阅读说明：本技术 一种气化飞灰资源化处理及热能再利用系统及方法 (Gasification fly ash recycling treatment and heat energy recycling system and method ) 是由 刘志成 朱治平 高鸣 吕清刚 于 2019-09-03 设计创作，主要内容包括：本发明涉及一种气化飞灰资源化处理及热能再利用系统及方法,包括：循环流化床气化炉、换热器、除尘器设备、飞灰熔融炉和高温分离器。在原有循环流化床煤气化炉中配套飞灰熔融炉实现对气化飞灰的资源化处理,从飞灰熔融炉中出来的高温烟气或煤气与部分二级气化剂混合,混合后形成高温混合烟气或煤气,在此过程中可实现对部分二级气化剂的预热,并可实现对高温烟气或煤气的急冷,把烟气或煤气中携带的熔融颗粒物淬化成小球体。气化飞灰中的大部分化学热转变成烟气焓或煤气焓进入气化炉中,实现了热能再利用；高温混合烟气或煤气中的CO<Sub>2</Sub>作为补充气化剂参与到气化反应中,能有效提高整个气化系统的碳转化率和冷煤气效率。(The invention relates to a gasification fly ash resource treatment and heat energy recycling system and a method, which comprises a circulating fluidized bed gasification furnace, a heat exchanger, a dust remover device, a fly ash melting furnace and a high-temperature separator, wherein the fly ash melting furnace is matched with an original circulating fluidized bed gasification furnace to realize resource treatment on gasification fly ash, high-temperature flue gas or coal gas from the fly ash melting furnace is mixed with part of secondary gasification agent to form high-temperature mixed flue gas or coal gas after mixing, preheating of part of the secondary gasification agent can be realized in the process, quenching of the high-temperature flue gas or coal gas can be realized, molten particles carried in the flue gas or coal gas are quenched into small spheres, most of chemical heat in the gasification fly ash is converted into flue gas enthalpy or coal gas enthalpy and enters the gasification furnace to realize heat energy recycling, CO 2 in the high-temperature mixed flue gas or coal gas is used as a supplementary gasification agent to participate in gasification reaction, and the carbon and cold coal gas efficiency of the whole gasification system.)

1. A gasification fly ash resourceful treatment and heat energy recycling system is characterized by comprising: the device comprises a circulating fluidized bed gasification furnace (1), dust remover equipment (4) and a fly ash melting furnace (5), wherein an outlet of the circulating fluidized bed gasification furnace (1) is communicated with an inlet of the dust removing equipment (4), the dust removing equipment (4) is provided with a fly ash outlet, the fly ash outlet is communicated with an inlet of the fly ash melting furnace (5), the fly ash melting furnace (5) is provided with a high-temperature flue gas outlet, and the high-temperature flue gas outlet is communicated with a hearth of the circulating fluidized bed gasification furnace (1) through a connecting pipeline (9).

2. The gasification fly ash resource treatment and heat energy recycling system according to claim 1, wherein: the system also comprises a high-temperature separator (7), wherein the high-temperature separator (7) is arranged on a connecting pipeline of the fly ash melting furnace (5) and the circulating fluidized bed gasification furnace (1), the inlet of the high-temperature separator is communicated with the outlet of the fly ash melting furnace (5), and the outlet of the high-temperature separator is communicated with the circulating fluidized bed gasification furnace (1).

3. The gasification fly ash resource treatment and heat energy recycling system according to claim 1, wherein: the hearth of the circulating fluidized bed gasification furnace (1) is provided with at least one secondary gasification agent inlet, the connecting pipeline (9) is communicated with the at least one secondary gasification agent inlet, and the secondary gasification agent inlet is arranged at the middle lower part of the hearth.

4. The gasification fly ash resource treatment and heat energy recycling system according to claim 1, wherein: an outlet pipeline of the fly ash melting furnace (5) is connected with a pass pipeline (6), and the pass pipeline (6) is suitable for introducing a secondary gasification agent.

5. A gasification fly ash resource treatment and heat energy recycling method is characterized by comprising the following steps:

step 1: the coal is gasified in the circulating fluidized bed gasification furnace (1), the gasification agents required by gasification are respectively fed from the bottom (2) of the hearth and the middle-lower oxidation zone (8) of the hearth in different heights in a grading way, the gasification agents fed from the bottom (2) of the hearth are used as first-stage gasification agents, and the gasification agents fed from the middle-lower oxidation zone (8) of the hearth in different heights are used as second-stage gasification agents; the secondary gasification dosage fed into the lower oxidation zone (8) in the hearth accounts for 20 to 30 percent of the total gasification dosage of the circulating fluidized bed gasification furnace;

Step 2: gas generated by the circulating fluidized bed gasification furnace (1) enters a dust remover device (4) for dust removal, fly ash in the gas is captured and sent to a fly ash melting furnace (5);

And step 3: the gasified fly ash collected by the dust collector (4) is sent into the fly ash melting furnace (5) for melting to generate high-temperature flue gas and melt, the temperature in the fly ash melting furnace (5) is controlled to be higher than the melting point temperature of the fly ash according to the difference of the melting points of the fly ash, and the melt is discharged from the bottom of the fly ash melting furnace (5); high-temperature flue gas is discharged from a flue gas outlet of the fly ash melting furnace (5);

And 4, step 4: introducing part or all of the secondary gasifying agent into the pipeline (6), mixing the high-temperature flue gas with the part or all of the secondary gasifying agent to form high-temperature mixed flue gas, quenching the high-temperature flue gas when the high-temperature flue gas meets the cold secondary gasifying agent in the process, simultaneously preheating the part or all of the secondary gasifying agent, controlling the gas temperature of the high-temperature mixed flue gas to be 900-1000 ℃, and quenching molten particles carried in the high-temperature gas into small spheres in the quenching process;

And 5: introducing the high-temperature mixed flue gas into a circulating fluidized bed gasification furnace (1) to participate in gasification.

6. The gasification fly ash resource treatment and heat energy recycling method according to claim 5, wherein: the high-temperature mixed flue gas is dedusted by a high-temperature separator (7) and then is sent into the circulating fluidized bed gasification furnace (1) from an oxidation zone (8) at the middle lower part of the hearth to participate in gasification.

7. The gasification fly ash resource treatment and heat energy recycling method according to claim 5, wherein: in the step 5, the high-temperature mixed flue gas is introduced from different heights of the circulating fluidized bed gasification furnace (1).

8. The gasification fly ash resource treatment and heat energy recycling method according to claim 6, wherein: the high temperature separator (7) has high temperature resistance of 1500-1800 ℃ and adopts inertial separation in a separation mode.

9. The gasification fly ash resource treatment and heat energy recycling method according to claim 5, wherein: in the step 5, the high-temperature flue gas discharged from the fly ash melting furnace (5) is directly introduced into the circulating fluidized bed gasification furnace (1), and the molten particles quenched into small balls are discharged from the bottom of the circulating fluidized bed gasification furnace (1) along with the bottom slag.

Technical Field

The invention relates to a gasification fly ash recycling treatment and heat energy recycling system and method, which are applied to the field of coal gasification.

Background

The coal gasification technology is an important technology in the fields of modern energy and chemical industry. The gasification fly ash problem existing in different gasification processes becomes a key problem restricting the development of coal gasification technology. In a general large coal gasification process, qualified coal gas or industrial gas is generated, and simultaneously gasification fly ash with carbon content of 30-50% is generated, so that the carbon conversion rate of a gasification furnace is low, and the cold coal gas efficiency is also seriously influenced.

With the increasing market demand of industrial gas and synthetic ammonia, the circulating fluidized bed coal gasification technology has obvious advantages in both technical advancement and low cost, and a large number of circulating fluidized bed coal gasification furnaces are put into production and use. However, how to reduce the carbon content of the gasification fly ash and further realize the resource treatment of the gasification fly ash, and how to effectively utilize the chemical heat of the gasification fly ash in the treatment process, thereby improving the carbon conversion rate of the whole gasification system and improving the cold gas efficiency of the system is a great problem faced by the circulating fluidized bed coal gasification technology.

in order to reduce the carbon content of the gasified fly ash, a fly ash returning technology is generally adopted at present, but the technology has limited carbon content reduction of the gasified fly ash, and the resource treatment of the gasified fly ash cannot be completely realized.

Chinese patent application 201310093369.7 discloses a pulverized coal gasification method with a fly ash forced reinjection system, which is characterized in that a gas ejector is installed between a vertical discharge pipe of a pulverized coal fluidized bed coke powder circulation system and a gasification furnace, and recovered fly ash particles pass through a gas distribution plate through the gas ejector and directly enter a high-temperature oxidation area at the central part of the gasification furnace, so as to generate combustion and gasification reactions again.

The Chinese patent application 201510500635.2 discloses a fluidized bed fly ash return furnace gasification device and method, wherein the fly ash injection device comprises an inner layer channel and an outer layer channel, the inner layer channel is used for introducing an oxygen-containing gasification agent, the outer layer channel is used for introducing a mixture of return ash blowing gas and fly ash, or the inner layer channel is used for introducing a mixture of return ash blowing gas and fly ash, and the outer layer channel is used for introducing an oxygen-containing gasification agent, so that the fly ash and the oxygen-containing gasification agent are injected into the gasification furnace to perform combustion reaction at an outlet in a fully mixed manner.

The two patents have the same work, and the core is that the gasification fly ash of the fluidized bed is sent into the gasification furnace through the gas ejector and the fly ash injection device, so that the carbon in the gasification fly ash can not be completely reacted, the unreacted gasification fly ash is changed into fly ash with low carbon content again, and the resource treatment of the fly ash and the effective utilization of the residual chemical energy can not be realized.

The U-gas gasification technology of America directly mixes the semicoke separated from the cyclone separator and the gasification fly ash separated from the cyclone dust collector and then sends the mixture back to the lower part of the gasification furnace, so that the gasification fly ash continuously enters the gasification furnace to participate in gasification reaction, and actually, the residence time of the gasification fly ash in the furnace is prolonged.

These techniques have limitations in reducing the carbon content of the gasified fly ash and fail to fully utilize the remaining chemical heat of the gasified fly ash; the fly ash with high carbon content is difficult to be recycled and disposed.

The technical proposal that the gasification fly ash is directly sent into the gasification furnace to participate in the gasification reaction again is adopted, so that the resource treatment of the gasification fly ash is not fundamentally solved, and the treatment problem of the gasification fly ash is not substantially solved. Because the reaction activity of the gasified fly ash is lower than that of carbon particles just entering the furnace after the gasified fly ash leaves from the furnace, the gasified fly ash is directly sent back to the furnace, because the particle size of the fly ash is very small, the residence time in the furnace is limited, in addition, the temperature is the main influence factor of the gasification reaction activity, a high-temperature area cannot be integrally or locally created, and the reaction rate of the gasified fly ash is basically a constant value. Therefore, in order to realize the resource treatment of the gasified fly ash and the effective utilization of the heat energy, it is necessary to develop a new gasified fly ash treatment system.

Disclosure of Invention

The invention solves the problems: the defects of the prior art are overcome, and a gasification fly ash recycling treatment and heat energy recycling system and method are provided, so that heat energy recycling is realized, and the carbon conversion rate and the cold gas efficiency of the whole gasification system can be effectively improved.

The technical scheme of the invention is as follows: a gasification fly ash resource treatment and heat energy recycling system and a method thereof mainly comprise a circulating fluidized bed gasification furnace (1), a dust remover device (4), a fly ash melting furnace (5) and a high temperature separator (7).

The coal is gasified in the circulating fluidized bed gasification furnace (1), the gasification agents required by gasification are respectively fed in by the bottom (2) of the hearth and the middle and lower oxidation zone (8) of the hearth in a grading way, the gasification agent fed in from the bottom (2) of the hearth is taken as a first-stage gasification agent, the gasification agents fed in from the middle and lower oxidation zone (8) of the hearth at different heights are taken as second-stage gasification agents, the quantities of the first-stage gasification agent and the second-stage gasification agent can be adjusted according to the process requirements and gasification indexes, and the quantity of the second-stage gasification agent fed in from the middle and lower oxidation zone of the hearth accounts for 20-30% of the total gasification.

high-temperature coal gas generated by the circulating fluidized bed gasification furnace (1) enters a heat exchanger (3) to exchange heat to 200-250 ℃, low-temperature coal gas enters a dust remover device (4) to remove dust, the dust content of the coal gas is reduced to below 30mg/Nm ³, and the carbon content of gasified fly ash collected by a cyclone dust remover and a bag-type dust remover is 30-40%.

The method comprises the steps of feeding collected gasified fly ash into a fly ash melting furnace (5), controlling the temperature in the fly ash melting furnace to be above the ash melting point temperature according to different ash melting points of coal, generally, 1500-1800 ℃, discharging a melt from the bottom of the fly ash melting furnace, discharging high-temperature flue gas containing high-concentration CO ₂ (40-50%) from the upper part of the fly ash melting furnace at 1500-1800 ℃, introducing part of secondary gasifying agent along a pipeline (6), quenching the high-temperature flue gas when the high-temperature flue gas meets the cold secondary gasifying agent, simultaneously preheating the secondary gasifying agent, controlling the gas temperature after the high-temperature flue gas is mixed with part of the secondary gasifying agent to be 900-1000 ℃, quenching the high-temperature flue gas or molten particles carried in the flue gas into small spheres during the quenching process, dedusting the mixed gas by a high-temperature separator (7), and feeding the mixed gas into a hearth from an oxidation zone (8) at the middle lower part of the hearth to participate in gasification, wherein the high-temperature mixed flue gas or coal gas is introduced from different heights of a.

The high-temperature flue gas or coal gas discharged from the fly ash melting furnace (5) is mixed with part of secondary gasifying agents, then the mixture is directly introduced into the circulating fluidized bed gasification furnace (1) without passing through the high-temperature separator (7), and the molten particles which are quenched into small balls are discharged from the bottom of the circulating fluidized bed gasification furnace (1) along with bottom slag.

The high temperature separator (7) has high temperature resistance of 1500-1800 ℃ and adopts inertial separation or centrifugal separation as the separation form.

Compared with the prior art, the invention has the advantages that:

(1) The invention realizes the resource treatment of the gasification fly ash by matching the fly ash melting furnace in the original circulating fluidized bed coal gasification furnace, most chemical heat in the fly ash enters the circulating fluidized bed gasification furnace, and the carbon conversion rate and the cold gas efficiency of the whole system are improved. The solid matter after the fly ash is melted can be used as building material raw material, and the resource treatment of the fly ash is thoroughly realized.

(2) Because the invention uses the second-stage gasification agent to realize the rapid cooling of the high-temperature flue gas of the melting furnace, the molten particles in the high-temperature flue gas are quenched by the rapid cooling, and the molten particles are prevented from being adhered to the flue in the slow cooling process; the preheating of the secondary gasification agent is realized in the process.

(3) CO ₂ in the high-temperature flue gas of the melting furnace is an effective gasifying agent for the gasification reaction, and the high-temperature flue gas is introduced into the circulating fluidized bed gasification furnace to strengthen the gasification reaction and improve the cold gas efficiency of the whole system.

Drawings

FIG. 1 is a schematic diagram of a gasification fly ash recycling system and method according to the present invention;

FIG. 2 is a schematic diagram of a gasification fly ash recycling system and method according to another embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.

The core idea of the invention is that the fly ash melting furnace is matched with the original circulating fluidized bed coal gasification furnace to realize resource treatment of gasification fly ash, high-temperature flue gas from the fly ash melting furnace can realize preheating of gasification agent and rapid cooling of the high-temperature flue gas, and molten particles carried in the flue gas are quenched into small spheres, most of chemical heat in the gasification fly ash is converted into flue gas enthalpy and enters the gasification furnace, so that heat energy is recycled, CO ₂ in the high-temperature mixed flue gas is used as a supplementary gasification agent to participate in gasification reaction, and the carbon conversion rate and the cold coal gas efficiency of the whole gasification system can be effectively improved.

as shown in figure 1, the invention relates to a gasification fly ash resource treatment and heat energy recycling system, which comprises a circulating fluidized bed gasification furnace 1, a heat exchanger 3, a dust remover device 4, a fly ash melting furnace 5 and a high-temperature separator 7.

The coal is gasified in the circulating fluidized bed gasification furnace 1, the gasification agent required by gasification is respectively fed from the bottom 2 of the hearth and the oxidation zone 8 at the middle lower part of the hearth, the gasification dosage of the oxidation zone at the bottom of the hearth and the oxidation zone at the middle lower part of the hearth can be adjusted according to the process requirement and gasification index, and the gasification dosage fed into the oxidation zone at the middle lower part of the hearth accounts for 20-30% of the total gasification dosage of the circulating fluidized bed gasification furnace.

High-temperature coal gas generated by the circulating fluidized bed gasification furnace 1 enters a heat exchanger 3 to exchange heat to about 200 ℃, and low-temperature coal gas enters a dust remover device 4 to remove dust, so that the dust content of the coal gas is reduced to below 30mg/Nm 3. The carbon content of the gasified fly ash collected by the dust remover equipment is 30-40%.

sending the collected gasified fly ash into a fly ash melting furnace 5, controlling the temperature in the fly ash melting furnace to be 1500-1800 ℃ according to different ash melting points of coal, and discharging the melt from the bottom of the fly ash melting furnace; high-temperature gas or flue gas containing high-concentration CO2 at 1500-1800 ℃ is discharged from the upper part of a fly ash melting furnace 5, part of gasifying agent is introduced along a path pipeline 6, the high-temperature gas or flue gas is quenched when meeting cold gasifying agent, preheating of the gasifying agent is realized at the same time, the temperature of the gas after mixing the gas or flue gas and the gasifying agent is controlled at 900-1000 ℃, molten particles carried in the high-temperature gas or flue gas are quenched into small spheres in the quenching process, and the mixed gas is dedusted by a high-temperature separator 7 and then fed into a hearth of a gasification furnace from an oxidation zone 8 at the middle lower part of the hearth to participate in gasification.

According to the process and technical requirements, the dust remover 4 in the invention can be single-stage separation or multi-stage separation; the high temperature separator 7 may take the form of other separators; the mixed gas of the secondary gasification agent and the high-temperature flue gas of the melting furnace can be introduced from different heights of the circulating fluidized bed gasification furnace 1.

The high-temperature flue gas from the melting furnace and the secondary gasifying agent can be directly introduced into the gasification furnace without passing through the high-temperature separator 7 after being mixed, and the molten particles quenched into small balls are discharged from the bottom of the gasification furnace along with the bottom slag.

In another embodiment of the invention, the gasification fly ash resource treatment and heat energy recycling system is not provided with the high temperature separator 7, namely the system comprises a circulating fluidized bed gasification furnace 1, a heat exchanger 3, a dust removal device 4 and a fly ash melting furnace 5 which are connected in sequence, and the outlet of the fly ash melting furnace 5 is communicated with the hearth of the gasification furnace through a path pipeline 6. The bottom of the hearth of the gasification furnace is provided with a bottom slag outlet, and molten slag generated in the gasification process is discharged from the bottom slag outlet. The rest of the procedure was the same as in example 1.

In a word, the invention realizes the resource treatment of the gasification fly ash by matching the fly ash melting furnace in the original circulating fluidized bed coal gasification furnace, the preheating of the secondary gasification agent can be realized by the high-temperature flue gas from the melting furnace, the rapid cooling of the high-temperature flue gas can be realized, and the molten particles carried in the flue gas are quenched into small spheres, most of the chemical heat in the gasification fly ash is converted into flue gas enthalpy to enter the gasification furnace, thereby realizing the reutilization of heat energy, and the CO ₂ in the high-temperature mixed flue gas is used as a supplementary secondary gasification agent to participate in the gasification reaction, thereby effectively improving the carbon conversion rate and the cold gas efficiency of the whole gasification system.

The above examples are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims. Various equivalent substitutions and modifications can be made without departing from the spirit and principles of the invention, and are intended to be within the scope of the invention.