Seawater self-circulation system meeting off-water idling working condition of marine diesel engine

Abstract

The invention discloses a seawater self-circulation system meeting the off-water idling working condition of a marine diesel engine, and relates to the diesel engine cooling technology. The system further comprises a seawater storage tank, an outboard cooler, a bypass valve and a control module. A seawater outlet of the heat exchanger is simultaneously connected with an outboard cooler and a seawater discharge pipe through a bypass valve, the outboard cooler is connected with a seawater storage tank, and the seawater storage tank is connected with the heat exchanger through a seawater pump; the control module judges the working condition of the diesel engine; if the working condition of the diesel engine is the off-water idling condition, the bypass valve is controlled to enable the heat exchanger, the outboard cooler, the seawater storage tank and the seawater pump to form a seawater self-circulation loop; otherwise, the bypass valve is controlled so that the seawater outlet from the heat exchanger directly communicates with the seawater discharge pipe. Good heat exchange temperature difference of the heat exchanger under the off-water idling working condition is ensured, and the salting-out phenomenon caused by too high seawater temperature of the self-circulation system is avoided.

Description

Technical Field

[0001] The invention relates to a diesel engine cooling technology, and more specifically, to a seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water. Background Art

[0002] The long-term operation of marine diesel engines will generate a lot of heat, causing the engine temperature to be too high, and even causing the diesel engine to malfunction and shut down, seriously affecting the engine life and normal operation. Therefore, the marine diesel engine cooling system generally uses a seawater pump to pump seawater into the heat exchanger to achieve cooling of the closed fresh water cooling system and other accessories.

[0003] like Figure 1 This is a traditional marine diesel engine seawater cooling solution. After the seawater enters from the seawater pump inlet 3, it enters the heat exchanger 1 through the seawater pump outlet 4 to achieve cooling of the fresh water in the closed fresh water cooling system. There are different water outlets on the heat exchanger 1 to divert the seawater to the accessories of the diesel engine that need to be cooled, such as the intercooler, oil cooler, etc. After cooling, the seawater finally flows into the sea through the seawater outlet 5 of the heat exchanger 1.

[0004] The rubber impeller seawater pump marine diesel engine requires the diesel engine to have the ability to idle out of water when the ship is shallow in draft. However, in the absence of seawater, the rubber impeller in the rubber impeller seawater pump will rub against the casing, which can easily cause the rubber impeller to burn and adhere to the casing, causing damage to the cooling system and failure. Summary of the invention

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

[0006] The seawater self-circulating system that meets the out-of-water idling condition of a marine diesel engine described in the present invention comprises a heat exchanger and a seawater pump; further comprises a seawater storage tank, an outboard cooler, a bypass valve and a control module; the seawater outlet of the heat exchanger is connected to the outboard cooler and the seawater discharge pipe at the same time 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 working condition of the diesel engine; if the working condition of the diesel engine is the water-free idling condition, the bypass valve is controlled to allow the heat exchanger, the outboard cooler, the seawater storage tank and the seawater pump to form a seawater self-circulating loop; otherwise, the bypass valve is controlled to allow the seawater outlet from the heat exchanger to be 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, and 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 the preset time threshold, it is judged to be an out-of-water idle condition.

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

[0011] As a further improvement, when the diesel engine is operating in the water-free idling condition, 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 according to the seawater inlet temperature T in-sea , Seawater outlet temperature T out-sea and inlet cooling water temperature T in The seawater pump is controlled to vary the flow of seawater into the heat exchanger.

[0012] Further, according to 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 of seawater into the heat exchanger, including:

[0013] According to the seawater inlet temperature T in-sea , and inlet cooling water temperature T in Obtaining a heat exchange temperature difference ΔT; determining whether the heat exchange temperature difference ΔT is within a set temperature difference threshold range, and if so, controlling the seawater pump to maintain the current seawater output displacement; otherwise determining whether the heat exchange temperature difference ΔT is greater than a maximum value of the temperature difference threshold range, and if so, controlling the seawater pump to reduce the seawater output displacement until the heat exchange temperature difference ΔT is within the temperature difference threshold range; otherwise controlling the seawater pump to increase the seawater output displacement until the heat exchange temperature difference ΔT is within the temperature difference threshold range;

[0014] According to the seawater outlet temperature T out-sea Determine whether the seawater temperature after heat exchange meets the temperature requirements. If the seawater outlet temperature T out-sea If the temperature of the water discharge is greater than the preset target temperature, the seawater pump is controlled to increase the seawater output displacement until the seawater outlet temperature T out-sea Less than the target drain water 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, and the current heat exchange temperature difference ΔT and the current seawater output displacement are stored as first preset data.

[0016] Furthermore, when the heat exchange temperature difference ΔT acquired by the control module is the same as the heat exchange 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 it is greater than the preset target discharge temperature, record the current seawater outlet temperature T out-sea , and the seawater output displacement of the seawater pump makes the seawater outlet temperature T out-sea When the discharge temperature is lower than the target discharge temperature, the current seawater output displacement of the seawater pump is recorded, and 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 thermal temperature difference ΔT is the same as the thermal temperature difference ΔT 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 the present invention are:

[0021] 1. The seawater self-circulation system of the marine diesel engine in the idle condition out of water monitors the seawater depth in real time through the water depth monitoring module, realizing the judgment and switching of the idle condition out of water; the heat exchanger inlet temperature monitoring module and the outlet temperature monitoring module are set, and the seawater pump displacement is adjusted after processing and analysis by the control processing module to ensure that the heat exchange temperature difference of the heat exchanger is good under the idle condition out of water, avoiding the salt precipitation phenomenon caused by the excessively high seawater temperature in the self-circulation system.

[0022] 2. Based on the traditional seawater cooling system, the present invention innovatively adds a bypass valve, a check valve and an outboard cooler to construct a seawater self-circulating system that meets the idle working condition of the marine diesel engine out of water, ensuring the normal operation of the rubber impeller in the seawater pump and the diesel engine under the idle working condition. In addition, the addition of the outboard cooler prevents the seawater in the self-circulating system from being too hot due to long-term heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a traditional marine diesel engine seawater cooling heat exchanger;

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

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

[0026] Among them: 1-heat exchanger, 2-seawater pump, 3-seawater pump inlet, 4-seawater pump outlet, 5-seawater outlet. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0028] See also Figure 2-Figure 3 The present invention provides a seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water, including a heat exchanger and a 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 the outboard cooler and the seawater discharge pipe at the same time through the bypass valve, the outboard cooler is connected to the seawater storage tank, the seawater storage tank is connected to the heat exchanger through a seawater pump, the seawater storage tank takes seawater from the ocean through a water intake pump and a water intake pipe, and a check valve is installed in the water intake pipe to prevent the seawater in the seawater storage tank from flowing back to the ocean.

[0029] In this embodiment, the seawater pump is a variable frequency seawater pump. The main function of the seawater pump is to suck in and pump out seawater. The seawater pump cools the relevant accessories of the diesel engine and the fresh water in the closed fresh water cooling system by pumping in seawater, thereby ensuring the normal operation of the diesel engine cooling system. The variable frequency seawater pump uses seawater pump frequency conversion control technology to achieve regulation and control of the water volume pumped by the seawater pump.

[0030] The main function of the heat exchanger is to transfer the heat of the hot fluid to the cold fluid to achieve cooling of the hot fluid. The marine heat exchanger is generally a shell and tube heat exchanger, which is not improved by the present invention.

[0031] The bypass valve is one of the important components of the closed loop of the seawater self-circulation system. Its main function is to control the flow direction and flow rate of the fluid. The principle is to set a bypass in the fluid pipeline. By adjusting the bypass valve, the fluid can be controlled to flow to the bypass in whole or in part. In addition, it can adjust the fluid flow rate to the required range. An electrically controlled bypass valve is innovatively added to the seawater outlet of the heat exchanger. When the ship is out of water or has a shallow draft, the bypass valve opens to close the passage to the sea, and the seawater flows into the seawater storage tank through the bypass valve.

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

[0033] Under the idling condition out of water, the closed circulating seawater is prone to salt precipitation due to excessive temperature, while 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 and the outboard water in the circulation system and the relative speed of the water and the hull when the ship is sailing to take away the heat of the high-temperature seawater in the circulation system to achieve the purpose of normal operation of the cooling system.

[0034] The temperature monitoring module is divided into the heat exchanger inlet temperature monitoring module and the heat exchanger outlet temperature monitoring module, which are 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 heat exchanger seawater inlet temperature T in-sea and cooling water inlet temperature T in The heat exchanger outlet temperature monitoring module is used to monitor the heat exchanger seawater outlet temperature T out-sea .

[0035] The water depth monitoring module is used to monitor the sea depth in real time. In this embodiment, when the sea depth is less than 30m and the time is greater than or equal to 5s, it is considered that the ship is in the water idle condition.

[0036] The control module is a key core component to ensure the normal operation of the diesel engine cooling system under the condition of idle out of water. Its main functions are: judging the working condition of the diesel engine according to the water depth signal and timing of the water depth monitoring module; if the working condition of the diesel engine is idle out of water, the bypass valve is controlled to form a seawater self-circulating loop with the heat exchanger, outboard cooler, seawater storage tank and seawater pump; otherwise, the bypass valve is controlled to connect the seawater outlet from the heat exchanger directly with the seawater discharge pipe, that is, the seawater is extracted from the ocean and directly discharged back to the ocean after passing through the heat exchanger. At the same time, the control module also monitors the temperature of the heat exchange fluid and controls the displacement of the seawater pump by adjusting the speed of the seawater pump, thereby ensuring good heat exchange of the heat exchanger and avoiding salt precipitation of seawater.

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

[0038] The water depth monitoring module monitors the sea depth. When the sea depth is less than 30m and the time is greater than or equal to 5s, it is considered that the ship is in an idle condition out of water. At this time, the control module controls the bypass valve to open; otherwise, the diesel engine is in normal working condition and the bypass valve is not 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 the 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°C-60°C. If it is within the range, maintain the existing displacement state 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] It is determined whether the heat exchange temperature difference ΔT is greater than the maximum value of the temperature difference threshold range, that is, whether ΔT is greater than 60°C. If so, the control module controls the displacement of the seawater pump to decrease, thereby increasing the seawater outlet temperature T out-sea , reducing the heat exchange temperature difference ΔT; if the heat exchange temperature difference ΔT is too small, that is, ΔT is less than 50°C, the control module controls the displacement of the seawater pump to increase, thereby reducing the seawater outlet temperature T out-sea , increasing the heat exchange temperature difference ΔT. And in the above process of adjusting the seawater pump displacement, until the heat exchange temperature difference ΔT is adjusted to the temperature difference threshold range.

[0041] According to the seawater outlet temperature T out-sea Determine whether the seawater temperature meets the requirements. out-sea When the temperature exceeds 50℃, salt precipitation will occur in the seawater. If the temperature is kept at this level for a long time, it will seriously affect the normal operation of the cooling system. out-sea When the temperature is less than 50℃, the risk of salt precipitation is small, and the heat exchange temperature difference and the outlet seawater temperature meet the requirements. out-sea When the temperature is greater than 50℃, the risk of salt precipitation is high. At this time, the seawater pump needs to be controlled to increase the seawater output displacement, thereby reducing the outlet seawater temperature until the seawater outlet temperature T out-sea Less than 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, 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, and the current heat exchange temperature difference ΔT and the current seawater output displacement are stored as the first preset data. In the subsequent working process, 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, thereby greatly improving the efficiency of adjusting the seawater temperature.

[0043] Similarly, when the seawater outlet temperature T out-sea When it is greater than 50℃, record the current seawater outlet temperature T out-sea , and the seawater output displacement of the seawater pump makes the seawater outlet temperature T out-seaWhen the temperature is less than 50℃, record the current seawater output displacement of the seawater pump and the current seawater outlet temperature T out-sea and the current seawater output displacement as the second preset data. In the subsequent working process, when the control module obtains the seawater outlet temperature T out-sea When the thermal temperature difference ΔT is the same as the thermal temperature difference ΔT 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 is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A seawater self-circulating system that meets the idle working condition of a marine diesel engine 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 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 working condition of the diesel engine; if the working condition of the diesel engine is the water-free idling condition, the bypass valve is controlled to allow the heat exchanger, the outboard cooler, the seawater storage tank and the seawater pump to form a seawater self-circulating loop; otherwise, the bypass valve is controlled to allow the seawater outlet from the heat exchanger to be directly connected to the seawater discharge pipe.

2. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 1, characterized in that: The control module is electrically connected to a water depth monitoring module.

3. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 2, characterized in that: The water depth monitoring module sends the collected water depth signal to the control module, and 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 the preset time threshold, it is judged to be an out-of-water idle condition.

4. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 3, characterized in that: The water depth threshold is 20-40m; the time threshold is 5-10s.

5. The seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 1 is characterized in that: When the diesel engine is operating in the water-free idling condition, 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 according to the seawater inlet temperature T in-sea , Seawater outlet temperature T out-sea and inlet cooling water temperature T in The seawater pump is controlled to vary the flow of seawater into the heat exchanger.

6. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 5, 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 Control the seawater pump to change the flow of seawater into the heat exchanger, including: According to the seawater inlet temperature T in-sea , and inlet cooling water temperature T in Obtaining a heat exchange temperature difference ΔT; determining whether the heat exchange temperature difference ΔT is within a set temperature difference threshold range, and if so, controlling the seawater pump to maintain the current seawater output displacement; otherwise determining whether the heat exchange temperature difference ΔT is greater than a maximum value of the temperature difference threshold range, and if so, controlling the seawater pump to reduce the seawater output displacement until the heat exchange temperature difference ΔT is within the temperature difference threshold range; otherwise controlling the seawater pump to increase the seawater output displacement until the heat exchange temperature difference ΔT is within the temperature difference threshold range; According to the seawater outlet temperature T out-sea Determine whether the seawater temperature after heat exchange meets the temperature requirements. If the seawater outlet temperature T out-sea If the temperature of the water discharge is greater than the preset target temperature, the seawater pump is controlled to increase the seawater output displacement until the seawater outlet temperature T out-sea Less than the target drain water temperature.

7. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 6, 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, and the current heat exchange temperature difference ΔT and the current seawater output displacement are stored as first preset data.

8. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 7, characterized in that: When the heat exchange temperature difference ΔT acquired by the control module is the same as the heat exchange 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.

9. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 6, characterized in that: When the seawater outlet temperature T out-sea When it is greater than the preset target discharge temperature, record the current seawater outlet temperature T out-sea , and the seawater output displacement of the seawater pump makes the seawater outlet temperature T out-sea When the discharge temperature is lower than the target discharge temperature, the current seawater output displacement of the seawater pump is recorded, and the current seawater outlet temperature T out-sea The current seawater output displacement is stored as the second preset data.

10. A seawater self-circulating system that meets the idle working condition of a marine diesel engine out of water according to claim 9, characterized in that: When the control module obtains the seawater outlet temperature T out-sea When the thermal temperature difference ΔT is the same as the thermal temperature difference ΔT 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.

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