A nitrogen circulation sulfur concentrate drying and heat recovery system and method

Abstract

The present invention provides a sulfur concentrate drying and heat recovery system with nitrogen circulation, including a sulfur concentrate drying mechanism, a circulating nitrogen dehydration mechanism and a heat recovery mechanism. Compared with the prior art, the present invention provides a sulfur concentrate drying and heat recovery system with nitrogen circulation, which uses a multi-stage cyclone separator and a multi-stage venturi to exchange heat between pyrolysis slag and nitrogen, recovers the heat in the high-temperature pyrolysis slag to heat the nitrogen, and uses the heated nitrogen for pre-drying of wet sulfur concentrate, thereby improving the heat exchange efficiency and heat recovery efficiency of the system; and adopts a nitrogen double circulation mode, namely a large nitrogen circulation and a small nitrogen circulation, and the nitrogen in the two nitrogen circulations is continuously recycled and replenished on a fixed schedule, thereby reducing nitrogen consumption, reducing production costs, and improving the safety of the system.

Description

Technical Field

[0001] The invention relates to the technical field of drying and heat recovery, in particular to a nitrogen-circulating sulfur concentrate drying and heat recovery system and method. Background Art

[0002] At present, my country's sulfur resources rely on pyrite and associated pyrite ores, mainly pyrolysis of pyrite to produce sulfur and pyrolysis slag. Therefore, improving the pyrolysis process of pyrite is crucial to improving the recovery of sulfur resources.

[0003] At present, the pyrolysis process for producing pyrite mainly adopts a three-stage series operation of a drying rotary kiln, a pyrolysis rotary kiln and a cooling rotary kiln. However, the drying and pyrolysis processes of this pyrolysis process require a large amount of heat from the outside, and the cooling rotary kiln needs to provide a large amount of cold, resulting in a serious waste of heat. At the same time, since the rotary kiln mainly relies on external heat sources to indirectly heat the material, the energy utilization rate is low. In addition, since oxygen cannot exist during the pyrolysis process of pyrite, the system must maintain an inert (nitrogen) environment. Summary of the invention

[0004] In view of the above problems, the present invention provides a sulfur concentrate drying and heat recovery system with nitrogen circulation, which adopts multi-stage cyclone separators and multi-stage venturis to exchange heat between pyrolysis slag and nitrogen, recovers the heat in the high-temperature pyrolysis slag to heat the nitrogen, and uses the heated nitrogen for pre-drying of wet sulfur concentrate, thereby improving the heat exchange efficiency and heat recovery efficiency of the system.

[0005] The technical solution adopted by the present invention is:

[0006] A sulfur concentrate drying and heat recovery system with nitrogen circulation, characterized in that it includes a sulfur concentrate drying mechanism, a circulating nitrogen dehydration mechanism and a heat recovery mechanism, the sulfur concentrate drying mechanism includes a predryer for inputting hot nitrogen to dry wet sulfur concentrate, a first bag filter connected to the predryer for separating the dried sulfur concentrate from the nitrogen, a first venturi connected to the first bag filter for receiving the sulfur concentrate separated by the first bag filter and mixing with the hot nitrogen for preheating, and a first cyclone separator connected to the first venturi for separating the preheated sulfur concentrate and nitrogen; the circulating nitrogen dehydration mechanism includes a dehydration tower for receiving a part of the nitrogen separated from the first bag filter for dehydration, and a first induced draft fan connected to the dehydration tower for outputting another part of the nitrogen separated from the first bag filter and the dehydrated nitrogen in the dehydration tower; the heat recovery mechanism includes a first induced draft fan for receiving the nitrogen separated by the first cyclone separator and the high-temperature pyrolysis a second venturi for collecting slag, a second cyclone separator connected to the second venturi for separating the mixed hot nitrogen and the pyrolysis slag, a third venturi connected to the second cyclone separator and the fourth cyclone separator for mixing nitrogen with the pyrolysis slag for first-stage heat recovery, a third cyclone separator connected to the third venturi for separating the pyrolysis slag from nitrogen, a fourth venturi connected to the second bag separator and the fourth cyclone separator for mixing nitrogen with the pyrolysis slag for second-stage heat recovery, a fourth cyclone separator connected to the fourth venturi for separating the pyrolysis slag from nitrogen, a fifth venturi connected to the first induced draft fan for mixing dehydrated mixed nitrogen with the pyrolysis slag for third-stage heat recovery, a second bag separator connected to the fifth venturi for separating the pyrolysis slag from nitrogen to obtain a pyrolysis slag product, a discharge port of the third cyclone separator is connected to the feed port of the fourth venturi, and an air outlet of the third cyclone separator is connected to the pre-dryer.

[0007] Preferably, part of the water removed by the dehydration tower is led out by a circulation pump, and part of it returns to the dehydration tower after heat exchange in a heat exchanger.

[0008] Preferably, a second induced draft fan is provided between the first cyclone separator and the second venturi; and a third induced draft fan is provided between the second bag filter and the fourth venturi.

[0009] Preferably, the pre-dryer is connected to a screw conveyor for conveying wet sulfur concentrate.

[0010] More preferably, the second venturi for inputting high-temperature pyrolysis slag, the second cyclone separator, the first venturi, the first cyclone separator and the second induced draft fan form a small nitrogen circulation mechanism.

[0011] More preferably, the circulating nitrogen dehydration mechanism, the fifth venturi, the second bag filter, the third induced draft fan, the fourth venturi, the fourth cyclone separator, the third venturi, the third cyclone separator, the pre-dryer and the first bag separator constitute a large nitrogen circulation mechanism.

[0012] Preferably, the system is also provided with a nitrogen replenishment pipe opening and a fixed discharge pipe opening.

[0013] The present invention also provides a method for drying sulfur concentrate and recovering heat with nitrogen circulation, comprising the following steps:

[0014] 1) Hot nitrogen is input into the pre-dryer to dry the wet sulfur concentrate to reduce the moisture content of the sulfur concentrate to less than 1%;

[0015] 2) The dried sulfur concentrate and the water-containing nitrogen in step 1) are separated in the first bag filter, the separated sulfur concentrate enters the first venturi and is mixed with the hot nitrogen for preheating, and the preheated sulfur concentrate enters the first cyclone separator for separation to obtain the preheated sulfur concentrate and cold nitrogen;

[0016] 3) The cold nitrogen obtained in step 2) enters the second venturi with high-temperature pyrolysis slag for heat exchange to form hot nitrogen and preliminarily cool the pyrolysis slag, the hot nitrogen and the preliminarily cooled pyrolysis slag enter the second cyclone separator for separation, the separated hot nitrogen is input into the first venturi in step 2), and the preliminarily cooled pyrolysis slag enters the third venturi;

[0017] 4) A portion of the nitrogen containing water in step 2) enters the dehydration tower for drying, and the dried nitrogen is mixed with another portion of the nitrogen containing water to form dehydrated mixed cold nitrogen and enter the fifth venturi;

[0018] 5) In step 3), the second heated nitrogen is input into the third venturi to complete the first stage heat recovery, the pyrolysis slag is preliminarily cooled to heat the second heated nitrogen for the third time, and the cooled pyrolysis slag and the heated nitrogen enter the third cyclone separator to separate into the first stage cooled pyrolysis slag and the third heated nitrogen;

[0019] 6) The third heating nitrogen obtained in step 5) is input into the pre-dryer in step 1); the first stage cooling pyrolysis slag enters the fourth venturi;

[0020] 7) The first heated nitrogen is input into the fourth venturi in step 6) to complete the second stage heat recovery, the first stage cooling pyrolysis slag heats the first heated nitrogen, and the cooled pyrolysis slag and heated nitrogen enter the fourth cyclone separator to separate into the second stage cooling pyrolysis slag and the second heated nitrogen;

[0021] 8) The second heating nitrogen obtained in step 7) is input into the third venturi in step 5); the second stage cooling pyrolysis slag is input into the fifth venturi in step 4);

[0022] 9) In step 8), the second-stage pyrolysis slag in the fifth venturi completes the third-stage heat recovery of the dehydrated mixed cold nitrogen, the second-stage cooled pyrolysis slag heats the dehydrated mixed cold nitrogen, the cooled pyrolysis slag and the heated nitrogen enter the second bag separator to separate the cooled pyrolysis slag product and the first heated nitrogen, and the first heated nitrogen is input into the fourth venturi of step 7).

[0023] Preferably, part of the water removed from the dehydration tower in step 4) is led out by a circulation pump, and the other part returns to the dehydration tower after heat exchange in a heat exchanger.

[0024] Preferably, the nitrogen separated by the first cyclone separator in step 2) is input into the second venturi by the second induced draft fan; and the first heated nitrogen separated by the second bag separator in step 9) is input into the fourth venturi by the third induced draft fan.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a sulfur concentrate drying and heat recovery system with nitrogen circulation, adopts a multi-stage cyclone separator and a multi-stage venturi to exchange heat between pyrolysis slag and nitrogen, recovers the heat in the high-temperature pyrolysis slag to heat the nitrogen, and uses the heated nitrogen for pre-drying of wet sulfur concentrate, thereby improving the heat exchange efficiency and heat recovery efficiency of the system; and adopts a nitrogen double circulation mode, namely a large nitrogen circulation and a small nitrogen circulation, the nitrogen in the two nitrogen circulations is continuously recycled and scheduled and replenished, thereby reducing nitrogen consumption, reducing production costs, and improving the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 , which is a flow chart of a sulfur concentrate drying and heat recovery system with nitrogen circulation provided by the present invention. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described in detail with reference to the accompanying drawings.

[0028] Figure 1 , which is a preferred embodiment of a sulfur concentrate drying and heat recovery system with nitrogen circulation provided by the present invention. Figure 1As shown, the sulfur concentrate drying and heat recovery system with nitrogen circulation includes a sulfur concentrate drying mechanism 1, a circulating nitrogen dehydration mechanism 2 and a heat recovery mechanism 3. The sulfur concentrate drying mechanism 1 uses hot nitrogen to dry the input wet sulfur concentrate and exchange heat with high-temperature pyrolysis slag. The circulating nitrogen dehydration mechanism 2 dehydrates the nitrogen after heat exchange with the wet sulfur concentrate. The heat recovery mechanism 3 uses the heat recovered in the high-temperature pyrolysis slag in the tertiary stage to heat the nitrogen. The heated nitrogen is used for pre-drying of the wet sulfur concentrate, thereby improving the heat exchange efficiency and heat recovery efficiency of the system.

[0029] The sulfur concentrate drying mechanism 1 includes a predryer 11 for drying the input wet sulfur concentrate by mixing with hot nitrogen, a first bag filter 12 connected to the predryer for separating the dried sulfur concentrate from the nitrogen, a first venturi 13 connected to the first bag filter for receiving the sulfur concentrate separated by the first bag filter and mixing with hot nitrogen for preheating, and a first cyclone separator 14 connected to the first venturi for separating the preheated sulfur concentrate from the nitrogen. The wet sulfur concentrate is transported to the vertical tube predryer 11 by a screw conveyor 18. After the wet sulfur concentrate is dried by hot nitrogen in the predryer 11, the moisture content of the sulfur concentrate is reduced to less than 1%; the dried sulfur concentrate is separated in the first bag filter 12 and preheated by nitrogen; the preheated sulfur concentrate is separated in the first cyclone separator 14 and then enters the subsequent sulfur concentrate pyrolysis system.

[0030] The circulating nitrogen dehydration mechanism 2 includes a dehydration tower 21 for receiving a part of the nitrogen separated from the first bag filter 12 for dehydration, and a first induced draft fan 22 connected to the dehydration tower for outputting the other part of the nitrogen separated from the first bag filter and the nitrogen dehydrated in the dehydration tower. The dried sulfur concentrate and the wet nitrogen after heat exchange are separated in the first bag filter 3. The wet nitrogen is divided into two parts, one part enters the dehydration tower 21 and is dehydrated by the dehydration tower 21, and the other part is directly drawn out and mixed with the dehydrated nitrogen to ensure the stability of the nitrogen moisture content in the system. The mixed nitrogen is drawn out through the first induced draft fan 22 and transported to the heat recovery mechanism 3. Part of the water removed from the dehydration tower 21 is drained by the circulation pump 23, and part returns to the dehydration tower 21 after heat exchange by the heat exchanger 24.

[0031] The heat recovery mechanism 3 includes a second venturi 38 for receiving the nitrogen and high-temperature pyrolysis slag separated by the first cyclone separator, a second cyclone separator 39 connected to the second venturi 38 for separating the mixed hot nitrogen and pyrolysis slag, a third venturi 31 connected to the second cyclone separator 39 and the fourth cyclone separator 34 for mixing the nitrogen and the pyrolysis slag for the first stage of heat recovery, and a third cyclone separator 32 connected to the third venturi 31 for separating the pyrolysis slag from the nitrogen. At the same time, a fourth venturi 33 is connected to the second bag separator 36 and the fourth cyclone separator 34 for mixing nitrogen with the pyrolysis slag for second-stage heat recovery, a fourth cyclone separator 34 is connected to the fourth venturi 33 for separating the pyrolysis slag from nitrogen, a fifth venturi 35 is connected to the first induced draft fan 22 for mixing the dehydrated mixed nitrogen with the pyrolysis slag for third-stage heat recovery, and a second bag separator is connected to the fifth venturi 35 for separating the pyrolysis slag from nitrogen to obtain a pyrolysis slag product. The third cyclone separator 32 is connected to the feed port of the fourth venturi 33, and the gas outlet of the third cyclone separator 32 is connected to the pre-dryer 11; thus, the nitrogen separated in the first cyclone separator 14 passes through the second venturi 38, and the hot nitrogen formed after mixing with the high-temperature pyrolysis slag is separated by the second cyclone separator, and then enters the first venturi 13 for recycling; the cold nitrogen after dehydration, drying and mixing passes through the fifth venturi 35, the second bag separator 36 in turn. , the fourth venturi 33, the fourth cyclone separator 34, the third venturi 31 and the third cyclone separator 32. After the three-stage heat exchange, the temperature rises to 300-400°C and enters the pre-drying mechanism to pre-dry the wet sulfur concentrate; and the high-temperature pyrolysis slag passes through the second venturi 38, the second cyclone separator 39, the third cyclone separator 32, the fourth venturi 33, the fourth cyclone separator 34, the fifth venturi 35 and the second bag separator 36, and finally forms the pyrolysis slag product output after cooling. It is worth noting that the venturi and the separator constitute the first stage of heat recovery, the third venturi 31 and the third cyclone separator 32 constitute the first stage of heat recovery, the fourth venturi 33 and the fourth cyclone separator 34 constitute the second stage of heat recovery, and the fifth venturi 35 and the second bag separator 36 constitute the third stage of heat recovery.

[0032] The second venturi 38, the second cyclone separator 39, the first venturi 13, the first cyclone separator 14 and the second induced draft fan 15 for inputting high-temperature pyrolysis slag form a small nitrogen circulation mechanism 100. The nitrogen is first heated by heat exchange with the high-temperature pyrolysis slag in the second venturi 38. The heated nitrogen and the pyrolysis slag after preliminary cooling are separated in the second cyclone separator 39 and enter the first venturi 13. The heated nitrogen preheats the dry sulfur concentrate in the first venturi, so that the high-temperature pyrolysis slag is preliminarily cooled and the sulfur concentrate is preliminarily preheated; and the cooled nitrogen and the preheated sulfur concentrate can be recycled again after being separated in the first cyclone separator 14. The second induced draft fan 15 pressurizes the circulating nitrogen to maintain the system balance. In addition, the system is provided with a nitrogen replenishment pipe port and a fixed discharge pipe port to facilitate the replenishment of nitrogen and maintain the system balance.

[0033] The circulating nitrogen dehydration mechanism 2, the fifth venturi 35, the second bag filter 36, the third induced draft fan 37, the fourth venturi 33, the fourth cyclone separator 34, the third venturi 31, the third cyclone separator 32, the pre-dryer 11 and the first bag separator 12 constitute a nitrogen large circulation mechanism 200. The third induced draft fan 37 pressurizes the circulating nitrogen to maintain the system balance.

[0034] The high-temperature pyrolysis slag is cooled to 80-120°C by multi-stage heat exchange, first passes through the second Venturi 38 and the second cyclone separator 39 in the nitrogen small circulation mechanism for primary heat exchange, and then passes through the third Venturi 31, the third cyclone separator 32, the fourth Venturi 33, the fourth cyclone separator 34, the fifth Venturi 35, and the second bag filter 36 in the nitrogen large circulation mechanism in sequence, and the cooled pyrolysis slag is output as a product.

[0035] The whole system adopts a nitrogen double circulation mode; the large nitrogen circulation is to pre-dry the wet sulfur concentrate by circulating hot nitrogen, and to perform three-stage heat recovery on the high-temperature pyrolysis slag (pyrrhotite), so that the high-temperature pyrolysis slag is cooled and output as a product, and the circulating nitrogen is heated at the same time, and the heated nitrogen is used in the pre-drying process; the small nitrogen circulation is that the nitrogen first exchanges heat with the high-temperature pyrolysis slag to increase the temperature, and then exchanges heat with the sulfur concentrate to cool it down, so that the high-temperature pyrolysis slag is initially cooled and the sulfur concentrate is initially preheated. The whole system is heat-exchanged by the nitrogen double circulation system, which improves the heat exchange efficiency and heat recovery efficiency of the system. At the same time, the closed circulation of nitrogen reduces the nitrogen consumption, improves the safety of the system, and reduces production costs.

[0036] The present invention also provides a method for drying sulfur concentrate and recovering heat with nitrogen circulation, comprising the following steps:

[0037] 1) Hot nitrogen is input into the pre-dryer 11 to dry the wet sulfur concentrate, so that the moisture content of the sulfur concentrate is reduced to less than 1%;

[0038] 2) The dried sulfur concentrate and the water-containing nitrogen in step 1) are separated in the first bag filter 12, the separated sulfur concentrate enters the first venturi 13 and is mixed with hot nitrogen for preheating, and the preheated sulfur concentrate enters the first cyclone separator 14 for separation to obtain preheated sulfur concentrate and cold nitrogen;

[0039] 3) The cold nitrogen obtained in step 2) enters the second venturi 38 with high-temperature pyrolysis slag for heat exchange to form hot nitrogen and preliminarily cool the pyrolysis slag. The hot nitrogen and the preliminarily cooled pyrolysis slag enter the second cyclone separator 39 for separation. The separated hot nitrogen is input into the first venturi 13 in step 2), and the preliminarily cooled pyrolysis slag enters the third venturi 31;

[0040] 4) A portion of the nitrogen containing water in step 2) enters the dehydration tower 21 for drying, and the dried nitrogen is mixed with another portion of the nitrogen containing water to form dehydrated mixed cold nitrogen and enters the fifth venturi 35;

[0041] 5) In step 3), the second heated nitrogen is input into the third venturi 31 to complete the first stage heat recovery, the pyrolysis slag is preliminarily cooled to heat the second heated nitrogen for the third time, and the cooled pyrolysis slag and the heated nitrogen enter the third cyclone separator 32 to separate into the first stage cooled pyrolysis slag and the third heated nitrogen;

[0042] 6) The third heating nitrogen obtained in step 5) is input into the pre-dryer 11 in step 1); the first stage cooling pyrolysis slag enters the fourth venturi 33;

[0043] 7) In step 6), the first heated nitrogen is input into the fourth venturi 33 to complete the second stage heat recovery, the first stage cooling pyrolysis slag heats the first heated nitrogen, and the cooled pyrolysis slag and heated nitrogen enter the fourth cyclone separator 34 to separate into the second stage cooling pyrolysis slag and the second heated nitrogen;

[0044] 8) The second heating nitrogen obtained in step 7) is input into the third venturi 31 in step 5); the second stage cooling pyrolysis slag is input into the fifth venturi 35 in step 4);

[0045] 9) In step 8), the second-stage pyrolysis slag in the fifth venturi 35 completes the third-stage heat recovery of the dehydrated mixed cold nitrogen, the second-stage cooled pyrolysis slag heats the dehydrated mixed cold nitrogen, the cooled pyrolysis slag and the heated nitrogen enter the second bag separator 36 to separate into a cooled pyrolysis slag product and the first heated nitrogen, and the first heated nitrogen is input into the fourth venturi 33 of step 7).

[0046] Part of the water removed from the dehydration tower 21 in step 4) is drawn out by the circulation pump 23, and the other part returns to the dehydration tower 21 after heat exchange in the heat exchanger 24. The nitrogen separated by the first cyclone separator 14 in step 2) is input into the second venturi 38 by the second induced draft fan 15; the nitrogen separated by the second bag separator 36 in step 9) is input into the fourth venturi 33 by the third induced draft fan 37.

[0047] In summary, the technical solution of the present invention can fully and effectively achieve the above-mentioned invention purpose, and the structure and functional principle of the present invention have been fully verified in the embodiments, and can achieve the expected effect and purpose. Without departing from the principle and essence of the present invention, various changes or modifications can be made to the embodiments of the invention. Therefore, the present invention includes all replacement contents within the scope mentioned in the scope of the patent application, and any equivalent changes made within the scope of the patent application of the present invention are within the scope of the patent application of this case.

Claims

1. A sulfur concentrate drying and heat recovery system with nitrogen circulation, characterized in that: The invention comprises a sulfur concentrate drying mechanism, a circulating nitrogen dehydration mechanism and a heat recovery mechanism. The sulfur concentrate drying mechanism comprises a predryer for inputting hot nitrogen to dry the wet sulfur concentrate, a first bag filter connected to the predryer for separating the dried sulfur concentrate from the nitrogen, a first venturi connected to the first bag filter for receiving the sulfur concentrate separated by the first bag filter and mixing with the hot nitrogen for preheating, and a first cyclone separator connected to the first venturi for separating the preheated sulfur concentrate and the nitrogen; the circulating nitrogen dehydration mechanism comprises a dehydration tower for receiving a part of the nitrogen separated from the first bag filter for dehydration, and a first induced draft fan connected to the dehydration tower for outputting another part of the nitrogen separated from the first bag filter and the dehydrated nitrogen in the dehydration tower; the heat recovery mechanism comprises a second venturi for receiving the nitrogen separated by the first cyclone separator and the high-temperature pyrolysis slag, a second cyclone separator connected to the second venturi for separating the mixed hot nitrogen and the pyrolysis slag, and a second cyclone separator connected to the second venturi for separating the mixed hot nitrogen and the pyrolysis slag. The separator and the fourth cyclone separator are connected to the third venturi for mixing nitrogen with the pyrolysis slag for the first stage heat recovery, the third cyclone separator connected to the third venturi for separating the pyrolysis slag from the nitrogen, and the fourth venturi connected to the second bag separator and the fourth cyclone separator for mixing nitrogen with the pyrolysis slag for the second stage heat recovery, the fourth cyclone separator connected to the fourth venturi for separating the pyrolysis slag from the nitrogen, and the first induced draft fan for mixing the dehydrated mixed nitrogen and the pyrolysis slag. A fifth venturi for mixing and performing third-stage heat recovery, a second bag separator connected to the fifth venturi for separating pyrolysis slag from nitrogen to obtain a pyrolysis slag product, a discharge port of the third cyclone separator connected to a feed port of the fourth venturi, an air outlet of the third cyclone separator connected to a pre-dryer, a discharge port of the second cyclone separator connected to a feed port of the third venturi, an air outlet of the second cyclone separator connected to the first venturi, and a discharge port of the fourth cyclone separator connected to a feed port of the fifth venturi.

2. The sulfur concentrate drying and heat recovery system with nitrogen circulation according to claim 1 is characterized in that: Part of the water removed from the dehydration tower is led out by a circulation pump, and part of it returns to the dehydration tower after heat exchange in a heat exchanger.

3. The sulfur concentrate drying and heat recovery system with nitrogen circulation according to claim 1 is characterized in that: A second induced draft fan is arranged between the first cyclone separator and the second venturi; and a third induced draft fan is arranged between the second bag filter and the fourth venturi.

4. The sulfur concentrate drying and heat recovery system with nitrogen circulation according to claim 1 is characterized in that: The pre-dryer is connected to a screw conveyor for conveying wet sulfur concentrate.

5. The sulfur concentrate drying and heat recovery system with nitrogen circulation according to claim 3 is characterized in that: The second venturi for inputting high-temperature pyrolysis slag, the second cyclone separator, the first venturi, the first cyclone separator and the second induced draft fan form a small nitrogen circulation mechanism.

6. The sulfur concentrate drying and heat recovery system with nitrogen circulation according to claim 3 is characterized in that: The circulating nitrogen dehydration mechanism, the fifth venturi, the second bag filter, the third induced draft fan, the fourth venturi, the fourth cyclone separator, the third venturi, the third cyclone separator, the predryer and the first bag separator constitute a large nitrogen circulation mechanism.

7. The sulfur concentrate drying and heat recovery system with nitrogen circulation according to claim 1 is characterized in that: The system is also provided with a nitrogen supplement pipe opening and a fixed discharge pipe opening.

8. A drying and heat recovery method for sulfur concentrate drying and heat recovery system with nitrogen circulation as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Hot nitrogen is input into the pre-dryer to dry the wet sulfur concentrate to reduce the moisture content of the sulfur concentrate to less than 1%; 2) The dried sulfur concentrate and the water-containing nitrogen in step 1) are separated in the first bag filter, the separated sulfur concentrate enters the first venturi and is mixed with the hot nitrogen for preheating, and the preheated sulfur concentrate enters the first cyclone separator for separation to obtain the preheated sulfur concentrate and cold nitrogen; 3) The cold nitrogen obtained in step 2) enters the second venturi with high-temperature pyrolysis slag for heat exchange to form hot nitrogen and preliminarily cool the pyrolysis slag, the hot nitrogen and the preliminarily cooled pyrolysis slag enter the second cyclone separator for separation, the separated hot nitrogen is input into the first venturi in step 2), and the preliminarily cooled pyrolysis slag enters the third venturi; 4) A portion of the nitrogen containing water in step 2) enters the dehydration tower for drying, and the dried nitrogen is mixed with another portion of the nitrogen containing water to form dehydrated mixed cold nitrogen and enter the fifth venturi; 5) In step 3), the second heated nitrogen is input into the third venturi to complete the first stage heat recovery, the pyrolysis slag is preliminarily cooled to heat the second heated nitrogen for the third time, and the cooled pyrolysis slag and the heated nitrogen enter the third cyclone separator to separate into the first stage cooled pyrolysis slag and the third heated nitrogen; 6) The third heating nitrogen obtained in step 5) is input into the pre-dryer in step 1); the first stage cooling pyrolysis slag enters the fourth venturi; 7) The first heated nitrogen is input into the fourth venturi in step 6) to complete the second stage heat recovery, the first stage cooling pyrolysis slag heats the first heated nitrogen, and the cooled pyrolysis slag and heated nitrogen enter the fourth cyclone separator to separate into the second stage cooling pyrolysis slag and the second heated nitrogen; 8) The second heating nitrogen obtained in step 7) is input into the third venturi in step 5); the second stage cooling pyrolysis slag is input into the fifth venturi in step 4); 9) In step 8), the second-stage pyrolysis slag in the fifth venturi completes the third-stage heat recovery of the dehydrated mixed cold nitrogen, the second-stage cooled pyrolysis slag heats the dehydrated mixed cold nitrogen, the cooled pyrolysis slag and the heated nitrogen enter the second bag separator to separate the cooled pyrolysis slag product and the first heated nitrogen, and the first heated nitrogen is input into the fourth venturi of step 7).

9. The drying and heat recovery method according to claim 8, characterized in that: Part of the water removed from the dehydration tower in step 4) is drawn out by a circulation pump, and the other part returns to the dehydration tower after heat exchange in a heat exchanger.

10. The drying and heat recovery method according to claim 8, characterized in that: The nitrogen separated by the first cyclone separator in step 2) is input into the second venturi by the second induced draft fan; the first heated nitrogen separated by the second bag separator in step 9) is input into the fourth venturi by the third induced draft fan.

Images