Steam Sootblower Nozzle Segmentation for Ammonium Bisulfate Removal
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Solution Overview
Problem
Conventional steam sootblowers for rotary air preheaters are ineffective in removing highly cohesive ash deposition containing ammonium bisulfate due to the low temperature of the steam jet, which reduces the purging effect, as the steam temperature decreases upon entrainment by surrounding low-temperature flue gas.
Innovation Solution
A steam soot blowing device with high-velocity and low-velocity nozzle assemblies is designed, where the first nozzle assembly uses a throttle pipe to produce a low-velocity, high-temperature steam jet that gasifies ammonium bisulfate, followed by a second nozzle assembly producing a high-velocity, low-temperature steam jet to shear and purge the loosened ash deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-nozzle steam sootblower is used, then the structure is simple, but the purging effect on highly cohesive ash deposition containing ammonium bisulfate is limited due to low steam jet temperature
Solution Approach 1:
The steam sootblower nozzle is segmented into two distinct assemblies: a first nozzle assembly that generates high-temperature steam jets for heating and gasifying ammonium bisulfate, and a second nozzle assembly that generates high-velocity steam jets for shearing and purging ash deposition. This segmentation allows each nozzle assembly to be optimized for its specific function, resolving the contradiction between purging effectiveness and structural simplicity.
Solution Approach 2:
The first nozzle assembly performs preliminary heating and gasification of ammonium bisulfate in the ash deposition before the second nozzle assembly performs the actual purging. This preliminary thermal treatment weakens the bonding strength of the highly cohesive ash, making it susceptible to removal by the subsequent high-velocity steam jet, thereby significantly improving overall purging effectiveness.
2Speed
If steam pressure is increased to improve jet velocity, then the shearing effect is enhanced, but the steam temperature decreases due to entrainment of low-temperature flue gas
Solution Approach 1:
The contradiction between steam jet velocity and temperature is resolved by segmenting the steam jet generation into two separate nozzle assemblies. The first nozzle assembly is optimized for generating high-temperature steam jets (prioritizing temperature) to gasify ammonium bisulfate, while the second nozzle assembly is optimized for generating high-velocity steam jets (prioritizing speed) to shear and purge the weakened ash deposition. This segmentation allows both parameters to be optimized independently for their respective functions.
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 solution significantly improves the purging effect of ash deposition by transforming ammonium bisulfate into a fluffy structure, reducing its hardness and bonding strength, thereby enhancing the removal efficiency and uniformity of the ash deposition across the air preheater rotor.
Implementation Method 1
heats and gasifies ammonium bisulfate in the ash deposition on the surface of the heat exchange elements through low-velocity and high-temperature steam jet
Implementation Method 2
gasifies ammonium bisulfate, so that the compact ash deposition is changed into a fluffy structure
Implementation Method 3
the loosed ash deposition without ammonium bisulfate was sheared and purged by using high-velocity and low-temperature steam jet
Implementation Method 4
steam jets to scour the surfaces of the heat exchange elements on-line intermittently, to blow off the ash deposition on the surfaces by shearing
Data Source
AI summary
A steam soot blowing device is provided, including: a steam sootblower, a first pipe communicating with the steam sootblower; and nozzle assemblies communicating with the first pipe, including a first nozzle assembly and a second nozzle assembly, wherein the first nozzle assembly includes a throttle pipe with one end communicating with the first pipe, and a sprayer communicating with the other end of the throttle pipe, and diameter of an inlet of the sprayer is smaller than diameter of an outlet thereof; the second nozzle assembly includes a distribution pipe communicating with the first pipe and at least one nozzle communicating with the distribution pipe, wherein steam jet velocity at the outlet of the sprayer is greatly smaller than steam jet velocity at an outlet of the nozzle.