms the secondary air flow (17a) and the secondary air flow (17b) conducted from the gap between the second guide member (35) and the partition (29) to the front surface side of the second guide member (35), into an outward flow from the centre axis of the burner, which can cool the front surface side of the second guide member (35) and prevents deposition of ash on it, thereby maintaining the fuel ignition and flaming stability at the burner outlet.