Elimination of bleed in flow control devices

Abstract

Amplifiers are configured for use on the control valve. These configurations provide a pneumatic signal to an actuator that regulates flow through the device. The amplifiers may include a variable orifice or bleed valve that moves in response to changes in the working medium near a steady state. The bleed valve prevents bleeding of the working medium at steady state. This feature reduces energy consumption or emissions from the control valve.

Description

Summary of the Invention

Problems to be Solved by the Invention

[0001] Flow control devices play a major role in many industrial facilities. For example, power plants and industrial processing facilities use different types of flow control devices to manage the flow of materials, typically fluids, throughout an extensive network of pipes, tanks, generators, and other equipment. Control valves are useful for accurately adjusting the flow rate to meet process parameters. These valves often use pneumatic actuators to maintain the position of the closing member relative to the seat. An amplifier may be connected to the pneumatic actuator. This amplifier can regulate the flow of an operating medium, such as pressurized air (or "instrument air") or pressurized natural gas, to the pneumatic actuator. It is not uncommon for the amplifier to essentially bleed the operating medium, especially when the valve is in a steady state.

[0002] The subject matter of the present disclosure relates to improvements that can reduce or eliminate bleeding in the amplifier in a steady state. Particularly interesting here are embodiments that incorporate a variable orifice or "bleed" valve into the vent / supply valve structure. This bleed valve eliminates the need for the vent valve to remain open in a steady state and ensures that the amplifier does not continuously discharge the operating medium to the atmosphere. This feature can result in a potential reduction in carbon dioxide (CO2) emissions by reducing the energy consumption required to operate compressors or pumps for the provision of instrument air, or in the case of natural gas supply devices, the proposed design reduces methane emissions into the air.

Brief Description of the Drawings

[0003] Here, briefly refer to the accompanying drawings. [Figure 1] FIG. 1 shows a schematic diagram of an exemplary embodiment of a pneumatic relay. [Figure 2] FIG. 2 shows a schematic diagram of an example of the pneumatic relay of FIG. 1. [Figure 3] Figure 3 shows a plot of the performance curve of the pneumatic relay shown in Figure 2. [Figure 4] Figure 4 shows a cross-sectional elevation view of the exemplary structure of the pneumatic relay shown in Figure 2. [Figure 5] Figure 5 shows a cross-section of Figure 5 with an additional exemplary structure of the pneumatic relay. [Figure 6] Figure 6 shows a cross-section of Figure 5 with an additional exemplary structure of the pneumatic relay. [Figure 7] Figure 7 shows an exploded perspective view of an exemplary controller structure with the relays shown in Figure 1. [Figure 8] Figure 8 shows a perspective view of an exemplary structure for a flow control device that can incorporate the controller shown in Figure 7.

[0004] Where applicable, similar reference letters designate identical or corresponding components and units throughout several figures, not necessarily to scale, unless otherwise indicated. Embodiments disclosed herein may include elements appearing in one or more of several figures, or in combinations of several figures. Furthermore, methods are merely illustrative and can be modified, for example, by rearranging, adding, removing, and / or changing individual steps.

[0005] The drawings and any descriptions herein use examples to disclose the present invention. These examples include the best mode and enable those skilled in the art to carry out the present invention, including fabricating and using any device or system and performing any incorporated method. Any element or function described in the singular and advanced by the words "a" or "an" should be understood not to exclude multiple such elements or functions unless such exclusion is expressly stated. References to "one embodiment" or "one embodiment" should not be construed as excluding the existence of additional embodiments or embodiments that also incorporate the enumerated features. [Modes for carrying out the invention]

[0006] Next, the features of the embodiments shown in the drawings above will be described. Embodiments of this specification improve upon the design of conventional relays or "amplifiers" that use a fixed orifice to bleed the working medium in a steady state. The fixed orifice addresses control problems arising from the nonlinearity of the performance of certain valves found in these amplifiers. This nonlinearity or "dead zone" can delay the amplifier's response to an increase in the supply signal from a steady state. By maintaining a steady bleed through the fixed orifice, the amplifier is equipped to provide accurate and stable control of any corresponding flow control device. The proposed design not only maintains this level of control but also eliminates the bleeding of the working medium from the amplifier to the atmosphere in a steady state (or when there is no valve movement). Other embodiments are within the scope of this disclosure.

[0007] Figure 1 shows an example of a pneumatic relay 100. This embodiment is typically found in a distribution network 102 designed to transport material 104 throughout a network of conduits 106. The relay 100 may be part of a flow control device 108 having a valve body 110 connected in series with the conduits 106. The valve body 110 may house a seat 112 and a closing member 114 that can move relative to the seat 112 to regulate the flow of material 104. The flow control device 108 can control the position of the closing member 114 using an actuator 116. A controller 118 connects to the actuator 116. The controller 118 may have operating hardware 120 connected to the relay 100. The operating hardware 120 can convert an input pneumatic supply signal S1 into an amplifier input signal S2 that operates a variable orifice 122 in the relay 100 and regulate the flow of actuator control signals S3.

[0008] In general, the pneumatic relay 100 can be configured to avoid bleeding into the atmosphere. These configurations can preferably embody a device that increases the pressure or volumetric flow rate of an input signal by a linearly proportional amount. The device comprises a relay, as well as an "amplifier" or "booster". These devices are used in flow control systems located in or near a pneumatically operated valve.

[0009] The distribution system 102 may be configured to deliver or move resources. These configurations can embody extensive infrastructure. The materials 104 may also include gases, liquids, solids, or mixtures. The conduits 106 may often include pipes or pipelines connected to pumps, boilers, etc. The pipes may also be connected to tanks or reservoirs. In many facilities, this system forms a complex network.

[0010] The flow control device 108 may be configured to regulate the flow of material 104 through the conduit 106 in this complex network. These configurations may include control valves and similar devices. The valve body 110 in such a device is often made of cast or machined metal. This structure may have flanges formed over openings I, O. Adjacent pipes 106 can be connected to these flanges to allow material 104 to flow through the device, for example, through the opening of the seat 112. The closing member 114 may embody a metal disc or a metal "plug". The actuator 116 may use pneumatic or hydraulic pressure to adjust the position of the plug 114, thereby controlling the flow of material 104 through the seat 112 into the pipe 106 downstream of the device.

[0011] The controller 118 may be configured to process and generate signals. These configurations can be connected to a control network (or “distributed control system” or “DCS”), which maintains the operation of all devices on the process line to ensure that material flows according to the process. The DCS can generate control signals having operating parameters that describe or define the operation of the control valve 108 for this purpose. The operating hardware 120 may use electrical and computing components (e.g., processor, memory, executable instructions, etc.). These components may also include electro-pneumatic devices that operate on the input pneumatic supply signal S1. These components ensure that the output actuator control signal S3 to the actuator 116 is appropriate for the control valve 108 to supply material 104 downstream according to the process parameters.

[0012] The variable orifice 122 may be configured to precisely control the actuator control signal S3. These configurations may include a device that incorporates a valve that operates in response to changes in the flow of the working medium, including an amplifier input signal S2. In steady state, these valves can prevent the flow or "bleed" of the working medium, thus eliminating a waste source in terms of both the cost of operating a pump or compressor in the equipment pressurizing the input pneumatic supply signal S1, or the release of potential greenhouse gases into the atmosphere.

[0013] Figure 2 shows an example of the pneumatic relay 100 of Figure 1. The variable orifice 122 may include a main flow control device 124 that controls the flow from the relay 100 to the actuator 116 (as an actuator control signal S3). The main flow control device 124 may include a pair of "main" valves that act as a supply valve V1 and a vent valve V2. The device may also include a "bleed" valve V3. In one embodiment, valves V1, V2, and V3 are closed in a steady state to prevent a change in the actuator control signal S3 to the actuator 116, for example, in response to the movement or progression of the flow control device 108. The vent valve V1 opens in response to a decrease in the amplifier input signal S2. This response causes material to be discharged from the actuator 116 via the relay 100. The bleed valve V3, on the other hand, first opens in response to an increase in the amplifier input signal S2. This response may cause a (slight) increase in the actuator control signal S3 to the actuator 116. As the amplifier input signal S2 increases, the bleed valve V3 remains open until it reaches a fully open state. Then, in response to a further increase in the amplifier input signal S2, the supply valve V1 opens.

[0014] Figure 3 shows a plot of exemplary performance for the exemplary relay 100 of Figure 2. The plots include performance curves (P1, P2) that describe exemplary operation for both the proposed design of relay 100 (no working medium bleeding in steady state SS) and the conventional design (working medium bleeding through a fixed orifice in steady state SS), respectively. Both designs exhibit a “main” dead zone D1 in which an increase in the amplifier input signal S2 does not result in any change in the actuator control signal S3. The dead zone D1 corresponds to the response of the main valve found in the proposed design (e.g., a supply valve V2) and the conventional design with a fixed orifice. The use of a bleed valve V3 also introduces a small dead zone D2 into the performance curve P1. However, the trade-off for this almost negligible change in performance (at the dead zone D2) is well outweighed by the benefit of relay 100 effectively not bleeding any amplifier input signal S2 in steady state SS. Relay 100 is relatively more energy-efficient, environmentally friendly, and functions similarly to the control of actuator 116 near the steady state SS.

[0015] Figure 4 shows a cross-sectional elevation view of an exemplary structure for use in the relay 100 of Figure 2. The main flow control device 124 may include a vent plug 126 having an elongated body 128 whose diameter changes along its length. These changes may form shoulders 130. The elongated body 128 may have a seating contact surface 132 at one end. The other end of the elongated body 128 may have a threaded end 134. The supply plug 136 may include a central bore 138 that receives the elongated body 128. The change in diameter of the central bore 138 may form several shoulders 140. At one end, the supply plug 136 may have a seating contact surface 142. The other end may have a recess 144. In one embodiment, the bleed plug 146 may be located within the recess 144. The bleed plug 146 may have a central bore 148 with threads T that allow it to be screwed into, for example, the exposed portion of the threaded end 134 of the vent plug 126. The bleed plug 146 may have a seating contact surface 150. A nut 152 or similar threaded fixture can preferably lock the bleed plug 144 onto the elongated body 128 to prevent the bleed plug from retracting from the threaded end 134. The device may also include a first spring 154 interposed between the vent plug 126 and the supply plug 136.

[0016] Figure 5 shows a cross-sectional elevation view of the relay 100 of Figure 4, along with additional details for device implementation. This example includes a vent seat 156 with an aperture 158. The device may also include a supply seat 160. This component may have a central aperture 162 and a supply aperture 164, often arranged around or circumferentially around the supply seat 160. This design may also require a second spring 166 interposed between the surface of the supply plug 136 and the end cap 168. This configuration prevents bleeding of the input pneumatic supply signal S1 in a steady state because the seat contact surface 150 of the bleed plug 146 remains in contact with the surface of the recess 144, the seat contact surface 142 of the supply plug 136 remains in contact with the surface of the supply seat 158, and the seat contact surface 132 of the vent plug 126 remains in contact with the surface of the vent seat 156. As a result, this configuration maintains the parameters of the actuator control signal S3 to the actuator 116 in a steady state.

[0017] Figure 6 also shows a cross-section of Figure 5. Relay 100 may comprise a housing schematically shown as 172. An opening 174 within the housing 172 may allow the amplifier input signal S2 to strike the diaphragm assembly 176. A spring 178 may be interposed between the vent seat 156 and the supply seat 160. In this example, as the amplifier input signal S2 increases, the bleed plug 146 first opens (relative to its contact position in the recess 144) overcoming the spring force of the first spring 154. This feature increases the actuator control signal S3 present in relay 100. Any further increase in the amplifier input signal S2 opens the supply plug 136 (relative to its contact position in the supply seat 160), further increasing the actuator control signal S3.

[0018] Figure 7 shows a perspective view of an example of a controller 118 in disassembled form. This structure may comprise a manifold having a manifold body 180, which is typically machined or molded metal, plastic, or composite material. The device may comprise one or more boards 182 on which processing hardware is located on top. Other hardware may include a current-pressure transducer 184 that, together with a relay 100, can generate actuator control signals S3 (e.g., instrument air) to the actuator 116. Also shown, the controller 100 may have hardware to protect the control components. This hardware may include enclosures shown in this example as covers C1, C2. Covers C1, C2 are fixed to the manifold body 182 and can protect the control components from conditions prevalent in the environment surrounding the flow control device 108. One of the covers, C2, may incorporate a display 186 and a push-button input device 188, which may act as a primary local user interface to allow an end user (e.g., a technician) to interact with the controller 100. This feature may be important for periodic maintenance, configuration, and setup, for example, to allow end users to exit valve operating mode and access a menu structure to manually perform functions such as calibration, setting, and monitoring. In one embodiment, the controller 118 may further include one or more gauges G1, G2 that can provide indications of fluid flow conditions (e.g., pressure, flow rate, etc.) that the controller 100 uses to operate the flow control device 108.

[0019] Figure 8 shows a perspective view of an exemplary structure of a flow control device 108. The valve body 110 may form a flow path 190 having a flanged open end 192. The controller 118 may be fixed to a bracket 194 which is part of the flow control device 108. Fasteners such as bolts are useful for this purpose. Valve components such as the seat and the closing member may be located inside the body 110 (and are therefore hidden in this figure). The device may include a valve stem 196 that connects the closing member to an actuator 116. In one embodiment, the actuator 116 may include a bulbous housing 198 with two parts that clamp around the edge to capture a diaphragm (not shown) around its periphery. As described herein, an actuator control signal S3 may pressurize the upper part of the housing 198 acting on one side of the diaphragm. An actuator spring located at the bottom of the housing 198 acts on the opposite side of the diaphragm. This configuration affects the position of the closing member and regulates the flow through the valve body 110.

[0020] In view of the above, the improvements described herein effectively eliminate working fluid bleeding from the amplifier. Embodiments incorporate a variable orifice, described herein as a miniature bleed valve, but other device structures can achieve similar results. By using a variable orifice instead of a fixed orifice, the flow of working fluid in a steady state is prevented. This feature saves energy and avoids unnecessary discharge. However, without sacrificing any control over the corresponding actuator, and therefore, a flow control device adapted to the amplifier of the proposed design can still maintain precise control over the flow to the process line.

[0021] Examples comprising specific elements or items (one or more of which may be combined with other elements and items) appear below to illustrate embodiments conceivable within the scope and spirit of this disclosure. This scope includes and may be conceivable of other embodiments conceived by those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that are not different from the literal wording of the claims, or equivalent structural elements that are substantially different from the literal wording of the claims.

Claims

1. A flow control device, Actuator and An amplifier coupled to the actuator to provide an actuator control signal, the amplifier having a variable orifice that changes position in response to changes in the amplifier input signal that is close to a steady state, and the amplifier comprises: The variable orifice controls the working medium including the amplifier input signal. The variable orifice includes a supply valve, a ventilation valve, and a bleed valve. The supply valve, the vent valve, and the bleed valve are connected to each other. The ventilation valve opens in response to a decrease in the amplifier input signal. The bleed valve opens in response to an increase in the amplifier input signal, and the increase in the amplifier input signal increases the actuator control signal to the actuator. As the amplifier input signal increases, the bleed valve remains open until it reaches a fully open state. In response to a further increase in the amplifier input signal, the supply valve opens. Flow control device.

2. The flow control device according to claim 1, wherein the variable orifice has a position that prevents flow in a steady state.

3. The flow rate control device according to claim 1, wherein the variable orifice has a position that allows flow in response to an increase in the amplifier input signal from a steady state.

4. A current-pressure converter coupled to the actuator and providing the amplifier input signal, The flow rate control device according to claim 1, further comprising the following:

5. A controller having an enclosure containing the aforementioned amplifier and a current-to-pressure converter that provides the amplifier input signal, The flow rate control device according to claim 1, further comprising the following:

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