Tubular graphite heat exchangers have various tube plate material, the graphite tube plate, stainless tube plate and titanium tube plate and carbon steel tube plate (needing anti-corrosion treatment) ,these several tube plate material have the advantages and disadvantages in the application of the soda ash, let’s explore it in the following several aspects .
The Comparison of corrosion resistance.
Corrosion in soda production is still quite strong, especially in the ammonium chloride section containing NH4 +, Cl -, CO32 -, Na + corrosive mediumthe of united alkali production , the corrosion resistance requirements for equipment is more higher.
Graphite is widely used in chemical production because of its excellent corrosion resistance, especially the corrosion resistance for CL-.
Stainless steel also is corrosion resistant material, but it contains a certain amount of CL- in the united alkali liquor ,it is corrosive for the stainless steel .
The precision requirements of the cooperation between the sealing rubber ring and tube plate is high,so the small corrosion of the tube plate will cause seal failure.
Titanium tube plate has good corrosion resistance, and it is widely used in soda.
The comparison of different materials of tube plate and graphite tube.
Graphite heat transfer tube and graphite tube plate is the same as the graphite material, the chemical composition is basically the same, the expansion coefficient is exactly the same. It don’t make the rubber gasket fatigue because of expansion force extruding rubber seal ring and to cause the seal failure phenomenon, it should be said it’s quite safe.Stainless steel expansion coefficient is 10 times higher than that of graphite, in under the action of the swelling stress will make the sealing rubber ring to produce fatigue and then affect the sealing effect.
The expansion coefficient of carbon steel is 4-5 times that of graphite, as well as that the expansion force will cause damage to the rubber ring, resulting in seal failure.
Need to explain is that the damage of expansion force has close relationship with temperature, in the production of soda ash, especially associated alkali ammonium chloride section, the lower the temperature, the less the rubber gasket damage caused by the expansion force.
The comparison of equipment maintenance and cleaning.
The daily maintenance and cleaning of equipment is also very simple, it can be cleaned by circulating water and hydrochloric acid for the fouling in the inner of tube,but it is prohibited that cleaning the equipment by mechanical method and high-pressure water gun .
It need the same procedure and time when we change the tubes of the stainless steel tube plate and graphite tube heat exchangers in the actual production , both of them require to remove the head, and then the change the graphite tubes. For the daily maintenance and cleaning of the equipment, it can be cleaned by circulating water when the scaling is light, but when the fouling is heavy, it can not be cleaned with hydrochloric acid (stainless steel is not resistant to hydrochloric acid). While the graphite tube can not be cleaned by the mechanical method and high-pressure water gun.
To be explained, due to the thickness of carbon steel pipe plate, stainless steel tube plate and titanium tube plate si more small than the graphite tube plate, the time of changing tube is faster than the graphite tube plate, but the total changing tube time required for is almost the same.
The comparison of pressure and temperature resistance.
The temperature resistance of the equipments with several different material tubes and plates is consistent because all of them use the graphite tube as a heat transfer tube based on the characteristics of the graphite tube that temperature resistance at -20 ℃ -180 ℃. In terms of pressure, the bearing pressure of stainless steel and carbon steel is big than the graphite . But now the graphite tube plate system equipment can withstand the pressure of 1.2MPA.
The comparison of equipment cost.
In terms of the overall cost of the equipment, titanium tube plate equipment is the most expensive. Stainless steel tube board equipment (in the soda is mainly due to 316L) the price is higher than the graphite tube equipment. The most economical equipment is the combination of carbon steel tube plate and graphite tube.