Condensers Aqueouos vapours Water 1000 - 1500 Organic vapours Water 700 - 1000 Refinery hydrocarbons Water 400 - 550 Vapours with some non condensibles Water 500 - 700 Vacuum condensers Water 200 - 500
COOLING WATER - Fouling Factors in [m2K/W] Conditions cooling water < 50 ° C cooled fluid < 120 ° C cooling water > 50 ° C cooled fluid > 120 ° C Water velocity v < 1 m/s v > 1 m/s v < 1 m/s v > 1 m/s
Type of Water Sea 0.00009 0.00009 0.00018 0.00018 Brackish 0.00035 0.00018 0.00053 0.00035 Cooling tower with inhibitor 0.00018 0.00018 0.00035 0.00035 Cooling tower without inhibitor 0.00053 0.00053 0.00088 0.00070 City grid 0.00018 0.00018 0.00035 0.00035 River mimimum 0.00018 0.00018 0.00035 0.00035 River average 0.00053 0.00035 0.00070 0.00035 Engine jacket 0.00018 0.00018 0.00018 0.00018 Demineralized or distilled 0.00009 0.00009 0.00009 0.00009 Treated Boiler Feedwater 0.00018 0.00009 0.00018 0.00018 Boiler blowdown 0.00035 0.00035 0.00035 0.00035
SEVERAL FLUIDS - Fouling Factors in [m2K/W] Group Fluid Fouling Factor Oil Gasoil 0.00009 Transformer 0.00018 Lubrication 0.00018 Heat Transfer oil 0.00018 Hydraulic 0.00018
Gas and Vapour Hydrogen 0.00176 Engine exhaust 0.00176 Steam 0.00009 Steam with oiltraces 0.00018 Cooling fluid vapours with oil traces 0.00035 Organic solvent vapours 0.00018 Compressed air 0.00035 Natural gas 0.00018 Stable top products 0.00018
Liquid Cooling Fluid 0.00018 Organic heat transfer fluids 0.00018 Salts 0.00009 LPG, LNG 0.00018 MEA and DEA (Amines) solutions 0.00035 DEG and TEG (Glycols) solutions 0.00035 Stable side products 0.00018 Stable bottom products 0.00018 Caustics 0.00035 Vegetable Oils 0.00053
REFINERY FLUIDS - Fouling Factors in [m2K/W] Crude - wet, (bearing salty water) Temperature 0 to 95 ° C 95 to 160 ° C 160 to 260 ° C > 95 ° C Velocity < 0.6 m/s 0.00053 0.00088 0.00105 0.00123 0.6 m/s to 1.2 m/s 0.00035 0.00070 0.00088 0.00106 > 1.2 m/s 0.00035 0.00070 0.00070 0.00088
Crude - dry Temperature 0 to 95 ° C 95 to 160 ° C 160 to 260 ° C > 95 ° C Velocity < 0.6 m/s 0.00053 0.00053 0.00070 0.00088 0.6 m/s to 1.2 m/s 0.00035 0.00035 0.00053 0.00070 > 1.2 m/s 0.00035 0.00035 0.00035 0.00053
Products Gasoline 0.00018 Naphtha and Light Distillates 0.00018 Kerosene 0.00018 Light gas oil 0.00035 Heavy gas oil 0.00053 Heavy fuel oils 0.00088 Asphalt and residuum 0.00176
Cracking and Coking Units streams Overhead vapors 0.00035 Light cycle oil 0.00035 Heavy cycle oil 0.00053 Light coker gas oil 0.00053 Heavy coker gas oil 0.00070 Bottom slurry (> 1.5 m/s) 0.00053 Bottom liquid products 0.00035
Catalytic Reforming, Hydrocracking, Hydrodesulfurization (HDS) Reformer charge 0.00035 Reformer effluent 0.00018 Hydrocracker charge and effluent 0.00035 Recycle gas 0.00018 HDS charge and effluent 0.00035 Overhead vapors 0.00018 Liquid product > 50 API 0.00018 Liquid product 30 to 50 API 0.00035
FLUID ALLOCATION: CHOICE BETWEEN SHELL OR TUBE SIDE
Introduction The choice of the allocation of the fluid to the shell side or tube side can have a significant impact on the performance, economics and maintainability of a heat exchanger. For most design work a balanced decision is required as the considerations can lead to opposite preferences. Some general guidelines are provided underneath:
Fouling There are many mechanisms of fouling. Allocating the most fouling fluid to the tube side will be more favourable as mechanical cleaning of the inside of the tubes wil be much easier. As the allowable velocity in the tubes is usually higher than at the shell side and a high fluid velocity causes attrition of the deposits, it is possible to reduce fouling by design.
Mechanical Design Pressure It will be more econamical to put the medium with the highest maximum allowable working pressure at the tube side. If the shell side needs to be designed for a high pressure the wall thickness will increase making the heat exchanger more expensive.
Corrosion If you need an expensive corrosion resistant material it will be more economical to place the corrosive fluid in the tubes as this will reduce the costs of the shell material or cladding.
High Viscosity or Low Flowrates To obtain an economic design high heat transfer coefficients are required. As heat transfer coefficients are much higher for turbulent flow this is the most important aspect to look into. For a highly viscous medium or a low flowrate turbulent flow can be obtained easier at the shell side. If the Reynolds number at the shell side is below 200, however, it will probably be cheaper to allocate this fluid to the tube side and use a high number of tube passes. Use the thermal rating calculation routine to do trial and error runs and get an economical design.
Heat Exchanger Calc.: Typical ...
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2005/02/07 01:28am 
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