Natural gas calorific value stabilizing system for kiln and using method

Abstract

The invention discloses a natural gas calorific value stabilizing system for a kiln and a using method, and relates to the field of high-aluminum-silicon cover plate glass manufacturing equipment.The system comprises a municipal natural gas storage tank, a liquefied natural gas storage tank, a calorific value detector, a natural gas flow control valve, a DCS control system and a mixing tank; a municipal natural gas storage tank and a liquefied natural gas storage tank are connected in parallel with a mixing tank and are connected with the mixing tank through natural gas flow control valves respectively, and the municipal natural gas storage tank, the liquefied natural gas storage tank and the natural gas flow control valves are provided with heat value detectors in a matched mode respectively. Each heat value detector is in communication connection with the DCS control system, and each natural gas flow control valve is in communication connection with the DCS control system. The problem that in the prior art, the natural gas heat value is adjusted only when the kiln process fluctuates, and the natural gas heat value cannot be stabilized for a long time can be solved.

Description

Technical Field

[0001] This invention relates to the field of high-alumina-silicon cover glass manufacturing equipment, specifically to a natural gas calorific value stabilization system for kilns and its usage method. Background Technology

[0002] In the overflow process for producing cover glass, the furnace heat source comes from electric melting and natural gas, with natural gas accounting for approximately 30% to 40% of the heat. The manufacturing process requires high temperature stability in the furnace; temperature fluctuations can cause sudden defects, affecting product quality. When using municipal natural gas, the composition varies from place to place, resulting in different calorific values, and these values ​​also differ between seasons, generally ranging from 8300 to 8800 kcal / Nm³. 3 Typically, changes in calorific value are only identified and adjustments made when kiln processes fluctuate. This process is very delayed and makes it impossible to consistently maintain the kiln process within its optimal range. Furthermore, the adjustment method involves stabilizing the natural gas heat by adjusting the burner flow rate, and frequent changes in burner flow rate significantly impact the lifespan of the burner bricks, the kiln arch, and the exhaust fan. Summary of the Invention

[0003] The purpose of this invention is to provide a natural gas calorific value stabilization system and method for use in kilns, in order to solve the problem that the existing technology only adjusts the natural gas calorific value when the kiln process fluctuates, and cannot stabilize the natural gas calorific value in the long term.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: In the first aspect, a natural gas calorific value stabilization system for kilns includes: a municipal natural gas storage tank, a liquefied natural gas storage tank, a calorific value detector, a natural gas flow control valve, a DCS (Distributed Control System) control system, and a mixing tank; A municipal natural gas storage tank and a liquefied natural gas storage tank are connected in parallel to form a mixing tank. The municipal natural gas storage tank and the liquefied natural gas storage tank are connected to the mixing tank through natural gas flow control valves. The municipal natural gas storage tank, the liquefied natural gas storage tank, and the natural gas flow control valves are each equipped with a calorific value detector. Each calorific value detector is communicatively connected to the DCS control system, and each natural gas flow control valve is communicatively connected to the DCS control system.

[0005] In some implementations, the municipal natural gas storage tank, liquefied natural gas storage tank, and mixing tank are made of stainless steel.

[0006] Secondly, a method of using a natural gas calorific value stabilization system for kilns, based on the natural gas calorific value stabilization system, includes the following steps: The calorific value of natural gas in municipal natural gas storage tanks, liquefied natural gas storage tanks, and mixing tanks is detected online using a calorific value detector to obtain the calorific value of municipal natural gas, liquefied natural gas, and the actual calorific value of the mixed natural gas. At the same time, the flow rates of municipal natural gas storage tanks and liquefied natural gas storage tanks are detected to obtain the flow rates of municipal natural gas and liquefied natural gas. The calorific value of municipal natural gas, the calorific value of liquefied natural gas, the calorific value of actual mixed natural gas, the flow rate of municipal natural gas, and the flow rate of liquefied natural gas are transmitted to the DCS control system to calculate the difference between the preset calorific value of mixed natural gas and the actual calorific value of mixed natural gas. When the difference is greater than a preset threshold, the flow rates of the municipal natural gas storage tank and the liquefied natural gas storage tank are adjusted by the natural gas flow control valve, and the above steps are repeated until the difference is less than the preset threshold.

[0007] In some embodiments, the calorific value of the municipal natural gas ranges from 8300 to 8800 kcal / Nm³. 3 The calorific value of the liquefied natural gas ranges from 9200 to 9500 kcal / Nm³. 3 .

[0008] In some embodiments, the calorific value of the preset mixed natural gas ranges from 8900 to 9100 kcal / Nm³. 3 .

[0009] In some implementations, the preset calorific value of the mixed natural gas is calculated using the following formula:

[0010] in, To preset the calorific value of the mixed natural gas, The calorific value of municipal natural gas, The calorific value of liquefied natural gas. This represents the volume percentage of municipal natural gas in the blended natural gas. This represents the volume ratio of liquefied natural gas in the mixed natural gas.

[0011] In some embodiments, the volume ratio of the municipal natural gas in the mixed natural gas is calculated by the following formula:

[0012] in, For municipal natural gas flow, This represents the flow rate of liquefied natural gas.

[0013] In some embodiments, the volume ratio of the liquefied natural gas in the mixed natural gas is calculated by the following formula:

[0014] in, For municipal natural gas flow, This represents the flow rate of liquefied natural gas.

[0015] In some implementations, the preset threshold is 0.1% to 1%.

[0016] In some embodiments, the step of adjusting the flow rates of the municipal natural gas storage tank and the liquefied natural gas storage tank via the natural gas flow control valve is specifically implemented by adjusting the municipal natural gas flow rate and the liquefied natural gas flow rate using the following formula:

[0017] in, For liquefied natural gas flow rate, For municipal natural gas flow, To preset the calorific value of the mixed natural gas, The calorific value of municipal natural gas, This refers to the calorific value of liquefied natural gas.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a natural gas calorific value stabilization system for kilns, comprising a municipal natural gas storage tank and a liquefied natural gas (LNG) storage tank connected in parallel to form a mixing tank. The municipal natural gas and LNG storage tanks are each connected to the mixing tank via a natural gas flow control valve. Each of the municipal natural gas storage tank, LNG storage tank, and natural gas flow control valve is equipped with a calorific value detector, and each calorific value detector and each natural gas flow control valve are communicatively connected to the DCS control system. The calorific value detectors upload data in real time, and the flow control valves receive instructions from the DCS control system, enabling real-time closed-loop control from calorific value detection to regulation. Furthermore, the parallel connection of the municipal natural gas and LNG storage tanks in the mixing tank ensures a flexible ratio of municipal natural gas and LNG. By adjusting their flow rates, the target calorific value of the mixed natural gas can be achieved, avoiding the impact of fluctuations from a single gas source.

[0019] This invention provides a method for using a natural gas calorific value stabilization system for kilns. It acquires the calorific values ​​of municipal natural gas, liquefied natural gas, and the actual mixed natural gas in real time and transmits this data to a DCS control system. This ensures the DCS control system can promptly detect calorific value fluctuations and avoids lag. By calculating the difference between the preset mixed natural gas calorific value and the actual mixed natural gas calorific value and comparing it with a preset threshold, dynamic response is achieved. This prevents the accumulation of calorific value fluctuations from causing abnormal kiln temperatures and solves the problem of product quality degradation due to calorific value fluctuations. Attached Figure Description

[0020] Figure 1A structural diagram of a natural gas calorific value stabilization system for a kiln provided in an embodiment of the present invention; Figure 2 A flowchart of a method for stabilizing the calorific value of natural gas for kilns, provided as an embodiment of the present invention.

[0021] In the diagram, 1 is a municipal natural gas storage tank; 2 is a liquefied natural gas storage tank; 3 is a calorific value detector; 4 is a natural gas flow control valve; 5 is a DCS control system; and 6 is a mixing tank. Detailed Implementation

[0022] In the following description, only certain exemplary embodiments are briefly described. The described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and descriptions are considered to be exemplary in nature and not restrictive.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0025] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] Example 1 like Figure 1 As shown, this embodiment provides a natural gas calorific value stabilization system for kilns, including: a municipal natural gas storage tank 1, a liquefied natural gas storage tank 2, a calorific value detector 3, a natural gas flow control valve 4, a DCS control system 5, and a mixing tank 6. The municipal natural gas storage tank 1 and the liquefied natural gas storage tank 2 are connected in parallel to the mixing tank 6. The municipal natural gas storage tank 1 and the liquefied natural gas storage tank 2 are each connected to the mixing tank 6 through the natural gas flow control valve 4. The municipal natural gas storage tank 1, the liquefied natural gas storage tank 2, and the natural gas flow control valve 4 are each equipped with a calorific value detector 3. Each calorific value detector 3 is communicatively connected to the DCS control system 5, and each natural gas flow control valve 4 is communicatively connected to the DCS control system 5.

[0028] The municipal natural gas storage tank 1 is a pressure vessel for storing conventional pipeline natural gas. Specifically, it can be a vertical tank equipped with a pressure reducing valve and a filter, used to supply basic fuel gas to the mixing tank 6. The liquefied natural gas storage tank 2 is an insulated storage tank for storing cryogenic liquefied natural gas. Specifically, it can employ a vacuum powder insulation structure, converting the gas into a gaseous state before inputting it into the mixing tank 6. The calorific value detector 3 is a sensor for online measurement of the calorific value of the gas. Specifically, it can be a detection device based on gas chromatography analysis or combustion heat calculation, collecting real-time calorific value data from each gas source and the mixed gas. The natural gas flow control valve 4 is an actuator for regulating the gas flow rate. Specifically, it can be an electric regulating valve or a proportional valve, receiving instructions from the DCS control system to adjust its opening. The DCS control system is a distributed control system, specifically integrating a data acquisition module, a calculation module, and a control signal output module to realize calorific value calculation and flow regulation command generation. The mixing tank 6 is a gas mixing container, specifically employing a multi-chamber structure with internal baffles to promote uniform mixing of different gas sources.

[0029] Municipal natural gas storage tank 1 and liquefied natural gas storage tank 2 are connected to mixing tank 6 via independent pipelines, forming a parallel gas supply path. Calorific value detectors 3 are installed at the outlets of each storage tank and the mixing tank, continuously monitoring the calorific values ​​of municipal natural gas, liquefied natural gas, and the mixed gas. The DCS control system 5 receives real-time data from each detection point and calculates the deviation between the preset mixed calorific value and the actual value. When the deviation exceeds the allowable range, the system generates a flow adjustment command based on the calorific value balance formula, changing the mixing ratio of municipal natural gas and liquefied natural gas by adjusting the opening of the natural gas flow control valves 4 on the two gas source pipelines. This process forms a closed-loop control, maintaining a stable mixed gas calorific value without manual intervention.

[0030] The municipal natural gas storage tank 1, the liquefied natural gas storage tank 2, and the mixing tank 6 are all made of stainless steel; the calorific value detector 3 detects the calorific value of municipal natural gas, liquefied natural gas, and the actual calorific value of the mixed natural gas, and uploads the detection data to the DCS control system 5; the natural gas flow control valve 4 is connected to the DCS control system 5, and can adjust the flow rate of municipal natural gas and liquefied natural gas according to the system input data. The flow rate of municipal natural gas is manually controlled, while the flow rate of liquefied natural gas is automatically controlled.

[0031] Compared to existing technologies, traditional methods rely on a single gas source to passively adjust the lance flow rate. The solution provided in this embodiment, however, actively compensates for calorific value fluctuations through dual-source mixing, eliminating the direct impact of calorific value differences on kiln temperature. Existing technologies require manual adjustments only after kiln process abnormalities occur; this solution achieves preventative adjustment through real-time monitoring and automatic control, avoiding temperature fluctuations. Existing technologies frequently change the lance flow rate, leading to equipment wear; this solution reduces the frequency of lance adjustments by optimizing the calorific value of the mixed gas, extending the lifespan of combustion system components. Through the above technical solutions, this application achieves continuous stability of the mixed gas calorific value, effectively suppressing kiln process temperature fluctuations and reducing product defect rates. The system's automatic adjustment mechanism replaces manual operation, eliminating response lag and ensuring process parameters remain within a controllable range. By optimizing the gas mixing ratio instead of frequent lance flow rate adjustments, wear on combustion system mechanical components is reduced, extending equipment maintenance cycles.

[0032] Example 2 like Figure 2 As shown, this embodiment provides a system for stabilizing the calorific value of natural gas in kilns and a method for using it, including the following steps: S1, the calorific value of natural gas in municipal natural gas storage tank 1, liquefied natural gas storage tank 2 and mixing tank 6 is detected online by calorific value detector 3 to obtain the calorific value of municipal natural gas, liquefied natural gas and actual mixed natural gas; at the same time, the flow rate of municipal natural gas storage tank 1 and liquefied natural gas storage tank 2 is detected to obtain the municipal natural gas flow rate and liquefied natural gas flow rate. S2, transmit the calorific value of municipal natural gas, calorific value of liquefied natural gas, calorific value of actual mixed natural gas, municipal natural gas flow rate and liquefied natural gas flow rate to DCS control system 5, and calculate the difference between the preset calorific value of mixed natural gas and the actual calorific value of mixed natural gas; S3, when the difference is greater than the preset threshold, adjust the flow rate of municipal natural gas storage tank 1 and liquefied natural gas storage tank 2 through natural gas flow control valve 4, and repeat the above steps until the difference is less than the preset threshold.

[0033] Specifically, the calorific value of the municipal natural gas is 8300~8800 kcal / Nm³. 3The calorific value of liquefied natural gas is 9200~9500 kcal / Nm³. 3 The calorific value is set at 8900~9100 kcal / Nm³. 3 .

[0034] Specifically, the preset threshold σ is 0.1~1%.

[0035] Specifically, the preset calorific value of the mixed natural gas is calculated using the following formula:

[0036] in, The preset calorific value of the mixed natural gas (unit: kcal / Nm³) 3 ), The calorific value of municipal natural gas (unit: kcal / Nm³) 3 ), Calorific value of liquefied natural gas (unit: kcal / Nm³) 3 ), This represents the volume percentage of municipal natural gas in the blended natural gas. This represents the volume ratio of liquefied natural gas in the mixed natural gas.

[0037] Specifically, the volume is: , For the volume of mixed natural gas, Municipal natural gas flow rate (unit: m³) 3 / h), : Liquid natural gas flow rate (unit: m³) 3 / h), A certain period of time.

[0038] Specifically, the volume ratio of municipal natural gas in the mixed natural gas is calculated using the following formula:

[0039] in, For municipal natural gas flow, This represents the flow rate of liquefied natural gas.

[0040] The volume ratio of the liquefied natural gas in the mixed natural gas is calculated by the following formula:

[0041] in, For municipal natural gas flow, This represents the flow rate of liquefied natural gas.

[0042] Specifically, the step of adjusting the flow rates of municipal natural gas storage tank 1 and liquefied natural gas storage tank 2 via natural gas flow control valve 4 is specifically achieved by adjusting the municipal natural gas flow rate and liquefied natural gas flow rate using the following formula:

[0043] in, For liquefied natural gas flow rate, For municipal natural gas flow, To preset the calorific value of the mixed natural gas, The calorific value of municipal natural gas, This refers to the calorific value of liquefied natural gas.

[0044] The working principle of this embodiment is as follows: A calorific value detector 3 is installed at the inlet of the mixing tank 6 to monitor the calorific value of municipal natural gas and liquefied natural gas in real time. Simultaneously, the actual mixed calorific value is detected at the outlet of the mixing tank 6. After the flow rate data and calorific value data are synchronously transmitted to the DCS control system, the theoretical mixing ratio is calculated based on a preset target range for the mixed natural gas calorific value, and compared with the actual mixed calorific value of the natural gas. When a deviation exceeding the process allowable threshold (i.e., the preset threshold) is detected, the system automatically generates a flow rate adjustment command, dynamically adjusting the input ratio of the two gas sources through the natural gas flow control valve 4, forming a continuous feedback adjustment cycle. For example, when the calorific value of the municipal natural gas decreases, causing the mixed calorific value to deviate from the target, the system can increase the blending ratio of liquefied natural gas, maintaining a stable mixed calorific value through complementary adjustment of high and low calorific value gas sources.

[0045] This embodiment is applied in a real-world scenario as follows: The calorific value of municipal natural gas is 8700 kcal / Nm³. 3 The calorific value of liquefied natural gas is 9300 kcal / Nm³. 3 The municipal natural gas flow rate is 50 Nm³. 3 / h, liquefied natural gas flow rate is 50 Nm 3 / h, with a set calorific value of 9000 kcal / Nm 3 The threshold σ is set to 0.5%. The calorific value of municipal natural gas fluctuates to 8400 kcal / Nm³. 3 The calculated difference between the calorific value of the mixed natural gas and the set value is 1.7%, which exceeds the preset threshold σ of 0.5%, prompting the DCS control system to intervene and adjust. The calculated liquefied natural gas flow rate is 100 Nm³. 3 / h, issues and executes the command, and pauses the adjustment when the final difference is less than the threshold.

[0046] The solution provided in this embodiment integrates the detected values ​​into the DCS control system. The DCS system monitors the difference between the calorific value of the mixed natural gas and the set calorific value. If the calorific value of the natural gas fluctuates and the difference exceeds a preset threshold, the DCS system intervenes to adjust the liquefied natural gas flow control valve, achieving stable calorific value control and eliminating the problem of product quality degradation caused by calorific value fluctuations. Compared with existing technologies, traditional methods compensate for calorific value fluctuations by directly adjusting the combustion gun flow rate, leading to frequent pressure changes in the gas delivery pipeline and accelerating the formation of thermal shock cracks in the burner bricks. In contrast, this embodiment precisely controls the mixing ratio through mathematical modeling, keeping the total flow rate of the combustion gun constant. Calorific value stability is achieved only by adjusting the supply ratio of the two gas sources, fundamentally avoiding the mechanical impact of drastic flow fluctuations on the combustion system. This effectively solves the problem of kiln temperature fluctuations caused by differences in the calorific values ​​of the gas sources, while eliminating the wear effect on combustion equipment caused by traditional flow regulation methods. This allows the kiln heat source supply system to maintain process temperature stability while extending the service life of key components. Furthermore, the gas flow rate does not need to be adjusted during the use of the kiln, which can effectively reduce kiln process fluctuations, reduce refractory material erosion, and extend the kiln's lifespan.

[0047] As is known from common technical knowledge, the present invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones; all modifications within the scope of the present invention or equivalent to the scope of the present invention are included in the present invention.

Claims

1. A natural gas heating value stabilization system for a kiln, characterized by, The system comprises: a municipal natural gas storage tank (1), a liquid natural gas storage tank (2), a calorific value detector (3), a natural gas flow control valve (4), a DCS control system (5) and a mixing tank (6); the municipal natural gas storage tank (1) and the liquid natural gas storage tank (2) are connected in parallel to the mixing tank (6), the municipal natural gas storage tank (1) and the liquid natural gas storage tank (2) are connected to the mixing tank (6) through the natural gas flow control valve (4) respectively, the municipal natural gas storage tank (1), the liquid natural gas storage tank (2) and the natural gas flow control valve (4) are respectively equipped with the calorific value detector (3), each calorific value detector (3) is communicatively connected to the DCS control system (5), and each natural gas flow control valve (4) is communicatively connected to the DCS control system (5).

2. A natural gas heating value stabilizing system for a kiln according to claim 1, characterized in that, The municipal natural gas storage tank (1), the liquid natural gas storage tank (2) and the mixing tank (6) are made of stainless steel.

3. A method of using a natural gas heating value stabilization system for a kiln, characterized by, The natural gas calorific value stabilizing system according to any one of claims 1-2 comprises the following steps: on-line detection of the natural gas calorific value of the municipal natural gas storage tank (1), the liquid natural gas storage tank (2) and the mixing tank (6) is performed by the calorific value detector (3) to obtain the municipal natural gas calorific value, the liquid natural gas calorific value and the actual mixed natural gas calorific value; the flow rates of the municipal natural gas storage tank (1) and the liquid natural gas storage tank (2) are detected simultaneously to obtain the municipal natural gas flow rate and the liquid natural gas flow rate; the municipal natural gas calorific value, the liquid natural gas calorific value, the actual mixed natural gas calorific value, the municipal natural gas flow rate and the liquid natural gas flow rate are transmitted to the DCS control system (5), and the difference between the preset mixed natural gas calorific value and the actual mixed natural gas calorific value is calculated; when the difference is greater than a preset threshold, the flow rates of the municipal natural gas storage tank (1) and the liquid natural gas storage tank (2) are adjusted by the natural gas flow control valve (4), and the above steps are repeated until the difference is less than the preset threshold.

4. A method of using a natural gas heating value stabilizing system for a kiln as claimed in claim 3, wherein, The city natural gas heat value ranges from 8300 to 8800 kcal / Nm 3 The liquid natural gas heat value ranges from 9200 to 9500 kcal / Nm 3 .

5. A method of using a natural gas heating value stabilizing system for a kiln as claimed in claim 3, wherein, The preset mixed natural gas calorific value ranges from 8900 to 9100 kcal / Nm 3 .

6. A method of using a natural gas heating value stabilizing system for a kiln as claimed in claim 3, wherein, the preset mixed natural gas calorific value is calculated by the following formula: wherein, is a preset mixed natural gas heating value, is a municipal natural gas heating value, is a liquid natural gas heating value, is a volume ratio of the municipal natural gas in the mixed natural gas, is a volume ratio of the liquid natural gas in the mixed natural gas.

7. A method of using a natural gas heating value stabilizing system for a kiln as claimed in claim 6, wherein, the volume ratio of the municipal natural gas in the mixed natural gas is calculated by the following formula: wherein, is the municipal natural gas flow, is the liquid natural gas flow.

8. A method of using a natural gas heating value stabilizing system for a kiln as defined in claim 6, wherein, the volume ratio of the liquid natural gas in the mixed natural gas is calculated by the following formula: wherein, is the municipal natural gas flow, is the liquid natural gas flow.

9. A method of using a natural gas heating value stabilizing system for a kiln as defined in claim 3, wherein, the preset threshold is 0.1%-1%.

10. A method of using a natural gas heating value stabilizing system for a kiln as defined in claim 3, wherein, the step of adjusting the flow rates of the municipal natural gas storage tank (1) and the liquid natural gas storage tank (2) by the natural gas flow control valve (4) is specifically adjusting the municipal natural gas flow rate and the liquid natural gas flow rate by the following formula: wherein, is the liquid natural gas flow rate, is the city gate natural gas flow rate, is the preset mixed natural gas heating value, is the city gate natural gas heating value, is the liquid natural gas heating value.

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