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CHAPTER 3: STEAM DISTRIBUTION & UTILIZATION, Types of steam trap…

- - - - 1) Efficient & economic to generate.
      - 2) Easy to distribute.
      - 3) Easy to control.
      - 4) Easily to transferred to the process.
      - 5) Steam plant is easy to manage.
      - 6) Flexible.
- - - - Material:
        
        Carbon steel / copper
      - Pipeline sizing:
        
        Correct pipeline sizing is important.
        
        Can be calculated based on pressure drop/velocity
        
        Oversized pipework
        
        Higher material and installation costs.
        
        Increased condensate formation.
        
        Undersized pipework
        
        Lower pressure at point of use.
        
        Risk of steam starvation.
        
        Risk of erosion.
      - Piping layout
        
        Steam mains should be installed with a fall of not less than 1:100
    - - Ensures that condensate can reach steam trap.
      - Consideration must be given to:
        
        Distance between drain points.
        
        Design of drain points.
        
        Condensate in steam main at shutdown.
        
        Diameter of drain pipe.
        
        Location of drain points.
    - - Take steam away from main steam
      - Shorter than main steam
      - Branch line connections taken from the top of the main line. If connection are taken from the side & bottom, they can accept the condensate & debris from the main.
    - - Stop scale, dirt & other solids in flowing liquids / gases.
      - Protect equipment from their harmful effects, thus reducing maintenance.
      - Types of strainers:
        
        1) Y-type
        
        Almost universally used.
        
        Can handle high pressure.
        
        Have lower dirt holding capacity: required more frequent cleaning.
        
        2) Basket type Strainer
        
        Less pressure drop.
        
        Preferred type of liquid application.
        
        Larger dirt holding capacity.
        
        Only for horizontal pipelines.
        
        When used on steam system, drain plug is needed to remove condensate.
        
        Commonly found in duplex arrangement (parallel position)
      - Types of Screens:
        
        1) Perforated Screen
        
        Holes punched in flat screen
        
        Large holes ( 0.8mm - 3.2mm
        
        Remove large debris
        
        2) Mesh Screen
        
        Fine wire into mesh arrangement
        
        Small holes (~0.07mm)
        
        Remove small debris
    - - To remove smaller particles.
      - Used in application:
        
        Dirty steam can cause rejection of the product
        
        Minimal particle emission required from steam humidifiers
        
        Direct injection of steam into a process
    - - Remove suspended water droplets from steam
      - Water in steam can cause a number of problems:
        
        Reduce plant productivity & product quality
        
        Erosion & corrosion of valve & fittings
        
        Scaling of pipework & heating surfaces from impurities
        
        Erratic operation & failure of valve & flow meters
      - Types of separators:
        
        1) Baffle Type
        
        2) Cyclonic Type
        
        3) Coalescence Type
    - - Function: "Purges" condensate out of the steam system & allows steam to reach destination as dry as possible.
      - Type of steam traps:
        
        1) Thermostatic Steam Traps
        
        2) Mechanical Steam Traps.
        
        3) Thermodynamics Steam Traps
    - - Function: To remove air from the steam
      - Types of air vents:
        
        1) Automatic air vent on jacketed pan (vessel)
        
        2) Automatic air vent on end of main.
      - The presence of air in the steam reduces the temperature of the steam & offers a resistance to heat transfer
      - Air vent location:
        
        Within low lying steam trap opposite high level steam inlet.
        
        Opposite low level steam inlet
        
        Opposite end of steam inlet
    - - What is condensate?
        
        Distilled water with heat content
        
        Discharged from steam plant and equipment through steam traps
      - Condensate recovery for?
        
        Reuse in boiler feed tank. deaerator/ as hot process water
        
        Heat recovery through heat exchanger
      - Reason for condensate recovery
        
        Water changes
        
        Maximizing boiler output
        
        Effluent restrictions
        
        Boiler feedwater quality
        
        Financial reason
    - - Insulator: Low thermal conductor that keeps heat confined within/ outside a system by preventing heat transfer to/from the external environment
      - Benefits:
        
        Reduction of fuel consumption
        
        Better process control
        
        Corrosion prevention
        
        Fire protection of equipment
        
        Absorbing of vibration
      - Suitable materials for steam & condensate line:
        
        2) Glass wool
        
        3) Rock wool
        
        1) Cork
        
        4) Asbestos