Exp 7 Spray Chamber

OVERVIEW

UNIVERSITI KUALA LUMPUR

Malaysian Institute of Chemical & Bioengineering

Technology

ENV 3053

Air Pollution Control Technology

Laboratory Report 6

Spray Chamber System

Date of experiment:

15th September 2006PREPARED BY:

FITRINNAS BIN MOHAMMAD NAZRI

55100204074NORAIN BT MOHD RAMLI

55100204079

SITI NUR BT YUSUF

55100204029

LECTURER: MR. TENGKU FAZLI TENGKU YAHYA1.0 SUMMARYThe Spray Chamber System consists of mainly a spray (separation chamber, a water re-circulation system, a feed container with a valve, an air blower, an outlet dust filter and air flow meter with control valve. Five different spray nozzles have been installed inside the chamber to produce five different droplet sizes. The experiment was performed to determine the effect of droplet size upon separation efficiency of the spray chamber unit by using different nozzle. The largest droplet size has less efficiency and the smallest droplet size has better efficiency.

2.0 INTRODUCTION

The spray chamber has five different spray nozzles that have been installed inside the chamber to produce five different droplet sizes. A mist eliminator at the top section of the chamber prevents water droplets from escaping. The water re-circulation tank consists of a water tank, water pump, liquid flow meters, pressure gauge and regulator. The different droplet sizes are for the separation process of dust. Spray chamber scrubbers consist of empty cylindrical chambers in which the gas stream is contacted with liquid droplets generated by spray nozzles. The resulting spray droplets impact with the particle matters, which are larger than 10m. The bulk of the liquor is separated by gravity and collects in the base of the tower. Mist eliminator is required to prevent excessive carry over of droplets with the clean gas. Spray chamber is a low energy scrubber and has low contacting power so it is not intended for collection of small particulates. The droplets size from the nozzle can be controlled to optimize particle contact. Furthermore, increasing of spray pressure will decreased the droplet size in order to provide more surface area.

3.0 OBJECTIVES

To determine the effect of droplet size upon separation efficiency of the spray chamber unit by using different nozzle

Different nozzles were used to determine the efficiency.

4.0 METHODOLOGY4.1 PROCEDURE

Below is the procedure to run the experiment.1. Ensure that all valves are initially closed except valve V9 to be initially opened.

2. The Centrifugal Pump, P1 was switched on.

3. Depending on the nozzle to be tested, the isolation valve as outlined in Table 1 below was opened. Then, the appropriate control valve was adjusted so that the nozzle pressure, PT1, was set according to Table 1.

Table 1: Operation Guide for AP03 Spray Chamber System

NozzleParticle

Size

(m)Isolation

ValveSet

Pressure,

PT1Flow meterControl Valve

N1520V12 barFM1CV1

N2290V22 barFM2CV2

N3130V35 barFM2CV2

N41000V42 barFM1CV1

N5190V52 barFM2CV2

4. The nozzle water flow rate was recorded either flow meter FM1 or FM2 depending on the nozzle to be tested (Table 1)

5. Valve V9 was closed. The water level inside the spray chamber was increased until it reached the desired level indicated by the line on the chamber. Once so, the valve V9 was adjusted to maintain this water height.

6. The air blower speed controller was set to its minimum. The blower was switched on. Then, the air blower speed controller was gradually adjusted so that the blower frequency is set to 20.0Hz.

7. 1 kg of sample (300m sand) was poured into the feed vessel with the feed control valve, V11 fully closed. Then, control valve V11 was opened slightly so that the sample flow down steadily.

8. After all the sand had been delivered into the air stream, wait two minutes to ensure all dust has cleared from the pipeline then the centrifugal water pump P1 and Centrifugal Air Blower was switched off.

9. Valve V9 was slowly opened to let the dust-laden water in the spray chamber flow down by gravity to dust collecting bucket.

10. The dust was let to settle down in the bucket (approximately 5 minutes) once all water has flowed down from the chamber.

11. The bucket was taken out carefully. The excess water was drained. Then the dust was collected on a suitable oven tray. The wet sample was heat up in an oven at 200C for 2 hours until the sample becomes sufficiently dry.

12. The collected sample was weighted and the final weight was recorded.

13. The efficiency was calculated.

5.0 RESULTSExperiment 1a) Nozzle size - 130m (Nozzle 3, N3)

Flow rate: 0.07m/s

Set Pressure, PT1 (Bar)5

Air blower speed (Hz)20

Weight of sample loaded (g)1000g

Weight of sample collected (g)657g

Collection efficiency, (%)65.7%

b) Nozzle size - 190m ( Nozzle 5, N5)

Flow rate: 0.08m/s






c) Nozzle size - 290m ( Nozzle 2, N2)

Flow rate: 0.06m/s






d) Nozzle size - 520m ( Nozzle 1, N1)

Flow rate: 5.58m/s






e) Nozzle size - 1000m ( Nozzle 4, N4)

Flow rate: 11.89m/s






The result obtained from the experiment is increasing in term of the efficiency by the size of nozzle used. The highest efficiency of the nozzle used is obtained by nozzle 4 which have the smallest droplets; 1000m. the lowest efficiency is obtained with nozzle 3 with 65.7% of efficiency.

6.0 DISCUSSIONThe experiment is aimed to determine the effect of droplet size upon separation efficiency of the spray chamber unit by using different nozzle. There are five types of nozzles inside the chamber to produce five different droplet sizes.

In experiment 1, the frequency is made to constant at 20 Hz. Each and every nozzle has different value of flowrate. From the data obtained, it shows that smaller size droplet, resulted better efficiency and biggest size droplet which is 130 m is less efficient. Note that, the sample use is sand with 300 microns in diameter.The smaller size nozzle produced smaller sized droplets. The smaller droplets have maximum surface area and increase the opportunity to pollutant to make contact with the water. Note that the water level in the chamber need to be maintained at a secure level by control the opening of valve V9. However, the flowrate also influence the efficiency of the spray chamber collection. The flowrate of the water works with the size of nozzle used, the higher, the better collection can be obtained.

However, some problems occur while running the experiment. The collected sand from the filter is not wholly weight as some of the sand remains on the filter. In addition, there are sand losses after the drying process which has affected the final weight reading. 7.0 CONCLUSIONFrom the experiment, it can be concluded that smaller droplet size, better efficiency of the collected particle/pollutant. As mentioned in discussion section, the smaller droplet has maximum surface area so that the particle is easily contacted with water and be collected. The frequency of the blower is maintained at 20 Hz.8.0 REFERENCE

1. William L Heumann, Industrial Air Pollution Control System, Mc Graw Hill, New York. 1997.

Exp 7 Spray Chamber

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