Method for improving efficiency of two-stage dry powder gasifier and two-stage dry powder gasifier

Abstract

The invention relates to the technical field of coal chemical industry, in particular to a method for improving the efficiency of a two-stage dry powder gasifier and the two-stage dry powder gasifier. A two-stage water cooler of the gasifier is transformed, a shrinkage opening is additionally formed in the two stage of the gasifier, an airflow path in the gasifier is optimized, airflow is gathered to a central area, a spiral rising flowing mode is formed, and the efficiency of the two-stage dry powder gasifier is improved. The residence time of the pulverized coal in a high-temperature area is prolonged, the combustion efficiency is improved, the spiral design of the necking can not only effectively gather airflow, but also form reverse rotation with main airflow in the gasification furnace, so that a medium in the gasification furnace forms disturbance, reactants are in full contact, and the stability of the airflow and the mixing effect of the pulverized coal and the airflow are enhanced; steam injection is added during second-stage coal feeding, steam injection participates in water gas reaction, the content of hydrogen and carbon monoxide in synthesis gas is increased, meanwhile, the combustion temperature is adjusted, and local overheating is prevented. And compared with single use of the necking or the steam, the combination of the necking and the steam further improves the combustion efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of coal chemical industry, in particular to a method for improving the efficiency of a two-stage dry powder gasification furnace and the two-stage dry powder gasification furnace. Background Art

[0002] The two-stage dry powder gasification furnace has the advantages of less quenching gas volume and small waste boiler heat exchange area. The temperature of the synthesis gas is lowered by adding coal to the second stage of the dry powder gasification furnace, and the temperature of the synthesis gas is lowered by the endothermic reaction of C+CO2=2CO.

[0003] The two-stage dry powder gasifier feeds coal powder in the second stage. Under the high temperature of the gasifier, carbon reacts with carbon dioxide to generate carbon monoxide. First, this reaction is an endothermic reaction and can absorb the heat of the synthesis gas. Secondly, it can also reduce the carbon dioxide in the synthesis gas and improve the reaction efficiency of the gasifier. However, in the actual production process, it is found that after the second stage of the dry powder gasifier is put into use, the temperature of the synthesis gas can be reduced, but the reaction is not sufficient, and a large amount of coal powder in the second stage escapes and does not participate in the reaction. The result is low efficiency and a large amount of residual carbon in the ash. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the first object of the present invention is to provide a method for improving the efficiency of a two-stage dry powder gasification furnace, so as to solve the problem that the efficiency of the two-stage dry powder gasification furnace is low and the residual carbon in the ash is large.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for improving the efficiency of a two-stage dry powder gasification furnace, which includes changing the direction of the flow field in the gasifier so that the upward airflow converges to the middle of the gasifier; when adding coal to the second stage, the second-stage coal powder is injected into the gasifier through the second-stage burner on the side of the gasifier, and under the disturbance of the airflow, the coal powder is distributed in the high-temperature area in the middle of the gasifier.

[0007] As a preferred solution of the method for improving the efficiency of a two-stage dry powder gasifier described in the present invention, when the airflow converges toward the middle of the gasifier, it rises in a spiral shape, and the spiral direction is opposite to the rotation direction of the airflow formed in the first-stage gasifier.

[0008] As a preferred solution of the method for improving the efficiency of a two-stage dry powder gasification furnace described in the present invention, the air flow path inside the gasifier forms a spiral upward flow pattern after passing through the second-stage contraction, and the spiral airflow ensures that the combustion products and unburned coal powder are fully mixed, and are further brought into the high-temperature zone to continue the reaction.

[0009] As a preferred solution of the method for improving the efficiency of a two-stage dry powder gasifier described in the present invention, after the second-stage coal powder enters the gasifier, steam is injected into the gasifier through the steam injection channel; the ratio of steam to second-stage coal powder is 1:3 to 1:5.

[0010] As a preferred embodiment of the method for improving the efficiency of a two-stage dry powder gasification furnace described in the present invention, the pulverized coal is mixed with boiler water during the second-stage coal feeding, and the ratio of boiler water to pulverized coal is 1:4 to 1:6.

[0011] As a preferred solution of the method for improving the efficiency of the two-stage dry powder gasification furnace described in the present invention, the steam injection angle is 45° to 60°.

[0012] The second object of the present invention is to provide a two-stage dry powder gasification furnace, which improves the efficiency of the two-stage dry powder gasification through simple structural modification.

[0013] In order to solve the above technical problems, the present invention provides the following technical solutions: a two-stage dry powder gasification furnace, comprising a second-stage necking, which is arranged above the second-stage burner of the gasification furnace, and the angle of the necking is 15° to 25°.

[0014] As a preferred solution of the two-stage dry powder gasification furnace described in the present invention, the second-stage constriction is arranged at 0.8 to 1.2 meters above the second-stage burner.

[0015] As a preferred solution of the two-stage dry powder gasifier of the present invention, the second-stage necking is in a conical shape, the necking tip is spiral, and the spiral direction is opposite to the airflow rotation direction formed by the first-stage gasifier.

[0016] As a preferred embodiment of the two-stage dry powder gasification furnace of the present invention, a steam injection channel is provided above the coal powder conveying channel, the steam injection channel is arranged longitudinally, and an opening of the steam injection channel is spaced 10 to 20 centimeters from the opening of the coal powder conveying channel.

[0017] The beneficial effects of the present invention are as follows: the present invention optimizes the airflow path in the gasifier through a two-stage necking design, so that the airflow converges to the central area, forming a spiral upward flow pattern, extending the residence time of coal powder in the high temperature zone, and improving the combustion efficiency. The spiral design of the necking can not only effectively gather the airflow, but also form a reverse rotation with the main airflow in the gasifier, so that the medium in the gasifier is disturbed, the reactants are fully contacted, the stability of the airflow and the mixing effect of coal powder and airflow are enhanced, and the design reduces the dispersion and unburned coal powder, effectively improves the completeness of combustion, and reduces the residual carbon content.

[0018] In addition, when the shrinkage design is combined with steam injection, the steam injection participates in the water-gas reaction, increases the content of hydrogen and carbon monoxide in the synthesis gas, and adjusts the combustion temperature to prevent local overheating. Compared with the use of shrinkage or steam alone, the combination of shrinkage and steam further improves the combustion efficiency, optimizes the combustible gas ratio of the synthesis gas, reduces the content of impurities such as CO2, and significantly improves the quality of the synthesis gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing 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. Among them:

[0020] Figure 1 This is the diagram of the shrinkage modification of the second-stage dry powder gasification furnace.

[0021] Figure 2 This is the structural diagram of the second-stage burner of the two-stage dry powder gasification furnace. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0023] 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.

[0024] 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 is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0025] Example 1

[0026] Reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, provides a method for improving the efficiency of a two-stage dry powder gasifier, including changing the flow field direction in the gasifier so that the upward airflow converges to the middle of the gasifier; when the second-stage coal is added, the second-stage coal powder is injected into the gasifier through the second-stage burner on the side of the gasifier, and the coal powder is distributed in the high-temperature area in the middle of the gasifier under the disturbance of the airflow;

[0027] By adjusting the airflow inside the gasifier, the upward airflow no longer flows along the furnace wall, but converges to the high-temperature area in the middle of the gasifier. This design ensures that the pulverized coal can enter the high-temperature area for reaction in a concentrated manner, avoiding inefficient combustion of the pulverized coal in the edge area. Through airflow disturbance, the pulverized coal can be effectively distributed before entering the high-temperature area, making the combustion more complete.

[0028] Specifically, when the airflow converges toward the middle of the gasifier, it rises in a spiral shape, and the spiral direction is opposite to the rotation direction of the airflow formed by the first stage of the gasifier;

[0029] The existence of the airflow convergence structure makes the airflow gather from the furnace wall to the center and reverse after passing through. This design ensures the convergence of the airflow and the control of the flow direction, making the airflow more concentrated. The reverse airflow can avoid the premature scattering of the airflow, ensure that the pulverized coal enters the high-temperature zone for reaction, and improve the combustion efficiency.

[0030] Specifically, the airflow path inside the gasifier forms a spiral upward flow pattern after the second-stage shrinkage, and the spiral airflow ensures that the combustion products are fully mixed with the unburned coal powder, and further brought into the high temperature zone for further reaction;

[0031] After the narrowing, the airflow forms a spiral upward pattern, which enhances the mixing effect of coal powder and combustion products. The spiral airflow can increase the residence time of coal powder in the high temperature area and ensure that the incompletely burned coal powder can get a chance to react again. This airflow pattern effectively improves the completeness of combustion and reduces unburned carbon residue.

[0032] Specifically, after the second-stage pulverized coal enters the gasifier, steam is injected into the gasifier through the steam injection channel; the ratio of steam to the second-stage pulverized coal is 1:3 to 1:5;

[0033] The ratio of steam to pulverized coal directly affects the efficiency and depth of gasification reaction. The appropriate ratio can adjust the combustion temperature and increase the generation of hydrogen. The introduction of steam can adjust the furnace temperature to avoid local temperature being too high or too low, thereby ensuring the stability of the combustion process and avoiding incomplete combustion caused by excessive steam. The preferred ratio is 1:4, which can ensure that the reaction between steam and pulverized coal is just right, increasing the hydrogen content without affecting the efficiency of pulverized coal too much.

[0034] Specifically, the pulverized coal during the second stage of coal feeding is mixed with boiler water, and the ratio of boiler water to pulverized coal is 1:4 to 1:6;

[0035] The ratio of water to coal powder affects the complete combustion of coal powder and the residual carbon content in the ash. Too little water cannot effectively regulate the temperature, and too much water may inhibit efficiency; the preferred ratio is 1:5, which ensures the complete combustion of coal powder while reducing the residual carbon content in the ash and optimizing the composition of the syngas.

[0036] Specifically, the steam injection angle is 45° to 60°;

[0037] The steam injection angle determines the mixing effect of steam and coal powder when they enter the furnace. Multi-angle injection can ensure that steam and coal powder are fully mixed in different directions, thereby improving the combustion reaction efficiency. The preferred injection angle is 50°, which can achieve the best steam and coal powder mixing, reduce steam waste, and improve reaction efficiency.

[0038] Example 2

[0039] Reference Figures 1-2 , which is the second embodiment of the present invention, and provides an improved two-stage dry powder gasification furnace, comprising: a second-stage constriction, arranged above the second-stage burner of the gasification furnace, and the angle of the constriction is 15° to 25°;

[0040] The two-stage constriction controls the airflow path, allowing the airflow to converge from the surroundings to the middle, concentrating the airflow direction, and increasing the airflow speed and the combustion efficiency of the pulverized coal. The constriction design ensures the combustion effect of the pulverized coal when it enters the high-temperature zone, making the combustion more concentrated and efficient. The angle of the constriction is between 15° and 25°. The preferred angle is 20°. Experiments show that 20° can effectively guide the airflow into the central area and minimize the vortex phenomenon of the airflow, which not only ensures the stability of the airflow, but also enables the pulverized coal in the airflow to burn in a concentrated manner and improve efficiency.

[0041] Specifically, the second-stage constriction is set at 0.8 to 1.2 meters above the second-stage burner. This height can ensure that the airflow is fully converged before entering the high-temperature zone, and the coal powder and gas are burned under suitable temperature and airflow conditions;

[0042] The position of the constriction affects the convergence effect of the airflow and the temperature distribution in the combustion area. Setting an appropriate height above the burner can ensure that the airflow converges before reaching the high-temperature area, thereby optimizing the combustion conditions; the preferred height is 1 meter, which is based on the distribution of airflow and temperature field analysis in the furnace. 1 meter can ensure that the airflow has enough time to adjust and concentrate during the convergence process, and fully burn the pulverized coal in the high-temperature area to improve efficiency.

[0043] Specifically, the second-stage necking is in a conical shape, the necking tip is in a spiral shape, and the spiral direction is opposite to the rotation direction of the airflow formed by the first-stage gasification furnace;

[0044] The spiral necking design can not only effectively gather the airflow, but also form a counter-rotation with the main airflow in the gasifier, so that the medium in the gasifier is disturbed, so that the reactants are fully contacted and can proceed more fully, thereby enhancing the stability of the airflow and the mixing effect of coal powder and airflow.

[0045] Specifically, a steam injection channel is provided above the pulverized coal conveying channel, the steam injection channel is arranged in the longitudinal direction, and a gap of 10 to 20 centimeters is maintained between the opening of the steam injection channel and the opening of the pulverized coal conveying channel;

[0046] The steam injection channel is arranged adjacent to the pulverized coal channel to ensure that steam and pulverized coal do not interfere with each other's transportation process before entering the gasifier. At the same time, the injection of steam helps to adjust the combustion temperature and increase the depth of the gasification reaction. The preferred interval is 15 cm. According to experiments, 15 cm can ensure the independent transportation of steam and pulverized coal, and at the same time provide sufficient space for the mixing of steam and pulverized coal, so that steam and pulverized coal can be properly mixed after entering the furnace to avoid premature reaction. In addition, the steam channel opening is kept at a certain distance from the pulverized coal transportation channel opening. This design effectively reduces the phenomenon of pulverized coal escaping directly due to high flow rate, and the buffer zone formed by the injection of steam can also optimize the distribution of pulverized coal in the furnace.

[0047] Comparative Example

[0048] According to the scheme of the present invention, an experimental verification was conducted to demonstrate the influence of the necking design and the optimization of the steam injection channel on the efficiency and the composition of the syngas. The following is the experimental data and analysis.

[0049] 1. Experimental setup

[0050] The configuration of the two-stage dry powder gasifier used in the experiment is as follows:

[0051] Narrowing design: The narrowing angle is 20° and the position is 1 meter away from the second-stage burner.

[0052] Steam injection channel: The steam injection channel is arranged longitudinally above the pulverized coal conveying channel, and the interval between the opening and the pulverized coal conveying channel opening is 15 cm to avoid interference and achieve moderate mixing of steam and pulverized coal.

[0053] Airflow path: The airflow rises in a spiral after passing through the neck, the pulverized coal burns in the high-temperature zone, and steam is injected to adjust the temperature and optimize the reaction depth.

[0054] 2. Experimental conditions

[0055] The particle size of the experimental coal powder is 40 microns, and the experiment is divided into three groups:

[0056] Experimental group 1: Neck design + steam injection

[0057] Experimental group 2: necking design only

[0058] Experimental Group 3: Steam Injection Only

[0059] Control group: no necking and steam injection

[0060] The experimental parameters are as follows:

[0061] Steam to pulverized coal ratio: 1:4

[0062] Water to coal powder ratio: 1:5

[0063] Steam injection timing: 0.3 seconds after pulverized coal enters the furnace

[0064] Steam injection angle: 50°

[0065] Furnace temperature: 1200℃ to 1350℃

[0066] 3. Experimental Data

[0067]

[0068] Syngas gas composition (dry basis):

[0069] Experimental group 1 (shrinkage + steam injection)

[0070] Element content(%) <![CDATA[H2]]> 47.5 CO 35.2 <![CDATA[CO2]]> 12.5 <![CDATA[CH4]]> 0.15 <![CDATA[N2]]> 1.2 <![CDATA[H2S]]> 0.35 COS 0.01 <![CDATA[NH3]]> 0.65

[0071] Experimental group 2 (neck shrinking design only)

[0072] Element content(%) <![CDATA[H2]]> 44.0 CO 32.0 <![CDATA[CO2]]> 16.3 <![CDATA[CH4]]> 0.18 <![CDATA[N2]]> 1.4 <![CDATA[H2S]]> 0.40 COS 0.02 <![CDATA[NH3]]> 0.75

[0073] Experimental Group 3 (Steam Design Only)

[0074]

[0075]

[0076] Control group (no regimen)

[0077] Element content(%) <![CDATA[H2]]> 40.2 CO 29.5 <![CDATA[CO2]]> 22.1 <![CDATA[CH4]]> 0.22 <![CDATA[N2]]> 1.7 <![CDATA[H2S]]> 0.45 COS 0.03 <![CDATA[NH3]]> 0.80

[0078] IV. Results Analysis

[0079] Efficiency improvement: The efficiency of experimental group 1 reached 98.7%, which was significantly higher than that of experimental group 2 (95.3%), experimental group 3 (94.5%) and control group (89.4%). This is because steam injection optimizes the temperature conditions for coal powder combustion, and the constriction design allows the coal powder to be concentrated in the high temperature area for efficient reaction;

[0080] In addition, the combustion efficiency in Experimental Group 1 (reduction + steam injection) is much higher than that in Experimental Groups 2 and 3. This proves that the combination of reduction and steam injection produces a synergistic effect, which makes the combustion of pulverized coal in the high temperature zone more complete and reduces the residual carbon content to 0.8%.

[0081] The residual carbon content was significantly reduced: the residual carbon content of experimental group 1 was 0.8%, which was much lower than that of experimental group 2 (2.1%), experimental group 3 (2.5%) and control group (5.5%). This proved that under the combined effect of steam injection and necking design, the coal powder was fully reacted in the high temperature zone, reducing the residual unburned coal powder.

[0082] Optimization of syngas gas composition: The hydrogen content in the syngas of experimental group 1 reached 47.5%, which was significantly higher than that of experimental group 2 (44.0%), experimental group 3 (45%) and control group (40.2%). This shows that the H2O+C→H2+CO reaction mechanism of steam injection plays an important role in increasing the hydrogen content. At the same time, the CO content of experimental group 1 is also high, and the content of impurities such as CO2 is relatively low, indicating that the constriction design makes the coal powder reaction more complete and reduces the impurity content in the syngas;

[0083] Moreover, the CO2 content of experimental group 1 is the lowest (12.5%), which means that the participation of steam not only increases the hydrogen content, but also the concentrated combustion of the shrinkage reduces the generation of impurities such as CO2, making the quality of the synthesis gas significantly better than the case of using shrinkage or steam alone.

[0084] Ash adhesion amount is reduced: the ash adhesion amount of experimental group 1 is 1.1g / m 2 , much lower than the control group's 4.0g / m 2 This indicates that the moderate mixing of steam and pulverized coal reduces the generation and adhesion of ash. The constriction design guides the airflow, prevents ash from gathering on the furnace wall, and improves the operating stability of the gasifier.

[0085] Reduced temperature fluctuations: The temperature fluctuations in experimental group 1 were controlled within (±12°C), which was significantly better than those in experimental group 2 (±25°C) and the control group (±45°C). Steam injection effectively regulated local overheating, and the shrinkage design ensured the concentration and stability of the airflow, making the temperature distribution more uniform.

[0086] Experimental data proves that the combination of constriction design and steam injection not only significantly improves the efficiency and hydrogen content of the second-stage dry powder gasifier, but also reduces the residual carbon and ash adhesion, and optimizes the proportion of combustible gas in the synthesis gas.

[0087] Moreover, experimental group 1 showed obvious synergistic effect of necking and steam. Various indicators such as combustion efficiency, residual carbon content and temperature fluctuation were better than those of the experimental groups using necking or steam injection alone, which fully demonstrated the significant advantages of the combination of necking and steam in optimizing combustion reactions and syngas quality.

[0088] 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 improving the efficiency of a two-stage dry powder gasification furnace, characterized in that: Change the flow direction in the gasifier so that the upward airflow converges to the middle of the gasifier; When the second stage coal is added, the second stage coal powder is injected into the gasifier through the second stage burner on the side of the gasifier. Under the disturbance of the air flow, the coal powder is distributed in the high temperature area in the middle of the gasifier.

2. The method for improving the efficiency of a two-stage dry powder gasification furnace according to claim 1, characterized in that: When the airflow converges toward the middle of the gasifier, it rises in a spiral shape, and the spiral direction is opposite to the rotation direction of the airflow formed by the first stage of the gasifier.

3. The method for improving the efficiency of a two-stage dry powder gasification furnace according to claim 2, characterized in that: The airflow path inside the gasifier forms a spiral upward flow pattern after the second-stage contraction. The airflow ensures that the combustion products are fully mixed with the unburned coal powder and are further brought into the high-temperature zone for further reaction.

4. The method for improving the efficiency of a two-stage dry powder gasification furnace according to any one of claims 1, 2 or 3, characterized in that: After the second-stage pulverized coal enters the gasifier, steam is injected into the gasifier through the steam injection channel; The ratio of steam to second-stage coal powder is 1:3 to 1:

5.

5. The method for improving the efficiency of a two-stage dry powder gasification furnace according to claim 4, characterized in that: The pulverized coal is mixed with boiler water during the second stage of coal feeding, and the ratio of boiler water to pulverized coal is 1:4 to 1:

6.

6. The method for improving the efficiency of a two-stage dry powder gasification furnace according to claim 5, characterized in that: The steam injection angle is 45° to 60°.

7. A two-stage dry powder gasification furnace, characterized in that: include, The second-stage necking is arranged above the second-stage burner of the gasifier, and the angle of the necking is 15° to 25°.

8. The two-stage dry powder gasification furnace according to claim 7, characterized in that: The second-stage constriction is arranged 0.8 to 1.2 meters above the second-stage burner.

9. The two-stage dry powder gasification furnace according to any one of claims 7 or 8, characterized in that: The second-stage necking is in a conical shape, and the tip of the necking is in a spiral shape, and the spiral direction is opposite to the rotation direction of the airflow formed by the first-stage gasification furnace.

10. The two-stage dry powder gasification furnace according to claim 9, characterized in that: A steam injection channel is provided above the pulverized coal conveying channel. The steam injection channel is arranged in the longitudinal direction, and a spacing of 10 to 20 centimeters is maintained between the opening of the steam injection channel and the opening of the pulverized coal conveying channel.

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