WO2011009234A1

WO2011009234A1 - Improved gasification process using staged oxygen

Info

Publication number: WO2011009234A1
Application number: PCT/CN2009/072838
Authority: WO
Inventors: 顾大地; 岳光溪
Original assignee: Gu Dadi; Yue Guangxi
Priority date: 2009-07-20
Filing date: 2009-07-20
Publication date: 2011-01-27
Also published as: CN101970618A

Abstract

Gasification process for producing crude coal gas containing CO and H₂with coal or coke as raw materials, involves following steps: 1) conveying raw materials, premixed gas and primary oxygen into a gasifier from a feeding burner at the top part of the gasifier, and performing primary combustion and gasification reaction, 2) at the same time, replenishing secondary oxygen from a secondary oxygen burner at the upper part of the gasification chamber of the gasifier to perform secondary combustion and gasification reaction, wherein the flow ratio of the primary oxygen to the secondary oxygen is 5:95 to 30:70, and 3) contacting the slag that flowing down along the gasifier wall with water to form solid slag at the bottom of the gasifier and then discharging the solid slag. Crude coal gas generated in the gasification chamber is discharged from a crude coal gas outlet at the lower part of the side wall of the gasifier. The process can optimize the axial temperature curve of the gasifier and can improve gasification efficiency.

Description

Improved oxygen fractionation gasification process

The invention relates to a gasification process for producing a crude gas containing carbon monoxide and hydrogen by gasification of coal and coke. Background technique

In the prior art, coal and coke can be gasified to form a gasification furnace containing carbon monoxide and hydrogen, and the raw fuel and oxygen are generally used simultaneously. Since the reaction state in the gasifier cannot be artificially controlled, the temperature distribution and the state of the gas flow in the furnace are not reasonable. The structure disclosed in the Chinese non-melting-melting gasification furnace of the Chinese invention patent application No. 02121086.1 filed by the inventor of the present application relates to two oxygen supply, but two furnace bodies must be adopted, the structure is complicated, and the investment is relatively high. High, there are some engineering difficulties in the pipeline connection, and should be improved in the promotion and application.

The inventor of the present application has a patent number of 200610114039.1, and the Chinese invention patent entitled "Classified gasification furnace for coal and coke gasification" discloses a technical solution for providing a secondary oxygen supply nozzle in a specific area of a furnace body. , that is, a secondary oxygen nozzle is arranged at the lower edge of the recirculation zone of the furnace body, so that a method of adding oxygen in a furnace can be adopted in a furnace body, the distribution of oxygen in the furnace can be adjusted, different temperature zones in the furnace can be established, and the reaction conditions can be optimized, and the second stage is added. The oxygen in the lower edge of the recirculation zone can disturb the gas in the "recirculation zone" of the furnace, strengthen the mass transfer and heat transfer of the raw fuel and oxygen in this zone, and make this inefficient recirculation zone a highly efficient reaction zone. The space in the recirculation zone is reduced, the mass transfer and heat transfer process of the chemical reaction in the furnace are strengthened, and the volume utilization rate of the gasification furnace is improved without changing the structure of the furnace body. The use of grading to add oxygen also forms two parts connected in series in the gasification furnace, that is, the low temperature non-melting zone and the high temperature melting zone in the furnace connected upstream and downstream. The advantage of the upper and lower series connection is that the raw fuel and oxygen flow smoothly in the gasifier, and the separation and bias of the solid and gas phases existing in the two isolated furnace bodies are not caused. The upper and lower parts can be connected directly by equal diameter, or they can be connected by unequal diameter or reduced diameter.

Although the above patent uses secondary oxygenation to increase the volume utilization rate of the gasifier, it does not take into account the influence of the secondary oxygen addition on the C0 ₂ content in the gasification gas. For the gasification process, the gasification process The content of C0 ₂ is an important indicator that directly affects the content of the effective gas (CO + H ₂ ). Because although the secondary oxygenation promotes the gasification reaction, there is an equilibrium reaction between CO and CO ₂ in the gasifier, so If the oxygen content is not suitable, it will not help the increase of the effective gas content, but will cause the secondary combustion and gasification reaction to be insufficient, or increase the content of C0 ₂ and reduce the content of the effective gas. Summary of the invention

The invention solves the problem that the secondary gas in the coal gasification process is uncertain about the effective gas content and the C0 ₂ content in the gasification gas and causes the secondary combustion and the gasification reaction to be insufficient, and provides a gasification process, which can improve the present There is technical gasification efficiency.

The technical solution of the present invention is as follows:

An improved oxygen fractionation gasification process characterized by comprising the steps of:

1) feeding the raw fuel, the premixed gas and the primary oxygen from the top feeding burner of the gasifier into the gasifier for a combustion and gasification reaction;

2) At the same time, secondary oxygen is supplied from the secondary oxygen nozzle located in the upper part of the gasification chamber of the gasification furnace, and secondary combustion and gasification reaction occur, and the flow ratio of the secondary oxygen to the primary oxygen is 5: 95. To 30: 70;

3) The ash flows down the inner wall of the gasifier, forms a solid smelting contact with water at the bottom of the furnace, and discharges the solid slag. The crude gas produced in the gasification chamber is from the crude gas located in the lower part of the side wall of the gasifier. The outlet is discharged.

The premixed gas is ejected from a central nozzle of the feed burner, the premixed gas is a gas having an oxygen content of 0 to 100%, and the non-oxygen component of the premixed gas includes N ₂ and/or C0 ₂ And / or 3⁄40 gas.

Providing one or more secondary oxygen nozzles in a plane perpendicular to the axis of the furnace body of the gasifier, the vertical distance of the plane of the secondary oxygen nozzle from the lower edge of the feed burner is the length of the straight section of the gasification chamber One or more secondary oxygen nozzles are respectively disposed in different planes perpendicular to the axis of the furnace body of the gasifier, and the different planes are divided from near to far according to the vertical distance of the plane of the secondary oxygen nozzle from the lower edge of the feed burner. a first layer plane and a second layer plane, wherein the vertical distance of the first layer plane from the lower edge of the feed burner is 15% to 35% of the length of the straight section of the gasification chamber, and the second layer plane is from the first layer The vertical distance of the plane is 4%~12% of the length of the straight section of the gasification chamber.

The secondary oxygen nozzle feeds secondary oxygen into the gasifier at a rate of from 70 m/sec to 200 m/sec. The flow ratio of the secondary oxygen to the primary oxygen is preferably from 10:90 to 25:75.

Technical Effect of the Invention - The improved oxygen fractionation gasification process of the present invention performs a flow ratio of secondary oxygen to primary oxygen Restriction, when the ratio of the flow rate of secondary oxygen to primary oxygen is less than 5:95, the secondary combustion and gasification reaction will be insufficient, and the secondary oxygen is not actually exerted, resulting in a change in the axial temperature curve of the gasifier. Large: The top temperature point is still at the top, and the average temperature does not change much. When the ratio of secondary oxygen to primary oxygen flow is greater than 30:70, the content of C0 ₂ is increased, the content of effective gas is reduced, and gasification is achieved. Efficiency will drop significantly. Therefore, only by controlling the flow ratio of secondary oxygen to primary oxygen to the above range, that is, adding a suitable amount of secondary oxygen, can truly achieve the effect of improving the gasification efficiency of the gasifier, so that the axial temperature curve of the gasifier tends to Reasonable: The top highest temperature point moves down and the average temperature is increased.

The premixed gas is ejected from the center nozzle of the feed burner, and the gas having a oxygen content of 0 to 100% is used as the premixed gas, which can reduce the top oxidation strength, thereby lowering the temperature of the feed nozzle region of the gasifier, and prolonging The service life of the feed burner can be adjusted over a wide range due to the oxygen content of the premixed gas, making the plant operation more flexible.

One or more secondary oxygen nozzles may be disposed on the same plane or different planes perpendicular to the axis of the furnace body of the gasifier. Since the injected gas is only gas, there is no solid, so the mass is small, and the secondary oxygen nozzle is asymmetrical. Arranged, it will not ablate the opposite wall. The setting of secondary oxygen nozzles of different heights can enlarge the oxidation zone and improve the capacity of the gasifier.

The secondary oxygen nozzle feeds the secondary oxygen into the gasifier at a speed of 70 m/s to 200 m/s, and the formed anti-diffusion flame is in the middle of the furnace, and does not ablate the secondary oxygen nozzle and the secondary oxygen nozzle. Furnace wall. DRAWINGS

1 is a schematic view showing the axial temperature change of a gasifier of a secondary oxygen gas and a primary oxygen gas at different flow ratios in a preferred modified oxygen gasification gasification process according to the present invention;

2 is a schematic diagram showing the relationship between the flow ratio of secondary oxygen to primary oxygen and the content of C0 _{2 at the} outlet of the gasifier;

3a, 3b and 3c are respectively schematic views showing the structure of three different gasification furnaces and their different secondary oxygen nozzles in the improved oxygen gasification gasification process of the present invention.

The labels in the figure are listed as follows:

1. Pressure-resistant steel shell, 2. Refractory layer, 3. Secondary oxygen nozzle, 4. Feeding burner, 41, inner tube, 42, intermediate casing, 43, outer casing, 5. Crude gas outlet 6, slag discharge, 7, water supply, 8, drain. detailed description

The invention will be further described below in conjunction with the accompanying drawings.

A preferred improved oxygen fractionation gasification process of the present invention comprises the steps of:

1) The raw fuel (coal, coke dry powder or slurry), premixed gas and primary oxygen are sent from the top of the gasifier to the gasifier, and a combustion and gasification reaction are carried out to form a local low temperature zone. Wherein, the premixed gas is ejected from the center nozzle of the feed burner, for example, the feed burner is a three-casing feed nozzle, which is divided into an inner tube, an intermediate sleeve and an outer sleeve, and the inner tube is opened. Premixed gas, the intermediate casing is fed with coal or coke dry powder or slurry, and the outer casing is filled with primary oxygen. The gas with oxygen content of 0~100% is used as the premixed gas, wherein when the oxygen content is 100% The premixed gas is pure oxygen. When the oxygen content is less than 100%, the non-oxygen component in the premixed gas preferably includes a gas such as N ₂ , C0 ₂ , H ₂ 0 gas, and the non-oxygen component can reduce the gasifier. The temperature of the top feed burner area extends the life of the feed burner.

2) replenishing secondary oxygen from a secondary oxygen nozzle located in the upper part of the gasification chamber of the gasification furnace, generating secondary combustion and gasification reaction, and the flow ratio of the secondary oxygen to primary oxygen is 5:95 to 30: 70, thereby forming a local high temperature zone. The secondary oxygen addition has a great influence on the effective gas (CO+H2) content in the gasification gas. Only the addition of the secondary oxygen in the above range can make the axial temperature curve of the gasifier tend to be reasonable: Moreover, the average temperature is increased to improve the gasification efficiency of the gasifier. The ratio of the secondary oxygen to the primary oxygen flow rate is too high or too low to improve the gasification efficiency of the gasifier and even reduce the gasification efficiency. Figure 1 is a schematic view showing the axial temperature change of the gasifier of the secondary oxygen and the primary oxygen at different flow ratios in the process of the present invention, wherein the X axis represents the gasifier from the top to the bottom (or from the gasification chamber) The axial height from the top to the bottom of the gasification chamber, the Y axis indicates the temperature. The signs, B, C, D and E in the figure indicate the flow ratio of secondary oxygen to primary oxygen, respectively: 0: 100, 5: 95, 10: 90, 20: 80 and 30: 70, the flow referred to can be volume flow or weight flow, but for a certain working condition, the ratio of the two oxygen flows is the same. In the figure, it can be concluded that the ratio of the secondary oxygen to the primary oxygen flow rate is 5:95 to 30::70, and the optimization of the axial temperature profile of the furnace temperature is obvious, especially at 10:90 to 25:75, gasification. The efficiency is higher than other ratios. When the ratio of secondary oxygen to primary oxygen flow is less than 5:95, the secondary combustion and gasification reaction will be insufficient. In fact, the secondary oxygen is not used, resulting in the gasifier. The axial temperature curve does not change much: the top temperature point is still at the top, and the average temperature does not change much. When the ratio of secondary oxygen to primary oxygen flow is greater than 30:70, the C0 ₂ content is increased, and the effective reduction is effective. The gas content and gasification efficiency will be significantly reduced. Figure 2 is a schematic diagram showing the relationship between the ratio of the flow rate of secondary oxygen to primary oxygen and the content of C0 _{2 at the} outlet of the gasifier. The Z axis in the figure indicates secondary oxygen. With a flow ratio of oxygen, V axis indicates the content of C0 _2, the flow ratio of oxygen to a secondary oxygen to the gasification gas in the C0 ₂ content is closely related to a flow rate ratio of oxygen to secondary oxygen of 5: 95 to 30: At 70 °C, the C0 ₂ content is at the lower end of the curve. After 30:70, the C0 ₂ content increases significantly, and the corresponding CO content decreases significantly, and the gasification efficiency will decrease significantly. It should be added that since the oxygen content in the premixed gas can be 0-100%, when the oxygen content in the premixed gas is greater than 0%, that is, the premixed gas also contains oxygen, then the feedstock is sent in the burner. The incoming oxygen includes oxygen in the primary oxygen and the premixed gas. The ratio of the secondary oxygen to the primary oxygen flow referred to above is actually the ratio of the flow rate of the secondary oxygen to the total oxygen fed into the feed burner.

The secondary oxygen nozzle can send the secondary oxygen into the gasifier at a speed of 70 m/s to 200 m/s, and the formed anti-diffusion flame is in the middle of the furnace, and does not ablate the secondary oxygen nozzle and the secondary oxygen nozzle. The wall of the furnace.

3) The molten ash flows down the inner wall of the gasifier refractory layer or the water-cooled wall, and solidifies the solid body of the glass body by contact with water at the bottom of the furnace, and discharges the solid slag, which is generated by the gasification chamber. The crude gas is discharged from the crude gas outlet located at the lower portion of the side wall of the gasifier.

3a, 3b and 3c are respectively schematic structural views of three different gasification furnaces and their different secondary oxygen nozzles in the improved oxygen gasification gasification process of the present invention, the gasification process being completed in the gasification furnace, chemistry A portion of the oxygen required for the reaction is fed from the feed burner outer sleeve 43 located at the top of the gasifier, and another portion is added from the secondary oxygen nozzle 3 located at the side of the gasifier and above the gasification chamber. Wherein, the gasification furnace is composed of the pressure resistant steel shell 1 and the refractory layer 2 therein to form a furnace body, the feed burner 4 is a three-casing feed nozzle, and the inner tube 41 is fed with a premixed gas, in the middle The casing 42 is supplied with dry powder or slurry of coal and coke, the outer casing 43 is supplied with primary oxygen, and the secondary oxygen nozzle 3 is sprayed with secondary oxygen. The resulting crude gas containing CO and H ₂ is passed through the pressure resistant steel. The crude gas outlet 5 provided at the lower portion of the side wall of the casing 1 is sent out to the gasification furnace, the slag discharge port 6 is installed at the bottom of the pressure resistant steel casing 1, and the lower portion of the pressure resistant steel casing 1 is provided with the drain port 8 and the water supply port 7 .

3a, 3b and 3c respectively show a gasifier of an equal diameter furnace body, an unequal diameter furnace body and a unequal diameter diameter connecting furnace body, and the positions and the number of the secondary oxygen nozzles 3 may be set differently. The secondary oxygen nozzle 3 is usually disposed on the upper portion of the side wall of the pressure resistant steel casing 1 (ie, the upper portion of the gasification chamber), and one or more may be disposed in the same plane or different planes perpendicular to the axis of the furnace body of the gasification furnace. The secondary oxygen nozzle, and the flow rate and velocity of the gas injected by the two or more secondary oxygen nozzles in the same plane may be different. Figure 3c shows two secondary oxygen nozzles symmetrically in the same plane perpendicular to the axis of the furnace body of the gasifier. Of course, the secondary oxygen nozzles can also be arranged asymmetrically or in multiples; Figure 3a and Figure 3b are In a vertical gasifier The two planes of the axis of the furnace body are respectively provided with one or more secondary oxygen nozzles, and the preferred position of the secondary oxygen nozzle is: the vertical distance from the lower edge of the feed nozzle of the secondary oxygen nozzle from the near to the far Divided into a first layer plane and a second layer plane, the vertical distance HI of the first layer plane from the lower edge of the feed burner is 15% to 35% of the length S of the straight section of the gasification chamber, and the second layer plane is the first layer The vertical distance H2 of the plane is 4% to 12% of the length S of the straight section of the gasification chamber. It should be noted that, in the unequal diameter furnace body shown in FIG. 3b, the above-mentioned "feeder burner lower edge" refers to the increase of the furnace body diameter, and at this time, the gasification chamber straight section length S is the furnace. The length of the gasification chamber at the lower portion of the body diameter is increased; in the unequal diameter reduction diameter connecting furnace body shown in Fig. 3c, the above "feeding burner lower edge" refers to the enlarged diameter of the furnace body after shrinking. At this time, the length S of the straight section of the gasification chamber is the length of the vaporization chamber at the lower portion where the diameter of the furnace body is increased after shrinking. The provision of secondary oxygen nozzles of different heights on different levels can enlarge the oxidation zone and contribute to the improvement of the gasifier capacity.

Claims

Rights request

An improved oxygen fractionation gasification process, comprising the steps of:

3) The ash flows down the inner wall of the gasifier, forms a solid melt in contact with the water at the bottom of the furnace, and discharges the solid slag. The crude gas produced in the gasification chamber is from the crude gas located in the lower part of the side wall of the gasifier. The outlet is discharged.

2. The improved oxygen fractionation gasification process according to claim 1, wherein the premixed gas is ejected from a center nozzle of the feed burner, and the premixed gas has an oxygen content of 0 to 100%. The gas, the non-oxygen component of the premixed gas comprises N ₂ and/or C0 ₂ and/or H ₂ 0 gas.

3. An improved oxygen fractionation gasification process according to claim 1 or 2, wherein one or more secondary oxygen nozzles are disposed in the same plane perpendicular to the axis of the furnace body of the gasifier, said second The vertical distance between the plane of the oxygen nozzle and the lower edge of the feed burner is 15% to 35% of the length of the straight section of the gasification chamber.

4. An improved oxygen fractionation gasification process according to claim 1 or 2, wherein one or more secondary oxygen nozzles are respectively disposed in different planes perpendicular to the axis of the furnace body of the gasifier, said different The plane is divided into a first layer plane and a second layer plane according to the vertical distance of the plane of the secondary oxygen nozzle from the lower edge of the feed burner, the vertical distance of the first layer plane from the lower edge of the feed burner The length of the straight section of the gasification chamber is 15% to 35%, and the vertical distance of the plane of the second layer from the plane of the first layer is 4% to 12% of the length of the straight section of the gasification chamber.

5. The improved oxygen fractionation gasification process of claim 1 wherein said secondary oxygen nozzle delivers secondary oxygen to the gasifier at a rate of from 70 meters per second to 200 meters per second.

6. The improved oxygen fractionation gasification process of claim 1 wherein said second oxygen to primary oxygen flow ratio is preferably from 10:90 to 25:75.