阅读说明：本技术 一种可降解塑料的制备系统 (Preparation system of degradable plastics ) 是由 何亮 温建强 符嘉欣 于 2021-09-09 设计创作，主要内容包括：本发明涉及可降解塑料制备技术领域,尤其涉及一种可降解塑料的制备系统,包括粉体制备单元、粉体应力消除单元、混合粉体制备单元、保护剂制备单元、物料混合单元、造粒单元和中控单元。本发明通过在对生物质粉体进行二次粉碎时根据生物质粉体的实际未过筛比例将粉碎扇叶的粉碎转速调节至对应值,能够有效地将制得的将生物质粉体的平均目数粉碎至预设区间,同时,根据评级结果对制备可降解塑料的后续工艺中的参数进行对应的调节,能够有效保证不同级别的生物质粉体在作为原料制备可降解塑料时均能够与各原料进行有效的混合,从而有效提高了本发明所述系统针对可降解塑料的制备效率。(The invention relates to the technical field of degradable plastic preparation, in particular to a preparation system of degradable plastic, which comprises a powder preparation unit, a powder stress relief unit, a mixed powder preparation unit, a protective agent preparation unit, a material mixing unit, a granulation unit and a central control unit. According to the invention, when the biomass powder is subjected to secondary crushing, the crushing rotating speed of the crushing fan blades is adjusted to a corresponding value according to the actual unscreened proportion of the biomass powder, so that the prepared biomass powder can be effectively crushed to a preset interval, and meanwhile, parameters in the subsequent process for preparing the degradable plastics are correspondingly adjusted according to the rating result, so that the biomass powder of different grades can be effectively mixed with all raw materials when being used as the raw materials for preparing the degradable plastics, and the preparation efficiency of the system for the degradable plastics is effectively improved.)

1. A system for preparing degradable plastics, which is characterized by comprising:

the powder preparation unit is used for preparing biomass powder and comprises a plant raw material storage tank for storing plants, a crushing mechanism arranged at the output end of the plant raw material storage tank and used for crushing the plants, a screen arranged at the output end of the crushing mechanism and used for screening crushed biomass powder, and a powder bearing bin arranged at the output end of the screen and used for loading the screened biomass powder; the plant crushing mechanism is internally provided with crushing fan blades; the screen is provided with a quality detector for detecting the quality of the unscreened powder;

the powder stress relieving unit is connected with the powder bearing bin and used for receiving and compacting the biomass powder output by the powder bearing bin so as to relieve the internal stress of the biomass powder, and a pressure detector is arranged in the powder stress relieving unit and used for detecting the pressure applied to the biomass powder by the powder stress relieving unit;

the mixed powder preparation unit is connected with the powder stress relief unit, and a modified raw material storage tank group is arranged at the top of the mixed powder preparation unit; when the mixed powder preparation unit is operated, the mixed powder preparation unit respectively receives the biomass powder output by the powder stress relief unit and the modified raw materials output by the modified raw material storage tanks in the modified raw material storage tank group and stirs the biomass powder and the modified raw materials to prepare mixed powder;

the protective agent preparation unit is used for preparing a protective agent;

the material mixing unit is respectively connected with the mixed powder preparation unit and the protective agent preparation unit, and is also connected with the starch storage tank; when the material mixing unit operates, the material mixing unit respectively receives the mixed powder output by the mixed powder preparation unit, the protective agent output by the protective agent preparation unit and the starch output by the starch storage tank and stirs the mixed powder, the protective agent and the starch to prepare a mixed material; a viscosity detector is arranged in the material mixing unit and used for detecting the viscosity of the mixed material in real time when the mixed material is prepared by the material mixing unit;

the granulating unit is connected with the material mixing unit and used for receiving the mixed material output by the material mixing unit, mixing the mixed material and preparing the mixed material into degradable plastic master batches;

and the central control unit is respectively connected with each unit, the components in each unit and each storage tank, and is used for adjusting the crushing rotating speed of the crushing fan blades in the crushing mechanism to a corresponding value according to the mass of the biomass powder which is not sieved when the system runs and grading the biomass powder prepared by the crushing mechanism when the mass of the biomass powder which is not sieved reaches the standard, and when the central control unit finishes grading the biomass powder, the central control unit adjusts the pressure of the powder stress eliminating unit on the biomass powder according to the grading result.

2. The system for preparing degradable plastics according to claim 1, wherein when the powder preparation unit prepares the biomass powder, the central control unit controls the plant material storage tank to convey a plant with a preset mass M to the crushing mechanism and controls the crushing fan blades to rotate at a preset crushing rotation speed V to crush the plant output from the plant material storage tank, after crushing, the crushing mechanism conveys the biomass powder to the powder bearing bin through a screen with a first preset mesh number r1, after sieving, the central control unit controls the mass detector to detect the mass of the biomass powder which is not sieved on the screen, calculates the ratio B of the mass of the residual biomass powder to the mass of the plant output from the plant material storage tank, and compares B with a preset mass ratio B0; if B is less than B0, the central control unit judges that the particle size of the biomass powder meets the standard and evaluates the biomass powder as first-grade biomass powder with high mesh number, and after the judgment is finished, the central control unit conveys the sieved biomass powder to the split stress eliminating unit; if B is larger than or equal to B0, the central control unit controls the screen to convey the remaining biomass powder to the crushing mechanism through the feed back channel, calculates the difference value delta B between B and B0, and adjusts the rotating speed of the crushing fan blades to a corresponding value according to the delta B so that the crushing mechanism performs secondary crushing on the remaining biomass powder, and the delta B is set to be B-B0;

the central control unit is provided with a first preset mass difference value delta B1, a second preset mass difference value delta B2, a first preset crushing rotating speed regulating coefficient alpha 1 and a second preset crushing rotating speed regulating coefficient alpha 2; wherein, the delta B1 is less than delta B2, 1 is more than alpha 1 and more than alpha 2 and more than 1.3;

when the delta B is not more than the delta B1, the central control unit does not adjust the crushing rotating speed of the crushing fan blades when the crushing mechanism performs secondary crushing on the residual biomass powder;

when the delta B1 is less than the delta B and less than or equal to the delta B2, the central control unit adjusts the crushing rotating speed of the crushing fan blades by using alpha 1 when the crushing mechanism performs secondary crushing on the residual biomass powder;

when delta B is > [ delta B ] 2, the central control unit adjusts the crushing rotating speed of the crushing fan blades by using alpha 2 when the crushing mechanism performs secondary crushing on the residual biomass powder;

when the central control unit adjusts the crushing rotation speed of the crushing fan blades by using the α i, i is set to be 1, 2, and the adjusted crushing rotation speed of the crushing fan blades is set to be V ', V' is set to be V × α i.

3. The system for preparing degradable plastics according to claim 2, wherein a preset critical crushing rotation speed Vmax is set in the central control unit, and when the central control unit determines that the crushing rotation speed of the crushing fan blades needs to be adjusted to V ', the central control unit compares V' with Vmax;

if V '< Vmax, the central control unit regulates the crushing rotating speed of the crushing fan blade to V', recalculates the ratio of the mass of the residual biomass powder on the screen to the mass of the plants output by the plant raw material storage tank after the crushing mechanism finishes crushing the residual biomass powder, and readjusts the crushing rotating speed of the crushing fan blade according to the difference value of the mass of the residual biomass powder and the mass of the plants output by the plant raw material storage tank when the ratio is greater than or equal to B0 so as to crush the residual biomass powder again until the ratio of the mass of the residual biomass powder on the screen to the mass of the plants output by the plant raw material storage tank after crushing is less than B0;

if V 'is more than Vmax, the central control unit sets the crushing rotating speed of the crushing fan blades to Vmax, recalculates the ratio B' of the mass of the residual biomass powder on the screen to the mass of the plants output by the plant raw material storage tank after the crushing mechanism finishes crushing the residual biomass powder, and ranks the biomass powder according to the ratio.

4. The system for preparing degradable plastics according to claim 3, wherein when said central control unit compares B 'with B0 to grade biomass powder, if B' is less than or equal to B0, said central control unit determines that the biomass powder is high-count biomass powder; if B ' > B0, the central control unit calculates the mass difference Delta B ' and grades the powder according to Delta B ', and sets Delta B ' ═ B ' -B0;

if the delta B' is less than or equal to the delta B1, the central control unit evaluates that the biomass powder is first-grade biomass powder with high mesh number;

if the delta B is more than delta B1 and is not more than delta B2, the central control unit controls the powder preparation unit to replace a screen with a second preset mesh number r2 to screen the crushed residual biomass powder, wherein r2 is more than 80 and r1 is more than 120; if the ratio B' of the mass of the remaining biomass powder after screening to the total mass of the plants is less than or equal to B0, the central control unit evaluates that the biomass powder is secondary biomass powder with a medium mesh number;

if B 'is greater than B0, the central control unit calculates delta B' and judges the biomass powder according to the delta B ', and sets the delta B' -B0; if the delta B is less than or equal to the delta B1, the central control unit evaluates that the biomass powder is secondary biomass powder with a medium mesh; if delta B' > [ delta B ] 1, the central control unit evaluates that the biomass powder is the three-level biomass powder with low mesh number;

if delta B' > [ delta B ] 2, the central control unit evaluates that the biomass powder is the three-level biomass powder with low mesh number.

5. The system for preparing degradable plastics according to claim 4, wherein when said central control unit finishes grading the mesh number of the biomass powder, the central control unit controls said plant material storage tank to deliver a corresponding amount of plants to said pulverizing mechanism and controls said pulverizing fan blades to pulverize the plants output from the plant material storage tank at the adjusted pulverizing speed, and during the pulverizing process, the central control unit detects the mass Ma of the biomass powder in said powder bearing bin in real time until Ma reaches the preset mass Ma0, and Ma0 is set as M x (1-B0); when Ma0, the central control unit controls the powder bearing bin to convey the sieved biomass powder to the powder stress relieving unit.

6. The system for preparing degradable plastics according to claim 4, wherein when said central control unit finishes ranking the mesh number of the biomass powder and delivers the biomass powder to said powder stress relief unit, the central control unit determines the pressure applied to the biomass powder by the powder stress relief unit according to the mass Ma of the biomass powder delivered to the powder stress relief unit and sets the pressure applied to the biomass powder by the powder stress relief unit to a corresponding value according to the level of the biomass powder and adjusts the applied pressure to the corresponding value according to the level of the biomass powder;

the central control unit is internally provided with a first preset plant mass M1, a second preset plant mass M2, a first preset pressure F1, a second preset pressure F2, a third preset pressure F3, a first preset pressure regulating coefficient beta 1 and a second preset pressure regulating coefficient beta 2, wherein M1 is more than M2, F1 is more than F2 and more than F3, and 1 is more than beta 1 and more than beta 2 and less than 1.5;

if Ma is less than or equal to M1, the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit to be F1;

if M1 is more than Ma and less than or equal to M2, the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit to be F2;

ma is larger than M2, and the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit to be F3;

when the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relieving unit to be Fj, setting j to be 1, 2, 3, and adjusting the Fj according to the grade of the biomass powder;

if the biomass powder is primary biomass powder, the central control unit does not adjust Fj;

if the biomass powder is secondary biomass powder, the central control unit adjusts Fj by using beta 1;

if the biomass powder is three-level biomass powder, the central control unit adjusts Fj by using beta 2;

when the central control unit uses β k to adjust Fj, k is set to 1, 2, and the adjusted pressure is denoted as Fj ', and Fj' is set to Fj × β k.

7. The system for preparing degradable plastics according to claim 6, wherein when the material mixing unit mixes the material and the mixing unit stirs the material for a preset time t at an initial stirring rotation speed W, the central control unit controls the viscosity detector to detect the viscosity E of the material and adds the corresponding kind of raw material when the viscosity of the material is judged not to meet the standard; a preset viscosity interval E0(Emin, Emax) is arranged in the central control unit, wherein Emin is the preset lowest viscosity, and Emax is the preset highest viscosity;

if E belongs to E0, the central control unit judges that the viscosity of the material meets the standard;

if it isThe central control unit judges that the viscosity of the material does not meet the standard;

when in useIf E is less than Emin, the central control unit calculates the viscosity difference delta E and adjusts the initial stirring speed of the mixing unit or adds starch and mixed powder according to the delta E: the central control unit is internally provided with a first preset viscosity difference delta E1, a second preset viscosity difference delta E2, a first preset stirring rotating speed adjusting coefficient gamma 1 and a second preset stirring rotating speed adjusting coefficient gamma 2, wherein delta E1 is less than delta E2, and gamma 1 is more than 0.8 and less than gamma 2 and less than 1;

if the delta E is less than or equal to the delta E1, the central control unit increases the stirring rotating speed of the stirring unit by using gamma 2;

if delta E1 is less than delta E and less than delta E2, the central control unit increases the stirring rotating speed of the stirring unit by using gamma 1;

if delta E > -delta E2, the central control unit increases the stirring speed of the stirring unit by using gamma 1 and adds biomass powder with Qa quality and starch with Qb quality into the stirring unit, wherein Qa + Qb is 0.1 XQ 0, and Q0 is the total mass of the materials in the material mixing unit;

when the central control unit increases the stirring rotation speed of the stirring unit by using the gamma x, setting x to be 1, 2, and setting the increased stirring rotation speed to be W ', and setting W' to be W x (2-gamma x);

if E is more than Emin, the central control unit calculates the viscosity difference delta E 'and adjusts the initial stirring speed of the mixing unit or adds a protective agent according to the delta E':

if the delta E' is less than or equal to the delta E1, the central control unit reduces the stirring rotating speed of the stirring unit by using gamma 2;

if the delta E1 is less than the delta E' and less than the delta E2, the central control unit reduces the stirring rotation speed of the stirring unit by using gamma 1;

if delta E' > [ delta E2 ], the central control unit reduces the stirring speed of the stirring unit by using gamma 1 and adds a protective agent with the quality of Qc into the stirring unit, wherein the Qc is 0.15 multiplied by Q0;

when the central control unit reduces the stirring rotation speed of the stirring unit by using γ x, the reduced stirring rotation speed is denoted as W ", and W ═ W × γ x is set.

8. The system for preparing degradable plastics according to claim 7, wherein a first preset mixed powder addition amount adjusting coefficient e1 and a second preset mixed powder addition amount adjusting coefficient e2 are further provided in the central control unit, 1 < e1 < e2 < 1.4;

when the central control unit judges that mixed powder with the quality of Qa needs to be added into the mixed material mixing unit, the central control unit judges whether the Qa needs to be adjusted according to the grade of biomass powder in the mixed powder;

if the biomass powder is primary biomass powder, the central control unit judges that the Qa is not required to be adjusted;

if the biomass powder is secondary biomass powder, the central control unit judges that the Qa needs to be adjusted and adjusts the Qa by using e 1;

if the biomass powder is three-level biomass powder, the central control unit judges that the Qa needs to be adjusted and adjusts the Qa by using e 2;

when the central control unit uses ey to adjust Qa, y is set to 1, 2, and the amount of the mixed powder added after adjustment is set to Qa ', Qa' is set to Qa × ey.

9. The system for preparing degradable plastics according to claim 8, wherein a preset critical addition amount Qamax of mixed powder, a preset critical addition amount Qbmax of starch and a preset critical addition amount Qcmax of protective agent are further provided in the central control unit;

when the central control unit controls the starch storage tank to add starch into the materials in the material mixing unit, the central control unit records the total mass Qb0 of the added mixed powder, if Qb0 is greater than Qbmax, the central control unit does not control the starch storage tank to add starch into the materials in the material mixing unit and only controls the mixed powder preparation unit to add the mixed powder into the materials in the material mixing unit in the subsequent adding process;

when the central control unit controls the mixed powder preparation unit to add the mixed powder into the materials in the material mixing unit, the central control unit records the total mass Qa0 of the added mixed powder, if Qa0 is larger than Qamax, the central control unit does not control the mixed powder preparation unit to add the mixed powder into the materials in the material mixing unit, and only adjusts the stirring speed in the material mixing unit;

when the central control unit controls the protective agent preparation unit to add the protective agent into the materials in the material mixing unit, the central control unit records the total mass Qc0 of the added protective agent, if Qc0 is larger than Qcmax, the central control unit does not control the protective agent preparation unit to add the protective agent into the materials in the material mixing unit, and only adjusts the stirring speed in the material mixing unit.

Technical Field

The invention relates to the technical field of degradable plastic preparation, in particular to a preparation system of degradable plastic.

Background

The plastic product has the characteristics of light weight, durability, safety, low cost and the like, and is widely applied to the fields of packaging, daily use, buildings and the like. While bringing convenience to people, the disadvantages of plastic products are gradually recognized, most of the currently commonly used petroleum-based polyolefins (polyethylene PE, polypropylene PP, polyvinyl chloride PVC, etc.) cannot be recycled, and the degradation time under natural conditions is very long, so that a large amount of garbage is generated, and a quite serious 'white pollution' is caused.

The biodegradable plastic refers to plastic which is degraded under natural conditions under the action of certain microorganisms in the nature, such as bacteria, fungi and algae, and comprises three major types, namely microbial synthetic biodegradable plastic (such as polyhydroxyalkanoates PHA and polyhydroxybutyrate PHB), chemical synthetic biodegradable plastic (such as polylactic acid PLA, polybutylene adipate-terephthalate PBAT, polybutylene succinate PBS, polycaprolactone PCL and the like) and natural biodegradable plastic (starch, cellulose and the like). The price of the current synthetic biodegradable plastics is generally higher, and even the polylactic acid which is industrially produced is almost twice as high as that of the common petroleum-based polyethylene, so that the application range of the synthetic biodegradable plastics is greatly limited.

The composite processing of natural materials such as starch, lignin and cellulose with relatively low price and degradable plastics such as PLA, PBAT and the like is an effective way for reducing the production cost of the degradable plastics. The PBAT is filled with cassava starch and corn starch, and the comprehensive mechanical property of the material is better improved when the using amount of the starch is 5-10 parts; however, when the amount of the starch exceeds 10 parts, the performance is obviously reduced (Ningping et al, research on the structure and performance of starch-filled modified PBAT, novel chemical materials, 2010.7). The crepe snow is found that when the lignin content is 5 percent in a PBAT/PES polyester matrix, the crepe snow can be uniformly dispersed in a system, and the mechanical property of the material is not obviously reduced; and when the lignin content reaches 15%, the tensile strength is greatly reduced (Zhouyanxue, preparation and performance research of lignin/PBAT/PES composite material, Master thesis of southwest science and technology university, 2016). The 3D printing material is prepared by mixing and melting starch and PLA (polylactic acid) for the Lilingyu, and the mechanical property of the composite material shows an obvious decline trend along with the increase of the proportion of the starch, when the using amount of the starch is 40%, the tensile strength is reduced by 72-74%, the impact strength is reduced by 28%, and the bending strength is reduced by 30-34% (Lilingyu, the preparation and characterization of the polylactic acid/starch composite material applied to 3D printing, chemical technology and development, 2018.7). Previous researches show that starch, lignin and the like can be only added in a small amount in degradable plastics, otherwise, the mechanical property of the composite material is reduced.

However, in the existing preparation process of cellulose-based degradable plastics, the situation that the prepared plant fiber powder has too high or too low mesh easily occurs, so that the plant fiber powder and other materials are not uniformly mixed in the subsequent preparation process of the degradable plastics, and the situation that the prepared plastics have poor practicability occurs, thereby reducing the preparation efficiency of the equipment in the prior art for the degradable plastics taking plant fibers as raw materials.

Disclosure of Invention

Therefore, the invention provides a preparation system of degradable plastics, which is used for solving the problem of low preparation efficiency of the degradable plastics caused by uneven mixing of plant fiber powder and materials in the prior art.

In order to achieve the above object, the present invention provides a system for preparing degradable plastics, comprising:

the powder preparation unit is used for preparing biomass powder and comprises a plant raw material storage tank for storing plants, a crushing mechanism arranged at the output end of the plant raw material storage tank and used for crushing the plants, a screen arranged at the output end of the crushing mechanism and used for screening crushed biomass powder, and a powder bearing bin arranged at the output end of the screen and used for loading the screened biomass powder; the plant crushing mechanism is internally provided with crushing fan blades; the screen is provided with a quality detector for detecting the quality of the unscreened powder;

the powder stress relieving unit is connected with the powder bearing bin and used for receiving and compacting the biomass powder output by the powder bearing bin so as to relieve the internal stress of the biomass powder, and a pressure detector is arranged in the powder stress relieving unit and used for detecting the pressure applied to the biomass powder by the powder stress relieving unit;

the mixed powder preparation unit is connected with the powder stress relief unit, and a modified raw material storage tank group is arranged at the top of the mixed powder preparation unit; when the mixed powder preparation unit is operated, the mixed powder preparation unit respectively receives the biomass powder output by the powder stress relief unit and the modified raw materials output by the modified raw material storage tanks in the modified raw material storage tank group and stirs the biomass powder and the modified raw materials to prepare mixed powder;

the protective agent preparation unit is used for preparing a protective agent;

the material mixing unit is respectively connected with the mixed powder preparation unit and the protective agent preparation unit, and is also connected with the starch storage tank; when the material mixing unit operates, the material mixing unit respectively receives the mixed powder output by the mixed powder preparation unit, the protective agent output by the protective agent preparation unit and the starch output by the starch storage tank and stirs the mixed powder, the protective agent and the starch to prepare a mixed material; a viscosity detector is arranged in the material mixing unit and used for detecting the viscosity of the mixed material in real time when the mixed material is prepared by the material mixing unit;

the granulating unit is connected with the material mixing unit and used for receiving the mixed material output by the material mixing unit, mixing the mixed material and preparing the mixed material into degradable plastic master batches;

and the central control unit is respectively connected with each unit, the components in each unit and each storage tank, and is used for adjusting the crushing rotating speed of the crushing fan blades in the crushing mechanism to a corresponding value according to the mass of the biomass powder which is not sieved when the system runs and grading the biomass powder prepared by the crushing mechanism when the mass of the biomass powder which is not sieved reaches the standard, and when the central control unit finishes grading the biomass powder, the central control unit adjusts the pressure of the powder stress eliminating unit on the biomass powder according to the grading result.

Further, when the powder preparation unit is used for preparing biomass powder, the central control unit controls the plant raw material storage tank to convey plants with preset mass M to the crushing mechanism and controls the crushing fan blades to rotate at a preset crushing rotating speed V so as to crush the plants output by the plant raw material storage tank, after crushing is completed, the crushing mechanism conveys the biomass powder to the powder bearing bin through a screen with a first preset mesh number r1, after sieving, the central control unit controls the mass detector to detect the mass of the biomass powder which is not sieved on the screen, calculates the ratio B of the mass of the residual biomass powder to the mass of the plants output by the plant raw material storage tank, and compares B with a preset mass ratio B0; if B is less than B0, the central control unit judges that the particle size of the biomass powder meets the standard and evaluates the biomass powder as first-grade biomass powder with high mesh number, and after the judgment is finished, the central control unit conveys the sieved biomass powder to the split stress eliminating unit; if B is larger than or equal to B0, the central control unit controls the screen to convey the remaining biomass powder to the crushing mechanism through the feed back channel, calculates the difference value delta B between B and B0, and adjusts the rotating speed of the crushing fan blades to a corresponding value according to the delta B so that the crushing mechanism performs secondary crushing on the remaining biomass powder, and the delta B is set to be B-B0;

the central control unit is provided with a first preset mass difference value delta B1, a second preset mass difference value delta B2, a first preset crushing rotating speed regulating coefficient alpha 1 and a second preset crushing rotating speed regulating coefficient alpha 2; wherein, the delta B1 is less than delta B2, 1 is more than alpha 1 and more than alpha 2 and more than 1.3;

when the delta B is not more than the delta B1, the central control unit does not adjust the crushing rotating speed of the crushing fan blades when the crushing mechanism performs secondary crushing on the residual biomass powder;

when the delta B1 is less than the delta B and less than or equal to the delta B2, the central control unit adjusts the crushing rotating speed of the crushing fan blades by using alpha 1 when the crushing mechanism performs secondary crushing on the residual biomass powder;

when delta B is > [ delta B ] 2, the central control unit adjusts the crushing rotating speed of the crushing fan blades by using alpha 2 when the crushing mechanism performs secondary crushing on the residual biomass powder;

when the central control unit adjusts the crushing rotation speed of the crushing fan blades by using the α i, i is set to be 1, 2, and the adjusted crushing rotation speed of the crushing fan blades is set to be V ', V' is set to be V × α i.

Furthermore, a preset critical crushing rotating speed Vmax is arranged in the central control unit, and when the central control unit judges that the crushing rotating speed of the crushing fan blades needs to be adjusted to V ', the central control unit compares the V' with the Vmax;

if V '< Vmax, the central control unit regulates the crushing rotating speed of the crushing fan blade to V', recalculates the ratio of the mass of the residual biomass powder on the screen to the mass of the plants output by the plant raw material storage tank after the crushing mechanism finishes crushing the residual biomass powder, and readjusts the crushing rotating speed of the crushing fan blade according to the difference value of the mass of the residual biomass powder and the mass of the plants output by the plant raw material storage tank when the ratio is greater than or equal to B0 so as to crush the residual biomass powder again until the ratio of the mass of the residual biomass powder on the screen to the mass of the plants output by the plant raw material storage tank after crushing is less than B0;

if V 'is more than Vmax, the central control unit sets the crushing rotating speed of the crushing fan blades to Vmax, recalculates the ratio B' of the mass of the residual biomass powder on the screen to the mass of the plants output by the plant raw material storage tank after the crushing mechanism finishes crushing the residual biomass powder, and ranks the biomass powder according to the ratio.

Further, when the central control unit compares B 'with B0 to grade the biomass powder, if B' is less than or equal to B0, the central control unit judges that the biomass powder is high-number biomass powder; if B ' > B0, the central control unit calculates the mass difference Delta B ' and grades the powder according to Delta B ', and sets Delta B ' ═ B ' -B0;

if the delta B' is less than or equal to the delta B1, the central control unit evaluates that the biomass powder is first-grade biomass powder with high mesh number;

if the delta B is more than delta B1 and is not more than delta B2, the central control unit controls the powder preparation unit to replace a screen with a second preset mesh number r2 to screen the crushed residual biomass powder, wherein r2 is more than 80 and r1 is more than 120; if the ratio B' of the mass of the remaining biomass powder after screening to the total mass of the plants is less than or equal to B0, the central control unit evaluates that the biomass powder is secondary biomass powder with a medium mesh number;

if B 'is greater than B0, the central control unit calculates delta B' and judges the biomass powder according to the delta B ', and sets the delta B' -B0; if the delta B is less than or equal to the delta B1, the central control unit evaluates that the biomass powder is secondary biomass powder with a medium mesh; if delta B' > [ delta B ] 1, the central control unit evaluates that the biomass powder is the three-level biomass powder with low mesh number;

if delta B' > [ delta B ] 2, the central control unit evaluates that the biomass powder is the three-level biomass powder with low mesh number.

Further, when the central control unit finishes grading the mesh number of the biomass powder, the central control unit controls the plant raw material storage tank to convey a corresponding amount of plants to the crushing mechanism and controls the crushing fan blades to crush the plants output by the plant raw material storage tank at the adjusted crushing rotating speed, and in the crushing process, the central control unit detects the mass Ma of the biomass powder in the powder bearing bin in real time until the Ma reaches the preset mass Ma0, and Ma0 is set as M x (1-B0); when Ma0, the central control unit controls the powder bearing bin to convey the sieved biomass powder to the powder stress relieving unit.

Further, when the central control unit finishes grading the mesh number of the biomass powder and conveys the biomass powder to the powder stress relieving unit, the central control unit determines the pressure applied to the biomass powder by the powder stress relieving unit according to the quality Ma of the biomass powder conveyed to the powder stress relieving unit, sets the pressure applied to the biomass powder by the powder stress relieving unit to be a corresponding value according to the grade of the biomass powder and adjusts the applied pressure to be the corresponding value according to the grade of the biomass powder;

the central control unit is internally provided with a first preset plant mass M1, a second preset plant mass M2, a first preset pressure F1, a second preset pressure F2, a third preset pressure F3, a first preset pressure regulating coefficient beta 1 and a second preset pressure regulating coefficient beta 2, wherein M1 is more than M2, F1 is more than F2 and more than F3, and 1 is more than beta 1 and more than beta 2 and less than 1.5;

if Ma is less than or equal to M1, the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit to be F1;

if M1 is more than Ma and less than or equal to M2, the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit to be F2;

ma is larger than M2, and the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit to be F3;

when the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relieving unit to be Fj, setting j to be 1, 2, 3, and adjusting the Fj according to the grade of the biomass powder;

if the biomass powder is primary biomass powder, the central control unit does not adjust Fj;

if the biomass powder is secondary biomass powder, the central control unit adjusts Fj by using beta 1;

if the biomass powder is three-level biomass powder, the central control unit adjusts Fj by using beta 2;

when the central control unit uses β k to adjust Fj, k is set to 1, 2, and the adjusted pressure is denoted as Fj ', and Fj' is set to Fj × β k.

Further, when the material mixing unit mixes the material and the mixing unit stirs the material for a preset time t at an initial stirring rotating speed W, the central control unit controls the viscosity detector to detect the viscosity E of the material and adds the corresponding type of raw material when the viscosity of the material is judged not to meet the standard; a preset viscosity interval E0(Emin, Emax) is arranged in the central control unit, wherein Emin is the preset lowest viscosity, and Emax is the preset highest viscosity;

if E belongs to E0, the central control unit judges that the viscosity of the material meets the standard;

if it isThe central control unit judges that the viscosity of the material does not meet the standard;

when in useIf E is less than Emin, the central control unit calculates the viscosity difference delta E and adjusts the initial stirring speed of the mixing unit or adds starch and mixed powder according to delta EBody: the central control unit is internally provided with a first preset viscosity difference delta E1, a second preset viscosity difference delta E2, a first preset stirring rotating speed adjusting coefficient gamma 1 and a second preset stirring rotating speed adjusting coefficient gamma 2, wherein delta E1 is less than delta E2, and gamma 1 is more than 0.8 and less than gamma 2 and less than 1;

if the delta E is less than or equal to the delta E1, the central control unit increases the stirring rotating speed of the stirring unit by using gamma 2;

if delta E1 is less than delta E and less than delta E2, the central control unit increases the stirring rotating speed of the stirring unit by using gamma 1;

if delta E > -delta E2, the central control unit increases the stirring speed of the stirring unit by using gamma 1 and adds biomass powder with Qa quality and starch with Qb quality into the stirring unit, wherein Qa + Qb is 0.1 XQ 0, and Q0 is the total mass of the materials in the material mixing unit;

when the central control unit increases the stirring rotation speed of the stirring unit by using the gamma x, setting x to be 1, 2, and setting the increased stirring rotation speed to be W ', and setting W' to be W x (2-gamma x);

if E is more than Emin, the central control unit calculates the viscosity difference delta E 'and adjusts the initial stirring speed of the mixing unit or adds a protective agent according to the delta E':

if the delta E' is less than or equal to the delta E1, the central control unit reduces the stirring rotating speed of the stirring unit by using gamma 2;

if the delta E1 is less than the delta E' and less than the delta E2, the central control unit reduces the stirring rotation speed of the stirring unit by using gamma 1;

if delta E' > [ delta E2 ], the central control unit reduces the stirring speed of the stirring unit by using gamma 1 and adds a protective agent with the quality of Qc into the stirring unit, wherein the Qc is 0.15 multiplied by Q0;

when the central control unit reduces the stirring rotation speed of the stirring unit by using γ x, the reduced stirring rotation speed is denoted as W ", and W ═ W × γ x is set.

Furthermore, a first preset mixed powder adding amount adjusting coefficient e1 and a second preset mixed powder adding amount adjusting coefficient e2 are also arranged in the central control unit, and e1 is more than 1 and e2 is more than 1.4;

when the central control unit judges that mixed powder with the quality of Qa needs to be added into the mixed material mixing unit, the central control unit judges whether the Qa needs to be adjusted according to the grade of biomass powder in the mixed powder;

if the biomass powder is primary biomass powder, the central control unit judges that the Qa is not required to be adjusted;

if the biomass powder is secondary biomass powder, the central control unit judges that the Qa needs to be adjusted and adjusts the Qa by using e 1;

if the biomass powder is three-level biomass powder, the central control unit judges that the Qa needs to be adjusted and adjusts the Qa by using e 2;

when the central control unit uses ey to adjust Qa, y is set to 1, 2, and the amount of the mixed powder added after adjustment is set to Qa ', Qa' is set to Qa × ey.

Furthermore, a preset critical adding amount Qamax of mixed powder, a preset critical adding amount Qbmax of starch and a preset critical adding amount Qcmax of a protective agent are also arranged in the central control unit;

when the central control unit controls the starch storage tank to add starch into the materials in the material mixing unit, the central control unit records the total mass Qb0 of the added mixed powder, if Qb0 is greater than Qbmax, the central control unit does not control the starch storage tank to add starch into the materials in the material mixing unit and only controls the mixed powder preparation unit to add the mixed powder into the materials in the material mixing unit in the subsequent adding process;

when the central control unit controls the mixed powder preparation unit to add the mixed powder into the materials in the material mixing unit, the central control unit records the total mass Qa0 of the added mixed powder, if Qa0 is larger than Qamax, the central control unit does not control the mixed powder preparation unit to add the mixed powder into the materials in the material mixing unit, and only adjusts the stirring speed in the material mixing unit;

when the central control unit controls the protective agent preparation unit to add the protective agent into the materials in the material mixing unit, the central control unit records the total mass Qc0 of the added protective agent, if Qc0 is larger than Qcmax, the central control unit does not control the protective agent preparation unit to add the protective agent into the materials in the material mixing unit, and only adjusts the stirring speed in the material mixing unit.

Compared with the prior art, the invention has the advantages that by arranging the central control unit in the system, when the biomass powder is prepared by the system, whether secondary crushing is needed to be carried out on the biomass powder is judged according to the sieving proportion of the prepared biomass powder, and the crushing rotating speed of the crushing fan blades is adjusted to a corresponding value according to the actual non-sieving proportion of the biomass powder during the secondary crushing, so that the prepared biomass powder can be effectively crushed to a preset interval with the average mesh number, and meanwhile, when the rotating speed of the crushing fan blades is adjusted to a critical value, the prepared biomass powder is graded, and parameters in a subsequent process for preparing the degradable plastics are correspondingly adjusted according to the grading result, so that the biomass powder with different grades can be effectively mixed with all raw materials when being used as the raw materials for preparing the degradable plastics, and the preparation efficiency of the system for preparing the degradable plastics is effectively improved.

Further, after the screening, the central control unit controls the quality detector to detect the quality of biomass powder which is not screened on the screen, calculates the ratio B of the quality of the residual biomass powder to the plant quality output by the plant raw material storage tank, and judges that B is not less than B0, the central control unit controls the screen to convey the residual biomass powder to the crushing mechanism through the feed back channel, calculates the difference value delta B between B and B0, and adjusts the rotating speed of the crushing fan blade to a corresponding value according to the delta B so that the crushing mechanism performs secondary crushing on the residual biomass powder And meanwhile, the preparation efficiency of the system aiming at the degradable plastics is further improved.

Further, when the central control unit judges that the crushing rotating speed of the crushing fan blades needs to be adjusted to V ' and V ' > Vmax, the central control unit sets the crushing rotating speed of the crushing fan blades to Vmax, recalculates the ratio B ' of the mass of the residual biomass powder on the screen and the mass of the plant output by the plant raw material storage tank after the crushing mechanism finishes crushing the residual biomass powder, and ranks the biomass powder according to the ratio.

Further, when the central control unit compares B 'with B0 to grade the biomass powder, if B' is less than or equal to B0, the central control unit judges that the biomass powder is high-number biomass powder; if B ' is more than B0, the central control unit calculates the mass difference value delta B ' and further grades the powder according to delta B ', the biomass powder prepared at this time is accurately graded according to the mass proportion of the biomass powder which is not sieved after being crushed when the crushing rotating speed of the crushing fan blade reaches a critical value, so that the biomass powder can be effectively mixed with various raw materials when being used as the raw materials to prepare the degradable plastics, and the preparation efficiency of the system for the degradable plastics is further improved.

Furthermore, when the central control unit finishes grading the mesh number of the biomass powder, the central control unit controls the plant raw material storage tank to convey a corresponding amount of plants to the crushing mechanism and controls the crushing fan blades to crush the plants output by the plant raw material storage tank at the adjusted crushing rotating speed, and during the crushing process, the central control unit detects the quality Ma of the biomass powder in the powder bearing bin in real time until the Ma reaches the preset quality Ma 0.

Further, when the central control unit finishes grading the mesh number of the biomass powder and conveys the biomass powder to the powder stress relieving unit, the central control unit determines the pressure applied to the biomass powder by the powder stress relieving unit according to the quality Ma of the biomass powder conveyed to the powder stress relieving unit, sets the pressure applied to the biomass powder by the powder stress relieving unit to a corresponding value according to the grade of the biomass powder and adjusts the applied pressure to the corresponding value according to the grade of the biomass powder, the invention can further ensure that the biomass powder can be effectively mixed with each raw material when being used as the raw material for preparing the degradable plastic by preliminarily determining the pressure applied to the biomass powder by the relieving unit according to the quality of the received biomass powder to be relieved of stress and adjusting the pressure to the corresponding value according to the specific grade of the biomass powder, the preparation efficiency of the system aiming at the degradable plastics is further improved.

Further, when the material mixing unit mixes the materials and the mixing unit stirs the materials at the initial stirring rotating speed W for a preset time t, the central control unit controls the viscosity detector to detect the viscosity E of the material and adds the corresponding type of raw material when judging that the viscosity of the material does not meet the standard, if E is less than Emin, the central control unit calculates the viscosity difference Delta E and adjusts the initial stirring rotating speed of the mixing unit or adds starch and mixed powder according to the Delta E, if E is more than Emin, the central control unit calculates the viscosity difference Delta E 'and adjusts the initial stirring rotating speed of the mixing unit or adds a protective agent according to the Delta E', the invention sets a preset viscosity interval and adds the corresponding raw material according to the actual condition when the viscosity of the material does not belong to the preset interval, and can ensure that the viscosity of the material meets the standard, the quality of the prepared degradable plastic is effectively improved, and the preparation efficiency of the system aiming at the degradable plastic is further improved.

Further, when the central control unit judges that mixed powder with Qa quality needs to be added into the mixed material mixing unit, the central control unit judges whether the Qa needs to be adjusted to a corresponding value or not according to the grade of biomass powder in the mixed powder.

Furthermore, the central control unit is also provided with a preset critical additive amount Qamax of mixed powder, a preset critical additive amount Qbmax of starch and a preset critical additive amount Qcmax of a protective agent, and in the process of adding materials, if the total addition amount of a single material reaches the critical additive amount, the material of the type is not added.

Drawings

FIG. 1 is a schematic structural diagram of a system for preparing the degradable plastic of the present invention.

Detailed Description

In order that the objects and advantages of the invention will be more clearly understood, the invention is further described below with reference to examples; it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and do not limit the scope of the present invention.

It should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, which are only for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, it should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Fig. 1 is a schematic structural diagram of a system for preparing degradable plastics according to the present invention. The preparation system of the degradable plastic comprises:

the powder preparation unit is used for preparing biomass powder and comprises a plant raw material storage tank 11 for storing plants, a crushing mechanism 12 arranged at the output end of the plant raw material storage tank 11 and used for crushing the plants, a screen 13 arranged at the output end of the crushing mechanism 12 and used for screening crushed biomass powder, and a powder bearing bin 14 arranged at the output end of the screen 13 and used for loading the screened biomass powder; the plant crushing mechanism 12 is provided with crushing fan blades 121; a quality detector 131 for detecting the quality of the unscreened powder is arranged on the screen 13;

the powder stress relieving unit 2 is connected with the powder bearing bin 14 and used for receiving and compacting the biomass powder output by the powder bearing bin 14 so as to relieve the internal stress of the biomass powder, and a pressure detector 21 is arranged in the powder stress relieving unit 2 and used for detecting the pressure applied to the biomass powder by the powder stress relieving unit 2;

the mixed powder preparation unit 3 is connected with the powder stress relieving unit 2, and the top of the mixed powder preparation unit 3 is provided with a modified raw material storage tank group 31; when the mixed powder preparation unit 3 is operated, the mixed powder preparation unit 3 receives the biomass powder output by the powder stress relief unit 2 and the modified raw materials output by the modified raw material storage tanks in the modified raw material storage tank group 31, respectively, and stirs the biomass powder and the modified raw materials to prepare mixed powder;

a protective agent preparation unit 4 for preparing a protective agent;

the material mixing unit 5 is respectively connected with the mixed powder preparation unit 3 and the protective agent preparation unit 4, and the material mixing unit 5 is also connected with a starch storage tank 6; when the material mixing unit 5 operates, the material mixing unit 5 respectively receives the mixed powder output by the mixed powder preparation unit 3, the protective agent output by the protective agent preparation unit 4 and the starch output by the starch storage tank 6 and stirs the mixed powder, the protective agent and the starch to prepare a mixed material; a viscosity detector 51 is arranged in the material mixing unit 5 and used for detecting the viscosity of the mixed material in real time when the mixed material is prepared by the material mixing unit 5;

the granulating unit 7 is connected with the material mixing unit 5 and used for receiving the mixed material output by the material mixing unit 5, preparing the mixed material into degradable plastic master batches;

and the central control unit (not shown in the figure) is respectively connected with each unit, the components in each unit and each storage tank, and is used for adjusting the crushing rotating speed of the crushing fan blades 121 in the crushing mechanism 12 to a corresponding value according to the mass of the biomass powder which is not sieved when the system runs, grading the biomass powder prepared by the crushing mechanism when the mass of the biomass powder which is not sieved reaches the standard, and adjusting the pressure of the powder stress eliminating unit 2 on the biomass powder according to the grading result when the central control unit finishes grading the biomass powder.

The invention judges whether the biomass powder needs to be secondarily crushed or not according to the sieving proportion of the prepared biomass powder when the system is used for preparing the biomass powder by arranging the central control unit in the system, adjusts the crushing rotating speed of the crushing fan blades 121 to a corresponding value according to the actual non-sieving proportion of the biomass powder when the biomass powder is secondarily crushed, can effectively crush the prepared average mesh number of the biomass powder to a preset interval, and simultaneously, when the rotating speed of the crushing fan blades 121 is adjusted to a critical value, the prepared biomass powder is graded, and parameters in a subsequent process for preparing the degradable plastics are correspondingly adjusted according to the grading result, so that the biomass powder with different grades can be effectively mixed with all raw materials when being used as the raw materials for preparing the degradable plastics, and the preparation efficiency of the system for preparing the degradable plastics is effectively improved.

Specifically, the plants for preparing the biomass powder comprise dried crop straws, bean stalks, corn stalks, sorghum stalks, chaffs and tree bark materials, and the raw materials of the mixed powder comprise, by percentage, 40% of the biomass powder, 50% of PLA powder and PHA powder, 8.3% of natural rubber powder, 1.5% of an antioxidant (citric acid) and 0.2% of nano silver oxide.

The protective agent comprises one of the following three components:

the composition is as follows: 1-35 parts by mass of polyvinyl butyral (PVB), 1-45 parts by mass of polyvinyl methyl acetaldehyde (PVFA), 0-15 parts by mass of polyvinyl butyral (PVAC)1 type and 0-15 parts by mass of polyvinyl butyral (PVAC)2 type;

the composition is two: 1-35 parts by mass of polyvinyl butyral (PVB), 1-45 parts by mass of polyvinyl methyl acetaldehyde (PVFA), 15-60 parts by mass of polyvinyl butyral (PVAC)1 type and 15-60 parts by mass of polyvinyl butyral (PVAC)2 type;

the composition is three: 1-35 parts of polyvinyl butyral (PVB), 1-45 parts of polyvinyl methyl acetaldehyde (PVFA), 60-120 parts of polyvinyl butyral (PVAC)1 type and 60-120 parts of polyvinyl butyral (PVAC)2 type.

The preparation method of the protective agent comprises the following steps: firstly preparing a polyacetal protectant, which comprises the following components: 30 parts by mass of PVB, 30 parts by mass of PVFA, 2 parts by mass of PVAC-1 type and 2 parts by mass of PVAC-2 type; a solution of polyacetal protectant was then prepared: the polyacetal protectant was dissolved in ethanol to prepare a colorless transparent solution having a concentration of 12 wt%, thereby obtaining a polyacetal protectant solution.

Specifically, when the powder preparation unit prepares the biomass powder, the central control unit controls the plant raw material storage tank 11 to convey a plant with a preset mass M to the crushing mechanism 12 and controls the crushing fan blades 121 to rotate at a preset crushing rotation speed V to crush the plant output from the plant raw material storage tank 11, after crushing is completed, the crushing mechanism 12 conveys the biomass powder to the powder bearing bin 14 through a screen 13 with a first preset mesh number r1, after sieving, the central control unit controls the mass detector 131 to detect the mass of the biomass powder which is not sieved on the screen 13, calculates an occupation ratio B of the mass of the residual biomass powder to the plant mass output from the plant raw material storage tank 11, and compares B with a preset mass occupation ratio B0; if B is less than B0, the central control unit judges that the particle size of the biomass powder meets the standard and evaluates the biomass powder as first-grade biomass powder with high mesh number, and after the judgment is finished, the central control unit conveys the sieved biomass powder to the split stress eliminating unit; if B is larger than or equal to B0, the central control unit controls the screen 13 to convey the residual biomass powder to the crushing mechanism 12 through a feed back channel (not shown in the figure), calculates the difference value delta B between B and B0, and adjusts the rotating speed of the crushing fan blades 121 to a corresponding value according to the delta B so that the crushing mechanism performs secondary crushing on the residual biomass powder, and sets the delta B to be B-B0;

the central control unit is provided with a first preset mass difference value delta B1, a second preset mass difference value delta B2, a first preset crushing rotating speed regulating coefficient alpha 1 and a second preset crushing rotating speed regulating coefficient alpha 2; wherein, the delta B1 is less than delta B2, 1 is more than alpha 1 and more than alpha 2 and more than 1.3;

when the Δ B is not more than Δ B1, the central control unit does not adjust the crushing rotation speed of the crushing fan blades 121 when the crushing mechanism 12 performs secondary crushing on the remaining biomass powder;

when the delta B1 is less than the delta B and less than or equal to the delta B2, the central control unit adjusts the crushing rotating speed of the crushing fan blades 121 by using alpha 1 when the crushing mechanism 12 performs secondary crushing on the residual biomass powder;

when Δ B > [ Δ B ] 2, the central control unit adjusts the pulverizing rotational speed of the pulverizing fan blades 121 using α 2 when the pulverizing mechanism 12 performs secondary pulverization on the remaining biomass powder;

when the central control unit adjusts the pulverizing rotational speed of the pulverizing fan blades 121 using α i, i is set to 1, 2, and the adjusted pulverizing rotational speed of the pulverizing fan blades 121 is set to V', V ═ V × α i.

According to the invention, through adjusting the crushing rotating speed of the crushing fan blades 121, the biomass powder which is not sieved can be efficiently secondarily crushed, so that the mass ratio of the biomass powder which is sieved after secondary crushing is effectively improved, the mesh number of the biomass powder can be effectively crushed to be within a corresponding interval, the biomass powder can be further ensured to be effectively mixed with various raw materials when being used as the raw materials for preparing the degradable plastics, and meanwhile, the preparation efficiency of the system for the degradable plastics is further improved.

Specifically, a preset critical crushing rotation speed Vmax is set in the central control unit, and when the central control unit determines that the crushing rotation speed of the crushing fan blades 121 needs to be adjusted to V ', the central control unit compares V' with Vmax;

if V '< Vmax, the central control unit adjusts the crushing rotating speed of the crushing fan blade 121 to V', recalculates the ratio of the mass of the residual biomass powder on the screen 13 to the mass of the plants output by the plant raw material storage tank 11 after the crushing mechanism 12 finishes crushing the residual biomass powder, and readjusts the crushing rotating speed of the crushing fan blade 121 according to the difference between the mass of the residual biomass powder on the screen 13 and the mass of the plants output by the plant raw material storage tank 11 when the ratio is greater than or equal to B0 so as to crush the residual biomass powder again until the ratio of the mass of the residual biomass powder on the screen 13 after crushing to the mass of the plants output by the plant raw material storage tank 11 is less than B0;

if V '> Vmax, the central control unit sets the crushing rotating speed of the crushing fan blades 121 to Vmax, recalculates the ratio B' of the mass of the residual biomass powder on the screen 13 to the mass of the plants output by the plant raw material storage tank 11 after the crushing mechanism 12 finishes crushing the residual biomass powder, and ranks the biomass powder according to the ratio.

According to the invention, the biomass powder is graded when the crushing rotating speed reaches the critical value, so that the condition that the prepared biomass powder does not meet the standard of the corresponding grade due to the fact that the plant is crushed only by the crushing mechanism 12 can be effectively avoided, the mixing efficiency of the biomass powder and each raw material is prevented from being reduced, and the preparation efficiency of the system for the degradable plastics is further improved.

Specifically, when the central control unit compares B 'with B0 to grade the biomass powder, if B' is less than or equal to B0, the central control unit judges that the biomass powder is high-number biomass powder; if B ' > B0, the central control unit calculates the mass difference Delta B ' and grades the powder according to Delta B ', and sets Delta B ' ═ B ' -B0;

if the delta B' is less than or equal to the delta B1, the central control unit evaluates that the biomass powder is first-grade biomass powder with high mesh number;

if the delta B is more than delta B1 and is not more than delta B2, the central control unit controls the powder preparation unit to replace the screen 13 with a second preset mesh number r2 to screen the crushed residual biomass powder, wherein r2 is more than 80 and r1 is more than 120; if the ratio B' of the mass of the remaining biomass powder after screening to the total mass of the plants is less than or equal to B0, the central control unit evaluates that the biomass powder is secondary biomass powder with a medium mesh number;

if B 'is greater than B0, the central control unit calculates delta B' and judges the biomass powder according to the delta B ', and sets the delta B' -B0; if the delta B is less than or equal to the delta B1, the central control unit evaluates that the biomass powder is secondary biomass powder with a medium mesh; if delta B' > [ delta B ] 1, the central control unit evaluates that the biomass powder is the three-level biomass powder with low mesh number;

if delta B' > [ delta B ] 2, the central control unit evaluates that the biomass powder is the three-level biomass powder with low mesh number.

According to the invention, when the crushing rotating speed of the crushing fan blades 121 reaches the critical value, the biomass powder prepared at this time is accurately graded according to the mass ratio of the biomass powder which is not sieved after crushing, so that the biomass powder can be effectively mixed with various raw materials when being used as the raw material for preparing degradable plastics, and the preparation efficiency of the system for preparing the degradable plastics is further improved.

Specifically, when the central control unit finishes grading the mesh number of the biomass powder, the central control unit controls the plant raw material storage tank 11 to convey a corresponding amount of plants to the crushing mechanism 12 and controls the crushing fan blades 121 to crush the plants output from the plant raw material storage tank 11 at the adjusted crushing rotating speed, and during the crushing process, the central control unit detects the mass Ma of the biomass powder in the powder bearing bin 14 in real time until Ma reaches a preset mass Ma0, and Ma0 is set as M x (1-B0); when Ma is Ma0, the central control unit controls the powder bearing bin 14 to convey the sieved biomass powder to the powder stress relieving unit 2.

According to the invention, the biomass powder is supplemented after the grading is finished, so that the condition that the quality of the prepared biomass powder meeting the corresponding grade is lower than the use requirement can be effectively avoided, the mixing efficiency of the biomass powder and each raw material is further reduced, and the preparation efficiency of the system for degradable plastics is further improved.

Specifically, when the central control unit finishes grading the mesh number of the biomass powder and conveys the biomass powder to the powder stress relieving unit 2, the central control unit determines the pressure applied to the biomass powder by the powder stress relieving unit 2 according to the quality Ma of the biomass powder conveyed to the powder stress relieving unit 2, sets the pressure applied to the biomass powder by the powder stress relieving unit 2 to a corresponding value according to the grade of the biomass powder and adjusts the applied pressure to the corresponding value according to the grade of the biomass powder;

the central control unit is internally provided with a first preset plant mass M1, a second preset plant mass M2, a first preset pressure F1, a second preset pressure F2, a third preset pressure F3, a first preset pressure regulating coefficient beta 1 and a second preset pressure regulating coefficient beta 2, wherein M1 is more than M2, F1 is more than F2 and more than F3, and 1 is more than beta 1 and more than beta 2 and less than 1.5;

if Ma is less than or equal to M1, the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit 2 to be F1;

if M1 is more than Ma and less than or equal to M2, the central control unit preliminarily sets the pressure applied by the powder stress relief unit 2 to the biomass powder to be F2;

ma is more than M2, and the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relief unit 2 to be F3;

when the central control unit preliminarily sets the pressure applied to the biomass powder by the powder stress relieving unit 2 as Fj, setting j to be 1, 2, 3, and adjusting Fj according to the grade of the biomass powder;

if the biomass powder is primary biomass powder, the central control unit does not adjust Fj;

if the biomass powder is secondary biomass powder, the central control unit adjusts Fj by using beta 1;

if the biomass powder is three-level biomass powder, the central control unit adjusts Fj by using beta 2;

when the central control unit uses β k to adjust Fj, k is set to 1, 2, and the adjusted pressure is denoted as Fj ', and Fj' is set to Fj × β k.

According to the invention, the pressure applied by the eliminating unit to the biomass powder is preliminarily determined according to the quality of the received biomass powder to be stress-eliminated, and the pressure is adjusted to the corresponding value according to the specific grade of the biomass powder, so that the biomass powder can be effectively mixed with various raw materials when being used as the raw materials to prepare the degradable plastics, and the preparation efficiency of the system of the invention for the degradable plastics is further improved.

Specifically, when the material mixing unit 5 mixes the material and the mixing unit stirs the material for a preset time t at an initial stirring rotation speed W, the central control unit controls the viscosity detector 51 to detect the viscosity E of the material and adds the corresponding kind of raw material when it is determined that the viscosity of the material does not meet the standard; a preset viscosity interval E0(Emin, Emax) is arranged in the central control unit, wherein Emin is the preset lowest viscosity, and Emax is the preset highest viscosity;

if E belongs to E0, the central control unit judges that the viscosity of the material meets the standard;

if it isThe central control unit judges that the viscosity of the material does not meet the standard;

when in useIf E is less than Emin, the central control unit calculates the viscosity difference delta E and adjusts the initial stirring speed of the mixing unit or adds starch and mixed powder according to the delta E: the central control unit is internally provided with a first preset viscosity difference delta E1, a second preset viscosity difference delta E2, a first preset stirring rotating speed adjusting coefficient gamma 1 and a second preset stirring rotating speed adjusting coefficient gamma 2, wherein delta E1 is less than delta E2, and gamma 1 is more than 0.8 and less than gamma 2 and less than 1;

if the delta E is less than or equal to the delta E1, the central control unit increases the stirring rotating speed of the stirring unit by using gamma 2;

if delta E1 is less than delta E and less than delta E2, the central control unit increases the stirring rotating speed of the stirring unit by using gamma 1;

if delta E > -delta E2, the central control unit increases the stirring speed of the stirring unit by using gamma 1 and adds biomass powder with Qa quality and starch with Qb quality into the stirring unit, wherein Qa + Qb is 0.1 XQ 0, and Q0 is the total mass of the materials in the material mixing unit 5;

when the central control unit increases the stirring rotation speed of the stirring unit by using the gamma x, setting x to be 1, 2, and setting the increased stirring rotation speed to be W ', and setting W' to be W x (2-gamma x);

if E is more than Emin, the central control unit calculates the viscosity difference delta E 'and adjusts the initial stirring speed of the mixing unit or adds a protective agent according to the delta E':

if the delta E' is less than or equal to the delta E1, the central control unit reduces the stirring rotating speed of the stirring unit by using gamma 2;

if the delta E1 is less than the delta E' and less than the delta E2, the central control unit reduces the stirring rotation speed of the stirring unit by using gamma 1;

if delta E' > [ delta E2 ], the central control unit reduces the stirring speed of the stirring unit by using gamma 1 and adds a protective agent with the quality of Qc into the stirring unit, wherein the Qc is 0.15 multiplied by Q0;

when the central control unit reduces the stirring rotation speed of the stirring unit by using γ x, the reduced stirring rotation speed is denoted as W ", and W ═ W × γ x is set.

According to the invention, the preset viscosity interval is set, and corresponding raw materials are added according to actual conditions when the viscosity of the material does not belong to the preset interval, so that the quality of the prepared degradable plastic can be effectively improved while the viscosity of the material is ensured to meet the standard, and the preparation efficiency of the system for the degradable plastic is further improved.

Specifically, the central control unit is also provided with a first preset mixed powder addition quantity adjusting coefficient e1 and a second preset mixed powder addition quantity adjusting coefficient e2, wherein the addition quantity of the first preset mixed powder is more than 1 and less than e1 and less than e2 and less than 1.4;

when the central control unit judges that mixed powder with the quality of Qa needs to be added into the mixed material mixing unit 5, the central control unit judges whether the Qa needs to be adjusted according to the grade of biomass powder in the mixed powder;

if the biomass powder is primary biomass powder, the central control unit judges that the Qa is not required to be adjusted;

if the biomass powder is secondary biomass powder, the central control unit judges that the Qa needs to be adjusted and adjusts the Qa by using e 1;

if the biomass powder is three-level biomass powder, the central control unit judges that the Qa needs to be adjusted and adjusts the Qa by using e 2;

when the central control unit uses ey to adjust Qa, y is set to 1, 2, and the amount of the mixed powder added after adjustment is set to Qa ', Qa' is set to Qa × ey.

According to the invention, the addition amount of the mixed powder is adjusted according to the grade of the biomass powder, so that the viscosity of the material can be effectively adjusted to a corresponding value after the corresponding amount of the mixed powder is added, and the preparation efficiency of the system for the degradable plastics is further improved while the biomass powder can be effectively mixed with each raw material when being used as the raw material for preparing the degradable plastics.

Specifically, the central control unit is also provided with a preset critical adding amount Qamax of mixed powder, a preset critical adding amount Qbmax of starch and a preset critical adding amount Qcmax of a protective agent;

when the central control unit controls the starch storage tank 6 to add starch into the material in the material mixing unit 5, the central control unit records the total mass Qb0 of the added mixed powder, if Qb0 is greater than Qbmax, the central control unit does not control the starch storage tank 6 to add starch into the material in the material mixing unit 5 and only controls the mixed powder preparation unit 3 to add the mixed powder into the material in the material mixing unit 5 in the subsequent adding process;

when the central control unit controls the mixed powder preparation unit 3 to add the mixed powder into the material in the material mixing unit 5, the central control unit records the total mass Qa0 of the added mixed powder, if Qa0 is greater than Qamax, the central control unit does not control the mixed powder preparation unit 3 to add the mixed powder into the material in the material mixing unit 5, and only adjusts the stirring speed in the material mixing unit 5;

when the central control unit controls the protective agent preparation unit 4 to add the protective agent into the materials in the material mixing unit 5, the central control unit records the total mass Qc0 of the added protective agent, if Qc0 is larger than Qcmax, the central control unit does not control the protective agent preparation unit 4 to add the protective agent into the materials in the material mixing unit 5, and only adjusts the stirring speed in the material mixing unit 5.

According to the invention, by setting a plurality of preset critical addition amounts, the condition that the prepared degradable plastic does not meet the requirement due to the unbalance of the raw material ratio caused by excessive addition of a single material can be effectively avoided, and the preparation efficiency of the system aiming at the degradable plastic is further improved.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention; various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.