Bitumen Heating

August 2, 2019



In today’s oil industry, there a fewer and fewer new finds of light crude petroleum. New sources, whether they be from the Canada tar sands, from shale oil or from offshore drilling for example, are often heavy oil, bitumen and asphalt. The two latter terms, sometimes used interchangeably, refer to long hydrocarbon chain molecules of very high viscosity.

Figure 1 – Bitumen flow by gravity is very sluggish in cold weather
Because of the growing importance of heavy oil, bitumen and asphalt, new techniques must be applied to process them. A basic challenge is to make them flow: from the reservoir to the refinery; from one station of the refinery to the next; from a depot tank to a truck or a railway car, among other situations.


Figure 2 – Effect of temperature on the viscosity of gas-free Athabasca (ARC) bitumen at constant pressure [1]
The extremely high viscosity shown for Athabasca bitumen in Figure 2 is typical of all bitumen – for reference, the viscosity of water is 8.9 x 10-4 Pa-s. Also typical is the observed tendency of the viscosity to decrease exponentially with temperature.
In this article, we demonstrate quantitatively the importance of heating heavy oil products before pumping. For convenience, we will simply use the term bitumen to designate all the heavy oil products described above.



The power P required to pump bitumen at a flow rate Q across a pipe in which the pressure drop is Δp is given by:
The pressure drop in turn, is proportional to the friction factor f, the ratio of pipe length l to diameter d, and the dynamic pressure ρV2/2, where ρ is the density and V the velocity:
As bitumen is extremely viscous, the flow is laminar and we have the familiar expression for the friction factor, f = 64/Re where Re is the Reynolds number
The flow rate Q is related to the pipe diameter d and velocity V by
Substituting from equations 2, 3 and 4 into 1, we obtain for the power the expression
In equation (5), we see that the pumping power is directly proportional to the temperature-dependent viscosity. A calculation with equation (5) and the viscosity data of Figure 2 illustrates the impact of heating, Table 1.

Effect of Temperature on Pumping Power of Bitumen
Volume flow rate: 250 barrel/hour
Pipe diameter: 3 in
Pipe length: 500 ft
Bitumen density 63.05 lb/ft3
Velocity 7.94 ft/s
oC oF    
40 104 17 382.0
60 140 2.8 62.9
80 176 0.6 13.5
100 212 0.2 4.5
Table 1 – Huge savings in pumping power are obtained by heating bitumen
Pumping power essentially decreases twenty-five-fold, from 382 kW to 13.5 kW, by heating the bitumen from 40 oC to 80 oC.
It should be pointed out that there is a savings not only in pumping power, but in capital cost, as a 13.5 kW pump costs but a small fraction of a 382 kW pump.



Figure 3 – Cross-section of a bitumen tank with electrical pipe heater.
Several techniques are used to heat bitumen. Electrical heating is a prime choice because of its precision, uniformity and compactness, among other qualities. Common arrangements are:
·         An immersion-type tank flange heater, comprising several metal-sheathed resistance heating elements in direct contact with the bitumen. The bitumen is heated and circulates by natural convection inside the tank;
·         A circulation heater. Here the flange heater is inside a circulation vessel fitted with inlet and outlet connections; heat transfer to the bitumen occurs by forced convection;
·         A pipe heater, one in which the heating elements are enclosed in a pipe and thereby shielded from direct contact with the bitumen as seen in Figure 3. This arrangement may be preferred in case of extreme viscosity.
In general, all bitumen must be considered as a flammable liquid or presenting the danger of an explosion in case of excessive heating. The maximum storage and handling temperature corresponds to the flash point, i. e. the temperature at which the vapor above which a liquid will catch fire in the presence of air and of a source of flame. This temperature varies according to the quality; a typical value is 450 oF. Accordingly, it is recommended that bitumen heaters have an explosion-proof (NEMA 7) enclosure.

Density ρ lb/ft3 kg/m3
Friction factor f (dimensionless)
Pipe diameter d in m
Pipe length l ft m
Power P HP kW
Pressure drop Δp psi kPa
Reynolds number Re (dimensionless)
Velocity V Q ft/s m/s
Volume flow rate   barrels/hour m3/s

[1]Mehrotra, A. K. and W. Y., C. J. Ch. E., v. 64, Oct. 1986.

Latest blogs

Common Industries that Wattco works with

Case Studies View All

Why is Mineral Oil Used in Thermal Heaters?
Thermal heaters, also known as thermal fluid heaters, employ the use of a thermal liquid such as wat...
Read More..

What to Use When Heating Wax
SituationA popular chemical compound that often requires heating is wax, which is an organic compoun...
Read More..

What is Passivation? Why do We Need to Passivate Flanged Heaters?
  Most of the parts of flanged heaters are made of stainless steel—an alloy that is mainly compri...
Read More..

What is a Digital Controller?
Control panels are essential elements of any electrical device. Control panels are especially i...
Read More..

Vegetable Oil Heating
Food Industries and Vegetable Oil Viscosity In Cleveland Ohio, a large food manufacturer called WATT...
Read More..

Wattco News View All

Circulation Heaters – Ideal for Clean Water Heating Applications
The rise of technology has left lasting impressions on the world of heating with some of newest heat...
Read More..

WATTCO Invites you to attend our booth #1867 at the Global Petroleum Show
Come see our exciting newly developed industrial heating products specifically designed for the Oil ...
Read More..

4 Advantages of Skid Systems in Industrial Heating Processes
Many industrial heating processes involve maintaining a consistent temperature in a vessel to protec...
Read More..

Advantages of Preheating Crude Oil With Electric Flanged Heaters
Crude oil refining is one of the most complex chemical processes in the petrochemical industry. As s...
Read More..

Electrical Heating Element
Long gone are the days when traditional heaters were used for heating purposes. Traditionally, the i...
Read More..

Most Popular Blogs View All