A method for controlling a cabin air supply and exhaust fan

Abstract

The application relates to a ship air exhaust technology field, in particular to a control method of a cabin air intake and exhaust machine, frequency of the variable frequency air supply and exhaust mechanical ventilation is very high, the variable frequency control method is optimized, the requirements of the ship owner can be met, better market can be won, the air intake and exhaust amount of the cabin is controlled through the more optimized variable frequency control method, the problem that the low-frequency work of the variable frequency air supply machine cannot meet the required air consumption of the large load working condition of the main generator in the low-temperature environment of the cabin in winter is solved, and the method is suitable for the SOV ship type with small space and compact layout.

Description

Technical Field

[0001] This invention relates to the field of ship ventilation technology, and in particular to a control method for engine room intake and exhaust fans. Background Technology

[0002] Marine mechanical ventilation is an important component of marine propulsion. It provides sufficient air to form an airflow to ensure that the main engine, air compressor, incinerator and other main and auxiliary equipment operate in good condition and maintain a good working environment in the engine room, thus determining whether the marine propulsion system can operate normally.

[0003] The nacelle ventilation is designed according to the ISO8861 standard and meets relevant specifications and requirements. According to the specifications of Shanghai Electric SOV wind power operation and maintenance mother ship, the nacelle temperature should not be higher than 10℃ or 55℃ above the outside temperature. The nacelle should have a slight positive pressure, generally not exceeding +50Pa. The ventilation volume is determined by the sum of the air volume required for the main generator set combustion and the air volume required to ensure the temperature rise of the nacelle.

[0004] Existing cabin ventilation solution 1: Using mechanical air supply and natural exhaust, the cabin is equipped with one or more air supply fans. Through the air pressure and thermal pressure difference between the cabin and the outside, the hot air inside the cabin is discharged from the exhaust port, thereby forming air flow.

[0005] The natural ventilation system design in the above scheme needs to fully consider the design of the exhaust outlet and air duct, and must plan a suitable location to avoid local high temperature caused by airflow short circuit. Therefore, it has great limitations on ships with very tight space, such as PSV and SOV. Secondly, it is ventilated by natural wind pressure and thermal pressure, which is easily affected by environmental factors.

[0006] Another engine room ventilation solution is the second option: mechanical air supply and exhaust, which involves installing one or more supply and exhaust fans in the engine room for air supply and exhaust. This solution uses one or more variable frequency supply and exhaust fans in the engine room. The main problem with this traditional solution is that in low-temperature winters, if the airflow of the supply fans is controlled solely by temperature sensors located in the engine room area, the fans may operate at low frequencies under heavy ship loads due to the low temperature. This can fail to meet the main engine's air consumption requirements, leading to main engine derating or even shutdown. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a control method for the intake and exhaust fans of the engine room, which addresses the issue that the low-frequency operation of the variable frequency fans in the engine room during winter (usually around 5°C) cannot meet the air consumption required by the main generator under high load conditions, and how to control the intake and exhaust air volume of the engine room through a more optimized variable frequency control method.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a control method for engine room intake and exhaust fans, applicable to controlling engine room intake and exhaust fan systems. Its innovation lies in the following: the engine room intake and exhaust fan system includes one variable frequency drive (VFD) fan with 50% rated power, one dual-speed drive (DSW) fan with 50% rated power, and two VFD exhaust fans with 100% rated power. Four main generators are installed in the engine room. The two VFD exhaust fans are arranged side-by-side on one side of the engine room, each connected to the engine room via a damper. Two temperature sensors are installed near the VFD exhaust fans in the engine room. The VFD fan and the DSW fan are arranged side-by-side on the other side of the engine room. The VFD fan is connected to the engine room via a first intake damper, and the DSW fan is connected to the engine room via a second intake damper. Two differential pressure sensors are installed at adjacent locations in the engine room. The control method for the engine room intake and exhaust fan system includes the following steps:

[0009] S1: Power on the variable frequency blower and the dual-speed blower;

[0010] S2: Check whether the corresponding No. 1 and No. 2 air intake dampers are open. If No. 1 air intake damper is successfully opened, start the variable frequency blower after a 30-second delay and proceed to S3; if No. 2 air intake damper is also successfully opened, start the dual-speed blower after a 30-second delay and proceed to S4.

[0011] S3: The variable frequency blower is turned on at full power to the maximum power, and then the air supply of the variable frequency blower is determined by taking the larger value of the constant static pressure method and constant temperature method according to the PLC. The frequency is gradually reduced to the off state or the variable frequency air supply continues as needed.

[0012] S4: After the dual-speed blower is turned on, it will run at low speed first. After the variable frequency blower in S3 reaches its maximum power, the dual-speed blower will start running at high speed.

[0013] S5: After the ship stops operating, disconnect the power supply, and the variable frequency blower and dual-speed blower will stop.

[0014] The operating frequency of the variable frequency exhaust fan is automatically adjusted according to the set average pressure of the nacelle, and the operating frequency of the variable frequency supply fan is automatically adjusted according to the set average temperature of the nacelle.

[0015] Furthermore, the dual-speed blower can be manually selected for low-speed or high-speed control. This ensures that using the low-speed blower during berthing or other low-load conditions saves fuel and reduces noise.

[0016] Furthermore, the constant static pressure method involves PID calculation and adjustment of the nacelle fan's operating frequency based on the measured average pressure difference in the nacelle and the set pressure difference to ensure stable positive pressure within the nacelle. The set pressure difference value is 50 Pa, which can be adjusted as needed. When the pressure difference sensor malfunctions, the operating frequency is set to the fan's minimum operating frequency of 30 Hz.

[0017] Furthermore, the constant temperature method: the operating frequency of the nacelle fan will be calculated and adjusted by PID based on the measured average temperature of the nacelle and the set temperature to ensure that the temperature of the nacelle is controlled within the set value. When the temperature sensor fails, the operating frequency will be set to the minimum operating frequency of the fan, 30Hz.

[0018] Furthermore, the set differential pressure value is 50 Pa, and the minimum operating frequency of the fan is 30 Hz.

[0019] The advantages of this invention are:

[0020] The frequency of variable frequency mechanical ventilation used in this invention is very high. By optimizing the variable frequency control method, it can better meet the requirements of ship owners and win a better market. By using a more optimized variable frequency control method to control the intake and exhaust air volume of the engine room, the problem of the variable frequency fan not being able to meet the air consumption required by the main generator under the high load conditions in the low temperature environment of the engine room during winter is solved. It is suitable for SOV ships with limited space and compact layout. Attached Figure Description

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] Figure 2 This is a diagram of the control method of the present invention. Detailed Implementation

[0024] like Figures 1 to 2 The method shown is a control method for the engine room intake and exhaust fans, which is applicable to controlling the engine room intake and exhaust fan system of the Shanghai Electric SOV 60P wind power maintenance mother ship.

[0025] The nacelle intake and exhaust fan system includes one variable frequency supply fan 2 with a rated power of 50%, one dual-speed supply fan 3 with a rated power of 50%, and two variable frequency exhaust fans 4 with a rated power of 100%. Four main generators 1 are installed in the nacelle 5. The two variable frequency exhaust fans 4 are arranged side by side on one side of the nacelle 5 and are connected to the nacelle 5 through an air damper 10. Two temperature sensors 6 are installed in the nacelle 5 near the variable frequency exhaust fans 4. The variable frequency supply fan 2 and the dual-speed supply fan 3 are arranged side by side on the other side of the nacelle 5. The variable frequency supply fan 2 is connected to the nacelle 5 through an air damper 8, and the dual-speed supply fan 3 is connected to the nacelle 5 through an air damper 9. Two differential pressure sensors 7 are installed at adjacent locations in the nacelle.

[0026] The control method for the nacelle's 5-stage intake and exhaust fan system includes the following steps:

[0027] S1: Connect the variable frequency blower 2 and the dual-speed blower 3 to the main generator 1;

[0028] S2: Check whether the corresponding No. 1 air intake damper 8 and No. 2 air intake damper 9 are open. If No. 1 air intake damper 8 is successfully opened, start the variable frequency blower 2 after a 30-second delay and proceed to S3; if No. 2 air intake damper 9 is also successfully opened, start the dual-speed blower 3 after a 30-second delay and proceed to S4.

[0029] S3: The variable frequency blower 2 is turned on at full power to the maximum power. Then, the air supply of the variable frequency blower 2 is determined by taking the larger value of the constant static pressure method and constant temperature method according to the PLC. The frequency is gradually reduced to the off state or the variable frequency air supply continues as needed.

[0030] Constant static pressure method: The operating frequency of the fan in nacelle 5 is calculated and adjusted using PID control based on the measured average pressure difference in nacelle 5 and the set pressure difference to ensure stable positive pressure within nacelle 5. (The set value is 50Pa, which can be adjusted as needed). When the pressure difference sensor fails, the operating frequency is set to the fan's minimum operating frequency of 30Hz.

[0031] Temperature control method: The operating frequency of the fan in nacelle 5 will be calculated and adjusted by PID based on the measured average temperature of nacelle 5 and the set temperature (the set temperature value of nacelle 5 can be adjusted according to factors such as load changes and seasonal changes in nacelle 5, such as setting it at 42℃) to ensure that the temperature of nacelle 5 is controlled within the set value. When the temperature sensor 6 fails, the operating frequency will be set at the minimum operating frequency of the fan, 30Hz.

[0032] The variable frequency control of the variable frequency blower 2 and the dual-speed blower 3 compares the greater demand for temperature and pressure. The PLC calculates and outputs the larger value to the frequency converter, which then operates at the corresponding frequency based on the given signal value. Through calculation and control, the positive pressure and temperature of the nacelle 5 are effectively controlled to achieve the set effects. For example, if the pressure inside the nacelle 5 is 50 Pa and the temperature is 60 °C, the pressure requirement is met, but the temperature requirement is not. Based on the temperature requirement, a constant temperature method is used to calculate the given frequency for the blower. The exhaust fan is controlled according to the pressure inside the nacelle 5.

[0033] S4: After the dual-speed blower 3 is turned on, it will run at low speed first. After the variable frequency blower 2 in S3 runs to its maximum power, it will run at high speed.

[0034] S5: After the ship stops operating, the power supply is disconnected, and the variable frequency blower 2 and the dual-speed blower 3 stop.

[0035] During the operation of this control method, if a communication failure occurs between the central control unit and the frequency converter, all fans will continue to operate according to the instructions given before the failure. If a communication failure occurs between the central control unit and temperature sensor 6 & differential pressure sensor 7, all fans will continue to operate at full speed.

[0036] The operating frequency of the variable frequency exhaust fan 4 is automatically adjusted according to the set average pressure of the nacelle 5, and the operating frequency of the variable frequency supply fan 2 is automatically adjusted according to the set average temperature of the nacelle 5.

[0037] In addition, the dual-speed blower 3 allows for manual selection of low and high speed control. This ensures that the low-speed blower can be used to save fuel and reduce noise during port operations or other low-load conditions.

[0038] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A control method for engine room intake and exhaust fans, applicable to controlling engine room intake and exhaust fan systems, characterized in that: The nacelle intake and exhaust fan system includes one variable frequency supply fan with 50% rated power, one dual-speed supply fan with 50% rated power, and two variable frequency exhaust fans with 100% rated power. Four main generators are installed in the nacelle. The two variable frequency exhaust fans are arranged side-by-side on one side of the nacelle, each connected to the nacelle via a damper. Two temperature sensors are installed near the variable frequency exhaust fans in the nacelle. The variable frequency supply fan and the dual-speed supply fan are arranged side-by-side on the other side of the nacelle. The variable frequency supply fan is connected to the nacelle via a first intake damper, and the dual-speed supply fan is connected to the nacelle via a second intake damper. Two differential pressure sensors are installed adjacent to each other in the nacelle. The control method for the nacelle intake and exhaust fan system includes the following steps: S1: Power on the variable frequency blower and the dual-speed blower; S2: Check whether the corresponding No. 1 and No. 2 air intake dampers are open. If No. 1 air intake damper is successfully opened, start the variable frequency blower after a 30-second delay and proceed to S3; if No. 2 air intake damper is also successfully opened, start the dual-speed blower after a 30-second delay and proceed to S4. S3: The variable frequency blower is turned on at full power to the maximum power, and then the air supply of the variable frequency blower is determined by taking the larger value of the constant static pressure method and constant temperature method according to the PLC. The frequency is gradually reduced to the off state or the variable frequency air supply continues as needed. S4: After the dual-speed blower is turned on, it will run at low speed first. After the variable frequency blower in S3 reaches its maximum power, the dual-speed blower will start running at high speed. S5: After the ship stops operating, disconnect the power supply, and the variable frequency blower and dual-speed blower will stop. The operating frequency of the variable frequency exhaust fan is automatically adjusted according to the set average pressure of the cabin, and the operating frequency of the variable frequency supply fan is automatically adjusted according to the set average temperature of the cabin. The constant static pressure method: The operating frequency of the nacelle fan is calculated and adjusted by PID based on the measured average pressure difference in the nacelle and the set pressure difference to ensure the stability of the positive pressure in the nacelle; The constant temperature method: The operating frequency of the nacelle fan will be calculated and adjusted by PID based on the measured average temperature of the nacelle and the set temperature to ensure that the temperature of the nacelle is controlled within the set value. When the temperature sensor fails, the operating frequency will be set to the lowest operating frequency of the fan.

2. The method for controlling the intake and exhaust fans of an engine room according to claim 1, characterized in that: The dual-speed blower can be manually selected for low-speed or high-speed control.

3. The method for controlling the intake and exhaust fans of an engine room according to claim 1, characterized in that: The set differential pressure value is 50Pa, and the minimum operating frequency of the fan is 30Hz.

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