CN211586499U - Anti-blocking high vacuum system suitable for polycarbonate production - Google Patents

Abstract

The utility model relates to an adaptation polycarbonate production prevent blockking up high vacuum system, this system regards phenol vapour as spraying power medium, utilize the noncondensable gas that produces in the multistage injection condensation subsystem suction polycarbonate condensation polymerization and the final condensation reaction, thereby required vacuum in the formation polycarbonate condensation reaction, noncondensable gas of multistage injection condensation subsystem suction is through liquid ring vacuum pump sending to phenol piece-rate system, a part phenol of separating through phenol piece-rate system is used for supplementing the spray liquid that sprays the condenser of spraying power medium and multistage injection condensation subsystem, a part diphenyl carbonate of separation and condenser exhaust liquid are as the circulation spray medium of condenser, remaining phenol, diphenyl carbonate and oligomer send to polycarbonate production system as raw materials for production. The utility model discloses can provide reliable, stable high vacuum for polycarbonate production, still can realize phenol and diphenyl carbonate's airtight circulation simultaneously, realize production system's waste liquid zero release.

Description

Anti-blocking high vacuum system suitable for polycarbonate production

Technical Field

The utility model relates to a produce vacuum technique specifically is a high vacuum system, mainly used chemical industry field are prevented blockking up of adaptation polycarbonate production.

Background

Several chemical reactions need to be carried out under high vacuum. For example, for a non-phosgene method polycarbonate production system, the viscosity (1000-1200 Pa.S) of slurry in the polycondensation reaction is 5-6 times of that of the conventional polyethylene terephthalate (PET), the vacuum degree of the slurry is much more severe than that of the PET polycondensation reaction, the operation pressure of the final polycondensation reaction is within 50PaA, and the long-term stable operation of the system is difficult to maintain under the high vacuum requirement in the prior art.

For example, the existing vacuum method generally employs a dry vacuum pump (dry pump) to form a vacuum in the pump by means of mechanical action, and sucks gas in a reaction system (apparatus) to form a vacuum in the reaction system (apparatus). When high vacuum is required, multiple dry pumps are typically connected in series. Because the dry pump needs periodic maintenance and switching, pressure fluctuation is easy to occur, and the production stability is not facilitated; meanwhile, the movable equipment is easy to break down in production, and the more the series stages are, the higher the failure probability is.

Another vacuum method is to use an ejector, use jet gas as power, form vacuum in the ejector, suck gas in the reaction system (equipment) to form vacuum in the reaction system (equipment), when high vacuum is required, usually connect multiple ejectors in series. Compared with the series connection of dry pumps, the technology has the main advantages of less dynamic equipment and stable production, so that the technology is superior to the series connection of multi-stage dry pumps in long-period stable operation, but the following defects still exist: 1) the total extraction amount is controlled by adjusting the flow rate of power steam merged into non-condensable gas to adjust the vacuum degree, and the power steam is additionally consumed, so that additional spraying liquid for condensation is consumed, the consumption of public works is overlarge, and the production cost is obviously increased; 2) according to the process requirement, the refrigerant for interstage cooling of the ejector adopts raw materials and/or byproducts of a reaction system, for example, in the non-phosgene production of polycarbonate, phenol which is a PC byproduct is usually used as a spraying liquid, the phenol liquid mixed with a small amount of oligomers after spraying can be sent to a DPC preparation system to be used as a phenol raw material, and because the freezing point of phenol is low, vacuum equipment is easy to block due to solidification of the oligomers, crystallization of phenol and the like, the vacuum degree required by design cannot be achieved, even the system is stopped, and the long-time stable operation of the system is seriously influenced.

The applicant researches and discovers that the melt viscosity of the low-molecular-weight PC is sensitive to the temperature change at a low shear rate; the viscosity of high molecular weight PC polymers increases substantially with decreasing temperature. The higher the viscosity of the PC polymer, the lower the flowability at low shear rate, and the tendency to build up on the walls of equipment and piping. This is also an important cause of clogging of phenol jet vacuum equipment.

At normal pressure, the boiling point of phenol is 181.9 ℃, and the saturated vapor pressure is 0.13kPa (40.1 ℃); the boiling point of DPC is 301-302 ℃. From the Clausius-Clappelon equation, the higher the saturated vapor pressure of the liquid, the lower the boiling point; conversely, the higher the temperature, the greater the saturated vapor pressure of the liquid. The saturation temperature of DPC is 119.1-120.1 ℃ higher than that of phenol, which indicates that the saturated vapor partial pressure of DPC is much lower than that of phenol under the same conditions. According to the research results of the applicant, the DPC content in the phenol solution is gradually increased, and the freezing point of the mixed solution is also gradually increased. The DPC concentration in the condensate of the interstage condenser is optimized, the temperature of the spray liquid can be increased, phenol is effectively prevented from being crystallized and separated out to block vacuum equipment, and the injection load of the next stage can be effectively reduced due to the great reduction of the saturated vapor pressure.

SUMMERY OF THE UTILITY MODEL

For overcoming the above-mentioned defect of prior art, the utility model provides an adaptation polycarbonate production prevent blockking up high vacuum system, this system is convenient for adjust the vacuum, reduces or avoids the oligomer to solidify and the jam that the crystallization arouses, and then provides the condition for the long-time steady operation of system.

The utility model discloses realize above-mentioned purpose's technical scheme is: an anti-blocking high vacuum system suitable for polycarbonate production comprises a multi-stage injection condensing subsystem, a liquid ring vacuum pump, a liquid separating tank, a liquid seal tank, a phenol evaporator and a phenol separating system, wherein a power gas inlet of each injection pump of the multi-stage injection condensing subsystem is communicated with a steam outlet of the phenol evaporator, an external suction port of the multi-stage injection condensing subsystem is communicated with a non-condensable gas outlet of a polycarbonate polycondensation reactor, the non-condensable gas outlet of the multi-stage injection condensing subsystem is communicated with an air suction port of the liquid ring vacuum pump, a liquid supply port of the liquid ring vacuum pump is communicated with the liquid separating tank through a ring liquid cooler, a liquid discharge port of the liquid ring vacuum pump is communicated with the liquid separating tank, and a liquid discharge port of the liquid separating tank is communicated with a liquid inlet of the phenol separating system, a phenol outlet of the phenol separation system is communicated with a medium inlet of the phenol evaporator, a medium inlet of the liquid seal tank and equipment requiring phenol in the polycarbonate production system, a diphenyl carbonate outlet of the phenol separation system is communicated with the medium inlet of the liquid seal tank and the equipment requiring diphenyl carbonate in the polycarbonate production system, solution outlets of condensers of the multi-stage injection condensation subsystem are communicated with the medium inlet of the liquid seal tank, and liquid outlets of the liquid seal tank are communicated with spraying ports of the condensers through a conveying pump.

Further, an exhaust port of the liquid separation tank is communicated with an external suction port of the multi-stage injection condensation subsystem.

Further, the multi-stage injection condensing subsystem comprises a first-stage injection pump, a second-stage injection pump, a third-stage injection pump, a first-stage condenser, a second-stage condenser and a third-stage condenser, inlets of the first-stage injection pump, the second-stage injection pump and the third-stage injection pump are all connected with a steam outlet of the phenol evaporator, the suction port of the primary jet pump is communicated with the non-condensable gas outlet of the polycarbonate final polycondensation reactor, the outlet of the primary jet pump is communicated with the non-condensable gas inlet of the primary condenser, the non-condensable gas outlet of the primary condenser is communicated with the suction port of the secondary injection pump, the outlet of the secondary injection pump is communicated with the first non-condensable gas inlet of the secondary condenser, the non-condensable gas outlet of the secondary condenser is communicated with the suction port of the tertiary jet pump, the outlet of the tertiary jet pump is communicated with the non-condensable gas inlet of the tertiary condenser, and the non-condensable gas outlet of the tertiary condenser is communicated with the air suction port of the liquid ring vacuum pump.

Furthermore, the multistage injection condensation subsystem further comprises a second-stage B injection pump, wherein an inlet of the second-stage B injection pump is connected with a steam outlet of the phenol evaporator, a suction port of the second-stage B injection pump is communicated with a non-condensable gas outlet of the polycarbonate pre-polycondensation reactor, and an outlet of the second-stage B injection pump is communicated with a second non-condensable gas inlet of the second-stage condenser.

Further, the exhaust port of the liquid separation tank communicates with the suction port of the primary jet pump and the suction port of the secondary B jet pump.

Further, the anti-blocking high vacuum system suitable for polycarbonate production further comprises a pre-cooler and a post-cooler, the liquid outlet of the liquid seal tank is communicated with the spraying port at the top end of the third-stage condenser through the conveying pump, the liquid outlet of the liquid seal tank is communicated with the spraying port at the top end of the second-stage condenser through the conveying pump and the pre-cooler which are connected in series, and the liquid outlet of the liquid seal tank is communicated with the spraying port at the top end of the first-stage condenser through the conveying pump, the pre-cooler and the post-cooler which are connected in series.

Furthermore, the bottom of the primary condenser is provided with a stirrer with a wall scraping function, and the stirrer is provided with frame-shaped, anchor-type or helical ribbon-type stirring blades.

Furthermore, the first-stage, second-stage B and third-stage injection pumps are all provided with heat-insulating heating medium full jackets.

Further, the bottoms of the first-stage condenser, the second-stage condenser and the third-stage condenser are all in a cone shape, the solution outlets of the condensers are all arranged at the bottom end of the bottom of the cone shape, and the bottom of the cone shape of the first-stage condenser, the bottom of the cone shape of the second-stage condenser and the bottom of the cone shape of the third-stage condenser are all provided with a heat preservation.

Furthermore, the liquid seal groove and the liquid separation tank are both provided with a heat preservation heating medium full jacket.

The utility model has the advantages that:

because the mixed solution of phenol and diphenyl carbonate is used as the spraying solution, the solidification temperature of the mixed solution is obviously higher than that of the phenol solution, so that the relatively higher temperature of the spraying solution can be set to avoid the condensation of the low polymer and the crystallization and precipitation of the phenol caused by the low temperature of the spraying solution, meanwhile, the non-condensable gas led out from the polycondensation reactor (usually comprising a pre-polycondensation reactor and a final polycondensation reactor, or the polycondensation reactor and the final polycondensation reactor) is not cooled, or the temperature after cooling is still obviously higher than the temperature of the condensation of the low polymer and the crystallization and precipitation of the phenol, thereby eliminating the problem of the blockage of a vacuum system caused by the condensation of the low polymer and the crystallization and precipitation of the phenol; the tail gas reflux is added at the suction port of the jet pump, the vacuum degree of the corresponding reactor is adjusted or controlled in a mode of adjusting the tail gas reflux flow, and the flow adjustment of the power steam of the jet pump is not required for adjusting the vacuum degree, so that the delivery and control system of the power steam is simplified, a complex adjusting device caused by high temperature, high pressure and high flow rate of the power steam is avoided, the cost of the adjusting device is obviously reduced, the failure rate and the maintenance period of the adjusting device are obviously reduced, and the high consumption of the power steam caused by the adjustment of the vacuum degree is favorably reduced.

The utility model discloses can be used for the polycarbonate production of non-phosgene formula and other similar occasions that need the vacuum, obviously alleviate or thoroughly eliminate because of the oligomer condenses and the phenol crystallization blocks up the hindrance to vacuum system steady operation, provide the assurance for production system's long period steady operation.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

Detailed Description

The first embodiment is as follows: the embodiment is described with reference to fig. 1, and the anti-clogging high vacuum system suitable for Polycarbonate (PC) production of the embodiment comprises a multi-stage injection condensing subsystem, the multi-stage injection condensing subsystem is composed of a plurality of injection pumps and a plurality of condensers, and further comprises a liquid ring vacuum pump 8, a liquid separating tank 10, a liquid seal tank 11, a phenol evaporator 15 and a phenol separating system 16, a motive gas inlet of each injection pump of the multi-stage injection condensing subsystem is communicated with a vapor outlet of the phenol evaporator, an external suction port of the multi-stage injection condensing subsystem is communicated with a non-condensable gas outlet of a PC polycondensation reactor, the non-condensable gas outlet of the multi-stage injection condensing subsystem is communicated with a suction port of the liquid ring vacuum pump, a liquid supply port of the liquid ring vacuum pump is communicated with the liquid separating tank through a liquid cooler 9, and a liquid discharge port of the liquid ring vacuum pump is communicated with the liquid separating tank, the liquid outlet of the liquid separation tank is communicated with a liquid inlet of a phenol separation system for PC production, a phenol outlet of the phenol separation system is communicated with a medium inlet of a phenol evaporator, a medium inlet of a liquid seal tank and equipment (recycled to the PC production system) requiring phenol in the PC production system, a diphenyl carbonate outlet of the phenol separation system is communicated with a medium inlet of the liquid seal tank and equipment (recycled to the PC production system) requiring diphenyl carbonate in the polycarbonate production system, oligomers separated by the phenol separation system are recycled to the PC production system, solution outlets of condensers of the multistage injection condensation subsystem are communicated with a medium inlet of the liquid seal tank, a liquid outlet of the liquid seal tank is communicated with a spray port of each condenser through a conveying pump 12, and the liquid seal tank has liquid storage and liquid seal functions.

The second embodiment is as follows: the embodiment is described with reference to fig. 1, and the exhaust port of the liquid separation tank of the embodiment is communicated with the external suction port of the multi-stage injection condensation subsystem. Other components and connections are the same as in the first embodiment.

The third concrete implementation mode: the embodiment is described with reference to fig. 1, the multistage jet condensation subsystem of the embodiment includes a first-stage jet pump 1, a second-stage jet pump 2, a third-stage jet pump 4, a first-stage condenser 5, a second-stage condenser 6 and a third-stage condenser 7, inlets of the first-stage, second-stage and third-stage jet pumps are all connected with a vapor outlet of the phenol evaporator, a suction port of the first-stage jet pump is communicated with a non-condensable gas outlet of a PC final condensation reactor, an outlet of the first-stage jet pump is communicated with a non-condensable gas inlet of the first-stage condenser, a non-condensable gas outlet of the first-stage condenser is communicated with a suction port of the second-stage jet pump, an outlet of the second-stage jet pump is communicated with a non-condensable gas inlet of the third-stage condenser, and the non-condensable gas outlet of the third-stage condenser is communicated with the air suction port of the liquid ring vacuum pump, and the solution outlets of the first-stage condenser, the second-stage condenser and the third-stage condenser are communicated with the medium inlet of the liquid seal tank. Other compositions and connections are the same as in the first or second embodiments.

The fourth concrete implementation mode: the embodiment is described with reference to fig. 1, the multistage injection condensation subsystem of the embodiment further includes a two-stage B injection pump 3, an inlet of the two-stage B injection pump is connected to the vapor outlet of the phenol evaporator, a suction port of the two-stage B injection pump is communicated with the non-condensable gas outlet of the PC pre-condensation reactor, and an outlet of the two-stage B injection pump is communicated with a second non-condensable gas inlet of the two-stage condenser. Other compositions and connection relationships are the same as in the first, second or third embodiment.

The fifth concrete implementation mode: referring to fig. 1, the exhaust port of the liquid separation tank of the present embodiment communicates with the suction port of the primary injection pump and the suction port of the secondary B injection pump, a valve is disposed on a communicating pipe, and the exhaust port of the liquid separation tank may also communicate with an exhaust gas treatment device. Other compositions and connection relationships are the same as those in the first, second, third or fourth embodiment.

The sixth specific implementation mode: the embodiment is described with reference to fig. 1, and the anti-clogging high vacuum system adapted to polycarbonate production of the embodiment further includes a pre-cooler 13 and a post-cooler 14, a liquid outlet of the liquid seal tank is communicated with a spray port at the top end of the tertiary condenser through the transfer pump, a liquid outlet of the liquid seal tank is communicated with a spray port at the top end of the secondary condenser through the transfer pump and the pre-cooler connected in series, and a liquid outlet of the liquid seal tank is communicated with a spray port at the top end of the primary condenser through the transfer pump, the pre-cooler and the post-cooler connected in series. Other compositions and connection relationships are the same as in the first, second, third, fourth or fifth embodiment.

The seventh embodiment: referring to fig. 1, the present embodiment is described, in which a stirrer having a wall scraping function is installed at the bottom of the primary condenser, the stirrer has a frame-shaped, anchor-shaped or ribbon-shaped stirring blade having a forward and reverse rotation function, and the stirring blade generally covers a communication port between the primary jet pump and the primary condenser and a region from the communication port to the bottom of the primary condenser. The setting of agitator can effectively avoid the oligomer to build the wall in the primary condenser, still helps the oligomer to discharge from the primary condenser, can effectively prevent that the oligomer from blockking up vacuum system, guarantees vacuum system's steady operation. Other compositions and connection relationships are the same as in the first, second, third, fourth, fifth or sixth embodiment.

The specific implementation mode is eight: the first-stage, second-stage B and third-stage injection pumps of the embodiment are all provided with heat-preserving heat medium full jackets. Other compositions and connection relationships are the same as those of embodiment one, two, three, four, five, six or seven.

The specific implementation method nine: the bottoms of the first-stage condenser, the second-stage condenser and the third-stage condenser are all in a conical shape, the solution outlets of the condensers are all arranged at the bottom end of the conical bottom, and the conical bottoms of the first-stage condenser, the second-stage condenser and the third-stage condenser are all provided with heat preservation heating medium jackets. The spraying series of each condenser can be one stage, and can also be two stages or multiple stages. Other compositions and connection relationships are the same as those in the first, second, third, fourth, fifth, sixth, seventh or eighth embodiment.

The detailed implementation mode is ten: the liquid seal groove and the liquid separation tank of the embodiment are both provided with a heat preservation heating medium full jacket. Other compositions and connection relationships are the same as those of embodiment one, two, three, four, five, six, seven, eight or nine.

The utility model discloses the reaction accessory substance phenol vapor in with the PC production is as spraying power vapour, utilize the noncondensable gas that the polycondensation produced in the injection pump system suction PC production, and condense the mixture that forms after the suction, regard the mixed liquid of phenol and diphenyl carbonate as the spray liquid of condensation usefulness, form required vacuum through the suction effect in PC reaction system, furthest has reduced the quantity of vacuum pipe in the vacuum system, compare in and advance the injection pump system in carrying out the suction after the preliminary treatment to the noncondensable gas that comes from in PC prepolycondensation and the final polycondensation reaction, on-the-way pressure loss and gas leakage are minimum, can provide reliably for the polycarbonate production, stable high vacuum. The non-condensable gas is sent to the liquid ring vacuum pump through the jet pump system, and liquid discharged after the liquid ring of the liquid ring vacuum pump is condensed by the jet pump system (usually, the liquid is a mixed liquid of phenol and diphenyl carbonate). After discharged liquid of the liquid ring vacuum pump is treated by the liquid separating tank, a liquid part is sent to the phenol separating system, a part of refined phenol separated by the phenol separating system is used for preparing power steam required by the jet pump, a part of diphenyl carbonate (DPC) separated by the phenol separating system is used for replenishing liquid of spraying liquid of the jet pump system, and the rest of phenol, diphenyl carbonate and oligomer are sent to the PC production system as production raw materials, wherein the phenol and the diphenyl carbonate are used as raw materials for preparing the DPC, and the oligomer is used as a raw material for polycondensation reaction, so that the closed circulation of the phenol and the DPC is realized, and the zero discharge of waste liquid of the system is realized.

Further, the degree of vacuum of the prepolycondensation reactor and/or the finisher reactor is adjusted or controlled in the following manner: after the discharged liquid of the liquid ring vacuum pump is treated by the liquid separating tank, one part of tail gas is exhausted, the other part of tail gas is respectively connected to a suction port of an injection pump for sucking the non-condensable gas of the pre-polycondensation reactor and/or the final polycondensation reactor, and the flow of the non-condensable gas sucked by the corresponding injection pump is regulated by regulating the flow of the tail gas sucked by the corresponding injection pump, so that the vacuum degree of the corresponding reactor is controlled. Compared with the traditional mode of adopting power steam to adjust the vacuum degree in the PC polycondensation reaction, the consumption of the power steam can be effectively reduced, and the consumption of a heating medium for generating the power steam is reduced.

The utility model discloses an each condenser adopts the mixed solution of phenol and DPC as spraying liquid, the mass ratio of phenol in the spraying liquid and DPC is 90:10 ~ 70:30, for example 90:10, 80:20 or 70: 30. Compared with the traditional method of adopting phenol as the spray liquid, the temperature of the circulating spray liquid can be effectively increased (usually more than 50 ℃) due to the addition of DPC, the risk that the spray pump system is blocked due to the precipitation of phenol crystals caused by the excessively low temperature of the spray liquid is reduced (the principle is shown below), and meanwhile, the injection load of the spray pump can be reduced due to the fact that the precipitation of phenol crystals in the spray liquid is avoided and the saturated vapor pressure of the mixed liquid is greatly reduced.

The melt viscosity of low molecular weight PC is sensitive to temperature change at low shear rate, and the viscosity of high molecular weight PC polymer is greatly increased along with the decrease of temperature. The higher the viscosity of the PC polymer, the lower the flowability at low shear rate, and the tendency to build up on the walls of equipment and piping. At normal pressure, the boiling point of phenol is 181.9 ℃, and the saturated vapor pressure is 0.13kPa (40.1 ℃); the boiling point of DPC is 301-302 ℃. From the Clausius-Clappelon equation, the higher the saturated vapor pressure of the liquid, the lower the boiling point; conversely, the higher the temperature, the greater the saturated vapor pressure of the liquid. The saturation temperature of DPC is 119.1-120.1 ℃ higher than that of phenol, which indicates that the saturated vapor partial pressure of DPC is much lower than that of phenol under the same conditions. Therefore, the DPC content in the phenol solution gradually increases, and the freezing point of the mixed solution also gradually increases.

Generally, the temperature of the spray liquid in the secondary condenser is higher than that in the primary condenser, and the temperature of the spray liquid in the tertiary condenser is higher than that in the secondary condenser. Generally, the first part of the liquid as the spraying liquid from the liquid seal tank is sent to the primary condenser as the spraying liquid after two-stage or multi-stage cooling, the temperature of the spraying liquid in the primary condenser is preferably 50-60 ℃, such as 50 ℃, 55 ℃ or 60 ℃, and the spraying ratio (mass) is preferably 500-700, such as 500, 600 or 700; the second part of the liquid serving as the spraying liquid from the liquid seal tank is sent to the secondary condenser after primary cooling to serve as the spraying liquid, the temperature of the spraying liquid in the secondary condenser is preferably 60-70 ℃, such as 60 ℃, 65 ℃ or 70 ℃, and the spraying ratio (mass) is preferably 400-600, such as 400, 500 or 600; and a third part of the liquid as the spraying liquid from the liquid seal tank is directly sent to the three-stage condenser without cooling to be used as the spraying liquid, and the spraying ratio (mass) is preferably 300-500, such as 300, 400 or 500. The temperature gradient of the spraying liquid for the first-stage, second-stage and third-stage condensers is increased, and compared with the traditional technology, the requirement of a refrigerant for cooling the spraying liquid can be effectively reduced, and the consumption of public works is reduced.

The utility model discloses a working process and principle do: and the non-condensable gas in the PC final polycondensation reactor is carried by phenol vapor from the phenol evaporator through the primary injection pump to enter the primary condenser, and the primary condenser adopts a mixed solution of phenol and DPC as a spray liquid to carry out spray cooling. The flow of the non-condensable gas entering the primary jet pump can be controlled by adjusting the amount of the tail gas entering the primary jet pump and coming from the liquid separation tank, so that the vacuum degree of the PC final polycondensation reaction is adjusted, the vacuum degree as high as possible is achieved under a certain power steam consumption, and the optimal power steam consumption is realized. Noncondensable gas in the primary condenser warp the second grade jet pump is got from phenol evaporimeter's phenol vapour carries the entering the secondary condenser, simultaneously, noncondensable gas in the PC pre-condensation reactor warp the second grade B jet pump is got from phenol evaporimeter's phenol vapour carries the entering the second grade condenser, the second grade condenser adopt with the same spray liquid of primary condenser sprays the cooling, the temperature of the spray liquid that the secondary condenser was used with the spray liquid temperature that the primary condenser was used is different, usually the temperature of the spray liquid that the secondary condenser was used is higher than the temperature of the spray liquid that the primary condenser was used. The flow of the non-condensable gas entering the secondary B jet pump can be controlled by adjusting the amount of tail gas entering the secondary B jet pump and coming from the liquid separation tank, so that the vacuum degree of the PC pre-polycondensation reaction is adjusted. The non-condensable gas in the secondary condenser is carried by phenol vapor from the phenol evaporator through the tertiary jet pump to enter the tertiary condenser, the tertiary condenser adopts the same spraying liquid as the primary condenser and the secondary condenser to carry out spraying cooling, the temperature of the spraying liquid for the tertiary condenser is different from that of the spraying liquid for the primary condenser and the secondary condenser, and generally, the temperature of the spraying liquid for the tertiary condenser is higher than that of the spraying liquid for the secondary condenser. And the non-condensable gas in the three-stage condenser is pumped out by the liquid ring vacuum pump, is separated by the liquid separating tank and then is discharged as tail gas, and in addition, a part of the tail gas is led to the suction ports of the primary injection pump and the secondary injection pump B to respectively adjust the pressure and the vacuum degree of the PC final polycondensation reactor and the PC pre-polycondensation reactor. The liquid after the first-stage, second-stage and third-stage condensers are subjected to spray cooling enters the liquid seal groove, the liquid in the liquid seal groove is pressurized by the delivery pump and then enters the first-stage, second-stage and third-stage condensers in a stepped manner after two-stage or multi-stage cooling to serve as spray liquid, and the liquid pressurized by the delivery pump is further sent to the liquid separation tank to be used for liquid circulation of the liquid ring vacuum pump. And the liquid separated by the liquid separating tank enters the phenol separating system, the separated phenol respectively enters the phenol evaporator and the liquid seal tank, the separated DPC enters the liquid seal tank to replace the liquid in the phenol evaporator and the liquid seal tank, and the residual phenol, the DPC and the oligomer are conveyed to a PC production system for recycling, so that the zero emission of the waste liquid of the vacuum system is realized.

Claims (10)

1. An anti-blocking high vacuum system suitable for polycarbonate production comprises a multi-stage injection condensation subsystem, wherein the multi-stage injection condensation subsystem is composed of a plurality of injection pumps and a plurality of condensers and is characterized by further comprising a liquid ring vacuum pump, a liquid separation tank, a liquid seal tank, a phenol evaporator and a phenol separation system, a power gas inlet of each injection pump of the multi-stage injection condensation subsystem is communicated with a vapor outlet of the phenol evaporator, an external suction port of the multi-stage injection condensation subsystem is communicated with a non-condensable gas outlet of a polycarbonate polycondensation reactor, the non-condensable gas outlet of the multi-stage injection condensation subsystem is communicated with an air suction port of the liquid ring vacuum pump, a liquid supply port of the liquid ring vacuum pump is communicated with the liquid separation tank through a ring liquid cooler, a liquid discharge port of the liquid ring vacuum pump is communicated with the liquid separation tank, and a liquid discharge port of the liquid separation tank is communicated with a liquid inlet of the phenol, a phenol outlet of the phenol separation system is communicated with a medium inlet of the phenol evaporator, a medium inlet of the liquid seal tank and equipment requiring phenol in the polycarbonate production system, a diphenyl carbonate outlet of the phenol separation system is communicated with the medium inlet of the liquid seal tank and the equipment requiring diphenyl carbonate in the polycarbonate production system, solution outlets of condensers of the multi-stage injection condensation subsystem are communicated with the medium inlet of the liquid seal tank, and liquid outlets of the liquid seal tank are communicated with spraying ports of the condensers through a conveying pump.

2. The anti-clogging high vacuum system for polycarbonate production according to claim 1, wherein the exhaust port of the separation tank is communicated with the external suction port of the multi-stage injection condensation subsystem.

3. The anti-clogging high vacuum system suitable for polycarbonate production according to claim 2, wherein the multi-stage injection condensing subsystem comprises a primary injection pump, a secondary injection pump, a tertiary injection pump, a primary condenser, a secondary condenser and a tertiary condenser, inlets of the primary, secondary and tertiary injection pumps are all connected with a vapor outlet of the phenol evaporator, a suction port of the primary injection pump is communicated with a non-condensable gas outlet of the polycarbonate final polycondensation reactor, an outlet of the primary injection pump is communicated with a non-condensable gas inlet of the primary condenser, a non-condensable gas outlet of the primary condenser is communicated with a suction port of the secondary injection pump, an outlet of the secondary injection pump is communicated with a first non-condensable gas inlet of the secondary condenser, a non-condensable gas outlet of the secondary condenser is communicated with a suction port of the tertiary injection pump, and an outlet of the tertiary injection pump is communicated with a non-condensable gas inlet of the tertiary condenser, and a non-condensable gas outlet of the three-stage condenser is communicated with an air suction port of the liquid ring vacuum pump.

4. The anti-clogging high vacuum system for polycarbonate production according to claim 3, wherein the multi-stage jet condensation subsystem further comprises a secondary B jet pump, an inlet of the secondary B jet pump is connected to the vapor outlet of the phenol evaporator, a suction port of the secondary B jet pump is communicated with the non-condensable gas outlet of the polycarbonate pre-polycondensation reactor, and an outlet of the secondary B jet pump is communicated with the second non-condensable gas inlet of the secondary condenser.

5. The anti-clogging high vacuum system for polycarbonate production according to claim 4, wherein the exhaust port of the liquid separation tank communicates with the suction port of the primary jet pump and the suction port of the secondary B jet pump.

6. The anti-clogging high vacuum system suitable for polycarbonate production as claimed in claim 5, further comprising a pre-cooler and a post-cooler, wherein the liquid outlet of the liquid seal tank is communicated with the spray port at the top end of the tertiary condenser through the transfer pump, the liquid outlet of the liquid seal tank is communicated with the spray port at the top end of the secondary condenser through the transfer pump and the pre-cooler connected in series, and the liquid outlet of the liquid seal tank is communicated with the spray port at the top end of the primary condenser through the transfer pump, the pre-cooler and the post-cooler connected in series.

7. The anti-clogging high vacuum system for polycarbonate production as claimed in claim 6, wherein the bottom of the primary condenser is equipped with a stirrer with wall scraping function, and the stirrer is provided with frame-type, anchor-type or helical stirring blades.

8. The anti-clogging high vacuum system for polycarbonate production as claimed in claim 7, wherein the primary, secondary B and tertiary jet pumps are all provided with a thermal insulation heating medium full jacket.

9. The anti-clogging high vacuum system for polycarbonate production as claimed in claim 8, wherein the primary, secondary and tertiary condensers each have a tapered bottom, the solution outlet of each condenser is provided at the bottom of the tapered bottom, and the tapered bottoms of the primary, secondary and tertiary condensers are provided with heat insulating medium jackets.

10. The anti-clogging high vacuum system suitable for polycarbonate production according to claim 9, wherein the liquid seal tank and the liquid separation tank are both provided with a heat insulating medium full jacket.

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