System for measuring trace oxygen in complex working condition gas based on dilution method

Abstract

The utility model relates to the technical field of analysis of coal gas produced by a Lurgi gasifier gasification process, in particular to a system for measuring trace oxygen in complex working condition gas based on a dilution method, which comprises an isolating valve, a condensation degreaser, a precise pressure regulating valve, a washing tank, a pneumatic valve, a dilution probe and a trace oxygen meter analyzer, one end of the isolating valve is connected with a sample gas inlet, the other end of the isolating valve is connected with a gas inlet of the condensation degreaser, a gas outlet of the condensation degreaser is connected with the precision pressure regulating valve and then is connected with the washing tank, a gas outlet of the washing tank is connected with the pneumatic valve and then is connected with an inlet of the dilution probe, and an outlet of the dilution probe is communicated with the trace oxygen meter analyzer; according to the utility model, a dilution method is combined with an electrochemical oxygen meter to measure the oxygen content in the raw gas, so that the operation failure rate is low, the maintenance cost is low and the use effect is more stable.

Description

Technical Field

[0001] The utility model relates to the technical field of analysis of coal gas produced by Lurgi furnace gasification process, and specifically relates to a system for measuring trace oxygen in complex working condition gas based on a dilution method. Background Art

[0002] In the Lurgi furnace gasification production process, the raw gas components are usually monitored by laboratory manual semi-component and chromatographic full-component analyzers. The laboratory semi-component should use Ostwald gas analyzer, which requires simple equipment and is cheap, but the manual sampling operation process is complicated, the sampling and analysis time is long, the instrument accuracy is not high, and the operator's operating skills affect the accuracy of the analysis results to a certain extent, making it difficult to reflect the working condition information in real time. If the process control is completely based on parameters such as temperature, pressure, and flow, the operation often fails to achieve the optimal working condition due to the influence of uncontrolled factors such as raw material composition and catalyst activity. Therefore, in order to reflect the working condition changes in a timely, continuous, accurate, and real-time manner, only through a set of analysis systems and continuous online analysis can the process control requirements be met. At present, the main methods for analyzing gas components are online analytical instrument analysis, laboratory gas chromatography analysis, and chemical absorption analysis. The main online analytical instruments are industrial gas chromatographs, non-spectroscopic infrared gas analyzers, oxygen analyzers, etc. The coal gas produced by the Lurgi furnace gasification process using flame coal as raw material has a complex composition and contains a large amount of impurities such as coal tar, dust, water, phenol, benzene and sulfide. These impurities will seriously damage the analytical instruments. Therefore, there is no precedent for the use of online analytical instruments to analyze the coal gas produced by the Lurgi furnace gasification process.

[0003] GB6222-2005 "Industrial Enterprise Gas Safety Regulations" 5.1.3.11 stipulates: The oxygen content of each gas generator should be analyzed before the gas is input into the network (or pressurized). If the oxygen content is greater than 1%, it is prohibited to be connected to the network. 5.2.4 stipulates: The oxygen content of water gas (semi-water gas) should be strictly controlled. Generally, an automatic analyzer should be installed, and manual analysis should be carried out for regular spot checks. Under normal circumstances, the gas content of the main pipe should be less than 0.6%; when the gas content of a single furnace system reaches 1%, the furnace must be stopped. Therefore, online O2 content analysis in raw gas is particularly important.

[0004] After a large number of experiments, a corresponding sample gas pretreatment system was designed to remove these impurities. Through comparison, three analytical instruments were combined into an analytical system to achieve continuous online analysis. Utility Model Content

[0005] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a system for measuring trace oxygen in complex working condition gases based on a dilution method.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a system for measuring trace oxygen in complex working conditions gas based on the dilution method, comprising an isolation valve, a condensate deoiler, a precision pressure regulating valve, a water washing tank, a pneumatic valve, a dilution probe and a trace oxygen meter analyzer, wherein one end of the isolation valve is connected to the sample gas inlet, and the other end is connected to the air inlet of the condensate deoiler, the air outlet of the condensate deoiler is connected to the precision pressure regulating valve and then to the water washing tank, the air outlet of the water washing tank is connected to the pneumatic valve and then to the inlet of the dilution probe, and the outlet of the dilution probe is connected to the trace oxygen meter analyzer.

[0007] In some embodiments, the dilution probe is an EPM303 dilution probe.

[0008] In some embodiments, the rear end of the water washing tank is connected to a liquid sealing tank, and the sample gas passes through the water washing tank and the liquid sealing tank in sequence and then is connected to the pneumatic valve.

[0009] In some of the embodiments, a pressure gauge is provided between the precision pressure regulating valve and the water washing tank.

[0010] Compared with the prior art, the beneficial effects of the utility model are: using the dilution method combined with the electrochemical oxygen meter to measure the oxygen content in the raw coal gas, low operating failure rate, low maintenance cost, and more stable use effect are achieved. When a single Lurgi furnace is operating normally, it is necessary to manually sample and analyze the raw coal gas once an hour. Two personnel in the central laboratory workshop cooperate with each other to sample, analyze, and issue reports for the six operating gasification furnaces. The whole process takes about 30 minutes, the workload is large, and the analysis data is seriously delayed. The use of online monitoring can effectively solve the problem of manual sampling lag and improve the accuracy of measurement data.

[0011] Details of one or more embodiments of the present application are presented in the following drawings and descriptions to make other features, purposes and advantages of the present application more concise and easy to understand. The present application is fully described and understood through the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the connection structure of the utility model.

[0013] In the figure: 1. Isolation valve; 2. Oil removal condenser; 3. Precision pressure regulating valve; 4. Water washing tank; 5. Pneumatic valve; 6. Dilution probe; 7. Analyzer; 8. Pressure gauge; 9. Liquid seal tank. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0015] See also Figure 1 The utility model provides a technical solution: a system for measuring trace oxygen in complex working conditions gas based on the dilution method, including an isolation valve, a condensate deoiler, a precision pressure regulating valve, a water washing tank, a pneumatic valve, a dilution probe and a trace oxygen meter analyzer, wherein one end of the isolation valve is connected to the sample gas inlet, and the other end is connected to the air inlet of the condensate deoiler, the air outlet of the condensate deoiler is connected to the precision pressure regulating valve and then connected to the water washing tank, the air outlet of the water washing tank is connected to the pneumatic valve and then connected to the inlet of the dilution probe, and the outlet of the dilution probe is connected to the trace oxygen meter analyzer.

[0016] The dilution probe is an EPM303 dilution probe.

[0017] The rear end of the water washing tank is connected with a liquid sealing tank, and the sample gas passes through the water washing tank and the liquid sealing tank in sequence and then is connected to the pneumatic valve.

[0018] A pressure gauge is provided between the precision pressure regulating valve and the water washing tank.

[0019] Through this technical solution, the sample gas passes through the isolation valve and the super-condensation oil removal device, and is sampled from the existing sampling point. Through rapid cooling, the gaseous oil and water in the flue gas are liquefied, achieving the effect of preliminary oil and water removal;

[0020] The flue gas is controlled to the corresponding pressure by the precision pressure regulating valve and then enters the water washing tank for washing; the flue gas is stabilized by the water seal to ensure the pressure stability of the entire system. The tar in the flue gas is further removed by the water washing device to achieve the purpose of clean oil removal;

[0021] The sample enters the dilution probe through the pneumatic valve and enters the trace oxygen analyzer for gas analysis after dilution is completed; the measured data is valid. The flue gas is extracted to dilute it, and the diluted sample is transported to the analytical instrument through the sampling pipeline in the form of positive pressure for analysis.

[0022] The theoretical basis of the dilution extraction method of the EPM303 dilution probe is the acoustic orifice built into the probe. Its geometric characteristics are that the diameter of the acoustic orifice is much larger than the compression length of the orifice, or the compression length of the orifice is much smaller than the diameter of the orifice. Its fluid characteristics are that when the pressure difference at both ends of the orifice is greater than 0.46 times, the volume flow rate of the gas flowing through the orifice mainly depends on the speed of the gas molecules flowing through the orifice (i.e., the local speed of sound), and has nothing to do with the local temperature and the changes in the air pressure at both ends of the orifice. (i.e., a constant flow is generated). The system relies on a high-precision pressure regulating valve to maintain the pressure at the inlet of the probe dilution air pipe (DA) unchanged, thereby ensuring that the flow rate of the dilution air remains unchanged, and also ensuring that the differential pressure at both ends of the acoustic orifice is more than 0.46 times, while ensuring that the flow rate of the acoustic orifice is constant. The stability of these two flows ensures the constant flow ratio of dilution air and flue gas, thereby achieving a constant dilution ratio.

[0023] Oxygen measurement: Electrochemical method is used to measure oxygen

[0024] The gas circuit system provides a relatively stable sample gas flow to the sensor. The sensor converts the oxygen content in the measured sample gas into a voltage signal and provides it to the signal processing circuit for amplification processing. Then the central single-chip computer performs calculation control and sends it to the display circuit to digitally display the oxygen content; then it is sent to various signal output circuits for analog and digital output. When the oxygen content in the measured sample gas is higher than the upper limit setting value, the normally open contact of the control output relay is closed and the normally closed contact is disconnected. When the oxygen content in the measured sample gas is higher than the alarm point setting value, an alarm will be issued. When the oxygen content in the measured sample gas is lower than the upper limit setting value and the alarm point setting value, the instrument is in normal state.

[0025] It can realize the purification of raw coal gas and the continuous monitoring of trace oxygen and carbon dioxide in raw coal gas, replacing the traditional off-line detection.

[0026] Combined with the actual situation of the project, the Lurgi furnace outlet raw gas online monitoring system has the following significance for the coal-to-gas process and production safety:

[0027] 1. Improve the real-time nature of analytical data: realize 24-hour uninterrupted continuous monitoring, transmit measurement data to the DCS control system, and monitor the carbon dioxide and oxygen content in the raw coal gas at the outlet of the Lurgi furnace in real time.

[0028] 2. Improve the automation level of chemical plants: replace manual sampling and analysis, saving a lot of manpower and material resources.

[0029] 3. Reduce safety hazards: reduce the frequency of manual sampling, reduce the time people stay in the gasification frame, and improve personnel safety

[0030] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for measuring trace oxygen in complex working conditions based on dilution method, characterized in that: It includes an isolation valve, a condensate deoiler, a precision pressure regulating valve, a water washing tank, a pneumatic valve, a dilution probe and a trace oxygen meter analyzer. One end of the isolation valve is connected to the sample gas inlet, and the other end is connected to the air inlet of the condensate deoiler. The air outlet of the condensate deoiler is connected to the precision pressure regulating valve and then to the water washing tank. The air outlet of the water washing tank is connected to the pneumatic valve and then to the inlet of the dilution probe. The outlet of the dilution probe is connected to the trace oxygen meter analyzer.

2. The system for measuring trace oxygen in complex working condition gas based on dilution method according to claim 1 is characterized in that: The dilution probe is an EPM303 dilution probe.

3. The system for measuring trace oxygen in complex working condition gas based on dilution method according to claim 1 is characterized in that: The rear end of the water washing tank is connected with a liquid sealing tank, and the sample gas passes through the water washing tank and the liquid sealing tank in sequence and then is connected to the pneumatic valve.

4. The system for measuring trace oxygen in complex working condition gas based on dilution method according to claim 3 is characterized in that: A pressure gauge is provided between the precision pressure regulating valve and the water washing tank.

Images