IGCC (integrated gasification combined cycle) unit low-heating-value synthetic gas temperature control method
By designing a wet synthesis gas temperature cascade closed-loop control loop and adding feedforward link in the IGCC unit, the problem of large deviations in the wet synthesis gas temperature and untimely control of the IGCC unit is solved, and more efficient temperature control is achieved, avoiding the risk of damage to the gas engine equipment and instability in combustion.
Patent Information
- Application Number
- CN202411472854.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-03-11
AI Technical Summary
The existing IGCC unit wet synthesis gas temperature control methods have problems such as large control deviations and untimely control, which leads to possible damage to the gas engine equipment, unstable combustion and unstable dual switching of the gas engine fuel.
A low-calorie value synthesis gas temperature control method is designed in the DCS, and a wet synthesis temperature cascade closed-loop control loop is used to design a wet synthesis temperature series closed-loop control loop, which increases the feedforward link of steam injection flow and dry synthesis gas flow, and controls it through the upper and lower limit locking function of the wet synthesis gas temperature, and sets the interlocking control function and alarm mechanism.
Through the design of the cascade closed-loop control and feedforward link, the control accuracy and response speed of the wet synthesis gas temperature are improved, and the damage and combustion instability of the gas engine equipment caused by excessive changes in the wet synthesis gas temperature are avoided.
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Figure CN119597041A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of gas turbine control technology and auxiliary machine system technology, in particular to a method for controlling the temperature of low calorific value synthesis gas of an IGCC unit. Background Art
[0002] The existing IGCC unit uses low calorific value syngas. During normal operation of the gas turbine, the low calorific value hydrogen-rich syngas produced by the gasifier is used. The syngas produced by the gasifier has a lower temperature after ash removal, desulfurization and purification, and cannot meet the combustion requirements of the gas turbine. The syngas temperature needs to be increased by a syngas heater. The heated syngas is mixed with the medium-pressure steam from the gasifier drum through a syngas mixer to finally form wet syngas at a certain temperature. The wet syngas enters the combustion chamber of the gas turbine for combustion and work. The current wet syngas temperature control method is single-loop closed-loop control.
[0003] The original wet syngas temperature control effect was poor and the hysteresis was serious, which could not meet the needs of gas turbine operation. When the calorific value of wet syngas was adjusted, the steam flow rate changed, which would have a greater impact on the wet syngas temperature. When the wet syngas temperature changed, the control hysteresis was serious. If the wet syngas temperature was not adjusted in time, the temperature change would be too large, which would cause the phase state of the wet syngas to change. On the one hand, it might cause damage to the gas turbine equipment and unstable combustion, and on the other hand, it would affect the stability of the dual-fuel switching process of the gas turbine. Summary of the invention
[0004] In view of the problems existing in the existing IGCC units, the present invention is proposed.
[0005] Therefore, the problem to be solved by the present invention is how to solve the problem of large deviation and untimely control of wet synthesis gas temperature in IGCC units.
[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:
[0007] In a first aspect, an embodiment of the present invention provides a method for controlling the temperature of low calorific value synthesis gas of an IGCC unit, which includes designing a wet synthesis temperature cascade closed-loop control circuit in a DCS; designing and adding a steam injection flow feedforward link and a dry synthesis gas flow feedforward link; controlling the temperature through the upper and lower limit locking functions of the wet synthesis gas temperature; and setting an interlocking control function for various faults in the wet synthesis gas temperature control, and simultaneously giving an alarm.
[0008] As a preferred solution of the IGCC unit low calorific value synthesis gas temperature control method of the present invention, wherein: the control loop includes a main loop and a sub-loop; the main loop controls the wet synthesis temperature; and the sub-loop controls the synthesis gas heater heating steam flow.
[0009] As a preferred solution of the IGCC unit low calorific value synthesis gas temperature control method of the present invention, the feedforward link of increasing the steam injection flow rate includes: when the steam injection flow rate increases, the heating steam flow rate is reduced in advance through the feedforward effect; when the steam injection flow rate decreases, the heating steam flow rate is increased in advance through the feedforward effect empirical function FX2, and the formula is as follows:
[0010]
[0011] Among them, X n is the steam injection flow value of the nth section, ranging from X1 = 0 to X 10 =50;Y n It is 70% of the actual heating steam flow at the set temperature, corresponding to X of the nth section. n The value of .
[0012] As a preferred solution of the IGCC unit low calorific value syngas temperature control method of the present invention, the dry syngas flow feedforward link includes: when the dry syngas flow increases, the heating steam flow is increased in advance through the feedforward effect, and when the dry syngas flow decreases, the heating steam flow is reduced in advance through the feedforward effect empirical function FX1, and the formula is as follows:
[0013]
[0014] Among them, P m is the dry synthesis gas flow value of the mth segment, ranging from P1 = 0 to P 10 =25;Q m It is 30% of the actual heating steam flow at the set temperature, corresponding to P of the mth section. m value.
[0015] As a preferred solution of the IGCC unit low calorific value synthesis gas temperature control method of the present invention, the upper and lower limit locking functions include: when the wet synthesis gas temperature is lower than the lower limit, the heating steam flow rate is locked to reduce, and when the wet synthesis gas temperature is higher than the upper limit, the heating steam flow rate is locked to increase.
[0016] As a preferred solution of the low calorific value synthesis gas temperature control method for the IGCC unit described in the present invention, the faults include wet synthesis gas temperature signal fault, dry synthesis gas flow signal fault, steam flow signal fault, heating steam flow signal fault, large feedback deviation of the valve regulating instruction or large wet synthesis gas temperature control deviation; when any fault occurs, the interlock control loop is manually switched and the system issues an alarm.
[0017] As a preferred solution of the IGCC unit low calorific value synthesis gas temperature control method of the present invention, when the fault is eliminated, the operator switches the control loop to the automatic state; the fault signal judgment criteria are signal disconnection, signal current exceeding the limit, and the deviation between redundant signals being greater than the set value.
[0018] In a second aspect, an embodiment of the present invention provides an IGCC unit low calorific value synthesis gas temperature control system, which includes: a filtering module, used to filter an input signal; a subtraction module, used to perform a subtraction operation on two input variables; a manual-automatic module, used to control the switching between manual and automatic of the loop and to transfer numerical values; an addition module, used to perform an addition operation on two input variables; an alarm module, used to monitor whether the input variable exceeds the limit, and the corresponding alarm output pin is True when the limit is exceeded; a quality monitoring module, used to monitor whether the input module measurement point is faulty, and OUT is True when a fault occurs; a logic module, when any input is True, the output is True.
[0019] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the IGCC unit low calorific value synthesis gas temperature control method as described in the first aspect of the present invention are implemented.
[0020] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of the IGCC unit low calorific value synthesis gas temperature control method as described in the first aspect of the present invention are implemented.
[0021] The beneficial effects of the present invention are as follows: the present invention adopts a cascade closed-loop control method for the wet syngas temperature, which can improve the control accuracy of the wet syngas temperature. At the same time, the design of a feedforward link can improve the response speed of the temperature control. When the steam injection flow rate or the dry syngas flow rate changes, the wet syngas temperature can be adjusted in time to avoid possible damage to the gas turbine equipment, unstable combustion, and unstable dual switching of the gas turbine fuel due to excessive changes in the wet syngas temperature. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0023] Figure 1 Schematic diagram of the original wet synthesis gas temperature control method.
[0024] Figure 2 Schematic diagram of the improved wet syngas temperature control method.
[0025] Figure 3 This is the structural diagram of the low calorific value synthesis gas heating system of the IGCC unit. DETAILED DESCRIPTION
[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.
[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0028] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.
[0029] Example 1
[0030] The first embodiment of the invention provides a method for controlling the temperature of low calorific value synthesis gas of an IGCC unit, comprising:
[0031] S1: Design a wet synthetic temperature cascade closed-loop control loop in the DCS.
[0032] The control loop includes a main loop and a sub-loop; the main loop controls the wet synthesis temperature, and the sub-loop controls the steam flow rate of the synthesis gas heater.
[0033] The main loop controls the wet synthesis gas temperature without deviation under the proportional-integral action. The wet synthesis gas temperature set value is given by the operator. The auxiliary loop quickly responds to changes in the heating steam flow rate under pure proportional action.
[0034] Among them, the non-biased control of wet synthesis gas temperature under the proportional integral action means that the purpose of non-biased control is achieved through the proportional and integral links of the PID controller. The proportional link can quickly reflect the error and reduce the error, but it cannot completely eliminate the steady-state error. The control accuracy can be improved by increasing the proportional link parameter KP, but too large a value will cause system instability. The integral link can make the deviation tend to 0 control through the integral algorithm, which can improve the system's non-difference and improve and enhance the system's steady-state performance.
[0035] "Rapidly responding to and adjusting changes in the heating steam flow rate under pure proportional action" means that the auxiliary circuit is composed of a pure proportional link. As mentioned above, the proportional link can quickly reflect the error and reduce the error under the action of the appropriate parameter KP, so that the auxiliary circuit can quickly adjust the valve opening and achieve the purpose of rapidly responding to and adjusting changes in the heating steam flow rate.
[0036] S2: Design to add steam injection flow feedforward link and dry synthesis gas flow feedforward link.
[0037] Specifically, the feedforward link of increasing the steam injection flow rate includes: when the steam injection flow rate increases, the heating steam flow rate is reduced in advance through the feedforward effect; when the steam injection flow rate decreases, the heating steam flow rate is increased in advance through the feedforward effect empirical function FX2 to improve the wet synthesis gas temperature control response speed, wherein the formula of the empirical function FX2 is:
[0038]
[0039] Among them, X n is the steam injection flow value of the nth section, ranging from X1 = 0 to X 10 =50;Y n It is 70% of the actual heating steam flow at the set temperature, corresponding to X of the nth section. n The output Y of this function represents the approximate relationship between the injection steam flow rate X and the heating steam flow rate at the set temperature, and only serves as a feedforward.
[0040] In actual control, the deviation of steam flow is further adjusted by the PID controller.
[0041] It should be noted that the FX2 function consists of an input terminal and an output terminal. The function body can be composed of multiple segments of data to form a broken line function. The more segments there are, the more accurate the function is. Generally, 10 segments are preferred. Each segment of data is represented by a corresponding X n and Y n Composition, n ranges from 1 to 10, X n Represents the steam injection flow rate, X n The range is 0~50 (depending on the actual operating conditions of the unit), Y n It is 70% of the actual heating steam flow at the set temperature (derived from the operating data under actual working conditions). The function output represents the approximate relationship between the injection steam flow and the heating steam flow at the set temperature. It is only used as a feedforward function, and the deviation is adjusted by the PID controller).
[0042] Furthermore, the dry synthesis gas flow feedforward link includes: when the dry synthesis gas flow increases, the heating steam flow is increased in advance through the feedforward effect, and when the dry synthesis gas flow decreases, the heating steam flow is reduced in advance through the feedforward effect empirical function FX1 to improve the wet synthesis temperature control response speed, wherein the formula of FX1 is:
[0043]
[0044] Among them, P m is the dry synthesis gas flow value of the mth segment, ranging from P1 = 0 to P 10 =25;Q m It is 30% of the actual heating steam flow at the set temperature, corresponding to P of the mth section. m value.
[0045] The output Q of the function represents the relationship between the dry syngas flow rate P at the set temperature and the heating steam flow rate as part of the feedforward control; the deviation will be adjusted by the PID controller.
[0046] It should be noted that the FX1 function consists of an input terminal and an output terminal. The function body can be composed of multiple segments of data to form a broken line function. The more segments there are, the more accurate the function is. Generally, 10 segments are preferred. Each segment of data is represented by a corresponding P m and Q m Composition, m ranges from 1 to 10, P m Represents the dry synthesis gas flow value, P m The range is 0 to 25 (depending on the actual operating conditions of the unit), Q m It is 30% of the actual heating steam flow at the set temperature (derived from the operating data under actual working conditions). The function output represents the approximate relationship between the dry synthesis gas flow and the heating steam flow at the set temperature. It is only used as a feedforward function, and the deviation is adjusted by the PID controller).
[0047] S3: The upper and lower limit locking function of the wet synthesis gas temperature ensures that the temperature is always controlled within a reasonable range.
[0048] The wet synthesis gas temperature limit locking function is designed. When the wet synthesis gas temperature is lower than the lower limit, the heating steam flow rate is locked to reduce. When the wet synthesis gas temperature is higher than the upper limit, the heating steam flow rate is locked to increase, ensuring that the wet synthesis gas temperature is controlled within a reasonable range. The upper and lower limits of the wet synthesis gas temperature are determined according to the wet synthesis gas temperature range required for the operation of the gas turbine. The lower limit is 10°C higher than the minimum required value, and the upper limit is 10°C lower than the maximum required value.
[0049] S4: For various faults in wet synthesis gas temperature control, an interlocking control function is set and an alarm is issued at the same time.
[0050] An abnormality handling link is designed. When any of the following occurs (regardless of priority): a wet synthesis gas temperature signal failure, a dry synthesis gas flow signal failure, a steam flow signal failure, a heating steam flow signal failure, a large feedback deviation of the valve control instruction, or a large deviation in the wet synthesis gas temperature control, the interlock control loop is switched to manual mode. At the same time, the system issues an alarm to remind the operating personnel to intervene at the first time and manually adjust the steam injection valve opening in time according to the wet synthesis gas temperature. After the failure is eliminated, the operating personnel switches the control loop to automatic mode to ensure that the control loop is always in a safe working state. The fault signal judgment criteria are signal disconnection (unable to detect the current value), signal current exceeding the limit (not between 3.8 and 20.2ma), and large deviation between redundant signals (the deviation setting value is 10°C).
[0051] Furthermore, a wet syngas temperature alarm function is designed. When the wet syngas temperature signal exceeds the alarm limit, a corresponding sound and light alarm should be given on the DCS screen. The upper and lower limits of the wet syngas temperature alarm are determined according to the wet syngas temperature range required for the operation of the gas turbine. The lower limit is 15°C higher than the minimum required value, and the upper limit is 15°C lower than the maximum required value.
[0052] Example 2
[0053] This embodiment provides an IGCC unit low calorific value synthesis gas temperature control system, including:
[0054] The filter module is used to filter the input signal; the subtraction module is used to perform subtraction operations on two input variables; the manual-automatic module is used to control the switching between manual and automatic in the loop and to transfer numerical values; the addition module is used to perform addition operations on two input variables; the alarm module is used to monitor whether the input variable exceeds the limit, and the corresponding alarm output pin is True when it exceeds the limit; the quality monitoring module is used to monitor whether the input module measurement point is faulty, and OUT is True when it fails; the logic module, when any input is True, the output is True.
[0055] The specific overall schematic diagram is as follows Figure 3 As shown, 1-1, 1-3, 1-4, 1-8 are steam pipes; 1-2, 1-5, 1-9 are synthesis gas pipes; 1-6, 1-7, 1-10, 1-11 are water pipes; 1 is a steam injection regulating valve; 2 is a synthesis gas heater; 3 is a heater drain regulating valve; 4 is a wet synthesis gas mixer; 5 is a drain expansion tank; and 6 is a drain valve.
[0056] This embodiment also provides a computer device, which is applicable to the low calorific value synthesis gas temperature control method of the IGCC unit, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to implement the low calorific value synthesis gas temperature control method of the IGCC unit proposed in the above embodiment.
[0057] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.
[0058] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for controlling the temperature of low calorific value synthesis gas of an IGCC unit as proposed in the above embodiment is implemented.
[0059] In summary, the present invention adopts a cascade closed-loop control method for the wet syngas temperature, which can improve the control accuracy of the wet syngas temperature. At the same time, the design of the feedforward link can improve the response speed of the temperature control. When the steam injection flow rate or the dry syngas flow rate changes, the wet syngas temperature can be adjusted in time to avoid possible damage to the gas turbine equipment, unstable combustion, and unstable dual switching of the gas turbine fuel due to excessive changes in the wet syngas temperature.
[0060] Example 3
[0061] Reference Figure 1-2 , which is the second embodiment of the present invention, and provides a method for controlling the temperature of low calorific value syngas of an IGCC unit. In order to verify the beneficial effects of the present invention, a comparison is made with the original wet syngas temperature control method, as follows:
[0062] Figure 1 It is the original wet synthesis gas temperature control method, where LDLG is a filter module, which is used to filter the input signal. The filter time is set to 6s, and the filtered value is output by OUT;
[0063] DEV is a subtraction block, which is used to perform subtraction operation on two input variables, and the operation result is output by OUT; PID1 and PID2 are PID modules, which are used for PID operation, and the operation result is output by OUT;
[0064] MA is a manual-automatic module, which is used to switch between manual and automatic control loops. It also plays a role in value transmission, sending signals from input IN to output OUT.
[0065] Figure 2 It is an improved wet synthesis gas temperature control method, in which LDLG is a filtering module used to filter the input signal. The filtering time is set to 6s, and the filtered value is output by OUT;
[0066] DEV is a subtraction module, which is used to perform subtraction operation on two input variables, and the operation result is output by OUT; PID1 and PID2 are PID modules, which are used for PID operation, and the operation result is output by OUT;
[0067] MA is a manual-automatic module, which is used to control the switching between manual and automatic in the control loop, and also plays a role in value transmission, sending the signal from input IN to output OUT;
[0068] ADD is an addition module, which is used to perform addition operation on two input variables, and the operation result is output by OUT;
[0069] ALM is an alarm module, which is used to monitor whether the input variable exceeds the limit. When the limit is exceeded, the corresponding alarm output pin is True;
[0070] QA is a quality monitoring module, which is used to monitor whether the input module measurement point is faulty. In case of fault, OUT is True.
[0071] OR is a logic module. When any input is True, the output is True. Fx1 and Fx2 are empirical function formulas. For specific explanations, see the technical solution.
[0072] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.
Claims
1. A method for controlling the temperature of low calorific value synthesis gas of an IGCC unit, characterized in that: include, Design wet synthesis temperature cascade closed-loop control loop in DCS; The design adds steam injection flow feedforward link and dry synthesis gas flow feedforward link; The temperature is controlled by the upper and lower limit locking function of the wet synthesis gas temperature; For various faults in wet synthesis gas temperature control, an interlocking control function is set and an alarm is issued at the same time.
2. The method for controlling the temperature of low calorific value synthesis gas of an IGCC unit according to claim 1, characterized in that: The control loop includes a main loop and a secondary loop; The main loop controls the wet synthesis temperature; the secondary loop controls the flow rate of steam heated by the synthesis gas heater.
3. The method for controlling the temperature of low calorific value synthesis gas of an IGCC unit according to claim 2, characterized in that: The step of increasing the steam flow rate feedforward comprises: When the steam injection flow rate increases, the heating steam flow rate is reduced in advance through the feedforward effect. When the steam injection flow rate decreases, the heating steam flow rate is increased in advance through the feedforward effect empirical function FX2. The formula is as follows: Among them, X n is the steam injection flow value of the nth section, ranging from X1 = 0 to X 10 =50;Y n It is 70% of the actual heating steam flow at the set temperature, corresponding to X of the nth section. n The value of .
4. The method for controlling the temperature of low calorific value synthesis gas of an IGCC unit according to claim 3, characterized in that: The dry synthesis gas flow feedforward link includes: When the dry syngas flow rate increases, the heating steam flow rate is increased in advance through the feedforward effect. When the dry syngas flow rate decreases, the heating steam flow rate is reduced in advance through the feedforward effect empirical function FX1. The formula is as follows: Among them, P m is the dry synthesis gas flow value of the mth segment, ranging from P1 = 0 to P 10 =25;Q m It is 30% of the actual heating steam flow at the set temperature, corresponding to P of the mth section. m value.
5. The method for controlling the temperature of low calorific value synthesis gas of an IGCC unit according to claim 4, characterized in that: The upper and lower limit locking functions include: When the wet synthesis gas temperature is lower than the lower limit, the lock heating steam flow rate is reduced, and when the wet synthesis gas temperature is higher than the upper limit, the lock heating steam flow rate is increased.
6. The method for controlling the temperature of low calorific value synthesis gas of an IGCC unit according to claim 5, characterized in that: The faults include wet syngas temperature signal fault, dry syngas flow signal fault, steam flow signal fault, heating steam flow signal fault, large feedback deviation of valve control command or large control deviation of wet syngas temperature; When any fault occurs, the interlock control circuit is switched to manual mode and the system issues an alarm.
7. The method for controlling the temperature of low calorific value synthesis gas of an IGCC unit according to claim 6, characterized in that: When the fault is eliminated, the operator switches the control circuit to the automatic state; The fault signal judgment criteria are signal disconnection, signal current exceeding the limit, and the deviation between redundant signals greater than the set value.
8. A low calorific value synthesis gas temperature control system for an IGCC unit, based on the low calorific value synthesis gas temperature control method for an IGCC unit according to any one of claims 1 to 7, characterized in that: Also includes, A filtering module, used for filtering the input signal; Subtraction module, used to perform subtraction operation on two input variables; Manual-automatic module, used to switch between manual and automatic control loops and transfer values; An addition module, used to perform addition operations on two input variables; The alarm module is used to monitor whether the input variable exceeds the limit. When the limit is exceeded, the corresponding alarm output pin is True; The quality monitoring module is used to monitor whether the input module measurement point is faulty. In case of fault, OUT is True. A logic module whose output is True when any of its inputs is True.
9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the IGCC unit low calorific value synthesis gas temperature control method according to any one of claims 1 to 7 are implemented.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the IGCC unit low calorific value synthesis gas temperature control method according to any one of claims 1 to 7 are implemented.