Graphite evaporator: what are the advantages of graphite heat exchanger?

The corrosion resistance and thermal conductivity of graphite heat exchangers are better than those of stainless steel; the pressure resistance of stainless steel heat exchangers is better than that of graphite heat exchangers. The specific material of the heat exchanger is mainly determined according to the process conditions. The applicable one is better. Of course, the cost performance must be considered. The graphite used in the heat exchanger made of graphite should be impermeable, and impermeable graphite and pressed impermeable graphite are commonly used. 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 easily brittle and has low flexural and tensile strength, so it can only be used at low pressure. Even if the block-shaped structure with better pressure bearing capacity is generally only 0.3 to 0.5 MPa. Graphite heat exchangers are expensive, bulky and not used much. It is mainly used for heat exchange of corrosive media such as hydrochloric acid, sulfuric acid, acetic acid and phosphoric acid, such as condensers for acetic acid and acetic anhydride. The bigger difference between graphite heat exchangers is not the heat transfer performance and corrosion resistance, but the copper tube is less prone to scaling, which the Chinese people do not realize.

Foreign commercial boilers do not use water treatment equipment, but their lifespan is as long as 15 years. The reason is that although water can also form scale on the copper pipe wall, it is only flocculent scale. In this case, as long as the water flow rate is increased, the scale cannot be precipitated. The second is heat transfer performance. The thermal conductivity of copper is higher than that of stainless steel, so the heat transfer coefficient of copper tubes of the same shape is higher than that of stainless steel. Therefore, the heat exchange tubes used in the evaporator condenser are basically made of copper. And the strength is higher than copper, so now the plates of the plate heat exchanger we see are all stainless steel, but the original plates are also copper.

Graphite heat exchangers can be divided into three types: block type, shell and tube type and plate type according to their structure. Block hole type: It is assembled from several block graphite components with holes. Shell and tube type: Shell and tube heat exchangers play an important role in graphite heat exchangers, and are divided into fixed type and floating head type according to their structure. Plate type: The plate heat exchanger is made by bonding graphite plates. In addition, there are immersion type, spray type and casing type, etc. (see coil type heat exchanger, casing type 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. Corrosion resistance: suitable for non-oxidizing or weakly oxidizing strong acids, alkalis, salt solutions, most organic solvents and composite media of organic acids. High thermal conductivity: The thermal conductivity is higher than many metals, second only to copper and aluminum, 2 times larger than carbon steel, 5 times larger than stainless steel, ranking first in non-metallic materials, suitable for making various heat exchange equipment.

Graphite heat exchangers are increasingly widely used in cold-rolled pickling lines and chemical, petroleum, pesticide and other industries. The application of graphite heat exchanger in pickling line is mainly introduced. In the cold-rolled pickling process, the acid is pumped out of the acid tank from one end of the acid tank by the graphite heat exchanger, pumped into the graphite heat exchanger, heated by the graphite heat exchanger and discharged back to the other end of the acid tank. It is carried out continuously, so it is realized that the graphite heat exchanger heats the acid. The graphite heat exchanger changes the heating method of the acid, makes the acid warm up evenly, shortens the heating time, reduces the steam consumption, reduces the energy waste, and improves the efficiency. Working efficiency: The graphite heat exchanger increases the fluidity of the acid, which has a certain scouring effect on the surface of the strip, and accelerates the process of removing the scale. Compared with the heating method of directly heating the acid liquid by steam, due to the change of the heating method, the superheated volatilization of the acid and the dilution of the acid by the condensed water are obviously weakened, and the acid consumption benefit is obviously reduced.