A cryogenic system for direct external air intake of a main engine and its control method

Abstract

This invention discloses a cryogenic system for direct external air intake of a main engine and its control method, relating to the field of marine main engine air intake control. The system includes a main engine, a turbocharger assembly, an intake manifold, an intake return pipe, an exhaust manifold, an exhaust bypass pipe, an air cooler, a PLC controller, an electric flue gas bypass valve, an electric booster air return valve, and a temperature acquisition device. The compressor is connected in series to the intake manifold, and the turbine is connected in series to the exhaust manifold. This method uses intake air temperature as the core parameter. The PLC controller controls the opening of two valves in stages according to the intake air temperature: in the 0℃~-10℃ range, only the flue gas bypass valve is adjusted; in the -10℃~-20℃ range, the booster air return valve is adjusted in addition to the intake air temperature. This invention can suppress combustion deterioration caused by excessive intake air density at low temperatures without preheating the intake air, avoiding preheating energy consumption and power loss. The dual-valve staged control improves the stability of main engine operation, has low modification difficulty, and is suitable for the cryogenic navigation requirements of container ship fleets.

Description

Technical Field

[0001] This invention relates to the field of marine main engine air intake system technology, specifically to a cryogenic system for direct external air intake of the main engine and its control method. Background Technology

[0002] Currently, most large container ships use direct air intake from outside the ship. Compared to the traditional forced ventilation mode in the engine room, this method can directly introduce colder outside air when the ambient temperature is above 0°C, thereby increasing the oxygen content of the intake air, optimizing the combustion efficiency of the main engine, and reducing fuel consumption. It has significant energy-saving and economic advantages.

[0003] However, under low-temperature navigation conditions, especially when ships are engaged in Arctic shipping or winter high-latitude navigation, the outside air intake temperature often drops below 0°C, and in extreme cases, it can be as low as -20°C or even lower. In low-temperature environments, air density increases significantly. If the original turbocharging intake logic is maintained, it will lead to an excess of air supply in the cylinders and a relatively lower fuel ratio, resulting in a prolonged combustion delay period, deteriorated combustion conditions, and ultimately a series of problems such as reduced main engine power output and decreased operational stability.

[0004] Currently, conventional solutions to the low-temperature air intake problem mainly fall into two categories: one is to add an intake preheating device to raise the intake temperature through electric heating or steam heat exchange. This method requires a large amount of additional energy, and the high energy consumption of preheating offsets the energy-saving benefits of direct air intake from outside the ship. The other is to forcibly reduce the main engine operating power by reducing the fuel injection volume to match the excessive intake volume. This method directly limits the ship's speed, lengthens the sailing cycle, and seriously affects the ship's operating efficiency. In addition, the existing single-stage exhaust bypass regulation scheme has limited adjustment range under extreme low-temperature conditions, making it difficult to accurately match the intake demand. Moreover, it is prone to turbocharger stall, surge, and other failures during the switching of operating conditions, resulting in insufficient operational reliability.

[0005] Therefore, it is necessary to provide a cryogenic system for direct external air intake of the main engine and its control method to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a cryogenic system for direct external air intake of a main engine and its control method. Through a dual-valve graded control strategy, the system can accurately match the main engine air intake requirements under different cryogenic conditions without the need for preheating the air intake or reducing the rated power of the main engine, effectively solving the problem of combustion deterioration caused by excessive direct external air intake density in cryogenic environments.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A cryogenic system for direct outboard air intake of a main engine includes a main engine, a turbocharger assembly, an intake manifold, an intake return pipe, an exhaust manifold, an exhaust bypass pipe, an air cooler, a PLC controller, an electric flue gas bypass valve, and an electric booster air return valve. The turbocharger assembly includes a turbine and a compressor. The compressor is connected in series to the intake manifold, and the turbine is connected in series to the exhaust manifold. The compressor's intake end is connected to the outboard atmosphere, and its outlet end is connected to the air cooler's inlet. The air cooler's outlet end is connected to the main engine's air manifold. The two ends of the intake return pipe are respectively connected to the compressor's intake manifold at the compressor's inlet end and the compressor's outlet manifold at the compressor's outlet end. The electric booster air return valve is equipped with... The compressor intake return pipe is fitted with an electric flue gas bypass valve to return pressurized air to the upstream pipeline of the compressor intake. The turbine intake is connected to the exhaust gas collection pipe of the main engine, and the turbine outlet is connected to the outside atmosphere. The two ends of the exhaust gas bypass pipe are connected to the exhaust gas main pipe of the turbine intake and the exhaust gas main pipe of the turbine outlet, respectively. The electric flue gas bypass valve is fitted on the exhaust gas bypass pipe to bypass part of the exhaust gas around the turbine. A temperature sensor is installed in the intake main pipe upstream of the compressor intake. The PLC controller is electrically connected to the temperature sensor, the electric flue gas bypass valve, and the electric pressurized air return valve, respectively, to receive the intake temperature signal detected by the temperature sensor and to adjust the valve opening of the electric flue gas bypass valve and the electric pressurized air return valve according to the intake temperature.

[0009] Preferably, both the electric flue gas bypass valve and the electric booster air return valve are electric regulating valves.

[0010] A control method for a direct external air intake cryogenic system for a main engine includes the following steps:

[0011] S1. Real-time temperature acquisition: The external air temperature in the air intake manifold is continuously acquired by the temperature acquisition device and the real-time temperature signal is transmitted to the PLC controller.

[0012] S2, graded opening control:

[0013] S21. When the intake air temperature is higher than 0℃, the PLC controller controls both the electric flue gas bypass valve and the electric booster air return valve to remain fully closed, and the system maintains normal booster intake conditions.

[0014] S22. When the intake air temperature is between 0℃ and -5℃, the PLC controller controls the electric flue gas bypass valve to open halfway, so that some exhaust gas bypasses the turbine through the exhaust gas bypass pipe, thereby reducing the operating speed of the turbocharger assembly.

[0015] S23. When the intake air temperature is between -5℃ and -10℃, the PLC controller controls the electric flue gas bypass valve to be fully opened, so that more exhaust gas bypasses the turbine through the exhaust gas bypass pipe, increasing the exhaust gas bypass flow and further reducing the operating speed of the turbocharger assembly.

[0016] S24. When the intake air temperature is between -10℃ and -15℃, while keeping the electric flue gas bypass valve fully open, the PLC controller controls the electric booster air return valve to be half open, so that part of the booster air flows back to the upstream pipeline of the compressor intake end through the intake return pipe, reducing the effective intake air volume entering the main unit.

[0017] S25. When the intake air temperature is between -15℃ and -20℃, while keeping the electric flue gas bypass valve fully open, the PLC controller controls the electric booster air return valve to be fully open, so that more booster air flows back to the upstream of the compressor intake end through the intake return pipe, further reducing the effective intake air volume entering the main unit, maximizing the return flow of booster air, and accurately matching the combustion requirements of the main unit under extreme low temperature conditions.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. Energy-saving and efficient: The system does not require an additional intake preheating device. It can suppress combustion deterioration and power reduction caused by excessive intake density in low-temperature environments by regulating the exhaust gas bypass and air recirculation through dual valves. It completely avoids preheating energy consumption and does not require reducing the rated power of the main engine, thus ensuring the ship's navigation efficiency and showing significant economic advantages.

[0020] 2. Precise and reliable control: Adopting a dual-valve graded control strategy, the valve opening is adjusted in stages according to different low temperature ranges, which can realize continuous and precise control of the intake air volume, smooth switching of operating conditions, effectively avoid the turbocharger from stalling, surging and other faults, and greatly improve the operating stability of the main unit under low temperature conditions.

[0021] 3. Low modification cost and easy to promote: This invention is based on the modification of the existing ship pressurization system. It only requires the addition of an exhaust bypass pipe, an intake return pipe and corresponding electric control valves. The structure is simple and compact, without the need for major changes to the main engine. It has high reliability and low modification cost, and is easy to promote and apply in the existing container ship fleet, with good market prospects. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the structural principle of the main engine external direct air intake cryogenic system of the present invention;

[0023] Among them, 1-Main unit, 2-Intake main pipe, 3-Intake return pipe, 4-Exhaust gas main pipe, 5-Exhaust gas bypass pipe, 6-Air cooler, 7-PLC controller, 8-Electric flue gas bypass valve, 9-Electric booster air return valve, 10-Turbine, 11-Compressor, 12-Air collection pipe, 13-Exhaust gas collection pipe, 14-Temperature acquisition device Detailed Implementation

[0024] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and not for limiting the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0025] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixed connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] In this invention, terms such as "upper," "lower," "bottom," and "top" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements of this invention, and do not specifically refer to any component or element in this invention, and should not be construed as limiting this invention.

[0027] like Figure 1 As shown, this invention provides a cryogenic system for direct outboard air intake of a main engine, which is used in conjunction with a ship's main engine system employing direct outboard air intake mode. The core components of the system include a main engine 1, a turbocharger assembly, an intake manifold 2, an intake return pipe 3, an exhaust manifold 4, an exhaust bypass pipe 5, an air cooler 6, a PLC controller 7, an electric flue gas bypass valve 8, and an electric booster air return valve 9. The turbocharger assembly consists of a coaxially linked turbine 10 and a compressor 11. The compressor is connected in series on the intake manifold, and the turbine is connected in series on the exhaust manifold. The exhaust gas discharged from the main engine drives the turbine to rotate, which in turn drives the coaxially connected compressor to operate synchronously, thereby pressurizing the intake airflow.

[0028] The airflow path on the intake side is as follows: Outside air is drawn into the intake manifold, pressurized by the compressor, and then cooled by the air cooler. The cooled pressurized air then flows into the air collection pipe 12 of the main engine 1, and is finally evenly distributed into each cylinder of the main engine to participate in combustion and power generation. An intake return pipe is installed across the intake manifold on the compressor intake side and the exhaust side. An electric pressurized air return valve is connected in series in the intake return pipe. When the valve is open, some of the air pressurized by the compressor can return to the upstream position of the compressor intake end through the intake return pipe, thereby directly reducing the effective total intake air volume sent to the main engine cylinders. A temperature sensor 14 is installed inside the intake manifold upstream of the compressor intake end to detect the actual temperature of the outside air directly entering in real time, and converts the collected temperature signal into a standard electrical signal to be transmitted to the PLC controller.

[0029] The airflow path on the exhaust side is as follows: the high-temperature exhaust gas discharged from each cylinder of the main engine flows into the exhaust gas collection pipe 13, then enters the exhaust gas main pipe and flows through the turbine. After using the exhaust gas energy to drive the turbine to do work, it is finally discharged to the outside atmosphere. An exhaust gas bypass pipe is installed between the exhaust gas main pipe on the turbine's inlet side and outlet side. An electric flue gas bypass valve is installed in series in the exhaust gas bypass pipe. When the valve is open, some of the main engine exhaust gas can bypass the turbine directly through the exhaust gas bypass pipe, reducing the exhaust gas energy driving the turbine's operation, thereby reducing the overall operating speed of the turbocharger and correspondingly reducing the compressor's boost intake volume.

[0030] The PLC controller, as the core of the entire system, is electrically connected to the temperature acquisition unit, the electric flue gas bypass valve, and the electric booster air return valve. It continuously receives real-time intake air temperature signals from the temperature acquisition unit and, based on internally preset temperature range control logic, outputs corresponding opening adjustment signals to precisely control the opening degree of the two valves. This ultimately achieves optimal matching between the main engine intake air volume and fuel injection volume under different low-temperature operating conditions. Both the electric flue gas bypass valve and the electric booster air return valve are electric proportional control valves, which can accurately respond to the analog control signals output by the PLC controller, achieving continuous stepless adjustment across the entire stroke range. This ensures the smoothness and accuracy of the intake air volume regulation process and avoids system fluctuations caused by sudden changes in operating conditions.

[0031] A control method based on the above-mentioned main engine external direct air intake cryogenic system includes the following steps;

[0032] S1. Real-time temperature acquisition: During system operation, the temperature acquisition unit continuously collects the external air intake temperature data in the air intake manifold and transmits the real-time temperature signal synchronously to the PLC controller. The PLC controller compares the real-time temperature value with the preset graded control threshold and automatically matches the corresponding control strategy.

[0033] S2, graded opening control:

[0034] S21. When the ship is sailing in a normal temperature environment and the intake air temperature is higher than 0℃, the intake air density is within the normal design range and no additional intake air volume adjustment is required. At this time, the PLC controller controls the electric flue gas bypass valve and the electric booster air return valve to remain fully closed. The booster operates under rated conditions, and the system maintains the normal booster intake mode, which fully ensures the combustion efficiency and power output of the main engine.

[0035] S22. When a ship enters a low-temperature navigation area and the intake air temperature drops to the range of 0°C to -5°C, the air density begins to increase as the temperature decreases. At this time, the PLC controller outputs a corresponding control signal to adjust the electric flue gas bypass valve to a half-open state. Some of the main engine exhaust gas bypasses the turbine through the exhaust gas bypass pipe and is discharged directly, reducing the exhaust gas energy driving the turbine. This causes the operating speed of the turbocharger assembly to decrease slightly, and the compressor's boost intake air volume decreases accordingly. This offsets the increase in air density caused by the low temperature, maintains a reasonable air-fuel ratio in the cylinder, and avoids deterioration of the combustion state.

[0036] S23. When the intake air temperature drops further to the range of -5℃ to -10℃, the low temperature intensifies and the air density increases further. Half-open exhaust bypass is no longer sufficient to meet the intake air control requirements. At this time, the PLC controller controls the electric flue gas bypass valve to be fully open, maximizing the exhaust gas bypass flow rate, further reducing the operating speed of the turbocharger components, significantly reducing the intake air volume of the compressor, continuously suppressing the combustion deterioration problem caused by excessively high intake air density, and ensuring stable power output of the main unit.

[0037] S24. When the intake air temperature drops below -10℃ and enters the extreme low temperature range, relying solely on exhaust gas bypass regulation is insufficient to meet the intake air volume control requirements. At this time, while keeping the electric flue gas bypass valve fully open, the PLC controller activates the electric booster air return valve for superimposed regulation. When the intake air temperature is between -10℃ and -15℃, the electric booster air return valve remains half-open, and some of the air boosted by the compressor flows back to the upstream pipeline of the compressor intake end through the intake return pipe, further reducing the effective intake air volume entering the main unit and further adapting to the combustion requirements at even lower temperatures.

[0038] S25. When the intake air temperature drops to extreme low temperature conditions of -15℃ to -20℃, the PLC controller controls the electric booster air return valve to fully open, maximizing the return flow of boosted air and minimizing the effective intake air volume sent to the main unit. This ensures that the intake air volume is precisely matched with the fuel injection volume of the main unit, guaranteeing stable combustion and power output of the main unit under extreme low temperature conditions. At the same time, the smooth staged adjustment logic can prevent the booster from stalling, surging, or other malfunctions due to sudden changes in operating conditions, thus improving the reliability of system operation.

[0039] This system is widely adaptable to various container ship main engines that employ direct outboard air intake, including 14,000 TEU large container ship main engines, 3,600 TEU container ship main engines, and their associated generator systems. It is particularly suitable for extreme low-temperature navigation scenarios, such as winter navigation in the Arctic, where outboard air intake temperatures can drop to below -20°C. The system is based on the existing pressurization piping of the ship and requires no modifications to the main engine or the main structure of the pressurizer. The modification work is minimal and the cost is low, allowing for rapid deployment and mass application in existing fleets.

[0040] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A cryogenic system for direct external air intake of a main engine, characterized in that: The system includes a main engine, a turbocharger assembly, an intake manifold, an intake return pipe, an exhaust manifold, an exhaust bypass pipe, an air cooler, a PLC controller, an electric flue gas bypass valve, and an electric booster air return valve. The turbocharger assembly comprises a turbine and a compressor. The compressor is connected in series to the intake manifold, and the turbine is connected in series to the exhaust manifold. The compressor's intake end connects to the outside atmosphere, and its outlet end connects to the air cooler's inlet. The air cooler's outlet end connects to the main engine's air collection pipe. The intake return pipe connects to the compressor's intake manifold at its inlet end and the compressor's outlet manifold at its outlet end, respectively. The electric booster air return valve is equipped with... The compressor intake return pipe is fitted with an electric flue gas bypass valve to return pressurized air to the upstream pipeline of the compressor intake. The turbine intake is connected to the exhaust gas collection pipe of the main engine, and the turbine outlet is connected to the outside atmosphere. The two ends of the exhaust gas bypass pipe are connected to the exhaust gas main pipe of the turbine intake and the exhaust gas main pipe of the turbine outlet, respectively. The electric flue gas bypass valve is fitted on the exhaust gas bypass pipe to bypass part of the exhaust gas around the turbine. A temperature sensor is installed in the intake main pipe upstream of the compressor intake. The PLC controller is electrically connected to the temperature sensor, the electric flue gas bypass valve, and the electric pressurized air return valve, respectively, to receive the intake temperature signal detected by the temperature sensor and to adjust the valve opening of the electric flue gas bypass valve and the electric pressurized air return valve according to the intake temperature.

2. The main engine external direct air intake cryogenic system according to claim 1, characterized in that: Both the electric flue gas bypass valve and the electric booster air return valve are electric regulating valves.

3. A control method based on the main engine external direct air intake cryogenic system as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Real-time temperature acquisition: The external air temperature in the air intake manifold is continuously acquired by the temperature acquisition device and the real-time temperature signal is transmitted to the PLC controller. S2, graded opening control: S21. When the intake air temperature is higher than 0℃, the PLC controller controls both the electric flue gas bypass valve and the electric booster air return valve to remain fully closed, and the system maintains normal booster intake conditions. S22. When the intake air temperature is between 0℃ and -5℃, the PLC controller controls the electric flue gas bypass valve to open halfway, so that some exhaust gas bypasses the turbine through the exhaust gas bypass pipe, thereby reducing the operating speed of the turbocharger assembly. S23. When the intake air temperature is between -5℃ and -10℃, the PLC controller controls the electric flue gas bypass valve to be fully opened, so that more exhaust gas bypasses the turbine through the exhaust gas bypass pipe, increasing the exhaust gas bypass flow and further reducing the operating speed of the turbocharger assembly. S24. When the intake air temperature is between -10℃ and -15℃, while keeping the electric flue gas bypass valve fully open, the PLC controller controls the electric booster air return valve to be half open, so that part of the booster air flows back to the upstream pipeline of the compressor intake end through the intake return pipe, reducing the effective intake air volume entering the main unit. S25. When the intake air temperature is between -15℃ and -20℃, while keeping the electric flue gas bypass valve fully open, the PLC controller controls the electric booster air return valve to be fully open, so that more booster air flows back to the upstream of the compressor intake end through the intake return pipe, further reducing the effective intake air volume entering the main unit, maximizing the return flow of booster air, and accurately matching the combustion requirements of the main unit under extreme low temperature conditions.

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