Robert Type Evaporator Design Calculation Sheet    
  INPUT DATA to be give in  Yellow colour cells  
  Heating surface m2 Inlet vapour temperature oC  
  Tube OD mm outlet vapour temperature oC  
  Tube thickness mm Velocity of inlet vapour m/sec  
  Tube Length mm velocity of outlet vapour m/sec  
  Tube plate thickness mm Velocity of condensate m/sec  
  Tube expansion allowance mm Evaporation rate of the body Kgs/m2 /hr  
  Legment
Author:
Generally Legment taken for Juice heater12mm, evaporators 10mm and for Pan 16mm
 mm Inlet vapour specific volume M3/kg  
  Tube clearance mm outlet vapour specific volume m3/kg  
  Tube plate hole clearance mm  
  proportional factor(β)
Author:
Generally β value take for multiple pass 0.6 to 0.8 and for single pass 0.8 to 1.0
    
  Percentage of downtake Dia on tube plate area of tubes
Author:
According to peiter rein down take dia consider less than 25% of the tube plate dia (p.no. 297)
According to Hugot The diameter of the centre well varies from ¼ to ⅛ of the interior diameter of the vessel. ( pg. no. 509)
 %  
S.No Description UOM Value Formula  
1 Number of tubes  
  Mean dia of the tube ( Dm) mtr Tube OD- Tube Thickness  
  Effective Length of the tube ( L ) m Tube lg - 2(Tube plate thk)-2(Tube expansion allowance)  
  No. of tubes no.s Heating Surface = π D L N  
2 Tube plate & Downtake dia  
a Area occupied for tube plate  
  Tube Pitch (P ) mtr OD+legment+tube clearance+hole clearance  
  Taken extra dia for stay roads arrangement or multiple down take arrangement %    
  Tube plate area required for tubes only m2 (0.866 x P2 x N /β)  x %extra  
  Tube plate Dia required for tubes only mtrs SQRT ( A x 4/π )  
    mm  
b Dia of the single down take  
  Dia of the down take mm Tube plate dia for tubes x % of downtake on tube plate  
  Area of the downtake m2 π r2  
  Total area of the tube plate m2 Area of the Tube plate for tubes + Downtake area  
c Final Dia of the tube plate mtr SQRT ( A x 4/π )  
    mm  
d Dia of the  multiple down takes      
  Consider each peripheral down take dia mm  
  Consider number of peripheral down takes no.s  
  Total area of peripheral down takes mm2 π r2 x  number of peripheral down takes (r = radious of each peripheral down take  
  Available area for central down take mm2 Area of the single downtake - Total area of peripheral down takes   
  Dia of the central down take mm SQRT ( A x 4/π )  
3 Dia required for vapour inlet  and Dia of the Calendria in radial steam/ vapour entry  
  Number of steam/ vapour entries no.s
Author:
If the sibgle entry than take value = 1
  
  Evaporation rate of the body Kgs/m2 /hr  
  Vapour required for calendria Kgs/hr Heating surface x Evap. Rate  
    m3/sec Multiptiplyed by specific volume of vapour  
  Total area for vapour entry ( A ) m2  A = Q/ V  
a Dia of the each steam entry mm SQRT [ (A / Number of steam/ vapour entries)  x (4/π ) ]  
  Say mm  
b Calendria dia at the entry of the steam/vapour jocket       
  Area of each steam entry mm2 π r2  
  Height of the steam entry mm Take Effective Length of the tube  
  Width of the steam entry mm A = L x W  
c Dia of calendria at the point of radial steam entry  mm It is to be maintained at the vapour entry side  later it may reduced in vapour travel direction.  
4 Vapour outlet pipe dia      
  Vapour volume m3/sec Heating surface X Evap. Rate x Specific volume of vapour/3600  
  Vapour outlet pipe dia mtr SQRT [vapour vol./(0.785 x velocity of vapour)]  
  Say mm  
5 Dia of the condensate line        
  Volume of the condensate kgs/hr Heating surface X Evap. Rate  
    m3/sec Here considered density of water as 1 and also consider 10% extra for free removal of condensate  
  No. of condensate withdrawals no.s  
  Condensate pipe dia each mtr SQRT (vapour vol./(0.785 x velocity of condensate))  
    mm  
6 Noxious gases         
  Cross section area of non condensable gases cm2    
  No. of NCG withdrawal points          
  Dia of the each non condensable gases line cm SQRT( 4*area./3.14*no. of points)  
  Say mm    
   
7 Vapour space height Take 
Author:
Generally for Robert type bodies taken for lost effect 2.5 times on calendria tube height and for remaining bodies take 2 tmes on Calendria tube height
 Generally for Robert type bodies taken for lost effect 2.5 times on calendria tube height  and for remaining bodies take 2 tmes on Calendria tube height  
    mm  
8 Velocity in vapour space of body (Cross checking of the system )  
  Vapour volume m3/sec Heating surface X Evap. Rate  
  Crossectional area of the body m2  
  Velocity in vapour space of body m/sec
Author:
vapour velocities in the vessels maximum reach 3.6m/sec and for lost body reach maximum 4.6 m/sec . And If more than 6m/sec than entrainment chance is more.
 The velocity of vapour leaving the liquid surface would then be approximately 10 cm/sec  
    Ft/sec  
9 Calendria shell thickness   (P*  Di / (2*F*J - P) ) + C    
  P = Maximum allowable pressure  kg/cm2  
  Di = ID of the Calendria mm  
  F = Allowable stress kg/cm2  
  J = Joint efficiency    
  C= corrosion allowance mm  
  Calendria shell thickness mm  
  Say mm  
10 Vapour shell thickness   (P*  Di / (2*F*J - P) ) + C  
  P = Maximum allowable pressure  kg/cm2  
  F = Allowable stress kg/cm2  
  J = Joint efficiency    
  C= corrosion allowance mm  
  Di = ID of the Calendria mm OD - 2 x Calendria shell thickness  
  Vapour shell thickness mm  
  Say mm  
11 Tube plate thickness   
  C= corrosion allowance mm  
  F = Allowable stress kg/cm2      
  P = Maximum allowable pressure  kg/cm2  
  Es = Modulus factor for MS sheet kg/cm2  
  Et = Modulus factor for SS sheet kg/cm2  
  G = ID of the shell mm OD - 2 x Calendria shell thickness  
  tts = Thickness of the shell mm  
  tt = Thickness of tube mm  
  do= OD of the tube mm  
  Do = OD of the calendria sheet mm  
  Nt = Number of tubes no.s  
  K   K =( Es x ts x (Do -ts)) /(Nt x Et x tt x(do -tt))  
  f = safety factor   f = SQRT ( K / (2 + 3K))  
  Tube plate thickness  mm f x G x SQRT((0.25 x P)/F) + C  
12 Vapour doom dia On vapour outlet line area
Author:
Generally for Robert type bodies vapour doom dia taken 2 to 2.5 times for vapour outlet pipe area
 Generally for Robert type bodies vapour doom dia taken 2 to 2.5 times for vapour outlet pipe area  
  Cross sectional area of the vapour doom mm2  
  Vapour doom dia    
  Say mm  
  Top cone angle (φ) Deg  
  Top cone height   Tan φ( (ID of body  -ID of doom)/2)  
13 Center Umbrella area  
a Case 1 (cross sectional Area  of the body - cross sectional area of the doom = area of Umbrella mm      
 
Author:
In some designs consider 60 to 65% on body dia
Case 2 (While considering 65% on body dia)
mm Here Case 2 considered  
  Gap between Umbrella to top cone at entry H mm π * Dia of Umbrella* H = Area of vapour doom  
  Gap between Umbrella to top cone at exist H mm π * ID of doom* H = Area of vapour doom    
 
Robert Type Evaporator Design Calculation Sheet    
  INPUT DATA to be give in  Yellow colour cells  
  Heating surface m2 Inlet vapour temperature oC  
  Tube OD mm outlet vapour temperature oC  
  Tube thickness mm Velocity of inlet vapour m/sec  
  Tube Length mm velocity of outlet vapour m/sec  
  Tube plate thickness mm Velocity of condensate m/sec  
  Tube expansion allowance mm Evaporation rate of the body Kgs/m2 /hr  
  Legment
Author:
Generally Legment taken for Juice heater12mm, evaporators 10mm and for Pan 16mm
 mm Inlet vapour specific volume M3/kg  
  Tube clearance mm outlet vapour specific volume m3/kg  
  Tube plate hole clearance mm  
  proportional factor(β)
Author:
Generally β value take for multiple pass 0.6 to 0.8 and for single pass 0.8 to 1.0
    
  Percentage of downtake Dia on tube plate area of tubes
Author:
According to peiter rein down take dia consider less than 25% of the tube plate dia (p.no. 297)
According to Hugot The diameter of the centre well varies from ¼ to ⅛ of the interior diameter of the vessel. ( pg. no. 509)
 %  
S.No Description UOM Value    
1 Number of tubes    
2 Tube plate & Downtake dia        
a Area occupied for tube plate        
  Taken extra dia for stay roads arrangement or multiple down take arrangement %    
  Tube plate Dia required for tubes only mm    
b Dia of the single down take mm  
  Final Dia of the tube plate mm    
d Dia of the  multiple down takes        
  Consider each peripheral down take dia mm    
  Consider number of peripheral down takes no.s    
  Dia of the central down take mm  
3 Dia required for vapour inlet  and Dia of the Calendria in radial steam/ vapour entry  
  Number of steam/ vapour entries no.s
Author:
If the sibgle entry than take value = 1
  
a Dia of the each steam entry mm  
  Say mm    
b Calendria dia at the entry of the steam/vapour jocket     
  Dia of calendria at the point of radial steam entry  mm  
4 Vapour outlet pipe dia      
  Vapour outlet pipe dia mtr  
  Say mm  
5 Dia of the condensate line        
  No. of condensate withdrawals no.s    
  Condensate pipe dia each mtr    
    mm  
6 Noxious gases   
  No. of NCG withdrawal points    
  Dia of the each non condensable gases line cm    
  Say      
7 Vapour space height Take 
Author:
Generally for Robert type bodies taken for lost effect 2.5 times on calendria tube height and for remaining bodies take 2 tmes on Calendria tube height
  
    mm    
8 Velocity in vapour space of body (Cross checking of the system )      
  Velocity in vapour space of body m/sec
Author:
vapour velocities in the vessels maximum reach 3.6m/sec and for lost body reach maximum 4.6 m/sec . And If more than 6m/sec than entrainment chance is more.
  
    Ft/sec      
9 Calendria shell thickness  
  P = Maximum allowable pressure  kg/cm2    
  F = Allowable stress kg/cm2  
  J = Joint efficiency    
  C= corrosion allowance mm  
  Calendria shell thickness mm  
  Say mm  
10 Vapour shell thickness  
  P = Maximum allowable pressure  kg/cm2  
  F = Allowable stress kg/cm2      
  J = Joint efficiency    
  C= corrosion allowance mm  
  Vapour shell thickness mm  
  Say mm  
11 Tube plate thickness         
  C= corrosion allowance mm    
  F = Allowable stress kg/cm2  
  P = Maximum allowable pressure  kg/cm2  
  Es = Modulus factor for MS sheet kg/cm2  
  Et = Modulus factor for SS sheet kg/cm2      
  Tube plate thickness  mm  
12 Vapour doom dia On vapour outlet line area
Author:
Generally for Robert type bodies vapour doom dia taken 2 to 2.5 times for vapour outlet pipe area
  
  Vapour doom dia    
  Say mm    
  Top cone angle (φ) Deg  
  Top cone height    
13 Center Umbrella area  
a Case 1 (cross sectional Area  of the body - cross sectional area of the doom = area of Umbrella mm  
 
Author:
In some designs consider 60 to 65% on body dia
Case 2 (While considering 65% on body dia)
mm  
  Gap between Umbrella to top cone at entry H mm    
  Gap between Umbrella to top cone at exist H mm