Device for controlling coal ethylene glycol rectification by APC system

Abstract

The utility model belongs to the technical field of coal ethylene glycol rectification, and particularly relates to a device for controlling coal ethylene glycol rectification by an APC (automatic process control) system, which comprises a methanol recovery tower device, a dehydrating tower device, a dealcoholization tower device, a product tower device and a recovery tower device which are sequentially connected according to a process sequence, the methanol recovery tower device, the dehydration tower device, the dealcoholization tower device, the product tower device and the recovery tower device respectively comprise a rectifying tower, a reboiler, a condensation cooling device and a pump, and the coal ethylene glycol rectification system is coupled with the APC system, so that the operation of the ethylene glycol rectification system is optimized and controlled, the load of the reboiler and the power consumption of a condenser are reduced, and the energy consumption of the product tower device is reduced. The energy waste is reduced, the automation of the rectification control process is improved, the labor intensity and the operation error of frequent operation of operators are reduced, and meanwhile, the product quality change caused by operation fluctuation is reduced. The utility model also has strong working condition adaptability, and the APC system can adapt to different working condition changes.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of coal -to -glycol rectification, specifically an APC system control coal -to -glycol rectification device. BACKGROUND

[0002] In the production process of coal -to -glycol, rectification procedure is core unit operation, mainly including methanol recovery tower, dehydration tower, dealcoholization tower, product tower and recovery tower etc. The operation of each tower directly influences the purity and energy consumption of glycol product. At present, coal -to -glycol rectification control system is distributed control system (abbreviation DCS), mainly for conventional single loop PID and manual remote operation, and most of PID loop is still manual operation, and single factor is contained in part of automatic loop, and there are problems such as too big fluctuation when controlling, and the correlation of single loop PID control is not high enough, and the automatic control degree is not perfect, and manual operation is more, and the control precision is low, and when loading or unloading, the whole device fluctuates frequently, for example: the control of parameters such as temperature, steam flow, liquid level and pressure is unstable. When temperature, steam and pressure and other external parameters are unstable or system load is raised or lowered, it is seriously dependent on central control operator, and the experience of operator is uneven, and the processing timeliness is poor, and the operation mode is different, and the judgment basis of running state is not the same, so the device cannot be in the best running state, not only the labor intensity is great, but also the production operation is unstable, so the energy consumption of glycol rectification is high.

[0003] By introducing advanced process control (abbreviation APC) technology, the global optimization of multi -tower multi -variable system can be realized, the energy consumption can be effectively reduced, and the stability of system operation can be improved. Especially for methanol recovery tower, dehydration tower, dealcoholization tower, product tower and recovery tower and other core unit operations, through the optimization control of APC system, the energy consumption in rectification process and the labor intensity of frequent operation of operator can be greatly reduced, and high -purity glycol product can be stably produced. UTILITY MODEL CONTENT

[0004] Based on the problems of prior art, the utility model provides a kind of APC system control coal -to -glycol rectification device, can realize the dynamic optimization and minimization of each tower energy consumption under the premise of guaranteeing the purity of glycol product, reduce production cost, improve the running efficiency of equipment, and reduce the strength of frequent operation of operator.

[0005] In order to solve the above technical problems, the technical scheme of the utility model is as follows:

[0006] An APC system controls a device for rectifying coal-to-ethylene glycol, which comprises, in sequence according to a process, a methanol recovery tower device, a dehydration tower device, a dealcoholization tower device, a product tower device, and a recovery tower device; each of the methanol recovery tower device, the dehydration tower device, the dealcoholization tower device, the product tower device, and the recovery tower device comprises a rectifying tower, a reboiler, a condensing and cooling device, and a pump; and temperature sensors and / or pressure sensors and / or component sensors and / or liquid level sensors and / or flow sensors and / or pumps and / or regulating valves arranged on the methanol recovery tower device, the dehydration tower device, the dealcoholization tower device, the product tower device, and the recovery tower device are connected with a DCS system and the APC system.

[0007] The methanol recovery tower device is used for recovering methanol in a hydrogenated crude ethylene glycol product.

[0008] The dehydration tower device is used for removing water and low-boiling-point alcohols, including methanol and ethanol, from the crude ethylene glycol product.

[0009] The dealcoholization tower device is used for removing residual alcohols from the crude ethylene glycol product.

[0010] The product tower device is used for purifying ethylene glycol to obtain a high-purity ethylene glycol product and ensure the quality of the final product.

[0011] The recovery tower device is used for separating heavy fractions in the discharge from the tower kettle of the product tower device and recovering ethylene glycol.

[0012] The APC system monitors, in real time, the operating parameters of each rectifying tower, reboiler, and condensing and cooling device by installing temperature sensors and / or pressure sensors and / or liquid level sensors and / or flow sensors and / or component sensors on the methanol recovery tower device, the dehydration tower device, the dealcoholization tower device, the product tower device, and the recovery tower device.

[0013] The APC system optimizes and controls the operating conditions of each rectifying tower, reboiler, and condensing and cooling device based on an MPC algorithm, i.e., a multivariable predictive control algorithm, in combination with a process model.

[0014] The APC system dynamically adjusts key operating parameters of the methanol recovery tower device, the dehydration tower device, the dealcoholization tower device, the product tower device, and the recovery tower device, such as reflux ratio, reboiler load, and condensing and cooling medium flow, to reduce energy consumption and stabilize product quality.

[0015] Further, the APC system is connected with a remote service system through a 4G network and a DTU device, i.e., a wireless terminal device.

[0016] Further, an isolation hardware firewall is arranged between the DCS system and the APC server and between the APC server and the remote service system.

[0017] Further, the APC server of the APC system is connected with the OPC server of the DCS system. Advantages

[0018] (1) Significant energy-saving effect: By optimizing the control of the operating parameters of the methanol recovery tower device, dehydration tower device, dealcoholization tower device, product tower device, and recovery tower device, unnecessary energy waste is reduced, especially the reboiler load and the power consumption of the condenser.

[0019] (2) Stable product quality: The APC system can ensure the high purity of the ethylene glycol product while reducing the product quality changes caused by operating fluctuations.

[0020] (3) High system automation: The control process of the entire device has a high degree of automation, reducing the dependence on operators, reducing manual operation errors, and also reducing the labor intensity of frequent operation of operators.

[0021] (4) Strong adaptability to working conditions: The APC system can adapt to different working condition changes, such as raw material fluctuations and environmental condition changes. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structure schematic diagram of the ethylene glycol rectification of the present application;

[0023] Figure 2 is an APC operation menu diagram of the ethylene glycol rectification of the present application;

[0024] Figure 3 is an APC system structure schematic diagram of the ethylene glycol rectification of the present application

[0025] In the figure: 1-methanol recovery tower device; 2-dehydration tower device; 3-dealcoholization tower device; 4-product tower device; 5-recovery tower device; 6-DCS system; 7-APC system. DETAILED DESCRIPTION Example 1

[0026] Reference Figure 1In order to minimize the energy consumption of the coal-to-ethylene glycol rectification system, reduce production costs, and reduce the operation error and operation intensity of the operator while ensuring the ethylene glycol product, the utility model provides a kind of device for APC system control coal-to-ethylene glycol rectification, including methanol recovery tower device 1, dehydration tower device 2, dealcoholization tower device 3, product tower device 4, recovery tower device 5 connected in order according to process sequence;Methanol recovery tower device 1, dehydration tower device 2, dealcoholization tower device 3, product tower device 4, recovery tower device 5 all include rectifying tower, reboiler, condensing cooling device and pump, regulating valve respectively;Temperature sensor and / or pressure sensor and / or component sensor and / or liquid level sensor and / or flow sensor and / or pump and / or regulating valve arranged on methanol recovery tower device 1, dehydration tower device 2, dealcoholization tower device 3, product tower device 4, recovery tower device 5 are connected with DCS system 6 and APC system 7;

[0027] Methanol recovery tower device 1 is used to recover methanol in hydrogenation crude ethylene glycol product;Dehydration tower device 2 is used to remove water and low-boiling alcohol in crude ethylene glycol product, and low-boiling alcohol includes methanol and ethanol;Dealcoholization tower device 3 is used to remove residual alcohol from crude ethylene glycol product, including removing 2,3-butanediol, 1,2-propanediol, 1,2-butanediol, methyl glycolate and other light fractions;Product tower device 4 is used to purify ethylene glycol to obtain high-purity ethylene glycol product and ensure the quality of the final product;Recovery tower device 5 is used to separate heavy fractions in product tower device 4 column still discharge and recover ethylene glycol in product tower device 4 column still discharge.

[0028] APC system 7 monitors the operating parameters of each rectifying tower, reboiler and condensing cooling device in real time by installing temperature sensor and / or pressure sensor and / or liquid level sensor and / or flow sensor and / or component sensor on methanol recovery tower device 1, dehydration tower device 2, dealcoholization tower device 3, product tower device 4 and recovery tower device 5.

[0029] APC system 7 optimizes and controls the operating conditions of each rectifying tower, reboiler, condensing cooling device and the like based on MPC algorithm, i.e. multivariable predictive control algorithm, combined with process model.

[0030] APC system 7 dynamically adjusts the reflux ratio, reboiler load, condensing cooling medium flow and other key operating parameters of methanol recovery tower device 1, dehydration tower device 2, dealcoholization tower device 3, product tower device 4 and recovery tower device 5 to achieve the purpose of reducing energy consumption and stabilizing product quality.

[0031] APC system 7 sets up device fault voice alarm, and reminds the operator through voice alarm when the device fails.

[0032] APC system 7 is connected with remote service system through 4G network and DTU device, i.e. DUT device is wireless terminal device.

[0033] A hardware firewall is set up between the DCS system 6 and the APC server, between the APC server and the remote service system.

[0034] The APC server of the APC system 7 is connected with the OPC server of the DCS system 6.

[0035] A method for controlling coal-to-ethylene glycol distillation by an APC system 7, comprising the following steps:

[0036] Data acquisition: Real-time acquisition of key process parameters such as temperature, pressure, component, flow rate and liquid level of methanol recovery column device 1, dehydration column device 2, dealcoholization column device 3, product column device 4 and recovery column device 5 through temperature sensors, pressure sensors, liquid level sensors, flow sensors and component sensors.

[0037] Step test: In the control system, step test is used to determine the dynamic characteristics of the coal-to-ethylene glycol distillation system. By changing the set value of temperature, pressure, component, flow rate, liquid level and other key process parameters, the output change of the coal-to-ethylene glycol distillation system is observed, and the data such as the speed of parameter rise or fall, overshoot and regulation time are recorded.

[0038] Process modeling: According to historical operation data and operation experience, a mathematical model of the distillation process is established to ensure accurate prediction of the entire system.

[0039] Energy consumption optimization: Based on the energy consumption model in the APC system 7, the operating conditions of the methanol recovery column device 1, dehydration column device 2, dealcoholization column device 3, product column device 4 and recovery column device 5 are dynamically optimized to reduce unnecessary energy consumption, such as optimizing steam consumption and cooling medium consumption by controlling reflux ratio, reboiler load and condensing cooling device load.

[0040] Product purity control: The APC system 7 adjusts the operating parameters of the methanol recovery column device 1, dehydration column device 2, dealcoholization column device 3, product column device 4 and recovery column device 5 in real time to ensure the purity of the final ethylene glycol product, while avoiding the increase of energy consumption caused by excessive purification.

[0041] Disturbance handling: When the feedstock composition and / or temperature and / or pressure and / or flow rate change, the APC system 7 can quickly respond and automatically adjust the operating parameters of the methanol recovery column device 1, dehydration column device 2, dealcoholization column device 3, product column device 4 and recovery column device 5 to ensure the continuous and stable production.

[0042] PID parameter tuning: By tuning the PID parameters of the methanol recovery column device 1, the dehydration column device 2, the dealcoholization column device 3, the product column device 4, and the recovery column device 5, the system can quickly recover to a stable state after being disturbed by reasonably adjusting the PID parameters, and the self-control rate and stability of the control system are improved, which provides data basis for the step test and process modeling of the APC system 7.

[0043] The APC server of the APC system 7 is connected with the OPC server of the DCS system 6, and the operator can select the DCS system 6 control or the APC system 7 control by the disturbance-free switching mode. The APC system 7 and the DCS system 6 can switch to control the temperature, pressure, component, flow, and liquid level of the methanol recovery column device 1, the dehydration column device 2, the dealcoholization column device 3, the product column device 4, and the recovery column device 5.

[0044] The communication between the APC system 7 and the DCS system 6 adopts the international standard OPC communication protocol to complete the bidirectional data exchange between the two systems.

[0045] The communication between the APC system 7 and the remote service system (HeroRTS) is based on the 4G network and the DTU device, adopts the virtual VPN data transmission technology, and completes the real-time remote service function of the APC server; the system is equipped with a special hardware firewall for the isolation between the DCS system 6 and the APC server and the APC server and the remote service system.

[0046] The control variables set for the methanol recovery column device 1 include the reflux tank liquid level at the top of the column, the methanol recovery column tank liquid level, the methanol recovery column intermediate temperature, the condensing and cooling device pressure, the methanol recovery column tank temperature, the feed temperature, the suction inlet pressure, and the methanol recovery column top pressure; the operation variables set for the methanol recovery column device 1 include the methanol recovery column top reflux amount, the methanol recovery column bottom production amount, the middle steam amount, the methanol recovery column tank steam amount, and the top vacuum valve position; the load adjustment set for the methanol recovery column device 1 includes the crude methanol feed amount and the crude ethylene glycol feed amount; the interference variables include the side sampling refined methanol amount;

[0047] The control variables set for the dehydration column device 2 include the dehydration column top temperature, the dehydration column tank temperature, the reflux tank liquid level at the top of the column, the dehydration column tank liquid level, the suction inlet pressure, and the dehydration column top pressure; the operation variables set for the dehydration column device 2 include the dehydration column top reflux amount, the dehydration column tank steam amount, the top production amount, the dehydration column tank production amount, and the top vacuum valve position; the interference variables set for the dehydration column device 2 include the top reflux amount and the dehydration column feed amount;

[0048] The control variables set by the dealcoholization tower device 3 include dealcoholization tower overhead temperature, overhead reflux tank level, overhead reflux ratio, overhead ethylene glycol content, overhead butylene glycol content, overhead water content, dealcoholization tower bottom temperature, dealcoholization tower bottom level, suction inlet pressure, dealcoholization tower overhead pressure; the operation variables set by the dealcoholization tower device 3 include dealcoholization tower overhead flow, dealcoholization tower overhead take-off, dealcoholization tower bottom steam, dealcoholization tower bottom take-off, overhead vacuum valve position; the interference variables set by the dealcoholization tower device 3 include dealcoholization tower feed flow, dealcoholization tower overhead flow;

[0049] The control variables set by the product tower device 4 include overhead reflux tank level, product tower bottom temperature, product tower bottom level, refined ethylene glycol product tank level, suction inlet pressure, product tower overhead pressure; the operation variables set by the product tower device 4 include overhead reflux valve position, product tower bottom steam, product tower side take-off, refined ethylene glycol product tank take-off valve position, overhead vacuum valve position, suction inlet pressure valve position; the interference variables set by the product tower device 4 include side take-off and product tower feed flow;

[0050] The control variables set by the recovery tower device 5 include recovery tower bottom temperature, recovery tower bottom level, suction inlet pressure, recovery tower overhead pressure; the operation variables set by the recovery tower device 5 include recovery tower bottom steam, recovery tower bottom take-off, overhead vacuum valve position.

[0051] Communication timer: monitors whether the APC controller and the DCS communicate normally. Starting from 0, the timer is increased by a fixed period each time. If the controller operating period is 30 seconds, the timer is increased by 30 seconds. If the APC server and the DCS communicate normally, the counting is restarted from 0, and the period cycle is restarted. When communication abnormalities occur, the counter will gradually increase to 120. The monitoring logic cuts all the APC circuits put into use to the DCS normal operation, and triggers a prompt information.

[0052] The main controller is set in three states of off, hot standby and control. Off means that the main controller is in the off state; hot standby means that the main controller is in the standby state; control means that the main controller is in the control state. The sub-controller is set in two states of on and off. On means that the sub-controller is in the put-into-use state; off means that the sub-controller is in the cut-off state.

[0053] The control variables and the operation variables set the measured values or the set values or the valve position values. The control variables further set the control high limit and the control low limit; the operation variables set the operation high limit and the operation low limit.

[0054] The control variable is set with measured value, current value, steady-state value, lower limit, upper limit, actual mode, and request mode a. The request mode a is set with open mode and closed mode. The actual mode is the actual activation state of the control variable, reflecting whether the control variable is controlled by the operation variable through APC, including the activation state and the non-activation state.

[0055] The operating variable settings include valve position, measured value, set value, lower limit, upper limit, next step amplitude adjustment, DCS mode, and request mode b. The request mode b sets APC mode and DCS mode. DCS mode is the current control mode for the corresponding operating variable. Next step amplitude adjustment indicates the adjustment range of the valve position or set value of the corresponding operating variable within the current cycle.

[0056] The load adjustment settings include valve position, measured value, set value, low limit, high limit, downward adjustment range, DCS mode, and request mode c, where request mode c includes APC mode and DCS mode.

[0057] The interference variable is set with interference value, change value, change state, actual mode and request mode d, wherein the request mode d is set with open mode and close mode.

[0058] The operation method of APC system 7 includes the following steps:

[0059] 1. Preparatory steps before starting the controller:

[0060] Before using the DCS operating interface, if APC System 7 is in offline "shutdown" mode, the engineer must first start the APC controller from the APC server. When the engineer starts the controller, it will enter "hot standby" mode, and a timer will begin counting. This continuous counting indicates that communication between APC System 7 and DCS System 6 is normal, and the system is in a "hot standby" state ready for deployment.

[0061] 2. Steps to start the sub-controller:

[0062] a. Confirm whether the communication counter is performing an increment operation and whether the control mode is in "hot standby" mode;

[0063] b. Verify that the high and low limits of the manipulated variable are set correctly. That is, confirm that the setpoint of the controller or the valve opening is within the high and low limit range of the manipulated variable to ensure that sufficient adjustment range is provided for the APC system 7.

[0064] c. Press the "Control" button on the main controller;

[0065] d. Next, press the "On" button on the sub-controller. Wait for one control cycle to confirm whether the corresponding control variable switch is in the "On" state;

[0066] e. confirming that the corresponding control variable switch is in the "on" state;

[0067] f. pressing the "APC" button of the operating variable switch, the operating variable will be switched from the local mode request to the remote mode;

[0068] g. waiting for one control cycle, the main controller mode will be changed to the "control" state, and the sub-controller mode will also be changed to the "on" state; if the main controller mode is in the "control" state and the sub-controller mode is in the "on" state, the APC system 7 will take over the operation of the PID controller to maintain the factory operation.

[0069] All the above steps must be completed within one control cycle. If the main controller is already in the "control" mode, starting the sub-controller only needs steps d~f; if the sub-controller is already in the control mode, the operating variable under the controller needs only step f.

[0070] 3. Cutting off the main controller, sub-controller and operating variable steps:

[0071] (1) If the APC system 7 is not needed to implement control, only the "hot standby" button needs to be pressed; in the next control cycle, the DCS system 6 switching program will switch the operating variable under the main controller back to local operation, and all sub-controllers are switched to the "off state.

[0072] (2) If a sub-controller is not needed to implement control, for example, cutting off the normal pressure tower controller, only the "off button of the sub-controller needs to be pressed, and in the next control cycle, the DCS system 6 will switch the operating variable under the sub-controller back to local operation, and the sub-controller is switched to the "off state, and the states of other sub-controllers remain unchanged.

[0073] (3) If you want to cut off an operating variable alone, click the "DCS" button of the operating variable switch in the APC system 7 screen, and the switching program will complete the switching back to local control operation.

[0074] (4) If an emergency occurs, only the "hot standby" button needs to be pressed, all sub-controllers will be switched to the "off state, the main controller will be switched to the "hot standby" state, and all operating variables in the remote mode will be switched back to the local mode, and the APC system 7 releases the control right to the operator.

[0075] The APC system 7 also sets up a test analysis data input interface to input test analysis data into the APC system 7, so that the APC system 7 can perform corresponding operations according to the test analysis data.

[0076] The utility model discloses a working principle: the utility model passes through the introduction APC technology, and optimization control coal methanol rectification system can realize the global optimization of multi -tower multivariable system, effectively reduce energy consumption, improve the stability of system operation, especially for methanol recovery tower, dehydration tower, dealcoholization tower, product tower and recovery tower etc. core unit operation, through the optimization control of APC system 7, can greatly reduce the energy consumption in rectification process, reduced unnecessary energy waste, especially reboiler load and condenser power consumption;The utility model greatly improved the automation degree of whole device control process, reduced the dependence to operating personnel, reduced the manual operation error, also reduced the labor intensity of operating personnel frequent operation simultaneously, and stable production high -purity glycol product, reduced the product quality change caused by operation fluctuation;The utility model can also adapt to different working condition change, for example raw material fluctuation and environmental condition change.

[0077] The modification and change of the utility model belong to the patent range of the utility model, and are not limited to the description of the embodiments.

Claims

1. An apparatus for controlling coal-to-ethylene glycol distillation by an APC system, characterized in that: The methanol recovery column device, the dehydration column device, the dealcoholization column device, the product column device and the recovery column device are connected in sequence according to the process sequence; the methanol recovery column device, the dehydration column device, the dealcoholization column device, the product column device and the recovery column device each comprises a rectifying column, a reboiler, a condensing and cooling device and a pump; the temperature sensor, the pressure sensor, the component sensor, the liquid level sensor, the flow sensor, the pump and the regulating valve arranged on the methanol recovery column device, the dehydration column device, the dealcoholization column device, the product column device and the recovery column device are connected with the DCS system and the APC system.

2. The APC system for controlling the apparatus for distilling coal-to-ethylene glycol according to claim 1, wherein: The APC system is connected with the remote service system through a 4G network and a DTU device, that is, the DTU device is a wireless terminal device.

3. The APC system for controlling the apparatus for distilling coal-to-ethylene glycol according to claim 1, wherein: An isolation hardware firewall is arranged between the DCS system and the APC server and between the APC server and the remote service system.

4. The apparatus for controlling coal-to-ethylene glycol distillation according to any one of claims 1 to 3, characterized in that: The APC server of the APC system is connected with the OPC server of the DCS system.

Images