A waste heat evaporator uses low-grade water vapor that normally would be wasted as the heat source for the evaporator system. In the starch industry there are dryers for fiber, gluten, and germ, In the ethanol industry there are dryers for DDGS, In the dryer exhaust gas, the ratio of water vapor to air is high enough that a meaningful amount of water vapor can be used as a replacement for steam in the evaporator. Also, during the saccharification process when starch is converted into glucose, low-pressure water vapor is generated. This water vapor can also be the heat source in a multiple effect evaporator operating under vacuum.

The evaporator can be designed to use multiple sources of waste heat in one system. The waste heat can be supplemented with steam to increase the capacity. The dryer exhaust gas that passes through the evaporator and is vented to atmosphere will have considerably less dust and VOC than the original dryer gas. A scrubber can be integrated with the system to reduce SO2 emissions.

• 
• 
• 
• 
  
• 
  

Evaporation	200kg/h	500kg/h	1000kg/h	2000kg/h	3000kg/h	4000kg/h	5000kg/h	10000kg/h
L*W*Hmm	2000*1200*2200	2500*1500*2500	3000*1800*5200	3300*2400*7800	3500*2600*7800	4500*2800*10000	4500*3000*10000	6500*3800*10000
area	Heater	weight/kg	Separator	weight/kg	Preheater	weight/kg	Crystallization tank	weight/kg
5m²	Φ273*2400	170	Φ400*700	40	Φ		Φ500*1800	120
10	Φ450*1725	330	Φ600*1800	120	Φ		Φ700*2000	180
15	Φ550*1775	460	Φ700*1800	170	Φ		Φ800*2200	230
20	Φ550*2275	560	Φ800*1900	220	Φ		Φ900*2300	290
30	Φ650*2326	800	Φ900*2000	280	Φ		Φ900*2600	340
40	Φ750*2276	1040	Φ900*2450	320	Φ		Φ1000*3000	400
50	Φ700*3750	1240	Φ1000*2450	390	Φ		Φ1100*3000	450
60	Φ750*3776	1430	Φ1100*2450	480	Φ		Φ1200*3200	510
70	Φ800*4200	1450	Φ1100*2750	540	Φ		Φ1300*3200	580
80	Φ750*5176	1750	Φ1200*3000	600	Φ		Φ1300*3300	650
90	Φ550*7075	2000	Φ1200*3300	650	Φ		Φ1400*3500	730
100	Φ700*7200	2300	Φ1200*3600	720	Φ		Φ1500*3700	800
110	Φ750*7176	2540	Φ1300*3650	800	Φ		Φ1500*3800	850
120	Φ780*7176	2750	Φ1300*3850	870	Φ		Φ1600*3800	910
130	Φ800*7200	2990	Φ1400*3900	940	Φ		Φ1600*3900	960
140	Φ820*7226	3220	Φ1400*4100	1000	Φ		Φ1700*3900	1010
150	Φ850*7226	3450	Φ1500*4150	1075	Φ		Φ1700*4000	1060
160	Φ880*7226	3680	Φ1500*4350	1150	Φ		Φ1700*4100	1100
170	Φ880*7226	3850	Φ1600*4200	1230	Φ		Φ1800*4100	1150
180	Φ900*7250	4140	Φ1600*4400	1280	Φ		Φ1800*4200	1200
190	Φ920*7250	4350	Φ1700*4600	1360	Φ		Φ1800*4300	1240
200	Φ950*7300	4540	Φ1800*4900	1440	Φ		Φ1800*4500	1280