Liquid level control device for main condensation evaporator of air separation device

Abstract

The utility model discloses a liquid level control device for a main condensing evaporator of an air separation device, which particularly relates to the field of gas separation and comprises a main condensing evaporator liquid level detector, a liquid oxygen flow detector and a liquid oxygen storage tank flow control regulating valve which are assembled at the output end of the air separation device. Wherein the output end of the main condensation evaporator liquid level detector is connected with a liquid level PID control module; the output end of the liquid oxygen flow detector is communicated with a flow PID control module, and the input end of the liquid oxygen storage tank flow control regulating valve is connected with a low-selection PID control module. According to the utility model, the stable control of the main cooling liquid level can be realized, the working condition fluctuation of the air separation device caused by the main cooling liquid level fluctuation is reduced, and the problems of long delay time and large liquid level fluctuation of the main cooling liquid level adjustment under the stable and variable load working conditions of the air separation device are solved.

Description

Technical Field

[0001] The utility model relates to the field of gas separation, in particular to a liquid level control device for a main condenser evaporator of an air separation device. Background Art

[0002] Maintaining a relatively stable main refrigerant level is the basis for ensuring the normal operation of the air separation unit and the stable working conditions of the distillation tower. During the actual operation of the unit, due to the large changes in the customer's product structure, including changes in liquid product output and gas product output, the main refrigerant level will have a certain impact. If the main refrigerant level cannot be effectively maintained stable, the fluctuation of the distillation condition will be aggravated, resulting in the deterioration of the operating conditions, and in severe cases, even affecting the purity of the oxygen product. Utility Model Content

[0003] The utility model aims to provide a liquid level control device for a main condenser evaporator of an air separation device, which can effectively control the relative stability of the main cooling liquid level when the operating load of the air separation device changes greatly.

[0004] In order to achieve the above-mentioned purpose, the utility model provides the following technical solutions: a liquid level control device for a main condenser evaporator of an air separation device, comprising a main condenser evaporator liquid level detector, a liquid oxygen flow detector and a liquid oxygen storage tank flow control regulating valve installed at the output end of the air separation device, wherein:

[0005] The output end of the main condenser evaporator liquid level detector is connected to a liquid level PID control module;

[0006] The output end of the liquid oxygen flow detector is connected to a flow PID control module, and the input end of the liquid oxygen to storage tank flow control regulating valve is connected to a low selection PID control module.

[0007] Preferably, the output ends of the flow PID control module and the liquid level PID control module are both connected to the input end of the low selection PID control module.

[0008] Preferably, the flow PID control module in the operating state is always in automatic state, and in this state the low selection module will increase the opening output by 1.5% based on the low selection result as the output upper limit of the flow PID control module and the flow PID control module.

[0009] Preferably, the flow PID control module is configured to automatically switch to an automatic state when the liquid level of the main condenser evaporator liquid level detector is within a certain range, automatically switch to a manual state when it exceeds a certain range, and set the PID module output to 100%.

[0010] Preferably, the liquid level PID control module includes a plurality of different PID parameter groups, and automatically selects the corresponding PID parameter group when the liquid level of the main condenser evaporator liquid level detector is within different ranges.

[0011] Preferably, the flow PID control module is used to control the set value of the low-select PID control module, and is manually input when the expander is running stably, and is automatically calculated according to the expansion gas volume when the expander is running with variable load.

[0012] Preferably, when the flow PID control module controls the set value of the low selection PID control module to be automatically calculated by the expander load, the output of liquid nitrogen and liquid argon needs to be actively subtracted.

[0013] Preferably, the low selected values ​​of the liquid level PID control module and the flow PID control module are used as inputs of the liquid oxygen to storage tank flow control regulating valve;

[0014] It also includes a liquid level PID control module that automatically selects multiple sets of different PID parameters.

[0015] In the above technical scheme, the utility model provides a main condenser evaporator liquid level control device for an air separation unit, which has the following beneficial effects: it is used for stable liquid level control during stable operation and variable load operation of the air separation unit, reducing the drastic fluctuations in operating conditions caused by the process lag of the liquid level corresponding PID adjustment of the main condenser evaporator liquid level detector and the inability of a single liquid level PID control to respond effectively and promptly, and at the same time can effectively curb the oscillation state of the liquid level of the main condenser evaporator liquid level detector caused by simple PID control, thereby ensuring process stability.

[0016] Through the low-selected control mode, when the liquid level of the main condenser evaporator liquid level detector exceeds the allowable range, the liquid level PID control module will dominate the control of the liquid level and liquid oxygen output of the main condenser evaporator liquid level detector, and with the assistance of a suitable PID parameter group, the fast opening or closing of the liquid oxygen to storage tank flow control regulating valve can be achieved to ensure process safety. When the liquid level of the main condenser evaporator liquid level detector fluctuates within a certain allowable range, the flow PID control module will play a leading role, and with the assistance of a suitable PID parameter group, the adjustment speed of the liquid oxygen to storage tank flow control regulating valve can be slowed down to prevent overshoot, so that the fluctuation of the liquid level of the main condenser evaporator liquid level detector tends to converge, and the occurrence of liquid level oscillation of the main condenser evaporator liquid level detector is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present utility model. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0018] Figure 1 Schematic diagram of the implementation structure provided for the embodiment of the utility model

[0019] Description of reference numerals:

[0020] LT160, main condenser evaporator liquid level detector; FT60, liquid oxygen flow detector; LV160, liquid oxygen to storage tank flow control regulating valve; LIC160, liquid level PID control module; MIN160, low selection PID control module; FIC160, flow PID control module. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0022] like Figure 1 As shown, a liquid level control device for a main condenser evaporator of an air separation unit includes a main condenser evaporator liquid level detector LT160, a liquid oxygen flow detector FT60 and a liquid oxygen storage tank flow control regulating valve LV160 installed at the output end of the air separation unit, wherein:

[0023] The output end of the main condenser evaporator liquid level detector LT160 is connected to the liquid level PID control module LIC160;

[0024] The output end of the liquid oxygen flow detector FT60 is connected to a flow PID control module FIC160, and the input end of the liquid oxygen to storage tank flow control regulating valve LV160 is connected to a low selection PID control module MIN160.

[0025] The output ends of the flow PID control module FIC160 and the liquid level PID control module LIC160 in the embodiment are both connected to the input end of the low selection PID control module MIN160.

[0026] Furthermore, the flow PID control module FIC160 in the operating state is always in the automatic state, and in this state the low selection module MIN160 will increase the opening output by 1.5% based on the low selection result as the output upper limit of the flow PID control module FIC160 and the flow PID control module FIC160.

[0027] Secondly, the flow PID control module FIC160 is equipped to automatically switch to the automatic state when the liquid level of the main condenser evaporator liquid level detector LT160 is within a certain range, and automatically switch to the manual state when it exceeds a certain range, and set the PID module output to 100%.

[0028] As an embodiment further provided by the present invention, the liquid level PID control module LIC160 includes a plurality of different PID parameter groups, and automatically selects the corresponding PID parameter group when the liquid level of the main condenser evaporator liquid level detector LT160 is within different ranges. The flow PID control module FIC160 is used to control the set value of the low selection PID control module MIN160, and is manually input when the expander is running stably, and is automatically calculated according to the expansion gas volume when the expander is running with variable load.

[0029] Secondly, when the set value of the flow PID control module FIC160 controls the low selection PID control module MIN160 and is automatically calculated by the expander load, the production of liquid nitrogen and liquid argon needs to be actively subtracted.

[0030] As an embodiment further provided by the present invention, the low selected values ​​of the liquid level PID control module LIC160 and the flow PID control module FIC160 are used as the input of the liquid oxygen to storage tank flow control regulating valve LV160;

[0031] It also includes a liquid level PID control module LIC160 that automatically selects multiple sets of different PID parameters (0%-100%).

[0032] Among the above technologies, the liquid level stability control used during stable operation and variable load operation of the air separation unit reduces the drastic fluctuations in operating conditions caused by the process lag of the PID adjustment corresponding to the liquid level of the main condenser evaporator liquid level detector LT160 and the inability of the single liquid level PID control to respond effectively and promptly. At the same time, it can effectively curb the oscillation state of the liquid level of the main condenser evaporator liquid level detector LT160 The PID control of the oscillation state can ensure process stability.

[0033] Through the low-selected control mode, when the liquid level of the main condenser evaporator liquid level detector LT160 exceeds the allowable range, the liquid level PID control module will dominate the control of the liquid level and liquid oxygen output of the main condenser evaporator liquid level detector LT160, and with the assistance of a suitable PID parameter group, the liquid oxygen to storage tank flow control regulating valve can be quickly opened or closed to ensure process safety. When the liquid level of the main condenser evaporator liquid level detector LT160 fluctuates within a certain allowable range, the flow PID control module will play a leading role, and with the assistance of a suitable PID parameter group, the adjustment speed of the liquid oxygen to storage tank flow control regulating valve can be slowed down to prevent overshoot, so that the fluctuation of the liquid level of the main condenser evaporator liquid level detector LT160 tends to converge, and the occurrence of liquid level oscillation of the main condenser evaporator liquid level detector LT160 is reduced.

[0034] Working principle:

[0035] In the low-select control mode, when the liquid level of the main condenser evaporator liquid level detector LT160 exceeds the allowable range, the liquid level PID control module LIC160 will dominate the control of the liquid level of the main condenser evaporator liquid level detector LT160 and the liquid oxygen output, assisted by a suitable PID parameter group to control the fast opening or closing of the liquid oxygen to storage tank flow control regulating valve LV160.

[0036] When the liquid level of the main condenser evaporator liquid level detector LT160 fluctuates within a certain allowable range, the liquid level PID control module LIC160 will play a leading role. Assisted by a suitable PID parameter group, it can slow down the adjustment speed of the liquid-liquid oxygen to storage tank flow control valve LV160 to prevent overshoot, so that the fluctuation of the liquid level of the main condenser evaporator liquid level detector LT160 tends to converge and reduce the liquid level oscillation of the main condenser evaporator liquid level detector LT160.

[0037] The above only describes some exemplary embodiments of the present invention by way of illustration. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A liquid level control device for a main condenser evaporator of an air separation unit, characterized in that: It includes a main condenser evaporator liquid level detector (LT160), a liquid oxygen flow detector (FT60) and a liquid oxygen storage tank flow control regulating valve (LV160) installed at the output end of the air separation unit, wherein: The output end of the main condenser evaporator liquid level detector (LT160) is connected to a liquid level PID control module (LIC160); The output end of the liquid oxygen flow detector (FT60) is connected to a flow PID control module (FIC160), and the input end of the liquid oxygen de-storage tank flow control regulating valve (LV160) is connected to a low selection PID control module (MIN160).

2. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: The output ends of the flow PID control module (FIC160) and the liquid level PID control module (LIC160) are both connected to the input end of the low selection PID control module (MIN160).

3. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: The flow PID control module (FIC160) in the running state is always in the automatic state, and in this state the low selection PID control module (MIN160) will increase the opening output by 1.5% based on the low selection result as the output upper limit of the flow PID control module (FIC160) and the flow PID control module (FIC160).

4. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: The flow PID control module (FIC160) is configured to automatically switch to an automatic state when the liquid level of the main condenser evaporator liquid level detector (LT160) is within a certain range, automatically switch to a manual state when it exceeds a certain range, and set the PID module output to 100%.

5. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: The liquid level PID control module (LIC160) includes a plurality of different PID parameter groups, and automatically selects a corresponding PID parameter group when the liquid level of the main condenser evaporator liquid level detector (LT160) is within different ranges.

6. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: The flow PID control module (FIC160) is used to control the set value of the low selection PID control module (MIN160), and is manually input when the expander is running stably, and is automatically calculated according to the expansion gas volume when the expander is running with variable load.

7. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: When the flow PID control module (FIC160) controls the set value of the low selection PID control module (MIN160) to be automatically calculated by the expander load, the output of liquid nitrogen and liquid argon needs to be actively subtracted.

8. The liquid level control device for the main condenser evaporator of an air separation unit according to claim 1, characterized in that: The low selected values ​​of the liquid level PID control module (LIC160) and the flow PID control module (FIC160) are used as inputs of the liquid oxygen de-storage tank flow control regulating valve (LV160); Also included is a level PID control module (LIC160) that automatically selects multiple sets of different PID parameters.

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