Course project: "Development of a system for cleaning air from dust and phenol in the production of plastics"

The theme of this course project: "Development of an air purification system for dust and phenol in the production of plastics." Polymers, in particular plastics, are one of the most common artificial materials absent in nature. The name "plastics" means that these materials, under the influence of heating and pressure, are able to form and maintain a predetermined shape after cooling or hardening [1]. Their prevalence, application is due to a number of their specific properties, such as low density with satisfactory technological strength, high chemical corrosion resistance, good electrical insulation properties, etc. In the production of plastic masses, harmful and dangerous factors are: hot materials and production equipment (danger of burns); moving parts of machine equipment (danger of mechanical injuries), the need to move heavy masses of materials, products, equipment parts, as well as the danger of electric shock and discharges of static electricity. But the greatest danger and harm are formed by gas-steam emissions and dust. The objectives of the course project are the selection of equipment, equipment calculation, development of a technological scheme for cleaning air from dust and phenol during the production of plastics. Calculation of task 3.2 Calculation of cyclone 1) We calculate the cyclone cross section area, m2 [7]: F = Q/wopt, (1) where Q is the cleaned air flow rate; wopt - optimal gas flow rate in the cyclone, m/s. Qgl = 600m3/ch∙8 = 0.17 m3/s∙8=1,36 m3/s; (2) F = Q/wop = 1.36/3.5 = 0.39 (m2). (3) 2) We calculate the diameter of the cyclone apparatus, m: D =; (4) D = (m); (5) 3) We calculate the actual air velocity in the cyclone, m/s: w = Q/0,785∙N∙D2; (6) w = 1,36/0,785∙1∙0,72=3,58 (m/s2); (7) 4) Determine the hydraulic resistance of the cyclone: The local resistance coefficient of the cyclone is ¼ c = K1∙K2∙ζ500 + K3, (8) where K1 is the coefficient depending on the cyclone diameter = 1, K2 is the correction coefficient for dust content of air = 1; ζ500 - the coefficient of local resistance of a cyclone carried to speed in cyclone section (at an exhaust in network for TsN-15 = 163); K3 - coefficient per arrangement method for the group of CP cyclones (= 0). ζц = 1∙1∙163 + 0 =163. (9) 5) Calculate pressure loss in the cyclone, Pa: ΔP = ζts∙pg∙w2/2; ΔP = 163∙0,00128∙3,582/2 = 1.34 (Pa). (10) 6) Calculate the particle diameter captured in the cyclone with an efficiency of 50%:; (11) (μm). (12) 7) Calculate the dimensionless coefficient x: (13) (14) f (-0.11) from the table of Appendix A = 0.4602. 8) We calculate the actual efficiency of gas purification in the cyclone h = 0.5 (1 + f (x)) 100 = 0.5 (1 + 0,4602) 100 = 73 (%). (15) 3.3 Calculation of bag filter Dust concentration after cyclone CN-15 decreased by 0.3g/m3-73% = 0.08g/m3 = 80 mg/m3, which exceeds the norm of 10 mg/m3 by 8 times. 1) Determine specific gas load: q = qH∙c1∙c2∙c3∙c4∙c5 [8]; where qH is the normative specific load depending on the type of dust and its tendency to agglomeration (for plastics qH = 1.7); c1 is a coefficient characterizing the characteristic of regeneration of filter elements c2 - a coefficient taking into account the effect of concentration on the specific load; c3 is a factor that takes into account the influence of the dispersed composition of dust in the gas; c4 is a factor that takes into account the influence of gas temperature; c5 is a factor that takes into account the requirements for cleaning quality. q = 1,7∙1∙1,1∙0,9∙1∙0,95 = 1.6 (g/m3).(16) 2) Calculate filtration surface: F = Q (60q); F = 4800 (60∙1,6) = 50 (m2); (17) The filter FRKI-60 with actual filtering surface of 60 m2 is selected from the catalogue for the given conditions. The degree of purification of this filter is 98-99.6%. The filtration rate when using lavsan hoses in combination with pulse blowing is 1.6-3.5 m/s, depending on the contamination of the filter surface. The dust content after cyclone TsN-15 was 80 mg/m3. We calculate the dust content after the bag filter: 80 mg/m3-98% (we take the minimum cleaning value) = 1.6 mg/m3. The result, more than, meets all standards. 3.4 Adsorber calculation Volume flow rate of steam-air mixture supplied for adsorption Q = 4800 m3/h. Initial concentration of formaldehyde C0 = 2.5 mg/m3. The velocity of the steam-air mixture w = 1.6 m/s, counting the minimum speed after the sleeve filter. Dynamic adsorption capacity of activated carbon (AU) ad = 7% (wt), residual activity after desorption 0.8% (wt). Bulk density HEY ρнас = 500 kg/m3. The duration of the adsorption period is 30 days (720 hours). Once a month, adsorbent regeneration is assumed. The mass of the adsorbent from the material balance equation for the pollutant (impurity to be removed) is [9]: ma = = = 140 kg. (18) The geometric dimensions of the adsorber are as follows: Da = = = 1.1 m. (19) Na = = = 0.3 m. (20) The weight of activated carbon is 140 kg, the diameter of the adsorber is 1.1m, the height of the adsorbent layer is 0.3m. Thus, the proposed scheme will achieve high air purification not only from dust (98-99.6%), but also from gaseous substances - phenols.