Thursday, February 21, 2013

EPA CHALLENGES FOR BAGASSE FIRED POWER STATIONS


By
M.B. INKSON, B.J. MISPLON and E. de VILLIERS 
Thermal Energy Systems
mike.i@sucrose.com

KEYWORDS: Cogeneration,
Environmental Impact, Emissions.

Abstract 

TRADITIONALLY, the sugar industry has been treated leniently with respect to emissions
standards but, as it focuses more on electricity as a profitable by-product, that is changing
even though bagasse is a renewable fuel.
Nowhere is that more the case than at US Sugar’s Clewiston factory in Florida: even
though it is not a major exporter of electricity, when it installed a new boiler, the factory was
obliged to conform with stringent EPA standards.
The challenges imposed by the standards are discussed together with the engineering
solutions and the results obtained.
The outline specification was for a 500 000 lbs/h [~226 800 kg/h] boiler delivering
600 psig, 750ºF [~4137 kPa, ~399°C] steam when firing bagasse.
The main challenges were seen in obtaining the 0.026 lbs/MMBTU [~24 mg/Nm³]
PM10limit and the original 0.12 lbs/MMBTU [~70 ppmvd] NOXlimit without exceeding the
0.38 lbs/MMBTU [~363 ppmvd] CO limit or the 20 ppmvd ammonia slip limit.
Continuous monitoring was required. Engineering was supported by fluid dynamic
studies, in particular with respect to the NOxand CO profiles in the furnace: i) maximum NOx
reduction was required from the urea injection system so location was critical; and ii)
engineering down combustion NOxincreases CO.
In the event, the unit comfortably passed all tests. The variable OFA nozzles which
had been installed proved particularly usefulin tuning the boiler and the low uncontrolled
NOxlevels [meaning there will be reduced urea charges] were pleasing to see.
While these stringent requirements are unlikely to be applied to other bagasse boilers
in the short term, the lessons learned will makeit possible to rise to those challenges when
they arise.

Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010

Saturday, February 9, 2013

IMPROVING PRODUCTIVITY IN SUGAR MILLS BY INTEGRATING CO-PRODUCTS UTILISATION


By
M. ENRÍQUEZ POY1 and R. PRADO2
1Director, Grupo MOTZORONGO
2Coordinador of Periferical Bussines Grupo MOTZORONGO
poymanuel@prodigy.net.mx

KEYWORDS: Productivity, Hydrolysed Bagasse, Compost, Biogas, Invert Rich, Molasses.

Abstract

This paper shows an ‘incentive program’ for workers, through one model of development,
using mainly co-products of sugarcane; used in different ways in ‘Granja Teresita’, 25
kilometres from the mill.
The mill has a plant to hydrolyse bagasse intwo batch reactors by a physical process
(using steam at 1.4 MPa) and areas for composting residuals (90 days, without enzymatic
process), and sell the production to the ranch.
For cattle and goats, we use the cane topswith molasses, hydrolysed bagasse, wet
fibre cane ‘cush – cush’ separated in clarifier filters, and other agriculture residuals of the
region.
For pigs, invert ‘B’ molasses and some locally produced complements are used. For
sustainable agriculture, organic fertiliser (compost), made from sugar mill products (vacuum
filter mud, bagasse, ashes, etc), and worm compost, produced locally, are used with lamb
manure.
A range of crops is grown including cornand sorghum and horticultural crops, and
there is also an aquaculture industry.


Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010 
__________________________________________________________________________

Tuesday, February 5, 2013

COMMUNITIES AUTO SUFFICIENT IN FUELS FOR HUMANS, TRANSPORT AND ELECTRIC NEEDS


By
PETER CHARLES JAIS 
Sugarsoft Ltda
peter@sugarsoft.com.br

KEYWORDS: Sugar, Ethanol, Co-generation.

Abstract

IN VIEW OFthe present problems facing the world withrespect to fossil fuels (pollution and
global warming, availability and price), we studied the possibility of a small community
becoming auto sufficient in sugar, automotive fuel (ethanol) and electricity, all from
renewable biomass (sugarcane).  The study was done, based on a real projectthat we are presently installing under similar lines. The fuel needs of a community of 100 000 people were quantified in terms of sugar,
ethanol, and electricity. A mass and energy balance was calculated to determine the amounts of cane and
trash needed to produce the sugar, ethanol and electricity by generation and co-generation.
The results showed us that 100 tonnes of cane per hour can supply sufficient sugar
and electric energy for a community of 100 000 people and run their cars on 96ºGL ethanol
(no mix with gasoline) and still be able to export surplus ethanol. The auto sufficiency is for the whole yearand not only the crop period. The overall results showed us that, when compared to the importation of ‘fuels’, the project was positive.


Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010
__________________________________________________________________________

Sunday, February 3, 2013

POTASSIUM REMOVAL FROM DISTILLERY SLOPS BY CANDIDA UTILISPROPAGATION


By
M.A. OTERO-RAMBLA, O.A. ALMAZAN-DEL OLMO, DANIEL BELLO-GIL, 
GUSTAVO SAURA-LARIA and JULIO A. MARTINEZ-VALDIVIESO 
Biotechnology Division, Cuban Institute for Research on Sugarcane By-Products (ICIDCA)
Vía Blanca # 804 and Carretera Central, 11000 Havana, Cuba
miguel.otero@icidca.edu.cu

KEYWORDS: Distillery Slops Decontamination,
Single Cell Protein, Feed Protein, Potassium Removal
.
Abstract 

YEASTSaccumulate varied amounts of most of the minerals present in their growth media.
Much of the 7.5–8.1% ash found in the yeast grown for baking or harvested from beer is
potassium phosphate, but yeast has the ability to accumulate other ions provided (but not
necessarily needed) in high concentration. Distillery slops still contain about 70% of all potassium contributed to the soil in cane fields as chemical fertiliser, thus fertigation with these wastewaters has to be carefully
calculated since otherwise soil salinisation can occur.
When grown in a medium composed of distillery slops, nutrient salts (ammonium
phosphate and sulfates) and a microbial growth enhancer Candida utilisshows a great
resistance to potassium concentration in continuous culture.
Yeast cells were propagated under the above conditions with increasing amounts of
K2O from 2.5 g/L concentration (distillery slops from molasses fermentation) up to 25 g/Lin propagation medium. Specific growth rate (µmax) ranged from 0.32 to 0.28 h–1 for the extreme values
mentioned above, while biomass-substrate yield coefficients were 0.23 to 0.18.
These results suggest that yeast propagated on supplemented distillery slops could
significantly reduce the potassium content of these wastes making them more suitable for
irrigation purposes. According to the nutritional assessment reported, the potassium accumulated has no
deleterious effect on animal health.

Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010

COGENERATION POTENTIAL IN COLOMBIAN SUGAR MILLS


By
EDGAR F. CASTILLO M., ADOLFO L. GÓMEZ, 
DIEGO COBO and CARLOS AGUIRRE 
Colombian Sugarcane Research Center CENICAÑA,
Cali, Colombia
efcastillo@cenicana.org

KEYWORDS: Cogeneration, Colombia, Distillation,
Electricity, Ethanol, Steam, Sugar.

Abstract

NOWADAYS, the Colombian sugar industry is involved in an expansion process, mainly
related to the diversification of final products.
In this way, since 2005 five ethanol distilleries are running, covering just 65% of
total ethanol demand. Distilleries were designed coupled with a composting plant, based on
vinasses and sludges from the sugar plant.
Both distilleries and composting plants show many features which make them a
special case in the ethanol market, so theyproduce a maximum of 3 L vinasse/L ethanol.
Besides, in all cases, the thermal and electrical power requirements at the ethanol
plant are supplied by the sugar plant.
In this paper, a brief description of technological features of the typical process
configuration followed by the Colombian sugar industry is shown.
It comprises the steam consumption distribution by sections, the common
configuration of the heat exchanger network (HEN) developed for vegetal steam usage and
the role of the energetic self-sufficiency ofthe factory played by the bagasse quality.
A set of possible scenarios for improving energy efficiency in a selected mill which
comprises a modified HEN can be formulated, including a revamping of existing boiler and
finally a new boiler operating at higher pressure.
Based on the previous information, the state of the main Colombian cogeneration
projects based on sugar cane and its potential impact on national energy supply is shown.
Finally, the paper describes how Colombian governmental requirements for
cogeneration plants are trying to establish a legal framework for this novel industrial activity
in the country.

Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010