Determination of Inert Gas in Anhydrous Ammonia

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Determination of Inert Gas in Anhydrous Ammonia

ANHYDROUS AMMONIA: DETERMINATION OF INERT GASES

SCOPE AND FIELD OF APPLICATION

This packed-column GC method is suitable for the determination of hydrogen, nitrogen, oxygen, argon and carbon monoxide in anhydrous ammonia. The determinations of the gases are linear in the range O-100 ppm v/v.

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Determination of Inert Gas in Anhydrous Ammonia

  1. 1. GBH Enterprises, Ltd. Plant Analytical Techniques ANHYDROUS AMMONIA: DETERMINATION OF INERT GASES Information contained in this publication or as otherwise supplied to Users is believed to be accurate and correct at time of going to press, and is given in good faith, but it is for the User to satisfy itself of the suitability of the information for its own particular purpose. GBHE gives no warranty as to the fitness of this information for any particular purpose and any implied warranty or condition (statutory or otherwise) is excluded except to the extent that exclusion is prevented by law. GBHE accepts no liability for loss or personnel injury caused by or resulting from reliance on this information. Freedom under Patent, Copyright and Designs cannot be assumed. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  2. 2. ANHYDROUS AMMONIA: DETERMINATION OF INERT GASES 1 SCOPE AND FIELD OF APPLICATION This packed-column GC method is suitable for the determination of hydrogen, nitrogen, oxygen, argon and carbon monoxide in anhydrous ammonia. The determinations of the gases are linear in the range O-100 ppm v/v. 2 PRINCIPLE The gaseous components of the test sample are separated on the solid phase of a packed chromatographic column, and are then detected by means of a helium ionization detector. Helium carrier gas flows through the detector ionization chamber, where collisions with primary electrons from a g-source occurs. A titrium radioactive source is mounted inside the detector cell. 3 REAGENTS AND MATERIALS 3.1 Carrier gas: Helium with 50 ppm v/v neon. 3.2 Service helium, 5 kg/cm2: used to operate the injection valve. 3.3 Water-free methanol. 3.4 Solid phase column packing: Porapak Q-S, SO-80 mesh. THIS MATERIAL IS HARMFUL BY INHALATION. 3.5 Calibration mixture: Approximately 10 ppm of each component analysed. The mixture must have a certificate guaranteeing the quality of the mixture: This mixture can be obtained from BOC or an alternative source. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  3. 3. 4 APPARATUS 4.1 Gas-chromatograph, having a helium ionization detector, and an amplifier. A Carlo-Erba 3700 model, or similar, is suitable. 4.2 Chromatography column: a 4m x 3 mm OD stainless steel tube, suitably adapted to a suitable size to fit into a 2L vacuum jar. 4.3 Rare gas purifier: a BOC Mk3 model, or similar, is suitable. 4.4 Recorder: 0.1 mv FSD with 1 s response time. 4.5 Flowmeter: O-10 L/hr. 4.6 Vacuum flask: a Dilvac Dewar Flask, model 990/111. or similar, is suitable. 4.7 Refrigeration unit: a Neslab CryoCool CC-80 model, capable of maintaining a cooling temperature of -80oC is suitable. 4.8 Sampling 'bomb' as shown in Figure 2. 4.9 Gas sample valve 4.10 Stop-watch. 5 PROCEDURE 5.1 Preparation of Column Bend the column tubing (4.2) into a suitable size to fit into the vacuum jar; close one end with a glass wool plug and connect this end via a catch-pot to a vacuum pump. Connect a small funnel to the other end, start the pump and fill the column with packing (3.4). vibrating it at the same time. Leave any pumping for a further 15 minutes and make up any fall in level. Switch off the pump, remove the funnel and close the open end of the column with a glass wool plug. Activate the column packing by heating overnight at 230°C in a stream of helium. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  4. 4. 5.2 Operating Conditions Column temperature: - 80°C. Carrier gas Helium containing 50 f- 10 ppm neon Inlet pressure 1.5 kg/cm2 (21.4 psig) Helium service 4 kg/cm2 (57 psig) Excitation voltage Attenuation Helium purifier 380 V 256 Switched on. (Preset by manufacturers at approximately 730oC. Recorder chart speed Injector Sample volume 2mm/min Gas loop 3mL Assemble the components of the chromatograph system as shown diagrammatically. in Figure 1, and check that the operating conditions are correctly set. 5.3 Calibration 5.3.1 Connect the primary calibration mixture cylinder (3.5) to the chromatograph fitted with a suitable exit flow indicator (4.5). 5.3.2 Maintain a purge rate of 3 L/hr through the gas loop, as indicated by the exit flow indicator. 5.3.3 After a period of approximately one minute, change the "LOAD" setting on the sampling valve control to "INJECT" and maintain this setting for exactly 15 seconds, as timed by a stop-watch. (4.10). 5.3.4 Change the setting on the sampling valve control back to "LOAD". 5.3.5 Reduce the flow rate such that it is just showing on the exit flow indicator. The system should be slowly purged. 5.3.6 Increase the flow rate back up to 3 L/hr and repeat the procedure from sub-sections 5.3.2 to 5.3.5 inclusive. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  5. 5. 5.3.7 Continue this procedure until the standards on the recorder (4.4) show good repeatability. Carefully check the consistency of the peaks for oxygen and nitrogen (see Figure 4). 5.4 Sampling REFER TO LABORATORY SAMPLING PROCEDURES MANUAL DOCUMENT: SPL-FE, PROCEDURE NUMBER: 52/1/l FOR SAFETY PRECAUTIONS. 5.4.1 The sampling "bomb" is used for this purpose (Figure 2). This consists of a liquid sample volume V1 and an in-line expansion volume, V2 enclosed by "Hake" ball valves. These volumes are such that the volume, V1 of liquid ammonia, when allowed to vaporize into a total volume of V1 + V 2 gives a gas sample at a pressure of three atmospheres. The test sample is collected as follows: 5.4.2 Connect the vessel to the sample point at the Ermeto coupling (Figure 3) and purge right through with liquid ammonia sample for 30 seconds. Close valve B and allow the liquid in V2 to evaporate. When the pressure in V 2 is almost at atmospheric pressure, close valve C. 5.4.3 Close valve A, open, then shut valve B and finally open valve A. The liquid in V1 will expand into V2. Open valve C again until V2 is almost at atmospheric pressure, then close valve C. 5.4.4 Repeat the purging procedure (5.4.3) eight times. 5.4.5 Take the final sample in the same manner, but leaving valves C and A closed. Close the plant sample point and open the purge line, allowing any ammonia present to rent to atmosphere before disconnecting the sample "bomb". 5.5 Analysis 5.5.1 Connect the outlet of the sample "bomb" to the column inlet by means of a micro-valve coupling. 5.5.2 Place the column in the vacuum flask, as shown in figure 1. Switch on the refrigeration unit and reduce the methanol temperature to - 80°C. Allow 2 hours for the temperature to stabilize. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  6. 6. 5.5.3 Open valve C, with valves A and B still closed, and by means of the needle valve, regulate the flow of test sample through the flow-meter at 3 L/hr for one minute. 5.5.4 Follow the procedure for the section Calibration from subsection 5.3.3 to 5.3.6 inclusive. 5.5.5 Duplicate tests should be run to check for the absence of air which may have diffused into the sample lines. 5.5.6 Typical retention times are as follows: Component Hydrogen Nitrogen Oxygen Argon Carbon Monoxide Retention time 2 mins 5 mins 6 mins 6.5 mins 7.5 mins 6 EXPRESSION OF RESULTS 6.1 Identify each peak by its retention time and measure its height from base line to tip. 6.2 Calculate the concentration of each component by relating this height to the peak heights of the standards. 7 NOTES 7.1 Ammonia will be retained on the column at -80°C, and is likely to break through approximately four hours after injection of the first sample, or after the analysis of approximately 20 samples. 7.2 The column is reactivated by maintaining it at ambient temperature for several hours, and preferably overnight. This process can be expedited by immersing the column in a bath of hot water. 7.3 Small amounts of methane (up to 50 ppm v/v) in the anhydrous ammonia will show up as a broad interference peak. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  7. 7. Figure 1 SCHEMATIC ARRANGEMENT OF CHROMATOGRAPH FOR THE DETERMINATION OF INERT GASES IN ANHYDROUS AMMONIA Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  8. 8. Figure 2 ANHYDROUS AMMONIA SAMPLE “BOMB” Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  9. 9. Figure 3 ANHYDROUS AMMONIA SAMPLE “POINT” Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  10. 10. Figure 4 EXAMPLE STANDARD CHROMATOGRAM FOR CALIBRATION STANDARDS Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  11. 11. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com

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