PetroChemistry 2016 Evaporation Velocity of Cryogenic Liquid With and Without Spreading 2016. 12. 06 Myungbae Kim Korea Institute of Machinery & Materials
Contents Introduction Evaporation Model Experimental Set-up Results & Discussion Conclusions 2
Introduction(1) Formation of a Pool and Its Spread Liquid Tank Leak Position Boiling Liquid Pool As time progresses Ground 3
Introduction(2) Evaporation of A Non-Spreading Pool Evaporation of A Spreading Pool 4
Introduction(3) Why Is The Phenomenon Important? Fires and explosions in case of LNG, LPG and so on. Inhalation of toxic material due to dispersion with wind What To Study? Measurement of the evaporation velocity Because it is a key parameter to analyze the spread of liquid Comparison between experimental results and unsteady 1- dimensional heat conduction model To suggest a new measurement technique for the evaporation velocity 5
Introduction(4) API RP 581 Risk-based Inspection Technology Loss Of Containment - Leak Occurs only when the pressure boundary is breached. Continuous Release - Spreading pool Occurs over a longer period of time, allowing the fluid to disperse in the shape of an elongated ellipse. Instantaneous Release - Non-spreading or Spreading pool Occurs so rapidly that the fluid disperses as a single large cloud or pool. API(American Petroleum Institute) 6
Evaporation Model(1) Evaporation of A Non-Spreading Pool Cryogenic Liquid T t = α 2 T z 2 T = T a for 0 z at t = 0 T = T B for 0 < t at z = 0 T = T a for 0 < t at z = Ground z Heat flux q = k T a T B πα 0.5 t 0.5 Evaporation velocity E 1 = q ρl = k T a T B ρl πα 0.5 t 0.5 7
Evaporation Model(2) Evaporation of A Spreading Pool Ground R(t) r Evaporation velocity z E 2 = 1 πr 2 k T a T B ρl πα 0.5 0 R(t) 2πr dr t t 0.5 8
Experimental Apparatus(1) 9
Experimental Apparatus(2) The Concrete Ground i Distance from the center of the plate, m Thermocouple number 0 0 TC-0 1 0.20 TC-101, TC-201 2 0.25 TC-102, TC-202 3 0.30 TC-103, TC-203 4 0.35 TC-104, TC-204 5 0.40 TC-105, TC-205 6 0.45 TC-106, TC-206 7 0.50 TC-107, TC-207 10
Mass Spill Rate, kg/s Experimental Apparatus(3) Spill Rates 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 Case 7 Case 6 Case 5 Case 4 Case 3 Case 2 0.00 0 20 40 60 80 100 120 140 160 180 200 Time, s Case 1 Case Spill time, s Nominal mass spill rate, kg/s Nominal volume spill rate, m 3 /s 1 198 0.0402 4.9806 10 5 2 135 0.0546 6.7755 10 5 3 87 0.0739 9.1709 10 5 4 67 0.0877 1.0873 10 4 5 51 0.1050 1.3024 10 4 6 37 0.1319 1.6358 10 4 7 27 0.1629 2.0203 10 4 11
Experimental Apparatus(4) Evaporation Velocity, E(m/s) W i + tw s W i+1 Spreading W i + tw s Evaporation = W i+1 E = Evaporation ρa t TC location Time i t i Wi i+1 t i+1 Mass of LN 2 W i+1 Spill rate W s 12
Experimental Apparatus(5) Table 1 Properties of liquid nitrogen Density, kg/m 3 Latent heat of vaporization, kj/kg Kinematic viscosity, m 2 /s Boiling temperature, K 806.11 199.18 1. 96 10 7 77 Table 2 Thermal properties and conditions of the plate Material Density, kg/m 3 Thermal conductivity, W/m. K Thermal Diffusivity, m 2 /s Initial temperature, K Concrete 2300 1.05 9.5X10-7 293 13
Evaporation Velocity, m/s Results & Discussion(1) 2.8x10-3 Case 1 2.4x10-3 2.0x10-3 1.6x10-3 1.2x10-3 8.0x10-4 4.0x10-4 0.0 0.20 0.25 0.30 0.35 0.40 0.45 Pool Radius, m Case 2 Case 3 Case 4 Case 5 Case 6 Case 7 14
Evaporation velocity (x10 4 ), m/s Evaporation velocity (x10 4 ), m/s Results & Discussion(2) 6 5 Experiment Unsteady 1-D heat conduction model 6 5 Experiment Unsteady 1-D heat conduction model 4 4 3 3 2 2 1 1 0 0.20 0.25 0.30 0.35 0.40 0.45 Pool radius, m 0 0.20 0.25 0.30 0.35 0.40 0.45 Pool radius, m Case 1 Case 2 15
Evaporation velocity (x10 4 ), m/s Evaporation velocity (x10 4 ), m/s Results & Discussion(3) 10 Experiment Unsteady 1-D heat conduction model 16 14 Experiment Unsteady 1-D heat conduction model 8 12 6 10 8 4 6 2 4 2 0 0.20 0.25 0.30 0.35 0.40 0.45 0 0.20 0.25 0.30 0.35 0.40 0.45 Pool radius, m Pool radius, m Case 3 Case 4 16
Evaporation velocity (x10 4 ), m/s Evaporation velocity (x10 4 ), m/s Results & Discussion(4) 18 15 Experiment Unsteady 1-D heat conduction model 24 20 Experiment Unsteady 1-D heat conduction model 12 16 9 12 6 8 3 4 0 0.20 0.25 0.30 0.35 0.40 0.45 0 0.20 0.25 0.30 0.35 0.40 0.45 Pool radius, m Pool radius, m Case 5 Case 6 17
Evaporation velocity (x10 4 ), m/s Results & Discussion(5) 30 25 Experiment Unsteady 1-D heat conduction model 20 15 10 Disagreement between the first values Discrepancy among the measurement values at 0.2 m. 5 0 0.20 0.25 0.30 0.35 0.40 0.45 Pool radius, m Case 7 18
Evaporation Velocity (x10 4 ), m/s Results & Discussion(6) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Spreading pool (Experimental result) Spreading pool (1-D heat conduction model) Non-spreading pool (Olewski et al., 2015) 0 30 60 90 120 150 180 210 Time, s Case 1 19
Conclusions The good agreement between the unsteady 1-D heat conduction model and the experimental data except the initial period. A new semi-theoretical method for measuring the evaporation velocity of the spreading pool without providing information about the spill rate and pool mass. We need only experimental data of the pool radius with time. Therefore, we don t need a digital balance as a part of experimental apparatus. The evaporation velocities in the spreading pool are much greater than those of the non-spreading pool because the spreading pool spreads continuously to new warm ground while the non-spreading pool is cooling ground continuously, which leads to decrease of heat flux into the non-spreading pool. 20