Student: GRIFFITH SCHOOL OF ENGINEERING 4201ENG / 7401ENG AIR QUALITY MONITORING AND CONTROL Assignment 1 ( weighting 20%) Air Pollution Monitoring According to local requirements, a particulate emission from a circular stack with the diameter of _____m has to be annually monitored. Your company has been commissioned to perform the test according to procedures recommended by Queensland Environmental Protection Agency: Gas velocity in the stack: Victorian EPA Method B4. Location of traverse points in circular stack: USEPA Method 1. Temperature of gas: BS 1041 Part 4 “ Guide to selection and use of thermocouples”. Water vapour concentration: USEPA Method 4. Particulates concentration: USEPA Method 5 (AS 4323.2, 1995). According to this method sampling has to be isokinetic (Fig.1). The isokinetic sampling is a procedure to ensure that a representative sample of an aerosol enters the inlet of a sampling tube when sampling from a moving aerosol stream. Sampling is isokinetic when the inlet of the sampler is aligned parallel to the gas streamlines and the gas velocity (U) entering the probe is identical to the free stream velocity approaching the inlet (U0). If sampling is isokinetic there is no particle loss at the inlet regardless of particle size or inertia. Isokinetic sampling in no way ensures that the concentration and size distribution of the aerosol entering the tube is the same as that in the flowing stream. The sampling train has to be assembled according to the US EPA Method 5 requirements. The sampling probe is attached to a filter assembly containing an ultrapure quartz microfibre filter. The filter assembly is attached to four impingers, the first two of which contain water, the next is empty and the last contains silica gel. The impingers are submerged into the ice-bath and attached to the vacuum pump. All calculations have to be made according to the USEPA Method 5 requirements (AS 4323.2, 1995). The following parameters were obtained: 1. Stack diameters downstream from flow disturbance - ______ 2. Stack diameters upstream from flow disturbance - ______ 3. Number and location of traverse points ( to be estimated according to Table 1, page 3) 4. Average temperature - _______ °C 5. Dew point - _______ °C 6. CO2 concentration - _______ %v/v 7. Velocity pressure at traverse points (Pa) 8. Static pressure was 761 mm Hg 9. Sampling time was ______ minutes per each traverse point. 10. Filter weight before the procedure - _______ mg 11. Filter weight after the procedure - ________ mg Parameters to be calculated: 1. Moisture content (kg/kg) and molecular weight (as additive) of the gas carrier 2. Gas carrier velocity (according to Eq.1) and flowrate 3. Sampling flowrate to ensure isokinetic conditions for the nozzle with 4 mm diameter 4. Total sample volume in normal cubic meters 5. Concentration of particles per normal cubic meter of exhaust gas Results Filter before Filter after Difference Sample Volume Stack gas velocity, Aver. stack temp, Dew Point Temperat. Velocity Pres. Molec. Weight Moisture Particulate Loading g g g Nm3* m/s °C °C kPa kg/kg dry air g/Nm3 *Nm3 – normalised cubic meter (at 25°C and 101.3 kPa) Structure of the Assignment report: 1. Introduction ( description of the monitoring method ). 2. Main chapter ( calculations and Results table ). 3. Conclusions and recommendations. 4. List of references. TABLE 1. LOCATION OF TRAVERSE POINTS IN CIRCULAR STACKES Traverse Point number on a diameter Number of traverse points on a diameter 2 4 6 8 10 12 14 16 18 20 22 24 1 14.6 6.7 4.4 3.2 2.6 2.1 1.8 1.6 1.4 1.3 1.2 1.1 2 85.4 25 14.6 10.5 8.2 6.7 5.7 4.9 4.4 3.9 3.5 3.2 3 75 29.6 19.4 14.6 11.8 9.9 8.5 7.5 6.7 6 5.5 4 93.3 70.4 32.3 22.6 17.7 14.6 12.5 10.9 9.7 8.7 7.9 5 85.4 67.7 34.2 25 20.1 16.9 14.6 12.9 11.6 10.5 6 95.6 80.6 65.8 35.6 26.9 22 18.8 16.5 14.6 13.2 7 89.5 77.4 64.4 36.6 26.3 23.6 20.4 18 16.1 8 96.8 85.4 75 63.4 37.5 29.6 25 21.5 19.4 9 91.6 82.3 73.1 62.5 38.2 30.6 26.2 23 10 97.4 88.2 79.9 71.7 61.8 38.8 31.5 27.2 11 93.3 85.4 78 70.4 61.2 39.3 32.3 12 97.9 90.1 83.1 76.4 69.4 60.7 39.8 13 94.3 87.5 81.2 75 68.5 60.2 14 98.2 91.5 85.4 79.6 73.8 67.7 15 95.1 89.1 83.5 78.2 72.8 16 96.4 92.5 87.1 82 77 17 95.6 90.3 85.4 80.6 18 98.6 93.3 88.4 83 19 95.1 91.3 86.8 20 96.9 94 89.5 21 95.5 92.1 22 96.9 94.5 23 96.8 24 98.9 (Percent of stack diameter from inside wall to traverse point) Diagram 1. Velocity of the air (1) Kp = 34.97 Cp = 0.99 Tgas (K) – (see item 4, p.1) Pp – mm H2O (see item 7, p.1) Pstat – mm Hg (see item 8, p.1) Mgas – g/gmol