KR20160004148A - Energy recycling method of waste energy in butadiene manufacturing process - Google Patents

Abstract

The present invention relates to an energy recycling method in a butadiene manufacturing process, regarding a butadiene manufacturing process using an oxidative dehydrogenation reaction, which comprises the steps of: a) supplying a reaction product obtained from a reactor to a compressor equipped with a heat exchanger; b) supplying the reaction product to a solvent absorbing tower by compressing the same in the compressor; and c) penetrating hot water (HW) or low hot water (LHW) discharged from the heat exchanger equipped in the compressor through at least one device unit equipped with the heat exchanger. The method is capable of improving economic feasibility of a butadiene manufacturing process, by reducing a net amount of energy required for the butadiene manufacturing process using the oxidative dehydrogenation reaction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling energy in a butadiene production process,

The present invention relates to a method for energy recycling in a butadiene production process.

Butadiene is an important basic chemical, and it is used as an intermediary between numerous petrochemical products such as synthetic rubber and electronic materials. It is one of the most important basic oils in the petrochemical market and its demand and value are gradually increasing. Examples of the method for producing butadiene include naphtha cracking, direct dehydrogenation reaction of n-butene, and oxidative dehydrogenation reaction of n-butene.

Among them, the butadiene production method using the oxidative dehydrogenation reaction is carried out at a high temperature of 300 to 600 ° C., and the butadiene produced by the reaction is dissolved in an absorption solvent to separate gas products, and the solvent is removed. Butadiene is obtained. On the other hand, among the separated gaseous products, the components effective for the reaction are circulated and re-introduced into the reactor, and the remaining portions are discharged to the outside of the system together with the purge stream.

In the production of butadiene through the oxidative dehydrogenation reaction, the reactor is operated at a relatively low pressure and the solvent absorption tower is operated at a relatively high pressure, so that the reaction product obtained from the reactor is compressed by the compressor before being supplied to the solvent absorption tower . The compression heat is generated in the compression process, and the compression heat needs to be removed before being supplied to the absorption tower.

The amount of net energy required in the process was reduced by supplying the compressed heat generated in the compression process to an individual unit in a process such as a high boiling point removing column, a degassing column and a butadiene refining column.

In one embodiment for achieving the object of the present invention, there is provided a process for producing butadiene using an oxidative dehydrogenation reaction, comprising the steps of: a) supplying a reaction product obtained from a reactor to a compressor equipped with a heat exchanger; b) compressing the reaction product in the compressor and supplying it to the solvent absorption tower; And c) passing hot water (HW) or low hot water (LHW) discharged from a heat exchanger provided in the compressor to at least one unit equipped with a heat exchanger. .

According to the present invention, the amount of the net energy required in the process can be reduced by supplying the compressed heat generated during the compression process before supplying the reaction product to the solvent absorption tower to the individual device units in the butadiene production process.

This improves the economical efficiency of the butadiene production process.

1 is a schematic view illustrating a process for preparing butadiene using an oxidative dehydrogenation reaction according to an embodiment of the present invention.
FIG. 2 is a schematic view illustrating a process of supplying compressed heat generated in a process of compressing a reaction product to an individual unit requiring heat energy according to an embodiment of the present invention.
FIG. 3 is a schematic view illustrating a process of supplying compressed heat generated during the compression of a reaction product to an individual unit requiring heat energy according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Although the present invention has been described with reference to the embodiments shown in the drawings, it is to be understood that the technical idea of the present invention and its essential structure and operation are not limited thereby. In particular, the term "light gas " as used throughout this specification, including claims and abstract, includes nitrogen, oxygen, water vapor, carbon monoxide, carbon dioxide, etc. in the reaction products produced through oxidative dehydrogenation Should be understood to refer to the gaseous components that comprise it. In addition, the term "active ingredient" should be understood to mean a component effective for the butadiene preparation reaction, such as nitrogen, oxygen, unreacted raw materials or butadiene.

Butadiene production equipment

The butadiene production apparatus for carrying out the above-mentioned butadiene production method through the oxidative dehydrogenation reaction is characterized in that each component of the first stream 30 containing C4 oil, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) Or a plurality of individual pipelines which are branched in one pipeline directly connected to the reactor 10 and into which components contained in the first flow are separately introduced, (See FIG. 1).

And a reactor 10 connected to the pipeline and having an oxidative dehydrogenation reaction. The mixing unit may further include a mixing unit for mixing the components included in the first flow before the mixture flows into the reactor (see FIG. 1).

A gas separation apparatus comprising at least one of a solvent absorption tower 21 and a degassing tower 22 for separating a C4 mixture containing butadiene obtained from the reactor 10 from a gas product, (See FIG. 1).

The apparatus for separating and recovering the solvent including the solvent recovery column 23, the high boiling point elimination column 24 and the solvent purification column 25 and the recovered butadiene were purified at a high purity level by using refining apparatuses for obtaining high purity butadiene. And a butadiene refining tower 26 (see FIG. 1).

In the meantime, the butadiene producing apparatus of the present invention is capable of re-introducing a second stream 40 containing at least one of nitrogen (N ₂ ) and carbon dioxide (CO ₂ ) out of the gas products separated from the gas separating apparatus into the reactor And an exhaust line for discharging the third flow 50 including the purge to the outside of the system (see FIG. 1).

Further, a quenching device including a quenching tower 60 for cooling the reaction product obtained from the reactor between the reactor and the gas separation device, a compressor 70 for compressing the reaction product, A dehydrator for removing water contained in the reaction product, and the like.

Butadiene manufacturing process

First, a first flow containing C4 oil, steam, oxygen (O ₂ ), and nitrogen (N ₂ ) is introduced into the reactor to advance the oxidative dehydrogenation reaction.

The C 4 fraction may be C4 Raffinate-1, 2, 3 remaining after separating the useful compound from the C4 mixture produced by naphtha cracking, and means C4 which can be obtained through ethylene dimerization It is possible to do. In one embodiment of the present invention, the C4 fraction is selected from the group consisting of n-butane, trans-2-butene, cis-2-butene, (1-butene), or a mixture of two or more thereof.

The steam or nitrogen (N ₂ ) is a diluent gas which is injected for the purpose of preventing the coking of the catalyst and eliminating the reaction heat while reducing the risk of explosion of the reactant in the oxidative dehydrogenation reaction.

On the other hand, the oxygen (O ₂ ) reacts with C4 oil as an oxidant to cause a dehydrogenation reaction.

In one embodiment of the invention, the first stream 30 is a stream in which C4 oil, steam, oxygen (O ₂ ), and nitrogen (N ₂ ) are introduced into the reactor via respective individual pipelines have.

Meanwhile, in another embodiment of the present invention, the first flow 30 is branched in one pipeline in which C4 oil, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) Wherein the components contained in the first stream are passed through a plurality of individual pipelines separately fed and then mixed in the one pipeline or mixed by a mixing device located in front of the reactor, .

In an embodiment of the present invention, the C4 oil, steam, oxygen, and nitrogen contained in the first flow may be introduced into the pipeline in a gaseous state, and the gas may be preheated to a temperature favorable for the oxidative dehydrogenation reaction It is possible.

In an embodiment of the present invention, the catalyst to be packed in the reactor is not particularly limited as long as it can produce butadiene by oxidative dehydrogenation reaction of C4 oil, for example, a ferrite catalyst or a bismuth molybdate catalyst .

In one embodiment of the present invention, the catalyst may be a bismuth molybdate catalyst, and the bismuth molybdate catalyst may be one selected from the group consisting of bismuth, molybdenum, and cobalt Or more, and the bismuth molybdate catalyst may be a multicomponent bismuth molybdate catalyst. However, the kind and amount of the reaction catalyst may vary depending on the specific conditions of the reaction.

In one embodiment of the present invention, the reactor 10 is not particularly limited as long as the oxidative dehydrogenation reaction can proceed. For example, a tubular reactor, a shaping reactor, or a fluidized bed reactor. As another example, the reactor may be a stationary phase reactor, a stationary phase shell-and-tube reactor, or a plate reactor.

As described above, when the first stream 30 containing C4 oil, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) flows into the reactor 10 filled with the catalyst, the oxidative dehydrogenation reaction proceeds . The oxidative dehydrogenation reaction is an exothermic reaction and the main reaction formula is as shown in the following reaction formula 1 or 2.

Scheme 1

C ₄ H ₈ + 1 / 2O ₂ → C ₄ H ₆ + H ₂ O

Scheme 2

C ₄ H ₁₀ + O ₂ ? C ₄ H ₆ + 2H ₂ O

Butadiene is produced by removing hydrogen of butane or butene by the oxidative dehydrogenation reaction. The oxidative dehydrogenation reaction is accompanied by a side reaction in addition to the main reaction as in the above formula (1) or ( ₂ ), and due to the side reaction, a low boiling point and a water-soluble byproduct such as carbon monoxide (CO), carbon dioxide (CO ₂ ), acetylenes or carbonyls, A side reaction product including high boiling point by-products such as phenol and coumarin can be produced. The side reaction products should be separated and discharged to the outside of the system in such a way that continuous accumulation does not occur in the process.

On the other hand, the C4 mixture containing the butadiene obtained from the reactor can be further subjected to post-treatment to obtain high purity butadiene. The post-treatment process may include a quenching step using a plurality of quenching towers, a compression step using a compressor, a dewatering step using a dewatering device, a gas separation step using a gas separation device, a solvent separation, And a purification step using a purification tower.

Quenching step

In one embodiment of the present invention, the reaction product obtained from the reactor can be subjected to a quenching step.

The reaction product obtained from the reactor may be in the form of a hot gas and therefore needs to be cooled before being fed to the gas separation unit.

The cooling method used in the quenching step is not particularly limited. For example, a cooling method in which the cooling solvent and the reaction product are brought into direct contact may be used, or a cooling method in which the cooling solvent and the reaction product are indirectly contacted may be used.

Dehydration step

In one embodiment of the present invention, the reaction product obtained from the reactor may further comprise a dehydration step of removing moisture.

If water remains in the reaction product, there is a possibility that the apparatus may be corroded by moisture in the step of absorption, separation and purification of the solvent, accumulation of impurities in the solvent, and so on.

The dehydration method in the dehydration step is not particularly limited. The dehydrating means used in the dewatering step is not particularly limited, but may be a drying agent (moisture adsorbent) such as calcium oxide, calcium chloride, and molecular sieve. The molecular sieve of the dehydrating means may be advantageous in terms of easiness of regeneration, ease of handling, and the like.

Compression stage

In one embodiment of the present invention, the reaction product obtained from the reactor may comprise a compression step before it is fed to the solvent absorption tower.

The reactor for the oxidative dehydrogenation reaction is operated at a low pressure to improve the conversion and selectivity, and the solvent absorption tower in the gas separation step is operated at a high pressure to increase the absorption efficiency of the C4 mixture containing butadiene.

Therefore, the reaction product obtained from the reactor must be compressed to a high pressure so that the absorption process in the absorption tower can proceed smoothly before being supplied to the absorption tower.

The step may be performed in a compressor, and in an embodiment of the present invention, the compressor may include a heat exchanger. In another embodiment of the present invention, the heat exchanger may be a multi-stage heat exchanger.

Gas separation step

In one embodiment of the present invention, the reaction product obtained from the reactor is contacted with an absorption solvent in a solvent absorption tower, so that only C4 mixture containing butadiene is selectively absorbed into the absorption solvent, and other gas products are separated Remove.

Specifically, when the reaction product obtained from the reactor is countercurrently contacted with the absorption solvent in the absorption tower, the C4 mixture containing butadiene is selectively absorbed by the absorption solvent, and the remaining gaseous product passes through the top of the absorption tower It goes out.

The type of the absorption tower is not particularly limited, and may be, for example, a packed tower, a wetted wall tower, a spray tower, a cyclone scrubber, a bubble column, a bubble stirring tank, a short tower (bubble column tower,

The absorption solvent may be an absorption solvent commonly used in the art, for example, C6 to C10 saturated hydrocarbons, C6 to C8 aromatic hydrocarbons or amide compounds, and the like.

The absorption solvent may also be selected from the group consisting of dimethylformamide (DMF), methylpyrrolidone (NMP), acetonitrile (ACN), dimethylacetamide (DMA), dimethylsulfoxide dimethyl sulfoxide (DMSO), acetonitrile (ACN), vinylcyclohexane, toluene, benzene, xylene, styrene, octane, octene, may be one or a mixture of two or more selected from the group consisting of octene, ethylcyclohexene, nonane, nonene and furfural.

Meanwhile, in one embodiment of the present invention, the gas product discharged through the pipe through the top of the absorption tower is divided into a second flow 40 and a third flow 50 (see FIG. 1).

The second stream may be a condensed stream comprising at least one selected from the group consisting of nitrogen and carbon dioxide, circulated along the inner circulation line and re-introduced into the reactor. The second flow may further contain unreacted raw materials and butadiene in addition to nitrogen (N ₂ ), carbon dioxide (CO ₂ ), and the carbon dioxide contained in the second flow may be recycled into the reactor through internal circulation, It can act as a mild oxidant or a diluting gas for the oxidative dehydrogenation reaction.

On the other hand, the third flow is discharged as a purge stream out of the system through a discharge line separate from the second flow. The third flow may further include nitrogen (N ₂ ), carbon dioxide (CO ₂ ), unreacted raw materials, and butadiene.

Meanwhile, in one embodiment of the present invention, the absorption solvent is used to selectively absorb only the C4 mixture including butadiene, but it is also possible to dissolve a part of the gas such as nitrogen and carbon dioxide. Accordingly, a degassing step for removing gas such as nitrogen and carbon dioxide may be further performed, and the degassing step may proceed in the degassing tower.

The degassing method in the degassing step is not particularly limited and may be a conventional method used in the art.

Purification step

In one embodiment of the present invention, the C4 mixture comprising butadiene contained in the absorption solvent is purified to high purity butadiene via a purification step. The purification step includes a solvent recovery / recovery device 23 including a solvent recovery column 23 for separating and recovering the absorption solvent, a high boiling point removal column 24 for removing high boiling point components, a solvent purification column 25, And a butadiene purification column 26 for purifying high purity butadiene (see Fig. 1).

In an embodiment of the present invention, the method for separating and recovering the solvent is not particularly limited, and for example, a distillation separation method may be used. According to the distillation separation method, an absorption solvent in which a C4 mixture containing butadiene is dissolved by a reboiler and a condenser is supplied to a solvent recovery tower, followed by distillation separation. After the distillation separation process, a C4 mixture containing butadiene is extracted from the vicinity of the column top.

The separated absorption solvent is extracted from the column bottom of the solvent recovery column, and the extracted absorption solvent can be supplied again to the shearing process and used again. Since the absorption solvent may contain impurities, a process of removing impurities by a known purification method such as distillation, decantation, sedimentation, contacting with an adsorbent or an ion exchange resin by extracting a part before recycling It can also be done.

In one embodiment of the present invention, the C4 mixture comprising butadiene isolated from the absorption solvent may be fed to a high boiling point removal column for separation of high boiling point components.

In the high boiling point elimination column, a process of removing a high boiling point component (a component having a higher solubility than that of butadiene) proceeds. In the above process, a component having a higher solubility than butadiene is dissolved in a solvent. The solvent may be discharged from the bottom of the column and transferred to the solvent purification column.

On the other hand, the butadiene from which the high boiling point component has been removed can be discharged from the column top of the high boiling point removal column and transferred to the butadiene purification column. In one embodiment of the present invention, the butadiene transferred to the purification column is removed as high purity butadiene by removing the high boiling point and low boiling point components through the purification column.

In one embodiment of the present invention, the final degree of purity of the butadiene obtained through the series of steps is 99.0 to 99.9%.

On the other hand, in the butadiene production process, the amount of net energy required in the butadiene production process can be reduced by utilizing the generated heat generated when the reaction product obtained from the reactor is compressed before being supplied to the solvent absorption tower have.

Energy recycling method in butadiene manufacturing process

In an embodiment of the present invention, a process for producing butadiene using an oxidative dehydrogenation reaction comprises the steps of: a) supplying a reaction product obtained from a reactor to a compressor equipped with a heat exchanger; b) compressing the reaction product in the compressor and supplying it to the solvent absorption tower; And c) passing hot water (HW) or low hot water (LHW) discharged from a heat exchanger provided in the compressor to at least one unit equipped with a heat exchanger. .

First, the reaction product obtained from the reactor is fed to a compressor equipped with a heat exchanger (step a) of the present invention.

In one example of the present invention, the pressure in the reactor may be from 0.01 to 0.3 MPaG, and the pressure of the reaction product discharged from the reactor may be equivalent to the pressure in the reactor.

The reaction product supplied to the compressor is supplied to the solvent absorption tower through the compression process (step b) of the present invention.

The compressor must be capable of compressing the reaction product in a gaseous state at a high temperature to a high pressure, and may be provided with a separate heat exchanger.

The heat exchanger is not particularly limited as long as it is an apparatus for causing heat transfer between a high temperature fluid and a low temperature fluid, and may be, for example, in the form of a pressure vessel.

In an exemplary embodiment, the heat exchanger allows hot fluid to flow into one side and low temperature fluid to the other side, for example, in two divided compartments to allow heat to flow from the hot fluid to the cold fluid, Is discharged in a cooled state than the circular state, and the low-temperature fluid is discharged in a heated state rather than the circular state.

The heat exchanger may be, for example, a multi-stage heat exchanger in which heat exchangers of the same kind are sequentially connected in series.

Meanwhile, the pressure in the solvent absorption tower may be 0.1 MPaG to 5 MPaG as a high pressure for increasing the absorption efficiency, and the reaction product is compressed or multi-stage compressed to a level equivalent to the pressure in the solvent absorption tower in the compressor, .

Meanwhile, the compression heat may be generated in the compression process, and the compressed heat is transferred to the refrigerant circulating through the heat exchanger provided in the compressor. The refrigerant circulating through the heat exchanger is not particularly limited, but may be, for example, water (H ₂ O).

In an embodiment of the present invention, the refrigerant is water, and the water discharged from the heat exchanger by receiving the compressed heat generated in the compression process is hot water (HW) having a temperature of 90 ° C or higher, It can be low hot water (LHW) with temperature.

As described above, the hot water (HW) or the low hot water (LHW) discharged from the heat exchanger provided in the compressor is used as a heat source for supplying heat to the device unit by passing through at least one device unit equipped with a heat exchanger (Step c).

Individual unit units that require energy in the butadiene production process include equipment necessary for the process of producing butadiene by an oxidative dehydrogenation reaction, such as reactor 10, quench tower 60, compressor 70, absorption tower 21 ), A deaerator column 22, a solvent recovery column 23, a high boiling point removal column 24, a solvent purification column 25, a butadiene purification column 26 and heat exchangers 91 and 92, Preferably, the device unit of the present invention may be one or more selected from the group consisting of hot water generators 81 and 82, a gas product heater 83 and a butadiene refining tower emitter 84. Each of the device units may include heat exchangers 91 and 92, respectively. 2 and 3, the heat exchangers 91 and 92 may be a combination of a heat exchanger and a drum (DRUM), or may be a heat exchanger in which the flow of the outlet has a gas phase and a liquid phase at the same time. The heat exchanger (91, 92) can further cool the gaseous product after hot water production and can perform removal of a small amount of water that can be generated.

That is, the hot water or the low hot water discharged from the heat exchanger provided in the compressor can be supplied to the device unit in the butadiene production process requiring heat as a heat source. Accordingly, the amount of steam to be separately applied to the in-process unit requiring the heat can be reduced, thereby reducing the amount of net energy required in the process. Therefore, the economical efficiency of the butadiene production process can be improved.

As described above, according to the energy recycling method in the butadiene production process according to the present invention, the compressed heat generated when the reaction product is compressed to supply the reaction product to the absorption tower can be recovered in a process requiring heat energy By supplying to the individual unit, the amount of net energy required in the process can be reduced, thereby improving the economical efficiency of the butadiene production process.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for illustrating the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Example  One

In the butadiene production process using the oxidative dehydrogenation reaction, a gas product recirculated to the reactor was heated in the top of the solvent absorption tower using the compressed heat generated in the compressor as shown in FIG. Since the temperature of the gaseous product of the top of the solvent absorption tower corresponds to the range of 10 to 50 ° C and must be 100 ° C or more when it is put back into the reactor, the steam is generated by using the hot water or low- And reduced usage. The amount of heat recovered by the hot water generators 81 and 82 was 0.15 Gcal / BD ton. When all of them were utilized in the gas product heater 83, the temperature of the gas product was 90 ° C (see Table 1).

Calories (Gcal / BD ton) utility HW generator 81 0.11 Hot water HW generator 82, 0.04 Hot water Gas product burners (83) 0.15 Hot water

Example  2

In the butadiene production process using the oxidative dehydrogenation reaction, as shown in FIG. 3, the heat of compression was supplied to the butadiene refining tower using a compression heat generated in the compressor. The butadiene refining tower batch was operated at a temperature of 100 ° C or lower and hot water or low hot water produced using the above-mentioned compressed heat was used as a heat source. The amount of heat recovered by the hot water generators 81 and 82 was 0.15 Gcal / BD ton, which was utilized for the butadiene refining tower 84 to reduce steam consumption (see Table 2).

Calories (Gcal / BD ton) utility HW generator 81 0.11 Hot water HW generator 82, 0.04 Hot water Butadiene refining tower (84) 0.15 Hot water

Comparative Example  One

Butadiene was produced in the same manner as in Example 1 except that the compressed heat generated in the compressor was not used in the butadiene production process using the oxidative dehydrogenation reaction. On the other hand, additional steam and cooling water were further added to heat the gas product recycled to the reactor from the top of the solvent absorption tower (see Table 3).

Heat exchanger name Calories (Gcal / BD ton) utility HW generator 81 0.11 Cooling water HW generator 82, 0.04 Cooling water

Compressed heat generated when compressing the reaction product according to the present invention can be recovered by heating the gas product heater 83 or the butadiene refiner, which is an individual unit in the process requiring heat energy, It can be confirmed that the amount of net energy required in the process can be reduced when it is supplied to the tower remover 84.

10: Reactor
21: absorption tower 22: degassing tower
23: Solvent recovery column 24: High boiling point removal column
25: Solvent refining tower 26: Butadiene refining tower
30: First flow
40: second flow
50: the third flow
60: rapid heating tower
70, 70-1, 70-2: compressor
81, 82: HW generator
83: Gas product heater 84: Made by butadiene refining tower

Claims (6)

In the butadiene production process using an oxidative dehydrogenation reaction,
a) feeding the reaction product obtained from the reactor to a compressor equipped with a heat exchanger;
b) compressing the reaction product in the compressor and supplying it to the solvent absorption tower; And
c) passing hot water (HW) or low hot water (LHW) discharged from a heat exchanger provided in the compressor to at least one unit equipped with a heat exchanger.
The method according to claim 1,
Wherein the pressure in the reactor is in the range of 0.01 to 0.3 MPaG.
The method according to claim 1,
Wherein the pressure in the solvent absorption tower is 0.1 to 5 MPaG.
The method according to claim 1,
Wherein the step b) is a multi-stage compression process.
The method according to claim 1,
Wherein the heat exchanger is a multi-stage heat exchanger in which one or more same-kind heat exchangers are sequentially connected.
The method according to claim 1,
Wherein the device unit is selected from the group consisting of a hot water generator, a gas product heater, and a butadiene tablet column reservoir.

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