Ammonium Chloride Decomposition with Cyclic Medium Gas Separation
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Solution Overview
Problem
The existing methods for decomposing ammonium chloride into hydrogen chloride and ammonia gas face challenges such as high volatilization of ammonium chloride and difficulty in separating the generated gases, limiting large-scale industrial applications.
Innovation Solution
A system and method involving a reactor with a solid particle feed apparatus for continuous addition of ammonium chloride, utilizing ammonium hydrogen sulfate as a cyclic medium, and employing multiple reactors or different reaction stages to facilitate the decomposition and regeneration reactions, with temperature control and heat management to enhance conversion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ammonium chloride is heated to decompose into NH3 and HCl, then decomposition products are obtained, but a great amount of NH4Cl is sublimated simultaneously and the generated NH3 and HCl are difficult to be separated
Solution Approach 1:
The patent introduces an acidic cyclic medium (such as concentrated sulfuric acid or phosphoric acid) as an intermediary substance. This medium absorbs the ammonia gas produced during decomposition to form ammonium salt, preventing ammonia from mixing with hydrogen chloride. The ammonium salt is then thermally decomposed in a second stage to release pure ammonia gas. This intermediary approach solves both the volatilization loss problem and the gas separation difficulty.
Solution Approach 2:
The patent divides the decomposition process into two separate stages: first, hydrogen chloride is released by reacting ammonium chloride with acidic medium at lower temperature; second, ammonia is released by thermal decomposition of the formed ammonium salt at higher temperature. This segmentation allows each gas to be collected separately without mixing, and prevents simultaneous volatilization of ammonium chloride.
2Productivity
If ammonium chloride is heated to decompose into NH3 and HCl, then decomposition products are obtained, but small NH4Cl particles are easily to be regenerated
Solution Approach 1:
The acidic cyclic medium serves as an intermediary that converts gaseous ammonia into ammonium salt form, preventing the regeneration of ammonium chloride particles. The ammonium salt formed in the first stage is then decomposed in the second stage to release pure ammonia gas, ensuring product purity and preventing particle regeneration issues.
3Productivity
If a reusable acidic cyclic medium is added to react with NH3 generated by heating NH4Cl, then HCl is released first, but an integral preparation system which can be conveniently implemented in the industry hasn't been proposed
Solution Approach 1:
The patent combines the decomposition reactions and gas separation processes into an integrated two-stage reactor system. The first reactor performs the reaction between ammonium chloride and acidic medium to release HCl, while the second reactor thermally decomposes the formed ammonium salt to release NH3. This merged system provides a complete, industrially implementable solution that maintains high gas separation efficiency while simplifying overall process implementation.
Solution Approach 2:
The patent designs a continuous operation system where the acidic cyclic medium circulates between the two reactors. The medium is regenerated in the second reactor and continuously fed back to the first reactor, maintaining continuous useful action without interruption. This continuous operation enables convenient industrial implementation with steady production of both gases.
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 system improves the conversion rate and utilization of ammonium chloride by reducing volatilization and enabling efficient separation of hydrogen chloride and ammonia gas, making it suitable for industrial-scale operations.
Implementation Method 1
NH4Cl may be decomposed into NH3 and HCl by being heated
Implementation Method 2
a great amount of NH4Cl is sublimated simultaneously
Implementation Method 3
the medium first reacts with NH3 (or HCl) generated by a heating process, to form an intermediate product and HCl (or NH3) is released first
Implementation Method 4
the intermediate product is further pyrolyzed to release NH3 (or HCl)
Data Source
AI summary
Disclosed is a system and method for preparing hydrogen chloride and ammonia gas by using ammonium chloride. The system includes a decomposition reactor and at least one regeneration reactor, or includes a reactor that may serve as the decomposition reactor and the regeneration reactor; ammonium chloride in particle form is continuously added to the decomposition reactor via a solid particle feed apparatus, and reacts with molten-state ammonium hydrogen sulfate to generate hydrogen chloride gas and an intermediate material; the intermediate material is discharged to the regeneration reactor, and heated therein to decompose into ammonium hydrogen sulfate and ammonia gas; and the ammonium hydrogen sulfate is returned to the decomposition reactor for recycling. The present disclosure provides an industrial feasible implementation solution for continuous decomposition of ammonium chloride, lowers volatilization of ammonium chloride by continuously and slowly adding ammonium chloride in particle form, and improves utilization rate of the ammonium chloride.