Performance of an Entegris phasor X Heat Exchanger in Cabot Semi-Sperse 12

Transcription

1 Performance of an Entegris phasor X Heat Exchanger in Cabot Semi-Sperse 12 Mark Litchy, Dennis Chilcote and Don Grant CT Associates, Inc. Bipin Parekh, Annie Xia, Michael Clarke, and Russ Mollica Entegris, Inc CMP Users Conference February 12, 2008 Slide 1

2 Introduction Heat exchangers can be used to efficiently remove heat from liquid delivery systems, such as those incorporating centrifugal pumps. The heat exchanger evaluated is constructed entirely of PFA to provide High purity Chemical compatibility Even though it is constructed of PFA, it is efficient at removing heat with an acceptable pressure drop. However, in slurry applications, there is concern that the heat exchanger may damage the slurry or clog. Slide 2

3 Introduction Materials of construction and design are important: Thermal conductivity Corrosion resistance Capable of withstanding thermal stresses and high pressures Since PFA has poor thermal conductivity properties relative to most metallic heat exchangers Tube thickness must be thin Exchanger must be well designed to prevent flow channeling and streaming Surface area must be large Tradeoffs: Reducing the tube thickness reduces the operating temperature and pressure rating of the device Increasing the surface area increases cost and size of the device Slide 3

4 Heat exchanger configurations Slide 4

5 Experiments performed in water Measurement of pressure drop ( P) in the tube and shell as a function of flow rate. PHX03U (U configuration, short: surface area = 0.3 m 2 ) PHX08S (S configuration, long: surface area = 0.8 m 2 ) PHX08U (U configuration, long: surface area = 0.8 m 2 ) Measurement of heat transfer coefficients at a series of flow rates for 3 different heat exchangers. PHX03U PHX08S PHX08U Slide 5

6 Schematic of pressure drop versus flow rate test system flow control valve thermistor T flow meter FM differential pressure gauge P heat exchanger P water tank circulation pump Slide 6

7 Schematic of heat transfer coefficient test system to drain T4 FM flow meter T1 heat exchanger T2 T1 thermistor #1 FM flow control valve T3 FM flow control valve to main water loop regulator cold water supply warm water tank circulation pump inlet filter Slide 7

8 Calculation of heat transfer coefficient Q c U = A where: U = heat transfer coefficient (Btu/hr/ft 2 / F) Q = flow rate on the tube side (lb/hr) c = specific heat of water (Btu/lb/ F) = 1.0 T tube = T tube in -T tube out ( F) A = surface area of heat exchanger (ft 2 ) T ln = logarithmic mean temperature difference = [ T 0 T L ]/[ln( T 0 / T L )] where: T 0 and T L = temperature differences between the hot and cold fluids at the two ends of the heat exchanger, x = 0 and x = L T T tube ln Slide 8

9 Experiments performed in slurry Measurement of the effect of the heat exchanger on the slurry particle size distribution (PSD) of Cabot Semi- Sperse 12 (SS-12). PHX08U (U-line long) 38.5 lpm 10 lpm Stainless steel coil (control test) 38.5 lpm Slide 9

10 Slurry test system schematic Humidified N 2 flow meter T2 P Heat Exchanger T3 SS12 T1 T5 T4 flow meter BPS4 Chiller Slide 10

11 Details of tests performed in slurry Tests at 38.5 lpm (PHX08U and control test): Test system volume: 50L of SS-12 Duration: 5 days (or ~5,700 turnovers) Pump outlet pressure: 34 psig Test at 10 lpm (PHX08U test only): Test system volume: 29L of SS-12 Duration: 10 days (or ~5,700 turnovers) Pump outlet pressure: 3 psig All tests: Tank blanketed with humidified N 2 : RH > 90% Slurry temperature: 21 ± 1 C SS-25 was filtered using an Entegris Planargard CMP5 10 filter prior to the test SS-25 was then diluted with ultra pure water as it was added to the test system tank. Slide 11

12 Particle size measurement Working particle size distribution Measured using dynamic light scattering Instrument used NICOMP 380ZLS (Particle Sizing Systems) All particles in a defined volume illuminated simultaneously Particles are sized by measuring their diffusion coefficient Measures relative concentrations Sensitive to about 1% by volume Large particle tail size distribution Instrument used: AccuSizer 780 sensor (Particle Sizing Systems) Uses a combination of light scattering and light extinction to size particles 0.56µm Requires dilution CMP Slurries contain >10 14 working particles/ml The large particle tail contains ~10 6 particles/ml ( 0.56µm) Slide 12

13 Working particle size distributions (PSDs) Relative Volume-Weighted Differential Concentration (%) Particle Diameter (µm) Slide 13

14 AccuSizer dilution system schematic Drain Bypass Loop PI AccuSizer Sensor Static Mixer Filter Ultrapure Water Tank Circulation Pump Injection Pump Slurry Sample Slide 14

15 Results Slide 15

16 Comparison of P vs. flow rate: shell side PHX03U-shell PHX08U-shell PHX08S-shell 20 Differential Pressure Across Heat Exchanger (psid) Differential Pressure Across Heat Exchanger (kpa) Flow rate (lpm) Slide 16

17 Comparison of P vs. flow rate: tube side PHX03U-tube PHX08U-tube PHX08S-tube 20 Differential Pressure Across Heat Exchanger (psid) Differential Pressure Across Heat Exchanger (kpa) Flow rate (lpm) Slide 17

18 Summary of differential pressure results Differential pressure drop versus flow rate were similar for both the PHX08U and PHX08S configurations. The P across tubes for the PHX03U configuration was significantly lower. Slide 18

19 Heat transfer coefficients vs. flow rate: PHX03U 200 Heat Transfer Coefficient (Btu/hr/ft 2 /F) Vary tube flow rate, constant shell flow rate = 12 lpm Vary shell flow rate, constant tube flow rate = 12 lpm Heat Transfer Coefficient (W/m 2 /K) Flow Rate (lpm) Slide 19

20 Heat transfer coefficients vs. flow rate: PHX08U 200 Heat Transfer Coefficient (Btu/hr/ft 2 /F) Vary tube flow rate, constant shell flow rate = 12 lpm Vary shell flow rate, constant tube flow rate = 12 lpm Heat Transfer Coefficient (W/m 2 /K) Flow Rate (lpm) Slide 20

21 Heat transfer coefficients vs. flow rate: PHX08S 200 Heat Transfer Coefficient (Btu/hr/ft 2 /F) Vary tube flow rate, constant shell flow rate = 12 lpm Vary shell flow rate, constant tube flow rate = 12 lpm Heat Transfer Coefficient (W/m 2 /K) Flow Rate (lpm) Slide 21

22 Summary of heat transfer coefficient results The S configuration is slightly more efficient than the U configuration. The long heat exchangers were more efficient than the short heat exchanger. Approach temperatures for these tests were ~10 F, which is a reasonable operating condition. Typical heat transfer coefficients in shell and tube heat exchangers ~ Btu/hr/ft 2 / F Average Heat Transfer Coefficients (Btu/hr/ft 2 / F) Configuration PHX08S PHX08U PHX03U Average of 4 heating and cooling tests Std. dev Slide 22

23 Cumulative Concentration (#/ml) Cumulative PSDs of the large particle tail Control Test (38.5 lpm) Turnovers Cumulative Concentration (#/ml) phasor X Test (10 lpm) Turnovers Cumulative Concentration (#/ml) Particle Diameter (µm) phasor X Test (38.5 lpm) Turnovers Particle Diameter (µm) 1 10 Particle Diameter (µm) Slide 23

24 Concentrations relative to initial concentration Control Test (38.5 lpm) phasor X Test (10 lpm) Concentration Relative to Initial Concentration Concentration Relative to Initial Concentration Turnovers Turnovers phasor X Test (38.5 lpm) Concentration Relative to Initial Concentration > 0.56 µm > 0.7 µm > 1.0 µm > 2.0 µm > 3.0 µm > 0.56 µm > 0.7 µm > 1.0 µm > 2.0 µm > 3.0 µm Turnovers Slide 24

25 Change in concentrations for selected sizes Control Test (38.5 lpm) phasor X Test (10 lpm) Change in Concentration (#/ml) Change in Concentration (#/ml) Turnovers phasor X Test (38.5 lpm) Turnovers Change in Concentration (#/ml) Turnovers > 1.0 µm > 2.0 µm > 3.0 µm Slide 25

26 Discussion of large particle test results A slight decrease in the large particle tail was observed during the control test. An increase in the concentrations of particles 1 µm was observed during the heat exchanger test at the higher flow rate. Agglomeration at smaller sizes probably occurred as well, but since the concentration of these particles was higher, no increase was apparent. Particle concentrations tended to increase roughly linearly with increasing turnovers. Slide 26

27 Discussion of large particle test results For particles 2 µm, the concentration increased by roughly a factor of 5 by the end of the test. This equates to a 0.07% increase in particle concentration 2 µm per pass through the heat exchanger. In a typical slurry delivery system application, slurry is used with ~100 turnovers, thus only a fairly small increase, ~7%, in concentration would occur. This level of increase is dramatically lower than generated by some pumps. (Previous studies have shown up to a 500% increase particle concentrations within 100 turnovers.) Concentration Relative to Initial Concentration > 0.56 µm > 0.7 µm > 1.0 µm > 1.5 µm > 2.0 µm > 5.0 µm Diaphragm Pump Turnovers 2007 CMP Users Conference Slide 27

28 Working particle size measurements Volume-Weighted Diameter (nm) Volume-Weighted Diameter (nm) Control Test (38.5 lpm) 50 Mean Error bars represent ± 3σ 99th Percentile Size Turnovers phasor X Test (38.5 lpm) Error bars represent ± 3σ Mean 99th Percentile Size Turnovers Volume-Weighted Diameter (nm) phasor X Test (10 lpm) Mean 50 99th Percentile Size Error bars represent ± 3σ Turnovers Slide 28

29 Discussion of working particle results No significant change in the mean or 99 th percentile size was observed due to the presence of the heat exchanger. A small increase (25-35 nm) in the 99 th percentile size was observed during the test at the high flow rate. However, this increase was also observed during the control test, thus it may be attributed to the test system rather than the heat exchanger. Slide 29

30 Summary of slurry test results No indication of clogging or settling of slurry in the heat exchanger during these tests. The heat exchanger was capable of efficiently removing heat so that a constant temperature could be maintained. No significant change in the mean or 99 th percentile size was observed due to the presence of the heat exchanger. Minimal change in the large particle tail was observed during the control test and heat exchanger test at 10 lpm. During the heat exchanger test at higher flow, an increase in particle concentrations were observed for particles 1 µm in size. Since slurry is typically used within 100 turnovers in a typical delivery system, only a small (~7%) increase in particle concentrations 2 µm would occur. This level of increase, although significant, is dramatically lower than that generated by some pump systems. Slide 30