Steam and Water Sample Conditioning

Steam cycle power plant sampling

Mechatest Sample Conditioning Panels are pre-designed for proper conditioning of your steam and water samples.

We take care from sample tap to sampling conditioning and analysis specific but not limited to the steam cycle and power plant industry.

 

The conditioning has the main function to reduce and regulate the temperature, flow and pressure of the sample.

All our sampling systems are designed with best-in-class and critical components such as sample coolers, pressure reducing valves (VREL), back pressure regulators, relief valves, flow controllers and thermal shut off valves. We are a distributor of several leading brands like Sentry, Herpi, Therm-Omega and in house designed sample conditioning systems. The sampling panels are provided with highly efficient double helix coil-in-shell type sample coolers based on contra flow design and therefore require a very low cooling water flow. 

Standards

Sample Conditioning Panels built as per standard ASME PTC 19.11 and/or VGB/DGRL. 

 

Steam sample conditioning and collection system - Mechatest

Working

The Sample is first cooled in Sample Coolers, depressurized in pressure regulators and then fed to various analyzers while keeping the flow constant by means of a Back Pressure Regulating Device. There are different safety equipment provided in SCS panels, so that the operators feel safe while working with these systems.


Sample Conditioning Panels

Predesigned SCS for water application. 

  • Compact design with best selection of top of the world fabricate components 
  • Efficient temperature cooling with Sentry sample coolers, pressure reduction with Sentry VREL and flow control
  • Grab sample capability
  • Including Swan Back Pressure Regulator BPR for constant pressure and sample flow for up to 4 water analyzer applications
  • Custom options are available to fit your needs
  • Manufactured by Mechatest Sampling Solutions.

LPMT - Sampling Panel

Low Pressure Medium Temperature water sampling panels for Condensate samples. 

  • Max. pressure: 35 barg
  • Max. temperature: 250°C (recommended) 
  • Single phase samples: Water and Condensate
  • Applications: Boiler water, Feed water

LPHT - SAMPLING PANEL

Low Pressure High Temperature sampling panels are for
LP-Steam samples.

  • Max. pressure: 35 barg
  • Max. temperature: 538°C (recommended) 
  • Single phase samples: Low pressure steam
  • Applications: 

HPMT - SAMPLING PANEL

High Pressure Medium Temperature sampling panels are for HP-Steam samples.

  • Max. pressure: 340 barg
  • Max. temperature: 250°C (recommended) 
  • Mix phase samples: ?
  • Applications: 

HPHT - SAMPLING PANEL

High Pressure High Temperature sampling panels are for HP-Steam samples. 

  • Max. pressure: 340 barg
  • Max. temperature: 538°C (recommended) 
  • Mix phase samples: HP-Steam ??
  • Applications: ?

Sampling Components

Sentry Sample Coolers

  • Single Helical Tube Sample Cooler
  • Compact, high efficiency sample coolers for cooling high temperature/high pressure liquid or gas samples
  • Temperature ratings to 593°C at 345 barg (1100°F at 5000 psig)
  • Models available for ultra-supercritical power plants with temperature ratings to 621°C at 356 barg (1150°F at 5175 psig)
  • Exotic materials such as titanium, Inconel® and Hastelloy® on the tube side, and Monel®, cupronickel, and stainless steel on the shell side are available
  • Highest efficiency sample cooler commercially available
  • Various configurations available to meet EPRI/ASTM/ASME sampling guidelines
  • Many models are available with ASME section VIII code stamp, CE or CRN registrations
  • No dead spots or crevices 
  • Sample flow rates up to 5.7 liters per minute (1.5 gallons per minute GPM); for higher flow rates see

Pressure Reducing Valve Sentry VREL

  • High Pressure Sample Flow Control Valve
  • The VREL® is an adjustable sample pressure reducerfor sample pressures above 35 barg (500 psig). A precisely machined tapered rod assembly moves inside precision holes within the barrel of the VREL®. Pressure drop is a function of the length of the rods inserted into the barrel.

Sentry Thermal Shutoff Valve (with reset button)

  • Shuts down high temperature sample in less than 5 seconds.
  • Need to reset by push button after sample is cooling down
  • Protect operators, analyzers and sampling components from high temperature liquids with a Sentry Thermal Shutoff Valve. The sensor/actuator is directly exposed to the sample, providing quick reaction time. Economical and highly reliable replacement for solenoid shutoff valve and temperature controller.
  • Suitable for system pressures up to 4400 psi (303 bar)
  • Totally mechanical design requires no electricity, air, or hydraulics
  • Optional dry contact for remote indication
  • Standard trip temperature is 120ºF (49ºC) with other temperatures available
  • 316 Stainless Steel construction

Thermal Shutoff Valve (automatic)

  • ThermOmegaTech
  • Protects expensive and delicate sample analyzers
  • Automatically resets when sample cools
  • No outside power required
  • Superior value vs. more expensive electric valves

    Design Features
  • Self-operating thermal actuator controls flow based on fluid temperature
  • Operating temperatures unaffected by variable inlet pressures
  • Wide choice of setpoints available
  • Ram-type plug provides tight shutoff
  • Corrosion resistant: all stainless steel construction

     Operation
  • The HST (High Sample Temperature) safety shutoff valve is used to sense the sample temperature after the sample cooler. The sample passes through this normally open valve whenever the sample temperature is below the valve setpoint. If the sample temperature exceeds the valve setpoint, the HST closes to protect expensive and delicate analyzers and other instruments from overtemperature damage. When the HST cools below the setpoint, it will automatically reset open again. Low coolant flow or total loss of cooling water or unusually high sample temperatures are typical reasons why the HST self-operating protective device should be considered.

     Typical Applications
  • Excessively hot samples can cause damage to expensive and sensitive hardware and electronics. For process analyzers and similar instrumentation, it is important to assure that the process samples fluids are always below the maximum allowable temperature for such instruments. Sample coolers are commonly used to reduce sample temperatures to the acceptable limits. In the event of a loss of cooling fluid to the sample cooler, or if the desired sample temperature is exceeded for any reason, the HST valve will close to prevent equipment damage. HST valves are covered with our standard 36 month prorated warranty.

Refillable Cation Exchange Resin Columns

  • Minimize "dead volume" assuring representative samples
  • Three models* (RC-100, RC-200 and RC-400) meet your specific requirements, withstanding the demands of power plants
  • Column(s) provide optimum fluid velocity with increased resin efficiency
  • Color-changing resin gives quick visual indication of resin depletion level
  • Twist-off cap for easy resin refill with available pre-sized Sentry resin refill packets 
  • No PVC; wetted materials will not leach chlorides or plasticizers

Location of Sample Tap Point

Samples must be taken from locations that are representative of the water source, treatment plant, storage facilities, distribution network, points at which water is delivered to the consumer, and points of use. In selecting sampling points, each locality should be considered individually; however, the following general criteria are usually applicable:

  • Sampling points should be selected such that the samples taken are representative of the different sources from which water is obtained by the public or enters the system.
  • These points should include those that yield samples representative of the conditions at the most unfavourable sources or places in the supply system, particularly points of possible contamination such as unprotected sources, loops, reservoirs, low-pressure zones, ends of the system, etc.
  • Sampling points should be uniformly distributed throughout a piped distribution system, taking population distribution into account; the number of sampling points should be proportional to the number of links or branches.
  • The points chosen should generally yield samples that are representative of the system as a whole and of its main components.
  • Sampling points should be located in such a way that water can be sampled from reserve tanks and reservoirs, etc.
  • In systems with more than one water source, the locations of the sampling points should take account of the number of inhabitants served by each source.
  • There should be at least one sampling point directly after the clean-water outlet from each treatment plant.

Sampling sites in a piped distribution network may be classified as:

— fixed and agreed with the supply agency;

— fixed, but not agreed with the supply agency; or

— random or variable.

Each type of sampling site has certain advantages and disadvantages. Fixed sites agreed with the supplier are essential when legal action is to be used as a

Isokinetic Sampling Probes for Steam Applications

EPRI Isokinetic Sampling Nozzles (Probes)

Ideal for saturated steam, superheated steam, and water sampling in steam and power plants.  

These nozzles meet the requirements of ASTM Standards D1066 and D3370.


The nozzles extract a representative isokinetic sample from a flow region removed from the pipe surface and at the average flow velocity of the sample fluid.  
This arrangement results in the withdrawal of the sample with representative concentrations of dissolved, suspended, and volatile constituents.

 

An appropriate nozzle (probe) is designed for the desired sample flow and typical conditions of the sample fluid.  When the flow velocity through the pipe changes, sample flow should be adjusted to maintain isokinetic sampling.

 

Each Nozzle (probe) is designed with considerations of vortex shedding, resonance, vibration, erosion, and strength of the attachment to the pipe.