Graphite materials are used in heat exchangers because they provide good refractory and mechanical properties but still maintain a high thermal conductivity.
Graphite heat exchangers provide excellent corrosion resistance to a wide variety of chemicals and are therefore commonly used in the following industries such as; chemical refining and processing, petrochemical, food and beverage, pharmaceutical, fertilizer, steel pickling, mining and metal finishing.
Types of Graphite Heat Exchangers
Cubic Heat Exchangers
Manufactured from a solid block of graphite with a square cross-section, the Cubic Block type heat exchangers is a simple design that is easy to maintain. The solid graphite block is kept in compression so this design is resistant to thermal and hydraulic shock as well as external loads.
The graphite block is maintained under compression by assembly plates tightened by tie rods. Each lateral face of the block is drilled with parallel cylindrical holes to allow fluid flow. The rows of holes are alternated through the thickness of the block.. Headers can be equipped with baffle plates to provide a multipass design if needed. This optimises the distribution of the two fluids by making conditions as close as possible to real countercurrent flow, which is particularly useful in energy recovery applications. It is also possible to vary the cross section or to have split flow. PTFE gaskets are used between the block and headers – no other gaskets are required.
- No gaskets or cemented parts between flow channels.
- Resistant to thermal shock
- Easy cleaning
- short channels
- simple dismantling and assembly
Graphite Block Heat Exchangers
The main reason for employing Graphite Block Heat Exchangers is their great flexibility. Best described as a series of block heat exchangers staked together and installed in a shell, they are modular which makes maintenance and expansion easy.
Corrosive fluids contact only the impervious graphite blocks having complete resistance to all acids, alkalis and solvents with the exception of a few strong oxidizing agents. The steel shell can be lined with suitable material or furnished in alloy materials to resist practically all corrosives, thereby allowing handling of two corrosive fluids.
- Rapid replacement of damaged blocks due to compact modular design
- High thermal efficiency, flexible in design and Compact
- Easy maintenance (cleaning and block replacement are very simple / simple dismantling and assembly)
- Corrosive media can be used in both service and process sides
- Capacity can be increased by adding block elements
Features / Design Options:
- ASME Construction and Stamp Available High Pressure Design
- Radial Multipass
- Easy cleaning
- Axial Multipass
- Four Available Impregnations
- Large Diameter Process Holes Available
- Overhead condensers and sump coolers
- Pickling line heaters
- Reactor heat exchangers; Including hydrolysis, polymerization or condensation reactions, where heat must be removed or supplied rapidly, during the reaction.
- Circulation coolers for quenchers
- Heating or cooling of corrosive fluids with water, brine, steam, gases or fluids.
- Boiling liquids in evaporation or distillation plants, etc.
Graphite Shell and Tube Heat Exchangers
Graphite shell and tube heat exchangers are used as heaters, coolers, condensers, falling-film coolers, evaporators and absorbers, especially in the treatment of:
- hydrolic acid
- sulphur acid
- hydroflouric acid
- phospheric acid
- chlorinated acid
- organic and inorganic media
- waste acids
- combustion gases
- Low pressure drops and high efficiency
- Large heat exchange area
- Excellent resistant to stress and pressure surges
- Special grades of tubes with higher strength and better corrosion resistance are available
- The units are easy to repair and bundles can be replaced