Steam Reforming Heat Exchangers for Dew-Point Catalyst Protection
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Solution Overview
Problem
Existing steam reforming processes face challenges in preventing moisture formation in the hydrocarbon/steam mixture fed to reforming operations, which can deactivate the catalyst, and often require superheated steam or fired heaters, leading to CO2 emissions.
Innovation Solution
A process utilizing first and second heat exchangers to pre-heat the hydrocarbon feed using crude syngas effluent, eliminating the need for superheated steam and fired heaters, and ensuring the mixture remains above its dew point to avoid moisture condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a fired heater is used to pre-heat the hydrocarbon/steam mixture, then the mixture temperature is increased above dew point, but CO2 emissions increase due to hydrocarbon fuel combustion
Solution Approach 1:
The invention converts the harmful waste heat from crude syngas into a beneficial heating source for pre-heating the hydrocarbon feedstock. The crude syngas stream, which would otherwise be cooled and potentially vented, is used to provide the necessary thermal energy to maintain the mixture above dew point, thereby eliminating CO2 emissions from fired heaters while achieving the same temperature control objective
Solution Approach 2:
The reforming process itself provides the heat needed for its own feed preparation. The crude syngas generated during reforming is recirculated through heat exchangers to pre-heat the incoming hydrocarbon feedstock, creating a self-sufficient thermal system that eliminates external fuel requirements and associated CO2 emissions
2Reliability
If superheated steam is injected to prevent moisture formation, then the mixture remains above dew point, but the risk of moisture formation persists if temperature or pressure is too low
Solution Approach 1:
The system uses the actual temperature and pressure conditions of the crude syngas stream to dynamically control the pre-heating process. By continuously monitoring the state of the hydrocarbon/steam mixture and adjusting the heat exchange accordingly, the system ensures the mixture remains above dew point without requiring complex superheated steam injection systems, achieving reliable moisture prevention through process feedback
3Loss of energy
If the hydrocarbon/steam mixture is cooled below dew point, then energy consumption is reduced, but moisture condensation occurs and deactivates the catalyst
Solution Approach 1:
The invention applies preliminary heating action to the hydrocarbon feedstock using crude syngas before the mixture enters the reforming catalyst. By pre-heating the feed to ensure it remains above dew point throughout the process, the system prevents moisture condensation and catalyst deactivation while minimizing energy consumption, avoiding the need for excessive heating that would increase energy loss
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 prevents catalyst deactivation by maintaining the hydrocarbon/steam mixture above its dew point, reducing CO2 emissions, and enhancing process efficiency without requiring decarbonized hydrogen as fuel.
Implementation Method 1
pre-heating a first hydrocarbon feedstock stream in a first heat exchanger by heat exchange with a partially cooled crude syngas stream
Implementation Method 2
pre-heating the second hydrocarbon feedstock stream in a second heat exchanger by heat exchange with a crude reformed syngas stream
Implementation Method 3
carrying out steam reforming on the pre-heated second hydrocarbon feedstock stream in an autothermal reformer using a reforming catalyst
Implementation Method 4
carrying out steam reforming on the pre-heated second hydrocarbon feedstock stream in an autothermal reformer
Data Source
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AI summary
The specification describes a steam reforming process in which a hydrocarbon feed is preheated in a first heat exchanger, steam is injected, and the resulting stream is then preheated in a second heat exchanger. The resulting stream is fed to an autothermal reformer, or a gas-heated reformer followed by an autothermal reformer. Effluent from the reforming operations is fed sequentially to the second heat exchanger then the first heat exchanger in order to pre-heat the hydrocarbon and steam mixture. The specification also describes a chemical plant arranged to carry out the steam reforming process, and a method of retrofitting a chemical plant which initially comprises a fired reformer, by removing the fired reformer and replacing it with an autothermal reformer or an autothermal reformer and gas-heated reformer.