A double-pulse differential phase-puffing smoke sampling device and method

Abstract

A double-pulse differential back-blowing flue gas sampling device and method, which is composed of alternating back-blowing sampling cycles and non-back-blowing sampling cycles. The periodic sampler operates continuously, and the flue gas is sucked in from the inner tube inlet and discharged from the sampler outlet. In the non-back-blowing cycle, the back-blowing pulse valve and the back-suction pulse valve are both closed. The flue gas enters the inner cavity from the outer surface of the smoke filter and then enters the inner tube inlet after being collected. The back-blowing pulse valve is opened and lasts for ΔT1 time, and the gas in the back-blowing preheating tube enters the inner cavity of the smoke filter. The dust accumulated on the outer surface of the smoke filter is back-blown, and the gas entering the inner tube inlet is the flue gas in the inner cavity. At the end of ΔT1, the back-suction pulse valve is opened and lasts for ΔT2 time, and the gas in the inner cavity flows to the vacuum tank, and the flue gas enters the inner cavity through the smoke filter. The present invention can achieve uninterrupted sampling during back-blowing, and realize truly continuous flue gas sampling, which provides conditions for improving the level of environmental monitoring and the control quality of environmental protection devices.

Description

Technical Field

[0001] The invention relates to a smoke sampling device and method, and in particular to a double-pulse differential phase-blowing smoke sampling device and method. Background Art

[0002] The continuous emission monitoring system (CEMS) is mainly based on the principle of extraction. The monitoring system based on this principle needs to filter out the dust in the sample gas first. The usual practice is to use high-temperature ceramic or metal filter elements. When the dust on the surface of the filter element accumulates to a certain thickness, it is back-blown with compressed air, which usually lasts about 2 minutes. During the back-blowing period, sampling is interrupted and flue gas analysis is suspended. Since the operation and control of environmental protection systems such as denitrification and desulfurization require the values ​​of flue gas components such as NOx and SO2, the interruption of sampling and analysis caused by such long-term back-blowing will have an adverse effect on the control of the environmental protection system; for the CEMS used for environmental protection monitoring of the total outlet, the pollutant emission data is missing during the back-blowing period. Summary of the invention

[0003] The purpose of the present invention is to solve the above-mentioned problems and to provide a dual-pulse differential back-blowing flue gas sampling device and method, which can achieve uninterrupted sampling during backblowing and realize truly continuous flue gas sampling, thus providing conditions for improving the level of environmental monitoring and the control quality of environmental protection devices.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A double-pulse differential back-blowing flue gas sampling device comprises a back-blowing buffer tank, a back-blowing preheating tube, a vacuum tank, a smoke filter, an inner tube and a probe base installed on the flue wall, wherein the probe base is provided with an inner tube support sleeve, the inner tube support sleeve is connected to the smoke filter, one end of the inner tube passes through the inner tube support sleeve, and the other end extends into the smoke filter, the outlet of the back-blowing buffer tank is connected to the inlet of the back-blowing preheating tube via a back-blowing pulse valve, the outlet of the vacuum tank is connected to the inlet of the back-blowing preheating tube via a back-suction pulse valve, the outlet of the back-blowing preheating tube is connected to the inner cavity of the smoke filter, and one end of the inner tube passing through the inner tube support sleeve is connected to the sampler.

[0006] A further improvement of the present invention is that the backflush buffer tank inlet of the backflush buffer tank is connected to a compressed air system.

[0007] A further improvement of the present invention is that the vacuum tank inlet of the vacuum tank is connected to an air extraction pump.

[0008] A further improvement of the present invention is that a tee is provided at the outlet of the connected back-blowing preheating tube, one outlet of the tee is connected to the inner tube support sleeve, and the other outlet is connected to the inner cavity of the smoke filter.

[0009] A further improvement of the present invention is that the inner tube support sleeve comprises a metal outer protective tube and an internal heat insulating material, and the internal heat insulating material is arranged inside the metal outer protective tube.

[0010] A further improvement of the present invention is that a sealing structure is provided between the inner tube and the metal outer protective tube.

[0011] A further improvement of the present invention is that the smoke filter is a cylindrical ceramic filter with a filtering accuracy of 1 micron, one end of the smoke filter is a closed end, and the other end is an open end.

[0012] A further improvement of the present invention is that the inner tube is arranged on the center line of the soot filter.

[0013] A further improvement of the present invention is that both the back-blowing pulse valve and the back-suction pulse valve are connected to a controller; one end of the inner tube passing through the inner tube support sleeve is connected to a sampling tube via a pipeline, and the sampling tube is connected to a sampler.

[0014] A double-pulse differential back-blowing flue gas sampling method based on the above device includes a back-blowing sampling period and a non-back-blowing sampling period, and the back-blowing sampling period and the non-back-blowing sampling period are performed alternately; wherein,

[0015] The specific process of the non-backflush sampling cycle is as follows: the backflush pulse valve and the back-suction pulse valve are closed, the smoke enters the inner cavity from the outer surface of the smoke filter and then enters the inner tube inlet, and then enters the sampler through the inner tube;

[0016] The specific process of the back-blowing cycle is as follows: the back-blowing pulse valve is opened and lasts for ΔT1 time, the preheated gas in the back-blowing preheating tube enters the inner cavity, the pressure in the inner cavity increases, the dust accumulated on the outer surface of the smoke filter is back-blown, and the smoke in the inner cavity moves to the closed end of the smoke filter and enters the sampler through the inner tube;

[0017] When the ΔT1 time ends, the back-suction pulse valve opens and lasts for ΔT2 time. The gas in the inner cavity flows to the vacuum tank through the back-blowing preheating tube, the inner cavity pressure drops, and the flue gas enters the inner cavity through the smoke filter and enters the sampler through the inner tube. After the ΔT2 time ends, the non-back-blowing sampling cycle begins.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention arranges a backblowing buffer tank, a backblowing preheating tube, a vacuum tank, a smoke filter, an inner tube and a probe base installed on the flue wall. The probe base is provided with an inner tube support sleeve, the inner tube support sleeve is connected to the smoke filter, one end of the inner tube passes through the inner tube support sleeve, and the other end extends into the smoke filter. The outlet of the backblowing buffer tank is connected with the inlet of the backblowing preheating tube via a backblowing pulse valve, the outlet of the vacuum tank is connected with the inlet of the backblowing preheating tube via a back-suction pulse valve, the outlet of the backblowing preheating tube is connected with the inner cavity of the smoke filter, and one end of the inner tube passing through the inner tube support sleeve is connected to the sampler, so that sampling can be carried out without interruption during backblowing, thereby realizing truly continuous flue gas sampling, providing conditions for improving the level of environmental protection monitoring and the control quality of environmental protection devices.

[0020] Continuous sampling consists of alternating back-blowing sampling cycles and non-back-blowing sampling cycles. All periodic samplers operate continuously, and the flue gas is continuously sucked in from the inner tube inlet and discharged from the sampler outlet, and the discharged flue gas enters the analyzer. In the non-back-blowing cycle, the back-blowing pulse valve and the back-suction pulse valve are closed. The flue gas enters the inner cavity from the outer surface of the smoke filter and then enters the inner tube inlet. The back-blowing cycle includes 1 purge pulse and 1 back-suction pulse. The two pulses are out of phase, continuous in time but not overlapping. At the beginning of the purge, the back-blowing pulse valve opens and lasts for ΔT1 time. During this period, the preheated gas in the back-blowing preheating tube quickly enters the inner cavity of the smoke filter, the inner cavity pressure increases, and the dust accumulated on the outer surface of the smoke filter is back-blown. At the same time, the smoke in the inner cavity moves to the right, but because the time is extremely short, during ΔT1, the gas entering the inner tube inlet is still the smoke in the original inner cavity. At the end of ΔT1, the back-suction pulse valve opens and lasts for ΔT2. The gas in the inner cavity quickly flows to the vacuum tank through the back-blowing preheating tube, the inner cavity pressure drops rapidly, and the flue gas quickly enters the inner cavity through the smoke filter. At the end of ΔT2, the inner cavity is full of flue gas. During ΔT2, the gas entering the inner tube inlet is still flue gas. After ΔT2 ends, the non-back-blowing sampling cycle begins. In this way, during the entire continuous sampling process, the gas entering the inner tube inlet is flue gas, achieving the purpose of full-time sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Among them, 1-backblowing buffer tank; 2-backblowing pulse valve; 3-probe base; 4-inner wall of flue; 5-backblowing preheating tube; 6-vacuum tank; 7-back-suction pulse valve; 8-inner tube support sleeve; 9-smoke filter; 10-inner cavity; 11-inner tube inlet; 12-backblowing gas end point; 13-inner tube; 14-sampler; 15-sampling tube; 16-vacuum tank inlet; 17-backblowing buffer tank inlet; 18-controller. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings.

[0024] refer to Figure 1 The double-pulse differential back-blowing flue gas sampling device described in the present invention includes a back-blowing buffer tank 1, a back-blowing pulse valve 2, a probe base 3, a back-blowing preheating tube 5, a vacuum tank 6, a back-suction pulse valve 7, an inner tube support sleeve 8, a smoke filter 9, an inner tube 13, a sampling tube 15, a sampler 14, a vacuum tank inlet 16, a back-blowing buffer tank inlet 17 and a controller 18, etc. The above components are installed on the flue wall 4 through the probe base 3; the backblowing buffer tank inlet 17 is connected to the external compressed air system, and the vacuum tank inlet 16 is connected to the external vacuum pump; specifically, the backblowing buffer tank 1 and the vacuum tank 6 outlets are connected in parallel through the backblowing pulse valve 2 and the back-suction pulse valve 7 respectively and then connected to the inlet of the backblowing preheating tube 5; the backblowing preheating tube 5 outlet is connected to the open end of the smoke filter 9 and the inner tube support sleeve 8 in a three-way manner; specifically, the inner tube support sleeve 8 is connected to the smoke filter 9 and is located on the same straight line, the inner tube support sleeve 8 is arranged on the probe base 3, the inner tube support sleeve 8 includes a thin-walled metal outer protective tube and an internal thermal insulation material, the internal thermal insulation material is arranged in the thin-walled metal outer protective tube, and the smoke filter 9 is a slender cylindrical ceramic filter with a filtration accuracy of 1 micron, one end of which is closed and the other end is open. The inner tube 13 is positioned on the center line of the soot filter 9 through the inner tube support sleeve 8; that is, one end (inner tube outlet) of the inner tube 13 passes through the inner tube support sleeve 8, and the other end (inner tube inlet 11) extends into the soot filter 9 and is close to the inner wall of the soot filter 9. An inner cavity 10 is formed between the inner tube 13 and the inner wall of the soot filter 9, and a sealing structure is provided between the inner tube 13 and the inner tube support sleeve 8, so that the inner cavity 10 is sealed and isolated from the external air;

[0025] The smoke filter 9 is connected and fixed to the probe base 3 through the inner tube support sleeve 8; the inner tube 13 is a stainless steel or quartz thin tube, and the inlet end of the inner tube 13 is close to the inner wall of the closed end of the smoke filter 9, and a 6-10mm gap is retained. The outlet of the inner tube 13 is connected to the inlet of the sampler 14 through the sampling tube 15. The sampler 14 includes an exhaust pump and a flue gas condensation dehumidifier, and the flue gas discharged by the sampler 14 is supplied to the downstream flue gas analyzer.

[0026] The double-pulse differential phase puffing flue gas sampling method of the present invention comprises the following steps:

[0027] During operation, the vacuum tank 6 is maintained at a negative pressure below -80 kPa through an external vacuum pump; the backflush buffer tank 1 is maintained at a positive pressure, usually between 100 and 300 kPa, through an external compressed air system.

[0028] Continuous sampling is composed of backflush sampling cycles and non-backflush sampling cycles alternately. All periodic samplers 14 are continuously operated, and sample gas is continuously sucked in from the inner tube inlet 11 and discharged from the sampler 14 outlet, and the discharged sample gas enters the analyzer.

[0029] In the non-backwash cycle, the backwash pulse valve 2 and the back-suction pulse valve 7 are both closed. The smoke enters the inner cavity 10 from the outer surface of the smoke filter 9 and then enters the inner tube inlet 11. The length of the non-backwash sampling cycle is determined by the characteristics of the smoke filter 9 and the smoke concentration in the smoke. The outer surface of the smoke filter 9 is the backwash gas end point 12.

[0030] The backflush cycle includes one purge pulse (width ΔT1) and one backsuck pulse (period ΔT2). The two pulses are out of phase and continuous in time but do not overlap.

[0031] When the purge starts, the back-blowing pulse valve 2 opens and lasts for ΔT1 time. During this period, the preheated gas in the back-blowing preheating tube 5 quickly enters the inner cavity 10, the pressure in the inner cavity 10 increases, and the dust accumulated on the outer surface of the soot filter 9 is back-blown. At the same time, the sample gas in the inner cavity 10 moves toward the closed end of the soot filter 9. However, due to the extremely short time, during ΔT1, the gas entering the inner tube inlet 11 is still the sample gas in the inner cavity 10 at the beginning.

[0032] When the ΔT1 time is over, the back-suction pulse valve 7 is opened and lasts for the ΔT2 time. The gas in the inner cavity 10 quickly flows to the vacuum tank 6 through the back-blowing preheating tube 5, the pressure of the inner cavity 10 drops rapidly, and the flue gas quickly enters the inner cavity 10 through the smoke filter 9. When the ΔT2 time is over, the inner cavity 10 is filled with sample gas; during the ΔT2 time, the gas entering the inner tube inlet 11 is still sample gas.

[0033] After the ΔT2 time is over, the non-backflush sampling cycle begins. In this way, during the entire continuous sampling process, the gas entering the inner tube inlet 11 is the sample gas, achieving the purpose of full-time sampling.

Claims

1. A double-pulse differential phase-puffing flue gas sampling device, characterized in that: The invention comprises a back-blowing buffer tank (1), a back-blowing preheating tube (5), a vacuum tank (6), a smoke filter (9), an inner tube (13), and a probe base (3) mounted on a flue wall (4); an inner tube support sleeve (8) is arranged on the probe base (3); the inner tube support sleeve (8) is connected to the smoke filter (9); one end of the inner tube (13) passes through the inner tube support sleeve (8) and the other end extends into the smoke filter (9); the outlet of the back-blowing buffer tank (1) is connected to the inlet of the back-blowing preheating tube (5) via a back-blowing pulse valve (2); the outlet of the vacuum tank (6) is connected to the inlet of the back-blowing preheating tube (5) via a back-suction pulse valve (7); the outlet of the back-blowing preheating tube (5) is connected to the inner cavity (10) of the smoke filter (9); and one end of the inner tube (13) passing through the inner tube support sleeve (8) is connected to a sampler (14); The back-blowing pulse valve (2) and the back-suction pulse valve (7) are both connected to a controller (18); The backflush cycle of the sampling device includes one purge pulse and one back-sucking pulse, and the two pulses are out of phase; The double-pulse differential back-blowing flue gas sampling method of the device includes a back-blowing sampling period and a non-back-blowing sampling period, and the back-blowing sampling period and the non-back-blowing sampling period are performed alternately; wherein, The specific process of the non-backflush sampling cycle is as follows: the backflush pulse valve (2) and the back-inhalation pulse valve (7) are closed, the smoke enters the inner cavity (10) from the outer surface of the smoke filter (9), is collected, and then enters the inner tube inlet (11), and enters the sampler (14) through the inner tube (13); The specific process of the back-blowing cycle is as follows: the back-blowing pulse valve (2) is opened and lasts for a time period of ΔT1, the preheated gas in the back-blowing preheating tube (5) enters the inner cavity (10), the pressure in the inner cavity (10) increases, the dust accumulated on the outer surface of the smoke filter (9) is back-blown, and the smoke in the inner cavity (10) moves toward the closed end of the smoke filter (9) and enters the sampler (14) through the inner tube (13); When the ΔT1 time is over, the back-suction pulse valve (7) opens and lasts for the ΔT2 time, the gas in the inner cavity (10) flows to the vacuum tank (6) through the back-blowing preheating tube (5), the pressure of the inner cavity (10) decreases, the smoke enters the inner cavity (10) through the smoke filter (9), and enters the sampler (14) through the inner tube (13). After the ΔT2 time is over, the non-back-blowing sampling cycle begins.

2. A double-pulse differential phase puffing smoke sampling device according to claim 1, characterized in that: The backflush buffer tank inlet (17) of the backflush buffer tank (1) is connected to a compressed air system.

3. A double-pulse differential phase puffing smoke sampling device according to claim 1, characterized in that: The vacuum tank inlet (16) of the vacuum tank (6) is connected to a vacuum pump.

4. A double-pulse differential phase puffing smoke sampling device according to claim 1, characterized in that: A tee is provided at the outlet of the connected back-blowing preheating pipe (5), one outlet of the tee is connected to the inner pipe support sleeve (8), and the other outlet is connected to the inner cavity (10) of the smoke filter (9).

5. The double-pulse differential phase puffing smoke sampling device according to claim 1 is characterized in that: The inner tube support sleeve (8) comprises a metal outer protective tube and an internal heat insulating material, wherein the internal heat insulating material is arranged inside the metal outer protective tube.

6. A double-pulse differential phase-puffing smoke sampling device according to claim 5, characterized in that: A sealing structure is provided between the inner tube (13) and the metal outer protective tube.

7. A double-pulse differential phase-puffing smoke sampling device according to claim 1, characterized in that: The smoke filter (9) is a cylindrical ceramic filter with a filtering accuracy of 1 micron. One end of the smoke filter (9) is a closed end and the other end is an open end.

8. The double-pulse differential phase-puffing smoke sampling device according to claim 1 is characterized in that: The inner tube (13) is arranged on the center line of the soot filter (9).

9. The double-pulse differential phase puffing smoke sampling device according to claim 1, characterized in that: One end of the inner tube (13) passing through the inner tube support sleeve (8) is connected to the sampling tube (15) through a pipeline, and the sampling tube (15) is connected to the sampler (14).

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