Super Heated Wash Water | SHWW | system for centrifugal machines

Super Heated Wash Water requirement for centrifugal machines with calculator

Sugar washing :

Washing in a centrifugal is designed to remove the high color molasses layer adhering to crystal surface.

This is an important part of the cycle and needs careful attention to detail if the required sugar quality is to be achieved without excessive dissolution of sugar. The sprays must be set up to spread the water uniformly across the height of the inside of the sugar layer.

In Water washing, the water is applied in fine spray on the surface of sugar. The water washes the molasses film and removes it and at the same time it unavoidably dissolves small amount of sugar.

The sprays are set up in an empty basket, and allowance must be made for the thickness of the cake in setting the sprays.

To avoid harmful effects of purity drop, the amount of washing has to be kept minimum. It is theoretically given that wash water is to applied when 75 % of molasses has been eliminated.

Super heated wash water (SHWW):

super heated wash water (SHWW) system for batch centrifugal machines - sugarprocesstech

For better washing and get good quality sugar, super heated wash water is used for washing. In case of self-discharge batch type centrifugal, both water and steam is adopted. The super heated wash water system heat the hot condensate water to 115 ± 5 oC  by steam. .  The supply of water to pump suction is from overhead condensate tank. And temperature is about 70-80oC.   Water under pressure 5 to 6kg/cm2 heated up to 115 – 120oC is known as super heated water.

The steam required to get the temperature should be applied at pressure of 7 kg/cm2 & 160oC – 180oC . The inlet hot water is supplied to suction side of pump.  The delivery side of pump is connected to inlet tube side of heater  the outlet  of heater is connected to main header of super heated wash water system running behind C/F machines the other end of main pipe should be constantly leaked out to hot water tanks or drain by means of spring loaded valves.

In present scenario for reducing steam consumption, few sugar mills are now using system Plate Type heat exchanger for heating the super heated wash water (SHWW). Here 2nd body condensate heated by exhaust steam.

Gravity factor of Centrifugal machine has significant effect on washing water requirement.  High G.F. of machine will require less water and vice versa

Quantity of water & steam to the sugar washing :

As per Noel Deer values are

Water required for washing 10 % on weight of sugar or . 5 % on massecuite.

Steam required for washing 20 % on weight of sugar or . 10 % on massecuite.

But practically  SHWW only  is sufficient for washing  maximum 4 – 5% on sugar or 2 –2.5% on massecuite

SHWW requirement can be calculate in three ways:

While considering of Crushing Rate :

Data requirement (For better understanding purpose go through the some values in example)

  • Crushing rate  230TCH
  • A m/c % on cane = 30
  • A m/c quantity  per hour = Crushing rate x m/c %cane = 69 T/hr
  • SHWW quantity  on m/c = 5% on m/c (taken maximum value)
  • Water inlet temperature = 85oC
  • SHWW temperature requirement=  120 oC
  • Heating media Temperature (Exhaust) =     125 oC (here consider PHE system and heating media is exhaust)

Calculation

  • Heating media latent heat = 522.5 Kcal/Kg (At 125oC)
  • SHWW requirement   =       3.45    kg/ hr
  • Take 100% extra  =  6.9       T/hr (To overcome the stoppages)
  • Steam requirement  for SHWW system= SHWW requirement (Kg/hr) x ( Water O/L temp. – Water I/L temp.)/ Latent heat. = 0.46  T/hr
  • Steam % Cane for SHWW system = Steam requirement  for SHWW system x 100 / TCH = 0.20
While considering of centrifugal machines:

Data requirement

  • Machine Capacity = 1750  kg/charge
  • Water quantity on m/c = 5   % on m/c (taken maximum value)
  • No. of cycles per hour = 22
  • No. of machines = 3
  • Water inlet temperature =   85oC
  • SHWW temperature requirement  = 120  oC
  •  Heating media Temp. (Exhaust) = 125 oC
  • Heating media Latent heat= 522.5  Kcal/Kg

Calculation

  • SHWW required per machine = Machine Capacity x Water quantity on m/c x No. of cycles per hour = 1925   kg/ hr
  • Total SHWW required for all machines =  SHWW required per machine  x No. of machines =   5775   kg/hr
  • Take 50% extra due to re circulation =  8.6625    T/hr
  • Steam requirement = 0.58    T/hr
While considering of centrifugal machines nozzle data

Here we can calculate requirement of SHWW can estimate  by the  No. of nozzles and its capacity per each machine,

Timing requirement for nozzle operation   ( Basket wash  + 1st wash + 2nd wash …..etc)

Now  we can calculate SHWW quantity requirement per cycle than easily find the total SHWW requirement.

To find the batch centrifugal machine capacity please go through the link

Batch Centrifugal Machine Capacity and Gravity Factor Calculation

 

Related Articles:

Rillieux’s principles and pressure drops calculation for Multiple Effect Evaporator bodies like Quadruple& Quintuple effect with online calculator.

Formulas for calculating steam Percent cane and heating surface of the individual evaporator bodies in multiple effect evaporator with powerful online calculator.

The purpose of this article is to evaluate the batch centrifugal machine capacity and its gravity factor by online calculator.

Concepts of NPSH calculation,NPSHa,NPSHr formulas, Pump cavitation , Pump suction and delivery lines head loss with online calculation.

Condensate or Duplex Heater (Liquid- Liquid Heater) heating surface, number of tubes, tube plate dia, pressure drop calculation formulas with online calculation sheet.

 

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Post Author: siva alluri

The aim of this Blog "sugarprocesstech" is Providing basic to advance knowledge in sugar process industry and providing maximum calculation regarding capacity and equipment design online calculators .

10 thoughts on “Super Heated Wash Water | SHWW | system for centrifugal machines

    Mahesh HOLDE

    (May 17, 2017 - 10:19 am)

    PL send such type of calculation relate to sugar industry

      siva alluri

      (May 17, 2017 - 11:40 am)

      Thank You Mr.Mahesh
      The sugarprocesstech website will cover maximum calculation part related to sugar industry one by one.
      The “www.sugarprocesstech.com” invites to all sugar technologists to share your knowledge, achievements in your working organization and new developments and technologies in sugar industry and its concerned units. It is very much helpful to show his identity to the world at the same time it will helpful to another technologist to enhance their insight and enhance great execution in there working.
      Contact mail id for submission of articles : sugarprocesstech@gmail.com

    Nk Jain

    (July 31, 2017 - 6:30 am)

    Dear sir,
    Above calculation is correct from he point of view of crushing Capacity & machine size but we have to see max discharge of water required from nozzles during 1st & 2nd wash that will be around 5 litres/sec. hence 18000 lit/hr capacity pump is required irrespective of very less water quantity per hour basis.

      siva alluri

      (July 31, 2017 - 1:36 pm)

      Thank sir for your valuable comment
      Sir according your condition around 5 lt/sec. So take 1st wash + 2nd wash duration approx. 30sec and cylcles per hour take around 20 than
      SHWW requirement = 30 x 20 x 5 = 3000lt/sec ( Do not take 3600sec )

    Akhilesh Dhar Diwedi

    (October 18, 2017 - 4:41 am)

    Dear Mr. Siva,
    SHWW reqirement at batch centrifugals varies for Raw Sugar, Sulphitation Sugar and Refined Sugar. It is good to have approximation of 7.25 % for raw sugar ,5% for PWS and 2-3.5% for refined sugar(% on Ma/c Base) for desining pupose..Along with the temp of SHWW- around 110-115 Deg C, the pressure is also an important factor. Traditionally it is in the range of 4-5 Kg/Cm2 but for water consumption point of view It is more use full in the range of 8-9 Kg/Cm2. At this pressure and temp. SHWW gives better results in terms of low volume of molasses.The rpm of 1st and 2nd wash application is also an important factor.
    In lieu of the above the SHWW ( for running plant) can be calculated by mass balance method –
    Thanks..
    Akhilesh Dhar Diwedi

      siva alluri

      (October 19, 2017 - 12:05 pm)

      Mr.Akhilesh Dhar Diwedi.
      Thank you very much for the sharing your knowledge. So we request to all technologist to share your knowledge and experience.

    B. N Amarendra

    (March 31, 2018 - 2:28 pm)

    hai really it is good. thanks a lot

    Srinath

    (July 13, 2018 - 9:48 am)

    Sir,
    Could you please tell me the velocity and viscosity of the SH wash water and PHE Exhaust steam inlet

      siva alluri

      (July 15, 2018 - 1:40 pm)

      The velocity of SH wash water is 2.0 to 2.2 m/sec
      Exhaust velocity consider 25 m/sec
      Viscosity for SHWW is negligible

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