A seawater self-circulation system that meets the idling speed requirements of marine diesel engines when out of water

Abstract

This invention discloses a seawater self-circulation system that meets the requirements of marine diesel engines operating at idling speed away from water. It relates to diesel engine cooling technology and includes a heat exchanger and a seawater pump. It also includes a seawater storage tank, an outboard cooler, a bypass valve, and a control module. The seawater outlet of the heat exchanger is connected to both the outboard cooler and a seawater discharge pipe via the bypass valve. The outboard cooler is connected to the seawater storage tank, which is connected to the heat exchanger via the seawater pump. The control module determines the operating condition of the diesel engine. If the diesel engine is operating at idling speed away from water, it controls the bypass valve to form a seawater self-circulation loop between the heat exchanger, outboard cooler, seawater storage tank, and seawater pump. Otherwise, it controls the bypass valve to directly connect the seawater outlet of the heat exchanger to the seawater discharge pipe. This invention ensures a good heat exchange temperature difference in the heat exchanger under idling speed conditions away from water, avoiding salt precipitation caused by excessively high seawater temperature in the self-circulation system.

Description

Technical Field

[0001] This invention relates to diesel engine cooling technology, and more specifically, to a seawater self-circulation system that meets the idling conditions of marine diesel engines when out of water. Background Technology

[0002] Marine diesel engines generate a large amount of heat during prolonged operation, causing excessively high engine temperatures and even engine failure and shutdown, severely impacting engine life and normal operation. Therefore, marine diesel engine cooling systems typically utilize seawater pumps to pump seawater into heat exchangers to cool the closed freshwater cooling system and other accessories.

[0003] like Figure 1 The traditional marine diesel engine seawater cooling solution involves seawater entering through the seawater pump inlet 3 and then entering the heat exchanger 1 through the seawater pump outlet 4 to cool the freshwater in the closed freshwater cooling system. The heat exchanger 1 has different outlets to divert the seawater to the diesel engine accessories that need cooling, such as the intercooler and oil cooler. After cooling is completed, the seawater finally flows into the sea through the seawater outlet 5 of the heat exchanger 1.

[0004] When the ship's draft is shallow, the diesel engine of the rubber impeller seawater pump is required to have the ability to idle at a speed away from the water. However, when the rubber impeller in the seawater pump is in the absence of seawater, the rubber impeller in the pump will dry-rub against the casing, which can easily cause the rubber impeller to burn out and stick to the casing, resulting in damage and failure of the cooling system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a seawater self-circulation system that meets the requirements of marine diesel engine idling conditions when it is out of water, thereby ensuring good heat exchange temperature difference of the heat exchanger under idling conditions and avoiding salt precipitation caused by excessively high seawater temperature in the self-circulation system.

[0006] The present invention provides a seawater self-circulation system for meeting the idling speed condition of a marine diesel engine when out of water, comprising a heat exchanger and a seawater pump; it also includes a seawater storage tank, an outboard cooler, a bypass valve, and a control module; the seawater outlet of the heat exchanger is connected to both the outboard cooler and the seawater discharge pipe through the bypass valve, the outboard cooler is connected to the seawater storage tank, and the seawater storage tank is connected to the heat exchanger through the seawater pump;

[0007] The control module determines the operating condition of the diesel engine; if the operating condition of the diesel engine is the off-water idling condition, it controls the bypass valve to make the heat exchanger, outboard cooler, seawater storage tank and seawater pump form a seawater self-circulation loop; otherwise, it controls the bypass valve to make the seawater outlet from the heat exchanger directly connected to the seawater discharge pipe.

[0008] As a further improvement, the control module is electrically connected to a water depth monitoring module.

[0009] Furthermore, the water depth monitoring module sends the collected water depth signal to the control module, which compares the water depth signal with a preset water depth threshold. When the water depth signal is less than the water depth threshold and the duration of the water depth signal being less than the water depth threshold is greater than or equal to a preset time threshold, it is determined to be an off-water idling condition.

[0010] Furthermore, the water depth threshold is 20-40m; the time threshold is 5-10s.

[0011] As a further improvement, when the diesel engine is operating at idle speed away from water, the control module simultaneously collects the seawater inlet temperature T of the heat exchanger through the temperature monitoring module. in-sea Seawater outlet temperature T out-sea and inlet cooling water temperature T in And based on the seawater inlet temperature T in-sea Seawater outlet temperature T out-sea and inlet cooling water temperature T in Control the seawater pump to change the flow rate of seawater entering the heat exchanger.

[0012] Furthermore, based on the seawater inlet temperature T in-sea Seawater outlet temperature T out-sea and inlet cooling water temperature T in Controlling the seawater pump to change the flow rate of seawater entering the heat exchanger specifically includes:

[0013] According to the seawater inlet temperature T in-sea and inlet cooling water temperature T in Obtain the heat exchange temperature difference ΔT; determine whether the heat exchange temperature difference ΔT is within the set temperature difference threshold range. If so, control the seawater pump to maintain the current seawater output discharge rate; otherwise, determine whether the heat exchange temperature difference ΔT is greater than the maximum value of the temperature difference threshold range. If so, control the seawater pump to reduce the seawater output discharge rate until the heat exchange temperature difference ΔT is within the temperature difference threshold range; otherwise, control the seawater pump to increase the seawater output discharge rate until the heat exchange temperature difference ΔT is within the temperature difference threshold range.

[0014] According to the seawater outlet temperature T out-sea To determine whether the seawater temperature after heat exchange meets the temperature requirements, if the seawater outlet temperature T... out-sea If the seawater temperature exceeds the preset target discharge temperature, the seawater pump is controlled to increase the seawater output discharge rate until the seawater outlet temperature T is reached. out-sea It is lower than the target drainage temperature.

[0015] Furthermore, when the heat exchange temperature difference ΔT is not within the temperature difference threshold range, the current heat exchange temperature difference ΔT is recorded. And when the seawater output displacement of the seawater pump makes the heat exchange temperature difference ΔT within the temperature difference threshold range, the current seawater output displacement of the seawater pump is recorded. The current heat exchange temperature difference ΔT and the current seawater output displacement are stored as the first preset data.

[0016] Furthermore, when the heat exchange temperature difference ΔT obtained by the control module is the same as the heat temperature difference ΔT in the stored first preset data, the seawater output displacement in the first preset data is retrieved as the current displacement of the seawater pump.

[0017] Furthermore, when the seawater outlet temperature T out-sea When the temperature exceeds the preset target discharge temperature, record the current seawater outlet temperature T. out-sea Furthermore, the seawater output discharge rate of the seawater pump causes the seawater outlet temperature T to... out-sea When the temperature is lower than the target discharge temperature, record the current seawater output discharge rate of the seawater pump and set the current seawater outlet temperature T. out-sea The current seawater output displacement is stored as the second preset data.

[0018] Furthermore, when the control module obtains the seawater outlet temperature T out-sea When the temperature difference ΔT is the same as that in the stored second preset data, the seawater output displacement in the second preset data is retrieved as the current displacement of the seawater pump.

[0019] Beneficial effects

[0020] The advantages of this invention are:

[0021] 1. The marine diesel engine's seawater self-circulation system for idling off-water operation monitors seawater depth in real time through a water depth monitoring module, enabling the judgment and switching of idling off-water operation. It is equipped with inlet and outlet temperature monitoring modules for the heat exchanger. After processing and analysis by the control module, the seawater pump displacement is adjusted to ensure good heat exchange temperature difference in the heat exchanger under idling off-water operation, thus avoiding salt precipitation caused by excessively high seawater temperature in the self-circulation system.

[0022] 2. Based on the traditional seawater cooling system, this invention innovatively adds a bypass valve, a check valve, and an external cooler to construct a seawater self-circulation system that meets the idling conditions of marine diesel engines when out of water, ensuring the normal operation of the rubber impeller in the seawater pump and the diesel engine under idling conditions. Furthermore, the addition of the external cooler prevents the seawater in the self-circulation system from becoming excessively hot due to prolonged heat exchange. Attached Figure Description

[0023] Figure 1 A schematic diagram of a traditional marine diesel engine seawater cooling heat exchanger.

[0024] Figure 2 This is a schematic diagram of the seawater self-circulation system of the present invention;

[0025] Figure 3 This is a schematic diagram of the working process of the seawater self-circulation system of the present invention.

[0026] Wherein: 1-heat exchanger, 2-seawater pump, 3-seawater pump inlet, 4-seawater pump outlet, 5-seawater outlet. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0028] See Figures 2-3 This invention discloses a seawater self-circulation system for marine diesel engines operating at idle speed away from water. The system includes a heat exchanger and seawater pump, a seawater storage tank, an outboard cooler, a bypass valve, a temperature monitoring module, a water depth monitoring module, and a control module. The seawater outlet of the heat exchanger is connected to both the outboard cooler and a seawater discharge pipe via the bypass valve. The outboard cooler is connected to the seawater storage tank, which is connected to the heat exchanger via the seawater pump. The seawater storage tank draws seawater from the ocean via a water intake pump and a water intake pipe. A check valve is installed in the water intake pipe to prevent backflow of seawater from the storage tank into the ocean.

[0029] In this embodiment, a variable frequency seawater pump is used. The main function of the seawater pump is to draw in and pump out seawater. By pumping seawater, the pump cools the diesel engine's accessories and the freshwater in the closed freshwater cooling system, thereby ensuring the normal operation of the diesel engine's cooling system. The variable frequency seawater pump utilizes variable frequency control technology to regulate and control the water flow rate.

[0030] The main function of a heat exchanger is to transfer heat from a hot fluid to a cold fluid, thereby cooling the hot fluid. Marine heat exchangers are generally shell-and-tube type, and this invention does not modify them.

[0031] The bypass valve is a crucial component in the closed loop of a seawater self-circulation system. Its primary function is to control the direction and flow rate of fluid. The principle involves installing a bypass in the fluid pipeline; by adjusting the bypass valve, all or part of the fluid can be directed to the bypass. Furthermore, it can regulate the fluid flow rate to the desired range. An innovative electrically controlled bypass valve is added at the seawater outlet of the heat exchanger. When the vessel is out of water or in shallow draft, the bypass valve opens, closing the passage to the sea, and seawater flows into the seawater storage tank through the bypass valve.

[0032] The check valve is one of the important components in forming a closed loop for seawater self-circulation. The main function of the check valve is to prevent fluid backflow, thereby forming a closed seawater circulation loop.

[0033] Under idling conditions away from water, closed-loop seawater is prone to salt precipitation due to excessively high temperature. The outboard cooler is directly installed on the outside of the hull below the waterline of the ship. It relies on the temperature difference between the high-temperature seawater in the circulation system and the water outside the hull, as well as the relative speed between the water and the hull during the ship's navigation, to remove the heat from the high-temperature seawater in the circulation system, thereby achieving the purpose of normal operation of the cooling system.

[0034] The temperature monitoring module is divided into a heat exchanger inlet temperature monitoring module and a heat exchanger outlet temperature monitoring module, used to monitor the cooling water and seawater temperature information in real time. The heat exchanger inlet temperature monitoring module is used to monitor the seawater inlet temperature T of the heat exchanger. in-sea With cooling water inlet temperature T in The heat exchanger outlet temperature monitoring module is used to monitor the seawater outlet temperature T of the heat exchanger. out-sea .

[0035] The water depth monitoring module is used to monitor seawater depth in real time. In this embodiment, when the seawater depth is less than 30m and the time is greater than or equal to 5s, the vessel is considered to be in an out-of-water idling state.

[0036] The control module is a key component ensuring the normal operation of the diesel engine cooling system under off-water idling conditions. Its main functions include: determining the diesel engine's operating condition based on water depth signals from the water depth monitoring module and timing data; if the diesel engine is operating under off-water idling conditions, controlling the bypass valve to create a seawater self-circulation loop between the heat exchanger, outboard cooler, seawater tank, and seawater pump; otherwise, controlling the bypass valve to directly connect the seawater outlet of the heat exchanger to the seawater discharge pipe, meaning seawater is drawn from the ocean, passes through the heat exchanger, and is directly discharged back into the ocean. Simultaneously, the control module monitors the temperature of the heat exchange fluid and controls the seawater pump's discharge rate by adjusting the pump speed, thereby ensuring good heat exchange in the heat exchanger and preventing seawater salt precipitation.

[0037] The control module monitors the temperature of the heat exchange fluid and controls the seawater pump, as follows: Figure 3 As shown.

[0038] The water depth monitoring module monitors the seawater depth. When the seawater depth is less than 30m and the time is greater than or equal to 5s, it is considered that the ship is in an out-of-water idling condition. At this time, the control module controls the bypass valve to open. Conversely, when the water depth is less than 30m and the time is greater than or equal to 5s, the bypass valve will not be opened.

[0039] The temperature monitoring module monitors the temperature of the heat exchange fluid in real time and obtains the seawater inlet temperature T. in-sea Inlet cooling water temperature T in and seawater outlet temperature Tout-sea Among them, the inlet cooling water temperature T in -Seawater inlet temperature T in-sea = Heat exchange temperature difference ΔT. Determine whether the heat exchange temperature difference ΔT is within the range of 50℃-60℃. If it is within this range, maintain the current discharge rate of the seawater pump; if it does not meet the temperature difference range, continue to determine whether the heat exchange temperature difference ΔT is too large.

[0040] The system determines whether the heat exchange temperature difference ΔT is greater than the maximum value of the temperature difference threshold range, i.e., whether ΔT is greater than 60℃. If so, the control module reduces the discharge rate of the seawater pump, thereby increasing the seawater outlet temperature T. out-sea This reduces the heat exchange temperature difference ΔT; if the heat exchange temperature difference ΔT is too small, i.e., ΔT is less than 50℃, the control module increases the discharge rate of the seawater pump, thereby reducing the seawater outlet temperature T. out-sea This increases the heat exchange temperature difference ΔT. Furthermore, during the process of adjusting the seawater pump discharge rate described above, this continues until the heat exchange temperature difference ΔT is adjusted to within the temperature difference threshold range.

[0041] Based on the seawater outlet temperature T out-sea Determine if the seawater temperature meets the requirements. When the seawater outlet temperature T... out-sea When the temperature exceeds 50℃, seawater will undergo salt precipitation. Prolonged exposure to this temperature will severely impair the normal operation of the cooling system. When the seawater outlet temperature T... out-sea At temperatures below 50℃, the risk of salt precipitation is low, and both the heat exchange temperature difference and the outlet seawater temperature meet the requirements. Therefore, if the seawater outlet temperature T... out-sea At temperatures above 50℃, the risk of salt precipitation is high. In this case, it is necessary to control the seawater pump to increase the seawater output flow rate, thereby reducing the outlet seawater temperature until the outlet seawater temperature T is reached. out-sea Below 50℃.

[0042] When the heat exchange temperature difference ΔT is not within the temperature difference threshold range, the current heat exchange temperature difference ΔT is recorded. Conversely, when the seawater output displacement of the seawater pump brings the heat exchange temperature difference ΔT within the temperature difference threshold range, the current seawater output displacement of the seawater pump is recorded. These two values ​​are stored as the first preset data. In subsequent operations, when the heat exchange temperature difference ΔT obtained by the control module matches the heat exchange temperature difference ΔT in the stored first preset data, the seawater output displacement from the first preset data is retrieved as the current displacement of the seawater pump. This significantly improves the efficiency of seawater temperature adjustment.

[0043] Similarly, when the seawater outlet temperature T out-sea When the temperature is greater than 50℃, record the current seawater outlet temperature T. out-sea Furthermore, the seawater output displacement of the seawater pump causes the seawater outlet temperature T to... out-seaWhen the temperature is below 50℃, record the current seawater output discharge of the seawater pump and set the current seawater outlet temperature T. out-sea The current seawater discharge rate is stored as the second preset data. During subsequent operation, when the control module acquires the seawater outlet temperature T... out-sea When the temperature difference ΔT is the same as that in the stored second preset data, the seawater output displacement in the second preset data is retrieved as the current displacement of the seawater pump.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A seawater self-circulation system for meeting the idling speed requirements of marine diesel engines when out of water, comprising a heat exchanger and a seawater pump; characterized in that, It also includes a seawater storage tank, an outboard cooler, a bypass valve, and a control module; the seawater outlet of the heat exchanger is connected to both the outboard cooler and the seawater discharge pipe through the bypass valve, the outboard cooler is connected to the seawater storage tank, and the seawater storage tank is connected to the heat exchanger through a seawater pump. The control module determines the operating condition of the diesel engine; if the operating condition of the diesel engine is the off-water idling condition, it controls the bypass valve to make the heat exchanger, outboard cooler, seawater storage tank and seawater pump form a seawater self-circulation loop; otherwise, it controls the bypass valve to make the seawater outlet of the heat exchanger directly connected to the seawater discharge pipe. The control module is electrically connected to a water depth monitoring module; The water depth monitoring module sends the collected water depth signal to the control module. The control module compares the water depth signal with a preset water depth threshold. When the water depth signal is less than the water depth threshold and the duration of the water depth signal being less than the water depth threshold is greater than or equal to a preset time threshold, it is determined to be an idling condition away from water. The water depth threshold is 20-40m; the time threshold is 5-10s.

2. The seawater self-circulation system according to claim 1, which satisfies the idling speed condition of a marine diesel engine when out of water, is characterized in that, When the diesel engine is operating at idle speed away from water, the control module simultaneously collects the seawater inlet temperature T of the heat exchanger through the temperature monitoring module. in-sea Seawater outlet temperature T out-sea and inlet cooling water temperature T in And based on the seawater inlet temperature T in-sea Seawater outlet temperature T out-sea and inlet cooling water temperature T in Control the seawater pump to change the flow rate of seawater entering the heat exchanger.

3. A seawater self-circulation system for meeting the idling speed condition of a marine diesel engine when out of water, as described in claim 2, is characterized in that... According to the seawater inlet temperature T in-sea Seawater outlet temperature T out-sea and inlet cooling water temperature T in Controlling the seawater pump to change the flow rate of seawater entering the heat exchanger specifically includes: According to the seawater inlet temperature T in-sea and inlet cooling water temperature T in Obtain the heat exchange temperature difference ΔT; determine whether the heat exchange temperature difference ΔT is within the set temperature difference threshold range. If so, control the seawater pump to maintain the current seawater output discharge rate; otherwise, determine whether the heat exchange temperature difference ΔT is greater than the maximum value of the temperature difference threshold range. If so, control the seawater pump to reduce the seawater output discharge rate until the heat exchange temperature difference ΔT is within the temperature difference threshold range; otherwise, control the seawater pump to increase the seawater output discharge rate until the heat exchange temperature difference ΔT is within the temperature difference threshold range. According to the seawater outlet temperature T out-sea To determine whether the seawater temperature after heat exchange meets the temperature requirements, if the seawater outlet temperature T... out-sea If the seawater temperature exceeds the preset target discharge temperature, the seawater pump is controlled to increase the seawater output discharge rate until the seawater outlet temperature T is reached. out-sea It is lower than the target drainage temperature.

4. A seawater self-circulation system for meeting the idling speed condition of a marine diesel engine when out of water, as described in claim 3, is characterized in that... When the heat exchange temperature difference ΔT is not within the temperature difference threshold range, the current heat exchange temperature difference ΔT is recorded. And when the seawater output displacement of the seawater pump makes the heat exchange temperature difference ΔT within the temperature difference threshold range, the current seawater output displacement of the seawater pump is recorded. The current heat exchange temperature difference ΔT and the current seawater output displacement are stored as the first preset data.

5. A seawater self-circulation system according to claim 4 that satisfies the idling speed condition of a marine diesel engine when out of water, characterized in that, When the heat exchange temperature difference ΔT obtained by the control module is the same as the heat temperature difference ΔT in the stored first preset data, the seawater output displacement in the first preset data is retrieved as the current displacement of the seawater pump.

6. A seawater self-circulation system for meeting the idling speed condition of a marine diesel engine when out of water, as described in claim 3, is characterized in that... When the seawater outlet temperature T out-sea When the temperature exceeds the preset target discharge temperature, record the current seawater outlet temperature T. out-sea Furthermore, the seawater output discharge rate of the seawater pump causes the seawater outlet temperature T to... out-sea When the temperature is lower than the target discharge temperature, record the current seawater output discharge rate of the seawater pump and set the current seawater outlet temperature T. out-sea The current seawater output displacement is stored as the second preset data.

7. A seawater self-circulation system according to claim 6 that satisfies the idling speed condition of a marine diesel engine when out of water, characterized in that, When the control module obtains the seawater outlet temperature T out-sea When the temperature difference ΔT is the same as that in the stored second preset data, the seawater output displacement in the second preset data is retrieved as the current displacement of the seawater pump.

Images