A system and method for generating electricity using waste heat from ship desulfurization pre-cooling water

Abstract

The present invention discloses a system and method for generating electricity by utilizing the waste heat of pre-cooling water of ship desulfurization. The system is arranged based on a pre-cooling spray system, and the air inlet throat is connected to an evaporator at the lower end outlet; the evaporator is connected to a working pump, and the working pump is connected to a liquid storage tank, and the liquid storage tank contains a liquid working medium; the evaporator is connected to an expansion generator at the outlet of the gaseous working medium, and the method is: utilizing the waste heat of the pre-cooling spray wastewater generated by the pre-cooling spray system to heat the liquid working medium into a gaseous working medium, and the gaseous working medium is used as an expansion agent in the expansion generator to drive the expansion generator to generate electricity. The present invention connects the pre-cooling spray wastewater of the pre-cooling spray system in the desulfurization system to the waste heat power generation system, and utilizes the waste heat of the pre-cooling spray wastewater to generate electricity, thereby improving the utilization efficiency of energy, and effectively saving fuel costs. At the same time, it effectively ensures the waste gas treatment effect of the desulfurization system to meet the requirements of low sulfur emissions.

Description

Technical Field

[0001] The present invention relates to a power generation system and method, and in particular to a system and method for generating power by utilizing waste heat of ship desulfurization pre-cooling water. Background Art

[0002] Ships are a high-energy-consuming means of transportation. At the same time, the operation of ships is also accompanied by serious environmental pollution problems. At present, EEDI (Energy Efficiency Design Index) has become an indicator for assessing the energy consumption of ship operation. For the problem of low energy utilization efficiency of ships, in addition to facing high fuel costs, they will also face additional fines to compensate for the damage to the environment.

[0003] Nowadays, a large number of ships are equipped with ship desulfurization systems, which use the desulfurization system to treat the exhaust gas generated by the combustion of diesel fuel by the ship's main engine. In the process of the desulfurization system treating the high-temperature exhaust gas, a large amount of waste heat will be generated. How to effectively improve the utilization efficiency of waste heat is one of the important ways for the shipbuilding industry to enhance its competitiveness; if the waste heat cannot be fully utilized, the fuel cost will be further increased and the energy utilization efficiency will be reduced; therefore, in order to effectively reduce the energy consumption index of ship operation, it is urgent to provide a power generation system and method that can fully utilize the waste heat of ship desulfurization pre-cooling water. Summary of the invention

[0004] In order to solve the deficiencies of the above-mentioned technologies, the present invention provides a system and method for generating electricity using waste heat from ship desulfurization pre-cooling water.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a system for generating electricity by utilizing the waste heat of pre-cooling water of ship desulfurization, based on the setting of the pre-cooling spray system, the pre-cooling spray system is located in the air intake throat on one side of the desulfurization tower; the power generation system includes an evaporator, an expansion generator, and a working fluid pump;

[0006] The air inlet throat is connected to the evaporator at the lower end outlet, and the pre-cooling spray water generated by the pre-cooling spray system flows into the evaporator through the lower end outlet of the air inlet throat; the evaporator is connected to the working pump, and the working pump is connected to a liquid storage tank, and the liquid storage tank contains liquid working medium; the liquid working medium in the liquid storage tank is sucked by the working medium pump and pumped into the evaporator for heat exchange with the pre-cooling spray wastewater;

[0007] The liquid working medium becomes a gaseous working medium after absorbing heat. The evaporator is connected to an expansion generator at the outlet of the gaseous working medium. The gaseous working medium acts as an expansion agent in the expansion generator to drive the expansion generator to generate electricity.

[0008] Furthermore, the rear end of the expansion generator is connected to a condenser, the condenser is connected to a seawater pump, and the condenser is also connected to a liquid storage tank; the seawater pumped in by the seawater pump provides a cold source for the condenser, and the working fluid condensed into a liquid phase enters the liquid storage tank and is sucked again by the working fluid pump for the next cycle.

[0009] Furthermore, the evaporator is connected to a heat exchanger at the outlet of the pre-cooling spray waste water, and the seawater pump is connected to the pre-cooling spray system through the heat exchanger.

[0010] Furthermore, a desulfurization tower exhaust port is arranged at the top of the desulfurization tower, and a desulfurization tower air inlet is arranged at the top of the air inlet throat.

[0011] A power generation method of a system utilizing waste heat of pre-cooling water of ship desulfurization for power generation, characterized in that: pre-cooling spray wastewater containing waste heat is discharged from the lower end of the air inlet throat where the air inlet of the desulfurization tower is located and flows into the evaporator, and at the same time, a working pump sucks liquid organic working medium in a liquid storage tank and pumps the liquid organic working medium into the evaporator; high-temperature pre-cooling spray wastewater and low-temperature liquid organic working medium perform heat exchange in the evaporator, wherein the liquid organic working medium absorbs heat and becomes a gaseous organic working medium; a large amount of heat is absorbed from the pre-cooling spray wastewater, and the temperature is reduced;

[0012] The gaseous organic working fluid enters the expansion generator, converts its own pressure energy and thermal energy into mechanical energy, and then drives the expander of the expansion generator to drag the generator to convert the mechanical energy into electrical energy.

[0013] Furthermore, the temperature and pressure of the gaseous organic working fluid after doing work in the expansion generator are reduced, and it is in a gas-liquid two-phase state and enters the condenser to exchange heat with the seawater supplied by the seawater pump. The organic working fluid in the gas-liquid two-phase state is completely condensed into a liquid phase and enters the liquid storage tank. The liquid working fluid is pumped back into use by the working fluid pump, thereby realizing the recycling of the condensed liquid working fluid.

[0014] Furthermore, the pre-cooling spray wastewater still containing residual heat enters the evaporator to exchange heat with the seawater supplied by the seawater pump. This water of the seawater pump is preheated and used for the work of the pre-cooling spray system.

[0015] Furthermore, the waste heat of the pre-cooling spray wastewater is obtained by absorbing the heat of the high-temperature exhaust gas generated by the ship's main engine during the initial cooling process of the pre-cooling spray system.

[0016] The present invention discloses a system and method for generating electricity by utilizing the waste heat of pre-cooling water of ship desulfurization. The pre-cooling spray waste water of the pre-cooling spray system in the desulfurization system is connected to the waste heat power generation system, so that the ship is equipped with a waste heat power generation system and a desulfurization system at the same time. The power generation system generates electricity by utilizing the waste heat of the pre-cooling spray waste water. The electric energy generated by the power generation system can be used for the operation of the ship, which not only improves the energy utilization efficiency, but also effectively saves fuel costs. At the same time, the waste heat of the pre-cooling spray waste water is also used to preheat the spray water used by the pre-cooling spray system. The assembly of this power supply system will not cause the problem of excessive back pressure of the desulfurization system, thereby effectively ensuring the exhaust gas treatment effect of the desulfurization system to meet the requirements of low sulfur emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the system connection relationship of the present invention.

[0018] 1. Condenser; 2. Expansion generator; 3. Evaporator; 4. Pre-cooling spray system; 5. Desulfurization tower air inlet; 6. Desulfurization tower exhaust port; 7. Spray system; 8. Seawater pump; 9. Heat exchanger; 10. Working fluid pump; 11. Liquid storage tank; 12. Desulfurization tower. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0020] A system for generating electricity by utilizing waste heat from pre-cooling water of ship desulfurization is designed based on the pre-cooling spray system 4 on the existing ship. Figure 1 As shown, the pre-cooling spray system 4 needs to be used in conjunction with the spray system 7; the spray system 7 is located in the desulfurization tower 12, one side of the desulfurization tower 12 is connected to an air intake throat, and the pre-cooling spray system 4 is located in the air intake throat;

[0021] The power generation system includes an evaporator 3, an expansion generator 2, a condenser 1, a working fluid pump 10, and a seawater pump 8; first, the air intake throat is connected to the evaporator 3 at the lower end outlet, and at the same time, the evaporator 3 is connected to the working pump 10, and the working pump 10 is connected to the liquid storage tank 11; the pre-cooling spray water generated by the pre-cooling spray system 4 flows into the evaporator 3 through the lower end outlet of the air intake throat, and the pre-cooling spray waste water containing residual heat enters the evaporator 3, and at the same time, the working fluid pump 10 sucks the liquid working fluid in the liquid storage tank 11 and pumps it into the evaporator 3 to exchange heat with the pre-cooling spray waste water containing residual heat; the liquid working fluid absorbs heat and becomes a gaseous working fluid, and the evaporator 3 is connected to the expansion generator 2 at the outlet of the gaseous working fluid, and the gaseous working fluid acts as an expansion agent in the expansion generator 2 to drive the expansion generator 2 to generate electricity.

[0022] After the gaseous working medium does work, its temperature and pressure decrease and it becomes a gas-liquid two-phase state. The expansion generator 2 is further connected to the condenser 1. The working medium in the gas-liquid two-phase state enters the condenser 1 and exchanges heat with the seawater pumped into the condenser 1 by the seawater pump 8. At this time, the working medium is completely condensed into a liquid phase and enters the liquid storage tank 11, and is pumped again by the working medium pump 10 for the next cycle.

[0023] For the pre-cooling spray wastewater in the evaporator 3, the temperature will be reduced due to the heat absorbed by the liquid working medium, but it still contains unused waste heat. In order to further make full use of the waste heat, the evaporator 3 is connected with a heat exchanger 9 at the outlet of the pre-cooling spray wastewater. The heat exchanger 9 is connected to the pre-cooling spray system 4 and the seawater pump 8. Therefore, the pre-cooling spray wastewater flowing out of the evaporator 3 enters the heat exchanger 9 to exchange heat with the seawater supplied by the seawater pump 8. The seawater absorbs heat and heats up, and is used as the pre-cooling spray water of the pre-cooling spray system. The water temperature of the pre-cooling spray water is higher than the normal seawater temperature used by the spray system, which will not cause the problem of excessive back pressure of the desulfurization system, thereby effectively ensuring the desulfurization spray effect of the desulfurization tower.

[0024] For the seawater pump 8, its water supply waterway is divided into three routes, one route is connected to the spray system 7, one route is connected to the pre-cooling spray system 4 through the heat exchanger 9, and one route is connected to the condenser 1; the high-temperature exhaust gas generated by the ship's main engine first enters the air inlet throat of the desulfurization tower 12 from the desulfurization tower air inlet 5, is first cooled by the pre-cooling spray system 4 at the air inlet throat, and then enters the desulfurization tower 12 for desulfurization treatment by the spray system 7, and is finally discharged from the desulfurization tower exhaust port 6.

[0025] The high-temperature exhaust gas generated by the main engine is initially cooled by the pre-cooling spray system 4. At the same time, the pre-cooling spray water absorbs the heat of the high-temperature exhaust gas to become pre-cooling spray waste water. The pre-cooling spray waste water contains a large amount of waste heat. If the pre-cooling spray waste water is directly discharged, it will cause serious waste of energy. Therefore, the present invention utilizes the waste heat to generate electricity, thereby realizing efficient utilization of energy. At the same time, the waste heat is further utilized to preheat the pre-cooling spray water, which will not cause the problem of excessive back pressure in the desulfurization system, thereby achieving a better desulfurization spray effect.

[0026] A method for generating electricity by utilizing waste heat of pre-cooling water of ship desulfurization is realized based on the above power generation system, specifically comprising: pre-cooling spray wastewater is discharged from the lower end of the air inlet throat where the air inlet 5 of the desulfurization tower is located and flows into the evaporator 3, and at the same time, the working pump 10 sucks the liquid organic working medium in the liquid storage tank 11 and pumps the liquid organic working medium into the evaporator 3; the high-temperature pre-cooling spray wastewater and the low-temperature liquid organic working medium exchange heat in the evaporator 3, wherein the liquid organic working medium absorbs heat and becomes a gaseous organic working medium; a large amount of heat is absorbed by the pre-cooling spray wastewater, and the temperature is reduced;

[0027] The gaseous organic working medium further enters the expansion generator 2, which is an expander and a generator in one. The gaseous organic working medium enters the expander of the expansion generator, converts its own pressure energy and heat energy into mechanical energy, and then drives the expander to drag the generator to convert the mechanical energy into electrical energy; the temperature and pressure of the gaseous organic working medium after working are reduced, and it is in a gas-liquid two-phase state and enters the condenser 1 to exchange heat with the seawater supplied by the seawater pump 8. The organic working medium in the gas-liquid two-phase state is completely condensed into a liquid phase and enters the liquid storage tank 11, realizing the recycling of the condensed liquid working medium, and the liquid working medium is pumped into the evaporator 3 again by the working medium pump 10 for the next working cycle.

[0028] The pre-cooling spray wastewater cooled in the evaporator 3 enters the heat exchanger 9 and exchanges heat with the seawater pumped in by the seawater pump 8. This seawater is preheated and used for desulfurization spraying in the pre-cooling spraying system, thereby realizing the reuse of waste heat, further improving energy utilization efficiency, and ensuring the desulfurization spraying effect.

[0029] Usually, the temperature of seawater pumped by the seawater pump 8 is about 32°C, and the exhaust gas generated by the main engine is a high-temperature exhaust gas of 220°C. The high-temperature exhaust gas of 220°C enters the air intake throat through the air inlet 5 of the desulfurization tower, and is cooled for the first time by the pre-cooling spray system. The pre-cooling spray water absorbs a large amount of heat in the process of cooling the high-temperature exhaust gas, and its temperature rises to about 120°C, and is discharged from the lower end of the air intake throat in the form of pre-cooling spray waste water, and enters the evaporator to heat the liquid organic working medium. After heat exchange, the temperature of the pre-cooling spray waste water drops to about 90°C, and then flows into the heat exchanger, and the pre-cooling spray water pumped into the pre-cooling spray system by the seawater pump 8 is preheated to 58°C, thereby realizing the preheating of the pre-cooling spray water and making full use of the waste heat. Finally, the pre-spray waste water in the heat exchanger merges with the wastewater discharge pipe of the desulfurization tower and is discharged to the drainage system.

[0030] The above implementation modes are not limitations of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also belong to the protection scope of the present invention.

Claims

1. A system for generating electricity using waste heat from pre-cooling water of a desulfurization vessel, the system being based on a pre-cooling spray system (4), the pre-cooling spray system (4) being located in the air intake throat on one side of a desulfurization tower (12); characterized in that: The power generation system comprises an evaporator (3), an expansion generator (2), and a working fluid pump (10); The air inlet throat is connected to the evaporator (3) at the lower end outlet, and the pre-cooling spray wastewater generated by the pre-cooling spray system (4) flows into the evaporator (3) through the lower end outlet of the air inlet throat; the evaporator (3) is connected to the working fluid pump (10), and the working fluid pump (10) is connected to a liquid storage tank (11), and the liquid storage tank (11) contains liquid working fluid; the liquid working fluid in the liquid storage tank (11) is sucked by the working fluid pump (10) and pumped into the evaporator (3) for heat exchange with the pre-cooling spray wastewater; The liquid working medium absorbs heat and becomes a gaseous working medium. The evaporator (3) is connected to the expansion generator (2) at the outlet of the gaseous working medium. The gaseous working medium drives the expansion generator (2) to generate electricity in the expansion generator (2). The rear end of the expansion generator (2) is connected to a condenser (1), the condenser (1) is connected to a seawater pump (8), and the condenser (1) is also connected to a liquid storage tank (11); the seawater pumped in by the seawater pump (8) provides a cold source for the condenser, and the working fluid condensed into a liquid phase enters the liquid storage tank (11) and is sucked again by the working fluid pump (10) for the next cycle; The evaporator (3) is connected to a heat exchanger (9) at the outlet of the pre-cooling spray wastewater, and the seawater pump (8) is connected to the pre-cooling spray system (4) through the heat exchanger (9); The water supply circuit of the seawater pump (8) is divided into three circuits, one circuit connected to the spray system (7), one circuit connected to the pre-cooling spray system (4) via the heat exchanger (9), and one circuit connected to the condenser (1).

2. The system for generating electricity by utilizing waste heat from ship desulfurization pre-cooling water according to claim 1 is characterized in that: A desulfurization tower exhaust port (6) is provided at the top of the desulfurization tower (12), and a desulfurization tower air inlet (5) is provided at the top of the air inlet throat.

3. A power generation method of a system for generating power using waste heat from ship desulfurization pre-cooling water as claimed in claim 2, characterized in that: The pre-cooling spray wastewater containing residual heat is discharged from the lower end of the air inlet throat where the desulfurization tower air inlet (5) is located and flows into the evaporator (3). At the same time, the working fluid pump (10) sucks the liquid organic working fluid in the liquid storage tank (11) and pumps the liquid organic working fluid into the evaporator (3). The high-temperature pre-cooling spray wastewater and the low-temperature liquid organic working fluid exchange heat in the evaporator (3), wherein the liquid organic working fluid absorbs heat and becomes a gaseous organic working fluid. A large amount of heat is absorbed from the pre-cooling spray wastewater, and the temperature is reduced. The gaseous organic working fluid enters the expansion generator (2), converts its own pressure energy and thermal energy into mechanical energy, and then drives the expander of the expansion generator (2) to drive the generator to convert the mechanical energy into electrical energy.

4. The power generation method of the system for generating power by utilizing waste heat of ship desulfurization pre-cooling water according to claim 3 is characterized in that: After doing work in the expansion generator (2), the temperature and pressure of the gaseous organic working fluid are both reduced, and the gaseous organic working fluid is in a gas-liquid two-phase state and enters the condenser (1) to exchange heat with the seawater supplied by the seawater pump (8). The gas-liquid two-phase organic working fluid is completely condensed into a liquid phase and enters the liquid storage tank (11). The liquid working fluid is pumped and reused by the working fluid pump (10), thereby realizing the recycling of the condensed liquid working fluid.

5. The power generation method of the system for generating power by utilizing waste heat of ship desulfurization pre-cooling water according to claim 4 is characterized in that: The pre-cooling spray wastewater still containing residual heat enters the heat exchanger (9) to exchange heat with the seawater supplied by the seawater pump (8). This water of the seawater pump (8) is preheated and used for the operation of the pre-cooling spray system (4).

6. The power generation method of the system for generating power by utilizing waste heat of ship desulfurization pre-cooling water according to claim 5, characterized in that: The waste heat of the pre-cooling spray wastewater is obtained by absorbing the heat of the high-temperature exhaust gas generated by the ship's main engine during the initial cooling process of the pre-cooling spray system (4).

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