Benefits of Compabloc technology versus shell & tube - Alfa Laval

Compabloc is a welded plate bloc type heat exchanger technology widely known for its high heat transfer efficiency and compact size. In the past three decades, more than 30,000+ units have been installed globally in various applications like crude oil refinery, oil and gas, petrochemicals, pulp and paper, mining and metal industries, to name a few.

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Compabloc technology is widely deployed in crude oil refinery processes like crude oil distillation, alkylation, hydrotreating, isomerization, catalytic cracking, sour water stripper etc. with more than -unit installations, delivering high performance in heat recovery applications, condensers, reboilers and product coolers.

Some of the most widely known benefits of Compabloc's technology over Shell &Tube are:

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• High heat transfer efficiency—3 to 5 times heat transfer coefficients compared to shell & tube.
• Compact Size—40,000 ft2 of shell & tube equivalent HTA can be fit in 7 x 7 ft2 of plot space.
• Lower Capex/ Total Installed Cost—Less number of shells, piping, insulation, foundation, valves, instrumentation and smaller structure.

This blog is intended to illustrate how Compabloc technology fares compared to its century old conventional counterpart shell & tube heat exchanger technology. For the purpose of comparison, a design simulation study was made using Alfa Laval’s proprietary design software for Compabloc technology and HTRI design software was used for shell & tube technology. Simulation was made for a typical heat recovery application in crude oil refinery—recovering heat from diesel product from atmospheric distillation column to boiler feed water. Table 1 shows/compares design output on various parameters for both Compabloc and shell and tube technology.

Parameter

Unit

Shell & Tube

Compabloc 

Application (Heat Recovery) Diesel Product vs Boiler Feed Water (BFW)

Design Input Parameters

Diesel Flow rate lbs/hr 355,000 BFW Flow rate lbs/hr 292,000 Diesel Temp. In/Out  oF 275 / 79.3 BFW Temp. In/Out in oF oF 70 / 190 Total Duty MMBtu/hr 35 Max. Design Pressure psig 370 Max. Design Temperature oF 350 Nozzle Size Hot In/Out, Cold In/Out inch 6 Pressure Vessel Code ASME Sec VIII Div.1

Design Output Parameters

No. of Shells required for Total Duty 4 in series 1 Exchanger Type & Orientation BEU Horizontal Compabloc Vertical Diesel pressures drop psi 15 17 BFW pressure drop psi 13 9 Total Heat Transfer Area ft2 17,960 Total Empty Weight lb 93,120 36,300 Total Flooded Weight lb  145,400 40,800 Tube/ Plate length ft 20 2.5 Shell OD  Inch 40 NA Overall Foot Print for single Shell ft 26 x 3.5 x 5.5 4.5 x 4.5 x 11.0 (Length x Width x Height) Approx. Overall Foot Print for total duty considering 2 stacked shells ft 26 x 10.5 x 11.5 (Length x Width x Height) Approx. Total plot space required including maintenance Length x Width ft 48 x 12.5 7.0 x 7.0 Shell Material SA516 Gr.70 Heat Transfer Material  SA214 SS316L Approx. Total Equipment Cost (S&T tubes in CS) 3.5 X X Approx. Total Installed Cost (S&T tubes in CS) 6 X 2 X Heat Transfer Material SA-249-TP316 SS316L Approx. Total Equipment Cost (S&T tubes in SS) 5.5 X X Approx. Total Installed Cost (S&T tubes in CS) 8 X 2 X

The key takeaways we found when  comparing the design output parameters of Compabloc and shell & tube from Table 1 include:

• 
  Compabloc needs five times less heat transfer area compared to shell & tube.
• Total duty can be performed in single Compabloc shell whereas we will need four shell & tube shells in series.
• Total flooded weight for Compabloc is 3.5 times less compared to shell & tube.
• Total plot space, including maintenance space required by single Compabloc shell, is 12 times smaller compared to 2 x 2 stacked shell and tubes.
• Total installed cost of Compabloc is six times less when compared with carbon steel shell and tube and eight times less when compared with SS tubes in shell and tubes.

To conclude, Compabloc welded plate heat exchanger technology is highly efficient, cost and plot space competitive for high heat recovery duties. We have also seen similar results in condensing applications with close temperature approach. General rule of thumb is: when you are working with two or more shell and tube in parallel/series, plot space limitation, tube metallurgy in higher alloys (eg. Stainless steel) OR when you want to reduce pressure drop, increase process unit capacity in same plot space, debottleneck or improve process efficiency, reduce utilities then you should consider evaluating Compabloc technology. Please contact Alfa Laval’s welded plate heat exchanger technologists for a free evaluation and consultation of your case.  

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