A method and system for wet syngas heating value control for an igcc unit

Abstract

The application discloses a wet synthetic gas heat value control method and system for an IGCC unit. First, a set value of regulation and control is set. In the process of regulation and control, constraint conditions such as a dry synthetic gas flow feedforward link, wet synthetic gas heat value low limit locking steam flow increase and wet synthetic gas heat value high limit locking steam flow decrease are added. The adjustment of the dry synthetic gas flow feedforward link can improve the heat value adjustment response speed. The adjustment of the wet synthetic gas heat value low limit locking steam flow increase and the wet synthetic gas heat value high limit locking steam flow decrease can ensure that the wet synthetic gas heat value changes within a reasonable control range. Based on this, when multiple changes of the gasifier working condition cause changes of the dry synthetic gas composition, corresponding adjustment strategies can be made in a timely manner according to different working conditions, so that the synthetic gas pipe network pressure fluctuation caused by excessive adjustment of the fuel valve of the gas turbine can be avoided, and the unit load fluctuation is reduced, the stability of the whole machine operation is improved, and the precision of the wet synthetic gas heat value adjustment is improved.

Description

Technical Field

[0001] This invention belongs to the field of IGCC unit power generation technology, and relates to a method and system for controlling the calorific value of wet syngas in IGCC units. Background Technology

[0002] When the IGCC unit is running normally, it uses low-calorific-value hydrogen-rich syngas produced by the gasifier. The calorific value of the wet syngas is adjusted by injecting dry syngas into the intermediate-pressure steam drum of the gasifier through a saturated humidification module to saturate the steam. The amount of steam to be injected is calculated based on the calorific value of the dry syngas and then controlled for calorific value. The current steam quantity is calculated by the dry syngas calorific value signal through a gain circuit, and the gain coefficient is manually set.

[0003] Existing calorific value control methods result in an open-loop adjustment of the calorific value of the syngas, making it impossible to precisely control the calorific value. When the gasifier's operating conditions change and the dry syngas composition changes, the calorific value of the wet syngas cannot be adjusted in a timely manner. This may lead to excessive adjustment of the gas turbine fuel regulating valve, causing pressure fluctuations in the syngas pipeline network, which in turn causes unit load fluctuations. Summary of the Invention

[0004] The purpose of this invention is to solve the problem in the prior art that when the operating conditions change, the calorific value of wet syngas cannot be adjusted in a timely manner, which leads to fluctuations in syngas pipeline pressure and thus fluctuations in unit load. This invention provides a method and system for controlling the calorific value of wet syngas in IGCC units.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for controlling the calorific value of wet syngas in IGCC units includes the following steps:

[0007] Obtain the measured calorific value of wet syngas;

[0008] Set the wet syngas calorific value setpoint, adjust the wet syngas calorific value based on the obtained measured wet syngas calorific value and the setpoint, and obtain the adjusted output value;

[0009] During the adjustment process, a feedforward loop for dry syngas flow rate is set, and the steam flow rate for the lower limit of wet syngas calorific value lockout is increased, while the steam flow rate for the upper limit of wet syngas calorific value lockout is decreased, to compensate for and constrain the adjustment of the wet syngas calorific value.

[0010] The steam injection flow rate to be adjusted is obtained based on the acquired adjustment output value, and the adjustment command is obtained based on the steam injection flow rate.

[0011] A further improvement of the present invention is that:

[0012] Establish a cascade closed-loop control loop for the calorific value of wet syngas, including a main loop and a secondary loop;

[0013] The main circuit controls and adjusts the calorific value of the wet syngas.

[0014] The secondary loop controls the steam injection flow rate, while the output value of the primary loop becomes the input value of the secondary loop. The output value of the secondary loop is the valve control command for the steam injection flow rate, which further adjusts the calorific value of the wet syngas.

[0015] Automatic compensation for humming in the left and right combustion chambers of the gas turbine is added to the main circuit. The automatic compensation is used to offset the set value of the calorific value of the wet syngas based on the humming value of the gas turbine combustion chamber.

[0016] The dry syngas flow feedforward includes:

[0017] The dry syngas flow feedforward circuit obtains the converted steam injection flow rate based on the dry syngas flow rate. When the dry syngas flow rate changes, the steam injection flow rate is adjusted.

[0018] The minimum calorific value of the wet syngas is increased by the required steam flow rate when the calorific value of the wet syngas is below 9000 KJ / m³. 3 At that time, the output value of the main circuit stops increasing;

[0019] The high-limit lockout steam flow rate for wet syngas calorific value is reduced to a value when the wet syngas calorific value is higher than 12000 KJ / m³. 3 At that time, the output value of the main circuit stops decreasing.

[0020] It also includes adding fault interlock control loops for wet syngas calorific value signals, dry syngas flow signals, and steam flow signals;

[0021] When any of the following signals fails: wet syngas calorific value signal, dry syngas flow rate signal, and steam flow rate signal, the control loop switches to manual mode, while the steam injection valve command remains unchanged, allowing for manual intervention and adjustment.

[0022] It also includes setting fault over-limit values ​​for wet syngas calorific value signals, dry syngas flow rate signals, and steam flow rate signals respectively;

[0023] An audible and visual alarm will be triggered when any of the following signals exceeds the corresponding fault limit: wet syngas calorific value signal, dry syngas flow rate signal, and steam flow rate signal.

[0024] A wet syngas calorific value control system for IGCC units includes a measured value acquisition module, an adjustment module, a compensation constraint module, and an adjustment command acquisition module.

[0025] The measured value acquisition module is used to acquire the measured calorific value of wet syngas;

[0026] The adjustment module is used to set the calorific value of wet syngas, adjust the calorific value of wet syngas based on the obtained measured calorific value of wet syngas and the set value, and obtain the adjustment output value;

[0027] The compensation and constraint module is used to compensate and constrain the adjustment of the calorific value of wet syngas by setting a feedforward link for dry syngas flow rate, increasing the steam flow rate at the lower limit of wet syngas calorific value lockout, and decreasing the steam flow rate at the upper limit of wet syngas calorific value lockout during the adjustment process.

[0028] The adjustment command acquisition module is used to obtain the steam injection flow rate to be adjusted based on the acquired adjustment output value, and to obtain the adjustment command based on the steam injection flow rate.

[0029] A terminal device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described in this invention.

[0030] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of any of the methods described in this invention.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention discloses a method for controlling the calorific value of wet syngas in IGCC units. First, a setpoint for regulation is established. During the regulation process, constraints are added, including a dry syngas flow feedforward loop, an increase in the steam flow rate locking the lower limit of wet syngas calorific value, and a decrease in the steam flow rate locking the upper limit of wet syngas calorific value. Adjusting the dry syngas flow feedforward loop improves the calorific value adjustment response speed. Adjusting the steam flow rate locking the lower limit of wet syngas calorific value and the decrease in the steam flow rate locking the upper limit of wet syngas calorific value ensures that the calorific value of wet syngas varies within a reasonable control range. Based on this, when various changes occur in the gasifier operating conditions, leading to changes in the dry syngas composition, corresponding adjustment strategies can be made promptly for different operating conditions. This avoids pressure fluctuations in the syngas pipeline caused by excessive adjustment of the gas turbine fuel regulating valve, thereby reducing unit load fluctuations, improving the overall stability of the unit operation, and increasing the accuracy of wet syngas calorific value adjustment.

[0033] Furthermore, this invention adds a fault interlock control loop for the wet syngas calorific value signal, dry syngas flow rate signal, and steam flow rate signal to ensure that the control loop does not malfunction due to measurement point faults. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the present invention;

[0036] 11-Filtering circuit; 12-Combustion chamber hum compensation; 13-Dry syngas flow feedforward circuit; 14-Wet syngas calorific value alarm interlock circuit; 15-Fault diagnosis circuit; 16-Wet syngas calorific value main control circuit; 17-Steam injection flow secondary control circuit. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0043] The present invention will now be described in further detail with reference to the accompanying drawings:

[0044] This invention discloses a method for controlling the calorific value of wet syngas in IGCC units, comprising the following steps:

[0045] Step 1: Calculate the measured calorific value of wet syngas using a syngas component analyzer. Transmit the calorific value signal from the TCS (Gas Turbine Control System) to the DCS (Distributed Control System). The DCS filters the signal through filter circuit 11 before using it.

[0046] Specifically, it includes:

[0047] The calorific value signal is sent to the DCS (Distributed Control System) via a 4-20mA signal. The DCS filters and limits the acquired calorific value signal, which is then used as the controlled variable in the main control loop of the wet syngas calorific value cascade closed-loop control.

[0048] The filtering time depends on the actual fluctuation of the calorific value and can be selected within 6 to 10 seconds. The limit is based on the unit's design value and is generally set to a lower limit of 8500 KJ / m³. 3 Upper limit 12500KJ / m 3 .

[0049] Step 2:

[0050] In the DCS, a cascade closed-loop control loop for the calorific value of wet syngas is designed, including a main control loop 16 for the calorific value of wet syngas and a secondary control loop 17 for the injection steam flow rate; the main loop controls the calorific value of wet syngas and the secondary loop controls the injection steam flow rate.

[0051] The main control loop is used for deviation-free control of the calorific value of wet syngas. Its controlled variable is the TCS signal used to measure the calorific value of wet syngas, and the setpoint is given by the operator.

[0052] Furthermore, an automatic humming compensation 12 is added to the left and right combustion chambers of the gas turbine. When the humming is high, the offset of the wet syngas calorific value setpoint is automatically increased. When the humming returns to normal, the offset of the wet syngas calorific value setpoint is 0, and the secondary loop quickly responds to the change in steam flow.

[0053] This compensation is performed by function FX1. The input to function FX1 is the hum value of the gas turbine combustion chamber, and the output is the offset of the wet syngas calorific value setpoint. The setting principle of FX1 is as follows:

[0054] When the humming varies between 30mbar and 200mbar, the output value of FX1 varies between 0 and 150KJ, thereby increasing the main control circuit setting value to increase the heat value and reduce the humming.

[0055] When the humming is between 0 and 30 mbar, the FX1 output value remains at 0, and the wet syngas calorific value setpoint is entirely set by the operator.

[0056] The output value of the main control loop after PID calculation is used as the set value of the secondary control loop. The controlled variable of the secondary control loop is the steam injection flow rate. The secondary control loop is usually selected with P or PI control law. The output command directly controls the adjustment of the steam injection regulating valve and responds quickly to changes in flow rate.

[0057] Step 2 also includes:

[0058] The dry syngas flow feedforward link 13 is designed to compensate for the steam flow in a timely manner when the dry syngas flow changes, thereby improving the response speed of calorific value adjustment.

[0059] Specifically:

[0060] In the main control loop of the wet syngas calorific value cascade closed-loop control loop, a dry syngas flow feedforward element FX2 is designed:

[0061] The dry syngas flow feedforward circuit FX2 takes dry syngas flow rate as input and outputs the converted steam injection flow rate. Due to the presence of the feedforward circuit, the steam injection flow rate setpoint of the secondary control circuit can be adjusted in a timely manner when the dry syngas flow rate changes, thereby adjusting the steam injection flow rate in a timely manner and improving the calorific value adjustment response speed.

[0062] Design a wet syngas calorific value alarm interlocking circuit 14, including a steam flow increase interlocking the low limit of wet syngas calorific value and a steam flow decrease interlocking the high limit of wet syngas calorific value, to ensure that the wet syngas calorific value changes within a reasonable control range.

[0063] Specifically:

[0064] In the main control loop of the cascade closed-loop control loop for wet syngas calorific value, the following are designed: Low-limit lockout for increased steam flow rate of wet syngas calorific value and high-limit lockout for decreased steam flow rate of wet syngas calorific value.

[0065] When the calorific value of wet syngas is below 9000 KJ / m3, the increase of PID output in the main control circuit is prohibited.

[0066] When the calorific value of wet syngas exceeds 12000 KJ / m3, the PID output of the main control circuit is prohibited from decreasing, thereby ensuring that the calorific value of wet syngas is controlled within a reasonable range.

[0067] Design a fault interlock control loop for wet syngas calorific value signal, dry syngas flow rate signal, and steam flow rate signal to switch to manual mode, and ensure that the control loop malfunctions caused by measurement point failures are avoided.

[0068] Specifically:

[0069] In the cascade closed-loop control loop for wet syngas calorific value, a manual switching function is designed for the interlock control loop of wet syngas calorific value signal, dry syngas flow signal, and steam flow signal. When any of the above fault signals is triggered, the control loop will switch to manual mode, while the steam injection valve command will remain unchanged. Operators can intervene and adjust in a timely manner based on the alarm information. This function ensures that abnormal operation of the control loop caused by measurement point failure is avoided.

[0070] The design incorporates a wet syngas calorific value alarm function. When the wet syngas calorific value signal exceeds the alarm limit, a corresponding audible and visual alarm should be triggered on the DCS screen.

[0071] Specifically:

[0072] The system is designed with alarm functions. When there is a fault in the calorific value signal of wet syngas, a fault in the flow rate signal of dry syngas, a fault in the steam flow rate signal, or when the calorific value signal of wet syngas exceeds the limit, the corresponding audible and visual alarms should be triggered on the DCS screen to remind the operators to intervene and make timely adjustments.

[0073] This embodiment discloses a method for controlling the calorific value of wet syngas in IGCC units. Employing a cascade closed-loop control method for wet syngas calorific value, this method improves the control accuracy of wet syngas calorific value. When the gasifier operating conditions change or the dry syngas composition changes, it ensures timely adjustment of the wet syngas calorific value, avoiding pressure fluctuations in the syngas pipeline caused by excessive adjustment of the gas turbine fuel regulating valve, thereby reducing unit load fluctuations.

[0074] This invention also discloses a wet syngas calorific value control system for IGCC units, comprising:

[0075] The measured value acquisition module is used to acquire the measured calorific value of wet syngas;

[0076] The adjustment module is used to set the calorific value of wet syngas, adjust the calorific value of wet syngas based on the obtained measured calorific value of wet syngas and the set value, and obtain the adjustment output value;

[0077] The compensation and constraint module is used to compensate and constrain the adjustment of the calorific value of wet syngas by setting a feedforward link for dry syngas flow rate, increasing the steam flow rate at the lower limit of wet syngas calorific value lockout, and decreasing the steam flow rate at the upper limit of wet syngas calorific value lockout during the adjustment process.

[0078] The adjustment command acquisition module is used to obtain the steam injection flow rate to be adjusted based on the acquired adjustment output value, and to obtain the adjustment command based on the steam injection flow rate.

[0079] A schematic diagram of a terminal device according to an embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0080] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0081] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0082] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0083] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0084] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0085] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the calorific value of wet syngas in an IGCC unit, characterized in that, Includes the following steps: Obtain the measured calorific value of wet syngas; Set the wet syngas calorific value setpoint, adjust the wet syngas calorific value based on the obtained measured wet syngas calorific value and the setpoint, and obtain the adjusted output value; During the adjustment process, a feedforward loop for dry syngas flow rate is set, and the steam flow rate for the lower limit of wet syngas calorific value lockout is increased, while the steam flow rate for the upper limit of wet syngas calorific value lockout is decreased, to compensate for and constrain the adjustment of the wet syngas calorific value. The steam injection flow rate to be adjusted is obtained based on the acquired adjustment output value, and the adjustment command is obtained based on the steam injection flow rate. Establish a cascade closed-loop control loop for the calorific value of wet syngas, including a main loop and a secondary loop; The main circuit controls and adjusts the calorific value of the wet syngas. The secondary loop controls the steam injection flow rate, while the output value of the primary loop becomes the input value of the secondary loop. The output value of the secondary loop is the valve control command for the steam injection flow rate, which further adjusts the calorific value of the wet synthesis gas. Automatic compensation for humming in the left and right combustion chambers of the gas turbine is added to the main circuit. The automatic compensation is used to offset the set value of the calorific value of wet syngas based on the humming value of the gas turbine combustion chamber. The dry syngas flow feedforward includes: The dry syngas flow feedforward circuit obtains the converted steam injection flow rate value based on the dry syngas flow rate. When the dry syngas flow rate changes, the steam injection flow rate is adjusted. The minimum calorific value of the wet syngas is increased by the required steam flow rate when the calorific value of the wet syngas is below 9000 KJ / m³. 3 At that time, the output value of the main circuit stops increasing; The high-limit lockout steam flow rate for wet syngas calorific value is reduced to a value when the wet syngas calorific value is higher than 12000 KJ / m³. 3 At that time, the output value of the main circuit stops decreasing.

2. The method for controlling the calorific value of wet syngas in an IGCC unit according to claim 1, characterized in that, It also includes adding fault interlock control loops for wet syngas calorific value signals, dry syngas flow signals, and steam flow signals; When any of the following signals fails: wet syngas calorific value signal, dry syngas flow rate signal, and steam flow rate signal, the control loop switches to manual mode, while the steam injection valve command remains unchanged, allowing for manual intervention and adjustment.

3. The method for controlling the calorific value of wet syngas in an IGCC unit according to claim 1, characterized in that, It also includes setting fault over-limit values ​​for wet syngas calorific value signals, dry syngas flow rate signals, and steam flow rate signals respectively; An audible and visual alarm will be triggered when any of the following signals exceeds the corresponding fault limit: wet syngas calorific value signal, dry syngas flow rate signal, and steam flow rate signal.

4. A wet syngas calorific value control system for IGCC units, used to implement the wet syngas calorific value control method for IGCC units as described in claim 1, characterized in that, It includes a measured value acquisition module, an adjustment module, a compensation constraint module, and an adjustment instruction acquisition module; The measured value acquisition module is used to acquire the measured calorific value of wet syngas; The adjustment module is used to set the calorific value of wet syngas, adjust the calorific value of wet syngas based on the obtained measured calorific value of wet syngas and the set value, and obtain the adjustment output value; The compensation and constraint module is used to compensate and constrain the adjustment of the calorific value of wet syngas by setting a feedforward link for dry syngas flow rate, increasing the steam flow rate at the lower limit of wet syngas calorific value lockout, and decreasing the steam flow rate at the upper limit of wet syngas calorific value lockout during the adjustment process. The adjustment command acquisition module is used to obtain the steam injection flow rate to be adjusted based on the acquired adjustment output value, and to obtain the adjustment command based on the steam injection flow rate.

5. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-3.

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-3.

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