Inductive Heating for Ammonia Converter Startup
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Solution Overview
Problem
Conventional gas fired heaters are inefficient for start-up heating of ammonia synthesis converters, leading to energy losses and suboptimal heating processes.
Innovation Solution
Inductive heating using an alternating high-frequency current passed through an inductive coil placed inside the reactor, with the catalyst in direct contact, allowing for efficient heat generation within the catalyst bed without external heat sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a gas fired heater is used for start-up heating, then the converter can be heated, but energy losses occur and heating efficiency is reduced
Solution Approach 1:
The patent replaces the conventional gas fired heater (thermal system) with an inductive heating system using electromagnetic fields. The induction coil generates a magnetic field that induces eddy currents in the catalyst bed, converting electromagnetic energy directly into heat within the catalyst material itself, thereby eliminating energy losses associated with gas combustion and heat transfer through reactor walls.
Solution Approach 2:
The catalyst bed serves dual purposes: it acts as both the catalytic material and the heating element. The magnetic field induces eddy currents directly in the catalyst particles, causing them to generate their own heat through resistive heating. This self-heating mechanism eliminates the need for external heat sources and improves energy efficiency by heating the catalyst directly where it is needed.
2Speed
If conventional heating methods are used, then heating can be achieved, but heating speed is slow and temperature control is imprecise
Solution Approach 1:
The induction heating system uses electromagnetic fields to directly induce eddy currents in the catalyst bed, enabling rapid heating. This electromagnetic heating method is significantly faster than conventional gas fired heating because it transfers energy directly to the catalyst particles through electromagnetic induction rather than through gradual heat conduction from external burners, thereby reducing startup time and improving heating speed.
3Loss of energy
If an induction coil is placed outside the reactor, then heating can be applied, but energy is lost through the reactor walls and magnetic field penetration is inefficient
Solution Approach 1:
The induction coil is nested within the reactor structure, specifically positioned inside the reactor vessel surrounding the catalyst bed. This nested configuration ensures that the magnetic field is generated directly within the reactor where the catalyst is located, maximizing energy efficiency by preventing magnetic field leakage outside the reactor and eliminating energy losses through reactor walls. The coil is effectively embedded in the reactor system to create a contained electromagnetic heating zone.
4Speed
If high-frequency alternating current is used in the induction coil, then rapid heating is achieved, but energy losses occur in the coil resistance
Solution Approach 1:
The system is designed so that the catalyst bed itself becomes the primary heating element through eddy current induction. While some ohmic losses occur in the induction coil, the majority of the electromagnetic energy is efficiently transferred to the catalyst particles, which generate heat through their own electrical resistance. This self-heating mechanism minimizes overall energy losses because the heat is generated directly in the catalyst material rather than being lost in external heating components.
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 method enables rapid and energy-efficient heating of the catalyst, reducing energy losses and allowing for high-temperature, high-pressure reactions with precise temperature control, ensuring efficient ammonia synthesis.
Implementation Method 1
induction heating is used instead of the traditional use of a gas fired heater... inductive heating is the process of heating an electrically conducting object (usually a metal) by magnetic induction, through heat generated in the object by eddy currents (also called Foucault currents, which are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction)
Implementation Method 2
The rapidly alternating magnetic field penetrates the object, whereby electric currents inside the conductor called eddy currents are generated. The eddy currents flowing through the resistance of the material will heat it by Joule heating.
Implementation Method 3
The eddy currents flowing through the resistance of the material will heat it by Joule heating.
Implementation Method 4
provided that the pressure shell is based on iron with a low hysteresis, or alternatively that the pressure shell is coated on the inside with such iron type, the magnetic field generated by the coil will not be able to penetrate out of the reactor... heat may alternatively or additionally be generated by magnetic hysteresis losses.
Data Source
AI summary
In a novel method for start-up heating of a converting re-actor in an ammonia synthesis plant, the conventional use of a gas fired heater is replaced by inductive heating. The inductive heating is obtained using an alternating high frequency current, which is passed through an inductive coil located inside the reactor, especially mounted inside a pressure shell. The method makes it possible to run reactions at high temperatures and high pressures in a very efficient way.