Bernard_Evaporators - GRADED

Bernard_Evaporators - GRADED - Summary and Explanations The...

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Summary and Explanations The base case steam economy is 2.40, the capacity is 71,794,077 Btu/hr, and the fre used is 28929 lb/hr. With the inclusion of the flash tank into the system the steam ec up to 2.47. The salesman of the flash tank said there would be a 4% savings in steam base case. With this model it shows that the flash tank did not reach this value and o savings of 2.88% from the base. This means that the salesman had incorrect inform not do correct calculations. The sensitvity analysis shows several important factors. The higher the feed tempera higher the steam economy and savings will be. The feed temperature at 185 C yielde economy of 2.48 and a savings of 3.32% from the base case. The feed temperature 180 C had a lower economy and savings. This means that if the liquor was hotter en not as much heat would needed to evaporate off water and not as much steam woul be used. This would mean cost savings in steam production. The analysis also shows that a higher % solids in the feed to the evaporaters will hav effect on the steam usage. If the liquor is at a higher solids content, then a lower am water will have to be evaporated out of the liquor. Small variations in inlet % solids w major effects on the steam usage also. When the inlet solids are at 13% the steam e be at 2.48, but the capacity goes up to 81,298,976 Btu/hr. This causes a -9.70% savi the base case which had an inlet at 14.5% solids. When the feed is at 16% solids the will go down to 62,305,922 Btu/hr, which translates into a 15.55% savings from the b Varying solids content of the weak black liquor will cause vast differences in the amo steam that has to be used in the evaporators. This means that the mill will be losing lower feed temperatures and % solids.
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esh steam conomy goes m from the only had a ation or did rature is, the ed an being at ntering, then ld need to ve a positive ount of ill have economy will ings from e capacity base case. ount of money at
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Vapor 24475.65 lb/hr 217.41 °F Steam in 90642.58 lb/hr Liquor out 90642.58 lb/hr Liquor in 115118.23 lb/hr Solids out 25.60% Solids in 20.15% 222.05 °F 187.83 °F Cond. Out 28929.24 lb/hr T vapor out T liquor in T liquor in Effect 1 U=150 A=4000 ft 2 Cp= .85 Effect U=200 A=4000 Cp= .89
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Vapor 21381.77 lb/hr Vapor 23500.00 lb/hr 184.42 °F 164.06 °F Liquor in 136500.00 lb/hr Liquor in 160000.00 Solids in 17.00% Solids in 14.50% 166.82 °F 183.00 Cond. Out 24475.65 lb/hr Cond. Out 21381.77 lb/hr T vapor out T vapor out T liquor in T liquor in t 2 ft 2 Effect 3 U=300 A=4000 ft 2 Cp= .92
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lb/hr °F
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Vapor 26202.90 lb/hr 220.81 °F Steam in #DIV/0! lb/hr Liquor out #DIV/0! lb/hr Liquor in #DIV/0! lb/hr Solids out #DIV/0! Solids in #DIV/0! #DIV/0! °F
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This note was uploaded on 02/07/2011 for the course PSE 417 taught by Professor Kirkman during the Fall '10 term at N.C. State.

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Bernard_Evaporators - GRADED - Summary and Explanations The...

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