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Urea-formaldehyde concentrate continuous mfr. - using formaldehyde converter gases and aq. urea soln. reacting counter-current in single multiple stage absorption column
Urea-formaldehyde concentrate continuous mfr. - using formaldehyde converter gases and aq. urea soln. reacting counter-current in single multiple stage absorption column
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机译：尿素甲醛精矿连续生产。 -使用甲醛转化器气体和水溶液尿素溶液单级吸收塔中的逆流反应
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摘要
An aq urea(U)-formaldehyde (F) concentrate (F:U mole ratio of 4-6:1 solids content 65-85 wt %) is continuously produced by continuously introducing gases from an HCHO converter into the bottom of a single HCHO absorber column down through which a 40-80 wt % aq. urea soln. is continuously fed from the top stage, the temp. in the column being 25-80 degrees C. Simultaneously a dil. aq. soln. of a base is fed into the column at a multipel of points so that the pH of the aq. soln. of methylol-ureas formed in the column is maintained at 6-9. Part of the aq. soln collected at the bottom of the column, is continuously recirculated to the column at a point above the last point where dil. aq. base is being fed and above the point where the gases are being introduced, but below the top stage of the column. The remainder of the collected aq. soln. is continuously removed. The process provides an efficient means of making a U/F concentrate using only a single HCHO absorber column. Formaldehyde losses in the absorber off-gases are reduced. The concentrate is used in the prodn. of urea-formaldehyde resins.
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