Ammonium Nitrate Production via Dual-Loop NOx Absorption
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Solution Overview
Problem
Current ammonia scrubbing systems face inefficiencies and safety concerns, particularly with acid scrubbers using hazardous chemicals and producing low-concentration N-nutrient products, while biological scrubbers are less reliable and less efficient in capturing ammonia.
Innovation Solution
A system utilizing two liquid loops with separate gas-liquid contactors, one for in-situ generation of nitric acid and the other for ammonia capture, allowing pH control and increased pressure to enhance NOx conversion and solubility, using oxygen-enriched air to optimize NOx generation and recycling, thereby producing a high-concentration ammonium nitrate solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acid scrubbers use concentrated sulphuric acid to capture ammonia, then ammonia capture efficiency is improved, but safety risks and handling complexity increase due to hazardous chemicals
Solution Approach 1:
The invention changes the chemical parameters by using nitric acid instead of sulphuric acid, and by controlling the concentration and pH levels dynamically. The system maintains pH between 1-6 in the gas-liquid contactor and adjusts it to pH 4-6.9 in the ammonia scrubbing unit, optimizing both capture efficiency and safety by avoiding highly concentrated hazardous acids.
Solution Approach 2:
The invention introduces nitric acid as an intermediary substance that mediates between ammonia capture and nitrogen fertilizer production. Nitric acid serves as a safer alternative to sulphuric acid while enabling the production of high-value ammonium nitrate product, thus resolving the contradiction between efficient capture and safety concerns.
2Productivity
If acid scrubbers produce dilute ammonium sulphate solution, then ammonia capture is achieved, but N-nutrient concentration in the liquid product is low
Solution Approach 1:
The invention changes the chemical composition parameters by using nitric acid instead of sulphuric acid, which fundamentally alters the product from dilute ammonium sulphate to concentrated ammonium nitrate. The system achieves N-nutrient concentrations of 300-500 g/L (30-50% w/v) by controlling the reaction between ammonia and nitric acid, thereby resolving the contradiction between capture and nutrient concentration.
Solution Approach 2:
The invention converts the potentially harmful byproduct of ammonia scrubbing (dilute ammonium sulphate with low nutrient value) into a valuable high-concentration nitrogen fertilizer (ammonium nitrate). This transformation turns a low-value product into a high-value resource, resolving the contradiction between achieving ammonia capture and producing high N-nutrient concentration.
3Object-affected harmful factors
If biological scrubbers are used to remove ammonia, then chemical hazards are reduced, but capture efficiency and reliability decrease
Solution Approach 1:
The invention changes from biological processes to chemical processes by using nitric acid-based gas-liquid contact. This chemical approach provides faster, more reliable, and more efficient ammonia capture compared to biological methods, while maintaining safety by avoiding hazardous sulphuric acid. The system achieves superior capture efficiency through controlled chemical reactions rather than dependent biological processes.
4Device complexity
If single liquid loop system is used, then device complexity is reduced, but pH control and process optimization are limited
Solution Approach 1:
The invention segments the single liquid loop into two separate liquid loops: one for nitric acid generation (high pressure, pH 1-6) and one for ammonia scrubbing (low pressure, pH 4-6.9). This segmentation allows independent optimization of each loop's parameters, improving overall process efficiency while maintaining manageable complexity through modular design.
Solution Approach 2:
The invention introduces dynamic pH control in both liquid loops, adjusting pH levels independently in each loop according to process requirements. The first loop maintains pH 1-6 for optimal nitric acid generation, while the second loop maintains pH 4-6.9 for optimal ammonia capture. This dynamic control enables precise process optimization that static single-loop systems cannot achieve.
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 effectively captures ammonia, reduces energy costs, minimizes hazardous chemical use, and produces a high-concentration N-nutrient product, improving efficiency and safety compared to existing systems.
Implementation Method 1
in-situ generation of nitric acid (HNO3) by reacting NOx gasses with an aqueous solution in a gas-liquid contactor
Implementation Method 2
reacting NOx gasses with an aqueous solution in a gas-liquid contactor (e.g. an absorption column)
Implementation Method 3
These acids combine with ammonia to form a solution of ammonium nitrate
Implementation Method 4
The ammonium nitrate and possibly ammonium nitrite salts can be precipitated to produce a solid product
Implementation Method 5
The finely divided water absorbs ammonia from the air
Data Source
Figure 1
AI summary
The present invention relates generally to an ammonia capture system or method comprising a NOx source or NOx generator (G) and, more particularly to such system and method for ammonia capture comprising a two-tank NOx absorption system. Furthermore the present invention concerns a system to produce ammonium nitrate in solution or as a solid from atmospheric ammonium.