Steam Flow Measurement

1
Steam Flow Measurement

• By-
• D K Singhal

2
Disclaimer

• This presentation is supplied as a self learning
  presentation, and is subjected to the condition
  that the author accepts no liability from the use
  of the same or from the techniques or information
  provided within the same.
• It is strongly recommended to consult your
  mechanical engineer, process engineer and other
  technical experts, before making any changes to
  the existing system.

3
Preface

• Steam consumption is one of the significant cost
  factors in paper and other process industries. In
  absence of any steam flow metering control and
  optimization of steam consumption is not
  possible.

4
Available Systems

• Steam flow measurement systems available in the
  market are very costly, and hence most of the
  mills cannot afford them to install. But, nothing
  can be controlled if it is not being monitored.

5
Proposed System

• This must be indicated that the proposed system
  is of very low cost. In the proposed system,
  reading is taken from the instrument and with the
  help of calibration chart, steam flow is
  estimated. Accuracy may be a little lower, but
  benefits obtained by the proposed system may even
  encourage the user to purchase and install steam
  flow meter from a reputed supplier.

6
Concept

• Pressure Drop across a saturated steam pipeline
  is a function of steam flow rate, steam pressure
  (and hence specific volume) and pipe diameter.
• For most of the cases, steam pressure is normally
  kept constant, or varies within narrow limits.
  Pipe diameter, of course, is fixed for a
  particular position.

7
Steam Flow

• The proposed system works on the basis of
  pressure drop in a horizontal steam pipeline,
  which is proportionate to square of steam flow
  rate. i.e. for any flow rate say pressure
  difference is 100mmWC, a 10 reduction in steam
  flow will be indicated by a reduction in pressure
  drop to 79mmWC. Thus, one can very easily achieve
  the optimum steam consumption for a particular
  application.

8
Schematic Drawing

• 
  Distance for which dP is to be
  measured

Steam Flow
Pressure Gauge
Gauge Glass Assly.
Closed Tank
Zero Level
Baffle Plate
Steam Trap
T
9
About the Equipment

• As indicated in figure, the tank has a partition
  in the center. The lower chamber is filled with
  water upto zero level prior to installation. Any
  further water coming into the tank is drained
  from the excess water removal line through valve
  and steam trap installed, as indicated in the
  left side of figure.

10
Operation

• Initially, the lower chamber is filled with
  water. When the system is connected to steam
  line, steam from upstream side fills lower
  chamber and exerts a pressure inside gauge glass.
  The downstream side steam pressure fills upper
  chamber and tries to counterbalance the upstream
  pressure. The pressure drop is indicated in the
  gauge glass.

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Initial Measurements

• Distance between the two points at which the unit
  is connected is measured. Steam pipe diameter is
  also measured. The line pressure can be measured
  by the pressure gauge mounted on the unit, as
  indicated in schematic.
• Gauge glass initial level is marked when there is
  no steam flow. Any increase in gauge glass level,
  thus, can be measured.
• Also, the pressure can be measured by the
  pressure gauge mounted on the unit.

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Flow Estimation

• The steam flow will be proportional to the square
  root of gauge glass level increase, and inversely
  proportional to the steam pressure as indicated
  by the pressure gauge.
• Formulae are available to calculate pressure drop
  in the pipeline, and depending on the distance
  between two points in the steam line, working
  pressure, pipe diameter etc., it is possible to
  develop a plant specific correlation.

13
Flow Optimization

• To optimize the steam flow, just measure gauge
  glass level increase at a particular operating
  condition and pressure.
• After altering process variables, if the gauge
  glass reading decreases, it will clearly indicate
  that the steam flow has reduced.

14
Feedback

• Please send in your comments on this presentation
  to-
• D K Singhal
• Deveshksinghal_at_rediffmail.com
• Deveshksinghal_at_gmail.com
• Thank You.