Natural gas and nitrogen mixed heating value control system

Abstract

The utility model relates to gas mixing field discloses a kind of natural gas and nitrogen mixed calorific value control system, including natural gas main pipeline, nitrogen main pipeline and mixer, two parallel large branch pipeline and small branch pipeline are equipped on natural gas main pipeline, and large branch pipeline, small branch pipeline and nitrogen main pipeline are connected mixer, and mixer is connected gas pipeline, and heat value analyzer is equipped on gas pipeline;Natural gas flowmeter is equipped on natural gas main pipeline, and first natural gas flow regulating valve and second natural gas flow regulating valve are respectively equipped on small branch pipeline and large branch pipeline, and nitrogen flowmeter and nitrogen flow regulating valve are equipped on nitrogen main pipeline;The valve opening degree regulating amount of first natural gas flow regulating valve is 10%~40%, and when the valve opening degree of first natural gas flow regulating valve is less than 40%, second natural gas flow regulating valve is closed.The utility model can realize the accurate control to natural gas and nitrogen mixed proportion, ensure the stability of calorific value, satisfy the continuity and safety of production.

Description

Technical Field

[0001] This utility model relates to the field of gas mixing, and more particularly to a calorific value control system for a mixture of natural gas and nitrogen. Background Technology

[0002] A steel plant's only by-product gas is blast furnace gas (calorific value 750 kcal / m³). 3 Natural gas (calorific value 8100 kcal / m³) needs to be introduced. 3 Nitrogen (0 kcal / m³) is used as supplementary fuel. The user's burner is designed for blast furnace gas. Because the calorific value of blast furnace gas differs significantly from that of natural gas, directly burning natural gas will prevent the burner from functioning properly when there is no blast furnace gas supply. Therefore, a portion of nitrogen (calorific value 0 kcal / m³) needs to be mixed in. 3 The gas is regulated by a gas mixing station to ensure that the calorific value of the mixed gas is consistent with that of the blast furnace gas, thereby meeting the requirements for continuous combustion and safety.

[0003] Due to the volatility of the production process, the demand for gas by users also fluctuates. The existing gas mixing station control system has only one adjustment method and the flow control valve has limited sensitivity. When two gases with significantly different calorific values ​​(natural gas and nitrogen) are mixed, the calorific value of the mixed gas is prone to fluctuate greatly, affecting production and safety. Utility Model Content

[0004] This invention aims to solve the technical problems existing in the prior art. Therefore, this invention provides a natural gas and nitrogen mixture calorific value control system, which achieves precise control of the mixing ratio of natural gas and nitrogen, thereby stabilizing the calorific value of the mixture.

[0005] The technical solution adopted by this utility model to solve its technical problem is:

[0006] A natural gas and nitrogen mixed calorific value control system is provided, comprising a natural gas main pipeline, a nitrogen main pipeline, and a mixer; the natural gas main pipeline has two parallel large branch pipelines and small branch pipelines, and the large branch pipelines, small branch pipelines, and nitrogen main pipeline are all connected to the mixer, the mixer is connected to a gas delivery pipeline, and a calorific value analyzer is installed on the gas delivery pipeline; a natural gas flow meter is installed on the natural gas main pipeline, and a first natural gas flow regulating valve and a second natural gas flow regulating valve are respectively installed on the small branch pipeline and the large branch pipeline; a nitrogen flow meter and a nitrogen flow regulating valve are installed on the nitrogen main pipeline; the valve opening adjustment range of the first natural gas flow regulating valve is 10% to 40%, and when the valve opening of the first natural gas flow regulating valve is less than 40%, the second natural gas flow regulating valve is closed.

[0007] In some alternative implementations, the diameter ratio of the large branch pipe to the small branch pipe is 1.5:1.

[0008] In some alternative embodiments, the natural gas pipeline and the nitrogen pipeline are also equipped with self-regulating pressure reducing valves.

[0009] In some alternative implementations, ball valves are provided on the main natural gas pipeline, branch pipelines, main branch pipelines, and main nitrogen pipeline.

[0010] In some optional embodiments, a safety valve, an electric blind valve, and an electric butterfly valve are sequentially installed on the gas supply pipeline at the outlet end of the calorific value analyzer.

[0011] In some alternative implementations, a controller is also included, which is electrically connected to the natural gas flow meter, the first natural gas flow regulating valve, the second natural gas flow regulating valve, the nitrogen flow meter, and the nitrogen flow regulating valve, respectively.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] This invention achieves precise control of the mixing ratio of natural gas and nitrogen by setting two parallel small and large branch pipelines on the main natural gas pipeline and relying on the first and second natural gas flow regulating valves to regulate the natural gas flow, thus ensuring the stability of the calorific value of the mixed gas and meeting the requirements of production continuity and safety. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0015] Figure 1 This is a schematic diagram of the structure of the natural gas and nitrogen mixed calorific value control system provided by this utility model.

[0016] The attached diagram lists the components represented by each number as follows:

[0017] 1—Main natural gas pipeline, 1a—Major branch pipeline, 1b—Minor branch pipeline, 2—Main nitrogen pipeline, 3—Mixer, 4—Calorific value analyzer, 5—Controller, 6—Natural gas flow meter, 7—First natural gas flow regulating valve, 8—Second natural gas flow regulating valve, 9—Nitrogen flow meter, 10—Nitrogen flow regulating valve, 11—Self-operated pressure reducing valve, 12—Ball valve, 13—Safety valve, 14—Electric blind flange valve, 15—Electric butterfly valve. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0020] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0021] Furthermore, the terms "first," "second," etc., used in this utility model are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. The terms "installed," "connected," and "joined" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0022] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0023] Example 1

[0024] As attached Figure 1 As shown, this embodiment provides a natural gas and nitrogen mixed calorific value control system, including a natural gas main pipeline 1, a nitrogen main pipeline 2, a mixer 3, a calorific value analyzer 4, and a controller 5, wherein:

[0025] The main natural gas pipeline 1 is equipped with two parallel branch pipelines 1a and 1b, with the diameter of the main branch pipeline 1a being larger than that of the 1b branch pipeline. Preferably, the diameter ratio of the main branch pipeline 1a to the 1b branch pipeline is 1.5:1. The main branch pipeline 1a, the 1b branch pipeline, and the main nitrogen pipeline 2 are all connected to a mixer 3. The mixer 3 is connected to a gas delivery pipeline, which is equipped with a calorific value analyzer 4 (e.g., a DN400 infrared spectrometer) for detecting the calorific value of the mixed gas.

[0026] The main natural gas pipeline 1 is equipped with a natural gas flow meter 6 for real-time monitoring of natural gas flow. The small branch pipeline 1b and the large branch pipeline 1a are respectively equipped with a first natural gas flow regulating valve 7 and a second natural gas flow regulating valve 8 for regulating the natural gas flow in the small branch pipeline and the large branch pipeline, respectively. The main nitrogen pipeline 2 is equipped with a nitrogen flow meter 9 and a nitrogen flow regulating valve 10 for real-time monitoring of nitrogen flow and regulation of nitrogen flow, respectively.

[0027] The controller 5 is electrically connected to the natural gas flow meter 6, the first natural gas flow regulating valve 7, the second natural gas flow regulating valve 8, the nitrogen flow meter 9, and the nitrogen flow regulating valve 10 for system control. In this embodiment, the controller can be a PLC controller or a microcontroller or other control components.

[0028] The valve opening adjustment range of the first natural gas flow regulating valve 7 is 10% to 40%, and when the valve opening of the first natural gas flow regulating valve 7 is less than 40%, the second natural gas flow regulating valve 8 is closed. That is, in the initial stage, the opening of the first natural gas flow regulating valve is set to 10%, and the second natural gas flow regulating valve is in the closed state; during system operation, when the opening of the first natural gas flow regulating valve reaches 40% and remains fixed, the second natural gas flow regulating valve will start to be used according to the ratio, thereby increasing the adjustable range of natural gas flow and the sensitivity of adjustment, and realizing precise control of the mixing ratio of natural gas and nitrogen.

[0029] In practice, at the initial stage of system operation, the second natural gas flow regulating valve is closed, and the opening degree of the first natural gas flow regulating valve is set to 10%. The controller synchronously controls the nitrogen flow regulating valve to participate in the proportional automatic adjustment according to the set calorific value of the mixed gas. As the gas consumption increases, the controller controls the opening degree of the first natural gas flow regulating valve to 40% and keeps it fixed. If the gas consumption continues to increase, the controller controls the second natural gas flow regulating valve to open.

[0030] Preferably, in this embodiment, a self-operated pressure reducing valve 11 is also provided on the natural gas main pipeline 1 and the nitrogen main pipeline 2. The self-operated pressure reducing valve can adjust the opening degree of the valve opening and closing parts by means of the downstream pressure, so that the downstream pressure is kept within a certain range, and the outlet pressure is kept within the set range when the inlet pressure changes continuously.

[0031] Preferably, in this embodiment, ball valves 12 are provided on the main natural gas pipeline 1, the small branch pipeline 1b, the large branch pipeline 1a, and the nitrogen main pipeline 2, respectively, for cutting off the main natural gas pipeline, the small branch pipeline, the large branch pipeline, and the nitrogen main pipeline.

[0032] Preferably, in this embodiment, a safety valve 13, an electric blind valve 14, and an electric butterfly valve 15 are sequentially provided on the gas supply pipeline at the outlet end of the calorific value analyzer. The safety valve can effectively prevent pipeline overpressure and ensure the safety of the pipeline system; the electric blind valve and the electric butterfly valve can jointly realize the system's entry and exit.

[0033] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made using the content of this utility model specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A natural gas and nitrogen mixing calorific value control system, comprising a natural gas main pipeline, a nitrogen main pipeline, and a mixer; characterized in that: The main natural gas pipeline is provided with two parallel large branch pipelines and small branch pipelines. The large branch pipelines, small branch pipelines and the main nitrogen pipeline are all connected to a mixer. The mixer is connected to a gas delivery pipeline. A calorific value analyzer is provided on the gas delivery pipeline. The main natural gas pipeline is equipped with a natural gas flow meter, and the small branch pipeline and the large branch pipeline are respectively equipped with a first natural gas flow regulating valve and a second natural gas flow regulating valve. The main nitrogen pipeline is equipped with a nitrogen flow meter and a nitrogen flow regulating valve. The valve opening adjustment range of the first natural gas flow regulating valve is 10% to 40%, and when the valve opening of the first natural gas flow regulating valve is less than 40%, the second natural gas flow regulating valve is closed.

2. The natural gas and nitrogen mixed calorific value control system according to claim 1, characterized in that: The diameter ratio of the large branch pipe to the small branch pipe is 1.5:

1.

3. The natural gas and nitrogen mixed calorific value control system according to claim 1, characterized in that: The natural gas pipeline and nitrogen pipeline are also equipped with self-regulating pressure reducing valves.

4. The natural gas and nitrogen mixed calorific value control system according to claim 1, characterized in that: Ball valves are installed on the main natural gas pipeline, small branch pipelines, large branch pipelines, and nitrogen main pipeline.

5. The natural gas and nitrogen mixed calorific value control system according to claim 1, characterized in that: The gas supply pipeline is also equipped with a safety valve, an electric blind valve, and an electric butterfly valve in sequence at the outlet end of the calorific value analyzer.

6. The natural gas and nitrogen mixed calorific value control system according to any one of claims 1 to 5, characterized in that: It also includes a controller, which is electrically connected to the natural gas flow meter, the first natural gas flow regulating valve, the second natural gas flow regulating valve, the nitrogen flow meter, and the nitrogen flow regulating valve.

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