Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B37/00—Component parts or details of steam boilers
  • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
  • F22B37/38—Determining or indicating operating conditions in steam boilers, e.g. monitoring direction or rate of water flow through water tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B35/00—Control systems for steam boilers

Definitions

• steam is most commonly used in a heat exchanger for heating the process fluid.
• To control the temperature of the process fluid at the outlet of the heat exchanger it is necessary to control the flow rate of steam.
• the conventional method to control the flow rate is by controlling the temperature alone.
• the conventional devices for limiting the downstream pressure of steam supplied to process works with the help of one fluid parameter at a time.
• the parameters include i.e., either temperature or pressure or flow rate.
• the conventional apparatus comprises a steam flow meter which measures the flow rate of the steam let in the device.
• the device further comprises a pressure reducing valve for reducing the pressure of the steam.
• a first controller and a first position sensor are coupled to the valve to sense and control the pressure reducing valve based on the pressure.
• the device also comprises a temperature reducing valve that is coupled to a second sensor and a second position to position the temperature reducing valve based on the sensed temperature of the steam.
• An object of the present disclosure is to provide a device for controlling steam flow in a steam line.
• Another object of the present disclosure is to provide a device for controlling steam flow in a steam line while ensuring prevention of loss of steam.
• the present disclosure envisages a device, of the present disclosure for controlling steam flow in a steam line in a steam line.
• the steam line is employed for a heat exchanger.
• the device includes a control valve, at least one first pressure sensing unit, control unit and an actuator.
• the control valve is configured to be positioned along the steam line.
• the pressure sensing unit is positioned upstream of the control valve.
• the first pressure sensing unit is configured to sense the pressure of steam at an inlet of the control valve, and is further configured to generate a first sensed pressure value.
• the temperature sensing unit is provided downstream of the heat exchanger.
• the temperature sensing unit is configured to sense the temperature of fluid led out of the heat exchanger, and is further configured to generate a sensed temperature value.
• the control unit is configured to communicate with the first pressure sensing unit and the temperature sensing unit to receive the sensed first pressure value and the sensed temperature value.
• the control unit is configured to process the received values based on a set of prestored set of rules to compute percentage opening of the control valve.
• the control unit is further configured to generate an actuating signal based on the computed percentage opening.
• the actuator is configured to communicate with the control unit to receive the actuating signal.
• the actuator is further configured to control the actuation of the control valve based on the actuating signal to allow flow of steam from the control valve at a controlled flow rate into the heat exchanger.
• control unit includes a repository, a computing unit and a comparator.
• the repository is configured to store the prestored set of rules, a predetermined value of pressure and a predetermined value of temperature therein.
• the computing unit is configured to compute steam flow parameters based on the set of rules and the predetermined value of temperature.
• the comparator is configured to receive the predetermined values, the sensed values, and the computed values.
• the comparator is configured to compare the sensed values with the computed values and predetermined values to generate a compared signal.
• the computing unit is configured to receive the compared signal to compute the percentage opening of the control valve and generate the actuating signal.
• the device includes at least one second pressure sensing unit positioned downstream of the control valve.
• the second pressure sensing unit is configured to sense the pressure of steam at an outlet of the control valve, and is further configured to generate a second sensed pressure value.
• the comparator is configured to receive the second sensed pressure value.
• the comparator is further configured to compare the second sensed pressure value with said computed pressure value to run the device at optimum pressure.
• Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
• the pressure sensing unit is positioned upstream of the control valve (105).
• the first pressure sensing unit (110) is configured to sense the pressure of steam at an inlet of the control valve (105), and is further configured to generate a first sensed pressure signal.
• the temperature sensing unit (130) is provided downstream of the heat exchanger (150). The temperature sensing unit (130) is configured to sense the temperature of fluid led out of the heat exchanger (150), and is further configured to generate a sensed temperature value.
• the control unit is configured to communicate with the first pressure sensing unit and the temperature sensing unit (130) to receive the sensed first pressure value and the sensed temperature value.
• the control unit is configured to process the received signals based on a set of prestored set of rules to compute percentage opening of the control valve (105).
• the actuator (125) is configured to communicate with the control unit to receive the actuating signal.
• the actuator is further configured to control the actuation of the control valve (105) based on the actuating signal to allow flow of steam from the control valve (105) at a controlled flow rate into the heat exchanger (150).
• control unit includes a repository, a computing unit (120) and a comparator (135).
• the repository is configured to store the prestored set of rules, a predetermined value of pressure and a predetermined value of temperature therein.
• the computing unit (120) is configured to compute steam flow parameters based on the set of rules and the predetermined value of temperature.
• the comparator (135) is configured to receive the predetermined values, the sensed values, and the computed values to generate a compared signal.
• the computing unit (120) is configured to receive the compared signal to compute the percentage opening of the control valve (105) and generate the actuating signal.
• the computation is based on the following logic implemented using the set of rules:
• the fluid at temperature Tfl is heated to temperature Tf2 using saturated steam as heating medium.
• the temperature Tf2 is to be maintained at pre-determined value.
• the temperature Tf2 will get changed if there is change in either fluid temperature Tfl or fluid flow m2.
• the steam flow rate ml is a function of pressure Pl, pressure P2 and valve opening.
• m 1 Mass flow rate of steam
• m2 Mass flow rate of fluid
• h2 is taken as enthalpy of condensate at saturation pressure P for practical purpose.
• the denominator value (hl - h2) also called latent heat of steam is inversely proportional to pressure P.
• the value of (hl-h2) increases if the pressure P is reduced.
• Saturated steam at typically 4 bar gauge is available in the distribution header. The invention reduces the pressure further in order to achieve steam saving.
• the below table illustrates the values of latent heat values of steam at different pressure condition.
• the device (100) includes at least one second pressure sensing unit (115) positioned downstream of the control valve (105).
• the second pressure sensing unit (115) is configured to sense the pressure of steam at an outlet of the control valve (105), and is further configured to generate a second sensed pressure value.
• a predetermined temperature value and a predetermined pressure value are fed to the repository. Based on the pre-determined temperature value and a predetermined pressure value, the computing unit computes the maximum temperature of steam to be supplied. The saturation pressure of the maximum steam temperature is computed and set as the maximum limit of steam pressure.
• control unit is configured to run multiple control loops with parameters of sensed temperature value, predetermined temperature value, and second sensed pressure value, to analyse the effect of incremental change in opening and closing of the control valve (105) based on the change in predetermined temperature value and second sensed pressure value.
• control unit iteratively computes a pressure value between an initially predetermined pressure value and the computed pressure value, and assigns it as a next pressure setpoint and changes it dynamically so that the sensed temperature value matches the predetermined temperature value.
• the device (100) acts as a combination of a pressure reducing valve and a temperature control valve which is an improvement over the conventional devices where at least two different valves were required for achieving the same results.
• control unit can be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and/or any devices that manipulate signals based on operational instructions.
• the actuator (125) is a control valve (105).
• a display unit (140) is communicatively coupled to the computation unit.
• the display unit (140) is configured to display from a group of data including the sensed pressure and temperature values.
• a data transmission unit (145) is coupled to the computation unit.
• the data transmission unit (145) is configured to transmit the calculated data by computation unit to other remote devices via a network.
• the data transmission unit (145) transmits the calculated data by selecting one of the wireless networks such as the Internet, one or more telecommunications networks as a wireless network, a wireless area network, a Wireless Video Are Network (WVAN), a Local Area Network (LAN), a WLAN, a PAN, a WPAN, WANs, metropolitan area networks (MANs), 4G/5G Hotspot, a WI-FI connection or an intranet.
• WVAN Wireless Video Are Network
• LAN Local Area Network
• WLAN Wireless Local Area Network
• PAN personal area network
• WPAN Wireless Personal Area Network
• WANs metropolitan area networks
• 4G/5G Hotspot a WI-FI connection or an intranet.
• the effect of the device (100) is such that if the steam temperature in the heat exchanger (150) is reduced, it is possible to have faster valve response to fluctuation in load. Since steam temperature is directly proportional to steam pressure, lowering the steam pressure at the inlet of heat exchanger (150) will result in lower steam temperature and improved accuracy of process fluid temperature control due to faster valve response.
• steam flow rate depends on both upstream and downstream pressure and also valve opening. Any fluctuation in downstream pressure can change the steam flow rate deviating from value required to achieve temperature of process fluid.
• the device (100) indicates the flow rate of steam passing through it.
• the device (100) is configured to employed in shell & tube heat exchangers, plate heat exchangers, spiral heat exchangers, straight tube heat exchangers, U - tube heat exchangers, and cross flow heat exchanger.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Control Of Turbines (AREA)
• Flow Control (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

Family Cites Families (1)

• 2023
  • 2023-09-12 WO PCT/IB2023/059024 patent/WO2024057198A1/en not_active Ceased
  • 2023-09-12 EP EP23864881.0A patent/EP4587774A1/de active Pending
• 2025
  • 2025-03-11 MX MX2025002904A patent/MX2025002904A/es unknown

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