JPH0221282B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the invention] Industrial application field The present invention relates to a method for starting operation of a distillation plant in petroleum refining, petrochemical, chemical industry, seawater desalination, etc. This article relates to a method for automatically starting operation using computer sequence control. Conventional technology Conventionally, in these distillation plants, as in the case of other types of plants such as reaction process plants, on-site workers start or stop operations based on instructions from the integrated chamber for each operation unit. Operates valves, cocks, and/or start/stop switches attached to equipment. However, as the scale of plants has increased in recent years, such on-site work has become increasingly difficult. On the other hand, recently, due to the slump in the mass-produced materials industry, there has been a particularly strong demand for cost reductions in plant operations, and it has become necessary to operate plants at minimum costs and with extremely limited personnel. Furthermore, in countries that possess raw materials and energy resources such as oil and natural gas, and developing countries, exports of unprocessed energy resources such as crude oil and natural gas,
The construction and start-up of oil refining, natural gas, petrochemical plants, etc., for the purpose of exporting products and satisfying domestic demand is increasing. In these energy resource-possessing countries and developing countries, due to rapid industrialization policies, the training of operating engineers in the equipment industry is unable to keep up with demand. In comparison, it has become extremely difficult to secure personnel for plant operations, especially at the start of operations, and the current situation is that plants rely on the support of engineers from developed countries. Problems to be Solved by the Invention The present invention has been made in view of the above situation, and improves the method for starting operation of various plants including distillation processes, so that operations can be started automatically without requiring much manpower. The purpose is to provide a method to do so. [Structure of the Invention] Means for Solving the Problems The above object can be achieved by the method of the present invention described below. The automatic operation starting method of the present invention is characterized by comprising the following steps (a) to (e). (a) Close the discharge flow control valve of the pump attached to the distillation plant, start the pump, and after the pump discharge pressure rises, adjust the control valve to the minimum flow rate, and after a predetermined period of time, adjust the control valve opening. (b) adjusting the flow rate of at least the bottom liquid pump discharge piping of the distillation column bottom liquid sent to the distillation column by the pump according to the column internal pressure or liquid head pressure; After filling up to the valve and detecting this with the bottom liquid level gauge, the bottom liquid pump is automatically started. (c) Liquid replacement in the raw material liquid supply system and bottom liquid extraction system of the distillation column. and/or automatically starting the ignition temperature increase of the distillation column heating furnace after achieving intra-plant fluid circulation; (d) predetermining a measured value of the distillation column heating furnace outlet fluid or distillation column plate temperature; The temperature difference between the two is calculated by comparing the target temperature with the target temperature every time, and the flow rate of the fuel supplied to the heating furnace is increased or decreased based on a preset value corresponding to the temperature difference, and this operation is repeated. a step of raising the temperature of the distillation column heating furnace to a predetermined temperature; (e) the liquid level of the top liquid, side stream distillate, side line reflux liquid, or bottom liquid distilled by raising the temperature of the distillation column heating furnace; Or when the temperature is detected and the liquid level or temperature reaches a preset liquid level height or upper limit temperature,
The process of automatically starting each extraction pump and transitioning to steady operation. By sequentially passing through the steps (a) to (e) above, automatic operation of the plant can be started smoothly. Also, following steps (a) to (e), the following (f) and (g)
Step (f) After the transition to steady operation, an upper limit value is set in advance for the temperature of the side stream distillate of the distillation column or the distillation column plate, and when this upper limit is reached, the temperature of the side stream distillate is (g) after reducing the amount of side stream distillate withdrawn;
By operating according to a step of automatically adjusting the flow rate of the distillation column feedstock liquid, each fraction extracted from the distillation column, the column top reflux or the side line reflux based on a preset value or increase/decrease rate, Steady operation can be continued automatically. Furthermore, when starting the pump attached to the distillation column in step (a), (h) detecting the empty state of the pump from the current value of the pump drive motor, and throttling or restricting the discharge flow rate control valve of the pump for a certain period of time; (i) Stop the pump by checking the liquid level in the suction side of the column or automatically switch to a standby pump to avoid dry pumping, or The operation of the pump can be quickly and safely shifted to a steady state. In addition, in step (e) above, when detecting the liquid level in the part that does not have a liquid level gauge, (j) Check the liquid level of the top liquid, side stream distillate, or side line reflux liquid of the distillation column at each extraction pump. It is simple and reliable to detect the pressure on the suction side. EXAMPLES Next, the present invention will be specifically described with reference to the drawings. An example will be described in which automatic operation is started using a distributed control system having a sequence control function in a crude oil atmospheric distillation apparatus having a processing capacity of 50,000 B/D as shown in FIG. In the present invention, the start of automatic operation refers to predetermined preparatory work before starting continuous operation, including removing oxygen from the equipment, draining water, replenishing lubricating oil to pumps and rotating machines, checking the opening and closing of all piping and equipment valves, and So-called operations such as checking the operating system of instruments, preparing the supply and receiving system for raw materials and product tanks, preparing the supply system for electricity, steam, water, air, etc., and preparing the receiving system for flue gas, waste water, and off-gas processing equipment. Refers to the process of completing start-up preparation work and then automatically proceeding with the start-up process of the distillation equipment according to the sequence control program, allowing normal operation to proceed without any operator intervention. There is. Depending on how the sequence control program is created, it is of course possible to temporarily stop the program at any stage during the start of automatic operation, or to stop the operation and return the work process to any stage. In this example, we will explain from the oxygen expulsion inside the equipment and the introduction of raw materials, but in a distillation equipment or a plant including a distillation equipment, continuous operation is temporarily stopped due to equipment failure repair or production planning reasons. The present invention can also be suitably applied to the case of a later start of operation. Furthermore, using each method shown in the present invention, it is also possible to automatically stop operation of a distillation apparatus or a plant including a distillation apparatus, automatically switch the type of raw material, change the amount of raw material processed, etc. First, after completing the equipment assembly, open inspection, repair, and cleaning of the crude oil atmospheric distillation equipment, and before starting plant operation, the oxygen in the equipment is expelled with an inert gas such as steam or nitrogen, and Fill with gas. In this embodiment, the inert gas sealing pressure is approximately 2.5 Kg/cm ² G in the front distillation column system, with the discharge side flow rate control valve 25 of the bottom oil pump 22 as the boundary, and the pressure in the main distillation column 5. Maintain the strain at 0.2-0.3 Kg/cm ² G. Next, the valve 11 of the pipe leading from the crude oil tank 1 to the crude oil pump 13 and the suction valve 12 and discharge valve 14 of the crude oil pump 13 are opened, and the crude oil pump 13 is degassed using the liquid head pressure of the crude oil. pump 1
Prepare to start step 3. In addition, all gate valves such as control valves and remote control valves that are activated during operation will be opened. The above operation preparation work is performed manually, but it can also be performed by remote automatic operation. Thereafter, a sequence control program created in advance using an instruction code method (command method) is started to enter the continuous process of starting automatic operation. (Starting the crude oil pump) First, the crude oil pump 13 is started using the method of step (a), that is, with the pump discharge valve 14 open and the discharge side flow control valve 16 closed, and the pump discharge side pressure is sufficiently increased. The flow rate control valve 16 is closed for about 10 seconds, and then the maximum flow rate during normal operation is
Open the valve to a preset opening of about 15% of 330K/hr (approximately 50K/hr) and hold for 15 seconds. Check the indicated value of the flow meter 15 for 15 seconds, and if there is no flow or the current value of the drive motor of the crude oil pump 13 is equivalent to the pump dry operation, proceed to step (h). Flow control valve 1
6 to stop the pump and restart the sequence control program from the beginning. If the flow meter 15 is checked and the predetermined flow rate is coming out, the opening degree of the flow control valve 16 is increased based on a predetermined flow rate increase/decrease rate to approximately 200 K/hr, and the piping inside the device is sequentially adjusted. 17, heat exchanger 18, 1
Crude oil is introduced into the desalination tank 9 (not shown) and the pre-refiner tower 2,
The liquid level is displayed on the liquid level gauge 27 at the bottom of the front distillation column. At the same time, the crude oil pump discharge pipe 17 is also connected to the main distillation column 5.
Crude oil is introduced via a branch pipe (not shown) from the column, and the liquid level is indicated at the liquid level gauge 54 at the bottom of the column. The crude oil stored at the bottom of the main distillation column is sent to the bottom oil system such as the bottom oil pump 51 and heat exchangers 52 and 53 using liquid head pressure. Depending on the method, the gas in the system will be replaced and the gas will be automatically vented. (Start-up of bottom oil pump) Next, when the indication of the liquid level gauge 27 at the bottom of the fore-stream column reaches 90%, the crude oil pump 13 is stopped, and the column of the fore-stream column 2 is stopped by the method of step (b). The discharge side flow rate control valve 25 of the bottom oil pump 22 is opened, and the crude oil stored at the bottom of the front distillation tower is pumped through the bottom oil pump 22, piping 24, Transfer to heating furnace 3. The nitrogen gas that existed in these equipment piping before the introduction of crude oil is replaced with crude oil and pushed into the main distillation column 5, and the crude oil is replaced from the crude oil pump 13 to the rising heating pipe 31 at the entrance of the heating furnace 3. Degassing takes place. To determine whether the crude oil has been filled up to the discharge side flow rate control valve 25 of the bottom oil pump 22 of the front distillation tower 2,
This is done by comparing the rate of drop in the liquid level of the front distillation column bottom liquid level gauge 27 and the system internal volume up to the discharge side flow rate control valve 25. In this embodiment, the time required for the reading on the liquid level gauge 27 at the bottom of the pre-distillation tower to drop from 90% to 50% is measured, and after a time lapse of five times the measured time, or
Considering the control valve liquid leakage before opening the discharge side flow rate control valve 25, after opening the discharge side flow rate control valve 25.
After 420 seconds have elapsed, it is determined that the flow rate control valve 25 has been filled with crude oil, and the process moves to the next sequence program. In addition, since the height of the heating furnace heating tube is high above ground,
Although it is possible to completely replace the inside of the heating furnace tube with crude oil by increasing the nitrogen gas pressure in the pre-distillation column, it is also possible to start the pre-distillation column bottom oil pump 22 according to the method described later, and to increase the heating furnace heating. It is preferable to replace the gas in the pipe with crude oil and send the crude oil to the main distillation column 5. In other words, if the crude oil pump 13 is restarted and the reading on the front distillation tower bottom liquid level gauge 27 reaches 50%, step (b)
The front distillation column bottom oil pump 22 is started according to the method described in the following. The procedure is almost the same as starting the crude oil pump 13, and the front distillation tower bottom oil pump 2 is started by the method of step (a).
The second discharge gate valve 23 is opened, the discharge side flow rate control valve 25 is closed, and the bottom oil pump 22 is automatically started. The flow rate control valve 25 is kept closed for about 10 seconds while the discharge side pressure increases, and then opened to a preset valve opening that is about 15% of the maximum flow rate during normal operation, and held for 15 seconds. Check the indication of the flowmeter 26 for 15 seconds, and if there is no flow or the ammeter indication of the drive motor of the bottom oil pump 22 is a value equivalent to the preset pump dry operation, The bottom oil pump 22 is stopped, the crude oil pump 13 is stopped, and the sequence program for starting the operation is restarted from the beginning. If the flow rate of the bottom oil pump 22 is measured within the above 15 seconds, the automatic flow rate control valve 25 in each pass of the heating furnace is operated to adjust the flow rate of crude oil charged into the main distillation column via the heating furnace. Set the pass to 50K/hr. Next, the indication on the main distillation column bottom liquid level gauge 54 is 50%.
When this is reached, the main distillation column bottom oil pump 51 is started according to the method of the previous application (Japanese Patent Application No. 58-143584), and the pre-distillation column 2 and main distillation column 5 systems are replaced with feedstock oil and the crude oil is replaced. A circulating flow of crude oil from tank 1 to crude oil tank 8 or slop oil tank 8' via crude oil atmospheric distillation apparatus is established. If the main distillation column bottom oil pump 51 cannot be started, the operation start sequence program is re-executed from the beginning in the same way as in the case of the front distillation column bottom oil pump 22. (Ignition of the heating furnace) Based on the step (c) above, after measuring and logically checking the operating status of the pump, the flow rate in the crude oil circulation system, the opening/closing status of the valves in the piping system, the pressure in each system, etc. , gas burner 3 of main distillation column heating furnace 3
Two of the two burner main valves 33 are automatically opened by remote control, and are ignited by the spark of a pilot burner (not shown) that has been ignited in advance, thereby starting to raise the temperature of the heating furnace 3. At this time, the opening degree of the fuel gas flow rate control valve 34 is the minimum flow rate value of the fuel gas, that is, the total calorific value.
Approximately 600Nm ³ / for 8000Kcal / Nm ³ fuel gas
Set in advance to be hr. After igniting the two gas burners, switch the amount of fuel gas supplied to automatic flow rate control (FIC). Next, the base point temperature of the temperature increase is measured and incorporated into the sequence controller program, and the target temperature after 4 minutes is calculated and stored. After 4 minutes have passed, detect the temperature of the heating furnace outlet fluid,
The difference between the measured temperature and the target temperature is calculated by comparing the temperature with the target temperature, and the flow rate of the fuel gas supplied to the heating furnace is increased or decreased based on a preset value corresponding to the difference between the measured temperature and the target temperature. For example, if the planned heating rate is set to 80℃ per hour,
The fuel gas flow rate is increased or decreased according to the following classifications. (1) When the currently measured temperature of the heating furnace outlet fluid is 6°C or more higher than the target temperature...Reduce the fuel gas amount by 50Nm ³ /hr. (2) When the measured temperature as above is 3°C or more and less than 6°C higher than the target temperature and higher than the previous measured temperature... Increase the flow rate as above by 30Nm ³ /hr. (3) When the measured temperature as above is 3°C or more and less than 6°C higher than the target temperature and lower than the previous measured temperature... Increase the flow rate as above by 50Nm ³ /hr. (4) When the measured temperature as above is higher than the target temperature by 0℃ or more and less than 3℃, and the temperature increase gradient (hereinafter simply referred to as temperature increase gradient) with respect to the previously measured temperature is greater than the planned temperature increase gradient...the flow rate as above. Increases by 70Nm ³ /hr. (5) When the measured temperature as above is higher than the target temperature by 0°C or more and less than 3°C, and the temperature increase gradient is less than the planned temperature rise gradient and higher than the previous measured temperature... Increase the flow rate as above by 100Nm ³ /hr. (6) When the measured temperature as above is 0°C or more and less than 3°C higher than the target temperature and lower than the previous measured temperature... Increase the flow rate as above by 130Nm ³ /hr. (7) The measured temperature as above is 3℃ or more lower than the target temperature,
And when the temperature increase gradient is more than twice the planned temperature increase gradient... Increase the flow rate as above by 100Nm ³ /hr. (8) The measured temperature as above is 3℃ or more lower than the target temperature,
And when the temperature increase gradient is less than twice the planned temperature increase gradient... Increase the flow rate as above by 150Nm ³ /hr. (9) When the measured temperature as above is 0°C or more and less than 3°C lower than the target temperature, and the temperature increase gradient is more than twice the planned temperature rise gradient... Increase the flow rate as above by 70Nm ³ /hr. (10) When the measured temperature as above is 0°C or more and less than 3°C lower than the target temperature, and the temperature increase gradient is 1 time or more and less than 2 times the planned temperature rise gradient... Increase the flow rate as above by 100Nm ³ /hr. Detects the above heating furnace outlet fluid temperature, compares it with the target temperature, calculates the difference between the two, and increases or decreases the flow rate of the fuel supplied to the heating furnace based on a preset value corresponding to the difference between the measured temperature and the target temperature. This operation is repeated every 4 minutes according to the program of the sequence controller. In addition, when increasing the temperature of the heating furnace 3, the temperature increase rate,
The measurement interval of the heating furnace fluid outlet temperature, the increase/decrease cycle of the amount of supplied fuel gas corresponding to the temperature difference, etc. can be freely set depending on the type and scale of the distillation plant. 4 minutes after increasing or decreasing the fuel gas flow rate, measure the fuel gas flow rate and check that it is 1200Nm ³ /hr or more.
If it is less than 1800Nm ³ /hr, gas burner 32
The two main valves 33 of the gas burners are opened to increase the number of burners to four, and when it is 1800Nm ³ /hr or more, the main valves of two gas burners are further opened to increase the number of burners to six. By this method, the temperature of the fluid at the outlet of the heating furnace is increased, and when it reaches a preset temperature, for example, 330°C, the automatic temperature controller (TRC) of the fluid at the outlet of the heating furnace is activated.
and fuel gas automatic flow controller (FIC) to cascade control, and transition to normal operation control method. FIG. 2 is an example of a temperature rise curve when the temperature of the furnace outlet fluid is raised according to the present invention, where the dotted line represents the target temperature gradient and the solid line represents the temperature rise result. The above is a case where the temperature of the fluid at the outlet of the heating furnace is increased by the method of step (d) of the present invention. When manually correcting the set value of the meter, as shown by the solid line in FIG. 3, the temperature cannot be raised quickly and accurately, so extra time is required for the temperature raising process. (Removal of distillate oil) On the other hand, as the temperature of the fluid at the outlet of the heating furnace rises, the temperature of the main distillation column also rises, and the crude oil from the crude oil tank is also heated by the main distillation column bottom oil heat exchanger, etc. As a result, the temperature of the former column also rises. In the pre-distillation column and the main distillation column, as the temperature inside the column increases, the top distillate oil is distilled out, and in the main distillation column, distillation of the side distillate oil begins. The overhead distillate oil is condensed in the overhead oil condensers 45 and 75 and accumulated in the overhead oil receiving tanks 4 and 7. The method of starting the main distillation column top oil pump 71 and the pre-distillation column top oil pump 41 to start column top reflux and extracting the top oil as a product follows the steps (e) and (g) above. That is, when the tower top temperature reaches the reference temperature or the liquid level in the tower top oil receiving tanks 4, 7 reaches 50% or more, the discharge side flow rate control valves 42,
72 is closed, the pump is automatically started, and after 10 seconds, the control valve opening is set to the minimum flow rate (15).
Hold the column for 2 seconds, and if the flow starts, set the column top temperature to [reference temperature - 10℃] and set the column top temperature controller (TRC) 28,
56 and overhead oil reflux flow controller (FRC)
42 and 72 are transferred to cascade control. The reference temperature can be arbitrarily selected depending on the properties of the crude oil and the operation start-up process, but as an example, it is 100 to 110°C at the top of the front distillation column and 80 to 90°C at the top of the main distillation column. If a flow rate does not come out even after starting the pump, avoid running the pump dry using the methods in steps (h) and (i) above, automatically switch to a standby pump, or automatically stop the pump and wait. Return to state and repeat this. After starting the tower top oil reflux using the method described above, the liquid level gauges 44 and 74 of the tower top oil receiving tanks 4 and 7 are indicated.
If it exceeds 50%, the automatic liquid level controllers 43, 73 are activated to start extracting the product top oil. As the temperature of the main distillation column 5 rises, the main distillation column side distillate oil enters the side distillate oil stripper 6, the liquid level at the bottom of the stripper rises, and the bottom liquid level gauges indicate 64, 64', 6.
4″ etc. reaches the set value, the side stream distillate oil pump 6
1, 61', 61'', etc., to start extracting product oil, and heat exchangers 62, 62'..., 63,
It is taken out through 63'... The method for starting and stopping the side distillate oil pump 61 and the like is the same as in the case of the above-mentioned bottom oil pump, tower oil reflux or tower oil extraction pump. The side line reflux oil pump 57 of the main distillation column may be automatically started and stopped in response to a level gauge instruction (not shown) on the main distillation column side line reflux oil tray, but based on step (j) above, From the suction side liquid head pressure calculated by comparing the suction side pressure gauge indication 58 of the pump 57 and the internal pressure 55 of the main distillation column, the liquid level level in the income side piping or the liquid level level in the side line reflux oil tray of the main distillation column is detected. By doing so, the method of automatically starting and stopping the pump is advantageous in that it does not require major modifications to existing equipment. In addition, when switching the operation of the high temperature fluid pump used in this example, it is necessary to change the operation of the high temperature fluid pump used in this example.
143583) is suitable. With the above steps, the process from feeding crude oil into the crude oil atmospheric distillation unit to raising the temperature of the heating furnace, extracting the top oil and side stream distillate oil, and circulating the side line reflux oil has been completed, and normal operation has begun. let (Normal operation) When transitioning to normal operation, upper limits are set in advance for the temperature of the side distillate oil extraction tray in the main distillation column by the method of step (f) above due to the necessity of quality control. If the upper limit value and the tray temperature have a margin, the amount of side-stream distillate oil to be extracted is automatically reduced by a sequence program, and if the upper limit value and the tray temperature have a margin, a plan determined in advance in step (g) is applied. Sidestream distillate oil is withdrawn based on yield. For example, the upper limit temperature of ^the extraction tray for light oil fraction is 262
℃ to satisfy the standard of JIS No. 1 kerosene 95% distillation temperature of 270℃ or less according to the JIS K2254 fuel oil distillation test method. The extraction tray temperature of
If the temperature exceeds 262℃, the rate of change in the amount of withdrawal is determined in advance by the same process (g), that is, in 30 seconds.
The yield change is effected by automatically reducing the withdrawal of the kerosene fraction at a rate of 0.2-0.3 k/hr. The rate of change when increasing the amount of extraction is also similar to this. In addition, a lower limit value is set for the stripper column bottom liquid level of side stream distillate oil or side line reflux oil, the indication of the main distillation column extraction tray liquid level gauge, or the extraction pump suction side liquid head pressure, and when the lower limit value is reached. Continuation of operation takes place by automatically reducing the respective withdrawal or circulation volume to, for example, 90% of the previous flow rate. In addition, when transitioning to normal operation, steam is blown into the bottom of the main distillation column and the bottom of the stripper column in order to improve the distillation properties of each product and increase the efficiency of distillation, but this work is also sequence controlled. It is possible to rely on programs to automate and generate necessary messages. In other words, the steam source for blowing into the bottom of the tower
Saturated low-pressure steam of 1.3 to 1.4 kg/cm ² G was passed through the heating tube of the convection section of the heating furnace (not shown) in advance, and when the crude oil temperature at the exit of the heating furnace reached 280°C, the bottom of the main distillation column and each After automatically draining the condensed water in the steam pipe (not shown) leading to the bottom of the stripper column, the injection of the required amount of superheated steam can be automatically started. When operating crude oil atmospheric distillation equipment, we use various online process analyzers, offline analysis devices, and Control the process with a flash monitor, calculate the dew point at the top of the main distillation column at regular intervals, and control the top temperature, pressure, and stripping steam injection amount to keep it outside the dew point range. Furthermore, in order to continuously and quickly monitor and detect the hue of the light oil fraction and control the amount of light oil distillate extracted, etc., a color monitor according to Japanese Patent Application Laid-Open No. 58-179342 has been used. The technique described above can be suitably applied in carrying out the present invention. Comparing the embodiments of the present invention with the prior art, it is found that the start-up time is greatly shortened, and at the same time, the amount of feedstock oil used during the start-up process is reduced, and so-called slop oil that requires re-refining is reduced. This not only reduces the amount of fuel generated, but also saves on the amount of fuel and other utilities consumed during this time.

[Table] Additionally, during the start-up process, after starting the sequence control program, it can be operated by a very small number of operators, which is very useful when trying to centrally control various plants with a small number of people. This can be said to be an effective method. Above, specific examples have been described for each step of steps (a) to (j) belonging to the present invention. [Effects of the Invention] From the above explanation, it will be easily understood that it is possible to automatically start operation of a crude oil atmospheric distillation apparatus using sequence control instrumentation. Sequence control methods to which the method of the present invention can be applied include a relay sequence method, a method using a centralized control computer system, a method using a distributed control system having a sequence control function, etc., and any method can be applied. , a distributed control system having a sequence control function can be suitably used. Sequence description methods include relay symbol method, theoretical symbol method, flow chart method, instruction code method (command method), time chart method, decision table method, etc., and any method can be used. be.

[Brief explanation of drawings]

Fig. 1 is a flow sheet of an atmospheric distillation apparatus used to explain the present invention, Fig. 2 is a graph showing the process of increasing the temperature of the fluid at the outlet of the heating furnace according to the present invention, and Fig. 3 is the temperature of the fluid at the outlet of the heating furnace according to the conventional method. It is a graph showing the temperature increase process. 1,8... Crude oil tank, 2... Pre-reterator, 3...
Heating furnace, 4, 7... Top oil receiver tank, 5... Main distillation column, 6... Stripper, 8'... Slop tank.

Claims (1)

[Scope of Claims] 1. A method for starting automatic operation of a distillation plant by sequence control, which comprises the following steps (a) to (e). (a) Close the discharge flow control valve of the pump attached to the distillation plant, start the pump, and after the pump discharge pressure rises, adjust the control valve to the minimum flow rate, and after a predetermined period of time, adjust the control valve opening. (b) adjusting the flow rate of at least the bottom liquid pump discharge piping of the distillation column bottom liquid sent to the distillation column by the pump according to the column internal pressure or liquid head pressure; After filling up to the valve and detecting this with the bottom liquid level gauge, the bottom liquid pump is automatically started. (c) Liquid replacement in the raw material liquid supply system and bottom liquid extraction system of the distillation column. and/or automatically starting the ignition temperature increase of the distillation column heating furnace after achieving intra-plant fluid circulation; (d) predetermining a measured value of the distillation column heating furnace outlet fluid or distillation column plate temperature; The temperature difference between the two is calculated by comparing the target temperature with the target temperature every time, and the flow rate of the fuel supplied to the heating furnace is increased or decreased based on a preset value corresponding to the temperature difference, and this operation is repeated. a step of raising the temperature of the distillation column heating furnace to a predetermined temperature; (e) the liquid level of the top liquid, side stream distillate, side line reflux liquid, or bottom liquid distilled by raising the temperature of the distillation column heating furnace; Or when the temperature is detected and the liquid level or temperature reaches a preset liquid level height or upper limit temperature,
The process of automatically starting each extraction pump and transitioning to steady operation. 2. A patent that, when starting a pump attached to the distillation plant, detects whether the pump is running dry based on the current value of the pump drive motor and restricts or closes the discharge flow control valve of the pump for a certain period of time to avoid running dry. A method for starting automatic operation according to claim 1. 3. The method for starting automatic operation according to claim 2, wherein, when starting the pump, the pump is checked against the liquid level of the suction side towers and tanks, and is stopped or automatically switched to a standby pump. 4. The method for starting automatic operation according to claim 1, wherein the liquid level of the top liquid, side stream distillate, or side line reflux liquid of the distillation column is detected by the suction side pressure of each extraction pump. 5. A method for starting automatic operation of a distillation plant by sequence control, comprising the following steps (a) to (g). (a) Close the discharge flow control valve of the pump attached to the distillation plant, start the pump, and after the pump discharge pressure rises, adjust the control valve to the minimum flow rate, and after a predetermined period of time, adjust the control valve opening. (b) adjusting the flow rate of at least the bottom liquid pump discharge piping of the distillation column bottom liquid sent to the distillation column by the pump according to the column internal pressure or liquid head pressure; After filling up to the valve and detecting this with the bottom liquid level gauge, the bottom liquid pump is automatically started. (c) Liquid replacement in the raw material liquid supply system and bottom liquid extraction system of the distillation column. and/or automatically starting the ignition temperature increase of the distillation column heating furnace after achieving intra-plant fluid circulation; (d) predetermining a measured value of the distillation column heating furnace outlet fluid or distillation column plate temperature; The temperature difference between the two is calculated by comparing the target temperature with the target temperature every time, and the flow rate of the fuel supplied to the heating furnace is increased or decreased based on a preset value corresponding to the temperature difference, and this operation is repeated. a step of raising the temperature of the distillation column heating furnace to a predetermined temperature; (e) the liquid level of the top liquid, side stream distillate, side line reflux liquid, or bottom liquid distilled by raising the temperature of the distillation column heating furnace; Or when the temperature is detected and the liquid level or temperature reaches a preset liquid level height or upper limit temperature,
The process of automatically starting each extraction pump and transitioning to steady operation. (f) After the transition to steady-state operation, an upper limit value is set in advance for the temperature of the side stream distillate of the distillation column or the distillation column plate, and when this upper limit is reached, the amount of side stream distillate to be withdrawn is reduced. (g) after reducing the withdrawal amount of said sidestream distillate;
A process of automatically adjusting the flow rate of the distillation column feedstock liquid, each fraction extracted from the distillation column, column top reflux, or side line reflux based on a preset value or rate of increase/decrease. 6. A patent for avoiding dry pumping by detecting the pump's emptying from the current value of the pump drive motor and throttling or closing the pump's discharge flow control valve for a certain period of time when starting the pump attached to the distillation plant. The method for starting automatic operation according to claim 5. 7. The method for starting automatic operation according to claim 6, wherein when starting the pump, the pump is stopped by checking the liquid level of the suction side towers and tanks, or the pump is automatically switched to a standby pump. 8. The method for starting automatic operation according to claim 5, wherein the liquid level of the top liquid, side stream distillate, or side line reflux liquid of the distillation column is detected by the suction side pressure of each extraction pump.