Biorefineries using crops for production of ethanol, biogas and chemicals - Biomass as Energy Source: Resources, Systems and Applications - page 153

In Tianguan Group resource consumption indicators, the unit comprehensive energy consump-
tion of main products shows a continuously downward trend, among which, the fuel ethanol
comprehensive energy consumption was reduced from 0.58 tonnes standard coal/unit production
in 2006 to 0.38 tonnes standard coal/unit production in 2009. The DDGS feed comprehensive
energy consumption was reduced from 1.11 tonnes standard coal/unit production in 2006 to 0.4
tonnes standard coal/unit production in 2009, and the wheat gluten for comprehensive consump-
tion declined from 0.57 tonnes standard coal/unit production in 2006 to 0.36 tonnes standard
coal/unit production in 2009. The unit comprehensive water consumption of main productions
shows a downward trend except wheat gluten flour, among which, the fuel ethanol reduced from
5.39 tonnes/unit production in 2006 to 3.74 tonnes standard coals/unit production in 2009. The
DDGS feed comprehensive water consumption declined from 3.09 tonnes standard coal/unit
production to 1.9 tonnes standard coal/unit production in 2009.
Among Tianguan Group resource comprehensive utilization indicators, there are three indi-
cators such as the comprehensive utilization rate of industrial solid waste, sewage centralized
treatment rate and harmless garbage treatment rate are always maintained at 100%. In addition,
the industrial water recycling utilization rate and industrial wastewater regeneration rate and some
other indicators maintain an increasing trend. Industrial water recycling rate rose from 92.8% in
2006 to 95.4% in 2009, while the industrial wastewater-recycling rate rose from 17% in 2006 to
35% in 2009.
Although Tianguan Group's four major indicators meet the need of the recycling economy,
however, there is still a certain distance against the level of overseas developed countries. The
main difference is as follows:

• The high-temperature liquefaction time of foreign production devices is short (104 ◦ C, 6 min or

so) and there is a vacuum flash cooling, while the spray liquefaction temperature of Tianguan
Group's production devices is lower (95-100 ◦ C), and there is no pre-liquefaction and post-
liquefaction process. The further development trend abroad is adopting high-quality composite
liquid enzymes to cancel the direct injection liquefaction steps, and good liquefaction results
can be achieved even at 85 ◦ C. Therefore, the cost is significantly reduced whether in terms of
equipment investment or consumption.

• The majority of foreign companies have canceled the saccharification process, and directly

perform saccharification and fermentation at the same time, which can effectively solve the
excessive growth of yeast caused by excessive nutrients, and meanwhile, the ethanol generated
by the large amount of sugar consumption influenced the feedback suppression caused by
yeast metabolism. However, Tianguan Group's devices all maintain an independent process of
saccharification.

• Most of the foreign devices adopt continuous thick mash fermentation, and the yeast can be

reused 2-3 times, significantly reducing production costs, while Tianguan group mostly used
semi-continuous thick mash fermentation, instead of yeast recycling technology. The above are
all factors that affect parts o f Tianguan Group indicators and are the main reasons for the gap
between Tianguan Group and overseas developed countries.

9.5 ENERGY FLOWANALYSIS

The energy that Tianguan Group mainly uses is coal, which equals to standard coal at 37 t/h, about
740.9MJ per hour. The ultimate effective energy that can be used is about 419.28MJ (the amount
of materials 277.08MJ, power 81 MJ and refrigeration work 54.2MJ), which accounts for 56.6%
of the total efficiency of the energy used by whole plant.
As to the company's heat losses, process emissions, boiler flue gas emissions and condensate
heat loss are the major ones, but it is materials that carry the most heat. For the utilization of the
steam, the production process, which uses most energy, is ethanol and feed production.
The specific energy flow analysis is shown in Figure 9.3.