Tanica PLC located at Bukoba town near Bukoba port, it involves in the production instant coffee, grinded coffee and Tanica water, the whole factory at a large is facing a problem of air pollution due excess smoke produced by boiler due to filter after they get dust which cause air pollution to the factory and surrounding area. There many activities which going on lie fishing, port, transportation and marketing.


Tanica PLC is been affecting by air pollution due to excess smoke produced by boiler after filter get dust. As boiler uses fuel furnace oil so they need to be filtering during its operation, when filters leave for long period of time they get dust, due to dust they cause boiler to receive little fuel furnace oil for operation or they receive fuel furnace oil with dust. due to contamination of dust in fuel furnace oil or little fuel furnace oil transporting to boiler, due to this factor they cause boiler to start to produce smoke to the boiler and surrounding area at large which cause many problems to the surrounding area like air pollution, air disease and many more.
So this project is focusing on combating the problem of air pollution and air disease by reducing smoke produced to the atmosphere which assumed to be main source of air pollution.


The aim of this project is design circuit for smoke detection with alarm which will alert whenever oil filter in boiler get dust using smoke produced after filter get dust.


This project will be useful to Tanica instant coffee and surrounding area by reducing the problem of air pollution
Increases boiler life span, which minimize possibility of needing major repair
To prevent corrective maintenance
Increases operation efficiency of factory.


According to the existing system the detection of smoke is by observation method in the boiler. Feed water for controlling level of water, oil demand for controlling level of oil, steam temperature control for controlling temperature of boiler. May intention is to add smoke control which will control smoke produced so this project will be more useful in the digital technology.


In the boiler their out puts like steam and smoke when filters get dust. So smoke detector is placed in the exhaust pipe so that to detect presence of smoke, then signal is sent to the control circuit for interpretation then signal are send to LCD display for visualization of the output and also to the buzzer so that it alert



The system will give out visual display of the output which will increase efficiency of system
Presence of software programming which make the system to function correctly
Immediately filter replacement is conducting.
Increase life span of boiler


This chapter contains information and data that are very influential and supportive to the design of my project. Data collected are through passing some of the boiler using factory and consulting Tanica factory engineer
1. Type of smoke produced by boiler is black smoke
Stainless less steel and plasma-welded both inside and out
Boiler thickness 2.5mm
Water capacity is 30 litre





The purpose of using the LCD was to display the quantity of smoke detected as well as to display the status of the system.
The LCD used was a 16 character by two line display.
The LCD can operate in 4-bit mode or 8-bit mode. The 4-bit mode is selecting due to the advantage of greater economy of I/O pins. Hence pins D0, D1, D2 and D3 connects to ground.
Also, R/W line connects to ground since data is always wrote into the LCD.


LEDs were used for the sole purpose of visual alert. One green LED was set to be lit when there was no significant smoke detected in the environment. In the event that smoke is detected, the green LED was set to go off. Four red were set to be off when there was no smoke detected and to blink in the event smoke is detected in the environment.
A current limiting resistance was required for each of the LED. With a Vcc of 5v, the mcu could give a maximum of 5v while the LED needs 20mA in order to light and a forward voltage of 1.8-
3.3V. From Ohm‟s Law, R=V/I.
In order to ensure the current sourced is as little as possible, 220Ω resistor was chosen for current limiting, such that the maximum current sourced became;


A pin type electromagnetic buzzer was selected due to its ease in mounting to printed circuit board as well as the sound output frequency of 2048Hz which is audible to most people. Its operating voltage was 3-6v and a maximum current of 60mA.
The buzzer is set off when there is no significant amount of smoke detecting in the environment and is activating when smoke is detecting.
It is selecting to pin PB0 of the microcontroller.


The MQ2 sensor module is electing to serve the purpose of sensing smoke. It has the capability of sensing smoke and other combustible gases. The following are the reasons as to why selection is:
i. Wide detecting scope
ii. Fast response & high sensitivity
iii. Stable and long life
iv. Simple drive circuit
The sensor can detect smoke in the range of 300-10,000 ppm, giving an analog output voltage of between 0v to 5v depending on the quantity of smoke detected.
The sensitive material used is SnO2, whose conductivity is lower in clean air. Its conductivity increases as the concentration of combustible gases increases, hence generating a corresponding analog voltage at the output.

The Arduino Uno is a microcontroller board based on the ATmega328. Arduino is an open-source, prototyping platform and its simplicity makes it ideal for hobbyists to use as well as professionals. The Arduino Uno have 14 digital input/output pins, of which 6 is using as PWM outputs. 6 analog inputs a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller simply connect it to a computer with a USB cable. power it with a AC-to-DC adapter or battery to get starting.


Selection of a suitable transformer was based on the following factors:
The load to drive requires the current(1A).
The input voltage to the 7805 IC should be at least 2V greater than the required 5V output, hence it requires an input voltage of at least 7V.
Hence the chosen transformer was a 9-0-9 transformer with current rating of 1A (Since 9*√2 = 12.73V).
Rectifying circuit
The best is using a full wave rectifier, it’s advantage being that DC saturation is less as both cycles conduct.
1N4007 diodes are used as it’s capable of withstanding a higher reverse voltage of 1000v whereas 1N4001 is 50V.


The main objective of this project has been to design a circuit that detects smoke and consequently triggers an alarm.
As the smoke detected in the environment varied, the LCD displayed the quantity constantly in particles per million (ppm). With the smoke below the preset critical value, the green LED was on and the red LEDs were off and the LCD displayed „STANDBY MODE‟. With the smoke detected above the preset critical value, the green LED was off while the red LEDs were flashing and the LCD displayed “SMOKE DETECTED‟.
This system can be of great in industrial settings to detect smoke and alert technician. so that immediately action should be taken to minimize air pollution and increase life span of boiler, instead of relying visualization of smoke which action are taken while effects of smoke are already made. The cost of implementing this system is relatively low since the components used are relatively cheap and are easily available in the market. The single microcontroller uses to interface several sensors with alarms located in different locations as long as more pins are freed for multiple inputs multiple outputs. This system comes with a power supply that is directly plugging in to the mains (240V AC) source and give the appropriate operating voltage.


Human safety and machine is a very crucial aspect in industrial setting.
This system should placed in a cool and dry place in order to ensure a longer life span. It is placing in a high place in the room and in the direction of the window where there is most likely to be the direction of the wind to facilitate the contact of the sensor with the smoke. The visual alarms is positioning in a control body where is easily visible. The audio alarm is positioning is in a place that its alarm can be easily sound also in control body of boiler.
Lastly, the method of relaying the alarm remotely has not explored in this project due to time constraint and cost. GSM and GPS modules is employing in this case to automatically send a message to a control room to notify operator on the presence of smoke and the exact location of smoke.

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