Caprolactam waste liquid and coal co-gasification device

Abstract

The utility model discloses a caprolactam waste liquid and coal co-gasification device which comprises a caprolactam waste liquid pretreatment unit and a co-gasification unit, the caprolactam waste liquid pretreatment unit comprises an extraction tower, a waste liquid preheater, a steam stripping tower, a deamination mixer, a deamination tower, a cooler and a benzene extraction residual liquid buffer tank which are connected in sequence; the co-gasification unit comprises a rod mill, a discharge chute, a coal slurry tank and an entrained-flow bed water-cooled wall gasification furnace which are connected in sequence; the benzene extraction residual liquid buffer tank is connected with the rod mill through a caprolactam waste liquid pipeline, and the rod mill is further connected with an additive pipeline, a fresh water pipeline and a weighing coal feeder. By adopting the caprolactam waste liquid and coal co-gasification device disclosed by the invention, efficient conversion of the caprolactam waste liquid is realized, crude synthesis gas is produced, meanwhile, the wastewater treatment difficulty is reduced, the environment-friendly production is promoted, and the social and economic benefits are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of water-coal slurry gasification, and specifically relates to a device for co-gasification of caprolactam waste liquid and coal. Background Art

[0002] Caprolactam waste liquid is acidic, contains benzene, has high COD content, contains ammonium sulfate, has a large output, is difficult to handle, and has a high cost. The treatment of high-salt caprolactam organic waste liquid has always been a difficult problem for chemical companies. In industrial applications, the concentrated incineration method and the concentrated extraction method are usually used to treat the benzene extraction residue. The concentrated extraction method has a simple process and the concentrated incineration method has a good treatment effect, but both methods require a large amount of steam during the treatment process. Among them, the organic waste liquid layer obtained by the concentrated extraction method needs to be further treated, and the concentrated incineration method requires auxiliary fuel, which leads to high treatment costs and serious corrosion of the incinerator. Simple and efficient caprolactam waste liquid treatment technology needs to be developed urgently.

[0003] As one of the mainstream gasification technologies, water-coal slurry gasification technology has easy operating parameters to control and stable operation. It is widely used in chemical production processes with the main goal of obtaining hydrogen resources, and has expanded and developed a series of wastewater slurry gasification technologies.

[0004] CN114410349 A discloses a waste pretreatment process for supporting water-coal slurry gasification, including a method for treating various waste liquids, urban sewage sludge, oil sludge, waste diesel and other wastes. After the waste is pretreated, it is sent to the gasifier to react with oxygen to generate synthesis gas. This method uses a specially designed burner to treat wastewater, sludge, waste residue, and waste oil. However, for treating organic wastewater such as caprolactam waste liquid, it does not consider that the organic waste liquid contains dissolved sodium salts, and the prepared water-coal slurry has a low concentration, is easy to precipitate or crystallize, and has a low effective component of synthesis gas. In addition, it does not consider that the sodium salt in the waste liquid has an erosive effect on the refractory bricks of the gasifier, and cannot be used for treating caprolactam waste liquid for a long time. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide a co-gasification device for caprolactam waste liquid and coal, so as to achieve efficient conversion of caprolactam waste liquid and produce crude synthesis gas (CO+H2), while reducing the difficulty of wastewater treatment, promoting environmentally friendly production, and improving social and economic benefits.

[0006] The utility model solves the above problems through the following technical means: a caprolactam waste liquid and coal co-gasification device, comprising a caprolactam waste liquid pretreatment unit and a co-gasification unit, the caprolactam waste liquid pretreatment unit comprising a caprolactam extraction tower, a waste liquid preheater, a steam stripping tower, a deamination mixer, a deamination tower, a cooler and a benzene extraction residual liquid buffer tank connected in sequence; the co-gasification unit comprises a rod mill, a discharge trough, a coal slurry trough and an entrained flow bed water-cooled wall gasifier connected in sequence; the benzene extraction residual liquid buffer tank is connected to the rod mill through a caprolactam waste liquid pipeline, and the rod mill is also connected with an additive pipeline, a fresh water pipeline and a weighing coal feeder.

[0007] Furthermore, the steam stripping tower is connected to a benzene-water separator.

[0008] Furthermore, the deamination tower is connected to an ammonia absorption tower.

[0009] Furthermore, the outlet of the hexane extraction tower is connected to the inlet of the waste liquid preheater through the hexane extraction tower waste liquid pump.

[0010] Furthermore, the outlet of the steam stripping tower is connected to the inlet of the deamination mixer through a stripping tower waste liquid pump.

[0011] Furthermore, the outlet of the benzene extraction residual liquid buffer tank is connected to the caprolactam waste liquid pipeline through a tank waste liquid pump.

[0012] Furthermore, the outlet of the discharge trough is connected to the inlet of the coal slurry tank through a discharge trough pump.

[0013] Furthermore, the outlet of the coal slurry tank is connected to the burner of the fluidized flow water-cooled wall gasifier through a coal slurry tank pump.

[0014] Furthermore, a pH analyzer and a waste liquid flow meter are provided on the caprolactam waste liquid pipeline.

[0015] Furthermore, a fresh water flow meter is provided on the fresh water pipeline.

[0016] During the connection process of the above-mentioned devices, corresponding pipelines are equipped as needed. This is the existing technology and will not be described in detail.

[0017] Beneficial effects of the utility model: The caprolactam waste liquid and coal co-gasification device of the utility model first pre-treats the caprolactam waste liquid through the caprolactam waste liquid pretreatment unit, and then co-gasifies it with coal, which can simply and efficiently treat the caprolactam waste liquid and produce crude synthesis gas (CO+H2), while reducing the difficulty of wastewater treatment, promoting environmentally friendly production, and improving social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0019] Figure 1 This is a schematic diagram of a device for co-gasification of caprolactam waste liquid and coal according to an embodiment of the utility model.

[0020] Figure numerals: 1. benzene extraction tower; 2. benzene extraction tower waste liquid pump; 3. waste liquid preheater; 4. steam stripping tower; 5. benzene water separator; 6. stripping tower waste liquid pump; 7. deamination mixer; 8. deamination tower; 9. ammonia absorption tower; 10. cooler; 11. benzene extraction residual liquid buffer tank; 12. membrane washing water pipeline; 13. ion exchange concentrated liquid pipeline; 14. tank waste liquid pump; 15. PH analyzer; 16. waste liquid flowmeter; 17. rod mill; 18. additive pipeline; 19. fresh water pipeline; 20. weighing coal feeder; 21. fresh water flowmeter; 22. discharge trough; 23. discharge trough pump; 24. coal slurry tank; 25. coal slurry tank pump; 26. fluidized bed water-cooled wall gasification furnace; 27. burner. DETAILED DESCRIPTION

[0021] The present invention will be further described below through the accompanying drawings and embodiments, which are not intended to further limit the content of the present invention. Those skilled in the art should understand that equivalent replacements or corresponding improvements made to the technical features of the present invention still fall within the scope of protection of the present invention.

[0022] like Figure 1 As shown, the caprolactam waste liquid and coal co-gasification device of this embodiment includes a caprolactam waste liquid pretreatment unit and a co-gasification unit. The caprolactam waste liquid pretreatment unit includes a caprolactam extraction tower 1, a waste liquid preheater 3, a steam stripping tower 4, a deamination mixer 7, a deamination tower 8, a cooler 10 and a benzene extraction residual liquid buffer tank 11 connected in sequence; the co-gasification unit includes a rod mill 17, a discharge trough 22, a coal slurry tank 24 and an entrained flow water-cooled wall gasifier 26 connected in sequence. The following is further elaborated:

[0023] Caprolactam waste liquid pretreatment unit: The properties and composition of the caprolactam waste liquid to be treated are shown in Table 1. The benzene extraction residue (caprolactam waste liquid to be treated) with an acidity of about 40°C is collected in a caprolactam extraction tower 1. The bottom outlet of the caprolactam extraction tower is connected to the inlet of a caprolactam extraction tower waste liquid pump 2. The outlet of the caprolactam extraction tower waste liquid pump is connected to the inlet of a waste liquid preheater 3. The outlet of the waste liquid preheater is connected to a steam stripping tower 4. A benzene water separator 5 is arranged on the top of the steam stripping tower. Benzene is separated by the benzene water separator for recycling. The bottom outlet of the steam stripping tower is connected to the inlet of a stripping tower waste liquid pump 6. The outlet of the stripping tower waste liquid pump is connected to a deamination mixer 7. 50% NaOH is added to the upper part of the deamination mixer for neutralization, and ammonium sulfate in the waste liquid is converted into sodium sulfate. The deamination mixer is connected to the deamination tower 8, the top of the deamination tower is connected to the ammonia absorption tower 9, the gaseous ammonia is recovered to generate dilute ammonia water, and the bottom outlet of the deamination tower is connected to the inlet of the cooler 10, at which time, an alkaline benzene extraction residual liquid with a temperature of 40-100°C, a pH of 7-9, and a benzene content of 35ppm is obtained. The outlet of the cooler is connected to the benzene extraction residual liquid buffer tank 11, the membrane washing water pipeline 12 and the ion exchange concentrated liquid pipeline 13 are connected to the top of the benzene extraction residual liquid buffer tank, and the bottom of the benzene extraction residual liquid buffer tank is connected to the tank waste liquid pump 14, and the outlet of the tank waste liquid pump is provided with a pH analyzer 15 and a waste liquid flow meter 16. The tank waste liquid pump is connected to the inlet of the rod mill 17.

[0024] Co-gasification unit: The inlet of the rod mill is connected to the caprolactam waste liquid pipeline, the additive pipeline 18, the fresh water pipeline 19, and the weighing coal feeder 20, wherein the fresh water pipeline is provided with a fresh water flow meter 21. The outlet of the rod mill is connected to the discharge trough 22, the discharge trough is connected to the inlet of the discharge trough pump 23, the outlet of the discharge trough pump is connected to the coal slurry trough 24, the coal slurry trough is connected to the inlet of the coal slurry trough pump 25, and the outlet of the coal slurry trough pump is connected to the burner 27 at the top of the fluidized bed water-cooled wall gasifier 26. The pulping feeding process is switched by the valve of the fresh water pipeline and the valve of the caprolactam waste liquid pipeline, and the pulping water flow is read by the waste liquid flow meter and the fresh water flow meter.

[0025] Table 1 Properties and composition of caprolactam waste liquid to be treated

[0026]

[0027]

[0028] After the device proposed in this scheme is implemented, qualified coal slurry is pumped to the burner through the coal slurry pump. When the concentration of coal slurry entering the furnace is 60%, the dry basis composition of the crude synthesis gas and the indicators of wastewater discharged from the fluidized flow water-cooled wall gasifier are shown in Table 2.

[0029] Table 2 Dry basis composition of crude synthesis gas and indicators of wastewater discharged from entrained flow water-cooled wall gasifier in Example 1

[0030] Crude syngas composition unit Numeric H2 <![CDATA[% v ]]> 30.22 CO <![CDATA[% v ]]> 49.82 CO2 <![CDATA[% v ]]> 18.39 H2S <![CDATA[% v ]]> 0.21 COS <![CDATA[% v ]]> <0.01 CH4 <![CDATA[mL / m 3 ]]> 24 N2 <![CDATA[% v ]]> 2.25 AR <![CDATA[% v ]]> 0.01 Gasifier wastewater discharge indicators unit Numeric COD mg / L 339 Ammonia nitrogen mg / L 114.6

[0031] Comparative Example 1

[0032] like Figure 1 As shown, the scheme includes a fresh water and coal co-gasification device: the rod mill inlet is connected to the additive pipeline 18, the fresh water pipeline 19, and the weighing coal feeder 20 respectively, wherein the fresh water pipeline is provided with a fresh water flow meter 21. The rod mill outlet is connected to the discharge trough 22, the discharge trough is connected to the inlet of the discharge trough pump 23, the outlet of the discharge trough pump is connected to the coal slurry trough 24, the coal slurry trough is connected to the inlet of the coal slurry trough pump 25, and the outlet of the coal slurry trough pump is connected to the burner 27 at the top of the fluidized bed water-cooled wall gasifier 26. Qualified coal slurry is pumped to the burner by the coal slurry pump. When the concentration of the coal slurry entering the furnace is 60%, the dry basis composition of the crude syngas is shown in Table 3.

[0033] Table 3 Comparative Example 1 Dry basis composition of crude synthesis gas and indicators of wastewater discharged from water-cooled wall gasifier

[0034] composition unit Numeric H2 <![CDATA[% v ]]> 27.4 CO <![CDATA[% v ]]> 45.58 CO2 <![CDATA[% v ]]> 22.37 H2S <![CDATA[% v ]]> 0.14 COS <![CDATA[% v ]]> <0.01 CH4 <![CDATA[mL / m 3 ]]> 33 N2 <![CDATA[% v ]]> 4.47 AR <![CDATA[% v ]]> 0.04 Gasifier wastewater discharge indicators unit Numeric COD mg / L 278 Ammonia nitrogen mg / L 112

[0035] The results in Tables 2 and 3 show that compared with the fresh water and coal co-gasification device, the dry basis composition (CO+H2) of the crude synthesis gas is improved according to the caprolactam waste liquid and coal co-gasification device proposed in this scheme, and the content of hydrogen sulfide, a corrosive factor, is slightly higher, and its content is also within the qualified range of the same industry. The results in Tables 1 and 2 show that according to the implementation of this scheme, the COD concentration of the wastewater discharged from the gasifier is much lower than the COD of the caprolactam waste liquid to be treated.

[0036] The reaction temperature in the fluidized-flow water-cooled wall gasifier is as high as 1400℃-1600℃, which can oxidize the organic matter in the waste liquid (typical COD content is 100000mg / L) to produce CO, H2, NH3 and H2S, etc. The volume content of effective gas (CO+H2) in the raw coal gas is greater than 78%, the COD of the wastewater discharged by the gasification reaction is less than 500mg / L, the COD removal rate is 99.5%, and the ammonia nitrogen content is 100-300mg / L.

[0037] Secondly, the co-gasifier uses an entrained flow water-cooled wall gasifier, which can prevent the erosion of inorganic salts in the caprolactam waste liquid. The reaction temperature in the co-gasifier is as high as 1400℃-1600℃, which can melt the sodium sulfate in the waste liquid and the ash in the coal to form millimeter-level slag liquid. The slag liquid flows downward through the slag mouth and is cooled by quenching water into a millimeter-level glassy solid, referred to as coarse slag. Most of the sodium element in the caprolactam waste liquid forms coarse slag, which can be used to make cement or other building materials.

[0038] In summary, the implementation of the caprolactam waste liquid and coal co-gasification device can achieve the efficient conversion of the organic components of the caprolactam waste liquid and greatly save the cost of wastewater treatment. It is a new, simple and efficient caprolactam waste liquid treatment device.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A caprolactam waste liquid and coal co-gasification device, characterized in that: It comprises a caprolactam waste liquid pretreatment unit and a co-gasification unit, wherein the caprolactam waste liquid pretreatment unit comprises a caprolactam extraction tower, a waste liquid preheater, a steam stripping tower, a deamination mixer, a deamination tower, a cooler and a benzene extraction residual liquid buffer tank which are connected in sequence; the co-gasification unit comprises a rod mill, a discharge trough, a coal slurry trough and an entrained flow water-cooled wall gasifier which are connected in sequence; the benzene extraction residual liquid buffer tank is connected to the rod mill through a caprolactam waste liquid pipeline, and the rod mill is also connected with an additive pipeline, a fresh water pipeline and a weighing coal feeder.

2. The caprolactam waste liquid and coal co-gasification device according to claim 1, characterized in that: The steam stripping tower is connected with a benzene-water separator.

3. The caprolactam waste liquid and coal co-gasification device according to claim 2, characterized in that: The deamination tower is connected with an ammonia absorption tower.

4. The device for co-gasification of caprolactam waste liquid and coal according to claim 3, characterized in that: The outlet of the hexane extraction tower is connected to the inlet of the waste liquid preheater through the hexane extraction tower waste liquid pump.

5. The device for co-gasification of caprolactam waste liquid and coal according to claim 4, characterized in that: The outlet of the steam stripping tower is communicated with the inlet of the deamination mixer through a stripping tower waste liquid pump.

6. The device for co-gasification of caprolactam waste liquid and coal according to claim 5, characterized in that: The outlet of the benzene extraction residual liquid buffer tank is connected to the caprolactam waste liquid pipeline through a tank waste liquid pump.

7. The device for co-gasification of caprolactam waste liquid and coal according to claim 6, characterized in that: The outlet of the discharge trough is communicated with the inlet of the coal slurry tank through a discharge trough pump.

8. The caprolactam waste liquid and coal co-gasification device according to claim 7, characterized in that: The outlet of the coal slurry tank is connected to the burner of the fluidized flow water-cooled wall gasifier through a coal slurry tank pump.

9. The device for co-gasification of caprolactam waste liquid and coal according to claim 8, characterized in that: The caprolactam waste liquid pipeline is provided with a pH analyzer and a waste liquid flow meter.

10. The device for co-gasification of caprolactam waste liquid and coal according to claim 9, characterized in that: The fresh water pipeline is provided with a fresh water flow meter.

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