Multi-Stage Flash Steam Recovery With Low-Pressure Compression

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Solution Overview

Problem

Existing heat recovery systems are limited in the amount of high-temperature and high-pressure steam they can produce due to lower temperatures and pressures in later stages of flash tanks, limiting their efficiency.

Innovation Solution

A heat recovery utilization system that includes a circulation line with a first heat exchanger, high-pressure and low-pressure flash tanks, steam merging lines, and low-pressure stage compressors to enhance steam pressure and temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If liquid heated by heat exchange with heat source medium is sequentially guided to multiple flash tanks, then heat is efficiently recovered, but the amount of high-temperature and high-pressure steam is limited

Engineering Contradiction:
Improveheat recovery efficiencyVSAvoidamount of high-temperature and high-pressure steam
Core Design Contradiction:
Loss of energyVSQuantity of substance

Solution Approach 1:

The system divides the flash tank into high-pressure and low-pressure stages, with the high-pressure flash tank generating high-temperature steam and the low-pressure flash tank generating low-pressure steam. This segmentation allows different pressure levels to be optimized independently, resolving the contradiction between heat recovery efficiency and steam quantity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the pressure parameter across different stages of the flash tank system. By maintaining high pressure in the first stage and reducing pressure in subsequent stages, the system enables both high-temperature steam generation and efficient heat recovery, thereby increasing the total amount of usable steam.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If low-pressure flash tank steam is merged with high-pressure flash tank steam, then the amount of steam is increased, but compressor power is required to pressurize low-pressure steam

Engineering Contradiction:
Improveamount of steamVSAvoidcompressor power
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The invention applies partial pressurization only to the low-pressure steam from the low-pressure flash tank, rather than pressurizing all steam. This partial action approach increases the total usable steam quantity while minimizing the energy required for compression, as only a portion of the steam requires pressurization.

Inventive Principle:
Principle #16Partial or excessive 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 enables the generation and use of a larger amount of high-temperature and high-pressure steam while efficiently recovering heat, utilizing a smaller compressor power.

Implementation Method 1

a first heat exchanger for heating the first medium in a liquid state flowing through the circulation line through heat exchange with a heat source medium

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a high-pressure flash tank provided in the circulation line and to which the first medium in the liquid state heated by the first heat exchanger is guided

Methodology Applied
Scientific EffectFlash evaporation: Flash Evaporation

Implementation Method 3

at least one low-pressure stage compressor for pressurizing the steam of the first medium from the at least one low-pressure flash tank

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP4707673A1Heat recovery utilization system
Publication Date: 2026.03.11 MITSUBISHI HEAVY IND LTD
  • EP4707673A1 patent drawingFigure 1
  • EP4707673A1 patent drawingFigure 2
  • EP4707673A1 patent drawingFigure 3

AI summary

This heat recovery utilization system comprises: a circulation line through which a first medium circulates; a first heat exchanger for heating the first medium in a liquid state flowing through the circulation line by means of heat exchange with a heat source medium; a high-pressure flash tank which is provided to the circulation line and through which the first medium in the liquid state heated by the first heat exchanger is guided; at least one low-pressure flash tank which is provided to the circulation line and through which the first medium in the liquid state is guided from the high-pressure flash tank; a steam supply line for guiding the steam of the first medium generated in the high-pressure flash tank to a heat utilization facility; a steam merging line for merging the steam of the first medium generated in the at least one low-pressure flash tank into the steam of the first medium from the high-pressure flash tank flowing through the steam supply line; and at least one low-pressure stage compressor provided to the steam merging line and raising the pressure of the steam of the first medium from the at least one low-pressure flash tank.