Waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas

Abstract

The utility model provides a waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas, which comprises a first dust remover, a waste heat boiler front evaporation section, a first gas heat exchanger, a deoxygenated water heat exchanger, a second gas heat exchanger and a second dust remover which are arranged between a charcoal burner and a waste heat boiler and are connected in sequence, the first dust remover is located in the charcoal burner, the first gas heat exchanger is located on a gas inlet pipeline of the charcoal burner, the deoxygenated water heat exchanger is located on a deoxygenated water inlet pipeline of the waste heat boiler, the second gas heat exchanger is located on an air inlet pipeline of the waste heat boiler, and a gas outlet of the second dust remover is connected with a gas inlet of the waste heat boiler. According to the utility model, the multi-stage dust remover and the heat exchanger are arranged on the basis of the existing equipment of the pyrolysis system, the flue gas exchanges heat with fed materials of the waste heat boiler and the charking device, the flue gas heat is recovered in a graded manner, the waste heat is fully recovered, and the problem that the equipment is blocked by dust is avoided; the device is reasonable in structural design, low in equipment cost and wide in application range.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas recovery and treatment, and relates to a waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas. Background Art

[0002] Given the proportion of coal in my country's energy production and consumption structure, the development of pulverized coal pyrolysis technology is an important measure to alleviate energy shortages and improve the energy structure. In the research of pulverized coal pyrolysis process, pyrolysis usually produces primary products such as coal gas, tar, and pulverized coke. Among them, pulverized coke often needs to be recycled as a heat carrier. The heat carrier is heated by its own partial combustion. The high-temperature heat carrier carries heat and mixes with the pulverized coal to achieve the pyrolysis process of the pulverized coal. During the combustion of pulverized coke, a large amount of high-temperature dusty flue gas is generated. The dust treatment and waste heat recovery in this flue gas are the key to achieving energy-saving and efficient charcoal burning reaction.

[0003] The main dust removal technologies for the high-temperature, dusty flue gas produced by the combustion of pulverized coke include cyclone separation, electrostatic separation, and filtration separation. Cyclone separation can usually only separate larger particles, and some small dust particles will still affect the heat exchange effect of subsequent heat exchange equipment. Electrostatic separation has a high dust removal effect, but the equipment cost is relatively high. Filtration separation involves passing high-temperature dust-laden gas through filter materials for gas-solid separation. However, high-temperature dust-laden flue gas causes severe flow wear on the filter materials, resulting in a large pressure drop on the equipment, resulting in a short equipment life and high cost. Therefore, dust removal and waste heat recovery for high-temperature dust-laden flue gas have become one of the difficult problems in pulverized coal pyrolysis technology, requiring the selection of multiple equipment and unit operations for comprehensive treatment based on the characteristics of the flue gas.

[0004] CN 221005034U discloses a boiler flue gas waste heat recovery system. The system includes a boiler, a flue gas waste heat recovery device, an air preheater, a dust collector, a chimney, and a blower. The boiler is equipped with a coal inlet, a boiler air inlet, and a boiler flue gas outlet. The flue gas waste heat recovery device includes a flue gas inlet, a flue gas outlet, a bypass flue, a preheating section, a heating section, a downcomer, and a steam drum. The flue gas inlet is connected to the flue gas outlet via a bypass flue. The preheating section is equipped with a flue gas waste heat recovery device working medium water inlet and a preheating section working medium water outlet. The heating section is equipped with a heating section working medium water inlet and a heating section steam-water outlet. The steam drum is equipped with a drum steam-water inlet, a drum working medium water outlet, and a flue gas waste heat recovery device working medium water outlet. Although this system involves flue gas waste heat recovery, its source is boiler flue gas, and the main waste heat recovery equipment is related equipment in the boiler system. This differs from the flue gas source of fine coke combustion, and the corresponding dust removal and waste heat recovery equipment is also different.

[0005] CN 107723012A discloses a system and method for producing coal tar gas by coupling multi-stage fluidized bed pulverized coal pyrolysis and dust removal. The system includes a drying unit, a fluidized bed pyrolysis and dust removal unit, a circulating semi-coke heating unit, a waste heat recovery unit, and a post-processing unit. The pyrolysis raw gas, after undergoing multi-stage cyclone dust removal, is then heat-exchanged with dried granular coal. Heavy components of the raw gas are condensed on the granular coal, entraining fine powder to achieve dust removal, while also undergoing secondary pyrolysis. The semi-coke from the fluidized bed pyrolysis is soot-blown and used as filter material for particle dust removal, further filtering and removing dust from the raw gas. The system focuses on the fluidized bed pyrolysis unit for pulverized coal, not on subsequent dust removal and waste heat recovery. Furthermore, the waste heat recovery unit exchanges heat with the drying and fluidized bed pyrolysis units, not with the waste heat boiler.

[0006] In summary, for the waste heat recovery of high-temperature dusty flue gas generated during the pyrolysis process, it is necessary to select a suitable combination of equipment and unit operations based on the characteristics of the flue gas, so that dust particles can be removed in time without causing equipment blockage, heat can be recovered in a step-by-step manner, heat loss can be avoided, and efficient utilization of heat inside the production device can be achieved. Utility Model Content

[0007] In response to the problems existing in the prior art, the purpose of the present utility model is to provide a waste heat recovery device for pyrolysis of high-temperature dust-laden flue gas. The device combines existing equipment in the pyrolysis system, and is equipped with a multi-stage dust collector and a heat exchanger to separate the dust in the high-temperature dust-laden flue gas and recover the heat carried by it in a graded manner. This can not only avoid the problem of dust clogging equipment during flue gas treatment, but also fully recover the heat energy in the flue gas to achieve the purpose of energy saving and consumption reduction.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] The utility model provides a waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas, the waste heat recovery device comprising a first dust collector, a pre-evaporation section of the waste heat boiler, a first gas heat exchanger, a deoxygenated water heat exchanger, a second gas heat exchanger and a second dust collector which are sequentially connected between the charcoal burner and the waste heat boiler, the first dust collector being arranged inside the charcoal burner, the first gas heat exchanger being located on the gas inlet pipeline of the charcoal burner, the deoxygenated water heat exchanger being located on the deoxygenated water inlet pipeline of the waste heat boiler, the second gas heat exchanger being located on the air inlet pipeline of the waste heat boiler, and the gas outlet of the second dust collector being connected to the gas inlet of the waste heat boiler.

[0010] In the present invention, for the treatment of high-temperature dust-containing flue gas generated by coal pyrolysis and charcoal burning processes, according to the dust particles in the flue gas and the heat carried by the high temperature, the present invention utilizes the existing equipment in the pulverized coal pyrolysis system to exchange heat with the feed of waste heat boilers, charcoal burners and other equipment. In particular, a first-stage dust collector is first set to remove coarse particles to avoid the problem of dust clogging the equipment, and then a multi-stage heat exchanger is set to cool the flue gas in steps, and the heat carried by it is recovered and utilized in a graded manner. Finally, it is subjected to a dust removal operation to remove fine particles in the flue gas to meet the requirements of the subsequent system for the dust content of the flue gas. The treated flue gas is then used as fuel gas for the waste heat boiler to provide combustion heat for the steam produced by the waste heat boiler, thereby realizing full recovery of waste heat in the system. The device has a reasonable structural design and utilizes the original equipment for combined design, which reduces equipment cost, saves energy consumption, and has a wide range of applications.

[0011] In the present invention, the temperature of the high-temperature dust-containing flue gas at the outlet of the charcoal burner is 600-750°C, for example, 600°C, 620°C, 650°C, 680°C, 700°C, 720°C or 750°C, and the pressure is 0.15-0.5MPaG, for example, 0.15MPaG, 0.2MPaG, 0.25MPaG, 0.3MPaG, 0.35MPaG, 0.4MPaG, 0.45MPaG or 0.5MPaG, etc.; but it is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0013] As a preferred technical solution of the present invention, the first dust collector includes a cyclone separator, and the cyclone separator is provided with at least one stage, such as one stage, two stages or three stages, etc. When the cyclone separator includes two stages or more, they are arranged in series.

[0014] In the utility model, the first dust collector is selected to separate the coarse particles in the high-temperature dusty flue gas. At this time, the dust content in the flue gas can be reduced to 14g / Nm 3 Below, for example 14g / Nm 3 、13g / Nm 3 、12g / Nm 3 、10g / Nm 3 , 9g / Nm 3 , 8g / Nm 3 or 6g / Nm 3 etc., but are not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0015] As a preferred technical solution of the present invention, the gas phase outlet of the first dust collector is connected to the inlet of the pre-evaporation section of the waste heat boiler. The particle size of the dust in the gas phase separated by the first dust collector is less than 20μm, for example, 20μm, 18μm, 15μm, 12μm, 10μm, 8μm, 6μm, 4μm or 2μm, etc., and the average particle size is not greater than 10μm, for example, 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm or 1μm, etc., but is not limited to the listed values, and other values not listed within this numerical range are also applicable.

[0016] As a preferred technical solution of the present invention, the front evaporation section of the waste heat boiler is a shell and tube heat exchanger or a shell and tube heat exchanger.

[0017] The heat exchange medium in the front evaporation section of the waste heat boiler is deoxygenated water, which comes from the plant's pipeline network and enters the waste heat boiler drum after heat exchange in the front evaporation section.

[0018] In the present invention, when the flue gas passes through the front evaporation section of the waste heat boiler, it exchanges heat with the deoxygenated water. After the heat exchange, the flue gas temperature is 500-600°C, for example, 500°C, 520°C, 540°C, 550°C, 560°C, 580°C or 600°C, etc., but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0019] As a preferred technical solution of the present invention, the cold source inlet of the first gas heat exchanger is connected to the fan outlet in front of the charcoal burner, and the cold source outlet of the first gas heat exchanger is connected to the gas inlet of the charcoal burner.

[0020] In the present invention, the gas source of the first gas heat exchanger is the main fan outlet of the charcoal burner. The main fan provides air for the charcoal burner reaction. After being heated by the first gas heat exchanger, the air enters the charcoal burner. The air can increase the temperature of the gas entering the charcoal burner, accelerate the charcoal heating rate, reduce the amount of coke in the charcoal burner, save energy, and thus reduce the dust and CO content in the charcoal burning flue gas; the temperature of the flue gas after passing through the first gas heat exchanger drops to 380-420°C, for example, 380°C, 390°C, 400°C, 410°C or 420°C, etc., but is not limited to the listed values, and other values not listed within this numerical range are also applicable.

[0021] As a preferred technical solution of the present invention, an auxiliary combustion chamber is further provided between the first gas heat exchanger and the charcoal burner. The auxiliary combustion chamber is provided with an air inlet, a fuel inlet and a flue gas outlet. The flue gas outlet of the auxiliary combustion chamber is connected to the gas inlet of the charcoal burner.

[0022] As a preferred technical solution of the present invention, the deaerated water heat exchanger is located in the economizer section of the waste heat boiler.

[0023] In the present invention, after passing through the deaerator water heat exchanger, the temperature of the flue gas is reduced to 240-280°C, for example, 240°C, 250°C, 260°C, 270°C or 280°C, etc., but is not limited to the listed values, and other values not listed within this numerical range are also applicable; then, after passing through the second gas heat exchanger and exchanging heat with the inlet air of the waste heat boiler, the temperature is reduced to 180-220°C, for example, 180°C, 190°C, 200°C, 210°C or 220°C, etc., but is not limited to the listed values, and other values not listed within this numerical range are also applicable.

[0024] As a preferred technical solution of the present invention, the second dust collector includes a bag dust collector, and the material of the bag dust collector includes polytetrafluoroethylene (PTFE).

[0025] In this utility model, when the bag filter is made of polytetrafluoroethylene, the maximum temperature it can withstand is 260°C. Therefore, the high-temperature flue gas needs to be cooled by heat exchange and then subjected to secondary dust removal to meet the temperature requirements of the bag filter. The secondary dust removal is set to meet the subsequent requirements for the dust content of the flue gas. The dust content of the outlet gas of the bag filter is less than 10mg / Nm 3 , for example 10mg / Nm 3 , 9mg / Nm 3 、8mg / Nm 3 , 7mg / Nm 3 、6mg / Nm 3 、5mg / Nm 3 , 4mg / Nm 3 、3mg / Nm 3 , 2mg / Nm 3 or 1mg / Nm 3 etc., but are not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0026] As a preferred technical solution of the present invention, the gas discharged from the second dust collector is cooled and dust-removed gas, which is burned in the waste heat boiler to generate waste heat boiler flue gas, and the deoxygenated water in the waste heat boiler generates steam.

[0027] In the present invention, the cooling and dust removal gas contains, in addition to nitrogen and carbon dioxide, combustible gas components including carbon monoxide, hydrogen, methane, ethylene, ethane and the like.

[0028] As a preferred technical solution of the present invention, the waste heat recovery device further includes a flue gas denitrification device, and the flue gas outlet of the waste heat boiler is connected to the inlet of the flue gas denitrification device.

[0029] In the present invention, the cooled and dust-removed gas after the flue gas dust removal and waste heat recovery is sent to the waste heat boiler for combustion, and the steam pressure generated is 0.5-5 MPaG, such as 0.5 MPaG, 1 MPaG, 2 MPaG, 3 MPaG, 4 MPaG or 5 MPaG, and the steam temperature is 360-400°C, such as 360°C, 370°C, 380°C, 390°C or 400°C, etc., so as to make full use of the characteristics of the components in the flue gas, burn and supply heat, and avoid direct emission of hydrocarbon-rich gas. The waste heat boiler flue gas after combustion is denitrified and then meets the emission standards.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The device described in the present invention is equipped with a multi-stage dust collector and a multi-stage heat exchanger on the basis of the existing equipment in the pyrolysis system, so as to exchange heat multiple times between the high-temperature dust-laden flue gas and the feed of the waste heat boiler, charcoal burner and other equipment, and to recover and utilize the heat carried by the flue gas in a graded manner, thereby achieving full recovery of the waste heat in the system and avoiding the problem of dust clogging the equipment;

[0032] (2) The device structure of the present invention is reasonably designed, and the original equipment is used for combined design, which reduces equipment cost, saves energy consumption, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of a waste heat recovery device for pyrolyzing high-temperature dust-laden flue gas provided in Example 1 of the present utility model;

[0034] Among them, 1-charcoal burner, 2-first dust collector, 3-waste heat boiler pre-evaporation section, 4-first gas heat exchanger, 5-deoxygenated water heat exchanger, 6-second gas heat exchanger, 7-second dust collector, 8-waste heat boiler, 9-fan, 10-auxiliary combustion chamber, 11-flue gas denitrification device. DETAILED DESCRIPTION

[0035] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are merely simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0036] The following are typical but non-limiting embodiments of the present invention:

[0037] Example 1:

[0038] This embodiment provides a waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas. The structural diagram of the waste heat recovery device is as follows: Figure 1As shown, it includes a first dust collector 2, a waste heat boiler pre-evaporation section 3, a first gas heat exchanger 4, a deoxygenated water heat exchanger 5, a second gas heat exchanger 6 and a second dust collector 7, which are arranged in sequence between the charcoal burner 1 and the waste heat boiler 8. The first dust collector 2 is arranged inside the charcoal burner 1, the first gas heat exchanger 4 is located on the gas inlet pipeline of the charcoal burner 1, the deoxygenated water heat exchanger 5 is located on the deoxygenated water inlet pipeline of the waste heat boiler 8, the second gas heat exchanger 6 is located on the air inlet pipeline of the waste heat boiler 8, and the gas outlet of the second dust collector 7 is connected to the gas inlet of the waste heat boiler 8.

[0039] The first dust collector 2 includes a cyclone separator, and the cyclone separator is provided with one stage.

[0040] The gas phase outlet of the first dust collector 2 is connected to the inlet of the pre-evaporation section 3 of the waste heat boiler. The particle size of the dust in the gas phase separated by the first dust collector 2 is less than 20 μm, and the average particle size is 10 μm.

[0041] The pre-evaporation section 3 of the waste heat boiler is a shell and tube heat exchanger. The heat exchange medium in the pre-evaporation section 3 of the waste heat boiler is deoxygenated water. The deoxygenated water comes from the plant pipeline network and enters the steam drum of the waste heat boiler 8 after heat exchange in the pre-evaporation section.

[0042] The cold source inlet of the first gas heat exchanger 4 is connected to the outlet of the fan 9 in front of the charcoal burner 1 , and the cold source outlet of the first gas heat exchanger 4 is connected to the gas inlet of the charcoal burner 1 .

[0043] An auxiliary combustion chamber 10 is also provided between the first gas heat exchanger 4 and the charcoal burner 1. The auxiliary combustion chamber 10 is provided with an air inlet, a fuel inlet and a flue gas outlet. The fuel includes fuel oil and fuel gas. The flue gas outlet of the auxiliary combustion chamber 10 is connected to the gas inlet of the charcoal burner 1.

[0044] The deaerated water heat exchanger 5 is located in the economizer section of the waste heat boiler 8 .

[0045] The second dust collector 7 includes a bag dust collector, and the material of the bag dust collector is polytetrafluoroethylene.

[0046] The gas discharged from the second dust collector 7 is a cooled and dust-removed gas, which is burned in the waste heat boiler 8 to generate waste heat boiler flue gas, and the deoxygenated water in the waste heat boiler 8 generates steam.

[0047] The waste heat recovery device further includes a flue gas denitrification device 11 , and the flue gas outlet of the waste heat boiler 8 is connected to the inlet of the flue gas denitrification device 11 .

[0048] Example 2:

[0049] This embodiment provides a waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas, and the waste heat recovery device includes a first dust collector 2, a waste heat boiler pre-evaporation section 3, a first gas heat exchanger 4, a deoxygenated water heat exchanger 5, a second gas heat exchanger 6 and a second dust collector 7, which are arranged between the charcoal burner 1 and the waste heat boiler 8 and connected in sequence. The first dust collector 2 is arranged inside the charcoal burner 1, the first gas heat exchanger 4 is located on the gas inlet pipeline of the charcoal burner 1, the deoxygenated water heat exchanger 5 is located on the deoxygenated water inlet pipeline of the waste heat boiler 8, the second gas heat exchanger 6 is located on the air inlet pipeline of the waste heat boiler 8, and the gas outlet of the second dust collector 7 is connected to the gas inlet of the waste heat boiler 8.

[0050] The first dust collector 2 includes a cyclone separator, and the cyclone separator is provided with two stages.

[0051] The gas phase outlet of the first dust collector 2 is connected to the inlet of the pre-evaporation section 3 of the waste heat boiler. The particle size of the dust in the gas phase separated by the first dust collector 2 is less than 15 μm, and the average particle size is 7 μm.

[0052] The pre-evaporation section 3 of the waste heat boiler is a shell and tube heat exchanger. The heat exchange medium in the pre-evaporation section 3 of the waste heat boiler is deoxygenated water. The deoxygenated water comes from the plant pipeline network and enters the steam drum of the waste heat boiler 8 after heat exchange in the pre-evaporation section.

[0053] The cold source inlet of the first gas heat exchanger 4 is connected to the outlet of the fan 9 in front of the charcoal burner 1 , and the cold source outlet of the first gas heat exchanger 4 is connected to the gas inlet of the charcoal burner 1 .

[0054] An auxiliary combustion chamber 10 is also provided between the first gas heat exchanger 4 and the charcoal burner 1. The auxiliary combustion chamber 10 is provided with an air inlet, a fuel inlet and a flue gas outlet. The fuel includes fuel oil. The flue gas outlet of the auxiliary combustion chamber 10 is connected to the gas inlet of the charcoal burner 1.

[0055] The deaerated water heat exchanger 5 is located in the economizer section of the waste heat boiler 8 .

[0056] The second dust collector 7 includes a bag dust collector, and the material of the bag dust collector is polytetrafluoroethylene.

[0057] The gas discharged from the second dust collector 7 is a cooled and dust-removed gas, which is burned in the waste heat boiler 8 to generate waste heat boiler flue gas, and the deoxygenated water in the waste heat boiler 8 generates steam.

[0058] The waste heat recovery device further includes a flue gas denitrification device 11 , and the flue gas outlet of the waste heat boiler 8 is connected to the inlet of the flue gas denitrification device 11 .

[0059] Example 3:

[0060] This embodiment provides a waste heat recovery device for pyrolyzing high-temperature dust-containing flue gas, and the waste heat recovery device includes a first dust collector 2, a waste heat boiler pre-evaporation section 3, a first gas heat exchanger 4, a deoxygenated water heat exchanger 5, a second gas heat exchanger 6 and a second dust collector 7, which are arranged between the charcoal burner 1 and the waste heat boiler 8 and connected in sequence. The first dust collector 2 is arranged inside the charcoal burner 1, the first gas heat exchanger 4 is located on the gas inlet pipeline of the charcoal burner 1, the deoxygenated water heat exchanger 5 is located on the deoxygenated water inlet pipeline of the waste heat boiler 8, the second gas heat exchanger 6 is located on the air inlet pipeline of the waste heat boiler 8, and the gas outlet of the second dust collector 7 is connected to the gas inlet of the waste heat boiler 8.

[0061] The first dust collector 2 includes a cyclone separator, and the cyclone separator is provided with two stages.

[0062] The gas phase outlet of the first dust collector 2 is connected to the inlet of the pre-evaporation section 3 of the waste heat boiler. The particle size of the dust in the gas phase separated by the first dust collector 2 is less than 18 μm, and the average particle size is 9 μm.

[0063] The pre-evaporation section 3 of the waste heat boiler is a shell and tube heat exchanger. The heat exchange medium in the pre-evaporation section 3 of the waste heat boiler is deoxygenated water. The deoxygenated water comes from the plant pipeline network and enters the steam drum of the waste heat boiler 8 after heat exchange in the pre-evaporation section.

[0064] The cold source inlet of the first gas heat exchanger 4 is connected to the outlet of the fan 9 in front of the charcoal burner 1 , and the cold source outlet of the first gas heat exchanger 4 is connected to the gas inlet of the charcoal burner 1 .

[0065] An auxiliary combustion chamber 10 is also provided between the first gas heat exchanger 4 and the charcoal burner 1. The auxiliary combustion chamber 10 is provided with an air inlet, a fuel inlet and a flue gas outlet. The fuel includes fuel gas. The flue gas outlet of the auxiliary combustion chamber 10 is connected to the gas inlet of the charcoal burner 1.

[0066] The deaerated water heat exchanger 5 is located in the economizer section of the waste heat boiler 8 .

[0067] The second dust collector 7 includes a bag dust collector, and the material of the bag dust collector is polytetrafluoroethylene.

[0068] The gas discharged from the second dust collector 7 is a cooled and dust-removed gas, which is burned in the waste heat boiler 8 to generate waste heat boiler flue gas, and the deoxygenated water in the waste heat boiler 8 generates steam.

[0069] The waste heat recovery device further includes a flue gas denitrification device 11 , and the flue gas outlet of the waste heat boiler 8 is connected to the inlet of the flue gas denitrification device 11 .

[0070] The waste heat recovery device in the above embodiment is used to remove dust from high-temperature dusty flue gas and recover waste heat. The operation process includes:

[0071] The flue gas with a temperature of 600-750℃ and a temperature of 0.15-0.5MPaG at the outlet of the charcoal burner is initially dusted by a cyclone separator to separate the coarse particles. The dust content in the flue gas is 14g / Nm 3 Below, of which the particle size is basically fine dust below 10μm; this high-temperature dust-laden flue gas first passes through the pre-evaporation section of the waste heat boiler for heat exchange to 500-600℃, and then exchanges heat with the air at the outlet of the main fan of the charcoal burner to 380-420℃, and then exchanges heat with the deaerated water heat exchanger to 240-280℃ in the economizer section of the waste heat boiler, and then exchanges heat with the inlet air of the waste heat boiler to 180-220℃, and enters the bag filter for dust removal. After the cooled and dust-removed gas enters the waste heat boiler for combustion to generate medium-pressure steam, and the waste heat boiler flue gas is sent to the denitrification device for treatment and then discharged into the air at high altitude after meeting the standards, so as to fully recover the waste heat of the system.

[0072] From the above embodiments, it can be seen that the device of the present invention is provided with a multi-stage dust collector and a multi-stage heat exchanger on the basis of the existing equipment in the pyrolysis system, and performs multiple heat exchanges between the high-temperature dust-containing flue gas and the feed of the waste heat boiler, charcoal burner and other equipment, and recovers and utilizes the heat carried by the flue gas in a graded manner, thereby achieving full recovery of the waste heat in the system and avoiding the problem of dust clogging the equipment; the device has a reasonable structural design and utilizes the original equipment for combined design, which reduces the equipment cost, saves energy consumption, and has a wide range of applications.

[0073] The applicant declares that while the above-described embodiments illustrate the detailed apparatus of the present invention, the present invention is not limited to the above-described detailed apparatus, nor does it imply that the present invention must rely on the above-described detailed apparatus in order to be implemented. Persons skilled in the art should understand that any improvements to the present invention, equivalent replacements for the apparatus of the present invention, additions of auxiliary devices, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A waste heat recovery device for pyrolysis of high-temperature dusty flue gas, characterized in that: The waste heat recovery device includes a first dust collector, a pre-evaporation section of the waste heat boiler, a first gas heat exchanger, a deoxygenated water heat exchanger, a second gas heat exchanger and a second dust collector which are connected in sequence between the charcoal burner and the waste heat boiler. The first dust collector is arranged inside the charcoal burner, the first gas heat exchanger is located on the gas inlet pipeline of the charcoal burner, the deoxygenated water heat exchanger is located on the deoxygenated water inlet pipeline of the waste heat boiler, the second gas heat exchanger is located on the air inlet pipeline of the waste heat boiler, and the gas outlet of the second dust collector is connected to the gas inlet of the waste heat boiler.

2. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 1, characterized in that: The first dust collector includes a cyclone separator, and the cyclone separator is provided with at least one stage.

3. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 1, characterized in that: The gas phase outlet of the first dust collector is connected to the inlet of the pre-evaporation section of the waste heat boiler; The particle size of the dust in the gas phase separated by the first dust collector is less than 20 μm, and the average particle size is not greater than 10 μm.

4. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 1, characterized in that: The pre-evaporation section of the waste heat boiler is a shell-and-tube heat exchanger or a shell-and-tube heat exchanger; The heat exchange medium in the front evaporation section of the waste heat boiler is deoxygenated water, which comes from the plant's pipeline network and enters the waste heat boiler drum after heat exchange in the front evaporation section.

5. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 1, characterized in that: The cold source inlet of the first gas heat exchanger is connected to the outlet of the fan in front of the charcoal burner, and the cold source outlet of the first gas heat exchanger is connected to the gas inlet of the charcoal burner.

6. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 5, characterized in that: An auxiliary combustion chamber is provided between the first gas heat exchanger and the charcoal burner. The auxiliary combustion chamber is provided with an air inlet, a fuel inlet and a flue gas outlet. The flue gas outlet of the auxiliary combustion chamber is connected to the gas inlet of the charcoal burner.

7. The waste heat recovery device for pyrolysis of high-temperature dusty flue gas according to claim 1, characterized in that: The deaerated water heat exchanger is located in the economizer section of the waste heat boiler.

8. The waste heat recovery device for pyrolysis of high-temperature dusty flue gas according to claim 1, characterized in that: The second dust collector includes a bag dust collector.

9. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 1, characterized in that: The gas discharged from the second dust collector is a cooled and dust-removed gas, which is burned in the waste heat boiler to generate waste heat boiler flue gas, and the deoxygenated water in the waste heat boiler generates steam.

10. The waste heat recovery device for pyrolysis of high-temperature dust-containing flue gas according to claim 9, characterized in that: The waste heat recovery device also includes a flue gas denitrification device, and the flue gas outlet of the waste heat boiler is connected to the inlet of the flue gas denitrification device.

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