"NCSCTECH MAN 4110-1-83 I (REVISION A) S00 TECHNICAL MANUAL tow DESIGN GUIDELINES FOR CARBON DIOXIDE SCRUBBERS I MAY 1983 REVISED JULY 1985 Prepared by M. L. NUCKOLS, A. PURER, G. A. DEASON I OF * Approved for public release; , J 1"73 distribution unlimited NAVAL COASTAL SYSTEMS CENTER PANAMA CITY, FLORIDA 32407 85. .U 15 (O SECURITY CLASSIFICATION OF TNIS PAGE (When Data Entered) R O DOCULMENTATIONkB PAGE READ INSTRUCTIONS REPORT DOCUMENTATION~ PAGE BEFORE COMPLETING FORM 1. REPORT NUMBER 2a. GOVT AQCMCSION N (.SAECIP F.NTTSChALOG NUMBER "NCSC TECHMAN 4110-1-83 (Rev A) A, -NI ' 4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED "Design Guidelines for Carbon Dioxide Scrubbers '" 6. PERFORMING ORG. REPORT N UMBER A' 7. AUTHOR(&) 8. CONTRACT OR GRANT NUMBER(S) M. L. Nuckols, A. Purer, and G. A. Deason 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT. TASK AREA 6t WORK UNIT NUMBERS Naval Coastal PanaaLSystems 3407Project CenterCty, S0394, Task Area Panama City, FL 32407210,WrUnt2 22102, Work Unit 02 II. CONTROLLING OFFICE NAME AND ADDRE1S t2. REPORT 3ATE May 1983 Rev. July 1985 13, NUMBER OF PAGES 69 14- MONI TORING AGENCY NAME & ADDRESS(if different from Controtling Office) 15. SECURITY CLASS. (of this report) UNCLASSIFIED ISa. OECL ASSI FICATION/DOWNGRADING _ __N•AEOULE 16. DISTRIBUTION STATEMENT (of thia Repott) Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, If different from Report) IS. SUPPLEMENTARY NOTES II. KEY WORDS (Continue on reverse side If noceassry and Identify by block number) Carbon Dioxide; Scrubbers; Absorption; Design; Life Support; Pressure; "Swimmer Diver; Environmental Effects; Diving., 20. ABSTRACT (Continue on reverse side if necessary end Identify by block number) ""ýDesign data and guidelines are presented to help predict the performance of "axial flow carbon dioxide canister designs using alkali metal hydroxide absorbers. The design data are d.!rived from a large series of laboratory test ./ "conducted at the Naval Coastal Systems Center to isolate the effects of environmental and geometric parameters on canister absorption efficiency. Sample canister designs are considered to demonstrate the use of the derived daza to predict effective canister life and pressure drop levels. Alternative techniques for the sorption of carbon dioxide are also reviewed. D JAN 73 1473 EDITION OF 1 NOV 65 IS OBSOLETE UNCLASSIFIED S/N 0102- LF.014- 6601 SECURITY CLASSIFICATION OF THIS PAGE (fhen Date Sntered) NCSC TECHMAN 4110-1-83(A) REVISION PAGE Changes and minor revisions have been made on the following pages. The changes have not resulted in any technical changes, nor in intent and purpose of the Manual. Page Change Page Change v Change AF to AW 37 Change diameter to 0.01167 ft. 2 Add "Text continues..." Change Re Equation to 0.01167 ft. 3 Box-in Table I Change AF to AW 17 Figure 4 - add gvid and 38 Change A. to A change scale in two places 23 Figure 10 - add grid 42 Change V to V in 0 24 , Correct Equation 11 three places 43 Change V toV 0o 25 Figure 11 - add grid 44 Change V to V in two 26 Figure 12 - add grid places0 27 Figure 13 - add grid 45 Change e to 0.01167 ft. in two places 28 Figure 14 - add grid Change V to V 0 29 Figure 15 - add grid 46 Change e to 0.01167 ft. Change AF to AW in Figure 19 Change V to V * 31 Correct Equations and 0 values in Steps 4, 5, 6 47 Change diameter values in Table 3 32 Change e from in. to ft. Change V to V in three in Step 6 places0 "Insert 0.01167 three 33 Change A to AW in places Steps 13 and 14 48 In Ap Equation change ""34 Change diameter from divisor to 0.01167 in. to ft. and A. to A 36 Change diameter to 0.01167 ft. and Ato A .4 4 NCSC TECHMAN 4110-1-83(A) GLOSSARY Baffle: An obstructing device within a canister which deflects the flow of gases. Breakthrough: The act, result, ar time at which the carbon dioxide concentra- ".tion in the gas stream that exits the canister exceeds the physiological limit for human respiration. * Breathing The impedance to the flow of respired gas, usually expressed Resistance: in the cm H20/l/sec. Canister Useful life of the carbon dioxide absorption system prior to Duration: breakthrough. Causticity: The ability to burn or destroy living tissue by chemical action. Contact Time: The time interval during which the CO2 laden gas is within the reaction zone of the canister; residence time. Dead Volume: The volume within a canister which is not occupied by the solid absorbent; equal to the sum of the interparticle space and the intraparticle space. Efficiency: Ratio which is indicative of the canister performance; equal to the capacity of canister CO2 absorption divided by its theoretical absorption capacity. Inter-Particle Dead volume in a canister which is located between the adjacent Space: particles of absorbent material. Intra-Particle Dead volume in a canister which is made up of the porous Space: volume within an absorbent particle. Linear Superficial velocity of gas flow through a canister, equal to Velocity the product of the canister length and volumetric flow rate divided by the canister dead volume. Pore: Microscopic spaces within absorbent particles which provide much of the surface area required for the chemical reactions involved in the absorption of carbon dioxide. Residence The mean transit time for a volume of breathing gas between Time: canister inlet and exit. Respiratory Number of breaths per minute. Rate: i , NCSC TECHMAN 4110-1.-83(A) *1% 4.. GLOSSARY (Continued) Respiratory One complete breath, consisting of an inspiratory and Cycle: expiratory cycle. Respiratory Volume per minute of gas moved in and out of the lungs. Minute Volume: Respiratory The ratio of the volume of carbon dioxide produced to the "Quotient: volume of oxygen consumed. Reynolda A dimensionless quantity expressing the ratio of inertia to Number: viscous forces in a flow system. Surface Level A measure of the partial pressure of CO* in a gas mix; equal Equivalent to the CO2 percentage by volume in the gas mix multiplied by (SLE): the total pressure in atmospheres absolute; i.e., %.SLE = % CO2 X P, ata Tidal Volume: Volume of gas inspired or expired during a single respiration. Vital The maximum volume of gas a subject is capable of exhaling Capacity: after inflating the lungs to their maximum capacity. Accession For NiTIS-G'R"A&Ik DTIC TAB Unannounced Justificatiox Distribut ion/ | COPY' Availability Codes nil am Dist Special NCSC TECG""w 4110-1-83(A) TABLE OF CONTENTS Page No. INTRODUCTION .. ... 1 CARBON DIOXIDE CONCENTRATION AND PHYSIOLOGICAL EFFECTS ... 2 DESIGN CONSIDERATIONS FOR CO2 SCRUBBERS . .. 7 *. DIMENSIONAL ANALYSIS OF ABSORPTION PROCESS . .... 12 CANISTER DESIGN DATA . .. .. .. 16 SCRUBBER DESIGN PROCEDURE . .. 24 PULSATILE VERSUS STEADY FLOW IN CANISTERS . .... 39 CANISTER FLOW RESISTANCE AND ITS INFLUENCE ON HUMAN BREATHING CHARACTERISTICS. 40 PRESSURE DROP THROUGH CANISTERS . 41 Sample Calculation .. ... 45 ALTERNATIVE CARBON DIOXIDE REMOVAL METHODS . .48 CHEMICAL REMOVAL OF CARBON DIOXIDE . ... 48 Hydroxides 50 Peroxides . ..... 51 Superoxides . .... .. 51 Ozonides . ... 53 "Amines . .. .. .. 54 ", Miscellaneous 55 "PHYSICAL SYSTEMS FOR THE REMOVAL OF CARBON DIOXIDE . .. 55 Molecular Sieve . .. 55 %4 iii NCSC TECIMAN 4110-1-83(A) TABLE OF CONTENTS (Continued) •, Page No. Membrane Separation . • 56 Cryogenic Removal (Freeze Out). 56 *- Miscellaneous ... 56 APPENDIX A - PROPERTIES OF CO2 ABSORBENTS . .. A-i APPENIDX B - CALCULATIONS OF DIMENSIONLESS GROUPS . .. B-i APPENDIX C - GAS STREAM PROPERTIES ..... .. C-1 LIST OF FIGURES Figure No. Page No. 1 Relation of Physiological Effects to Carbon "Dioxide Concentration and Exposure Period 5 2 Relation of CO2 Tolerance Zones to Depth and Percentage of CO2 in Breathing Gas 6 3 The Absorption Process 8 4 Calculated Efficiency of Stanldard Test Canister at Varying Pressures 17 5 Effect of Gas Stream Temperature on Canister Efficiency at 1 ata 18 6 Effect of Gas Stream Humidity on Canister * Efficiency at 1 ata 19 7 Effect of Gas Stream CO2 Content on Canister Efficiency at 1 ata 20 8 Effect of Canister LID Ratio on its Efficiency at 1 ata 21 9 Effect of D/e Ratio on Canister Efficiency 22 iv NCSC TECHMAN 4110-1-83(A) LIST OF ILLUSTRATIONS (Continued) Figure No. Page No. "10 Theoretical Bedlife for Sodasorb Canisters 23 11 Temperature Effect Factor, AT 25 12 Humidity Effect Factor, AH 26 13 CO2 Injection Rate Factor, AC 27 14 Length-to-Diameter Effect Factor, AD 28 15 Wall Effect Factor, A 29 A 16 Typical Breathing Pattern for Man 40 17 Coi:lelaLion of Data on Pressure Drop Through Beds of Solids 43 18 Wall Effect Factor 44 19 Pressure Drop Across Absorbent Canisters at Various Depths 46 LIST OF TABLES Table No. Page No. 1 CO2 Production Versus 02 Consumption for Various Swimming Rates 3 2 Parameters of Canister CO2 Absorption 9 3 Particle Mesh Sizes 47 4 Chemical Removal of Carbon Dioxide 49 5 Physical Systems for the Removal of Carbon Dioxide 49 6 Properties of Metal Hydroxides 50 7 Capacities of Superoxide Compounds 51 8 Capacities of Ozonide Compounds 53 9 Absorption Capacities of Metal Oxides 54 .4 V NCSC TECHMAN 4110-1-83(A) INTRODUCTION Since World War I, when chemical absorbing agents were being investigated for gas masks, 1 engineers have been asking how the absorption efficiency of their CO2 scrubbers can be optimized. What are the most favorable environmen- tal conditions for efficient operation of the absorption canister? How does the geometry of the canister affect this efficiency? Can we predict the per- formance of a CO2 scrubber under one flow condition based on our observations of its performance under different flow conditions? This manzial has been developed in an effort to help answer these questions as well as help engineers to predict the performance of prototype designs.