CN220381495U - Evaporation two-effect liquid level control system - Google Patents
Evaporation two-effect liquid level control system Download PDFInfo
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- CN220381495U CN220381495U CN202322231126.7U CN202322231126U CN220381495U CN 220381495 U CN220381495 U CN 220381495U CN 202322231126 U CN202322231126 U CN 202322231126U CN 220381495 U CN220381495 U CN 220381495U
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- evaporation
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- 239000007788 liquid Substances 0.000 title claims abstract description 61
- 238000001704 evaporation Methods 0.000 title claims abstract description 27
- 230000008020 evaporation Effects 0.000 title claims abstract description 26
- 230000001105 regulatory effect Effects 0.000 claims abstract description 31
- 230000000694 effects Effects 0.000 claims abstract description 13
- 230000005284 excitation Effects 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims 1
- 238000002161 passivation Methods 0.000 abstract description 7
- 230000008859 change Effects 0.000 abstract description 5
- 238000000034 method Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 4
- 238000004537 pulping Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000004836 empirical method Methods 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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- Control Of Non-Electrical Variables (AREA)
Abstract
The utility model discloses an evaporation two-effect liquid level control system, which comprises a regulating valve, a liquid level transmitter and a flowmeter which are respectively and electrically connected with a DCS control system, wherein the liquid level transmitter is arranged on an evaporation two-effect tank body, the evaporation two-effect tank body is connected with a first effect through a conveying pipe provided with a conveying pump, and the regulating valve and the flowmeter are sequentially arranged on the conveying pipe; the DCS control system comprises a main controller and a secondary controller, the liquid level transmitter is electrically connected with the main controller, the main controller is connected with the secondary controller and outputs instructions to the main controller, the flowmeter is electrically connected with the secondary controller, and the secondary controller is electrically connected with the regulating valve and outputs instructions to the secondary controller. The utility model adopts a flow-liquid level cascade control mode, overcomes the fluctuation of the second-effect liquid level and the fluctuation of the second-effect outlet flow caused by the disturbance quantity generated by a passivation system or the change of the system load, and improves the stability of the second-effect liquid level control.
Description
Technical Field
The utility model belongs to the technical field of paper pulping and cooking, and particularly relates to an evaporation two-effect liquid level control system.
Background
The method comprises the steps of (1) evaporating and concentrating dilute black liquor with the solid content of 16.5% from a pulping workshop digestion section in a six-effect nine-body tube type falling film evaporator to produce concentrated black liquor with the solid content of 71%, and delivering the concentrated black liquor to a combustion section for combustion; heavy-sewage condensed water generated by a pulping workshop and an evaporation workshop is stripped to generate medium-sewage condensed water for production. In the evaporation system, the black liquor from the third effect is sent into the passivation system by an independent outlet pump, is sent into the second effect after four-stage preheating and flash evaporation, and is sent into the first-effect tetrad after the second effect is evaporated. The advantages and disadvantages of the liquid level control of the evaporation double effect directly affect the control of the subsequent first effect quadruple, the liquid level of the evaporation double effect is affected by the circulating passivation system, once the circulating passivation system fluctuates, the liquid level of the double effect is difficult to control, and great fluctuation is caused.
The original liquid level control mode of evaporation two-effect adopts single loop liquid level control, namely, the control of the two-effect liquid level is controlled by a control valve of an outlet pump, and when the liquid level measured value is larger than a liquid level set value required to be controlled by the process, the two-effect liquid level is reduced by opening a large outlet control valve. Therefore, the disturbance quantity or the change of the system load generated by the passivation system causes the fluctuation of the two-effect liquid level, the control of the regulating valve after the two-effect pump causes control hysteresis, and simultaneously causes the fluctuation of the two-effect flow, thereby affecting the liquid level control of the one-effect four-body.
Disclosure of Invention
The utility model aims to provide an evaporation two-effect liquid level control system, which adopts a flow-liquid level cascade control mode, overcomes the fluctuation of the two-effect liquid level and the fluctuation of the two-effect outlet flow caused by the disturbance quantity or the change of the system load generated by a passivation system, and improves the stability of the two-effect liquid level control.
The technical scheme adopted by the utility model is that the evaporation two-effect liquid level control system comprises a regulating valve, a liquid level transmitter and a flowmeter which are respectively and electrically connected with a DCS control system, wherein the liquid level transmitter is arranged on an evaporation two-effect tank body, the evaporation two-effect tank body is connected with a first effect through a conveying pipe provided with a conveying pump, and the regulating valve and the flowmeter are sequentially arranged on the conveying pipe.
Preferably, the DCS control system comprises a main controller and a sub-controller, the liquid level transmitter is electrically connected with the main controller, the main controller is connected with the sub-controller, the flow meter is electrically connected with the sub-controller, and the sub-controller is electrically connected with the regulating valve, and outputs instructions to the sub-controller.
Preferably, the DCS control system adopts an EPKS R300 control system.
Preferably, the regulating valve adopts a pneumatic V-shaped regulating ball valve, the flowmeter adopts a double-frequency excitation electromagnetic flowmeter, and the liquid level transmitter adopts a double-flange liquid level transmitter.
The evaporation two-effect liquid level control mode adopts flow-liquid level cascade control, namely, a two-effect liquid level control loop is used as a main regulating loop, flow control is used as an auxiliary regulating loop, liquid level is measured by the main device, flow is measured by the auxiliary device, and output of the liquid level regulating loop is used as a given value of the flow regulating loop. Therefore, the liquid level control loop is a constant value control system, and the flow control loop is a follow-up control system, when the disturbance quantity generated by the passivation system or the change of the system load causes the two-effect liquid level to fluctuate, the flow control loop can play a regulating role before the disturbance quantity affects the flow change, so that the flow regulating system controls the two-effect liquid level to fluctuate in advance. Compared with the prior art, the following beneficial effects are achieved:
1) The disturbance entering the auxiliary regulating loop can be overcome early, the control characteristic of the whole control process can be improved, the auxiliary controlled variable detects the influence of the disturbance, the control variable is timely regulated through the constant value effect of the auxiliary regulating loop, the auxiliary controlled variable is returned to the auxiliary set value, the influence of the disturbance on the main controlled variable is reduced, namely the auxiliary loop rough-adjusts the disturbance, and the main loop fine-adjusts the disturbance, so that the cascade control system can quickly overcome the influence of the disturbance entering the auxiliary loop, and the system residual error is greatly reduced, and the whole control quality is further improved;
2) The phase lag of the auxiliary measuring object is obviously reduced due to the existence of the auxiliary regulating loop, so that the response speed of the main regulating loop is improved, and the running stability of the whole system is improved;
3) The influence of the gain variation of the secondary measuring object is overcome in advance inside the secondary regulating loop;
4) Under the condition of the same damping ratio, the working frequency of the cascade control system is higher than that of the single-loop control system, the working frequency of the system is improved, and the transition process is shortened, so that the control quality is improved;
5) The auxiliary regulating loop can be precisely controlled according to the requirement of the main regulating loop, so that the control quality of the whole control system is improved.
Drawings
FIG. 1 is a schematic diagram of the structure of the present utility model;
FIG. 2 is a diagram of a control system according to the present utility model.
Detailed Description
The utility model will be further explained in conjunction with the drawings of the specification so as to be better understood by those skilled in the art.
As shown in fig. 1-2, the evaporative two-effect liquid level control system comprises a DCS control system 1, a regulating valve 2, a liquid level transmitter 3 and a flowmeter 4.
In this embodiment, the DCS control system 1 adopts the EPKS R300 control system of Honeywell corporation, the regulating valve 2 adopts the RAA series pneumatic V-type regulating ball valve of the metafile, the liquid level transmitter 3 adopts the EJA118 series double flange liquid level transmitter of the cross river instrument, and the flowmeter 4 adopts the double frequency excitation electromagnetic flowmeter of the Shanghai cross river AXG series.
The liquid level transmitter 3 is arranged on the evaporation two-effect tank 5 and is electrically connected with the DCS control system 1, the evaporation two-effect tank 5 is connected with the one-effect tank through a conveying pipe 6 provided with a conveying pump, and the regulating valve 2 and the flowmeter 4 are sequentially arranged on the conveying pipe 6 and are respectively electrically connected with the DCS control system 1.
The DCS control system 1 comprises a main controller 11 and a secondary controller 12, the liquid level transmitter 3 is electrically connected with the main controller 11, the main controller 11 is connected with the secondary controller 12 and outputs instructions to the main controller, the flowmeter 4 is electrically connected with the secondary controller 12, and the secondary controller 12 is electrically connected with the regulating valve 2 and outputs instructions to the secondary controller.
The utility model designs the evaporation two-effect liquid level control as cascade control, and takes the flow in the cascade control system as an auxiliary variable and takes the flow control as an auxiliary control loop; the liquid level is used as a main variable, and the liquid level control is used as a main control loop. The PID parameter setting is carried out on the main control loop and the auxiliary control loop on line by monitoring the on-line operation of the cascade control system, and the parameter setting method of the single loop system controller is independently carried out according to the principle from inside to outside by using an empirical method. Because the auxiliary control loop plays a rough adjustment process, under the condition that the main control loop and the auxiliary control loop are closed-loop control, the proportion and integral of the auxiliary control loop are preset, then the main control loop is set according to a general single-loop control mode, the main control loop is debugged according to the principle of proportion and integral, and whether the control curve accords with 4: 1, if not satisfied, continuing to make proper adjustments to the proportional and integral of the main control loop, and if necessary, properly adding a certain differential until the control curve is satisfied.
Through optimizing the evaporation two-effect liquid level control, the liquid level and the outlet flow of the evaporation two-effect liquid level are stable, the evaporation two-effect liquid level control can be controlled quickly under the condition of interference, and the process control of one-effect four bodies is ensured, so that the whole production device can continuously and stably operate for a long period, and excellent economic and social benefits are brought to companies.
The above embodiments are only for illustrating the technical solution of the present utility model and not for limiting the same, and although the present utility model has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present utility model, which is intended to be covered by the claims of the present utility model.
Claims (4)
1. The utility model provides a two effect liquid level control system of evaporation, includes governing valve (2), liquid level changer (3) and flowmeter (4) that are connected with DCS control system (1) electricity respectively, its characterized in that, liquid level changer (3) are installed on two effect jar body (5) of evaporation, and two effect jar body (5) of evaporation are connected one through conveyer pipe (6) that install the delivery pump and are effective, and governing valve (2) and flowmeter (4) are installed on conveyer pipe (6) in proper order.
2. The evaporative two-way liquid level control system according to claim 1, wherein the DCS control system (1) comprises a main controller (11) and a sub-controller (12), the liquid level transmitter (3) is electrically connected with the main controller (11), the main controller (11) is connected with the sub-controller (12) to output instructions thereto, the flowmeter (4) is electrically connected with the sub-controller (12), and the sub-controller (12) is electrically connected with the regulating valve (2) to output instructions thereto.
3. The evaporative two-way liquid level control system of claim 1, wherein the DCS control system (1) employs an EPKS R300 control system.
4. The evaporative two-way liquid level control system of claim 1, wherein the regulating valve (2) is a pneumatic V-shaped regulating ball valve, the flowmeter (4) is a double-frequency excitation electromagnetic flowmeter, and the liquid level transmitter (3) is a double-flange liquid level transmitter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322231126.7U CN220381495U (en) | 2023-08-18 | 2023-08-18 | Evaporation two-effect liquid level control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322231126.7U CN220381495U (en) | 2023-08-18 | 2023-08-18 | Evaporation two-effect liquid level control system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220381495U true CN220381495U (en) | 2024-01-23 |
Family
ID=89561193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322231126.7U Active CN220381495U (en) | 2023-08-18 | 2023-08-18 | Evaporation two-effect liquid level control system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220381495U (en) |
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2023
- 2023-08-18 CN CN202322231126.7U patent/CN220381495U/en active Active
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