A high calorific value producer gas production process

Abstract

The present invention discloses a process for producing high-calorific-value producer gas. High-temperature residual carbon at 1000 - 1100 °C is added into a vertical gasifier from the middle part on one side of the vertical gasifier. During the falling process, the high-temperature residual carbon contacts with high-temperature steam blown in from the bottom upwards, so that the residual carbon contacts with water steam during the boiling movement process and a water gas reaction occurs. During the multiple boiling movement processes in the vertical direction, the residual carbon flows from one side of the vertical gasifier to the other side. When the residual carbon flows to the other side of the vertical gasifier and its temperature is below 600 °C, the low-temperature residual carbon is discharged from the middle part on the other side of the vertical gasifier; the high-calorific-value gas generated in the furnace is discharged from the top of the vertical gasifier, and the high-calorific-value gas is then supplied to users for utilization after being dust-removed, cooled and pressurized.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy chemical engineering, and particularly relates to a process for producing producer gas with high calorific value. Background Art

[0002] A gas producer is a production device that converts coal into combustible gas - producer gas (mainly composed of CO, H2, CH4, etc.). Its working principle is as follows: After screening coal that meets the gasification process indicators (generally low-rank coal), the coal with a particle size less than 10 mm is added into the gas producer by a coal feeder. Steam and air or a mixture of oxygen and steam are blown into the furnace from the bottom as the gasifying agent. The coal undergoes physical and chemical reactions in the furnace to generate combustible gas - producer gas.

[0003] In a fluidized bed gasifier commonly used in industry, the formation of the fluidized bed layer is a dynamic gasification method between layered gasification and suspended gasification. When the flow rate of the gasifying agent exceeds the minimum limit at which coal particles can stay on the grate, some coal particles in the pulverized coal will lose stability and start to fluctuate locally in the air flow, forming a fluidized gasification state. At this time, the flow rate of the gasifying agent passing through the coal particle layer on the grate is an important factor determining the fluidized gasification effect. If the flow rate of the gasifying agent is too small, the fluidized state of the coal particles cannot be formed, or the number of particles participating in the fluidized state is small and the duration is short, and they will quickly return to the grate under the action of the particle self-weight; if the flow rate of the gasifying agent is too large, the gasification environment on the grate is damaged, and the fluidized gasification bed layer cannot be stable or even lost. Only when the flow rate of the gasifying agent and the fluidized movement of the coal particles reach a relative balance, can most or all of the coal particles continuously maintain the upward and downward movement states under the action of the gasifying agent pressure. During this fluidized movement process, the coal particles are fully mixed with the gasifying agent, and carbon gasification can be maximized, thus forming an efficient coal gasification process.

[0004] The characteristics of a fluidized bed gasifier are that the heat transfer and mass transfer rates between the gasifying agent and solid coal are extremely fast, and the temperature gradient is relatively small. This characteristic is caused by the rapid agitation and mixing of solid particles in the air flow, resulting in a large contact area between solid particles and the gasifying agent and high heat transfer efficiency. In a fluidized bed gasifier, producer gas with different calorific values can be obtained according to the oxygen content of the gasifying agent.

[0005] Figure 1This is a diagram of an existing fluidized-bed gasifier. A fluidized-bed gasifier generally consists of a coal bunker, a gasifier, a grate, secondary air nozzles, and an ash discharge port. After coal is added to the coal bunker, it is transported into the gasifier by a screw conveyor. The coal flows from top to bottom, while the gasifying agent blown in from the grate flows from bottom to top. During the contact between the coal and the gasifying agent, the coal undergoes a fluidized motion, enabling the coal to undergo a carbon gasification reaction with water vapor during the temperature increase process, producing producer gas. The raw gas is discharged from the top of the gasifier. At the same time, the coal at the bottom of the gasifier burns under the action of air or oxygen and supplies heat to the furnace. The coal ash generated by the coal combustion deposits at the bottom of the producer furnace and is then discharged through a screw conveyor.

[0006] The particle size of the coal used in the fluidized-bed gasifier is generally 0 - 10 mm. Air or oxygen mixed with water vapor is used as the gasifying agent, and the gasifying agent is blown into the furnace from the bottom through the grate. The pulverized coal undergoes fluidization under the action of the gasifying agent. The height of the fluidized bed is generally 1.0 - 1.5 m, and the carbon gasification temperature is 950 - 1000 °C. During the fluidized heat exchange process of the pulverized coal in the furnace, drying, heating, dry distillation, and carbon gasification occur. The carbon gasification efficiency can reach 50 - 60%, and production operations can be carried out under normal pressure. Due to the intense fluidization inside the material layer, the gasifying agent can be fully contacted with the pulverized coal, and the heat transfer conditions of the pulverized coal are very good. The temperature of the entire material layer of the fluidized-bed gasifier is basically uniform.

[0007] The fluidized-bed gasifier can produce gas with different calorific values according to the oxygen content of the gasifying agent. When air-steam is blown, the calorific value of the gas is between 4180 - 4606 KJ / Nm 3 , and the calorific value of the gas is relatively low. When oxygen-steam is blown, the calorific value of the gas is between 8793 - 9211 KJ / Nm 3 . Although this method can increase the calorific value of the gas, oxygen is consumed during the production process, resulting in a relatively high production cost. The fluidized-bed gasifier uses a mixture of air and water vapor as the gasifying agent. The amount of gasifying agent required for the fluidization of the coal is relatively large, and the outlet temperature of the gas is relatively high. If a gas sensible heat recovery device is not used, the outlet temperature can reach above 900 °C. This type of gasifier is more suitable for areas where hot gas is needed. It can not only improve the energy utilization rate, but also has simple equipment, low investment, and low operating costs. Pulverized coal can be used as the raw material, the gasification intensity inside the furnace is high, the gas produced does not contain tar, and the post-treatment equipment is simple, making it easy to meet environmental protection requirements. Summary of the Invention

[0008] To solve the problems of the existing fluidized-bed gasifier that uses normal-temperature coal as the raw material and has a relatively low calorific value of the gas when using air-steam as the gasifying agent, and although the calorific value of the gas can be increased when using oxygen-steam as the gasifying agent, the production cost is relatively high; the present invention uses high-temperature residual carbon as the raw material and high-temperature steam as the gasifying agent, and the present invention provides a high-calorific value producer gas production device.

[0009] To this end, the present invention adopts the following technical solutions:

[0010] A high calorific value producer gas production process, including a vertical gasifier. The lower end of the vertical gasifier is provided with an ash discharge port, and the top is provided with a raw gas outlet; a horizontal grate is provided at the lower part of the inner cavity of the vertical gasifier. The outer edge of the grate is fixedly connected to the inner wall of the vertical gasifier. A dust accumulation area is formed below the grate, and a carbon gasification area is formed above the grate. The gas-solid separation area is above the carbon gasification area;

[0011] At the same height of the outer shell of the vertical gasifier, there are a material inlet and a material outlet. The material inlet and the material outlet are arranged oppositely, and the heights of the material inlet and the material outlet are at the boundary between the carbon gasification area and the gas-solid separation area; A spiral air-lock feeder is connected to the material inlet, and the inlet end of the spiral air-lock feeder is connected to a high-temperature residual carbon bin; A spiral air-lock discharger is connected to the material outlet; The production process includes the following steps:

[0012] 1) Residual carbon with a particle size of 0-10 mm and a temperature of 1000-1100 °C is added to the high-temperature residual carbon bin from the high-temperature material feeding port, and the high-temperature residual carbon is added to the furnace through the spiral air-lock feeder;

[0013] 2) A plurality of small holes with a diameter of 2-3 mm are provided on the grate of the vertical gasifier, and the center distance between adjacent small holes is 4-5 mm; After high-temperature steam is introduced from the bottom of the vertical gasifier, it is introduced into the furnace through the small holes on the grate, and then blown vertically upward into the carbon gasification area;

[0014] 3) In the carbon gasification area, when the high-temperature residual carbon flows downward, it contacts the high-temperature steam blown upward, causing the residual carbon to perform a boiling motion in the furnace;

[0015] 4) The high-temperature residual carbon continuously undergoes a water gas reaction with the high-temperature steam during the boiling motion, producing a high calorific value gas containing H2 and CO. The temperature of the high-temperature residual carbon gradually decreases during the water gas reaction; When the temperature of the residual carbon drops below 600 °C, the water gas reaction rate approaches zero;

[0016] When the low-temperature residual carbon flows to the middle position of the other furnace wall of the vertical gasifier during the boiling motion, the low-temperature residual carbon is discharged from the material outlet and discharged out of the furnace through the spiral air-lock discharger;

[0017] 5) In the vertical gasifier, when the high calorific value gas produced in the carbon gasification area flows upward through the gas-solid separation area, the coarse dust in the gas sinks to the carbon gasification area under the action of gravity. The carbon powder continues to participate in the carbon gasification reaction of the high-temperature steam and produces a high calorific value gas, and the high calorific value gas is discharged from the raw gas outlet;

[0018] 6) The high-temperature, high-calorific-value gas at 700 - 800 °C discharged from the top of the vertical gasifier enters the cyclone dust collector for secondary rough dust removal. After removing the medium-sized dust in the high-calorific-value gas, it is converted into low-dust, high-calorific-value gas;

[0019] 7) The low-dust, high-calorific-value gas discharged from the cyclone dust collector is introduced into the gas cooler. Through indirect heat exchange with water, the temperature of the low-dust, high-calorific-value gas is reduced to below 150 °C;

[0020] 8) The cooled high-calorific-value gas is introduced into the bag filter for fine dust removal. The obtained clean gas is pressurized by a gas booster and then stored in a storage tank;

[0021] 9) The low-temperature residual carbon below 600 °C discharged from the vertical gasifier is added into the rotary cooler. The temperature of the low-temperature residual carbon is reduced under the indirect cooling effect of cooling water and is discharged from the rotary cooler after the temperature is reduced to below 200 °C.

[0022] Furthermore, the carbon gasification zone of the vertical gasifier is set as an inverted trumpet structure with a larger upper part and a smaller lower part, so that the residual carbon performs a boiling motion in the carbon gasification zone.

[0023] The process of the present invention is as follows:

[0024] The process of the present invention is as follows: The high-temperature residual carbon at 1000 - 1100 °C is added into the vertical gasifier from the middle part on one side of the vertical gasifier. During the falling process, the high-temperature residual carbon contacts the high-temperature water vapor blown from the bottom upwards, so that the residual carbon contacts and undergoes the water gas reaction with the water vapor during the boiling motion process. The residual carbon flows from one side to the other side of the vertical gasifier during multiple boiling motion processes in the vertical direction. When the residual carbon flows to the other side of the vertical gasifier and the temperature is below 600 °C, the low-temperature residual carbon is discharged from the middle part on the other side of the vertical gasifier; The high-calorific-value gas generated in the furnace is discharged from the top of the vertical gasifier after passing through the gas-solid separation zone, and the high-calorific-value gas is further supplied to users for utilization after dust removal, cooling, and pressurization.

[0025] The vertical gasifier of the present invention uses the power of high-temperature steam to complete heat transfer, mass transfer, and carbon gasification reactions of the high-temperature residual carbon in a boiling state. The entire material layer is equivalent to a large high-temperature pool. The temperature of the introduced steam rises rapidly and undergoes a carbon gasification reaction with the residual carbon, and the entire carbon gasification reaction proceeds violently. The gas produced by the present invention does not contain N2 and can produce high-calorific-value gas.

[0026] The present invention sets the carbon gasification zone of the vertical gasifier as an inverted trumpet structure with a larger upper part and a smaller lower part, which can reduce the gas flow velocity during the boiling motion from bottom to top of the residual carbon, thereby improving the separation effect of the gas-solid two-phase in the upper part of the vertical gasifier.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The vertical gasifier of the present invention makes full use of the waste heat of high-temperature residual carbon and adopts the fluidized gasification technology. Under the action of the gasifying agent gas flow, the residual carbon particles are in a continuous tumbling and undulating motion, and the carbon gasification reaction rate of the residual carbon is fast;

[0029] 2. The vertical gasifier of the present invention uses high-temperature steam as the gasifying agent, and the calorific value of the producer gas produced is above 8500 KJ / Nm 3 above, which can meet the production needs of various industrial furnaces;

[0030] 3. The content of macromolecular substances such as tar, benzene, and naphthalene in the high-calorific value gas produced by the present invention is relatively low, and the gas can be utilized without purification treatment;

[0031] 4. The production capacity of the fluidized gasifier of the present invention is relatively large, and the raw material preparation, process, and equipment conditions are all simpler than other methods. Description of the Drawings

[0032] Figure 1 is a structural schematic diagram of an existing fluidized gasifier;

[0033] Figure 2 is a structural schematic diagram of the fluidized gasifier of the present invention;

[0034] Figure 3 is Figure 2 a cross-sectional view taken along A-A in

[0035] In the figure: 1 - vertical gasifier, 2 - ash discharge port, 3 - raw gas outlet, 4 - grate, 5 - dust accumulation area, 6 - carbon gasification area, 7 - gas-solid separation area, 8 - spiral air-lock feeder, 9 - high-temperature residual carbon bin, 10 - spiral air-lock discharger. Detailed Embodiments

[0036] The present invention will be further described below in conjunction with the drawings:

[0037] As Figure 2 and 3 shown, a high-calorific value producer gas production process includes a vertical gasifier 1. The lower end of the vertical gasifier 1 is provided with an ash discharge port 2, and the top is provided with a raw gas outlet 3; a horizontal grate 4 is provided at the lower part of the inner cavity of the vertical gasifier 1. The outer edge of the grate 4 is fixedly connected to the inner wall of the vertical gasifier 1. A dust accumulation area 5 is formed below the grate 4, a carbon gasification area 6 is formed above the grate 4, and a gas-solid separation area 7 is above the carbon gasification area 6;

[0038] At the same height of the shell of the vertical gasifier 1, there are a material inlet and a material outlet. The material inlet and the material outlet are arranged opposite to each other, and the heights of the material inlet and the material outlet are at the boundary between the carbon gasification zone 6 and the gas-solid separation zone 7. A spiral air-lock feeder 8 is connected to the material inlet, and the inlet end of the spiral air-lock feeder 8 is connected to the high-temperature residual carbon bin 9. A spiral air-lock discharger 10 is connected to the material outlet. The production process includes the following steps:

[0039] 1) Residual carbon with a particle size of 0 - 10 mm and a temperature of 1000 - 1100 °C is added to the high-temperature residual carbon bin 9 from the high-temperature material feeding port, and the high-temperature residual carbon is added to the furnace through the spiral air-lock feeder 8.

[0040] 2) A plurality of small holes with a diameter of 2 - 3 mm are provided on the grate 4 of the vertical gasifier 1, and the center distance between adjacent small holes is 4 - 5 mm. After high-temperature steam is introduced from the bottom of the vertical gasifier 1, it is introduced into the furnace through the small holes on the grate 4, and then blown vertically upward into the carbon gasification zone 6.

[0041] 3) In the carbon gasification zone 6, during the downward flow of the high-temperature residual carbon, it contacts the high-temperature steam blown upward from the bottom, causing the residual carbon to perform a boiling motion in the furnace.

[0042] 4) The high-temperature residual carbon continuously undergoes a water-gas reaction with the high-temperature steam during the boiling motion, producing a high-calorific-value gas containing H2 and CO. The temperature of the high-temperature residual carbon gradually decreases during the water-gas reaction. When the temperature of the residual carbon drops below 600 °C, the water-gas reaction rate approaches zero.

[0043] When the low-temperature residual carbon flows to the middle position of the other side furnace wall of the vertical gasifier 1 during the boiling motion, the low-temperature residual carbon is discharged from the material outlet and discharged out of the furnace through the spiral air-lock discharger 10.

[0044] 5) In the vertical gasifier 1, when the high-calorific-value gas produced in the carbon gasification zone 6 flows upward through the gas-solid separation zone 7, the coarse dust in the gas sinks to the carbon gasification zone 6 under the action of gravity. The carbon powder continues to participate in the carbon gasification reaction with the high-temperature steam and produces a high-calorific-value gas, and the high-calorific-value gas is discharged from the raw gas outlet 3.

[0045] 6) The high-temperature, high-calorific-value gas at 700 - 800 °C discharged from the top of the vertical gasifier 1 enters the cyclone dust collector for secondary rough dust removal, and after removing the medium-sized dust in the high-calorific-value gas, it is converted into low-dust high-calorific-value gas.

[0046] 7) The low-dust high-calorific-value gas discharged from the cyclone dust collector is introduced into the gas cooler, and the high-calorific-value gas reduces its temperature to below 150 °C through indirect heat exchange with water.

[0047] 8) The high calorific value gas after temperature reduction is introduced into a bag filter for fine dust removal. The clean gas obtained is then pressurized by a gas booster and stored in a storage tank after being pressurized.

[0048] 9) The low-temperature residual carbon below 600 °C discharged from the vertical gasifier 1 is added into a rotary cooler. The temperature of the low-temperature residual carbon decreases under the indirect cooling effect of cooling water and is discharged from the rotary cooler after the temperature drops below 200 °C.

[0049] The carbon gasification zone 6 of the vertical gasifier 1 is set as an inverted flared structure with a larger upper part and a smaller lower part, enabling the residual carbon to perform a boiling motion within the carbon gasification zone 6.

Claims

1. A high calorific value producer gas production process, characterized in that, It includes a vertical gasifier (1). The lower end of the vertical gasifier (1) is provided with an ash discharge port (2), and the top is provided with a raw gas outlet (3). At the lower part inside the cavity of the vertical gasifier (1), a horizontal grate (4) is provided. The outer edge of the grate (4) is fixedly connected to the inner wall of the vertical gasifier (1). A dust accumulation area (5) is formed below the grate (4), and a carbon gasification area (6) is formed above the grate (4). Above the carbon gasification area (6) is a gas-solid separation area (7). At the same height of the outer shell of the vertical gasifier (1), there are a material inlet and a material outlet. The material inlet and the material outlet are arranged oppositely, and the heights of the material inlet and the material outlet are at the boundary between the carbon gasification area (6) and the gas-solid separation area (7). A screw lock feeder (8) is connected to the material inlet, and the inlet end of the screw lock feeder (8) is connected to a high-temperature residual carbon bin (9). A screw lock discharger (10) is connected to the material outlet. The production process includes the following steps: 1) Residual carbon with a particle size of 0 - 10 mm and a temperature of 1000 - 1100 °C is added to the high-temperature residual carbon bin (9) from the high-temperature material feeding port, and the high-temperature residual carbon is added to the furnace through the screw lock feeder (8). 2) A plurality of small holes with a diameter of 2 - 3 mm are opened on the grate (4) of the vertical gasifier (1), and the center distance between adjacent small holes is 4 - 5 mm. After high-temperature steam is introduced from the bottom of the vertical gasifier (1), it passes through the small holes on the grate (4) into the furnace, and then blows vertically upward into the carbon gasification area (6). 3) In the carbon gasification area (6), during the process of the high-temperature residual carbon flowing from top to bottom, it contacts the high-temperature steam blowing from bottom to top, causing the residual carbon to perform a boiling motion in the furnace. 4) The high-temperature residual carbon continuously undergoes a water-gas reaction with the high-temperature steam during the boiling motion, producing high-calorific gas containing H2 and CO. The temperature of the high-temperature residual carbon gradually decreases during the water-gas reaction process. When the temperature of the residual carbon drops below 600 °C, the water-gas reaction rate approaches zero. When the low-temperature residual carbon flows to the middle position of the other side furnace wall of the vertical gasifier (1) during the boiling motion process, the low-temperature residual carbon is discharged from the material outlet and discharged out of the furnace through the screw lock discharger (10). 5) In the vertical gasifier (1), when the high-calorific gas produced in the carbon gasification area (6) flows upward through the gas-solid separation area (7), the coarse dust in the gas sinks to the carbon gasification area (6) under the action of gravity. The carbon powder continues to participate in the carbon gasification reaction with the high-temperature steam and produces high-calorific gas, and the high-calorific gas is discharged from the raw gas outlet (3). 6) The high-temperature, high-calorific gas at 700 - 800 °C discharged from the top of the vertical gasifier (1) enters a cyclone dust collector for secondary rough dust removal, and after removing the medium-sized dust in the high-calorific gas, it is converted into low-dust high-calorific gas. 7) The low-dust high-calorific gas discharged from the cyclone dust collector is introduced into a gas cooler, and the high-calorific gas reduces its temperature below 150 °C through indirect heat exchange with water. 8) The cooled high-calorific gas is introduced into a bag filter for fine dust removal to obtain clean gas, which is then pressurized by a gas booster and stored in a storage tank. 9) The low-temperature residual carbon below 600°C discharged from the vertical gasifier (1) is added into the rotary cooling furnace. The temperature of the low-temperature residual carbon decreases under the indirect cooling effect of the cooling water and is discharged from the rotary cooling furnace after the temperature drops below 200°C.

2. The high calorific value producer gas production process according to claim 1, characterized in that, The carbon gasification zone (6) of the vertical gasifier (1) is arranged in an inverted flared structure with a larger upper part and a smaller lower part, so that the residual carbon performs a boiling motion in the carbon gasification zone (6).

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