MICROMETRIC VALVE ACTUATOR DEVICE FOR GAS PRESSURE CONTROL

Abstract

The present invention addresses to a device that allows the control of the gas pressure at the outlet of a fixed bed adsorption equipment operated at high pressures, by means of the actuation of a micrometric valve (6), wherein the valve must be located downstream of the equipment. The valve actuation takes place by means of a stepper motor (1), controlled by a microcontroller board (22), which connects to the valve shaft by means of a system of pulleys (2, 5) and belt (3). The present invention is applied in adsorption units, in which other gases are present, by altering the tuning parameters of the PID controller or even being used in a liquid medium or gas-liquid two-phase flow.

Claims

1 A MICROMETRIC VALVE ACTUATOR DEVICE FOR GAS PRESSURE CONTROL, characterized in that it comprises a stainless steel support (4) having a base with holes (7) for wall fixing, allowing the fixing of a stepper motor (1) and a micrometric valve (6); it has an actuation system by means of a toothed pulley (5) coupled to the metric valve head (6), connected by a toothed belt (3) to a toothed pulley (2), allowing the transfer of movement from the stepper motor shaft (1) to the micrometric valve (6); a microcontroller board (22); buttons for motor manual driving (24, 25); a signal converter (21); and a stepper motor driver device (23).

2 THE DEVICE according to claim 1, characterized in that the toothed pulley (5) is a toothed pulley with 40 teeth and the toothed pulley (2) is a toothed pulley with 20 teeth.

3 THE DEVICE according to claim 1, characterized in that the toothed belt (3) is a toothed belt with 6 mm thickness and 2 mm spacing between the teeth.

4 THE DEVICE according to claim 1, characterized in that the micrometric valve (6) is of the needle type.

5 THE DEVICE according to claim 1, characterized in that the driver device (23) is controlled by an Arduino Mega 2560 microcontroller board (22), which requests by means of a I2C-RS485 signal converter (21) the pressure recorded by a data acquisition module (20).

6 THE DEVICE according to claim 1, characterized in that the microcontroller board (22) provides the operating modes to said device: open or close with buttons (9), pressure control (10), fully close valve (11) and fully open valve (12).

7 THE DEVICE according to claim 6, characterized in that it operates in pressure control mode (10), using a PID controller with anti-windup mechanism (13), allowing the control of the pressure inside an adsorption bed at high pressures (16), when it is pressurized with gases present in natural gas.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0018] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

[0019] FIG. 1 illustrating a perspective view of the device of the present invention;

[0020] FIG. 2 illustrating a flowchart of the internal functioning of the device of the present invention;

[0021] FIG. 3 illustrating a flowchart of the operation of the device in the gas adsorption unit at high pressures;

[0022] FIG. 4 illustrating the pressure response during pressurization in an adsorption unit at high pressures, when the device is installed.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The micrometric valve actuator device for gas pressure control according to the present invention and illustrated in FIG. 1 comprises the following components: [0024] a stainless steel support (4), which has a base with holes (7), for wall mounting; [0025] a micrometric valve (6); [0026] a stepper motor (1); [0027] a toothed pulley with 40 teeth (5); [0028] a toothed pulley with 20 teeth (2); [0029] a toothed belt with 2 mm spacing between the teeth and 6 mm thickness (3) connects the two pulleys, allowing the transfer of movement from the stepper motor shaft (1) to the needle valve (6), without the vertical opening movement of the needle valve (6) being impaired; [0030] a microcontroller board (22); [0031] buttons for motor manual driving (24) and (25); [0032] a I2C-RS485 signal converter (21); [0033] a stepper motor driver device (23);

[0034] As shown in FIG. 1, a stainless steel support (4), which has a base with holes (7), for wall mounting, holds tight a micrometric valve (6) and a stepper motor (1). A pulley with 40 teeth (5) is attached to the needle valve head (6). A toothed pulley with 20 teeth (2) is connected to the stepper motor shaft (1). A toothed belt with 2 mm spacing between the teeth and 6 mm thickness (3) connects the two pulleys, allowing the transfer of movement from the stepper motor shaft (1) to the needle valve (6), without the movement vertical opening of the needle valve (6) being impaired.

[0035] According to FIG. 2, the stepper motor (1) is controlled by a driver device (23) with a supply voltage of 24 V, average current of 1.5 A with a peak of 1.7 A, with overvoltage and short circuit protection and optically isolated digital inputs. The device reproduces, at the specified voltage and current, the train of pulses sent by the Arduino Mega 2560 microcontroller board (22) at low current.

[0036] According to FIG. 2, the microcontroller board (22) functions as a MODBUS master and slave device, with an initialization algorithm followed by an algorithm that operates in a loop, allowing four modes of operation: control by means of buttons; operating pressure control; fully close; and fully open.

[0037] According to FIG. 3, in the button operation mode (9), two buttons, one designed to open (24) and the other designed to close (25) the needle valve, are connected to the microcontroller board (22). The microcontroller board (22) checks which button is pressed and opens or closes the valve accordingly, in the smallest number of steps previously specified (8).

[0038] In the pressure control operating mode (10), the controller requests the pressure recorded by the data acquisition module (20), by means of the I2C-RS485 converter (21), using MODBUS protocol. The pressure is recorded and compared to the set-point pressure. The pressure error is used to compute the control response by means of a PID controller with anti-windup mechanism (13).

[0039] In the fully close operation mode (11), the controller checks the valve position and returns to the position determined as zero.

[0040] In the fully open operating mode (12), the controller checks the valve position and rotates it to the position determined as fully open.

[0041] The movement of the motor shaft is controlled by a pulse train with variable frequency, which allows acceleration to the desired rotation, stabilization and deceleration until reaching the required number of steps.

[0042] As shown in FIG. 3, the device is installed in an adsorption module at high pressures that has a gas cylinder (14), a mass flow rate controller (15), an adsorption bed (16) at high pressures, a pressure transducer (17), a mass flow rate indicator (18) and the present invention (19).

[0043] In FIG. 4, there is shown that the bed pressure is controlled when it contains methane (27) or a mixture of methane with carbon gas (28). When changing the set-point pressure (31), the micrometric valve (6) is partially closed, causing the outlet flow rate (30) to be reduced. As the inlet flow rate (29) remains constant by means of the mass flow rate controller (15), there is an increase in the gas pressure (32) inside the adsorption bed (16). When the gas pressure (32) approaches the value of the Set-point (31), the micrometric valve (6) partially opens, causing the outlet flow rate (30) to increase, regulating the pressure inside the bed of adsorption (16) at pressure values that differ from the Set-point value by a maximum of 0.06 bar (6 kPa), as indicated in (33) for methane gas and in (34) for the gaseous mixture of methane and carbon gas.

EXAMPLES

[0044] The following examples are presented in order to illustrate some particular embodiments of the present invention, and should not be interpreted as limiting the same. Other interpretations of the nature and mechanism of obtaining the components claimed in the present invention do not alter the novelty thereof.

[0045] The experiments performed can be seen in FIGS. 3 and 4.

[0046] As shown in FIG. 3, the device was installed in an adsorption module at high pressures that has a gas cylinder (14), a mass flow rate controller (15), an adsorption bed (16) at high pressures, a pressure transducer (17), a mass flow rate indicator (18) and the present invention (19).

[0047] In FIG. 4, there is shown that the bed pressure is controlled when it contains methane (27) or a mixture of methane with carbon gas (28). Initially, the gas is flown with a well-defined initial flow rate and, at a given moment, the Set-point pressure is changed. When changing the Set-point pressure (31), the micrometric valve (6) is partially closed, causing the outlet flow rate (30) to be reduced. As the inlet flow rate (29) remains constant by means of the mass flow rate controller (15), there is an increase in the gas pressure (32) inside the adsorption bed (16). When the gas pressure (32) approaches the value of the Set-point (31), the micrometric valve (6) partially opens, causing the outlet flow rate (30) to increase, regulating the pressure inside the bed of adsorption (16) at pressure values that differ from the Set-point value by a maximum of 0.06 bar (6 kPa), as indicated in (33) for methane gas and in (34) for the gaseous mixture of methane and carbon gas.

[0048] It should be noted that, although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that it is within the inventive scope defined herein.