Multi-Energy Energy Tower for Gas Engine Waste Heat Recovery
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Solution Overview
Problem
Existing waste heat recovery methods for gas engines are inefficient in utilizing the varying energy quality of waste heat sources, as they can only effectively recycle heat within a certain energy quality, failing to fully utilize the waste heat due to large temperature differences and varying heat amounts.
Innovation Solution
A multi-energy-form output energy tower system that combines steam Rankine cycle, organic Rankine cycle, and lithium bromide refrigerator systems with multiple heat exchangers to stepwise recover waste heat from a gas engine, allowing for the utilization of high, medium, and low-grade energy for electricity generation, heating, and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single waste heat recovering method is used, then the system is simple and easy to operate, but the waste heat cannot be fully utilized due to limited energy quality range
Solution Approach 1:
The waste heat recovery system is segmented into multiple independent modules: a steam Rankine cycle system for high-temperature exhaust, an organic Rankine cycle system for medium-temperature heat sources, a lithium bromide absorption refrigerator for cooling, and a hot water heat exchanger. Each module operates independently within its optimal temperature range, allowing the system to handle varying energy qualities without increasing overall complexity
Solution Approach 2:
The energy tower integrates multiple functions into a single structure: power generation through two Rankine cycles, cooling through absorption refrigerator, and heating through hot water heat exchanger. This multi-functional design allows one system to address diverse energy quality requirements simultaneously, improving versatility without proportionally increasing device complexity
2Loss of energy
If multiple waste heat recovering methods are combined, then the waste heat utilization efficiency is improved, but the system complexity increases
Solution Approach 1:
The system divides waste heat recovery into distinct temperature zones with dedicated methods: steam Rankine cycle for high-temperature exhaust (>400°C), organic Rankine cycle for medium-temperature sources (80-250°C), and heat exchangers for low-temperature waste heat. This segmentation maximizes recovery efficiency at each temperature level while keeping individual subsystems relatively simple
Solution Approach 2:
The energy tower employs a nested structure where the steam Rankine cycle system is positioned to handle high-temperature exhaust first, the organic Rankine cycle system processes medium-temperature heat sources, and the hot water heat exchanger recovers low-temperature waste heat. This nested arrangement allows systematic energy recovery from high to low temperatures, improving overall efficiency while organizing complexity in a structured manner
3Temperature
If waste heat is recovered from high temperature sources, then the energy quality is high, but the temperature difference is large causing significant energy loss
Solution Approach 1:
The system segments the temperature recovery process into multiple stages: the steam Rankine cycle captures high-temperature energy, the organic Rankine cycle recovers medium-temperature heat, and the hot water heat exchanger utilizes low-temperature waste heat. This multi-stage segmentation reduces the temperature difference at each stage, minimizing exergy loss and improving overall energy utilization efficiency
Solution Approach 2:
The system changes the operating parameters of different recovery methods to match the temperature level of waste heat sources. The steam Rankine cycle operates at high temperature and pressure for exhaust heat, while the organic Rankine cycle uses lower temperature thresholds for jacket water and charge air. This parameter optimization ensures efficient heat transfer at each temperature level, reducing energy loss
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 maximizes waste heat recycling by providing different energy qualities and functions, significantly improving energy utilization efficiency and achieving energy savings and emission reduction.
Implementation Method 1
a steam Rankine cycle system which is capable of heat exchanging with the high temperature exhaust exhausted from the IC engine to make the steam turbine do expansion work
Implementation Method 2
an organic Rankine cycle system which is respectively heat exchanged with high temperature exhaust, jacket water and charge air which are exhausted from the IC engine, and with condensation heat in the steam Rankine cycle system to do expansion work
Implementation Method 3
a Lithium bromide refrigerator which uses part of jacket water discharged from the IC engine
Implementation Method 4
a waste heat boiler, which can heat the water flowing through the internal to high temperature and high pressure gas
Implementation Method 5
a steam turbine for receiving the high temperature and high pressure gas exhausted from the waste heat boiler via pipelines, which is used for doing expansion work
Implementation Method 6
a first condenser for receiving the gas exhausted from steam turbine via pipelines, which is used for cooling and condensing the gas
Implementation Method 7
a pump connected with a condensed water outlet of the first condenser via pipelines, which is used for pressurizing the water
Implementation Method 8
an expansion engine, which performs expansion work via high temperature gaseous working medium and then exhausts low temperature gaseous working medium
Implementation Method 9
a second condenser, which is used for cooling the organic working medium
Implementation Method 10
a working medium pump arranged on the pipelines
Implementation Method 11
a first branch of the low temperature liquid working medium goes through an exhaust preheater arranged at the exhausting end of the jacket water heat exchanger for heating
Implementation Method 12
a second branch of the low temperature liquid working medium goes through a charge air preheater for heating by the charge air of the IC engine
Implementation Method 13
a third branch of the low temperature liquid working medium goes through a jacket water preheater for heating by the jacket water exhausted from the second branch of the jacket water of the IC engine
Implementation Method 14
a hot water heat exchanger connected at the end of the high temperature exhaust for heating domestic water
Data Source
AI summary
A multi-energy-form output energy tower for stepwise recovering waste heat of a gas engine, comprising an internal combustion engine (1), wherein the present invention also comprises a steam Rankine cycle system (2) which is capable of heat exchanging with the high temperature exhaust exhausted from the IC engine (1) to make the steam turbine (22) do expansion work. An organic Rankine cycle system which is respectively heat exchanged with high temperature exhaust, jacket water and charge air which are exhausted from the IC engine (1), and with condensation heat in the steam Rankine cycle system (2) to do expansion work; a lithium bromide refrigerator (4) which uses jacket waterpart of jacket water discharged from the IC engine (1) as a heat source of the absorption cooling system for heat exchange; and a hot water heat exchanger (5) connected with a high temperature exhaust of the IC engine (1) for heating domestic water. The energy tower of the present invention adopts multiple waste heat recovering methods and combines cooling, heating and power supplying methods, which improves comprehensive energy utilization efficiency of the system and achieves the effects of energy saving and emission reduction.