WO2020102958A1 - 一种可精确控制流量的计量泵控制*** - Google Patents

一种可精确控制流量的计量泵控制***

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Publication number
WO2020102958A1
WO2020102958A1 PCT/CN2018/116314 CN2018116314W WO2020102958A1 WO 2020102958 A1 WO2020102958 A1 WO 2020102958A1 CN 2018116314 W CN2018116314 W CN 2018116314W WO 2020102958 A1 WO2020102958 A1 WO 2020102958A1
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Prior art keywords
flow
metering pump
flow rate
output
control system
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PCT/CN2018/116314
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English (en)
French (fr)
Inventor
韩正奇
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中芳特纤股份有限公司
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Priority to PCT/CN2018/116314 priority Critical patent/WO2020102958A1/zh
Publication of WO2020102958A1 publication Critical patent/WO2020102958A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity

Definitions

  • the invention relates to the technical field of metering equipment, in particular to a metering pump control system capable of accurately controlling flow.
  • the metering pump is a special volume pump that can meet the requirements of various strict technological processes.
  • the flow rate can be adjusted steplessly within the range of 0-100%. It is used to transport liquids (especially corrosive liquids). It is widely used in the quantitative and proportional dosing of fluids in petroleum, chemical, water treatment, food, pharmaceutical, environmental protection, medical equipment and other industries (referred to as fluid constant dosing), and has become the heart and engine of the process industry.
  • the first one is to adjust the flow of liquid by manually rotating the flow adjustment handle.
  • the second method is to adjust the flow rate of the metering pump by adjusting the frequency converter.
  • the metering pump is a positive displacement pump, and the flow rate fluctuates in a sinusoidal curve, the accurate flow rate output by the metering pump cannot be obtained in real time.
  • the above two flow adjustment methods have certain blindness, which greatly reduces the accuracy of the metering pump.
  • the traditional control method has a long operation time, low flow control accuracy, and a large cumulative error, which cannot meet the process requirements.
  • the present invention proposes a metering pump control system that can accurately control the flow rate.
  • the flow control system has high precision and high efficiency, and can be widely used in the field that requires precise and rapid control of the metering pump flow rate. .
  • the metering pump flow control system proposed by the present invention includes:
  • Buffer used to clip the smooth wave to the pulsating flow output by the metering pump
  • the controller is used to collect flow signals in real time and process the flow signals, compare the set flow and actual flow, and control the output of the inverter through a software algorithm;
  • the frequency converter controls the speed of the metering pump by receiving the speed signal output by the controller, which has achieved the purpose of controlling the fluid flow;
  • the buffer described in the present invention mainly plays the role of physical filtering.
  • the capacity of the buffer tank must be more than 10 times the capacity of the metering pump to obtain a better filtering effect.
  • the nitrogen inlet, outlet and a gas pressure gauge are installed on the top of the buffer tank, and the liquid material inlet is installed on the side of the buffer tank, the height is 60% -70% Left and right, the outlet is installed at the bottom of the buffer.
  • Fluid material flows in through the upper part of the buffer and flows out at the bottom.
  • the pressure sensor installed on the top of the buffer tank is used to detect the nitrogen pressure in the buffer tank. When the nitrogen pressure in the tank is insufficient, the nitrogen is supplied through the nitrogen input valve. When the nitrogen pressure in the tank is too high, the nitrogen is released through the nitrogen output valve.
  • the flowmeter of the present invention requires that the length of the upstream straight pipe section of the flowmeter should be at least 5 times the pipe diameter, and the length of the downstream straight pipe section should be at least 3 times the pipe diameter.
  • the process tube and the sensor must be concentric, and the coaxial deviation is not greater than 0.05DN. (DN refers to the diameter of the pipe)
  • the metering pump needs to be turned on first to allow a certain amount of material to be stored in the buffer tank.
  • the height of the material liquid level is higher than the entrance of the buffer tank and does not exceed 80% of the height of the buffer tank.
  • the filtered flow signal is accumulated in the timing period T to obtain the cumulative flow Q.
  • the average instantaneous flow F Q / T is calculated.
  • the accumulated flow Q is cleaned at the same time, and the flow is accumulated in the next timing period.
  • the average instantaneous flow rate F and the set flow rate F s are processed by the PID algorithm to obtain an output value, and this output value is converted into a frequency signal of the frequency converter and output to the frequency converter, and the flow rate of the metering pump is controlled by controlling the speed of the frequency converter.
  • FIG. 1 is a block diagram of the system of the present invention
  • the serial numbers in the system block diagram of Figure 1 are: 1) Metering pump, 2) Frequency converter, 3) Nitrogen input valve, 4) Pressure sensor, 5) Nitrogen output valve, 6) Buffer tank, 7) Nitrogen pipeline, 8) Fluid Material pipeline, 9) flowmeter, 10) controller
  • the invention discloses a metering pump control system capable of accurately controlling the flow rate.
  • the following implementation example will be described in conjunction with FIGS. 1 and 2.
  • the equipment used in this implementation example is as follows:
  • the metering pump uses a plunger metering pump with a working flow of 200L / h and a motor using a 1.1kw variable frequency motor;
  • the buffer as shown in (6) in Figure 1, has a capacity of 2L;
  • the flowmeter uses an electromagnetic flowmeter with a range of 400L / h and an output signal of 4-20ma (4ma corresponds to 0L / h and 20ma corresponds to 400L / h);
  • the controller uses a Siemens S7-300 controller, which is installed with a 4-20ma analog input module and a 4-20ma analog output module.
  • the frequency converter as shown in (2) in Figure 1, uses Siemens MM440 frequency converter with a power of 1.5kw.
  • the height of the liquid level of the material is required to be higher than the inlet of the buffer tank and not exceed 80% of the height of the buffer tank.
  • the flow control scheme in the controller performs software filtering on the flow signal received from the flowmeter.
  • the filtering algorithm can use sliding filtering or average filtering.
  • the filtered flow signal is accumulated in the timing period T to obtain the cumulative flow Q.
  • the accumulated flow Q is cleaned at the same time, and the flow is accumulated in the next timing period.
  • the average instantaneous flow rate F and the set flow rate F s are processed by the PID algorithm to obtain an output value, and this output value is converted into a frequency signal of the frequency converter and output to the frequency converter, and the flow rate of the metering pump is controlled by controlling the speed of the frequency converter.
  • the controller detects and controls the pressure of the buffer tank at the same time. When the controller detects that the nitrogen pressure in the tank is insufficient, the nitrogen is supplemented through the nitrogen input valve. When the nitrogen pressure in the tank is too high, the nitrogen is released through the nitrogen output valve.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Flow Control (AREA)

Abstract

一种可精确控制流量的计量泵控制***，该计量泵流量控制***包括：计量泵（1）、缓冲器（6）、流量计（9）、控制器（10）和变频器（2），通过缓冲罐（6）滤波、软件滤波算法准确得到计量泵（1）输出的瞬时流量，控制器（10）通过PID算法将瞬时流量和设定流量进行计算控制变频器（2）的输出频率，从而调节计量泵（1）的输出流量。该流量控制***精度高，效率高，可广泛应用于需要精确、快速控制计量泵流量的领域。

Description

一种可精确控制流量的计量泵控制*** 技术领域
本发明涉及计量设备的技术领域，特别涉及一种可精确控制流量的计量泵控制***。
背景技术
计量泵是一种可以满足各种严格的工艺流程需要，流量可以在0-100％范围内无级调节，用来输送液体(特别是腐蚀性液体)一种特殊容积泵。广泛应用于石油、化工、水处理、食品、制药、环保、医疗器械等行业的流体定量投加和比例投加(简称流体定比投加)，已成为流程工业的心脏和发动机。
在现有的计量泵应用中，为达到控制流量的目的通常有两种控制方案。第一种，通过手动旋转流量调节手柄进而调节液体的流量。第二种，通过调节变频器调节计量泵转速的方法实现流量调节。但是，由于计量泵属于容积泵，流量成正弦曲线波动的，无法实时获取计量泵输出的准确流量，导致以上两种流量调节方式都带有一定的盲目性，大大降低计量泵的使用精度。特别在化纤和精细化工领域，如果使用过程中要频繁的改变流量，传统的控制方式操作时间长，流量控制精度低，累计误差大，无法满足工艺需求。
发明内容
本发明针对现有计量泵应用中存在的不足，提出一种可精确控制流量的计量泵控制***，该流量控制***精度高，效率高，可广泛应用于需要精确、快速控制计量泵流量的领域。
为实现快速精确控制计量泵流量，本发明提出的计量泵流量控制***包括：
1)计量泵，用于输送流体物料并通过转速控制输出流体物料的流量；
2)缓冲器，用于对计量泵输出的脉动流量起到削波平波的作用；
3)流量计，用于检测输出的瞬时流量，并将流量以4-20ma电流信号传输到控制器中；
4)控制器，用于实时采集流量信号，并对流量信号进行处理，对比设定流量和实际流量，通过软件算法控制变频器的输出；
5)变频器，通过接收控制器输出的转速信号，控制计量泵的转速，已达到控制流体流量的目的；
本发明中所述的缓冲器，主要起到物理滤波的效果。缓冲罐的容量要大于计量泵容量的10倍以上才能得到比较好的滤波效果，缓冲罐顶部安装氮气入口、出口以及一个气体压力表，液体物料入口安装在缓冲罐侧面，高度60％-70％左右，出口安装在缓冲器底部。
流体物料通过缓冲器的上部流入，底部流出。缓冲罐顶部安装的压力传感器用于检测缓冲罐内的氮气压力，当罐内氮气压力不足时，通过氮气输入阀补充氮气，当罐内氮气压力过高时，通过氮气输出阀释放氮气。
本发明所述的流量计，要求流量计上游直管段长度至少应为5倍管径，下游直管段长度至少为3倍管径。工艺管与传感器必须同心，同轴偏差不大于0.05DN。(DN指的是管道的直径)
缓冲器在使用过程中，需要先开启计量泵，让缓冲罐内储存一定量的物料，要求物料液位高度高于缓冲罐的入口，并且不超过缓冲罐高度的80％。
本发明中所述的控制***，接收到流量计的流量信号后，要先进行软件滤波，滤波算法可采用滑动滤波或平均值滤波。
通过滤波后的流量信号在定时周期T内进行累计得到累计流量Q，当定时周期结束时，计算平均瞬时流量F＝Q/T。定时周期结束时，同时对累计流量Q进行清理，同时进入下一个定时周期进行流量累计。
将平均瞬时流量F与设定流量F s通过PID算法处理得到输出值，并将此输出值转换成变频器频率信号输出到变频器中，通过控制变频器转速起到控制计量泵流量的作用。
附图说明
图1是本发明***框图；
图1***框图中的序号分别为：1)计量泵，2)变频器，3)氮气输入阀，4)压力传感器，5)氮气输出阀，6)缓冲罐，7)氮气管线，8)流体物料管线，9)流量计，10)控制器
图2是本发明控制器中的控制流程；
具体实施方式
本发明公开了一种可精确控制流量的计量泵控制***，通过以下实施实例并结合图1和图2进行说明。
本实施实例中使用的设备如下：
计量泵，如图1中(1)所示，采用柱塞计量泵，工作流量200L/h，电机采用1.1kw变频电机；
缓冲器，如图1中(6)所示，容量2L；
流量计，如图1中(9)所示，采用电磁流量计，量程400L/h，输出信号4-20ma(4ma对应0L/h，20ma对应400L/h)；
控制器，如图1中(10)所示，采用西门子S7-300控制器，同时安装有一个4-20ma模拟量输入模块和一个4-20ma模拟量输出模块。
变频器，如图1中(2)所示，采用西门子MM440变频器，功率1.5kw。
首先，按照图一进行管路安装，将计量泵的输出接入缓冲罐的输入，缓冲罐的输出接入电磁流量计的输入，在缓冲罐的顶部安装压力表和氮气输入阀以及氮气输出阀。安装电磁流量计时为保证流量稳定，要求流量计上游直管段长度至少应为5倍管径，下游直管段长度至少为3倍管径。工艺管与传感器必须同心，同轴偏差不大于0.05DN。(DN指的是管道的直径)
然后，按照图一进行电气连接，将流量计和压力变送器的输入信号接入控制器的模拟量输入模块，将控制器模拟量输出模块的模拟量信号接入变频器的模拟量输入端子。再将变频器和电机连接。
启动整个***后，先手动开启计量泵，让缓冲罐内储存一定量的物料，要求物料液位高度高于缓冲罐的入口，并且不超过缓冲罐高度的80％。
然后开启氮气输入阀和氮气输入法，调整缓冲罐内压力，同时观察电磁流量计的流量曲线，当流量波动最小时记下此时压力变送器上的压力值，同时关闭氮气的输入阀和输出阀。
控制器中的流量控制方案，将接收到流量计的流量信号进行软件滤波，滤波算法可采用滑动滤波或平均值滤波。通过滤波后的流量信号在定时周期T内进行累计得到累计流量Q，当定时周期结束时，计算平均瞬时流量F＝Q/T。定时周期结束时，同时对累计流量Q进行清理，同时进入下一个定时周期进行流量累计。将平均瞬时流量F与设定流量F s通过PID算法处理得到输出值，并将此输出值转换成变频器频率信号输出到变频器中，通过控制变频器转速起到控制计量泵流量的作用。
控制器同时检测和控制缓冲罐的压力，当控制器检测到罐内氮气压力不足时，通过氮气输入阀补充氮气，当罐内氮气压力过高时，通过氮气输出阀释放氮气。

Claims (5)

  1. 一种可精确控制流量的计量泵控制***，用于计量泵流量控制，包括：
    计量泵，用于输送流体物料并通过转速控制输出流体物料的流量；
    缓冲器，用于对计量泵输出的脉动流量起到削波平波的作用；
    流量计，用于检测输出的瞬时流量，并将流量信号传输到控制器中；
    控制器，用于实时采集流量信号，并对流量信号进行处理，对比设定流量和实际流量，通过软件算法控制变频器的输出；
    变频器，通过接收控制器输出的转速信号，控制计量泵的转速，已达到控制流体流量的目的。
  2. 根据权利要求1所述的可精确控制流量的计量泵控制***，其特征在于，缓冲罐的容量要大于计量泵容量的10倍以上，缓冲罐顶部安装氮气入口阀、氮气出口阀以及一个气体压力变送器，液体物料入口安装在缓冲罐侧面，高度60％-70％左右，出口安装在缓冲器底部，工作时缓冲器内部物料液面高于物料入口并且不超过缓冲罐高度的80％。
  3. 根据权利要求1所述的可精确控制流量的计量泵控制***，其特征在于，控制器接收到流量计的流量信号后，要先进行软件滤波，滤波算法可采用滑动滤波或平均值滤波，通过滤波后的流量信号在定时周期T内进行累计得到累计流量Q，当定时周期结束时，计算平均瞬时流量F＝Q/T，定时周期结束时，同时对累计流量Q进行清零，同时进入下一个定时周期进行流量累计，将平均瞬时流量F与设定流量Fs通过PID算法处理得到输出值，并将此输出值转换成变频器频率信号输出到变频器中，通过控制变频器转速起到控制计量泵流量的作用。
  4. 根据权利要求1所述的可精确控制流量的计量泵控制***，其特征在于，要求流量计上游直管段长度至少应为5倍管径，下游直管段长度至少为3倍管径，工艺管与传感器必须同心，同轴偏差不大 于0.05DN。
  5. 一种可精确控制流量的计量泵流量控制的方法，其使用如权利要求1-4所述的可精确控制流量的计量泵控制***，其特征在于：
    S1：开始；
    S2：读取流量数据；
    S3：对流量数据进行软件滤波处理；
    S4：将累计流量值清零并开启定时器；
    S5：开始计算累计流量；
    S6：判断定时器是否结束，没有结束返回S5，定时器结束继续执行S7并返回S4重新开始计算累计流量；
    S7：将S6得到的累计流量除以定时器定时周期得到平均瞬时流量；
    S8：将S7得到的瞬时流量进行PID处理；
    S9：将PID处理结果转换成变频器转速控制信号，控制变频器转速；
    S10：结束。
PCT/CN2018/116314 2018-11-20 2018-11-20 一种可精确控制流量的计量泵控制*** WO2020102958A1 (zh)

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CN108167169A (zh) * 2018-03-05 2018-06-15 中芳特纤股份有限公司 一种可精确控制流量的计量泵控制***
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Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2352533A (en) * 1999-07-12 2001-01-31 Danfoss As Method for regulating a delivery variable of a pump
DE202009002155U1 (de) * 2009-02-14 2009-05-14 Gea Diessel Gmbh Vorrichtung zur Durchflussregelung
CN103133320A (zh) * 2013-02-25 2013-06-05 长春工业大学 基于转矩角控制的空压机变转速调节方法
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