Pneumatic optimization system and method for high-power-to-weight-ratio single-stage high-vacuum turbine vacuum pump

Abstract

The invention discloses a system and a method for optimizing a high-power-to-weight-ratio single-stage high-vacuum turbine vacuum pump. Comprising a PLC (Programmable Logic Controller), a frequency converter and a gas-water separator arranged between a gas inlet of the high-power-to-weight-ratio single-stage high-vacuum turbine vacuum pump and a gas suction port of a paper machine, the flow sensor and the first temperature sensor are arranged at the outlet end of the gas-water separator; the energy recovery heat exchanger is arranged between a gas outlet of the high-power-to-weight-ratio single-stage high-vacuum turbine vacuum pump and a gas inlet of the silencer; the first pressure sensor and the second pressure sensor are respectively arranged at an air inlet and an air outlet of the energy recovery heat exchanger, and the PLC is electrically connected with a control end of the high-power-to-weight-ratio single-stage high-vacuum turbine vacuum pump through a frequency converter. According to the control system, the rotating speed of the efficient motor and the load change condition of the centrifugal impeller can be monitored in real time, and whether the vacuum degree and the air suction amount of the high-power-to-weight-ratio single-stage high-vacuum turbine vacuum pump meet preset conditions or not is judged. And process demand fluctuation can be accurately matched and adapted.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-power turbine vacuum pumps, and in particular relates to a pneumatic optimization system and method for a high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump. Background Art

[0002] The vacuum system of the papermaking machine plays an important role in the papermaking process. The papermaking machine introduces a vacuum system to keep the wet paper stable on the paper machine net, avoiding deformation and wrinkling of the paper due to factors such as humidity and temperature; the pressure below the paper machine net is reduced, so that the pressure of the contact surface between the net and the pulp is lower than the atmospheric pressure, thereby generating a pressure difference between the contact surface between the pulp and the atmospheric pressure and the vacuum contact surface. That is, the vacuum system forms a squeezing force on the upper and lower sides of the pulp to dehydrate the pulp and control the humidity of the wet paper when it enters the rear-end drying section.

[0003] The vacuum system of a paper machine accounts for 30%-40% of the system's energy consumption, making it a crucial component in both energy consumption and equipment investment. As the core component of a vacuum system, the performance of the vacuum pump directly determines the system's operational stability and energy efficiency. Furthermore, precise adjustment of the vacuum level plays a crucial role in improving paper machine production efficiency. Finely adjusting the vacuum level is crucial for ensuring both production efficiency and paper quality. This is especially true as paper machine speeds increase and paper dehydration time decreases, necessitating a corresponding increase in the vacuum level to ensure adequate dehydration.

[0004] Currently, large, high-performance paper machines typically use a positive displacement water ring vacuum pump and a high-speed turbine vacuum pump in series with a two-stage centrifugal impeller to meet vacuum requirements above 65kPa. Water ring vacuum pumps suffer from low energy efficiency, require water as a working medium, and are prone to scaling. The overall operating efficiency is 45% to 55%, and this efficiency decreases significantly with age. Furthermore, water volume control significantly impacts the operating efficiency of the water ring vacuum pump. Furthermore, the water ring vacuum pump is equipped with a low-speed power frequency motor that operates at a constant speed, making it difficult to precisely match the operating parameters of the water ring vacuum pump with the process requirements.

[0005] To address the need for energy conservation and consumption reduction, high-speed turbine vacuum pumps with two-stage centrifugal impellers in series are gradually being used to meet the high vacuum requirements of papermaking machines. These pumps require performance matching between the two impellers. Generally, it's difficult for both impellers to operate within their optimal aerodynamic efficiency range, resulting in a 3% to 5% loss in efficiency. Furthermore, once production process requirements deviate from the design point, the aerodynamic efficiency drops significantly, impacting the equipment's operating efficiency. Overall machine efficiency is typically 65% ​​to 70%. Furthermore, these pumps have a narrow adjustment range, making them prone to surge. Furthermore, when the two impellers deviate from their design point, their efficiency drops significantly, resulting in poor adjustability. Therefore, designing a high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump system addresses this performance matching issue for the two-stage series impellers, avoiding the high risk of surge and significantly improving energy efficiency. Summary of the Invention

[0006] The present invention aims to provide a pneumatic optimization system and method for a high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump. The high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump of the present invention features flexible operating mode adjustment, enabling precise adjustment of the turbine vacuum pump's operating parameters to accurately match process requirements and adapt to fluctuating process requirements caused by changes in paper machine operating conditions. To achieve this objective, the present invention employs the following technical solutions:

[0007] According to one aspect of the present invention, the present invention provides a pneumatic optimization system for a high power-to-weight ratio single-stage high vacuum turbine vacuum pump, the pneumatic optimization system including a PLC controller, a frequency converter, an air-water separator arranged between the air inlet of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump and the air suction port of a paper machine, a flow sensor and a first temperature sensor arranged at the outlet end of the air-water separator, and an energy recovery heat exchanger arranged between the air outlet of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump and the air inlet of a muffler, a first pressure sensor and a second pressure sensor respectively arranged at the air inlet and the air outlet of the energy recovery heat exchanger, the PLC controller is electrically connected to the control end of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump through the frequency converter, and the flow sensor, the first temperature sensor, the first pressure sensor and the second pressure sensor are respectively connected to the PLC controller.

[0008] The above scheme is preferred, wherein the high power-to-weight ratio single-stage high vacuum turbine vacuum pump includes a high-efficiency motor, a high-speed speed-increasing gear transmission assembly and a pneumatic assembly, wherein the pneumatic assembly includes a centrifugal impeller and a volute, wherein the centrifugal impeller is rotatably arranged in the volute, wherein the PLC controller is electrically connected to the terminal of the high-efficiency motor via a frequency converter, wherein the power output end of the high-efficiency motor is transmission-connected to the power input shaft of the high-speed speed-increasing gear transmission assembly, wherein the power output shaft of the high-speed speed-increasing gear transmission assembly is fixedly connected to the centrifugal impeller, wherein the energy recovery heat exchanger is arranged between the air outlet of the volute and the air inlet of the muffler, wherein a second temperature sensor is arranged at the air outlet of the volute, wherein a third temperature sensor is arranged on the air outlet side of the energy recovery heat exchanger, and wherein the gas-water separator is arranged between the air inlet of the volute and the air intake of the paper machine. The above scheme is preferred, wherein the volume of the gas-water separator and the rated suction capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump satisfy:

[0009] V ≥ Q*t / 60;

[0010] V is the volume of the gas-water separator, unit: m 3 ; Q is the rated suction capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump, unit: m 3 / min; t is time, unit: s;

[0011] The gas flow rate in the gas-water separator and the rated pumping capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump satisfy: ν = Q / (60*A);

[0012] A is the flow cross-sectional area of ​​the gas-water separator, in m2.

[0013] 5. The pneumatic optimization system for a high power-to-weight ratio single-stage high vacuum turbine vacuum pump according to claim 1 or 2, wherein the energy absorbed by the energy recovery heat exchanger satisfies:

[0014] W = c*m*(T1-T2);

[0015] Where W is the energy absorbed by the heat exchanger, in J; c is the specific heat capacity of the gas, in J / (kg·K); m is the mass of the gas passing through the energy heat exchanger, in kg; T1 is the gas temperature at the inlet of the energy recovery heat exchanger, and T2 is the gas temperature at the outlet of the energy recovery heat exchanger, both in K.

[0016] In the above solution, the rotation speed n of the centrifugal impeller and the output frequency f of the frequency converter satisfy:

[0017] n = C*f, where C is a constant, C = 60*Z1 / (p*Z2);

[0018] For this purpose, the rotation speed of the centrifugal impeller and the output frequency of the frequency converter are n=(60*f / p)*Z1 / Z2;

[0019] Among them, n is the speed of the centrifugal impeller, in r / min; f is the output frequency of the inverter, in Hz; p is the number of pole pairs of the high-efficiency variable frequency motor; Z1 is the number of teeth of the input large gear; Z2 is the number of teeth of the output small gear of the high-speed speed increase gearbox.

[0020] According to another aspect of the present invention, the present invention provides a pneumatic optimization method for a single-stage vacuum turbine vacuum pump with a high power-to-weight ratio, the pneumatic control method comprising the following steps:

[0021] According to the process fluctuation requirements of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump, the output frequency f of the inverter is set to set the vacuum degree and exhaust volume of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump;

[0022] Based on the output frequency f of the frequency converter, the speed change of the high-efficiency motor and the load change of the centrifugal impeller are monitored. Under the conditions of the vacuum degree and air extraction volume of the single-stage high vacuum turbine vacuum pump with a high power-to-weight ratio, the comprehensive aerodynamic efficiency η at the rated aerodynamic point position of the centrifugal impeller and the volute is calculated.

[0023] If the comprehensive aerodynamic efficiency η meets the preset aerodynamic efficiency condition, the vacuum degree of the centrifugal impeller and the volute is judged based on the comprehensive aerodynamic efficiency η to determine whether it meets the system's process demand fluctuations. If so, the system's process demand fluctuations are continuously monitored. If not, the output frequency of the inverter is adjusted until the system's process demand fluctuations are met.

[0024] The above solution is preferred. If the comprehensive aerodynamic efficiency of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump does not meet the preset aerodynamic efficiency conditions, then the intake pressure value P of the air inlet of the energy recovery heat exchanger is obtained. i1 And the outlet pressure value P o2 , if P i1 -P o2 >1kPa, adjust the flow structure of the energy recovery heat exchanger to reduce the gas flow rate and reduce the pressure loss; if P i1 -P o2 If the pressure is less than 1kPa, the design of centrifugal impeller and volute should be optimized.

[0025] In summary, the invention adopts the above technical solution, and the invention has the following technical effects:

[0026] (1) The present invention has high operating efficiency. For high vacuum pumps, especially high power-to-weight ratio single-stage high vacuum turbine vacuum pumps, the efficiency can be improved by 35% compared to water ring vacuum pumps, and by 5% to 10% compared to two-stage series turbine vacuum pumps. In addition, the energy recovery device configured at the gas outlet can further improve the energy utilization rate of the vacuum system.

[0027] (2) The adjustment method of the present invention is flexible and accurate. The high power-to-weight ratio single-stage high vacuum turbine vacuum pump adopts variable frequency adjustment. Compared with the two-stage series turbine vacuum pump, it avoids the efficiency loss caused by the unbalanced performance matching between the two centrifugal impellers, and is more adaptable to the working conditions of the paper machine caused by the fluctuation of process requirements. The present invention adopts a single-stage centrifugal impeller to achieve the high vacuum required by the high-performance paper machine. The single-stage centrifugal impeller is easier to adjust, closer to the process requirements, and simpler to control.

[0028] (3) The high power-to-weight ratio single-stage high vacuum turbine vacuum pump has high power density and compact structure, and has low installation requirements. It is easy to install and arrange, reducing the investment in infrastructure costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a system principle diagram of a pneumatic control system for a single-stage vacuum turbine vacuum pump with a high power-to-weight ratio according to the present invention;

[0030] Figure 2 It is a schematic diagram of the high-speed speed-increasing gear transmission system of the present invention;

[0031] Figure 3 This is a PLC optimized control flow chart of a high power-to-weight ratio single-stage high vacuum turbine vacuum pump of the present invention;

[0032] In the accompanying drawings, there are a PLC controller 1, a frequency converter 2, a high power-to-weight ratio single-stage high vacuum turbine vacuum pump 3, a gas-water separator 4, a flow sensor 5, a first temperature sensor 6, a muffler 8, an energy recovery heat exchanger 9, a second temperature sensor 10, a first pressure sensor 11, a second pressure sensor 12, a high-efficiency motor 30, a high-speed speed-increasing gear transmission assembly 31, a pneumatic assembly 32, a gear box 310, an input gear shaft 311, an output gear shaft 312, an input large gear 313, an output small gear 314, an input shaft round pad sliding bearing 315, a high-speed tilting pad sliding bearing 316, and a coupling 317. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the invention more clearly understood, the invention is further described below with reference to the accompanying drawings and by way of preferred embodiments. However, it should be noted that many of the details listed in this specification are merely provided to help the reader gain a thorough understanding of one or more aspects of the invention, and that these aspects of the invention can be practiced even without these specific details.

[0034] Combine Figure 1The present invention provides a pneumatic optimization system for a high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump, the pneumatic control system comprising a PLC controller 1, a frequency converter 2, an air-water separator 4 arranged between the air inlet of the high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump 3 and the air suction port of a paper machine, a flow sensor 5 and a first temperature sensor 6 arranged at the outlet end of the air-water separator, an energy recovery heat exchanger 9 arranged between the air outlet of the high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump 3 and the air inlet of a muffler 8, a first pressure sensor 11 and a second pressure sensor 12 respectively arranged at the air inlet and the air outlet of the energy heat exchanger 9; the first pressure sensor 11 is used to detect the intake pressure on the air inlet side of the energy recovery heat exchanger 9, and the second pressure sensor 12 is used to detect the intake pressure on the air outlet side of the energy recovery heat exchanger 9; in the present invention, the PLC controller 1 is connected to the frequency converter 2 It is electrically connected to the control end of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump 3, and the flow sensor 5, the first temperature sensor 6, the first pressure sensor 11 and the second pressure sensor 12 are respectively connected to the PLC controller; in the present invention, the high power-to-weight ratio single-stage high vacuum turbine vacuum pump 3 includes a high-efficiency motor 30, a high-speed speed-increasing gear transmission assembly 31 and a pneumatic assembly 32, the pneumatic assembly 32 includes a centrifugal impeller and a volute, the centrifugal impeller is arranged in the volute through the rotation of the rotating shaft, because the single-stage centrifugal impeller must meet the high vacuum requirement, the vacuum degree of the centrifugal impeller is ≥70kPa, so a higher rotation speed is required, for this reason, the linear speed at the maximum wheel rim of the centrifugal impeller is ≥500m / s, the centrifugal impeller is made of titanium alloy forging blank, and is integrally milled and formed using a five-axis machining center. The centrifugal force of the centrifugal impeller is large at high speed, and its maximum stress σ is ≤0.8σ under the state of maximum centrifugal force. s To ensure the centrifugal impeller does not break, a certain safety margin is left. The comprehensive aerodynamic efficiency of the centrifugal impeller and volute at the rated aerodynamic point is η ≥ 80% under the conditions of the specified vacuum and air volume. The volute is precision cast using QT400 or 316 stainless steel. The complex flow path surface is determined by joint aerodynamic simulation with the centrifugal impeller, and the accuracy is guaranteed by the mold.

[0035] In the present invention, Figure 1As shown, the PLC controller 1 is electrically connected to the terminal (frequency conversion control terminal) of the high-efficiency motor 30 through the frequency converter 2, the power output terminal of the high-efficiency motor 30 is connected to the power input shaft of the high-speed speed-increasing gear transmission component 31, the power output terminal of the high-speed speed-increasing gear transmission component 31 is fixedly connected to the centrifugal impeller, the energy recovery heat exchanger is arranged between the air outlet of the volute and the air inlet of the muffler, a second temperature sensor 10 is arranged in the pipe on the air outlet side of the volute, and a third temperature sensor 13 is arranged in the pipe on the outlet gas side of the energy recovery heat exchanger 9. The air-water separator 4 is arranged between the air inlet of the volute and the air suction port of the paper machine; in the present invention, the inverter 2 is installed on the ground in the distribution room, and the distribution power supply is connected to the input terminal of the inverter 2 by a cable. The output terminal of the inverter 2 is connected to the terminal of the high-efficiency motor 30 by a cable. The high-efficiency motor 30 is installed on the mounting base of the high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump and is fastened to the mounting base by bolts. The high-efficiency motor 30 adopts a three-phase asynchronous motor or a permanent magnet synchronous motor with a speed of 3000r / min, which can reduce the transmission ratio of the high-speed speed-increasing gearbox and reduce the design difficulty.

[0036] In the present invention, combined with Figure 2 The high-speed speed-increasing gear transmission assembly 31 includes a gear box body 310, an input gear shaft 311, an output gear shaft 312, an input large gear 313 and an output small gear 314 arranged in parallel in the gear box body 310, the input gear shaft 311 is mounted on the gear box body 310 through an input shaft round pad sliding bearing 315, the output gear shaft 312 is mounted on the gear box body 310 through a high-speed tilting pad sliding bearing 316, the input large gear 313 is arranged on the input gear shaft 311, and the output small gear 314 is arranged on the output gear shaft. One end of the input gear shaft 311 is connected to the power output end of the high-efficiency motor 30 through an input coupling 317. The input gear shaft 311 and the output gear shaft 312 are connected to each other through a coupling 317. The transmission is achieved through the mutual meshing of the input large gear 313 and the output small gear 314; the high-speed speed-increasing gear transmission assembly 31 is installed on the mounting base of the high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump and is fixed to the mounting base by bolts. After centering with a laser alignment instrument, the motor shaft of the high-efficiency motor 30 is connected to the input gear shaft 311 of the gear box body 310 by a diaphragm coupling 317; the gear box body 310 adopts a first-stage helical gear transmission, that is, the input large gear 313 drives the output small gear 314, and the transmission ratio of the input large gear 313 to the output small gear 314 is ≤10. The input gear shaft 311 is installed on the gear box body 310 by a round pad sliding bearing 315, and the output shaft is supported by a tilting pad sliding bearing 316. The axial force is borne by the thrust bearing.

[0037] In the present invention, the air intake system of the turbine vacuum pump has a large water content in the gas discharged from the vacuum suction port of the paper machine, which affects the operating performance of the turbine vacuum pump. Therefore, it is necessary to set a gas-water separator at the front end of the volute inlet to effectively separate the gas before entering the volute. The volume of the gas-water separator and the rated air extraction capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump meet the following requirements:

[0038] V ≥ Q*t / 60;

[0039] V is the volume of the gas-water separator, unit: m 3 ; Q is the rated suction capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump, unit: m 3 / min; t is time, unit is: s, usually t = 1s;

[0040] The gas flow rate in the gas-water separator and the rated pumping capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump satisfy: ν = Q / (60*A);

[0041] A is the flow cross-sectional area of ​​the gas-water separator, in m2;

[0042] In the present invention, since the vacuum degree of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump is high and the pressure ratio of the centrifugal impeller is large, the pressure ratio is ≥3.3, so the temperature of the centrifugal impeller outlet is relatively high, and the energy recovery device can be used to recover heat, further improving the energy utilization rate of the system, and the pressure loss P of the energy recovery heat exchanger is loss Too much will cause the energy consumption of the vacuum pump to increase, so it is necessary to control P loss ≤1kPa (including the pressure loss of the silencer). A resistive and resistive composite silencer is set at the outlet of the energy recovery heat exchanger to reduce the airflow noise and control the noise value within 85dB. To this end, the energy absorbed by the energy heat exchanger meets the following requirements:

[0043] W = c*m*(T1-T2);

[0044] Wherein, W is the energy absorbed by the heat exchanger, in J; c is the specific heat capacity of the gas, in J / (kg·K); m is the mass of the gas passing through the energy heat exchanger, in kg; T1 is the gas temperature at the inlet of the energy heat exchanger, and T2 is the gas temperature at the outlet of the energy heat exchanger. The units of T1 and T2 are K, where the gas temperature T2 at the outlet of the energy heat exchanger is measured by the third temperature sensor 13.

[0045] The rotation speed of the centrifugal impeller and the output frequency of the frequency converter satisfy:

[0046] n = C*f, where C is a constant, C = 60*Z1 / (p*Z2);

[0047] For this purpose, the rotation speed of the centrifugal impeller and the output frequency of the frequency converter are n=(60*f / p)*Z1 / Z2;

[0048] Among them, n is the speed of the centrifugal impeller, in r / min; f is the output frequency of the inverter, in Hz; p is the pole pair number of the high-efficiency variable-frequency motor; Z1 is the number of teeth of the input large gear; Z2 is the number of teeth of the output small gear of the high-speed speed-increasing gearbox. Therefore, after the number of teeth of the gearbox and the number of poles of the high-efficiency motor are determined, changing the output frequency f of the inverter can effectively change the operating speed of the centrifugal impeller, and thus change the vacuum degree and suction volume of the single-stage high vacuum turbine vacuum pump.

[0049] According to another aspect of the present invention, a pneumatic control method for a high power-to-weight ratio single-stage high vacuum turbine vacuum pump system is provided. The pneumatic control method comprises the following steps:

[0050] Step 1: setting the output frequency f of the frequency converter according to the process fluctuation requirements of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump to set the vacuum degree and the suction volume of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump;

[0051] Step 2: Monitor the speed change of the high-efficiency motor and the load change of the centrifugal impeller based on the output frequency f of the frequency converter. Under the conditions of the vacuum degree and air extraction volume of the single-stage high vacuum turbine vacuum pump with a high power-to-weight ratio, calculate the comprehensive aerodynamic efficiency η at the rated aerodynamic point position of the centrifugal impeller and the volute.

[0052] Step 3: If the comprehensive aerodynamic efficiency η meets the preset aerodynamic efficiency condition, the vacuum degree of the centrifugal impeller and the volute is determined based on the comprehensive aerodynamic efficiency η to determine whether it meets the process demand fluctuation of the system. If it does, the process demand fluctuation of the system is continuously monitored. If it does not, the output frequency of the frequency converter is adjusted until it meets the process demand fluctuation of the system. When the output frequency does not change, if the centrifugal impeller speed remains unchanged, the vacuum degree decreases, and the air extraction volume increases; if the vacuum degree increases, the air extraction volume decreases.

[0053] In the present invention, when adjusting the speed, while ensuring that the vacuum degree remains unchanged, increasing the speed increases the suction volume, and reducing the speed reduces the suction volume; when judging the vacuum degree of the centrifugal impeller and the volute, the pressure ratio of the centrifugal impeller is the absolute pressure Ps of the volute outlet and the absolute pressure P of the volute inlet. d , calculate the absolute pressure Ps at the volute outlet and the absolute pressure P at the volute inlet d The ratio (pressure ratio), if Ps / P d ≥3.3, then the process fluctuation requirements are met. If the absolute pressure at the outlet of the vacuum pump is atmospheric pressure, the greater the vacuum degree at the inlet and the lower the absolute pressure, the greater the pressure ratio; and the comprehensive aerodynamic efficiency η satisfies:

[0054]

[0055] η is the comprehensive aerodynamic efficiency of the centrifugal impeller and volute; k is the medium insulation coefficient,

[0056] P o is the volute outlet pressure; P i is the centrifugal impeller inlet pressure;

[0057] T O is the volute outlet temperature, and the volute outlet temperature T O The same as the gas temperature T1 at the energy recovery heat exchanger inlet, measured by the second temperature sensor 10;

[0058] T i is the centrifugal impeller inlet temperature, and the centrifugal impeller inlet temperature Ti is measured by the first temperature sensor 5.

[0059] In the present invention, if the comprehensive aerodynamic efficiency of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump does not meet the preset conditions, the intake pressure value P of the air inlet of the energy recovery heat exchanger is obtained. i1 And the outlet pressure value P o2 , if P i1 -P o2 >1kPa, adjust the flow structure of the energy recovery heat exchanger to reduce the gas flow rate and reduce the pressure loss. i1 -P o2 If the pressure is less than 1kPa, the design of the centrifugal impeller and the volute is optimized. By optimizing the structural parameters of the centrifugal impeller, the purpose of adjusting the comprehensive aerodynamic efficiency is achieved, and the volute flow channel is matched with the centrifugal impeller.

[0060] In the present invention, the PLC controller detects fluctuations in process requirements in real time, and by changing the output frequency of the frequency converter, changes the speed of the motor, and then changes the vacuum degree and suction volume of the turbine vacuum pump to automatically adapt to changes in process requirements and feedback to the PLC control system. If the process system requirements are met, the process system requirements will continue to be monitored; if the process requirements are not met, the output frequency of the frequency converter will continue to be adjusted until the process system requirements are met. The high power-to-weight ratio single-stage high vacuum turbine vacuum pump has high power density and adopts a high-speed gear transmission system and a high-speed complex curved centrifugal impeller. It has a high speed, a small size, a high power density, a high power output per unit weight, and a small footprint. Because the high power-to-weight ratio single-stage high vacuum turbine vacuum pump has a compact structure, high power density, and is supported by flexible shock absorbers, it is simple to arrange on site and can be installed on a high-rise platform, making pipeline arrangement easy.

[0061] The above is only a preferred embodiment of the invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the invention. These improvements and modifications should also be regarded as within the scope of protection of the invention.

Claims

1. A high power-to-weight ratio single-stage high vacuum turbine vacuum pump pneumatic optimization system, characterized by: The pneumatic optimization system includes a PLC controller, a frequency converter, an air-water separator arranged between the air inlet of a high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump and the air suction port of a paper machine, a flow sensor and a first temperature sensor arranged at the outlet end of the air-water separator, an energy recovery heat exchanger arranged between the air outlet of the high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump and the air inlet of a muffler, and a first pressure sensor and a second pressure sensor respectively arranged at the air inlet and the air outlet of the energy recovery heat exchanger. The PLC controller is electrically connected to the control end of the high-power-to-weight ratio single-stage high-vacuum turbine vacuum pump through the frequency converter, and the flow sensor, the first temperature sensor, the first pressure sensor and the second pressure sensor are respectively connected to the PLC controller.

2. The high power-to-weight ratio single-stage high vacuum turbine vacuum pump pneumatic optimization system according to claim 1, characterized in that: The high power-to-weight ratio single-stage high vacuum turbine vacuum pump includes a high-efficiency motor, a high-speed speed-increasing gear transmission assembly and a pneumatic assembly. The pneumatic assembly includes a centrifugal impeller and a volute. The centrifugal impeller is rotatably arranged in the volute. The PLC controller is electrically connected to the terminal of the high-efficiency motor through a frequency converter. The power output end of the high-efficiency motor is transmission-connected to the power input shaft of the high-speed speed-increasing gear transmission assembly. The power output shaft of the high-speed speed-increasing gear transmission assembly is fixedly connected to the centrifugal impeller. The energy recovery heat exchanger is arranged between the air outlet of the volute and the air inlet of the muffler. A second temperature sensor is arranged at the air outlet of the volute. A third temperature sensor is arranged on one side of the air outlet of the energy recovery heat exchanger. The air-water separator is arranged between the air inlet of the volute and the air intake of the paper machine.

3. The high power-to-weight ratio single-stage high vacuum turbine vacuum pump pneumatic optimization system according to claim 2, characterized in that: The high-speed speed-increasing gear transmission assembly includes a gear box body, an input gear shaft, an output gear shaft, an input large gear and an output small gear arranged in parallel in the gear box body, the input gear shaft is supported on the gear box body through an input shaft circular pad sliding bearing, the output gear shaft is supported on the gear box body through a tilting pad sliding bearing, the input large gear is arranged on the input gear shaft, and the output small gear is arranged on the output gear shaft, one end of the input gear shaft is connected to the power output shaft of the high-efficiency motor through an input coupling, and the input gear shaft and the output gear shaft are meshed with each other through the input large gear and the output small gear.

4. The high power-to-weight ratio single-stage high vacuum turbine vacuum pump pneumatic optimization system according to claim 1 or 2, characterized in that: The volume of the gas-water separator and the rated pumping capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump meet the following requirements: V ≥ Q*t / 60; V is the volume of the gas-water separator, unit: m 3 ; Q is the rated suction capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump, unit: m 3 / min; t is time, unit: s; The gas flow rate in the gas-water separator and the rated pumping capacity of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump satisfy the following conditions: ν = Q / (60*A); A is the flow cross-sectional area of ​​the gas-water separator, in m2.

5. The pneumatic optimization system for a high power-to-weight ratio single-stage high vacuum turbine vacuum pump according to claim 1 or 2, characterized in that: The energy absorbed by the energy recovery heat exchanger satisfies: W = c*m*(T1-T2); Where W is the energy absorbed by the heat exchanger, in J; c is the specific heat capacity of the gas, in J / (kg·K); m is the mass of the gas passing through the energy heat exchanger, in kg; T1 is the gas temperature at the inlet of the energy recovery heat exchanger, and T2 is the gas temperature at the outlet of the energy recovery heat exchanger, both in K.

6. The high power-to-weight ratio single-stage high vacuum turbine vacuum pump pneumatic optimization system according to claim 3, characterized in that: The rotation speed n of the centrifugal impeller and the output frequency f of the frequency converter satisfy: n = C*f, where C is a constant, C = 60*Z1 / (p*Z2); For this purpose, the rotation speed of the centrifugal impeller and the output frequency of the frequency converter are n=(60*f / p)*Z1 / Z2; Among them, n is the speed of the centrifugal impeller, in r / min; f is the output frequency of the inverter, in Hz; p is the number of pole pairs of the high-efficiency variable frequency motor; Z1 is the number of teeth of the input large gear; Z2 is the number of teeth of the output small gear of the high-speed speed increase gearbox.

7. A pneumatic optimization method for a high power-to-weight ratio single-stage vacuum turbine vacuum pump, characterized by: The pneumatic control method comprises the following steps: According to the process fluctuation requirements of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump, the output frequency f of the inverter is set to set the vacuum degree and exhaust volume of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump; Based on the output frequency f of the frequency converter, the speed change of the high-efficiency motor and the load change of the centrifugal impeller are monitored. Under the conditions of the vacuum degree and air extraction volume of the single-stage high vacuum turbine vacuum pump with a high power-to-weight ratio, the comprehensive aerodynamic efficiency η at the rated aerodynamic point position of the centrifugal impeller and the volute is calculated. If the comprehensive aerodynamic efficiency η meets the preset aerodynamic efficiency condition, the vacuum degree of the centrifugal impeller and the volute is judged based on the comprehensive aerodynamic efficiency η to determine whether it meets the system's process demand fluctuations. If so, the system's process demand fluctuations are continuously monitored. If not, the output frequency of the inverter is adjusted until the system's process demand fluctuations are met.

8. The aerodynamic optimization method for a high power-to-weight ratio single-stage vacuum turbine vacuum pump according to claim 7, characterized in that: If the comprehensive aerodynamic efficiency of the high power-to-weight ratio single-stage high vacuum turbine vacuum pump does not meet the preset aerodynamic efficiency conditions, the inlet pressure value P of the air inlet of the energy recovery heat exchanger is obtained. i1 And the outlet pressure value P o2 , if P i1 -P o2 >1kPa, adjust the flow structure of the energy recovery heat exchanger to reduce the gas flow rate and reduce the pressure loss; if P i1 -P o2 If the pressure is less than 1kPa, the design of centrifugal impeller and volute should be optimized.

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