A device for on-line detection of small pressure difference of desulfurized flue gas

Abstract

The utility model relates to the field of gas measurement technology of desulfurization flue gas, environmental protection device and chemical industry system, specifically is a kind of desulfurization flue gas small differential pressure on-line detection device, it can long time stable carry out differential pressure detection, it includes desulfurization absorption tower, the top cylinder of desulfurization absorption tower is equipped with demister or filler layer, its characterized in that, the upper and lower of demister or filler layer are all provided with measurement installation interface, diaphragm pressure transmitter is installed on the measurement installation interface.

Description

Technical Field

[0001] This utility model relates to the field of gas measurement technology for desulfurization flue gas, environmental protection devices, and chemical systems, specifically to an online detection device for minute differential pressure in desulfurization flue gas. Background Technology

[0002] The flue gas from boilers or kilns generates significant amounts of pollutants and is treated using an advanced limestone (lime)-gypsum wet desulfurization process. Flue gas from boilers or industrial kilns enters the lower part of the desulfurization absorption tower and flows upwards. The washing circulating slurry at the bottom of the absorption tower is atomized and sprayed downwards through a circulating pipeline by a desulfurization circulating pump into the spray layer pipeline at the top of the absorption tower. During the spraying process, acidic components in the flue gas, such as SO2, SO3, HF, and HCl, are absorbed and sprayed downwards into the circulating slurry oxidation reaction tank at the bottom of the absorption tower. The desulfurization absorbent, limestone CaCO3 (or lime CaO), reacts with the acidic substances in the desulfurization tower (oxidation reaction tank), oxidizing them into gypsum slurry CaSO4·2H2O (circulating slurry). The clean flue gas, washed by the spray layer, flows upwards, passes through a demister or packing layer to remove water droplets and dust particles, and is discharged from the top of the absorption tower. See Appendix. Figure 1 Schematic diagram of a wet desulfurization tower system.

[0003] After a certain period of operation, slurry or solid particles of flue gas will accumulate on the surface of the demister or packing layer. The pressure difference between the two sides of the flue gas will increase (10-200 Pa). Therefore, it is necessary to flush the surface in time according to the pressure difference between the two sides. However, the pressure difference is usually measured by a capillary differential pressure transmitter. However, the transmitter has the disadvantages of small sampling port that is easy to be blocked, inconvenient maintenance, and the capillary is easily affected by the environment and operating conditions, causing the measured value to fluctuate irregularly and be inaccurate. It cannot reflect the dynamic pressure difference between the two sides in real time, and cannot provide a reliable basis for controlling the resistance of the demister (or packing layer) and flushing it. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an online detection device for minute differential pressure in desulfurized flue gas, which can stably detect differential pressure over a long period of time.

[0005] The technical solution is as follows: an online detection device for minute differential pressure of desulfurized flue gas, comprising a desulfurization absorption tower, wherein a demister or packing layer is installed in the top cylinder of the desulfurization absorption tower, characterized in that a measurement installation interface is provided above and below the demister or packing layer, and a diaphragm pressure transmitter is installed on the measurement installation interface.

[0006] A further feature is that each of the measurement installation interfaces is equipped with a flushing water branch pipe and a purge hot air branch pipe, all of the flushing water branch pipes are connected to the flushing water main pipe with a flushing water inlet valve, and all of the purge hot air branch pipes are connected to the purge hot air main pipe with a purge air inlet valve.

[0007] By adopting this utility model, the pressure difference between the upper and lower parts can be easily measured using diaphragm pressure transmitters above and below the demister or packing layer without being affected, thus achieving stable pressure difference detection over a long period of time. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of a wet desulfurization tower system; Figure 2 for Figure 1 A schematic diagram showing the installation of this utility model in the middle; Figure 3 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0009] See Figure 2 , Figure 3 As shown, an online detection device for minute differential pressure in desulfurized flue gas includes a desulfurization absorption tower. A demister or packing layer is installed inside the top cylinder 3 of the desulfurization absorption tower. In this embodiment, the packing layer is used as an example, including a first packing layer 4 and a second packing layer 6. Measurement installation interfaces are provided above and below the first packing layer 4, including a first measurement installation interface 11, a second measurement installation interface 19, and a third measurement installation interface 27. A diaphragm pressure transmitter 14 is installed on the first measurement installation interface 11 via a flange 12 and a flange 13. A diaphragm pressure transmitter 22 is installed on the second measurement installation interface 19 via a flange 20 and a flange 21. A diaphragm pressure transmitter 30 is installed on the third measurement installation interface 27 via a flange 28 and a flange 29. The three diaphragm pressure transmitters are... Figure 2 The positions of PA1, PA2 and PA3 in the middle.

[0010] Each measurement installation interface is equipped with a flushing water branch pipe and a purge hot air branch pipe. Specifically, measurement installation interface 11 is equipped with a flushing water branch pipe 8 with a flushing water inlet valve 7 and a purge hot air branch pipe 10 with a purge air inlet valve 9. Measurement installation interface 29 is equipped with a flushing water branch pipe 216 with a flushing water inlet valve 215 and a purge hot air branch pipe 218 with a purge air inlet valve 217. Measurement installation interface 37 is equipped with a flushing water branch pipe 324 with a flushing water inlet valve 323 and a purge hot air branch pipe 326 with a purge air inlet valve 325. The flushing water branch pipes 18, 216, and 24 are connected to the flushing water main pipe 2 with a flushing water inlet main valve 1. The purge hot air branch pipes 10, 218, and 26 are connected to the purge hot air main pipe 5 with a purge air inlet main valve 31.

[0011] Workflow: The flue gas (gas) from the lower part of the top cylinder 3 passes sequentially through packing layer 4 and packing layer 6, and is discharged from the upper part of the top cylinder 3. As the flue gas (gas) passes through packing layer 4 and packing layer 6, water droplets and dust particles are removed, and a small differential pressure (resistance) is generated on the upper and lower sides of packing layer 4 and packing layer 6. During operation, more and more slurry or flue gas solid particles accumulate on the surface of packing layer 4 and packing layer 6, and the small differential pressure (resistance) on the upper and lower sides increases. This small differential pressure is measured by diaphragm pressure transmitters 14, 22, and 30, respectively, to determine the pressure value PA1 at the lower part of packing layer 4, the pressure value PA2 between packing layer 4 and packing layer 6, and the pressure value PA3 at the upper part of packing layer 6. The small differential pressure value PD1 on the upper and lower sides of packing layer 4 is PA2 - PA1, and the small differential pressure value PD2 on the sides of packing layer 6 is... PA3-PA2, set the upper limit (PD1max, PD2max) and lower limit (PD1min, PD2min) for the micro differential pressure values.

[0012] When any differential pressure value (PD1 or PD2) is greater than or equal to the upper limit value PD1max or PD2max, the flushing water inlet valve 1-7, flushing water inlet valve 2-15, and flushing water inlet valve 3-23 will automatically open sequentially to circulate and flush the packing layer 1-4 and packing layer 2-6. When the differential pressure value (PD1 or PD2) is less than or equal to the upper limit value PD1min or PD2min, the corresponding flushing water inlet valve will close. When the differential pressure value (PD1 or PD2) is between the lower and upper limits, flushing water inlet valve 1-7, flushing water inlet valve 2-15, and flushing water inlet valve 3-23 will remain in their original states.

Claims

1. An online detection device for minute differential pressure in desulfurized flue gas, comprising a desulfurization absorption tower, wherein a demister or packing layer is installed in the top cylinder of the desulfurization absorption tower, characterized in that, Measurement installation interfaces are provided above and below the demister or packing layer. A diaphragm pressure transmitter is installed on the measurement installation interface. A flushing water branch pipe and a purging hot air branch pipe are installed on each measurement installation interface.

2. The online detection device for minute differential pressure in desulfurized flue gas according to claim 1, characterized in that, All of the flushing water branch pipes are connected to the flushing water main pipe with the flushing water inlet valve, and all of the purging hot air branch pipes are connected to the purging hot air main pipe with the purging air inlet valve.

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