METHOD AND APPARATUS FOR QUANTITATIVELY ANALYZING A GASEOUS PROCESS STREAM

• US 20190317065A1
• Filed: 10/12/2017
• Published: 10/17/2019
• Est. Priority Date: 10/14/2016
• Status: Active Grant

• Current Assignee: Shell USA Incorporated (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: BLACK, Jesse Raymond, FREELIN, Julie Michelle, OLDFIELD, Richard Kenneth, WARD, Gregory John
• Granted Patent: US 11,408,869 B2
• Time in Patent Office: Days
• CPC Class Codes: B01J 2208/00964 Reactants
• CPC Class Codes: B01J 2219/00247 Fouling of the reactor or the process equipment
• CPC Class Codes: B01J 4/008 Feed or outlet control devices
• CPC Class Codes: B01J 8/0457 the beds being placed in separate reactors
• CPC Class Codes: C07C 31/202 Ethylene glycol
• CPC Class Codes: C07D 317/38 Ethylene carbonate
• CPC Class Codes: G01N 2030/025 Gas chromatography
• CPC Class Codes: G01N 2030/8845 involving halogenated organic compounds
• CPC Class Codes: G01N 2030/8886 Analysis of industrial production processes
• CPC Class Codes: G01N 30/06 Preparation
• CPC Class Codes: G01N 30/24 Automatic injection systems
• CPC Class Codes: G01N 30/68 Flame ionisation detectors
• CPC Class Codes: G01N 30/70 Electron capture detectors
• CPC Class Codes: G01N 30/88 Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
• CPC Class Codes: G01N 33/0006 Calibrating gas analysers

Abstract

The present invention relates to method and an apparatus for quantitatively analyzing a gaseous process stream, in particular a stream from a process for producing ethylene carbonate and/or ethylene glycol, in particular where such stream comprises gaseous organic iodides.

Claims

1. A gas blending system, wherein said gas blending system provides blends of a first gas and a second gas in different mixing ratios, said gas blending system comprising

(a) means for separately controlling the flow rate and/or pressure of a first gas stream supplied to each of two or more flow restrictor devices arranged in parallel, wherein each flow restrictor device has an inlet for receiving and an outlet for discharging a stream of the first gas, wherein said outlet is fluidly connected to means for measuring the pressure of the first gas stream discharged from the flow restrictor device, and wherein the dimensions of the flow restrictor devices are selected such that each of said flow restrictor devices produces a different controlled volumetric flow rate of the first gas stream at the outlet, and

(b) means for controlling the flow rate of a second gas stream supplied to a multi-port flow selector device, wherein said multi-port flow selector device comprises an inlet for receiving and outlets for removing a stream of the second gas at a controlled volumetric flow rate,

(c) a mixing zone located downstream of each flow restrictor device and the multi-port flow selector device, wherein each mixing zone comprises a first inlet for receiving a stream of the first gas from the outlet of the flow restrictor device fluidly connected to it, a second inlet for receiving a stream of the second gas from an outlet of the multi-port flow selector device and an outlet for discharging a blend of the first gas and the second gas.

2. The system according to claim 1, wherein said system further comprises means for selectively splitting off a portion of the first gas stream supplied to a flow restrictor device, said means comprising a branched tubular body arranged upstream of the flow restrictor device, wherein said branched tubular body comprises an inlet for receiving the first gas stream, a first outlet connected to the flow restrictor device and a second outlet connected to an apparatus capable of metered venting of a portion of the first gas stream.

3. An analyzer for quantitatively analyzing the composition of a gaseous process stream, said analyzer comprising

(i) one or more inlets configured to receive a gaseous process stream withdrawn from one or more sample points of a chemical conversion system;

(ii) a gas blending system according to claim 1 or 2, wherein the gas blending system is configured to prepare gas blends for use as calibration standard;

(iii) an analytical apparatus, wherein the analytical apparatus comprises one or more detectors that are sensitive to the components of the gaseous process stream to be analyzed.

4. The analyzer according to claim 3, wherein said analyzer further comprises

(iv) a stream selection system configured to selectively direct samples of the gaseous process stream and of the calibration standard gas blend to an analytical apparatus.

5. The analyzer according to claim 3, wherein the analytical apparatus is a gas chromatography (GC) apparatus equipped with at least one detector that is sensitive to organic halide concentrations in the parts per trillion volume (pptv) range.

6. The analyzer according to claim 3, wherein the analytical apparatus is a gas chromatography (GC) apparatus equipped with a Micro Electron Capture Detector (μ

ECD) and a Flame Ionization Detector (FID).

7. A method for quantitatively analyzing a gaseous process stream comprising one or more gaseous organic halides, said method comprising the steps of

(i) withdrawing a sample of a gaseous process stream from one or more sample points in a chemical conversion process;

(ii) supplying the sample of a gaseous process stream to an analyzer according to any one of claims 3-6;

(iii) determining the concentration of the gaseous organic halides in the gaseous process stream sample,

wherein prior to step (iii) the one or more detectors of the analytical apparatus of the analyzer have been calibrated for the gaseous organic halides to be analyzed.

8. The method according to claim 7, wherein a detector of the analytical apparatus has been calibrated for one or more iodides selected from methyl iodide, ethyl iodide and vinyl iodide.

9. The method according to claim 8, wherein additionally a detector of the analytical apparatus has been calibrated for one or more chlorides selected from methyl chloride, ethyl chloride, and vinyl chloride.

10. The method according to claim 7, wherein the gaseous process stream sample is withdrawn from a process for the conversion of ethylene to ethylene carbonate and/or ethylene glycol.

11. The method according to claim 10, wherein said ethylene conversion process comprises:

contacting at least a portion of a recycle gas stream comprising one or more iodide impurities with one or more guard bed materials in a guard bed vessel to yield a treated recycle gas stream; and

contacting an epoxidation feed gas comprising ethylene, oxygen and at least a portion of the treated recycle gas stream with an epoxidation catalyst in an epoxidation reactor to yield an epoxidation reaction product stream comprising ethylene oxide; and

contacting at least a portion of the epoxidation reaction product stream comprising ethylene oxide in an ethylene oxide absorber with a lean absorbent in the presence of an iodide-containing carboxylation catalyst to yield a fat absorbent stream comprising ethylene carbonate and/or ethylene glycol and the recycle gas stream comprising the one or more iodide impurities.

12. The method according to claim 11, wherein the gaseous process stream sample is withdrawn at one or more points in the epoxidation reaction product stream and/or the recycle gas stream, wherein said sample points are located at one or more of

(i) at or near the outlet of the ethylene oxide absorber;

(ii) at or near the inlet of the first guard bed vessel downstream of the ethylene oxide absorber;

(iii) at or near the outlet of the first guard bed vessel downstream of the ethylene oxide absorber;

(iv) at or near the outlet of each optional guard bed system downstream of said first guard bed vessel;

(v) at or near the outlet of a carbon dioxide absorber, wherein the carbon dioxide absorber is upstream of the ethylene epoxidation reactor;

(vi) at or near the inlet of the ethylene epoxidation reactor;

(vii) at our near the outlet of the ethylene epoxidation reactor.

13. A reaction system for the production of ethylene carbonate and/or ethylene glycol comprising:

a recycle gas loop fluidly connected to a source of ethylene and oxygen;

an epoxidation reactor comprising an epoxidation catalyst, an inlet, and an outlet, wherein the inlet of the epoxidation reactor is fluidly connected to the recycle gas loop;

an ethylene oxide absorber comprising an iodide-containing carboxylation catalyst, an inlet, and an outlet, wherein the outlet of the epoxidation reactor is fluidly connected to the inlet of the ethylene oxide absorber, the outlet of the ethylene oxide absorber is fluidly connected to the recycle gas loop, and the ethylene oxide absorber is configured to produce a recycle gas stream comprising one or more organic halide impurities and a fat absorbent stream comprising ethylene carbonate and/or ethylene glycol;

a first and optionally more guard bed systems downstream of said first guard bed system, each guard bed system comprising an inlet, an outlet and one or more guard bed vessels comprising a guard bed material, wherein the inlet of each guard bed system is fluidly connected to the recycle gas loop, and wherein the guard bed material is configured to remove at least a portion of the one or more organic halide impurities from at least a portion of the recycle gas stream to yield a partially treated recycle gas stream, and

wherein said reaction system comprises one or more gas sampling points located at one or more of

(i) at or near the outlet of the ethylene oxide absorber;

(ii) at or near the inlet of the first guard bed vessel downstream of the ethylene oxide absorber;

(iii) at or near the outlet of the first guard bed vessel downstream of the ethylene oxide absorber;

(iv) at or near the outlet of each optional guard bed system downstream of said first guard bed vessel);

(v) at or near the outlet of a carbon dioxide absorber, wherein the carbon dioxide absorber is upstream of the ethylene epoxidation reactor;

(vi) at or near the inlet of the ethylene epoxidation reactor;

(vii) at our near the outlet of the ethylene epoxidation reactor; and

an analyzer according to claim 3, wherein said one or more sampling points are fluidly connected to said analyzer.

14. A method for calibrating a detector in an analytical apparatus for quantitatively analyzing one or more components in a gaseous stream, comprising the steps of

(i) providing a standard gas, wherein said standard gas contains each of the components to be analyzed in a fixed concentration, and an inert diluent gas;

(ii) feeding the standard gas and the diluent gas to a gas blending system to obtain a diluted standard gas sample having a known concentration;

(iii) feeding the diluted standard gas sample obtained in step (ii) to the analytical apparatus and recording a detector output for said sample;

(iv) repeating steps (ii) and (iii) at least twice in succession to obtain a series of diluted standard gas samples having different concentrations and corresponding detector outputs;

(v) combining the detector outputs for the diluted standard gas samples to generate a calibration curve for the detector,

wherein said gas blending system comprises

(a) means for controlling the flow rate or pressure of the standard gas supplied to two or more different flow restrictor devices arranged in parallel, wherein each flow restrictor device has an inlet for receiving and an outlet for discharging the standard gas, wherein said outlet is fluidly connected to means for measuring the pressure of the standard gas stream discharged from the flow restrictor device, and wherein the dimensions of the flow restrictor devices are selected such that each flow restrictor device produces a different controlled volumetric flow rate of the standard gas at the outlet, and

(b) means for controlling the flow rate of a diluent gas supplied to a multi-port flow selector device, wherein said multi-port flow selector device comprises an inlet for receiving and outlets for removing the diluent gas at a controlled volumetric flow rate,

(c) two or more mixing zones located downstream of the flow restrictor devices and the multi-port flow selector device, wherein each mixing zone comprises a first inlet for receiving standard gas from the outlet of the flow restrictor device fluidly connected to it, a second inlet for receiving diluent gas from an outlet of the multi-port flow selector device and an outlet for discharging a diluted standard gas sample, and

wherein said series of diluted standard gas samples having different concentrations is obtained by,

using the multi-port flow selector device to selectively direct flow of the diluent gas to each of the mixing zones, and by

successively adjusting the volumetric flow rate of the standard gas from the outlet of the flow restrictor device supplied to each mixing zone, and

optionally adjusting the volumetric flow rate of the diluent gas supplied to each of the mixing zones,

to produce a variety of mixing ratios of standard gas and diluent gas.

15. The method according to claim 14, wherein the analytical apparatus comprises a first detector with non-linear response to analyte concentration and a second detector with linear response to analyte concentration,

wherein the analyte concentrations detected by the first detector are lower than the analyte concentrations detected by the second detector and wherein a linear response of the second detector is used to validate the accuracy of the calibration of the first detector.