Condenser water supply control method based on seawater temperature

Abstract

The present invention discloses a condenser water supply control method based on seawater temperature, comprising the following steps: obtaining a lower threshold value and an upper threshold value of the seawater temperature as initial values; obtaining the ship's speed and the seawater temperature; determining whether to switch the water supply mode; when in the first water supply mode, obtaining the condenser pressure; calculating the intermediate value of the seawater temperature upper threshold value based on the condenser pressure value; determining whether the condenser pressure is greater than the preset working pressure of the condenser; if so, updating the seawater temperature upper threshold value according to a first preset formula; if not, updating the seawater temperature upper threshold value according to a second preset formula; updating the seawater temperature lower threshold value; and returning to the step of obtaining the ship's speed and the seawater temperature. The technical solution of the embodiment of the present invention can simply and reliably realize the switching of the condenser water supply mode, and can correct the seawater temperature threshold value during the operation of the ship, thus having good engineering practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of digital control of ships, and in particular to a condenser water supply control method based on seawater temperature. Background Art

[0002] Steam thermal systems convert primary energy sources such as fossil fuels, nuclear energy, and solar energy into secondary energy sources such as mechanical energy, electrical energy, and hot water. In the civilian sector, steam thermal systems provide process steam, thermal energy, and power to companies such as oil refining, heating, and power generation. In the military sector, steam power systems, diesel engine power systems, and gas turbine power systems are all forms of power for ships and are mainly used on large ships. The steam thermal system uses the steam Rankine cycle. The basic thermodynamic process is the absorption of heat energy, expansion work, condensation and exhaust steam, and pressurization of condensate. The cycle efficiency can be improved through steam reheating and steam heat recovery. Condensation and exhaust steam is the core link in completing the steam Rankine cycle. The steam that has been used for work is cooled by seawater through the condenser to remove the waste heat from the cycle.

[0003] Cycle efficiency is a key indicator influencing the economic viability of steam thermal systems. The condenser's operating status is dependent on factors such as seawater temperature, flow rate, and ship speed. To ensure stable turbine operation, the condenser pressure must remain within the design range. This requires either gravity diversion or circulating water pumps, depending on actual conditions. Determining the condenser water supply method is crucial for achieving precise control of steam thermal systems.

[0004] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a condenser water supply control method based on seawater temperature, which can simply and reliably realize the switching of the condenser water supply mode, and can correct the seawater temperature threshold during the operation of the ship, and has good engineering practicality.

[0006] To achieve the above-mentioned object, the present invention provides a condenser water supply control method based on seawater temperature, comprising: step S100, obtaining a lower threshold value and an upper threshold value of the seawater temperature as initial values; step S200, obtaining a ship speed and a seawater temperature; step S300, judging whether to switch the water supply mode; step S400, when in the first water supply mode, obtaining the condenser pressure; step S500, calculating an intermediate value of the upper threshold value of the seawater temperature according to the condenser pressure value; step S600, judging whether the condenser pressure is greater than a preset working pressure of the condenser; step S700, if greater than, updating the upper threshold value of the seawater temperature according to a first preset formula; step S800, if not greater than, updating the upper threshold value of the seawater temperature according to a second preset formula; step S900, updating the lower threshold value of the seawater temperature; step S1000, returning to step S200.

[0007] In one embodiment of the present invention, step S100 includes: step S101, obtaining the condenser heat load according to the ship speed; step S102, obtaining the gravity flow rate according to the ship speed and the resistance of the circulating water system; step S103, obtaining the total heat transfer coefficient of the condenser according to a preset empirical formula; step S104, generating the upper threshold value according to the thermal balance relationship; step S105, taking the difference between the upper threshold value and the lower threshold value as the initial value.

[0008] In one embodiment of the present invention, step S200 includes: step S201, a temperature sensor measures the seawater temperature; step S202, a controller obtains the ship speed and the seawater temperature.

[0009] In one embodiment of the present invention, step S300 includes: step S301, determining the current water supply mode; step S302, if the current water supply mode is the first water supply mode and the seawater temperature is greater than the upper threshold, switching to the second water supply mode; step S303, if the current water supply mode is the second water supply mode and the seawater temperature is less than the lower threshold, switching to the first water supply mode.

[0010] In one embodiment of the present invention, step S400 includes: step S401, when in the first water supply mode, the pressure sensor measures the condenser pressure; step S402, the controller obtains the condenser pressure.

[0011] In one embodiment of the present invention, according to the condenser pressure value P s Calculate the middle value t of the upper threshold of seawater temperature b *Calculated using the following formula:

[0012] t b *=t s (P s0 )-t s (Ps )+t1;

[0013] Among them, P s0 is the preset working pressure of the condenser, t1 is the seawater temperature, t s (P s0 ) is P s0 Steam saturation temperature under s (P s ) is P s The steam saturation temperature.

[0014] In one embodiment of the present invention, the first preset formula is: b (U)=min(t b (U),t b *); where U is the ship speed, which means t b is a function of U.

[0015] In one embodiment of the present invention, the second preset formula is: b (U)=max(t b (U),t b *); where U is the ship speed, which means t b is a function of U.

[0016] Compared with the existing technology, the condenser water supply control method based on seawater temperature according to the present invention can simply and reliably realize the switching of the condenser water supply mode, and can correct the seawater temperature threshold during the operation of the ship, which has good engineering practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of a condenser water supply control method based on seawater temperature in Example 1 of the present invention;

[0018] Figure 2 This is a logic flow diagram of a condenser water supply control method based on seawater temperature in Example 1 of the present invention;

[0019] Figure 3 This is a structural diagram of a condenser water supply system based on seawater temperature in Example 1 of the present invention.

[0020] Description of main reference numerals:

[0021] 1-circulating water pump, 2-condenser, 3-temperature sensor, 4-pressure sensor, 5-controller, 6-power switch. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0023] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0024] To facilitate understanding, the main implementation concepts of the embodiments of the present invention are first briefly described.

[0025] Steam thermal systems convert primary energy sources such as fossil fuels, nuclear energy, and solar energy into secondary energy sources such as mechanical energy, electrical energy, and hot water. In the civilian sector, steam thermal systems provide process steam, thermal energy, and power to companies such as oil refining, heating, and power generation. In the military sector, steam power systems, diesel engine power systems, and gas turbine power systems are all forms of power for ships and are mainly used on large ships. The steam thermal system uses the steam Rankine cycle. The basic thermodynamic process is the absorption of heat energy, expansion work, condensation and exhaust steam, and pressurization of condensate. The cycle efficiency can be improved through steam reheating and steam heat recovery. Condensation and exhaust steam is the core link in completing the steam Rankine cycle. The steam that has been used for work is cooled by seawater through the condenser to remove the waste heat from the cycle.

[0026] Cycle efficiency is a key indicator influencing the economic viability of steam thermal systems. In addition to employing energy-saving speed regulating devices, ships can also employ gravity cooling technology to reduce pump work. The operating state of the condenser is dependent on factors such as seawater temperature, flow rate, and ship speed. To ensure stable turbine operation, the condenser pressure must remain within the design range. This requires either gravity diversion or circulating water pumps, depending on actual conditions. Determining the condenser water supply method is crucial for achieving precise control of steam thermal systems.

[0027] The inventors discovered the technical defects described in the previous background technology and hope to find a way to simply and reliably switch the condenser water supply mode, and to correct the seawater temperature threshold during the operation of the ship, which has good engineering practicality.

[0028] In order to solve the technical problems in the prior art that the condenser water supply mode cannot be determined and the precise control of the steam thermal system cannot be achieved, the inventors of the present invention have creatively developed a condenser water supply control method based on seawater temperature.

[0029] Example 1

[0030] Figure 1This is a flow chart of a condenser water supply control method based on seawater temperature in Example 1 of the present invention; Figure 2 This is a logic flow diagram of a condenser water supply control method based on seawater temperature in Example 1 of the present invention; Figure 3 This is a structural diagram of a condenser water supply system based on seawater temperature in Example 1 of the present invention. Figures 1 to 3 As shown, a condenser water supply control method based on seawater temperature is provided in the first embodiment. The method is applied to a condenser water supply system based on seawater temperature, such as Figure 3 As shown, the system includes a controller 5, a power switch 6, a temperature sensor 3, a pressure sensor 4, and a circulating water pump 1 and a condenser 2 connected in sequence.

[0031] The condenser water supply control method based on seawater temperature includes:

[0032] Step S100: obtaining a lower threshold and an upper threshold of the seawater temperature as initial values.

[0033] Specifically, set the seawater temperature threshold t a (U) and upper threshold t b The initial value of (U), t a (U) <t b (U), and the difference between the two is Δt ab is the initial value.

[0034] Step S200: Obtain the ship's speed and seawater temperature.

[0035] Specifically, the ship speed U and the seawater temperature t1 are measured.

[0036] Step S300, determining whether to switch the water supply mode.

[0037] Specifically, if the current water supply is gravity flow, compare t1 with t b (U), when t1>t b (U), switch to pump flow water supply; if it is currently in pump flow water supply, compare t1 with t a (U), when t1 <t a (U) switches to gravity water supply.

[0038] Step S400: When in the first water supply mode, obtain the condenser pressure.

[0039] Specifically, when in gravity water supply mode, measure the condenser pressure P s .

[0040] Step S500: Calculate the critical temperature of the fresh water outlet on the hot side of the first heat exchanger according to the condenser pressure value.

[0041] Specifically, according to P s Calculate the median value t b *=t s (P s0 )-t s (P s )+t1, where P s0 is the design working pressure of the condenser, t s (P s0 ) and t s (P s ) is the same as P s0 and P s The corresponding steam saturation temperature (the saturation pressure and saturation temperature of water vapor correspond one to one).

[0042] Step S600, determine the condenser pressure P s Is it greater than the preset working pressure P of the condenser? s0 ;

[0043] Step S700: If it is greater than, update the upper threshold of seawater temperature according to the first preset formula;

[0044] Step S800: If it is not greater than, update the upper threshold of the seawater temperature according to the second preset formula.

[0045] Specifically, compared with P s With P s0 , if P s >P s0 , press t b (U)=min(t b (U), t b *) Update t b (U); if P s <P s0 , press t b (U)=max(t b (U), t b *) Update t b (U).

[0046] Step S900, according to the Δt given in step S100 ab Update a (U), that is, t a (U) = t b (U)-Δt ab .

[0047] Step S1000, return to step S200.

[0048] Based on the above, it can be seen that this embodiment can simply and reliably realize the switching of the condenser water supply mode, and can correct the seawater temperature threshold during the operation of the ship, which has good engineering practicality.

[0049] In this embodiment, t in step S100 a (U) and t b (U) The initial value is obtained as follows:

[0050] Step S101, obtaining the condenser heat load according to the ship speed.

[0051] Specifically, the condenser heat load Q is obtained according to the ship speed U.

[0052] Step S102: Obtain the gravity flow rate according to the ship speed and the resistance of the circulating water system.

[0053] Specifically, the gravity flow rate G is estimated based on the ship speed U and the resistance of the circulating water system.

[0054] Step S103: Obtain the total heat transfer coefficient of the condenser according to a preset empirical formula.

[0055] Specifically, the total heat transfer coefficient K of the condenser is estimated according to an empirical formula.

[0056] Step S104: generating the upper threshold value according to the thermal balance relationship.

[0057] Specifically, t is calculated based on the thermal equilibrium relationship. b The initial value of is as follows:

[0058]

[0059]

[0060] Where Q is the heat load of the condenser, G is the flow rate of seawater, c p is the specific heat of seawater, Δt is the temperature difference between the inlet and outlet of seawater, t s is the steam saturation temperature corresponding to the preset working pressure of the condenser, K is the total heat transfer coefficient, A is the heat exchange area of the condenser, ln is the logarithmic function, and exp is the exponential function.

[0061] Step S105: taking the difference between the upper threshold and the lower threshold as the constant value Δt ab , thus obtaining the initial value of the lower threshold t a (U) = t b (U)-Δt ab .

[0062] Based on the above, it can be seen that this embodiment can simply and reliably realize the switching of the condenser water supply mode, and can correct the seawater temperature threshold during the operation of the ship, which has good engineering practicality.

[0063] In this embodiment, step S200 includes:

[0064] Step S201, a temperature sensor measures the seawater temperature;

[0065] In step S202, the controller obtains the ship speed and the seawater temperature.

[0066] In this embodiment, step S300 includes:

[0067] Step S301, determining the current water supply mode;

[0068] Specifically, the water supply mode includes gravity water supply mode and pump flow water supply mode.

[0069] Step S302: If the current water supply mode is the first water supply mode and the seawater temperature is greater than the upper threshold, switch to the second water supply mode.

[0070] Specifically, if the current water supply mode is the gravity water supply mode and the seawater temperature is greater than the upper threshold, the water supply mode is switched to the pump flow water supply mode;

[0071] Step S303: If the current water supply mode is the second water supply mode and the seawater temperature is lower than the lower threshold, switch to the first water supply mode.

[0072] Specifically, if the current water supply mode is the pump flow water supply mode and the seawater temperature is lower than the lower threshold, the water supply mode is switched to the gravity flow water supply mode.

[0073] In this embodiment, step S400 includes:

[0074] Step S401, when in the first water supply mode, the pressure sensor measures the condenser pressure;

[0075] Specifically, when in gravity water supply mode, the pressure sensor measures the condenser pressure;

[0076] Step S402: The controller obtains the condenser pressure P s .

[0077] In this embodiment, the intermediate value of the seawater temperature threshold is calculated based on the condenser pressure value by the following formula:

[0078] t b *=t s (P s0 )-t s (P s )+t1;

[0079] Among them, P s0 is the preset working pressure of the condenser, t1 is the seawater temperature, t s (P s0 ) is P s0Steam saturation temperature under s (P s ) is P s The steam saturation temperature.

[0080] In this embodiment, the first preset formula is: b (U)=min(t b (U),t b *);

[0081] Specifically, press t b (U)=min(t b (U), t b *) Update t b (U), that is, the upper threshold of seawater temperature t b (U) is updated to t b With t b *The smaller value between b (U) represents t b is a function of the ship's speed U, t b (U) can be abbreviated as t b .

[0082] In this embodiment, the second preset formula is: b (U)=max(t b (U),t b *);

[0083] Specifically, press t b (U)=max(t b (U), t b *) Update t b (U), and then update t a (U), that is, the upper threshold of seawater temperature t b (U) is updated to t b With t b *The larger value

[0084] In practical applications, the specific calculation examples are as follows:

[0085] First, t is estimated from step S101 to step S105. a and t b Initial value. When a certain type of ship is sailing at a speed of 15 knots, the heat load of the condenser Q = 20MW, the gravity flow rate G is about 2000t / h, and the condenser design pressure P s0 The saturated steam temperature is 53.97℃, and the heat exchange surface area of the condenser is 800m 2 According to the empirical formula of the total heat transfer coefficient of the condenser given by the American Society of Heat Transfer, the total heat transfer coefficient K is estimated to be 1050W / (m 2℃), the specific heat of seawater is about 4000 J / (kg℃), and t is calculated by step S104 b The initial value of t is 25.38℃. According to step S105, take t b With t a The difference is 2℃, t a The initial value is 23.38℃.

[0086] From step S200, at this time, the ship's speed is 15 knots and the seawater temperature t1 is 22°C.

[0087] From step S300, due to t1 <t a , so gravity water supply is adopted.

[0088] In step S400, the condenser pressure P is measured at this time. s The pressure is 16 kPa, and the corresponding saturated steam temperature is 55.31 °C.

[0089] From step S500, t is calculated b *=20.66℃.

[0090] From step S600 to step S800, since P s >P s0 , update t b =min(t b , t b *)=20.66℃, update t a It is 18.66℃.

[0091] From step S900, return to step S200, the seawater temperature t1 is still 22°C, according to step S300, since t1>t b , and switch to pump flow water supply.

[0092] In summary, the condenser water supply control method based on seawater temperature of the present invention can determine the water supply mode according to the operating requirements of the condenser. The present invention can determine the switching timing between gravity water supply and pump water supply according to the seawater temperature, and provides an online correction method for the seawater temperature, which has good engineering practicality.

[0093] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A condenser water supply control method based on seawater temperature, characterized in that: include: Step S100, obtaining a lower threshold and an upper threshold of the seawater temperature as initial values; Step S200, obtaining the ship's speed and seawater temperature; Step S300, determining whether to switch the water supply mode; Step S400, when in the first water supply mode, obtaining the condenser pressure; Step S500, calculating the middle value of the upper threshold of the seawater temperature according to the condenser pressure value; Step S600, determining whether the condenser pressure is greater than the preset working pressure of the condenser; Step S700: If it is greater than, update the upper threshold of seawater temperature according to a first preset formula; Step S800: If not, update the upper threshold of seawater temperature according to the second preset formula; Step S900, updating the seawater temperature threshold; Step S1000, return to step S200; Wherein, the step S100 includes: Step S101, obtaining the condenser heat load according to the ship speed; Step S102, obtaining the gravity flow rate according to the ship speed and the resistance of the circulating water system; Step S103, obtaining the total heat transfer coefficient of the condenser according to a preset empirical formula; Step S104, generating the upper threshold of seawater temperature according to the thermal balance relationship; Step S105, taking the difference between the upper threshold value of the seawater temperature and the lower threshold value of the seawater temperature as a fixed value, thereby obtaining an initial value of the lower threshold value of the seawater temperature; Wherein, the step S300 includes: Step S301, determining the current water supply mode; Step S302: If the current water supply mode is the first water supply mode and the seawater temperature is greater than the upper threshold, switch to the second water supply mode; Step S303: If the current water supply mode is the second water supply mode and the seawater temperature is lower than the lower threshold, switch to the first water supply mode; According to the condenser pressure value P s The middle value of the upper threshold of seawater temperature is calculated by the following formula: t b *= t s ( P s0 )- t s ( P s )+ t 1； in, t b * is the median value for calculating the upper threshold of seawater temperature. P s0 Preset working pressure for the condenser, t 1 is the sea water temperature, t s ( P s0 ) is the saturated steam temperature at the preset working pressure, t s ( P s )for P s Saturated steam temperature under Wherein, the first preset formula is: t b ( U )= min( t b ( U ), t b *); in, U is the ship speed, indicating t b yes U function; Wherein, the second preset formula is: t b ( U )=max( t b ( U ), t b *); in, U is the ship speed, indicating t b yes U function.

2. The condenser water supply control method based on seawater temperature according to claim 1, characterized in that: The step S200 includes: Step S201, a temperature sensor measures the seawater temperature; In step S202, the controller obtains the ship speed and the seawater temperature.

3. The condenser water supply control method based on seawater temperature according to claim 1, characterized in that: The step S400 includes: Step S401, when in the first water supply mode, the pressure sensor measures the condenser pressure; In step S402 , the controller obtains the condenser pressure.

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