Triple-effect evaporators

A liquid with no appreciable elevation of boiling-point is concentrated in a triple-effect evaporator. If the temperature of the steam to the first effect is 395 K and vacuum is... 

A triple-effect evaporator is fed with 5 kg/s of a liquor containing 15 per cent solids. The concentration in the last effect, which operates at 13.5 kN/m2, is 60 per cent solids. If the overall heat transfer coefficients in the three effects are 2.5, 2.0, and 1.1 kW/m2K, respectively, and the steam is fed at 388 K to the first effect, determine the temperature distribution and the area of heating surface required in each effect The calandrias are identical. What is the economy and what is the heat load on the condenser ... 

A salt solution at 293 K is fed at the rate of 6.3 kg/s to a forward-feed triple-effect evaporator and is concentrated from 2 per cent to 10 per cent of solids. Saturated steam at 170 kN/m2 is introduced into the calandria of the first effect and a pressure of 34 kN/m2 is maintained in the last effect. If the heat transfer coefficients in the three effects are 1.7, 1.4 and 1.1 kW/m2K respectively and the specific heat capacity of the liquid is approximately 4 kJ/kgK, what area is required if each effect is identical Condensate may be assumed to leave at the vapour temperature at each stage, and the effects of boiling point rise may be neglected. The latent heat of vaporisation may be taken as constant throughout. 

A feed-forward triple-effect evaporator is to concentrate 5 % NaOH to 50 % NaOH. 

Fig. 21. Reordered occurrence matrix for the triple effect evaporator system illustrated in Fig. 20.

The classical procedure to solve the triple effect evaporator problem is as follows ... 

Equations and Unknown Variables for Triple Effect Evaporator... 

Figure 14.5. Forward-feed arrangement for a triple-effect evaporator...

Figure 14.8. Effect of feed temperature on the operation of a triple effect evaporator (a) Forward feed...

A triple-effect evaporator concentrates a liquid with no appreciable elevation of boiling point. If the temperature of the steam to the first effect is 395 K, and vacuum is applied to the third effect so that the boiling point is 325 K, what are the approximate boiling points in the three effects The overall heat transfer coefficients may be taken as 3.1, 2.3, 1.3 kW/m2 K in the three effects, respectively. 

Edmondson, K.H. Disposal of antibiotic spent beers by triple effect evaporation. Proceedings of the 8th Industrial Waste Conference, Purdue University, West Lafayette, IN, 1953 46-58. 

Figure 8.17. Forward and backward of liquid flow with respect to steam flow in triple-effect evaporators, (a) Forward flow of liquid by action of pressure differences in the vessels, (b) Backward-pumped flow of liquid through the vessels.

Fig, 1. Triple-effect evaporator used in concemraiing soda solutions and preparation of solid sodium hydroxide... 

A triple effect evaporator is designed to reduce water from an incoming brine (NaCl + H2O) stream from 25 wt % to 3 wt %. If the evaporator unit is to produce 14,670 lb/hr of NaCl (along with 3 wt % H2O), determine ... 

To obtain essentially equal temperature-differences over the triple effect evaporator, operate the first evaporator at 10 atm, the second at 5 atm, and the third at 2 atm. (The latter choice was... 

Fig. 3. Triple-effect evaporator. Cp Cjp Cjjj, condensate valnes Fp Fjj, Fjjj, feed valves J, Air Injector and Condenser P and T, pressnre and temperatnre for each effect.

Sludge is concentrated in a triple-effect evaporator to recover vitamin The first effect operates at 8 psig, whereas the last effect operates at a temperature of 110°F. If the overall heat transfer coefficients are 400, 320, and 240 for the first, second, and third effects, respectively, estimate the liquor boiling temperature in each stage. Neglect any boiling point elevation. 

A 50% NaCl solution is to be concentrated in a triple-effect evaporator as shown in Fig. P2.76. (Each individual evaporator is termed an effect.) An equal amount of water is evaporated in each effect. Determine the composition of the outlet stream from effect 2 if the internal contents of effect 2 are uniformly mixed so that the outlet stream has the same composition as the internal contents of effect 2. The steam lines in each effect are completely separate from the evaporator contents so that no mixing of the steam with the contents occurs. 

Glucose.—One bushel of corn will give about 14 gal. of liquor, and the first concentration is done in a triple-effect evaporator from 15 to 30°B6. with from 5 to 10 lb. of exhaust steam pressure and a vacuum of from 27 to 28 in. The capacity is from 2 i to 3 gal. per square foot. Usually the standard and the horizontal-type evaporators are used also the semi-film. The latter has the advantage that it will prevent foaming and facilitate cleaning. The second concentration from 30 to from 44 to 45°B. is done in a single-effect of the standard or horizontal type. The capacity is from % to. 1 gal. per square foot, and the horizontal type must be of special construction so as to leave sufficient space between the tubes for the discharge of the heavy syrup. On account of the calcium sulphate in the weak liquor, the tubes in the multiple effect will foul very rapidly, and have to be cleaned either chemically or mechanically. The liquors are apt to foam, and special precautions in the form of extra vapor space and separators are to be taken. Evaporators are usually built with cast-iron shells and copper tubes. 

Glue.—Hide-glue is usually concentrated from 2 to 15 per cent solids, and bone glue from 3 to 20 per cent in a horizontal-tube or rapid-circulation type double or triple effect evaporator. The capacity is from 2 to 2 gal. per square foot with a steam pressure of 5 lb. and a vacuum of 27 in. Evaporators are built of cast iron with copper or brass tubes. 

---