Method of compensating for mass flow using known density
A method for determining a mass flow measurement is provided. The method comprises calibrating a flowmeter sensor at a first temperature and flowing a fluid having a second temperature through the flowmeter sensor. A density of the fluid is input into meter electronics. A compensated mass flow value of the fluid is determined by meter electronics, wherein the Modulus of Elasticity of the flowmeter sensor is unknown.
1. A method for determining a mass flow measurement, comprising:
calibrating a flowmeter sensor at a first temperature;
flowing a fluid having a second temperature that is different from the first temperature through the flowmeter sensor;
inputting a density of the fluid into a flowmeter electronics;
determining a compensated mass flow value of the fluid with the meter electronics, without using a function that utilizes a temperature or Modulus of Elasticity;
wherein the compensated mass flow rate is calculated as:
m
.
=
FCF
·
(
Δ
t
-
zero
)
·
ρ
f
·
(
1
+
α
·
Δ
T
)
3
+
C
2
K
2
·
C
1
where:
{dot over (m)}=mass flow
FCF=Flow Calibration Factor (units: g/s per μs)
Δt=fundamental Coriolis time measurement
zero=Δt at no-flow conditions
ρ f =fluid density
α=thermal expansion coefficient
C1 & C2=calibration constants
K 2 =Period squared.
2. The method of claim 1 , wherein the density is a known reference value.
3. The method of claim 1 , wherein the density is calculated from an equation of state.
4. The method of claim 3 , wherein the equation of state comprises a pressure term and a temperature term.
5. The method of claim 1 , wherein the accuracy of the compensated mass flow value is ±0.5%.
6. The method of claim 1 , wherein the first temperature is a non-cryogenic temperature, and the second temperature is a cryogenic temperature.
7. A flowmeter ( 5 ) comprising meter electronics ( 20 ) configured to receive a process fluid having a second temperature, the meter electronics ( 20 ) configured to communicate with a sensor assembly ( 10 ) of the flowmeter ( 5 ), wherein the flowmeter ( 5 ) comprises:
at least one flow conduit ( 103 A, 103 B) configured to receive the process fluid;
at least one driver ( 104 ) configured to vibrate the at least one flow conduit ( 103 A, 103 B);
and at least one pickoff ( 105 , 105 ′) for detecting vibrations of the at least one flow conduit ( 103 A, 103 B);
wherein the flowmeter is calibrated at a first temperature;
wherein a density of the fluid is input into meter electronics ( 20 ); and
wherein the meter electronics ( 20 ) is configured to determine a compensated mass flow value of the fluid without using a function that utilizes a temperature or Modulus of Elasticity of the at least one flow conduit ( 103 A, 103 B) as variables;
wherein the compensated mass flow rate is calculated as:
m
.
=
FCF
·
(
Δ
t
-
zero
)
·
ρ
f
·
(
1
+
α
·
Δ
T
)
3
+
C
2
K
2
·
C
1
where:
{dot over (m)}=mass flow
FCF=Flow Calibration Factor (units: g/s per μs)
Δt=fundamental Coriolis time measurement
zero=Δt at no-flow conditions
ρ f =fluid density
α=thermal expansion coefficient
C1 & C2=calibration constants
K 2 =Period squared.
8. The flowmeter ( 5 ) of claim 7 , wherein the density is a known reference value.
9. The flowmeter ( 5 ) of claim 7 , wherein the density is calculated from an equation of state.
10. The flowmeter ( 5 ) of claim 9 , wherein the equation of state comprises a pressure term and a temperature term.
11. The flowmeter ( 5 ) of claim 7 , wherein the accuracy of the compensated mass flow value is ±0.5%.
12. The flowmeter ( 5 ) of claim 7 , wherein the first temperature is a non-cryogenic temperature, and the second temperature is a cryogenic temperature.