Power generation from Waste Wind Energy

Career Episode

Your Full Name: Mohammad Bahalul AlamYour Date of Birth: 12/06/1981Your Email: Mohammad.bahalul@gmailcomYour Address:Your Phone No:

A. Introduction:

CE 2.1: This career episode is based on the project of designing, installation and commissioning of a windmill in the Dhaka Factory of British American Tobacco Bangladesh Company Limited. The duration of the project was from 15th February to 29 th February, 2012.The Dhaka Factory of BATB is situated at Mohakhali DOHS, Dhaka. I joined BATB on 15th December, 2009 as Manufacturing Services Engineer.

B. Background:

CE 2.2: Engineering project background:

British American Tobacco Bangladesh Company Limited has only one cigarette manufacturing factory in Dhaka. The average capacity of the factory is 100 million stick per day. The primary manufacturing department (PMD) and the secondary manufacturing department (SMD) produce an average 2800 KG tobacco dust per day. The factory collects this amount of dust through Dust Recovery Facilities (DRF). There are three DRF employed for SMD and two of them are always running where one is standby for maintenance purpose. Each DRF has a large blower fan, driven by 132 KW motor having capacity of 46,200 m3/hr. These fans suck the dust from the cigarette manufacturing machines through a group of dust filters and exhaust the dust free air to the atmosphere. The flow rate of the air on the exhaust is too high and I thought that it could be used for power generation.

Project objectives:

The objective of the project was to generate power by harnessing the exhaust air of DRF. This is an initiative to use unnatural wind sources for electricity generation. The project was taken by me as pilot basis and planned to supply electricity for the DRF room.

CE 2.3: My duties and responsibilities in this project:

The idea of the project was first introduced by me. I shared my idea and implementation plan to my line manager and the head of department. They gave approval to implement it as early as possible. Then I planned it by myself, designed the whole system and implemented it with the help of contractor’s people. The whole project was led by me and I was the project manager of the project.

The organizational structure for the particular project was as follows:

C. Personal Engineering Activities:

CE 2.4: Reason of project initiating:

Power is a very essential thing for modern era. But the affect of producing power is not negligible. Power plants generate fly ash, CO2, CO, SOx, NOx, radiation which are not environment friendly. Moreover the carbon emission increases the temperature of earth. Furthermore energy is not limitless. So for the next generation we have to preserve energy and ensure a good environment. From this point of view I always prefer renewable energy and I took an initiative in Dhaka Factory. I introduced solar panel for lighting system; recycle process water for cooling tower makeup water, using ETP water for gardening and toilet flushing etc. But it is not suitable to install a wind turbine to extract wind energy because the wind speed is low throughout the year (free stream wind speed, V < 4 m/s) in the factory. In this case electricity can be generated from unnatural wind resources by harnessing wind energy. As there are many exhaust air systems in my factory, I prepared a plan to generate power from the exhaust air as an energy saving initiative.

CE 2.5: Visiting similar project / review previous similar work:

In Bangladesh some factories are now installing solar power system, but the wind power generation is still rare. Though Government took some initiative to install large windmills on the costal areas, these are not applicable in low air velocity areas like our factory premises. So I had no opportunity to visit similar power plant or review previous similar work. But I got some idea from internet. Furthermore as I worked in a power plant before I had a clear idea about power generation. I know the alternator needs a rotational energy to cut flux in its armature to generate power and I used the exhaust air to rotate a fan or turbine to transfer rotational energy to the armature shaft. I started the job with this basic idea.

Technical Services Manager

Manufacturing Services Manager

Manufacturing Services Engineer (My Position)

Electrical Contractor

Mechanical Contractor

CE 2.6: Project proposal submission, tendering or meeting with higher authority:

When I decided to do that, I shared my plan to my line manager and the head of department. They appreciated my plan and showed keen interest in my project. They wanted to know all of the project related information minutely and gave me a go ahead to complete the project in quickest possible time. Then I selected an electrical contractor and a mechanical contractor who is experienced to manufacture fan for the project. At first I gave them a clear overview of my project in a meeting.

CE 2.7: Project scheduling, tendering, etc.

I planned to use all of the resources and materials from local market. I made a list of my requirements as follows:

A mild steel square bend with both end flung A mild steel reducer from square to round with both end flung A mild steel shaft with key arrangement The fan blade arrangement Two numbers of pulleys Two number of V belts Guards of the pulley and the belts Blower guards Nut bolts A 3 KW AC alternator Cover for the alternator Wires of different specifications Magnetic contactors and the circuit breakers with a box A voltage stabilizer etc.

I asked my contractors to submit a quotation of the above materials with their making and labor charges. When I got the quotations, I called for procurement and finance personnel in the negotiation meeting and signed off the quotations. Then the Purchase order was raised and the contractors started working.

CE 2.8: Technical Details of the Work:

At first I select a three KW single phase AC generator. The specification of the generator and other electrical equipments as below:

Sl. No. Description Unit Value1 Generator Power Watt 30002 Generator Voltage V 2203 Generator Current A 13.64 Generator Frequency Hz 505 Generator shaft Speed rpm 15006 Generator Phase Single7 Voltage stabilizer (output 220V) Watt 40008 Wire (4rm X 2 core) feet 3009 Magnetic contactor (16 A) pcs 210 Circuit Breaker (16 A) pcs 211

By considering total lighting load (2500 watt) in DRF room, I estimated the above electrical equipments.For wire selection I took a wire manufacturer (BRB Cables) guide and choose wires by adding 20% more amperes over the rated current as a safety factor. For example: I choose 2 X 4 rm NYY wire for transferring power from generator to load.2 X 4 means 2 no of wire having the nominal cross sectional area of conductor of 4 mm &rm means the conductor of multiple stranded wires of circular cross section

NYY means PVC insulated and PVC sheathed cablesStandard BDS-901 and VDE-0271/3.69Voltage rating: 600/1000 voltsCurrent rating: Under ground at 30 deg C: 40 A

In the air at 35 deg C: 35 A

I designed the wire for 2500 watt lighting load.P = VI

=> 2500 = 220*I => I = 2500/220 => I = 11.36 ampThe designed wire took 35 amps. So I had also option to distribute more power for other rooms.

Then according to the generator, I choose the following materials.

Sl. No.

Description Specification Unit Qty.

1 Bearing Block 160mm X 160mm Pcs 22 Bearing number UC 206 Pcs 23 Fan hub dia 240 mm4 Fan dia (center to blade tip) 820 mm5 Fan blade( Base width X Tip width

X Length)75m X 100m X 290m; 35 deg base to 0 deg tip

Pcs 11

6 Fan pulley (Dia X Width) 9” X 32mm Pcs 17 Generator pulley (Dia X Width) 3” X 32mm Pcs 18 V-belt B 80 Pcs 29 Shaft (dia X length) 32mm X 2 feet Pcs 110 Key(t X w X l) 5mm X 10mm X 100mm Pcs 111 90deg square bends 1000mm X 1000mm, 1150mm high Pcs 112 Reducer (square to round) 1000mm sq X 845mm dia X 620mm slope and

845 mm dia X 220mm length of round ductPcs 1

13 Angle 2” X 2” X 5 mm Pcs14 Nut bolt 12 mm, 50mm L pcs 6415 Fan material Aluminium16 Fan type Axial Flow

CE 2.9: Design and planning for the project:

The air exhausted in the DRF was vertically. At first I calculated its velocity.

According to my plan, I decided to flow the air horizontally for the ease of maintenance of fan or turbine unit. Then a horizontal axis wind turbine (HAWT) with an enclosure is mounted at the end DRF exhaust

Flow ,m³ / min60 Pipe Cross Section Area, m²

Velocity, m / s

462003600 × (1 × 1)

12.83 m/s

fan to harness the wind energy for producing electricity. The reducer and an enclosure are attached at the end of the bend so that there will be venture effect i.e. the blade can get more air with comparatively higher velocity. I again calculated the velocity after attaching the enclosure and got 22 m / s. But practically I got the velocity was 19 m/s on an average. The fan was designed so that I could get the full advantages of this velocity and air flow. The blade angle was kept 35 degree at fan hub and it became gradually 0 degree up to the tip. The fan was made by casting the aluminium to reduce its weight. The shaft was two feet long and diameter was 32 mm. According to the shaft diameter the bearing and the bearing housing were selected. For pulley selection at first we made a 9 inches diameter pulley for fan or turbine and the RPM of the fan / turbine was measured to around 526 by a tachometer. Thus we got the generator pulley should be 3 inches diameter by the following:

D1/D2 = RPM2/RPM1

Where D1 : Diameter of generator pulleyD2 : Diameter of generator pulleyRPM1 : Revolution per minute of generator.RPM2 : Revolution per minute of fan blower.

Fig: Pictorial depiction of the arrangement when the project is going on

Though the generator had the capacity of 3 KW, I planned to connect 1 KW load at first. By considering this I selected 2 X 4 rm wire for the output of the generator. I wanted to employ a voltage stabilizer for a stable voltage at the load end in case of speed variation of the fan. I also planned for an auto change over arrangement from generator to PDB (Govt. owned power) or PDB to generator. It assists me that if generator power is not available then it switches to PDB and when generator power is available it switches back to generator automatically.

Alternator

90 deg Bend Enclosur

Pulley

Fan blower

Bearing Housing

V-belt

CE 2.10: Project supervision / implementation and commissioning:

Before the project, the air was exhausted to atmosphere vertically and a hinge type triangular door was attached at the exhaust duct end to protect the inside of the duct from rain water. I asked the mechanical contractor to attach a 90 degree bend so that the air flows horizontally. Then I suggested attaching a reducer (square to round) at the open end of the square bend. I attached the fan blade (HAWT) assembly with an enclosure at the opening of the reducer. The fan shaft was then connected to the alternator shaft through pulleys and then 2 V-belts were connected. When the fan blower ran we saw the voltage was generated at alternator end but it was fluctuating from 160 to 240 volts. So I connected the output of the generator on a voltage stabilizer where I got 205 +/- 10 volts. Then I connected the stabilizer output to the load. At first we light around 800 watt lighting load in the DRF room. The loads were energy saving light. I also compared the before and after scenario of the DRF motor when it is connected with load or not and I got the same ampere reading for both cases.

CE 2.11: Project submission / presentation:

After completion of the project I ran the system for two days with 800 watt load and saw everything was fine. I took the project on experimental basis and now I see that it can be used for some lighting load. My plan is to light the DRF room with this Horizontal Axis Wind Turbine. I also had another six exhaust air sources and this pilot project is just an ignition to install the other HAWT. I presented my project to my top team and they took a visit to my project area. They appreciated it and asked me to try for its continuous improvement.

CE 2.12: Complex Problem Identification and Solution:

Though the DRF motor has constant speed, but sometimes its air flow varied which had an impact on the alternator output voltage. Sometimes the voltage varied from 170 to 280 V. The voltage stabilizer did not have the capacity to operate within this voltage range. If the output voltage of alternator is beyond the range then the voltage stabilizer is cut off. To avoid these difficulties I arranged an automatic transfer system where if the generator output voltage is beyond the range the system will auto transfer to the existing power system (PDB) and when the voltage is back in its operating range it again switches from PDB to generator automatically.

CE 2.13: Project outcome:

I could light 800 watt of lighting load in DRF room through this project. The outcome of the project opens immense potentiality of this type of power generation. In Bangladesh, the generation capacity was always lower than its maximum demand. So we face a lot of load shedding especially in summer. Currently every commercial building in Bangladesh is equipped with HVAC system. This project can be installed on the cooling tower of the HVAC system and a portion of the building lighting system can be possible with it. Furthermore there is a huge potential of this project in the industrial area where the exhaust air source is existed.

Without fan blower With fan blower and enclosure

Current consumption of DRF motor

112 Ampere 112 Ampere

Fan rotation 526 rpm

Cost management:

Total net project cost was BDT 150,000.

Total load connected in this project (In DRF room) was 800 watt.These lighting loads were applicable for 24 hours in the DRF room and DRF is running 350 days in a year. The average rate of Government generated electricity is BDT 6.5 / KWH.

So, total load used in DRF/year = (800/1000)*24*350 = 6624 KWH per yearTotal cost per year = 6624*6.5 = 43,680 BDT.

So payback time of the project = 150,000/43,680 = 3.434 years

So after 3.434 years the project will provide us the electricity without any cost.

CE 2.14: Risk Management

Before this project I calculated the probable risk relating to the project. According to the risk calculation, DRF room is noisy and dusty. So while working in this room people must wear ear plugs and mask. The fan unit (HAWT) and the pulley belt assembly should be guarded otherwise the high speed rotating parts may cause accident. As the alternators were situated on the roof, there should be a cover for it and I ensured the cover & all guards. All the electrical cables should be concealed in wall or in PVC conduit or in the cable tray. All the metal structures like fan assembly and the breaker box should be properly earthed. I did the job when my contractors and I got some time from other day to day job. So it took some time but no one was bothered. I thanked my team for trying their best to implement my idea in this form. CE 2.15: Occupational Health and Safety Management:

At the time of project job, I closely monitored the safety issues relevant to the work and ensured the following things

All contractors’ people should use Personal Protective Equipments (Safety shoes, mask, safety goggles, helmets, ear plugs hand gloves etc.).

Work Permit for work at height, working with heavy object, electrical work and hot work etc. for the contractors.

Prohibition of the Use of adjustable Spanner (slide-wrench). All portable electrical equipment / tools like hand drill; hand grinding machine etc. must be double

insulated AC. Defective plugs, sockets, cables must not be used under any circumstances. Metal ladders must NOT be used while doing any electrical job. While using ladders one person must be at the bottom of it tightly pressing the feet of the ladder to

the ground. Ensure that main switch, Local Isolators, Main isolating valves of compressed air etc. are in

‘OFF’ position and locked using a multi-locking device before starting of any job on the machine or any energy line.

Any equipment using electrical main supply must have appropriate earthing facility with a 3pin flat plug-socket arrangement covered by ELCB.

All the guards at the fan blade opening and the pulley & V-belt were fitted. A cover for the alternator was made to save it from rain water. All the electrical cables are laid in the PVC pipe or in the cable tray.

D. Summery:

CE 2.16: Summery:

This is the project where I generated my own idea, implemented it and shared it with others. I took the project experimentally and my concern was that DRF motor took more amperes from its original condition. But the positive thing is the alternator did not make any impact on the main fan motor performance. This project helped me to know electrical job well. By this project I learnt to take calculative risk by my own. The main outcome of the project for me is self-reliance. It is a confidence to implement a self generated idea.