Overview
Applying the DX's mathematical functions, humidity is calculated using the dry bulb and wet bulb formulas based on input from a resistance temperature detector (Pt). The calculation follows the Perunta formula.
Customer Needs
- To have the humidity calculation function be internal to the DX, since we want to monitor humidity along with the internal temperature of the environmental testing equipment
- To use general purpose RTDs rather than specialized humidity sensors, and avoid depending on external instruments and complicated programming
Process Outline
Signals are input from Pt type RTD sensors. Dry and wet bulb temperature are measured with the Pt's, and the DX's calculation function automatically calculates humidity based on the measured values. The calculation is based on the Perunta formula, and the multipliers in the formula are input ahead of time as Kxx. Dedicated humidity sensors or external computing units are not needed to determine the humidity, resulting in reduced costs and more compact instrumentation. The number of instruments comprising the system is also reduced, resulting in higher overall reliability. Sensors can be hard to calibrate due to the difficulty of creating a reference humidity. The DX overcomes this problem because humidity is determined through a calculation, and calibration of the input can be substituted with calibration of the Pt100ohm range.
| Input: | Pt100 (or JPt100) |
|---|---|
| CH1: dry bulb°C), CH2: wet bulb°C) | |
| Computed result: | Humidity displayed on CH37 (MATH channel) |
| Expressions and constants: | Perunta formula |
| 31: | 1+K9 |
| 32: | 2+K9 |
| 33: | EXP(K1/31+K2+K3*31+K4*31*31+K5*LOG(31)) |
| 34: | EXP(K1/32+K2+K3*32+K4*32*32+K5*LOG(32)) |
| 35: | 33*K10 |
| 36: | 34*K10 |
| 37: | ((36-K6*K7*(K11+2/K8)*(1-2))/35)*K10 |
| K01: | -6096.9 |
| K02: | 16.636 |
| K03: | -0.027112 |
| K04: | 1.674E-5 |
| K05: | 5.6033 |
| K06: | 0.0012 (ramda) |
| K07: | 1.0133E+5 |
| K08: | 610 |
| K09: | 273.15 |
| K10: | 100 |
| K11: | 1 |
| K12: | 2 |
| K06 (ramda) value is set as follows | |
| When wind speed is 0-0.5 m/s: 0.0012 | |
| When wind speed is 1-1.5 m/s: 0.0008 | |
| When wind speed is 2.5 m/s or higher: 0.000656 |
Yokogawa's Solution
DX Series Paperless Recorders can easily calculate humidity using RTDs
- Humidity calculated with a MATH function (optional)
- Measured and calculated results saved electronically to local media while being displayed in real time on the large, color TFT display
- Enables data sharing on the network (Ethernet compatible)
Conclusion
 |
| DX |
DX series instruments allow you to determine temperature and humidity and manage the results as manufacturing/quality data at a reasonable cost with a simple configuration. No special external equipment or humidity sensors are required, resulting in overall cost reductions in the system.
Industrieën
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Offshore (FPSO FLNG & FSRU)
Offshore exploratie en productie vereist maximale uptime onder zware omstandigheden. Bemande en onbemande installaties hebben behoefte aan betrouwbare geïntegreerde controle- en veiligheidssystemen (ICSS) met geavanceerde mogelijkheden voor bewaking op afstand. Yokogawa beschikt over ultramoderne technologie en uitgebreide ervaring in de uitvoering van offshore projecten van elke omvang en complexiteit van de automatisering.
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Olie & gas
Yokogawa heeft diepgaande ervaring in elk deel van de olie- en gasindustrie. Van offshore- en onshore-installaties tot pijpleidingen, terminals en diepwateractiviteiten. Wij leveren oplossingen die de veiligheid verhogen, een nauwkeurige en betrouwbare werking garanderen en de efficiëntie van de installatie verhogen.
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Upstream olie & gas
De upstream-industrie omvat offshore- en onshore-activiteiten, waaronder automatisering van boorputten, raffinage, voltooiing en scheiding om ondergronds of onder water ruwe olie en aardgas te winnen en te bewerken.
Wanneer aardolie naar de oppervlakte wordt gebracht, moet het worden gescheiden voordat het wordt vervoerd. Primaire en secundaire scheidingsfasen verdelen gewoonlijk de gasstroom, waterstroom en oliestroom in een driefasen scheiding. Voor het vervoer van gas is een pijpleiding nodig en kan een raffinageproces in de upstream fase voorafgaand aan het vervoer plaatsvinden. Vloeistoffen kunnen via tanks of pijpleidingen voor verwerking worden verzonden, waarbij nauwkeurige niveaumetingen vereist zijn.
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