Vapor-Liquid Ejector Supercharging with Flash Vaporization for Waste Heat Recovery
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Solution Overview
Problem
The direct use of high-pressure steam from steam injection boilers for heavy oil thermal recovery in seawater desalination or sewage treatment processes results in significant energy waste and reduced water production economy.
Innovation Solution
A vapor source system utilizing vapor-liquid ejector supercharging combined with flash vaporization technology, where high-pressure steam drives a vapor-liquid ejector to increase the pressure and temperature of low-pressure water, which is then sent to an intermediate heat exchanger and finally to a flash vaporization tank to generate low-pressure steam, thereby improving thermal economy and utilizing waste heat from boiler flue gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-pressure steam is used directly or with decompressor for seawater desalination or sewage treatment device, then the steam can be supplied to the device, but significant energy waste occurs and water production economy reduces
Solution Approach 1:
The system segments the steam utilization process into multiple stages: high-pressure steam first drives the vapor-liquid ejector to generate vacuum, then heats water in the flash vaporization tank to produce low-pressure steam, which is subsequently used for seawater desalination. This segmentation allows each component to operate at optimal pressure levels, preventing energy waste while maintaining productivity.
Solution Approach 2:
The system changes the pressure parameter of steam through a series of transformations: high-pressure steam (10-21 MPa) from the boiler is converted to drive the ejector, then the water is heated to generate low-pressure steam (0.3-1.0 MPa) in the flash vaporization tank. This parameter change enables efficient energy transfer and prevents direct use of high-pressure steam causing energy waste.
2Loss of energy
If waste heat from flue gas of small-sized steam boiler is used for thermal seawater desalination or sewage treatment device, then feed water quality improves and thermal efficiency increases, but requires additional heat exchange equipment
Solution Approach 1:
The system merges the waste heat recovery function with the existing flash vaporization tank by integrating a heat exchanger that utilizes flue gas heat to preheat the water before it enters the flash vaporization tank. This combining approach recovers waste heat while maintaining the simplicity of the overall system structure.
Solution Approach 2:
The system introduces an intermediary heat exchanger that mediates between the flue gas waste heat and the water to be vaporized. This intermediary component enables efficient heat transfer from the flue gas to the water, improving energy utilization efficiency without requiring direct contact between flue gas and water, thus maintaining system simplicity.
3Loss of energy
If high-pressure steam is used to drive vapor-liquid ejector and flash vaporization, then thermal economy improves, but system complexity increases
Solution Approach 1:
The system employs self-service principles where the high-pressure steam automatically drives the vapor-liquid ejector to generate vacuum and heat water without requiring external mechanical drivers or complex control systems. The flash vaporization process occurs automatically when heated water enters the tank, eliminating the need for additional mechanical equipment and reducing system complexity while improving thermal economy.
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 system reduces energy loss and improves water production economy by generating multiple low-pressure steam through flash vaporization, while also enhancing energy utilization efficiency by utilizing waste heat from boiler flue gas, leading to improved thermal efficiency and reduced operational costs.
Implementation Method 1
the high-pressure steam is used to drive the vapor-liquid ejector, while the low-pressure water in the flash vaporization tank is sucked to increase pressure and temperature
Implementation Method 2
a supersonic jet is generated at the outlet of the primary nozzle
Implementation Method 3
vacuum is formed in the suction chamber
Implementation Method 4
The intermediate heat exchanger of the vapor source system may use the flue gas of the boiler as a heat source, and realize the waste heat utilization of the boiler flue gas
Implementation Method 5
the mixed fluid is sent into the intermediate heat exchanger to increase temperature to saturated or nearly saturated fluid
Implementation Method 6
multiple low-pressure steam is flashed in the flash vaporization tank to improve the thermal economy of low-pressure steam process
Implementation Method 7
then sent into the flash vaporization tank to flash, and low-pressure saturated steam is generated
Data Source
AI summary
A vapor source system based on vapor-liquid ejector supercharging combined with flash vaporization technology belongs to the technical fields of waste heat utilization and steam generation. The system comprises a vapor-liquid ejector, a flash vaporization tank and a intermediate heat exchanger, wherein the vapor-liquid ejector uses high-pressure steam to raise temperature and pressure of low-pressure water absorbed from the flash vaporization tank; the pressure-increased water is flashed into low-pressure saturated steam after entering the flash vaporization tank; the saturated water which is not flashed is collected at the bottom of the flash vaporization tank. The system generates multiple low-pressure flash vaporization saturated steam with a small portion of high-pressure steam, and realizes the recovery and utilization of waste heat such as flue gas of boiler, improves the economy of thermal process, and provides a flexible and adjustable vapor source for heavy oil thermal recovery, seawater desalination or sewage treatment equipment.