In-line Milling System for Sorbent Particle Size Control
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Solution Overview
Problem
Current air pollution control technologies face challenges in effectively controlling both SO2 and SO3 emissions from coal-fired power plants, particularly in accommodating varying particle sizes of trona/sodium bicarbonate sorbents, preventing clogging, and minimizing downtime and moisture introduction during cleaning cycles in pneumatic conveying systems.
Innovation Solution
An in-line milling system with multiple mills and electronic controllers is designed to process sorbent materials, ensuring optimal particle size for duct injection, preventing clogging, and implementing bypass configurations and controlled drying to maintain system performance and reduce downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If trona/sodium bicarbonate is pre-milled by the supplier to smaller particle size, then the material becomes more cost-effective and efficient for absorption, but it becomes more difficult to handle, does not flow properly, and causes agglomeration and clogging in delivery and piping systems
Solution Approach 1:
The milling process is segmented into two distinct stages: pre-milling at the supplier's facility to reduce particle size to a manageable range, and final milling at the injection system to achieve the precise target particle size. This segmentation allows the sorbent to be handled more easily during transport while still achieving the desired fine particle size for effective absorption when finally milled and injected.
2Device complexity
If a single duct injection system is used to accommodate multiple trona/sodium bicarbonate sources with varying particle sizes, then system simplicity is maintained, but it becomes difficult to accommodate multiple sources with different particle size ranges
Solution Approach 1:
The system incorporates adjustable milling parameters and controllable feed rates that can be dynamically modified based on the specific particle size characteristics of different sorbent sources. This dynamic adaptability allows a single injection system to effectively handle multiple trona/sodium bicarbonate sources with varying initial particle sizes by optimizing the milling process for each material source.
3Reliability
If the sorbent milling and delivery system is cleaned routinely to maintain system performance, then good system performance is maintained, but downtime is incurred during cleaning cycles
Solution Approach 1:
The system is designed with continuous sorbent delivery capability that maintains emission treatment during cleaning operations. By implementing a design where sorbent can continue to be delivered and injected into the duct while the milling mechanism undergoes cleaning, the system maintains its useful function without interruption, eliminating downtime associated with cleaning cycles.
4Ease of manufacture
If water is used to flush residual sorbent from the mill during cleaning, then cleaning effectiveness is improved, but moisture is introduced into the system which can cause unwanted agglomeration
Solution Approach 1:
An intermediary drying step is introduced between the water flushing and sorbent delivery processes. This drying mechanism removes introduced moisture before the sorbent material is reintroduced into the system, preventing agglomeration while maintaining the cleaning effectiveness of the water flush. The intermediary drying action mediates between the conflicting requirements of thorough cleaning and moisture prevention.
Data Source
AI summary
The present invention provides an in-line system for milling sorbent material to be used in a pneumatic conveying system. The system provides for optimal particle size in a duct injection system, regardless of the original sorbent particle size, and is designed to prevent clogging of the milled material through the system. Methods of operation for milling, as well as cleaning the mills while providing various sorbent material by-pass configurations to minimize system down-time while enhancing material throughput and that support the unique aspects of the system, are also described in detail below.