In this anaylsis water content will not be removed which provides a measure Oxygen as O2 = 0.2 : 11.5 = 1.7% .here the Oxygen contents to the volume of dry flu gases is 11.5 m3 with excess of air ?=1.1
In the analysis of the flue gas Electrochemical sensors will be used . these sensors require dry gas to measure its composition there for dry basis in the analysis is used to measure the composition of the flue gas generated by the boiler. International units will be considered in taking the measurements , hence the gas concentration will be measured in the means of PPm (parts per millions).Pollutants in the emissions can also be measured in terms of mg/Nm3 (milligrams per cubic meter).But since we need to address the factor of efficiency of the boiler mg/Kwh will also be considered. Thereby a through this energy related unit a wide understanding about the efficiency of the boiler can be obtained. This converstion can be directly obtained as follow,
Value in Mg/Kwh= value in ppm *1074 (.M, 1998).
One of the key Priorities of flue gas analysis is run the boiler a Energy saving manner.It is required by the requaltions to measure for efficiency of all the heat generating boilers.the Efficency of the boiler is measured as follow (ToolBox, 2003),
Boiler Efficiency related to the boilers energy output to the boilers energy input can be expressed as:
• Boiler efficiency (%) = 100 (heat exported by the fluid (water, steam ..) / heat provided by the fuel)
This is also recognized as the ratio between the “Useful output” and the “Gross heat input”. For a Boiler operating at an ideal condition it is considered that 1Kcal is the heat quantity required to grow the temperature of 1 Liter of water by 1celcious. But this amount varies in the practical applications. In automation of the boiler the objective is to change the variable parameters in the boiler to bring close to this ideal condition.
Combustion efficiency in relation to the emission of the flue gas is measured as follow (Hajari, 2017),
• Efficency = 100-Qs Stack Flue loss
• Qs = k * (Tg – Ta) / CO2
Qs- Stack Flue Loss
K- Factor related to fuel
Tg -Flue Gas Temperature
Ta -Supplied Combustion Air Temperature
CO2 -% of Carbon Dioxide
It is to be noted that certain regulations need to be followed to make sure that the operation of the boiler is conducted in an environmental friendly, safe manner while it is operating at the optimum efficiency (Rogers, 2008). They are ,
A. NFPA 85 Boiler and Combustion Control Systems Hazards code.
B. API 556 Instrumentation and Controls for Fire Heaters and Steam Generators
C. AS 3814 Industrial and Commercial Gas-Fired Appliances
D. AS 61508 /AS 61511 Standard for Safety Instrumented Systems.
Compliance to these regulations will make sure the boiler is function according to the laid down rules and regulations.
In order to perform the flue gas analysis following steps are expected to be followed,
1. Boiler has to work under the maximum power in the stable condition for a desired period of time.
2. Probe is to be inserted in to the tube of the boiler at a height which is 2 times the diameter.
3. If a Type C boiler is in use remote combustion air probe is to be inserted.
4. Perform the draft Measurement
5. Obtain the correct factor for the calculations
6. Perform the flue gas Analysis.
Importance of the boiler featured in this article is that the above mentioned process will be conducted automatically without any involvement of a human. In this manner it is expected to avoid errors caused due to human mistakes .This will provide information to the Control system to function without any errors. But it is expected to run periodic maintenance on the measuring equipment to make sure the reading taken are without errors.
Inorder to have a clear idea about the condition of the flue gas following types of sensors are to used. These sensors will be connected to the exhaust of the boiler. The type of sensors which will be used are,
1. CO2 Sensor
2. O2 Sensor
3. Ph Sensor
4. Humidity Sensor
The output signal generated by these sensors is a physical quantity thereby to convert this to useful form Analog to digital converter will be used. Through ADC sensors will be connected to the microcontroller. Where the collected data from the sensors will be used to automate the boiler. Continuous Monitoring of the collected data will occur through the microcontroller since the accumulated data is stored in the microcontroller’s memory. It is expected to collect data from the boiler for a time period of 2 weeks where the condition of the flue gas is recognized when the boiler is running at its optimum level. By using this data various threshold levels will be assigned for each sensor. If the data acquired by any of the sensor exceeds or goes below its preset threshold level which is setup according to the boiler specification to obtain efficiency of the boiler, it will be indicated automictically to the maintenance technicians through a display device(HMI) of PC in work place or through Web base application to the supervisors and engineers to their smart phone to monitor boiler condition and to make correct decision. It is expected to automate the boiler to make the corrective measures by itself by using the training data. Thereby the boiler will always be running under the optimum conditions.