Tracer gas airflow measurement system with high turndown ratio

An apparatus for injecting tracer gas into a bulk fluid flow, comprising:

• (a) a source of high pressure tracer gas, said tracer gas having a pressure greater than approximately 100 psi;
• (b) a heating element fluidly coupled to the source of tracer gas configured to heat the tracer gas isobarically at a first pressure;
• (c) a pressure regulator fluidly coupled to the heating element, the regulator configured to reduce the pressure of said heated tracer gas to a second pressure;
• (d) at least one control valve fluidly coupled to the pressure regulator;
• and
• (e) an injector head fluidly coupled to the control valve;
• (f) wherein said control valve modulates a flow of tracer gas emitted through said injector head;
• (g) wherein said control valve comprises:
• a mass flow controller with a high turndown ratio;
• and
• a mass flow meter;
• and
• (h) wherein the apparatus modulates tracer gas flow using the mass flow controller.

An apparatus for injecting tracer gas into a bulk fluid flow, comprising:

• (a) a source of high pressure tracer gas, said tracer gas having a pressure greater than approximately 100 psi;
• (b) a heating element fluidly coupled to the source of tracer gas configured to heat the tracer gas isobarically at a first pressure;
• (c) a pressure regulator fluidly coupled to the heating element, the regulator configured to reduce the pressure of said heated tracer gas to a second pressure;
• (d) at least one control valve fluidly coupled to the pressure regulator;
• and
• (e) an injector head fluidly coupled to the control valve;
• (f) wherein said control valve modulates a flow of tracer gas emitted through said injector head;
• and
• (g) wherein said injector head comprises a perforated tubular wand.

An apparatus for injecting tracer gas into a bulk fluid flow, comprising:

• (a) a source of high pressure tracer gas, said tracer gas having a pressure greater than approximately 100 psi;
• (b) a heating element fluidly coupled to the source of tracer gas configured to heat the tracer gas isobarically at a first pressure;
• (c) a pressure regulator fluidly coupled to the heating element, the regulator configured to reduce the pressure of said heated tracer gas to a second pressure;
• (d) at least one control valve fluidly coupled to the pressure regulator;
• and
• (e) an injector head fluidly coupled to the control valve;
• (f) wherein said control valve modulates a flow of tracer gas emitted through said injector head;
• (g) wherein said injector head comprises:
• a manifold body with a central chamber and a plurality of openings;
• and
• flexible tubes disposed in said openings of said manifold body;
• and
• (h) wherein tracer gas is emitted through said central chamber and out an open end of said flexible tubes.

A method of injecting a volume of tracer gas into a bulk fluid flow, the method comprising:

• (a) heating pressurized tracer gas isobarically at a first pressure greater than 100 psi;
• (b) reducing the pressure of heated tracer gas to a second pressure with a pressure reducer;
• (c) modulating tracer gas flow with a mass flow controller with a high turndown ratio;
• and
• (d) injecting tracer gas into a bulk fluid flow with an injector head;
• (e) wherein temperature of said pressure reducer and said mass flow controller does not drop below the freezing point of water.

A tracer gas injector apparatus for an airflow measurement system, comprising:

• a CO2 cylinder coupled with a heating element;
• a pressure regulator communicating with an output duct of the heating element;
• and
• a control valve;
• wherein the system vaporizes liquid CO2 by allowing phase change within the CO2 cylinder;
• wherein the system heats the CO2 vapor isobarically at high pressure (>100 psi);
• wherein the system expands the hot gas across the pressure regulator to a lower working pressure;
• and
• wherein the system modulates gas flow using the mass flow controller with a high turndown ratio.