Undisturbed starting and mixing control switching system for raw material pump set

Abstract

The utility model relates to a raw material pump set undisturbed starting and mixing control switching system which comprises a plurality of raw material tanks, a plurality of variable frequency pumps and a control system, an outlet pipeline of a first raw material tank is respectively connected with a first variable frequency pump and a second variable frequency pump, and an outlet pipeline of a second raw material tank is connected with the second variable frequency pump. Remote stop valves are arranged on pipelines between the two raw material tanks and the connected variable frequency pumps, remote pressure transmitters, check valves and flowmeters are arranged on branch outlet pipelines of the two variable frequency pumps, the two remote pressure transmitters are connected with the differential pressure controller, the two flowmeters are electrically connected with the ratio controller, and the ratio controller is electrically connected with the two variable frequency pumps. Branch outlet pipelines of the two variable frequency pumps are connected with a main outlet pipeline; by means of the control system, one-key switching of undisturbed pump starting and mixed feeding is achieved, using is fast, time and labor cost are saved, safety and reliability are achieved, the failure rate of device operation is reduced, and the automation level is improved.

Description

Technical Field

[0001] The utility model relates to a disturbance-free starting and mixing control switching system for a raw material pump group. Background Art

[0002] At the beginning of a petrochemical plant, raw materials are transported by pipeline from raw material tanks. After the raw material pump group is lifted and operated normally, the subsequent process needs to be mixed and fed, which can be operated by the local PLC control one-key switching system. In the actual operation process, two pumps need to be enabled (for the sake of convenience, they are called pump A and pump B). The amount of raw materials delivered by pump A cannot meet the processing needs of the production unit, and pump B needs to be started to increase the delivery of raw materials. However, due to the excessive back pressure difference, pumps A and B will stop one after another, resulting in the inability of the unit to feed normally and interrupting continuous production. Utility Model Content

[0003] The purpose of the utility model is to provide a disturbance-free starting and mixing control switching system for a raw material pump group to solve the problems raised in the above-mentioned background technology.

[0004] The purpose of this utility model is to adopt the following technical solutions to achieve:

[0005] A disturbance-free starting and mixing control switching system of a raw material pump group proposed by the utility model comprises a plurality of raw material tanks, a plurality of variable frequency pumps, and a control system. The outlet pipeline of the first raw material tank is respectively connected to the first variable frequency pump and the second variable frequency pump, and the outlet pipeline of the second raw material tank is connected to the second variable frequency pump. A remote cut-off valve is arranged on the pipelines between the two raw material tanks and the connected variable frequency pumps, and a remote pressure transmitter, a check valve and a flow meter are arranged on the branch outlet pipelines of the two variable frequency pumps. The two remote pressure transmitters are connected to the differential pressure controller, and the two flow meters are electrically connected to the ratio controller. The branch outlet pipelines of the two variable frequency pumps are connected to the main outlet pipeline, and the main outlet pipeline is connected to the intermediate buffer tank, and a remote pressure transmitter and a pipeline static mixer are arranged on the main outlet pipeline.

[0006] The two variable frequency pumps, three remote cut-off valves, three remote pressure transmitters, two flow meters, a ratio controller and a differential pressure controller are all electrically connected to the control system.

[0007] By means of the above technical solution, the utility model has the following advantages:

[0008] The utility model realizes one-key switching between disturbance-free pump starting and mixed feeding through the control system, which is not only quick to use and saves time and labor costs, but also safe and reliable, reduces the failure rate of device operation and improves the level of automation.

[0009] Furthermore, the outlet pipelines of the two raw material tanks are both provided with manually operated valves.

[0010] Advantages: When the remote shut-off valve fails or is damaged, the manually operated valve can be used to quickly close the pipeline to avoid further losses.

[0011] Furthermore, both variable frequency pumps are positive displacement variable frequency pumps.

[0012] Advantages: The volumetric variable frequency pump is not easy to get clogged during the delivery process, can adapt to a larger working flow, and has stable delivery pressure and smooth operation.

[0013] Furthermore, each of the remote pressure transmitters is also provided with a corresponding local pressure gauge.

[0014] Furthermore, the control system is a PLC control system.

[0015] Advantages: The PLC control system not only has flexible control methods and reliable working methods, but also has fast control speed, simple operation, good reliability and maintainability.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of a disturbance-free starting and mixing control switching system of a raw material pump group of the utility model;

[0018] Figure 2 yes Figure 1 A partial enlarged view of

[0019] Figure 3 The utility model is a schematic diagram of the principle of a ratio controller in a disturbance-free starting and mixing control switching system of a raw material pump group.

[0020] [Reference Signs]

[0021] 101. The first raw material tank; 102. The second raw material tank; 201. The first positive displacement frequency conversion pump; 202. The second positive displacement frequency conversion pump; 301. The first remote pressure transmitter; 302. The second remote pressure transmitter; 303. The third remote pressure transmitter; 401. The first local pressure gauge; 402. The second local pressure gauge; 403. The third local pressure gauge; 501. The first flow meter; 502. The second flow meter; 601. The first remote shut-off valve; 602. The second remote shut-off valve; 603. The third remote shut-off valve; 7. The manually operated valve; 8. The check valve; 9. The pipeline static mixer; 10. The PLC control system; 111. The differential pressure controller; 112. The ratio controller. DETAILED DESCRIPTION

[0022] The features and exemplary embodiments of various aspects of the utility model will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the utility model. However, it is obvious to those skilled in the art that the utility model can be implemented without the need for some of these specific details. The following description of the embodiment is only to provide a better understanding of the utility model by showing an example of the utility model. In the accompanying drawings and the following description, at least part of the known and prior art is not shown to avoid unnecessary ambiguity to the utility model; and, for clarity, the size and shape of the part may be exaggerated. The features or characteristics described below can be combined in one or more embodiments in any suitable manner. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity.

[0023] The utility model provides Figure 1-2 The shown system is a disturbance-free starting and mixing control switching system for a raw material pump group, comprising a first raw material tank 101 and a second raw material tank 102. The outlet pipeline of the first raw material tank 101 is respectively connected to the first volumetric variable frequency pump 201 and the second volumetric variable frequency pump 202, and the outlet pipeline of the second raw material tank 102 is connected to the second volumetric variable frequency pump 202. A remote shut-off valve is provided on the pipelines between the two raw material tanks and the connected variable frequency pumps. A remote pressure transmitter, a check valve 8 and a flow meter are provided on the branch outlet pipelines of the two variable frequency pumps. The two remote pressure transmitters and the two flow meters are electrically connected to the differential pressure controller 111 and the ratio controller 112, respectively. The branch outlet pipelines of the two variable frequency pumps are connected to the main outlet pipeline, the main outlet pipeline is connected to the intermediate buffer tank, and a remote pressure transmitter and a pipeline static mixer 9 are provided on the main outlet pipeline.

[0024] A first remote shut-off valve 601 is provided on the pipeline between the first raw material tank 101 and the first positive displacement variable frequency pump 201, a third remote shut-off valve 603 is provided on the pipeline between the first raw material tank 101 and the second positive displacement variable frequency pump 202, and a second remote shut-off valve 602 is provided on the pipeline between the second raw material tank 102 and the second positive displacement variable frequency pump 202; further, a manual operating valve 7 is provided on the outlet pipelines of the first raw material tank 101 and the second raw material tank 102, which can close the pipeline in time when the remote shut-off valve fails or malfunctions to avoid further losses.

[0025] The first remote pressure transmitter 301 , the second remote pressure transmitter 302 , and the third remote pressure transmitter 303 are respectively equipped with a corresponding first local pressure gauge 401 , a second local pressure gauge 402 , and a third local pressure gauge 403 .

[0026] A first flow meter 501 and a second flow meter 502 are respectively provided on the branch outlet pipelines of the first positive displacement variable frequency pump 201 and the second positive displacement variable frequency pump 202 .

[0027] The first remote pressure transmitter 301 and the second remote pressure transmitter 302 are both electrically connected to the differential pressure controller 111 ; the first flow meter 501 and the second flow meter 502 are both electrically connected to the ratio controller 112 .

[0028] The two variable frequency pumps, three remote shut-off valves, three remote pressure transmitters, two flow meters, a differential pressure controller 111 , and a ratio controller 112 are all electrically connected to the PLC control system 10 .

[0029] The PLC control system 10 presets two working conditions:

[0030] Working condition 1: feeding from the first raw material tank 101 and discharging through the first positive displacement variable frequency pump 201 and the second positive displacement variable frequency pump 202;

[0031] Working condition 2: the first raw material tank 101 and the second raw material tank 102 are mixed and fed, and the materials are discharged through the first positive displacement variable frequency pump 201 and the second positive displacement variable frequency pump 202 .

[0032] The specific operation steps of a raw material pump group non-disturbance starting and mixing control switching system are as follows:

[0033] See also Figure 1-2 In the actual operation of this embodiment, when the first volumetric variable frequency pump 201 cannot meet the processing volume demand of the production device, it is necessary to start the second volumetric variable frequency pump 202 to increase the delivery volume of the raw materials. Because the first volumetric variable frequency pump 201 and the second volumetric variable frequency pump 202 merge into the main outlet pipeline, when the second volumetric variable frequency pump 202 is started at zero pressure, the outlet pressure PT-2B is less than the pressure PT-1 of the discharge pipeline. Due to the excessive back pressure difference, the outlet flow of the second volumetric variable frequency pump 202 is blocked, causing the pipeline vibration to increase, and the motor current of the second volumetric variable frequency pump 202 is overloaded and tripped, thereby causing the first volumetric variable frequency pump 201 and the second volumetric variable frequency pump 202 to stop pumping successively, which is easy to cause mechanical damage to the volumetric variable frequency pump and the instruments on the pipeline, and the device cannot feed normally and interrupts production.

[0034] In order to achieve the smooth operation of the first positive displacement frequency conversion pump 201 and the second positive displacement frequency conversion pump 202, the first remote pressure transmitter 301 and the second remote pressure transmitter 302 are respectively arranged on the branch outlet pipelines of the first positive displacement frequency conversion pump 201 and the second positive displacement frequency conversion pump 202, and the instrument signals of the two remote pressure transmitters are transmitted to the PLC control system 10 and the working condition 1 is executed: the first remote cut-off valve 601 and the third remote cut-off valve 603 are opened, the second remote cut-off valve 602 is closed, and the second remote cut-off valve 602 is closed. At this time, the PLC control system 10 calculates the pressure difference between the first remote pressure transmitter 301 and the second remote pressure transmitter 302 through the differential pressure controller 111, and controls the first positive displacement frequency conversion pump 201 and the second positive displacement frequency conversion pump 202 respectively, and performs frequency conversion speed regulation to reduce the influence of the back pressure difference at the outlets of the two positive displacement frequency conversion pumps and control the working current of the positive displacement frequency conversion pump motor within the allowable range, so as to realize the operation of the first positive displacement frequency conversion pump 201 and the smooth start-up of the second positive displacement frequency conversion pump 202 at the same time.

[0035] See also Figure 1-2 If the subsequent process such as device production requires mixed feed, the PLC control system 10 can be switched to the execution condition 2, first close the third remote shut-off valve 603, then open the first remote shut-off valve 601 and the second remote shut-off valve 602, and the data signals of the first flow meter 501 (FT-1A, active quantity) and the second flow meter 502 (FT-1B, driven quantity) are transmitted to the PLC control system 10. The ratio controller 112 controls the flow rates of the first positive displacement variable frequency pump 201 and the second positive displacement variable frequency pump 202 according to the set proportional coefficient required by the process to achieve the material mixing degree required by the process (active quantity = driven quantity * ratio control coefficient K), and send them to the pipeline static mixer 9 and the intermediate buffer tank to complete further material mixing.

[0036] See also Figure 3 , wherein the flow rate measured by the first flow meter 501 is Q1A (active quantity), and the flow rate measured by the second flow meter 502 is Q1B (driven quantity). According to the proportional coefficient required by the set process, under the action of the ratio controller 112, the PLC control system 10 controls the flow rates of the first positive displacement frequency conversion pump 201 and the second positive displacement frequency conversion pump 202 respectively, so that the value of Q1B changes with the value of Q1A (active quantity = driven quantity * ratio control coefficient K).

[0037] The above is only a preferred embodiment of the present invention. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, makes any simple modifications, equivalent changes and modifications to the above embodiments based on the technical essence of the present invention, which still fall within the scope of the technical solution of the present invention.

Claims

1. A system for undisturbed starting and mixing control switching of a raw material pump group, characterized in that: It includes multiple raw material tanks, multiple variable frequency pumps, and a control system. The outlet pipeline of the first raw material tank is connected to the first variable frequency pump and the second variable frequency pump respectively, and the outlet pipeline of the second raw material tank is connected to the second variable frequency pump. The pipelines between the two raw material tanks and the connected variable frequency pumps are provided with remote cut-off valves. The branch outlet pipelines of the two variable frequency pumps are provided with remote pressure transmitters, check valves and flow meters. The two remote pressure transmitters are connected to the differential pressure controller, and the two flow meters are electrically connected to the ratio controller. The branch outlet pipelines of the two variable frequency pumps are connected to the main outlet pipeline, and the main outlet pipeline is connected to the intermediate buffer tank, and a remote pressure transmitter and a pipeline static mixer are provided on the main outlet pipeline. The two variable frequency pumps, three remote cut-off valves, three remote pressure transmitters, two flow meters, a ratio controller and a differential pressure controller are all electrically connected to the control system.

2. A raw material pump set disturbance-free starting and mixing control switching system according to claim 1, characterized in that: Manually operated valves are provided on the outlet pipelines of the two raw material tanks.

3. A material pump set non-disturbance starting and mixing control switching system according to claim 1, characterized in that: Both variable frequency pumps are positive displacement variable frequency pumps.

4. A material pump set non-disturbance starting and mixing control switching system according to claim 1, characterized in that: Each of the remote pressure transmitters is also provided with a corresponding local pressure gauge.

5. The system for non-disturbance starting and mixing control switching of a raw material pump group according to claim 1 is characterized in that: The control system is a PLC control system.

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