Principle of graphite heat exchanger

Graphite heat exchanger - the principle of graphite heat exchanger

Graphite not only has acid corrosion resistance, but also has good thermal conductivity. The graphite core is made into a block-hole structure that is vertically and horizontally separated from each other. When the two media pass through each other, the high-temperature medium continuously transfers heat to the graphite. The low-temperature medium continuously obtains heat from the heat exchanger, thereby realizing heat exchange. Graphite heat exchangers are heat exchangers whose heat transfer components are made of graphite. Graphite for manufacturing heat exchangers should be impermeable, and impregnated impermeable graphite and pressed impermeable graphite are commonly used. Graphite heat exchangers can be divided into three types according to their structure: block hole type, tube shell type and plate type. Block hole type: assembled by several block graphite components with holes. Shell and tube type: Shell and tube heat exchangers occupy an important position in graphite heat exchangers, and are divided into two types: fixed type and floating head type according to the structure. Plate type: The plate heat exchanger is made of bonded graphite plates.

Graphite heat exchanger - introduction to the structure of graphite heat exchanger

Graphite heat exchangers can be divided into three types according to their structure: block hole type, shell and tube type and plate type. Block hole type: assembled by several block graphite components with holes. Shell-and-tube heat exchanger: shell-and-tube heat exchanger occupies an important position in graphite heat exchangers, and can be divided into fixed type and floating head type according to the structure. Plate type: The plate heat exchanger is made of bonded graphite plates. In addition, there are immersion type, spray type and casing type (see coil heat exchanger, casing heat exchanger). The graphite heat exchanger has good corrosion resistance, the heat transfer surface is not easy to scale, and the heat transfer performance is good. However, graphite is brittle and has low flexural and tensile strengths, so it can only be used at low pressures. Even with the best block pore structure, the working pressure is generally only 0.3-0.5 MPa. Graphite heat exchangers are expensive, bulky and rarely used. It is mainly used for heat exchange of corrosive media such as hydrochloric acid, sulfuric acid, acetic acid and phosphoric acid, such as a condenser for acetic acid and acetic anhydride.

Graphite Heat Exchanger - Advantages and Disadvantages of Graphite Heat Exchanger

Advantages: Suitable for non-oxidizing or weakly oxidizing strong acids, alkalis, salt solutions, most organic solvents and composite media of organic acids. The thermal conductivity is higher than that of many metals, second only to copper and aluminum, 2 times larger than carbon steel, 5 times larger than stainless steel, ranking first among non-metallic materials, suitable for making various heat exchange equipment. Small coefficient of linear expansion, high temperature resistance, thermal shock resistance. The surface is not easy to scale and has no pollution. Good machining performance. Small density and light weight.

Disadvantages: Graphite heat exchangers are divided into two types: block hole type and tube shell type. The main disadvantage of block-hole graphite heat exchangers is that once a leak occurs, it is difficult to find and repair. The disadvantage of the shell-and-tube graphite heat exchanger is that the strength of the graphite tube is relatively low, and the steam pressure used cannot exceed 0.15MPa; the flow rate of the heating medium is low and can only be controlled at 2 ~ 3m/s; the temperature difference between the inlet and outlet can only be controlled at 2 ~ 4 ℃, the volume of the heat exchanger is large.