CN107843465A - A kind of two-stage type fume duct fly ash sampler - Google Patents

Abstract

A two-stage flue fly ash sampling device includes: a flange, a fly ash sampling gun, a primary cyclone separator, a primary air extractor, a secondary cyclone separator and a secondary air extractor. The method of two-stage separation is adopted. The medium carrying fly ash in the first-stage separation is flue gas, and the medium carrying fly ash in the second-stage separation is air. The sampling pipeline of the first-stage separation is in the flue and cannot directly contact with the external environment. The sampling pipeline part of the secondary separation is outside the flue, but due to the low dew point temperature of the air, the wall temperature of the secondary separation sampling pipeline can always be higher than the dew point temperature of the air, thus completely avoiding the water vapor in the flue gas during fly ash sampling The condensation problem of the fly ash sampling device is improved, and the reliability of the fly ash sampling device is improved. At the same time, during the secondary separation, the method of isolating the pipeline of the fly ash sampling gun is adopted, which prevents the fly ash of the primary separation from being sucked back by the negative pressure in the flue, and ensures the realization of the two-stage separation method.

Description

A Two-Stage Flue Ash Sampling Device

technical field

The invention relates to the field of fly ash sampling, in particular to a two-stage flue fly ash sampling device.

Background technique

Fly ash is a fine particle formed after pulverized coal is burned in the boiler furnace, which enters the tail flue along with the flue gas. The percentage of the mass of unburned carbon in the fly ash to the mass of the fly ash is called the carbon content of the fly ash. The carbon content of fly ash is the main indicator reflecting the combustion effect of the boiler, and has a great impact on the economic operation of coal-fired units. Therefore, thermal power plants need to sample and test fly ash every day. Operators optimize the operation mode according to the test results. Control the carbon content index of fly ash within a certain range.

There are two ways to routinely monitor the carbon content of common fly ash. One is to take samples on site, and then take the samples to the laboratory for testing, and the other is to measure the carbon content of fly ash online. These two methods require fly ash sampling, and the suction fly ash sampling method is generally used for fly ash sampling. Under the action of suction force, the flue gas carrying fly ash enters the fly ash sampling gun and is separated when it passes through the cyclone separator. The main problem with the suction sampling method is the condensation of water vapor in the flue gas in the sampling line. In suction fly ash sampling, the fume flows through a sampling line that is partially installed in the atmosphere. Therefore, the temperature of the flue gas will gradually decrease, and the water vapor in the flue gas will condense due to the lowering of the flue gas temperature or when it contacts the wall with a lower temperature, resulting in the deposition of fly ash until the sampling pipeline is blocked.

Therefore, it is hoped to obtain a coal-fired boiler flue fly ash sampling method that can effectively avoid the condensation of water vapor in the boiler flue gas, obtain real and reliable test data of the carbon content of the fly ash, and realize the carbon content of the fly ash. effective supervision.

Contents of the invention

In order to overcome the deficiencies of the above technologies, the present invention provides a two-stage flue ash sampling device which avoids the condensation of water vapor in the flue gas during fly ash sampling and improves the working reliability of the fly ash sampling device.

The technical scheme that the present invention overcomes its technical problem adopts is:

A two-stage flue fly ash sampling device, comprising:

Flanges arranged on the flue;

Fly ash sampling gun, one end of which is located in the flue, and the other end passes through the flange and is connected to the isolation valve of the fly ash sampling gun;

The primary cyclone separator is located in the flange, and its air inlet is connected with the fly ash sampling gun;

The primary air extractor is located on the outside of the flange. Its air suction port is connected to the exhaust end of the primary cyclone separator through the primary air extraction pipe. Its air inlet is connected to a primary pneumatic air intake valve. Connected to each other, and a primary air return pneumatic valve is set on the primary air return pipe;

The secondary cyclone separator is located on the outside of the flange. Its air inlet is connected to the flue through the secondary exhaust pipe. The ash outlet of the primary cyclone separator is connected to the secondary exhaust pipe. The primary cyclone separator is separated from the secondary cyclone A secondary extraction valve B is provided on the secondary extraction pipe between the primary cyclone separators, and a secondary extraction valve A is provided on the secondary extraction pipe outside the flue of the primary cyclone separator;

The secondary air extractor is located on the outside of the flange. Its air extraction port is connected to the exhaust end of the secondary cyclone separator, its air inlet is connected to a secondary pneumatic air intake valve, and its air outlet is connected to the flue through a secondary air return pipe. Pass.

In order to measure the flue gas flow, it also includes a primary wind measuring device arranged on the primary exhaust pipe.

In order to measure the flue gas flow, it also includes a secondary wind measuring device arranged between the first air inlet of the secondary air extractor and the exhaust port of the secondary cyclone separator.

In order to adjust the intake pressure conveniently, a primary compressed air pressure regulating valve connected to the primary pneumatic intake valve is also included.

In order to adjust the intake pressure conveniently, a secondary compressed air pressure regulating valve connected to the secondary pneumatic intake valve is also included.

In order to facilitate the control, it also includes a secondary return air pneumatic valve arranged on the secondary return air pipe.

In order to protect the fly ash sampling gun, a ceramic sleeve is also included, and the ceramic sleeve is set on the outside of the fly ash sampling gun.

In order to facilitate the storage of fly ash samples, the ash discharge port of the above-mentioned secondary cyclone separator is connected with an ash collection tank.

It also includes an instrument box arranged on the flange and a controller installed on the instrument box, the isolation valve of the sampling gun, the primary pneumatic air intake valve, the secondary air extraction valve A, the secondary air extraction valve B and the secondary pneumatic air intake valve. The air intake valves are all installed on the instrument box and connected with the controller respectively.

The beneficial effects of the present invention are as follows: the method of two-stage separation is adopted, the medium carrying the fly ash is flue gas during the one-stage separation, the medium carrying the fly ash during the two-stage separation is air, the sampling pipeline of the one-stage separation is in the flue, It cannot be in direct contact with the external environment, and the sampling pipeline part of the secondary separation is outside the flue, but due to the low dew point temperature of the air, the wall temperature of the secondary separation sampling pipeline can always be higher than the air dew point temperature, thus completely avoiding fly ash The condensation of water vapor in the flue gas during sampling improves the reliability of the fly ash sampling device. At the same time, during the secondary separation, the method of isolating the pipeline of the fly ash sampling gun is adopted, which prevents the fly ash of the primary separation from being sucked back by the negative pressure in the flue, and ensures the realization of the two-stage separation method.

Description of drawings

Fig. 1 is a structural representation of the present invention;

In the figure, 1. Fly ash sampling gun 2. Ceramic sleeve 3. Secondary suction pipe 4. Flange 5. Primary suction pipe 6. Primary air return pneumatic valve 7. Primary air return pipe 8. Controller 9. Primary pneumatic inlet Air valve 10. Primary compressed air pressure regulating valve 11. Instrument box 12. Primary air extractor 13. Primary wind measuring device 14. Secondary compressed air pressure regulating valve 15. Secondary pneumatic intake valve 16. Secondary air extractor 17. Secondary wind measuring device 18. Secondary cyclone separator 19. Ash tank 20. Secondary air extraction valve A21. Fly ash sampling gun isolation valve 22. Secondary return air pneumatic valve 23. Secondary air extraction valve B 24 . Primary cyclone separator 25. Secondary air return pipe.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing 1.

According to the principle of engineering thermodynamics, when the content of unsaturated water vapor in the mixed gas containing water vapor remains constant and the temperature gradually decreases, the water vapor is in an isobaric cooling process, and when it reaches a certain temperature point, the water vapor reaches a saturated state. If cooled again, water droplets will precipitate out. The dew point temperature is the saturation temperature corresponding to a certain partial pressure of water vapor.

The flue gas generated after coal combustion mainly contains nitrogen, carbon dioxide, oxygen, water vapor and other gases. The sources of water vapor in the flue gas mainly include the evaporation of water in the fuel, the water vapor generated by the combustion of hydrogen in the fuel, and the water vapor carried in the combustion air. By measuring the negative pressure of the flue gas and the volume percentage of water vapor in the flue gas, the partial pressure of the water vapor can be obtained, and then the saturation temperature of the water vapor under the corresponding pressure can be found through the water vapor meter, that is, the dew point temperature of the water vapor in the flue gas. In the flue gas produced by coal-fired boilers under normal pressure, the partial pressure of water vapor is about 0.01-0.015 MPa, and the corresponding dew point temperature of water vapor is 45-54 °C.

For air, it mainly contains gases such as nitrogen, oxygen, and water vapor. The dry bulb temperature and relative humidity can be measured by the dry wet bulb hygrometer. The corresponding saturation pressure at this temperature can be found through the water vapor table, and then the partial pressure of water vapor in the air can be calculated, and then the corresponding saturation temperature under the corresponding water vapor pressure can be found through the water vapor table, that is, the water vapor in the air The dew point temperature of the vapor. The actual measurement shows that for the Shandong area, the dew point temperature in the air in summer is 20-25°C, and the dew point temperature in winter can be reduced to -10-2°C.

The fly ash sampling device is generally installed on the tail flue at the outlet of the air preheater, and the flue gas temperature is generally 120-150 °C. When the flue gas passes through the sampling pipeline exposed to the environment, if the pipe wall temperature is lower than the dew point temperature of the water vapor in the flue gas, the water vapor in the flue gas will condense, and the fly ash particles in the flue gas encounter water droplets It will deposit and even block the sampling pipeline. Especially when winter comes, the ambient temperature will drop to -15°C. At this time, the wall temperature of the sampling pipeline exposed to the environment is difficult to maintain 45-54°C, and the water vapor in the flue gas will condense.

It can be seen from the above calculation that the dew point temperature of water vapor in the air is relatively low, and the dew point temperature is -10 ~ 2°C in winter. If the fly ash is carried by air instead, the wall temperature of the sampling pipeline exposed to the environment will not be as low as -10°C even if it is lower, that is to say, it is easy to keep above the water vapor dew point temperature, and it will not There is a problem that water vapor condensation blocks the sampling pipeline.

According to the above thinking, a two-stage flue ash sampling device of the present invention includes: a flange 4 arranged on the flue; a fly ash sampling gun 1, one end of which is located in the flue, and the other end passes through the flange 4 Afterwards, it is connected to the isolation valve 21 of the fly ash sampling gun; the primary cyclone separator 24 is located in the flange 4, and its air inlet is connected to the fly ash sampling gun 1; the primary air extractor 12 is located outside the flange 4, and its air intake port The exhaust end of the primary cyclone separator 24 is connected through the primary exhaust pipe 5, and its air inlet is connected with a primary pneumatic air inlet valve 9, and its air outlet is connected with the flue through the primary air return pipe 7, and the primary air return pipe 7 is provided with There is a primary air return pneumatic valve 6; the secondary cyclone separator 18 is located outside the flange 4, and its air intake end is connected to the flue through the secondary exhaust pipe 3, and the ash discharge port of the primary cyclone separator 24 is connected to the secondary exhaust pipe 3 connected, the secondary air extraction pipe 3 between the primary cyclone separator 24 and the secondary cyclone separator 18 is provided with a secondary air extraction valve B 23, and the secondary air extraction pipe 3 outside the flue of the primary cyclone separator 24 is provided with There is a secondary air extraction valve A 20; the secondary air extractor 16 is located outside the flange 4, its air extraction port is connected to the exhaust end of the secondary cyclone separator 18, and its air inlet is connected to a secondary pneumatic air intake valve 15. Its air outlet communicates with the flue through the secondary air return pipe 25.

When the boiler is running normally, the flue gas in the flue carries the fly ash and flows through the flue. First close the secondary air extraction valve A 20 and the secondary air extraction valve B 23, open the primary pneumatic air intake valve 9, and the compressed air flows through the primary air extractor 12 to generate a large negative pressure, which is lower than that in the flue. Flue gas negative pressure. Under the action of differential pressure, the flue gas flow carrying fly ash enters the suction port of the fly ash sampling gun 1 , and enters the primary cyclone separator 24 through the sampling gun pipeline of the fly ash sampling gun 1 . In the primary cyclone separator 24, the gas-solid separation of the flue gas and the fly ash occurs, and the fly ash particles are thrown to the wall of the separator under the action of centrifugal force and slide down along the wall to the secondary extraction at the lower part of the primary cyclone separator 24. In the air pipe 3, the flue gas enters the primary exhaust pipe 5, and finally enters the primary air extractor 12 to mix with compressed air, and then is discharged back to the flue through the primary air return pipe 7. It is known from experiments that after the primary cyclone separator 24 works continuously for 100s, about 2g of fly ash particles accumulate in the secondary exhaust pipe 3 at the lower part of the primary cyclone separator 24 . Afterwards, the primary pneumatic air inlet valve 9 is closed, and the primary cyclone separator 24 stops working. At the same time, the primary return air pneumatic valve 6 and the fly ash sampling gun isolation valve 21 are closed, and the secondary cyclone separator 18 is completely isolated from the flue gas in the flue.

The secondary air extraction valve A 20 and the secondary air extraction valve B 23 open the secondary pneumatic air intake valve 15, and the compressed air flows through the secondary air extraction device 16, which also produces a large negative pressure, which is lower than the ambient atmospheric pressure. Under the action of differential pressure, the air outside the flue flows through the secondary exhaust valve A 20 and the secondary exhaust pipe 3, and carries the fly ash separated by the primary cyclone separator 24 and accumulated in the secondary exhaust pipe through the secondary exhaust. Air valve B 23 enters secondary cyclone 18 . In the secondary cyclone separator 18, air and fly ash undergo gas-solid separation, and the fly ash particles are thrown to the wall of the separator under the action of centrifugal force and slide down along the wall to the ash discharge port at the lower part of the secondary cyclone separator. Air enters the secondary air extractor 16 to mix with compressed air, and then is discharged back to the flue through the secondary air return pipe 25 . After the secondary cyclone separator 18 works continuously for a certain period of time, the secondary pneumatic air intake valve 15, the secondary air extraction valve A 20 and the secondary air extraction valve B 23 are closed in sequence, and the fly ash sampling device completes the primary sampling. The above actions are repeated, and enough fly ash can be taken from the ash discharge port at the lower part of the secondary cyclone separator for laboratory analysis of the carbon content of the fly ash.

This two-stage flue ash sampling device adopts a two-stage separation method. The medium carrying fly ash in the first stage separation is flue gas, and the medium carrying fly ash in the second stage separation is air. The sampling pipeline of the first stage separation is Inside the flue, there is no direct contact with the external environment, and the sampling pipeline part of the secondary separation is outside the flue, but due to the low dew point temperature of the air, the wall temperature of the secondary separation sampling pipeline can always be higher than the air dew point temperature, thereby completely avoiding The problem of water vapor condensation in the flue gas during fly ash sampling is solved, and the working reliability of the fly ash sampling device is improved. At the same time, during the secondary separation, the method of isolating the pipeline of the fly ash sampling gun is adopted, which prevents the fly ash of the primary separation from being sucked back by the negative pressure in the flue, and ensures the realization of the two-stage separation method.

Further, it also includes a primary wind measuring device 13 arranged on the primary air extraction pipe 5 and a secondary wind measuring device arranged between the first air inlet of the secondary air extractor 16 and the exhaust port of the secondary cyclone separator 18 17. The function of primary wind measuring device 13 is to measure flue gas flow during primary separation. The effect of the secondary air measuring device 17 is to measure the air flow during secondary separation.

Further, it also includes a primary compressed air pressure regulating valve 10 connected to the primary pneumatic air intake valve 9 . And the secondary compressed air pressure regulating valve 14 connected to the secondary pneumatic air intake valve 15. The function of the primary compressed air pressure regulating valve 10 is to regulate the intake pressure of the primary air extractor 12 , and the effect of the secondary compressed air pressure regulating valve 14 is to regulate the intake pressure of the secondary air extractor 16 .

Preferably, a secondary air return pneumatic valve 22 arranged on the secondary air return pipe 25 is also included. The secondary return air pneumatic valve 22 can be controlled to open or disconnect the secondary return air pipe 15 . It also includes a ceramic casing 2, which is set on the outside of the fly ash sampling gun 1. The effect of ceramic bushing 2 is to be set on the outside of fly ash sampling gun 1 to prevent fly ash sampling gun 1 from being scoured and worn by flue gas. The reliability of the overall use is further improved. The ash discharge port of the secondary cyclone separator 18 is connected with an ash tank 19, and the function of the ash tank 19 is to store the fly ash samples taken, which improves the convenience of operation.

Preferably, it also includes an instrument case 11 arranged on the flange 4 and a controller 8 installed on the instrument case 11, a sampling gun isolation valve 21, a primary pneumatic air intake valve 9, a secondary air extraction valve A 20, a secondary Both the exhaust valve B 23 and the secondary pneumatic air intake valve 15 are installed on the instrument case 11 and are respectively connected to the controller 8 under control. The controller 8 controls the sampling gun isolation valve 21, the primary pneumatic air intake valve 9, the secondary air intake valve A 20, the secondary air extraction valve B 23 and the secondary air intake valve 15 to automatically open or close in sequence, which improves the automation level of control.

Claims (9)

1. A two-stage flue fly ash sampling device, characterized in that it comprises: A flange (4) arranged on the flue; A fly ash sampling gun (1), one end of which is located in the flue, and the other end passes through the flange (4) and is connected to the fly ash sampling gun isolation valve (21); The primary cyclone separator (24) is located in the flange (4), and its air intake end is connected with the fly ash sampling gun (1); The primary air extractor (12) is located on the outside of the flange (4), and its air suction port is connected to the exhaust end of the primary cyclone separator (24) through the primary air extraction pipe (5), and its air inlet is connected to a primary pneumatic air intake Valve (9), the air outlet of which is connected to the flue through the primary air return pipe (7), and the primary air return pipe (7) is provided with a primary air return pneumatic valve (6); The secondary cyclone separator (18) is located outside the flange (4), and its air inlet is connected to the flue through the secondary exhaust pipe (3). The air pipe (3) is connected, and the secondary air extraction pipe (3) between the primary cyclone separator (24) and the secondary cyclone separator (18) is provided with a secondary air extraction valve B (23), and the primary cyclone separator ( 24) The secondary exhaust pipe (3) outside the flue is provided with a secondary exhaust valve A (20); The secondary air extractor (16) is located outside the flange (4), its air suction port is connected to the exhaust end of the secondary cyclone separator (18), and its air inlet is connected to the secondary pneumatic air intake valve (15) , the gas outlet communicates with the flue through the secondary air return pipe (25). 2. The two-stage flue fly ash sampling device according to claim 1, characterized in that it further comprises a primary wind measuring device (13) arranged on the primary air extraction pipe (5). 3. The two-stage flue fly ash sampling device according to claim 1, characterized in that it also includes the first air inlet of the secondary air extractor (16) and the row of secondary cyclone separator (18). Secondary wind measuring device (17) between gas ports. 4. The two-stage flue fly ash sampling device according to claim 1, characterized in that it further comprises a primary compressed air pressure regulating valve (10) connected to the primary pneumatic inlet valve (9). 5. The two-stage flue fly ash sampling device according to claim 1, characterized in that it further comprises a secondary compressed air pressure regulating valve (14) connected to the secondary pneumatic air intake valve (15). 6. The two-stage flue fly ash sampling device according to claim 1, characterized in that it further comprises a secondary air return pneumatic valve (22) arranged on the secondary air return pipe (25). 7. The two-stage flue ash sampling device according to claim 1, characterized in that it also includes a ceramic sleeve (2), and the ceramic sleeve (2) is set on the outside of the fly ash sampling gun (1) . 8. The two-stage flue fly ash sampling device according to claim 1, characterized in that: the ash discharge port of the secondary cyclone separator (18) is connected with an ash collection tank (19). 9. The two-stage flue fly ash sampling device according to claim 1, characterized in that it also includes an instrument box (11) installed on the flange (4) and a control panel installed on the instrument box (11) device (8), the sampling gun isolation valve (21), primary pneumatic air intake valve (9), secondary air extraction valve A (20), secondary air extraction valve B (23) and secondary pneumatic air intake valve (15) are all installed on the instrument box (11), and are respectively connected with the controller (8).