Method for confirming and analyzing unknown components of ammonia synthesis gas

Abstract

The invention belongs to the technical field of ammonia synthesis, and particularly relates to a method for confirming and analyzing unknown components of ammonia synthesis gas. According to the method, a Hayesep Q column is adopted for pre-separation, NH3 or possible harmful gas is removed, H2 is used as carrier gas, detection is carried out after separation is carried out on a Porapak Q column and a 5A molecular sieve column, the peak appearance position of unknown gas is obtained, according to the separation characteristic of the 5A molecular sieve column, the possible gas type is judged, then qualitative confirmation is carried out through standard gas, and qualitative recognition of the unknown component Ne in the ammonia synthesis gas is achieved. The contents of Ne, Ar, N2 and CH4 in the ammonia synthesis gas are accurately determined under the conditions; meanwhile, a Hayesep Q column is adopted for pre-separation, N2 serves as carrier gas, detection is conducted after separation is conducted through a 5A molecular sieve column, and the content of H2 in the ammonia synthesis gas can be accurately measured. And process production is guided in time according to the measured content of each component, production conditions are optimized, and a positive contribution is made to efficient and stable operation of the synthetic tower.

Description

Technical Field

[0001] The invention belongs to the technical field of ammonia synthesis, and in particular relates to a method for confirming and analyzing unknown components of ammonia synthesis gas. Background Art

[0002] At present, the synthetic ammonia production device uses coal as raw material, which is burned in the Shell coal gasification device under oxygen and reduced to generate raw coal gas. After dust removal, washing and purification, the raw coal gas is transformed in the synthesis conversion device, and then washed with methanol and liquid nitrogen to become fresh synthesis gas mainly containing H2 and N2; it is mixed with N2 produced by the air separation device in the ratio of (H2: N2 = 3: 1), compressed and synthesized in the synthesis tower, and produces gaseous NH3 or condensed into liquid ammonia products.

[0003] In order to regulate the production status of the synthesis tower and the synthesis efficiency of ammonia, it is necessary to analyze the synthesis gas at the outlet and inlet of the synthesis tower, that is, to determine the content of H2, Ar, N2, CH4 and NH3 in the outlet and inlet gas of the synthesis tower. In the detection, it was found that there was always an unknown peak before the Ar peak. Ar, CH4 and unknown gases in the synthesis gas are impurity gases, and they do not participate in the chemical reaction of ammonia synthesis. Therefore, they gradually accumulate in the ammonia synthesis loop, causing the content of impurity gases in the circulating gas to increase, which will consume the cycle compression work and consume more energy. It is necessary to discharge part of the circulating gas from time to time to maintain a lower impurity gas concentration in the synthetic ammonia loop. Of course, when discharging, the effective gases H2 and N2 will also be discharged together, which will cause certain economic losses. Therefore, accurately and completely measuring the content of each component in the synthesis gas at the outlet and inlet of the synthesis tower is a condition to ensure the efficient operation of the synthesis tower. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for confirming and analyzing unknown components of ammonia synthesis gas. The present invention first confirms the unknown components, and the analysis method can accurately determine the content of each component in the synthesis gas at the outlet and inlet of the ammonia synthesis tower.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for confirming unknown components of ammonia synthesis gas, wherein the ammonia synthesis gas includes outlet gas or inlet gas of a synthesis tower, and the preparation of the initial ammonia synthesis gas includes: using coal as a raw material, generating raw coal gas through underoxygen combustion, and then obtaining the initial ammonia synthesis gas after dust removal, washing, gas conversion, methanol washing, and liquid nitrogen washing. Ammonia is synthesized in a synthesis tower, and the method for confirming the unknown components includes the following steps:

[0007] Performing a first gas chromatography analysis on the ammonia synthesis gas to be tested to obtain a first spectrum of the ammonia synthesis gas to be tested, comparing the retention time with the standard gas spectrum, confirming that the ammonia synthesis gas to be tested contains Ar, N2 and CH4, and an unknown peak appears before Ar in the first spectrum of the ammonia synthesis gas to be tested;

[0008] Perform a second gas chromatography analysis on the Ne-containing standard gas and the ammonia synthesis gas to be tested, respectively, to obtain a Ne standard gas spectrum, and compare the retention time with the second spectrum of the ammonia synthesis gas to be tested to confirm that the unknown peak is a Ne peak;

[0009] The conditions of the first gas chromatography analysis include: using hydrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80° C., the column oven temperature is 45-55° C., and the detector temperature is 140-160° C.;

[0010] The conditions of the second gas chromatography analysis include: using helium as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

[0011] Preferably, the conditions for the first gas chromatography analysis also include: a hydrogen flow rate of 18.0 mL / min and a reference flow rate of 30 mL / min.

[0012] Preferably, the Hayesep Q columns used in the first gas chromatography analysis and the second gas chromatography analysis are both 6 feet×1 / 8″ stainless steel packed columns.

[0013] Preferably, the Porapak Q columns used in the first gas chromatography analysis and the second gas chromatography analysis are both 6 feet×1 / 8″ stainless steel packed columns.

[0014] Preferably, the 5A molecular sieve columns used in the first gas chromatography analysis and the second gas chromatography analysis are both W070521, 2.74 m long, 1 / 8″, 2 mm.

[0015] Preferably, the injection port temperature of the first gas chromatography analysis and the second gas chromatography analysis are both 70°C.

[0016] Preferably, the column oven temperatures of the first gas chromatography analysis and the second gas chromatography analysis are both 50°C.

[0017] Preferably, the detector temperature of the first gas chromatography analysis and the second gas chromatography analysis are both 150°C.

[0018] The present invention also provides an ammonia synthesis gas analysis method, comprising the following steps:

[0019] The ammonia synthesis gas to be tested is subjected to a third gas chromatography analysis to obtain the peak areas of Ne, Ar, N2 and CH4, and the contents of Ne, Ar, N2 and CH4 are obtained according to a predetermined standard curve respectively;

[0020] The ammonia synthesis gas to be tested is subjected to a fourth gas chromatography analysis to obtain the peak area of ​​H2, and the H2 content is obtained according to a predetermined standard curve;

[0021] The conditions of the third gas chromatography analysis are the same as the conditions of the first gas chromatography analysis in the method for confirming unknown components of ammonia synthesis gas described in the above technical solution;

[0022] The conditions of the fourth gas chromatography analysis include: using nitrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, separating it on a 5A molecular sieve column, and detecting it with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

[0023] Preferably, the conditions for the fourth gas chromatography analysis also include: a nitrogen flow rate of 22.4 mL / min and a reference flow rate of 35 mL / min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention adopts Hayesep Q column for pre-separation to remove NH3 or other possible harmful gases, uses H2 as carrier gas, and detects after separation on Porapak Q column and 5A molecular sieve column to obtain the peak position of unknown gas. According to the separation characteristics of 5A molecular sieve column, the possible gas type is judged, and then the standard gas is used for qualitative confirmation, thereby solving the problem of identification and qualitative analysis of unknown components (Ne) in ammonia synthesis gas.

[0026] The present invention uses a Hayesep Q column for pre-separation in channel A to remove NH3 or other possible harmful gases, uses H2 as a carrier gas, and detects after separation by a Porapak Q column and a 5A molecular sieve column, and can accurately determine the content of each component of Ne, Ar, N2, and CH4 in the ammonia synthesis gas at the outlet and inlet of the synthesis tower; uses a Hayesep Q column for pre-separation in channel B to remove NH3 or other possible harmful gases, uses N2 as a carrier gas, and detects after separation by a 5A molecular sieve column, and can accurately determine the content of H2 in the ammonia synthesis gas at the outlet and inlet of the synthesis tower. According to the determined content of each component, timely guide the process production and optimize the production conditions, and make positive contributions to the efficient and stable operation of the synthesis tower. The analysis method of the present invention has good separation effect of each component, fast analysis speed, and precision of the analysis result RSD%≤0.27, and the measurement result meets the requirements of analysis and inspection. In the production of synthetic ammonia, it makes positive contributions to optimizing the production conditions of the synthesis tower, and has broad application prospects and promotion value in similar enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is the flow chart of the A and B channel valve switching of the Agilent 6890N gas chromatograph;

[0029] Figure 2 This is the chromatogram of channel A of the outlet gas of a synthesis tower 105D;

[0030] Figure 3 This is the Ne standard gas chromatogram when He is used as carrier gas;

[0031] Figure 4 This is the gas chromatogram at the 105D outlet when He is used as the carrier gas;

[0032] Figure 5 When using He as carrier gas, high purity H2 chromatogram is used;

[0033] Figure 6 This is a chromatographic calibration table using H2 gas as carrier gas;

[0034] Figure 7 This is the Ne standard gas chromatogram using H2 gas as carrier gas;

[0035] Figure 8 This is a chromatogram of the analysis results of the synthesis gas at the outlet of a synthesis tower. DETAILED DESCRIPTION

[0036] The present invention provides a method for confirming unknown components of ammonia synthesis gas, wherein the ammonia synthesis gas includes outlet gas or inlet gas of a synthesis tower, and the preparation of the initial ammonia synthesis gas includes: using coal as a raw material, generating raw coal gas through underoxygen combustion, and then obtaining the initial ammonia synthesis gas after dust removal, washing, gas conversion, methanol washing, and liquid nitrogen washing. Ammonia is synthesized in a synthesis tower, and the method for confirming the unknown components includes the following steps:

[0037] Performing a first gas chromatography analysis on the ammonia synthesis gas to be tested to obtain a first spectrum of the ammonia synthesis gas to be tested, comparing the retention time with the standard gas spectrum, confirming that the ammonia synthesis gas to be tested contains Ar, N2 and CH4, and an unknown peak appears before Ar in the first spectrum of the ammonia synthesis gas to be tested;

[0038] Perform a second gas chromatography analysis on the Ne-containing standard gas and the ammonia synthesis gas to be tested, respectively, to obtain a Ne standard gas spectrum, and compare the retention time with the second spectrum of the ammonia synthesis gas to be tested to confirm that the unknown peak is a Ne peak;

[0039] The conditions of the first gas chromatography analysis include: using hydrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80° C., the column oven temperature is 45-55° C., and the detector temperature is 140-160° C.;

[0040] The conditions of the second gas chromatography analysis include: using helium as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

[0041] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0042] In the present invention, the initial ammonia synthesis gas preferably also includes N2 produced by an air separation unit.

[0043] The present invention performs a first gas chromatography analysis on the ammonia synthesis gas to be tested to obtain a first spectrum of the ammonia synthesis gas to be tested, compares the retention time with the standard gas spectrum, confirms that the ammonia synthesis gas to be tested contains Ar, N2 and CH4, and an unknown peak appears before Ar in the first spectrum of the ammonia synthesis gas to be tested;

[0044] The conditions of the first gas chromatography analysis include: using hydrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

[0045] In the present invention, the specification of the Hayesep Q column in the first gas chromatography analysis is preferably 6 feet×1 / 8″ (OD), a stainless steel packed column. The ammonia synthesis gas to be measured is pre-separated from NH3 and impurity gases in the Hayesep Q column.

[0046] In the present invention, the specification of the Porapak Q column in the first gas chromatography analysis is preferably 6 feet×1 / 8″ (OD), a stainless steel packed column. The Porapak Q column mainly separates CO2 and other hydrocarbons to prevent possible CO2 from entering the subsequent 5A molecular sieve, causing the 5A molecular sieve to fail prematurely.

[0047] In the present invention, the 5A molecular sieve column in the first gas chromatography analysis is preferably an Agilent 5A molecular sieve packed column, preferably model W070521, 2.74m long, 1 / 8″, 2mm. The 5A molecular sieve column can separate permanent gases and inert gases.

[0048] In the present invention, in the first gas chromatography analysis, the injection port temperature is preferably 70°C, the column oven temperature is preferably 50°C, and the detector temperature is preferably 150°C.

[0049] In the present invention, the conditions of the first gas chromatography analysis preferably also include: a hydrogen flow rate of 18.0 mL / min and a reference flow rate of 30 mL / min.

[0050] After confirming that an unknown peak appears before Ar in the first spectrum of the ammonia synthesis gas to be tested, the present invention performs a second gas chromatography analysis on the Ne-containing standard gas and the ammonia synthesis gas to be tested, respectively, to obtain a Ne standard gas spectrum, and compares the retention time with the second spectrum of the ammonia synthesis gas to be tested, confirming that the unknown peak is a Ne peak;

[0051] The conditions of the second gas chromatography analysis include: using helium as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

[0052] In the present invention, the specification of the Hayesep Q column in the second gas chromatography analysis is preferably 6 feet × 1 / 8 "(OD), stainless steel packed column; the specification of the Porapak Q column is preferably 6 feet × 1 / 8 "(OD), stainless steel packed column; the 5A molecular sieve column is preferably Agilent 5A molecular sieve packed column, model is preferably W070521, length 2.74m, 1 / 8", 2mm.

[0053] In the present invention, in the second gas chromatography analysis, the injection port temperature is preferably 70°C, the column oven temperature is preferably 50°C, and the detector temperature is preferably 150°C.

[0054] The present invention uses different carrier gases to perform gas chromatography analysis to confirm unknown components, and the result is accurate and reliable.

[0055] The present invention also provides an ammonia synthesis gas analysis method, comprising the following steps:

[0056] The ammonia synthesis gas to be tested is subjected to a third gas chromatography analysis to obtain the peak areas of Ne, Ar, N2 and CH4, and the contents of Ne, Ar, N2 and CH4 are obtained according to a predetermined standard curve respectively;

[0057] The ammonia synthesis gas to be tested is subjected to a fourth gas chromatography analysis to obtain the peak area of ​​H2, and the H2 content is obtained according to a predetermined standard curve;

[0058] The conditions of the third gas chromatography analysis are the same as the conditions of the first gas chromatography analysis in the method for confirming unknown components of ammonia synthesis gas described in the above technical solution;

[0059] The conditions of the fourth gas chromatography analysis include: using nitrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, separating it on a 5A molecular sieve column, and detecting it with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

[0060] In the present invention, the specification of the Hayesep Q column in the fourth gas chromatography analysis is preferably 6 feet×1 / 8″ (OD), a stainless steel packed column; the 5A molecular sieve column is preferably an Agilent 5A molecular sieve packed column, preferably model W070521, 2.74 m long, 1 / 8″, 2 mm.

[0061] In the present invention, in the fourth gas chromatography analysis, the injection port temperature is preferably 70°C, the column oven temperature is preferably 50°C, and the detector temperature is preferably 150°C.

[0062] In the present invention, the conditions for the fourth gas chromatography analysis preferably also include: a nitrogen flow rate of 22.4 mL / min and a reference flow rate of 35 mL / min.

[0063] In the present invention, the contents of Ne, Ar, N2 and CH4 are obtained, and the predetermined standard curves used all take the concentration of the standard gas as the horizontal coordinate and the peak area corresponding to the standard gas as the vertical coordinate.

[0064] In the present invention, the concentration of Ne standard gas is preferably 3.9533% mole±0.2% rel, N2 balance gas; the concentration of Ar standard gas is preferably 2.92% mole±0.2% rel, N2 balance gas; the concentration of N2 standard gas is preferably 21%, H2 balance gas; the concentration of CH4 standard gas is preferably 2.0%, N2 balance gas.

[0065] In the present invention, the method for obtaining the contents of Ne, Ar, N2 and CH4 is preferably an external standard method.

[0066] In the present invention, the H2 content is obtained by using a predetermined standard curve with the concentration of the H2 standard gas as the horizontal coordinate and the peak area corresponding to the standard gas as the vertical coordinate.

[0067] In the present invention, the concentration of H2 standard gas is preferably 65.0%, and N2 balance gas.

[0068] In the present invention, the method for obtaining the H2 content is preferably an external standard method.

[0069] The present invention determines the content of useless components in the synthesis gas at the inlet and outlet of the ammonia synthesis tower, and can determine whether it is necessary to start the discharge, and understand the changes in the production device.

[0070] In order to further illustrate the present invention, the unknown component identification and analysis method of ammonia synthesis gas provided by the present invention is described in detail below in combination with the accompanying drawings and examples, but they should not be understood as limiting the scope of protection of the present invention.

[0071] In the embodiment of the present invention, the main instruments and configurations, main carrier gases and standard gases used are as follows:

[0072] 1) Agilent 6890N gas chromatograph: manufactured by Agilent Technologies (China) Co., Ltd., USA, model 6890N; equipped with Agilent 6890N chemical workstation. Stationary phase: Hayesep Q, Hayesep Q, Porapak Q, 5A, 5A, a total of five columns. 2 Hayesep Q columns are the same, with specifications of 6 feet × 1 / 8″ (OD), stainless steel filling columns; manufacturer: Lanzhou Zhongke Kaidi Chemical New Technology Co., Ltd. Porapak Q, specifications of 6 feet × 1 / 8″ (OD), stainless steel filling columns; manufacturer: Lanzhou Zhongke Kaidi Chemical New Technology Co., Ltd. 2 5A molecular sieve columns, model W070521, length 2.74m, 1 / 8″, 2mm, Agilent 5A special molecular sieve filling columns. 2 channels, equipped with 2 TCD detectors.

[0073] Figure 1The figure is the valve switching flow chart of the A and B channels of the Agilent 6890N gas chromatograph, and Table 1 is the valve cutting time. In the Agilent 6890N gas chromatograph, the synthetic gas sample is replaced and quantified in the two quantitative tubes of the A and B channels respectively, and then sent to the Hayesep Q by the carrier gas for pre-separation to remove NH3 or other possible harmful gases. The A channel (front channel) uses H2 as the carrier gas, and after switching valves 3 and 2, Ne, Ar, N2, and CH4 are separated in the Porapak Q and 5A molecular sieve columns. The B channel (back channel) uses N2 as the carrier gas, and after switching valve 1, H2 is separated in the 5A molecular sieve column. The data is processed in the Agilent 6890N chemical workstation after detection by the thermal conductivity cell detector. The contents of H2, Ne, Ar, N2, and CH4 are calculated by the peak area external standard method.

[0074] Table 1 Synthetic tower synthesis gas analysis method valve cutting time

[0075] Time (min) Specified matters parameter Settings 0.01 valve 1 Open 0.01 Signal 2 Import side Post-detector 0.95 valve 1 closure 1.50 valve 3 Open 1.85 Signal 2 Import side Front detector 3.20 valve 2 Open 7.00 valve 3 closure 7.05 valve 2 closure

[0076] 2) Main carrier gas and some standard gas:

[0077] High purity N2: carrier gas, 99.999%, GB / T 8972-2008;

[0078] High purity H2: carrier gas, 99.999% GB / T 3634.2-2011;

[0079] High purity He: carrier gas, 99.999% GB / T4844-2011;

[0080] Ne standard gas: Beijing Helium Gas Industry Co., Ltd., Ne = 3.9533% mole ± 0.2% rel, N2 balance gas.

[0081] Example 1

[0082] 1. According to the analysis process and working conditions of Agilent 6890N gas chromatograph, the outlet gas of a synthesis tower 105D was tested and analyzed. The main chromatographic working conditions include:

[0083] 1) Temperature conditions: front inlet 70°C, rear inlet 70°C, column oven 50°C, two TCD detectors both at 150°C.

[0084] 2) Carrier gas and flow rate: Channel A, high-purity H2 as carrier gas, 18.0 mL / min, reference flow rate 30 mL / min; Channel B, high-purity N2 as carrier gas, 22.4 mL / min, reference flow rate 35 mL / min.

[0085] Figure 2This is the chromatogram of channel A of the outlet gas of a certain synthesis tower 105D. The measurement results of the outlet gas of a certain synthesis tower 105D are shown in Table 2.

[0086] Table 2 Analysis and determination results of gas at the outlet of a synthesis tower 105D (volume content, v / v%)

[0087]

[0088] In Table 2, the retention time of the unidentified component X is 3.041 min, which is an unknown component and was once identified as a He peak. However, after analysis and verification, the component is not He and needs to be qualitatively confirmed.

[0089] 2. Qualitative analysis of unknown components

[0090] 1) Determination of retention time of X (unknown) peak: Syngas sample uses H2 as carrier gas in channel A (front channel), and after switching between valve 3 and valve 2, Ar, N2, and CH4 (not necessarily contained or with very low content) are separated on Porapak Q and 5A molecular sieve columns. However, a small peak appears before Ar, which is tentatively designated as X peak, with a retention time of t R =3.042min, such as Figure 2 shown.

[0091] 2) Qualitative analysis of possible components of peak X (unknown)

[0092] Since He, Ne, and Ar are all inert gases, under the same conditions, they emit peaks in the order of boiling points, with low-boiling-point components emitting peaks first and high-boiling-point components emitting peaks later. The boiling point increases with the increase of atomic weight, that is, the peak with a small molecular weight emits peaks first. 5A molecular sieve can separate permanent gases and inert gases. Therefore, when using H2 as a carrier gas, under the same conditions, the peak that can be emitted on 5A molecular sieve and whose retention time is before Ar may be He (M He =2) or Ne(M Ne =10)gas.

[0093] 3) Use He as carrier gas to determine the name of the X (unknown) peak

[0094] Use He as carrier gas, introduce Ne standard gas sample, keep valve 2 open, directly introduce 5A molecular sieve, and then enter TCD detection. Figure 3 This is the Ne standard gas chromatogram when He is used as the carrier gas. The standard Ne peak t R =4.33min. Under the same conditions, the outlet gas sample of 105D was injected. Figure 4 This is the gas chromatogram of 105D outlet when He is used as carrier gas. R =4.34min also has a peak.

[0095] Figure 4 Medium R=3.708min The inverted peak was speculated to be the H2 peak, which was verified using high-purity H2. Figure 5 This is a chromatogram of high-purity H2 when using He as the carrier gas.

[0096] According to the chromatogram Figures 3 to 5 , it can be seen that with He as carrier gas, at the same retention time t R =4.34min, all the unknown components can emit peaks, indicating that the X (unknown) substance is not He, but Ne.

[0097] Example 2

[0098] Debug the chromatograph and set the valve operating conditions to be consistent with Table 1.

[0099] Chromatography restored H2 as carrier gas, debugged analysis method, restored normal operating conditions, introduced standard gas, and made calibration table

[0100] According to the Agilent 6890N operation manual, prepare the calibration table. Figure 6 Ne standard gas was introduced, and the new analysis method was named "New Synthesis Tower Synthesis Gas Analysis Method". Single-point calibration was used, and the correlation met the requirements (multi-point calibration could also be used as needed).

[0101] Figure 6 This is a chromatographic calibration table using H2 as carrier gas. Figure 7 This is a chromatogram using H2 gas as carrier gas and Ne standard gas.

[0102] Example 3

[0103] 1. Use a closed sampler to take the synthesis gas sample from the outlet of synthesis tower 105D, and use the "New Synthesis Tower Synthesis Gas Analysis Method" to analyze the sample. Figure 8 This is the chromatogram of the analysis results of the synthesis gas at the outlet of the synthesis tower.

[0104] 2. Precision experiment

[0105] Five samples of synthesis gas from the outlet of synthesis tower 105D were taken continuously, and the samples were analyzed using the “new synthesis tower synthesis gas analysis method”. The data are shown in Table 3.

[0106] Table 3 Analysis results of synthesis gas at the outlet of synthesis tower 105D (volume content, v / v%)

[0107]

[0108]

[0109] As can be seen from Table 3, the analysis results of the synthesis gas at the outlet of the synthesis tower 105D measured by the "new synthesis tower synthesis gas analysis method" are RSD%≤0.27, the analysis results have good precision, and the measurement results meet the requirements of analytical inspection.

[0110] 3. Influencing factors and control measures during the measurement process

[0111] 1) Stability of the chromatographic column

[0112] The three chromatographic columns Porapak Q, 5A, and 5A installed in the Agilent 6890N chromatograph are the main chromatographic columns for sample separation in chromatography. The quality of their status directly affects the accuracy and reliability of the analysis results. Therefore, these chromatographic columns should be aged or replaced regularly according to the separation effect during use to ensure normal peak output.

[0113] 2) Detector

[0114] In the Agilent 6890N chromatography analysis, the sensitivity of the TCD detector will also have a certain impact on the analysis results, and heat treatment is also required during breaks in use.

[0115] 3) Strictly control the instrument injection port, column temperature, and detector temperature. Temperature has an important impact on the analysis results and operations should be performed at the specified temperature.

[0116] 4) Strictly control the carrier gas pressure. If the pressure is unstable, it will affect parameters such as the carrier gas flow rate and the retention time of the components, resulting in inaccurate measurement results.

[0117] The present invention uses a Hayesep Q column for pre-separation in the chromatographic channel A to remove NH3 or other possible harmful gases, uses H2 as a carrier gas, and detects after separation by a Porapak Q column and a 5A molecular sieve column to determine the peak position of the unknown gas, and judges the possible gas type according to the separation characteristics of the 5A molecular sieve column, and then uses a standard gas for qualitative confirmation, thereby solving the identification and qualitative analysis of the unknown component (Ne) in the ammonia synthesis gas. The above conditions are then used to accurately determine the contents of Ne, Ar, N2, and CH4 in the ammonia synthesis gas; a Hayesep Q column is used for pre-separation in the chromatographic channel B, and N2 is used as a carrier gas, and detection is performed after separation by a 5A molecular sieve column, so that the H2 content in the ammonia synthesis gas can be accurately determined. According to the determined contents of each component, timely guidance of process production and optimization of production conditions are made, which actively contributes to the efficient and stable operation of the synthesis tower.

[0118] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for confirming unknown components of ammonia synthesis gas, wherein the ammonia synthesis gas includes outlet gas or inlet gas of a synthesis tower, and the preparation of the initial ammonia synthesis gas includes: Coal is used as a raw material, and raw coal gas is generated by under-oxygen combustion. After dust removal, washing, gas shift, methanol washing, and liquid nitrogen washing, initial ammonia synthesis gas is obtained, and ammonia is synthesized in a synthesis tower. The method for confirming unknown components includes the following steps: Performing a first gas chromatography analysis on the ammonia synthesis gas to be tested to obtain a first spectrum of the ammonia synthesis gas to be tested, comparing the retention time with the standard gas spectrum, confirming that the ammonia synthesis gas to be tested contains Ar, N2 and CH4, and an unknown peak appears before Ar in the first spectrum of the ammonia synthesis gas to be tested; Perform a second gas chromatography analysis on the Ne-containing standard gas and the ammonia synthesis gas to be tested, respectively, to obtain a Ne standard gas spectrum, and compare the retention time with the second spectrum of the ammonia synthesis gas to be tested to confirm that the unknown peak is a Ne peak; The conditions of the first gas chromatography analysis include: using hydrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80° C., the column oven temperature is 45-55° C., and the detector temperature is 140-160° C.; The conditions of the second gas chromatography analysis include: using helium as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, then entering a Porapak Q column and a 5A molecular sieve column for separation, and detecting with a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

2. The unknown component confirmation method according to claim 1, characterized in that: The conditions of the first gas chromatography analysis also include: a hydrogen flow rate of 18.0 mL / min and a reference flow rate of 30 mL / min.

3. The unknown component confirmation method according to claim 1 or 2, characterized in that: The Hayesep Q columns used in the first gas chromatography analysis and the second gas chromatography analysis were both 6 feet×1 / 8″ stainless steel packed columns.

4. The unknown component confirmation method according to claim 1, characterized in that: The Porapak Q columns used in the first gas chromatography analysis and the second gas chromatography analysis are both 6 feet×1 / 8″ stainless steel packed columns.

5. The unknown component confirmation method according to claim 1, characterized in that: The 5A molecular sieve columns used in the first gas chromatography analysis and the second gas chromatography analysis were both W070521, 2.74 m long, 1 / 8″, 2 mm.

6. The unknown component confirmation method according to claim 1, characterized in that: The injection port temperature of the first gas chromatography analysis and the second gas chromatography analysis is 70°C.

7. The unknown component confirmation method according to claim 1 or 6, characterized in that: The column oven temperature of the first gas chromatography analysis and the second gas chromatography analysis is 50°C.

8. The unknown component confirmation method according to claim 1 or 6, characterized in that: The detector temperature of the first gas chromatography analysis and the second gas chromatography analysis are both 150°C.

9. An ammonia synthesis gas analysis method, characterized in that: The following steps are involved: The ammonia synthesis gas to be tested is subjected to a third gas chromatography analysis to obtain the peak areas of Ne, Ar, N2 and CH4, and the contents of Ne, Ar, N2 and CH4 are obtained according to a predetermined standard curve respectively; The ammonia synthesis gas to be tested is subjected to a fourth gas chromatography analysis to obtain the peak area of ​​H2, and the H2 content is obtained according to a predetermined standard curve; The conditions of the third gas chromatography analysis are the same as the conditions of the first gas chromatography analysis in the method for confirming unknown components of ammonia synthesis gas according to any one of claims 1 to 8; The conditions of the fourth gas chromatography analysis include: using nitrogen as carrier gas, pre-separating the ammonia synthesis gas to be tested on a Hayesep Q column, separating it on a 5A molecular sieve column, and detecting it on a thermal conductivity cell detector; the injection port temperature is 60-80°C, the column oven temperature is 45-55°C, and the detector temperature is 140-160°C.

10. The analysis method according to claim 9, characterized in that The conditions for the fourth gas chromatography analysis also include: a nitrogen flow rate of 22.4 mL / min and a reference flow rate of 35 mL / min.

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