Md. Emdadul Haque Bhuiyan Remon, Department of Apparel Engineering (41st Batch), Bangladesh University of Textiles
Shariful Islam Tushar, Department of Apparel Engineering (42ndBatch), Bangladesh University of Textiles
* This paper won the 1st position in “1st Inter University Innovative Research & Idea Competition 2018” organized by Department of Textile Engineering, Dhaka University of Engineering Technology (DUET)
According to Petrobangla, the remaining gas reserve in Bangladesh at present is about 13 Tcf. Due to the increasing gas demand in our country, this reserve would run out within 10 to 12 years next. If the gas production regulated downwards, this would run for some more years. But, what will happen after that?Gas is the main fuel of Boiler. Boiler generates Steam and stream is very important in textiles production. The use of stream is in every important processes in textile manufacturing, such as man made fiber production, dyeing, printing and ironing. Since, Textiles & RMG industries are the basis of our economy, any scarcity of gas directly affects our economy. So, it is high time to think about replacement of fuel of boiler as well as the boiler by any other sources. Renewable energy will be a potential replacement for boiler. Main target of Boiler is to produce steam and here, we use Sunlight instead of natural gas for producing steam. In that case, we want to use Parabolic Dish Concentrator to produce steam by using sunlight.
What is a Boiler?
A boiler is a closed vessel in which water or other fluid is heated. Main function of Boiler is to produce steam from water. Converting water to steam involves in three stages. In the first stage, water is heated to boiling point, in the second stage, water boils at saturation temperature to produce steam and the final stage, heating steam from saturation temperature to higher temperature called super heating to increase the power plant output and efficiency.
Explanation of Problem and Context:
We recognized boiler as the main problems in this context, as it consumes huge amount of natural gas to convert water to required stream. If we ensure required steam for our production purpose without using boiler or replacing it, we can save natural gas.
In this chart, we can easily realize that the demand for gas is increasing day by day in Bangladesh but the production of gas is decreasing simultaneously.
A Parabolic Dish Concentrator is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its physical shape is part of a circular parabolic i.e the surface generated by a parabola revolving around its axis.
The parabolic reflector transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus. Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light). It is used in applications such as solar cooking, where sunlight has to be focused well enough to strike a cooking pot, but not to an exact point.
Explanation of Solution and relevant information:
Generally we use Boiler to produce steam in Textile industries. But we want to use Parabolic Dish Concentrators instead of Boiler.
Here we use Parabolic Dish Concentrators. Each Parabolic Dish Concentrator has a reflective surface area and reflects sunlight on the receivers of the header pipes by special white glass pieces. Steam is collected in the header pipes, which is then directed, used in textile works especially in boiler.
In textiles processing, water is supplied into a boiler to generate stream but in the proposed method, water is supplied in cylindrical pipe. This pipe should contain the receiver where the reflected sun-ray which heat the pipe in order to convert water into stream of required temperature. The receiver earns required power from the Parabolic Dish Concentrators which are mounted both side of the pipe as like above figure.
The Parabolic Dish changes its direction with the change of movement of sun. It’s concentrating reflectors track the movement of the sun, reflecting the light of the sun and concentrating it on a fixed position. The rotating reflector produces a converging beam of sunlight aligned with its axis of rotation which is parallel to the axis of the earth. The rotating reflector turns at a rate of one revolution per day (15 degrees per hour) to keep the reflected beam aligned with the axis of rotation as the sun moves.
Starting of each day, manual adjustment of the Parabolic Dish is necessary with the rise of the sun. Every few days later, the adjustment of angle between the axis of rotation and the concentrating reflector are necessary to accommodate the seasonal variation in the height of the sun. Once the reflected beam is aligned with the axis of rotation of the concentrating reflector and the clockwork is in motion, the reflected beam remains aligned with the axis of rotation all day. With the increase or decrease of parabolic dishes, the definite temperature of the stream is maintained.
Parabolic Dish Concentrator –
Surface area : 9.2 sq. meters
Steam Production : 3500-4000 kg/day
Temperature of Steam : 600-650 degree Celsius
Price for each dish : 75 Euro (may vary)
Steam Production : 3000 kg/hr
Temperature of Steam : 170-190 degree Celsius
Natural gas : 0.072 m /kg
Price for Installment : 3540 Euro (may vary)
Feasibility andImpact Analysis:
1. Boiler maintenance cost is very high in comparison with Parabolic Dish Concentrators.
As for example: Maintenance cost for a small size boiler in a month with its installment cost isBDT15, 58,562 .A recent calculation shows that we can install Parabolic Dish Concentrators with the 8 month’s maintenance cost of Boiler. After that both can serve same period approximately 15 years but later on little amount of maintenance cost required.
2. Boiler uses a lot of natural gas per day. On the contrary,Parabolic Dish Concentrators have no use of natural gas.
A cost & consumption calculation for a small size boiler is given here:
For Small Boiler, we use = 3,368 m3 gas/Day (Average)
Per Month Total gas use for this boiler = (3,368*30) m3 = 101040 m3 (Average)
We know, cost of 1 m3 gas = 7.76 BDT
Per Month Gas Bill for a boiler = (101040*7.76) BDT = 784071 BDT
whereas there is no cost in Parabolic Dish Concentrator about this
3. Boiler is run by electricity, whereas there is no need of electricity in Parabolic Dish Concentrator.
4. Handling boiler bears high danger to the workers who closely involved with it and the environment.It costs human life and huge destruction of natural resources while it accidently exploded. Let take a recent example of boiler accident: a boiler exploded at a garment factory in Bangladesh owned by export-oriented Multifabs Ltd has killed 10 people and injured 50.
But, there is no bad record about Parabolic Dish Concentrators since it is run by sunlight.So,there is no risk to explode.
These are the main feasible points.
Existing Applications of Parabolic Dish Concentrator:
- Shri SaibabaSansthan, Maharashtra:
The solar steam cooking system installed at Shirdi has 40 parabolic concentrators / dishes placed on the terrace of Sai Prasad Building No.2. A parabolic type concentrating solar steam cooking system was commissioned at Shri SaibabaSansthan, Shirdi on 24th May, 2002. This system received financial assistance of 50 % of the total project cost from the Ministry of Non-Conventional Energy Sources, GoI. This is the first of its kind in Maharashtra. It cooks food for about 3000 devotees.
The 40 nos. of solar parabolic concentrators raise the water temperature to 550C to 650C and convert it into steam for cooking purposes. This system is integrated with the existing boiler to ensure continued cooking even at night and during rain or cloudy weather.
Before the installation of the solar cooking system, the steam for cooking at Sansthan was being generated by LPG gas firing in the boiler.
The main goal of the system was to reduce LPG gas consumption by 50 %.
- Tirumala TirupatiDevasthanams (TTD) :
World’s largest solar steam cooking system with 106 Solar Concentrators of 9.4 sqrmtr each installed at Tirumala TirupatiDevasthanams (TTD) to cook for 15,000 persons. The Solar Steam Cooking System at Tirupati temple is the present World’s largest Solar Steam Cooking System using 106 Scheffler Concentrators of 9.4 sqrmtr and the Cooker was inaugurated by the Chief Minister of the State of Andhra Pradesh Shri Chandra Baba Naidu.
- More Examples:
– Rishi Valley School, Madanappaly, Andhra Prades for 500 students
– Sanghi Textiles for their industrial Canteen and many more…
There are some challenges of the installation and use of the parabolic dish concentrators, and installment charges and space. In the primary installment the charge might be an issues as well as the space required. Yet in Bangladesh, there is no use or project relating Parabolic Dish Concentrators. It is high time to consider the use of the concept to save our natural resources, environment and people-a first footstep to sustainability.