Fuel Oil Viscosity Control System

00:11:17
https://www.youtube.com/watch?v=P1s_61vG58A

الملخص

TLDRThis section provides an overview of control systems, focusing on how controllers manage temperature and viscosity. It explains the function of controllers that compare measured values to desired setpoints and adjust outputs to maintain stability. The text details proportional, integral, and derivative control methods, emphasizing their roles in reducing offsets and improving system response. A specific viscosity control system for fuel oil heaters is described, including its components like differential pressure transmitters and capillary tubes, which measure viscosity and help regulate the heating process effectively.

الوجبات الجاهزة

  • 🔧 Control systems manage inputs and outputs to maintain desired conditions.
  • 🌡️ Temperature controllers adjust heating based on measured values.
  • 📏 Proportional controllers can lead to offsets in system response.
  • 📉 PI controllers help eliminate offsets over time.
  • 💧 Viscosity control systems use differential pressure to measure oil viscosity.
  • 🔄 Oscillation can occur if the proportional band is too narrow.
  • 🛠️ Magnetic couplings ensure leak-free operation in viscosity sensors.
  • 📊 Temperature correction scales aid in accurate viscosity adjustments.
  • 🔄 Laminar flow is crucial for accurate viscosity measurement.
  • ⚙️ The viscosity control system stabilizes temperature by adjusting heating methods.

الجدول الزمني

  • 00:00:00 - 00:05:00

    This section discusses control systems, specifically controllers that take a measured value, compare it to a desired value, and output a control signal to adjust a system, such as a temperature controller with a heater. The controller uses inputs from thermal detectors and adjusts the heat output to stabilize the temperature at a setpoint. The relationship between the control output and the measured temperature is illustrated, showing how proportional control can lead to an offset, which can be corrected using proportional-integral control to eliminate the offset over time.

  • 00:05:00 - 00:11:17

    The discussion then shifts to proportional-integral-derivative (PID) control, which enhances the control system's response time. The viscosity control system is detailed, explaining how it uses a differential pressure transmitter to convert oil pressure into control air pressure, which regulates the viscosity of fuel oil. The schematic of the viscosity controller is described, including its components and how it measures viscosity through a capillary tube assembly, ensuring accurate control of the heating process.

الخريطة الذهنية

فيديو أسئلة وأجوبة

  • What is a control system?

    A control system is a system that accepts a measured value as input, compares it to a desired value, and outputs a control signal to adjust a mechanism accordingly.

  • What is the purpose of a proportional controller?

    A proportional controller adjusts the output based on the difference between the measured value and the setpoint, but may result in an offset.

  • How does a PI controller differ from a proportional controller?

    A PI controller includes an integral adjustment that gradually reduces any offset to zero, improving accuracy.

  • What is the role of a differential pressure transmitter in viscosity control?

    It converts differential oil pressure to a control air pressure that varies with the measured viscosity.

  • What happens if the proportional band is set too small?

    If the proportional band is too small, the system may oscillate, leading to instability.

  • What is the function of the viscosity sensor?

    The viscosity sensor measures the viscosity of the oil by creating a differential pressure across a capillary tube.

  • What is the significance of laminar flow in viscosity measurement?

    Laminar flow ensures that the pressure differential across the capillary tube is directly proportional to the viscosity.

  • How does the viscosity control system stabilize the temperature?

    It adjusts the amount of steam, thermal oil, or electric power to the fuel heater based on the viscosity measurement.

  • What is the function of the magnetic coupling in the viscosity sensor?

    It provides leak-free power transmission and prevents overloading of the electric motor.

  • What is the purpose of the temperature correction scale in the viscosity controller?

    It helps in adjusting the supply of steam or thermal oil based on the actual temperature of the fuel.

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الترجمات
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التمرير التلقائي:
  • 00:00:00
    In this section we will look at the control system
  • 00:00:23
    controllers are systems that accept a measured value as an input compare it to
  • 00:00:28
    some desired value and then output a control signal the control signal is
  • 00:00:34
    connected to a valve or switching mechanism which will move the measured
  • 00:00:39
    value toward the desired level for instance imagine a temperature
  • 00:00:44
    controller with a heater regulated by controller input to the controller would
  • 00:00:50
    be a thermal detector like an RTD or thermocouple suppose the controller
  • 00:00:57
    calls for no heat ie zero control variable output with no heat added the
  • 00:01:05
    system would stay at a certain temperature call it t1 on the other hand
  • 00:01:11
    if the controller calls for full heat the system will eventually stabilize at
  • 00:01:16
    a higher temperature call it t4 for every intermediate control output there
  • 00:01:24
    is some stable temperature connect temperature t1 to t4 with a line that
  • 00:01:30
    illustrates the way the system responds to heat being added usually we will not
  • 00:01:36
    know what the shape of this curve is suppose we want to control the
  • 00:01:41
    temperature to a setpoint indicated by the horizontal green line labeled
  • 00:01:46
    setpoint we could design our controller so it would call for full heat if the
  • 00:01:52
    temperature is well below the setpoint no heat if it is well above the setpoint
  • 00:01:58
    and a proportionate amount in between as indicated by the dark blue line the
  • 00:02:06
    darkened bands shown is the proportional band suppose then we position the
  • 00:02:12
    proportional band evenly about the setpoint temperature since before
  • 00:02:17
    starting we don't know what the shape of the black line will be the system will
  • 00:02:22
    eventually stabilize at temperature t2 since that is the point at which the
  • 00:02:28
    system responds line intersects the controller output since t2 is above our
  • 00:02:33
    setpoint there is an offset the difference between temperatures t2
  • 00:02:39
    and the set point proportional controllers are simple but they are
  • 00:02:45
    likely to result in an offset proportional integral control is the
  • 00:02:51
    same as proportional control except an integral adjustment gradually reduces
  • 00:02:56
    the offset to zero also since the viscosity of a liquid is
  • 00:03:02
    decreased by the addition of heat or a solvent the system response line slopes
  • 00:03:08
    down with increasing control output since it is assumed that a viscosity P I
  • 00:03:13
    controller health puts is used to either heat the liquid or add solvent the
  • 00:03:19
    output has an inverse relationship between the control output and the
  • 00:03:23
    measured value ie the blue control output line slopes up to the right
  • 00:03:32
    this illustration shows an initial setting with P I viscosity control the
  • 00:03:39
    black line represents the system response to either adding heat or
  • 00:03:43
    solvent the graph illustrates the system in its initial State with an offset
  • 00:03:50
    once the system enters the band of proportional control the PI controller
  • 00:03:55
    periodically tests to determine whether the actual viscosity is above or below
  • 00:04:01
    the setpoint if it is below the proportional band is very slowly
  • 00:04:07
    adjusted upward at a rate that is slow compared to the response time of the
  • 00:04:11
    system eventually the offset is reduced to zero at which point the system
  • 00:04:17
    continues to dither above and below the setpoint by a small amount
  • 00:04:25
    if the proportional band width is reduced the response of the controller
  • 00:04:30
    will be faster and in general the offset will be smaller if the proportional band
  • 00:04:37
    is set to small the system will oscillate as a rule of thumb said the
  • 00:04:43
    proportional band as small as possible without inducing oscillations
  • 00:04:51
    to visualize the oscillation process imagine that the proportional band is
  • 00:04:56
    set to zero with temperature based control if the temperature is below the
  • 00:05:01
    setpoint the heat will be on full full heat application will continue until the
  • 00:05:08
    thermal detector reaches the setpoint temperature at that point the heat
  • 00:05:13
    application will go full off but by then the system will be overheated and will
  • 00:05:19
    overshoot the setpoint when the temperature detector cools to the
  • 00:05:24
    setpoint the heat will switch on full but by then
  • 00:05:28
    much of the system will have cooled below the setpoint the result is
  • 00:05:33
    oscillation proportional integral derivative control is similar to PI
  • 00:05:39
    control except a derivative action increases the reaction time of the
  • 00:05:44
    control system the smaller the derivative action the faster the control
  • 00:05:50
    system will be within certain limits the viscosity controller positions the steam
  • 00:05:56
    valve of the fuel oil heater directly or indirectly by adjusting the setpoint of
  • 00:06:01
    a separate slave controller the slave controller is of the PID type the
  • 00:06:07
    feedback signal to the slave controller is the mean tuber metal temperature of
  • 00:06:12
    the fuel oil heaters
  • 00:06:16
    the viscosity sensor can be mounted anyplace between the fuel oil heater and
  • 00:06:21
    Emme inlet by specification of nominal transport time delay note that the
  • 00:06:28
    actual time delay will be adjusted according to fuel oil flow the delay
  • 00:06:33
    will increase rapidly at low fuel oil flow and may then cause oscillations at
  • 00:06:40
    low load it may prove necessary to stabilize the control by reducing the
  • 00:06:45
    steam supply to the fuel oil heaters
  • 00:06:50
    here we have a schematic illustration that shows how the visco therm automatic
  • 00:06:55
    viscosity controller is built into the fuel oil system a differential pressure
  • 00:07:01
    transmitter is used which linearly converts the differential oil pressure
  • 00:07:06
    to a control air pressure varying between three and 15 psi this controller
  • 00:07:13
    air pressure which varies linearly with the viscosity measured flows to a
  • 00:07:18
    central adjustment or control panel this control system consists of the
  • 00:07:23
    following main parts control or adjustment panel viscosity reader
  • 00:07:29
    shutoff valve on the visco therm visco therm sensor electric motor fuel line
  • 00:07:35
    two fuel pump shutoff valve in fuel bypass line fine filter fuel oil pre
  • 00:07:42
    heater differential pressure transmitter steam control valve shutoff valves valve
  • 00:07:48
    for manual control compressed air supply line combined air filter and pressure
  • 00:07:54
    reducer steam supply fuel oil inlet outlet for condensate combined air
  • 00:08:01
    filter and pressure reducer the housing contains a stainless steel gear pump to
  • 00:08:07
    which a stainless steel capillary tube is connected the gear pump is driven by
  • 00:08:12
    an electric motor and continuously draws a constant amount of oil from the
  • 00:08:17
    chamber and forces it through the capillary tube as the flow through the
  • 00:08:21
    capillary tube is laminar the differential pressure across the
  • 00:08:25
    capillary tube is directly proportional to the viscosity of the oil with this
  • 00:08:31
    viscosity sensor the differential pressure is transferred to an indicator
  • 00:08:35
    and the viscosity controller the indicator scale is graded as required in
  • 00:08:41
    Redwood seconds or centistokes a temperature correction scale is provided
  • 00:08:47
    under the viscosity scale to make the adjustment of the supply of steam
  • 00:08:51
    thermal oil or electrical oil preheater easier possible pressure pulsations in
  • 00:08:59
    the fuel line can be dampened by means of the hand operated valves mount
  • 00:09:03
    under the indicator
  • 00:09:07
    the viscosity sensor consists furthermore of a housing in which is
  • 00:09:12
    mounted a capillary tube assembly as the measuring element together with a gear
  • 00:09:17
    pump an electric motor with reduction gear drives the pump in such a way that
  • 00:09:23
    the volume of oil flowing through the capillary tubes is constant as the flow
  • 00:09:29
    through the capillary assembly is laminar the pressure differential across
  • 00:09:33
    the capillary is directly proportional to the viscosity of the fuel oil
  • 00:09:40
    each capillary tube assembly consists of a glass measuring capillary in a
  • 00:09:45
    resilient stainless steel housing and a stainless steel damping capillary to
  • 00:09:50
    compensate for undue pressure waves in the fuel lines the use of a glass
  • 00:09:56
    capillary reduces the possibility of clogging by cold heavy fuel oil a
  • 00:10:02
    thermometer displays the actual fuel temperature to pressure taps are
  • 00:10:08
    provided to connect the differential pressure developed across the
  • 00:10:11
    capillaries to the differential pressure transmitter the plus tap is connected to
  • 00:10:18
    the measuring capillary and the minus tap is connected to the damping
  • 00:10:22
    capillary a magnetic coupling between viscosity sensor motor and gear pump
  • 00:10:28
    provides a leak free power transmission and prevents overloading the electric
  • 00:10:34
    motor the viscosity control station receives a zero point two to one point
  • 00:10:40
    zero bar or three to 15 psi signal from the differential pressure transmitter
  • 00:10:46
    and compares this signal with the desired setpoint viscosity value any
  • 00:10:52
    deviation between the actual viscosity and the desired viscosity results in a
  • 00:10:58
    corrective air signal to the control valve to control the amount of steam
  • 00:11:03
    thermal oil or electric power to the fuel heater
الوسوم
  • control system
  • controllers
  • temperature control
  • viscosity control
  • proportional control
  • integral control
  • derivative control
  • differential pressure transmitter
  • capillary tube
  • fuel oil heater