Device and method for treating salt-containing wastewater by downflowing and concurrent coal gasification heat recovery coordination

Abstract

The application discloses a device and method for treating salt-containing wastewater by down-flow and concurrent-flow coal gasification heat recovery coordination, which comprises a coal gasification furnace, a synthetic gas cooler, a cyclone separator, a material return, a particulate controller, a raw material burner, a salt-containing wastewater feeding device, a lined pipeline and the like. Oxygen is injected into the generated crude synthetic gas through an oxygen nozzle at the connection between the coal gasification furnace and the lined pipeline, so that the carbon-containing material in the crude synthetic gas is combusted with the oxygen, the crude synthetic gas is secondarily heated, and the molten fly ash is not directly contacted with the quenching water. Solid particles are used as heat transfer media, and the specific surface area of the solid particles is extremely large, so that the overall heat transfer coefficient is more than 5 times of that of a traditional radiant waste heat boiler. The recovery of the sensible heat of the crude synthetic gas can be used to treat the salt-containing wastewater and produce glass bodies. The cooling and purification process of the crude synthetic gas is completely realized by a dry process, and no water-containing fine slag is generated.

Description

Technical Field

[0001] This invention belongs to the technical field of syngas production and saline wastewater treatment, specifically relating to a device and method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery. Background Technology

[0002] Coal is the world's most abundant and widely distributed fossil fuel. Against the backdrop of high oil prices, coal's price advantage is becoming increasingly apparent. Furthermore, the world's recoverable coal reserves and mining lifespan are significantly greater than those of oil and natural gas, providing a favorable environment for the development of the coal chemical industry. The clean and efficient utilization of coal is a major technological challenge in the fields of energy and environmental protection today, and also one of the key technologies for the sustainable development of my country's national economy.

[0003] In recent years, many foreign companies have conducted research and development on combined cycle gasification power generation technology to improve the thermal efficiency of coal-fired power plants, thus promoting the development of coal gasification technology. In existing industrial plants, there are two common processes for recovering heat from high-temperature syngas: one is the waste heat boiler process, represented by Shell's dry pulverized coal gasifier, and the other is the quench process, represented by GE's (formerly Texaco) coal-water slurry gasifier. Shell's gasification process has disadvantages such as low efficiency in cooling syngas, increased equipment investment, high compressor power consumption, and the need for circulating dust removal of the syngas used for quenching. GE's coal-water slurry gasification process has two forms of syngas heat recovery: a gasifier using direct quenching or a gasifier equipped with a radiant cooler. In the direct quench gasifier, high-temperature syngas is sprayed with water in the quench chamber and quenched to 130–260°C, directly converting the sensible heat of the syngas into steam during the washing process. This method of converting high-temperature heat sources into low-grade, low-temperature heat energy is extremely unreasonable in terms of heat energy utilization, and the value of heat recovery is also low. Gasifiers equipped with radiant coolers employ either water-cooled wall structures or water-tube structures. High-temperature syngas first undergoes radiant heat exchange through the descending channel of the radiant cooler, reducing its temperature to the range of 250–600°C, before being quenched with water to remove slag. In this heat recovery method, molten ash easily adheres to the surface of the water-cooled walls or water tubes, which can severely reduce the heat transfer efficiency of the radiant cooler.

[0004] Chinese patent CN1900234A discloses a dry pulverized coal pressurized gasification quenching device and process. This involves arranging a set of sprayers at the outlet of the gasifier above the gasifier and controlling the supply of medium-pressure water via valves to reduce the outlet gas temperature from 1450-1600℃ to 900℃ for the first quench. The raw gas, after this first quench, enters the quench chamber for further quenching and washing. However, this patent involves directly spraying quench water from the top of the gasifier, which lowers the temperature inside the gasifier, reduces gasification conversion efficiency, and cannot guarantee uniform mixing of syngas and cooling water. Furthermore, the direct impact of syngas on the water spray pipes may cause ablation. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and to provide a device and method for coordinated treatment of saline wastewater by downflow parallel coal gasification heat recovery.

[0006] To achieve the above objectives, the present invention provides a downstream parallel-flow coal gasification heat recovery and coordinated treatment device for saline wastewater, comprising a coal gasifier, a syngas cooler, a cyclone separator, a particulate matter controller, and a lined pipe. The coal gasifier is divided from bottom to top into a slag-water zone, a constant-temperature zone, and a reaction zone. The syngas cooler is divided from bottom to top into a dense-phase zone, a transition zone, a heat exchange zone, and a separation zone. The particulate matter controller is divided from bottom to top into a cooling zone, a moving zone, and a desolidification zone. The reaction zone of the coal gasifier is equipped with a feed burner. The constant-temperature zone is connected to the dense-phase zone of the syngas cooler via a lined pipe, and an oxygen nozzle is provided at the connection between the constant-temperature zone and the lined pipe. The dense-phase zone of the syngas cooler is connected to a saline wastewater feed device, and the separation... The zone is connected to the upper part of the cyclone separator, and the bottom of the cyclone separator is connected to the transition zone of the syngas cooler through the material leg and the circulating sealed tank. The heat exchange zone of the syngas cooler is equipped with a heat exchange system, which is connected to the boiler feedwater system. The bottom outlet of the syngas cooler is connected to the glass collector through the No. 1 continuous cooling pressure reducing ash discharge device. The top of the cyclone separator is connected to the desolidification zone of the particulate matter controller. The desolidification zone of the particulate matter controller is equipped with a gas-solid separation unit, the moving zone is equipped with a fine powder level monitoring system, and the cooling zone is connected to the downstream ash silo through the No. 2 continuous cooling pressure reducing ash discharge device. The top of the particulate matter controller is connected to the crude syngas subsequent treatment system and the backflushing system.

[0007] Furthermore, a saline wastewater nozzle is provided at the connection between the dense phase zone of the aforementioned syngas cooler and the saline wastewater feed device.

[0008] Furthermore, the angle α between the aforementioned lining pipe and the horizontal plane is 10° to 45°.

[0009] The method for coordinating the treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery using the above-mentioned device includes the following steps:

[0010] a) Before starting work, a cooling water bath should be set up in the slag and water area of ​​the coal gasification furnace, and solid particles heated to 200-400°C should be filled into the material leg.

[0011] b) Use the feed burners in the reaction zone of the coal gasifier to inject preheated fuel and air and ignite them to raise the temperature of the reaction zone of the coal gasifier to 950°C, while ensuring that the temperature of the dense phase zone of the syngas cooler is above 300°C.

[0012] c) Replace the preheated fuel injected into the feedstock burner with gasification feedstock and gasifying agent, and adjust the ratio of gasification feedstock and gasifying agent to gradually increase and stabilize the temperature of the coal gasifier reaction zone to 1200-1600℃, so that the gasification feedstock and gasifying agent undergo gasification reaction in the reaction zone to generate crude syngas. The generated crude syngas carries molten fly ash and flows laterally into the lining pipe; at the same time, start the syngas cooler, heat exchange system and boiler feedwater system.

[0013] d) Start the oxygen nozzle at the connection between the constant temperature zone of the coal gasifier and the lining pipe, and inject oxygen into the crude syngas entering the lining pipe. The amount of oxygen injected is 1 to 5 vol% of the total crude syngas.

[0014] e) Gradually add solid particles from the feedstock into the syngas cooler until the solid particle content in the transition zone of the syngas cooler reaches 0.3 to 0.6 times the total volume of the syngas cooler; as the operating temperature of the separation zone of the syngas cooler reaches 200 to 500°C, the syngas cooler begins normal circulating fluidization; the water from the boiler feedwater system exchanges heat with the crude syngas in the heat exchange zone of the syngas cooler through the heat exchange system to generate steam, and the crude syngas after heat exchange enters the cyclone separator from the separation zone, and the generated steam is incorporated into the steam pipeline network;

[0015] f) Start the backflush system at the top of the particulate matter controller to perform regular backflush operations on the desolidification zone; at the same time, start the cooling water supply to the cooling zone and the fine powder level monitoring system in the moving zone; the coarse syngas, after further separation by the cyclone separator, enters the desolidification zone of the particulate matter controller, and after further separation in the gas-solid separation unit, it enters the coarse syngas post-processing system, and the resulting fine powder enters the moving zone of the particulate matter controller downwards.

[0016] g) Start the No. 2 continuous cooling pressure reduction and ash discharge device to cool and depressurize the fine powder in the moving area of ​​the particulate matter controller and discharge it to the downstream ash silo.

[0017] h) Start the saline wastewater feeding device and spray saline wastewater into the dense phase zone of the syngas cooler. At the same time, start the No. 1 continuous cooling pressure reduction and ash discharge device. The molten fly ash entrained in the crude syngas and the soluble salt solids in the saline wastewater are converted into glass in the dense phase zone and transition zone of the syngas cooler. The No. 1 continuous cooling pressure reduction and ash discharge device cools and depressurizes the glass before discharging it to the glass collector.

[0018] After completing the above steps, the entire device will enter the normal production process.

[0019] Furthermore, in step c) above, when the gasification feedstock is dry coal powder, the gasifying agent is oxygen and steam, and the crude syngas composition is: CH4 content of 0.01–0.1 vol%, H2 content of 5–15 vol%, CO content of 35–45 vol%, CO2 content of 3–10 vol%, and water content of 35–45 vol%. When the gasification feedstock is coal-water slurry, the gasifying agent is oxygen, and the crude syngas composition is: CH4 content of 0.01–0.1 vol%, H2 content of 15–25 vol%, CO content of 20–30 vol%, CO2 content of 10–15 vol%, and water content of 40–50 vol%.

[0020] Furthermore, in step d) above, the apparent velocity of the crude syngas in the lining pipe is 10–25 m / s.

[0021] Furthermore, in step e) above, the operating pressure of the syngas cooler after normal circulating fluidization is 1-8 MPaG, the operating temperature of the dense phase zone is 1250-1600℃, the operating temperature of the transition zone is 800-900℃, the operating temperature of the heat exchange zone is 200-800℃, and the operating temperature of the separation zone is 200-500℃.

[0022] Furthermore, the particle size of the solid particles is 50–200 μm, and in step e), the apparent velocity of the crude syngas participating in the circulating fluidization of the solid particles is 0.5–10 m / s.

[0023] Furthermore, in step e) above, the steam pressure generated by the boiler feedwater system via the heat exchange system is 0.5–10 MPaG, and the temperature is 150–540°C.

[0024] Furthermore, in step h) above, the salt content of the saline wastewater is mainly NaCl and Na2SO4, and its total dissolved solids content is 10,000 to 60,000 mg / L.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. In this invention, oxygen is injected into the crude syngas about to enter the lining pipe through an oxygen nozzle at the connection between the constant temperature zone of the coal gasifier and the lining pipe. This causes the carbon-containing materials in the crude syngas to undergo an oxidation reaction with the oxygen, releasing heat and reheating the crude syngas. The heated crude syngas carries molten fly ash and flows laterally into the lining pipe, so that the molten fly ash no longer comes into direct contact with the quench water. This keeps the viscosity of the molten fly ash at 20 Pa·s, which has good fluidity.

[0027] 2. This invention uses solid particles as a heat transfer medium, so that the high-temperature crude syngas and solid particles are completely mixed in the dense phase zone and transition zone of the syngas cooler. The heat of the crude syngas is first transferred to the solid particles, and then the solid particles directly contact the heat exchange system in the heat exchange zone. The solid particles have a very large specific surface area, so the overall heat transfer coefficient is more than 5 times that of the traditional radiant waste boiler.

[0028] 3. This invention utilizes a syngas cooler to cool and recover heat from the high-temperature crude syngas from the coal gasification furnace. It solidifies the molten fly ash entrained in the high-temperature crude syngas and the soluble salts from the saline wastewater feeder into a glassy substance. During the temperature drop from above 1250℃ to below 900℃, this glassy substance undergoes granulation in the dense phase and transition zones, using solid particles from the syngas cooler as auxiliary materials. This achieves the simultaneous treatment of saline wastewater and the generation of sodalite-like material (Na4Al3Si3O4) while recovering the sensible heat of the crude syngas. 12 The glassy form of products such as Cl), calcium chlorosilicate (Ca7(SiO4)2Cl6), and lapis lazuli (Na6Ca2(AlSiO4)6(SO4)4) was obtained, which enabled the co-treatment of saline wastewater and the generation of glassy form during the recovery of the sensible heat of crude syngas.

[0029] 4. The cooling and purification process of the crude syngas in this invention adopts a completely dry process, thereby avoiding the method of water washing and solidification of the crude syngas. Instead, the particulate matter in the crude syngas is removed by gas-solid separation, and no water-containing fine residue is generated in this process. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the device of the present invention.

[0031] In the diagram: 1-Coal gasification furnace, 2-Synthesis gas cooler, 3-Cyclone separator, 4-Material return, 5-Circulating sealed tank, 6-Particulate matter controller, 7-No. 1 continuous pressure reducing cooling and ash removal device, 8-No. 2 continuous pressure reducing cooling zone ash removal device, 9-Raw material burner, 10-Heat exchange system, 11-Material level detection system, 12-Gas-solid separation unit, 13-Backflush system, 14-Glass collector, 15-Saline wastewater feeding device, 16-Lined pipe, 17-Downstream ash silo, 18-Boiler feedwater system, 19-Crude syngas post-treatment system. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0033] like Figure 1As shown, the device for coordinated treatment of saline wastewater by downstream parallel-flow coal gasification heat recovery according to the present invention includes a coal gasifier 1, a syngas cooler 2, a cyclone separator 3, a material return 4, a circulating sealed tank 5, a particulate matter controller 6, a first continuous pressure reduction cooling ash discharge device 7, a second continuous pressure reduction cooling cold zone ash discharge device 8, a raw material burner 9, a heat exchange system 10, a material level detection system 11, a gas-solid separation unit 12, a backflushing system 13, a glass collector 14, a saline wastewater feeding device 15, a lined pipe 16, a downstream ash silo 17, a boiler feedwater system 18, and a crude syngas post-treatment system 19.

[0034] The coal gasifier 1 is divided into a slag-water zone, a constant temperature zone, and a reaction zone from bottom to top. The syngas cooler 2 is divided into a dense phase zone, a transition zone, a heat exchange zone, and a separation zone from bottom to top. The particulate matter controller 6 is divided into a cooling zone, a moving zone, and a desolidification zone from bottom to top.

[0035] The slag-water zone of the coal gasifier 1 is equipped with a coarse slag cooling water bath, the reaction zone is equipped with a raw material burner 9, and the constant temperature zone is connected to the dense phase zone of the syngas cooler 2 via a lining pipe 16. An oxygen nozzle is installed at the connection between the constant temperature zone and the lining pipe 16. The inner walls of both the reaction zone and the constant temperature zone of the coal gasifier 1 are lined with refractory linings; the angle α between the lining pipe 16 and the horizontal plane is 10° to 45°. The gasification raw materials and gasifying agent react in the reaction zone of the coal gasifier 1 to generate crude syngas. The generated crude syngas flows downward to the constant temperature zone, where the carbonaceous materials react with the oxygen injected by the oxygen nozzle to release heat, which reheats the crude syngas and prevents the temperature of the crude syngas from dropping, thus preventing molten fly ash from sticking to the wall and forming slag. The heated crude syngas carries molten fly ash and flows laterally into the lining pipe 16, no longer flowing downward to the slag-water zone, thus avoiding direct contact between the molten fly ash and the quench water in the slag-water zone.

[0036] The dense phase zone of the syngas cooler 2 is connected to the saline wastewater feed device 15, and the separation zone is connected to the upper part of the cyclone separator 3. The bottom of the cyclone separator 3 is connected to the transition zone of the syngas cooler 2 via the material leg 4 and the circulating sealed tank 5. A saline wastewater nozzle is provided at the connection between the dense phase zone of the syngas cooler 2 and the saline wastewater feed device 15. A heat exchange system 10 is provided in the heat exchange zone, and the heat exchange system 10 is connected to the boiler feedwater system 18. The heat exchange system 10 consists of a saturation unit, a superheating unit, and a preheating unit. The bottom outlet of the syngas cooler 2 is connected to the glass collector 14 via a first continuous cooling pressure reducing ash removal device 7. The material leg 4 is used to fill solid particles with a particle size of 50-200 μm, specifically corundum, quartz sand, catalyst, etc. Syngas cooler 2 uses circulating fluidized solid particles as the heat transfer medium, so that the high-temperature crude syngas and solid particles are completely mixed in the dense phase zone and transition zone of syngas cooler 2. The heat of crude syngas is first transferred to solid particles, and then the solid particles directly contact the heat exchange system 10 in the heat exchange zone. The solid particles have a very large specific surface area, so the overall heat transfer coefficient is more than 5 times that of traditional radiant waste boilers. At the same time, syngas cooler 2 cools down the high-temperature crude syngas from coal gasifier 1 and recovers heat. It solidifies the molten fly ash entrained in the high-temperature crude syngas and the soluble salts from the saline wastewater feeder 15 into a glassy substance. The glassy substance is granulated in the dense phase zone and transition zone with the solid particles in syngas cooler 2 as auxiliary material. Finally, the granulated glassy substance is cooled and discharged to the glassy substance collector 14 by the No. 1 continuous cooling pressure reduction ash discharge device 7.

[0037] The top of the cyclone separator 3 is connected to the desolidification zone of the particulate matter controller 6. The desolidification zone of the particulate matter controller 6 is equipped with a gas-solid separation unit 12, the moving zone is equipped with a fine powder level monitoring system 11, and the cooling zone is connected to the downstream ash silo 17 through a second continuous cooling pressure reduction and ash discharge device 8. The top of the particulate matter controller 6 is connected to the crude syngas post-treatment system 19 and the backflushing system 13, respectively. The crude syngas separated by the cyclone separator 3 enters the desolidification zone of the particulate matter controller 6. After further separation in the gas-solid separation unit 12, the crude syngas enters the crude syngas post-treatment system 19, and the resulting fine powder flows downward into the moving zone of the particulate matter controller 6. After the fine powder level monitoring system 11 detects that it has reached a certain level, it enters the cooling zone of the particulate matter controller 6. After being cooled by the second continuous cooling pressure reduction and ash discharge device 8, it is collected through the downstream ash silo 17.

[0038] The method for coordinating the treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery using the above-mentioned device includes the following steps:

[0039] a) Before starting work, a cooling water bath is set up in the slag and water area of ​​the coal gasifier 1, and solid particles heated to 200-400°C are filled into the material leg 4.

[0040] b) The preheated fuel and air are injected into the raw material burner 9 in the reaction zone of the coal gasifier 1 and ignited to raise the temperature of the reaction zone of the coal gasifier 1 to 950°C, while ensuring that the temperature of the dense phase zone of the syngas cooler 2 is higher than 300°C.

[0041] c) Replace the preheated fuel injected into the feedstock burner 9 with gasification feedstock and gasifying agent, adjust the ratio of gasification feedstock and gasifying agent to gradually increase and stabilize the temperature of the reaction zone of the coal gasifier 1 to 1200-1600℃, so that the gasification feedstock and gasifying agent undergo gasification reaction in the reaction zone to generate crude syngas, and the generated crude syngas carries molten fly ash and flows laterally into the lining pipe 16; at the same time, start the syngas cooler 2, heat exchange system 10, boiler feedwater system 18.

[0042] d) Start the oxygen nozzle at the connection between the constant temperature zone of the coal gasifier 1 and the lining pipe 16, and inject oxygen into the crude syngas entering the lining pipe 16. The amount of oxygen injected is 1 to 5 vol% of the total crude syngas.

[0043] e) Gradually add solid particles from feed 4 into the syngas cooler 2, until the amount of solid particles in the transition zone of the syngas cooler 2 reaches 0.3 to 0.6 times the total volume of the syngas cooler 2; as the operating temperature of the separation zone of the syngas cooler 2 reaches 200 to 500°C, the syngas cooler 2 begins normal circulating fluidization; the water from the boiler feedwater system 18 exchanges heat with the crude syngas in the heat exchange zone of the syngas cooler 2 through the heat exchange system 10 to generate steam, and the crude syngas after heat exchange enters the cyclone separator 3 from the separation zone, and the generated steam is incorporated into the steam pipeline network;

[0044] f) Start the back-flushing system 13 at the top of the particulate matter controller 6 to perform periodic back-flushing operations on the desolidification zone; at the same time, start the cooling water supply system in the cooling zone and the fine powder level monitoring system 11 in the moving zone; the coarse syngas after further separation by the cyclone separator 3 enters the desolidification zone of the particulate matter controller 6, and after further separation in the gas-solid separation unit 12, it enters the coarse syngas post-processing system 19, and the generated fine powder enters the moving zone of the particulate matter controller 6 downwards;

[0045] g) Start the No. 2 continuous cooling pressure reduction and ash discharge device 8 to cool and depressurize the fine powder in the moving area of ​​the particulate matter controller 6 and discharge it to the downstream ash silo 17.

[0046] h) Start the saline wastewater feeding device 15 and spray saline wastewater into the dense phase zone of the syngas cooler 2. At the same time, start the No. 1 continuous cooling pressure reduction and ash discharge device 7. The molten fly ash entrained in the crude syngas and the soluble salt solids in the saline wastewater are converted into glass in the dense phase zone and transition zone of the syngas cooler 2. The No. 1 continuous cooling pressure reduction and ash discharge device 7 cools the glass and depressurizes it before discharging it to the glass collector 14.

[0047] After completing the above steps, the entire device will enter the normal production process.

[0048] In step c) above, when the gasification feedstock is dry coal powder, the gasifying agent is oxygen and steam, and the crude syngas composition is: CH4 content of 0.01-0.1 vol%, H2 content of 5-15 vol%, CO content of 35-45 vol%, CO2 content of 3-10 vol%, and water content of 35-45 vol%. When the gasification feedstock is coal-water slurry, the gasifying agent is oxygen, and the crude syngas composition is: CH4 content of 0.01-0.1 vol%, H2 content of 15-25 vol%, CO content of 20-30 vol%, CO2 content of 10-15 vol%, and water content of 40-50 vol%.

[0049] In step d) above, the apparent velocity of the crude syngas in the lining pipe 16 is 10-25 m / s.

[0050] In step e) above, the operating pressure of the syngas cooler 2 after normal circulating fluidization is 1-8 MPaG, the operating temperature of the dense phase zone is 1250-1600℃, the operating temperature of the transition zone is 800-900℃, the operating temperature of the heat exchange zone is 200-800℃, and the operating temperature of the separation zone is 200-500℃; the steam pressure generated by the boiler feedwater system 18 through the heat exchange system 10 is 0.5-10 MPaG, and the temperature is 150-540℃; the apparent velocity of the crude syngas participating in the circulating fluidization of solid particles is 0.5-10 m / s.

[0051] In step h) above, the salt content of the saline wastewater is mainly NaCl and Na2SO4, and its total dissolved solids content is 10,000 to 60,000 mg / L.

[0052] Example 1

[0053] Bituminous coal is ground into dry pulverized coal using a dry mill and used as gasification feedstock, with oxygen and steam as gasifying agents. Preheated fuel and air are injected into the feed burner 9 in the reaction zone of gasifier 1 and ignited to raise the temperature. Once the temperature in the reaction zone of gasifier 1 reaches 950℃, the preheated fuel is replaced with dry pulverized coal, and the air is replaced with oxygen and steam. The dry pulverized coal flow rate is gradually increased to 62.5 t / h, while the oxygen and steam flow rates are gradually increased to 33650 Nm³. 3 With a flow rate of 4850 kg / h, the temperature in the reaction zone of gasifier 1 gradually increases and stabilizes at approximately 1500℃. The pressure in gasifier 1 is 4 MPaG. The operating temperature in the dense phase zone is 1300℃, the operating temperature in the transition zone is 850℃, the operating temperature in the heat exchange zone is 500℃, and the operating temperature in the separation zone is 240℃. During this process, 500 Nm³ of oxygen is injected into the crude syngas entering the lining pipe 16.3 The temperature of the crude syngas is maintained above 1500℃, and the apparent velocity of the crude syngas in the lined pipe 16 is 18 m / s. Subsequently, 60 t / h of saline wastewater (the main salts in the saline wastewater are NaCl and Na2SO4, with a total dissolved solids content of 10000 mg / L) is injected into the dense phase zone of the syngas cooler 2. The molten fly ash entrained in the high-temperature crude syngas and the soluble salts from the saline wastewater are solidified and transformed into sodalite-like material (Na4Al3Si3O4). 12 The syngas consists of a glassy mass primarily composed of Cl, calcium chlorosilicate (Ca7(SiO4)2Cl6), and kosmochlor (Na6Ca2(AlSiO4)6(SO4)4). This glassy mass is granulated in the dense phase and transition zones using quartz sand (50–200 μm particle size) circulating fluidized within the syngas cooler 2 as an auxiliary material. The apparent velocity of the crude syngas participating in the quartz sand circulation fluidization is 5 m / s. Approximately 1.5 t / h of glassy mass is generated and discharged from the first continuous cooling and pressure reducing ash removal device 7. After passing through the syngas cooler 2, the temperature of the crude syngas drops to 240℃. At this point, the heat exchange system 10 generates 70 t / h of steam at a pressure of 10 MPaG and a temperature of 540℃. After passing through the particulate matter controller 6, the solid content of the crude syngas is less than 0.1 ppm, with a 99.99% removal efficiency for 1 μm particles. The final crude syngas composition was: CH4 content 0.01 vol%, H2 content 10 vol%, CO content 40 vol%, CO2 content 7 vol%, and water content 42.5 vol%.

[0054] Example 2

[0055] Bituminous coal is ground into a 62% (w / w) coal-water slurry using a wet mill, which is then used as the gasification feedstock, with oxygen as the gasifying agent. Preheated fuel and air are injected into the feed burner 9 in the reaction zone of gasifier 1 and ignited to raise the temperature. Once the temperature in the reaction zone of gasifier 1 reaches 950℃, the preheated fuel is replaced with coal-water slurry, and the air is replaced with oxygen. The flow rate of the coal-water slurry is gradually increased to 100 t / h, while the oxygen flow rate is gradually increased to 40,000 Nm³. 3 The gasification process is as follows: At a rate of / h, the temperature in the reaction zone of gasifier 1 gradually increases and stabilizes at approximately 1300℃. The pressure in gasifier 1 is 6.5 MPaG. The operating temperature in the dense phase zone is 1250℃, the transition zone is 850℃, the heat exchange zone is 500℃, and the separation zone is 280℃. During this process, 500 Nm³ of oxygen is injected into the crude syngas entering the lining pipe 16. 3The temperature of the crude syngas is maintained above 1300℃, and the apparent velocity of the crude syngas in the lined pipe 16 is 18 m / s. Subsequently, 40 t / h of saline wastewater (the main salts in the saline wastewater are NaCl and Na2SO4, with a total dissolved solids content of 10000 mg / L) is injected into the dense phase zone of the syngas cooler 2. The molten fly ash entrained in the high-temperature crude syngas and the soluble salts from the saline wastewater are solidified and transformed into sodalite-like material (Na4Al3Si3O4). 12 The syngas consists of a glassy mass primarily composed of Cl, calcium chlorosilicate (Ca7(SiO4)2Cl6), and kosmochlor (Na6Ca2(AlSiO4)6(SO4)4). This glassy mass is granulated in the dense phase and transition zones using quartz sand (50–200 μm particle size) circulating fluidized within the syngas cooler 2 as an auxiliary material. The apparent velocity of the crude syngas participating in the quartz sand circulation fluidization is 5 m / s. Approximately 1 t / h of glassy mass is generated at this point and discharged from the No. 1 continuous cooling and pressure reducing ash removal device 7. After passing through the syngas cooler 2, the temperature of the crude syngas drops to 260℃. At this point, the heat exchange system 10 generates 60 t / h of steam with a pressure of 10 MPaG and a temperature of 540℃. After passing through the particulate matter controller 6, the solid content of the crude syngas is less than 0.1 ppm, with a 99.99% removal efficiency for 1 μm particles. The final crude syngas composition was: CH4 content 0.05 vol%, H2 content 19 vol%, CO content 24 vol%, CO2 content 12 vol%, and water content 44.5 vol%.

Claims

1. A method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery, characterized in that, This method is implemented using the following apparatus: The device includes a coal gasifier (1), a syngas cooler (2), a cyclone separator (3), a particulate matter controller (6), and a lined pipe (16). The coal gasification furnace (1) is divided into a slag water zone, a constant temperature zone and a reaction zone from bottom to top. The reaction zone is equipped with a raw material burner (9). The constant temperature zone is connected to the dense phase zone of the syngas cooler (2) through a lining pipe (16). An oxygen nozzle is provided at the connection between the constant temperature zone and the lining pipe (16). The syngas cooler (2) is divided into a dense phase zone, a transition zone, a heat exchange zone and a separation zone from bottom to top. Its dense phase zone is connected to the saline wastewater feed device (15), and its separation zone is connected to the upper part of the cyclone separator (3). The heat exchange zone is equipped with a heat exchange system (10) connected to the boiler feedwater system (18). The bottom outlet of the syngas cooler (2) is connected to the glass collector (14) through the No. 1 continuous cooling pressure reducing ash discharge device (7). The bottom of the cyclone separator (3) is connected to the transition zone of the syngas cooler (2) through the material leg (4) and the circulating sealed tank (5), and the top of the cyclone separator (3) is connected to the desolidification zone of the particulate matter controller (6). The particulate matter controller (6) is divided into a cooling zone, a moving zone and a desolidification zone from bottom to top. The desolidification zone is equipped with a gas-solid separation unit (12), the moving zone is equipped with a fine powder level monitoring system (11), the cooling zone is connected to the downstream ash silo (17) through the No. 2 continuous cooling pressure reduction ash discharge device (8), and the top of the particulate matter controller (6) is connected to the crude syngas post-treatment system (19) and the backflushing system (13) respectively. The method includes the following steps: a) Before starting work, a cooling water bath is set up in the slag water area of ​​the coal gasification furnace (1), and solid particles heated to 200-400°C are filled into the material leg (4); b) Using the raw material burner (9) in the reaction zone of the coal gasifier (1), preheated fuel and air are injected and ignited to raise the temperature, thereby raising the temperature of the reaction zone of the coal gasifier (1) to 950°C, while ensuring that the temperature of the dense phase zone of the syngas cooler (2) is higher than 300°C. c) Replace the preheated fuel injected into the raw material burner (9) with gasification raw material and gasifying agent, adjust the ratio of gasification raw material and gasifying agent to gradually increase the temperature of the reaction zone of the coal gasifier (1) and stabilize it at 1200-1600℃, so that the gasification raw material and gasifying agent undergo gasification reaction in the reaction zone to generate crude syngas, which carries molten fly ash; the generated crude syngas carrying molten fly ash flows laterally into the lining pipe (16); at the same time, start the syngas cooler (2), heat exchange system (10), and boiler feedwater system (18). d) Start the oxygen nozzle at the connection between the constant temperature zone of the gasifier (1) and the lining pipe (16) to inject oxygen into the crude syngas entering the lining pipe (16), so that the carbon-containing materials in the crude syngas burn and release heat, and the crude syngas is heated a second time to keep the molten fly ash entrained in the crude syngas in a molten flow state before entering the dense phase zone of the syngas cooler (2), so as to avoid it adhering to the pipe wall; the amount of oxygen injected is 1 to 5 vol% of the total crude syngas. e) Gradually add solid particles from the feed leg (4) into the syngas cooler (2), eventually making the solid particle content in the transition zone of the syngas cooler (2) reach 0.3 to 0.6 times the total volume of the syngas cooler (2); control the process parameters to ensure normal circulating fluidization of the syngas cooler (2), with an operating pressure of 1 to 8 MPaG, an operating temperature of 1250 to 1600℃ in the dense phase zone, an operating temperature of 800 to 900℃ in the transition zone, an operating temperature of 200 to 800℃ in the heat exchange zone, and an operating temperature of 200 to 800℃ in the separation zone. The operating temperature is 200-500℃; in the dense phase zone and transition zone, the molten fly ash comes into contact with the circulating solid particles, and is vitrified and granulated to form solid granular glass during the process of cooling from 1250-1600℃ to 800-900℃; the water in the boiler feedwater system (18) exchanges heat with the crude syngas in the heat exchange zone of the syngas cooler (2) through the heat exchange system (10) to generate steam, and the crude syngas after heat exchange enters the cyclone separator (3) from the separation zone, and the generated steam is incorporated into the steam pipeline network; f) Start the back-flushing system (13) at the top of the particulate matter controller (6) to perform periodic back-flushing operations on the desolidification zone; at the same time, start the cooling water supply system in the cooling zone and the fine powder level monitoring system (11) in the moving zone; the coarse syngas after further separation by the cyclone separator (3) enters the desolidification zone of the particulate matter controller (6), and after further separation in the gas-solid separation unit (12), it enters the coarse syngas post-processing system (19), and the generated fine powder enters the moving zone of the particulate matter controller (6) downwards; g) Start the No. 2 continuous cooling pressure reduction and ash discharge device (8) to cool and depressurize the fine powder in the moving area of ​​the particulate matter controller (6) and discharge it to the downstream ash silo (17). h) Start the saline wastewater feeding device (15) and spray saline wastewater into the dense phase zone of the syngas cooler (2). At the same time, start the No. 1 continuous cooling pressure reduction and ash discharge device (7). The molten fly ash entrained in the crude syngas and the soluble salt solids in the saline wastewater are transformed into glass in the dense phase zone and transition zone of the syngas cooler (2). The No. 1 continuous cooling pressure reduction and ash discharge device (7) cools the glass and depressurizes it before discharging it to the glass collector (14). After completing the above steps, the entire device will enter the normal production process.

2. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, A saline wastewater nozzle is provided at the connection between the dense phase zone of the syngas cooler (2) and the saline wastewater feed device (15).

3. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, The angle α between the lining pipe (16) and the horizontal plane is 10° to 45°.

4. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, In step c), when the gasification feedstock is dry coal powder, the gasifying agent is oxygen and steam, and the crude syngas composition is: CH4 content of 0.01-0.1 vol%, H2 content of 5-15 vol%, CO content of 35-45 vol%, CO2 content of 3-10 vol%, and water content of 35-45 vol%; when the gasification feedstock is coal-water slurry, the gasifying agent is oxygen, and the crude syngas composition is: CH4 content of 0.01-0.1 vol%, H2 content of 15-25 vol%, CO content of 20-30 vol%, CO2 content of 10-15 vol%, and water content of 40-50 vol%.

5. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, In step d), the apparent velocity of the crude syngas in the lining pipe (16) is 10 to 25 m / s.

6. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, The particle size of the solid particles is 50–200 μm, and in step e), the apparent velocity of the crude syngas participating in the circulating fluidization of the solid particles is 0.5–10 m / s.

7. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, In step e), the steam pressure generated by the boiler feedwater system (18) through the heat exchange system (10) is 0.5 to 10 MPaG and the temperature is 150 to 540 °C.

8. The method for coordinated treatment of saline wastewater by downflow parallel-flow coal gasification heat recovery according to claim 1, characterized in that, In step h), the salt content of the saline wastewater is mainly NaCl and Na2SO4, and the total dissolved solids content is 10,000 to 60,000 mg / L.

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