Valve driving with mechanical delay

Abstract

The present invention provides an electro-pneumatic arrangement to act as a mechanical timer (delay) in ON-OFF valve actuators. The arrangement comprises: two directional valves (1 and 2) with three ways and two positions, actuated by solenoid; a three-way, two-position directional valve (3), actuated by a pneumatic pilot; a set of compressed air conditioning with filter and pressure regulating valve (4); a valve metering (precise flow rate adjustment) (5), a check valve (6); and an accumulator vessel (7).

Claims

1. A valve driver with a mechanical delay, the valve driver comprising; two directional valves, each of the two directional valves having three ways and two positions, each of the two directional valves actuated by an electrical solenoid; a three-way, two-position directional valve actuated by a pneumatic pilot fluidically coupled and actuable by the two directional valves; a set of compressed air conditioning with filter and pressure regulating valve; an accumulator vessel; flowrate adjustment valve arranged and configured to regulate a flowrate from the accumulator vessel; a check valve arranged and configured to allow flow into the accumulator vessel.

2. The valve driver according to claim 1, wherein a valve being driven by the valve driver is a blowdown valve (BDV), wherein the pressure regulating valve, a volume of the accumulator vessel, and the flowrate adjustment valve are configured to adjust an opening time of the BDV.

3. The valve driver according to claim 2, wherein the opening time is sufficient enough to allow a staggered depressurization of a process unit, delaying an opening of the BDV, during electric power loss of controllers coupled to the valve driver.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The present invention will be described in more detail below, referring to the attached figures which, in a schematic way and not limited of the inventive scope, represent examples of its realization. The drawings show:

(2) FIG. 1 illustrating the schematic diagram of the mechanical timing system by driving delay of the present invention

(3) FIG. 2 illustrating the system of the invention with pneumatic energy, ready to operate;

(4) FIG. 3 illustrating the system of the invention with pneumatic and electrical energy, wherein the solenoid is energized (2), which inhibits the timing;

(5) FIG. 4 illustrating the command for the activated solenoid (1) and the actuated closed BDV, in operating position;

(6) FIG. 5 illustrating normal operation, with commanded BDV opening, without timing;

(7) FIG. 6 illustrating normal operation, with commanded BDV closure;

(8) FIG. 7 illustrating the situation with the loss of power supply, in which the BDV remains closed and the circuit starts to be timed; and

(9) FIG. 8 illustrating the open BDV after the adjusted delay.

DETAILED DESCRIPTION OF THE INVENTION

(10) Below follows a detailed description of a preferred embodiment of the present invention, by way of example and in no way limiting. Nevertheless, it will be clear to a person skilled in the art, from the reading of this description, possible additional embodiments of the present invention further comprised by the essential and optional features below.

(11) The invention refers to a device (electropneumatic panel) for activating an ON-OFF valve (BDV) with mechanical delay. Said device came up with the need to time the opening of the BDV after a scenario of electrical energy loss from the controllers, which cannot be prevented with programming logic.

(12) The arrangement of the present invention and illustrated in FIG. 1 comprises: two directional valves (1 and 2) with three ways and two positions, actuated by solenoid; a three-way, two-position directional valve (3), actuated by a pneumatic pilot; a set of compressed air conditioning with filter and pressure regulating valve (4); a valve metering (precise flow rate adjustment) (5), a check valve (6); and an accumulator vessel (7).

(13) Initially, compressed air (A.I.) is aligned from the process plant to the set and the system is pressurized with the directional valves (1, 2 and 3) in the off position, as shown in FIG. 2.

(14) With the system of the invention ready for operation, the solenoid that actuates the directional valve (2) is energized, inhibiting the timing path. This is the normal operating condition, which enables the driving of the BDV, by the control system, without timing, that is, under normal operating conditions. This configuration is illustrated in FIG. 3. The BDV can be actuated by energizing the directional valve solenoid (1), as shown in FIG. 4.

(15) Removing the energy from the solenoid of (1), the BDV will return to the safety situation, by the action of the spring of its actuator. The BDV driving occurs normally, without timing (delay) by the circuit, as shown in FIG. 5.

(16) The BDV valve can be operated normally, without delaying its driving. FIG. 6 again shows the command and configuration for actuation (closing) of the BDV.

(17) However, if the BDV is actuated (normal operating mode) and a loss of electrical power occurs in the control system, both directional valve solenoids (1 and 2) will lose power and go to the safe position through the spring force moving its spool. At this moment, the directional valve (2) activates the timing path in the circuit, initiating the controlled depressurization of the accumulator vessel (7) through the mettering valve (5). When the circuit pressure drops enough to disable the piloted directional valve (3), the BDV will open.

(18) The design of the delay time adjustment contemplates the variables: regulated pressure in (4), accumulator volume in (7) and flow rate adjusted by the mettering valve (5). The times are defined for each valve, allowing a staggered opening (depressurization) in the process unit. The BDV opening takes place quickly, so as not to allow freezing, if it presents potential. The delay system does not interfere with the normal operation of the BDV, either by the safety controller or manually by the control operator.

(19) FIG. 7 represents the actuated BDV and timing its opening, once the solenoids are de-energized. FIG. 8 shows the BDV opened after the configured delay.