A variable pressure oxygen analysis system

Abstract

The utility model discloses a kind of variable pressure oxygen analysis systems, belong to chemical waste gas detection technology.In the system, sample gas after pretreatment unit is transported to magnetic oxygen analyzer after coalescing filter, pneumatic valve PV02, pressure reducing valve PR02, pneumatic valve PV02 includes leading out a pipeline to be transported to magnetic oxygen analyzer across pressure reducing valve PR02;Coalescing filter includes being connected with back gas pipeline, vacuum generator is set on back gas pipeline;Vacuum generator has a pipeline connection instrument air main pipe to realize air intake, the pipeline is provided with pneumatic valve PV01, and the pneumatic valve PV01 is used to control to provide instrument air for vacuum generator;The system is provided with pressure gauge on the pipeline of sample gas before entering pretreatment unit, and pressure gauge feeds back the sample gas pressure detected to PLC control unit, and provides driving gas to the pneumatic valve by controlling solenoid valve to control, to realize the switching of pneumatic valve.

Description

Technical Field

[0001] This utility model belongs to the field of chemical waste gas detection technology, specifically involving a pressure swing oxygen analysis system. Background Technology

[0002] In the petrochemical industry, waste gases are generally hazardous, and proper disposal is a crucial technology. Flare gases are characterized by their diverse and complex composition, high boiling point, high toxicity, flammability, wide concentration range, and inconsistent emission time intervals. Therefore, flare gas online monitoring systems must meet basic requirements such as the ability to measure a wide range of gas components, a large measurement range, leak prevention, ease of maintenance, fast response time, suitability for use in hazardous areas, and representative monitoring data.

[0003] Sampling of exhaust gas emitted from petrochemical flares typically involves inserting a probe into the exhaust pipe of the flare for extraction. If necessary, an air pump is required to provide pressure. However, simple sampling can cause harmful substances or other deposits in the exhaust gas to accumulate in the pipe or probe, which can lead to blockage of the pipe over time and affect the subsequent detection results.

[0004] When detecting exhaust gas during the operation of the oven, the process of exhaust gas pressure change needs to be considered. Existing detection and analysis systems cannot meet the dynamic adjustment and control requirements of pressure changes and detection pipeline design. Therefore, they are not very suitable for exhaust gas detection in the special working environment of the oven. Utility Model Content

[0005] The present invention aims to provide a pressure swing oxygen analysis system that can meet the requirements for collecting and analyzing oxygen under pressure changes in furnace exhaust gas.

[0006] Technical solution: A pressure swing oxygen analysis system, including a sampling device, which acquires sample gas and connects to a pretreatment unit via a heat tracing pipeline. The pretreatment unit includes a gas-liquid separator and a tube cooler. The gas-liquid separator is used to separate any suspended liquid water that may be present in the sample gas from the sample. The tube cooler is used for secondary cooling and water removal to achieve drying of the sample gas.

[0007] The sample gas after passing through the pretreatment unit is delivered to the magnetic oxygen analyzer after passing through the coalescing filter, pneumatic valve PV02, and pressure reducing valve PR02. The pneumatic valve PV02 includes a pipeline that leads out through the pressure reducing valve PR02 to deliver the sample gas to the magnetic oxygen analyzer.

[0008] The coalescing filter includes a return gas pipeline, on which a vacuum generator is installed. The vacuum generator is used to control the low-pressure discharge of excess sample gas. The exhaust gas after passing through the magnetic oxygen analyzer is connected to the vacuum generator through a pipeline, and a pneumatic valve PV03 is installed on the pipeline. The pneumatic valve PV03 includes a pipeline leading out for the discharge of exhaust gas.

[0009] The vacuum generator has a pipeline connected to the instrument air main pipe for air intake. A pneumatic valve PV01 is installed on this pipeline. The pneumatic valve PV01 is used to control the supply of instrument air to the vacuum generator.

[0010] The system has a pressure gauge installed on the pipeline before the sample gas enters the pretreatment unit. The pressure gauge feeds back the detected sample gas pressure to the PLC control unit. The PLC control unit controls the solenoid valve to control the supply of driving gas to the pneumatic valve, so as to realize the switching of the pneumatic valve.

[0011] Furthermore, the sampling device collects sample gas through a water-cooled sampling probe. The water-cooled sampling probe uses a built-in cooling pipe to liquefy the sample gas into gaseous water, and the liquefied cooling water is used to wash the sample gas.

[0012] Furthermore, the system is equipped with the following sample gas transmission pipeline:

[0013] The sample gas collected by the sampling device passes through a gas-liquid separator, a tube cooler, a coalescing filter, a pneumatic valve PV02, a pressure reducing valve PR02, and a switching valve BXV01 before entering the magnetic oxygen analyzer. The switching valve BXV01 is connected to the standard gas device.

[0014] Furthermore, the sample gas transmission pipeline includes a water-blocking filter to achieve final drying and filtration of the sample gas before it enters the magnetic oxygen analyzer.

[0015] Furthermore, the return gas pipeline includes a needle valve flow meter, and the system is equipped with the following sample gas transmission pipeline:

[0016] The sample gas flowing out of the coalescing filter flows to the vacuum generator through a needle valve flow meter.

[0017] Furthermore, the system includes a ball valve on the gas pipeline to control the on / off state of the pipeline, and a needle valve flow meter on the gas transmission pipeline to monitor the gas flow rate.

[0018] Furthermore, the air intake pipe connecting the vacuum generator to the instrument air main includes an air filter pressure reducing valve.

[0019] Furthermore, the water-cooled sampling probe has a flow tube distributed inside the tube for sample gas transmission. The gas outlet of the tube forms a gas collection chamber through a baffle. The gas collection chamber is used to collect the sample gas in the flow tube and then flow out through the gas outlet. The outer side of the flow tube and the inner wall of the tube form a cooling chamber. The cooling chamber has an inlet and an outlet on the tube.

[0020] Beneficial effects: Addressing the issue that the pressure of the exhaust gas during furnace operation is a continuous increase from near zero to a maximum of 0.5 MPa, the system provided by this invention can extract and extract the gas from the furnace under low-pressure conditions, and simultaneously depressurize and cool the gas under high-pressure conditions, thereby achieving continuous measurement and smooth, stable transitions between low and high pressures. Furthermore, the system also considers the process conditions within the equipment, including handling issues related to high dust levels in the gas. Finally, this invention employs a PLC control unit to control the solenoid valves, thereby controlling the pneumatic valve's drive gas and switching, preventing the danger of direct contact between electrical equipment and sample gas. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the system described in this utility model;

[0022] Figure 2 This is a structural diagram of the water-cooled sampling probe in the sampling device. Detailed Implementation

[0023] To illustrate the technical solution provided by this utility model in detail, further description is provided below with reference to the accompanying drawings.

[0024] Unlike traditional chemical flare exhaust gas analysis systems, this invention can meet the detection requirements of exhaust gas pressure changes. During the furnace drying process, the pressure continuously increases from near zero to a maximum of 0.5 MPa. Gas analysis during this process presents significant challenges. Firstly, the gas needs to be extracted from the furnace under low-pressure conditions; secondly, the gas needs to be depressurized and cooled under high-pressure conditions. Furthermore, because continuous measurement is required, the critical transition between low and high pressure must be smooth and stable. In addition, due to the process conditions within the equipment, the gas contains a significant amount of dust, making the design of a gas pretreatment system under pressure variation a considerable challenge.

[0025] In response to the above-mentioned exhaust gas detection and analysis conditions of the oven, this utility model provides the following... Figure 1 The diagram shows a pressure swing oxygen analysis system, which includes:

[0026] The sampling device uses a water-cooled sampling probe cooled by circulating water. The sample gas entering the probe is cooled by the low-temperature circulating water flowing in the factory, causing the gaseous water in the sample gas to liquefy, thereby lowering the overall dew point of the sample gas and ensuring the relative dryness of the sample when it enters the subsequent equipment. At the same time, the liquefied cooling water has a washing effect on the sample gas, encapsulating the particulate matter in the sample gas, which flows into the original sampling point under the action of gravity. This maintenance-free self-cleaning function ensures the cleanliness of the sample gas.

[0027] For water-cooled sampling probes, combined with Figure 2 The structure shown describes a water-cooled sampling probe comprising a tube body 1, within which flow tubes 5 are distributed. One end of each flow tube 5 is connected to a process pipeline via a flange 4 for sampling. The flow tubes 5 are evenly distributed within the tube body 1, and their other ends are connected to a baffle 6. The baffle 6 and the outlet end of the tube body 1 form a gas collection chamber, which collects the sample gas within the flow tubes 5 before it flows out. An inlet 3 and an outlet are also provided on the side of the tube body 1, through which a cooling water pipe is connected to achieve cooling water circulation. The cooling water entering through the inlet 3 can fill the area around the flow tubes 5.

[0028] Further integration Figure 1 , Figure 1 In Chinese: BV represents a ball valve, NV represents a needle valve, BXV represents a switching valve, VC represents a vortex dehumidifier, FI represents a needle valve flow meter, PR represents a pressure reducing valve, PV represents a pneumatic valve, FR represents an air filter pressure reducing valve, CR represents a cylinder pressure reducing valve, MS represents a membrane filter, RLV represents a proportional unloading valve, BF represents a coalescing filter, GLS represents a gas-liquid separator, SDS represents a water storage observation tank, SV represents a two-way solenoid valve, SXV represents a three-way solenoid valve, CP represents a vacuum generator, U1 represents a discharge main, U2 represents a liquid drain main, U3 represents an instrument air main, and U4 represents a steam main.

[0029] The sample gas collected by the sampling device is transported through a heated pipeline to maintain a constant temperature and keep the sample in a gaseous state during long-distance transmission.

[0030] After the sample enters the pretreatment chamber, ball valve BV03 shuts off the pressure. Pressure gauge P01 monitors the sample pressure in real time and synchronously feeds back the measurement signal to the interlocking control system. The PLC control unit within the interlocking control system then uses control signals to drive the relevant solenoid valves. Figure 1 The solenoid valves (SXV01-SXV03) are housed in a central solenoid valve box. The solenoid valves then control the air path to supply the driving air for the pneumatic valves (PV01-PV03), ultimately achieving the switching action of the pneumatic valves. This design avoids direct contact between the solenoid valves and the sample, and reduces the risk of explosion and leakage through electro-pneumatic and pneumatic control of air.

[0031] The pretreatment unit includes a gas-liquid separator (GLS) and a tube cooler (LVD). The sample still contains some gaseous water after being cooled by the water-cooled probe. At this time, it first enters the gas-liquid separator (GLS) to separate any suspended liquid water that may be present in the sample from the sample. Then it enters the air-cooled equipment powered by instrument air. The tube cooler (LVD) performs secondary cooling and water removal to ensure the dryness of the sample.

[0032] After the sample gas passes through the coalescing filter (BF), there is a return gas line. The return gas line is a line that leads from the coalescing filter (BF) to the vacuum generator. The purpose is to provide the sample with sufficient flow rate during the transmission process through the high-flow vent, thereby reducing the system response time.

[0033] The vacuum generator and pressure reducing valve constitute the power source and regulator of the sample gas. The vacuum generator serves as a pump, providing power when the pressure at the front end of the vacuum generator is low. When the pressure at the front end is high and it is not needed to pump, it functions as a regular three-way valve and does not affect gas flow.

[0034] Combination Figure 1 The system structure shown in this invention utilizes pneumatic valve switching (PV) to allow samples to enter different flow paths, thereby meeting the instrument's sample introduction conditions under the action of different devices. The flow path design is as follows:

[0035] When the sample pressure at the sampling point is within the pressure range of 0 MPa to the maximum back pressure of 0.15 MPa at the return point, the pneumatic valve PV02 is driven to switch to direct connection with the switching valve BXV01 via the electrical signal feedback from the remote pressure gauge. At the same time, the pneumatic valve PV01 is activated to provide instrument air to the vacuum generator CP. Using the principle of the Venturi tube, the instrument air is used as a power source to generate negative pressure at the tail end of the analyzer, making the sample pressure greater than the discharge pressure (0.15 MPa) at the return point. When the sample is drawn into the analyzer from flow path 1, the pneumatic valve PV03 switches to connect to the vacuum generator CP, so that the exhaust gas after analysis by the magnetic oxygen analyzer is delivered to the vacuum generator. Thus, the analysis exhaust gas will be discharged to the designated return point under the action of the vacuum generator (CP).

[0036] The sample pressure at the sampling point is within the pressure range of 0.15 MPa to the minimum inlet pressure of the sample pressure reducing valve PR02, which is 0.2 MPa. At this time, the interlock control of the pressure measured by the pressure gauge keeps the pneumatic valve PV02 directly connected to the switching valve BXV01. When the pneumatic valve PV01 is closed, the vacuum generator (CP) functions as a three-way valve without the help of a gas source. At the same time, the pneumatic valve PV03 maintains the passage for the analysis tail gas to be delivered to the vacuum generator. The sample will flow through the switching valve BXV01 to the magnetic oxygen analyzer. After analysis, the tail gas will flow through the vacuum generator and return to the designated return point.

[0037] When the sample pressure at the sampling point is within the pressure range of the minimum inlet pressure of the pressure reducing valve PR02 (0.2 MPa) to the maximum pressure of the sampling point (0.5 MPa), the pneumatic valve PV02 switches to this path for control via the interlock control of the pressure measured by the pressure gauge. The sample needs to pass through the pressure reducing valve PR02 to reduce the pressure to the allowable inlet pressure of the analyzer (0.1 MPa). At this time, the exhaust gas pressure of the analyzer no longer meets the discharge pressure of the return point, so the pneumatic valve PV03 switches to the discharge main U1. At this time, the discharge outlet is the high-altitude atmospheric vent, with zero back pressure and direct discharge to the air.

[0038] Through the aforementioned flow path switching process, the analytical system of this invention can cover the entire pressure variation range of the original sampling point with acceptable sample pressure, enabling continuous and stable gas measurement.

Claims

1. A pressure swing oxygen analysis system, comprising a sampling device, wherein the sampling device acquires sample gas and is connected to a pretreatment unit via a heat tracing pipeline, characterized in that, The pretreatment unit includes a gas-liquid separator and a tube cooler. The gas-liquid separator is used to separate any suspended liquid water that may be present in the sample gas from the sample. The tube cooler is used for secondary cooling and water removal to achieve drying of the sample gas. The sample gas after passing through the pretreatment unit is delivered to the magnetic oxygen analyzer after passing through the coalescing filter, pneumatic valve PV02, and pressure reducing valve PR02. The pneumatic valve PV02 includes a pipeline that leads out through the pressure reducing valve PR02 to deliver the sample gas to the magnetic oxygen analyzer. The coalescing filter includes a return gas pipeline, on which a vacuum generator is installed. The vacuum generator is used to control the low-pressure discharge of excess sample gas. The exhaust gas after passing through the magnetic oxygen analyzer is connected to the vacuum generator through a pipeline, and a pneumatic valve PV03 is installed on the pipeline. The pneumatic valve PV03 includes a pipeline leading out for the discharge of exhaust gas. The vacuum generator has a pipeline connected to the instrument air main pipe for air intake. A pneumatic valve PV01 is installed on this pipeline. The pneumatic valve PV01 is used to control the supply of instrument air to the vacuum generator. The system has a pressure gauge installed on the pipeline before the sample gas enters the pretreatment unit. The pressure gauge feeds back the detected sample gas pressure to the PLC control unit. The PLC control unit controls the solenoid valve to control the supply of driving gas to the pneumatic valve, so as to realize the switching of the pneumatic valve.

2. The pressure swing oxygen analysis system according to claim 1, characterized in that, The sampling device collects sample gas through a water-cooled sampling probe. The water-cooled sampling probe liquefies the sample gas into gaseous water through a built-in cooling pipe, and washes the sample gas with the liquefied cooling water.

3. The pressure swing oxygen analysis system according to claim 1, characterized in that, The system is equipped with the following sample gas transmission pipeline: The sample gas collected by the sampling device passes through a gas-liquid separator, a tube cooler, a coalescing filter, a pneumatic valve PV02, a pressure reducing valve PR02, and a switching valve BXV01 before entering the magnetic oxygen analyzer. The switching valve BXV01 is connected to the standard gas device.

4. The pressure swing oxygen analysis system according to claim 3, characterized in that, The sample gas transmission pipeline includes a water-blocking filter.

5. The pressure swing oxygen analysis system according to claim 1, characterized in that, The return gas pipeline includes a needle valve flow meter, and the system is equipped with the following sample gas transmission pipeline: The sample gas flowing out of the coalescing filter flows to the vacuum generator through a needle valve flow meter.

6. The pressure swing oxygen analysis system according to claim 1, characterized in that, The system's gas pipelines include on / off ball valves to control the opening and closing of the pipelines they are connected to.

7. The pressure swing oxygen analysis system according to claim 1 or 3, characterized in that, The system uses a needle valve flow meter installed on the gas transmission pipeline to monitor the gas flow rate.

8. The pressure swing oxygen analysis system according to claim 1, characterized in that, The air intake pipe of the vacuum generator, which connects to the instrument air main, includes an air filter and pressure reducing valve.

9. The pressure swing oxygen analysis system according to claim 2, characterized in that, The tube body (1) of the water-cooled sampling probe has a flow tube (5) for sample gas transmission. The gas outlet of the tube body (1) forms a gas collection chamber through a baffle (6). The gas collection chamber is used to collect the sample gas in the flow tube (5) and then flow out through the gas outlet (2). The outer side of the flow tube (5) and the inner wall of the tube body (1) form a cooling chamber. The cooling chamber has an inlet (3) and an outlet on the tube body (1).

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