. The manufacture of pulp and paper : a textbook of modern pulp and paper mill practice. °Be.; the solutionis then ready to be used in the absorption system. 41. The Tank System.âA three-tank system is shown indiagram in Fig. 10. It consists of three wooden tanks, arrangedone above the other, so that the milk-of-lime solution can flowfrom one tank into the next below. When the tanks are filled,the gas from the coolers enters at the bottom of the lowest tankA, in which it is absorbed by the milk of lime, forming at first 24 MANUFACTURE OF SULPHITE PULP M calcium (and magnesium) monosulphite CaS
. The manufacture of pulp and paper : a textbook of modern pulp and paper mill practice. °Be.; the solutionis then ready to be used in the absorption system. 41. The Tank System.âA three-tank system is shown indiagram in Fig. 10. It consists of three wooden tanks, arrangedone above the other, so that the milk-of-lime solution can flowfrom one tank into the next below. When the tanks are filled,the gas from the coolers enters at the bottom of the lowest tankA, in which it is absorbed by the milk of lime, forming at first 24 MANUFACTURE OF SULPHITE PULP M calcium (and magnesium) monosulphite CaS03 (and MgS03)which is very sightly soluble, but which, in the presence of anexcess of sulphur dioxide, combines with the sulphur dioxide,forming the soluble calcium bisulphite Ca(HS03)2 (and magne-sium bisulphite Mg(HS03)2). The reactions are:Ca(OH)2 + S02 = CaS03 + H20 CaS03 + S02 + H20 = Ca(HS03)2The gas from the burner enters the lowest tank A through alead pipe a. The unabsorbed gas leaves the first tank A througha lead pipe b, and enters the bottom of the second tank B, where. Fig. 10. it reacts with the milk of lime, as in the tank A. The gas thatis not absorbed in tank B enters the third tank C through thepipe c, the unabsorbed gas (nitrogen and oxygen) leaving thisuppermost tank through d. The gas is either pulled throughthe system by means of a vacuum or is forced through the tanksunder pressure. In the vacuum system, it is difficult to discoverleakage; and air may enter and cause the formation of S03,which forms insoluble sulphate with the lime and causes troublein form of deposits in the bottom of the tanks (which again meansa loss of sulphur and lime), and plugs pipes and valves. Thepressure system is better, and small leaks are easily In the intermittent system, the gas is passed through thesystem until a sample taken from the lowest tank shows thedesired strength. This tank is then emptied through g, and the §4 PREPARATION OF THE COOKING ACID
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpaperma, bookyear1921
