Subsea Cooler Recirculation and Bypass Control

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Solution Overview

Problem

Existing subsea cooler systems lack flexibility in accommodating varying flow rates and temperatures of hydrocarbon flows, which can lead to hydrate formation and blockages, and require robust and low-maintenance compressors due to harsh subsea conditions.

Innovation Solution

A cooler system with a recirculation loop and bypass circuit, allowing for adjustable cooling by directing fluid flow through multiple coolers in series and parallel connections, and incorporating MEG-injection to prevent hydrate formation, with flow control devices and adjustable perforated plates for natural convection and temperature management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If cooling the hydrocarbon flow is increased to improve compressor efficiency, then compressor efficiency is improved, but hydrate formation risk increases

Engineering Contradiction:
Improvecompressor efficiencyVSAvoidhydrate formation
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The system employs dynamic flow control through multiple valves (first, second, third, and fourth valves) that can adjust the distribution of hydrocarbon flow between parallel cooling paths and recirculation loops. This dynamic adjustment allows the system to optimize cooling efficiency while preventing hydrate formation by adapting to varying flow rates and temperature conditions throughout the well's lifetime.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters by controlling flow rates through adjustable valves and adjusting the degree of cooling in different parallel paths. By varying these parameters, the system can maintain optimal compressor efficiency while staying above the hydrate formation temperature threshold, thus resolving the contradiction between cooling efficiency and hydrate prevention.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the cooler system is made more complex to accommodate varying flow rates and temperatures, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improveflexibility with regards to flow rate and temperatureVSAvoidcooler system structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cooling system is divided into multiple independent parallel cooling paths, each with its own flow control valve. This segmentation allows each path to be independently controlled and adjusted according to specific cooling requirements, providing high adaptability to varying flow rates and temperatures without requiring a completely redesigned complex system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system incorporates a recirculation loop that can serve multiple functions: it can recirculate cooling medium to enhance cooling capacity when needed, or be bypassed when sufficient cooling is achieved. This multi-functional design allows the same structural elements to serve different purposes under different operating conditions, increasing adaptability without proportionally increasing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Temperature

If cooling is applied continuously to maintain temperature control, then temperature stability is improved, but energy consumption increases

Engineering Contradiction:
Improvetemperature stability of cooled flowVSAvoidcooling energy consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The system incorporates temperature sensors that continuously monitor the temperature of the cooled flow and provide feedback to the control system. Based on this feedback, the flow control valves automatically adjust the cooling medium flow rate to maintain the temperature within the desired range, avoiding excessive cooling and reducing energy consumption while ensuring temperature stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Instead of continuous full-capacity cooling, the system uses periodic adjustment of cooling intensity through the controllable valves. The cooling intensity is modulated based on actual temperature needs, applying cooling only when and where required, thus maintaining temperature stability while minimizing energy consumption.

Inventive Principle:
Principle #19Periodic action

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

The system provides flexible cooling capabilities, preventing hydrate formation and maintaining a predetermined temperature range, ensuring efficient compressor operation and minimizing maintenance needs across the lifetime of a well flow.

Implementation Method 1

each of said coolers may be provided with a recirculation loop for recirculating at least an amount of the flow if the temperature is above a threshold value

Methodology Applied
Scientific EffectRecirculation:

Implementation Method 2

it might be arranged a bypass circuit over said first cooler and/or second cooler, which bypass circuit allows at least fractions of the flow, alternatively the whole flow, to bypass the cooler

Methodology Applied
Scientific EffectBypass flow:

Implementation Method 3

The system may be provided with means for MEG-injection to prevent the formation of hydrates

Methodology Applied
Scientific EffectHydrate prevention: Hydrates

Implementation Method 4

A cooler system with a recirculation loop and bypass circuit, allowing for adjustable cooling by directing fluid flow through multiple coolers in series and parallel connections

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentEP2877685B1Active control of subsea coolers
Publication Date: 2019.05.22 FMC KONGSBERG SUBSEA AS
  • EP2877685B1 patent drawingFigure 1A~1F
  • EP2877685B1 patent drawingFigure 2A~2K
  • EP2877685B1 patent drawingFigure 3A~3B

AI summary

A cooler system having an inlet (A) and an outlet (B), the cooler system comprising; at least a first cooler (20, 21, 22, 23, 24) and a second cooler (20, 21, 22, 23, 24), wherein the first cooler (20, 21, 22, 23, 24) and second cooler (20, 21, 22, 23, 24) are arranged in a series connection, the cooler system further comprises at least a third cooler (20, 21, 22, 23, 24) which is arranged in parallel connection with the first cooler (20, 21, 22, 23, 24) and second cooler (20, 21, 22, 23, 24), and the cooler system comprises at least one flow control device for directing flow through at least one cooler(20, 21, 22, 23, 24)wherein at least one of the coolers (20, 21, 22, 23, 24) comprises a bypass circuit and/ or recirculation loop (35).