Foamed SiC is a kind of porous ceramics with three-dimensional network connected structure. Its characteristics are: The holefraction higher than 99%, and according to the application requirements, respectivelyselect the mesh size and porosity in the range of 0.5mm-5mm and 30%-90%; High intensity, is 5-7 times as much as the same kind of material in the country. For example, at 70% porosity, the compressive strength is 30MPa; The excellent thermophysical properties, the thermal conductivity is more than 10 times higher than that of the same kind in China. For example, at 70% porosity, the thermal conductivity at room temperature reaches 50W/m.K, about 3 times as much as stainless steel; Excellent corrosion resistance, can be used for a long time under the conditions of strong acid, strong alkali and high temperature oxidation; Excellent processing and molding performance, can achieve accurate fabrication of complex configuration foamed SiC; It can use the soldering and brazing technology realize connection with metal reliably; Low cost, compared with the international same property material (CVD method, USA), the cost is only 1/10. At present, the production technology of foamed SiC has entered the stage of industrialization, It has an annual production capacity of 1000m3 SiC foam in Liaoning Zhuoyi new materials company.
2,Application of high performance SiC foam in chemical separation process
Distillation is the main technical means of chemical separation, and occupies an important position in the chemical process industry. At present, the energy consumption of distillation accounts for 50 to 70% of the whole separation process, Reducing the energy consumption of distillation is the key point of energy saving in the chemical industry, and it needs the support of new high efficiency tower internals. In view of the large specific surface area, excellent three-dimensional network connection structure, high thermal conductivity, acid and alkali corrosion resistance of foam SiC, a new type of highly efficient foam SiC corrugated regular packing has been developed by the Institute of metal research, Chinese Academy of Sciences. The new high efficiency foam SiC corrugated packing has the following advantages compared with the existing regular packing: First, it has excellent fluid mechanics and mass transfer performance, showing significant enhancement of mass transfer and heat transfer enhancement. Under the fluid mechanics performance is not reduced conditions, the separation efficiency of SiC foam material than wire mesh corrugated BX structured packing (500X) improve 50%-80%, MELLAPAK (350Y) filler nearly doubled, than MELLAPAK (350Y) packing improve nearly doubled, show table 1; Second, excellent corrosion resistance performance, long service life, can effectively guarantee the quality of the product. The new high performance SiC foam corrugated structured packing is a kind of promising tower materials, especially in various corrosive media and high requirements on separation efficiency, more broad application prospects, can become a high-grade stainless steel, titanium and other structured packing alternatives. At present, various types of fillers have been developed, and figure 1 is the physical photo of the packing
Table 1 Comparison of theoretical plate number of foam SiC filler and wire mesh BX 500X and mellapak350Y filler
Spray density m3/(m2×h)
Number of theoretical plates
Wire mesh Ripple 500X
Foam SiC 500X
Foam SiC 350Y
Figure 1-1 figure1-2
figure1 Packing picture
A new type of foam SiC tower valve and tray is developed under the cooperation of the Institute of Metal Research, Chinese Academy of Sciences and the national rectification center of Tianjin University, as shown in Figure 2 below. Its each performance was tested at Tianjin University, and the results are compared with the commonly used F1 floating valve tray. The results are shown in Figure 3.
Figure 2-1 Foamed SiC tower valve figure 2-2 Foam SiC tray
Figure 3-1 A comparison diagram of pressure drop between SiC mass transfer body and dry-wet plate of F1 floating valve
Figure 3-2 A comparison diagram of the entrainment between the SiC mass transfer body and the F1 floating valve
And get the following form:
Comprehensive comparison of foamed SiC tray and F1 float valve
Type of tray
The clear liquid height
Whole tower efficiency
F1 floating valve
The results show: Foamed SiC mass transfer tray does not exist weeping phenomenon, wet and dry plate pressure drop lower than the F1 floating valve tray, the clear liquid height of it higher than the F1 floating valve tray. In addition, the entrainment of foamed SiC mass transfer tray is also smaller than the F1 floating valve tray. These results show that the SiC mass transfer tray is a new type of high efficiency tray.