A method of space division initiation

Abstract

The embodiment of the application discloses a kind of air separation starting methods, when checking that the state of air separation system related equipment meets automatic starting condition before starting, trigger one-button starting button action to start air separation system related equipment according to the control timing determined by preset strategy.The embodiment of the application completes a series of complex actions from starting to output product by one-button starting air separation, and the effect is better in efficiency and precision.

Description

TECHNICAL FIELD

[0001] The present application relates to air separation technology, and in particular to an air separation starting method. BACKGROUND

[0002] Air separation device (ASU) is an industrial equipment which separates each component gas in air by using the different boiling points of each component in air to produce oxygen, nitrogen and other gases. Figure 1 A typical ASU system structure is shown, and its basic working process is as follows: raw material air (AIR) is filtered to remove dust and mechanical impurities in the air through a self-cleaning air filter AF1001, and then enters an air compressor AC1001 through a pipeline for compression. The compressed air enters a pre-cooling unit RU1101 for washing and cooling. The cooled air enters a purification system (consisting of adsorbers MS1201A and MS1201B, an electric heater EH1201, etc.) for purification. After adsorbing water, carbon dioxide and most of the hydrocarbons in the air, the air is divided into two parts. A small part is used as instrument air and seal gas (SEAL GAS), and the other part enters a cold box F101 (consisting of a main heat exchanger E1, a lower column C1, a main condenser evaporator K1, an upper column C2, a subcooler E2, etc.). The cold energy generated by a turbine type expander unit (consisting of expanders ET4101 and ET4101, aftercoolers WC401 and WC451, etc.) is used to liquefy part of the air, and then the liquefied air is further rectified. The separated oxygen (GOX) and nitrogen (GN) are sent to users after leaving the cold box F101, and the waste nitrogen is used as a regeneration gas for the purification system.

[0003] The above-mentioned air separation system relates to various control objects such as instruments, valves, motors and the like, which need to act according to the set timing when starting, and generally uses a pure manual control mode or a semi-automatic control mode for starting. The pure manual control mode is completed by multiple operators according to the on-site display instrument, and the equipment investment cost is low, and the disadvantages are that: multiple people are needed to participate in the commissioning at the time of starting, the labor cost is high; the operation accuracy and precision are determined by the level of the operator, and there are too many uncontrollable factors; the level of the operator directly affects the equipment starting time, causing unnecessary energy loss; in the system starting, the on-site operator needs to manually confirm the single machine starting condition before the next operation, increasing the on-site operator commissioning risk. The semi-automatic control mode of various instruments, valves, motor control and the like is completed by the distributed control system (DCS), and the operator can complete the operation of the entire device in the control room through the computer, and only 2-3 people are needed to participate in the commissioning, the labor cost is reduced, and the equipment action accuracy and precision are improved, and the disadvantages are that: the equipment starting time cannot be avoided due to the level of the operator, causing energy waste; the operator needs to confirm the single machine starting condition on site during starting, and cannot avoid the risk of on-site operator. In view of the deficiencies of the existing air separation starting method, it is necessary to optimize the design. SUMMARY

[0004] In view of the deficiencies of the prior art, the embodiments of the present application aim to solve the above technical problems and propose a high-efficiency and precise air separation starting method.

[0005] To solve the above technical problems, the technical solutions of the embodiments of the present application are as follows:

[0006] An air separation starting method, comprising the following steps:

[0007] checking the state of the related equipment of the air separation system before starting;

[0008] judging whether the state of the related equipment of the air separation system before starting meets the automatic starting condition;

[0009] if yes, triggering the one-key starting button action;

[0010] and starting the related equipment of the air separation system according to the control timing determined according to the preset strategy.

[0011] Preferably, when the state of the cooling water, electricity, instrument gas and the like of the air separation system before starting meets the automatic starting condition, the purification starting button is pressed to sequentially start the purification system, the cold box system and the expander to output the product.

[0012] Preferably, the purification system performs the actions of air compressor start-up, air compressor pressure setting, air compressor loading and purification system valve opening in sequence when one of the adsorbers is ready, the cold box inlet valve is closed and the air compressor is ready.

[0013] Preferably, the action relationship of the purification system valve is that the purification system valve opening-time curve comprises four increasing line segments, wherein the first segment slope > the third segment slope > the fourth segment slope > the second segment slope.

[0014] Preferably, the cold box system performs the action of cold box inlet valve gradual opening when the main cold liquid level, air inlet lower column temperature, air inlet cold box CO2 purity and air inlet cold box dew point meet the set conditions.

[0015] Preferably, the action relationship of the cold box system valve is that the cold box system valve opening-time curve comprises three increasing line segments, wherein the third segment slope > the first segment slope > the second segment slope.

[0016] Preferably, the expander performs the actions of expander inlet valve opening and expander guide vane gradual opening in sequence when the lower column pressure is normal, the expander has no alarm and the expander return valve is fully open.

[0017] Preferably, the action relationship of the expander inlet valve is that the expander inlet valve opening-time curve comprises six segments, wherein the first segment, the third segment and the fifth segment are increasing line segments, and the first segment slope > the third segment slope > the fifth segment slope; the second segment, the fourth segment and the sixth segment are respectively holding line segments with a slope of 0.

[0018] Preferably, the action relationship of the expander guide vane is that the expander guide vane opening is proportional to the expander speed.

[0019] Preferably, when the product purity is qualified, the product delivery valve is gradually slowly opened and the product vent valve is gradually closed while ensuring that the product pressure and flow are within the allowable variation range, until the product vent valve flow is closed and the product delivery valve opening remains unchanged when the pressure remains unchanged.

[0020] Compared with the prior art, the air separation start-up method of the embodiment of the present application can complete a series of complex actions from start-up to product output by one-key start-up, and does not require the participation of an operator in the start-up process, and has high operation efficiency and precision. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a typical air separation system structure diagram;

[0022] Figure 2 is a flowchart of the air separation start-up method of the embodiment of the present application;

[0023] Figure 3 is a schematic diagram of the air separation system start-up preparation condition of the embodiment of the present application;

[0024] Figure 4 The one-key start condition diagram of the air separation system of the embodiment of the present application;

[0025] Figure 5 The related equipment start sequence diagram of the air separation system of the embodiment of the present application;

[0026] Figure 6 The valve opening-time curve diagram of the valve of the air separation purification system of the embodiment of the present application;

[0027] Figure 7 The valve opening-time curve diagram of the air separation cold box inlet valve of the embodiment of the present application;

[0028] Figure 8 The valve opening-time curve diagram of the air separation expander inlet valve of the embodiment of the present application;

[0029] Figure 9 The architecture diagram of the air separation start method of the embodiment of the present application;

[0030] Figure 10 The software example diagram of the air separation start method of the embodiment of the present application;

[0031] Figures 11-1 to 11-10 The control timing diagram of the air separation start method of the embodiment of the present application, in which the sequence is connected between the front and rear diagrams.

[0032] In the above drawings, the related reference signs are described as follows:

[0033] AF1001-filter; AC1001-air compressor; RU1001-precooler; MS1201A / MS1201B-molecular sieve adsorber; EH1201-electric heater; SL1201-polluted nitrogen venting silencer; ET401 / ET402-expander; AF2001-expander fan end filter E1-main heat exchanger; E2-subcooler; C1-lower column; K1-main condenser evaporator; C2-upper column; WC401 / WC451-aftercooler; SL401-oxygen silencer; OC1401A / OC1401B-oxygen compressor; LV101-residual liquid leaf evaporator; ST1401 / ST1402-oxygen buffer tank; BT401-nitrogen buffer tank; SE301-liquid nitrogen tank; Wi-water inlet; Wo-water outlet; AIR-air; GOX-oxygen; GN-nitrogen; SEAL GAS-sealing gas.

[0034] In the above drawings, the related variable and parameter meanings are described as follows:

[0035] PT5001 - cooling water pipe pressure; PT2001 - instrument air pressure; KV1201 / KV1203 - adsorber A inlet and outlet valve; KV1202 / KV1204 - adsorber B inlet and outlet valve;

[0036] HV101 - cold box inlet valve;

[0037] HV1213 - purification system valve;

[0038] RS_1001 - air compressor allowed to start;

[0039] HO_1001 - air compressor start;

[0040] SP_1001 - air compressor outlet pressure;

[0041] SO_1001 - air compressor outlet; PT2003 - expander A outlet pressure; PT2004 - expander B outlet pressure;

[0042] HN1215 - purification system valve;

[0043] SV1202 - dew point meter status;

[0044] HC1213.MODE - purification system valve working mode; DHC1213.SV - purification system valve target opening; DHC1213.MV - purification system valve opening per minute;

[0045] FI1201.PV - dirty nitrogen flow setting; PCV1212.PV - dirty nitrogen pressure setting;

[0046] PPU SEQ START - purification system sequence control start;

[0047] PIO101.MODE - valve PID working mode; PCV1212.MODE - dirty nitrogen valve working mode; FICAS1201.SV - dirty nitrogen flow PID setting value; PICA1212.SV - dirty nitrogen pressure PID setting value;

[0048] SP1001.MODE - air compressor pressure setting mode; SP1001.SV - air compressor pressure setting value; SP1001.RP - air compressor pressure setting per minute increase value;

[0049] SV1201.2 - purification system solenoid valve 2#; SV1201.3 - purification system solenoid valve 3#; SV1201.3 - purification system solenoid valve 1#.

[0050] Cold box Auto Start - cold box start;

[0051] AL1201.PV - Air CO2 purity after purification; AL1202.PV - Air CO2 dew point after purification; ZSL101 - Chiller inlet valve closed;

[0052] HV101.MV - Chiller inlet valve valve opening;

[0053] PI1 - Lower column pressure; PT101 - Chiller inlet pressure;

[0054] HV101.MV - Chiller inlet valve valve opening; PCV105B.SV - Nitrogen send-out valve valve opening; FCV102B.SV - Oxygen send-out valve valve opening;

[0055] HV1215.MV - Purification system valve opening;

[0056] HV401A.MV - Expander A# inlet valve opening; HV401B.MV - Expander B# inlet valve opening;

[0057] ST401A - Expander A# speed; ST401B - Expander B# speed;

[0058] LI1 - Lower column level;

[0059] LCV1 - Lower column valve; LCV1.SP - Lower column valve opening setpoint; LCV1.PV - Lower column valve opening setpoint;

[0060] TIME.SET - Time set;

[0061] LCV1.SP - Lower column valve opening setpoint; LCV1.MODE - Lower column valve mode of operation;

[0062] PI1 - Lower column pressure;

[0063] HV2.MV - Upper column valve opening;

[0064] PDI1 - Lower column resistance;

[0065] ASV-5 - Trace nitrogen analyzer;

[0066] AI5 - Nitrogen product purity;

[0067] FCV105A.SV - Nitrogen product flow setpoint;

[0068] PDI2 - Upper column resistance;

[0069] ASV-2 - Trace oxygen analyzer;

[0070] AI102 - Oxygen product purity;

[0071] FCV102A.SV - oxygen product flow set point;

[0072] AI102 - oxygen product purity; AI103 - oxygen product dew point; AI105 - nitrogen product purity; AI106 - nitrogen product dew point;

[0073] HV102C.MV - oxygen vent valve opening; HV105C.MV - nitrogen vent valve opening. DETAILED DESCRIPTION

[0074] The application will be described in further detail below with reference to the drawings and specific embodiments, but this should not be understood as limiting the scope of protection of the application to only the embodiments described below.

[0075] Referring to Figure 2 , is a flow chart of the air separation system start-up method of the embodiment of the application. It mainly includes the following steps:

[0076] S010, check the status of the air separation system related equipment before start-up.

[0077] S020, determine whether the status of the air separation system related equipment before start-up meets the automatic start-up condition, if yes, go to step S030; if no, go to step S050.

[0078] S030, trigger the one-key start button action;

[0079] S040, start the air separation system related equipment according to the control time sequence determined by the preset strategy.

[0080] S050, alarm and prohibit start-up.

[0081] The embodiment uses the one-key start sequence control method to start the air separation system, and before start-up, it needs to check whether each condition meets the requirements, such as the detection status and parameters of the cooling water, electricity, instrument air, etc. After meeting the requirements, the air separation system is started by one key, otherwise, the air separation system start-up can be prohibited after alarm. If an emergency occurs during the one-key start process, it can be paused at any time to avoid accidents.

[0082] Referring to Figure 3 , Figure 4 , wherein: Figure 3 is a schematic diagram of the air separation system preparation start-up condition of the embodiment of the application; Figure 4 is a schematic diagram of the one-key start condition of the air separation system of the embodiment of the application. The specific condition before start-up is that before starting the air separation system, it needs to check whether each condition (such as the cooling water, electricity, instrument air, etc.) meets the requirements, and only when the requirements are met, the air separation system can be started by one key. For example, Figure 3As shown in the figure, when the cooling water pipe pressure (PT5001> 0.35Mpa, which is the detected value on the circulating water main pipe), the instrument air pressure (PT2001> 0.45Mpa, which is the detected value on the instrument air main pipe) and the electrical conditions meet the requirements at the same time, the preparation for starting can be prepared; if Figure 4 As shown in the figure, when the preparation for automatic conditions is met and the purification system automatic start button is pressed, the one-key automatic start of air separation is started.

[0083] Referring to Figure 5 , it is a schematic diagram of the starting sequence of the air separation system related equipment of the embodiment of the present application. The embodiment adopts a one-key starting sequence control method based on the SFC program architecture and the SEBOL language: first, a one-key start button action, then a purification system start, followed by a cold box system start, then an expander start, and finally product output, until the starting program ends.

[0084] Specifically, when the cooling water, electricity, instrument air state of the air separation system before starting is checked and judged to meet the automatic starting conditions, the purification start button is pressed to sequentially start the purification system, the cold box system and the expander to output the product, and if an emergency is encountered during the one-key starting process, it can be paused at any time.

[0085] Referring to Figure 6 , Figure 7 and Figure 8 , wherein: Figure 6 is a valve opening-time curve diagram of the air separation purification system valve of the embodiment of the present application; Figure 7 is a valve opening-time curve diagram of the air separation into cold box valve of the embodiment of the present application; Figure 8 is a valve opening-time curve diagram of the air separation expander inlet valve of the embodiment of the present application, wherein the target opening of each valve and the valve opening speed please refer to the specific numerical values in FIG. 11. According to Figures 6-8 As shown in the figure, the valve opening-time curves of the main valves in each link during the air separation starting process are composed of multiple line segments, which is beneficial to make the equipment starting more smooth, and can avoid damage caused by impact.

[0086] The starting conditions and actions of each main link during the air separation starting process will be further described below in combination with Figures 5-8 .

[0087] I. Purification system start

[0088] 1. Conditions:

[0089] (1) The adsorber A or B is ready - KV1201 and KV1203 are opened or KV1202 and KV1204 are opened;

[0090] (2) The cold box inlet valve HV101 is closed;

[0091] (3) Air compressor is ready - Instrument air pressure is normal and start cabinet is ready.

[0092] 2. Action:

[0093] (1) Air compressor is started;

[0094] (2) Air compressor pressure is set;

[0095] (3) Air compressor is loaded;

[0096] (4) Purification system valve HV1213 is slowly opened;

[0097] Here, the specific action relationship of the purification system valve HV1213 is that the valve opening-time curve of the purification system includes four increasing line segments, wherein the first segment slope > third segment slope > fourth segment slope > second segment slope, as shown in Figure 6 , wherein the valve opening and valve opening time of each stage can be set open.

[0098] II. Cold box system start

[0099] 1. Condition:

[0100] (1) The lower tower liquid level LT1 <100MM;

[0101] (2) The main cold liquid level LT2 <100MM;

[0102] (3) The air into the lower tower temperature TI1>-50℃;

[0103] (4) The air into the cold box CO2 purity <1PPM;

[0104] (5) The air into the cold box dew point <-65℃.

[0105] 2. Action:

[0106] The cold box valve HV101 is slowly opened.

[0107] Here, the action relationship of the cold box valve HV101 is that the valve opening-time curve of the cold box system includes three increasing line segments, wherein the third segment slope > first segment slope > second segment slope, as shown in Figure 7 , wherein the valve opening and valve opening time of each stage can be set open.

[0108] III. Expander start

[0109] 1. Condition:

[0110] (1) The lower tower pressure PT1 is normal;

[0111] (2) The expander has no alarm;

[0112] (3) The expansion machine backflow valve is fully opened.

[0113] 2. Action:

[0114] (1) The expansion machine inlet valve is opened.

[0115] (2) The expansion machine guide vane is slowly opened.

[0116] Here, the action relationship of the expansion machine inlet valve is that the expansion machine inlet valve opening-time curve includes six segments, the first segment, the third segment and the fifth segment are increasing line segments, and the first segment slope > the third segment slope > the fifth segment slope, the second segment, the fourth segment and the sixth segment are respectively holding line segments with a slope of 0, as shown in the following table: Figure 8 Wherein the valve opening and valve opening time of each stage can be set; at the same time, the opening of the expansion machine guide vane is proportional to the speed of the expansion machine, and the speed-time of the expansion machine can also be set according to multiple line segments.

[0117] Four, product output

[0118] 1. Condition:

[0119] The product purity is qualified, such as the purity of oxygen, nitrogen and argon.

[0120] 2. Action:

[0121] While ensuring that the pressure and flow of the product are within the allowable variation range, the product delivery valve is slowly opened and the product vent valve is slowly closed until the vent valve is closed, the flow and pressure remain unchanged, and the product delivery valve opening remains unchanged.

[0122] Referring to Figure 9 , Figure 10 , wherein: Figure 9 is the air separation starting method architecture diagram of the embodiment of the application; Figure 10 is the software example diagram of the air separation starting method of the embodiment of the application. The embodiment of the application adopts a one-key starting sequence control (SFC) architecture, a hardware configurable workstation desktop computer and a win10 operating system, and a software configurable Yokogawa CENTUM VP DCS system.

[0123] Taking the Yokogawa software as an example, each step can be completed by using the SEBOL language, the software structure is good, and after the parameter table is configured and initialized, the corresponding action steps such as STEP1, STEP2, …, and STEP8 can be sequentially called and executed, wherein each step has a corresponding condition judgment to determine whether it can continue to proceed under the premise of ensuring the safety of the equipment. The whole program automatically runs without human intervention until the qualified product is produced.

[0124] Referring to Figures 11-1 to 11-10, the sequence of the front and rear figures is connected, such as the node 1-1 in Figure 11-2 is connected to the node 1-1 in Figure 11-1 , such as the node 2-1 in Figure 11-3 is connected to the node 2-1 in Figure 11-2 , and so on. The meanings of the parameters in these figures are as described above, and the preferred values of the parameters are as listed in the figures and will not be repeated here.

[0125] As shown in Figure 11-1 , after the purification start button is pressed to start in step S101, steps S102-S113 are executed, which include air compressor start, air compressor pressure setting, air compressor loading, slow opening of the purification system valve, and the like, until the purification system is started in sequence control. In step S105, the outlet pressures of the expander A and the expander B are required to be greater than 0.55 MPa, respectively.

[0126] As shown in Figure 11-2 , when the purification system is started, steps 201-205 are mainly executed, which set the PID working mode and parameters of the related valves, and cause the cold box system to start gas intake under certain conditions.

[0127] As shown in Figure 11-3 , when the cold box system is started, steps S301-S305 are mainly executed, which include adjusting the cold box valve opening degree, and also need to set the opening degrees of the oxygen and nitrogen product control valves.

[0128] As shown in Figure 11-4 , Figure 11-5 , after steps S401 and S402 are executed when the expander is started, step S403 is executed to select the start of the expander A or the expander B: if the expander A is selected to start, steps S404A-S504A are executed; otherwise, if the expander B is selected, steps S404B-S504B are executed. Regardless of whether the expander A or the expander B is started, the opening degree of the corresponding expander inlet valve is gradually opened according to the set curve, and the expander speed is also gradually increased.

[0129] As shown in Figures 11-6 to 11-10 , after steps S601-S904 are executed in sequence, the product is output by pressing the product output button in step S904, which is specifically outputting the oxygen product by steps S1001A-S1002A and outputting the nitrogen product by steps S1001B-S1002B.

[0130] The above Figures 11-1 to 11-10The parameter combination of the steps is optimized, which helps to ensure that the product preparation efficiency and purity reach a satisfactory effect. Of course, according to different equipment structures, the parameters need to be changed to a certain extent, and details are not repeated.

[0131] The air separation starting method of the embodiment of the application is described in detail above, which adopts one-key starting of air separation, and has the advantages that an operator does not need to participate, a series of complex actions from starting to product output are completed by the DCS system by pressing a starting button; the operation precision is high, the problem of extending the equipment starting time due to the level of the operator is avoided, and energy waste is avoided; the operator does not need to approach a dangerous source during starting, the debugging danger of the operator is reduced; and considerable economic benefits can be generated in two aspects of manpower and energy consumption. In the case that the automation degree is required to be higher and higher, and the manpower cost and energy consumption are required to be lower and lower, the one-key automatic starting of air separation of the embodiment of the application is very necessary, which can greatly reduce the manpower cost and energy consumption.

[0132] Although the application is disclosed with the preferred embodiment as above, it is not intended to limit the application, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the application, so the protection scope of the application should be defined by the scope defined by the claims of the application.

Claims

1. A space separation startup method, characterized in that, Includes the following steps: Check the status of relevant equipment in the air separation system before startup; Determine whether the status of relevant equipment in the air separation system meets the automatic startup conditions before startup; If so, trigger the one-click start button action; And, start the relevant equipment of the air separation system according to the control sequence determined by the preset strategy; Before starting, check and determine that the cooling water, electricity, and instrument gas status of the air separation system meet the automatic start conditions, then press the purification start button to start the purification system, cold box system, and expander in sequence to output products. When one of the adsorbers is ready, the cold box valve is closed, and the air compressor is ready, the purification system sequentially performs the actions of air compressor start-up, air compressor pressure setting, air compressor loading, and purification system valve opening. The action relationship of the purification system valves is as follows: the purification system valve opening-time curve includes four increasing line segments, where the slope of the first segment > the slope of the third segment > the slope of the fourth segment > the slope of the second segment. When the main cooling liquid level, air inlet temperature, air inlet CO2 purity, and air inlet dew point meet the set conditions, the cold box system will gradually open the cold box valves. The valve action relationship of the cold box system is as follows: the valve opening degree-time curve of the cold box system includes three increasing line segments, where the slope of the third segment > the slope of the first segment > the slope of the second segment. When the expansioner is operating at normal pressure in the lower tower, without any alarms, and with the expansioner reflux valve fully open, it sequentially performs the actions of opening the expansioner inlet valve and gradually opening the expansioner guide vanes. The expansioner inlet valve's action relationship is as follows: the expansioner inlet valve opening-time curve consists of six segments, of which the first, third, and fifth segments are increasing segments, and the slope of the first segment > the slope of the third segment > the slope of the fifth segment; the second, fourth, and sixth segments are holding segments with a slope of 0. The expansioner guide vane's action relationship is as follows: the expansioner guide vane opening is directly proportional to the expansioner speed.

2. The space separation startup method as described in claim 1, characterized in that, When the product purity is qualified, while ensuring that the product pressure and process are within the allowable range of variation, the product delivery valve is gradually opened slowly and the product vent valve is gradually closed until the product vent valve is completely closed and the flow rate and pressure remain constant, and the opening of the product delivery valve also remains constant.

Images