In the corn starch processing plant, the bundle dryer generates a large amount of waste heat steam and high-temperature condensed water during the by-product drying process, which are directly discharged into the atmosphere, causing great waste. The corn slurry waste heat evaporator uses the waste heat steam and high-temperature condensed water discharged from the bundle dryer as a heat source. When the workshop operates normally, the waste heat generated fully satisfies the evaporation of dilute corn slurry, achieving zero consumption of steam in the corn slurry evaporation process, greatly reducing the production cost of enterprises, improving market competitiveness, and having high economic and social benefits.

The process flow of waste steam utilization is as follows:

The waste steam from the bundle dryer is collected → washed and purified → enters the waste steam evaporator → the waste steam and air are discharged by the induced draft fan.

The purification treatment of waste steam from the bundle dryer inevitably brings in a small amount of dust. When using waste steam, the dust must be removed. Otherwise, if used for a long time, the evaporator tube wall is easily clogged due to the long-term adhesion of small particles, which affects the heat transfer efficiency.

There are generally three steps for comprehensive treatment of waste steam:

A The shell side of the bundle dryer is sealed and adopts a sealed discharge method to minimize the entry of cold air, thereby increasing the waste steam temperature and reducing the overall investment of the waste heat evaporator;
B The waste steam is subjected to a cyclone dust collector to remove slightly larger dust particles. The cyclone dust collector should provide steam tracing and insulation to prevent condensation of the waste steam;
C The waste steam enters the waste steam washing tower, and the dust in it is sprayed and washed with high-temperature water. After washing, the dust containing wastewater is regularly discharged outside;
D According to customer requirements, the waste heat evaporation system can be integrated with desulfurization equipment for the removal of toxic sulfur dioxide gas emitted from starch production workshops, reducing plant odors, and improving the production environment.

The progressiveness of corn pulp waste heat evaporator lies in:

1. By adopting a unique waste steam washing system, clean secondary steam can be obtained, eliminating the key problems of waste steam dust pollution and blockage of shell side heat exchange tubes;
2. Adopting advanced foreign liquid distribution technology to avoid problems such as dry wall, scaling, and blockage of heat exchange tubes caused by uneven distribution of fabric;
3. The evaporation system uses all the waste heat from the tube bundle machine as a heat source, and the evaporator does not produce any steam at all; The condensed water after flash evaporation can be used for heating the soaking solution, and corn soaking heating does not require steam production except in winter; The condensed water cooled by the soaking process can be used as starch washing water;
4. Waste steam evaporation belongs to low-temperature evaporation with a large circulation volume, which can reduce or avoid scaling of evaporator tubes.

Economic and technical parameters of corn slurry waste heat evaporator
Starch production scale (10000 tons/year)	3	6	12	20	40	60
Water evaporation rate (T/H)	3	6	12	20	40	60
Feed concentration	8-10%
Discharge concentration	40-45%
Circulating cooling water consumption (m3/h)	100	200	400	700	1350	2000
Supporting power (KW)	45	80	120	180	360	480
Total heat exchange area (m2)	800	1600	3000	5000	9500	14000
Investment estimate (10000 yuan)	130	220	400	550	1100	1600
Investment payback period (months)	According to the energy prices of different manufacturers, within about 13 months (calculated at 150 yuan/ton for steam)