CN114163291A - Propane dehydrogenation reaction product separation system and method - Google Patents
Propane dehydrogenation reaction product separation system and method Download PDFInfo
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- CN114163291A CN114163291A CN202010948444.3A CN202010948444A CN114163291A CN 114163291 A CN114163291 A CN 114163291A CN 202010948444 A CN202010948444 A CN 202010948444A CN 114163291 A CN114163291 A CN 114163291A
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- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 182
- 239000001294 propane Substances 0.000 title claims abstract description 91
- 238000006356 dehydrogenation reaction Methods 0.000 title claims abstract description 89
- 239000007795 chemical reaction product Substances 0.000 title claims abstract description 67
- 238000000926 separation method Methods 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 32
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 113
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 112
- 238000011084 recovery Methods 0.000 claims abstract description 86
- 238000010992 reflux Methods 0.000 claims abstract description 71
- 239000007789 gas Substances 0.000 claims abstract description 55
- 239000001257 hydrogen Substances 0.000 claims abstract description 40
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 40
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000463 material Substances 0.000 claims abstract description 10
- 239000000047 product Substances 0.000 claims description 115
- 239000012071 phase Substances 0.000 claims description 54
- 239000007791 liquid phase Substances 0.000 claims description 45
- 238000001816 cooling Methods 0.000 claims description 40
- 238000007599 discharging Methods 0.000 claims description 16
- 239000012535 impurity Substances 0.000 claims description 13
- 238000001035 drying Methods 0.000 claims description 10
- 238000007701 flash-distillation Methods 0.000 claims description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 8
- 230000006835 compression Effects 0.000 claims description 8
- 238000007906 compression Methods 0.000 claims description 8
- 239000001569 carbon dioxide Substances 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 4
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims 1
- 239000012263 liquid product Substances 0.000 claims 1
- 239000003507 refrigerant Substances 0.000 abstract description 7
- 230000008901 benefit Effects 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 21
- 238000009833 condensation Methods 0.000 description 21
- 230000005494 condensation Effects 0.000 description 21
- 238000005057 refrigeration Methods 0.000 description 8
- 238000001704 evaporation Methods 0.000 description 7
- 230000008020 evaporation Effects 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 239000000126 substance Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 4
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000002745 absorbent Effects 0.000 description 3
- 239000002250 absorbent Substances 0.000 description 3
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- 238000012986 modification Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002151 riboflavin Substances 0.000 description 2
- PPASLZSBLFJQEF-RKJRWTFHSA-M sodium ascorbate Substances [Na+].OC[C@@H](O)[C@H]1OC(=O)C(O)=C1[O-] PPASLZSBLFJQEF-RKJRWTFHSA-M 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 239000004261 Ascorbyl stearate Substances 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 1
- 239000004283 Sodium sorbate Substances 0.000 description 1
- 239000000728 ammonium alginate Substances 0.000 description 1
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- 239000006227 byproduct Substances 0.000 description 1
- 239000000648 calcium alginate Substances 0.000 description 1
- 235000010410 calcium alginate Nutrition 0.000 description 1
- 239000011692 calcium ascorbate Substances 0.000 description 1
- 239000004303 calcium sorbate Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000000542 fatty acid esters of ascorbic acid Substances 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- -1 polypropylene, propylene Polymers 0.000 description 1
- 239000000737 potassium alginate Substances 0.000 description 1
- 235000010408 potassium alginate Nutrition 0.000 description 1
- 239000004302 potassium sorbate Substances 0.000 description 1
- 239000000770 propane-1,2-diol alginate Substances 0.000 description 1
- 235000010409 propane-1,2-diol alginate Nutrition 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000004149 tartrazine Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/06—Flash distillation
- B01D3/065—Multiple-effect flash distillation (more than two traps)
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a propane dehydrogenation reaction product separation system which is sequentially provided with at least one stage of heat exchange flash unit, a carbon three recovery tower and a reflux tank along the input direction of a propane dehydrogenation reaction product, wherein the heat exchange flash unit is sequentially provided with a first heat exchanger and a flash tank along the input direction of the propane dehydrogenation reaction product, the carbon three recovery tower is communicated with the reflux tank to form a circulation loop, and a condenser is arranged on an input pipeline from the carbon three recovery tower to the reflux tank. The invention further provides a separation method of the propane dehydrogenation reaction product. By adopting the propane dehydrogenation reaction product separation system and the method thereof, the loss of carbon three in the hydrogen-rich gas can be reduced, the consumption of high-grade refrigerant is reduced, the material can flow automatically through reasonable equipment arrangement, a low-temperature pump with high price is omitted, the investment is reduced, the occupied area is reduced, and the economic benefit of the propane dehydrogenation device is increased.
Description
Technical Field
The invention belongs to the technical field of light hydrocarbon separation, relates to a separation system and a separation method for a propane dehydrogenation reaction product, and particularly relates to a separation system and a separation method for improving the recovery rate of carbon III in the separation process of the propane dehydrogenation reaction product.
Background
Propylene is second only to ethylene, an important petrochemical feedstock. The method is mainly used for producing dozens of petrochemical products and raw materials such as polypropylene, propylene oxide, acrylic acid, acrylonitrile, alkylate oil, high-octane gasoline blending materials and the like. Propane dehydrogenation technology is an important source of propylene.
The propane dehydrogenation technology is to obtain propylene by catalytic dehydrogenation with propane as a raw material. The propane dehydrogenation reaction product mainly contains hydrogen and carbon three, and also contains a small amount of methane, carbon two, nitrogen and the like. Methane and part of the carbon dioxide come from the by-products of propane dehydrogenation, part of the carbon dioxide comes from the raw material propane, and nitrogen comes from the regeneration process.
Because the propane dehydrogenation reaction product contains a large amount of hydrogen, the separation of hydrogen and carbon three needs to be realized at a cryogenic temperature. After the hydrogen-rich gas is reheated, pure hydrogen products are obtained through PSA purification, and tail gas absorbed by PSA is used as fuel gas to be burned. The carbon three contained in the hydrogen-rich gas is reduced, the recovery rate of the carbon three is improved, and the economy of the propane dehydrogenation device can be improved.
CN107954815A and CN107954819A use membrane separation to process the propane dehydrogenation reaction product, absorb carbon three in the non-permeable gas in an absorption tower by using a toluene-rich absorbent, and desorb the carbon three-component-absorbing absorbent in a desorption tower. The patent uses a membrane separation method and an absorption desorption method at the same time, and the process is complex. CN108456128A is a separation process by using refrigerant and solvent for absorption. CN108713052A used benzene as absorbent. The larger the amount of hydrogen in the propane dehydrogenation reaction product, the more solvent will be taken away. Therefore, the absorption method is adopted, the solvent supplement amount is large, and the cost of propane dehydrogenation is increased. If the solvent is to be recovered from the hydrogen-rich gas, more additional equipment is required, and additional energy consumption is increased.
CN103159582B, CN203187601U, CN104296499B, CN108036583A and CN207751220U adopt a joint expander for refrigeration, and are improved on the basis of the refrigeration process of the expander. CN103159582B, CN203187601U, CN108036583A and CN207751220U mainly improve the design of a heat exchange channel, and CN104296499B adopts a parallel double expansion machine. In these schemes, there is still room for further reduction in carbon three lost in the hydrogen-rich gas.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a propane dehydrogenation reaction product separation system and method thereof, which can significantly reduce the loss of carbon-three in hydrogen-rich gas, reduce the cold consumption, and increase the economic efficiency of a propane dehydrogenation device.
In order to achieve the above object, a first aspect of the present invention provides a propane dehydrogenation reaction product separation system, which is sequentially provided with at least one stage of heat exchange flash unit, a carbon recovery tower and a reflux tank along an input direction of a propane dehydrogenation reaction product, wherein the heat exchange flash unit is sequentially provided with a first heat exchanger and a flash tank along the input direction of the propane dehydrogenation reaction product, the carbon recovery tower and the reflux tank are communicated to form a circulation loop, and an input pipeline from the carbon recovery tower to the reflux tank is provided with a condenser.
Preferably, the separation system further comprises a compression device and a drying and impurity removing device, and the compression device and the drying and impurity removing device are sequentially arranged along the material flow direction and are both arranged at the material flow upstream of the heat exchange flash unit.
Preferably, a second heat exchanger is arranged on an input pipeline from the flash tank to the carbon recovery tower.
Preferably, one end of the input pipeline from the flash tank to the carbon three recovery tower is communicated with the top of the flash tank, and the other end of the input pipeline from the flash tank to the carbon three recovery tower is communicated with the lower part of the tower body of the carbon three recovery tower.
Preferably, one end of an input pipeline from the carbon three recovery tower to the reflux tank is communicated with the top of the carbon three recovery tower, and the other end of the input pipeline from the carbon three recovery tower to the reflux tank is communicated with the tank body of the reflux tank. Preferably, a reflux pump is arranged on an input pipeline from the reflux tank to the carbon recovery tower.
Preferably, one end of an input pipeline from the reflux tank to the carbon three recovery tower is communicated with the bottom of the reflux tank, and the other end of the input pipeline from the reflux tank to the carbon three recovery tower is communicated with the upper part of a tower body of the carbon three recovery tower. The second aspect of the present invention provides a method for separating a product of a propane dehydrogenation reaction, which is used to increase the recovery rate of carbon III in the separation process of the product of the propane dehydrogenation reaction, and the separation system for the product of the propane dehydrogenation reaction comprises the following steps:
1) cooling, condensing and flashing the propane dehydrogenation reaction product for at least one time to form a first gas-phase product and a first liquid-phase carbon-three product, and discharging the first liquid-phase carbon-three product;
2) inputting the first gas-phase product into a carbon-three recovery tower, separating to form a second gas-phase product and a second liquid-phase carbon-three product, and discharging the second liquid-phase carbon-three product;
3) and cooling and condensing the second gas-phase product, inputting the second gas-phase product into a reflux tank for separation to form hydrogen-rich gas and a liquid-phase product, discharging the hydrogen-rich gas, refluxing the liquid-phase product to a carbon-III recovery tower for adsorbing carbon III in the first gas-phase product, and discharging.
Preferably, in the step 1), the input pressure of the propane dehydrogenation reaction product is 0.5-2.0 MPaG. More preferably, the input pressure of the propane dehydrogenation reaction product is 1.0-1.5 MPaG.
Preferably, in the step 1), the input temperature of the propane dehydrogenation reaction product is 35-55 ℃. More preferably, the input temperature of the propane dehydrogenation reaction product is 40-48 ℃.
Preferably, in the step 1), the propane dehydrogenation reaction product is cooled and condensed by a first heat exchanger, and the temperature of an outlet of the first heat exchanger is-60-10 ℃.
Preferably, in the step 1), the propane dehydrogenation reaction product is flashed by a flash tank, wherein the flash temperature of the flash tank is-80-20 ℃. More preferably, the flash temperature of the flash tank is-60 to 10 ℃.
More preferably, in step 1), the flash temperature of the flash tank is gradually decreased in a plurality of stages arranged along the input direction of the propane dehydrogenation reaction product.
Preferably, in the step 1), the first liquid-phase carbon-three product is discharged from the bottom of the flash tank and then is input into the deethanizer. The deethanizer separates the first liquid phase carbone three product into carbon two and carbon three.
Preferably, in the step 2), the first gas-phase product can be directly input into the carbon-three recovery tower or input into the carbon-three recovery tower after being cooled and condensed by the second heat exchanger. More preferably, the temperature at the outlet of the second heat exchanger is-80 to-35 ℃.
Preferably, in the step 2), the first gas-phase product is input through the lower part of the body of the carbon-three recovery tower, and the second gas-phase product is output through the top of the carbon-three recovery tower.
Preferably, in the step 2), the second liquid-phase carbon-three product is discharged from the bottom of the carbon-three recovery tower and then is input into the deethanizer.
Preferably, in the step 3), the second gas-phase product is cooled and condensed by a condenser, and the temperature of the outlet of the condenser is-110 to-35 ℃.
Preferably, in step 3), the hydrogen-rich gas is discharged through the top of the reflux drum.
Preferably, in the step 3), the hydrogen-rich gas is discharged from the reflux tank, and then the cold energy is recovered and conveyed to a battery limit area.
More preferably, the recovered cold energy is the cold energy recovered in the heat exchanger directly or after being expanded by an expander.
Preferably, in the step 3), the output temperature of the hydrogen-rich gas is-120 to-90 ℃. More preferably, the output temperature of the hydrogen-rich gas is-110 to-98 ℃.
Preferably, in step 3), the liquid phase product contains 20 to 80% of carbon dioxide. The liquid phase product is contacted with the first gas phase product and is used for adsorbing the carbon III in the first gas phase product, so that the effect of reducing the content of the carbon III in the hydrogen-rich gas is achieved. The% of carbon two is mol%.
Preferably, in the step 3), the liquid-phase product is refluxed to the carbon recovery tower from the reflux tank in a self-flowing mode or a pressurizing mode by using a reflux pump.
More preferably, when the liquid-phase product is refluxed in a self-flowing mode, the placing position of the reflux tank is higher than the top of the carbon three-recovery tower, and the placing position of the condenser is higher than the feeding hole of the reflux tank.
In the step 1) or 3), the cold energy source of the cooling condensation comprises but is not limited to refrigerant refrigeration, process material cold energy recovery and expander refrigeration. The method is suitable for propane dehydrogenation separation flow of expansion machine refrigeration and propane dehydrogenation separation flow of refrigerant refrigeration.
In the method, the carbon three refers to propane and propylene. The carbon two refers to ethane and ethylene. The deethanizer is a rectification column for deethanization, which is conventionally used.
As described above, the present invention has the following advantageous effects:
(1) in the separation process of the propane dehydrogenation reaction product, a first gas-phase product obtained by flash evaporation of the flash tank is input into a carbon-III recovery tower, a second gas-phase product obtained after separation of the carbon-III recovery tower is cooled and condensed and then is input into a reflux tank for separation, and hydrogen-rich gas and a liquid-phase product are obtained. Wherein, the liquid phase product is rich in 20-80% of carbon two and is sent back to the top of the carbon three recovery tower to be used as reflux, and when the liquid phase product rich in carbon two descends in the tower, the liquid phase product rich in carbon two is contacted with the first gas phase product rich in carbon three to absorb carbon three, so that the loss of carbon three in the hydrogen-rich gas is reduced, and the effect of reducing the content of carbon three in the hydrogen-rich gas is achieved.
(2) In the invention, as part of the carbon III in the first gas phase product is absorbed by the carbon II and is reduced to the same temperature, the required amount of the condensed carbon III is reduced. Compared with the method without the carbon-three recovery tower, the method has the advantages that the required refrigerant load is reduced, and the consumption of high-grade refrigerant is reduced, so that the effect of reducing energy consumption is achieved.
(3) The invention can adopt a low-temperature reflux pump to send the liquid-phase product in the reflux tank into the carbon recovery tower, and can also lead the material to flow automatically through reasonable equipment arrangement, thereby saving a low-temperature pump with high price, reducing the investment and the occupied area.
Drawings
FIG. 1 is a flow chart showing the separation process of the product of the propane dehydrogenation reaction in comparative example 1.
FIG. 2 is a flow chart showing the separation process of the product of propane dehydrogenation reaction in example 1.
Fig. 3 is a flow chart showing the separation process of the product of propane dehydrogenation reaction in comparative example 2.
FIG. 4 is a flow chart showing the separation process of the product of propane dehydrogenation reaction in example 2.
Reference numerals
1 first heat exchanger
2 second heat exchanger
3 flash tank
4-carbon three-recovery tower
5 refluxing tank
6 condenser
7 reflux pump
8 compression device
9 drying and impurity removing device
Detailed Description
The present invention is further illustrated below with reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It should be understood that the processing equipment or devices not specifically mentioned in the following examples are conventional in the art; all pressures refer to relative pressures.
Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
The invention provides a propane dehydrogenation reaction product separation system, as shown in figure 2 or 4, at least one stage of heat exchange flash unit, a carbon recovery tower and a reflux tank are sequentially arranged along the input direction of a propane dehydrogenation reaction product, the heat exchange flash unit is sequentially provided with a first heat exchanger and a flash tank along the input direction of the propane dehydrogenation reaction product, the carbon recovery tower and the reflux tank are communicated to form a circulation loop, and a condenser is arranged on an input pipeline from the carbon recovery tower to the reflux tank.
In the propane dehydrogenation reaction product separation system provided by the invention, similar to the prior art, when the heat exchange flash units are in multiple stages, the heat exchange flash units of each stage are connected in series, specifically shown in fig. 1, 3 and 4. And the heat exchange flash units at all stages are sequentially increased along the stage number of the input direction of the propane dehydrogenation reaction product. In the same way, the first heat exchanger and the flash tank in each stage of the heat exchange flash unit are sequentially increased along the input direction of the propane dehydrogenation reaction product.
In the separation system of the propane dehydrogenation reaction product provided by the invention, as shown in fig. 2 or 4, the separation system further comprises a compression device and a drying and impurity removing device, wherein the compression device and the drying and impurity removing device are sequentially arranged along the material flow direction and are both arranged at the material flow upstream of the heat exchange flash unit.
Specifically, the compression device is a compressor which is conventionally used for propane dehydrogenation reaction products in the chemical industry field, and can compress the propane dehydrogenation reaction products.
Specifically, the drying and impurity removing device is a drying and impurity removing device which is conventionally used for compressing a propane dehydrogenation reaction product in the chemical field, and can be used for drying the compressed propane dehydrogenation reaction product and removing impurities in the product.
In the propane dehydrogenation reaction product separation system provided by the invention, as shown in fig. 2, a second heat exchanger is arranged on an input pipeline from the flash tank to the carbon recovery tower. The second heat exchanger can cool and condense the first gas phase product output by the heat exchange flash unit and then input the first gas phase product into the carbon recovery tower.
In the propane dehydrogenation reaction product separation system provided by the invention, as shown in fig. 2 or 4, one end of an input pipeline from the flash tank to the carbon recovery column is communicated with the top of the flash tank, and the other end of the input pipeline from the flash tank to the carbon recovery column is communicated with the lower part of the tower body of the carbon recovery column. So that the first gas phase product flows into the carbon recovery tower from the flash tank.
In the propane dehydrogenation reaction product separation system provided by the invention, as shown in fig. 2 or 4, one end of an input pipeline from the carbon three recovery tower to the reflux tank is communicated with the top of the carbon three recovery tower, and the other end of the input pipeline from the carbon three recovery tower to the reflux tank is communicated with the tank body of the reflux tank. Facilitating the second gas phase product to flow from the carbon three recovery tower into the reflux tank.
The flash tank is a flash tank which is conventionally used in the field of chemical industry.
In the propane dehydrogenation reaction product separation system provided by the invention, as shown in fig. 4, a reflux pump is arranged on an input pipeline from the reflux tank to the carbon recovery tower. And providing power for the liquid phase product to flow back to the carbon recovery tower from the reflux tank.
The reflux pump is a pump which is conventionally used in the chemical field.
In the propane dehydrogenation reaction product separation system provided by the invention, as shown in fig. 2 or 4, one end of an input pipeline from the reflux tank to the carbon three recovery tower is communicated with the bottom of the reflux tank, and the other end of the input pipeline from the reflux tank to the carbon three recovery tower is communicated with the upper part of a tower body of the carbon three recovery tower. The liquid phase product is convenient to flow back to the carbon recovery tower from the reflux tank.
The first heat exchanger, the second heat exchanger and/or the condenser are heat exchangers conventionally used in the chemical industry, and the types of the heat exchangers include, but are not limited to, shell-and-tube heat exchangers, wound-tube heat exchangers and plate-fin heat exchangers. The heat exchange process of the heat exchanger can be that one hot stream and one cold stream exchange heat with each other, or can also be that a plurality of hot streams and a plurality of cold streams exchange heat with each other.
The carbon three recovery tower is a plate tower or a packed tower in the chemical field.
Comparative example 1
As shown in fig. 1, the propane dehydrogenation reaction product is fed into a two-stage heat exchange flash unit, cooled and condensed by a first-stage first heat exchanger, fed into a first-stage flash tank for flash evaporation, and the formed gas phase product is discharged from the top of the first-stage flash tank, and the formed liquid phase product is sent to a deethanizer. The propane dehydrogenation reaction product can be compressed and dried to remove impurities.
And the gas-phase product discharged from the top of the first-stage flash tank is cooled and condensed by a second-stage first heat exchanger and then is input into a second-stage flash tank for flash evaporation, the formed liquid-phase product is sent to a deethanizer, and finally a gas-phase product is formed: rich in hydrogen. And the hydrogen-rich gas is discharged from the top of the second-stage flash tank, and is conveyed to a battery limit after cold energy is directly recovered or is recovered after being refrigerated by an expansion machine.
Example 1
As shown in fig. 2, the propane dehydrogenation reaction product is input into a first-stage heat exchange flash unit, cooled and condensed by a first-stage first heat exchanger, and then input into a first-stage flash tank for flash evaporation, so that a first gas-phase product is formed and discharged from the top of the first-stage flash tank, and a formed first liquid-phase carbon-three product is input into a deethanizer. The propane dehydrogenation reaction product can be compressed and dried to remove impurities.
And cooling and condensing the first gas-phase product to-80 ℃ through a second heat exchanger, inputting the cooled and condensed first gas-phase product into a tower kettle of a carbon three recovery tower for separation, discharging a second liquid-phase carbon three product from the bottom of the carbon three recovery tower, inputting the discharged second liquid-phase carbon three product into a deethanizer, discharging a second gas-phase product from the top of the carbon three recovery tower, cooling and condensing the second gas-phase product through a condenser, and inputting the cooled and condensed second gas-phase product into a reflux tank. After separation in the reflux tank, the formed hydrogen-rich gas is discharged from the top of the reflux tank, and is conveyed to a battery limit after cold energy is directly recovered or is recovered after refrigeration by an expander; and discharging the formed liquid phase product from the bottom of the reflux tank, automatically flowing back to the top of the carbon three recovery tower, contacting with the second gas phase product, absorbing carbon three in the second gas phase product, discharging from the bottom of the carbon three recovery tower, and inputting into a deethanizer.
In order to realize self-flow, the placing position of the reflux tank is higher than the top of the carbon three-recovery tower, and the placing position of the condenser of the carbon three-recovery tower is higher than the feeding hole of the reflux tank.
The results of the reactions in comparative example 1 and example 1 were compared and the data are shown in table 1. As can be seen from table 1, example 1 has an additional carbon triple recovery column and condenser compared to comparative example 1. The liquid phase product in the reflux tank automatically flows back to the carbon three recovery tower, the process is simple, and a reflux pump is not required to be additionally arranged. Meanwhile, in example 1, the liquid phase product in the reflux drum contains about 46 mol% of carbon two and lighter components, and the liquid phase product enters the carbon three recovery tower, descends and contacts with the ascending second gas phase product to wash off the carbon three in the second gas phase product. In comparison with comparative example 1, the carbon triple loss in the hydrogen rich gas in example 1 was reduced by 18.7 mol%, and the second stage cooling condensation duty was reduced by 0.17 MW. It can be seen by comparison that, by adopting the method of the embodiment 1, not only the carbon loss and the cold consumption are reduced, but also the economic benefit of the propane dehydrogenation device is improved.
TABLE 1 comparison of comparative example 1 and example 1
| Unit of | Comparative example 1 | Example 1 | |
| Flow rate of propane dehydrogenation reaction product | kmol/h | 7250 | 7250 |
| Propane dehydrogenation reaction product pressure | MPaG | 1.5 | 1.5 |
| Propane dehydrogenation reaction product temperature | ℃ | 45 | 45 |
| First stage flash tank temperature | ℃ | -60 | -60 |
| Hydrogen rich gas temperature | ℃ | -110 | -110 |
| Hydrogen rich gas flow | kmol/h | 2805 | 2826 |
| Carbon content of hydrogen-rich gas | mol％ | 0.090 | 0.072 |
| Carbon loss in hydrogen-rich gas | kmol/h | 2.52 | 2.05 |
| Carbon recovery rate | ％ | 99.938％ | 99.950％ |
| First stage cooling condensation load | MW | 31.30(E101) | 31.30(E201) |
| Second stage cooling condensation load | MW | 1.87(E102) | 1.70(E202+E203) |
In the above table 1, E101 is the first-stage first heat exchanger for cooling condensation in comparative example 1; e201 is a first-stage first heat exchanger for cooling and condensing in the embodiment 1; e102 is a second-stage first heat exchanger for cooling and condensing in the comparative example 1; e202 is a second heat exchanger for cooling and condensing in the embodiment 1; e203 is the condenser for cooling and condensing in example 1.
Comparative example 2
As shown in fig. 3, the propane dehydrogenation reaction product is fed into a five-stage heat exchange flash unit, and the propane dehydrogenation reaction product can be compressed and dried to remove impurities. And cooling and condensing the product by a first-stage first heat exchanger, inputting the product into a first-stage flash tank for flash evaporation, sending the formed liquid-phase product to a deethanizer, and discharging the formed gas-phase product through the top of the first-stage flash tank.
Similarly, gaseous product of first order flash tank deck combustion gas is again through second level first heat exchanger cooling condensation after input second level flash tank carries out the flash distillation, again through third level first heat exchanger cooling condensation after input third level flash tank carries out the flash distillation, again through the first heat exchanger cooling condensation of fourth level after input third level flash tank carries out the flash distillation, again through the first heat exchanger cooling condensation of fifth level after input fifth level flash tank carries out the flash distillation, so in proper order cool off condensation and flash distillation step by step, liquid phase product that flash tanks at different levels formed sends the deethanizer, finally form gaseous product: rich in hydrogen. And the hydrogen-rich gas is discharged from the top of the fifth-stage flash tank, and is conveyed to a battery limit after cold energy is directly recovered or is recovered after being refrigerated by an expansion machine.
Example 2
As shown in fig. 4, the propane dehydrogenation reaction product is fed into a four-stage heat exchange flash unit, and the propane dehydrogenation reaction product may be compressed, dried and purified. And cooling and condensing the product by a first-stage first heat exchanger, inputting the product into a first-stage flash tank for flash evaporation, inputting the formed first liquid-phase carbon three product into a deethanizer, and discharging the formed gas-phase product through the top of the first-stage flash tank. Similarly, the gas phase product is input the second level flash tank and is flashed after the first heat exchanger of second level cooling condensation again, and input the third level flash tank and carry out the flash distillation after the first heat exchanger of third level cooling condensation again, and input the fourth level flash tank and flash the evaporation after the first heat exchanger of fourth level cooling condensation again, so cooling condensation and flash distillation step by step in proper order, the third product of first liquid phase carbon that flash tanks at different levels formed inputs the deethanizer, finally forms the gas phase product: the first gas phase product is discharged from the top of the fourth-stage flash tank.
And the first gas-phase product is input into a carbon-III recovery tower for separation, a second liquid-phase carbon-III product is formed and is input into a deethanizer after being discharged from the bottom of the carbon-III recovery tower, and a second gas-phase product is formed and is discharged from the top of the carbon-III recovery tower, and is input into a reflux tank after being cooled and condensed by a condenser. After separation in the reflux tank, the formed hydrogen-rich gas is discharged from the top of the reflux tank, and is conveyed to a battery limit after cold energy is directly recovered or is recovered after refrigeration by an expander; and discharging the formed liquid phase product from the bottom of the reflux tank, pressurizing by a reflux pump, refluxing to the top of the carbon three-phase recovery tower, contacting with the second gas phase product, absorbing carbon three in the second gas phase product, discharging from the bottom of the carbon three-phase recovery tower, and inputting into a deethanizer.
The results of the reactions in comparative example 2 and example 2 were compared and the data are shown in table 2. As can be seen from table 2, example 2 has an additional carbon triple recovery column, condenser and reflux pump compared to comparative example 2.
Meanwhile, in example 2, the liquid phase product in the reflux drum contains about 79 mol% of carbon two and lighter components, and the liquid phase enters a carbon three recovery tower, descends and contacts with the ascending second gas phase product to wash off the carbon three in the second gas phase product. In comparison with comparative example 2, the carbon-three loss in the hydrogen-rich gas in example 2 was reduced by 59.7 mol%, and the fifth stage cooling condensation duty was reduced by 0.35 MW.
It can be seen by comparison that the method of example 2 reduces both the carbon loss and the cold consumption.
TABLE 2 comparison of comparative example 2 and example 2
| Unit of | Comparative example 2 | Example 2 | |
| Flow rate of propane dehydrogenation reaction product | kmol/h | 5916 | 5916 |
| Propane dehydrogenation reaction product pressure | MPaG | 1.0 | 1.0 |
| Propane dehydrogenation reaction product temperature | ℃ | 42 | 42 |
| First stage flash tank temperature | ℃ | 10 | 10 |
| Second stage flash tank temperature | ℃ | -15 | -15 |
| Third stage flash tank temperature | ℃ | -37 | -37 |
| Fourth stage flash tank temperature | ℃ | -55 | -55 |
| Hydrogen rich gas temperature | ℃ | -98 | -98 |
| Hydrogen rich gas flow | kmol/h | 1965 | 2025 |
| Carbon content of hydrogen-rich gas | mol％ | 0.299 | 0.117 |
| Carbon loss in hydrogen-rich gas | kmol/h | 5.88 | 2.37 |
| Carbon recovery rate | ％ | 99.84％ | 99.93％ |
| First stage cooling condensation load | MW | 3.28(E301) | 3.28(E401) |
| Second stage cooling condensation load | MW | 14.51(E302) | 14.51(E402) |
| Third stage cooling condensing load | MW | 4.05(E303) | 4.05(E403) |
| Fourth stage cooling condensation load | MW | 1.52(E304) | 1.52(E404) |
| Fifth stage cooling condensation load | MW | 1.82(E305) | 1.47(E405) |
In the above table 2, E301 is the first-stage first heat exchanger for cooling condensation in comparative example 2; e401 is the first-stage first heat exchanger for cooling and condensing in the embodiment 2; e302 is the second-stage first heat exchanger for cooling and condensing in comparative example 2; e402 is the second-stage first heat exchanger for cooling and condensing in the embodiment 2; e303 is a third-stage first heat exchanger for cooling and condensing in the comparative example 2; e403 is the third-stage first heat exchanger for cooling and condensing in the embodiment 2; e304 is the fourth stage first heat exchanger which is cooled and condensed in comparative example 2; e404 is a fourth-stage first heat exchanger for cooling and condensing in the embodiment 2; e305 is a fifth-stage first heat exchanger for cooling and condensing in the comparative example 2; e405 is the condenser for cooling condensation in example 2.
In conclusion, the invention can reduce the loss of carbon III in the hydrogen-rich gas, reduce the consumption of high-grade refrigerant, lead the material to flow automatically through reasonable equipment arrangement, save a low-temperature pump with high price, reduce the investment, reduce the occupied area and increase the economic benefit of the propane dehydrogenation device. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. The utility model provides a propane dehydrogenation reaction product piece-rate system, its characterized in that is equipped with at least one-level heat transfer flash distillation unit, three recovery towers in carbon (4), reflux drum (5) in proper order along propane dehydrogenation reaction product input direction, heat transfer flash distillation unit is equipped with first heat exchanger (1), flash drum (3) in proper order along propane dehydrogenation reaction product input direction, three recovery towers in carbon (4) are linked together with reflux drum (5) and form circulation circuit, be equipped with condenser (6) on the input pipeline of three recovery towers in carbon (4) to reflux drum (5).
2. The propane dehydrogenation reaction product separation system according to claim 1, wherein the separation system further comprises a compression device (8) and a drying and impurity removing device (9), and the compression device (8) and the drying and impurity removing device (9) are arranged in sequence along the material flow direction and are both arranged upstream of the heat exchange flash unit.
3. The propane dehydrogenation reaction product separation system according to claim 1, wherein the input line from the flash tank (3) to the carbon recovery column (4) is provided with a second heat exchanger (2).
4. The propane dehydrogenation reaction product separation system according to claim 1, wherein a reflux pump (7) is provided on the input line from the reflux drum (5) to the carbon recovery column (4).
5. A propane dehydrogenation reaction product separation method comprises the following steps:
1) cooling, condensing and flashing the propane dehydrogenation reaction product for at least one time to form a first gas-phase product and a first liquid-phase carbon-three product, and discharging the first liquid-phase carbon-three product;
2) inputting the first gas-phase product into a carbon-three recovery tower, separating to form a second gas-phase product and a second liquid-phase carbon-three product, and discharging the second liquid-phase carbon-three product;
3) and cooling and condensing the second gas-phase product, inputting the second gas-phase product into a reflux tank for separation to form hydrogen-rich gas and a liquid-phase product, discharging the hydrogen-rich gas, refluxing the liquid-phase product to a carbon-III recovery tower for adsorbing carbon III in the first gas-phase product, and discharging.
6. The method for separating the propane dehydrogenation reaction product according to claim 5, wherein in the step 1), the propane dehydrogenation reaction product is cooled and condensed by a first heat exchanger, and the temperature of the outlet of the first heat exchanger is-60-10 ℃.
7. The method for separating the product of the propane dehydrogenation reaction according to claim 5, wherein in the step 2), the first gas-phase product is directly fed into a carbon-three recovery tower or fed into the carbon-three recovery tower after being cooled and condensed by a second heat exchanger; the temperature of the outlet of the second heat exchanger is-80 to-35 ℃.
8. The method for separating the product of the propane dehydrogenation reaction according to claim 5, wherein in the step 3), the second gas-phase product is cooled and condensed by a condenser, and the temperature of the outlet of the condenser is-110 to-35 ℃; the liquid phase product contains 20-80% of carbon dioxide.
9. The method for separating a propane dehydrogenation reaction product according to claim 5, wherein in the step 3), the liquid phase product is refluxed from the reflux tank to the carbon recovery column in a self-flowing manner or pressurized by using a reflux pump.
10. The method for separating a product of a propane dehydrogenation reaction according to claim 9, wherein the reflux drum is positioned higher than the top of the carbon recovery column and the condenser is positioned higher than the feed inlet of the reflux drum when the liquid product is refluxed by gravity flow.
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| CN102795956A (en) * | 2012-08-30 | 2012-11-28 | 惠生工程（中国）有限公司 | Method for separating reaction products produced during preparation of propylene by dehydrogenating propane |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102795956A (en) * | 2012-08-30 | 2012-11-28 | 惠生工程（中国）有限公司 | Method for separating reaction products produced during preparation of propylene by dehydrogenating propane |
| CN106316761A (en) * | 2015-06-24 | 2017-01-11 | 中石化广州工程有限公司 | Method for separation of products of reaction for preparation of propylene from propane by dehydrogenation |
| CN108456128A (en) * | 2018-06-05 | 2018-08-28 | 北京恒泰洁能科技有限公司 | A kind of separating technology and system of dehydrogenating propane product gas |
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