A system and method for extracting and recovering styrene from styrene-butadiene rubber wastewater

Abstract

The present invention discloses a system and method for extracting and recovering styrene from styrene-butadiene rubber (SBR) wastewater. The evaporator comprises a shell and a heat exchange pipeline. The SBR wastewater delivery pipeline is connected to the shell inlet. A first outlet at the bottom of the shell is connected to the bottom of a condenser via a first pipeline. The outlet of the heat exchange pipeline is connected to a gas-liquid separator via a pipeline. A styrene discharge pipeline is provided at the bottom of the gas-liquid separator. The gas outlet of the gas-liquid separator is connected to the inlet of a compressor. The outlet of the compressor is connected to the inlet of an internal pipeline within the condenser. The terminal outlet of the internal pipeline is located at the bottom of the condenser. The top outlet of the condenser is connected to the inlet of the heat exchange pipeline of the evaporator via a connecting pipeline. A styrene-free water discharge pipeline is provided in the middle of the condenser. The connecting pipeline is equipped with an expansion valve. The present invention utilizes the large difference in boiling points between n-hexane and styrene to stably recover styrene from SBR wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, in particular to a system for extracting and recovering styrene from styrene-butadiene rubber wastewater and a recovery method thereof. Background Art

[0002] SBR wastewater has a complex composition, containing styrene, salts, phenols, and organic amines, making it difficult to treat and poorly biodegradable. Wastewater treatment alone cannot meet wastewater discharge standards. In particular, the styrene in SBR wastewater easily polymerizes, making it difficult to recycle and reuse. Summary of the Invention

[0003] The purpose of the present invention is to provide a system for extracting and recovering styrene from styrene-butadiene rubber wastewater in order to solve the problem that styrene in styrene-butadiene rubber wastewater in the prior art is difficult to recycle.

[0004] Another object of the present invention is to provide a method for recovering styrene based on the system.

[0005] The technical solution adopted to achieve the purpose of the present invention is:

[0006] A system for extracting and recovering styrene from styrene-butadiene rubber wastewater, comprising an evaporator, a gas-liquid separator, a compressor, and a condenser, wherein:

[0007] The evaporator includes a shell and a heat exchange pipeline located inside the shell, and a styrene-butadiene rubber sewage delivery pipeline is connected to the inlet of the shell; a first outlet at the bottom of the shell is connected to the bottom of the condenser through a first pipeline, and the outlet of the heat exchange pipeline is connected to the gas-liquid separator through a pipeline; a styrene discharge pipeline is provided at the bottom of the gas-liquid separator, the gas outlet of the gas-liquid separator is connected to the inlet of the compressor, the outlet of the compressor is connected to the inlet of the internal pipeline in the condenser, the end outlet of the internal pipeline is located at the bottom of the condenser, and the top outlet of the condenser is connected to the inlet of the heat exchange pipeline of the evaporator through a connecting pipeline, a styrene-free water discharge pipeline is provided in the middle of the condenser, and an expansion valve is provided on the connecting pipeline.

[0008] The heat exchange pipeline is a spiral coil.

[0009] The bottom of the shell is further provided with a second outlet, and the second outlet is connected to the styrene-butadiene rubber sewage conveying pipeline through a second pipeline.

[0010] The internal piping is spiral coiled.

[0011] The terminal outlet of the internal pipeline is connected with a porous distributor, and the porous distributor is located at the bottom of the condenser.

[0012] Another aspect of the present invention is a method for recovering styrene based on the system, comprising the following steps:

[0013] The styrene-containing wastewater is transported to the shell of the evaporator through a styrene-butadiene rubber wastewater transport pipeline, and after cooling in the evaporator, it enters the bottom of the condenser through a first pipeline. In the condenser, n-hexane is mixed with the styrene-containing wastewater, and the n-hexane extracts styrene. The upper part of the condenser is a mixture of n-hexane and styrene, which is discharged from the top of the condenser and enters a connecting pipeline. After passing through an expansion valve, the mixture of n-hexane and styrene is heated and enters the heat exchange pipeline inside the evaporator. The n-hexane is completely vaporized in the heat exchange pipeline of the evaporator, while the styrene is not vaporized. The mixture enters a gas-liquid separator, where gas-liquid separation is performed. The styrene liquid is discharged from the styrene discharge pipeline of the gas-liquid separator. After passing through a compressor, the n-hexane gas enters the internal pipeline of the condenser. The n-hexane converted into liquid is output from a porous distributor, mixed with the styrene-containing wastewater entering the condenser, and styrene is extracted. Wastewater not containing styrene is discharged from a styrene-free water discharge pipeline in the middle of the condenser.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] By utilizing the significant difference in boiling points between n-hexane and styrene, the present invention can stably recover styrene from styrene-butadiene rubber wastewater, thereby reducing the COD content of the wastewater and achieving environmental protection. Furthermore, styrene, an important chemical raw material, can be recycled and reused, reducing production costs and facilitating market promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Shown is a schematic structural diagram of the present invention.

[0017] In the figure: 1-evaporator, 2-gas-liquid separator, 3-compressor, 4-condenser, 5-shell, 6-heat exchange pipeline, 7-styrene-butadiene rubber sewage transmission pipeline, 8-first pipeline, 9-second pipeline, 10-styrene discharge pipeline, 11-internal pipeline, 12-porous distributor, 13-connecting pipeline, 14-expansion valve, 15-styrene-free water discharge pipeline. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] Example 1

[0020] A system for extracting and recovering styrene from styrene-butadiene rubber wastewater comprises an evaporator 1, a gas-liquid separator 2, a compressor 3, and a condenser 4, wherein:

[0021] The evaporator 1 includes a shell 5 and a heat exchange pipe 6 located within the shell 5. Preferably, the heat exchange pipe 6 is a spiral coil to enhance heat exchange efficiency. A styrene-butadiene rubber wastewater delivery pipe 7 is connected to the inlet of the shell 5. A first outlet at the bottom of the shell 5 is connected to the bottom of the condenser 4 via a first pipe 8, and the outlet of the heat exchange pipe 6 is connected to the gas-liquid separator 2 via a pipe. Preferably, a second outlet is also provided at the bottom of the shell 5, connected to the styrene-butadiene rubber wastewater delivery pipe 7 via a second pipe 9.

[0022] A styrene discharge line 10 is provided at the bottom of the gas-liquid separator 2. The gas outlet of the gas-liquid separator 2 is connected to the inlet of the compressor 3, and the outlet of the compressor 3 is connected to the inlet of an internal line 11 within the condenser 4. Preferably, the internal line 11 is a spiral coil to increase heat exchange efficiency. A perforated distributor 12 is provided at the end of the internal line 11. The top outlet of the condenser 4 is connected to the inlet of the heat exchange line 6 within the evaporator 1 via a connecting line 13. The connecting line 13 is provided with an expansion valve 14. A styrene-free water discharge line 15 is provided in the middle of the condenser 4.

[0023] Example 2

[0024] The method for recovering styrene based on the system described in Example 1 comprises the following steps:

[0025] The 60°C styrene-containing wastewater is transported to the shell 5 of the evaporator 1 through the styrene-butadiene rubber wastewater transport pipeline 7. After passing through the evaporator 1, the styrene-containing wastewater is cooled to 55°C and enters the bottom of the condenser 4 through the first pipeline 8. In the condenser 4, n-hexane is mixed with the styrene-containing wastewater, and the n-hexane extracts styrene. The upper part of the condenser 4 is a mixture of n-hexane and styrene. The mixture is discharged from the top of the condenser 4 and enters the connecting pipeline 13. Before passing through the expansion valve 14, the mixed liquid of n-hexane and styrene is 75°C. After passing through the expansion valve 14, the mixed liquid of n-hexane and styrene is 69°C and enters the evaporator. In the heat exchange pipe 6 of the evaporator 1, the n-hexane is completely vaporized in the heat exchange pipe 6 of the evaporator 1, and the styrene is not vaporized. After passing through the evaporator 1, the temperature of the n-hexane and styrene is 74°C, and they enter the gas-liquid separator 2. Gas-liquid separation is performed in the gas-liquid separator 2, and the styrene liquid is discharged from the styrene discharge pipe 10. The n-hexane gas passes through the compressor 3 and is heated to 90°C. It enters the internal pipe 11 in the condenser 4, and the n-hexane converted into liquid is output from the porous distributor 12, mixed with the styrene-containing wastewater entering the condenser 4, and styrene is extracted. The wastewater not containing styrene is discharged from the styrene-free water discharge pipe 15 in the middle of the condenser.

[0026] For ease of explanation, spatial relative terms such as "upper", "lower", "left", "right" and the like are used in the embodiments to illustrate the relationship of one element or feature shown in the figures relative to another element or feature. It should be understood that, in addition to the orientation shown in the figures, spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, the element described as being "under" other elements or features will be positioned "above" other elements or features. Therefore, the exemplary term "under" can include both upper and lower orientations. The device can be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here can be interpreted accordingly.

[0027] Moreover, relational terms such as “first” and “second” are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any such actual relationship or order between these components.

[0028] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting and recovering styrene from styrene-butadiene rubber wastewater, characterized in that: The extraction recovery method is based on an extraction recovery system comprising an evaporator, a gas-liquid separator, a compressor and a condenser, wherein: The evaporator includes a shell and a heat exchange pipeline located inside the shell, and a styrene-butadiene rubber sewage delivery pipeline is connected to the inlet of the shell; a first outlet at the bottom of the shell is connected to the bottom of the condenser through a first pipeline, and the outlet of the heat exchange pipeline is connected to the gas-liquid separator through a pipeline; a styrene discharge pipeline is provided at the bottom of the gas-liquid separator, the gas outlet of the gas-liquid separator is connected to the inlet of the compressor, the outlet of the compressor is connected to the inlet of the internal pipeline in the condenser, the terminal outlet of the internal pipeline is located at the bottom of the condenser, and the top outlet of the condenser is connected to the inlet of the heat exchange pipeline of the evaporator through a connecting pipeline. A styrene-free water discharge pipeline is provided in the middle of the condenser, and an expansion valve is provided on the connecting pipeline; The extraction recovery method comprises the following steps: The styrene-containing wastewater is transported to the shell of the evaporator through a styrene-butadiene rubber wastewater transport pipeline, and after cooling in the evaporator, it enters the bottom of the condenser through a first pipeline. In the condenser, n-hexane is mixed with the styrene-containing wastewater, and the n-hexane extracts styrene. The upper part of the condenser is a mixture of n-hexane and styrene, which is discharged from the top of the condenser and enters a connecting pipeline. After passing through an expansion valve, the mixture of n-hexane and styrene is cooled and enters the heat exchange pipeline inside the evaporator. The n-hexane is completely vaporized in the heat exchange pipeline of the evaporator, while the styrene is not vaporized. The mixture enters a gas-liquid separator, where gas-liquid separation is performed. The styrene liquid is discharged from the styrene discharge pipeline of the gas-liquid separator. After passing through a compressor, the n-hexane gas enters the internal pipeline of the condenser. The n-hexane converted into liquid is output from a porous distributor, mixed with the styrene-containing wastewater entering the condenser, and styrene is extracted. Wastewater not containing styrene is discharged from a styrene-free water discharge pipeline in the middle of the condenser.

2. The extraction recovery method according to claim 1, wherein The heat exchange pipeline is a spiral coil.

3. The extraction recovery method according to claim 1, wherein: The bottom of the shell is further provided with a second outlet, and the second outlet is connected to the styrene-butadiene rubber sewage conveying pipeline through a second pipeline.

4. The extraction recovery method according to claim 1, wherein: The internal piping is spiral coiled.

5. The extraction recovery method according to claim 1, wherein: The terminal outlet of the internal pipeline is connected with a porous distributor, and the porous distributor is located at the bottom of the condenser.

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