| Author | Raveendran, Kandasamy |
| Call Number | AIT Thesis no. ET-02-21 |
| Subject(s) | Tea trade--Energy conservation
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering. School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ET-02-21 |
| Abstract | Tea is the number one foreign earner in Sri Lanka and is produced in 635 factories (as
in March, 2002). The industry consumes the highest amount of electricity and fuel wood
among the industries in Sri Lanka. Electricity demand in Sri Lanka is steadily increasing
and thermal power is used to meet the increased demand. Withering is the first process in
tea manufacture. It consumes about 42% of the total energy for tea manufacture. Therefore,
the main objective of the research was to study the energy saving opportunities in the
withering process. To achieve this objective, first the influence of process parameters was
studied. Two energy saving options in the withering process, the application of variable
speed drive system in the withering unit and silica gel air dehumidification system using
solar energy has been studied.
Experimental studies on a pilot scale conventional withering unit were conducted to study
the influence of various process parameters such as dry bulb temperature of inlet withering
air, airflow rate and loading rate of leaves on energy (electrical and thermal) consumption
and withering time period. Increasing the dry bulb temperature of the withering air help to
reduce the withering time and save electrical energy and thermal energy (total amount of
heat required to raise the temperature reduced for the reduced operating time). Increase in
airflow rate accelerates the withering rate and, thus reduces the withering time and the total
energy consumption. Also the withering airflow rate could be reduced during the latter part
of withering and when the loading rate of leaves is reduced. Reducing the airflow reduces
the total thermal energy consumption.
Energy saving by using variable speed drive system and reduced motor size was studied by
testing different sizes of withering units coupled with this system. A saving of 30 -46%
energy was found to be possible depending on the sizes of the units. If the system could be
implemented in tea industry, the saving estimated was about 15.56 GWh per year.
Moisture adsorption and regeneration rate of commercially available silica gel was tested.
A system for dehumidification of withering air was discussed. The application of solar air
collectors in regenerating the silica gel has been considered. Depending on the solar
radiation, performance of the solar collectors and the available roof area, the number of
withering units to be served by the system was estimated. The airflow to the withering
units is reduced when using this system and the saving in electricity by reducing the
airflow (in a withering unit coupled with the variable speed drive system) was estimated to
vary between 60 to 82 kWh/ day in a typical tea factory.
This study shows that energy saving in withering process is possible by suitably changing
the process parameters and by application of variable speed drive system. The desiccant
dehumidification system further enhances the electricity saving in withering in variable
speed drive system coupled units. |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ET-02-21 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Kumar, S. |
| Examination Committee(s) | Bhattacharya, S.C. ;Mohanty, B. |
| Scholarship Donor(s) | Tea Research Institute of Sri Lanka |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2002 |