JPWO2020154197A5 - - Google Patents

Description

Many industrial processes require accurate and precise measurement and control of various process fluids. Certain processes, such as measuring incompressible fluids (e.g., liquids), volumetric flow rates (e.g., liters per minute (lpm), standard cubic centimeters per minute (sccm), or even cubic meters per second (m ³ /s)) Just measure. However, other processes, such as measuring compressible fluids (e.g., gases), may require mass flow rate measurements (e.g., milligrams per minute (mg/m), or kilograms per second (kg/s)). many. Therefore, for compressible fluids, the discussion of the fluid's volumetric mass density (also referred to herein simply as mass density) may be considered a function of absolute pressure and temperature. For example, the semiconductor and related industries use mass flow meters and mass flow controllers to accurately and precisely measure and control the mass of process fluid introduced into a process chamber. A wide variety of techniques can be used to measure flow rates in devices such as thermal devices, ultrasonic time-of-flight devices, Coriolis devices, and pressure-based devices.

Referring now to FIG. 2, a cross-sectional view of one embodiment of a differential pressure-based flow meter 200 according to the subject matter of this disclosure is shown. A differential pressure based flow meter 200 is shown including a fluid inlet 201 and a fluid outlet 203 for fluid to flow through a flow path 205 . FIG. 2 is also shown to include a flow sensor 207 having a first side 207A and a second side 207B, as well as a flow restriction element 211 and a flowmeter body 215. FIG. Since the fluid flowing through flow path 205 is in direct hydraulic or pneumatic communication with flow sensor 207, the first and second pressure ports 105A of FIG. 105B need not relay pressure to the first and second cavities 103A, 103B. As a result, pressure ports 105A, 105B and cavities 103A, 103B are not required in various embodiments of the disclosed subject matter, so there is no dead volume that can trap and later release contaminants. Furthermore, because the flow path is continuous, differential pressure based flow meter 200 is continuously flushed during operation.

With continued reference to FIG. 2 , first bend 209 and second bend 213 are on opposite sides of flow restricting element 211 . However, for a given implementation of differential pressure-based flow meter 200, if fluid flow is desired to be in the laminar flow regime, at least one of first bend 209 and second bend 213 may each , upstream and downstream of the flow restricting element 211, respectively, at least 5-7 diameters (based on internal dimensions and assuming a circular cross-section of the channel). Alternatively, or in addition to increased path lengths of at least 5-7 diameters, various rectifier devices known in the art may be used within channel 205 as well. Based on basic principles of fluid mechanics, those skilled in the art will recognize how to arrange and size the channels 205 to accommodate laminar fluid flow. For example, if the channel 205 does not have a circular cross-sectional area, other relevant factors such as the hydraulic diameter, e.g. An internal characteristic length dimension may be selected to restore laminar flow. Based on a reading and understanding of the subject matter of this disclosure, one skilled in the art will be able to determine the length of the flow path (e.g., before or after a bend) to provide a given fluid flow rate, fluid density, and fluid flow rate. One will recognize how to create laminar flow for kinematic viscosity.

Claims (20)

a flow meter,
a channel having an inlet and an outlet and configured to carry a fluid;
at least one flow restriction element within the flow path and positioned between the inlet and outlet of the flow path and configured to impart a pressure drop to the fluid;
a flow sensor positioned between the inlet portion and the outlet portion of the flow path, the first surface of the flow sensor being in direct contact with the fluid flowing upstream of the at least one flow restricting element; A second surface of the portion of the flow sensor configured in fluid communication opposite the first surface of the flow sensor is in direct fluid communication with the fluid flowing downstream of the at least one flow restricting element. wherein the flow sensor is configured to sense a differential pressure of the fluid across the at least one flow restriction element. A flow meter according to claim 1, wherein
The flow meter, wherein the at least one flow restricting element comprises a laminar flow element. A flow meter according to claim 1, wherein
A flow meter, wherein the at least one flow restricting element comprises an orifice. A flow meter according to claim 1, wherein
A flow meter, wherein the at least one flow restricting element comprises a plurality of orifices. A flow meter according to claim 1, wherein
The flow meter, wherein the inlet and outlet of the flow path are arranged substantially parallel to each other. A flow meter according to claim 1, wherein
The flow meter, wherein the inlet and outlet of the flow path are positioned at an angle between about 0° and about 45°. A flow meter according to claim 1, wherein
The flow meter, wherein the inlet and outlet of the flow path are positioned at an angle between about 45° and about 60°. The flow meter of claim 1 further comprising:
A flow meter comprising a first bend in said flow path upstream of said at least one flow restricting element and a second bend downstream of said at least one flow restricting element. A flow meter according to claim 1, wherein
At least one of said first bend and said second bend is at least 5-7 characteristic length dimensions away from said at least one flow restricting element, said characteristic length dimension A flow meter based on the internal dimensions of the channel. A flow meter according to claim 1, wherein
A flow meter, wherein the flow sensor is a differential pressure sensor. A flow meter according to claim 1, wherein
A flow meter, wherein a turndown ratio of said flow meter is at least about 100:1. a flow meter,
a channel having an inlet and an outlet and configured to carry a fluid, the channel having a single bend formed therein;
at least one flow restriction element within the flow path and positioned between the inlet and outlet of the flow path and configured to impart a pressure drop to the fluid;
at least one flow sensor having a first surface and a second surface opposite said first surface, said first surface of said flow sensor being aligned with said at least one flow restricting element. configured for direct fluid communication with said fluid flowing upstream, said second surface configured for direct fluid communication with said fluid flowing downstream of said at least one flow restricting element, said flow sensor comprising: A flow meter configured to sense differential pressure of the fluid across the at least one flow restricting element. 13. The flow meter of claim 12, comprising:
The flow meter, wherein the at least one flow restricting element is located within the single bend in the flow path. 13. The flow meter of claim 12, comprising:
The flow meter, wherein said at least one flow restricting element is a laminar flow element. 13. The flow meter of claim 12, comprising:
The flowmeter, wherein the at least one flow restricting element is a plate configured transverse to the direction of fluid flow having at least one orifice formed therethrough. 13. The flow meter of claim 12, comprising:
The single bend in the channel has a reduced cross-sectional area compared to the cross-sectional area of the rest of the channel, and the at least one flow restricting element reduces the reduced cross-sectional area. Have a flow meter. 13. The flow meter of claim 12, comprising:
The flow meter, wherein the cross-sectional area of the inlet portion of the channel is greater than the cross-sectional area of the outlet portion of the channel. 13. The flow meter of claim 12, comprising:
The flow meter, wherein the cross-sectional area of the outlet of the flow path is greater than the cross-sectional area of the inlet of the flow path. 13. The flow meter of claim 12, comprising:
A flow meter, wherein the flow meter is configured such that no dead volume is located therein. a flow meter,
an upstream sub-channel and a downstream sub-channel for carrying a fluid, the upstream sub-channel and the downstream sub-channel being substantially collinear with each other;
a flow sensor carrier disposed between said upstream sub-channel and said downstream sub-channel, transversely to the direction of said fluid being conveyed ;
at least one orifice formed through the flow sensor carrier in a direction substantially the same as the direction of the fluid, the at least one orifice providing a pressure drop between the upstream sub-channel and the downstream sub-channel; an orifice;
a flow sensor formed within the flow sensor carrier and having a first surface and a second surface opposite the first surface, the first surface of the flow sensor configured to be in direct fluid communication with the fluid flowing upstream of the sensor carrier, wherein the second surface of the flow sensor is configured to be in direct fluid communication with the fluid flowing downstream of the flow sensor carrier; A flow meter, wherein the flow sensor is configured to sense differential pressure of the fluid across the at least one orifice.