Gas Chromatography Analysis Scheme for Fuel Grade Dimethyl Ether Production Process

Gas Chromatography Analysis Scheme for Fuel Grade Dimethyl Ether Production ProcessabstractApplication of packed column gas chromatography for fuel gradeDimethyl ether productsProduction processAnalyze and useQuantification using external standard method or calibration area normalization method.

Dimethyl ether is a colorless and easily liquefied gas, and its production process mainly includes the two-step synthesis process of methanol liquid-phase or gas-phase dehydration, or the one-step process of direct synthesis of synthesis gas. Currently, in China, coal or petroleum and natural gas are mainly used as raw materials to generate water gas for the synthesis of methanol, followed by methanol dehydrationAfter catalytic conversion, dimethyl ether and trace impurities such as carbon monoxide, methane, carbon dioxide, ethylene, ethane, propylene, propane, methanol, and water are generated. For the detection of fuel grade dimethyl ether products, gas chromatography is used, and thermal conductivity and hydrogen flame detectors are used to determine the components in the dimethyl ether products and the methanol, water, exhaust gas, and wastewater in the production process. External standard method or calibration area normalization method is used for quantificationbe used forFuel gradeQuality control analysis of dimethyl ether products.

Our company's researchers have conducted research based onCharacteristics of producing fuel grade dimethyl ether,Develop high-performance detection for dimethyl ether, methanol, and waterGC-7890 gas chromatograph.

inProduct Features:

A 320 × 240 graphic large screen is used to display both Chinese and English, with simple and intuitive parameter settings;

● Comprehensive self diagnostic function, which enables users to conveniently check the location and type of faults;

A reliable anti-interference system ensures that power fluctuations or momentary power outages will not affect the normal operation of the instrument;

Complete temperature overheating protection and platinum resistance open circuit and short circuit alarm functions to ensure that the temperature does not lose control;

● Carrier gas pressure monitoring system to achieve the function of protecting chromatographic columns, TCD, and ECD;

Adopting advanced FLASH memory system, data protection is no longer trapped by battery failure;

The highly stable and sensitive microcurrent amplification technology significantly improves the detection limit of FID;

The new thermal conductivity detector has higher sensitivity;

The instrument can be equipped with a built-in AD conversion circuit for direct digital output of chromatographic signals;

The instrument can be equipped with XS-3000 workstation to complete all control and analysis tasks on a PC;

The instrument pneumatic system can be equipped with electronic flow display;

New pneumatic control valves ensure the repeatability of analysis parameters;

Capillary systems have split and split/non split injection modes;

● Rear door opening technology enables near room temperature operation and 9-stage programmed heating;

The instrument can be equipped with manual/automatic FID and FPD ignition devices;

needInstruments and equipment:

GC-7890 gas chromatograph: dual detector (TCD, FID)/methane converter/dual gas injection system

Stainless steel chromatography column:

Dimethyl ether chromatography column (GDX-502, 25% PEG-1500/porapak Q imported support) (1 piece ￠4＊4m）

ModificationGDX-502 chromatographic column (1 piece ￠4＊2m)

TDX-01 (1 piece ￠3＊2m)

liquid gasSampling steel cylinder(250ml) and sampling bag

Data processing: computer andN-2000Chromatography workstation

Analytical balance (one ten thousandth)

• Reagents and materials:

Carrier gas: high-purity nitrogen, high-purity hydrogen, air（AirRequire no oil, no impurities)

Standard gas:

AConstantCO、CH4、CO2Standard gas

BDimethyl ether product standard gas:CO、CH4、CO2、C2H4、C2H6、C3H6、C3H8、CH3OCH3、CH3OH、H2O.

Chromatographic grade methanol, distilled water

Sample glass instrument: 10ml test tube with stopper, 10ml flask, dropper

• Chromatographic conditions:

Column temperature: 100 ℃ Gasification: 160 ℃ Detection (FID): 140 ℃ Thermal conductivity: 140 ℃ Bridge current: 140mA

Flow rate: 35ml/min Sample: Standard

Testing items：

1. Raw material methanol detection:

The raw material methanol is mainly used to detect water in methanol. A thermal conductivity detector is used, and a modified GDX-502 chromatographic column is used for separation. The area correction normalization method is used for quantification, and the injection volume is 1ul. The analysis spectrum is as follows:

2. Gasification tower kettle liquid analysis:

useThermal conductivity detector detection,Separation of gasification tower kettle liquid using modified GDX-502 chromatographic columnMethanol, waterPerform detection, quantify by area correction normalization method, inject 1ul, and analyze the spectrum as follows:

3. Distillation tower kettle liquid analysis:

useThermal conductivity detector detection,Separation of dimethyl ether distillation tower kettle liquid using modified GDX-502 chromatographic columnDimethyl ether, methanol, waterPerform detection, quantify by area correction normalization method, inject 1ul, and analyze the spectrum as follows：

4. Analysis of exhaust gas from alcohol washing tower:

(1) Exhaust gas includes constantsCarbon monoxide, methane, carbon dioxideuseThermal conductivity detector detection,Separate using TDX-01 chromatographic column, quantify by area external standard method, inject 1ml, and analyze the spectrum as follows:

(2) Exhaust gas also includesEthylene, ethane, propylene, propane, dimethyl ether, methanol, and water,Separate using a dimethyl ether column and heat treatment

Lead detector detection,Quantitative analysis was performed using the external standard method with an injection volume of 1ml. The column temperature was lowered to 80 ℃, and the analysis spectrum is shown below:

5、Discharge of wastewater:

Mainly detecting ppm methanol in discharged wastewater, usingHydrogen flame detector detection,Separation was performed using a modified GDX-502 chromatographic column, quantified by area external standard method, with an injection volume of 1ul. The analysis spectrum is shown below:

6Analysis of fuel grade dimethyl ether products:

The analysis of the content of fuel grade dimethyl ether products mainly involves the determination of trace impurities, water, and methanol. The products are separated using a dimethyl ether column and detected using a thermal conductivity detector,The area correction normalization method was used for quantification, with an injection volume of 1ml. The analysis spectrum is shown below: