CN101885842A - Continuous Polymerization Production Process of Nylon 6 - Google Patents

Abstract

The invention relates to a continuous polymerization production process of nylon 6, a textile raw material. The invention uses liquid caprolactam or solid caprolactam as a raw material, undergoes melting, storage, preparation of additives, continuous polymerization, tape injection pelletizing, slice extraction, slice drying, and slice transportation. , Measuring and packaging, extracting water evaporation, concentrate treatment and other processes to produce high-performance nylon 6 slices with a certain molecular weight.

Description

Continuous polymerization production technology for polyamide fibre 6

Technical field:

The present invention relates to a kind of textile raw material continuous polymerization production technology for polyamide fibre 6.

Background technology:

The polymerization of hexanolactam, the difference according to its used ring opening agent (also have claim initiator) can be divided into two classes: a kind ofly make ring opening agent with alkaloids, therefore be called the alkaline process polymerization, the fast polymerization of expressing one's gratification again; Another kind uses water as ring opening agent, therefore is called hydrolytic polymerization.This device adopts hydrolytic polymerization technology.

The hydrolytic polymerization process of hexanolactam is made up of initiation addition, the growth of chain, chain balance three phases.

(1) initiation of hexanolactam and addition stage

After hexanolactam was hydrolyzed into hexosamine, the hexanolactam molecule will be connected one by one on the molecule of hexosamine and become the short molecular chain that certain reaction is arranged.

Because participating in the hexanolactam molecule of hydrolysis is minority, so the molecule number of the hexosamine that hydrolysis generates is also few,, mainly show as addition reaction therefore in this stage, the initiation of addition reaction is owing to the formed negative ions of ring opening agent, the cause of having facilitated the hexanolactam molecular polarization.

(2) build phase of chain

Between the short chain molecule that in a last chemical reaction process, generates, form long chain molecule by polycondensation.

H-[-NH(CH ₂) ₅CO-] _n-OH+H-[-NH(CH ₂) ₅CO-] _m-OH＝H-[-NH(CH ₂) ₅CO-] _n+m-OH+H ₂O

Above-mentioned two reactions steps are not well-separated in time, and two are reflected at greatly on the time sequence all and intert mutually.Just in the initial stage, take reaction as the leading factor with open loop, addition, that continues then takes reaction as the leading factor with transfer reaction.

(3) chain equilibrium stage

This stage is mainly carried out the chain permutoid reaction.Amido linkage on the long chain molecule of various differential responses is subjected to holding amino effect, carrying out acidolysis and ammonia and separating, thereby the exchange of initiation chain makes polymeric molecular-weight average reach certain value.

H-[-NH(CH ₂) ₅CO-] _K1-OH+H-[-NH(CH ₂) ₅CO-] _K2--[-NH(CH ₂) ₅CO-] _K3-OH

＝H-[-NH(CH ₂) ₅CO-] _K2-OH+H-[-HN(CH ₂) ₅CO-] _K1--[-NH(CH ₂) ₅CO-] _K3-OH

During this period, hydrolysis and polycondensation are also carried out at the same time.

According to chemical equation, store liquid caprolactam that operation sends here after the preheating of hexanolactam preheater by hexanolactam, the concentrated solution of handling with additive for preparing and recovery process is mixed in proportion, send into pressure polymerization pot, pressure polymerization pot is a pressurized operation, and hexanolactam at first carries out open loop, addition reaction in this reactor.The oligomer of initial reaction is sent to the post polymerization device through toothed gear pump in the pressure polymerization pot, and the post polymerization device is normal pressure or decompression operation, finishes polycondensation at this reactor interpolymer, and water is discharged from outside the tower, thereby makes polymer chain rise to the needed polymerization degree.

Polymer melt becomes regular cylindrical section through casting, cooling, curing in the dicing machine inscribe.Contain section quilt thermal process water extraction of counter current contact with it in extraction tower of low-grade polymer, the extraction water that contains oligopolymer is discharged by cat head, delivers to the extraction water evaporization process.Constantly dry through the hot nitrogen that the section that extracts is recycled in drying tower, one joins the drying tower epimere hot nitrogen, this strand hot nitrogen is mainly removed the surface water of section, and another strand hot nitrogen is sent into the hypomere of drying tower, and this hot nitrogen then is used for removing the residual water-content in the section.

Dried section is moisture≤0.06%, cooled section is delivered to chip bunker and slice packaging feed bin with the pulse pneumatic conveying e Foerderanlage under nitrogen protection, after be delivered to again that the spinning process feed bin is directly used in spinning or behind metering packing as international sale.

The processing technology routine of home and abroad caprolactam polymerization production at present mainly contains following three classes:

(1) one section polymerization under atmospheric pressure technology;

Two sections polymerization under atmospheric pressure technology of (2) one sections pressurizations;

Two sections decompressions of (3) one sections pressurizations polymerization technique.

Broadness (η=2.2～4.0) and device versatility characteristics according to the handiness of producing, product relative viscosity, the present invention selects two sections decompressions of one section pressurization or non-pressurized processing technology routine for use, produces a kind of textile raw material continuous polymerization production technology for polyamide fibre 6 through craft screening.

Summary of the invention:

The present invention is a raw material with liquid caprolactam or solid hexanolactam, through preparation, successive polymerization, casting pelletizing, the operations such as extraction, chip drying, section conveying, metering packing and extraction water evaporation, concentrated solution processing of cutting into slices of fusion (solid hexanolactam), storage, additive, produce the high-performance chinlon 6 section of certain molecular weight.

Production technique of the present invention is characterized in that, step is as follows:

1) processing of raw material hexanolactam,

If raw material hexanolactam solid hexanolactam is then used the hot water fusion, insulation obtains liquid caprolactam, when the raw material hexanolactam need not fusion during for liquid caprolactam, and insulation, directly use,

2) preparation of additive

The preparation of titanium dioxide

The titanium dioxide de-salted water is thorough mixing under agitation, and after the mixing, sedimentation 24 hours obtains tio_2 suspension, and tio_2 suspension adds liquid caprolactam and obtains titanium dioxide hexanolactam mixing suspension,

The preparation of properties-correcting agent

PTA (pure terephthalic acid) and properties-correcting agent S-EED (material of a kind of nylon stabilizer S-EED, market is on sale) filter after mixing with liquid caprolactam, obtain modifier solution,

3) hexanolactam successive polymerization

Tio_2 suspension, liquid caprolactam behind the modifier solution thorough mixing, is carried out ring-opening reaction respectively, polyaddition reaction, the polyreaction of molecular chain lengthening obtains polymkeric substance,

4) pelletizing

The cooling of fused polymkeric substance, curing, moulding, the particle section of being cut into the specification equalization at last by dicing machine,

5) extraction

The section water extracts,

6) drying

Section after the extraction obtains chinlon 6 section through the super-dry cooling.

Preferred production technique of the present invention is characterized in that step is as follows:

1) fusion of hexanolactam

When adopting the solid hexanolactam to be raw material, the solid hexanolactam is pulverized after the hot water fusion is heated to 85～90 ℃, and by 85 ℃ of hot water thermal insulatings,

When adopting liquid caprolactam, raw material need not fusion,

2) preparation of additive

The preparation of titanium dioxide

The de-salted water of 30% parts by weight of titanium oxide and 70% weight part is thorough mixing under high-speed stirring, mix back sedimentation 24 hours, obtain tio_2 suspension, tio_2 suspension add 40% weight part liquid caprolactam obtain titanium dioxide hexanolactam mixing suspension.

The preparation of properties-correcting agent

The liquid caprolactam of the de-salted water of the properties-correcting agent of the PTA of 10% weight part, 5% weight part and 10% weight part and 75% weight part is filtered after agitator stirs thorough mixing, obtains modifier solution.

3) caprolactam polymerization

Add 0.45% weight part modifier solution, the liquid caprolactam of 99.55% weight part is preheated to 180 ℃, add 0.3% parts by weight of titanium oxide hexanolactam mixing suspension in case of necessity, carry out the pressure polymerization ring-opening reaction, 240 ℃ of its temperature of reaction are carried out polyaddition reaction then, and temperature of reaction is 275 ℃, 3～4 hours time, the polymer viscosity that obtains is about 1.7.

Polymkeric substance carries out the polyreaction of molecular chain lengthening, is reflected under normal pressure or the vacuum and operates, and temperature is at 255 ℃, and the melt drop temperature is at 250～260 ℃, and 10 hours residence time of polymkeric substance, the viscosity of polymkeric substance is 2.4～3.5 when going out the post polymerization device,

4) pelletizing

The water quench that the fused polymkeric substance is sprayed into continuously, curing, moulding, the particle section of being cut into the specification equalization at last by dicing machine,

5) extraction

After extracting in advance in the pre-extraction of the section water pot, send into extraction and take extraction, section in extraction tower with the water counter current contact,

The blending ratio of section and water is controlled by the add-on of regulating fresh de-salted water, its bath raio 1: 1, section 24 hours residence time in extraction tower, extractable drops to below 0.5% by original 10% in the section, after separating water, drying is carried out in section

6) drying

The section of moisture percentage about 8～15% dry dwell time in the tower 24 hours, obtains moisture at the chinlon 6 section below 0.06%.

Production technique of the present invention comprises that also technology is reclaimed in the recycling of following raw material, as:

The extraction water evaporation

The extraction water that contains hexanolactam and oligomer concentrations about 10% by the pre-extraction of extraction process is concentrated to about 80%,

The concentrated solution aftertreatment

80% concentrated solution carries out aftertreatment.The concentrated solution of handling is mixed into pressure polymerization pot with fresh hexanolactam in proportion by pressure reduction and carries out polyreaction, realizes the closed cycle of hexanolactam.

Production technique of the present invention need be used some industrial equipmentss, and these equipment are general polymerization unit, as refluxing, and pressurization, drying, equipment such as controlled temperature all belong to the category of prior art.The invention reside in through screening and obtain good reaction conditions and processing step, make product meet industrialized high-level efficiency and high quality more.

Technology of the present invention has following characteristics:

1. caprolactam polymerization is a two-section type successive polymerization flow process, pre-polymerization pressurization, post polymerization decompression or normal pressure.Gas phase or liquid phase biphenyl segmentation control heating, thus polyreaction is complete in can guaranteeing to produce, the polymer viscosity fluctuation is little, and molecular weight distribution is even, regular, helps post-treatment.

2. adopt extraction water concentrated solution direct reuse novel process after high temperature, autoclaving, be equipped with the charging of certain proportion of additive with fresh hexanolactam with after the hexanolactam concentrated solution that high temperature, autoclaving are crossed is mixed in proportion again as polymerization process.

3. the multi-stage continuous extraction technology of the pre-extraction of band is adopted in the section extraction, novel tower inner member is adopted in the extraction tower design, thereby can improve extraction efficiency, after the extraction, extractable is less than 0.6% in the section, and extraction water concentration can be brought up to more than 10%, and therefore the energy consumption that makes hexanolactam reclaim can reduce greatly.

4. chip drying adopts two sections nitrogen circulation adverse current successive drying flow processs, and when dry, by successive drying, drying effect is good like this in closed system in section, and the section water ratio is low, and can not be subjected to atmospheric oxidation, so chipping qualities is good.Both can satisfy and produce the section of polyamide fibre 6 high speed spinnings, and can carry out solid phase polycondensation again and produce full-bodied engineering plastics.

5. section is carried and is adopted home-made closed nitrogen circulation pulse pneumatic conveying delivery technology.

6. the technology of triple effect evaporation is adopted in the extraction water evaporation.

Description of drawings:

Fig. 1: process flow diagram

Fig. 2: equipment flowsheet synoptic diagram

Embodiment:

Further specify the present invention by the following examples, but not as limitation of the present invention.

Embodiment 1

1. the fusion of hexanolactam and storage

When adopting the solid hexanolactam to be raw material, the solid hexanolactam that is stored in the warehouse is carried to melting zone through fork truck, and Kai Bao is after after hexanolactam charging system (X-1100) pulverizing, send in the hexanolactam fusion pot (V-1101) through screw feeder again.The solid hexanolactam of Jia Ruing is after the hot water fusion first, circulate through hexanolactam recycle pump (P-1101) supercharging by hexanolactam prefilter (X-1101), be heated to 85～90 ℃ by hexanolactam well heater (E-1101), the hexanolactam well heater is by steam heating.Hexanolactam after the heating is back to the fusion pot; with initiate solid hexanolactam mixed melting; the fused liquid caprolactam is delivered to hexanolactam middle vessel (V-1103) after hexanolactam strainer (X-1102) filters, basin is established the protection of nitrogen envelope, by 85 ℃ of hot water thermal insulatings.

When adopting liquid caprolactam, raw material is transported to the tank field with tank car, and liquid caprolactam is from the tank car discharge by pump and deliver to hexanolactam middle vessel (V-1103).

The liquid caprolactam that is stored in the hexanolactam middle vessel is delivered to additive preparation and polymerization process by hexanolactam charge pump (P-1102) through hexanolactam strainer (X-1103).

2. the preparation of additive

The preparation of titanium dioxide

Titanium dioxide is used for producing half delustring or full-dull nylon 6-slice, packed titanium dioxide weight is on request poured titanium dioxide preparing tank (V-1141) into, with de-salted water thorough mixing under high-speed stirring, be made into tio_2 suspension, deliver to titanium dioxide slurry tank (V-1142), after sedimentation in 24 hours, suspension is delivered to titanium dioxide weighing jar (V-1144), allocate a certain amount of hexanolactam into, regulate the concentration of titanium dioxide, it is stand-by to deliver to tio_2 suspension basin (V-1145) again.

The thick tio_2 suspension of discharging from titanium dioxide slurry tank (V-1142) bottom drains into titanium dioxide accumulator tank (V-1146), will reclaim titanium dioxide after the water evaporates with the steam coils heating.

The preparation of properties-correcting agent

Packed PTA and properties-correcting agent are after solid properties-correcting agent feeding unit (X-1131) metering, join properties-correcting agent Preparation tank (V-1131), with liquid caprolactam after agitator stirs thorough mixing, filter through properties-correcting agent strainer (X-1133), deliver to properties-correcting agent susceptor (V-1133), deliver to polymerization process through properties-correcting agent volume pump (P-1132) again.

3. hexanolactam successive polymerization

Polyreaction comprises two stages.Be the compressive reaction of fs and the normal pressure or the decompression reaction of subordinate phase.

When producing half delustring section, add a certain amount of tio_2 suspension from pressure polymerization pot (R-1201) ingress.The fresh liquid hexanolactam is delivered to hexanolactam preheater (E-1201) through hexanolactam charge pump (P-1102) and is preheated to 180 ℃, the concentrated solution that titania solution (in case of necessity), modifier solution and the recovery process of sending here with the additive preparation process handled is by a certain percentage by behind the static mixer thorough mixing, send into pressure polymerization pot (R-1201) top again, the pressure of pressure polymerization pot (R-1201) is controlled at 0.15MPa (G) by the top exhaust regulating valve.Epimere at polymerizing pipe mainly carries out ring-opening reaction, 240 ℃ of its temperature of reaction, the hexanolactam hydrolysis need absorb heat, the reactor upper design a built-in well heater, come heat supplied with biphenyl steam (270～280 ℃).After biphenyl steam is condensed, heats again vaporization cycle at biphenyl vaporizer (E-1202) with liquid phase heating agent (320 ℃) and use.Polyaddition reaction is carried out in the pressure polymerization pot bottom, and temperature of reaction is 275 ℃, and reaction institute heat requirement is provided by the gas diphenyl (270～280 ℃) that the wall chuck feeds by biphenyl vaporizer (E-1203) heating.Polymkeric substance stopped in pressure polymerization pot about 3～4 hours, and when going out pressure polymerization pot, polymer viscosity can reach about 1.7.

The reinforced liquid level control by flow and pressure polymerization pot of hexanolactam, feeding quantity is measured with a mass flowmeter.Hexanolactam preheater (E-1201) and heat with a secondary liquid phase heating agent loop to the product pipeline of pressure polymerization pot (R-1201), the temperature in this loop can independently be controlled.

By the liquid level control of preceding poly-discharging pump (P-1201) and post polymerization device (R-1202), prepolymer is sent to post polymerization device (R-1202), and what the post polymerization device mainly carried out is the polyreaction of molecular chain lengthening.Post polymerization device (R-1202) is in normal pressure (also can in vacuum) operation down, heat with gas diphenyl on its top, in, the bottom is with the heat exchange of liquid phase biphenyl, the built-in interchanger of particular design cools off with liquid phase biphenyl, remove the reaction liberated heat, the heat of cooling section is recovered and is used for the preheating hexanolactam.The upper temp of control post polymerization device is at 255 ℃, the melt drop temperature is at 250～260 ℃, about 10 hours of the residence time of polymkeric substance, the viscosity of polymkeric substance can reach 2.4～3.5 when going out the post polymerization device, and the special construction of this equipment can guarantee that product flows therein equably.Factory can be according to the demand of market to product specification, the vacuum tightness that the control post polymerization is produced, thereby the polymerization section of producing different viscosity.

When reacting in pressure polymerization pot (R-1201) and post polymerization device (R-1202), water and hexanolactam are evaporated.Steam is through separation column (T-1203) distillation, and the solution that contains hexanolactam is delivered to hexanolactam water enrichment process through separation column (T-1203), and outer dispatch sewage works is handled after the overhead vapours condensation.。

Post-polymerization device bottom material is discharged with a melt discharging pump (P-1205).Pump is delivered to fondant filter (X-1204) and casting head (X-1202) with polymkeric substance through the polymkeric substance pipeline of heating.Fondant filter is the strainer that do not stop, and when needs switch filtering device, reserve filter switches by valve and just can start.

4. pelletizing

Extrude the aperture of fused polymkeric substance from end of extruded band, the particle of specification equalization is cut in water quench, curing, the moulding that is sprayed into continuously on the cooling plate of dicing machine (M-1201) under water at last by dicing machine.Section falls into pre-extraction water pot (V-1301) after vibratory screening apparatus (M-1202) separates underproof section and surperficial moisture content.

The pelletizing water coolant of finishing after the pelletizing flows into pelletizing water basin (V-1208); extract out by pelletizing water-circulating pump (P-1209); deliver to pelletizing water filter (X-1203) and filter out solids, and pelletizing watercooler (E-1212) is cooled to 16 ℃ by 7 ℃ refrigerated water and sends dicing machine back to and recycle.

The monomer vapours at the monomer vapours at end of extruded band place and dicing machine place is by air-breathing squirt pump (J-1202) sucking-off; the injection water of air-breathing squirt pump is provided by injection water recycle pump (P-1208); the injection water recycle pump is extracted injection water out from pelletizing water basin (V-1208) and is sent into air-breathing squirt pump, has drawn the injection water inflow pelletizing water basin (V-1208) behind the monomer and has used repeatedly.

The frequency transformer and the discharging gear pump motor frequency transformer of underwater pelletizer (M-1201) motor are chain, and dicing machine can be regulated automatically according to what of polymer flow rate, work in the best condition with the maintenance machine.

5. continuous extraction

Section falls into pre-extraction water pot (V-1301) from vibratory screening apparatus, after section extracts in pre-extraction water pot in advance, rotational lock inlet valve (X-1301) quantitative discharging at the bottom of jar, section and water are extracted out through section slush pump (P-1302) and are sent into the hydathode (X-1303) that is located at the extraction cat head, after separating big water gaging, section falls into extraction and takes (T-1301).Extraction is extracted water-circulating pump (P-1304A/B) with de-salted water and extracts out from extraction water pot (V-1304), after extraction water strainer (X-1304) filters out solids, ℃ entered extraction tower (T-1301) through extraction water well heater (E-1302) by 0.3MPa (G) steam heating to 97 again from the tower bottom, section in extraction tower with the water counter current contact.Throughput according to device, the forms such as single-stage extractions such as one-level extraction tower, secondary extraction tower and three grades of extraction towers or multi-stage solvent extraction that are provided with of extraction tower, multi-stage solvent extraction and single-stage extraction process form are basic identical, the just repetition of single-stage extraction, level extracts in principle that extraction temperature is higher than the prime extraction after the technology controlling and process.

The section and the blending ratio of water are controlled by the add-on of regulating fresh de-salted water, and its bath raio 1: 1 is cut into slices about 24 hours of the residence time in extraction tower, and extractable drops to below 0.5% by original 10% in the section.Qualified section rotational lock inlet valve (X-1305 or X-1308) at the bottom of tower is controlled continuous discharging, to cut into slices by section cement slurrypump (P-1305 or P-1307) and water is delivered to the water extracter (M-1301) that is located at the drying tower top, separating cuts into slices behind the water falls into drying tower (T-1401) again.

The water that water extracter (M-1301) is told flows into extraction water sealed cans (V-1307) with one of the de-salted water that replenishes, extraction water sealed cans inner coil pipe feeds the steam of 0.3MPa (G), the temperature of extraction water is heated to about 95 ℃, extraction water is discharged from extraction water sealed cans top, flow into extraction water pot (V-1306) from top, here the gas of carrying secretly in the water is discharged from outdoor and controls the liquid level that extracts water pot and exceeds 500mm than extraction tower (T-1301) liquid level.The extraction water of getting rid of at the bottom of the jar is divided into two-way, one the road flows into rotational lock inlet valve (X-1308) provides water for the section conveying, one the road flows into extraction water recycle pump (P-1306), after extraction water strainer (X-1307) filters, ℃ entered extraction tower (T-1302) through extraction water well heater (E-1303) by 0.3MPa (G) steam heating to 98 again from the tower bottom, with the section counter current contact, extraction monomer and oligomer wherein.

The extraction water that contains monomer concentration about 7.5% flows out from one-level extraction tower top, with the hydration of getting rid of from hydathode (X-1303) also, one the road flows into rotational lock inlet valve (X-1301) provides water for the section conveying, one the road flows into pre-extraction water pot (V-1301) end, from the effusive extraction water monomer concentration about 10% in pre-extraction water pot top, be sent to extraction water pot (V-1601) and store, hexanolactam is stand-by as reclaiming.

In pre-extraction water pot and extraction tower equipment, be provided with multi-layer efficient, no stagnant area and strengthen extraction water and the tower inner member of cutting into slices and fully contacting.Pre-extraction water pot is provided with a heating jacket, feeds the low-pressure steam heating of 0.05MPa (G) in the chuck, to keep pre-extraction water temperature.Be provided with a special built-in well heater at the bottom of the extraction Tata, the low-pressure steam heating of interior feeding 0.3MPa (G) guarantees the extraction efficiency to oligopolymer with convenient adjusting to extraction temperature.

6. successive drying

The section moisture percentage that comes out from water extracter (M-1301) is about 8～15%, enters the drying tower (T-1401) from the top, according to the throughput of device, establishes a cover drying tower system or two covers drying tower system arranged side by side.Desiccant hot nitrogen divides two strands from tower bottom and tower middle part adding tower, the hot nitrogen that top adds is mainly used in dry sliced surface-moisture, and the heating section, and the hot nitrogen that the bottom adds removes the remaining moisture of section, and the heated polymerizable thing, its molecular weight is improved.Section about 24 hours at dry dwell time in the tower.It is moisture below 0.06% to cut into slices when going out drying tower, and dry good section is sent to section cooling feed bin (V-1403) after star is measured transfer valve (X-1401) dominant discharge.Under the circulation cooling of cold nitrogen gas stream, after section is cooled to qualified temperature, be sent to section blending bun (V-1506) through pneumatic conveyer.

Nitrogen ejects from drying tower, after the pressurization of the first nitrogen circulation blower fan (C-1401), part nitrogen is entered drying tower by after 1.0MPa (G) steam heating to 130 ℃ from the middle part through nitrogen heater (E-1401), another part nitrogen enters nitrogen heat exchanger (E-1402) with after the next cold nitrogen heat exchange in cooling tower (T-1402) top, go into tower from the cooling tower bottom, with the spraying cooling water counter current contact that adds from tower top, nitrogen is washed, cooling back temperature is controlled at 12 ℃ and comes out from cat head, after entering nitrogen heat exchanger (E-1402) and high temperature nitrogen heat exchange, enter the second nitrogen circulation blower fan (C-1402), enter nitrogen deoxygenator (R-1401) after the supercharging, nitrogen heater (E-1404) is by 1.0MPa (G) steam heating to 125 ℃, enter drying tower from the bottom, recycle.

Cooling tower (T-1402) bottom spray water is delivered to spray water recycle pump (P-1401) and is cycled back to cooling tower top spray after spray water water cooler (E-1403) is cooled to 12 ℃ extremely down, cooling shunts to wet nitrogen from the drying tower top, cool down unnecessary water of condensation from the cooling tower overflow to water-sealed tank (V-1404), and overflow effluxes again.

Cool nitrogen is delivered to nitrogen cooler (E-1405) by nitrogen three-circulation wind machine (C-1403), be cooled with circulating water, send into the bottom of section cooling feed bin (V-1403) then, nitrogen is discharged by the equipment top from bottom to top, loops back the three-circulation wind machine after dust filter unit (X-1403) dedusting.

Also can carry out the solid phase aftercondensated in drying tower, but the temperature requirement of nitrogen is higher, the residence time of section is more longer.When carrying out the solid phase aftercondensated, the nitrogen that comes out in the drying tower top need all be delivered to cooling tower and wash.

7. section is carried and packing

Being located at the beneath pulse transfer pot (V-1502) of section cooling feed bin (V-1403) is used for section is transported to section blending bun (V-1506), cuts into slices and store feed bin (V-1507).Finished product section can be stored under the feed bin (V-1507) through wrapping machine (M-1501) metering, packing in section blending bun (V-1506) or section, puts export trade in storage after dressing up the pouch of the sack of 750kg or 25kg.

Option: be located at pulse transfer pot (V-1503) under section blending bun (V-1506) and be used for that section is transported to section and store feed bin (V-1507) or directly be delivered to the spinning feed bin and be used for spinning.

Underproof section is directly delivered to packaging system and is packed separately.

Conveying is used with nitrogen circulation, delivers to the pulse transfer pot again after sack cleaner (X-1501), nitrogen compressor (C-1501) and circulating nitrogen gas basin (V-1501) pressurization.

8. extraction water evaporation

Extract the extraction water that contains hexanolactam and oligomer concentrations about 10% that water pot (V-1301) is sent here in advance by extraction process, flow into extraction water pot (V-1601) (all water that contain hexanolactam all are collected in wherein in the device).Extract out, filter through extraction water charge pump (P-1601), send into one and imitate evaporator tower (T-1601).One thermal source of imitating reboiler (E-1601) is provided by two secondary steams of imitating evaporator tower, extraction water is heated to 80 ℃ and enters an effect evaporator tower (T-1601), this tower working pressure is 0.04MPa (absolute pressure), the aqueous vapor that cat head steams is cooled off through condenser (E-1602) condensation, phlegma flows into phegma holding tank (V-1602), and a phlegma of imitating reboiler is also collected phegma holding tank (V-1602).Partial condensation liquid squeeze into through reflux pump (P-1602) one imitate, two imitate, the triple effect evaporation tower refluxes, all the other phlegmas return extraction process and make extraction water usefulness, the closed cycle of realization water.Non-condensable gas is extracted out through vacuum pump (K-1601), to keep cat head negative-pressure operation condition.Through an effect evaporation, extraction water concentration brings up to 15% at the bottom of the tower, is extracted out by hexanolactam water pump (P-1603) and delivers to two effect evaporator towers (T-1602).

The thermal source of two effect reboilers (E-1602) is provided by the secondary steam of triple effect evaporation tower, extraction water is heated to 98 ℃ and enters two effect evaporator towers (T-1602), this tower working pressure is 0.08MPa (absolute pressure), the aqueous vapor that cat head steams is used as a thermal source of imitating reboiler (E-1601), and two phlegmas of imitating reboiler are collected phegma holding tank (V-1602) too.Through an effect evaporation, extraction water concentration brings up to 25% at the bottom of the tower, is extracted out by hexanolactam water pump (P-1604) and delivers to triple effect evaporation tower (T-1603).

By two imitate the extraction water come through triple effect reboiler (E-1603) by 1.0MPa (G) steam heating to 138 ℃, triple effect evaporation tower working pressure is 0.04MPa (G), extraction water is concentrated to about 80% at this tower, and spissated caprolactam water solution flows into the hexanolactam water feed pot (V-1604) at the bottom of tower certainly by the jacket pipe by 0.3MPa (G) steam insulation.

9. concentrated solution aftertreatment

80% concentrated solution is stored in the hexanolactam water feed pot (V-1604), and by concentrated solution recycle pump (P-1604) pump circulation, hexanolactam water feed pot and circulation line are by 0.3MPa (G) steam insulation.Partial concentration liquid is pressurized to 2.9MPa (G) by concentrated solution fresh feed pump (P-1605), is heated to 250 ℃ by concentrated solution well heater (E-1605) and enters in the cracking reactor (R-1601) and carry out aftertreatment.The concentrated solution of handling is mixed in the pressure polymerization pot (R-1201) with fresh hexanolactam in proportion by pressure reduction and carries out polyreaction, realizes the closed cycle of hexanolactam.

The required heat of concentrated solution aftertreatment is supplied with by biphenyl steam (275 ℃), after biphenyl steam is condensed, heats again vaporization cycle at biphenyl vaporizer (E-1606) with liquid phase heating agent (320 ℃) and uses.

10. hot-water system

The hot water that is come by house steward hot water backwater is delivered to hot water heater through hot water circulating pump (P-8101) and is circulated after the needed temperature with 0.3MPa (G) steam heating and deliver to each hot water user.Divide another branch road supply and demand low-temperature water heating user after hot water water cooler (E-8101) is cooled to needed temperature to use behind the hot water circulating pump.The return main need be connected to hot water expansion slot (V-8101).

11. steam condensate

Each steam user's vapor condensation moisture different pressures grade is delivered to hot well (V-9421) through coagulating the supply mains, and fusion workshop (far away) user's steam condensate is sent back to by condensated water recovering pump.Hot well (V-9421) has the special setting interchanger and is used to reclaim overheated condensed water heat.Water of condensation in the receiving tank is then delivered to the boiler house by condensate pump (P-9421).

12. biphenyl is reinforced and collection

Liquid phase biphenyl is stored in the biphenyl holding tank (V-8201), is sent to each user through biphenyl fresh feed pump (P-8201).Biphenyl holding tank escape pipe is provided with condensing works, and by the gas diphenyl of water coolant and air cooling discharging, non-condensable gas discharges through height point.

Each gas diphenyl system establishes one's own system, by charging of gas phase furnace bottom and discharge, condensation biphenyl also returns from the bottom, gas diphenyl is expelled to each user's point from furnace roof portion, escape pipe is provided with safety valve, and the gassy system vertex is provided with the biphenyl vapor-liquid separation tank, and non-condensable gas irregularly drains into the biphenyl holding tank (V-8201) from the vapor-liquid separation tank deck, lime set is returned the gas phase stove

Liquid phase biphenyl system is made up of biphenyl recycle pump, well heater and biphenyl expansion slot, the shared biphenyl expansion slot of two cover liquid phase biphenyl systems of post polymerization device, the height point of system is provided with vent line and inserts expansion slot, and expansion slot is provided with manual exhaust (advancing the biphenyl holding tank) and safety valve.Liquid phase systems biphenyl is reinforced to be arranged on expansion slot top, and the blowing pipeline is arranged on the lower-most point of system.The outlet line of well heater is provided with safety valve.

The blowing pipeline of each system and the outfall pipeline of safety valve all insert the biphenyl holding tank.

13. primary fluid heating system

The heating system of pressure polymerization pot (R-1201), post polymerization device (R-1202) and cracking reactor (R-1601) is no matter vapour phase or liquid phase all heat with primary fluid.

The primary fluid medium is modification terphenyl or biphenyl-biphenyl ether, as uses biphenyl-biphenyl ether, and the primary fluid system needs pressurized treatment.Primary fluid is delivered to each user after the heating agent process furnace is heated to 320 ℃ of temperature, the heating agent that each user flows back to is delivered to the heating of heating agent process furnace through heat medium circulation pump, realizes the recycle of heating agent.The high point of return main is provided with the primary fluid expansion slot, is used for the expansion and the exhaust of primary fluid, and low spot is provided with the heating agent blowdown vessel.

14. the process control system of device

The technology controlling and process of whole device is finished by a general distributed control system (DCS), and distributed control system all has redundancy on communication function and technology controlling and process function.

Other complete supply of material equipment such as section flow delivery systems and underwater pelletizer system are established the field control cabinet in addition.

Claims (3)

1. a nylon 6 continuous polymerization production technique, is characterized in that, the steps are as follows: 1) the processing of raw material caprolactam, If the raw material caprolactam is solid caprolactam, melt it with hot water and keep it warm to obtain liquid caprolactam. 2) Preparation of additives Preparation of Titanium Dioxide Titanium dioxide desalted water is fully mixed under stirring, after mixing, settle for 24 hours to obtain a titanium dioxide suspension, add liquid caprolactam to the titanium dioxide suspension to obtain a titanium dioxide caprolactam mixed suspension, and prepare the modifier PTA and modifier S-EED are stirred and mixed with liquid caprolactam, filtered to obtain modifier solution, 3) Continuous polymerization of caprolactam After the titanium dioxide suspension, liquid caprolactam, and modifier solution are fully mixed, the ring-opening reaction, polyaddition reaction, and polymerization reaction of molecular chain lengthening are respectively carried out to obtain a polymer. 4) Diced The molten polymer is cooled, solidified, shaped, and finally cut into pellets of equal size by a pelletizer. 5) Extraction The slices were extracted with water, 6) dry The extracted slices are dried and cooled to obtain nylon 6 slices. 2. according to the production technology of claim 1, it is characterized in that, step is as follows: 1) Melting of caprolactam When solid caprolactam is used as raw material, the solid caprolactam is pulverized and melted by hot water, heated to 85-90°C, and kept warm by 85°C hot water. When liquid caprolactam is used, the raw material does not need to be melted, 2) Preparation of additives Preparation of Titanium Dioxide 30% by weight of titanium dioxide and 70% by weight of desalted water are fully mixed under high-speed stirring, and after mixing, they settle for 24 hours to obtain a titanium dioxide suspension, and 40% by weight of liquid caprolactam is added to the titanium dioxide suspension to obtain a mixed suspension of titanium dioxide caprolactam , Modifier preparation 10% by weight of PTA, 5% by weight of modifier, 10% by weight of desalted water and 75% by weight of liquid caprolactam are thoroughly mixed with a stirrer, and then filtered to obtain a modifier solution. 3) Polymerization of caprolactam Add 0.45% by weight of modifier solution, 99.55% by weight of liquid caprolactam preheated to 180 ° C, if necessary, add 0.3% by weight of titanium dioxide caprolactam mixed suspension, carry out pressure polymerization ring-opening reaction, the reaction temperature 240°C, then carry out polyaddition reaction, the reaction temperature is 275°C, the time is 3-4 hours, the viscosity of the obtained polymer is about 1.7, The polymer undergoes a polymerization reaction of molecular chain lengthening, the reaction is operated under normal pressure or vacuum, the temperature is 255°C, the melt discharge temperature is 250-260°C, the residence time of the polymer is 10 hours, and the polymer is The viscosity is 2.4 ~ 3.5, 4) Diced The molten polymer is cooled, solidified and formed by continuous spraying of cooling water, and finally cut into pellets of equal size by a pelletizer. 5) Extraction After pre-extraction in the slice pre-extraction water tank, it is sent to the extraction tower for extraction, and the slices are in countercurrent contact with water in the extraction tower. The mixing ratio of slices and water is controlled by adjusting the amount of fresh desalted water added. The bath ratio is 1:1. The slices stay in the extraction tower for 24 hours, and the extractable content in the slices is reduced from the original 10% to below 0.5%. , after separating off the water, the slices were dried, 6) dry The slices with a moisture content of about 8-15% stay in the drying tower for 24 hours to obtain nylon 6 slices with a moisture content of less than 0.06%. 3. according to the production technology of claim 1, it is characterized in that, step is as follows: 1. Melting and storage of caprolactam When solid caprolactam is used as the raw material, the solid caprolactam stored in the warehouse is transported to the melting area by a forklift, and after being unpacked, it is pulverized by the caprolactam feeding system, and then sent into the caprolactam melting pot through the screw feeder. The solid caprolactam added for the first time is passed through After the hot water is melted, it passes through the caprolactam pre-filter and is pressurized and circulated by the caprolactam circulating pump, and is heated to 85-90°C by the caprolactam heater, which is heated by steam, and the heated caprolactam flows back to the melting pot, and is mixed with the newly added solid Caprolactam is mixed and melted, and the molten liquid caprolactam is filtered by a caprolactam filter) and then sent to the caprolactam intermediate storage tank, which is protected by nitrogen sealing and kept warm by 85°C hot water. When liquid caprolactam is used, the raw materials are transported to the tank area by tank truck, and the liquid caprolactam is unloaded from the tank truck with a pump and sent to the caprolactam intermediate storage tank. The liquid caprolactam stored in the caprolactam intermediate storage tank is sent to the additive preparation and polymerization process by the caprolactam feeding pump through the caprolactam filter, 2. Preparation of additives Preparation of Titanium Dioxide Titanium dioxide is used to produce semi-dull or full-dull nylon 6 slices. The bagged titanium dioxide is poured into the titanium dioxide preparation tank according to the required weight, fully mixed with desalted water under high-speed stirring, and made into a titanium dioxide suspension, which is sent to the titanium dioxide settling tank. After 24 After settling for one hour, the suspension is sent to a titanium dioxide weighing tank, and a certain amount of caprolactam is added to adjust the concentration of titanium dioxide, and then sent to a titanium dioxide suspension storage tank for use. The crude titanium dioxide suspension discharged from the bottom of the titanium dioxide settling tank is discharged to the titanium dioxide recovery tank, and the titanium dioxide is recovered after the water is evaporated by heating with a steam coil. Modifier preparation After the bagged PTA and modifier are measured by the solid modifier feeding device, they are added to the modifier preparation tank, fully mixed with liquid caprolactam by a stirrer, filtered through the modifier filter, and sent to the modifier Receiver, and then pumped to the polymerization process through modifier metering, 3. Continuous polymerization of caprolactam The polymerization reaction includes two stages, that is, the pressurized reaction of the first stage and the normal pressure or reduced pressure reaction of the second stage, When producing semi-dull slices, a certain amount of titanium dioxide suspension is added from the inlet of the pressurized polymerizer, and the fresh liquid caprolactam is pumped to the caprolactam preheater to preheat to 180°C through the caprolactam feeding pump, and the titanium dioxide solution sent from the additive preparation process , modifier solution, and the concentrated solution treated in the recovery process are fully mixed by a static mixer in a certain proportion, and then sent to the upper part of the pressurized polymerizer. The pressure of the pressurized polymerizer is controlled at 0.15MPa through the top exhaust regulating valve. The upper section of the polymerization tube is mainly for ring-opening reaction, the reaction temperature is 240°C, caprolactam hydrolysis ring-opening needs to absorb heat, a built-in heater is designed on the upper part of the reactor, and biphenyl steam is used to supply heat at 270-280°C, biphenyl After the steam is condensed, the biphenyl evaporator is heated with a liquid-phase heat medium at 320°C for re-evaporation and recycling. The lower part of the pressurized polymerizer undergoes polyaddition reaction at a reaction temperature of 275°C. The gas-phase biphenyl heated by the biphenyl evaporator is provided at 270-280°C. The polymer stays in the pressurized polymerizer for about 3-4 hours. When it exits the pressurized polymerizer, the polymer viscosity can reach about 1.7. The feeding of caprolactam is controlled by the flow rate and the liquid level of the pressurized polymerizer, and the feeding amount is measured by a mass flow meter. The caprolactam preheater and the product pipeline to the pressurized polymerizer are heated by a secondary liquid phase heat medium circuit. The temperature of the circuit can be independently controlled, Through the liquid level control of the pre-polymerization pump and the post-polymerizer, the pre-polymer is sent to the post-polymerizer. The post-polymerizer mainly performs the polymerization reaction of molecular chain lengthening. The post-polymerizer operates under normal pressure. Heating with gas phase biphenyl, heat exchange with liquid phase biphenyl in the middle and lower parts, and the specially designed built-in heat exchanger is cooled with liquid phase biphenyl to remove the heat released by the reaction, and the heat in the cooling section is recovered for preheating For caprolactam, the upper temperature of the polymerizer after control is 255°C, the melt discharge temperature is 250-260°C, the residence time of the polymer is about 10 hours, and the viscosity of the polymer when it exits the polymerizer can reach 2.4-3.5. This equipment The special structure can ensure that the product flows evenly in it. The factory can control the vacuum degree of post-polymerization production according to the market's demand for product specifications, so as to produce polymer chips with different viscosities. When the reaction is carried out in the pressurized polymerizer and the post-polymerizer, water and caprolactam are evaporated, and the steam is distilled through the fractionating tower, and the solution containing caprolactam is sent to the caprolactam water concentration process through the fractionating tower, and the steam at the top of the tower is condensed and discharged to sewage treatment station processing, The material at the bottom of the post-polymerization reactor is discharged by a melt discharge pump. The pump sends the heated polymer pipeline to the melt filter and the injection head. The melt filter is a non-stop filter, and the filter can be switched when necessary. When the filter is used, the backup filter can be activated by switching the valve, 4. Diced The molten polymer is extruded from the small hole on the casting head, cooled, solidified and shaped by the cooling water sprayed continuously on the cooling plate of the underwater pelletizer, and finally cut into uniform particles by the pelletizer, sliced After the unqualified slices and surface moisture are separated by a vibrating screen, they fall into the pre-extraction tank. After the granulation is completed, the granulation cooling water flows into the granulation water storage tank, is pumped out by the granulation water circulation pump, and sent to the granulation water filter to filter out solid particles, and the granulation water cooler is cooled to 16°C by 7°C chilled water. ℃ sent back to the granulator for recycling, The monomer steam at the casting head and the monomer steam at the pelletizer are sucked out by the suction jet pump, and the jet water of the suction jet pump is provided by the jet water circulation pump, and the jet water circulation pump draws the jet water from the cutting water storage tank and sends it into the Suction jet pump, after absorbing the monomer, the jet water flows into the granulation water storage tank for repeated use, The frequency converter of the underwater granulator motor is linked with the frequency converter of the discharge gear pump motor, so that the granulator can be automatically adjusted according to the flow rate of the polymer to keep the machine working in the best condition. 5. Continuous extraction The slices fall from the vibrating screen into the pre-extraction water tank. After the slices are pre-extracted in the pre-extraction water tank, the material is quantitatively discharged through the rotary lock supply valve at the bottom of the tank. The slices and water are pumped out by the slice mud pump and sent to the extraction machine. The drainer at the top of the tower, after separating a large amount of water, the slices fall into the extraction tank, the desalted water for extraction is extracted from the extraction water tank by the extraction water circulation pump, and the solid particles are filtered out by the extraction water filter, and then passed through the extraction water heater. It is heated by 0.3MPa steam to 97°C and enters the extraction tower from the lower part of the tower. The slices are in countercurrent contact with water in the extraction tower. According to the production capacity of the device, the extraction tower is equipped with a primary extraction tower, a secondary extraction tower and a tertiary extraction tower, etc. Single-stage extraction or multi-stage extraction. The multi-stage extraction is basically the same as the single-stage extraction process, but the single-stage extraction is repeated. In principle, the extraction temperature of the latter stage of process control is higher than that of the previous stage of extraction. The mixing ratio of slices and water is controlled by adjusting the amount of fresh desalted water added. The bath ratio is 1:1. The slices stay in the extraction tower for about 24 hours, and the extractable content in slices is reduced from 10% to 0.5%. Next, the qualified slices are continuously discharged through the rotary locking feed valve at the bottom of the tower, and then the slices and water are sent to the dehydrator on the top of the drying tower by the slice cement slurry pump, and the slices fall into the drying tower after the water is separated. The water separated from the dehydrator and the supplemented desalinated water flow into the extraction water seal tank together, and the coil inside the extraction water seal tank is fed with 0.3MPa steam to heat the temperature of the extraction water to about 95°C, and the extraction water flows from the extraction water seal tank It is discharged from the top and flows into the extraction water tank from the upper part, where the gas entrained in the water is discharged outside and the liquid level of the extraction water tank is controlled to be 500mm higher than the liquid level of the extraction tower. Lock the feed valve to provide water for slice transportation, all the way into the extraction water circulation pump, filtered by the extraction water filter, and then heated by 0.3MPa steam to 98°C through the extraction water heater, enter the extraction tower from the lower part of the tower, and contact with the slice countercurrently, Extract the monomers and oligomers, The extraction water with a monomer concentration of about 7.5% flows out from the upper part of the primary extraction tower, merges with the water discharged from the drainer, flows into the rotary lock supply valve all the way to provide water for slice transportation, and flows into the bottom of the pre-extraction water tank all the way, from the pre-extraction water tank. The monomer concentration of the extracted water flowing out from the upper part of the extraction water tank is about 10%, and it is sent to the extraction water tank for storage, which is used for recovering caprolactam. In the pre-extraction water tank and the extraction tower equipment, a multi-layer high-efficiency, no stagnation area and tower internals that strengthen the full contact between the extraction water and the slices are set. The pre-extraction water tank is equipped with a heating jacket, and 0.05MPa is introduced into the jacket The low-pressure steam heating is used to maintain the temperature of the pre-extraction water. There is a special built-in heater at the bottom of the extraction tower, which is heated by 0.3MPa low-pressure steam to facilitate the adjustment of the extraction temperature and ensure the extraction efficiency of oligomers. , 6. Continuous drying The slices coming out of the dehydrator have a moisture content of about 8-15%, and enter the drying tower from the top. According to the production capacity of the device, set up a drying tower system or two parallel drying tower systems. The hot nitrogen used for drying is divided into two The strands are fed into the tower from the bottom and middle of the tower. The hot nitrogen gas added to the upper part is mainly used to dry the surface moisture of the slices and heat the slices. The hot nitrogen gas added to the lower part removes the residual moisture of the slices and heats the polymer to increase its molecular weight. The slices stay in the drying tower for about 24 hours, and the water content of the slices is below 0.06% when they leave the drying tower. Next, after the slices are cooled to the qualified temperature, they are sent to the slice mixing bin through the air conveying device. Nitrogen comes out from the top of the drying tower, and after being pressurized by the first nitrogen circulation fan, part of the nitrogen is heated to 130°C by the nitrogen heater (E-1401) by 1.0MPa steam and then enters the drying tower from the middle, and the other part of the nitrogen enters the nitrogen for heat exchange After exchanging heat with the cold nitrogen from the top of the cooling tower, it enters the tower from the lower part of the cooling tower, and contacts with the spray cooling water added from the upper part of the tower in countercurrent. After entering the nitrogen heat exchanger and exchanging heat with high-temperature nitrogen, it enters the second nitrogen circulation fan. After pressurization, it enters the nitrogen deoxidizer. The nitrogen heater is heated to 125°C by 1.0MPa steam, and enters the drying tower from the lower part for recycling. The spray water at the bottom of the cooling tower is sent to the spray water cooler by the spray water circulation pump to cool down to 12°C and then circulated back to the upper part of the cooling tower and sprayed to the bottom, cooling the wet nitrogen diverted from the top of the drying tower to cool down the excess condensed water Overflow from the cooling tower to the water seal tank, and then overflow to the outside, The cooling nitrogen is sent to the nitrogen cooler by the third nitrogen circulation fan, cooled by circulating water, and then sent to the lower part of the slicing cooling bin. The nitrogen is discharged from the top of the equipment from bottom to top, and circulates back to the third circulation after being dedusted by the dust filter. fan, Solid-phase post-polycondensation can also be carried out in the drying tower, but the temperature of nitrogen is required to be higher, and the residence time of the chips is longer. When performing solid-phase post-polycondensation, all the nitrogen gas from the top of the drying tower must be sent to the cooling tower for washing. 7. Slice delivery and packaging The pulse conveying tank located under the slice cooling silo is used to transport the slices to the slice mixing silo and the slice storage silo. The finished slices can be measured and packaged by the packaging machine under the slice mixing silo or the slice storage silo, and packed into 750kg big bags or 25kg small bags are put into storage for export, Optional: The pulse conveying tank under the chip mixing silo is used to transport the chips to the chip storage silo or directly to the spinning silo for spinning, Unqualified slices are directly sent to the packaging system for individual packaging, Nitrogen for transportation is recycled, and then sent to the pulse conveying tank after being pressurized by the bag filter, nitrogen compressor and circulating nitrogen storage tank. 8. Evaporation of extraction water The extraction water containing caprolactam and oligomer concentration of about 10% sent from the pre-extraction water tank of the extraction process flows into the extraction water tank, is pumped out by the extraction water feeding pump, filtered, and sent to the first-effect evaporation tower and the first-effect reboiler The heat source is provided by the secondary steam of the second-effect evaporation tower. The extracted water is heated to 80°C and enters the first-effect evaporation tower. The operating pressure of the tower is 0.04MPa. The reflux liquid collection tank, the condensate of the first-effect reboiler is also collected into the reflux liquid collection tank, part of the condensate is pumped into the first-effect, second-effect, and third-effect evaporation towers for reflux through the reflux pump, and the rest of the condensate is returned to the extraction process for extraction For water use, the closed-circuit circulation of water is realized. The non-condensable gas is pumped out by the vacuum pump to maintain the negative pressure operating condition at the top of the tower. After the first-effect evaporation, the concentration of the extracted water at the bottom of the tower is increased to 15%, and it is pumped out by the caprolactam water pump to the second-effect evaporation tower. , The heat source of the second-effect reboiler is provided by the secondary steam of the three-effect evaporation tower. The extracted water is heated to 98°C and enters the second-effect evaporation tower. The operating pressure of the tower is 0.08MPa (absolute pressure). Used as the heat source of the first-effect reboiler, the condensate of the second-effect reboiler is also collected into the reflux liquid collection tank, after the first-effect evaporation, the concentration of the extracted water at the bottom of the tower is increased to 25%, and it is pumped out by the caprolactam water pump to the third-effect evaporation tower, The extracted water from the second effect is heated to 138°C by 1.0MPa steam through the three-effect reboiler, and the operating pressure of the three-effect evaporation tower is 0.04MPa. The extracted water is concentrated to about 80% in this tower, and the concentrated caprolactam aqueous solution passes through the The 0.3MPa steam-insulated jacketed pipe flows into the caprolactam water feeding tank from the bottom of the tower. 9. Concentrate post-treatment 80% of the concentrated solution is stored in the caprolactam water feeding tank, which is forced to circulate by the concentrated liquid circulation pump. The caprolactam water feeding tank and the circulating pipeline are insulated by 0.3MPa steam, and part of the concentrated liquid is pressurized to 2.9MPa by the concentrated liquid feeding pump. The concentrate heater is heated to 250°C and enters the cracking reactor for post-treatment. The treated concentrate is mixed with fresh caprolactam in proportion to the pressure difference and enters the pressurized polymerizer for polymerization reaction to realize the closed loop of caprolactam. The heat required for the aftertreatment of the concentrated liquid is supplied by the biphenyl steam at 275°C. After the biphenyl steam is condensed, it is re-evaporated and recycled in the biphenyl evaporator with a liquid-phase heat medium (heated at 20°C, 10. Hot water system The hot water from the hot water return main pipe is sent to the hot water heater through the hot water circulation pump, heated to the required temperature by 0.3MPa steam, and then circulated to each hot water user. After the hot water circulation pump, it is divided into another branch through After the hot water cooler is cooled to the required temperature, it is used by users who need low-temperature hot water. The return water main pipe needs to be connected to the hot water expansion tank. 11. Steam condensate The steam condensed water of each steam user is sent to the condensed water collection tank through the condensed water main pipe at different pressure levels, and the steam condensed water of the users in the melting workshop is sent back by the condensed water recovery pump, and the condensed water collecting tank is equipped with a special heat exchanger for recovery of superheated condensation The water heat, the condensed water in the collection tank is pumped to the boiler room by the condensed water, 12. Biphenyl dosing and collection The liquid phase biphenyl is stored in the biphenyl collection tank, and is sent to various users through the biphenyl feed pump. A condensation device is installed on the outlet pipe of the biphenyl collection tank, and the gas phase biphenyl is cooled by cooling water and air, and the non-condensable gas Discharged through a high point, Each gas-phase biphenyl system is a self-contained system, which is fed and discharged from the bottom of the gas-phase furnace, condensed biphenyl is also returned from the bottom, and gas-phase biphenyl is discharged from the top of the furnace to each user point. A safety valve is installed on the gas-phase system. The highest point is equipped with a biphenyl vapor-liquid separation tank, and the non-condensable gas is discharged from the top of the vapor-liquid separation tank to the biphenyl collection tank from time to time, and the condensate is returned to the gas phase furnace. The liquid phase biphenyl system consists of a biphenyl circulation pump, a heater and a biphenyl expansion tank. The two sets of liquid phase biphenyl systems in the postpolymerizer share a biphenyl expansion tank. The high point of the system is equipped with an exhaust line connected to the expansion tank. The expansion tank is equipped with manual exhaust and safety valve, the biphenyl feeding of the liquid phase system is set on the upper part of the expansion tank, the discharge pipeline is set at the lowest point of the system, and the outlet pipeline of the heater is set with a safety valve. The discharge pipeline of each system and the discharge pipeline of the safety valve are all connected to the biphenyl collection tank. 13. Primary heat medium heating system The heating system of the pressurized polymerizer, post-polymerizer and cracking reactor, regardless of the vapor phase or liquid phase, is heated by a primary heat medium, The primary heat medium is modified terphenyl or biphenyl-biphenyl ether. If biphenyl-biphenyl ether is used, the primary heat medium system needs to be pressurized. To each user, the heat medium discharged by each user is pumped to the heat medium heating furnace for heating through heat medium circulation, so as to realize the recycling of heat medium. And exhaust, the low point is equipped with a heat medium discharge tank, 14. The process control system of the device The process control of the whole device is completed by a general distributed control system, which has redundancy in communication function and process control function. Slice air conveying system and underwater granulator system and other complete sets of supply equipment are also equipped with on-site control cabinets.

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