CN116734592B

CN116734592B - Control method, device, equipment and storage medium for moisture of dry PVC

Info

Publication number: CN116734592B
Application number: CN202311002615.3A
Authority: CN
Inventors: 侯卫锋; 任玉龙; 叶建位
Original assignee: Zhejiang Zhongzhida Technology Co ltd
Current assignee: Zhejiang Zhongzhida Technology Co ltd
Priority date: 2023-08-10
Filing date: 2023-08-10
Publication date: 2023-10-27
Anticipated expiration: 2043-08-10
Also published as: CN116734592A

Abstract

The application discloses a control method, a device, equipment and a computer readable storage medium for drying PVC water, which are applied to drying equipment for heating air flow by high-temperature steam and drying PVC materials by the heating air flow, wherein the control method for drying PVC water comprises the following steps: collecting the steam pressure, the drying temperature and the water content of high-temperature steam; according to the changes of steam pressure, drying temperature and moisture content, respectively determining a first regulating variable, a second regulating variable and a third regulating variable; and the valve position adjusting quantity of the steam control valve is determined according to the three adjusting quantities, and the steam control valve is controlled and adjusted according to the valve position adjusting quantity. The application takes into account the influence of the valve position opening change of the steam control valve on the state of each aspect such as steam pressure, drying temperature and moisture content, is beneficial to maintaining the stability of the whole drying state and improving the stability of the moisture content and PVC quality.

Description

Control method, device, equipment and storage medium for moisture of dry PVC

Technical Field

The application relates to the technical field of PVC production, in particular to a control method, a device and equipment for moisture of dry PVC and a computer readable storage medium.

Background

Polyvinyl chloride (Polyvinyl chloride), abbreviated as PVC in English, is a polymer prepared by polymerizing Vinyl Chloride Monomer (VCM) under the action of initiator such as peroxide and azo compound or light and heat according to free radical polymerization reaction mechanism. The change of the PVC water content of the PVC product directly affects the quality of the PVC product, so that the stability of the PVC water content is ensured in the production process, and the PVC water content has very important significance. However, it is difficult to realize stable control of the water content of PVC under the influence of actual production conditions. At present, in order to ensure that the PVC product is qualified, the adopted means are to control the water content of the PVC to be lower as much as possible, but the method cannot ensure the stability of the water content of the PVC, and the drying cost is increased possibly because the PVC product is dried in a transitional way.

Disclosure of Invention

The invention aims to provide a control method, a device and equipment for the moisture of dry PVC and a computer readable storage medium, which can reduce the fluctuation range of the moisture content of the dried PVC material to a certain extent and are beneficial to ensuring the stability of the quality of the PVC material.

In order to solve the technical problems, the invention provides a control method for drying PVC water, which is applied to drying equipment for drying PVC materials, wherein the drying equipment is used for heating air flow by utilizing high-temperature steam and heating the PVC materials by utilizing the heated air flow; the control method comprises the following steps:

Collecting the steam pressure of high-temperature steam, the drying temperature of the dried PVC material and the moisture content of the dried PVC material;

determining a first adjustment amount of an output steam control valve based on the change in steam pressure;

PID feedback adjustment operation is carried out on the drying temperature and the temperature set value, and a second adjustment quantity of the steam control valve is determined;

determining a third adjustment amount of the steam control valve according to the moisture content and the moisture set point;

and determining valve position adjustment quantity of the steam control valve according to the first adjustment quantity, the second adjustment quantity and the third adjustment quantity, and controlling and adjusting the steam control valve according to the valve position adjustment quantity.

Optionally, determining a first adjustment amount of the output steam control valve according to the change in the steam pressure includes:

and taking the product of the difference between the current steam pressure and the last steam pressure and the steam pressure compensation coefficient as the first adjustment quantity.

Optionally, determining a third adjustment amount of the steam control valve according to the moisture content and the moisture set point includes:

performing difference operation on the water content and the water set value to determine a water deviation value; determining a temperature change trend according to the drying temperature;

When the moisture deviation value and the temperature change trend meet a first condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a first preset regulating quantity; the first condition is that the moisture deviation value is a positive value with a magnitude larger than a first deviation threshold value and the temperature change trend is reduced;

when the moisture deviation value and the temperature change trend meet a second condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a second preset regulating quantity; the second condition is that the moisture deviation value is a positive value with a magnitude smaller than the first deviation threshold and larger than a second deviation threshold, and the temperature change trend is declining;

when the moisture deviation value and the temperature change trend meet a third condition, the value of the third regulating quantity is a negative value and the magnitude of the third regulating quantity is a second preset regulating quantity; the third condition is that the moisture deviation value is a negative value with a magnitude smaller than the first deviation threshold value and larger than a second deviation threshold value, and the temperature change trend is rising;

when the moisture deviation value and the temperature change trend meet a fourth condition, the value of the third regulating quantity is a negative value and the value of the third regulating quantity is a first preset regulating quantity; wherein the fourth condition is that the moisture deviation value is a negative value larger than a first deviation threshold value and the temperature change trend is rising;

When the moisture deviation value and the temperature variation trend do not satisfy any one of the first condition, the second condition, the third condition, and the fourth condition, the third adjustment amount is 0.

Optionally, after determining the valve position adjustment amount, further comprising:

when the valve position adjustment amount is larger than an adjustment amount threshold value, the adjustment amount threshold value is taken as the valve position adjustment amount;

and when the accumulated valve position adjustment quantity of the steam control valve in a preset time period before the current moment is larger than a valve position adjustment threshold value, the valve position adjustment quantity is 0.

Optionally, the control method for the moisture of the dry PVC further comprises the following steps:

when the temperature set value is changed according to the adjusting instruction, determining a step adjusting quantity according to the ratio of the set value difference value between the current temperature set value and the temperature set value before the change and the set proportion coefficient;

if the step adjustment amount is larger than the first adjustment threshold value and smaller than the second adjustment threshold value, taking the step adjustment amount as a fourth adjustment amount;

if the step adjustment amount is smaller than a first adjustment threshold, taking the first adjustment threshold as the fourth adjustment amount;

If the step adjustment amount is larger than a second adjustment threshold, taking the second adjustment threshold as the fourth adjustment amount;

wherein, the positive and negative of the fourth regulating variable are the same as the positive and negative of the set value difference value;

determining a valve position adjustment amount of the steam control valve based on the first adjustment amount, the second adjustment amount, and the third adjustment amount, comprising:

and taking the sum operation result of the first adjustment amount, the second adjustment amount, the third adjustment amount and the fourth adjustment amount as the valve position adjustment amount.

collecting the drying amount of the PVC material;

if the absolute value of the difference between the current time drying amount and the last time drying amount of the PVC material is larger than a drying amount threshold, judging whether the accumulated change amount of the temperature set value in a first preset time period before the current time reaches a first accumulated threshold, if not, determining the change amount of the temperature set value according to the ratio between the difference of the drying amount and a load steam ratio coefficient;

and changing the temperature set value according to the temperature set value change amount. Optionally, the control method for the moisture of the dry PVC further comprises the following steps:

Respectively carrying out difference absolute value operation between the moisture content and the moisture set value and between the drying temperature and the temperature set value to obtain moisture deviation and temperature deviation;

when the moisture deviation is larger than a first moisture deviation threshold value and the accumulated change of the temperature set value in a first preset time period before the current moment is smaller than a second accumulated threshold value, the second accumulated threshold value is used as the temperature set value change;

when the moisture deviation is smaller than a second moisture deviation threshold, if the temperature deviation value is larger than a first temperature deviation threshold and the accumulated change of the temperature set value in a first preset time period before the current moment is smaller than a third accumulated threshold, the third accumulated threshold is used as the temperature set value change;

when the moisture deviation is smaller than a second moisture deviation threshold, if the temperature deviation value is smaller than the first temperature deviation threshold and larger than the second temperature deviation threshold, and the accumulated change of the temperature set value in a first preset time period before the current moment is smaller than a third accumulated threshold, taking the drying temperature at the current moment as a new temperature set value;

When the moisture deviation is larger than a second moisture deviation threshold value and smaller than the first moisture deviation threshold value in a second preset time period before the current moment and the temperature deviation value is larger than a second temperature deviation threshold value, if the moisture content is larger than the moisture set value, the drying temperature is larger than the temperature set value, and the accumulated change amount of the temperature set value in the first preset time period before the current moment is smaller than a third accumulated threshold value, the magnitude of the third accumulated threshold value is taken as the magnitude of the temperature set value change amount, and the value is a negative value;

when the moisture deviation is larger than a second moisture deviation threshold value and smaller than the first moisture deviation threshold value in a second preset time period before the current moment and the temperature deviation value is larger than a second temperature deviation threshold value, if the moisture content is larger than the moisture set value, the drying temperature is larger than the temperature set value, and the accumulated change amount of the temperature set value in the first preset time period before the current moment is smaller than a third accumulated threshold value, the third accumulated threshold value is used as the change amount of the temperature set value, and the value is a positive value;

And changing the temperature set value according to the change amount of the temperature set value.

The control device for drying the PVC water is applied to drying equipment for drying PVC materials, wherein the drying equipment is used for heating air flow by utilizing high-temperature steam and heating the PVC materials by utilizing the heated air flow; the control device includes:

the data acquisition module is used for acquiring the steam pressure of the high-temperature steam, the drying temperature of the dried PVC material and the moisture content of the dried PVC material;

the first operation module is used for determining a first adjustment quantity of the output steam control valve according to the change of the steam pressure;

the second operation module is used for carrying out PID feedback adjustment operation on the drying temperature and the temperature set value and determining a second adjustment quantity of the steam control valve;

the third operation module is used for determining a third adjustment quantity of the steam control valve according to the moisture content and the moisture set value;

the valve position regulating and controlling module is used for determining the valve position regulating quantity of the steam control valve according to the first regulating quantity, the second regulating quantity and the third regulating quantity and controlling and regulating the steam control valve according to the valve position regulating quantity.

A control device for drying PVC moisture comprising:

a memory for storing a computer program;

a processor for implementing the steps of the method for controlling moisture in dry PVC as described in any one of the above when executing the computer program.

A computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of the method of controlling moisture in a dry PVC as defined in any one of the preceding claims.

The control method, the device, the equipment and the computer readable storage medium for drying the PVC water are applied to drying equipment for drying PVC materials, wherein the drying equipment is used for heating air flow by utilizing high-temperature steam and heating the PVC materials by utilizing the heated air flow; the control method for the moisture of the dry PVC comprises the following steps: collecting the steam pressure of high-temperature steam, the drying temperature of the dried PVC material and the moisture content of the dried PVC material; determining a first adjustment amount of the output steam control valve according to the change of the steam pressure; PID feedback adjustment operation is carried out on the drying temperature and the temperature set value, and a second adjustment quantity of the steam control valve is determined; determining a third adjustment amount of the steam control valve according to the moisture content and the moisture set value; and determining the valve position adjustment quantity of the steam control valve according to the first adjustment quantity, the second adjustment quantity and the third adjustment quantity, and controlling and adjusting the steam control valve according to the valve position adjustment quantity.

According to the application, the PVC material is dried by mainly utilizing the air flow heated by the steam, so that when the moisture content of the PVC material is controlled, the flow, pressure and the like of the steam for heating the air flow can be controlled by controlling the valve position of the steam control valve, and the temperature of the air flow is further changed, namely the heating temperature of the air flow for drying and heating the PVC material is changed to a certain extent, and the moisture in the drying process of the PVC material is controlled; on the basis, in order to ensure the moisture stability of the dried PVC material, in the valve position opening adjusting process of the steam control valve, three different aspects of data conditions such as the steam pressure in a steam pipeline, the drying temperature for heating the PVC material, the moisture content of the finally output PVC material and the like are considered, three different adjusting amounts are correspondingly determined, the valve position final adjusting amount of the steam control valve is combined with the three adjusting amounts, the influence of the valve position opening change of the steam control valve on the data fluctuation in all aspects is comprehensively considered, the stability of the running state of the whole drying equipment is favorably maintained, the stability of the moisture content of the PVC material is improved to a certain extent, and the stability of the quality of the PVC material is ensured.

Drawings

For a clearer description of embodiments of the application or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description below are only some embodiments of the application, and that other drawings can be obtained from them without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a drying apparatus for drying heated PVC material;

FIG. 2 is a schematic flow chart of a method for controlling moisture of a dry PVC according to an embodiment of the present application;

FIG. 3 is a schematic flow chart of determining a third adjustment amount according to an embodiment of the present application;

FIG. 4 is a flow chart of determining the variation of the temperature set point according to the embodiment of the present application;

FIG. 5 is a graph showing the fluctuation of the water content of PVC materials according to the embodiment of the application;

FIG. 6 is a block diagram of a control device for moisture content of a dry PVC according to an embodiment of the application.

Detailed Description

FIG. 1 is a schematic diagram of a drying apparatus for drying heated PVC material. In the apparatus shown in fig. 1, the high temperature steam heats the cold air blown by the blower in the heat exchanger to generate a hot air flow; the hot air flow sequentially passes through the drying cylinder and the drying sieve together with the PVC material, and carries out drying and heating on the PVC material in the process of passing through the drying cylinder and the drying sieve, and finally flows out of the rotary discharging hopper from the PVC material.

It is obvious that the moisture content of the dried PVC material depends largely on the temperature of the hot air flow, but the temperature of the hot air flow depends on the heat absorbed by the hot air flow when the high-temperature steam and the hot air flow exchange heat. The temperature of the high temperature steam output in the steam pipe is generally relatively constant. Depending on the amount of heat absorbed by the hot air stream, it is therefore generally dependent on the steam pressure and steam flow in the steam line, which are obviously controlled by the valve opening of the steam control valve. It can be seen that the moisture content of the PVC material can be adjusted by controlling the valve position opening of the steam control valve throughout the drying process of the PVC material. However, because the high-temperature steam is not directly heated but indirectly heated by hot air flow, the control of the water content of the PVC material by the valve position adjustment of the steam control valve has serious hysteresis, and if the valve position opening of the steam control valve is adjusted only by the water feedback of the PVC material output by the drying sieve, the water fluctuation of the PVC material after drying is huge, which is unfavorable for maintaining the quality stability of the PVC material.

Therefore, the application provides a technical scheme capable of improving the stability of the water content of the PVC material to a certain extent.

In order to better understand the aspects of the present application, the present application will be described in further detail with reference to the accompanying drawings and detailed description. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

As shown in FIG. 2, FIG. 2 is a flow chart of a method for controlling moisture of a dry PVC according to an embodiment of the present application.

The control method of the moisture of the dried PVC is mainly applied to drying equipment for drying PVC materials, and the drying equipment is used for heating air flow by utilizing high-temperature steam and heating the PVC materials by utilizing the heated air flow.

In one embodiment of the present application, the method for controlling the moisture content of the dry PVC may comprise:

s11: the steam pressure of high-temperature steam, the drying temperature of the dried PVC material and the water content of the dried PVC material are collected.

It can be understood that the PVC material is continuously introduced into the drying cylinder and the drying screen in the drying process of the PVC material, so that the steam pressure, the drying temperature, the moisture content and the like are continuously monitored in real time or periodically monitored at short intervals in the whole drying process of the PVC material, thereby providing timely and reliable monitoring data for valve position opening adjustment of the steam control valve.

In addition, the vapor pressure of the high-temperature vapor collected in the present embodiment refers to the vapor pressure in the vapor pipe extending into the heat exchanger after passing through the vapor control valve.

The drying temperature for drying the PVC material mainly refers to the temperature in the drying environment in the drying process of the PVC material; as shown in fig. 1, in the drying apparatus shown in fig. 1, the drying temperature generally refers to the temperature within the drying screen. The drying temperature reflects the drying capacity of the hot air flow on the PVC material to a certain extent, and the height of the drying temperature is directly influenced by high-temperature steam.

In addition, the water content of the PVC material is mainly data obtained by detecting the water content of the PVC material output by the rotary blanking hopper.

S12: a first adjustment amount of the output steam control valve is determined based on the change in the steam pressure.

The change in steam pressure in the heat exchanger causes a change in the heating value of the steam, which in turn causes a change in the temperature of the hot air stream heated by the high temperature steam, which in turn causes a change in the drying temperature.

Alternatively, in determining the first adjustment amount based on the vapor pressure, specifically, a product between the vapor pressure compensation coefficient and a difference between the vapor pressure at the present time and the vapor pressure at the previous time may be used as the first adjustment amount.

The magnitude of the compensation coefficient for vapor pressure may be a constant coefficient determined based on trial and error or based on human experience.

Of course, in this embodiment, the first adjustment amount is determined in a proportional relationship between the variation amount of the vapor pressure and the first adjustment amount; in practical application, other association relation formulas can be set between the steam pressure and the first regulating variable, so long as the influence of the change of the steam pressure on the fluctuation of the water content of the PVC material can be ensured, and the valve position opening degree of the steam control valve can be regulated more accurately.

In order to avoid excessive pressure abrupt change caused by abrupt change of the steam air valve, the first adjustment amount may be further limited in size, and taking the maximum opening of the valve position opening as 1 as an example, the first adjustment amount may be determined to be not more than 0.1 each time; when the determined first adjustment amount is greater than 0.1, then 0.1 is used as the first adjustment amount.

S13: and PID feedback adjustment operation is carried out on the drying temperature and the temperature set value, and a second adjustment quantity of the steam control valve is determined.

PID feedback regulation is a relatively common feedback regulation mode. Since the high-temperature steam directly heats the hot air flow, that is to say directly influences the drying temperature, for this purpose, a second control variable for the corresponding valve position opening adjustment for the fluctuating change of the drying temperature can be determined by means of a PID feedback control algorithm.

S14: a third adjustment of the steam control valve is determined based on the moisture content.

In this embodiment, the valve position opening of the steam control valve is adjusted, so that the final purpose is to realize control and adjustment of the water content in the PVC material, therefore, when the valve position opening of the steam control valve is actually controlled, the water content in the PVC material is also used as one of reference factors, which is favorable for improving the accuracy of valve position opening adjustment and ensuring the stability of the water content.

S15: and determining the valve position adjustment quantity of the steam control valve according to the first adjustment quantity, the second adjustment quantity and the third adjustment quantity, and controlling and adjusting the steam control valve according to the valve position adjustment quantity.

Respectively feeding back and determining a first regulating quantity, a second regulating quantity and a third regulating quantity of the steam control valve according to three different aspects of data of steam pressure, drying temperature and moisture content; in the process of finally determining the valve position adjustment amount of the steam control valve by combining the three adjustment amounts, the first adjustment amount, the second adjustment amount and the third adjustment amount may be directly added and summed, and the final sum result is taken as the final valve position adjustment amount.

Based on the above discussion, the final valve position adjustment quantity of the steam control valve in the application simultaneously takes into account the data changes in three different aspects of steam pressure, drying temperature, water content of PVC materials and the like, so that the valve position adjustment quantity determined by adding and summing the corresponding three adjustment quantities is favorable for maintaining the stability of the state of each aspect in the whole running process of the drying equipment and also favorable for ensuring the stability of the water content of the PVC materials.

Furthermore, considering that if the valve position opening of the steam control valve is greatly increased or decreased too frequently, the stability of the whole drying environment is not maintained, in another alternative embodiment of the present application, the method may further include:

When the valve position adjustment quantity is larger than the adjustment quantity threshold value, taking the adjustment quantity threshold value as the valve position adjustment quantity;

when the accumulated valve position adjustment amount of the steam control valve in a preset time period before the current moment is larger than the valve position adjustment threshold value, the valve position adjustment amount is 0.

In the embodiment, the valve position opening is regulated in two different aspects such as the valve position regulating quantity and the valve position regulating frequency, so that the problem of stability of the whole drying environment is solved by avoiding too frequent change or too large change of the valve position opening of the steam control valve, and the stability of the water content in the PVC material is also maintained to a certain extent.

In summary, in the valve position opening adjusting process of the steam control valve, an adjusting quantity is respectively determined based on the steam pressure, the drying temperature and the water content of the PVC material, and the final valve position adjusting quantity of the steam control valve is determined by the three adjusting quantities, so that the influence of the valve position opening change of the steam control valve on the data fluctuation in all aspects is more comprehensively considered, the stability of the running state of the whole drying equipment is maintained, and the stability of the water content of the PVC material is improved to a certain extent.

Based on any of the above embodiments, for the process of determining the third adjustment amount of the steam control valve according to the moisture content and the moisture set point in the above embodiments, in an alternative embodiment of the present application, the method may specifically include:

s141: performing difference operation on the water content and the water set value to determine a water deviation value; determining a temperature change trend according to the drying temperature;

s142: when the moisture deviation value and the temperature change trend meet the first condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a first preset regulating quantity; the first condition is that the moisture deviation value is a positive value with the size larger than a first deviation threshold value and the temperature change trend is reduced;

s143: when the moisture deviation value and the temperature change trend meet the second condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a second preset regulating quantity; the second condition is that the moisture deviation value is a positive value with the size smaller than the first deviation threshold value and larger than the second deviation threshold value, and the temperature change trend is reduced;

s144: when the moisture deviation value and the temperature change trend meet a third condition, the value of the third regulating quantity is a negative value and the magnitude of the third regulating quantity is a second preset regulating quantity; the third condition is that the moisture deviation value is a negative value with the size smaller than the first deviation threshold value and larger than the second deviation threshold value, and the temperature change trend is rising;

S145: when the moisture deviation value and the temperature change trend meet the fourth condition, the value of the third regulating quantity is a negative value and the value of the third regulating quantity is a first preset regulating quantity; the fourth condition is that the moisture deviation value is a negative value larger than the first deviation threshold value and the temperature change trend is rising;

s146: when the moisture deviation value and the temperature variation trend do not satisfy any one of the first condition, the second condition, the third condition, and the fourth condition, the third adjustment amount is 0.

Referring to fig. 3, fig. 3 is a schematic flow chart of determining a third adjustment amount according to an embodiment of the present application. In practical applications, the third adjustment amount may be determined according to the flow shown in fig. 3. Shown in FIG. 3In the embodiment(s) toRepresenting a moisture deviation value between the moisture content and the moisture set point; the first deviation threshold is denoted by S1 and the second deviation threshold is denoted by S2; the first preset adjustment amount is represented by K1, and the second preset adjustment amount is represented by K2; it can be understood that the first deviation threshold, the second deviation threshold, the first preset adjustment amount, and the second preset adjustment amount in this embodiment are all positive values, and the first deviation threshold is smaller than the second deviation threshold, and the first preset adjustment amount is smaller than the second preset adjustment amount.

In addition, the temperature change trend in this embodiment refers to the drying temperature of the PVC material, which may be determined based on the drying temperature collected in a period of time before the current time, for example, a linear fitting of a least square method may be performed based on the drying temperature collected in a period of time from the current time to 10 minutes before the current time, and if the slope of a straight line obtained by the fitting is positive, the rising trend is the rising trend, and if the slope is negative, the falling trend is the falling trend.

As mentioned above, the influence of the valve position opening adjustment of the steam control valve on the drying temperature has hysteresis, and the influence of the drying temperature on the moisture content also has hysteresis, so as to reduce the hysteresis field of the valve position opening adjustment of the steam control valve on the moisture content adjustment, and increase the influence of the real-time moisture content measurement value on the valve position opening adjustment.

Based on any of the above embodiments, in the process of drying the PVC material, the drying temperature is a parameter of directly applying the moisture content of the PVC material, and when measuring whether the drying temperature is reasonable, a temperature setting value needs to be set, and when considering the influence of the valve opening adjustment of the steam control valve on the drying temperature, the adjustment amount of the corresponding valve opening is also determined mainly by the deviation degree of the drying temperature relative to the temperature setting value. However, in the practical application process, when the PVC material is conveyed into a drying space such as a drying cylinder and a drying screen, the flow rate of the material, the water content of the material, the temperature of high-temperature steam for heating cold air flow and other factors may fluctuate; at this time, the temperature set value corresponding to the drying temperature also needs to be adjusted to a certain extent, so that the stability of the final moisture content of the PVC material can be better maintained.

Therefore, when the valve position opening of the steam control valve is actually adjusted, in order to ensure that the drying temperature can reach the temperature set value quickly after the temperature set value of the drying sieve is changed, an instantaneous step value can be given to the valve position opening of the steam control valve when the temperature set value of the drying sieve is changed, so that the drying temperature reaches the changed temperature set value more quickly than the normal adjusting speed.

Based on the discussion above, in an alternative embodiment of the present application, it may further include:

s21: when the temperature set value is changed according to the adjusting instruction, determining the step adjusting quantity according to the ratio of the set value difference between the current temperature set value and the temperature set value before the change and the set proportion coefficient.

It should be noted that, the set scaling factor in this embodiment may be the same as the scaling system used in the PID feedback adjustment operation when determining the second adjustment amount in the above embodiment.

S22: and if the step adjustment amount is larger than the first adjustment threshold value and smaller than the second adjustment threshold value, taking the step adjustment amount as a fourth adjustment amount.

S23: and if the magnitude of the step adjustment quantity is smaller than the first adjustment threshold value, taking the first adjustment threshold value as the magnitude of the fourth adjustment quantity.

S24: and if the magnitude of the step adjustment quantity is larger than the second adjustment threshold value, taking the second adjustment threshold value as the magnitude of the fourth adjustment quantity.

Wherein, the positive and negative of the fourth regulating variable are the same as the positive and negative of the set value difference value.

Accordingly, determining a valve position adjustment amount of the steam control valve based on the first adjustment amount, the second adjustment amount, and the third adjustment amount includes:

and taking the sum of the first adjustment amount, the second adjustment amount, the third adjustment amount and the fourth adjustment amount as valve position adjustment amount.

In this embodiment, in order to avoid an excessive fourth adjustment amount that is finally determined, the magnitude of the fourth adjustment amount is defined in a range section between the first adjustment threshold value and the second adjustment threshold value.

It will be appreciated that if the difference between the current temperature set point and the temperature set point before modification is positive, the current temperature set point will be increased relative to the temperature set point before modification, and accordingly, the corresponding valve opening should be increased for the change of the steam control valve needle to the temperature set point, and thus the corresponding fourth adjustment amount will be a positive value. Otherwise, when the difference value of the set value is negative, the change of the set value of the temperature is reduced, and correspondingly, the valve position opening of the steam control valve is also reduced, and the fourth adjustment amount is also negative.

On the basis, if the step adjustment amount determined based on the set value difference and the proportional coefficient is between the first adjustment threshold and the second adjustment threshold, the step adjustment amount can be directly used as a fourth adjustment amount; when the step adjustment amount is smaller than the first adjustment threshold, the first adjustment threshold can be directly used as a fourth adjustment amount, so that the problem that the drying temperature cannot be quickly adjusted to about a reset temperature set value due to the adjustment change of the valve position opening degree caused by too small fourth adjustment amount is avoided; and when the step adjustment quantity is larger than the second adjustment threshold value, the second adjustment threshold value is used as the fourth adjustment quantity, so that the problem of overlarge drying temperature fluctuation caused by overlarge valve position opening degree change is avoided.

After determining a fourth adjustment amount corresponding to adjusting the valve position opening of the steam control valve in response to the temperature set point change, the fourth adjustment amount may be summed together with the first adjustment amount, the second adjustment amount, and the third adjustment amount in each of the above embodiments to determine a final valve position adjustment amount of the steam control valve. Therefore, in the process of controlling and adjusting the valve position of the steam control valve, the embodiment further considers the influence of the change of the temperature setting value on the whole drying state on the basis of valve position adjustment required for the change of various factors such as steam pressure, drying temperature, water content of the PVC material and the like, further determines the corresponding fourth adjustment amount, finally carries out superposition summation on the adjustment amounts corresponding to the four factors in different aspects to determine more reasonable valve position adjustment amount, ensures that the temperature of the PVC material after final drying is closer to the ideal target water content on the basis of maintaining the stability of the whole drying state, and is favorable for more accurate adjustment of the drying process of the PVC material.

As described above, in the process of drying PVC materials, the temperature set point may be changed due to various factors such as the production speed of PVC materials, the moisture content of PVC materials themselves, the temperature change of high temperature steam, and the like. The specific manner in which the temperature set point adjustment changes are specified is described in the following specific examples.

In an alternative embodiment of the present application, it may further include:

s31: collecting the drying amount of PVC materials;

s32: if the absolute value of the difference between the current time drying amount and the last time drying amount of the PVC material is larger than the drying amount threshold, judging whether the accumulated change amount of the temperature set value in a first preset time period before the current time reaches a first accumulated threshold, if not, determining the temperature set value change amount according to the ratio between the drying amount difference and the load steam ratio coefficient.

S33: the temperature set point is changed according to the temperature set point change amount.

It is understood that the PVC production and the drying of the PVC material are synchronously carried out in the process of drying the PVC material; that is, the PVC material produced and molded is directly transferred to the drying equipment for drying, and thus, the actual drying amount of the PVC material to be dried depends on the production speed of the PVC material. However, it is clear that the production rate of the PVC material is not completely constant, but is subject to rapid and slow fluctuation. Correspondingly, the drying amount of the PVC material to be dried also varies. The more the PVC material is dried, the more heat is required to be absorbed, and accordingly, the drying temperature set value should be properly increased, whereas when the PVC material is dried in a smaller amount, the less heat is required to be absorbed, and the drying temperature set value can be properly reduced.

In addition, the drying amount of the PVC material referred to in this embodiment may refer to the mass of the PVC material newly input into the drying apparatus per unit time. Of course, the measurement of the dry weight of the PVC material from other dimensions is not excluded in this example. In practical application, the drying quantity of the PVC material input into the drying equipment can be monitored in real time, so that the fluctuation condition of the drying quantity is determined.

In addition, if the drying amount of the PVC material only fluctuates in a small range, the temperature setting value is not enough to be adjusted, for this purpose, the difference between the current drying amount and the previous drying amount needs to be compared with the drying amount threshold, and only if the difference between the current drying amount and the previous drying amount is greater than the drying amount threshold, the temperature setting value needs to be adjusted.

Further, considering that if the fluctuation of the drying amount of the PVC material is frequent, the corresponding frequent adjustment of the temperature setting value obviously affects the stability of the whole drying environment to a certain extent, which is easy to cause the problem of large fluctuation range of the final moisture content of the PVC material. Therefore, in the process of determining whether to adjust the temperature set value, it is further determined whether the accumulated change amount of the accumulated change of the temperature set value is too large in a period of time before the current time, if yes, the current temperature set value is not changed any more, otherwise, the temperature set value is changed.

In addition, the change in the temperature setting value is not merely a change in the drying amount of the PVC material. In another alternative embodiment of the present application, it may further include:

s41: and respectively carrying out difference absolute value operation between the moisture content and the moisture set value and between the drying temperature and the temperature set value to obtain the moisture deviation value and the temperature deviation value.

S42: and when the moisture deviation is greater than the first moisture deviation threshold and the accumulated change of the temperature set value in the first preset time period before the current moment is less than the second accumulated threshold, taking the second accumulated threshold as the temperature set value change.

S43: and when the moisture deviation is smaller than the second moisture deviation threshold, if the temperature deviation value is larger than the first temperature deviation threshold and the accumulated change of the temperature set value in the first preset time period before the current moment is smaller than the third accumulated threshold, taking the third accumulated threshold as the temperature set value change.

S44: and when the moisture deviation is smaller than the second moisture deviation threshold, if the temperature deviation value is smaller than the first temperature deviation threshold and larger than the second temperature deviation threshold and the accumulated change of the temperature set value in the first preset time period before the current moment is smaller than the third accumulated threshold, taking the drying temperature at the current moment as a new temperature set value.

S45: when the water deviation is larger than the second water deviation threshold and smaller than the first water deviation threshold in the second preset time period before the current moment and the temperature deviation value is larger than the second temperature deviation threshold, if the water content is larger than the water setting value, the drying temperature is larger than the temperature setting value, and the accumulated change of the temperature setting value in the first preset time period before the current moment is smaller than the third accumulated threshold, the size of the third accumulated threshold is taken as the size of the change of the temperature setting value, and the value is a negative value.

S46: when the moisture deviation is larger than the second moisture deviation threshold and smaller than the first moisture deviation threshold in the second preset time period before the current moment and the temperature deviation value is larger than the second temperature deviation threshold, if the moisture content is larger than the moisture set value and the drying temperature is larger than the temperature set value and the accumulated change of the temperature set value in the first preset time period before the current moment is smaller than the third accumulated threshold, the size of the third accumulated threshold is taken as the size of the change of the temperature set value and the value is a positive value.

S47: the temperature set point is changed according to the change amount of the temperature set point.

Referring to FIG. 4, FIG. 4 is a schematic illustration of the present application The embodiment provides a flow chart for determining the variation of the temperature set point. In practical applications, the amount of change in the temperature set point may be determined according to the flow shown in fig. 4. In the embodiment shown in figure 4 of the drawings,and k is a load steam ratio coefficient, which is the difference between the current drying amount and the last drying amount. />Represents the difference between the measured moisture content at the current time and the target moisture content, A1 represents a first moisture deviation threshold, A2 represents a second moisture deviation threshold, and A1>A2；/>Representing the difference between the measured drying temperature value and the temperature set value at the current moment; />Indicating a first temperature deviation threshold,/>Represents a second temperature deviation threshold and +.>；Indicating the amount of change in the temperature set point,/-, for example>Indicating the accumulated variation of the temperature set point; t1 is a first accumulation threshold, T2 is a second accumulation threshold, T3 is a third accumulation threshold, and T1>T2>T3；/>For a first preset period of time before the current moment, -/-, a first preset period of time before the current moment>Is the first one before the current timeTwo preset time periods.

Based on the embodiment shown in fig. 4, in this embodiment, the amount of change in the temperature set point is determined based on the change in the moisture content and the difference between the drying temperature and the temperature set point at the current time.

For the difference between the measured moisture content at the current time and the target moisture content valueIn this example, A1, < > is set to the size of (A)>Two water contents deviate from the threshold.

When (when)At this time, it is indicated that the water content in the PVC material is relatively close to the set value of the water content, so that it can be seen that the drying temperature at the current time of drying the PVC material is relatively suitable, and thus at +.>In other words, the difference between the current drying temperature and the temperature set value is relatively large, and the current drying temperature can be directly used as a new temperature set value; while->If the current drying temperature is directly used as the temperature set value, the drying temperature may be suddenly changed, which is unfavorable for maintaining the stability of the drying state, so that the second temperature deviation threshold is used as the variation of the temperature set value, and if->Then->And->Then->On the basis of ensuring that the moisture content of the PVC material after drying can be more approximate to the ideal moisture content, the excessive fluctuation of the drying temperature is avoided.

While whenWhen the PVC material is dried, the moisture content of the PVC material has a certain deviation relative to a moisture set value, but the deviation is relatively small. In this case, it is necessary to further determine the deviation between the drying temperature at the present moment and the temperature set point, if at this point +. >Is smaller than the first temperature deviation threshold +.>It is explained that the difference between the drying temperature at the present moment and the temperature set point is relatively small, if it is the first preset time period before the present momentIn that the temperature set point is not greatly adjusted, namely the accumulated change of the temperature set pointAt this time, the amount of change in the temperature setting value may be directly set to the third cumulative threshold value T3; on the contrary, if it isThe first preset time period before the current time indicates that the temperature set value is frequently adjusted, and at this time, the temperature set value may not be adjusted temporarily, that is, the change amount of the temperature set value is 0.

While whenIn the case of->The deviation between the drying temperature and the temperature set value at the current moment is relatively large; at this time, if it is the second preset period before the current time +.>Inner part (S)>And is also provided withOr +.>And->Setting the change amount of the temperature setting value to be the third cumulative threshold value T3 and +.>Then->And->Then->. That is, the moisture content in the PVC material is higher than the moisture set value and the drying temperature is lower than the temperature set value, or the moisture content is lower than the moisture set value and the drying temperature is higher than the temperature set value, the size of the temperature set value is adjusted, otherwise, the variation of the temperature set value is 0; of course, the precondition for the adjustment of the temperature set point still requires +. >Inner part (S)>。

When (when)In this case, it is stated that the deviation between the moisture content and the moisture setpoint is relatively large, no matter +.>The value is only +.>Inner part (S)>Then T2 is taken as the amount of change in the temperature set point. It will be appreciated that at this pointThen->And->Then->。

It can be understood that, in practical application, the adjustment of the temperature setting value according to the change of the drying amount of the PVC material and the adjustment of the temperature setting value according to the deviation between the moisture content of the PVC material and the moisture setting value can be performed independently and in parallel, and the judgment is not necessarily performed according to the sequence shown in fig. 4, but the judgment is performed in any way, but the change of the temperature setting value should not be excessively large in a period of time before the current moment, so as to ensure the stability of the drying environment.

Referring to fig. 5, fig. 5 is a schematic diagram showing fluctuation of the moisture content of the PVC material according to the embodiment of the present application, wherein the abscissa in fig. 5 is the detection time, the ordinate is the moisture content percentage, and the middle horizontal line is the target moisture content percentage. As is evident from fig. 5, the adjustment of the valve position of the steam control valve in the manner provided by the application ensures that the moisture content of the PVC material fluctuates within a small range.

The following describes the device for controlling moisture of dry PVC according to the embodiment of the present invention, and the device for controlling moisture of dry PVC described below and the method for controlling moisture of dry PVC described above may be referred to correspondingly.

FIG. 6 is a block diagram of a control device for drying PVC water according to an embodiment of the present invention, and the control device for drying PVC water according to FIG. 6 is applied to a drying apparatus for drying PVC materials, wherein the drying apparatus is used for heating an air flow by using high-temperature steam and heating the PVC materials by using the heated air flow; the control device for the moisture content of the dry PVC can comprise:

the data acquisition module 100 is used for acquiring the steam pressure of the high-temperature steam, the drying temperature of the dried PVC material and the moisture content of the dried PVC material;

a first operation module 200 for determining a first adjustment amount of the output steam control valve according to the variation of the steam pressure;

the second operation module 300 is configured to perform PID feedback adjustment operation on the drying temperature and the temperature set value, and determine a second adjustment amount of the steam control valve;

a third operation module 400, configured to determine a third adjustment amount of the steam control valve according to the moisture content and the moisture set value;

The valve position regulating module 500 is configured to determine a valve position regulating amount of the steam control valve according to the first regulating amount, the second regulating amount and the third regulating amount, and control and regulate the steam control valve according to the valve position regulating amount.

In an alternative embodiment of the present application, the first operation module 200 is specifically configured to take, as the first adjustment amount, a product of a difference between the current steam pressure and the previous steam pressure and a steam pressure compensation coefficient.

In an alternative embodiment of the present application, the third operation module 400 is specifically configured to perform a difference operation on the moisture content and the moisture set value to determine a moisture deviation value; determining a temperature change trend according to the drying temperature; when the moisture deviation value and the temperature change trend meet a first condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a first preset regulating quantity; the first condition is that the moisture deviation value is a positive value with a magnitude larger than a first deviation threshold value and the temperature change trend is reduced; when the moisture deviation value and the temperature change trend meet a second condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a second preset regulating quantity; the second condition is that the moisture deviation value is a positive value with a magnitude smaller than the first deviation threshold and larger than a second deviation threshold, and the temperature change trend is declining; when the moisture deviation value and the temperature change trend meet a third condition, the value of the third regulating quantity is a negative value and the magnitude of the third regulating quantity is a second preset regulating quantity; the third condition is that the moisture deviation value is a negative value with a magnitude smaller than the first deviation threshold value and larger than a second deviation threshold value, and the temperature change trend is rising; when the moisture deviation value and the temperature change trend meet a fourth condition, the value of the third regulating quantity is a negative value and the value of the third regulating quantity is a first preset regulating quantity; wherein the fourth condition is that the moisture deviation value is a negative value larger than a first deviation threshold value and the temperature change trend is rising; when the moisture deviation value and the temperature variation trend do not satisfy any one of the first condition, the second condition, the third condition, and the fourth condition, the third adjustment amount is 0.

In an alternative embodiment of the present application, valve position adjustment module 500 is further configured to take the valve position adjustment threshold value as the valve position adjustment value when the valve position adjustment value is greater than the adjustment value threshold value; and when the accumulated valve position adjustment quantity of the steam control valve in a preset time period before the current moment is larger than a valve position adjustment threshold value, the valve position adjustment quantity is 0.

In an optional embodiment of the application, the device further comprises a fourth operation module, configured to determine a step adjustment amount according to a ratio between a set value difference between the current temperature set value and the temperature set value before being changed and a set proportionality coefficient after the temperature set value is changed according to an adjustment instruction; if the step adjustment amount is larger than the first adjustment threshold value and smaller than the second adjustment threshold value, taking the step adjustment amount as a fourth adjustment amount; if the step adjustment amount is smaller than a first adjustment threshold, taking the first adjustment threshold as the fourth adjustment amount; if the step adjustment amount is larger than a second adjustment threshold, taking the second adjustment threshold as the fourth adjustment amount; wherein, the positive and negative of the fourth regulating variable are the same as the positive and negative of the set value difference value;

The valve position adjusting module 500 is configured to take the sum of the first adjustment amount, the second adjustment amount, the third adjustment amount, and the fourth adjustment amount as the valve position adjustment amount.

In an optional embodiment of the present application, the system further includes a first change operation module, configured to collect a drying amount of the PVC material; if the absolute value of the difference between the current time drying amount and the last time drying amount of the PVC material is larger than a drying amount threshold, judging whether the accumulated change amount of the temperature set value in a first preset time period before the current time reaches a first accumulated threshold, if not, determining the change amount of the temperature set value according to the ratio between the difference of the drying amount and a load steam ratio coefficient; and changing the temperature set value according to the temperature set value change amount.

In an optional embodiment of the application, the device further comprises a second change operation module, which is used for respectively carrying out difference absolute value operation between the moisture content and the moisture set value and between the drying temperature and the temperature set value to obtain a moisture deviation amount and a temperature deviation value; when the moisture deviation is larger than a first moisture deviation threshold value and the accumulated change of the temperature set value in a first preset time period before the current moment is smaller than a second accumulated threshold value, the second accumulated threshold value is used as the temperature set value change; when the moisture deviation is smaller than a second moisture deviation threshold, if the temperature deviation value is larger than a first temperature deviation threshold and the accumulated change of the temperature set value in a first preset time period before the current moment is smaller than a third accumulated threshold, the third accumulated threshold is used as the temperature set value change; when the moisture deviation is smaller than a second moisture deviation threshold, if the temperature deviation value is smaller than the first temperature deviation threshold and larger than the second temperature deviation threshold, and the accumulated change of the temperature set value in a first preset time period before the current moment is smaller than a third accumulated threshold, taking the drying temperature at the current moment as a new temperature set value; when the moisture deviation is larger than a second moisture deviation threshold value and smaller than the first moisture deviation threshold value in a second preset time period before the current moment and the temperature deviation value is larger than a second temperature deviation threshold value, if the moisture content is larger than the moisture set value, the drying temperature is larger than the temperature set value, and the accumulated change amount of the temperature set value in the first preset time period before the current moment is smaller than a third accumulated threshold value, the magnitude of the third accumulated threshold value is taken as the magnitude of the temperature set value change amount, and the value is a negative value; when the moisture deviation is larger than a second moisture deviation threshold value and smaller than the first moisture deviation threshold value in a second preset time period before the current moment and the temperature deviation value is larger than a second temperature deviation threshold value, if the moisture content is larger than the moisture set value, the drying temperature is larger than the temperature set value, and the accumulated change amount of the temperature set value in the first preset time period before the current moment is smaller than a third accumulated threshold value, the third accumulated threshold value is used as the change amount of the temperature set value, and the value is a positive value; and changing the temperature set value according to the change amount of the temperature set value.

The control device for the moisture content of the dry PVC in this embodiment is used to implement the foregoing control method for the moisture content of the dry PVC, so that the specific implementation of the control device for the moisture content of the dry PVC can be found in the foregoing example portion of the control method for the moisture content of the dry PVC, which is not described herein again.

The application also discloses an embodiment of a control device for the moisture of the dry PVC, which comprises:

a memory for storing a computer program;

The memory may be Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

The application also discloses a computer readable storage medium, wherein the computer readable storage medium stores a computer program which realizes the steps of the control method for drying PVC water content according to any one of the above when being executed by a processor.

It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is inherent to. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. In addition, the parts of the above technical solutions provided in the embodiments of the present application, which are consistent with the implementation principles of the corresponding technical solutions in the prior art, are not described in detail, so that redundant descriptions are avoided.

The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims

1. The control method for drying the PVC water is characterized by being applied to drying equipment for drying PVC materials, wherein the drying equipment is used for heating air flow by utilizing high-temperature steam and heating the PVC materials by utilizing the heated air flow; the control method comprises the following steps:

Determining valve position adjustment quantity of the steam control valve according to the first adjustment quantity, the second adjustment quantity and the third adjustment quantity, and controlling and adjusting the steam control valve according to the valve position adjustment quantity;

determining a first adjustment amount of the output steam control valve based on the change in steam pressure, comprising:

taking the product of the difference value between the current steam pressure and the last steam pressure and the steam pressure compensation coefficient as the first regulating quantity;

determining a third adjustment amount of the steam control valve based on the moisture content and the moisture setpoint, comprising:

2. The method of controlling moisture in dry PVC according to claim 1, further comprising, after determining the valve position adjustment:

3. The method for controlling moisture in dry PVC according to claim 1, further comprising:

4. A method of controlling moisture in dry PVC according to any one of claims 1 to 3, further comprising:

collecting the drying amount of the PVC material;

and changing the temperature set value according to the temperature set value change amount.

5. A method of controlling moisture in dry PVC according to any one of claims 1 to 3, further comprising:

6. The control device for drying the PVC water is characterized by being applied to drying equipment for drying PVC materials, wherein the drying equipment is used for heating air flow by utilizing high-temperature steam and heating the PVC materials by utilizing the heated air flow; the control device includes:

the valve position regulating and controlling module is used for determining the valve position regulating quantity of the steam control valve according to the first regulating quantity, the second regulating quantity and the third regulating quantity and controlling and regulating the steam control valve according to the valve position regulating quantity;

the first operation module is specifically configured to take a product of a difference between the current steam pressure and the previous steam pressure and a steam pressure compensation coefficient as the first adjustment amount;

the third operation module is specifically configured to perform a difference operation on the moisture content and the moisture set value, and determine a moisture deviation value; determining a temperature change trend according to the drying temperature; when the moisture deviation value and the temperature change trend meet a first condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a first preset regulating quantity; the first condition is that the moisture deviation value is a positive value with a magnitude larger than a first deviation threshold value and the temperature change trend is reduced; when the moisture deviation value and the temperature change trend meet a second condition, the value of the third regulating quantity is a positive value and the value of the third regulating quantity is a second preset regulating quantity; the second condition is that the moisture deviation value is a positive value with a magnitude smaller than the first deviation threshold and larger than a second deviation threshold, and the temperature change trend is declining; when the moisture deviation value and the temperature change trend meet a third condition, the value of the third regulating quantity is a negative value and the magnitude of the third regulating quantity is a second preset regulating quantity; the third condition is that the moisture deviation value is a negative value with a magnitude smaller than the first deviation threshold value and larger than a second deviation threshold value, and the temperature change trend is rising; when the moisture deviation value and the temperature change trend meet a fourth condition, the value of the third regulating quantity is a negative value and the value of the third regulating quantity is a first preset regulating quantity; wherein the fourth condition is that the moisture deviation value is a negative value larger than a first deviation threshold value and the temperature change trend is rising; when the moisture deviation value and the temperature variation trend do not satisfy any one of the first condition, the second condition, the third condition, and the fourth condition, the third adjustment amount is 0.

7. A control device for drying PVC moisture, comprising:

a memory for storing a computer program;

a processor for carrying out the steps of the method for controlling moisture in dry PVC according to any one of claims 1 to 5 when executing said computer program.

8. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method for controlling moisture in dry PVC according to any one of claims 1 to 5.