Oil tank heating device and lubricating oil system

Abstract

The utility model discloses an oil tank heating device and a lubricating oil system, and relates to the field of electric power, the oil tank heating device comprises a temperature detection module, the temperature detection module is respectively connected with an oil tank in a steam turbine lubricating oil system and an automatic control end of a controller, and is used for detecting the temperature of the oil tank; the delay module is respectively connected with the state feedback end of the heater and the protection control end of the controller and is used for outputting a heating stopping signal at a first preset time after the heater is started, so that the controller controls the heater to stop heating; the instruction output end of the controller is connected with the control end of the heater, and the controller is used for controlling the heater based on the temperature and the heating stopping signal; and the heater is used for heating the oil tank according to the instruction received by the control end. The controller can control the heater to heat according to the temperature of the oil tank, the delay module is also arranged to control the heater to stop heating within the first preset time after heating is started, and subsequent faults caused by excessive heating of the oil tank can be avoided.

Description

Technical Field

[0001] The utility model relates to the field of electricity, in particular to an oil tank heating device and a lubricating oil system. Background Art

[0002] In the electric power industry, in power generation enterprises with a long history and outdated equipment, the lubricating oil in the lubricating oil tank of the lubricating oil system of the steam turbine needs to be heated, wherein the lubricating oil system also includes pipelines, pumps and valves, etc. In the related art, a temperature measuring device is set in the lubricating oil tank to detect the temperature, and the detected temperature is output to the controller. If the temperature is lower than the first temperature, the controller controls the heater to start heating the lubricating oil tank, and if the temperature is higher than the second temperature, the controller controls the heater to stop heating the lubricating oil tank, and the second temperature is higher than the first temperature. In the related art, there is a case where the temperature measuring device fails, causing the heater to continue to heat, and the temperature of the lubricating oil continues to rise, which will increase the temperature of the turbine bearing and trip the turbine protection. There is even a fire accident caused by the failure of the heater temperature measuring device, which causes the heater to continue to heat, and finally causes damage to the steam turbine. Therefore, it is necessary to more accurately control the heater in the lubricating oil tank to achieve stable heating of the lubricating oil. Utility Model Content

[0003] The utility model aims to provide an oil tank heating device and a lubricating oil system, which can avoid overheating of the oil tank and cause subsequent failures.

[0004] In order to solve the above technical problems, the utility model provides a fuel tank heating device, comprising:

[0005] A temperature detection module, the temperature detection module is respectively connected to the oil tank in the lubricating oil system of the steam turbine and the automatic control end of the controller, and is used to detect the temperature of the oil tank;

[0006] A delay module, the delay module is connected to the state feedback end of the heater and the protection control end of the controller respectively, and is used to output a stop heating signal at a first preset time after the heater is started, so that the controller controls the heater to stop heating;

[0007] The controller, wherein the command output terminal of the controller is connected to the control terminal of the heater, and is used to control the heater based on the temperature and the stop heating signal;

[0008] The heater is used to heat the oil tank according to the instruction received by the control end.

[0009] On the other hand, the temperature detection module includes a temperature detector, an automatic start signal generator and an automatic stop signal generator;

[0010] The control end of the automatic start signal generator is connected to the output end of the temperature detector, and the output end of the automatic start signal generator is connected to the protection control end of the controller, for outputting an automatic start signal to the controller so that the heater is started;

[0011] The control end of the automatic stop signal generator is connected to the output end of the temperature detector, and the output end of the automatic stop signal generator is connected to the protection control end of the controller, for outputting an automatic stop signal to the controller so that the heater stops;

[0012] The temperature detector is used to detect the temperature of the oil tank.

[0013] On the other hand, it also includes the power circuit;

[0014] The first end of the power circuit is connected to a three-phase power supply, and the second end of the power circuit is connected to a power supply end of the heater, so as to conduct the first end and the second end to supply power to the heater.

[0015] On the other hand, the power circuit includes contacts of a switch and a contactor;

[0016] The first end of the switch is connected to a three-phase power supply, the second end of the switch is connected to a first end of a contact of the contactor, and the second end of the contact of the contactor is connected to a power supply end of the heater;

[0017] The contacts of the contactor are used to close when the coil of the contactor is energized to supply power to the heater.

[0018] On the other hand, the power circuit further includes a first fuse;

[0019] The first end of the first fuse is connected to the second end of the switch, and the second end of the first fuse is connected to the first end of the contact of the contactor for protecting the circuit.

[0020] On the other hand, it also includes the control loop;

[0021] The output end of the control loop is connected to the control end of the power loop, the control end of the control loop is connected to the controller, and the control loop is used to control the power loop to be turned on or off.

[0022] On the other hand, the control circuit includes the coil of the contactor, a start command switch and a stop command switch;

[0023] The coil of the contactor, the start command switch and the stop command switch are connected in series and then connected to the three-phase power supply;

[0024] The start command switch is used to close so that the coil of the contactor is energized, and the stop command switch is used to open so that the coil of the contactor is deenergized.

[0025] On the other hand, the control circuit further includes a second fuse;

[0026] The first end and the second end of the second fuse are both connected to the three-phase power supply for protecting the circuit.

[0027] On the other hand, the delay module is a time-delay relay;

[0028] The time delay relay is used to open at a first preset time point after the heater is started to output a heating stop signal.

[0029] In order to solve the above technical problems, the utility model also provides a lubricating oil system, including the above oil tank heating device and an oil tank.

[0030] The utility model discloses an oil tank heating device and a lubricating oil system, which relates to the field of electric power, and includes a temperature detection module, which is respectively connected to the oil tank in the lubricating oil system of a steam turbine and the automatic control end of a controller, and is used to detect the temperature of the oil tank; a delay module, which is respectively connected to the state feedback end of the heater and the protection control end of the controller, and is used to output a stop heating signal at the first preset time after the heater is started, so that the controller controls the heater to stop heating; a controller, whose command output end is connected to the control end of the heater, and is used to control the heater based on the temperature and the stop heating signal; and a heater, which is used to heat the oil tank according to the command received by the control end. The controller can control the heater to heat according to the temperature of the oil tank, and also sets a delay module to control the heater to stop heating within the first preset time after the heating starts, so as to avoid overheating of the oil tank and cause subsequent failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 The utility model is a structural schematic diagram of an oil tank heating device provided by the utility model.

[0033] Figure 2 This is a structural schematic diagram of another oil tank heating device provided by the utility model. DETAILED DESCRIPTION

[0034] The core of the utility model is to provide an oil tank heating device and a lubricating oil system, which can avoid excessive heating of the oil tank and cause subsequent failures.

[0035] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] In the power industry, power generation companies with old equipment have experienced a failure in the temperature measurement device in the remote heater of the auxiliary machine's lubricating oil tank, which caused the heater to continue heating, resulting in high lubricating oil temperature and then causing the auxiliary machine to trip, affecting the stable operation of the generator set. There have even been cases where the heater temperature measurement device failed, causing the heater to continue heating and causing fire accidents, ultimately leading to equipment damage. Therefore, it is necessary to more accurately control the heater of the oil tank to achieve stable heating of the lubricating oil.

[0037] Figure 1 A schematic diagram of the structure of a fuel tank heating device provided by the utility model includes:

[0038] A temperature detection module 1, which is connected to the oil tank in the lubricating oil system of the steam turbine and the automatic control end of the controller 3, and is used to detect the temperature of the oil tank;

[0039] The delay module 2 is connected to the state feedback end of the heater 4 and the protection control end of the controller 3 respectively, and is used to output a stop heating signal at a first preset time after the heater 4 is started, so that the controller 3 controls the heater 4 to stop heating;

[0040] A controller 3, wherein a command output terminal of the controller 3 is connected to a control terminal of the heater 4, and is used to control the heater 4 based on the temperature and a heating stop signal;

[0041] The heater 4 is used to heat the fuel tank according to the instruction received by the control end.

[0042] The temperature detection module 1 is pre-set with an upper threshold and a lower threshold. According to the set lower threshold, when the temperature of the detected oil tank is lower than the lower threshold, the lower limit (L) alarm is triggered, and the automatic start port of the controller 3 controls the heater 4 to start after receiving the signal; according to the set upper threshold, when the temperature of the detected oil tank is higher than the upper threshold, the upper limit (H) alarm is triggered, and the automatic stop port of the controller 3 controls the heater 4 to stop running after receiving the signal. The temperature detection module 1 realizes automatic control of the start and stop of the heater 4. It should also be noted that the process of automatic control of the heater 4 according to the temperature detection module 1 is the same as the prior art, and the present application does not improve it.

[0043] Considering that the oil tank cannot be overheated, the present application sets a delay module 2. After the delay module 2 determines that the heater 4 returns to the operating state, it starts timing, and sends a signal to the protection stop port of the controller 3 after the first preset time, and then the controller 3 controls the heater 4 to stop running. Therefore, the heating time of the heater 4 will not exceed the first preset time, thus avoiding the problem of overheating.

[0044] For heater 4, the state feedback end of heater 4 will return three signals to controller 3, namely, running state, stop state and remote / local switching state, which respectively indicate that the current working state of heater 4 is running, stop, and remote / local switching state. Heater 4 heats or stops working according to the control instruction output by controller 3. Remote control of heater 4 can be realized through controller 3, without on-site control, which is more convenient.

[0045] For the controller 3, the state returned by the heater 4 is received through the state monitoring end, and then the working state of the heater 4 is confirmed. The controller determines whether the current heater 4 is in the running state, the stopped state, the remote state or the local state according to the signal returned by the state feedback end. When the heater 4 is in the running state, the controller will not send a start instruction to the heater 4, and when the heater 4 is in the stopped state, the controller will not send a stop instruction to the heater 4. When the heater 4 is in the remote state, the start and stop of the heater are controlled by the controller 3, and the user cannot control it manually. When the heater 4 is in the local state, the start and stop of the heater are controlled by the user, and the controller 3 does not control it. The above process is the same as the prior art, and this application has not made any improvements. The protection control end of the controller 3 is connected to the delay module 2, and the delay module 2 outputs a stop signal to the controller 3 after the first preset time after the heater 4 starts heating. At this time, the controller 3 controls the heater 4 to stop running. In addition, the port will also receive other protection stop signals, such as other protection conditions to control the heater 4 to stop running. No matter what condition triggers, the protection control end of the controller 3 will control the heater 4 to stop heating after receiving the signal. When the automatic stop port of the controller 3 receives a signal, it indicates that the current temperature of the fuel tank exceeds the preset 30 degrees Celsius, and the heater 4 needs to be controlled to stop heating. When the automatic start port of the controller 3 receives a signal, it indicates that the current temperature of the fuel tank is lower than the preset 5 degrees Celsius, and the heater 4 needs to be controlled to start heating.

[0046] The utility model discloses an oil tank heating device, which relates to the field of electric power, and includes a temperature detection module, which is respectively connected to the oil tank in the steam turbine lubricating oil system and the automatic control end of the controller, and is used to detect the temperature of the oil tank; a delay module, which is respectively connected to the state feedback end of the heater 4 and the protection control end of the controller, and is used to output a stop heating signal at the first preset time after the heater 4 is started, so that the controller controls the heater 4 to stop heating; a controller, whose instruction output end is connected to the control end of the heater 4, and is used to control the heater 4 based on the temperature and the stop heating signal; the heater 4 is used to heat the oil tank according to the instruction received by the control end. The controller can control the heater 4 to heat according to the temperature of the oil tank, and also sets the delay module to stop controlling the heater 4 to heat within the first preset time after the heating starts, so as to avoid overheating of the oil tank and cause subsequent failures.

[0047] Based on the above embodiments:

[0048] Figure 2 A schematic diagram of the structure of another fuel tank heating device provided by the utility model;

[0049] Among them, HTR is the heater 4.

[0050] In some embodiments, the temperature detection module 1 includes a temperature detector, an automatic start signal generator, and an automatic stop signal generator;

[0051] The control end of the automatic start signal generator is connected to the output end of the temperature detector, and the output end of the automatic start signal generator is connected to the protection control end of the controller 3, for outputting the automatic start signal to the controller 3 so that the heater 4 is started;

[0052] The control end of the automatic stop signal generator is connected to the output end of the temperature detector, and the output end of the automatic stop signal generator is connected to the protection control end of the controller 3, for outputting the automatic stop signal to the controller 3 so that the heater 4 stops;

[0053] The temperature sensor is used to detect the temperature of the fuel tank.

[0054] According to actual needs, this application pre-sets the lower limit threshold to 5 degrees Celsius and the upper limit threshold to 30 degrees Celsius. The upper limit threshold and the lower limit threshold are pre-set in the temperature detection module 1. According to the set lower limit threshold (LOSP = 5 degrees Celsius), when the detected temperature of the oil tank is lower than 5 degrees Celsius, the lower limit (L) alarm is triggered and the signal is sent to the pulse block. After the automatic start port of the controller 3 receives the signal, it will control the heater 4 to start; according to the set upper limit threshold (HISP = 30 degrees Celsius), when the detected temperature of the oil tank is higher than 30 degrees Celsius, the upper limit (H) alarm is triggered and the signal is sent to the pulse block. After receiving the signal, the automatic stop port of the controller 3 will control the heater 4 to stop running. The temperature detection module 1 realizes the automatic start and stop control of the heater 4. The automatic start signal generator and the automatic stop signal generator are both pulse blocks. After receiving the control instruction, the pulse block sends a 3-second pulse to the control driver automatic start entrance according to the set time (TARG).

[0055] In some embodiments, further comprising a power circuit;

[0056] The first end of the power circuit is connected to a three-phase power supply, and the second end of the power circuit is connected to a power supply end of the heater 4 , so as to conduct the first end with the second end to supply power to the heater 4 .

[0057] The heater 4 is powered by a three-phase power supply, and the three-phase power supplies L1, L2 and L3 are connected to the heater 4. Considering that the heater 4 is not heated in real time, a power circuit is set, and the first end of the power circuit is connected to the three-phase power supply, and the second end of the power circuit is connected to the heater 4. When the heater 4 needs to heat the oil tank, the power circuit needs to connect the first end with the second end, and then the three-phase power supply supplies power to the heater 4, and the heater 4 can start working to heat the oil tank. When the heater 4 does not need to heat the oil tank, the power circuit needs to disconnect the first end from the second end, and then the three-phase power supply does not supply power to the heater 4, and the heater 4 can stop working, that is, stop heating the oil tank.

[0058] In some embodiments, the power circuit includes a switch Q and a contact KM1 of the contactor;

[0059] A first end of the switch Q is connected to a three-phase power supply, a second end of the switch Q is connected to a first end of a contact KM1 of a contactor, and a second end of the contact KM1 of the contactor is connected to a power supply end of the heater 4;

[0060] The contact KM1 of the contactor is used to close when the coil KM of the contactor is energized to supply power to the heater 4 .

[0061] In the present application, the power circuit is provided with a switch Q and a contactor KM1. For example, after the auxiliary machine starts to run, the switch Q may be closed when it is necessary to heat the oil tank. After the auxiliary machine stops running, it is not necessary to heat the oil tank, and the switch Q can be disconnected at this time. The contactor's contact KM1 is turned on or off according to whether the contactor's coil KM is energized or not. Whether the contactor's coil KM is energized is controlled by the controller 3, that is, the controller 3 directly controls the contactor's coil KM to gain or lose power, and indirectly controls whether the contactor's contact KM1 is closed, thereby realizing whether the heater 4 is powered.

[0062] In some embodiments, the power circuit further includes a first fuse FU1;

[0063] A first end of the first fuse FU1 is connected to a second end of the switch Q, and a second end of the first fuse FU1 is connected to a first end of a contact KM1 of the contactor, for protecting the circuit.

[0064] In order to protect the circuit, if the heater 4 fails or other components in the circuit fail, it may easily lead to problems such as line short circuit. The present application sets a first fuse FU1 in the power circuit. The first fuse FU1 can disconnect the circuit in time after the fault occurs to avoid subsequent larger faults caused by component failure, thereby improving the safety of the circuit.

[0065] In some embodiments, further comprising a control loop;

[0066] The output end of the control loop is connected to the control end of the power loop, and the control end of the control loop is connected to the controller 3. The control loop is used to control the power loop to be turned on or off.

[0067] Considering that it is inconvenient for the user to control the heater 4 locally, a remote control method is provided. In order to achieve remote control, a control circuit is set to control the power circuit. The control circuit can realize whether the three-phase power supply supplies power to the heater 4 by whether the first end and the second end of the power circuit are conductive, thereby realizing the heating control of the heater 4.

[0068] Specifically, after the switch Q of the power circuit is closed, the control circuit can realize the turning on and off of the power circuit by controlling the turning on and off of the contact KM1 of the contactor of the power circuit.

[0069] In some embodiments, the control circuit includes a contactor coil KM, a start command switch SB1, and a stop command switch SB2;

[0070] The contactor coil KM, the start command switch SB1 and the stop command switch SB2 are connected in series and then connected to a three-phase power supply;

[0071] The start command switch SB1 is used to close so that the coil KM of the contactor is energized, and the stop command switch SB2 is used to open so that the coil KM of the contactor is de-energized.

[0072] The start command switch SB1 is a normally open switch. After the controller 3 sends a start command, the start command switch SB1 is controlled to close, and then the coil KM of the contactor is energized, the contact KM1 of the contactor is closed, and the three-phase power supply supplies power to the heater 4; the stop command switch SB2 is a normally closed switch. When the controller 3 sends a stop command, it is disconnected, and then the coil KM of the contactor is de-energized, the contact KM1 of the contactor is disconnected, and the three-phase power supply stops supplying power to the heater 4.

[0073] By outputting a start command to the start command switch SB1 or a stop command to the stop command switch SB2 through the controller 3, the power gain and loss of the contactor's coil KM is controlled, thereby controlling whether the contactor's contact KM1 is closed, and finally controlling the power supply to the heater 4.

[0074] It should be noted that both the start command switch SB1 and the stop command switch SB2 can be manually controlled. When the user selects the local control logic, both switches are directly pressed by the user to achieve the control of the power on and off of the contactor coil KM. Under the remote control logic, the start command switch SB1 and the stop command switch SB2 are controlled by the controller 3 and cannot be manually controlled by the user.

[0075] In some embodiments, the control circuit further includes a second fuse FU2;

[0076] The first end and the second end of the second fuse FU2 are both connected to a three-phase power supply for protecting the circuit.

[0077] In order to protect the circuit, if the heater 4 fails or other components in the circuit, such as the start command switch SB1 and the stop command switch SB2, fail, it may easily lead to problems such as line short circuit. In this application, a second fuse FU2 is set in the control loop. The second fuse FU2 can disconnect the circuit in time after the fault occurs, so as to avoid subsequent larger faults caused by component failure, thereby improving the safety of the circuit.

[0078] In some embodiments, the delay module 2 is a delay relay SB3;

[0079] The time delay relay SB3 is used to be disconnected at a first preset time after the heater 4 is started, so as to output a heating stop signal.

[0080] Specifically, the time delay relay SB3 is used to disconnect after the first preset time to cut off the power supply to the heater 4. When the operation status display sends a signal, the delayed closure (TD-ON) will be triggered; when the delayed closure (TD-ON) receives the trigger signal, it will delay 1800 seconds according to the set time (TARG) and send a signal to the pulse block; when the pulse block sends a 3-second pulse according to the set time (TARG), it sends a signal to "OR"; when the signal is transmitted to the protection stop entrance of the control driver through "OR", when the drive controller 3 receives the protection stop signal, it sends a stop command to stop the heater 4. The time delay relay SB3 is added in series in the control loop (the time is also set to 1800 seconds), so that if the loop is powered on, it has a delayed disconnection function after a delay of 1800 seconds regardless of remote control or local control.

[0081] The present application also provides a lubricating oil system, comprising the above-mentioned oil tank heating device and an oil tank.

[0082] For an introduction to the lubricating oil system provided in this application, please refer to the above-mentioned embodiments, which will not be described in detail here.

[0083] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0084] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, article or device including the element.

[0085] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fuel tank heating device, characterized in that: include: A temperature detection module, the temperature detection module is respectively connected to the oil tank in the lubricating oil system of the steam turbine and the automatic control end of the controller, and is used to detect the temperature of the oil tank; A delay module, the delay module is connected to the state feedback end of the heater and the protection control end of the controller respectively, and is used to output a stop heating signal at a first preset time after the heater is started, so that the controller controls the heater to stop heating; The controller, wherein the command output terminal of the controller is connected to the control terminal of the heater, and is used to control the heater based on the temperature and control the heater to stop operating upon receiving the stop heating signal; The heater is used to heat the oil tank according to the instruction received by the control end; The delay module is a delay relay; The time delay relay is used to disconnect at a first preset time after the heater is started to output a heating stop signal.

2. The fuel tank heating device according to claim 1, characterized in that: The temperature detection module includes a temperature detector, an automatic start signal generator and an automatic stop signal generator; The control end of the automatic start signal generator is connected to the output end of the temperature detector, and the output end of the automatic start signal generator is connected to the protection control end of the controller, for outputting an automatic start signal to the controller so that the heater is started; The control end of the automatic stop signal generator is connected to the output end of the temperature detector, and the output end of the automatic stop signal generator is connected to the protection control end of the controller, for outputting an automatic stop signal to the controller so that the heater stops; The temperature detector is used to detect the temperature of the oil tank.

3. The fuel tank heating device according to claim 1, characterized in that: Also includes a power circuit; The first end of the power circuit is connected to a three-phase power supply, and the second end of the power circuit is connected to a power supply end of the heater, so as to conduct the first end and the second end to supply power to the heater.

4. The fuel tank heating device according to claim 3, characterized in that: The power circuit includes contacts of a switch and a contactor; The first end of the switch is connected to a three-phase power supply, the second end of the switch is connected to a first end of a contact of the contactor, and the second end of the contact of the contactor is connected to a power supply end of the heater; The contacts of the contactor are used to close when the coil of the contactor is energized to supply power to the heater.

5. The fuel tank heating device according to claim 4, characterized in that: The power circuit also includes a first fuse; The first end of the first fuse is connected to the second end of the switch, and the second end of the first fuse is connected to the first end of the contact of the contactor for protecting the circuit.

6. The fuel tank heating device according to claim 3, characterized in that: Also includes control loop; The output end of the control loop is connected to the control end of the power loop, the control end of the control loop is connected to the controller, and the control loop is used to control the power loop to be turned on or off.

7. The fuel tank heating device according to claim 6, characterized in that: The control circuit includes a contactor coil, a start command switch and a stop command switch; The coil of the contactor, the start command switch and the stop command switch are connected in series and then connected to the three-phase power supply; The start command switch is used to close so that the coil of the contactor is energized, and the stop command switch is used to open so that the coil of the contactor is deenergized.

8. The fuel tank heating device according to claim 7, characterized in that: The control circuit also includes a second fuse; The first end and the second end of the second fuse are both connected to the three-phase power supply for protecting the circuit.

9. A lubricating oil system, characterized in that: The oil tank heating device comprises the oil tank heating device as claimed in any one of claims 1 to 8, and also comprises an oil tank.

Images