CN114702044A - High-efficiency energy-saving caprolactam production method - Google Patents
High-efficiency energy-saving caprolactam production method Download PDFInfo
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- CN114702044A CN114702044A CN202210314147.2A CN202210314147A CN114702044A CN 114702044 A CN114702044 A CN 114702044A CN 202210314147 A CN202210314147 A CN 202210314147A CN 114702044 A CN114702044 A CN 114702044A
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- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 title claims abstract description 132
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- 238000006243 chemical reaction Methods 0.000 claims abstract description 55
- 238000000034 method Methods 0.000 claims abstract description 34
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 103
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 90
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 80
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 80
- 239000007788 liquid Substances 0.000 claims description 63
- 229910021529 ammonia Inorganic materials 0.000 claims description 51
- 230000008707 rearrangement Effects 0.000 claims description 49
- 239000007789 gas Substances 0.000 claims description 48
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 44
- 239000012452 mother liquor Substances 0.000 claims description 40
- 238000006386 neutralization reaction Methods 0.000 claims description 40
- 239000003921 oil Substances 0.000 claims description 40
- 239000002562 thickening agent Substances 0.000 claims description 30
- 239000006227 byproduct Substances 0.000 claims description 19
- 239000000047 product Substances 0.000 claims description 19
- 150000001408 amides Chemical class 0.000 claims description 18
- 238000002156 mixing Methods 0.000 claims description 16
- 239000003513 alkali Substances 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 239000010779 crude oil Substances 0.000 claims description 11
- 239000013078 crystal Substances 0.000 claims description 11
- 238000005119 centrifugation Methods 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 230000035484 reaction time Effects 0.000 claims description 10
- 239000002002 slurry Substances 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 10
- 238000001311 chemical methods and process Methods 0.000 claims description 9
- 239000012295 chemical reaction liquid Substances 0.000 claims description 9
- 238000002425 crystallisation Methods 0.000 claims description 9
- 230000008025 crystallization Effects 0.000 claims description 9
- 238000011084 recovery Methods 0.000 claims description 9
- 238000003860 storage Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000007670 refining Methods 0.000 claims description 8
- 230000014759 maintenance of location Effects 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 4
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 claims description 4
- 239000002351 wastewater Substances 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 238000001816 cooling Methods 0.000 description 6
- KBMSFJFLSXLIDJ-UHFFFAOYSA-N 6-aminohexanenitrile Chemical compound NCCCCCC#N KBMSFJFLSXLIDJ-UHFFFAOYSA-N 0.000 description 3
- 229920002292 Nylon 6 Polymers 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 125000003182 D-alloisoleucine group Chemical group [H]N([H])[C@@]([H])(C(=O)[*])[C@](C([H])([H])[H])([H])C(C([H])([H])[H])([H])[H] 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000137 polyphosphoric acid Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000017105 transposition Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/18—Nitrates of ammonium
- C01C1/185—Preparation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/02—Preparation of lactams
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D223/00—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom
- C07D223/02—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings
- C07D223/06—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D223/08—Oxygen atoms
- C07D223/10—Oxygen atoms attached in position 2
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the field of caprolactam production, in particular to a high-efficiency and energy-saving caprolactam production method; the invention provides a high-efficiency energy-saving caprolactam production method, which improves the original process so as to strengthen the mass transfer process of the reaction, quicken the reaction rate, effectively utilize the reaction generated heat, reduce the power consumption of the original process, more effectively save the energy consumption, reduce the production cost, improve the production efficiency and finally realize the comprehensive improvement of the technical level of the old process.
Description
Technical Field
The invention relates to the field of caprolactam production, in particular to a high-efficiency and energy-saving caprolactam production method.
Background
Caprolactam of the formula C6H11NO, molecular weight 113.16, is one of the important organic chemical materials, and has white powder or crystal appearance and oily hand feeling. The main application is to generate polyamide slices (usually called nylon-6 slices or nylon-6 slices) by polymerization, and the polyamide slices can be further processed into nylon fibers, engineering plastics and plastic films. The nylon-6 slice has different application fields depending on the quality and indexes.
CN97196496.3 claims a process for preparing caprolactam from 6-aminocapronitrile, a process for preparing caprolactam by cyclizing 6-aminocapronitrile in the presence of high temperature water and in the presence or absence of a catalyst and a solvent, the process comprising: a) separating caprolactam and all components having a boiling point higher than that of caprolactam ("high boilers") from the cyclization reaction effluent ("reaction effluent I"), b) treating the high boilers of step a) with phosphoric acid and/or polyphosphoric acid at from 200 to 350 ℃ to give a reaction effluent II, and c) separating the caprolactam formed from the reaction effluent II of step b) and separating 6-aminocapronitrile from the unconverted high boilers and the acid used.
In the prior art, a medium-temperature (50-60 ℃) negative-pressure (absolute pressure 10KPa) synthesis process is adopted, so that the retention time of materials in a reactor is long, the volume of reaction equipment is overlarge, and more fields are occupied. In the reaction process, the negative pressure needs to be maintained all the time, the energy consumption is high, and simultaneously, a large amount of waste of heat generated by the reaction of ammonia and the transposition ester is caused.
In order to enhance the mass transfer process of the reaction, increase the reaction rate, and effectively utilize the heat generated by the reaction (in an attempt to convert it to high-grade steam for utilization), improvements to the original process are needed.
Disclosure of Invention
The invention discloses a high-efficiency energy-saving caprolactam production method, belonging to the field of caprolactam production.
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: reacting 0-5000kg/h of gas ammonia and 0-28000kg/h of rearrangement liquid from outside a battery compartment in a neutralization reactor 1 containing ammonium sulfate mother liquor, reacting the gas ammonia and sulfuric acid in heavy discharge liquor according to an equimolar ratio, wherein the acidity of the sulfuric acid in the rearrangement liquid is 40-65%, the flow rate of the ammonium sulfate mother liquor is 0-180t/h, starting the reaction under the set conditions, the reaction time is 0.05-0.5h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and the byproduct steam of 0-12.0t/h is sent to an ammoximation chemical process for use;
step 2: the reaction liquid in the step 1 overflows to a separator 2, the separation of crude oil and ammonium sulfate solution is completed under set conditions, the upper oil phase is cooled to 45-65 ℃ by an amide oil heat exchanger 4 and then enters an amide oil storage tank 5, and caprolactam is sent to a caprolactam working procedure for refining to produce a caprolactam product;
and step 3: after heat exchange is carried out on the lower-layer ammonium sulfate by a heat recovery heat exchanger 7, the temperature is reduced to 70-90 ℃ from 100-150 ℃, and the lower-layer ammonium sulfate enters a negative-pressure crystallizer 8 to finish crystallization; simultaneously carrying out neutralization reaction on the rearrangement liquid and the gas ammonia which are not sent into the neutralization reactor 1 in the crystallizer, carrying out mixing reaction on the part of the gas ammonia and the rearrangement liquid through an annular distribution nozzle in a guide cylinder of the crystallizer, and synchronously crystallizing the part of the gas ammonia and the rearrangement liquid with the solid ammonium sulfate generated in the step 3; the low-quality steam at the top of the crystallizer 8 is compressed, heated and pressurized to generate low-pressure steam of 0-50KPaG and 100-110 ℃ for ammoximation.
And 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product, and mother liquor overflowing from the top of the thickener is circularly sent to a neutralization reactor;
and 5: mixing the by-product steam condensate with alkali in a weight ratio of 4.8-5.2:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
More optimally, the ratio of the flow rate of the gas ammonia and the rearrangement liquid entering the neutralization reactor 1 to the flow rate of all the gas ammonia and the rearrangement liquid is 0-1
More optimally, the heavy liquid drainage in the step 1 is from a caprolactam working procedure and mainly comprises the following components: caprolactam, sulfuric acid, sulfur trioxide;
more optimally, the reaction conditions in the step 1 are as follows: the reaction temperature is 100-150 ℃, the reaction pressure is 0.08-0.4MPa, and the retention time is 2-10 minutes;
more preferably, the separation conditions of the crude oil and the ammonium sulfate solution in the step 2 are as follows: the temperature is 100 ℃ and 150 ℃, and the pressure is 0.08-0.4 MPa;
more optimally, the operation conditions of the crystallizer in the step 3 are as follows: temperature 40-80 deg.C, pressure 5-50KPa, pH: 4-6.5, the retention time is 1-5 minutes;
more optimally, the low-quality steam at the top of the crystallizer 8 in the step 3 is compressed to generate low-pressure steam with the pressure of 0-50KPaG and the temperature of 100-110 ℃;
more preferably, the alkali content in the step 5 is 30-32%;
more preferably, the pH value in the step 5 is 12-13;
more preferably, in the rectifier, ammonia in the wastewater is stripped by low-pressure steam, absorbed and condensed into high-concentration ammonia water, and the wastewater with the ammonia nitrogen content reduced to below 40mg/L is sent out after heat exchange.
Technical effects
Through improvement of the original process, the improvement of the space-time capacity of ammonium sulfate production is hopefully realized, the power consumption of the original process is reduced, certain grade steam is obtained, the energy consumption is effectively saved, the production cost is reduced, the production efficiency is improved, and finally the comprehensive improvement of the technical level of the old process is realized.
Description of the drawings:
FIG. 1 is a process flow diagram of the present invention.
The specific implementation mode is as follows:
the invention is further illustrated by the following specific examples and comparative examples:
comparison example (original process)
The method comprises the following steps:
step 1: 5150kg/h of gas ammonia and 28000kg/h of rearrangement liquid from outside a boundary area react and crystallize in a crystallizer 8 containing ammonium sulfate mother liquor, the gas ammonia reacts with sulfuric acid in heavy discharge liquor according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 53%, the flow rate of the ammonium sulfate mother liquor is 120t/h, the reaction temperature is 55 ℃, the reaction pressure is 0.01MPa, the reaction time is 0.1h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, low-quality steam with the temperature of 10kpa and 55 ℃ is generated, and the low-quality steam is condensed by circulating water;
step 2: the crystallized supersaturated ammonium sulfate solution enters a thickener 9, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization crystallizer 8.
And step 3: and mixing the byproduct steam condensate with alkali in a weight ratio of 4.8:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
And (4) conclusion: the comparative example is a standard working condition, and the caprolactam steam unit consumption reaches 5.3t/t because the steam quality at the top of the crystallizer is too low to be utilized.
Example 1
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 2000kg/h of gas ammonia and 10000kg/h of rearrangement liquid from outside a battery compartment react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and the sulfuric acid in heavy discharge liquid react according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 40%, the flow rate of the ammonium sulfate mother liquor is 80t/h, the reaction temperature is 100 ℃, the reaction pressure is 0.08MPa, the reaction time is 0.1h, the reaction heat is absorbed and evaporated by the water in the ammonium sulfate mother liquor, and 4t/h of byproduct steam is sent to an ammoximation chemical process for use;
and 2, step: overflowing the reaction liquid in the step 1 to a separator 2, separating crude oil from an ammonium sulfate solution at 105 ℃ and 0.09MPa, cooling an upper oil phase to 45 ℃ through an amide oil heat exchanger 4, feeding the cooled upper oil phase into an amide oil storage tank 5, and refining the upper oil phase in a caprolactam working procedure to produce a caprolactam product;
and step 3: the temperature of the lower-layer ammonium sulfate is reduced from 105 ℃ to 70 ℃ after heat exchange by a heat recovery heat exchanger 7, the lower-layer ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, neutralization reaction of rearrangement liquid and gas ammonia which are not sent into a neutralization reactor 1 is simultaneously carried out in the crystallizer, the gas ammonia and the rearrangement liquid are subjected to mixing reaction by an annular distribution nozzle in a guide cylinder of the crystallizer, and are synchronously crystallized with solid ammonium sulfate contained and generated in the step 3, and the operation condition of the crystallizer is as follows: temperature 40 ℃, pressure 12KPa, pH: 5, compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate low-pressure steam of 20KPaG and 100 ℃ for ammoximation;
and 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: and mixing the byproduct steam condensate with alkali in a weight ratio of 4.8:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
And (4) conclusion: compared with the comparative example, the steam consumption of the example can be reduced by 0.38t/t caprolactam, namely 4.75t/h steam under the condition of equivalent material consumption and equivalent quality.
Example 2
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 1950kg/h of gas ammonia and 13000kg/h of rearrangement liquid from outside a boundary area react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and sulfuric acid in the heavy discharge liquid react according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 45 percent, the flow rate of the ammonium sulfate mother liquor is 80t/h, the reaction temperature is 105 ℃, the reaction pressure is 0.16MPa, the reaction time is 0.20h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and 5.0t/h of byproduct steam is sent to an ammoximation chemical process for use;
and 2, step: overflowing the reaction liquid in the step 1 to a separator 2, separating crude oil from an ammonium sulfate solution at 110 ℃ and 0.09MPa, cooling an upper oil phase to 50 ℃ through an amide oil heat exchanger 4, feeding the cooled upper oil phase into an amide oil storage tank 5, and refining the upper oil phase in a caprolactam working procedure to produce a caprolactam product;
and step 3: the temperature of the ammonium sulfate at the lower layer is reduced from 110 ℃ to 80 ℃ after heat exchange by a heat recovery heat exchanger 7, the ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, the neutralization reaction of the rearrangement liquid and the gas ammonia which are not sent into a neutralization reactor 1 is simultaneously carried out in the crystallizer, the part of the gas ammonia and the rearrangement liquid are mixed and reacted by an annular distribution nozzle in a guide shell of the crystallizer, and are synchronously crystallized with the solid ammonium sulfate contained generated in the step 3, and the operation condition of the crystallizer is as follows: temperature 45 ℃, pressure 24KPa, pH: 5.5, compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate low-pressure steam of 30KPaG and 100 ℃ for ammoximation;
and (3) simultaneously completing partial neutralization reaction in the crystallizer, wherein about 2000kg/h of ammonia gas and 13600kg/h of rearrangement solution are subjected to mixing reaction through an annular distribution nozzle in a guide cylinder of the crystallizer, and are synchronously crystallized with the solid ammonium sulfate generated in the step (3).
And 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: and mixing the byproduct steam condensate with alkali in a weight ratio of 4.9:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
And (4) conclusion: compared with the comparative example, the steam consumption of the example can be reduced by 0.39t/t caprolactam, namely 4.875t/h steam under the condition of equivalent material consumption and equivalent quality.
Example 3
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 2500kg/h of gas ammonia and 18500kg/h of rearrangement liquid from outside a battery compartment react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and sulfuric acid in heavy discharge liquor react according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 50%, the flow rate of the ammonium sulfate mother liquor is 120t/h, the reaction temperature is 110 ℃, the reaction pressure is 0.24MPa, the reaction time is 0.25h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and 7.5t/h of byproduct steam is sent to an ammoximation chemical process for use;
step 2: overflowing the reaction liquid in the step 1 to a separator 2, separating crude oil from an ammonium sulfate solution at 110 ℃ and 0.10MPa, cooling an upper oil phase to 55 ℃ through an amide oil heat exchanger 4, feeding the cooled upper oil phase into an amide oil storage tank 5, and refining the upper oil phase in a caprolactam working procedure to produce a caprolactam product;
and 3, step 3: after heat exchange is carried out on the lower-layer ammonium sulfate by a heat recovery heat exchanger 7, the temperature is reduced from 110 ℃ to 90 ℃, and the lower-layer ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, wherein the operation conditions of the crystallizer are as follows: temperature 50 ℃, pressure 32KPa, pH: 5.5, simultaneously carrying out neutralization reaction on the rearrangement liquid and the gas ammonia which are not sent into the neutralization reactor 1 in the crystallizer, carrying out mixed reaction on the part of the gas ammonia and the rearrangement liquid through an annular distribution nozzle in a guide cylinder of the crystallizer, synchronously crystallizing the part of the gas ammonia and the rearrangement liquid with the solid ammonium sulfate generated in the step 3, compressing low-quality steam at the top of the crystallizer 8, then heating and boosting the pressure to generate low-pressure steam with 30KPaG and 110 ℃ for ammoximation.
And 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: mixing the by-product steam condensate with alkali at a weight ratio of 5.0:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and feeding the condensate into the rectifier
And (4) conclusion: compared with the comparative example, the steam consumption of the caprolactam can be reduced by 0.6t/t, namely 7.5t/h under the condition of equivalent material consumption and equivalent quality.
Example 4
An efficient and energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 3000kg/h of gas ammonia and 24000kg/h of rearrangement liquid from outside a battery compartment react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and sulfuric acid in the heavy discharge liquid react according to an equimolar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 50%, the flow rate of the ammonium sulfate mother liquor is 140t/h, the reaction temperature is 125 ℃, the reaction pressure is 0.30MPa, the reaction time is 0.30h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and 7t/h of byproduct steam is sent to an ammoximation chemical process for use;
step 2: the reaction liquid in the step 1 overflows to a separator 2, crude oil and ammonium sulfate solution are separated at 115 ℃ and 0.10MPa, the upper oil phase is cooled to 55 ℃ by an amide oil heat exchanger 4 and then enters an amide oil storage tank 5, and the upper oil phase is refined by a caprolactam working procedure to produce a caprolactam product;
and step 3: the temperature of the lower-layer ammonium sulfate is reduced from 115 ℃ to 85 ℃ after heat exchange by a heat recovery heat exchanger 7, the lower-layer ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, neutralization reaction of rearrangement liquid and gas ammonia which are not sent into a neutralization reactor 1 is simultaneously carried out in the crystallizer, the gas ammonia and the rearrangement liquid are subjected to mixing reaction by annular distribution nozzles in a guide shell of the crystallizer, and are synchronously crystallized with solid ammonium sulfate contained and generated in the step 3, and the operation condition of the crystallizer is as follows: temperature 60 ℃, pressure 38KPa, pH: 5.5, compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate 40KPag and 105 ℃ low-pressure steam for ammoximation;
and 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: the by-product steam condensate and alkali are mixed in a micro mixer according to the weight ratio of 5.1:1, the pH value of the condensate is adjusted, and the condensate enters a rectifier after exchanging heat with the discharged liquid of the rectifier.
And (4) conclusion: in the case of equivalent material consumption and equivalent quality, the steam consumption can be reduced by 0.6t/t caprolactam, namely 7.5t/h steam.
Example 5
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 4000kg/h of gas ammonia and 26000kg/h of rearrangement liquid from outside a battery compartment react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and sulfuric acid in heavy discharge liquor react according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 60%, the flow rate of the ammonium sulfate mother liquor is 160t/h, the reaction temperature is 130 ℃, the reaction pressure is 0.35MPa, the reaction time is 0.45h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and 9.0t/h of byproduct steam is sent to an ammoximation chemical process for use;
step 2: overflowing the reaction liquid in the step 1 to a separator 2, separating crude oil from an ammonium sulfate solution at 115 ℃ and 0.11MPa, cooling an upper oil phase to 65 ℃ through an amide oil heat exchanger 4, feeding the cooled upper oil phase into an amide oil storage tank 5, and refining the upper oil phase in a caprolactam working procedure to produce a caprolactam product;
and step 3: after heat exchange is carried out on the lower-layer ammonium sulfate by a heat recovery heat exchanger 7, the temperature is reduced from 115 ℃ to 85 ℃, and the lower-layer ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, wherein the operation conditions of the crystallizer are as follows: temperature 70 ℃, pressure 42KPa, pH: 5.8; simultaneously carrying out neutralization reaction on the rearrangement liquid and the gas ammonia which are not sent into the neutralization reactor 1 in the crystallizer, carrying out mixing reaction on the part of the gas ammonia and the rearrangement liquid through an annular distribution nozzle in a guide cylinder of the crystallizer, and synchronously crystallizing the part of the gas ammonia and the rearrangement liquid with the solid ammonium sulfate generated in the step 3; compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate low-pressure steam of 50KPag and 100 ℃ for ammoximation;
and 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: the by-product steam condensate and alkali are mixed in a micro mixer according to the weight ratio of 5.1:1, the pH value of the condensate is adjusted, and the condensate enters a rectifier after exchanging heat with the discharged liquid of the rectifier.
And (4) conclusion: compared with the comparative example, the steam consumption of the caprolactam can be reduced by 0.7t/t, namely 8.8t/h under the condition of equivalent material consumption and equivalent quality.
Example 6
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 4500kg/h of gas ammonia and 28000kg/h of rearrangement liquid from outside a boundary area react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and sulfuric acid in heavy discharge liquor react according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 65%, the flow rate of the ammonium sulfate mother liquor is 170/h, the reaction temperature is 140 ℃, the reaction pressure is 0.40MPa, the reaction time is 0.40h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and 10.0t/h of byproduct steam is sent to an ammoximation chemical process for use;
step 2: overflowing the reaction liquid in the step 1 to a separator 2, separating crude oil from an ammonium sulfate solution at 115 ℃ and 0.11MPa, cooling an upper oil phase to 65 ℃ through an amide oil heat exchanger 4, feeding the cooled upper oil phase into an amide oil storage tank 5, and refining the upper oil phase in a caprolactam working procedure to produce a caprolactam product;
and step 3: after heat exchange is carried out on the lower-layer ammonium sulfate by a heat recovery heat exchanger 7, the temperature is reduced from 115 ℃ to 90 ℃, and the lower-layer ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, wherein the operation conditions of the crystallizer are as follows: temperature 75 ℃, pressure 48KPa, pH: 5.8; simultaneously carrying out neutralization reaction on the rearrangement liquid and the gas ammonia which are not sent into the neutralization reactor 1 in the crystallizer, carrying out mixing reaction on the part of the gas ammonia and the rearrangement liquid through an annular distribution nozzle in a guide cylinder of the crystallizer, and synchronously crystallizing the part of the gas ammonia and the rearrangement liquid with the solid ammonium sulfate generated in the step 3; compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate low-pressure steam of 50KPag and 105 ℃ for ammoximation
And 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: and mixing the byproduct steam condensate with alkali in a weight ratio of 5.2:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
And (4) conclusion: compared with the comparative example, the steam consumption of the caprolactam can be reduced by 0.8t/t, namely 10t/h under the condition of equivalent material consumption and equivalent quality.
Example 7
The high-efficiency energy-saving caprolactam production method is characterized by comprising the following steps:
step 1: 5000kg/h of gas ammonia and 28000kg/h of rearrangement liquid from outside a battery compartment react in a neutralization reactor 1 containing ammonium sulfate mother liquor, the gas ammonia and sulfuric acid in heavy discharge liquor react according to an equal molar ratio, the acidity of the sulfuric acid in the rearrangement liquid is 65%, the flow rate of the ammonium sulfate mother liquor is 180/h, the reaction temperature is 150 ℃, the reaction pressure is 0.40MPa, the reaction time is 0.50h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and 12.0t/h of byproduct steam is sent to an ammoximation chemical process for use;
step 2: overflowing the reaction liquid in the step 1 to a separator 2, separating crude oil from an ammonium sulfate solution at 115 ℃ and 0.12MPa, cooling an upper oil phase to 65 ℃ through an amide oil heat exchanger 4, feeding the cooled upper oil phase into an amide oil storage tank 5, and refining the upper oil phase in a caprolactam working procedure to produce a caprolactam product;
and 3, step 3: after heat exchange is carried out on the lower-layer ammonium sulfate by a heat recovery heat exchanger 7, the temperature is reduced from 115 ℃ to 90 ℃, and the lower-layer ammonium sulfate enters a negative pressure crystallizer 8 to complete crystallization, wherein the operation conditions of the crystallizer are as follows: temperature 80 ℃, pressure 50KPa, pH: 5.8; simultaneously carrying out neutralization reaction on the rearrangement liquid and the gas ammonia which are not sent into the neutralization reactor 1 in the crystallizer, carrying out mixing reaction on the part of the gas ammonia and the rearrangement liquid through an annular distribution nozzle in a guide cylinder of the crystallizer, and synchronously crystallizing the part of the gas ammonia and the rearrangement liquid with the solid ammonium sulfate generated in the step 3; compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate low-pressure steam of 0-50KPag and 100-110 ℃ for ammoximation;
and 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, and crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product; the mother liquor overflowing from the top of the thickener is circularly sent to the neutralization reactor.
And 5: and mixing the byproduct steam condensate with alkali in a weight ratio of 5.2:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
And (4) conclusion: in the case of equivalent material consumption and equivalent quality, the steam consumption can be reduced by 0.4t/t caprolactam, namely 5t/h steam.
In conclusion, compared with the comparative example, the method provided by the patent can reduce the steam consumption by 0.9t/t caprolactam, namely 11.3t/h steam under the condition of equivalent material consumption and equivalent quality.
Claims (10)
1. An efficient and energy-saving caprolactam production method comprises the following operation steps:
step 1: reacting 0-5000kg/h of gas ammonia and 0-28000kg/h of rearrangement liquid from outside a battery compartment in a neutralization reactor 1 containing ammonium sulfate mother liquor, reacting the gas ammonia and sulfuric acid in heavy discharge liquor according to an equimolar ratio, wherein the acidity of the sulfuric acid in the rearrangement liquid is 40-65%, the flow rate of the ammonium sulfate mother liquor is 0-180t/h, starting the reaction under the set conditions, the reaction time is 0.05-0.5h, the reaction heat is absorbed and evaporated by water in the ammonium sulfate mother liquor, and the byproduct steam of 0-12.0t/h is sent to an ammoximation chemical process for use;
step 2: the reaction liquid in the step 1 overflows to a separator 2, the separation of crude oil and ammonium sulfate solution is completed under set conditions, the upper oil phase is cooled to 45-65 ℃ by an amide oil heat exchanger 4 and then enters an amide oil storage tank 5, and caprolactam is sent to a caprolactam working procedure for refining to produce a caprolactam product;
and step 3: after heat exchange is carried out on the lower-layer ammonium sulfate by the heat recovery heat exchanger 7, the temperature is reduced to 70-90 ℃ from 100-150 ℃, and the lower-layer ammonium sulfate enters a negative-pressure crystallizer 8 to complete crystallization; simultaneously carrying out neutralization reaction on the rearrangement liquid and the gas ammonia which are not sent into the neutralization reactor 1 in the crystallizer, carrying out mixing reaction on the part of the gas ammonia and the rearrangement liquid through an annular distribution nozzle in a guide cylinder of the crystallizer, and synchronously crystallizing the part of the gas ammonia and the rearrangement liquid with the solid ammonium sulfate generated in the step 3; compressing the low-quality steam at the top of the crystallizer 8, heating and boosting the pressure to generate low-pressure steam of 0-50KPaG and 100-110 ℃ for ammoximation;
and 4, step 4: the crystallized supersaturated ammonium sulfate solution enters a thickener, crystal slurry at the bottom of the thickener is sent to a centrifugation and drying unit to produce an ammonium sulfate product, and mother liquor overflowing from the top of the thickener is circularly sent to a neutralization reactor;
and 5: mixing the by-product steam condensate with alkali in a weight ratio of 4.8-5.2:1 in a micro mixer, adjusting the pH value of the condensate, exchanging heat with the discharged liquid of the rectifier, and then feeding the condensate into the rectifier.
2. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the flow rate of the gas ammonia and the rearrangement liquid entering the neutralization reactor 1 accounts for the ratio of the flow rate of all the gas ammonia and the rearrangement liquid to be 0-1.
3. An energy-efficient caprolactam production method according to claim 1, characterized in that: the heavy liquid discharge in the step 1 is from a caprolactam working procedure and mainly comprises the following components: caprolactam, sulfuric acid, sulfur trioxide.
4. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the reaction conditions in the step 1 are as follows: the reaction temperature is 100 ℃ and 150 ℃, the reaction pressure is 0.08-0.4MPa, and the retention time is 2-30 minutes.
5. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the separation conditions of the crude oil and the ammonium sulfate solution in the step 2 are as follows: the temperature is 100 ℃ and 150 ℃, and the pressure is 0.08-0.4 MPa.
6. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the crystallizer operation conditions in the step 3 are as follows: temperature 40-80 deg.C, pressure 5-50KPa, residence time 1-15 minutes, pH: 4-6.5.
7. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the low-quality steam at the top of the crystallizer 8 in the step 3 is compressed to generate low-pressure steam with the pressure of 0-50KPaG and the temperature of 100-110 ℃.
8. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the alkali content in the step 5 is 30-32%.
9. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: the pH value in the step 5 is 9-13.
10. An energy efficient process for producing caprolactam as claimed in claim 1, wherein: in the rectifier, ammonia in the wastewater is stripped by low-pressure steam, absorbed and condensed into high-concentration ammonia water, and the wastewater with the ammonia nitrogen content reduced to below 40mg/L is sent out after heat exchange.
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| US4138472A (en) * | 1976-11-10 | 1979-02-06 | Basf Aktiengesellschaft | Process for obtaining coarsely crystalline pure ammonium sulfate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4138472A (en) * | 1976-11-10 | 1979-02-06 | Basf Aktiengesellschaft | Process for obtaining coarsely crystalline pure ammonium sulfate |
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