Industry
Flow, pressure, temperature and analysis instruments for boiler, turbine, cooling and emissions duties.
A power station is a heat balance with instruments attached. Almost everything measured there exists to establish how much energy went in, how much came out and where the difference went, which is why steam flow, feedwater flow, pressure and temperature are measured with more care than the same quantities would receive in a general process plant.
The sector also packs very different conditions into one plot. A boiler sees high temperature and pressure together with a water chemistry that has to be controlled to protect the metal. A turbine hall needs vibration, speed and metal-temperature measurement that will survive a fast transient. A cooling water circuit deals with large pipes, dirty water and a requirement for a reliable flow figure rather than a precise one. No single specification covers all three, and applying one across a site is how instruments end up either over-specified or unsuitable.
Steam is the measurement that most often surprises buyers. It is hot, it is compressible and it changes state, so a volumetric reading means nothing without the line pressure and the temperature behind it, and that compensation is part of the measurement rather than a refinement added afterwards. Establishing who performs it - the transmitter, a flow computer or the control system - is worth settling before the instrument is chosen.
Fuel handling, feed rate, combustion air and flue gas. The measurements here determine both the efficiency figure and the emission record, so they are frequently tied to a reporting obligation as well as to control.
Water chemistry, steam flow, drum level, pressure and temperature. The chemistry and the steam measurement are both protective, because they protect the boiler and the turbine from damage rather than optimising the process.
Speed, vibration, bearing and metal temperature and power output. Several of these are protective rather than controlling, and they are expected to survive a fast transient without being damaged by it.
Cooling water flow, condenser performance, condensate and auxiliary systems. Large pipes and aggressive water mean the flow technology is chosen for reliability and for fitting the pipe rather than for the tightest accuracy.
| Measurement | What is measured in this sector | Instruments commonly specified |
|---|---|---|
| Flow | Steam, feedwater, condensate, fuel, cooling water and flue gas | Vortex and differential-pressure installations for steam with pressure and temperature compensation, electromagnetic or ultrasonic meters for water, Coriolis where a mass figure is needed, and differential-pressure or thermal measurement for gas |
| Pressure | Drum and superheater pressure, steam header pressure, condenser vacuum and differential across filters and strainers | Pressure and differential transmitters rated for the temperature at the tapping, frequently with impulse lines or seals, and vacuum-rated instruments for the condenser |
| Temperature | Superheated and reheated steam, boiler and turbine metal, bearing temperature, and the temperature used to compensate steam flow | Thermocouples for the hot and fast duties, RTDs where a stable and traceable reading is wanted, and surface or embedded measurement for metal temperature |
| Level | Boiler drum, deaerator, condenser hotwell, fuel and ash handling | Differential-pressure and hydrostatic transmitters with the density compensated, plus independent switches or a redundant channel where drum level protection is required |
| Analysis | Boiler and feedwater chemistry, dissolved oxygen, conductivity and pH, plus flue gas oxygen and carbon monoxide | In-line water chemistry analysers with sample conditioning, and combustion analysers mounted where the sample is representative and the analyser remains accessible |
| Vibration and speed | Turbine, pump and fan vibration, rotating speed and over-speed protection | Proximity and accelerometer based vibration measurement, and speed sensors arranged so that protection remains independent of the control system |
Which of these is appropriate depends on the unit, its duty and the standard the installation follows. The protective measurements in this sector normally carry their own redundancy requirement.
Frequently asked
The questions that come up in this sector before an order. If yours is not here, send it with the duty and we will answer it alongside the quotation.
Normally with a vortex meter or a differential-pressure installation, because steam is hot, compressible and not conductive. The figure that matters is mass flow, so the reading has to be compensated with line pressure and temperature and the correct steam table, and the compensation is part of the measurement rather than an addition to it. State saturated or superheated, the pressure, the temperature and the maximum flow, and the installation follows.
Because getting it wrong in either direction damages the plant - too low risks the tube metal, too high carries water into the superheater and the turbine. As a result the requirement is normally for redundancy and for independence from the control system, and it comes from the plant standard rather than from the instrument. Mention at the enquiry whether the channel is for control, for protection, or both.
Where the water treatment regime depends on continuous control rather than on grab samples, yes, and the analysers are protective equipment rather than process equipment. Conductivity, pH and dissolved oxygen are the recurring measurements, and each needs sample conditioning that keeps the sample within the sensor limits. The treatment regime decides which parameters are monitored continuously.
By the pipe and by whether the line can be opened, more than by the accuracy. A large circulating water main is usually measured with an electromagnetic or ultrasonic meter, and where the line cannot be cut, a clamp-on ultrasonic set is used and a lower accuracy accepted in exchange for not taking the unit out of service. Give the pipe size, the material, the flow range and whether there is an outage available.
Yes, against a stated protection concept, and the classified areas in a power station are usually around fuel handling and generator cooling rather than across the whole site. Give us the zone, the gas group and the temperature class from the site drawing, and we will confirm which models can be offered and which approvals correspond to them. Assuming a classification is not something we will do.
The unit and the duty, the medium and its condition at the tapping, the range and the required figure - volumetric or mass - the compensation arrangement for steam, the connection and material standard, the area classification and whether the measurement is protective. Where an emission obligation applies, say so, because the method may be fixed before the instrument is considered.
Published products
DL-16 · Industrial Data Loggers Reference listing
Standalone multi-channel data logger recording temperature, voltage and current inputs at programmable intervals, with internal memory and network export.
DMM-600 · Digital Multimeters Reference listing
True RMS benchtop digital multimeter for voltage, current, resistance, capacitance and continuity, with a CAT III safety rating and data logging output.
DPM-48 · Panel Meters Reference listing
Panel-mounted digital indicator accepting 4-20 mA, voltage or RTD input, with programmable scaling and relay outputs for local alarm duty.
PCAL-60 · Pressure Calibrators Reference listing
Handheld pressure calibrator combining a hand pump and a reference sensor, generating pressure and measuring the transmitter output in a single instrument.
PTX-200 · Pressure Transmitters Reference listing
Two-wire 4-20 mA pressure transmitter with a stainless steel wetted diaphragm, available in gauge, absolute and compound ranges for process and utility duties.
RTD-PT100 · RTD Temperature Sensors Reference listing
PT100 resistance thermometer assembly with a stainless steel sheath, available in two, three and four-wire configurations for process and laboratory duty.
UTG-5 · Ultrasonic Thickness Gauges Reference listing
Portable ultrasonic thickness gauge measuring remaining wall thickness of metals and plastics from one side, for corrosion survey and inspection work.
Send the process conditions and the standard you have to meet, and we will confirm the instrument, availability and documentation that can accompany the order.
Request for quotation
Send the technical detail and we will confirm availability, lead time and terms. In-stock items ship within 48 hours; customized specifications typically take 2-10 days. Minimum order quantity is 1 pc.