Sampling device and method for testing concentration of SO3 in coal-fired flue gas

Abstract

The invention discloses a sampling device and method for testing the concentration of SO3 in coal-fired flue gas, and belongs to the technical field of coal-fired atmospheric pollutant prevention and monitoring, the sampling device comprises a heating sampling system, an SO3 separating and trapping system and a washing and collecting system, and all the systems are assembled into a single hand-held belt wheel box body; the heating and sampling system comprises a telescopic sampling gun, a heating device connected with the telescopic sampling gun and a smoke sampler; the SO3 separation and trapping system comprises a spiral condenser pipe, a membrane separation device and a circulating water bath kettle; the washing and collecting system comprises a flushing pump, an alkaline solution bottle and a collecting liquid bottle; the telescopic heating sampling gun, the spiral condenser pipe, the membrane separation device and the smoke sampler are sequentially connected in series through interfaces; the circulating water bath kettle and the spiral condenser pipe form a circulating loop; and the SO3 separating and trapping system is connected with the washing and collecting system. The device disclosed by the invention is simple to operate, and the trapping efficiency of SO3 in the coal-fired flue gas is improved.

Description

Technical Field

[0001] This invention relates to the field of air pollutant control and monitoring technology for coal combustion, and in particular to a sampling device and method for testing SO3 concentration in coal combustion flue gas. Background Technology

[0002] SO3 in coal-fired flue gas can cause corrosion of pipelines, equipment and chimneys, as well as a decrease in flue gas transparency, which has attracted widespread attention. Accurately measuring the SO3 content in coal-fired flue gas is a necessary condition for controlling its emissions.

[0003] Controlled condensation is currently considered the most accurate method for determining low-concentration SO3 / H2SO4 in power plants. It involves using a heated sampling gun to collect flue gas from the flue, and then collecting the condensed SO3 acid mist droplets using the centrifugal force of a spiral condenser. However, since SO3 acid mist droplets are primarily submicron-sized particles, the condensation temperature and spiral condenser design parameters significantly affect the SO3 acid mist collection efficiency. Under different testing conditions, this method has low accuracy and generally large errors. The isopropanol absorption method uses an 80% isopropanol solution placed in a 0°C ice bath to absorb SO3 from the flue gas and prevent SO2 oxidation from affecting SO3 determination. This absorption method can efficiently capture SO3 from the flue gas, but due to the solubility of SO2 in the isopropanol solution, this method has a large testing error and a high detection limit, lacking accuracy for determining low-concentration SO3 acid mist in desulfurized flue gas. Membrane separation, as a highly efficient separation, concentration, purification, and treatment technology, is widely used in various industrial fields. Selecting a suitable gas-liquid separation membrane can efficiently separate and collect submicron-sized SO3 acid mist droplets from flue gas, avoiding the influence of acidic gaseous pollutants such as SO2, effectively simplifying SO3 acid mist sampling devices and improving measurement accuracy. However, existing devices for measuring SO3 concentration in coal-fired flue gas are bulky, inconvenient to transport, and involve a large workload, long testing time, and significant operational errors during on-site testing. Therefore, actively developing and manufacturing a highly efficient and compact sampling device for measuring SO3 concentration in coal-fired flue gas will have a significant impact on SO3 control in coal-fired flue gas. Summary of the Invention

[0004] The purpose of this invention is to provide a sampling device and method for testing SO3 concentration in coal-fired flue gas. By combining a spiral condenser tube with a membrane separator, and by assembling the sampling device into functional subsystems, it achieves efficient capture of SO3 in coal-fired flue gas and optimizes the size of the sampling device. Combined with a flushing pump and a timed valve, it achieves automatic washing and collection of the sample to be analyzed.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution: On the one hand, the present invention provides a sampling device for testing the SO3 concentration in coal-fired flue gas, including a heating sampling system, an SO3 separation and capture system and a washing and collection system, wherein each system is assembled into a single hand-held wheeled box; The heating sampling system includes a retractable sampling gun, a heating device connected to the retractable sampling gun, and a flue gas sampler, used to remove solid particulate matter from the flue gas and ensure that the temperature of the coal-fired flue gas is above the acid dew point; the SO3 separation and collection system includes a spiral condenser, a membrane separator, and a circulating water bath, used to collect SO3 acid mist; the washing and collection system includes a flushing pump, an alkaline solution bottle, and a collection liquid bottle, used to wash the collected SO3 acid mist and convert it into SO4. 2- ; The retractable heated sampling gun, spiral condenser, membrane separator, and dust sampler are connected in series via interfaces; the circulating water bath and spiral condenser form a circulation loop; flue gas inlet valve and flue gas outlet valve are respectively installed at the flue gas inlet position of the spiral condenser and the flue gas outlet position of the membrane separator; the SO3 separation and capture system is connected to the washing and collection system.

[0006] Optionally, the SO3 separation and capture system is connected to the washing and collection system in the following manner: A tee is provided at the rear end of the flue gas inlet valve; the left end of the tee is the flue gas inlet, the right end of the tee is the flue gas outlet, and the lower end of the tee is the alkaline solution bottle outlet. A timer valve is provided at the alkaline solution bottle outlet, and a quick-connect interface is provided after the timer valve. The alkaline solution bottle outlet is equipped with a tee; the left end of the tee is equipped with a quick-connect interface, which is connected to the quick-connect interface at the rear end of the timer valve; the right end of the tee is the flushing pump inlet; the lower end of the tee is the alkaline solution inlet, where the timer valve is located. The membrane separation device is equipped with a second timer valve on the inlet side, and a quick-connect interface is provided at the rear end of the second timer valve. The collection liquid bottle inlet is equipped with a three-way valve; the left end of the three-way valve is the outlet of the flushing pump; the right end of the three-way valve is equipped with a quick-connect interface, which is connected to the quick-connect interface at the rear end of the second timer valve; the lower end of the three-way valve is the collection liquid inlet, where the fourth timer valve is located.

[0007] Optionally, the length of each individual portable wheeled box is 0.5-0.8m, the height is 0.5-0.8m, and the width is 0.4-0.6m. The front of each box can be opened to view and maintain the internal equipment and pipelines.

[0008] Optionally, the series connection interface is configured such that: a flange interface is provided at the outlet position of the retractable sampling gun, and quick-connect interfaces are provided at the inlet positions of the spiral condenser tube, the outlet position of the membrane separation device, and the inlet position of the dust sampler.

[0009] Optionally, a glass fiber filter cartridge is placed inside the retractable sampling gun, and the adjustable length of the retractable sampling gun is 1-3m.

[0010] Optionally, the membrane in the membrane separation device is a modified polypropylene membrane.

[0011] Optionally, the rinsing pump is a peristaltic pump. The timing logic is set by PLC programming to control the opening and closing of valves at different positions and the start and stop of the rinsing pump in different time periods, so as to realize the automatic injection of alkaline solution, thorough washing, and automatic collection of the washed sample to be analyzed.

[0012] Secondly, the present invention also provides a sampling method for testing the SO3 concentration in coal-fired flue gas, comprising: Open the flue gas inlet valve and flue gas outlet valve, and remove solid particulate matter from the coal-fired flue gas through the filter cartridge in the retractable sampling gun. The coal-fired flue gas then enters the spiral condenser tube. The temperature of the coal-fired flue gas entering the spiral condenser is reduced to below the acid mist point through the circulation loop, and the gaseous SO3 condenses into SO3 acid mist droplets, which are then captured by the spiral condenser and membrane separation device. Close the flue gas inlet valve and flue gas outlet valve, and use a washing and collection system to wash the SO3 acid mist droplets captured by the spiral condenser and membrane separator and convert them into SO4. 2- The collected solution was then analyzed by ion chromatography to determine the SO3 concentration.

[0013] Optionally, the washing process of the washing and collection system is as follows: At the start of the washing process, timer valves one and four are closed, while timer valves two and three are open, and the flushing pump starts running. The washing liquid in the alkaline solution bottle is drawn into the spiral condenser and membrane separator. After running for 1 minute, timer valve three is closed, and timer valve one is opened. The flushing pump runs for 5 minutes to thoroughly flush the system, converting the collected SO3 acid mist droplets into SO4. 2- Obtain the collected liquid; finally, open timer valve four and close timer valve two to transfer the collected liquid into the collection bottle. After the flushing pump runs for 2 minutes, stop and close all timer valves.

[0014] Optionally, the washing solution is a 0.5-1% wt NaOH solution.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention provides a sampling device and method for testing SO3 concentration in coal-fired flue gas. It organically combines controlled condensation for SO3 acid mist capture with membrane separation capture, reducing interference from other components in the flue gas such as particulate matter and SO2, and further improving the SO3 capture efficiency. The entire device is divided into different systems, each modularly assembled into a single portable wheeled housing. Each system has corresponding interfaces; during use, the corresponding interfaces of different systems are connected, further enhancing the device's compactness and simplifying the operation. PLC programming is used to set timing logic, controlling the opening and closing of valves at different positions and the start and stop of the rinsing pump in different time periods, achieving automatic alkaline solution injection, thorough washing, and automatic collection of the washed sample for analysis. Attached Figure Description

[0016] Figure 1 This is a flowchart of the overall process of the sampling device for testing SO3 concentration in coal-fired flue gas according to the present invention. Figure 2 This is a flowchart of the automatic washing and collection system of the present invention.

[0017] The markings in the diagram are: 1-Flue gas inlet valve, 2-Flue gas outlet valve, 3-Timer valve one, 4-Timer valve two, 5-Timer valve three, 6-Timer valve four. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Example 1:

[0019] This embodiment describes a sampling device for testing the SO3 concentration in coal-fired flue gas, such as... Figure 1 and Figure 2 As shown, it includes a heating sampling system, an SO3 separation and capture system, and a washing and collection system, with each system assembled into a single portable wheeled box; The heating sampling system includes a retractable sampling gun, a heating device connected to the retractable sampling gun, and a flue gas sampler, used to remove solid particulate matter from the flue gas and ensure that the temperature of the coal-fired flue gas is above the acid dew point; the SO3 separation and collection system includes a spiral condenser, a membrane separator, and a circulating water bath, used to collect SO3 acid mist; the washing and collection system includes a flushing pump, an alkaline solution bottle, and a collection liquid bottle, used to wash the collected SO3 acid mist and convert it into SO4. 2- ; The retractable heated sampling gun, spiral condenser, membrane separator, and dust sampler are connected in series via interfaces; the circulating water bath and spiral condenser form a circulation loop; flue gas inlet valve 1 and flue gas outlet valve 2 are respectively installed at the flue gas inlet position of the spiral condenser and the flue gas outlet position of the membrane separator; the SO3 separation and capture system is connected to the washing and collection system.

[0020] The connection method between the SO3 separation and capture system and the washing and collection system is as follows: A tee is provided at the rear end of the flue gas inlet valve 1; the left end of the tee is the flue gas inlet, the right end of the tee is the flue gas outlet, and the lower end of the tee is the alkaline solution bottle outlet. A timer valve 3 is provided at the alkaline solution bottle outlet, and a quick-connect interface is provided after the timer valve 3. The alkaline solution bottle outlet is provided with a tee; the left end of the tee is provided with a quick-connect interface, which is connected to the quick-connect interface at the rear end of the timer valve 3; the right end of the tee is the flushing pump inlet; the lower end of the tee is the alkaline solution inlet, where the timer valve 5 is located; The membrane separation device is equipped with a timing valve 4 at the inlet side, and a quick-connect interface is provided at the rear end of the timing valve 4. The collection liquid bottle inlet is equipped with a three-way valve; the left end of the three-way valve is the outlet of the flushing pump; the right end of the three-way valve is equipped with a quick-connect interface, which is connected to the quick-connect interface at the rear end of the timer valve 4; the lower end of the three-way valve is the collection liquid inlet, where the timer valve 6 is located.

[0021] Each individual portable wheeled box has a length of 0.5-0.8m, a height of 0.5-0.8m, and a width of 0.4-0.6m. The front of each box can be opened to view and maintain the internal equipment and pipelines.

[0022] The series connection interface is configured as follows: a flange interface is provided at the outlet position of the retractable sampling gun, and quick-connect interfaces are provided at the inlet positions of the spiral condenser tube, the outlet position of the membrane separation device, and the inlet position of the dust sampler.

[0023] The retractable sampling gun contains a glass fiber filter cartridge, and the adjustable length of the retractable sampling gun is 1-3m.

[0024] The membrane in the membrane separation device is a modified polypropylene membrane.

[0025] The rinsing pump is a peristaltic pump. It uses PLC programming to set timing logic to control the opening and closing of valves at different positions and the start and stop of the rinsing pump in different time periods, so as to realize the automatic injection of alkaline solution, thorough washing, and automatic collection of the washed sample to be analyzed. Example 2:

[0026] This embodiment describes a sampling method for testing the SO3 concentration in coal-fired flue gas, including: Open flue gas inlet valve 1 and flue gas outlet valve 2. Remove solid particulate matter from the coal-fired flue gas through the filter cartridge in the retractable sampling gun. The coal-fired flue gas then enters the spiral condenser tube. The temperature of the coal-fired flue gas entering the spiral condenser is reduced to below the acid mist point through the circulation loop, and the gaseous SO3 condenses into SO3 acid mist droplets, which are then captured by the spiral condenser and membrane separation device. Close flue gas inlet valve 1 and flue gas outlet valve 2, and use a washing and collection system to wash the SO3 acid mist droplets captured by the spiral condenser and membrane separator and convert them into SO4. 2- The collected solution was then analyzed by ion chromatography to determine the SO3 concentration.

[0027] I. Heating Sampling Based on the sampling pipeline requirements, the length of the sampling gun is determined. According to the original flue gas temperature and the heating device, the flue gas temperature is ensured to be above the acid dew point during the sampling process, and the flue gas temperature at the sampling gun outlet is above 180℃. Particulate matter in the flue gas is removed by the filter cartridge placed in the middle of the sampling gun, and the flue gas then enters the spiral condenser tube.

[0028] II. SO3 Condensation and Capture The flue gas entering the spiral condenser is cooled by circulating water, and the flue gas temperature drops to 60-80℃. The gaseous SO3 condenses into SO3 acid mist droplets, most of which are captured by the spiral condenser, and a small amount enters the subsequent membrane separation device with the flue gas for capture.

[0029] III. SO3 Acid Mist Collection The SO3 acid mist captured by the spiral condenser and membrane separator is automatically washed and converted into SO4 using a 0.5-1% wt NaOH solution as an alkaline solution. 2- The system utilizes PLC programming to set timing logic, closing the inlet valve of the spiral condenser and the outlet valve of the membrane separator when washing begins. The alkaline solution washing and collection process is controlled by setting the opening and closing states of the timing valves and the flushing pump.

[0030] At the start of the washing process, timer valves one and four are closed, while timer valves two and three are open. The flushing pump starts running, drawing the alkaline solution into the spiral condenser and membrane separator. After running for 1 minute, timer valve three is closed, and timer valve one is opened. The flushing pump then runs for 5 minutes to thoroughly flush the system, converting the collected SO3 acid mist into SO4. 2- Finally, open timer valve four and close timer valve two. The washing solution is delivered to the collection bottle. The rinsing pump runs for 2 minutes and then stops. All timer valves are closed, and the collection solution is taken out for subsequent analysis.

[0031] IV. Comparative Analysis An SO3 generator produces a certain concentration of SO3, which is then introduced into simulated wet desulfurization flue gas containing water vapor, SO2, and particulate matter. The humidity is 90%, and the SO2 concentration is 40 mg / m³. 3 The particulate matter concentration was 10 mg / m³. 3 The present invention utilizes the device to detect the concentration of SO3 acid mist in simulated flue gas. The SO3 generator produces SO3 by oxidizing SO2 with O3, and precisely controls the O3 and SO2 content to maintain the SO3 production at 50 mg / m³. 3 The device of this invention measured the SO3 acid mist concentration in the simulated flue gas to be 49.3 mg / m³. 3 The capture efficiency reached 98.6%.

[0032] Comparative Example 1: The same simulated flue gas was prepared as described above. Referring to the "Performance Test Method for Coal-fired Flue Gas Desulfurization Equipment (GB / T21508-2008)", the SO3 acid mist content was determined by controlled condensation method. The collection efficiency was found to be 87.3%, which is relatively low.

[0033] Comparative Example 2: The same simulated flue gas was prepared as described above, and the SO3 acid mist content was determined by isopropanol absorption method. The SO3 acid mist concentration in the simulated flue gas was measured to be 55.4 mg / m3, and the collection efficiency exceeded 100%. The SO2 component in the flue gas had a significant impact on the measurement results.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sampling device for testing the SO3 concentration in coal-fired flue gas, characterized in that, It includes a heating sampling system, an SO3 separation and capture system, and a washing and collection system, with each system assembled into a single portable wheeled box; The heating sampling system comprises a telescopic sampling gun, a heating device connected with the telescopic sampling gun and a smoke dust sampler, which is used for removing solid particles in flue gas and ensuring that the temperature of the flue gas is above the acid dew point; the SO3 separation and capture system comprises a spiral condenser tube, a membrane separation device and a circulating water bath, which is used for capturing SO3 acid mist; the washing and collecting system comprises a flushing pump, an alkaline solution bottle and a collecting liquid bottle, which is used for washing the captured SO3 acid mist and converting it into SO4 2- . The retractable heated sampling gun, spiral condenser, membrane separator, and dust sampler are connected in series via interfaces; the circulating water bath and spiral condenser form a circulation loop; flue gas inlet valve and flue gas outlet valve are respectively installed at the flue gas inlet position of the spiral condenser and the flue gas outlet position of the membrane separator; the SO3 separation and capture system is connected to the washing and collection system.

2. The sampling device for testing SO3 concentration in coal-fired flue gas according to claim 1, characterized in that, The connection method between the SO3 separation and capture system and the washing and collection system is as follows: A tee is provided at the rear end of the flue gas inlet valve; the left end of the tee is the flue gas inlet, the right end of the tee is the flue gas outlet, and the lower end of the tee is the alkaline solution bottle outlet. A timer valve is provided at the alkaline solution bottle outlet, and a quick-connect interface is provided after the timer valve. The alkaline solution bottle outlet is equipped with a tee; the left end of the tee is equipped with a quick-connect interface, which is connected to the quick-connect interface at the rear end of the timer valve; the right end of the tee is the flushing pump inlet; the lower end of the tee is the alkaline solution inlet, where the timer valve is located. The membrane separation device is equipped with a second timer valve on the inlet side, and a quick-connect interface is provided at the rear end of the second timer valve. The collection liquid bottle inlet is equipped with a three-way valve; the left end of the three-way valve is the outlet of the flushing pump; the right end of the three-way valve is equipped with a quick-connect interface, which is connected to the quick-connect interface at the rear end of the second timer valve; the lower end of the three-way valve is the collection liquid inlet, where the fourth timer valve is located.

3. The sampling device for testing SO3 concentration in coal-fired flue gas according to claim 1, characterized in that, Each individual portable wheeled box has a length of 0.5-0.8m, a height of 0.5-0.8m, and a width of 0.4-0.6m. The front of each box can be opened to view and maintain the internal equipment and pipelines.

4. The sampling device for testing SO3 concentration in coal-fired flue gas according to claim 1, characterized in that, The series connection interface is configured as follows: a flange interface is provided at the outlet position of the retractable sampling gun, and quick-connect interfaces are provided at the inlet positions of the spiral condenser tube, the outlet position of the membrane separation device, and the inlet position of the dust sampler.

5. The sampling device for testing SO3 concentration in coal-fired flue gas according to claim 1, characterized in that, The retractable sampling gun contains a glass fiber filter cartridge, and the adjustable length of the retractable sampling gun is 1-3m.

6. The sampling device for testing SO3 concentration in coal-fired flue gas according to claim 1, characterized in that, The membrane in the membrane separation device is a modified polypropylene membrane.

7. The sampling device for testing SO3 concentration in coal-fired flue gas according to claim 1, characterized in that, The flushing pump is a peristaltic pump, and the timing logic is set using PLC programming.

8. A sampling method for testing the SO3 concentration in coal-fired flue gas, characterized in that, include: Open the flue gas inlet valve and flue gas outlet valve, and remove solid particulate matter from the coal-fired flue gas through the filter cartridge in the retractable sampling gun. The coal-fired flue gas then enters the spiral condenser tube. The temperature of the coal-fired flue gas entering the spiral condenser is reduced to below the acid mist point through the circulation loop, and the gaseous SO3 condenses into SO3 acid mist droplets, which are then captured by the spiral condenser and membrane separation device. Turning off the flue gas inlet valve and the flue gas outlet valve, using the scrubbing collection system to scrub the SO3 acid mist droplets captured by the spiral condenser tube and the membrane separation device and convert them into SO4 2- The collection liquid is obtained, and the SO3 concentration of the collection liquid is determined by ion chromatography.

9. The sampling method for testing SO3 concentration in coal-fired flue gas according to claim 8, characterized in that, The washing process of the washing and collection system is as follows: At the beginning of washing, the timing valve one and the timing valve four are closed, the timing valve two and the timing valve three are opened, and the flushing pump is started to run; the washing liquid in the alkaline solution bottle is extracted to the spiral condenser and the membrane separation device, the timing valve three is closed after running for 1 min, and the timing valve one is opened; the flushing pump runs for 5 min, and the flushing is fully carried out, and the collected SO3acid mist droplets are converted into SO4 2- The collected liquid is obtained; finally, the timing valve four is opened, and the timing valve two is closed, the collected liquid is transported to the collected liquid bottle, and the flushing pump stops after running for 2 min, and all the timing valves are closed.

10. The sampling method for testing SO3 concentration in coal-fired flue gas according to claim 9, characterized in that, The washing solution is a 0.5-1% wt NaOH solution.

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