Agriculture Reference
In-Depth Information
Chapter 3
E
NERGY
R
ECOVERY FROM
B
Y
-P
RODUCTS
OF
S
UGAR
M
AKING
P
ROCESS
Muhammad Akram
*
University of South Wales (formerly University of Glamorgan), UK
A
BSTRACT
Sugar beet is widely used in the world to manufacture sugar. In the UK 7.5 million
tonnes of sugar beet is processed for sugar production each year. The sugar making
process produces by-products such as vinasse, raffinate and pressed sugar beet pulp.
Vinasse and raffinate are liquids while pressed pulp is a solid by-product. After sugar
extraction, remaining beet is pressed mechanically to remove water which results in
pressed sugar beet pulp having 20 - 24% dry matter. Raffinate and vinasse originate from
the liquid stream after sugar; alcohol and betaine are taken out. All these by-products
have an energy value associated with them which can be recovered by employing a
suitable technology. The most widely used energy recovery technology is thermal
processes also known as combustion. As a result of the high moisture content which is of
the order of 50 - 75%, it may not be possible to combust these materials without the use
of a primary fuel, such as coal, having a high calorific value to compensate for the energy
loss due to the presence of excessive amounts of water. Moreover, it may not be possible
to combust these materials in conventional systems without major modifications or
without penalties.
This chapter discusses potential for energy recovery from beet sugar industry by-
products using fluidized bed combustion technology. Vinasse, raffinate and pressed pulp
were fired/cofired with Thoresby coal in a fluidized bed test rig. The tests were
conducted at different thermal inputs at a wide range of operating conditions. The chapter
also includes discussions on alternative uses of sugar industry by-products.
The work is focused on the combustion of blends of coal and pressed pulp in
different proportions. It was observed that the proportion of pressed pulp in the blended
fuel can be up to 50% for successful energy recovery using fluidized bed technology.
During combustion of different coal-pulp blends it was found that excess air requirement
