Dense-Phase Sorbent Injection System for Coal Plant Emissions

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Solution Overview

Problem

Current sorbent injection systems for coal-fired power plants, particularly those using dilute-phase pneumatic conveying, face limitations in conveying distance, feed rate, and sorbent degradation, which can be overcome by adopting dense-phase pneumatic conveying systems.

Innovation Solution

Implementing a dense-phase pneumatic conveying system that transports sorbents from a storage vessel to injectors in a contaminated gas stream using high gas pressures and low sorbent velocities below the saltation velocity, with a system comprising storage vessels, feeders, valves, and a controller for efficient additive introduction and pressure management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If dilute-phase pneumatic conveying is used to transport sorbents, then the system can operate with high velocities above saltation velocity, but the conveying distance and feed rate are limited and sorbent degradation occurs

Engineering Contradiction:

Improveconveying distance and feed rateVSAvoidsorbent degradation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by transitioning from dilute-phase to dense-phase pneumatic conveying, fundamentally changing the operating parameters from high velocity/low pressure to low velocity/high pressure. This parameter transformation enables increased conveying distance and feed rate while reducing sorbent degradation, as the lower velocities prevent excessive abrasion and the higher pressures improve conveying capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes pneumatic principles by employing dense-phase pneumatic conveying where compressed gas at high pressure transports sorbent material at low velocity. The system uses a gas compressor to provide pressurized gas that moves sorbent through the conveying line, eliminating the need for high velocity operation and its associated drawbacks of sorbent degradation and limited conveying distance.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Speed

If high velocity pneumatic conveying is used, then sorbent can be transported quickly, but sorbent abrasion and degradation increase

Engineering Contradiction:

Improvesorbent transport velocityVSAvoidsorbent abrasion

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional approach by using low velocity instead of high velocity for pneumatic conveying. Rather than relying on high speed to transport sorbent, the system uses high pressure to push the sorbent through the conveying line at reduced speeds, thereby eliminating the harmful abrasion and degradation that occur at high velocities.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the key parameter of conveying velocity from high to low, transforming the operating conditions to reduce sorbent abrasion. By operating below saltation velocity, the system minimizes particle-particle and particle-wall collisions that cause wear and degradation, while still achieving effective transport through the combined effect of high pressure and optimized gas flow.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If dilute-phase pneumatic conveying is used, then the system structure is simpler, but conveying distance and feed rate capabilities are limited

Engineering Contradiction:

Improvefeed rate capabilityVSAvoidsystem structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs pneumatic conveying technology to achieve high feed rate capability without significantly increasing system complexity. The dense-phase pneumatic system uses a gas compressor and controlled gas flow to transport large quantities of sorbent through the conveying line, enabling high productivity while maintaining a relatively simple system structure based on standard pneumatic components.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 approach reduces sorbent abrasion and degradation, enhances solids-to-air ratio efficiency, and increases conveying distance and rate capabilities, allowing for effective contaminant removal in coal-fired power plant emissions control.

Implementation Method 1

Pneumatic conveying of sorbent material is a common method of introducing sorbent into contaminated gas streams. It operates by creating a pressure differential along a pipeline and using the air that moves toward the area of lower pressure to move bulk sorbent material.

Methodology Applied

Scientific EffectPneumatic conveying:

Implementation Method 2

The process can be performed with a vacuum inducer or by injecting compressed air into one end of or along a pipeline.

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

Sorbents used for emission control at coal-fired power plants may include, for example, powdered activated carbon (PAC) for mercury control, dry sorbent injection (DSI) including powdered trona, lime and sodium bicarbonate for acid gas control

Methodology Applied

Scientific EffectAdsorption: Adsorption