Delayed Coke Drum Quench System Ejector Design
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Solution Overview
Problem
Conventional delayed coking quench systems experience significant atmospheric emissions of hydrocarbon vapors due to the venting of hydrocarbon-rich steam plumes and coke fines, which can lead to environmental issues and operational challenges such as noise and equipment plugging, especially when the pressure in the inactive coke drum is maintained at 14 kPag (2 psig) before venting.
Innovation Solution
The system reduces atmospheric emissions by flashing off hydrocarbon vapors in an overflow drum where the pressure is reduced to 0 Pag (0 psig) using an overhead ejector, and any remaining vapors are further flashed off in an overflow tank with the pressure reduced to 0 Pag (0 psig by an overflow ejector, ensuring minimal emissions when vented to the atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pressure in the inactive coke drum is maintained at 14 kPag (2 psig) before venting, then the steam plume can be controlled, but hydrocarbon vapor emissions increase and environmental compliance deteriorates
Solution Approach 1:
The system divides the pressure reduction process into two stages: first reducing pressure from 14 kPag to 0 kPag in the inactive coke drum, then managing the resulting vapor discharge through a dedicated ejector system. This segmentation allows controlled pressure reduction while capturing and treating hydrocarbon vapors, thereby reducing emissions compared to single-stage venting.
Solution Approach 2:
An overhead ejector is introduced as an intermediary device between the pressure reduction process and atmospheric venting. The ejector captures hydrocarbon-rich vapors generated during pressure reduction and transports them to a blowdown condenser for treatment, preventing direct release to atmosphere and reducing harmful emissions.
2Ease of operation
If hydrocarbon-rich steam plumes are vented to atmosphere, then the coke drum can be isolated, but atmospheric emissions of hydrocarbon vapors increase
Solution Approach 1:
The ejector system serves as an intermediary that captures hydrocarbon vapors during the isolation process. Instead of direct atmospheric venting, vapors are routed through the ejector to the blowdown condenser, enabling coke drum isolation while preventing harmful emissions.
Solution Approach 2:
The system converts the harmful hydrocarbon vapor plume into a manageable stream by using the ejector to direct vapors to the blowdown condenser. The previously harmful atmospheric emission becomes a controlled condensation process that recovers hydrocarbons, transforming an environmental problem into a resource recovery opportunity.
3Object-generated harmful factors
If pressure is reduced to 0 Pag (0 psig) using an overhead ejector, then hydrocarbon vapors are flashed off and emissions are reduced, but device complexity increases
Solution Approach 1:
The overhead ejector is designed to utilize the vapor pressure differential and steam energy from the coke drum itself to drive the pressure reduction and vapor transport process. This self-service approach reduces the need for external power sources or complex control systems, thereby limiting the increase in device complexity while achieving effective vapor management.
4Productivity
If steam and hydrocarbons are condensed in the blowdown condenser, then vapor recovery is maximized, but equipment plugging by coke fines increases
Solution Approach 1:
The condensation and separation process is segmented into distinct zones within the blowdown condenser: a vapor condensation zone, a liquid discharge zone, and a coke fines removal zone. This segmentation allows efficient vapor recovery while separating coke fines from the condensate stream, preventing equipment plugging.
Solution Approach 2:
The system extracts and removes coke fines from the condensate stream through dedicated removal mechanisms in the blowdown condenser. By separating and removing these solid particles before the condensate is discharged or recycled, the system prevents plugging of downstream equipment while maintaining high vapor recovery efficiency.
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 minimizes hydrocarbon vapor emissions by maximizing vapor recovery and maintaining a closed system, reducing the risk of steam plumes and coke fines release, thus enhancing environmental compliance and operational efficiency.
Implementation Method 1
the pressure is reduced by an overhead ejector to 0 Pag (0 psig)
Implementation Method 2
flashing off hydrocarbon vapors in an overflow drum wherein the pressure is reduced by an overhead ejector to 0 Pag (0 psig)
Implementation Method 3
any remaining hydrocarbon vapors are flashed off through the overflow ejector to the blowdown condenser
Implementation Method 4
any remaining hydrocarbon vapors are flashed off through the overflow ejector to the blowdown condenser wherein the pressure is reduced to 0 Pag (0 psig)
Implementation Method 5
any remaining hydrocarbon vapors are flashed off through the overflow ejector to the blowdown condenser
Data Source
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AI summary
Systems and methods for reducing atmospheric emission of hydrocarbon vapors by flashing off hydrocarbon vapors in an overflow drum where the pressure is ultimately reduced to 0 psig and then flashing off any remaining hydrocarbon vapors in an overflow tank wherein the pressure in the overflow tank is reduced to 0 psig by an overflow ejector.