Desalter Effluent Cooling Via Heat Integration for Wash Water Reuse
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Solution Overview
Problem
The recycling of desalter effluent water in gas oil separation plants (GOSPs) is challenging due to temperature limitations of polymer-based membranes, high operational costs of mechanical vapor compressor technology, and inefficiencies in existing cooling methods like cooling towers, which lead to water loss and ion concentration increases.
Innovation Solution
A heat integration concept using multiple heat exchangers to cool desalter effluent water before desalination, employing permeate and brine reject streams as cooling media, and optionally using groundwater or alternative cooling systems to achieve temperature reduction and heat recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling towers are used to cool desalter effluent water, then the temperature reduction is achieved, but water loss increases and ion concentration increases
Solution Approach 1:
The patent introduces an intermediary heat exchanger system that transfers heat from the hot effluent water to a cooling medium (such as fresh water or recycled water) without direct mixing. This allows temperature reduction while preventing water loss and ion concentration increases that occur in cooling towers through evaporation and drift.
Solution Approach 2:
The patent replaces the mechanical evaporation-based cooling tower system with a heat exchanger-based thermal exchange system. This substitution eliminates the need for water evaporation to achieve cooling, thereby preventing water loss and ion concentration increases while still achieving the required temperature reduction for desalination.
2Temperature
If cooling towers are used to cool desalter effluent water, then the temperature reduction is achieved, but ion concentration increases
Solution Approach 1:
The heat exchanger acts as an intermediary that transfers thermal energy without causing water loss or ion concentration increases. The cooling medium absorbs heat from the effluent water through the heat exchanger walls, achieving temperature reduction while keeping the effluent water composition unchanged.
Solution Approach 2:
The patent replaces the evaporation-based cooling mechanism with a thermal conduction-based heat exchange mechanism. This substitution prevents ion concentration increases by eliminating water evaporation, while still achieving the necessary temperature reduction for effective desalination.
3Quantity of substance
If mechanical vapor compressor technology is used for desalination, then high TDS water can be treated, but operational costs increase
Solution Approach 1:
The patent changes the temperature parameter of the effluent water from high temperature to a lower temperature suitable for membrane desalination. This parameter change enables the use of more energy-efficient membrane-based desalination technologies instead of expensive mechanical vapor compressor systems, while still achieving effective TDS removal.
Solution Approach 2:
The patent performs preliminary cooling of the hot effluent water before it enters the desalination process. This preliminary action prepares the water for more efficient desalination using membrane technologies, avoiding the need for high-cost mechanical vapor compressor systems that would be required for hot water treatment.
4Quantity of substance
If polymer-based membranes are used for desalination, then desalination can be achieved, but temperature limitations apply
Solution Approach 1:
The patent performs preliminary cooling of the effluent water before it enters the membrane desalination unit. This preliminary cooling action ensures the water temperature is within the operational limits of polymer-based membranes, enabling effective desalination while maintaining membrane performance and longevity.
Solution Approach 2:
The patent changes the temperature parameter of the feed water from high temperature to a lower temperature suitable for polymer membrane operation. This parameter change enables the use of cost-effective polymer-based membranes while maintaining their operational limitations in mind, achieving desalination without requiring high-temperature tolerant materials.
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 method effectively reduces the temperature of desalter effluent to suitable levels for desalination, minimizes water loss, and decreases the carbon footprint and energy consumption, enabling continuous reuse of treated water as wash water.
Implementation Method 1
The desalter effluent water and the permeate water stream flow through a heat exchanger in a series of heat exchangers, thereby cooling the desalter effluent water
Implementation Method 2
The brine reject stream and the desalter effluent water flow through a heat exchanger in a series of heat exchangers, thereby heating the brine reject stream
Implementation Method 3
The desalter effluent water is cooled to a temperature below 35°C in a cooling system before flowing through the desalination unit
Data Source
AI summary
This disclosure relates to the method and system of cooling a pre-treated produced water stream in a gas oil separation plant (GOSP), using a heat integration concept. The pre-treated produced water stream is cooled by multiple heat exchangers arranged in series or in parallel. The cooled pre-treated produced water stream is desalinated to produce a permeate stream and a brine reject stream. The permeate and brine reject streams are used as the cooling media for the heat exchangers. This operates in a cyclic way, such that the permeate stream from the desalination unit heats up while cooling the pre-treated produced water. The heated permeate stream is used as a wash water stream for a desalter unit in the GOSP. This method reduces the reliance on an external fresh water source for the wash water stream and provides an energy efficient way of cooling the pre-treated produced water stream.