A dechlorination system and dechlorination method for co-disposal of washed fly ash in cement kiln

Abstract

The invention discloses a dechlorination system and a dechlorination method for co-disposing washed fly ash in a cement kiln. The air intake device is connected to the kiln tail smoke chamber in the kiln system, the air outlet of the circulating fan is connected to the air outlet of the air intake device and the air inlet of the heat exchanger, and the air outlet of the air intake device is also connected to the air inlet of the lower cyclone separator; the air outlet of the lower cyclone separator is connected to the air inlet of the upper cyclone separator, the ash drop port of the upper cyclone separator is connected to the air inlet of the lower cyclone separator, and the air outlet of the upper cyclone separator is connected to the air inlet of the heat exchanger; the air outlet of the heat exchanger is connected to the air inlet of the cooler, the air outlet of the cooler is connected to the air inlet of the bag dust collector, and the air outlet of the bag dust collector is respectively connected to the air inlet of the induced draft fan and the circulating fan. The dechlorination system and the dechlorination method improve the dechlorination efficiency and achieve zero emission.

Description

Technical Field

[0001] The invention relates to a dechlorination system and a dechlorination method for co-disposing washed fly ash in a cement kiln. Background Art

[0002] According to the National List of Hazardous Wastes (2016 edition), fly ash from the incineration of domestic waste is classified as hazardous waste. The Cl- content in its chemical composition is about 16%, and it can be co-disposed after water washing. The Cl- content of washed fly ash after water washing is about 1%, and the water content is about 5%. If the washed fly ash is directly fed into the decomposition furnace, in order to ensure the stability of the decomposition furnace operating conditions, coal consumption will inevitably increase. At the same time, when the amount of fly ash co-disposed of cement kilns is large, the chlorine content of the raw material is relatively high (Cl-≥0.015%). In order to ensure the normal operation of the clinker burning system, a bypass wind protection system should be added to reduce the amount of chlorine circulation.

[0003] The current dechlorination system extracts gas enriched with Cl- at about 1050℃ from the smoke chamber at the tail of the kiln, mixes it with cold air and cools it down to about 400℃, and then passes through a cyclone separator to separate the raw material from the gas before entering the decomposition furnace. This gas is cooled down to about 180℃ by a cooler, so that the chlorine, alkali and other elements in the gas cool and crystallize, and then is collected by a bag filter. According to previous studies, every 1% of bypass wind protection increases the heat consumption by about 2.0kcal / kg.cl; the cement kiln system handles 1t / h of fly ash, and washes the fly ash into the decomposition furnace, which increases by about 1.0kcal / kg.cl.

[0004] Therefore, the fly ash co-treatment of cement kilns will greatly increase the heat consumption of the system. At the same time, the fly ash produced by the dechlorination system has a high chlorine content and is difficult to treat. Summary of the invention

[0005] The purpose of the present invention is to provide a dechlorination system and a dechlorination method for co-disposing washed fly ash in a cement kiln, wherein the dechlorination system and the dechlorination method improve the dechlorination efficiency and achieve zero emission.

[0006] In order to achieve the above-mentioned object, the present invention provides a dechlorination system for the coordinated disposal of washed fly ash in a cement kiln, the dechlorination system comprising: a circulating fan, an air intake device, a lower cyclone separator, an upper cyclone separator, a heat exchanger, a cooler, a bag dust collector and an induced draft fan; the air intake device is connected to the kiln tail smoke chamber in the kiln system, the air outlet of the circulating fan is connected to the air outlet of the air intake device and the air inlet of the heat exchanger, and the air outlet of the air intake device is also connected to the air inlet of the lower cyclone separator. ; The air outlet of the lower cyclone separator is connected to the air inlet of the upper cyclone separator, the dust discharge port of the upper cyclone separator is connected to the air inlet of the lower cyclone separator, and the air outlet of the upper cyclone separator is connected to the air inlet of the heat exchanger; the air outlet of the heat exchanger is connected to the air inlet of the cooler, the air outlet of the cooler is connected to the air inlet of the bag dust collector, and the air outlet of the bag dust collector is respectively connected to the air inlets of the induced draft fan and the circulating fan.

[0007] Preferably, the ash outlet of the lower cyclone separator is connected to the decomposition furnace in the kiln system.

[0008] Preferably, the dechlorination system further comprises: a storage bin, which is connected to the high-chlorine return ash outlet of the cooler and the bag filter for collecting high-chlorine return ash.

[0009] Preferably, the storage bin is also connected to a fly ash washing system.

[0010] Preferably, the discharge port of the fly ash washing system is communicated with the air inlet of the upper cyclone separator.

[0011] The present invention also provides a dechlorination method, characterized in that the dechlorination method uses the dechlorination system according to any one of claims 1 to 6, comprising the following steps:

[0012] 1) Use the air intake device to extract a portion of the Cl-enriched gas from the kiln tail smoke chamber, mix it with the cold air introduced by the circulating fan, and cool the extracted Cl-enriched gas;

[0013] 2) The Cl-enriched gas after cooling in step 1) enters the lower cyclone separator for the first gas-solid separation, and the Cl-enriched gas after the first gas-solid separation enters the upper cyclone separator for the second gas-solid separation;

[0014] 3) The Cl-enriched gas after the second gas-solid separation enters the heat exchanger and mixes with the cold air introduced by the circulating fan, and the Cl-enriched gas after the second gas-solid separation is cooled again;

[0015] 4) The Cl-enriched gas after cooling again enters the cooler, at which time, the harmful elements in the Cl-enriched gas after cooling again crystallize in the cooler;

[0016] 5) The gas discharged from the cooler is sent to the bag dust collector, and part of the gas discharged from the bag dust collector is sent to the circulating fan, and the rest is discharged into the kiln head grate cooler through the induced draft fan.

[0017] Preferably, in step 2), after the upper cyclone separator performs the second gas-solid separation, the material located at the ash outlet enters the lower cyclone separator for further separation.

[0018] Preferably, in steps 4) and 5), the harmful elements after crystallization are sent to a storage bin, and then the high-chlorine return ash collected in the storage bin is sent to a fly ash washing system for washing.

[0019] Preferably, a part of the high-chlorine return ash after water washing is collected, and the other part is fed through the air inlet heat exchange pipe of the upper cyclone separator. After being collected by the upper cyclone separator, it enters the air inlet heat exchange pipe of the lower cyclone separator, and then the gas-solid separation is achieved through the lower cyclone separator, and then enters the decomposition furnace together with the high-chlorine return ash brought out from the kiln tail smoke chamber.

[0020] According to the above technical scheme, the dechlorination system for the cement kiln coordinated treatment of washed fly ash in the present invention improves the dechlorination efficiency and achieves zero emission.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment of a dechlorination system.

[0024] Description of Reference Numerals

[0025] 1 Kiln system 2 Air intake device

[0026] 3 decomposition furnace 4 lower cyclone separator

[0027] 5 Air inlet of lower cyclone separator 6 Upper cyclone separator

[0028] 7 Air inlet of upper cyclone separator 8 Heat exchanger

[0029] 9Cooler 10Bag dust collector

[0030] 11 Storage silo 12 Fly ash washing system

[0031] 13 induced draft fan 14 circulating fan DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0033] In the present invention, unless otherwise stated, directional words such as "up, down, top, bottom, far, near, side" contained in the terms merely represent the orientation of the terms in normal usage, or are common names understood by those skilled in the art, and should not be regarded as limitations on the terms.

[0034] See also Figure 1 A dechlorination system for co-disposing washed fly ash in a cement kiln is shown, and the dechlorination system comprises: a circulating fan 14, an air intake device 2, a lower cyclone separator 4, an upper cyclone separator 6, a heat exchanger 8, a cooler 9, a bag dust collector 10 and an induced draft fan 13; the air intake device 2 is connected to the kiln tail smoke chamber in the kiln system 1, the air outlet of the circulating fan 14 is connected to the air outlet of the air intake device 2 and the air inlet of the heat exchanger 8, and the air outlet of the air intake device 2 is also connected to the air inlet 5 of the lower cyclone separator; the lower The air outlet of the cyclone separator 4 is connected to the air inlet 7 of the upper cyclone separator, the dust outlet of the upper cyclone separator 6 is connected to the air inlet 5 of the lower cyclone separator, and the air outlet of the upper cyclone separator 6 is connected to the air inlet of the heat exchanger 8; the air outlet of the heat exchanger 8 is connected to the air inlet of the cooler 9, and the air outlet of the cooler 9 is connected to the air inlet of the bag dust collector 10, and the air outlet of the bag dust collector 10 is respectively connected to the air inlets of the induced draft fan 13 and the circulating fan 14.

[0035] Through the implementation of the above technical solutions, the dechlorination system of the cement kiln for the coordinated disposal of washed fly ash has improved the dechlorination efficiency and achieved zero emissions.

[0036] In this embodiment, in order to further feed the raw material separated by the lower cyclone separator 4 into the decomposition furnace 3, increase the amount of solid waste disposal, and increase enterprise benefits, preferably, the ash outlet of the lower cyclone separator 4 is connected to the decomposition furnace 3 in the kiln system 1.

[0037] In this embodiment, in order to further collect the high-chlorine return ash discharged from the cooler 9 and the bag dust collector 10, preferably, the dechlorination system also includes: a storage bin 11, and the storage bin 11 is connected to the high-chlorine return ash outlet of the cooler 9 and the bag dust collector 10 for collecting the high-chlorine return ash.

[0038] In this embodiment, in order to further wash the fly ash in the storage bin 11 and further dechlorinate the fly ash, preferably, the storage bin 11 is also connected to a fly ash washing system 12 .

[0039] In this embodiment, in order to further deliver the washed fly ash into the decomposition furnace 3, preferably, the discharge port of the fly ash washing system 12 is connected to the air inlet 7 of the upper cyclone separator.

[0040] The specific dechlorination process is as follows: the dechlorination system uses an air intake device 2 (such as an exhaust pump) to extract a portion of Cl-enriched gas from the kiln tail smoke chamber, mixes it with the cold air introduced by the circulating fan 14, and reduces the 1050°C gas to about 850°C within 1-3 seconds. The gas then enters a group of cyclone separator devices connected in series, that is, it enters the lower cyclone separator 4 and the upper cyclone separator 6 in sequence. The cyclone separator mainly separates the gas and the material, and at the same time, realizes the gas-solid heat exchange.

[0041] In order to prevent harmful elements such as alkali and chlorine from crystallizing before being discharged from the upper cyclone separator 6 and adhering to the surface of the raw material and entering the decomposition furnace 3, the harmful substances are discharged as much as possible. By controlling the air volume of the circulating fan 14 and the feed amount of the washed fly ash, the gas temperature is guaranteed to be around 650°C when it leaves the upper cyclone separator 6. Subsequently, this gas is mixed with another cooling air sent by the circulating fan 14 in the heat exchanger 8, and the gas temperature is reduced to 400°C within 1-3s. At this time, the harmful elements such as alkali and chlorine in the gas are crystallized. The gas temperature is further cooled by the cooler 9 to reduce it to about 180°C, and the harmful components in the gas are completely crystallized, and then collected and discharged by the bag dust collector 10. After removing the air volume after circulation, the remaining air volume is discharged into the kiln head grate cooler to achieve zero gas emission.

[0042] The high-chlorine return ash collected by the cooler 9 and the bag filter 10 has a high Cl- content and is difficult to handle. Therefore, the collected high-chlorine return ash is transported to the fly ash washing system 12, and then chlorine is further removed and then co-processed, that is, a part of the high-chlorine return ash after washing is collected, and the other part of the high-chlorine return ash after washing is fed through the heat exchange pipe of the air inlet 7 of the upper cyclone separator 6, and after being collected by the upper cyclone separator 6, it enters the heat exchange pipe of the air inlet 5 of the lower cyclone separator 4, and then realizes gas-solid separation through the lower cyclone separator 4, and enters the decomposition furnace 3 together with the high-chlorine return ash brought out of the smoke chamber by the high-temperature gas. At this time, the temperature of the washed fly ash after heat exchange is 700℃-800℃, which has little effect on the working condition of the decomposition furnace 3.

[0043] The present invention increases the temperature of the gas discharged from the upper cyclone separator 6, ensures the chlorine and alkali content in the gas to be treated, and thus improves the dechlorination efficiency of the dechlorination system. At the same time, the heat of the dechlorination system is recovered, the temperature of the fly ash entering the decomposition furnace 3 for water washing is increased, and the effective use of heat is ensured. According to the calculation of 5000t / d production line and 4% bypass wind volume, after comprehensive consideration, about 1.0kg / t.cl standard coal consumption can be saved. At the same time, the system exhaust gas is discharged into the kiln head grate cooler as cooling air, and the high-chlorine return ash is transported to the fly ash washing system 12, and reused after dechlorination, to achieve zero emission of system gas and materials.

[0044] The present invention is applied to the raw fuel and water-washed fly ash used in the clinker burning system, which have high sulfur, alkali and chlorine contents and a large bypass wind volume. Generally, the air volume is above 3%, and the energy-saving effect is better.

[0045] Taking 3500Nm3 / h extracted from the kiln tail smoke chamber for the bypass wind protection system as an example, the temperature of the cooling air is 180℃, and the cooling air volume should be 1150Nm3 / h to ensure that the inlet temperature of the lower cyclone separator 4 is about 850℃. At the same time, in order to ensure that the outlet temperature of the upper cyclone separator 6 is about 650℃, the feed amount of fly ash after water washing should be less than 2t / h, and the processing capacity is about 48t / d. At this time, the solid-gas ratio in the cyclone separator is about 0.33, and it can operate normally. At the same time, the air volume entering the heat exchanger 8 is 4650Nm3 / h, and the temperature is about 650℃. To remove the heat absorbed by the heat exchanger 8, the amount of cold air added should be about 2500Nm3 / h. Therefore, the cooler 9 and the bag dust collector 10 process the air volume at 7150Nm3 / h, and the circulating air volume is about 3650Nm3 / h. Without considering the air leakage of the system, the air volume entering the kiln head grate cooler is about 3500Nm3 / h.

[0046] The present invention also provides a dechlorination method, which comprises the following steps:

[0047] 1) A portion of the Cl-enriched gas is extracted from the kiln tail smoke chamber using the air intake device 2, mixed with the cold air introduced by the circulating fan 14, and the extracted Cl-enriched gas is cooled;

[0048] 2) The Cl-enriched gas after cooling in step 1) enters the lower cyclone separator 4 for the first gas-solid separation, and the Cl-enriched gas after the first gas-solid separation enters the upper cyclone separator 6 for the second gas-solid separation;

[0049] 3) The Cl-enriched gas after the second gas-solid separation enters the heat exchanger 8 and mixes with the cold air introduced by the circulating fan 14, and the Cl-enriched gas after the second gas-solid separation is cooled again;

[0050] 4) The Cl-enriched gas after cooling again enters the cooler 9, at which time, the harmful elements in the Cl-enriched gas after cooling again crystallize in the cooler 9;

[0051] 5) The gas discharged from the cooler 9 is sent to the bag dust collector 10, and part of the gas discharged from the bag dust collector 10 is sent to the circulating fan 14, and the rest is discharged into the cellar head grate cooler through the induced draft fan 13.

[0052] In this embodiment, in order to improve the separation rate, preferably, in step 2), after the upper cyclone separator 6 performs the second gas-solid separation, the material located at the ash outlet enters the lower cyclone separator 4 for further separation.

[0053] In this embodiment, in order to further collect and process the high-chlorine return ash, preferably, in steps 4) and 5), the crystallized harmful elements are sent to the storage bin 11, and then the collected high-chlorine return ash in the storage bin 11 is sent to the fly ash washing system 12 for washing.

[0054] In this embodiment, preferably, a part of the high-chlorine return ash after water washing is collected, and the other part is fed through the heat exchange pipe of the air inlet 7 of the upper cyclone separator 6, and after being collected by the upper cyclone separator 6, enters the heat exchange pipe of the air inlet 5 of the lower cyclone separator 4, and then achieves gas-solid separation through the lower cyclone separator 4, and enters the decomposition furnace 3 together with the high-chlorine return ash brought out from the kiln tail smoke chamber. By controlling the air volume of the circulating fan 14 and the feeding amount of the washed fly ash, it is ensured that the gas temperature is about 650°C when leaving the upper cyclone separator 6.

[0055] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0056] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0057] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for dechlorination, characterized in that: The dechlorination method comprises the following steps: 1) Use the air extraction device (2) Extract a portion of the enriched Cl from the kiln tail smoke chamber - The gas is mixed with the cold air introduced by the circulating fan (14) to extract the enriched Cl - The gas is cooled; 2) Enriched Cl after cooling in step 1) - The gas enters the lower cyclone separator (4) for the first gas-solid separation. The enriched Cl - The gas enters the upper cyclone separator (6) for a second gas-solid separation; 3) Enriched Cl after the second gas-solid separation - The gas enters the heat exchanger (8) and mixes with the cold air introduced by the circulating fan (14) to separate the Cl - The gas is cooled again; 4) Enriched Cl after cooling again - The gas enters the cooler (9), at which point the Cl enriched gas is cooled again. - Harmful elements in the gas are crystallized in the cooler (9); 5) sending the gas discharged from the cooler (9) into a bag filter (10), sending part of the gas discharged from the bag filter (10) into a circulating fan (14), and the rest of the gas discharged into a cellar head grate cooler through an induced draft fan (13); The dechlorination method uses a dechlorination system for co-disposing washed fly ash in a cement kiln, the dechlorination system comprising: a circulating fan (14), an air intake device (2), a lower cyclone separator (4), an upper cyclone separator (6), a heat exchanger (8), a cooler (9), a bag filter (10) and an induced draft fan (13); The air intake device (2) is connected to the kiln tail smoke chamber in the kiln system (1); the air outlet of the circulating fan (14) is connected to the air outlet of the air intake device (2) and the air inlet of the heat exchanger (8); the air outlet of the air intake device (2) is also connected to the air inlet (5) of the lower cyclone separator; The air outlet of the lower cyclone separator (4) is connected to the air inlet (7) of the upper cyclone separator, the ash outlet of the upper cyclone separator (6) is connected to the air inlet (5) of the lower cyclone separator, and the air outlet of the upper cyclone separator (6) is connected to the air inlet of the heat exchanger (8); The air outlet of the heat exchanger (8) is connected to the air inlet of the cooler (9), the air outlet of the cooler (9) is connected to the air inlet of the bag dust collector (10), and the air outlet of the bag dust collector (10) is respectively connected to the air inlets of the induced draft fan (13) and the circulating fan (14); In steps 4) and 5), the harmful elements after crystallization are sent to a storage bin (11), and then the high-chlorine return ash collected in the storage bin (11) is sent to a fly ash washing system (12) for washing; A portion of the high-chlorine return ash after water washing is collected, and the other portion is fed through the air inlet (7) of the upper cyclone separator (6). After being collected by the upper cyclone separator (6), the other portion enters the air inlet (5) of the lower cyclone separator (4). Subsequently, the gas-solid separation is achieved by the lower cyclone separator (4), and the other portion enters the decomposition furnace (3) together with the high-chlorine return ash brought out from the kiln tail smoke chamber.

2. The dechlorination method according to claim 1, characterized in that: The ash outlet of the lower cyclone separator (4) is in communication with the decomposition furnace (3) in the kiln system (1).

3. The dechlorination method according to claim 1, characterized in that: In step 2), after the upper cyclone separator (6) performs the second gas-solid separation, the material located at the ash outlet enters the lower cyclone separator (4) for further separation.

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