Marine main engine flue gas waste heat recycling power generation system
By setting up a multi-stage heat recovery system on the flue gas output line of the ship main engine, including the first-stage single-stage heat recovery SRC, the second-stage single-stage heat recovery SRC, the third-stage single-stage heat recovery ORC and the fourth-stage single-stage heat recovery ORC, the problem of low flue gas waste heat recovery efficiency in the existing technology is solved, and efficient waste heat utilization and significant energy-saving and emission reduction effects are achieved.
Patent Information
- Application Number
- CN202510543448.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-07-18
AI Technical Summary
The flue gas waste heat recovery system of existing marine diesel engines is inefficient and cannot maximize waste heat recovery and power generation in different temperature segments, resulting in unsatisfactory energy waste and energy conservation and emission reduction effects.
A multi-stage heat recovery system is adopted, including a single-stage heat recovery SRC of the first-stage dual-turbine turbine, a single-stage heat recovery SRC of the second-stage single-turbine turbine, and a single-stage heat recovery ORC of the third-stage single-turbine turbine, and is set in sequence according to the flue gas temperature to achieve efficient waste heat utilization at the stage.
The recycling efficiency of the waste heat of the ship's main engine has been significantly improved, and the cumulative power generation power has reached 966.91kW, achieving the efficient utilization of the waste heat of the ship's main engine, and significantly saving energy and emission reduction.
Smart Images
Figure CN120331923A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a power generation system for recovering waste heat from the flue gas of a ship's main engine. Background Art
[0002] With the advent of the green economy, energy conservation and emission reduction have become one of the major issues in all industries. Limited by technical conditions, currently, most ships use diesel engines as the main power source. However, when the diesel engine is working, more than 20% of the heat generated by the fuel is discharged with the high-temperature flue gas and not converted into useful work, resulting in energy waste. Therefore, if the exhaust waste heat can be collected and converted into electric energy, it can not only significantly improve the energy conservation and emission reduction effect of the ship, but also greatly reduce the operating cost of the ship.
[0003] Among various cycle theories applicable to the field of waste heat recovery and power generation from the flue gas of the main engine, thermal recovery cycles such as the steam Rankine cycle (SRC) and the organic Rankine cycle (ORC) are the most widely used. At present, most ships use a heat energy recovery system based on a single cycle principle. Considering the large span of the exhaust gas temperature of large two-stroke ship diesel engines, the heat energy recovery system based on a single cycle principle cannot recover waste heat for power generation to the maximum extent in each temperature section, and the actual working efficiency is not very ideal. Summary of the Invention
[0004] The purpose of the present invention is to provide a power generation system for recovering waste heat from the flue gas of a ship's main engine, including a ship's main engine. A multi-stage regenerative system is sequentially arranged on the flue gas output line of the ship's main engine according to a temperature gradient. The multi-stage regenerative system includes: a first-stage double steam turbine single-stage regenerative SRC, a second-stage single steam turbine non-regenerative SRC, and a third-stage single steam turbine single-stage regenerative ORC. A fourth-stage single steam turbine single-stage regenerative ORC is provided on the working fluid pipeline between the turbine unit of the first-stage double steam turbine single-stage regenerative SRC and the first condenser.
[0005] Preferably, the first-stage double steam turbine single-stage regenerative SRC includes a first evaporator arranged on the flue gas output line. The first evaporator is connected to the turbine unit through a working fluid pipeline. The turbine unit is drivingly connected to a first generator. The turbine unit is connected to the first condenser through a working fluid pipeline. The first condenser is connected to a regenerator group through a working fluid pipeline. A first pump body is provided on the working fluid pipeline between the first condenser and the regenerator group. The regenerator group is connected to the first evaporator through a pipeline. A second pump body is provided on the working fluid pipeline between the regenerator group and the first evaporator.
[0006] Preferably, the steam turbine unit includes a first steam turbine and a second steam turbine, the regenerator group includes a first low-pressure regenerator and a high-pressure regenerator, and the first steam turbine is connected to the high-pressure regenerator through a steam extraction pipeline.
[0007] Preferably, the second-stage single steam turbine without regeneration SRC includes a second evaporator provided on the flue gas output line. The second evaporator is connected to a third steam turbine through a working fluid pipeline. The third steam turbine is drivingly connected to a second generator. The third steam turbine is connected to a second condenser through a working fluid pipeline. The second condenser is connected to the second evaporator through a working fluid pipeline. A third pump body is provided on the working fluid pipeline between the second condenser and the second evaporator.
[0008] Preferably, the third-stage single steam turbine with single-stage regeneration ORC includes a third evaporator provided on the flue gas output line. The third evaporator is connected to a fourth steam turbine through a working fluid pipeline. The fourth steam turbine is drivingly connected to a third generator. The fourth steam turbine is connected to a second low-pressure regenerator through a working fluid pipeline. The second low-pressure regenerator is connected to a third condenser through a working fluid pipeline. The third condenser is connected back to the second low-pressure regenerator through a working fluid pipeline. A fourth pump body is provided on the working fluid pipeline between the third condenser and the second low-pressure regenerator. The second low-pressure regenerator is connected to the third evaporator through a working fluid pipeline.
[0009] Preferably, the fourth-stage single steam turbine with single-stage regeneration ORC includes a fourth evaporator provided on the working fluid pipeline between the steam turbine unit and the first condenser. The fourth evaporator is connected to a fifth steam turbine through a working fluid pipeline. The fifth steam turbine is drivingly connected to a fourth generator. The fifth steam turbine is connected to a third low-pressure regenerator through a working fluid pipeline. The third low-pressure regenerator is connected to a fourth condenser through a working fluid pipeline. The fourth condenser is connected back to the third low-pressure regenerator through a working fluid pipeline. A fifth pump body is provided on the working fluid pipeline between the fourth condenser and the third low-pressure regenerator. The third low-pressure regenerator is connected to the fourth evaporator through a working fluid pipeline.
[0010] The advantages and beneficial effects of the present invention are as follows: A ship main engine flue gas waste heat recovery power generation system is provided. By arranging three levels of power generation with different thermal efficiencies on the flue gas output line of the ship main engine according to the step change of the flue gas temperature, and performing fourth-level power generation on the exhausted steam discharged in the first-stage regenerative cycle, the recovery efficiency of the ship main engine flue gas waste heat is improved, the stepwise high-efficiency utilization of the ship main engine waste heat is realized, and the energy conservation and emission reduction effect is remarkable. Brief Description of the Drawings
[0011] Figure 1 is a schematic diagram of the present invention. Detailed Embodiments
[0012] The following will further describe the specific embodiments of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.
[0013] The technical solution of the specific implementation of the present invention is as follows: As Figure 1 shown, a power generation system for recovering waste heat from the flue gas of a marine main engine includes a marine main engine. On the flue gas output line 1 of the marine main engine, a multi-stage regenerative system is sequentially arranged according to the temperature gradient. The multi-stage regenerative system includes: a first-stage double steam turbine single-stage regenerative SRC, a second-stage single steam turbine non-regenerative SRC, and a third-stage single steam turbine single-stage regenerative ORC; On the working fluid pipeline between the turbine steam turbine unit (3 + 4) of the first-stage double steam turbine single-stage regenerative SRC and the first condenser 6, a fourth-stage single steam turbine single-stage regenerative ORC is provided.
[0014] The above-mentioned first-stage double steam turbine single-stage regenerative SRC includes a first evaporator 2 arranged on the flue gas output line 1. The first evaporator 2 is connected to the turbine steam turbine unit (3 + 4) through a working fluid pipeline. The turbine steam turbine unit (3 + 4) is drivingly connected to a first generator 5. The turbine steam turbine unit (3 + 4) is connected to the first condenser 6 through a working fluid pipeline. The first condenser 6 is connected to a regenerator group (8 + 9) through a working fluid pipeline. A first pump body 7 is provided on the working fluid pipeline between the first condenser 6 and the regenerator group (8 + 9). The regenerator group (8 + 9) is connected to the first evaporator 2 through a working fluid pipeline. A second pump body 10 is provided on the working fluid pipeline between the regenerator group (8 + 9) and the first evaporator 2; Specifically, the flue gas enters the first evaporator 2 and exchanges heat with the working fluid water in the first evaporator 2. The water absorbs the heat of the flue gas and becomes steam, enters the turbine steam turbine unit (3 + 4) to expand and do work. The turbine steam turbine unit (3 + 4) drives the first generator 5 to generate electricity. The exhaust steam discharged from the turbine steam turbine unit (3 + 4) enters the fourth evaporator 22, exchanges heat with the working fluid R245fa (pentafluoropropane) in the fourth evaporator 22, and then enters the first condenser 6 to condense into water. The water enters the regenerator group (8 + 9) through the first pump body 7 and then enters the first evaporator 2 again through the second pump body 10 to complete the cycle.
[0015] The above-mentioned turbine steam turbine unit (3 + 4) includes a first turbine steam turbine 3 and a second turbine steam turbine 4. The regenerator group (8 + 9) includes a first low-pressure regenerator 8 and a high-pressure regenerator 9. The first turbine steam turbine 3 is connected to the high-pressure regenerator 9 through a steam extraction pipeline; Specifically, part of the steam is extracted from the first steam turbine 9 through the extraction pipeline and enters the high-pressure regenerative heater 9 and the low-pressure regenerative heater 8 in sequence to heat the water passing through the high-pressure regenerative heater 9 and the low-pressure regenerative heater 8.
[0016] The above-mentioned second-stage single steam turbine non-regenerative SRC includes a second evaporator 11 provided on the flue gas output line 1. The second evaporator 11 is connected to a third steam turbine 12 through a working medium pipeline. The third steam turbine 12 is drivingly connected to a second generator 13. The third steam turbine 12 is connected to a second condenser 14 through a working medium pipeline. The second condenser 14 is connected to the second evaporator 11 through a working medium pipeline. A third pump body 15 is provided on the working medium pipeline between the second condenser 14 and the second evaporator 11; Specifically, the flue gas enters the second evaporator 11 and exchanges heat with the working medium water in the second evaporator 11. The water absorbs the heat of the flue gas and becomes steam. The steam enters the third steam turbine 12 to expand and do work. The third steam turbine 12 drives the second generator 13 to generate electricity. The exhausted steam discharged from the third steam turbine 12 enters the second condenser 14 to condense into water. The water re-enters the second evaporator 11 through the third pump body 15 to complete the cycle.
[0017] The above-mentioned third-stage single steam turbine single-stage regenerative ORC includes a third evaporator 16 provided on the flue gas output line 1. The third evaporator 16 is connected to a fourth steam turbine 17 through a working medium pipeline. The fourth steam turbine 17 is drivingly connected to a third generator 18. The fourth steam turbine 17 is connected to a second low-pressure regenerative heater 19 through a working medium pipeline. The second low-pressure regenerative heater 19 is connected to a third condenser 20 through a working medium pipeline. The third condenser 20 is re-connected to the second low-pressure regenerative heater 19 through a working medium pipeline. A fourth pump body 21 is provided on the working medium pipeline between the third condenser 20 and the second low-pressure regenerative heater 19. The second low-pressure regenerative heater 19 is connected to the third evaporator 16 through a working medium pipeline; Specifically, the flue gas enters the third evaporator 16 and exchanges heat with the liquid R141b in the third evaporator 16. The R141b evaporates and enters the fourth steam turbine 17 to expand and do work. The fourth steam turbine 17 drives the third generator 18 to generate electricity. The gaseous R141b discharged from the fourth steam turbine 17 enters the second low-pressure regenerative heater 19 and then enters the third condenser 20 to condense into a liquid. The liquid R141b returns to the second low-pressure regenerative heater 19 through the fourth pump body 21, exchanges heat with the gaseous R141, and then enters the third evaporator 16 to complete the cycle.
[0018] The above-mentioned fourth-stage single steam turbine single-stage regenerative ORC includes a fourth evaporator 22 disposed on the working fluid pipeline between the turbine steam turbine unit (3 + 4) and the first condenser 6. The fourth evaporator 22 is connected to a fifth steam turbine 23 through a working fluid pipeline. The fifth steam turbine 23 is drivingly connected to a fourth generator 24. The fifth steam turbine 23 is connected to a third low-pressure regenerator 25 through a working fluid pipeline. The third low-pressure regenerator 25 is connected to a fourth condenser 26 through a working fluid pipeline. The fourth condenser 26 is connected back to the third low-pressure regenerator 25 again through a working fluid pipeline. A fifth pump body 27 is provided on the working fluid pipeline between the fourth condenser 26 and the third low-pressure regenerator 25. The third low-pressure regenerator 25 is connected to the fourth evaporator 22 through a working fluid pipeline; Specifically, since the exhaust steam temperature of the turbine steam turbine unit (3 + 4) is relatively high, reaching 140 °C, if it directly enters the first condenser 6 for cooling, it will not only cause a huge working burden on the first condenser 6, but also there is a problem of waste of thermal energy; Therefore, the exhaust steam of the turbine steam turbine unit (3 + 4) enters the fourth evaporator 22, exchanges heat with the liquid-phase R245fa in the fourth evaporator 22, and then enters the first condenser 6 for circulation. The R245fa evaporates and enters the fifth steam turbine 23 to expand and do work. The fifth steam turbine 23 drives the fourth generator 24 to generate electricity. The steam discharged from the fifth steam turbine 23 enters the third low-pressure regenerator 25, and then enters the fourth condenser 26 to condense into a liquid. The liquid returns to the third low-pressure regenerator 25 again through the fifth pump body 27, exchanges heat with the gaseous R245fa in the third low-pressure regenerator 25, and finally enters the fourth evaporator 22 again to complete the cycle.
[0019] During use, the flue gas (about 400 °C) discharged from the ship's main engine is discharged to the outside through the flue gas output line 1. After the heat of the 400 °C flue gas is recovered by the first-stage double steam turbine single-stage regenerative SRC, the flue gas temperature drops to 298.3 °C. The power generation power of the first-stage double steam turbine single-stage regenerative SRC is 263.1 kW. The temperature of the flue gas is still relatively high. After the heat is recovered by the second-stage single steam turbine non-regenerative SRC, the flue gas temperature drops to 206.2 °C. The power generation power of the second-stage single steam turbine non-regenerative SRC is 241.2 kW. After the first two stages use SRC for heat recovery, the flue gas temperature drops a lot, but there is still value in waste heat recovery. Finally, after the heat is recovered by the third-stage single steam turbine single-stage regenerative ORC, the flue gas temperature drops to 112.4 °C. The power generation power of the third-stage single steam turbine single-stage regenerative ORC is 214.5 kW; after three-stage heat recovery, the waste heat recovery power generation of the flue gas discharged from the ship's main engine has been completed.
[0020] However, the exhaust steam temperature of the turbine unit (3 + 4) of the first-stage double steam turbine single-stage regenerative SRC is relatively high, reaching 140 °C. If it directly enters the first condenser 6 for cooling, it will not only impose a huge working burden on the first condenser 6, but also there is a problem of waste of thermal energy. Therefore, we use the fourth-stage single steam turbine single-stage regenerative ORC to recover the waste heat of this part of the hot water. The power generation of the fourth-stage single steam turbine single-stage regenerative ORC is 221.20 kW, and the temperature of the hot water after recovery is 72.6 °C. The hot water then enters the first condenser 6 again.
[0021] Through four-stage heat recovery, heat absorption and power generation are carried out in each stage of the waste heat recovery power generation process of the ship's main engine flue gas. The exhaust temperature of the ship's main engine flue gas is reduced from the initial 400 °C to 112.4 °C, and the cumulative power generation reaches 966.91 kW, improving the recovery efficiency of the ship's main engine flue gas waste heat, realizing the cascade and efficient utilization of the ship's main engine waste heat, and having remarkable energy conservation and emission reduction effects.
[0022] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A waste heat recovery power generation system for a marine main engine, comprising a marine main engine, characterized in that, A multi-stage regenerative system is sequentially arranged on the flue gas output line of the ship's main engine according to the temperature gradient. The multi-stage regenerative system includes: the first-stage double steam turbine single-stage regenerative SRC, the second-stage single steam turbine non-regenerative SRC, and the third-stage single steam turbine single-stage regenerative ORC; A fourth-stage single steam turbine single-stage regenerative ORC is arranged on the working medium pipeline between the turbine steam turbine unit of the first-stage double steam turbine single-stage regenerative SRC and the first condenser.
2. The marine main engine flue gas waste heat recovery power generation system according to claim 1, characterized in that, The first-stage double steam turbine single-stage regenerative SRC includes a first evaporator arranged on the flue gas output line. The first evaporator is connected to the turbine steam turbine unit through a working medium pipeline. The turbine steam turbine unit is drivingly connected to a first generator. The turbine steam turbine unit is connected to the first condenser through a working medium pipeline. The first condenser is connected to a regenerator group through a working medium pipeline. A first pump body is arranged on the working medium pipeline between the first condenser and the regenerator group. The regenerator group is connected to the first evaporator through a working medium pipeline. A second pump body is arranged on the working medium pipeline between the regenerator group and the first evaporator.
3. A power generation system for recovering waste heat from the flue gas of a marine main engine according to claim 2, characterized in that, The turbine steam turbine unit includes a first turbine steam turbine and a second turbine steam turbine. The regenerator group includes a first low-pressure regenerator and a high-pressure regenerator. The first turbine steam turbine is connected to the high-pressure regenerator through a steam extraction pipeline.
4. A power generation system for recovering waste heat from the flue gas of a marine main engine according to claim 3, characterized in that, The second-stage single steam turbine non-regenerative SRC includes a second evaporator arranged on the flue gas output line. The second evaporator is connected to a third turbine steam turbine through a working medium pipeline. The third turbine steam turbine is drivingly connected to a second generator. The third turbine steam turbine is connected to a second condenser through a working medium pipeline. The second condenser is connected to the second evaporator through a working medium pipeline. A third pump body is arranged on the working medium pipeline between the second condenser and the second evaporator.
5. A power generation system for recovering waste heat from the flue gas of a marine main engine according to claim 4, characterized in that, The third-stage single steam turbine single-stage regenerative ORC includes a third evaporator arranged on the flue gas output line. The third evaporator is connected to a fourth turbine steam turbine through a working medium pipeline. The fourth turbine steam turbine is drivingly connected to a third generator. The fourth turbine steam turbine is connected to a second low-pressure regenerator through a working medium pipeline. The second low-pressure regenerator is connected to a third condenser through a working medium pipeline. The third condenser is connected back to the second low-pressure regenerator through a working medium pipeline. A fourth pump body is arranged on the working medium pipeline between the third condenser and the second low-pressure regenerator. The second low-pressure regenerator is connected to the third evaporator through a working medium pipeline.
6. A power generation system for recovering waste heat from the flue gas of a marine main engine according to claim 5, characterized in that, The fourth-stage single steam turbine single-stage regenerative ORC includes a fourth evaporator arranged on the working medium pipeline between the turbine steam turbine unit and the first condenser. The fourth evaporator is connected to a fifth turbine steam turbine through a working medium pipeline. The fifth turbine steam turbine is drivingly connected to a fourth generator. The fifth turbine steam turbine is connected to a third low-pressure regenerator through a working medium pipeline. The third low-pressure regenerator is connected to a fourth condenser through a working medium pipeline. The fourth condenser is connected back to the third low-pressure regenerator through a working medium pipeline. A fifth pump body is arranged on the working medium pipeline between the fourth condenser and the third low-pressure regenerator. The third low-pressure regenerator is connected to the fourth evaporator through a working medium pipeline.