Heat-Integrated Fired Heaters Using Superheated Vapor Preheating
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Solution Overview
Problem
The use of fired heaters in hydrocarbon processes leads to high CO2 emissions and potential issues like coking, thermal cracking, and fouling, limiting the adoption of electric heating for liquid and two-phase hydrocarbon streams.
Innovation Solution
Integrate electric heaters or alternative heat sources with fired heaters to reduce fired heater duty, using heat integration schemes that preheat vapor streams to superheat them, allowing them to act as heat sources for liquid hydrocarbon streams, thereby reducing fired heater size and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fired heaters are used to heat liquid and two-phase hydrocarbon streams, then heating effectiveness is achieved, but CO2 emissions increase and coking/thermal cracking/fouling occurs
Solution Approach 1:
The heating process is divided into multiple stages: first, vapor streams are separated from liquid hydrocarbon streams; second, the vapor streams are heated in electric heaters to generate process heat; third, the heated vapor streams heat the liquid hydrocarbon streams in heat exchangers; fourth, any remaining heating requirements are met by fired heaters. This segmentation allows the harmful fired heater to be used only when necessary, reducing CO2 emissions and coking while maintaining heating effectiveness.
Solution Approach 2:
Heated vapor streams act as an intermediary heat transfer medium. These vapor streams are first heated by electric heaters, then used to heat liquid hydrocarbon streams through heat exchangers. This intermediary approach transfers thermal energy without direct combustion contact with the hydrocarbon stream, eliminating coking and thermal cracking issues while reducing fired heater duty and CO2 emissions.
2Temperature
If fired heaters are used for heating, then process heating objectives are met, but heater size and fuel consumption increase
Solution Approach 1:
The process uses its own vapor streams as heat sources after heating them in electric heaters. The heated vapor streams circulate through heat exchangers to provide process heat, essentially serving the heating needs of the process itself. This self-service approach reduces external fuel consumption and fired heater size while meeting all process heating objectives.
3Object-generated harmful factors
If electric heaters are used directly on liquid hydrocarbon streams, then CO2 emissions are reduced, but coking and thermal cracking occur
Solution Approach 1:
Vapor streams serve as an intermediary between electric heaters and liquid hydrocarbon streams. The electric heaters heat the vapor streams, which then transfer heat to the liquid hydrocarbon streams through heat exchangers. This intermediary arrangement allows electric heating benefits (reduced CO2 emissions) to be achieved without exposing liquid hydrocarbons directly to high temperatures that cause coking and thermal cracking.
Solution Approach 2:
The process utilizes phase transitions of hydrocarbon components between vapor and liquid phases. Vapor streams are separated, heated, and used to condense on liquid hydrocarbon streams in heat exchangers, transferring heat during the phase change process. This phase transition mechanism enables efficient heat transfer at controlled temperatures that prevent coking and thermal cracking.
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 decreases fuel consumption, lowers CO2 emissions, reduces heater footprint, and lowers operating costs while enabling the transition to greener heating methods.
Implementation Method 1
The heated vapor stream exchanges heat with an incoming liquid hydrocarbon stream from a column (a column bottom stream, a column side draw stream, or both), increasing the fired heater inlet temperature and resulting in a reduction in the fired heater duty.
Implementation Method 2
All or a portion of a vapor stream from a two phase separator is heated by an electric heater or other heater source (or multiple electric heaters or other sources in series and/or in parallel) to a requisite temperature
Data Source
AI summary
Processes integrating electric heaters or other heating sources for heating of liquid and two phase hydrocarbon streams resulting in reduced CO2 emissions are described. The processes shift a portion of the fired heater duty to an electric heater or other heat source. All or a portion of a vapor stream from a two phase separator is heated or superheated by an electric heater or other heat source to provide sufficient temperature that the heated/superheated vapor stream acts as a heat source to a bottom or side draw stream from a column. The preheated bottom or side draw stream is sent to the fired heater.