Ship main engine generator combined with EGR system

Abstract

The present invention discloses a ship main engine generator combined EGR system, wherein a first branch pipe branches out from a main engine exhaust manifold and is connected to a boiler through a bypass valve control; the exhaust gas outputted from the second branch pipe is connected to a supercharger to provide power for the supercharger and then outputted to a boiler; the exhaust gas outputted from the third branch pipe is passed into a pre-washing unit with an alkaline liquid; the exhaust gas outputted from the pre-washing unit is inputted into an EGR unit; the exhaust gas outputted from the EGR unit is mixed with fresh air delivered by the supercharger and then blown into a scavenging manifold through an EGR blower, and the scavenging manifold is connected to a main engine combustion chamber; the exhaust gas generated by the generator is outputted to a first exhaust branch pipe and a second exhaust branch pipe, and the first exhaust branch pipe is connected to an SCR device; the second exhaust branch pipe is connected to an input port of the pre-washing unit; the present invention introduces the exhaust gas of the generator into the main engine, and by using the EGR system in combination, it can meet the emission requirements, reduce the energy consumption of the ship and meet the daily navigation needs.

Description

Technical Field

[0001] The invention relates to a ship exhaust system, and more particularly to a ship main engine generator combined EGR system. Background Art

[0002] Conventional ships use EGR systems for their main engines and SCR systems for their generators to meet NOX emission requirements.

[0003] Within the NOX emission zone, the main engine and generator need to meet the TIER III requirements for NOX emissions, and outside the NOX emission zone, the main engine and generator need to meet the TIER II requirements for NOX emissions. Within the SOX emission zone, the main engine and generator need to meet the emission requirements equivalent to burning fuel with a sulfur content of 0.1%, and in the global navigation area outside the SOX emission zone, the main engine and generator need to meet the emission requirements equivalent to burning fuel with a sulfur content of 0.5%.

[0004] There is a pair of conflicting technical requirements for diesel engines such as main engines and generators to meet NOX emission requirements and diesel engine fuel consumption. In order to meet NOX emission requirements, the fuel consumption of diesel engines is usually sacrificed. NOX emissions are divided into 3 levels, TIER I, TIER II, and TIER III. From TIER I to TIER II, it is usually achieved by adjusting diesel engine parameters. From TIER II to TIER III, it must be achieved by adding SCR or EGR systems. This is also the current status of ship configuration and the basis of this invention.

[0005] The current conventional technical solution, i.e. the basic solution, is that the diesel engine directly meets the TIER II emission requirements outside the NOX emission zone, and within the emission zone, the main engine meets the TIER III emission requirements through EGR, and the generator meets the TIER III emission requirements through SCR. However, it is entirely possible to transport the exhaust gas on the generator side to the main engine exhaust for treatment, thereby increasing the efficiency of exhaust treatment and reducing energy consumption. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a ship main engine generator combined EGR system, the purpose of which is to meet the emission requirements and reduce the energy consumption of the ship and meet the daily navigation needs. In order to achieve the above purpose, the present invention adjusts the parameters and control of the generator and the main engine and applies the combined EGR configuration, so that the diesel engine can meet the emission requirements under various working conditions and improve the energy efficiency of the ship.

[0007] The specific technical solutions are as follows:

[0008] A ship main engine generator combined EGR system, comprising a main engine combustion chamber and a generator;

[0009] The exhaust gas generated by the main engine combustion chamber is transported to the main engine smoke exhaust manifold; the main engine smoke exhaust manifold branches into a first branch pipe, a second branch pipe and a third branch pipe;

[0010] The exhaust gas outputted from the first branch pipe is connected to the boiler through a bypass valve;

[0011] The exhaust gas outputted by the second branch pipe is connected to the supercharger to provide power to the supercharger and then outputted to the boiler;

[0012] The exhaust gas outputted from the third branch pipe is controlled by a bypass valve to enter a pre-washing unit (6) with alkaline liquid for washing and desulfurizing the exhaust gas; the exhaust gas outputted from the pre-washing unit (6) is inputted into an EGR unit (7) for cooling the exhaust gas and removing water mist; the exhaust gas outputted from the EGR unit (7) is blown into a scavenging manifold (9) through an EGR blower (8); fresh air delivered from the supercharger (12) is also inputted into the scavenging manifold (9); the scavenging manifold (9) is connected to the main engine combustion chamber (13);

[0013] The exhaust gas generated by the generator is output to the generator exhaust pipe, and the generator exhaust pipe branches into a first exhaust branch pipe and a second exhaust branch pipe. The first exhaust branch pipe is connected to the SCR device; the second exhaust branch pipe is connected to the input port of the pre-washing unit; and bypass valves are provided on the first exhaust branch pipe and the second exhaust branch pipe.

[0014] Preferably, the alkaline liquid provided in the pre-washing unit is sodium hydroxide liquid.

[0015] Preferably, there are three generators, and the exhaust gas output by each generator is respectively introduced into one of the generator exhaust pipes; each of the generator exhaust pipes branches into one of the first exhaust branch pipes and one of the second exhaust branch pipes, and the three first exhaust branch pipes are respectively connected to the three SCR devices.

[0016] Optionally, three of the second smoke exhaust branch pipes are connected in parallel to the input port of the pre-washing unit.

[0017] Optionally, a main pipe formed by connecting three of the second smoke exhaust branch pipes in parallel is connected to the input port of the pre-washing unit after being connected in parallel with the third branch pipe.

[0018] Preferably, each of the first smoke exhaust branch pipe and the second smoke exhaust branch pipe is provided with a bypass valve.

[0019] Preferably, the second smoke exhaust branch pipe is connected to the input port of the pre-washing unit after being connected in parallel with the third branch pipe.

[0020] The advantage of the present invention is that the exhaust smoke of the generator is introduced into the main engine, and by using the EGR system in combination, the total NOX TIER III emission requirements are met in the emission area through the EGR system. In order to improve economy and meet the TIER II emission requirements at the same time, the operating mode of the generator and the main engine can be adjusted to the most economical mode, that is, the lowest fuel consumption mode, which can be considered as the original TIER I mode, which can significantly reduce the fuel consumption of the main engine and the generator, and can also achieve the effect of reducing the ship energy efficiency index EEDI. The sulfur content requirement of the fuel burned by the generator does not have to be 0.1%, and fuel with a sulfur content of 0.5% can be used, because the main engine EGR system includes a pre-washing unit, which is equivalent to a closed washing tower for processing high-sulfur oil, and meets the total sulfur content of 0.1% emission requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the system of the present invention.

[0022] In the figure, 1. generator; 2. SCR equipment; 4. second exhaust branch pipe; 5. main engine exhaust manifold; 6. pre-washing unit; 7. EGR unit; 8. EGR fan; 9. scavenging manifold; 11. boiler; 12. supercharger; 13. main engine combustion chamber. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0024] like Figure 1 As shown, a ship main engine generator combined EGR system of the present invention comprises a main engine combustion chamber 13 and a generator 1;

[0025] The exhaust gas generated by the main engine combustion chamber 13 is transported to the main engine exhaust manifold 5; the main engine exhaust manifold 5 branches into a first branch pipe, a second branch pipe and a third branch pipe;

[0026] The exhaust gas output from the first branch pipe is connected to the boiler 11 through the bypass valve control;

[0027] The exhaust gas outputted from the second branch pipe is connected to the supercharger 12 to provide power to the supercharger 12 and then outputted to the boiler 11;

[0028] The exhaust gas outputted from the third branch pipe is controlled by a bypass valve to enter a pre-washing unit 6 with alkaline liquid for washing and desulfurization of the exhaust gas; the exhaust gas outputted from the pre-washing unit 6 is inputted into an EGR unit 7 for cooling the exhaust gas and removing water mist; the exhaust gas outputted from the EGR unit 7 is blown into a scavenging manifold 9 through an EGR blower 8; the fresh air delivered from the supercharger 12 is also inputted into the scavenging manifold 9; the scavenging manifold 9 is connected to a main engine combustion chamber 13;

[0029] The exhaust gas generated by the generator 1 is output to the generator exhaust pipe, and the generator exhaust pipe branches into a first exhaust branch pipe and a second exhaust branch pipe 4. The first exhaust branch pipe is connected to the SCR device 2; the second exhaust branch pipe 4 is connected to the input port of the pre-washing unit 6; bypass valves are provided on the first exhaust branch pipe and the second exhaust branch pipe 4.

[0030] The alkaline liquid provided in the pre-washing unit 6 is sodium hydroxide liquid.

[0031] There are three generators 1, and the exhaust gas output by each generator 1 is respectively introduced into a generator exhaust pipe; each generator exhaust pipe branches out into a first exhaust branch pipe and a second exhaust branch pipe 4, and the three first exhaust branch pipes are respectively connected to three SCR devices 2. A bypass valve is provided on each first exhaust branch pipe; and a bypass valve is provided on each second exhaust branch pipe 4.

[0032] The three second smoke exhaust branch pipes 4 are connected in parallel to the input port of the pre-washing unit 6. Specifically, the main pipe formed by the three second smoke exhaust branch pipes 4 being connected in parallel is connected to the input port of the pre-washing unit 6 after being connected in parallel with the third branch pipe.

[0033] When in use, the exhaust gas discharged by the generator can be processed by the SCR device 2, or can be input to the input port of the pre-washing unit 6 of the main engine through the interlock of the bypass valve. The exhaust gas output by the main engine combustion chamber 13 is mixed with air after being processed by the pre-washing unit 6 and the EGR unit 7 and then returned to the combustion chamber for combustion. After fully utilizing the exhaust gas, it returns to the main engine exhaust manifold 5. At the same time, the final output of the exhaust gas can be controlled by adjusting the bypass valve on the first branch pipe.

[0034] The details are as follows:

[0035] The working principle of the TIER III main engine EGR system is that when the main engine burns fuel oil containing 0.5% sulfur, 40% of the main engine exhaust volume is passed into the pre-washing unit 6, then passes through the EGR unit 7, and then passes through the EGR fan 8 and the scavenging air generated by the supercharger 12, and enters the scavenging manifold 9, and then enters the main engine combustion chamber 13 for combustion. By reducing the combustion oxygen content and lowering the combustion temperature, the combustion is reorganized to achieve the effect of reducing NOX emissions and meet the TIER III emission requirements, but at the same time, fuel consumption is also increased. The present invention introduces the exhaust of the generator 1 into the inlet of the pre-washing unit 6 of the main engine EGR process through the exhaust, enters the washing and demisting process, and then enters the scavenging manifold 9 and the combustion chamber 13 to participate in the combustion process.

[0036] In order to meet the NOX emission requirements, based on the basic principle of EGR and keeping it in working state all the time, the exhaust gas recirculation volume can be adjusted between 10% and 40%. The greater the recirculation rate, the greater the NOX removal. When the recirculation volume is 10%, it can be considered that the NOX emission of the main engine is reduced from the TIER I level to the TIER II level. When the recirculation volume is 40%, it is equivalent to the NOX emission of the main engine from the TIER II level to the TIER III level. According to the general ship configuration and operating conditions, consider the situation when the power of generator 1 accounts for about 10% of the power of the main engine. Under the main navigation conditions, a generator 1 and the main engine are running at the same time. When the exhaust gas of generator 1 is introduced into the main engine, the exhaust gas bypass valve of generator 1 is fully opened, and the NOX emission system of generator 1 is controlled by the main engine. According to the actual operating conditions, the exhaust gas recirculation volume is adjusted by adjusting the exhaust gas recirculation bypass valve of the main engine and the exhaust gas recirculation EGR fan 8. At the same time, the bypass valve of the first branch pipe of the main engine is adjusted to control the combustion process of the main engine to meet the ship's energy efficiency requirements and emission requirements of different levels. Regardless of whether it is inside or outside the emission area, the main engine generator 1 is used in conjunction with the EGR system. Therefore, in the combined EGR mode, the basic fuel consumption of the main engine and the generator 1 can be reduced by adjusting the internal parameters to achieve the most economical mode or the highest energy efficiency mode, which can also meet the NOX emission requirements, thereby improving the energy efficiency or economy of ship operation.

[0037] The current and upcoming NOX emission areas are also SOX emission areas, so it is required to burn fuel oil with a sulfur content of 0.1%. Because the present invention introduces the exhaust gas of generator 1 into the main engine, all SOX and part of NOX in the exhaust gas of generator 1 can be removed through the pre-washing unit 6 of the main engine EGR. Therefore, in the emission area, generator 1 can burn fuel oil with a sulfur content of 0.5%, and the emission requirements are also met. The main engine EGR system needs to adjust the injection amount of NAOH solution according to the fuel type. Considering the current price difference between the two fuels, the economy of the ship can be significantly improved in the emission area. In the joint mode, generator 1 can always use fuel oil with a sulfur content of 0.5%, which reduces the oil change operation and saves labor costs.

[0038] By adopting the combined EGR system, in order to meet TIER III requirements, the generator 1SCR can be stopped, which also saves the SCR operating costs.

[0039] Usually, the host EGR system is used for a very short time. The present invention increases the utilization time of the EGR system, keeps it in working state for a long time, improves the equipment utilization rate, maintains the stable operation of the equipment and reduces the failure rate of the equipment at the same time.

[0040] Based on the above invention, the main engine and the generator 1 inside and outside the emission area can reduce fuel consumption, thereby reducing the ship energy efficiency index EEDI.

[0041] After the exhaust smoke of generator 1 is introduced into the main engine, all the exhaust smoke is finally discharged through the main engine exhaust pipe. The specifications of the main engine exhaust pipe need to be designed according to the total amount of the main engine and generator 1. Under the premise of meeting the NOX emission requirements, the total amount of exhaust waste heat of the main engine and generator 1 is introduced into the main engine exhaust gas economizer (boiler 11) through the main engine exhaust pipe to generate steam to meet daily navigation needs, without the need for the aforementioned multi-inlet exhaust gas economizer or independent generator 1 economizer configuration, reducing costs and solving the problem of insufficient steam volume for many ships that were previously only equipped with main engine exhaust gas economizers.

[0042] This invention takes the current status of a ship and the comparative analysis of the main engine generator combined with EGR cycle as an example (some parameters are estimated values) to illustrate that the ship's operating cost can be saved by about 100,000 US dollars per year. :

[0043] Host data (TIER II):

[0044] SMCR: 11300kW x 77rpm, ISO exhaust volume 22.1kg / s;

[0045] NCR: 9176kW x 71.8rpm, ISO exhaust volume 19.5kg / s;

[0046] Generator 1 (900rpm) data:

[0047] The diesel engine is 1050kW, the motor is 998kW, and the daily load rate is 85%; the ISO operating exhaust gas volume is 2.0kg / s under daily load and 2.3kg / s under full load.

[0048] The expected technical data comparison is shown in the following table:

[0049]

[0050]

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A ship main engine generator combined with EGR system, characterized in that: It comprises a main engine combustion chamber (13) and a generator (1); The exhaust gas generated by the main engine combustion chamber (13) is transported to the main engine smoke exhaust manifold (5); the main engine smoke exhaust manifold (5) branches into a first branch pipe, a second branch pipe and a third branch pipe; The exhaust gas outputted from the first branch pipe is connected to the boiler (11) through a bypass valve; The exhaust gas outputted by the second branch pipe is connected to the supercharger (12) to provide power for the supercharger (12) and then outputted to the boiler (11); The exhaust gas outputted from the third branch pipe is controlled by a bypass valve to enter a pre-washing unit (6) with alkaline liquid for washing and desulfurizing the exhaust gas; the exhaust gas outputted from the pre-washing unit (6) is inputted into an EGR unit (7) for cooling the exhaust gas and removing water mist; the exhaust gas outputted from the EGR unit (7) is blown into a scavenging manifold (9) through an EGR blower (8); fresh air delivered from the supercharger (12) is also inputted into the scavenging manifold (9); the scavenging manifold (9) is connected to the main engine combustion chamber (13); The exhaust gas generated by the generator (1) is output to the generator exhaust pipe, the generator exhaust pipe branches into a first exhaust branch pipe and a second exhaust branch pipe (4), the first exhaust branch pipe is connected to the SCR device (2); the second exhaust branch pipe (4) is connected to the input port of the pre-washing unit (6); the first exhaust branch pipe and the second exhaust branch pipe (4) are both provided with bypass valves; The alkaline liquid provided in the pre-washing unit (6) is sodium hydroxide liquid; The second smoke exhaust branch pipe (4) is connected in parallel with the third branch pipe and then connected to the input port of the pre-washing unit (6).

2. The ship main engine generator combined with EGR system according to claim 1, characterized in that: There are three generators (1), and the exhaust gas output by each generator (1) is respectively introduced into one of the generator exhaust pipes; each of the generator exhaust pipes branches into one of the first exhaust branch pipes and one of the second exhaust branch pipes (4), and the three first exhaust branch pipes are respectively connected to the three SCR devices (2).

3. The ship main engine generator combined with EGR system according to claim 2, characterized in that: The three second smoke exhaust branch pipes (4) are connected in parallel to the input port of the pre-washing unit (6).

4. The ship main engine generator combined with EGR system according to claim 2, characterized in that: The main pipe formed by connecting the three second smoke exhaust branch pipes (4) in parallel is connected to the third branch pipe in parallel and is connected to the input port of the pre-washing unit (6).

5. The ship main engine generator combined with EGR system according to claim 2, characterized in that: Each of the first smoke exhaust branch pipe and the second smoke exhaust branch pipe (4) is provided with a bypass valve.

6. The ship main engine generator combined with EGR system according to claim 1, characterized in that: The generator (1) burns fuel oil with a sulfur content of 0.5%.

7. The ship main engine generator combined with EGR system according to claim 1, characterized in that: The exhaust gas recirculation rate is 10%~40%.

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