A freshwater transport monitoring and metering system and its control method for water supply tugboats

Abstract

This invention discloses a freshwater delivery monitoring and metering system and its control method for a water supply tugboat. The system includes a PLC monitoring unit, an industrial computer, a printer, a Mimic monitoring board, an electrically adjustable butterfly valve, an electrically operated butterfly valve, a freshwater tank level sensor, an outlet flow meter, an outlet main pipe pressure sensor, and a water supply pump. The industrial computer or Mimic monitoring board is integrated with the PLC monitoring unit. The PLC monitoring unit automatically or manually controls the external water supply or internal water injection. Based on the measured freshwater tank level dataset, the PLC monitoring unit obtains the still water level and tank volume, and controls the opening of the electrically adjustable butterfly valve and the opening and closing of the electrically operated butterfly valve. This ensures that the freshwater tank level and level difference remain within allowable limits during external water supply or internal water injection. The system also features self-leveling of level data, alarm functions for abnormal situations, and report printing functions. This invention ensures that the injection or output of freshwater does not affect the stability of the tugboat during freshwater replenishment or external water supply.

Description

Technical Field

[0001] This invention belongs to the field of freshwater transport monitoring of ships, and specifically relates to a freshwater transport monitoring and metering system and its control method for water supply tugboats. Background Technology

[0002] Water supply tugboats are based on traditional tugboats, but with the added function of providing drinking water to ships that have difficulty docking to refill their drinking water supply.

[0003] The utility model patent with application number 202122285244.7, entitled "Full Rotation Tugboat External Water Supply System", describes the mechanical structure of a tugboat external water supply system, but does not involve its monitoring and metering system and its control method.

[0004] In actual refueling or external water supply processes, without suitable control methods, refueling or external water supply can increase the instability of tugboats, thereby forcing the ballast water system to operate and increasing additional losses. Therefore, how to accurately and efficiently control the freshwater delivery system to avoid forcing the ballast water system to operate during refueling or external water supply is a technical problem that needs to be solved. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a freshwater transportation monitoring and metering system and control method for water supply tugboats, so as to ensure that the injection or output of freshwater does not affect the stability of the tugboat itself when adding or supplying freshwater, and to accurately measure the water supply when supplying water to the outside world, so as to provide a reliable basis for water supply charges.

[0006] Technical solution: The present invention provides a freshwater transport monitoring and metering system for water supply tugboats, comprising a PLC monitoring unit, and an industrial control computer, a Mimic monitoring board, an electric regulating butterfly valve, an electric switching butterfly valve, a freshwater tank level sensor, an outlet flow meter, an outlet main pipe pressure sensor, and a water supply pump connected to the PLC monitoring unit; the number of the electric switching butterfly valves is several, one of which is an electric filling changeover butterfly valve;

[0007] The industrial control computer is used to set various data for external fresh water supply or internal fresh water replenishment, send the set data, start / stop, pause / continue commands to the PLC monitoring unit, and display and store the operating data. The industrial control computer or Mimic monitoring board is combined with the PLC monitoring unit, and the PLC monitoring unit automatically or manually controls the external fresh water supply or internal fresh water replenishment according to the data and commands set by the industrial control computer or the control commands of the Mimic monitoring board.

[0008] The Mimic monitoring board is connected to the PLC monitoring unit via an RS485 bus. It sends manual / automatic status and control commands during manual operation to the PLC monitoring unit. The PLC monitoring unit first determines the system status. In automatic mode, it executes the automatic program. In manual mode, it controls the opening and closing of the electric switch butterfly valve, the opening degree of the electric regulating butterfly valve, the opening and closing of the electric filling switch butterfly valve, and the start and stop of the water supply pump according to the commands sent by the Mimic monitoring board. The Mimic monitoring board is also used to obtain the opening degree of the regulating butterfly valve, the on / off status of the switch butterfly valve, the liquid level in the chamber, the water volume in the chamber, the water pressure, the cumulative flow at the end of the last water discharge, the current cumulative flow of the water discharge, and alarm signals, and displays them on the Mimic monitoring board to provide a basis for issuing control commands during manual operation.

[0009] The PLC monitoring unit is used to monitor the freshwater tank level and calculate the tank volume based on data from the freshwater tank level sensor, the outlet flow meter, and the outlet main pipe pressure sensor. In automatic mode, it automatically controls the opening and closing of the electric switch butterfly valve, the electric regulating butterfly valve opening, and the electric filling switch butterfly valve on the outlet pipe according to the calculation results and the data and commands set by the industrial control computer, so as to keep the freshwater tank levels on the left and right sides the same and keep the difference between the bow and stern freshwater tank levels within the allowable range.

[0010] Furthermore, the electric regulating butterfly valve is installed on the inlet and outlet water pipes of the freshwater tank hatch to regulate the inlet and outlet water flow of the freshwater tank hatch.

[0011] The electrically operated butterfly valve is installed on the pipeline and is used to control the opening and closing of the pipeline;

[0012] The freshwater tank level sensor consists of several units, which are installed at the midpoint of the cross-section of the freshwater tank to measure the tank level. The PLC monitoring unit measures the analog signal of the freshwater tank level sensor in real time and converts it into the corresponding level value.

[0013] The main outlet water pressure sensor is installed on the main outlet water pipe to measure the outlet water pressure when supplying water to the outside. The PLC monitoring unit measures the analog signal of the main outlet water pressure sensor in real time and converts it into the corresponding pressure value.

[0014] The water flow meter is installed on the water outlet pipe to measure the water flow rate, and the PLC monitoring unit reads the flow meter data in real time.

[0015] The water supply pump is installed on the main water supply pipe and is used to supply water to external users.

[0016] Furthermore, the electric refueling changeover switch butterfly valve is installed on the connecting pipe between the bow and stern freshwater tanks, while the remaining electric switch butterfly valves are installed on the water outlet pipe of the water supply tugboat.

[0017] The electrically operated refueling changeover butterfly valve is used to close when the bow is internally refueling and the aft-to-rear liquid level difference is close to the maximum allowable value or the stern freshwater tank level reaches the maximum value, so that only the bow freshwater tank is refueled. In addition, the electrically operated refueling changeover butterfly valve is also used to close when the bow is externally supplying water and the aft-to-rear liquid level difference is close to the maximum allowable value, so that only the bow freshwater tank supplies water to the outside.

[0018] Furthermore, the number of water flow meters is at least four, which are installed on the external water supply and outlet pipes at the bow and stern of the ship;

[0019] The number of Mimic monitoring boards is at least two, which are installed on the bow and stern decks respectively.

[0020] Furthermore, the electric regulating butterfly valve and the PLC monitoring unit exchange information via a 4-20mA current signal; the electric switching butterfly valve and the PLC monitoring unit, and the water supply pump and the PLC monitoring unit, exchange information via switching signals.

[0021] The freshwater tank level sensor and the outlet main pressure sensor respectively transmit a 4-20mA current signal to the PLC monitoring unit.

[0022] Furthermore, the number of water supply pumps is at least two, which are installed on the bow water supply main pipe and the stern water supply main pipe respectively. When supplying water, one of the water supply pumps is selected to operate according to the water supply location.

[0023] Based on the same inventive concept, the present invention provides a control method for a freshwater transport monitoring and metering system for a water supply tugboat, comprising two stages: automatic / manual water filling of the freshwater tank and automatic / manual water supply to the outside of the freshwater tank; wherein...

[0024] During the automatic water filling phase, the PLC monitoring unit forms a liquid level dataset based on the set data and control commands of the industrial control computer, as well as the real-time liquid level data of the tanks measured by several freshwater tank level sensors. The actual liquid level data during static water is obtained by looking up the table based on the liquid level dataset, and then the liquid level change rate and tank volume change value are calculated. The PLC monitoring unit combines the freshwater tank liquid level data, freshwater tank volume data, and the set data and commands of the industrial control computer to control the opening of the electric regulating butterfly valve and the opening and closing of the electric filling conversion switch butterfly valve. In the process of completing the input of the specified freshwater volume, the liquid level difference between the left and right freshwater tanks approaches 0 and the liquid level difference between the front and rear freshwater tanks is less than the maximum allowable liquid level difference.

[0025] During the automatic water supply phase, in addition to combining the freshwater tank level data, freshwater tank capacity data, and data set by the industrial control computer, the PLC monitoring unit also needs to combine the flow meter data measured by the outlet flow meter and control the opening and closing of the electric butterfly valve on the outlet pipeline.

[0026] In manual mode, the Mimic monitoring board sends control commands to the PLC monitoring unit via RS485. The PLC monitoring unit controls the opening and closing of the electric switch butterfly valve, the opening degree of the electric regulating butterfly valve, the opening and closing of the electric filling changeover switch butterfly valve, and the start and stop of the water supply pump on the water outlet pipeline according to the control commands. The Mimic monitoring board obtains the liquid level change rate and tank volume change value, regulating butterfly valve opening degree, switch butterfly valve opening status, tank liquid level, tank water volume, water outlet pressure, cumulative flow at the end of the last water outlet, current cumulative water outlet flow and alarm signals calculated by the PLC monitoring unit via RS485 and displays them on the Mimic monitoring board, providing a basis for issuing control commands in manual mode.

[0027] Furthermore, the actual liquid level data during still water conditions is obtained by looking up a table based on the liquid level dataset, including:

[0028] Based on the relationship curve between liquid level and tank capacity when the tank capacity table is fitted, and the relationship dataset between liquid level data and actual liquid level corresponding to different tilt angles is obtained based on the known range and period of change of the tilt angle.

[0029] Furthermore, the calculation process for the dataset relating the liquid level data corresponding to different tilt angles and the actual liquid level is as follows:

[0030] Based on the minimum change period, the timing sampling period and calculation step size are set to calculate the critical liquid level at different tilt angles, thus obtaining the critical vertical liquid level h measured during tilt. i0 =Lsinα, α≠0, where L is the distance from the freshwater tank level sensor to the tank side wall, and the corresponding liquid level in still water is H. i0 =0.25Lsin2α;

[0031] The liquid level H of this tank in still water is obtained from the critical vertical liquid level measured during tilting. i Let the vertical h measured in real time be... i Greater than h i0 The vertical liquid level measured at this tilt angle is h. i =h i0 +Δh i Then the corresponding liquid level H in still water can be obtained. i =H i0 +Δh i cosα=0.25Lsin2α+Δh i cosα;

[0032] Let h be the vertical liquid level measured in real time. i Less than h i0 The vertical liquid level measured at this tilt angle is h. i ′, then the corresponding liquid level H in still water can be obtained. i =0.25(L+h)i ′ / sinα) 2 sinα / L; thus, the dataset based on the critical liquid level is calculated for different tilt angles. In practical applications, the corresponding liquid level value under static water is obtained by looking up the table based on the measured liquid level value, and then the corresponding tank capacity value is obtained.

[0033] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0034] This solution can effectively ensure that the stability of the tugboat is not affected when injecting fresh water or supplying water to the outside world. It avoids the need for the ballast water system to operate to adjust the stability of the tugboat due to water injection or external water supply, and can accurately measure the amount of water supplied to the outside world.

[0035] The control method of the present invention can accurately estimate and control the level and volume of the freshwater tank, so that when water is injected into the freshwater tank on the ship or freshwater is supplied to the outside of the ship, the change in the level of the freshwater tank will not increase the roll amplitude of the tugboat. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a freshwater transport monitoring and metering system for a water supply tugboat disclosed in an embodiment of the present invention;

[0037] Figure 2 This is a flowchart illustrating the workflow of an industrial control computer as disclosed in an embodiment of the present invention.

[0038] Figure 3 This is a flowchart of the PLC monitoring unit disclosed in an embodiment of the present invention. Detailed Implementation

[0039] The technical solution of the present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0040] Example 1

[0041] like Figure 1As shown, the freshwater transport monitoring and metering system for a water supply tugboat of the present invention includes a PLC monitoring unit, and an industrial control computer, a Mimic monitoring board, an electrically adjustable butterfly valve, an electrically operated butterfly valve, a freshwater tank level sensor, an outlet flow meter, an outlet main pipe pressure sensor, and a water supply pump connected to the PLC monitoring unit. The industrial control computer is also connected to a printer. The industrial control computer and the PLC monitoring unit communicate via Ethernet; the Mimic monitoring board and the PLC monitoring unit, and the outlet flow meter and the PLC monitoring unit communicate via RS485; the electrically adjustable butterfly valve and the PLC monitoring unit communicate via a 4-20mA current signal; the electrically operated butterfly valve and the PLC monitoring unit, and the water supply pump and the PLC monitoring unit communicate via switch signals; the printer and the industrial control computer communicate via a USB cable.

[0042] The PLC monitoring unit is installed inside the engine room and can effectively monitor the freshwater tank level and accurately calculate the tank volume based on input and output signals. In this embodiment, the PLC monitoring unit is used to monitor the freshwater tank level and calculate the tank volume based on signals from the freshwater tank level sensor, the outlet flow meter, and the outlet main pressure sensor. In manual mode, the PLC monitoring unit receives commands from the Mimic monitoring board and manually controls the start / stop of the water supply pump, the opening of the electric regulating butterfly valve, and the opening and closing of the electric switch butterfly valve. It also determines whether to issue an alarm signal based on the calculation results and the data set by the industrial control computer. In automatic mode, the PLC monitoring unit automatically controls the opening of the electric regulating butterfly valve and the opening and closing of the electric switch butterfly valve based on the calculation results, the data set by the industrial control computer, and the commands, so that the freshwater tank levels on the left and right sides are the same and the difference between the bow and stern freshwater tank levels is kept within the allowable range.

[0043] The industrial control computer is used to set various data for external freshwater supply or internal freshwater replenishment, and to display the opening degree of the electric regulating butterfly valve, the on / off status of the electric regulating butterfly valve, the liquid level and actual water volume of each freshwater tank in the tugboat, etc. In automatic mode, it is also used to send the set data and start / stop, pause / continue commands to the PLC monitoring unit. The PLC monitoring unit automatically controls the external freshwater supply or internal freshwater replenishment according to the received data and commands. It is also used to store operating data and print reports.

[0044] In this embodiment, the industrial control computer is installed in the control room. It can set the total external water supply flow rate and the external water supply flow rate of each compartment during automatic external water supply, and select the water supply pump to be operated during external water supply (one of two options); it can also set the water injection volume of each compartment during automatic freshwater tank filling; and it displays the opening degree of each regulating butterfly valve, the on / off status of each switch butterfly valve, the liquid level of each freshwater tank, and the actual water volume, etc. In automatic mode, the PLC monitoring unit automatically controls the external freshwater supply or the internal freshwater filling according to the received data and commands, and stores the operating data. A printer is installed in the control room to print data when external water supply ends or to print a water filling report when water filling ends.

[0045] In this embodiment, two Mimic monitoring boards are installed on the bow and stern decks, respectively. They can be set to manual or automatic modes. In manual mode, the Mimic monitoring board can send commands to the PLC monitoring unit via RS485 communication to manually control the opening of the electric regulating butterfly valve, the opening and closing of the electric switch butterfly valve, and the start and stop of the water supply pump. The board can obtain information from the PLC monitoring unit via RS485 communication, including the opening of the regulating butterfly valve, the switch butterfly valve's on / off status, the compartment liquid level, the compartment water volume, the outlet pressure, the cumulative flow at the end of the last outlet, the current cumulative outlet flow, and alarm information, and display this information on the Mimic monitoring board, providing a basis for issuing control commands in manual mode.

[0046] The electrically operated regulating butterfly valves are installed at the intake of the freshwater tank to regulate the inlet and outlet flow rates. In this embodiment, four electrically operated regulating butterfly valves are installed on the inlet and outlet pipes of the four freshwater tank hatches, respectively.

[0047] The electrically operated butterfly valves are installed on the pipelines to control their opening and closing. There are several electrically operated butterfly valves, one of which is a refueling changeover butterfly valve installed on the connecting pipeline between the bow and stern freshwater tanks, and the rest are installed on the outlet pipelines of the water supply tugboat. In this embodiment, there are five electrically operated butterfly valves: one is an electrically operated refueling changeover butterfly valve installed on the connecting pipeline between the bow and stern freshwater tanks, and the other four are installed at the outlets of the four outlet pipelines at port bow, starboard bow, port stern, and starboard stern, respectively.

[0048] Several freshwater tank level sensors are installed at the midpoint of the freshwater tank's cross-section to measure the tank's liquid level. The PLC monitoring unit monitors the analog signals from the freshwater tank level sensors in real time and converts them into corresponding liquid level values. The outlet main pipe pressure sensor is installed on the outlet main pipe to measure the outlet water pressure when supplying water to the outside. The PLC monitoring unit monitors the analog signals from the outlet main pipe pressure sensor in real time and converts them into corresponding pressure values.

[0049] In this embodiment, four freshwater tank level sensors are installed at the midpoint of the cross-section of each of the four freshwater tanks to measure the tank level. Two main outlet pressure sensors are installed on the bow and stern main outlet pipes respectively to measure the outlet pressure during water supply; an alarm is triggered if the outlet pressure does not meet the requirements. Two water supply pumps are installed on the bow and stern main outlet pipes respectively.

[0050] The water flow meter is installed on the water outlet pipe to measure the water flow rate, and the PLC monitoring unit reads the flow meter data in real time. In this embodiment, there are four water flow meters, which are installed on the water supply pipes at the bow and stern of the ship to measure the water flow rate.

[0051] like Figure 2 As shown, the industrial control computer acts as the host computer, and its workflow is as follows:

[0052] The industrial control computer acquires data from the PLC monitoring unit in real time and checks for alarm information. If an alarm is detected, it records the alarm information. Then, the display shows the cumulative water supply flow rate at the end of the last water supply cycle, the current cumulative water supply flow rate, the initial liquid level and capacity of each compartment, the current liquid level and capacity, and the system status (manual / automatic, running, terminated, adjusting butterfly valve opening, butterfly valve on / off status, fault alarm, etc.). Next, it determines the system's operating status. If in manual mode, it repeats the above steps cyclically; if in automatic mode, it first checks whether it has entered automatic operation mode. If automatic operation has been initiated, the system checks whether the target has been achieved. If so, it prints the data, clears the set parameters, and enables the parameter setting function. If the target has not been achieved, it checks for pause or continue commands. If so, it sends a pause or continue command to the PLC. When not in automatic operation mode, the system can set the filling flow rate of each compartment or the external water supply flow rate, the total external water supply flow rate, and select the water pump to be run. After setting, the "Start" button can be clicked to send the set parameters and control commands to the PLC and disable the parameter setting function.

[0053] The PLC monitoring unit periodically collects the liquid level values ​​of each compartment when there is no water supply or external water supply. For example... Figure 3 As shown, the workflow of the PLC monitoring unit is as follows: First, it checks if there is a running signal. If not, the PLC monitoring unit compares and corrects the collected data (timely collection of liquid level values ​​in each compartment) with known liquid level parameters and corresponding calculation datasets, and supplements the existing dataset; the above cycle is repeated. If there is a running signal, it first determines the running mode. In manual mode, it executes the corresponding operation according to the instructions sent by the Mimic monitoring board, and obtains the liquid level value and tank capacity when the water is still based on the collected liquid level values ​​in each compartment. It then performs liquid level difference comparison, injection quantity judgment, or external water supply quantity judgment. If there is an abnormality, an alarm signal is issued. In automatic mode, it first checks if the control target has been completed. If it has been completed, the automatic running signal is cleared. If it has not been completed, it controls the opening of the regulating butterfly valve or the opening and closing of the injection conversion butterfly valve according to the data and instructions sent by the industrial control computer, as well as the liquid level data, liquid level difference data, tank capacity, and flow rate data, so that the liquid level difference, injection quantity, or external water supply quantity meets the requirements during injection or external water supply.

[0054] In this scheme, when the freshwater tank is supplying water to the outside, in automatic mode, the PLC monitoring unit calculates the actual liquid level and tank volume of the freshwater tank in real time based on the liquid level signal, liquid level signal change rate, flow rate signal, flow rate change rate, and data set by the industrial control computer, combined with pre-calculated liquid level and tank volume datasets. It then controls the opening of the electric regulating butterfly valve and the opening and closing of the electric filling changeover butterfly valve to keep the liquid levels in the left and right freshwater tanks the same and to keep the liquid level difference between the bow and stern freshwater tanks within the allowable range. When manually supplying water to the outside, the PLC monitoring unit controls the start / stop of the water supply pump, the opening of the electric regulating butterfly valve, and the opening and closing of the electric filling changeover butterfly valve according to commands sent from the Mimic monitoring board. It also judges in real time whether the liquid level difference between the left and right freshwater tanks and the liquid level difference between the bow and stern freshwater tanks are within the allowable range. If the level is outside the allowed range, an alarm will be issued. During freshwater tank filling, in automatic mode, the PLC monitoring unit calculates the actual level and capacity of the freshwater tank in real time based on the level signal, level change rate, data set by the industrial control computer, and pre-calculated level and tank capacity datasets. It automatically controls the opening of the electric regulating butterfly valve and the opening and closing of the electric filling switch butterfly valve to maintain the same level in the left and right freshwater tanks and keep the level difference between the bow and stern freshwater tanks within the allowable range. In manual mode, the PLC monitoring unit controls the start / stop of the water supply pump, the opening of the electric regulating butterfly valve, and the opening and closing of the electric filling switch butterfly valve according to commands from the Mimic monitoring board. It also judges in real time whether the level difference between the left and right freshwater tanks and the level difference between the bow and stern freshwater tanks are within the allowable range; if not, an alarm will be issued.

[0055] Example 2

[0056] The present invention discloses a control method for a freshwater transport monitoring and metering system for a water supply tugboat, comprising automatically supplying freshwater into the freshwater tank. Manual / Automatic Water Injection The process involves two stages: automatic / manual water supply to the freshwater tank. Details are as follows:

[0057] During the automatic water injection phase into the freshwater tank, the PLC monitoring unit, based on the set data and control commands from the industrial control computer, as well as the real-time liquid level data from several freshwater tank level sensors, forms a liquid level dataset. The actual liquid level data during still water is obtained by looking up the data in a table, and then the liquid level change rate and tank volume change value are calculated. The PLC monitoring unit, combining the freshwater tank liquid level data, freshwater tank volume data, and the data set by the industrial control computer, controls the opening of the electric regulating butterfly valve and the opening and closing of the electric filling changeover butterfly valve. During the process of inputting the specified freshwater volume, the liquid level difference between the left and right freshwater tanks approaches 0, and the liquid level difference between the front and rear freshwater tanks is less than the maximum allowable liquid level difference.

[0058] During the automatic water supply phase to the outside of the freshwater tank, compared to the automatic water filling phase, the PLC monitoring unit, in addition to combining the freshwater tank level data, tank volume data, and data set by the industrial control computer, also needs to consider the flow meter data measured by the outlet flow meter. Specifically:

[0059] The PLC monitoring unit, based on the set data and control commands from the industrial control computer, as well as the real-time liquid level data of the tanks obtained from several freshwater tank level sensors, forms a liquid level dataset. It then looks up the actual liquid level data during still water conditions using this dataset, and calculates the accurate rate of change of liquid level and tank volume change. Combining the flow meter data measured by the outlet flow meter, the freshwater tank level data, the freshwater tank volume data, and the data set by the industrial control computer, the PLC monitoring unit controls the opening of the electric regulating butterfly valve and the opening and closing of the electric switch butterfly valve. During the process of outputting the specified freshwater volume, it ensures that the liquid level difference between the left and right freshwater tanks approaches zero and the liquid level difference between the front and rear freshwater tanks is less than the maximum liquid level difference.

[0060] In manual mode, the Mimic monitoring board sends control commands to the PLC monitoring unit via RS485. The PLC monitoring unit controls the opening of the electric regulating butterfly valve, the opening and closing of the electric filling changeover butterfly valve, and the start and stop of the water supply pump according to the control commands. The Mimic monitoring board obtains the liquid level change rate and tank volume change value, regulating butterfly valve opening, butterfly valve opening and closing status, tank liquid level, tank water volume, outlet pressure, cumulative flow at the end of the last water discharge, current cumulative flow, and alarm signals calculated by the PLC monitoring unit via RS485 and displays them on the Mimic monitoring board, providing a basis for issuing control commands in manual mode.

[0061] In this embodiment, the actual liquid level data during still water is obtained by looking up a table based on the liquid level dataset, including:

[0062] First, the relationship curve between liquid level and tank capacity in still water is fitted according to the tank capacity table. Based on the known range and period of change of the tilt angle, the data set of liquid level data corresponding to different tilt angles and the relationship data between the actual liquid level are obtained. Then, the opening degree of the regulating butterfly valve is determined according to the liquid level change rate of the freshwater tank corresponding to the electric regulating butterfly valve, the liquid level difference between the freshwater tank and the vertically adjacent freshwater tanks in the horizontal and vertical directions, and the output water flow rate.

[0063] The method for obtaining the still water level data corresponding to the roll angle is as follows: A curve relating the still water level and tank capacity is fitted based on the tank capacity table. Then, based on the known range and period of the roll angle variation, a dataset relating the water level data at different roll angles to the actual water level is calculated. In practical applications, the actual water level data is obtained by looking up the table from the real-time measured water level dataset. The specific implementation method and steps are as follows:

[0064] Based on the minimum possible variation period, the timing sampling period and calculation step size are set to calculate the critical liquid level at different tilt angles (when tilting, the liquid level at one end of the cross-section of the pressure sensor through the main outlet pipe is just flush with the lowest end of the side wall of the compartment), thus obtaining the critical vertical liquid level h at the tilt angle. i0=Lsinα, α≠0, where L is the distance from the freshwater tank level sensor to the tank side wall, and the corresponding liquid level in still water is H. i0 =0.25Lsin2α;

[0065] The liquid level of this tank in still water is obtained from the critical vertical liquid level measured during tilting; let h be the vertical liquid level measured in real time. i Greater than h i0 The vertical liquid level measured at this tilt angle is h. i =h i0 +Δh i Then the corresponding liquid level H in still water can be obtained. i =H i0 +Δh i cosα=0.25Lsin2α+Δh i cosα;

[0066] Let h be the vertical liquid level measured in real time. i Less than h i0 The vertical liquid level measured at this tilt angle is h. i ′, then the corresponding liquid level H in still water can be obtained. i =0.25(L+h) i ′ / sinα) 2 sinα / L; This allows us to calculate the dataset based on the critical liquid level at different tilt angles. In practical applications, based on the measured pressure value, we can look up the corresponding liquid level value in still water by referring to a table, and then obtain the corresponding tank capacity value.

[0067] After obtaining the static water level data corresponding to the heeling position, the opening degree of the regulating butterfly valve is determined based on the water level change rate of a certain freshwater tank, the water level difference data between this freshwater tank and the vertically adjacent freshwater tanks in the transverse and longitudinal directions, and the output water flow rate. This ensures that the water level difference between the port and starboard freshwater tanks approaches 0, and the water level difference between the fore and aft freshwater tanks is less than the maximum water level difference. The specific implementation method is as follows: Assume that the bow freshwater tanks are numbered 1 and 2, and the stern freshwater tanks are numbered 3 and 4; tanks 1 and 3 are on the port side, and tanks 2 and 4 are on the starboard side.

[0068] Taking freshwater tank No. 1 as an example, the opening degree of its electric regulating butterfly valve, the rate of change of the freshwater level in tank No. 1, and the level difference between freshwater tanks No. 1 and No. 2 satisfy the following relationship:

[0069]

[0070] Among them, C 艏 The flow rate for adding or removing water to the designated compartments; ΔC 艏 The real-time water flow rate for filling or emptying the compartment decreases continuously as water is added or removed, until it reaches 0, Δh 12 This represents the liquid level difference between the left and right compartments.

[0071]

[0072] Valve opening degree K i The value range is [0, 1], corresponding to 4 to 20 mA.

[0073] The level difference between the bow and stern freshwater tanks is relatively easy to control. When water is supplied to the outside from the stern, if the level difference approaches the maximum allowable value, the electrically operated regulating butterfly valves of the port and starboard stern freshwater tanks are simultaneously closed, allowing only the port and starboard stern freshwater tanks to supply water. When the bow-stern level difference is less than or equal to 2 / 3 of the maximum allowable value, the stern freshwater tanks then supply water to the outside simultaneously. When water is supplied to the outside from the bow, if the level difference approaches the maximum allowable value, the electrically operated refueling switch butterfly valve is closed, allowing only the port and starboard stern freshwater tanks to supply water. When the bow-stern level difference is less than or equal to 1 / 3 of the maximum allowable value, the electrically operated refueling switch butterfly valve is opened, allowing the stern freshwater tanks to supply water to the outside simultaneously. During refueling... If the filling location is at the stern, when the level difference is close to the maximum allowable value, or when the stern freshwater tank is full, the electric regulating butterfly valves of the port and starboard stern freshwater tanks will be closed simultaneously, and filling will only be done to the port and starboard bow freshwater tanks; when the level difference between the bow and stern is less than or equal to 2 / 3 of the maximum allowable value and the stern freshwater tank is not full, the stern freshwater tank will be filled simultaneously again. If the filling location is at the bow, when the level difference is close to the maximum allowable value, the filling conversion switch butterfly valve will be closed, and filling will only be done to the port and starboard bow freshwater tanks; when the level difference between the bow and stern is less than or equal to 2 / 3 of the maximum allowable value and the stern freshwater tank is not full, the filling conversion switch butterfly valve will be opened again, and the stern freshwater tank will be filled simultaneously again.

Claims

1. A freshwater transport monitoring and metering system for a water supply tugboat, characterized in that: It includes a PLC monitoring unit, and an industrial computer, Mimic monitoring board, electric regulating butterfly valve, electric switching butterfly valve, freshwater tank level sensor, outlet flow meter, outlet main pipe pressure sensor, and water supply pump connected to the PLC monitoring unit; the number of electric switching butterfly valves is several, one of which is an electric filling changeover butterfly valve; The industrial control computer is used to set various data for external fresh water supply or internal fresh water replenishment, send the set data, start / stop, pause / continue commands to the PLC monitoring unit, and display and store the operating data. The industrial control computer or Mimic monitoring board is combined with the PLC monitoring unit, and the PLC monitoring unit automatically or manually controls the external fresh water supply or internal fresh water replenishment according to the data and commands set by the industrial control computer or the control commands of the Mimic monitoring board. The Mimic monitoring board is connected to the PLC monitoring unit via an RS485 bus. It sends manual / automatic status and control commands during manual operation to the PLC monitoring unit. The PLC monitoring unit first determines the system status. In automatic mode, it executes the automatic program. In manual mode, it controls the opening and closing of the electric switch butterfly valve, the opening degree of the electric regulating butterfly valve, the opening and closing of the electric filling switch butterfly valve, and the start and stop of the water supply pump according to the commands sent by the Mimic monitoring board. The Mimic monitoring board is also used to obtain the opening degree of the regulating butterfly valve, the on / off status of the switch butterfly valve, the liquid level in the chamber, the water volume in the chamber, the water pressure, the cumulative flow at the end of the last water discharge, the current cumulative flow of the water discharge, and alarm signals, and displays them on the Mimic monitoring board to provide a basis for issuing control commands during manual operation. The PLC monitoring unit is used to monitor the freshwater tank level and calculate the tank volume based on data from the freshwater tank level sensor, the outlet flow meter, and the outlet main pipe pressure sensor. In automatic mode, it automatically controls the opening and closing of the electric switch butterfly valve, the electric regulating butterfly valve opening, and the electric filling switch butterfly valve on the outlet pipe according to the calculation results and the data and commands set by the industrial control computer, so as to keep the freshwater tank levels on the left and right sides the same and keep the difference between the bow and stern freshwater tank levels within the allowable range.

2. The freshwater transport monitoring and metering system for water supply tugboats according to claim 1, characterized in that: The electric regulating butterfly valve is installed on the inlet and outlet water pipes of the freshwater tank hatch and is used to regulate the inlet and outlet water flow of the freshwater tank hatch. The electrically operated butterfly valve is installed on the pipeline and is used to control the opening and closing of the pipeline; The freshwater tank level sensor consists of several units, which are installed at the midpoint of the cross-section of the freshwater tank to measure the tank level. The PLC monitoring unit measures the analog signal of the freshwater tank level sensor in real time and converts it into the corresponding level value. The main outlet water pressure sensor is installed on the main outlet water pipe to measure the outlet water pressure when supplying water to the outside. The PLC monitoring unit measures the analog signal of the main outlet water pressure sensor in real time and converts it into the corresponding pressure value. The water flow meter is installed on the water outlet pipe to measure the water flow rate, and the PLC monitoring unit reads the flow meter data in real time. The water supply pump is installed on the main water supply pipe and is used to supply water to external users.

3. The freshwater transport monitoring and metering system for water supply tugboats according to claim 1, characterized in that: The electric refueling changeover switch butterfly valve is installed on the connecting pipe between the bow and stern freshwater tanks, while the other electric switch butterfly valves are installed on the water outlet pipe of the water supply tugboat. The electrically operated refueling changeover butterfly valve is used to close when the bow is internally refueling and the aft-to-rear liquid level difference is close to the maximum allowable value or the stern freshwater tank level reaches the maximum value, so that only the bow freshwater tank is refueled. In addition, the electrically operated refueling changeover butterfly valve is also used to close when the bow is externally supplying water and the aft-to-rear liquid level difference is close to the maximum allowable value, so that only the bow freshwater tank supplies water to the outside.

4. The freshwater transport monitoring and metering system for water supply tugboats according to claim 1, characterized in that: The number of water flow meters is at least four, and they are installed on the external water supply and outlet pipes at the bow and stern of the ship; The number of Mimic monitoring boards is at least two, which are installed on the bow and stern decks respectively.

5. The freshwater transport monitoring and metering system for water supply tugboats according to claim 1, characterized in that: The electric regulating butterfly valve and the PLC monitoring unit exchange information via a 4-20mA current signal; the electric switching butterfly valve and the PLC monitoring unit, and the water supply pump and the PLC monitoring unit exchange information via switching signals. The freshwater tank level sensor and the outlet main pressure sensor respectively transmit a 4-20mA current signal to the PLC monitoring unit.

6. The freshwater transport monitoring and metering system for water supply tugboats according to claim 1, characterized in that: The number of water supply pumps is at least two, which are installed on the bow water supply main pipe and the stern water supply main pipe respectively. When supplying water, one of the water supply pumps is selected to operate according to the water supply location.

7. A control method for a freshwater transport monitoring and metering system for a water supply tugboat, characterized in that, It includes two stages: automatic / manual water filling into the freshwater tank and automatic / manual water supply to the outside of the freshwater tank; among which, During the automatic water injection phase into the freshwater tank, the PLC monitoring unit, based on the set data and control commands from the industrial control computer, as well as the real-time liquid level data of the tanks obtained from several freshwater tank level sensors, forms a liquid level dataset. The actual liquid level data during static water is obtained by looking up the table based on the liquid level dataset, and then the liquid level change rate and tank volume change value are calculated. The PLC monitoring unit combines the freshwater tank liquid level data, freshwater tank volume data, and the set data and commands from the industrial control computer to control the opening of the electric regulating butterfly valve and the opening and closing of the electric filling conversion switch butterfly valve. In the process of completing the input of the specified freshwater volume, the liquid level difference between the left and right freshwater tanks approaches 0 and the liquid level difference between the front and rear freshwater tanks is less than the maximum allowable liquid level difference. During the automatic water supply phase to the freshwater tank, in addition to combining the freshwater tank level data, freshwater tank capacity data, and data and commands set by the industrial control computer, the PLC monitoring unit also needs to combine the flow meter data measured by the outlet flow meter and control the opening and closing of the electric butterfly valve on the outlet pipeline.

8. The control method for the freshwater transport monitoring and metering system of the water supply tugboat according to claim 7, characterized in that, In manual mode, the Mimic monitoring board sends control commands to the PLC monitoring unit via RS485. The PLC monitoring unit then controls the opening and closing of the electric butterfly valve on the outlet pipeline, the opening and closing of the electric regulating butterfly valve, the opening and closing of the electric filling changeover butterfly valve, and the start and stop of the water supply pump according to the control commands. The Mimic monitoring board obtains the liquid level change rate and tank volume change value, regulating butterfly valve opening, butterfly valve opening and closing status, tank liquid level, tank water volume, outlet pressure, cumulative flow at the end of the last outlet, current cumulative outlet flow, and alarm signals calculated by the PLC monitoring unit via RS485 and displays them on the Mimic monitoring board, providing a basis for issuing control commands in manual mode.

9. The control method for the freshwater transport monitoring and metering system of the water supply tugboat according to claim 7, characterized in that, The actual still water level data is obtained by looking up a table from the liquid level dataset, including: Based on the relationship curve between liquid level and tank capacity when the tank capacity table is fitted, and the relationship dataset between liquid level data and actual liquid level corresponding to different tilt angles is obtained based on the known range and period of change of the tilt angle.

10. The control method of the freshwater transport monitoring and metering system for water supply tugboats according to claim 9, characterized in that, The calculation process for the dataset showing the relationship between the liquid level data corresponding to different tilt angles and the actual liquid level is as follows: Based on the minimum change period, the timing sampling period and calculation step size are set to calculate the critical liquid level at different tilt angles, thus obtaining the critical vertical liquid level h measured during tilt. i0 =Lsinα, α≠0, where L is the distance from the freshwater tank level sensor to the tank side wall, and the corresponding liquid level in still water is H. i0 =0.25Lsin2α; The liquid level H of this compartment in still water is obtained from the critical vertical liquid level measured during tilting. i Let h be the vertical liquid level measured in real time. i Greater than h i0 The vertical liquid level measured at this tilt angle is h. i =h i0 +Δh i Then the corresponding liquid level H in still water can be obtained. i =H i0 +Δh i cosα=0.25Lsin2α+Δh i cosα; Let h be the vertical liquid level measured in real time. i Less than h i0 The vertical liquid level measured at this tilt angle is h′. i Then the corresponding liquid level H in still water can be obtained. i =0.25(L+h) i ′ / sinα) 2 sinα / L; thus, the dataset based on the critical liquid level is calculated for different tilt angles. In practical applications, the corresponding liquid level value under static water is obtained by looking up the table based on the measured liquid level value, and then the corresponding tank capacity value is obtained.

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