Patent Description:
A Shutdown Valve, SDV, also referred to as Process Shutdown Valve, PSDV or Emergency Shutdown Valve, ESDV or ESV, is an actuated valve designed to stop the flow of a hazardous fluid upon the detection of a dangerous event. Blow Down Valves (BDV's) are designed to depressurize a process system in case of a detected hazardous situation on the plant.

BDV's are shut in normal operations and must have high integrity for opening when a process blow-down is required. Both SDV's and BDV's provide protection against possible harm to people, environment and the investments. SDV's and BDV's form part of a Safety Instrumented System. The process of providing automated safety protection upon the detection of a hazardous event is called Functional Safety.

SDV's and BDV's are primarily associated with the oil and gas industry, although other industries may also require this type of protection system.

In a process plant in operation, both SDV's and BDV's are "static" valves, which stay in one position until a hazardous condition occurs, where an automated shut down is required and the SDV's all closes, and/or a process depressurisation is required and the BDV's all open.

SDV's and BDV's are typically high-recovery valves that lose little energy due to low flow turbulence. Flow paths are straight through. As SDV's and BDV's form part of an automated safety instrumented system it is necessary to operate the valve by means of an actuator. These actuators are normally fail-safe with either a pneumatic cylinder or a hydraulic cylinder.

In addition to the fluid type, actuators also vary in the way energy is stored to operate the valve on demand such as single-acting cylinder with spring return where the energy is stored by means of a compressed spring. Another type is double-acting cylinder, where the "fail safe" energy is stored using a volume of compressed fluid from external accumulators.

The type of actuation required depends upon the application (pressure and flow), site facilities and the physical space available, although the majority of actuators for smaller SDV's and BDV's are of the spring return type due to the failsafe nature of spring return systems, while larger valves may have hydraulic double-acting actuators with separate hydraulic accumulators for back-up power to make up the failsafe requirement.

SDV's and BOV's are used in a variety of industrial applications to safeguard process equipment for exposure of internal pressures exceeding the equipment design pressure. One industrial application where SDV's and BDV's are used is within the oil and gas industry. Consequences of a fault on any one shutdown valve ranges from hazardous explosions and fire to releases of hydrocarbon and other toxic gases to the atmosphere.

Maintenance of SDV's and BDV's are of major importance to the economy in the operation. In the maintenance context, it is distinguished between (REF. NORSOK Z008 and others): "corrective maintenance" where the equipment is run to failure, "preventive maintenance" where maintenance of the equipment is performed at pre-defined (planned) intervals and "condition-based maintenance" where maintenance is performed based on measurements of equipment condition and performance.

SDV's and BDV's are normally maintained on predefined intervals in the class of "preventive maintenance". Reducing maintenance time and costs associated with maintaining SDV's and BDV's can have a large impact on the plant maintenance cost.

For SDV's and BDV's used in safety instrumented systems it is essential to know that the valve can provide the required level of safety performance and that the valve will operate on demand. The required level of performance is dictated by the Safety Integrity Level (SIL). In order to adhere to this level of performance it is necessary to test the valve.

There are <NUM> types of testing methods available, namely:.

Partial stroke test is used to assist in determining that the safety function will operate on demand by moving the valve some degree from open or closed at specified time intervals. The idea is to test the valve without interrupting the process. However, the test measures actuator pressure and time and is therefore only an indirect measure of valve movement related to stiction of the shutdown valve.

Partial stroke testing introduces additional components directly connected to the hydraulic/pneumatic actuator system of the shutdown valve adding components and complexity, which may reduce the probability of failure on demand which is an essential measure for a safety system and not a replacement for the need to fully stroke valves, as proof testing is still a mandatory requirement.

Other systems for automated online monitoring of SDV's and BDV's include continuous online monitoring connected to the plant monitoring system, which create a huge amount of data to be analysed and evaluated, which has proven to create costly installations and require specialised personnel to maintain and extract the data for the PSV maintenance process.

One obvious opportunity for test of SDV's and BDV's integrity is unplanned plant shutdowns, caused by equipment, instrument or human failure or caused by a real hazardous situation such as a fire or gas leak on the plant.

However, due to the nature of the shutdown and the need to bring the plant back to normal production, testing SDV's and BDV's in this operational transient, unplanned situations are complicated tasks which need special equipment, which is not readily available on the market or far too expensive to install using existing instrument systems.

<CIT> discloses a prior art system for detecting abnormal operation conditions in a shutdown valve.

It is an object of the invention to provide a system and method to detect abnormal operating conditions which will influence functional safety of Shut Down Valves (SDV's) or Blow Down Valves (BOV's) by monitoring valve performance as part of the normal operation of the plant, which also include spurious process shutdowns.

It is further an object of the invention to provide a method and system in order to reduce maintenance work and operating cost for the SDV's. The invention is thus defined by a system for detecting abnormal operating conditions in a shutdown valve according to claim <NUM> and the corresponding method as defined in claim <NUM>.

It is further an object of the invention to provide a method and a system to measure stiction of the valve when it is activated by any spurious process shutdown where the valve control system moves the SDV from open to closed or from closed to open position.

It is further an object of the invention to provide a method and system to determine when the SDV deviates from the acceptable operating specification by leaking process medium and to quantify the leak rate per unit time when the SDV is closed.

A further object of the invention is to provide a method and system to determine when the SDV's deviate from the acceptable operating specification by valve leakage in closed position and to quantify the leak rate per unit time.

Yet a further object of the invention is to generate, and store defined abnormal condition messages in real time in the local predictor microcontroller and to transmit the messages wireless as required by external operational data systems.

These objects are achieved with the method and system of the disclosed invention as set forth in the appended claims.

The invention will now be described in more detail and with reference to the appended claims in which:.

At least one embodiment of the present invention is described below in reference to operation of a Shut Down Valve (SDV) within an oil and gas production plant. However, it should be apparent to those skilled in the art and guided by the teaching herein that the present invention is likewise applicable to any Emergency Shutdown Valve (ESDV) and any, Blow Down Valve (BDV) in any industrial facility that may employ SDV's, ESDV's or BDV's.

A non-exhaustive listing of possible industrial facilities that employ SDV'S, ESDV's or BDV's and that need to monitor such valves includes power generation plants, chemical facilities and electrical facilities. Those skilled in the art will further recognize that the teaching herein is suited to other applications in addition to industrial settings such as for example military, commercial and residential applications.

Referring to the drawings, <FIG> is a schematic illustration of a Shut Down Valve and a Blow Down Valve with monitoring system for abnormal situation detection depicting the communication as a generic symbol, achieved either over a Wi-Fi network, Bluetooth protocol, SMS protocol (a cloud, dedicated application or a handheld device), or any other applicable method according to one embodiment of the present invention. SDV's and/or BDV's with sensors and the Predictors are able to communicate with different recipients. Referring to the drawing <FIG>, shows the details of at least one SDV <NUM> with a first detector system comprising at least one first predictor <NUM> intended to record if the SDV's ,flow-controlling element <NUM> sticks in closed or open valve position, also including:.

The said predictor <NUM> is fixed on top of the stem <NUM> and when the actuator <NUM> is activated, the flow- controlling element <NUM> move between open and closed position.

A second detector system comprising at least one second predictor <NUM> configurated to record and estimate leakage of the SDV's flow-controlling element <NUM> in closed position, is fixed to at least one downstream inlet pipe <NUM> and a downstream outlet pipe <NUM> on the said SDV <NUM>, also including.

And where the second detector system also including at least one fastener <NUM> with at least one strain gauge sensor <NUM> is clamped to the downstream pipe <NUM> with the said fastener, where the pressure in the downstream pipe <NUM> expands the downstream pipe <NUM> and thereby increases the strain in the fastener <NUM> and the strain gauge sensor <NUM>, and the measured strain that is proportional to the pressure in the downstream pipe <NUM> and/or at least one pressure sensor <NUM> which may be of piezoceramic type is installed in the downstream pipe <NUM> which also measures the pressure in the said downstream piping.

Where the said sensors <NUM> and <NUM> are wired onto the external sensor interface <NUM> which is controlled by the microcontroller <NUM> and measured as pipe pressure strain gauge <NUM> and pipe pressure <NUM>, when the said microcontroller <NUM> wakes up from sleep mode as described in the flow chart <FIG>.

Referring to <FIG>, which illustrates the program steps for the said microcontroller <NUM>, where START <NUM> is the initial sleep mode state of the microcontroller <NUM>, and the at least one shock sensor <NUM> is installed in the Predictor <NUM> or at least one piezoelectric pressure sensor <NUM> is detecting sufficient ultrasonic vibrations energy transmitted from the downstream pipe <NUM> to generate an activation signal <NUM>.

Where the microcontroller <NUM> wake-up <NUM>, and communicate through the wireless interface <NUM> with the predictor <NUM> and receives the valve position data <NUM> for SDV <NUM>, and if the flow-controlling element <NUM> is open, the program store the data with time <NUM> and goes back to sleep <NUM>, but if the valve position <NUM> is closed the microcontroller <NUM> read and compute sensor data <NUM> from at least one of the said sensors <NUM>, <NUM>, <NUM>, and accelerometer <NUM> and temperature sensor <NUM>.

The microcontroller <NUM> then correlates the measured leak data <NUM> with a pre-defined leak data <NUM> and if the measured leak data <NUM> conforms with the pre-defined leak data <NUM>, a leak is detected <NUM> and a leak flow is estimated <NUM> and a leak alarm <NUM> is generated and stored with real time and SDV <NUM> specific information in the microcontroller <NUM>, and the microcontroller <NUM> can go back to sleep <NUM>.

If the measured leak data <NUM> does not compare to a predefined leak data <NUM>, no leak data is stored and the microcontroller <NUM> can go back to sleep <NUM> and wait for the above sequence from <NUM> to sleep <NUM> to be repeated by either the interrupt of the shock sensor <NUM> or wake-up call set by operational procedures to typically between <NUM> hour to <NUM> hours in the wake up timer <NUM>.

Or where the predictor <NUM> intended to record if the flow-controlling element <NUM> sticks in closed or open valve position or where the said SDV is worn by wear and tear, where a plant-control system energizes or de-energizes the hydraulic or pneumatic pressure in the actuator <NUM> monitored by the actuator pressure sensor <NUM> and the movement of the actuator <NUM> turns the stem <NUM> to open or close the flow-controlling element <NUM>.

The plant-control system while energizing or de-energizing the hydraulic or pneumatic pressure in the actuator <NUM>, intermittently closes a normally open contact valve control <NUM> and where at least one strain gauge sensor <NUM> measures the dynamic force induced on the flow controlling element <NUM> by the rotational torque generated by the actuator <NUM> and where the sensor cable <NUM> from strain gauge sensor <NUM> and the sensor cable <NUM> from actuator pressure sensor <NUM> and the sensor cable <NUM> from remote valve control <NUM> may be connected in junction box <NUM> and wired through multi-sensor cable <NUM> or alternatively sensor cable <NUM>, <NUM> and/or <NUM> be connected to the predictor <NUM>.

External sensor interface <NUM> which is controlled by the microcontroller <NUM>, will read the signal from the strain gauge sensor <NUM> and detect the stem torque <NUM> and the signal from the actuator pressure sensor <NUM> to the actuator pressure <NUM> and the signal from the remote valve control <NUM> to the actuator trigger <NUM>.

And where a change of state in at least one actuator triggers <NUM> awake the microcontroller <NUM> to wake- up from sleep mode which is further described in the flow chart in <FIG>, which illustrates the program steps for the said microcontroller <NUM>, where START <NUM> is in the initial sleep mode state of the microcontroller <NUM> and at least one actuator trigger <NUM> generate an activation signal where the microcontroller <NUM> wake up <NUM> and reads sensor data <NUM> from the sensors <NUM> and <NUM>, motion sensor <NUM>, accelerometer sensor <NUM>, shock sensor <NUM> and temperature sensor <NUM>. And microcontroller <NUM> transmit said sensor signals through the wireless interface <NUM> through the wireless interface <NUM> to the microcontroller <NUM> which then reads computed sensor data <NUM> from at least one of the said sensors <NUM>, <NUM>, <NUM>, accelerometer sensor <NUM> and temperature sensor <NUM> and then the microcontroller <NUM> correlate the measured leak data <NUM> with a pre-defined leak data <NUM>. If the measured leak data <NUM> conforms with the pre-defined leak data <NUM> a leak is detected <NUM> and a leak flow is estimated <NUM> and a leak alarm <NUM> generated and data is stored with real time. The SDV <NUM> specific information is stored in the microcontroller <NUM>, and the microcontroller <NUM> can go back to sleep <NUM>.

If the measured leak data <NUM> does not compare to a pre-defined leak data <NUM>, no leak data is stored and the microcontroller <NUM> can go back to sleep <NUM> and wait for the above sequence from <NUM> to <NUM> to be repeated by either the interrupt of the shock sensor <NUM> or wake-up call set by operational procedures to typically between <NUM> hour to <NUM> hours in the wake-up timer <NUM> and the microcontroller <NUM> reads sensor data <NUM> from at least one of the said sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>.

The microcontroller <NUM> then compute the measured stiction data <NUM> and compare with the pre-defined acceptable stiction data <NUM> which define the conditions for acceptable stiction in SDV <NUM> and therefore if correlation of stiction data <NUM> is outside acceptable limits, stiction deviation data <NUM> is stored and a stiction alarm <NUM> is generated and stored with real time SDV <NUM> specific information in the microcontroller <NUM>.

If the measured stiction data <NUM> does not compare to a pre-defined stiction data set <NUM> no stiction deviation is detected and the microcontroller <NUM> compute the measured movement data set <NUM> and compare with the pre-defined acceptable movement data <NUM> which defines the conditions for acceptable movement of the flow-controlling element <NUM> and therefore if correlation of movement data <NUM> is out of acceptable limits due to wear and tear or other actuator problems, movement deviation data <NUM> is stored and a movement alarm <NUM> is generated and stored with real time and SDV <NUM> specific information in the microcontroller <NUM>.

Claim 1:
A system for detecting abnormal operating conditions in a shutdown valve, the system including a shutdown valve (SDV <NUM>) with an inlet pipe (<NUM>), an outlet pipe (<NUM>), a flow-controlling element (<NUM>) located between said inlet and outlet pipes, a stem (<NUM>) connected to the flow-controlling element (<NUM>) driven by an actuator arrangement (<NUM>),
wherein the system further includes a first detector system for detecting stiction of the flow-controlling element (<NUM>), including a first predictor (<NUM>) connected to the stem (<NUM>), with an accelerometer sensor (<NUM>) detecting rotational acceleration of the stem (<NUM>) and
a motion sensor (<NUM>) detecting rotational motion of the stem (<NUM>), the first predictor detecting the position of the flow-controlling element (<NUM>) transferred through the stem (<NUM>), and
a second detector system for detecting a leak in the flow-controlling element (<NUM>), including a second predictor (<NUM>) for detecting vibrations in the flow-controlling element (<NUM>).