CN210595877U - Production single line 165 tons of level nylon-6 polymerization systems - Google Patents

Abstract

The utility model provides a production single line 165 tons of level nylon-6 polymerization systems, the utility model discloses polymerization systems only includes a preceding polymerization reactor, a back polymerization reactor, a preceding melt pump that gathers, a back melt pump that gathers, a pelleter under water, a section water storage tank, an extraction tower, an extraction rotary valve discharger, a drying tower, a dry rotatory bleeder valve, a section cooling feed bin, a section sending system, realized that back gathers the melt bleeder pump, the pelleter, the extraction tower, the drying tower, section water centrifuge, the single operation of single line such as drying tower, make the technology operation more simple and convenient, production efficiency is higher, overcome and all had work load increase of different degrees in the aspect of arranging in the place in the current nylon polymerization technology, workman's operation, the equipment maintenance, equipment investment etc. defects such as increase, one-time investment increase.

Description

Production single line 165 tons of level nylon-6 polymerization systems

Technical Field

The utility model particularly relates to a nylon polymerization technical field, concretely relates to production single line 165 tons of level nylon-6 polymerization systems.

Background

The nylon as one important member of synthetic fiber family has nylon-6 chip produced with caprolactam as the upstream material, and the nylon-6 chip producing process in the world is mainly caprolactam hydrolyzing polymerization process, including one section of normal pressure polymerization process and two-section polymerization process with pressurized front section and depressurized back section, including liquid or molten solid caprolactam as material, monobasic acid of acetic acid, benzoic acid, etc. or dibasic acid of adipic acid, terephthalic acid, etc. as chain terminator for caprolactam polymerization, pure desalted water as ring opener for caprolactam to produce high temperature hydrolyzing polymerization, pelletizing, extracting, drying, cooling and packing.

The nylon-6 polymerization production line in China introduces foreign process technology from the 80 th century, and the single-line capacity is from 10 tons/day ↗ 15 tons/day ↗ 25 tons/day ↗ 40 tons/day ↗ 65 tons/day ↗ 100 tons/day ↗ 150 tons/day ↗ 200 tons/day ↗ 260 tons/day ↗ 390 tons/day 36390 tons/day, until the Taiwan Libao dragon has 500 tons/day production line put into operation.

Engineering companies of process technology introduced from abroad mainly comprise three families, namely Swiss EMS, German Lugir and German PE, wherein the maximum capacity of the Swiss EMS single line is 200 tons/day, the maximum capacity of the German Lugir single line is 390 tons/day, and the maximum capacity of the German PE single line is 150 tons/day.

The Swiss EMS single line production capacity is more than 150 tons/day production line flow:

prepolymerization reaction → final polymerization reaction → granulation (two granulators connected in parallel) → extraction (two-way discharge) → drying (two drying towers connected in parallel) → slice conveying (two conveying in parallel);

the German Lugir single line production capacity is more than 150 tons/day production line flow:

prepolymerization reaction → final polymerization reaction → granulating (two granulators are connected in parallel) → first-stage extraction → second-stage extraction → third-stage extraction (two-way discharge) → drying (two drying towers are connected in parallel) → slice conveying (two conveying are connected in parallel);

germany PE single line maximum production energy 150 ton/day production line flow:

prepolymerization reaction → final polymerization reaction → granulation (two granulators connected in parallel) → extraction (two extraction towers connected in parallel) → drying (two drying towers connected in parallel) → slice conveying (two conveying towers connected in parallel);

the three foreign nylon-6 engineering companies have the following disadvantages and shortcomings:

as can be seen from the process flow diagrams of the three companies, the process steps from the granulating step to the extracting step, the drying step and the slicing conveying step are all realized by connecting two or more sets of process equipment in parallel or in series to meet the production requirement.

1. Two nylon-6 grain cutters need two nylon-6 melt discharge pumps and two sets of melt filters, and the workload and the one-time investment are increased to different degrees in the aspects of site arrangement, worker operation, equipment maintenance, equipment investment and the like.

2. Increases the flow complexity of the nylon-6 slice extraction process and the adjustment in the system pipeline

The number of valves, flow meters, thermometers and pipes increases with the number of extraction columns in series.

The number of the single-line extraction process equipment is increased along with the number of the extraction towers which are connected in series (or in parallel), and each stage of extraction tower which is connected in series (or in parallel) needs to be provided with a corresponding extraction water circulating pump, an extraction water filter, a slice cement slurry pump, a slice rotary discharge valve, an extraction water heater, an extraction water degassing tank and the like.

And as the number of the extraction towers connected in series (or in parallel) is increased, the number of related operating equipment is increased, and the daily maintenance workload and the equipment failure rate of the equipment are correspondingly increased.

And because the multiple towers are operated in series (or in parallel), and the extraction water and the slices run in a countercurrent way, the water balance of the extraction water circulating system is not easy to control, the operation difficulty is improved, the extraction water circulating system is more sensitive to the change of process conditions, and the stability of the quality of the slices is not facilitated.

6. Due to the combination of the multi-stage extraction towers, the civil construction area of a factory building is increased, and the initial fixed asset investment is increased.

7. The flow complexity of the nylon-6 slice drying process is increased, and the system pipeline is adjusted

The number of valves, flow meters, thermometers and pipes increases with the number of parallel drying towers.

The number of the single-line drying process equipment is increased along with the number of the drying towers which are connected in parallel, and when one drying tower is connected in parallel, a corresponding drying nitrogen circulating fan, a dust filter, a slice rotating discharge valve, a nitrogen heater and the like are required to be added.

And as the number of the parallel drying towers is increased, the number of related operating equipment is increased, and the daily maintenance workload and the equipment failure rate of the equipment are correspondingly increased.

And because the multiple towers are operated in parallel, the technological working conditions of each drying tower are inconsistent, the difference of the water content of the dry slices of the final product is large, different product batch numbers are generated, and the requirements of the slicing users on the uniformity of the slice indexes are not facilitated.

11. Due to the combination of a plurality of drying towers, the civil construction area of a plant is increased, and the initial fixed asset investment is increased.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical defects existing in the prior art, the utility model provides a production single line 165 tons of nylon-6 polymerization systems.

The utility model discloses a technical solution be: the utility model provides a production single line 165 tons of level nylon-6 polymerization systems, includes caprolactam feed system, preceding polymerization ware, melt pump, back polymerization ware, cast belt pump, fuse-element filtration eager grain and eager grain water circulating system, section water blending tank, extraction tower, centrifugal dehydrator, drying tower, cooling feed bin, section conveying system and section packaging system in proper order, the fuse-element filter eager grain and eager grain water circulating system in the pelleter be single pelleter, extraction tower and drying tower be single tower, section conveying system carry for the single line section, the extraction tower be single-stage extraction tower.

The caprolactam feed system comprises a caprolactam feeding adjusting valve, a titanium dioxide metering pump, an ADX metering pump, an ADY metering pump and an automatic control system, wherein the caprolactam feeding adjusting valve, the titanium dioxide metering pump, the ADX metering pump and the ADY metering pump automatically calculate the feeding amount of each component and feed the components according to the material proportion of a DCS program calculation formula by the automatic control system.

The top of the front polymerization reactor is provided with a packed tower and a condenser which distills the caprolactam-containing water vapor discharged from the top of the front polymerization reactor in the tower and condenses and refluxes the caprolactam-containing water vapor to the front polymerization reactor.

The front polymerizer is connected with a dehydrator at the upper part of the back polymerizer through a melt pump.

The upper part of the post polymerization reactor is heated by a vapor phase biphenyl heater 301-E-24, and the middle and lower parts of the post polymerization reactor control the heat preservation of liquid phase biphenyl and remove the reaction heat of polycondensation reaction by the biphenyl heater 301-E-26 and a biphenyl circulating pump 301-P-26.

The condenser is connected with the slice water mixing tank through a vacuum water-sealed tank.

Melt filtration cut grain and cut grain water circulating system include BKG under water earnestly cutting machine, gear pump, melt filter, hydroextractor in proper order, melt filter include the one-level cut grain water coarse filtration ware, the second grade cut grain water fine filtration ware.

The chip conveying system comprises a blower or compressor for pressurizing pure nitrogen, a filter for separating polymer dust from the gas at the feed end, a cooler for removing heat generated by compression at the discharge end and a special pulse conveyor for distributing chips.

A polymerization process for producing single-line 165-ton nylon-6, comprising the steps of:

(1) prepolymerization reaction: the method comprises the following steps of feeding caprolactam melt at 85 ℃ into a caprolactam preheater, heating the caprolactam melt to 180 ℃ by liquid phase biphenyl discharged from a coil pipe at the lower part of a rear polymerizer, feeding the caprolactam melt into a front polymerizer together with additives sent by a titanium dioxide metering pump, an ADX metering pump and an ADY metering pump, wherein the heat required by a ring opening reaction is provided by gas phase biphenyl heated by a biphenyl evaporator, the heating temperature of the gas phase biphenyl of the upper biphenyl evaporator is controlled within the range of 230-290 ℃ according to different yields, the heating temperature of the gas phase biphenyl at the lower part is usually controlled within the range of 265-285 ℃, the material temperature at the upper part of the front polymerizer is controlled within the range of 240-275 ℃, the temperature at the middle part of the front polymerizer is influenced by the temperature at the upper part, the temperature at the 255-275 ℃ is the highest in the heat release stage of the polymerization reaction at the lower part of the front polymerizer, the temperature is usually 3-5 ℃, the, the higher operating pressure is favorable for ensuring the water required by the ring-opening reaction of caprolactam, improving the polymerization reaction speed and reducing the generation of low molecular weight substances, the relative viscosity of the final material at the lower part of the front polymerization part is 1.3-1.8, and the front polymerization material is conveyed into a dehydrator at the upper part of the rear polymerization reactor by a front polymerization discharge pump to remove part of the water and then enters the rear polymerization reactor;

(2) final polymerization reaction: in the decompression polymerization stage, water generated by polycondensation is removed, so that the molecular chain of the polymer can be increased to a required length, the rear polymerizer mainly performs polymerization reaction with the molecular chain being lengthened, and the molten polymer with the molecular weight reaching the process requirement at the bottom of the rear polymerizer is pumped to a pelletizing section through a discharge gear. The post-polymerizer is operated by reducing pressure, the upper part of the post-polymerizer is heated by a vapor phase biphenyl heater, the temperature of vapor phase biphenyl is controlled to be 255-275 ℃, the temperature of materials at the upper part is controlled to be 250-265 ℃, the middle and lower parts are insulated by liquid phase biphenyl and the reaction heat of polycondensation is removed, wherein the temperature of a heat removing section is controlled by the biphenyl heater and a biphenyl circulating pump, the temperature of the liquid phase biphenyl at the heat removing section is usually controlled to be 235-245 ℃, the temperature of the materials is controlled to be 230-248 ℃, the post-polymerization lower part belongs to a balancing stage, the temperature is usually realized by the biphenyl heater and the biphenyl circulating pump, the temperature of the liquid phase biphenyl at the part is usually controlled to be 230-245 ℃, the temperature of finally post-polymerized discharged polymers is also 230-245 ℃, the relative viscosity of the post-polymerized discharged materials is 2.20-2.30, the post-polymerized materials are discharged by a melt filter, and gel particles, titanium dioxide coarse particles and, the method comprises the following steps of (1) entering a grain cutting working section for grain cutting, distilling water generated in a polycondensation reaction through a packed tower to enable most caprolactam to flow back to a post-polymerizer, condensing water vapor containing trace caprolactam from the top of the tower in a partial condenser, using the condensed liquid as reflux, further condensing the uncondensed water vapor in a steam condenser, discharging the uncondensed water vapor into a grain cutting water storage tank through a vacuum water sealing tank, controlling the operation pressure of the post-polymerizer through a discharge control valve of post-polymerizer packing and a vacuum unit, and finally discharging the post-polymerizer until the relative viscosity of the discharged material reaches 3.0-3.5;

(3) pelletizing and pelletizing water circulation: the rear gathered material is granulated through a BKG underwater hot cutter, the melt is conveyed through a gear pump and filtered by a melt filter to remove impurities, then the melt is extruded through a BKG die orifice plate, the melt is granulated through a rotary cutter head of a BKG granulator, the cut spherical slice is directly conveyed to a dehydrator, after the slice is separated from water and dried, the ultra-long type in the slice is unqualified and separated through a vibrating screen, the qualified slice enters a pre-extraction tank through a screen, the granulation circulating water at 45 ℃ of the granulator die head returns to a granulation water storage tank, the granulation circulating water is filtered through a primary granulation water coarse filter and a secondary granulation water fine filter, then the granulation circulating water is cooled to 40 ℃ through 32 ℃ cooling water of a plate heat exchanger, the granulation circulating water returns to a granulation material cavity to cool the melt again, and;

(4) continuous extraction of slices: the slices fall into a pre-extraction tank from a vibrating screen, the slices move from top to bottom under the action of gravity and fully contact with countercurrent extraction water, the slices are conveyed to a slice water separation tank at the top of an extraction tower through a slurry pump and a rotary discharger at the bottom of the pre-extraction tank, wherein the slices fall into the extraction tower after being separated, the water and overflow water of the extraction tower return to a pre-extraction degassing tank together, in order to improve the extraction effect, after the slice conveying water and the overflow water of the extraction tower are converged, one part of the water is conveyed to the bottom of the pre-extraction tank to be used as extraction inlet water for pre-extraction, the other part of the water is used as slice conveying water of the rotary discharger at the bottom of the pre-extraction tank, the slices move from top to bottom and fully contact with the countercurrent extraction water at the top of the extraction tower for extraction, monomers and oligomers in the slices are taken away by countercurrent extraction hot water, conveying water is sent back to be recycled, four circulating water paths and one extracting water cooling are arranged in an extraction tower, the circulating water paths are used for increasing the mass transfer effect of slices and water in the extraction tower and reducing the radial temperature difference of the slices and the water in the extraction tower, the water temperature distribution of the extraction tower is gradually reduced from bottom to top, the temperature difference of each temperature point is about 1-3 ℃, the temperature of the lowest temperature point of the extraction tower is usually not less than 130 ℃, the temperature of the uppermost temperature point of the extraction tower is not more than 100 ℃, if the water temperature of the extraction tower does not meet the process requirement, jacket steam of the extraction tower can be opened for auxiliary heating, the auxiliary heating standard is that the temperature of the upper part of the extraction tower is not more than 85 ℃, the slices conveyed to a centrifugal dehydrator by the extraction tower are dehydrated, and the water content of;

(5) and (3) continuously drying the slices: and (3) dehydrating the slices with the water content of less than or equal to 10% from the extraction section through a centrifugal machine, drying the slices with nitrogen airflow, discharging the nitrogen from the top of the drying tower, pressurizing the nitrogen by a first circulating fan, heating a part of the nitrogen to the required temperature of 105-120 ℃ by steam through a nitrogen heater, and feeding the nitrogen into the drying tower from the upper part at the flow rate of 20000-40000 m 3/h. The other part of nitrogen enters a nitrogen heat exchanger to exchange heat with nitrogen from a spray water cooler, enters a tower from the lower part of a cooling tower to be in countercurrent contact with spray water added from the upper part of the tower, is cooled to 10-15 ℃, is washed and then comes out from the top of the tower, exchanges heat through the nitrogen heat exchanger, enters a nitrogen deoxygenator to be deoxygenated, enters a second circulating fan and a third circulating fan to be pressurized, is heated to a required temperature of 105-130 ℃ through a nitrogen heater, the nitrogen flow is 7000-20000 m3/h and respectively enters a drying tower from the middle part and the lower part for recycling, hot nitrogen for drying is added into the tower from the bottom of the tower and the middle part of the tower in three strands, the temperature of the hot nitrogen added in the middle part is 110-120 ℃ and is mainly used for removing moisture on the surface of the slices and heating the slices, the temperature of the hot nitrogen added in the lower part is 105-120 ℃ to remove residual moisture, the method comprises the following steps that slices of a drying tower are continuously sent to a slice cooling bin through a rotary discharging valve, the speed of the rotary discharging valve is automatically controlled by the slice material level of the drying tower, when the slice material level of the drying tower is low and gives an alarm, and when the slice material level of the cooling bin is high and gives an alarm, the rotary valve is interlocked and stopped to operate, hot slices are cooled by cooled nitrogen in the cooling bin and then the temperature of the hot slices is reduced to be below 45 ℃, the cooled slices are sent to a slice packaging bin through a pneumatic conveying system to be packaged, the final water content of the dried slices is less than or equal to 0.06%, the slices are purple under ultraviolet light, and oxidized slices are white under the ultraviolet light;

(6) conveying the slices: and the pulse conveying tank arranged below the cooling bin conveys the slices to a slice-cutting loading bin under the protection of pure and clean nitrogen, and the slices fall into a packaging machine through the slice-transition bin by gravity for quantitative bagging and delivery.

The utility model has the advantages that: the utility model provides a polymerization system for producing single line 165 ton nylon-6, which comprises only a front polymerization reactor, a rear polymerization reactor, a front melt-gathering pump, a rear melt-gathering pump, an underwater granulator, a sliced water storage tank, an extraction tower, an extraction rotary valve discharger, a drying tower, a drying rotary discharge valve and a sliced cooling bin, a section sending system realizes single-line single-station operation of a post-polymerization melt discharge pump, a granulator, an extraction tower, a drying tower, a section water centrifuge, a drying tower and the like, so that the process operation is simpler and more convenient, the production efficiency is higher, and the defects of workload increase, one-time investment increase and the like of different degrees in the aspects of field arrangement, worker operation, equipment maintenance, equipment investment and the like in the conventional nylon polymerization process are overcome.

Drawings

Fig. 1 is a schematic view of the polymerization system of the present invention.

FIG. 2 is a flow chart of the polymerization process of the present invention.

Detailed Description

Now, the utility model is further explained with reference to fig. 1 and 2, the process flow of the single line 165 ton/day production line of the utility model is as follows:

prepolymerization reaction → final polymerization reaction → granulating and granulating water circulation (single station) → continuous extraction of chips (single tower) → continuous drying of chips (single tower) → conveying of chips (single line)

The simplification of production line equipment and flow is realized, the equipment investment is saved, and the process operation efficiency is higher.

The utility model provides a production single line 165 tons of grades of nylon-6 polymerization systems, includes caprolactam feed system, preceding polymerization ware, melt pump, back polymerization ware, cast belt pump, fuse-element filtration grain and cut grain water circulating system, section water blending tank, extraction tower, centrifugal dehydrator, drying tower, cooling feed bin, section conveying system and section packaging system in proper order, the pelleter be single pelleter, extraction tower and drying tower be single tower, section conveying system carry for the single line section, the extraction tower be single-stage extraction tower.

A single-line 165-ton/day nylon-6 polymerization production line is followed by a melt discharge pump with a Mago Meyer specification of TR125-6GU-2, the capacity of the pump per hour can reach 7500KG/H, and the requirements on discharge flow and pressure are completely met.

The single-line 165 ton/day nylon-6 polymerization production line pelletizing system adopts a pelletizer with the German BKG specification of AHD300, the pelletizer is an underwater hot cutting machine, the pelletizer is cooled by using circulating water of 42 degrees, no chilled water is needed, the capacity of the pelletizer can reach 180 tons/day, the operation is simple, the occupied area is small, and the energy-saving benefit is considerable because no chilled water is used.

The slice water tank for the single-line 165-ton/day nylon-6 polymerization production line discharges a slice rotary discharger which is produced by Wenzhou bang deer chemical industry limited and has the specification and model number WZBL-QL- - -LX-1, and the rotary valve can meet the conveying requirement of 200 tons of slices produced per day.

The diameter of an extraction tower of a single-line 165 ton/day nylon-6 polymerization production line is 2400-3200 mm, the height of the extraction tower is 40-52m, the effective extraction residence time of the slice in the extraction tower is more than 20 hours, the bottom temperature of the extraction tower can reach 120-145 ℃, and the final extractable matter content of the slice is less than or equal to 0.4%.

The extraction tower of the single-line 165 ton/day nylon-6 polymerization production line adopts a slice rotary discharger of specification type WZBL-CQ- - -LX-1 produced by Wenzhou bang deer chemical company Limited, and the rotary valve can meet the conveying requirement of 200 tons of slices per day.

The single-line 165-ton/day nylon-6 polymerization production line slicing water centrifuge adopts a slicing rotary discharging device of specification model GCD-424A produced by Wenzhou bang deer, the rotary discharging device can meet the dehydration requirement of 165-ton daily-produced slices, and the water content of the final slices is less than or equal to 4%.

The diameter of a drying tower of a single-line 165 ton/day nylon-6 polymerization production line is 4200-5500 mm, the height of the drying tower is 20-35m, the effective residence time of the slices in the drying tower is more than 24 hours, the bottom temperature of the drying tower can reach 150-165 ℃, the solid-phase tackifying of the high-viscosity slice production can be realized, and the final water content of the slices is less than or equal to 0.05%.

The single-line 165 ton/day nylon-6 polymerization production line drying tower adopts a rotary discharger which is produced by Wenzhou bang deer chemical industry Limited and has the model specification of WZBL-GZ-LX-1, the maximum rotating speed of the rotary discharger is 11 r/min, and the capacity can meet the requirement of 200 ton/day.

The single-line 165-ton/day nylon-6 polymerization production line chip conveying system adopts powder conveying equipment with the Kanbergs model specification of PA6-CS-N2CL, and can completely meet the capacity requirement required by conveying.

Caprolactam feeding metering system

The feeding metering system is a proportion control system, the materials prepared from liquid caprolactam storage, titanium dioxide preparation, ADX and ADY are all automatically added according to the material proportion of a DCS program calculation formula, then the respective added amounts are realized through the automatic control of a caprolactam feeding adjusting valve, a titanium dioxide metering pump, an ADX metering pump and an ADY metering pump, the material flow of the whole metering system is in dynamic balance, the flow of the titanium dioxide, the ADX and the ADY changes proportionally along with the change of the caprolactam flow, the flow of the caprolactam changes along with the material level change of a pre-polymerization reactor, when the current polymerization material level is subjected to high-level alarm, the feeding metering system automatically stops running, and the aim is to prevent the polymerization tower material level from being too high. If the adding amount ratio of the additive is changed, the set data is modified in the calculation formula.

The start-up sequence of the feeding system is to start caprolactam for feeding, then start ADX, ADY and titanium dioxide in sequence, and the stop sequence is opposite to the start-up sequence.

Pre-polymerization system

And in the pressurized polymerization stage, the hydrolysis ring-opening reaction of caprolactam is mainly completed, and the addition polymerization reaction is started at the same time. The caprolactam melt liquid at 85 ℃ sent by a caprolactam charging pump enters a caprolactam preheater, is heated to 180 ℃ by liquid phase biphenyl from a coil pipe at the lower part of the postpolymerizer, and enters a postpolymerizer together with additives sent by a titanium dioxide metering pump, an ADX metering pump and an ADY metering pump. The upper part of the front polymerizer 301-R-01 mainly carries out ring-opening reaction, the heat required by the ring-opening reaction is provided by gas-phase biphenyl heated by a biphenyl evaporator 301-E-22, the lower part of the front polymerizer 301-R-01 carries out addition polymerization reaction, the heat required by the reaction is provided by gas-phase biphenyl heated by a biphenyl evaporator 301-E-23, the heating temperature of the gas-phase biphenyl of the upper biphenyl evaporator is controlled within the range of 230-290 ℃ according to different output, the temperature required according to different output is also different, generally higher output requires higher heating temperature, the heating temperature of the gas-phase biphenyl of the lower part is generally controlled within the range of 265-285 ℃, and the adjustment can be carried out according to the material temperature of the front polymerizer. The material temperature at the upper part of the front polymerization reactor is generally controlled to be 240-275 ℃, the lower reaction temperature can reduce the generation of low molecular weight substances of a final polymer, the higher reaction temperature can improve the polymerization reaction speed, the temperature at the middle part of the front polymerization reactor can be influenced by the temperature at the upper part, the more proper temperature is 255-275 ℃, the temperature at the lower part of the front polymerization reactor is the highest in the heat release stage of the polymerization reaction, the temperature is generally 3-5 ℃ higher than that at the middle part of the front polymerization reactor, the normal temperature is 250-280 ℃, and the highest temperature of the first start of the polymerization reactor is sometimes more than 300 ℃.

The top of the pre-polymerization reactor is provided with a packed tower, the caprolactam-containing steam discharged from the top of the pre-polymerization reactor is distilled in the tower to make most of caprolactam flow back to the pre-polymerization reactor, the trace caprolactam-containing steam discharged from the top of the pre-polymerization reactor is condensed in a condenser, part of the condensate flows back through a diaphragm metering pump, and part of the condensate flows over a water-sealed tank and is discharged into a grain-sized water storage tank or a recovery system. The condenser is cooled by hot water of 85 ℃, the hot water is cooled by circulating cooling water through a hot water cooler, and the hot water is circulated through a hot water storage tank by a hot water circulating pump. The operation pressure of the pre-polymerization reactor is controlled by controlling the temperature of a pre-polymerization packed tower, the operation pressure of the polymerization reactor provided by the high-speed spinning production line of the process package is 5.0bar (gauge pressure) at most, the operation pressure of the polymerization reactor provided by the conventional spinning production line is 10.0bar (gauge pressure) at most, and the higher operation pressure is favorable for ensuring the moisture required by the ring-opening reaction of caprolactam, improving the polymerization reaction speed and reducing the generation of low molecular weight substances.

The final material relative viscosity (96% concentrated sulfuric acid) at the lower part of the front polymerization part is about 1.3-1.8, and the front polymerization material is sent to a dehydrator at the upper part of the rear polymerization reactor through a front polymerization discharge pump to remove part of water and then enter the rear polymerization reactor.

Postpolymerization system

In the decompression polymerization stage, the water produced by polycondensation is removed to make the molecular chain of the polymer grow to the required length. The post-polymerizer mainly carries out polymerization reaction for lengthening molecular chains, and the molten polymer with the molecular weight reaching the process requirement at the bottom of the post-polymerizer is pumped to a granulating working section through a discharge gear.

The post-polymerizer is subjected to pressure reduction operation, the upper part of the post-polymerizer is heated by a vapor phase biphenyl heater 301-E-24, the temperature of vapor phase biphenyl is controlled to be about 255-275 ℃, the temperature of materials at the upper part is controlled to be about 250-265 ℃, the middle part and the lower part are insulated by liquid phase biphenyl, and the reaction heat of polycondensation reaction is removed. Wherein the temperature of the heat transfer section is controlled by a biphenyl heater 301-E-26 and a biphenyl circulating pump 301-P-26, the temperature of liquid phase biphenyl of the heat transfer section is usually controlled between 235-245 ℃, the temperature of materials is controlled between 230-248 ℃, the rear polymerization section belongs to an equilibrium stage, a certain equilibrium temperature is required to be kept, the temperature is usually realized by the biphenyl heater 301-E-25 and the biphenyl circulating pump 301-P-25, the temperature of the liquid phase biphenyl of the part is usually controlled between 230-245 ℃, the temperature of finally discharged polymers of the rear polymerization is also proper between 230-245 ℃, the higher heat preservation temperature is favorable for increasing the fluidity of melt, the relative viscosity (96 percent concentrated sulfuric acid) of the discharged materials of the rear polymerization is about-2.20-2.30, and the ring-opening polymerization reaction of caprolactam is a reversible chemical equilibrium reaction, so that the discharged polymers of the rear polymerization contain 8-12 percent of incompletely reacted monomers and oligomers, the conversion rate of the polymerization reaction can reach 90 percent generally, and the post-polymerization material is discharged by a gear pump, filtered by a melt filter to remove gel particles, titanium dioxide coarse particles and other impurities with the particle diameter of more than or equal to 10 mu and then enters a granulating section for granulating.

Distilling water generated by the polycondensation reaction by a packed tower to make most caprolactam flow back to a postpolymerizer, condensing water vapor containing trace caprolactam from the top of the tower in a partial condenser, using the condensate as reflux, further condensing the uncondensed water vapor in a steam condenser, discharging the uncondensed water vapor into a granulating water storage tank through a vacuum water seal tank, controlling the operating pressure of the postpolymerization reactor by a discharge control valve and a vacuum unit of the postpolymerization filler, and keeping the polymerization operating pressure after common civil low-viscosity nylon-6 slices at micro positive pressure or micro negative pressure, wherein the micro positive pressure is generally controlled at 5-25 Kpa if the micro negative pressure is generally controlled at-20-60 Kpa if the micro negative pressure is adopted; if the final polymer product is a high-viscosity industrial slice, a higher vacuum degree is required for post polymerization to achieve higher viscosity, the vacuum degree is usually-70 Kpa, and the relative viscosity (96% concentrated sulfuric acid) of the material discharged finally after polymerization can reach 3.0-3.5.

Melt filtering, granulating and granulating water circulation system

The back gathers the ejection of compact and cuts grain through BKG underwater hot cutter, and the fuse-element carries and filters the impurity back through gear pump conveying and fuse-element filter, through BKG die orifice extrusion, cuts grain through BKG pelleter rotary cutter head, and the hydroextractor is directly carried to the ball form section of cutting off, and after the section and separation of water is dry, the unqualified screen cloth separation through the shale shaker in the section, and qualified section passes through the screen cloth and gets into the extraction jar in advance.

Granulating circulating water at 45 ℃ of a granulator die head returns to a granulating water storage tank, is filtered by a primary granulating water coarse filter and a secondary granulating water fine filter, is cooled to 40 ℃ by 32 ℃ cooling water of a plate heat exchanger, returns to a granulating material cavity again to cool a melt, and is recycled.

Continuous extraction of slices

The slices fall into a pre-extraction tank from a vibrating screen, the slices move from top to bottom under the action of gravity and fully contact with extraction water from the upstream to the downstream, the slices are conveyed to a slice water separation tank at the top of an extraction tower through a slurry pump and a rotary discharging device at the bottom of the pre-extraction tank, the slices fall into the extraction tower after being separated, the water and overflow water of the extraction tower return to a pre-extraction degassing tank together, and in order to improve the extraction effect, after the slice conveying water and the overflow water of the extraction tower are converged, one part of the slice conveying water is conveyed to the bottom of the pre-extraction tank to be used as extraction inlet water for pre-extraction, and the other.

The top of the extraction tower is provided with a slice which moves from top to bottom and is fully contacted with the extraction water flowing upwards in a counter-current manner

And (3) extracting, wherein monomers and oligomers in the slices are taken away by hot extraction water flowing up in a counter-current manner, the extracted slices are automatically controlled by the bottom of the extraction tower according to the liquid level, conveyed to a dehydrator for sieving and dewatering and then enter a subsequent drying section, and the conveying water is returned for recycling. The extraction tower is internally provided with four circulating water paths and one extraction water cooling path, and the circulating water paths are used for increasing the mass transfer effect of the slices and the water in the extraction tower and reducing the radial temperature difference of the slices and the water in the extraction tower.

The water temperature distribution of the extraction tower is gradually reduced from bottom to top, the temperature difference of each temperature point is about 1-3 ℃, the temperature of the temperature point at the lowest part of the extraction tower is usually more than or equal to 130 ℃, the temperature of the temperature point at the uppermost part of the extraction tower is less than or equal to 100 ℃, if the water temperature of the extraction tower does not meet the process requirement, jacket steam of the extraction tower can be opened for auxiliary heating, the auxiliary heating standard is that the temperature at the upper part of the extraction tower does not exceed 85 ℃, the steam resistance generated by water boiling can be caused by overhigh temperature at the upper part of the extraction tower, the normal blanking of slices can be caused in serious cases.

In normal extraction operation, the caprolactam and oligomer content of the slices discharged from the bottom of the extraction tower is lower than 0.5 percent (wt), the concentration of circulating water at the upper part of the extraction tower is about 8-12 percent (wt), the higher concentration is favorable for extracting and separating out oligomers in the slices, the concentration of extraction water entering the lower part of the extraction tower is less than or equal to 0.1 percent (wt), the slices conveyed to a centrifugal dehydrator by the extraction tower are dehydrated, and the water content of the slices conveyed to a drying tower is less than or equal to 10 percent (wt).

Continuous drying of the slices

The drying of the chips serves to remove the water absorbed during chip extraction, since excessive water adversely affects chip post-processing, leading to filament flying and end breakage during spinning.

The slices with the water content less than or equal to 10 percent (wt) are dehydrated from an extraction section by a centrifugal machine and are dried by nitrogen airflow, hot nitrogen for drying is added into the tower from the bottom and the middle of the tower in three strands, the temperature of the hot nitrogen added in the middle is 110-120 ℃ and is mainly used for removing the water on the surfaces of the slices, the slices are heated, the temperature of the hot nitrogen added in the lower part is about 105-120 ℃ and can remove the residual water in the slices, so the molecular weight is slightly increased, and the slices can reach the expected drying effect only by staying in the drying tower for enough time. The water content of the dried slices is below 0.05%, the slices of the drying tower are continuously sent to a slice cooling bin through a rotary discharge valve, the speed of the rotary discharge valve is automatically controlled by the slice material level of the drying tower, when the slice material level of the drying tower is low and gives an alarm, and when the slice material level of the cooling bin is high and gives an alarm, the rotary valve is stopped in an interlocking manner, the hot slices are cooled by cooled nitrogen in the cooling bin and then the temperature of the hot slices is reduced to be below 45 ℃, and the cooled slices are sent to a slice packaging bin through a pneumatic conveying system to be packaged.

And (3) discharging nitrogen for drying from the top of the drying tower, pressurizing by a first circulating fan, heating a part of the nitrogen to the required temperature of 105-120 ℃ by steam through a nitrogen heater, and feeding the nitrogen into the drying tower from the upper part at the flow rate of 20000-40000 m 3/h. And the other part of nitrogen enters nitrogen heat exchangers 304-E-09 and 304-E-10 to exchange heat with the nitrogen from a spray water cooler, enters the tower from the lower part of a cooling tower 304-D-08 and is in countercurrent contact with spray water added from the upper part of the tower, is cooled to 10-15 ℃, is washed and then comes out from the top of the tower, exchanges heat through the nitrogen heat exchanger 304-E-09, enters a nitrogen deoxygenator (the oxygen content is less than or equal to 1 ppm), enters a second circulating fan 304-B-02 and a third circulating fan 304-B-03 to be pressurized, is heated to the required temperature of 105-130 ℃ through nitrogen heaters 304-E-06 and 304-E-07, and then enters a drying tower from the lower part of the nitrogen heat exchangers for recycling after the nitrogen flow is 7000-20000 m 3/h. The slice cooling bin is used for reducing the temperature of the slices, because the higher-temperature slices are easily oxidized when exposed to air, and the short-time exposure of the normal-temperature slices to the air has no adverse effect.

The temperature of the top of the drying tower is 70-100 ℃ under the normal drying operation condition, if the temperature of a certain temperature point of the drying tower suddenly drops during normal operation, water is suspected to enter the drying tower or water is introduced into the drying tower by nitrogen after instrument factors are eliminated, the attention of management and operating personnel needs to be attracted, in addition, the problem needing attention of a drying system is the oxygen content of the nitrogen, the oxygen entering the drying system can be sliced and oxidized, generally, the highest oxygen content of the nitrogen at any position of the drying tower is less than 30ppm, the oxygen content of the nitrogen after deoxygenation is required to be less than or equal to 1ppm, and the air tightness of the system needs to be checked once the oxygen content of the nitrogen exceeds a control range.

The nitrogen washing tower 304-D-08 has the functions of cooling, dedusting and dew removal on hot nitrogen, the spray water flow of the nitrogen washing tower of the 165 ton/day polymerization production line is controlled to be about 20-60T/H, the upper part of the nitrogen washing tower is provided with a wire mesh demister and a filler, the function of the nitrogen washing tower is to prevent the moisture entrainment of the nitrogen from influencing the final dew point of the nitrogen to be unfavorable for drying slices, and the spray water cooling is realized by using 7 ℃ chilled water of a public engineering station and a group of plate heat exchangers.

The positive pressure of the whole drying system is guaranteed by supplementing nitrogen, zero leakage cannot be guaranteed due to the air tightness of the drying system, nitrogen is supplemented from an inlet of a cooling fan 304-B-04, nitrogen is supplemented from the lower part of a drying tower, the positive pressure of the drying system is generally controlled to be 8-15 Kpa, excessively high system pressure can cause water seal ultrahigh air leakage of a water seal tank, water needs to be supplemented to the water seal tank at the moment, a water seal liquid column is guaranteed, and the air is prevented from entering the system to oxidize slices.

The final water content of the dried slices is less than or equal to 0.06 percent, the slices are purple under the ultraviolet light, and the oxidized slices are white under the ultraviolet light.

Air flow transport and packaging

The entire system was kept under a blanket of clean, clean nitrogen to prevent moisture re-absorption by the cut pieces. All functions of the system are controlled by an automatic control device without any manual operation.

Each pneumatic chip conveying system is a group of devices composed of the same type of equipment:

-blowers or compressors for pressurization of pure nitrogen;

-a filter for separation of polymer dust from feed end gas;

-a cooler for removing heat generated by compression at the discharge end;

-a dedicated pulse conveyor for distributing the slices (divided into slugs);

the pulse conveying tank arranged below the cooling bin can be used for conveying the slices to a slice conveying bin, and the slices fall into a packaging machine through the slice transition bin by means of gravity for quantitative bagging and delivery.

Conveying nitrogen for recycling, filtering by a bag-type dust collector, cooling by a nitrogen cooler, pressurizing by a fan and a nitrogen compressor, and then conveying to a pulse conveying tank.

The exhaust pressure of a nitrogen compressor for conveying the slices is usually 6bar, the nitrogen pressure of a sending tank is about 1.2-3.0 bar, the nitrogen pressure of a pulse air knife is 1.5-3.0 bar, and usually 1 kg of nitrogen can convey 10-15 kg of slices.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

The skilled person should understand that: although the present invention has been described in accordance with the above embodiments, the inventive concept is not limited to this embodiment, and any modification of the inventive concept will be included in the scope of the patent claims.

It is above only the utility model discloses a preferred embodiment, the utility model discloses a scope of protection does not only confine above-mentioned embodiment, the all belongs to the utility model discloses a technical scheme under the thinking all belongs to the utility model discloses a scope of protection. It should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (8)

1. The utility model provides a production single line 165 tons of level nylon-6 polymerization systems, its characterized in that includes caprolactam feed system, preceding polymerization ware, melt pump, back polymerization ware, cast belt pump, fuse-element filtration grain and cut grain water circulating system, section water blending tank, extraction tower, centrifugal dehydrator, drying tower, cooling feed bin, section conveying system and section packaging system in proper order, fuse-element filtration grain and cut grain water circulating system in the pelleter be single pelleter, extraction tower and drying tower be the single tower, section conveying system for single line section transport, the extraction tower be single-stage extraction tower.

2. The system of claim 1, wherein the caprolactam feed system comprises a caprolactam feed regulating valve, a titanium dioxide metering pump, an ADX metering pump, an ADY metering pump, and an automatic control system, and the caprolactam feed regulating valve, the titanium dioxide metering pump, the ADX metering pump, and the ADY metering pump automatically calculate and feed the addition amount of each component according to the material ratio of the DCS program calculation formula by the automatic control system.

3. The polymerization system of claim 1, wherein the top of the pre-polymerization reactor is provided with a packed column and a condenser for distilling caprolactam-containing vapor discharged from the top of the pre-polymerization reactor and condensing the caprolactam-containing vapor to reflux the pre-polymerization reactor.

4. The polymerization system of claim 1, wherein the front polymerizer is connected to the dehydrator in the upper part of the back polymerizer via a melt pump.

5. The polymerization system for producing single-line 165-ton nylon-6 according to claim 1, wherein the upper part of the post reactor is heated by a vapor phase biphenyl heater 301-E-24, and the middle and lower parts of the post reactor are controlled by a biphenyl heater 301-E-26 and a biphenyl circulating pump 301-P-26 to keep the liquid phase biphenyl warm and remove the reaction heat of the polycondensation reaction.

6. The polymerization system for producing single line 165 ton grade nylon-6 as recited in claim 3 wherein the condenser is connected to the flake water mixing tank through a vacuum water seal tank.

7. The polymerization system for producing single-strand 165-ton grade nylon-6 as claimed in claim 1, wherein the melt filtering, dicing and dicing water circulating system comprises a BKG underwater heat cutter, a gear pump, a melt filter and a dehydrator in sequence, and the melt filter comprises a primary dicing water coarse filter and a secondary dicing water fine filter.

8. The polymerization system of claim 1, wherein the chip conveyor system comprises a blower or compressor for pressurizing pure nitrogen, a filter for separating polymer dust from feed-end gas, a cooler for removing heat generated by compression at the discharge end, and a dedicated pulse conveyor for distributing chips.

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