阅读说明：本技术 一种熔体输送方法及设备 (Melt conveying method and device ) 是由 吴培服 邓十全 吴迪 池卫 罗海洋 于 2021-08-31 设计创作，主要内容包括：本申请公开了一种熔体输送设备,包括熔体输送总泵、成品制造装置、造粒装置以及流量分配阀,其中,所述流量分配阀同步将熔体输送总泵输送的熔体的一部分通过管道输送至所述成品制造装置、将剩余部分的熔体通过管道输送至造粒装置；所述流量分配阀和所述成品制造装置之间并联设置有两路管道,其中第一路管道中的熔体流量由第二路管道中的压力控制。另外,本申请还公开了一种熔体输送方法。本申请通过设置两路并联的管道,第一路管道作为补偿管道,第二路管道作为主输送管道,第一路管道在负担额外的需求量的输送的同时,负责调控下游方向的熔体波动,从而减少了塑料成品的瑕疵,提升了成品的品质。(The application discloses a melt conveying device, which comprises a melt conveying master pump, a finished product manufacturing device, a granulating device and a flow distribution valve, wherein the flow distribution valve synchronously conveys one part of melt conveyed by the melt conveying master pump to the finished product manufacturing device through a pipeline and conveys the rest part of melt to the granulating device through the pipeline; two pipelines are connected in parallel between the flow distribution valve and the finished product manufacturing device, wherein the melt flow in the first pipeline is controlled by the pressure in the second pipeline. In addition, the application also discloses a melt conveying method. This application is through setting up two parallelly connected pipelines of way, and the pipeline of the first way is as compensating pipe, and the pipeline of the second way is as main pipeline, and the pipeline of the first way is in the transport of the extra demand of burden, and it is undulant to be responsible for the melt of regulation and control downstream direction to reduce the off-the-shelf flaw of plastics, promoted off-the-shelf quality.)

1. A melt conveying device, comprising a melt conveying general pump (100), a finished product manufacturing device (200), a granulating device (300) and a flow distribution valve (10), wherein the flow distribution valve (10) synchronously conveys one part of the melt conveyed by the melt conveying general pump (100) to the finished product manufacturing device (200) through a pipeline and conveys the rest part of the melt to the granulating device (300) through the pipeline; two pipelines are arranged in parallel between the flow distribution valve (10) and the finished product manufacturing device (200), wherein the melt flow in the first pipeline (20) is controlled by the pressure in the second pipeline (30).

2. The melt conveying equipment according to claim 1, wherein a compensating conveying pump (21) for melt flow control is arranged in the first pipeline (20), and a pressure transmitter (31) for detecting melt pressure is arranged in the second pipeline (30).

3. Melt conveying device according to claim 2, characterized in that the inlet of the first conduit (20) is arranged after the flow distributing valve (10) and before the pressure transmitter (31), and the outlet of the first conduit (20) is arranged before the finishing device (200) and after the flow distributing valve (10).

4. The melt conveying apparatus according to claim 2, wherein a metering pump (32) for metering the melt flow is further provided in the second pipeline (30), the metering pump (32) being provided downstream of the pressure transmitter (31); the inlet of the first pipeline (20) is arranged behind the flow distribution valve (10) and in front of the pressure transmitter (31), and the outlet of the first pipeline (20) is arranged in front of the finished product manufacturing device (200) and behind the metering pump (32).

5. The melt conveying apparatus according to claim 4, wherein a pipe length Δ L between the metering pump (32) and the pressure transmitter (31) and a difference Δ t between a flow rate change of the metering pump (32) and a start time of a pressure change of the pressure transmitter (31) are set as a gradient value for controlling the opening degree change of the compensating conveying pump (21).

6. The melt delivery apparatus of claim 1, wherein the melt delivery manifold (100) delivers an amount of melt greater than that required by the final manufacturing device (200).

7. Melt conveying device according to claim 6, characterized in that the total flow of the first (20) and second (30) ducts is equal to the demand of the finished product manufacturing means (200).

8. A method of melt conveying comprising the steps of: synchronously conveying a part of the melt conveyed by the melt conveying master pump 100 to a finished product manufacturing device (200) and conveying the rest part of the melt to a granulating device (300) through at least one flow distribution valve (10); the melt delivered to the finished product manufacturing device (200) is delivered through two parallel pipelines, wherein the melt flow in the first pipeline (20) is controlled by the pressure in the second pipeline (30).

9. The method of claim 8, wherein the total melt delivery pump (100) delivers an amount of melt greater than that required by the finished product manufacturing device (200).

10. The method of claim 9, wherein the total flow of the first conduit (20) and the second conduit (30) is equal to the demand of the final manufacturing device (200).

Technical Field

The application relates to a plastic product production technology in the field of chemical industry, in particular to a melt conveying method and equipment in the production process of plastic products.

Background

The plastic products are widely applied in the industrial and living fields. Common plastic products include various plastic films, plastic fiber filaments, and the like, which are prepared from thermoplastic high molecular compounds such as Polyethylene (PE), polyvinyl chloride (PVC), Polystyrene (PS), Polyester (PET), polypropylene (PP), nylon, and the like.

In the prior art document "problems and solutions of melt conveying systems" (synthetic fibers, 2002, 03 st., zhang yumei), a process flow that a melt is conveyed from a final polymerization kettle of a polyester device to a filament device through a melt discharge pump and then is conveyed to a twelve filament production line through a multiway valve and three booster pumps is analyzed. It is mentioned that in order to stabilize the melt delivery pressure, the system employs a cascade control scheme. When the problem that the operation of a controller is unbalanced and the booster pump trips without a fault occurs due to the fact that the pressure transmitter is close to the booster pump in flow and pressure control and a pulse signal generated in the operation of the booster pump, the technical solution for adjusting the position of the pressure transmitter is provided.

CN 101481827B discloses a control method and system for polyester melt conveying pressure, the control of polyester melt pressure is divided into five control links of polyester melt discharge pump flow control, final melt filter back pressure control, melt discharge pump speed control, granulator flow control and granulator speed control, the polyester melt discharge pump flow control, final melt filter back pressure control and granulator flow control form a cascade control loop by a main ring and an auxiliary ring, the melt discharge pump speed control is respectively controlled by a melt discharge pump speed PID control module, and the granulator speed control is respectively controlled by a granulator speed PID control module.

As can be seen from the above description of the prior art, the prior art only stays in the stage of simply controlling the melt flow in cascade through pressure feedback. However, since the viscosity of the plastic melt is much greater than that of other fluids, there is a problem in that the melt flow rate is delayed with respect to the pressure feedback. That is, when the measured melt pressure exceeds (or falls below) the threshold value, measures are taken to control the flow rate, and the amount of melt actually conveyed in the conveying pipe has already exceeded (or fallen below) the threshold value. On the other hand, if the position of the pressure transmitter is adjusted to be as close to the melt distribution valve as possible, the melt distribution valve needs to be immediately adjusted when the pressure is instantaneously changed, the abrupt instantaneous adjustment easily causes control signal divergence to cause control failure, and the abrupt instantaneous change of the flow rate also causes strong conveying pulse to destroy the conveying stability.

In a word, the existing melt conveying system is difficult to obtain a stable conveying effect through simple cascade control, and is not beneficial to obtaining excellent plastic finished products in a subsequent preparation process.

Disclosure of Invention

The technical problem to be solved by the present application is to provide a method and an apparatus for melt transportation, which reduce or avoid the aforementioned problems.

In order to solve the technical problems, the application provides a melt conveying device, which comprises a melt conveying master pump, a finished product manufacturing device, a granulating device and a flow distribution valve, wherein the flow distribution valve synchronously conveys one part of melt conveyed by the melt conveying master pump to the finished product manufacturing device through a pipeline and conveys the rest part of melt to the granulating device through a pipeline; two pipelines are connected in parallel between the flow distribution valve and the finished product manufacturing device, wherein the melt flow in the first pipeline is controlled by the pressure in the second pipeline.

Preferably, a compensation delivery pump for melt flow control is arranged in the first pipeline, and a pressure transmitter for detecting melt pressure is arranged in the second pipeline.

Preferably, the inlet of the first pipeline is arranged after the flow distribution valve and before the pressure transmitter, and the outlet of the first pipeline is arranged before the finished product manufacturing device and after the flow distribution valve.

Preferably, a metering pump for metering the melt flow is further arranged in the second pipeline, and the metering pump is arranged at the downstream of the pressure transmitter; the inlet of the first pipeline is arranged behind the flow distribution valve and in front of the pressure transmitter, and the outlet of the first pipeline is arranged in front of the finished product manufacturing device and behind the metering pump.

Preferably, the length Δ L of the pipeline between the metering pump and the pressure transmitter, and the starting time difference Δ t of the flow change of the metering pump and the pressure change of the pressure transmitter, and the ratio Δ L/Δ t between the two are used as gradient values for controlling and compensating the opening change of the delivery pump.

Preferably, the total melt delivery pump delivers an amount of melt greater than that required by the finished product manufacturing apparatus.

Preferably, the total flow of the first and second conduits is equal to the demand of the final manufacturing device.

In addition, the application also provides a melt conveying method, which comprises the following steps: synchronously conveying one part of the melt conveyed by the melt conveying master pump to a finished product manufacturing device and conveying the rest part of the melt to a granulating device through at least one flow distribution valve; and conveying the melt conveyed to the finished product manufacturing device through two pipelines connected in parallel, wherein the melt flow in the first pipeline is controlled by the pressure in the second pipeline.

This application is through setting up two parallelly connected pipelines of way, and the pipeline of the first way is as compensating pipe, and the pipeline of the second way is as main pipeline, and the pipeline of the first way is in the transport of the extra demand of burden, and it is undulant to be responsible for the melt of regulation and control downstream direction to reduce the off-the-shelf flaw of plastics, promoted off-the-shelf quality.

Drawings

The drawings are only for purposes of illustrating and explaining the present application and are not to be construed as limiting the scope of the present application.

FIG. 1 shows a schematic block diagram of a melt delivery apparatus according to an embodiment of the present application.

FIG. 2 shows a schematic block diagram of a melt delivery apparatus according to another embodiment of the present application.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present application, embodiments of the present application will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

The present application provides a melt conveying apparatus as shown in fig. 1, which can be used to convey melts of various plastic resins, including but not limited to thermoplastic high molecular compounds such as polyethylene, polyvinyl chloride, polystyrene, polyester, polypropylene, nylon, etc. to a finished product manufacturing device to prepare various plastic finished products. The plastic finished product includes, but is not limited to, plastic film, fiber filament, etc.

As shown in the drawings, the melt conveying equipment provided by the present application comprises a melt conveying general pump 100, at least one finished product manufacturing device 200, at least one granulating device 300 and at least one flow distribution valve 10, wherein the flow distribution valve 10 synchronously conveys a part of the melt conveyed by the melt conveying general pump 100 to the finished product manufacturing device 200 through a pipeline, and conveys the rest of the melt to the granulating device 300 through a pipeline. The melt can be directly from a melt discharge tank at the polymerization terminal or indirectly from a resin melt obtained by remelting a polymerization master batch. The product manufacturing apparatus 200 may be any conventional plastic product manufacturing apparatus, including a plastic film stretch forming apparatus or a plastic filament draw forming apparatus.

In the prior art, a granulating device is usually used as a backup of a finished product manufacturing device, a melt conveying master cylinder conveys all melts to the finished product manufacturing device, and when the finished product manufacturing device is shut down due to problems, the melt is conveyed to the granulating device. This does not solve the problem of a lower melt flow in the direction of the finished product. In this application melt conveying scheme, the fuse-element is carried to two directions in step, when the fuse-element flow of finished product direction takes place undulant, can increase and decrease the regulation and control through the fuse-element flow of granulation direction.

That is, in the present application, the amount of the melt delivered by the melt delivery pump 100 is greater than the amount required by the product manufacturing apparatus 200, so that the opening degree of the flow distribution valve 10 can be flexibly controlled according to the requirement of the product manufacturing apparatus 200, so that the amount of the melt delivered to the granulating apparatus 300 is changed to meet the requirement of the product direction. Since the granulating device 300 obtains a semi-finished product of a plastic product, the melt flow rate in the granulating direction does not need to be precisely controlled, and the product manufacturing device 200 obtains a plastic product such as a plastic film, a fiber filament and the like, and the melt flow rate in the direction needs to be precisely controlled to obtain a high-quality plastic product.

In addition, as shown in the figure, two pipelines are arranged in parallel between the flow distribution valve 10 and the product manufacturing apparatus 200, wherein the flow rate of the melt in the first pipeline 20 is controlled by the pressure in the second pipeline 30. In a specific embodiment, a compensating delivery pump 21 for controlling the melt flow is disposed in the first pipeline 20, and a pressure transducer 31 for detecting the melt pressure is disposed in the second pipeline 30. In another embodiment, the inlet of the first pipeline 20 is disposed after the flow distribution valve 10 and before the pressure transmitter 31, and the outlet of the first pipeline 20 is disposed before the product manufacturing apparatus 200 and after the pressure transmitter 31.

The application sets up two routes pipeline in parallel, and first pipeline 20 is as compensating pipe, and second pipeline 30 is as main pipeline, and the total flow of first pipeline 20 and second pipeline 30 equals the demand of finished product manufacturing device 200. Normally, the second pipeline 30 is used as the main conveying pipeline to convey most of the required melt, for example, 80% of the required amount, and once the pressure in the second pipeline 30 becomes higher as measured by the pressure transmitter 31, it means that the conveying amount in the product direction needs to be reduced, for example, the melt distribution amount of the flow distribution valve 10 is controlled by the melt pressure detected by the pressure transmitter, so as to convey more melt to the granulation direction. However, in this case, a part of the excess melt is already accumulated in the second line 30 from the flow distributing valve 10 to the pressure transmitter 31, and this part of the excess melt is only allowed to be transported downstream in the prior art. The present application, by providing the first conduit 20, while conveying the excess, for example 20%, of the demand, is responsible for controlling the downstream flow fluctuations of the melt, for example, by pumping away a portion of the excess melt that has been accumulated by the compensating pump 21, so that the excess melt is distributed in a buffer over a relatively long downstream conveying distance over a period of time. Similarly, when the pressure in the second pipe 30 becomes lower as measured by the pressure transmitter 31, the melt distribution amount of the flow distribution valve 10 is controlled by the melt pressure detected by the pressure transmitter to decrease the melt conveying amount in the granulation direction. At the same time, the melt conveying capacity of the compensation conveying pump 21 in the first pipeline 20 is reduced, so that the part of the flow rate lacking in the second pipeline 30 can be partially supplemented in a period of time, and the melt flow rate reduction amplitude in the downstream direction can be reduced. The two pipelines are arranged in parallel, melt conveying fluctuation cannot be absolutely removed, but fluctuation can be balanced as far as possible, and therefore the quality of subsequent finished products can be improved.

In addition, a metering pump 32 for metering the melt flow rate may be further provided in the second branch pipe 30, and the metering pump 32 is provided downstream of the pressure transmitter 31. At this time, the inlet of the first pipeline 20 is disposed after the flow distributing valve 10 and before the pressure transmitter 31, and the outlet of the first pipeline 20 is disposed before the finishing apparatus 200 and after the metering pump 32.

The metering pump 32 is designed as a complement to the pressure transmitter 31 for measuring the actual melt flow in the second pipe 30. As mentioned above, the melt conveying device of the present application is not limited to conveying one melt, and in some cases, melt materials with different compositions can be conveyed. The viscosity of different melts is different, and the parameters for controlling the melt flow in the first pipeline 20 through the pressure in the second pipeline 30 are also changed. Therefore, in the above embodiment of the present application, the metering pump 32 is further disposed in the second pipeline 30, and the pipeline length Δ L between the metering pump 32 and the pressure transmitter 31, and the start time difference Δ t between the flow rate change of the metering pump 32 and the pressure change of the pressure transmitter 31 obtained by measurement are used, so that the ratio Δ L/Δ t between the two is used as a gradient value for controlling the opening change of the compensation delivery pump 21, thereby perfectly solving the control problem of the compensation delivery pump 21 under different melt conditions, and improving the universality of the device.

For example, when the flow rate of the downstream metering pump 32 changes, the pressure change does not reach the upstream pressure transmitter 31, the time difference Δ t between the two changes represents the time of the melt property transfer change, and the melt property transfer change speed can be calculated by the ratio of the pipe length Δ L to the time difference Δ t, and can be used for controlling the gradient value for compensating the opening change of the delivery pump 21 gradually reaching the control value. For example, the pressure change in the second pipeline 30 is measured by the pressure transmitter 31, and the delivery capacity of the compensating delivery pump 21 needs to be controlled to reach a certain control value, at this time, the opening degree of the compensating delivery pump 21 is not adjusted to a required size at a time, but the opening degree of the compensating delivery pump 21 is gradually adjusted to the required size from zero by taking the value of Δ L/Δ t as a gradient value for adjusting the opening degree, so that the technical effect of buffering and distributing the melt with different properties to a relatively long delivery distance downstream in a period of time can be flexibly obtained.

The melt conveying method of the present application is further described below with reference to the drawings. Of course, the melt-conveying method of the present application is actually described in the above-mentioned introduction to the apparatus in inclusion, which is supplemented by the summary of the present application in the following by a summary form.

As shown, the melt conveying method of the present application comprises the following steps: a part of the melt delivered by the melt delivery master pump 100 is delivered to the finished product manufacturing device 200 and the rest of the melt is delivered to the granulating device 300 synchronously through at least one flow distribution valve 10; the melt to be delivered to the product manufacturing apparatus 200 is delivered through two pipes connected in parallel, wherein the flow rate of the melt in the first pipe 20 is controlled by the pressure in the second pipe 30.

In an embodiment, a plurality of flow distribution valves 10 may be further disposed in parallel in the melt conveying apparatus, and the melt conveyed by the melt conveying master pump 100 is respectively conveyed to the plurality of product manufacturing devices 200 and the plurality of granulating devices 300 through the plurality of flow distribution valves 10 disposed in parallel, depending on the problem of matching the production capacity of the melt with the consumption of the product manufacturing devices. For example, assuming that the capacity of the melt is 50 tons per day and the consumption of one finished product line is 20 tons per day, it may be necessary to provide two finished product lines and 1-2 granulation lines, as shown in fig. 2.

It should be appreciated by those skilled in the art that while the present application is described in terms of several embodiments, not every embodiment includes only a single embodiment. The description is thus given for clearness of understanding only, and it is to be understood that all matters in the embodiments are to be interpreted as including all technical equivalents which are encompassed by the claims and are to be interpreted as combined with each other in a different embodiment so as to cover the scope of the present application.

The above description is only illustrative of the present invention and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations that may be made by those skilled in the art without departing from the spirit and principles of this application shall fall within the scope of this application.