Heat Exchanger Tubes in the Mining Industry

Efficient heat recovery is an essential component in reducing energy costs and decreasing the negative environmental impact of the mining process. Shell and tube heat exchangers are particularly well suited for industrial mining since they can withstand the demands of high temperatures and substantial pressures.

In a shell and tube configuration, the shell contains an inlet and outlet flow control which determines the amount of fluid entering the device. The tube bundle is positioned inside the shell and is used to either heat or cool the fluid traveling through the shell side. Various materials and the tube design determine the efficiency of the overall heat exchange process.

Tube Design

There are several varieties of shell and tube heat exchangers including U-tube, spiral, finned and straight tube. The Tubular Exchangers Manufacturers Association (TEMA) provides standards for products with a shell diameter of 10 inches or above.

Tubes are either welded or seamless and are made from copper, stainless steel, copper-nickel alloy, low carbon steel and titanium. Exotic metals and alloys are also sometimes used in especially corrosive environments.

A primary heat exchanger design utilizes the U-shaped tube. The tube bundle includes flow baffles or tube supports depending on the nature of the fluid surrounding the tubes. Additional enhancements can be added to the surface to promote greater fluid turbulence which results in a more efficient energy exchange.

In environments with fluids that contain contaminants, or whenever there are cross temperature conditions, a straight tube design may be more appropriate. Head assemblies can be removed for cleaning, but the ability to handle significant temperature differentials may be the limited.

Shell Design

Steel is used in most shell designs, primarily for economic reasons. It is important to obtain consistency in the inner shell diameter to minimize the baffling space on the outside edge. Unnecessary space causes fluid to pool and bypass the core, resulting in greater inefficiencies.

Impingement plates can also be added to regulate high fluid velocity from the nozzle and promote even distribution of the fluid over the tube assembly. This helps prevent premature erosion while reducing vibration as well.

Value

Shell and tube heat exchangers can serve to enhance the productivity and lower the overall cost of mining operations. Recovered heat can be used to augment the leaching process and improve plant performance. Other applications include quench oil coolers. strike solution cooling and analyzing heaters and coolers.