Air Quality Research Program Project Work Plan. CFD Modeling for UT/TCEQ Low BTU & Low Flow Rate Flare Tests

Transcription

1 February 2011, Rev. 3 Air Quality Research Program Project Work Plan CFD Modeling for UT/TCEQ Low BTU & Low Flow Rate Flare Tests Prepared by: Daniel Chen, PI Helen Lou, Co-PI Kuyen Li, Co-PI Dan F. Smith Department of Chemical Engineering, Lamar University Christopher Martin, Co-PI Department of Chemistry & Biochemistry, Lamar University X. Chang Li, Co-PI Department of Mechanical Engineering, Lamar University Page 1

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3 1.2 Distribution List Jim MacKay TCEQ Project Liaison Air Quality Division Texas Commission on Environmental Quality Austin, Texas Mr. Vincent M. Torres Project Manager Air Quality Research Program The University of Texas at Austin, Austin, Texas Dr. Daniel H. Chen Principal Investigator Lamar University, Beaumont, Texas Page 3

4 2. Table of Contents Section Description Page No 1 Title and Approval Sheets Approval Page Distribution List 3 2 Table Of Contents 4 3 Statement of Work 5 4 References STATEMENT OF WORK Page 4

5 Current methodologies for calculating VOC emissions from flaring activities generally apply a simple mass reduction to the VOC species sent to the flare. While it is assumed that a flare operating under its designed conditions and in compliance with 40 CFR may achieve 98% destruction/removal efficiency (DRE), a flare operating outside of these parameters may have a DRE much lower than 98%. Basic combustion chemistry demonstrates that many intermediate VOC species may be formed by the combustion process. In this project, computational fluid dynamics (CFD) methods based on CHEMKIN-CFD and FLUENT are used to model low-btu, low- flow rate propylene/tng/nitrogen flare tests conducted during September, 2010 in the John Zink test facility, Tulsa, Oklahoma, in which plume measurements using both remote sensing and direct extraction were carried out to determine flare efficiencies and emissions of regulated and photo chemically important pollution species for air-assist and steam-assist flares. Various combinations of fuel BTU and flow rates were performed under open-air conditions. This project will primarily use CFD modeling as a predicting tool for the Tulsa flare performance tests. If the test data is available by May 31, 2011, the CFD modeling will be further compared with the flare performance data, i.e., flare efficiencies, and other measurement data (e.g., species concentrations) reported in the TCEQ Comprehensive Flare Study Project. If the difference between the model value and the test data is within the combined measurement & prediction uncertainty limit (e.g., ±39% for CE and ±30%% for CO, details see Sec. 7.2 ), the model value and the test data will be considered in good agreement. This modeling tool has the potential to help TCEQ s on-going evaluation on flare emissions and to serve as a basis for a future SIP revision. Lamar University will model the combustion processes data conducted in the TCEQ Comprehensive Flare Study Project (PGA No FY09-04) using computational fluid dynamics (CFD) programs. The modeling programs used by Lamar Page 5

6 University will be CHEMKIN and FLUENT. And also for this proposed project, Lamar University will provide matching to pay for the license fee to the project. GRI-Mech 3.0 is an optimized mechanism designed to model natural gas (C 1 ) combustion, including NO formation and reburn chemistry while USC is an Optimized Reaction Model of C 1 -C 3 Combustion but lacks chemistry needed to define NO formation for flaring in air. So the inclusion of NO formation chemistry from the GRI 1 mechanism will make the USC 2 mechanism suitable for modeling Tulsa test flares (that burn fuel from C 1 to C 3 and measure NO emission). Ideally the combined and individually optimized components can be optimized again as a whole. From an engineering point of view, since that bulk of the mechanism (USC) has been optimized, we only need to demonstrate this mechanism is applicable and is validated with combustion experimental data. Indeed, this mechanism has been validated by the LU team against the methane, ethylene, and propylene experimental data 3 like laminar flame speed, adiabatic flame temperature, and ignition delay. We will also add a couple of NOx species that are important to atmospheric chemistry (NO 2 and HONO) to the existing mechanism and a comparison with lab data will be carried out to evaluate this new mechanism. Lamar University will acquire the operating and design data of the flare tests conducted at the John Zink facility in Tulsa, OK from the University of Texas. These data should include the geometry of the steam-assist and air-assist flares used in the tests (AutoCad sketch with data preferred), meteorological data (cross-wind speed/direction, humidity, temperature), and the operating data (aeration, steaming, exit velocity, waste gas/pilot fuel species) available from the data acquisition system. If Lamar University acquires the test data (efficiencies and emissions) from the University of Texas by May 31, 2011, the test data will be compared with the model results to see if they are in good Page 6

7 agreement, i.e., within the combined uncertainty limits. The test data include estimated Combustion Efficiency (CE)/Destruction & Removal Efficiencies (DRE), concentration/location/path of monitored emission species (VOC, CO/CO2, and NOx), and plume temperature/ location/path. Through intensive CFD modeling, this project shall predict the regulated, monitored, and photo chemically important flare emissions that result from flaring operations at the John Zink test facility in Tulsa, Oklahoma. This project shall predict the Destruction and Removal Efficiency (DRE) and Combustion Efficiency (CE) of flares under the specified test conditions. Regulated and monitored flare emissions: O2, NO, NO2, CO, CO2, CH4, C2H2 (Acetylene), C2H4 (Ethylene), C3H6 (Propylene), CH2O (Formaldehyde), C2H4O (Acetaldehyde), and C3H6O (Acetone) will be predicted. Combustion efficiency is defined as the percentage of flare emissions that are completely oxidized to CO2. It can be written mathematically as: CO 2 % CE = 100 CO 2 + CO + THC + Soot (3.1) Where CO2 - parts per million by volume of carbon dioxide, CO - parts per million by volume of carbon monoxide exiting from the flare, THC - parts per million by volume of total hydrocarbon exiting from the flare, and Soot - parts per million by volume of soot as carbon. Soot is eliminated from industrial flares by adding appropriate amounts of steam or air and that is the reason it can be equal to zero in the above equation. The destruction & removal efficiency is given as (using propylene as an example): Propylene Destruction eff = (Amount of C3H6 fed Amount of unburned C3H6) 100 (3.2) Amount of C3H6 fed The effect of back-wash will be incorporated in the model using the Enhanced Wall Treatment feature in FLUENT. Enhanced wall treatment is a near-wall modeling Page 7

8 method that combines a two-layer model with enhanced wall functions. And this approach has successfully been used to model back-wash in industrial flares 6. There are two approaches to model back-wash or any other turbulence in the near-wall region. In one approach, the viscosity-affected inner region (viscous sublayer and buffer layer) is not re-solved. Instead, semi-empirical formulas called wall functions" are used to bridge the viscosity-affected region between the wall and the fully-turbulent region. In another approach, the turbulence models are modified to enable the viscosity-affected region to be resolved with a mesh all the way to the wall, including the viscous sublayer. Table 3.1: Proposed cases for Air Assisted flares Test Point lb Air/lb Waste Gas Ratio Waste Gas flow Waste Gas composition lb/hr Prop TNG N2 BTU/Scf CFD A % 0.00% 0% 2183 CFD A % 0.00% 0% 2183 CFD A.3 <snuff % 0.00% 0% 2183 CFD A % 20.00% 350 CFD A % 20.00% 600 LHV Table 3.2: Proposed cases for Steam Assisted flares Test Point lb Steam/lb Waste Gas Ratio Waste Gas flow Waste Gas composition N2 LHV lb/hr Prop TNG BTU/Scf CFD S % 0.00% 0% 2183 CFD S % 0.00% 0% 2183 CFD S.3 <snuff % 0.00% 0% 2183 CFD S % 20.00% 350 CFD S % 20.00% 600 A base case will be chosen for the air-assist flare (CFD A.5) and the steam-assist flare (CFD S.5). For each base case, we will run 2 more air (or steam) flow rates. We will also run 2 more LHV cases for each flare. So the total number of cases will be 2 (base cases) Page 8

9 + 2 (additional air flow rates) + 2 (additional steam flow rates) + 2 (LHVs in air-assist flare) + 2 (LHVs in steam-assist flare) =10 cases. The proposed project will: 1) Model the low-btu, low-flow rate Propylene/TNG/Nitrogen flare tests conducted during September 2010 in Tulsa, Oklahoma for the TCEQ Comprehensive Flare Study Project, using the detailed reaction mechanisms and Fluent CFD software. 2) Predict the test results: flare efficiencies (DRE/CE) and emissions using the CFD modeling 3) Compare the CFD prediction results with the flare test data (efficiencies and emissions) if available by May 31, The proposed project includes the following tasks: Task 1: Work Plan Lamar University will submit a work plan with a work statement, QAPP, and budget. The organization and task responsibilities are given below and in Section 5. Responsible Faculty: D. Chen, H. Lou, K. Li, C. Martin, X. Li Deliverable 1: Work Plan (Revision 3) Deliverable Date: February 9, 2011 Task 2: Flare Test Operation/Design/Performance Data Lamar University will acquire the operating and design data of the flare tests conducted at the John Zink facility in Tulsa, OK from the University of Texas. These data should Page 9

10 include the geometry of the steam-assist and air-assist flares used in the test (AutoCad sketch with data preferred), meteorological data (cross-wind speed/direction, humidity, temperature), and the operating data (aeration, steaming, exit velocity, waste gas/pilot fuel species) available from the data acquisition system. If Lamar University acquires the test data conducted at the John Zink facility in Tulsa, OK from the University of Texas by May 31, 2011, the test data will be compared with the model results. The flare Design/test Operation data from UT will be organized into input files for Fluent simulations such as geometry generation, fuel/steam/flow/crosswind specifications. Flare test data, if received by May 31, 2011, will be used to carry out Task 7. We need a base case of air-assist flare and another base case for steam-assist flare. For each base case, we need to run 2 more air (or steam) flow rates. We also run 2 more LHV cases for each flare. So the total number of cases will be 2 (base cases) + 2 (additional air flow rates) + 2 (additional steam flow rates) + 2 (LHVs in air-assist flare) + 2 (LHVs in steam-assist flare) =10 cases. Responsible Faculty: D. Chen Deliverable 2: Included in Monthly Reports Deliverable Date: March 31, Task 3: Hardware/Software Acquisition and Data Storage Responsible Faculty: H. Lou Deliverable 3: Included in Monthly and Final Reports Deliverable Date: Same as the due date for Task 8 Task 4: Combustion Mechanism Development The details of combustion mechanism development are given in Sections The role of individual faculty is given below and Section 5. Page 10

11 4A Combustion Mechanism Generation Responsible Faculty: C. Martini (Combustion Mechanism Generation) Deliverable 4A: Deliverable Date: Included in Monthly Reports The existing 50 species mechanism is fully functional. The next version mechanism (USC + GRI 3.0) with additional NOx species will be delivered by May 31, B Combustion Mechanism Validation Responsible Faculty: H. Lou Deliverable 4B: Deliverable Date: Included in Monthly Reports The data pertinent to the validation (or performance evaluation) of the new mechanism (USC + GRI 3.0) with additional NOx species will be delivered in May, Task 5: CFD Model Development The details of the CFD model development are given in Sections A. Geometry Creation & Boundary Conditions The details of the Geometry Creation & Boundary Conditions are given in Sections 6.4. Responsible Faculty: X. Li Deliverable 5A: Included in Monthly Reports Deliverable Date: March 31, B Physical/Turbulence Model Selection & Parameter Evaluation The details of the Physical/Turbulence Model Selection & Parameter Evaluation are given in Sections 6.7. Page 11

12 Responsible Faculty: X. Li Deliverable 5B: Included in Monthly Reports Deliverable Date: March 31, C Model Development Presentation The PI will provide a presentation to the AQRP Project Manager and the staff to review the model development (Tasks 5A & 5B). Deliverable 5C: Model Development Presentation Deliverable Date: March 31, D CFD Model Calibration The selection of physical/turbulence models and parameters will be checked against literature flare test data 4,5,6 and will be varied if necessary to validate the CFD modeling used in this project. The chosen physical/turbulence models, model parameters, and simulation results will be delivered at the conclusion of this subtask. Responsible Faculty: X. Li Deliverable 5D: Included in Monthly Reports Deliverable Date: June 30, 2011 Task 6: CFD Modeling & Post Processing 6A Modeling Base Case Implement developed CFD modeling framework to run the selected Base Case. Page 12

13 Responsible Faculty: K. Li (CE & DRE), D. Chen (NOx Species) & C. Martin (VOC Species) Deliverable 6A: Included in Monthly and Final Reports Deliverable Date: April 30, B Base Case Presentation The PI will present the results of the base case modeling (Task 6A) to the AQRP manager and staff. Responsible Faculty: D. Chen Deliverable 6B: Base Case Presentation Deliverable Date: April 30, C Modeling Rest of the Cases Implement developed CFD modeling framework to run the 10 chosen Tulsa, OK Flare test cases. The post-processing of CFD will predict flare efficiencies and the extent of flare emissions. Responsible Faculty: K. Li (CE & DRE), D. Chen (NOx Species) & C. Martin (VOC Species) Deliverable 6C: Included in Monthly and Final Reports Deliverable Date: Same as the due date for Task 8. Task 7: Comparison CFD Prediction and Flare Test Data Page 13

14 Comparison will be carried out if the data is provided by UT by May 31, The CFD model will be validated using literature data. Responsible Faculty: D. Chen (Species), K. Li (CE & DRE) Deliverable 7: Included in Monthly and Final Reports Deliverable Date: August 31, 2011 Task 8: Reports 8A Monthly Project Report Responsible Faculty: D. Chen, H. Lou, K. Li, C. Martin, X. Li Deliverable 8A: Deliverable Date: Monthly Project Report 8th day of the month after the issue of the work order 8B: Draft Final Project Report Responsible Faculty: D. Chen, H. Lou, K. Li, C. Martin, X. Li Deliverable 8B: Draft Final Project Report Deliverable Date: July 20, C Final Project Report Responsible Faculty: D. Chen, H. Lou, K. Li, C. Martin, X. Li Deliverable 8C: Final Project Report Deliverable Date: August 31, 2011 The organization and responsibilities are summarized as follows: Page 14

15 Dr. Daniel Chen, Principal Investigator o Work Plan, Flare Test Operation/Design/Performance data, Model Development/ Base Case Presentations, CFD modeling & Post processing, Comparison CFD Prediction and Flare Test Data, and Reporting (Tasks 1, 2, 5C, 6, 7, 8) Dr. Helen Lou, Co-PI o Work Plan, Hardware/Software acquisition, Data Storage, Mechanism Development, and Reporting (Tasks 1, 3, 4B, 8) Dr. Kuyen Li, Co-PI o Work Plan, CFD Modeling & Post processing, and Comparison CFD Prediction and Flare Test Data, and Reporting (Tasks 1, 6A, 6C, 7, 8) Dr. Christopher Martin, Co-PI o Work Plan, Combustion Mechanism Development, CFD modeling & Post processing, and Reporting (Tasks 1, 4A, 6A, 6C, 8) Dr. X. Chang Li, Co-PI o Geometry generation, CFD boundary conditions, Physical/Turbulence Model Selection & Parameter Evaluation, and Reporting (Tasks 1, 5A, 5B, 5D, 8) Duties of the Students A. PhD Graduate Students: 2 Working on Combustion Mechanism Generation & Evaluation, CFD Model Development, Physical/Turbulence Model Selection & Parameter Evaluation, CFD Model Calibration, and Comparison of CFD Prediction and Flare Test Data (Tasks 4A, 4B, 5B, 5D, 7) B. MS Research Assistants: 3 Page 15

16 Working on Geometry Generation, Input Data File Preparation, CFD Modeling & Post Processing, Comparison of CFD Prediction and Flare Test Data, and Data Storage. (Tasks 2, 3, 5A, 6A, 6C, 7) Table 3.3 Task Chart: Task vs. Responsible Faculty No. Tasks Responsible Faculty Chen Lou K. Li Martin X. Li 1 Work Plan X X X X X 2 Collection of Flare X Operation/Design/Performance Data Hardware/Software Acquisition and X 3 Data Storage 4 Combustion Mechanism Development a Combustion Mechanism Generation X b Combustion Mechanism Validation X 5 CFD Model Development a Geometry Creation & Boundary Conditions X b Physical/Turbulence Model Selection & Parameter Evaluation X c Model Development Presentation X d CFD Model Calibration X 6 CFD Modeling & Post Processing a Modeling Base Case X X X b Base Case presentation X c Modeling rest of the cases X X X 7 Comparison CFD Prediction and Flare Test Data X X 8 Reports a Monthly Report X X X X X b Draft Final Report X X X X X c Final Report X X X X X Page 16

17 Table 3.4 Task Chart: Task vs. Schedule No. Tasks Months Work Plan X X 2 Collection of Flare Operation/Design/Performance Data X X X Hardware/Software Acquisition and X X X X 3 Data Storage X X X X 4 Combustion Mechanism Development a Combustion Mechanism Generation X X X X b Combustion Mechanism Validation X X 5 CFD Model Development a Geometry Creation & Boundary Conditions X X b Physical/Turbulence Model Selection & Parameter Evaluation X X c Model development presentation X d CFD Model Calibration X X X X X 6 CFD Modeling & Post Processing X X X X X X X a Modeling base case X X X b Base Case presentation X c Modeling rest of the cases X X X X X 7 Comparison CFD Prediction and Flare Test Data X X X 8 Reports a Monthly Report X X X X X X b Draft Final Report X c Final Report X Page 17

18 4. REFERENCES 1 Gregory P. Smith, David M. Golden, Michael Frenklach, Nigel W. Moriarty, Boris Eiteneer, Mikhail Goldenberg, C. Thomas Bowman, Ronald K. Hanson, Soonho Song, William C. Gardiner, Jr., Vitali V. Lissianski, and Zhiwei Qin 2 Wang, H.; Laskin, A. A Comprehensive Kinetic Model of Ethylene and Acetylene Oxidation at High Temperatures, University of Southern California, Progress Report, C4/c2.html 3 Daniel J.Serry, C.T.Bowman, "An Experimental and Analytical Study of Methane Oxidation behind Shock Wavess",Combustion and Flame,14,37-48(1970). 4 URS Corporation. (2004) Passive FTIR Phase I Testing of Simulated and Controlled Flare Systems final report, for Texas Commission on Environmental Quality and University of Houston. 5 Kostiuk, L, Johnson, M and Thomas, G. (2004). University of Alberta Flare Research Project Final Report. 6 David Castiñeira and Thomas F. Edgar, CFD for Simulation of Steam-Assisted and Air-Assisted Flare Combustion Systems, Energy & Fuels 20, (2006) Page 18