الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
SUMMARY
The problems of scale formation (adherent deposit of inorganic compounds and organic fouling precipitate from fermented mash) in molasses based alcohol distilleries are very common. The nature and intensity of scales may differ from distillery to distillery depending upon the quality of raw materials used for alcohol production and operating conditions of the distillery. Unwelcome gypsum precipitation is a serious problem associated with many sugar industry and byproducts due to the system of cane juice clarification
A new scale inhibitor was applied where a series of runs were conducted on clarified molasses of mash. The suitable concentrations of the anti-scale components were in the range from 5 to 30 ppm of different phosphonates, acrylic polymer and its co-polymer. The new anti-scale mixture as well as the commercially available inhibitors was tested at the same conditions of laboratory and pilot scales. The proper anti-scale mixture was chosen according to its maximum effective inhibition of CaSO4 precipitation and the greatest distortion of CaSO4 crystals at a dose of 20 ppm of this mixture. Applying this inhibitor enables us to enlarge the time intervals for mechanical cleaning of the stripping column, which can be regarded as an important advance in alcoholic distillation technology.
The study started by investigating the composition of distillery scale and parameters affecting the inhibition of distillery scales according to the following procedure:
* Collection of different samples from Hawamdia distillery during one year period. The finely divided scale samples were subjected to wet chemical analysis described in material and methods. The main composition (80.3%) of the scales was found to be calcium sulphate. Further investigations using atomic absorption and electronic microscope were done.
*Investigating of the effect of the individual anti-scalants on distillery scale inhibition was investigated as follow:
a- Inhibition effect of 1-hydroxyethyledene-1,1-diphosphonic acid(HEDP) on CaSO4 deposition and determination of mash TDS. The maximum inhibition was obtained at a dose of 20 ppm. the determined CaSO4 concentration at different dose of HEDP were compared with the corresponding values of TDS. It is showed that both results are compatible.
b- The work was intended to investigate the influence of polyacrylic acid mw/2000 water polymerized on CaSO4 deposition. Addition of that compound prevents deposition of the mineral scales and keeps the mash TDS values almost constant. The results showed that at 25 ppm a maximum inhibition of CaSO4 was obtained. Decreasing mash TDS values was, however obtained upon using 30 ppm of that inhibitor.
c- The effect of polyacrylic acid mw/2000 solvent-isopropanol - polymerized on the inhibition of CaSO4 was studied. Addition of the previous compound deeply affected the deposition of the mineral scales. The results showed that at 25 ppm maximum inhibition (71.4%) of CaSO4 was obtained. Further addition of inhibitor seems to decrease the ability of the inhibitor to keep TDS constant in solution.
D- Evaluation of the capacity of phosphinopolycarboxylic acid (PPCA) as a scale inhibitor was investigated. In this experiment, different dose of phosphino polycarboxylic acid were used. The results showed that the inhibitor strongly affects mineral scale deposition and keeps it soluble in solution. A higher effect was obtained at dose of 25 ppm..
e -Different doses of hexamethylenediamine-tetramethylenephosphonic acid. HMDP were used in laboratory and pilot scale as previously described. It was found that HMDP is a unique inhibitor for distillery scales, as it can prevent fouling and scale formation together. The results demonstrate the superior inhibition action on mineral scales deposition using this inhibitor.
Higher and economical values were obtained at a dose of 20ppm. The inhibitor is very effective for controlling gypsum deposits and at the same time stabilizing hydroxides of iron, demonstrating that HDTMP is able to overcome all the shortfalls of the current technology used for scale/deposit control in alcoholic distillation.
f - Polyacrylates and phosphonates are the work – horses of the sugar and distillery industry and are the essential building blocks in most antiscalant formulations. Different doses of maleic - acrylic co - polymer were used. The results showed that the inhibitor strongly affects minerals formation and fouling . The maximum inhibition of maleic - acrylic co - polymer was however obtained at a dose of 25 ppm.
g - The effect of phosphonobutanetricarboxylic acid on deposition and crystal distortion of gypsum scale was investigated. The selected inhibitor was added using different doses, namely at 5, 10, 15, 20, 25 and 30 ppm .
Addition of this compound greatly affects the inhibition of calcium sulphate deposition. The effect of this compound, however increases sharply at the doses 10, 15, 20 and 25 ppm. Maximum effect was obtained at 25 ppm. Further addition of the inhibitor leads to an adverse effect on calcium sulphate deposition and TDS of the solutions decreases.
h - The effect of different blend using the more effective inhibitors on inhibition of CaSO4 deposition was studied. These blends were investigated as follows:
1-Effect of a blend of 20% poly maleic 40% PAA and 40% HEDP on CaSO4 deposition. The blending investigations of maleic - acrylic co - polymer, PAAs, and HEDP after many trails of mixing different percentages showed that the above percentages of the inhibitors in the blend gave better results.
2 - The inhibition effect of a blend consisting of PAAs 40% PBTC 20% HEDP 15 % maleic - acrylic co - polymer 10% HMDP 15% on CaSO4 deposition showed that upon using the above inhibitor mixture at the optimal dose (25ppm) a noticeable reduction of incrustation on the heating surfaces of the laboratory jar and 6 % of CaSO4 was precipita