Fog Computing Control for Delayed Coker Pressure and Yield
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Solution Overview
Problem
In delayed coker units, the operating column pressure of the coke drum is limited by the net positive suction head (NPSH) requirement for the fractionator bottom pump, preventing a reduction in coker fractionator pressure, which in turn limits the liquid product yield.
Innovation Solution
Fog computing is applied to dynamically control the coker fractionator pressure by utilizing a pump characteristics curve and real-time sensed parameters to minimize the gap between NPSHa and NPSHr, allowing for reduced coke drum pressure and increased liquid distillate yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the coker fractionator pressure is reduced to increase liquid distillate yields, then the liquid product yield increases, but the NPSH margin for the fractionator bottom pump becomes insufficient
Solution Approach 1:
The patent implements dynamic control of the fractionator bottom pump speed to adapt to varying process conditions. By using variable speed drives and real-time optimization algorithms, the system dynamically adjusts pump operating parameters to maintain adequate NPSH margin while operating at reduced fractionator pressures, thereby enabling increased liquid distillate yields without compromising pump reliability
Solution Approach 2:
The system changes multiple operating parameters simultaneously including pump speed, impeller diameter, and casing configuration to optimize the NPSH characteristics. By modifying these parameters dynamically based on real-time process conditions, the system can operate at lower fractionator pressures while maintaining sufficient NPSH margin for reliable pump operation
2Power
If the fractionator bottom pump operates at high temperature and high discharge pressure to meet process requirements, then the pump can deliver required flow, but the NPSH requirement increases creating a larger gap between NPSHr and NPSHa
Solution Approach 1:
The patent employs dynamic speed control and real-time optimization to adjust pump operating conditions based on actual process demands. This allows the system to operate at lower speeds and temperatures when possible, reducing the NPSH requirement while still meeting the required discharge pressure and flow rate, thereby maintaining adequate NPSH margin
Solution Approach 2:
The system modifies multiple operating parameters including temperature, pressure, and speed to optimize pump performance. By dynamically adjusting these parameters and using alternative configurations such as different impeller designs or casing types, the system can reduce the NPSH requirement while maintaining the necessary power output and discharge pressure
Data Source
AI summary
A method of operating a refinery including at least one coke drum coupled to a coker fractionator. A pump characteristics curve is provided for a fractionator bottom pump coupled to the coker fractionator comprising a net positive suction head required (NPSHr) curve as a function of a pump flow rate. Fog computing utilizes the pump characteristics curve along with at least one sensed input parameter including a real-time value for the pump flow rate to control the fractionator bottom pump to dynamically control a column pressure (Pc) in the coker fractionator. A reduction in Pc is obtained that reduces an available NPSH (NPSHa) which lessens a difference between the NPSHa and the NPSHr.