Ei dian otsikkoa

1
NELFLOW - a valve as a flowmeter
Capacity curve
ND800 Nelflow
FLOW 4 - 20 mA
pot.
P1 ,T1
P2
Flow
2
NELFLOW - a valve as a flowmeter

• Product concept
• any Neles Controls valve or actuator
• ND800 as a basic unit
• pressure differential based measurement
• configuration via Valve Manager for Nelflow
  -software utilizing HART

3
NELFLOW - Pressure differential based measurement

• upstream and downstream pressure transmitters
• or differential pressure transmitter
• 2-wire, 420 mA transmitters
• diaphragm type, WIKA 891.13.520 from Neles
  Controls
• three alternatives to mount transmitters
• transmitter flanges
• pipeline
• constant pressure, configuration by software

4
NELFLOW - Electronics

• own printed circuit board for valve controller
• own printed circuit board for flow transmitter
  isolated current circuits
• valve controller powered from control signal
• flow transmitter powered from flow output signal
• isolated from each others
• Nelflow capability cannot be installed to
  existing ND800, you must change the ND800 to
  NDQ800

5
NELFLOW - Transmitters

• four input channels in flow transmitter PCB
• possibility for four transmitters
• 2pressures, temperature and consistency
• each transmitter require own power supply
• 420 mA transmitters from any supplier
• isolated from other circuits

6
NELFLOW - Electrical connections
Supply 24 V
Measurement transmitters
4 - 20 mA (corresponds max. load 350 W)
NDQ800
p1
4 - 20 mA HART (13.2 V _at_ 20 mA )
Flow
p2 or Dp
ND800
temperature (for steam or gas)
consistency for pulp stocks
Positiontransmitter 4 - 20 mA
Flowtransmitter 4 - 20 mA
Energy for circuit boards
7
NELFLOW - Flow calculation

• flow calculated at flow transmitter circuit board
• using actual Cv and dp
• standard equations for control valves (IEC 60534)
• liquids, pulp, gases, steam
• fluid properties configured by Valve Manager for
  Nelflow
• steam density calculation using actual p1 and T1
• choked flow, cavitation and flashing compensation
• pulp stock consistency compensation

8
NELFLOW - Performance

• repeatability of flow measurement
• 0.5
• error in flow measurement
• 2.5 of reading for calibrated unit, flow
  velocity gt 0.5 m/s

9
NELFLOW - Valve Manager for Nelflow (HART5)

• data transmission based on HART
• configuration (medium, channel settings,
  transmitter location)
• valve selection and Cv-curve
• calibration
• monitoring (flow, pressures)
• other features all the same functionality as
  with Valve Manager for HART Modems HART1
• limited version for configuration HART6

10
NELFLOW - All in one

• fast and accurate control valve
• control valve diagnostics
• flow meter
• control valve needed anyway
• Benefit Ease of purchasing and responsibilities

11
NELFLOW - Wide applicability

• wide range of different fluids
• wide measurement rangeability
• wide range of nominal sizes
• wide range of materials, pressures, temperatures
• if flow is controlled by a valve then its
  measurable
• Benefit Ease of selection and interchangeability

12
NELFLOW - Pressure differential based measurement

• immune to electrical conductivity
• immune to air content
• immune to fiber suspensions or particles
• immune to fluid getting stuck
• immune to installation misalignment
• Benefit Reliable and robust flow measurement

13
NELFLOW - Cost effecient solution

• low initial costs
• low installation costs, valve installed anyway
• low operation costs, no extra pressure loss
• low maintenance costs, valve maintained anyway
• Benefit Low cost of ownership

14
NELFLOW - Need to add flow measurement afterwards

• simply change positioner and add pressure
  transmitter
• piping changes not necessary
• fits to existing valves
• Benefit Ease of retrofit

15
Flow measurement error in field
conditions (Oriface plates, Venturi tubes,
Magnetic and Ultrasonic flowmeters)
16
Application comparison
17
Flowmeter selection guide