Study On Scale In Evapration Concentration Method Of Sugarcane Molasses Alcohol Efflenent And Its Sacle Control

The effluent expelled from sugarcane molasses alcohol production is difficult to handle. Multi Effect Flash Evaporation Concentration Method is used extensively to recycle the effluent. However, numerous scale generated during the processing will attach to the surface of heat-exchange equipment under this high temperature and low pressure and it is difficult to clean away. The scale will have a major impact on the heat transfer and fluid flow, the production cost will increase, heat-exchange machine will be partly overheated and be eroded. This paper analyzes the major components of the scale and its crystal shape, simulates an experiment to research the deposition property of scale in concentration processing, combines descaling and scale inhibition method to determine a comprehensive scale control. The research results are as follows:(1) Through the analysis of chemical titration, the major ingredients are difficult soluble inorganic salt which mainly contains calcium salt and sulfate salt、several organic objects、colloid particles and so on. By taking use of Scanning Electron Microscope with an energy spectrum, the typical crystal form of scale is oblique cube with smooth surface, the main chemical elements are S、 O and Ca, the major constituent of scale is CaSO4.(2) The surface temperature of1#heat-exchanger reaches to115℃. Ash content here is relatively low and the sulphate accounts for the major part. After the observation of soil, crystal form is quite small, dense, irregular with a rough surface and aggregation. Spectrum energy diagram shows that chemical elements are S、Ca、O、K. Sylvite is soluble and its main resource is from depositional yeast cell. The amount of surface soil of effluent and pyrogenic decomposition soil is high, which indicates respectively that there are abundant soil and part of organics is in the state of suspension which may deposit because of gravity. Through investigation it is found on the heat transfer surface and thus we can make the prediction that the high temperature destroys the organics in soil and the constant state of large colloidal particles. The coalescence of them lead suspending calcium sulfate crystal from depositing to scale. When organics is heated, they coke on the heat exchanger surface and make the soil irremovable.The temperature in2#heat-exchanger is100℃. The increase of saturability of calcium sulfate can promote the crystal form. With electron microscopy (SEM) figure, we can conclude that there are two different kinds of crystal forms of calcium sulfate. Along with the destruction of organics, their dispersion and suspension effect on crystal particle of calcium sulfate disappear. As a result, in the2#heat-exchanger the crystal form of calcium sulfate is mostly separated out. It is tested that the amount of surface soil and surface pyrogenic decomposition of3#heat-exchanger at this time can separate less soil under gravity. The ratio of organics in surface pyrogenic decomposition increases. By analyzing the constituents of soil, we can also find several kinds of inorganic salt are separated out and their crystal form is relatively large and loose with a smooth surface. When various kinds of crystal form of metal salt in soil development and mixed crystal are separated out, the soil this time is a loose structure, little deposition and is easy to remove.(3) Compared to Standing Descaling Method, eccentric descaling method works efficiently. In single chemical scale inhibitor experiment, the most appropriate additive amount is NO.1and NO.350mg·L-1, NO.425mg·L-1.When compounding scale inhibitor according to the most appropriate ratio of1:1:1, conducting orthogonal experiment to optimize the environmental factor. We get the best condition:temperature at70℃,stirs speed of120r℃min-1,and work time of40min. Under this condition, scale inhibition efficiency reaches to33.4%. When the work time of an ultrasonic wave scale inhibition method is40min and frequency is120Hz, the scale inhibition efficiency reaches to the highest of20.2%.(4) This paper evaluates the scale inhibition effect of pulse deposition device of F factory. The scale inhibition is26.47%. Through the analysis of flocculant experiment of pulse deposition device, the scale inhibition effect comes to the best when the additive compound Polyaluminium chloride flocculant is6ppm and the filth-controlling rate is36.23%。 when the additive compound Polyaluminium chloride flocculant is excess, it will retain the scale inhibition efficiency.(5) The comprehensive filth controlling plan directing is "first descaling and then scale inhibition". That is first adopting eccentric descaling method, and then chemical antitussive agent scale inhibition and finally ultrasonic wave scale inhibition method. After this measure, scale inhibition efficiency can reach39.82%.