A furnace temperature optimization control method based on fuel gas component change, a DCS control system and a fuel gas heating furnace

Abstract

The present application relates to a kind of furnace temperature optimization control method based on fuel gas component change, DCS control system and fuel gas heating furnace, comprising: S1, according to preset time interval, fuel gas component sensor is set at fuel gas feed pipe, and real-time component information of fuel gas is obtained;S2, based on the real-time component information of fuel gas and fuel gas flow set value, obtain fuel gas optimization flow value;S3, according to optimization control switching logic, fuel gas feed flow is set according to the fuel gas optimization flow value or the fuel gas flow set value by fuel gas flow controller according to optimization control switching logic.This application compared with traditional temperature flow control scheme, control cycle is short, and adjustment speed is fast, and control difficulty is reduced;After the change of fuel gas component, still can provide stable heat by optimizing fuel gas feed flow, then keep furnace temperature constant, improve system stability, also reduce operator operating intensity.

Description

Technical Field

[0001] This invention relates to a furnace temperature optimization control method based on changes in fuel gas composition, a DCS control system, and a fuel gas heating furnace. Background Technology

[0002] As the largest and most complex utility system in the petrochemical industry, the fuel gas system involves almost all production units within the plant. Its main function is to provide a heat source for the reactors that require heating. Each reactor maintains the required temperature for the reaction products through the heat released from the combustion of fuel gas. Fuel gas mainly originates from small-molecule gases in various byproducts of the production process, primarily consisting of methane, ethane, CO, nitrogen, hydrogen, hydrogen sulfide, and water. Among these, methane, ethane, CO, hydrogen, and hydrogen sulfide are combustible gases, while nitrogen and water are non-combustible gases. The combustible gases in the fuel gas react with oxygen in the reactor furnace, releasing heat; the non-combustible gases do not react in the furnace and are discharged with the exhaust gas after the reaction. As the proportion of non-combustible gases in the fuel gas increases, the heat released from combustion at the same flow rate decreases, thus affecting the temperature balance of each reactor.

[0003] Because the combustion and heating of fuel gas is a temperature transfer process involving thermal radiation, the combustion range of fuel gas will change with the change of furnace pressure and composition. It is impossible to directly measure the combustion temperature of fuel gas using a corresponding temperature sensor. In industry, there are three main control methods for fuel gas: single-loop flow control scheme, temperature flow control scheme, and calorific value flow control scheme.

[0004] Single-loop flow control is a method that reduces temperature fluctuations by maintaining a constant fuel gas feed flow rate. It involves installing a flow sensor on the fuel gas feed line, using the real-time fuel gas flow rate as negative feedback to construct a single-loop closed-loop flow control circuit. Stable fuel gas flow can be achieved by adjusting the flow controller parameters. However, this method is susceptible to temperature fluctuations when changes in fuel gas composition or process conditions occur, potentially leading to insufficient heat generation from combustion in the reactor and impacting the reaction process. Furthermore, the flow setpoint is manually set by the operator, requiring significant experience and increasing the learning curve and workload. Despite this, it is the most basic control scheme used in most plants, with subsequent temperature and calorific value flow control based on improved versions of single-loop flow control.

[0005] Temperature and flow control does not directly measure the combustion temperature of fuel gas. Instead, it is a control scheme that compensates for the feed flow of fuel gas by measuring the outlet temperature of the reactants in the reactor. The temperature measurement in this scheme is at the very downstream end of the entire reaction process, which is significantly lagging. Moreover, it is affected by multiple factors such as the reaction process, the feeding principle, and the feed flow of fuel gas. The direct coupling between the variables is high, making adjustment difficult and operation complex.

[0006] Calorific value flow control is a control scheme that compensates for feed flow by measuring the calorific value coefficient of fuel gas. The calorific value sensor can measure the calorific value of the feed flow and use it as a reference to compensate the feed flow. However, the calorific value sensor has certain limitations. On the one hand, because the calorific value sensor has a long testing time, it will bring a large lag to the system. When the composition of the fuel gas changes, it cannot quickly adjust according to the composition of the fuel gas, thus reducing the control effect. On the other hand, because the composition of the fuel gas itself is complex and highly variable, the complex combination of components will reduce the measurement accuracy of the calorific value sensor, and thus affect the entire calorific value flow control system. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a furnace temperature control method, a DCS control system and a fuel gas heating furnace based on changes in fuel gas composition. This solution measures the composition of the fuel gas and optimizes the fuel gas feed flow rate according to the changes in the fuel gas composition, thereby achieving the effect of stable control of the furnace temperature, while also reducing the operator's workload.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0011] In a first aspect, embodiments of the present invention provide a furnace temperature control method based on changes in fuel gas composition, comprising:

[0012] S1. Real-time fuel gas composition information is obtained by a fuel gas composition sensor installed at the fuel gas inlet pipe at preset time intervals.

[0013] S2. Based on the real-time composition information of the fuel gas and the set value of the fuel gas flow rate, the optimized flow rate value of the fuel gas is obtained;

[0014] S3. According to the optimized control switching logic, the fuel gas feed flow rate is set by the fuel gas flow controller based on the optimized fuel gas flow rate value or the fuel gas flow rate set value.

[0015] Optionally, the process may further include the following before step S1:

[0016] After the fuel gas system is first put into operation and the fuel gas flow rate is stable, the initial fuel gas composition information is obtained by the fuel gas composition sensor and used as the stable fuel gas composition information.

[0017] The fuel gas flow rate setting value is determined based on the preset range of furnace temperature and the stable composition information of the fuel gas.

[0018] Optionally, after S3, the following is also included:

[0019] The fuel gas feed flow rate is acquired and displayed in real time using a flow detection sensor.

[0020] Optionally, the optimized control switching logic in S3 includes:

[0021] The optimization control switching is achieved by using an optimization control switch. When optimization control is turned on, the fuel gas feed flow rate is set using the optimized fuel gas flow rate value; otherwise, the fuel gas feed flow rate is set using the fuel gas flow rate set value.

[0022] Optionally, the fuel gas may comprise one or more of the following gases:

[0023] Methane, ethane, hydrogen, carbon monoxide, and nitrogen.

[0024] Optionally, S2 includes:

[0025] S21. Obtain information on the stable components of fuel gas;

[0026] S22. Calculate the optimized flow rate of the fuel gas using the following formula:

[0027] =1-( )×

[0028] in, Optimize the flow rate value for the fuel gas. Set the fuel gas flow rate value. - Information on the stable components of the fuel gas, in order: methane, ethane, hydrogen, carbon monoxide, and nitrogen. - The real-time composition information of the fuel gas, in order, is methane, ethane, hydrogen, carbon monoxide, and nitrogen.

[0029] In a second aspect, the present invention provides a DCS control system for controlling a fuel gas heating furnace, including a furnace temperature control function block, wherein the furnace temperature control function block is capable of implementing any of the furnace temperature optimization control methods based on changes in fuel gas composition described in the first aspect above.

[0030] Thirdly, the present invention provides a fuel gas heating furnace, including a fuel gas component sensor, a fuel gas flow controller, and a processor.

[0031] The fuel gas composition sensor is used to measure the proportion of each gas in the fuel gas composition and obtain fuel gas composition information;

[0032] The fuel gas flow controller is used to control the fuel gas feed flow rate based on the input fuel gas flow rate setting parameters.

[0033] The processor is used to obtain an optimized fuel gas flow rate value based on the real-time fuel gas composition information obtained by the fuel gas composition sensor at preset time intervals and the input fuel gas flow rate set value. The processor then uses the optimized fuel gas flow rate value to control the fuel gas flow controller to achieve fuel gas flow rate control based on fuel gas composition, thereby achieving furnace temperature control.

[0034] Optionally, the fuel gas component sensor includes: a methane gas measuring sensor, an ethane gas measuring sensor, a hydrogen gas measuring sensor, a carbon monoxide gas measuring sensor, and a nitrogen gas measuring sensor.

[0035] Optionally, a flow detection sensor is also included for acquiring and displaying the fuel gas feed flow rate in real time.

[0036] (III) Beneficial Effects

[0037] Compared with existing technologies, the furnace temperature optimization control method based on changes in fuel gas composition proposed in this invention has fuel gas composition measurement points located before fuel gas combustion. Compared with traditional temperature and flow control schemes, it has a shorter control cycle, faster adjustment speed, and reduced control difficulty.

[0038] The control method proposed in this invention can still provide stable heat by optimizing the fuel gas feed flow rate after the fuel gas composition changes, thereby maintaining a constant furnace temperature, improving system stability, and reducing the operator's workload. Attached Figure Description

[0039] Figure 1 A flowchart of a furnace temperature optimization control method based on fuel gas composition variation provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram illustrating the operation of controlling the fuel gas feed flow rate based on changes in fuel gas composition, according to an embodiment of the present invention. Detailed Implementation

[0041] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0042] Example 1

[0043] like Figure 1 As shown, this embodiment provides a furnace temperature optimization control method based on changes in fuel gas composition, which mainly includes the following steps:

[0044] S1. Real-time fuel gas composition information is obtained by a fuel gas composition sensor installed at the fuel gas inlet pipe at preset time intervals.

[0045] S2. Based on the real-time composition information of the fuel gas and the set value of the fuel gas flow rate, the optimized flow rate value of the fuel gas is obtained;

[0046] S3. According to the optimized control switching logic, the fuel gas feed flow rate is set by the fuel gas flow controller based on the optimized fuel gas flow rate value or the fuel gas flow rate set value.

[0047] Specifically, in practical applications, the following is included before step S1:

[0048] After the fuel gas system is first put into operation and the fuel gas flow rate is stable, the initial fuel gas composition information is obtained by the fuel gas composition sensor and used as the stable fuel gas composition information.

[0049] The fuel gas flow rate setting value is determined based on the preset range of furnace temperature and the stable composition information of the fuel gas.

[0050] like Figure 2 As shown, in practical applications, the fuel gas flow rate setpoint can be determined by the operator.

[0051] like Figure 2 As shown, in practical applications, a flow detection sensor can be used to acquire and display the real-time fuel gas feed flow rate, and this data can be fed back to the flow controller as a reference for adjusting the fuel gas feed flow rate according to the optimized fuel gas flow rate value.

[0052] The optimized control switching logic in embodiment S3 includes:

[0053] The optimization control switching is achieved by using an optimization control switch. When optimization control is turned on, the fuel gas feed flow rate is set using the optimized fuel gas flow rate value; otherwise, the fuel gas feed flow rate is set using the fuel gas flow rate set value.

[0054] like Figure 2 As shown, in practical applications, the operator can optimize the switching of the control switch according to the site conditions. When switched to downstream, the fuel gas flow setpoint set by the operator is directly sent to the flow controller, which is a single-loop flow control. When the switch is switched to upstream, the real-time fuel gas component value measured by the fuel gas component sensor is used to optimize the flow setpoint setpoint given by the operator. The optimized setpoint (i.e., the optimized fuel gas flow value) is sent to the flow controller, and the flow controller adjusts the flow according to the new setpoint.

[0055] It should be noted that, due to the complexity of fuel gas composition, measuring all components of fuel gas is costly and difficult to implement. For components that account for a very small proportion of fuel gas, they can be ignored during the combustion process. Therefore, this embodiment selects the main components of fuel gas as the optimized measurement parameters, mainly including methane, ethane, hydrogen, carbon monoxide and nitrogen as the measurement sources.

[0056] It should be noted that the five types of fuel gas components selected above should not be regarded as a limitation on the types of fuel gas components in this invention. In fact, those who implement this invention can freely choose appropriate categories to use the optimized control method of this invention according to the specific fuel gas components.

[0057] To explain embodiment S2 in more detail, the sub-steps included in S2 are described below, including:

[0058] S21. Obtain information on the stable components of fuel gas;

[0059] S22. Calculate the optimized flow rate of the fuel gas using the following formula:

[0060] =1-( )×

[0061] in, Optimize the flow rate value for the fuel gas. Set the fuel gas flow rate value. - Information on the stable components of the fuel gas, in order: methane, ethane, hydrogen, carbon monoxide, and nitrogen. - The real-time composition information of the fuel gas, in order, is methane, ethane, hydrogen, carbon monoxide, and nitrogen.

[0062] The furnace temperature optimization control method based on changes in fuel gas composition proposed in this embodiment uses fuel gas composition measurement points located before fuel gas combustion. Compared with traditional temperature and flow control schemes, it has a shorter control cycle, faster adjustment speed, and reduces control difficulty.

[0063] The control method proposed in this embodiment can still provide stable heat by optimizing the fuel gas feed flow rate after the fuel gas composition changes, thereby maintaining a constant furnace temperature, improving system stability, and reducing the operator's workload.

[0064] Example 2

[0065] This embodiment provides a DCS control system for controlling a fuel gas heating furnace, including a furnace temperature control function block. The furnace temperature control function block can implement any of the furnace temperature optimization control methods based on changes in fuel gas composition in Embodiment 1.

[0066] The fuel gas heater is used in conjunction with the DCS control system of this embodiment to realize fuel gas component measurement, optimized flow value calculation based on fuel gas components, and automatic control of fuel gas feed flow, ultimately achieving stable control of the furnace temperature.

[0067] Example 3

[0068] This embodiment provides a fuel gas heating furnace, including:

[0069] Fuel gas composition sensor, fuel gas flow controller, and processor.

[0070] The fuel gas composition sensor is used to measure the proportion of each gas in the fuel gas composition and obtain fuel gas composition information;

[0071] The fuel gas flow controller is used to control the fuel gas feed flow rate based on the input fuel gas flow rate setting parameters.

[0072] The processor is used to obtain an optimized fuel gas flow rate value based on the real-time fuel gas composition information obtained by the fuel gas composition sensor at preset time intervals and the input fuel gas flow rate set value. The processor then uses the optimized fuel gas flow rate value to control the fuel gas flow controller to achieve fuel gas flow rate control based on fuel gas composition, thereby achieving furnace temperature control.

[0073] The fuel gas component sensors include: a methane gas measurement sensor, an ethane gas measurement sensor, a hydrogen gas measurement sensor, a carbon monoxide gas measurement sensor, and a nitrogen gas measurement sensor.

[0074] It also includes a flow detection sensor for acquiring and displaying the fuel gas feed flow rate in real time.

[0075] It should be explained that the description of the fuel gas composition sensor here does not constitute a limitation on its composition. In specific implementation, the implementer can select a gas measurement sensor that matches the actual fuel gas composition to form the fuel gas composition sensor.

[0076] It should be noted that, in the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0077] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Clearly, those skilled in the art can make various modifications and variations to the invention without departing from its spirit and scope.

Claims

1. A furnace temperature optimization control method based on changes in fuel gas composition, characterized in that, The method includes: S1. Real-time fuel gas composition information is obtained by a fuel gas composition sensor installed at the fuel gas inlet pipe at preset time intervals. S2. Based on the real-time composition information of the fuel gas and the set value of the fuel gas flow rate, the optimized flow rate value of the fuel gas is obtained; S3. According to the optimized control switching logic, the fuel gas flow controller sets the fuel gas feed flow rate according to the optimized fuel gas flow rate value or the fuel gas flow rate set value, and obtains the real-time feed flow rate through the flow detection sensor and feeds it back to the flow controller as a reference for adjusting the fuel gas feed flow rate according to the optimized fuel gas flow rate value. Before S1, the following also applies: After the fuel gas system is first put into operation and the fuel gas flow rate is stable, the initial fuel gas composition information is obtained by the fuel gas composition sensor and used as the stable fuel gas composition information. S2 includes: S21. Obtain information on the stable components of fuel gas; S22. Calculate the optimized flow rate of the fuel gas using the following formula: =1-( )× ； in, Optimize the flow rate value for the fuel gas; Set the fuel gas flow rate to a specified value; Information on the stable components of methane fuel gas; Information on the stable components of ethane fuel gas; Information on the stable components of hydrogen fuel gas; Information on the stable components of fuel gas containing carbon monoxide; Information on the stable components of nitrogen fuel gas; Real-time composition information for methane fuel gas; Real-time composition information for ethane fuel gas; Real-time composition information for hydrogen fuel gas; Real-time composition information of fuel gas containing carbon monoxide; This provides real-time composition information for nitrogen fuel gas.

2. The method according to claim 1, characterized in that, Before S1, the following also applies: The fuel gas flow rate setting value is determined based on the preset range of furnace temperature and the stable composition information of the fuel gas.

3. The method according to claim 1, characterized in that, Following S3, the following also includes: The fuel gas feed flow rate is acquired and displayed in real time using a flow detection sensor.

4. The method according to claim 2, characterized in that, The optimized control switching logic in S3 includes: The optimization control switching is achieved by using an optimization control switch. When optimization control is turned on, the fuel gas feed flow rate is set using the optimized fuel gas flow rate value; otherwise, the fuel gas feed flow rate is set using the fuel gas flow rate set value.

5. A DCS control system, characterized in that, The furnace is used to control a fuel gas heating furnace, including a furnace temperature control function block, which is capable of implementing the furnace temperature optimization control method based on the change of fuel gas composition as described in any one of claims 1-4.

6. A fuel gas heating furnace, characterized in that, This includes a fuel gas composition sensor, a flow detection sensor, a fuel gas flow controller, and a processor. The fuel gas composition sensor is used to measure the proportion of each gas in the fuel gas composition and obtain fuel gas composition information; The flow detection sensor is used to acquire and display the fuel gas feed flow rate in real time and feed it back to the fuel gas flow controller as a reference for adjusting the fuel gas feed flow rate according to the optimized fuel gas flow rate value. The fuel gas flow controller is used to control the fuel gas feed flow rate based on the input fuel gas flow rate setting parameters. The processor is configured to acquire initial fuel gas composition information via the fuel gas composition sensor after the fuel gas system has been running for the first time and the fuel gas flow rate has stabilized, and use this information as stable fuel gas composition information; based on the real-time fuel gas composition information acquired by the fuel gas composition sensor at preset time intervals, combined with the stable fuel gas composition information and the input fuel gas flow rate setpoint, the processor obtains an optimized fuel gas flow rate value. =1-( )× ； in, Optimize the flow rate value for the fuel gas; Set the fuel gas flow rate to a specified value; Information on the stable components of methane fuel gas; Information on the stable components of ethane fuel gas; Information on the stable components of hydrogen fuel gas; Information on the stable components of fuel gas containing carbon monoxide; Information on the stable components of nitrogen fuel gas; Real-time composition information for methane fuel gas; Real-time composition information for ethane fuel gas; Real-time composition information for hydrogen fuel gas; Real-time composition information of fuel gas containing carbon monoxide; Real-time composition information for nitrogen fuel gas; The optimized flow rate value of the fuel gas is used to control the fuel gas flow controller to achieve fuel gas flow control based on fuel gas composition, thereby realizing furnace temperature control.

7. The fuel gas heating furnace according to claim 6, characterized in that, The fuel gas component sensors include: a methane gas measurement sensor, an ethane gas measurement sensor, a hydrogen gas measurement sensor, a carbon monoxide gas measurement sensor, and a nitrogen gas measurement sensor.

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