Gas Ejector for NOx Evacuation from Nitric Acid Storage

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Solution Overview

Problem

Conventional systems for neutralizing NOx gases from nitric acid storage tanks are complex, costly, and require a large area footprint, often involving water washing which has limitations.

Innovation Solution

A gas ejector system is used to evacuate NOx gases from nitric acid storage tanks by utilizing tail gas as a motive gas to create a pressure difference, allowing for the evacuation and dilution of NOx gases without the need for water washing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional water washing systems are used to neutralize NOx gases, then the NOx gases can be treated, but the system becomes complex, costly, and requires large area footprint

Engineering Contradiction:
ImproveNOx gas treatment effectivenessVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of NOx gas evacuation from the complex water washing system and implements it using a simple gas ejector device. The ejector creates a vacuum effect to draw out NOx gases directly from the storage tank without requiring water washing towers, pumps, or complex neutralization systems, thereby maintaining treatment effectiveness while dramatically reducing system complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses pneumatic principles by employing a gas ejector that utilizes high-pressure gas flow to create a vacuum effect and evacuate NOx gases from the storage tank. This pneumatic approach replaces the hydraulic water washing system, achieving gas treatment through gas dynamics rather than liquid absorption, thus simplifying the overall system

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Object-affected harmful factors

If conventional water washing systems are used to neutralize NOx gases, then the NOx gases can be treated, but the area footprint becomes large

Engineering Contradiction:
ImproveNOx gas treatment effectivenessVSAvoidarea footprint
Core Design Contradiction:
Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent extracts and eliminates the large water washing infrastructure from the system, replacing it with a compact gas ejector device. This extraction of the essential evacuation function from the bulky water washing system achieves the same NOx treatment effectiveness in a much smaller footprint

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The gas ejector system is self-contained and uses the process gas itself to create the vacuum effect needed for evacuation. This self-service approach eliminates the need for separate water supply systems, drainage systems, and neutralization equipment that would increase the area footprint

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If conventional water washing systems are used to neutralize NOx gases, then the NOx gases can be treated, but the operational costs increase

Engineering Contradiction:
ImproveNOx gas treatment effectivenessVSAvoidoperational costs
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The gas ejector system uses the existing high-pressure gas flow from the process as the driving force for evacuation, making the system self-powered. This eliminates the need for external water pumps, blowers, and energy-intensive water heating systems required by conventional water washing, thereby reducing operational energy costs

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system recovers and utilizes the high-pressure gas that would otherwise be wasted or require additional compression. By using this available high-pressure gas to drive the ejector, the system converts a potential waste stream into a useful resource, reducing the need for additional energy input

Inventive Principle:
Principle #34Discarding and recovering

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 gas ejector system simplifies the process of NOx gas evacuation, reduces the area footprint, and lowers operational costs compared to traditional scrubbing systems, while effectively handling NOx gases.

Implementation Method 1

utilizing tail gas as a motive gas to create a pressure difference, allowing for the evacuation and dilution of NOx gases

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentEP4347485B1System for evacuating NOX gases from a nitric acid storage tank
Publication Date: 2025.06.04 YARA INTERNATIONAL ASA
  • EP4347485B1 patent drawingFigure 1
  • EP4347485B1 patent drawingFigure 2
  • EP4347485B1 patent drawingFigure 3

AI summary

The present disclosure relates to a system for evacuating NOx gases from a nitric acid storage tank in a nitric acid production plant. The system is characterized in that the nitric acid production plant comprises a gas ejector comprising at least two gas inlets and at least one gas outlet, wherein: • a first gas inlet of the gas ejector is branched from a gas conduit of the nitric acid production plant through which NOx-containing gas is flowing at a pressure P1 ranging from 2 bar to 16 bar; • a second gas inlet of the gas ejector is fluidically connected to the nitric acid storage tank essentially maintained at atmospheric pressure; and • a gas outlet of the gas ejector is fluidically connected to a gas conduit of the nitric production plant through which NOx-containing gas is flowing at a pressure P2 which is lower than P1. The present disclosure further relates to a method for evacuating NOx gases from a nitric acid storage tank, in a system according to the system of the disclosure. The present disclosure also relates to a method for revamping the system of a nitric acid plant according to the prior art into a system according to the system of the disclosure. Finally, the present disclosure relates to the use of a gas ejector for evacuating NOx gases from a nitric acid storage tank released therein, in a production plant for producing nitric acid or in a storage area for nitric acid.