HK1230692B - Passive explosion isolation valve with pulse jet cleaning - Google Patents

Description

Passive explosion isolation valve with pulse jet cleaning

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/946,319, filed February 28, 2014, which is incorporated herein by reference in its entirety.

Background of the Invention

Technical Field

The present invention generally relates to a passive explosion isolation valve having a self-cleaning feature configured to prevent the accumulation of debris that could adversely affect the closure of the valve in the event of an energy event.

Background Art

Dust collection systems are used in various industrial plants to remove fine particulate matter from material handling equipment to prevent it from being released into the environment. These systems typically include baghouses or similar dust collection devices, where particulate matter is collected before the airstream is vented to the atmosphere. The collected particulate matter can be highly flammable or explosive. Isolation valves are often used to protect upstream equipment from the catastrophic consequences of an explosion within the dust collection equipment.

Isolation valves can be of active or passive type. Active isolation valves generally require some kind of mechanical actuation in response to a detected hazardous condition, such as a deflagration wave or flame front. Active isolation valves can be of the gate valve type, such as described in U.S. Patent No. 6,131,594, in which the switching of the gate member is affected by an actuator device. Another type of active isolation valve is a pinch valve, such as disclosed in U.S. Application Publication No. 2013/0234054, in which an inner sleeve is compressed. With respect to gate type isolation valves, the closing of the pinch valve sleeve is affected by an actuator device. While effective, active isolation valves are generally more complex and require the installation of detection equipment that can identify the onset of a hazardous energy event and trigger the valve closing actuator, thereby resulting in increased capital cost.

Passive isolation valves, such as check valves, are generally less complex and do not rely on detection devices for their actuation. Specifically, passive isolation valves typically respond to environmental changes, such as the energy event itself or changes in the pressure or direction of the fluid flow. As such, passive isolation valves are generally not actively monitored to ensure their operational integrity, except for routine inspections and maintenance. In dust collection systems, the accumulation of particulate matter near the valve has been found to adversely affect the valve's effectiveness in preventing the propagation of an energy event. Specifically, the accumulation of dust or other matter can interfere with the complete closure of the valve's gate member.

The present invention seeks to overcome these problems by providing a passive isolation valve configured to prevent the accumulation of particulate matter near the valve closure member that could adversely affect the performance of the valve in response to an energy event.

Summary of the Invention

According to one embodiment of the present invention, a passive isolation valve is provided. The valve includes a valve body including a valve inlet, a valve outlet, and a passage through the valve body that interconnects the valve inlet and the valve outlet. A gate member is fixed to the valve body by a hinge that allows the gate member to switch between a valve open position and a valve closed position. In the valve open position, the valve inlet is connected to the valve outlet, and in the valve closed position, the gate member blocks the communication between the valve inlet and the valve outlet. The valve body further includes a valve seat, and the gate member contacts the valve seat in response to an energy event downstream of the valve during switching from the open position to the closed position. The valve further includes one or more nozzles mounted in the valve body and configured to direct airflow into the passage near the valve seat and remove accumulated particulate matter from the vicinity of the valve seat, which would interfere with contact between the gate member and the valve seat during switching from the open position to the closed position.

According to another embodiment of the present invention, a passive isolation valve is provided. The valve includes a valve body including a valve inlet, a valve outlet, and a passageway through the valve body that interconnects the valve inlet and the valve outlet. The valve further includes a hinge that allows a gate member to be switched between a valve open position and a valve closed position, wherein in the valve open position, the valve inlet is in communication with the valve outlet, and in the valve closed position, the gate member blocks communication between the valve inlet and the valve outlet. The valve body further includes a valve seat, the gate member contacting the valve seat in response to an energy event downstream of the valve during switching from the open position to the closed position. The gate member includes a raised central section and surrounding sidewalls and a surrounding rim, wherein the central section has convex and concave surfaces, the sidewalls extending laterally from the concave surface, and the rim extending laterally from the sidewalls and outside of the central section. When the gate member is in the valve closed position, the sidewalls and the rim cooperate with the valve seat to block communication between the valve inlet and the valve outlet.

In another embodiment of the present invention, a method for cleaning a passive isolation valve installed in a pneumatic material handling system is provided. The method includes providing a passive isolation valve according to any embodiment of the present invention. One or more nozzles of the valve are connected to a pressurized gas source. An airflow including suspended particulate matter is directed through a valve passageway and around a gate member. The pressurized airflow is supplied to the one or more nozzles so as to cause the pressurized gas to be discharged from the one or more nozzles and enter the valve passageway near the valve seat. The pressurized airflow causes particulate matter that has settled from the airflow in the area near the valve seat to be resuspended in the airflow and removed from the area near the valve seat.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic diagram of a passive isolation valve and a baghouse as part of a dust collection system according to one embodiment of the present invention;

FIG2 is a perspective view of an embodiment of a passive isolation valve according to the present invention;

FIG3 is another perspective view of the embodiment of FIG2 ;

4 is a cross-sectional view of the embodiment of FIG. 2 , depicting particulate matter flowing through the passive isolation valve in its valve-open configuration;

5 is a cross-sectional view of a passive isolation valve effecting closure of the valve during an energy event;

6 is a partially cutaway view of a passive isolation valve according to one embodiment of the present invention illustrating the operation of a nozzle to remove accumulated material from the valve; and

7 is a cross-sectional view of the valve taken along line 7 - 7 of FIG. 5 .

DETAILED DESCRIPTION

The present invention generally relates to passive isolation valves for pneumatic material handling systems, and specifically to dust collection systems. FIG1 shows a dust collection system 10 comprising a dust collection device 12. Under normal operating conditions, excess dust or particulate matter suspended in an airflow (e.g., air stream) transported from an industrial plant or process (not shown) is directed to the collection system 10. The collection device 12 is configured to remove at least a portion of the suspended matter and preferably remove most of it to prevent the particulate matter from being discharged into the atmosphere. As depicted in FIG1 , the dust collection device 12 is a bag filter 14 comprising a plurality of bag filters 16 suspended therein. However, it should be noted that the collection device 12 may include other devices commonly used in dust collection or dry material handling systems, such as cyclone separators, wherein the dust collection or dry material handling system comprises an impeller or fan operable to supply a motive force for guiding the airflow through the collection system. The collection device 12 comprises an inlet 18, in which an airflow comprising suspended particulate matter enters the device 12. The air flow passes through a plurality of bag filters 16, which separate the suspended particulate matter, which remains within an interior chamber 20 where it collects until removed via a particle outlet 22. The air that has passed through the bag filters 16 and from which a substantial portion of the suspended solid particulate matter has been removed is then removed from the baghouse 14 via a clean air outlet 24. In certain embodiments, the collection apparatus 12 is equipped with a bag cleaning system 26 including a pressurized gas delivery system 28 capable of delivering a high-pressure air flow through the delivery system to the bag filters 16, which "shakes" the filters so as to dislodge accumulated particulate matter therefrom and cause such particulate matter to collect within the interior chamber 20.

The dust collection system 10 also includes or is operably connected to a passive isolation valve 30, which is in fluid communication with the dust collection device 12. The valve 30 includes a valve body 32 disposed between a valve inlet section 34 and a valve outlet section 36. The valve body 32 at least partially defines a valve internal chamber 38, within which a hinged gate member 40 is located. In certain embodiments, the valve inlet section 34 and the valve outlet section 36 include respective flanges 42, 44 that allow the valve 30 to be secured to process pipes or ductwork sections 46, 48 (e.g., see FIG. 2 ). In certain embodiments, the valve 30 may also include a removable panel 50 that allows access to the valve internal chamber 38. In addition, the panel 50 may be equipped with a connective structure 52, such as an eye hook, to facilitate transport and installation of the valve 30 between the ductwork sections 46, 48, and a handle 53 that allows the panel 50 to be lifted from the valve body 32.

Turning now to Figures 4-6, a gate member 40 is shown fixed to a rotatable rod 54 that acts as a hinge for the member 40, the rotatable rod 54 being fixed to a mechanism 56 that is operable to prevent the gate member from opening once it is closed due to a downstream energy event. In some embodiments, the mechanism 56 includes a damping member that is operable to dampen the rotation of the rod 54 and, accordingly, dampen the displacement of the gate member 40, as described below. In some embodiments, the damping mechanism 56 includes damping members 58, 60 that include biasing devices (not shown), such as hydraulic elements, that inhibit, but do not necessarily prevent, rotation of the rod 54. In other embodiments, the mechanism 56 may include a locking mechanism that physically locks or limits further movement of the gate member 40 after a downstream energy event.

In certain embodiments, the gate member 40 includes a concave plate having a central section 62 that protrudes from a generally flat, surrounding flange region or rim 64. In a particular embodiment, the central section 62 is a raised, concave-convex configuration having opposing convex and concave surfaces. In certain embodiments, the surface of the central section 62 facing the valve inlet section 34 can be convex, while the surface of the central section 62 facing the valve outlet section 36 can be concave. Extending laterally from the central section 62 and interconnected with the flange region 64 is a surrounding sidewall or transition region 66.

The valve inlet section 34 includes an end section 68 that extends through an angled wall section 70 of the valve body 32 (relative to the longitudinal axis of the valve 30, which is also generally parallel to the direction of gas flow through the valve) and into the interior chamber 38. The end section 68 includes an angled end edge 72 that, in some embodiments, lies in a plane parallel to the wall section 70. As further explained below, the end edge 72 and/or the end section 68 form a receptacle for the gate member 40 during switching of the gate member 40 between the valve open and valve closed positions in response to an energy event. The valve outlet section 36 is fixed to a valve body side wall section 74 that is disposed opposite the angled wall section 70. In some embodiments, the outlet section 36 is frustoconical in shape, having a larger diameter at its intersection 76 with the side wall section 74 than at its distal end 78. This is in contrast to the valve inlet section 34, which is cylindrical and has a relatively constant diameter from one end to the other.

Isolation valve 30 further includes one or more nozzles 80, 82 extending through valve body 32 and communicating with internal chamber 38. In certain embodiments, the nozzles are oriented obliquely relative to the respective valve body sidewalls 84, 86 through which they extend. In a specific embodiment, nozzles 80, 82 are positioned at an approximately 45-degree angle relative to the respective sidewalls 84, 86. In certain embodiments, nozzles 80, 82 communicate with internal chamber 38 via ports in sidewalls 84, 86, positioned below the longitudinal axis of valve 30 and between angled wall section 70 and end edge 72. Each nozzle 80, 82 is operably connected to a pressurized gas source via gas lines 88, 90, respectively, and is configured to introduce a pressurized gas flow into internal chamber 38, as discussed below. Specifically, nozzles 80, 82 are positioned to deliver the pressurized gas flow into a "dead space" 92 within internal chamber 38. Dead space 92 is characterized as a region within internal chamber 38 that exhibits a reduced velocity of the gas flowing through valve 30, such that particulate matter being carried by the valve throughput is no longer able to remain in suspension. Consequently, particulate matter entering dead space 92 is at risk of falling out of suspension within the gas passing through valve 30 and accumulating in dead space 92 near inlet end section 68 and end edge 72, as illustrated in FIG4 . Generally speaking, dead space 92 is defined as the annular passage of internal chamber 38 between angled wall section 70 and end edge 72 and below the longitudinal axis of valve 30. Specifically, dead space 92 can be further defined as the region below the ports in sidewalls 84, 86 through which nozzles 80, 82 communicate with internal chamber 38.

In certain embodiments, the valve 30 can be equipped with one or more sensors (not shown), such as optical sensors, attached via sensor ports 94, 96 formed in the valve body 32. The ports 94, 96 are positioned so as to be able to detect the accumulation of particulate matter within the dead space 92. In particular embodiments, the ports 94, 96 are disposed below the ports in the sidewalls 84, 86 through which the nozzles 80, 82 communicate with the internal chamber 38.

As illustrated in FIG4 , in certain embodiments, when the valve 30 is connected to the particle collection system 10, particulate matter 98 suspended in an airflow (illustrated by arrows) comprising, for example, air, enters the isolation valve 30 via the valve inlet section 34 and flows through the valve body 32, past the gate member 40, and exits via the valve outlet section 36. Upon exiting the outlet section 36, the airflow comprising particulate matter 98 can then be directed to the collection device 12. The gate member 40, in its valve-open configuration illustrated in FIG4 , disposed at an angle of approximately 70 degrees relative to a line perpendicular to the longitudinal axis of the valve, partially obstructs passage between the valve inlet section 34 and the valve outlet section 36, thereby causing the airflow to be deflected in a generally downward manner. Due to this deflection, a portion of the airflow is directed toward the dead space 92, thereby causing a portion of the suspended particulate matter 98 to fall and deposit within or immediately adjacent to the dead space 92. As explained below, the accumulation of particulate matter 98 can become sufficient to interfere with the closure of the gate member 40 in response to an energy event downstream of the isolation valve 30.

As illustrated in FIG5 , during an energy event occurring downstream of the valve 30, such as an explosion in the dust collection system 10, rapidly expanding gas begins to flow upstream through the ductwork 38, as illustrated by the arrows. This upstream flow of gas exerts a force on the gate member 40, thereby causing the gate member to switch to a valve-closed configuration in which the gate member 40 seats on the inlet end section 68 to cover the outlet 100 of the inlet section 34. Thus, propagation of the energy event upstream of the valve 30 is arrested.

In certain embodiments of the present invention, in the valve closed configuration, the gate member 40 is arranged at an angle of approximately 30 degrees relative to a line perpendicular to the longitudinal axis of the valve. Therefore, during the closing of the valve, the gate member 40 travels through a path of approximately 40 degrees. In the valve closed configuration, the gate center section 62 is located inside the inlet end section 68 and upstream of the end edge 72, and at least a portion of the transition region 66 can contact the inner surface 102 of the end section 68. In addition, at least a portion of the flange 64 can contact the end edge 72. The placement (seating) of the gate member 40 in this manner effectively blocks the communication between the inner chamber 38 and the valve inlet section 34, thereby preventing the upstream propagation of the energy event. Once seated, the damping mechanism 56 prevents further movement of the gate member 40, especially the movement of the gate member toward the valve open configuration. Therefore, the damping mechanism 56 prevents the gate member 40 from reopening prematurely after the energy event.

During the closing of the valve 30, the lower portion 104 of the gate member 40 swings through a path of travel and through which the path may approach or enter the dead space 92. Particulate matter 98 (as shown in FIG4 ) that has accumulated in the dead space 92 may contact the lower portion 104 and may become lodged between the transition region 66 and the inner surface 102 and/or the flange 64 and the end edge 72, thereby preventing the gate member 40 from being properly seated and effectively preventing communication between the inner chamber 38 and the valve inlet section 34, and preventing the propagation of energy events upstream. The valve 30 is equipped with a device for removing such accumulated particulate matter 98 from the path of travel of the lower portion 104 of the gate member 40. Specifically, such a device includes one or more nozzles 80, 82 configured to deliver pressurized airflow into a portion of the annular passage between the inlet end section 68 and the valve body 32.

6 and 7 , nozzles 80, 82 are mounted in valve body 32 and are configured to introduce a flow of gas into the annular passage of interior chamber 38, and particularly into dead space 92, between angled wall section 70, end edge 72, and inlet end section 68, in order to resuspend accumulated particulate matter into the gas flow passing through valve 30. Introducing the gas flow from above and directing it downwardly onto the accumulated matter has been found to be particularly effective in resuspending particulate matter into the gas flow passing through valve 30. Accordingly, nozzles 80, 82 are angled downwardly toward the bottom of interior chamber 38 so that the gas flow introduced via nozzles 80, 82 can be directed into dead space 92. In certain embodiments, the gas flow from nozzles 80, 82 can be controlled by a controller assembly 106 (see FIG. 2 ), which is operably connected to a source of pressurized gas (not shown). The controller assembly 106 may include a manual shutoff valve 108 to which the supply line can be connected, one or more solenoid valves 110 for metering air flow to the nozzles 80, 82, and a gas purge device 112 for purging gas and condensate from the controller assembly. In an alternative embodiment, the nozzles 80, 82 and gas lines 88, 90 are operably connected to the bag cleaning system 26 and operate under the control of the system 26. In some embodiments, the air flow delivered from the nozzles 80, 82 is introduced as a constant flow. However, in other embodiments, the air flow delivered from the nozzles 80, 82 into the inner chamber 38 is delivered as pulses of compressed air. In such embodiments, the duration of each pulse or air flow is preferably between about 200 milliseconds and about 1.5 seconds, more preferably between about 500 milliseconds and about 1.3 seconds, and even more preferably between about 750 milliseconds and about 1.2 seconds, with the air flow being interrupted between successive pulses. The time between successive pulses may vary depending on the specific application of the valve 30.

In some embodiments, a pulse of gas is supplied simultaneously with the airflow supplied by the bag cleaning system 26 to expel particulate matter from the bag filter 16. In specific embodiments, the pulse is controlled by the bag filter controller and is supplied at regular, repeating intervals. In other embodiments, a pulse of gas from the nozzles 80, 82 is delivered only when an unacceptable accumulation of particulate matter 98 is detected within the interior of the inner chamber 38. As previously discussed, sensors can be mounted within the sensor ports 94, 96 to detect accumulation of particulate matter in the path of travel of the lower portion 104 of the gate member 40 or near the end edge 72. In one embodiment, the sensor (not shown) comprises an optical sensor. For example, a light sensor can be mounted within the port 94, the light sensor being operable to emit a light beam that is received by a receiving sensor mounted within the port 96. If the light beam is interrupted by sufficient accumulation of particulate matter within the dead space 92, the gas control assembly 106 may issue a command to deliver a pulse of gas or a constant airflow to the nozzles 80, 82.

When airflow begins, gas flows from nozzles 80, 82 and is directed in a generally downward direction into the annular passage between the sloping wall section 70, the end edge 72, and the inlet end section 68. Specifically, the airflow is then directed into the dead space 92, near any accumulated particulate matter 98. The airflow displaces at least a portion of any accumulated particulate matter present in the dead space 92 into the airflow flowing through the valve 30, thereby suspending the particulate matter within the airflow, which guides the particulate matter through the valve outlet section. It should be appreciated that other nozzle configurations are possible without departing from the spirit of the present invention. For example, the valve 30 may include a single nozzle 80, or two, three, or more nozzles spaced apart around the annular passage between the sloping wall section 70, the end edge 72, and the inlet end section 68. For example, the nozzle may be positioned at the bottom center dead zone of the dead space 92, indicated in the figure by port 114. However, in some embodiments, it is not desirable for the nozzle positioned at port 114 to be the only nozzle used. If no nozzle is installed in port 114, other sensing means for detecting the presence of accumulated particulate matter in dead space 92 may be disposed through the port, or the ports may simply be blocked.

It should be understood that the foregoing description of certain embodiments according to the present invention is intended to be illustrative, and should not be construed as limiting the scope of the invention in any way.

Claims (16)

1. A passive isolation valve, comprising: A valve body, comprising a valve inlet, a valve outlet, and a channel through the valve body connecting the valve inlet and the valve outlet; and A gate member, secured to the valve body by a hinge that allows the gate member to switch between a valve open position and a valve closed position, wherein in the valve open position the valve inlet communicates with the valve outlet, and in the valve closed position the gate member prevents communication between the valve inlet and the valve outlet. The valve body further includes a valve seat, the gate member contacting the valve seat during switching from the open position to the closed position in response to an energy event downstream of the valve, the gate member extending downstream away from the valve seat when in the open position, and the valve body also including an annular channel located upstream of the valve seat. The valve further includes one or more nozzles mounted within the valve body and oriented at an angle to the annular channel, configured to introduce downstream airflow into the annular channel and near the valve seat to remove accumulated particulate material from the vicinity of the valve seat. The accumulated particulate material will contact the gate member during the transition from the open position to the closed position and become interposed between the gate member and the valve seat, thus resuspending the particulate material within the airflow flowing between the valve inlet and the valve outlet. 2. The valve of claim 1, wherein the valve seat includes an edge of a tubular member extending into the channel, the edge existing in a plane inclined to the channel through the valve body. 3. The valve of claim 2, wherein one or more nozzles are mounted within the valve body upstream of the edge and operable to introduce airflow into the channel upstream of the edge. 4. The valve of claim 2, wherein the edge cooperates with the valve body to define the annular channel. 5. The valve of claim 1, wherein the one or more nozzles are operable to deliver pulsed airflow into the passage near the valve seat. 6. The valve of claim 5, wherein the duration of each of the pulses is between 200 milliseconds and 1.5 seconds. 7. The valve of claim 1, wherein the valve further comprises a mechanism fixed to the gate member, the mechanism being operable to restrict movement of the gate member from the closed position. 8. The valve of claim 1, wherein the gate member comprises a raised central section and surrounding sidewalls and surrounding flanges, the central section having opposing convex and concave surfaces, the sidewalls extending laterally from the concave surfaces, and the flanges extending laterally outside the central section and from the sidewalls, wherein when the gate member is in the valve closed position, the sidewalls and the flanges cooperate with the valve seat to prevent communication between the valve inlet and the valve outlet. 9. A method for cleaning a passive isolation valve installed in a pneumatic material handling system, comprising: Provide a valve according to any one of claims 1-8; Connect one or more nozzles to a pressurized gas source; Guides an airflow, including suspended particulate material, through the channel and around the gate component; and The pressurized gas flow is supplied to one or more nozzles to cause the pressurized gas to exit from the one or more nozzles and enter the channel near the valve seat. The pressurized gas flow causes particulate material that has settled from the gas flow into the area near the valve seat to become resuspended in the gas flow and removed from the area near the valve seat. 10. The method of claim 9, wherein the pneumatic material handling system comprises a bag filter located downstream of the valve, the bag filter comprising a plurality of bag filters suspended therein and a bag cleaning system comprising a pressurized gas delivery system and a controller, the pressurized gas delivery system being configured to deliver pulses of pressurized gas to the bag filters, the controller being operable to control the delivery of the pulses of pressurized gas to the bag filters. 11. The method of claim 10, wherein the flow of pressurized gas to the one or more nozzles is controlled by a controller of the bag filter. 12. The method of claim 10, wherein the pressurized gas source connected to the nozzle is also a pressurized gas source for delivering pulses of pressurized gas to the bag filter. 13. The method of claim 9, wherein the pressurized airflow to the one or more nozzles is provided as a pulsed pressurized airflow. 14. The method of claim 13, wherein the valve includes a controller for controlling the pressurized airflow of the pulse. 15. The method of claim 14, wherein the controller is programmed to deliver pulses of pressurized gas to the one or more nozzles at regularly repeating intervals. 16. The method of claim 14, wherein the valve further comprises one or more sensors operable to detect the accumulation of the particulate matter near the valve seat and to provide the controller with a signal that causes the controller to deliver pressurized gas to the one or more nozzles.