Phosphate slurry pump common sense

This pump is used to transport phosphate slurry media. It is one of the key pumps in the installation. It can be installed on the top of the extraction tank by vertical or horizontal vertical pumps. First, the characteristics of operating conditions 1, Dihydrate phosphate plant transport medium: Dihydrate phosphate slurry solids: phosphogypsum (the main component of CaSO4 • 2H2O and undecomposed phosphate and acid insoluble). 25% to 32% Liquid phase: 20% to 30% of phosphoric acid (P2O5); 41% to 40% of free sulfuric acid H2SO; 61% to 3% of fluorosilicic acid H2SiF; Slurry) 1.3 ~ 1.5t / m³ Medium temperature: 70 ~ 85 ℃ 2, semi-aqueous phosphoric acid plant Semi-aqueous phosphoric acid plant operating conditions and dihydrate phosphoric acid plant is the main difference between the liquid phosphoric acid concentration and the reaction temperature Higher, the specific data are as follows: liquid phosphoric acid P2O540% ~ 48%; reaction temperature 95 ~ 105 ℃. The above media are under vigorous stirring conditions. Second, the selection requirements Phosphate slurry pump selection requirements are mainly based on the medium and the reaction tank stirring conditions, both decay resistance and wear resistance of the pump over-current components of materials and reasonable structure of the vertical pump. 1, pump over-current parts material selection In the phosphoric acid medium (solid content less than 3%) under the conditions of ultra-low carbon molybdenum two titanium and molybdenum three titanium corrosion resistance is good, but phosphoric acid slurry (containing 25% ~ 35%) conditions, severe wear and tear, shortened service life. Therefore, pay particular attention to media and operating conditions when selecting pump overcurrent component materials. (1) Medium temperature pump The overcurrent component corrosion rate aggravates with increasing temperature. For example, the extraction phosphoric acid temperature from 70 ℃ to 85 ℃, the corrosion rate doubled. Therefore, the selection of materials to pay attention to the temperature. (2) phosphoric acid concentration increased phosphoric acid concentration, corrosion increased. For example, molybdenum tri-titanium stainless steel can resist corrosion in dihydrate phosphoric acid production. However, in semi-aqueous phosphoric acid, when used in a reaction vessel stirred shaft bushing, 85% of the molybdenum is corroded in only one month, point. Therefore, the dihydrate phosphoric acid reaction tank vertical pump overcurrent not seen Recommended CD-4Mcu; Z3CNUD26-05; Chromium 30 (F30% CrMo and FCr30) alloy; (F30% CrMo and FCr30) alloys; J-1 alloys; F5 alloys; SaniCrO28; HastelloyC. 2, the choice of pump speed Pump speed increase, will accelerate the impeller and volute overcurrent components such as erosion and corrosion. According to foreign Phosphorus Ammonia Phosphorus Ammonia plant pumps and Yunnan Phosphate Fertilizer Plant in the 1970s, the introduction of phosphoric acid plant pump speed, the vast majority of 970 and 1460r / min (the former more), but not up to 2900 r / min speed. Therefore, to meet the flow, lift the premise, try to choose low-speed pump. 3, the choice of vertical pumps and horizontal pumps Before the 1980s, China's phosphorus phosphate ammonia plant pumps, almost all vertical pumps. Due to the prevailing conditions, the domestic horizontal shaft pump leak serious. At present, many domestic horizontal pump sealing technology has been greatly improved, in addition to Dalian, acid pump plant double-sided mechanical seal more successful use, Jiangsu Zhangjiagang Jiangnan Chemical Equipment Factory production of aero-impeller with Feiyu parking sealed pump in the country Phosphorus, ammonia and ammonia plants of all sizes are also very successful. Horizontal packing used in the seal, agreed that the use of carbon fiber filler is more reliable. Compared with the vertical pump, the horizontal pump also has the following advantages: (1) The low price of horizontal pumps, usually the same flow, vertical pump lift 1/2 to 1/3, or even 1 / (2) vertical pump support frame cantilever shaft length is limited, often to produce control of the level of trouble. (3) If the vertical pump can not be directly installed in a large tank (such as phosphate finished product storage tank), the medium must be guided to the small tank of the vertical pump by the opening on the side of the lower part of the large tank, which increases the investment, Sometimes in order to prevent "empty" or "full slot", but also one more for the operating workers. 4, the choice of pump impeller type As phosphoric acid, phosphoric acid slurry and phosphorus ammonia material slurry contains solid particles, combined with the phosphate rock into the sodium, potassium and iron, aluminum, magnesium and other impurities, especially sodium, potassium ) In the production of phosphoric acid will produce sodium fluoride and potassium silicate, dissolved in phosphoric acid. As the temperature drops, solubility decreases and precipitates, making it easy to form a hard scale on the pump impellers, especially the volute (these foulants are also intermingled with other solids, such as calcium sulfate). Therefore, in the phosphorus phosphate ammonia plant, generally use open impeller, especially in the phosphoric acid plant reaction tank and phosphate filtration system, we must choose the open impeller; phosphorus ammonia slurry pump should also use open impeller. Third, the structure of phosphate slurry pump and product status at home and abroad Phosphoric acid slurry pumps are vertical, single-stage, single-suction cantilevered submerged pump, base, the liquid pipe separated from the cylindrical tube, without shaft seal. Pump shaft in the liquid part of the bearing does not set to accommodate the transport of solids containing media. The depth of the pump immersed in the medium can be 700 ~ 2000mm, if necessary, can also be installed at the pump suction inlet pipe.

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