Drying device for producing polycarbonate

Abstract

The utility model provides a drying device for producing polycarbonate. The drying device comprises a drying tower, a molecular sieve, a first nitrogen fan and a cooler. A first nitrogen fan and a cooler are connected in series between the nitrogen outlet of the drying tower and the gas inlet of the molecular sieve, and the gas outlet of the molecular sieve is communicated with the nitrogen inlet of the drying tower. Part of nitrogen is led out of the drying tower, conveyed to the cooler through the first nitrogen fan to be cooled and then enters the molecular sieve to be dehydrated, and the dehydrated nitrogen is conveyed into the drying tower. By adding the molecular sieve which is a parallel device, on the premise that the capacity of other devices is not changed, the hot nitrogen circulation amount of the drying tower can be increased, the dehydration effect is improved, meanwhile, the molecular sieve also dries nitrogen circulating in the system, and the drying capacity of the drying tower is improved. After improvement, the water content of the polycarbonate product is obviously reduced, yellow particles in the polycarbonate product are reduced, the melt index is more stable, and the product quality and the operability of the device are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of drying process, and particularly relates to a drying device for producing polycarbonate. Background Art

[0002] At present, the existing drying process in the continuous production of polycarbonate (PC for short) industry is: PC flakes are subjected to devolatilization treatment in a devolatilization tower, and the PC flakes after devolatilization still contain 35%-38% of moisture. The PC flakes after devolatilization enter the drying system for drying treatment, and enter the primary drying fluidized bed, the secondary drying fluidized bed, and the ridge drying tower for three-stage drying treatment in sequence. The three-stage drying uses hot nitrogen for heating and drying. The final moisture content of the treated PC flakes should be less than 3000ppmw, wherein the moisture content of the PC flakes after the primary fluidized bed drying is less than 30wt%, the moisture content of the PC flakes after the secondary fluidized bed drying is less than 15wt%, and the final moisture content of the PC flakes after the ridge drying tower treatment should be less than 3000ppmw.

[0003] In the actual production process, after the PC flakes undergo three-stage drying, the drying capacity of the first-stage fluidized bed and the second-stage sulfurized bed meet the index requirements, but the moisture drying capacity of the ridge drying tower does not meet the standard of less than 1000ppmw. The presence of moisture will cause the PC flakes to degrade, the melt index to shift, and yellow particles to appear during the extrusion process, which reduces the quality and performance of the product, and also reduces the operability and stability of the device.

[0004] Therefore, how to solve the technical defect of insufficient drying capacity of the drying tower in the polycarbonate production process is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0005] The utility model aims to provide a drying device for producing polycarbonate, which can effectively improve the drying capacity of a drying tower and improve the quality of polycarbonate products.

[0006] In order to solve the above technical problems, the utility model provides a drying device for producing polycarbonate, comprising: a drying tower, a molecular sieve, a first nitrogen blower and a cooler;

[0007] The first nitrogen blower and the cooler are connected in series between the nitrogen outlet of the drying tower and the gas inlet of the molecular sieve, and the gas outlet of the molecular sieve is communicated with the nitrogen inlet of the drying tower.

[0008] Optionally, the above-mentioned drying device for producing polycarbonate further includes a nitrogen drying tower, a first filter for filtering powder, a second nitrogen blower and a first heater, and the first filter, the second nitrogen blower and the first heater are connected in series in sequence between the nitrogen outlet of the nitrogen drying tower and the nitrogen inlet of the drying tower.

[0009] Optionally, in the above-mentioned drying device for producing polycarbonate, the gas outlet of the molecular sieve is connected to the inlet of the second nitrogen blower, and the outlet of the first heater is connected to the nitrogen inlet of the drying tower.

[0010] Optionally, in the above-mentioned drying device for producing polycarbonate, a first adsorption valve is connected in series between the inlet of the molecular sieve and the outlet of the cooler, a second regeneration valve is connected in series between the inlet of the molecular sieve and the gas inlet of the primary fluidized bed, the outlet of the molecular sieve is respectively connected to a first branch and a second branch, the first branch is connected to the drying tower, the second branch is connected to the nitrogen drying tower, the first branch is connected in series with a second adsorption valve, and the second branch is connected in series with a first regeneration valve.

[0011] Optionally, in the above-mentioned drying device for producing polycarbonate, the molecular sieve includes a plurality of molecular sieves arranged in parallel, the inlet of each molecular sieve is connected to the outlet of the cooler through a third branch, each of the third branches is connected in series with the first adsorption valve, the inlet of each molecular sieve is connected to the gas inlet of the primary fluidized bed through a fourth branch, and each of the fourth branches is connected in series with the second regeneration valve;

[0012] The second adsorption valve and the first regeneration valve are respectively connected in series on each of the first branches and each of the second branches, all of the first branches are connected to the gas inlet of the drying tower through the first main pipeline, and all of the second branches are connected to the gas outlet of the nitrogen drying tower through the second main pipeline.

[0013] Optionally, in the above-mentioned drying device for producing polycarbonate, an analyzer for detecting the moisture content of nitrogen is connected in series to the first main pipeline.

[0014] Optionally, the above-mentioned drying device for producing polycarbonate further includes a controller, the analyzer is connected to the controller, and the controller is used to control the first adsorption valve and the second adsorption valve of the current molecular sieve to close and open the first adsorption valve and the second adsorption valve of another molecular sieve when the analyzer detects that the moisture content in the nitrogen of the current molecular sieve exceeds the standard.

[0015] Optionally, in the above-mentioned drying device for producing polycarbonate, the controller is also used to control the first regeneration valve and the second regeneration valve of the current molecular sieve to open when the analyzer detects that the moisture content in the nitrogen of the current molecular sieve exceeds the standard.

[0016] Optionally, in the above-mentioned drying device for producing polycarbonate, a third nitrogen blower and a second heater are connected in series on the second main pipeline.

[0017] Optionally, in the above-mentioned drying device for producing polycarbonate, the nitrogen outlet of the drying tower is also connected to the gas inlet of the primary fluidized bed, and a second filter and a pressure regulating valve for filtering powder are connected in series between the nitrogen outlet of the drying tower and the gas inlet of the primary fluidized bed.

[0018] The utility model provides a drying device for producing polycarbonate, which has the following beneficial effects:

[0019] Part or all of the nitrogen is drawn out of the drying tower, transported to the cooler for cooling through the first nitrogen blower, and then enters the molecular sieve for dehydration. The dehydrated nitrogen is then transported to the drying tower. By adding the molecular sieve as a parallel dehydration device, the hot nitrogen circulation volume of the drying tower can be increased without changing the capacity of other equipment, thereby increasing the dehydration effect. At the same time, the molecular sieve also dries the nitrogen circulating in the system, which also improves the drying capacity of the drying tower. After the improvement, the water content of the polycarbonate product is significantly reduced, the yellow particles in the polycarbonate product are reduced, the melt index is more stable, and the product quality and the operability of the device are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0021] Figure 1 A schematic diagram of a process of a drying device for producing polycarbonate provided in an embodiment of the utility model;

[0022] Figure 2 A schematic structural diagram of a drying device for producing polycarbonate provided in an embodiment of the utility model (one molecular sieve, the molecular sieve only performs adsorption);

[0023] Figure 3 A schematic diagram of the structure of a drying device for producing polycarbonate provided in an embodiment of the utility model (a molecular sieve, which can be adsorbed and regenerated);

[0024] Figure 4 A schematic structural diagram of a drying device for producing polycarbonate provided in an embodiment of the utility model (two molecular sieves, which can be adsorbed and regenerated).

[0025] In the above picture:

[0026] A-primary fluidized bed; B-secondary fluidized bed; C-product silo; D-nitrogen drying tower;

[0027] 1-drying tower; 2-molecular sieve; 201-first molecular sieve; 202-second molecular sieve; 301-first nitrogen blower; 302-second nitrogen blower; 303-third nitrogen blower; 401-primary cooler; 402-secondary cooler; 501-first heater; 502-second heater; 601-second filter; 602-first filter; 7-analyzer; 8-rotary discharge valve;

[0028] a1-first adsorption valve; a2-second adsorption valve; b1-first regeneration valve; b2-second regeneration valve;

[0029] Q1-hydrogen; Q2-condensate; Q3-dry nitrogen. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0031] The core of the utility model is to provide a drying device for producing polycarbonate, which can effectively improve the drying capacity of a drying tower and improve the quality of polycarbonate products.

[0032] In order to enable those skilled in the art to better understand the technical solution provided by the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] Specifically, please refer to Figure 1-Figure 4 The utility model provides a drying device for producing polycarbonate, comprising: a drying tower 1, a molecular sieve 2, a first nitrogen blower 301, a cooler, a second nitrogen blower 302 and a first heater 501.

[0034] A first nitrogen blower 301 and a cooler are connected in series between the nitrogen outlet of the drying tower 1 and the gas inlet of the molecular sieve 2, and a second nitrogen blower 302 and a first heater 501 are connected in series between the gas outlet of the molecular sieve 2 and the nitrogen inlet of the drying tower 1. The drying tower 1 may be a ridge drying tower. A nitrogen outlet is provided at the top of the drying tower 1, and a nitrogen inlet is provided at the bottom.

[0035] This solution provides a drying device for producing polycarbonate. Part or all of the nitrogen is drawn out of the drying tower 1, transported to the cooler for cooling through the first nitrogen blower 301, and then enters the molecular sieve 2 for dehydration. The dehydrated nitrogen is then transported to the drying tower 1. By adding the molecular sieve 2, a parallel dehydration device, the circulation volume of the hot nitrogen in the drying tower 1 can be increased without changing the capacity of other equipment, thereby increasing the dehydration effect. At the same time, the molecular sieve 2 also dries the nitrogen circulating in the system, thereby improving the drying capacity of the drying tower 1. After the improvement, the water content of the polycarbonate product is significantly reduced, the yellow particles in the polycarbonate product are reduced, the melt index is more stable, and the product quality and the operability of the device are improved.

[0036] In a specific embodiment, the material inlet of the drying tower 1 is connected to the material outlet of the secondary fluidized bed B, and the material outlet of the drying tower 1 can be connected to the product silo C. In addition, a rotary discharge valve 8 can be connected in series between the material outlet of the drying tower 1 and the product silo C to control the opening of the material outlet of the drying tower 1.

[0037] This solution also includes a nitrogen drying tower D, a first filter 602 for filtering powder, a second nitrogen blower 302 and a first heater 501. The first filter 602, the second nitrogen blower 302 and the first heater 501 are connected in series in sequence between the nitrogen outlet of the nitrogen drying tower D and the nitrogen inlet of the drying tower 1.

[0038] Fresh hot nitrogen from nitrogen drying tower D passes through the first filter 602 to filter the PC powder in the nitrogen, and is then transported to the first heater 501 by the second nitrogen blower 302 for heating, and then enters the drying tower 1.

[0039] In one form, the nitrogen after dehydration from the molecular sieve 2 can be directly sent back to the drying tower 1; in another form, the gas outlet of the molecular sieve 2 is connected to the inlet of the second nitrogen blower 302, and the outlet of the first heater 501 is connected to the nitrogen inlet of the drying tower 1. That is, the nitrogen after dehydration from the molecular sieve 2 and the dry nitrogen Q3 from the nitrogen drying tower D can enter the drying tower 1 together through the second nitrogen blower 302 and the first heater 501.

[0040] In a specific embodiment, a first adsorption valve a1 is connected in series between the inlet of the molecular sieve 2 and the outlet of the cooler, a second regeneration valve b2 is connected in series between the inlet of the molecular sieve 2 and the gas inlet of the primary fluidized bed A, and the outlet of the molecular sieve 2 is connected to a first branch and a second branch respectively, the first branch is connected to the drying tower 1, and the second branch is connected to the nitrogen drying tower D, the second adsorption valve a2 is connected in series on the first branch, and the first regeneration valve b1 is connected in series on the second branch.

[0041] The working principle of the molecular sieve 2 is to adsorb at low temperature and regenerate at high temperature. Therefore, when the molecular sieve adsorbs moisture in nitrogen, the first adsorption valve a1 and the second adsorption valve a2 are opened. When the molecular sieve 2 has low working efficiency, the first adsorption valve a1 and the second adsorption valve a2 are closed, and the first regeneration valve b1 and the second regeneration valve b2 are opened, so that the high-temperature nitrogen from the nitrogen drying tower D regenerates the molecular sieve 2.

[0042] In order not to affect the working process of the entire drying device, multiple molecular sieves can be used to switch the working state. Specifically, the molecular sieve 2 includes multiple molecular sieves arranged in parallel, the inlet of each molecular sieve is connected to the outlet of the cooler through the third branch, each third branch is connected in series with a first adsorption valve a1, the inlet of each molecular sieve is connected to the gas inlet of the primary fluidized bed A through the fourth branch, and each fourth branch is connected in series with a second regeneration valve b2.

[0043] Each first branch and each second branch is connected in series with a second adsorption valve a2 and a first regeneration valve b1 respectively. All first branches are connected to the gas inlet of the drying tower 1 through the first main pipeline, and all second branches are connected to the gas outlet of the nitrogen drying tower D through the second main pipeline.

[0044] At the same time, the moisture content in the nitrogen is monitored by using the analyzer 7, and the first main pipeline is connected in series with the analyzer 7 for detecting the moisture content of the nitrogen.

[0045] This solution also includes a controller, and the analyzer 7 is connected to the controller. The controller is used to control the first adsorption valve a1 and the second adsorption valve a2 of the current molecular sieve to close when the analyzer 7 detects that the moisture content in the nitrogen of the current molecular sieve exceeds the standard, and to open the first adsorption valve a1 and the second adsorption valve a2 of another molecular sieve.

[0046] The controller is also used to control the first regeneration valve b1 and the second regeneration valve b2 of the current molecular sieve to open when the analyzer 7 detects that the moisture content in the nitrogen of the current molecular sieve exceeds the standard.

[0047] In order to improve the regeneration effect of the molecular sieve, the third nitrogen blower 303 and the second heater 502 are connected in series on the second main pipeline.

[0048] In addition, in a specific embodiment, the nitrogen outlet of the drying tower 1 is also connected to the gas inlet of the primary fluidized bed A, and a second filter 601 for filtering powder and a pressure regulating valve are connected in series between the nitrogen outlet of the drying tower 1 and the gas inlet of the primary fluidized bed A.

[0049] The cooler includes a primary cooler 401 and a secondary cooler 402. The refrigerant in the primary cooler 401 is circulating water, and the refrigerant in the secondary cooler 402 is chilled water. The cost of chilled water is higher than that of circulating water. Therefore, the primary cooler 401 is used to cool down first, and then the secondary cooler 402 is used for further cooling.

[0050] In a specific embodiment, Figure 4 As shown, after the PC flakes enter the primary fluidized bed A for drying, they are blown to the secondary fluidized bed B for drying. After drying in the secondary fluidized bed B, they enter the ridge drying tower from the bottom by gravity for drying. Part of the nitrogen gas is drawn out from the gas outlet at the top of the ridge drying tower and transported to the cooler through the first nitrogen blower 301 for cooling, and then enters the molecular sieve for dehydration. The dehydrated nitrogen gas returns to the ridge drying tower and is transported into the ridge drying tower together with the fresh hot nitrogen gas through the second nitrogen blower 302 set at the bottom of the tower.

[0051] The molecular sieves are used in a one-on-one standby mode (i.e., including a first molecular sieve 201 and a second molecular sieve 202). When the first molecular sieve 201 is used, the analyzer 7 located at the outlet alarms and switches to the standby second molecular sieve 202. The first molecular sieve 201 is heated by the nitrogen from the nitrogen drying tower D through the third nitrogen blower 303 and the second heater 502 to perform heating dehydration regeneration, and the two molecular sieves are dehydrated and regenerated for continuous use.

[0052] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and 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 therefore should not be understood as a limitation on the present application.

[0053] In the description of this application, the meaning of "plurality" is more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and it cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0054] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "a kind" and / or "the" do not refer to the singular, but also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements. The elements defined by the sentence "includes a..." do not exclude the existence of other identical elements in the process, method, commodity or device that includes the elements.

[0055] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0056] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0057] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0058] This article uses specific examples to illustrate the principles and implementation methods of the utility model. The above examples are only used to help understand the method and core ideas of the utility model. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. A drying device for producing polycarbonate, characterized in that: include: Drying tower, molecular sieve, first nitrogen blower and cooler; The first nitrogen blower and the cooler are connected in series between the nitrogen outlet of the drying tower and the gas inlet of the molecular sieve, and the gas outlet of the molecular sieve is communicated with the nitrogen inlet of the drying tower.

2. The drying device for producing polycarbonate according to claim 1, characterized in that: It also includes a nitrogen drying tower, a first filter for filtering powder, a second nitrogen blower and a first heater, wherein the first filter, the second nitrogen blower and the first heater are sequentially connected in series between the nitrogen outlet of the nitrogen drying tower and the nitrogen inlet of the drying tower.

3. The drying device for producing polycarbonate according to claim 2, characterized in that: The gas outlet of the molecular sieve is communicated with the inlet of the second nitrogen blower, and the outlet of the first heater is communicated with the nitrogen inlet of the drying tower.

4. The drying device for producing polycarbonate according to claim 2, characterized in that: A first adsorption valve is connected in series between the inlet of the molecular sieve and the outlet of the cooler, a second regeneration valve is connected in series between the inlet of the molecular sieve and the gas inlet of the primary fluidized bed, the outlet of the molecular sieve is respectively connected to a first branch and a second branch, the first branch is connected to the drying tower, the second branch is connected to the nitrogen drying tower, the first branch is connected in series with a second adsorption valve, and the second branch is connected in series with a first regeneration valve.

5. The drying device for producing polycarbonate according to claim 4, characterized in that: The molecular sieve comprises a plurality of molecular sieves arranged in parallel, the inlet of each molecular sieve is connected to the outlet of the cooler through a third branch, each of the third branches is connected in series with the first adsorption valve, the inlet of each molecular sieve is connected to the gas inlet of the primary fluidized bed through a fourth branch, each of the fourth branches is connected in series with the second regeneration valve; The second adsorption valve and the first regeneration valve are respectively connected in series on each of the first branches and each of the second branches, all of the first branches are connected to the gas inlet of the drying tower through the first main pipeline, and all of the second branches are connected to the gas outlet of the nitrogen drying tower through the second main pipeline.

6. The drying device for producing polycarbonate according to claim 5, characterized in that An analyzer for detecting the moisture content of nitrogen is connected in series to the first main pipeline.

7. The drying device for producing polycarbonate according to claim 6, characterized in that: It also includes a controller, the analyzer is connected to the controller, and the controller is used to control the first adsorption valve and the second adsorption valve of the current molecular sieve to close and open the first adsorption valve and the second adsorption valve of another molecular sieve when the analyzer detects that the moisture content in the nitrogen of the current molecular sieve exceeds the standard.

8. The drying device for producing polycarbonate according to claim 7, characterized in that: The controller is also used to control the first regeneration valve and the second regeneration valve of the current molecular sieve to open when the analyzer detects that the moisture content in the nitrogen of the current molecular sieve exceeds the standard.

9. The drying device for producing polycarbonate according to claim 5, characterized in that: The second main pipeline is connected in series with a third nitrogen blower and a second heater.

10. The drying device for producing polycarbonate according to claim 1, characterized in that: The nitrogen outlet of the drying tower is also connected to the gas inlet of the primary fluidized bed, and a second filter and a pressure regulating valve for filtering powder are connected in series between the nitrogen outlet of the drying tower and the gas inlet of the primary fluidized bed.

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