A heat carrier circulating pyrite concentrate pyrolysis upgrading system

Abstract

The application relates to a heat carrier circulating pyrite concentrate pyrolysis upgrading system, and aims at the problems existing in the prior pyrite concentrate pyrolysis process. The pyrite concentrate is directly contacted and heated by solid heat carriers (pyrolysis residues), the desulfurization efficiency is improved, and heat loss is reduced; circulating hot nitrogen gas is used in the system to heat and convey the materials, the purity and recovery rate of subsequent obtained pyrrhotite are ensured, and the safety of the pyrolysis process is ensured.

Description

Technical Field

[0001] This invention relates to a pyrolysis upgrading system for sulfur concentrate, specifically a desulfurization method in a sulfur concentrate system using pyrolysis products as a solid heat carrier. Background Technology

[0002] my country has long relied on imports for sulfur, with a severe shortage of domestic supply. A large amount of sulfur resources, such as sulfur concentrate, are used to produce sulfuric acid. However, sulfuric acid production is limited by transportation costs and storage conditions, resulting in a waste of sulfur resources. But pyrolysis of sulfur concentrate can yield pyrolysis slag and sulfur vapor, which can then be used to produce pyrrhotite and sulfur, thus improving the utilization rate of sulfur concentrate.

[0003] The existing pyrolysis method for sulfur concentrate (CN215668138) mainly uses a pyrolysis rotary kiln to first pyrolyze the sulfur concentrate into pyrolysis slag and sulfur vapor, and then uses a cooling rotary kiln to cool the pyrolysis slag. In this case, the pyrolysis rotary kiln uses indirect contact heating, resulting in low heat utilization and uneven material heating. Furthermore, because the generated sulfur easily corrodes metal equipment, non-metallic castable refractory needs to be added to the inner wall of the equipment. Conventional pyrolysis rotary kilns use external heating, but the low thermal conductivity of the castable refractory makes it difficult for heat to be conducted to the inside of the equipment for pyrolysis, resulting in significant heat waste. In addition, the pyrolysis slag is directly cooled in the cooling rotary kiln, and its heat cannot be recovered and reused, resulting in low heat utilization. Therefore, developing a sulfur concentrate pyrolysis process with high heat utilization and system safety is of great significance for improving the utilization rate of sulfur concentrate. Summary of the Invention

[0004] In view of the problems existing in the pyrolysis process of sulfur concentrate, the purpose of this invention is to propose a sulfur concentrate pyrolysis upgrading system with heat carrier circulation.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A pyrolysis and upgrading system for sulfur concentrate with circulating heat carrier, the system comprising a first mixer for mixing high-temperature nitrogen and sulfur concentrate for initial preheating, the first mixer being connected to a dust collector for circulating nitrogen and the preheated sulfur concentrate, a second mixer for mixing sulfur concentrate and circulating nitrogen for secondary heating being connected to the bottom of the dust collector, a first gas-solid separator for separating circulating nitrogen and sulfur concentrate being connected to the tail end of the second mixer, the top of the first gas-solid separator being connected to the first mixer, and a second material storage bin for holding sulfur concentrate being connected to the bottom of the first gas-solid separator.

[0007] The system also includes a converter connected to a degassing device for separating pyrolysis slag and sulfur vapor. The degassing device is equipped with a sulfur vapor outlet for discharging sulfur vapor out of the system, a second pyrolysis slag outlet for discharging part of the pyrolysis slag out of the system, and a first pyrolysis slag outlet for returning part of the pyrolysis slag to the system as a heat source. The first pyrolysis slag outlet is connected to a pneumatic conveying pipe. The first end of the pneumatic conveying pipe is connected to a high-temperature nitrogen input pipe, and the last end of the pneumatic conveying pipe is connected to a second gas-solid separator for separating the heated high-temperature pyrolysis slag from the nitrogen. The top of the second gas-solid separator is connected to a second mixer, and the second gas-solid separator is connected to a first material sealing bin for storing the high-temperature pyrolysis slag.

[0008] The dust collector is connected to a heater at the top via an induced draft fan, and the heater is connected to a high-temperature nitrogen input pipe at the beginning of the pneumatic conveying pipe 1.

[0009] The first and second material sealing chambers are connected to converter 5 for pyrolysis of sulfur concentrate.

[0010] Furthermore, the first mixer and the second mixer are Venturi mixers.

[0011] Furthermore, the first outlet and the second outlet of the pyrolysis slag are connected to a disc feeder, which controls the feeding via gravity interlock.

[0012] Furthermore, the second gas-solid separator and the first gas-solid separator are cyclone separators.

[0013] Furthermore, the first and second material sealing chambers are controlled by gravity interlocking for material feeding.

[0014] Furthermore, the first material sealing chamber and the second material sealing chamber are provided with material sealing layers.

[0015] Furthermore, the converter is fed using a screw conveyor.

[0016] Furthermore, the converter is equipped with baffles inside.

[0017] This invention also provides a method for upgrading sulfur concentrate by pyrolysis using a heat carrier circulation method, characterized in that the method includes the following steps:

[0018] (1) The dry sulfur concentrate enters the system through the first mixer. In the first mixer, the sulfur concentrate and the hotter circulating nitrogen from the first gas-solid separator are fully mixed to preheat the sulfur concentrate for the first time.

[0019] (2) After the first preheating is completed, the material enters the dust collector. After passing through the dust collector, the clean nitrogen enters the heater under the action of the induced draft fan 13 and is heated to about 900°C. The sulfur concentrate then enters the second mixer.

[0020] (3) In the second mixer, the sulfur concentrate and the circulating nitrogen from the second gas-solid separator are thoroughly mixed to heat the sulfur concentrate for the second time;

[0021] (4) After heating is completed, the material enters the first gas-solid separator. After passing through the separator, nitrogen is discharged upwards into the first mixer as the heat source for the first preheating, while sulfur concentrate is discharged downwards into the second material storage tank.

[0022] (5) The hot nitrogen gas heated by the heater enters the pneumatic conveying pipe and is fully mixed with the pyrolysis residue discharged from the first outlet of the degassing device, and the pyrolysis residue is further heated;

[0023] (6) The pneumatic conveying pipe sends the material and circulating nitrogen into the second gas-solid separator. After passing through the separator, the circulating nitrogen is discharged into the second mixer as the heat source for the second heating of the sulfur concentrate. The high-temperature pyrolysis residue is discharged downwards into the first material sealing chamber.

[0024] (7) The high-temperature pyrolysis residue from the first material storage bin and the sulfur concentrate from the second material storage bin are mixed and then fed into the converter. The high-temperature pyrolysis residue serves as a heat source and comes into direct contact with the sulfur concentrate, causing the sulfur concentrate to pyrolyze.

[0025] (8) After pyrolysis, the pyrolysis gas of the pyrolysis residue enters the degassing device for degassing. After degassing, the steam is discharged from the system. The steam contains a large amount of sulfur, mainly sulfur vapor. The pyrolysis residue is divided into two parts according to the needs of the system. One part is discharged from the system through the second outlet of the pyrolysis residue and is used for heat recovery. The other part of the pyrolysis residue enters the pneumatic conveying pipe through the first outlet of the pyrolysis residue and is used as a heat source for further heating.

[0026] The beneficial effects of the present invention are as follows: (1) The solid heat carrier (pyrolysis slag) is used to directly heat the sulfur concentrate, thereby improving the desulfurization efficiency and reducing heat loss; (2) The circulating hot nitrogen gas is used in the system to heat and transport the materials, ensuring the inert environment of the system, preventing the pyrolysis slag from being oxidized by air, ensuring the purity and recovery rate of the pyrrhotite obtained later, and also ensuring the safety of the pyrolysis process; (3) The high-temperature pyrolysis slag and the sulfur concentrate are collected by the material sealing bin before being discharged, isolating nitrogen gas and water vapor that may be generated during the pyrolysis process, thereby improving the purity of sulfur vapor during the pyrolysis process and improving the sulfur recovery rate; (4) The material sealing bin and the disc feeder control the discharge ratio by gravity, control the mixing ratio of high and low temperature materials and the circulation volume of the solid heat carrier, thereby ensuring the pyrolysis effect of the sulfur concentrate. Attached Figure Description

[0027] Figure 1 This is a simplified schematic diagram of the present invention. Detailed Implementation

[0028] The present invention will be further explained and described below with reference to the accompanying drawings.

[0029] A pyrolysis and upgrading system for sulfur concentrate with a circulating heat carrier, the system comprising a first mixer 12 for mixing high-temperature nitrogen gas and sulfur concentrate, the first mixer 12 having a first high-temperature nitrogen gas inlet at its head and a first mixture outlet at its tail, the first mixer 12 also having a sulfur concentrate inlet, through which the sulfur concentrate enters the system. The sulfur concentrate entering the system is mixed with high-temperature nitrogen for the first preheating. The outlet of the first mixture is connected to a dust collector 9 for separating the cooled circulating nitrogen and the preheated sulfur concentrate. The bottom of the dust collector 9 is connected to a second mixer 8 for exchanging heat between the sulfur concentrate and the high-temperature nitrogen to reheat the sulfur concentrate. The tail end of the second mixer 8 is connected to a first gas-solid separator 11 for separating the heat-exchanged circulating nitrogen and the sulfur concentrate. The top of the first gas-solid separator 11 is connected to the first mixer 12. The hotter circulating nitrogen enters the first mixer 12 from the top and mixes with the sulfur concentrate, making full use of the remaining heat of the circulating nitrogen to preheat the sulfur concentrate that has just entered the system. The bottom of the first gas-solid separator 11 is connected to a second material sealing chamber 10, and the reheated sulfur concentrate enters the second material sealing chamber 10.

[0030] The system also includes a converter 5, which is connected to a degassing device 2 for separating pyrolysis slag and sulfur vapor. The degassing device 2 is provided with a sulfur vapor outlet for discharging sulfur vapor out of the system, a first pyrolysis slag outlet 3 for returning part of the pyrolysis slag to the system for circulation, and a second pyrolysis slag outlet 4 for discharging part of the pyrolysis slag out of the system. The pyrolysis slag returning part of the pyrolysis slag to the system for circulation serves as a solid heat carrier. The first pyrolysis slag outlet 3 is connected to a pneumatic conveying pipe 1. The first end of the pneumatic conveying pipe 1 is connected to a high-temperature nitrogen input pipe. The pyrolysis slag input through the first pyrolysis slag outlet 3 and the high-temperature nitrogen input through the high-temperature nitrogen input pipe converge in the pneumatic conveying pipe 1. The pyrolysis slag is heated to become high-temperature pyrolysis slag. The tail end of the pneumatic conveying pipe 1 is connected to a second gas-solid separator 7 for separating the heated high-temperature pyrolysis slag from the nitrogen. The second gas-solid separator 7 is provided with a first gas outlet 71 at the top and a first solid outlet 72 at the bottom. The first solid outlet 72 is connected to a first material sealing bin 6 for storing high-temperature pyrolysis slag.

[0031] The dust collector 9 is connected to a heater 14 via an induced draft fan 13 at its top. The heater 14 is connected to a high-temperature nitrogen input pipe at the beginning of the pneumatic conveying pipe 1. The circulating nitrogen separated by the dust collector 9 is discharged from the top of the dust collector 9 and heated to about 900°C by the heater 14. Then it enters the pneumatic conveying pipe 1 and is transported together with the pyrolysis slag input through the first outlet 3 of the pyrolysis slag to the second gas-solid separator 7 via the pneumatic conveying pipe 1.

[0032] Both the first material sealing bin 6 and the second material sealing bin 10 are connected to the converter 5 for pyrolyzing sulfur concentrate. The high-temperature pyrolysis slag from the first material sealing bin 6 and the secondary heated sulfur concentrate from the second material sealing bin 10 are mixed in the converter 5. The sulfur concentrate is pyrolyzed at high temperature. The high-temperature pyrolysis slag, as a solid heat carrier, is fully mixed with the sulfur concentrate in the converter 5, achieving direct contact heating of the sulfur concentrate, improving desulfurization efficiency, and reducing heat loss. Before mixing, the high-temperature pyrolysis slag and sulfur concentrate are collected in the material sealing bins and then fed in, isolating nitrogen and water vapor that may be generated during pyrolysis, improving the purity of sulfur vapor during pyrolysis, and increasing sulfur recovery rate.

[0033] In this system, nitrogen is continuously heated and circulated throughout the system, and exchanges heat with the sulfur concentrate to be pyrolyzed or the pyrolysis slag that serves as a heat carrier to heat the sulfur concentrate or pyrolysis slag, thereby achieving the pyrolysis of the sulfur concentrate and obtaining sulfur vapor.

[0034] Preferably, the first mixer 12 and the second mixer 8 are Venturi mixers, and the Venturi mixers may also be tee pipes or other pneumatic conveying equipment.

[0035] Preferably, the first outlet 3 and the second outlet 4 of the pyrolysis slag are connected to a disc feeder. The disc feeder controls the material feeding through gravity interlocking, thereby controlling the circulation rate of the solid heat carrier.

[0036] Preferably, all of the second gas-solid separators 7 and the first gas-solid separators 11 are cyclone separators.

[0037] Preferably, all the first material sealing bins 6 and the second material sealing bins 10 are controlled by gravity interlocking to control the mixing ratio of high and low temperature materials in the converter, thereby ensuring the pyrolysis effect of sulfur concentrate.

[0038] All the first material sealing chambers 6 and the second material sealing chambers 10 maintain a certain material sealing layer during system operation, which isolates circulating nitrogen and water vapor that may be generated during pyrolysis, improves the purity of sulfur vapor during pyrolysis, and improves sulfur recovery rate.

[0039] The converter 5 uses a screw conveyor for feeding and is equipped with baffles inside the converter to improve the heat exchange effect between the sulfur concentrate and the pyrolysis slag.

[0040] To maintain the smooth operation of the entire system, the system is also equipped with a nitrogen replenishment port and a nitrogen discharge port.

[0041] A method for upgrading sulfur concentrate by pyrolysis using a heat carrier circulation method, the method comprising the following steps:

[0042] (1) The dry sulfur concentrate enters the system through the first mixer 12. In the first mixer 12, the sulfur concentrate and the hotter circulating nitrogen from the first gas-solid separator 11 are fully mixed to preheat the sulfur concentrate to 400-500℃.

[0043] (2) After the first preheating is completed, the material enters the dust collector 9. After passing through the dust collector 9, the clean nitrogen enters the heater 14 under the action of the induced draft fan 13 and is heated to about 900°C. The sulfur concentrate then enters the second mixer 8.

[0044] (3) In the second mixer 8, the sulfur concentrate and the circulating nitrogen from the second gas-solid separator 7 are fully mixed, and the sulfur concentrate is heated for the second time to 600-720°C;

[0045] (4) After heating is completed, the material enters the first gas-solid separator 11. After passing through the separator, nitrogen is discharged upward into the first mixer 12 as the heat source for the first preheating, while the sulfur concentrate is discharged downward into the second material sealing chamber 10.

[0046] (5) The hot nitrogen gas heated by heater 14 enters the pneumatic conveying pipe 1 and is fully mixed with the pyrolysis residue discharged from the first outlet 3 of the pyrolysis residue of the degassing device. The pyrolysis residue is further heated to 700-800℃.

[0047] (6) The pneumatic conveying pipe 1 sends the material into the second gas-solid separator 7. After passing through the separator, the circulating nitrogen is discharged into the second mixer 8 as the heat source for the second heating of the sulfur concentrate; the high-temperature pyrolysis residue is discharged downward into the first material sealing silo 6.

[0048] (7) The high-temperature pyrolysis slag from the first material sealing chamber 6 and the sulfur concentrate from the second material sealing chamber 10 are mixed and then fed into the converter 5. The high-temperature pyrolysis slag is used as a heat source and comes into direct contact with the sulfur concentrate, and the sulfur concentrate is pyrolyzed. Generally speaking, after the amount of sulfur concentrate is determined, the amount of high-temperature pyrolysis slag required is determined by heat balance.

[0049] (8) After pyrolysis, the pyrolysis gas of the pyrolysis residue enters the degassing device 2 for degassing. After degassing, the steam is discharged from the system. The steam contains a large amount of sulfur, mainly sulfur vapor. The pyrolysis residue is divided into two parts according to the needs of the system. One part is discharged from the system through the second outlet 4 of the pyrolysis residue and is used for heat recovery. The other part of the pyrolysis residue enters the pneumatic conveying pipe 1 through the first outlet 3 of the pyrolysis residue and is used as a heat source for further heating.

Claims

1. A pyrolysis and upgrading system for sulfur concentrate with circulating heat carrier, characterized in that, The system includes a first mixer for mixing high-temperature nitrogen and sulfur concentrate for initial preheating, the first mixer being connected to a dust collector for separating circulating nitrogen and the preheated sulfur concentrate, a second mixer for mixing sulfur concentrate and circulating nitrogen for secondary heating being connected to the bottom of the dust collector, a first gas-solid separator for separating circulating nitrogen and sulfur concentrate being connected to the tail end of the second mixer, the top of the first gas-solid separator being connected to the first mixer, and a second material hopper for placing sulfur concentrate being connected to the bottom of the first gas-solid separator. The system also includes a converter connected to a degassing device for separating pyrolysis slag and sulfur vapor. The degassing device is equipped with a sulfur vapor outlet for discharging sulfur vapor out of the system, a second pyrolysis slag outlet for discharging part of the pyrolysis slag out of the system, and a first pyrolysis slag outlet for returning part of the pyrolysis slag to the system as a heat source. The first pyrolysis slag outlet is connected to a pneumatic conveying pipe. The first end of the pneumatic conveying pipe is connected to a high-temperature nitrogen input pipe, and the last end of the pneumatic conveying pipe is connected to a second gas-solid separator for separating the heated high-temperature pyrolysis slag from the nitrogen. The top of the second gas-solid separator is connected to a second mixer, and the second gas-solid separator is connected to a first material sealing bin for storing the high-temperature pyrolysis slag. The dust collector is connected to a heater at the top via an induced draft fan, and the heater is connected to a high-temperature nitrogen input pipe at the beginning of the pneumatic conveying pipe. The first and second feed silos are connected to a converter for pyrolyzing sulfur concentrate.

2. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, The first and second mixers are Venturi mixers.

3. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, The first and second outlets of the pyrolysis slag are connected to a disc feeder, which controls the feeding via gravity interlock.

4. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, All of the second gas-solid separators and the first gas-solid separator are cyclone separators.

5. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, All the first and second material sealing chambers are controlled by gravity interlocking for material feeding.

6. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, All the first and second material sealing chambers are equipped with material sealing layers.

7. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, The converter is fed by a screw conveyor.

8. The sulfur concentrate pyrolysis and upgrading system with heat carrier circulation as described in claim 1, characterized in that, The converter is equipped with baffles inside.

9. A pyrolysis upgrading method for a sulfur concentrate pyrolysis upgrading system with heat carrier circulation as described in any one of claims 1-8, characterized in that, The method includes the following steps: (1) The dry sulfur concentrate enters the system through the first mixer. In the first mixer, the sulfur concentrate and the hotter circulating nitrogen from the first gas-solid separator are fully mixed to preheat the sulfur concentrate for the first time. (2) After the first preheating is completed, the material enters the dust collector. After passing through the dust collector, the clean nitrogen enters the heater under the action of the induced draft fan and is heated to 900°C. The sulfur concentrate then enters the second mixer. (3) In the second mixer, the sulfur concentrate and the circulating nitrogen from the second gas-solid separator are thoroughly mixed to heat the sulfur concentrate for the second time; (4) After heating is completed, the material enters the first gas-solid separator. After passing through the separator, nitrogen is discharged upwards into the first mixer as the heat source for the first preheating, while sulfur concentrate is discharged downwards into the second material storage tank. (5) The hot nitrogen gas heated by the heater enters the pneumatic conveying pipe and is fully mixed with the pyrolysis residue discharged from the first outlet of the degassing device, and the pyrolysis residue is further heated; (6) The pneumatic conveying pipe sends the material into the second gas-solid separator. After passing through the separator, the circulating nitrogen is discharged into the second mixer as the heat source for the second heating of the sulfur concentrate. The high-temperature pyrolysis residue is discharged downwards into the first material sealing chamber. (7) The high-temperature pyrolysis residue from the first material storage bin and the sulfur concentrate from the second material storage bin are mixed and then fed into the converter. The high-temperature pyrolysis residue serves as a heat source and comes into direct contact with the sulfur concentrate, causing the sulfur concentrate to pyrolyze. (8) After pyrolysis, the pyrolysis gas of the pyrolysis residue enters the degassing device for degassing. After degassing, the steam is discharged from the system. The steam contains a large amount of sulfur, mainly sulfur vapor. The pyrolysis residue is divided into two parts according to the needs of the system. One part is discharged from the system through the second outlet of the pyrolysis residue and is used for heat recovery. The other part of the pyrolysis residue enters the pneumatic conveying pipe through the first outlet of the pyrolysis residue and is used as a heat source for further heating.

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