Method and apparatus for heat recovery from a pyrolysis rotary kiln

Abstract

The application provides a heat recovery method and device of a pyrolysis rotary furnace, and the heat recovery method comprises pyrolysis gas flow condensation: high-temperature pyrolysis gas flows out from a pyrolysis furnace, enters a high-temperature condenser after slag removal, is cooled by a light working medium, high-boiling-point pyrolysis oil components are condensed out, are collected and discharged into a high-boiling-point oil tank for storage, and meanwhile, medium-temperature pyrolysis gas is obtained; working medium circulation: the light working medium absorbs the heat of the high-temperature pyrolysis gas in the high-temperature condenser, evaporates water vapor and becomes a concentrated working medium which is discharged from the lower part of the condenser and returned to a medium absorber, during which, the concentrated and light liquid heat exchanger is used to transfer the heat of the working medium to the light working medium of the high-temperature condenser; the application of the mature technology is a derivative application of the absorption heat pump technology, the working principle is simple, the system route is safe, and the operation is stable.

Description

Technical Field

[0001] This invention relates to the field of pyrolysis furnace technology, and in particular to a method and apparatus for heat recovery in a pyrolysis rotary furnace. Background Technology

[0002] With the development of society and the economy, the amount of solid waste generated has increased dramatically, and the situation of solid waste pollution prevention and control is becoming increasingly severe.

[0003] The need for proper treatment of large amounts of stockpiled solid waste has led to the rapid development of pyrolysis converter equipment in recent years.

[0004] Pyrolysis refers to the process of decomposing organic matter in solid waste by placing it in a pyrolysis reactor and utilizing its thermal instability. This technology can convert polymeric waste into high-value-added energy products and is the most important final treatment method for polymeric waste. It is widely used in the harmless and resource-based treatment of waste such as waste tires, waste plastics, sludge, biomass, waste mineral oil, and tar residue. The main equipment used is the pyrolysis furnace, with pyrolysis converters and vertical furnaces being the most mature and representative pyrolysis equipment.

[0005] A pyrolysis furnace is a device that encloses pyrolysis materials in a furnace body and raises the temperature and pressure inside the furnace through heating. The high temperature causes the pyrolysis materials to decompose into low-molecular-weight materials, and it is widely used in the pyrolysis industry. During operation, fuel heats the bottom or interior of the equipment. Heat is transferred through the outer wall of the furnace or directly into the interior. Once the pyrolysis materials inside the furnace reach the pyrolysis temperature, pyrolysis begins. Simultaneously, the furnace body rotates continuously or an internal stirring mechanism ensures uniform heating and tumbling of the materials, promoting rapid decomposition. The generated pyrolysis gas escapes through a vent pipe section. After passing through a slag removal tank, the escaped pyrolysis gas enters a condenser. At the low temperature of the condenser, the pyrolysis gas first condenses to form pyrolysis oil and then enters a non-condensable gas safety water seal. After passing through the water seal, it is drawn in by a gas fan and blown into the pyrolysis furnace burner, where it is burned as fuel to provide heat to the pyrolysis furnace. The flue gas after combustion is discharged through a flue.

[0006] The technology of pyrolysis furnaces has become very mature after years of use. However, because pyrolysis gas is used as fuel instead of fuel transported from outside the plant, fuel costs have been reduced. Therefore, the research on the technology of pyrolysis furnaces has not paid much attention to the comprehensive utilization of heat. With the gradual increase of national energy conservation and emission reduction policies, this invention uses the principle of absorption heat pump and related technologies to recover and utilize the heat of pyrolysis gas in the pyrolysis gas condenser section, so as to achieve the purpose of energy conservation, consumption reduction and reduction of enterprise production and processing costs.

[0007] In traditional pyrolysis equipment, apart from the heating part for the pyrolysis material, the main heat exchange is located at the pyrolysis gas condenser heat exchanger. That is, the cooling water removes the heat from the pyrolysis gas and condenses the pyrolysis oil components in the pyrolysis gas. After absorbing the heat, the cooling water is discharged into the atmosphere through the cooling tower and then cooled down before returning to the condenser for condensation. In this cycle, the heat is directly discharged into the atmosphere without being utilized, resulting in a waste of heat.

[0008] Therefore, a method and apparatus for heat recovery from a pyrolysis rotary furnace are proposed. Summary of the Invention

[0009] In view of this, the present invention aims to provide a heat recovery method and apparatus for a pyrolysis rotary furnace to solve or alleviate the technical problems existing in the prior art, and at least provide a beneficial alternative.

[0010] The technical solution of this invention is implemented as follows: a method for heat recovery in a pyrolysis rotary furnace, comprising:

[0011] Pyrolysis gas flow condensation: High-temperature pyrolysis gas flows out of the pyrolysis furnace, is removed from the slag, and enters the high-temperature condenser. It is cooled by a dilute working medium, and the high-boiling-point pyrolysis oil components are condensed out, collected, and discharged into a high-boiling-point oil tank for storage. At the same time, medium-temperature pyrolysis gas is obtained.

[0012] The medium-temperature pyrolysis gas enters the medium-temperature condenser for condensation. The medium-boiling-point oil components in the cooled pyrolysis gas are condensed out, collected, and discharged into the medium-boiling-point oil tank for storage, while low-temperature pyrolysis gas is obtained at the same time.

[0013] Low-temperature pyrolysis gas is introduced into a low-temperature condenser, where it is finally cooled once by low-temperature water. The low-boiling-point oil components in the pyrolysis gas are condensed out, collected, and discharged into a low-boiling-point oil tank for storage, while non-condensable gas is obtained at the same time.

[0014] Working medium circulation: The desalted working medium absorbs the heat of the high-temperature pyrolysis gas in the high-temperature condenser, evaporates water vapor and becomes concentrated working medium, and is discharged from the bottom of the condenser and returned to the medium absorber. During this process, it passes through the concentrated and desalted liquid heat exchanger to transfer its own heat to the desalted working medium going to the high-temperature condenser.

[0015] The evaporated water vapor is discharged from the top of the condenser and enters the medium cooler. It is cooled to high temperature condensate by the steam water source and then enters the medium storage tank. The steam water source absorbs heat and then enters the medium absorber.

[0016] The condensate in the medium storage tank enters the medium-temperature condenser through the medium pump and pipeline, is heated by the high-temperature pyrolysis gas, and then enters the medium absorber.

[0017] Condensate is mixed and dissolved with the concentrated working medium returned in the medium absorber and high-temperature condenser to form a desalinated working medium, releasing heat at the same time. The heat generated is carried away by the steam water source in the heat exchange pipeline, and the temperature of the steam water source is heated. The heat of the thermodynamic pyrolysis gas system is transferred to the steam water source. The desalinated working medium is pumped out by the medium pump and sent to the high-temperature condenser to start a new heat exchange cycle. The steam water source enters the steam flash tank.

[0018] Further preferred: the non-condensable gas is a combustible gas.

[0019] A further preferred embodiment: the non-condensable gas, after passing through a non-condensable gas water seal, enters the combustible gas centralized collection section 60 or is returned to the pyrolysis furnace as fuel gas.

[0020] A further preferred embodiment is that the working medium is an aqueous solution of lithium bromide.

[0021] A further preferred embodiment: the steam flash tank stores superheated steam water in liquid form. When in use, the exhaust valve is opened to flash saturated steam for use by the heating department. After use, the steam is recovered and used as steam water to regenerate steam.

[0022] 65. The present invention also provides a heat recovery device for a pyrolysis rotary furnace, characterized in that it includes a pyrolysis...

[0023] Gas flow condensation section and working medium circulation section;

[0024] The pyrolysis gas flow condensation section includes a condensation section and a storage section;

[0025] in:

[0026] The condensation section is used to condense the pyrolysis gas;

[0027] The storage unit described in 70 is used to store the pyrolysis oil obtained after condensing the pyrolysis gas;

[0028] The working medium circulation section is used to complete condensation and heat release by cooperating with the condensation section using the working medium. More preferably, the condensation section includes a high-temperature condenser, a medium-temperature condenser, a low-temperature condenser, and a non-condensable gas water seal connected in sequence.

[0029] A further preferred embodiment: the storage unit includes a high-boiling-point oil tank connected to a high-temperature condenser, a medium-boiling-point oil tank connected to a medium-temperature 75°C condenser, and a low-boiling-point oil tank connected to a low-temperature condenser.

[0030] A further preferred embodiment: the working medium circulation unit includes:

[0031] Medium cooler: Used to cool the high-temperature steam discharged from the high-temperature condenser into high-temperature condensate via an external steam-water source, which is then discharged into the medium storage tank. Simultaneously, it discharges the steam-water source, after absorbing heat, into the medium.

[0032] Absorber;

[0033] 80 Medium Storage Tank: Used to store the working medium condensed by the medium cooler;

[0034] Concentrated-dilute heat exchanger: used for heat exchange between the dilute working medium solution going to the high-temperature condenser and the concentrated working medium solution returning to the medium absorber;

[0035] Medium pump: Used to pump the dilute working medium solution to the high-temperature condenser and to send the condensate in the medium storage tank to the medium-temperature condenser for heat exchange.

[0036] Medium absorber: Used to absorb the condensate after heat exchange in the medium-temperature condenser and turn it into a dilute working medium solution, and release a large amount of heat to raise the temperature of the dilute working medium solution.

[0037] Steam flash tank: Used to store superheated steam water source. When a steam point needs to use steam, the valve is opened to flash generate steam for the steam point to use.

[0038] A further preferred embodiment: The medium absorber is equipped with a closed heat exchange pipe, which allows the steam water source from the medium cooler to flow in the heat exchange pipe and be heated before entering the steam flash tank. At the same time, the concentrated working medium solution returning from the high-temperature condenser replenishes the dilute working medium solution discharged from the absorber.

[0039] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions:

[0040] I. The technology used in this invention is mature and is a derivative application of absorption heat pump technology. It has a simple working principle, a safe system route, and stable operation.

[0041] Second, the present invention can recover heat from pyrolysis gas to generate saturated steam. Saturated steam has a wide range of applications and can be conveniently used in heat-using sections and departments of the plant area, such as heating, evaporation, purging, and thermal cooling.

[0042] Third, the condenser of this invention can condense pyrolysis gas at different temperature ranges to obtain pyrolysis oil components with different boiling points, which facilitates subsequent oil separation and can replace the crude fractionation section of pyrolysis oil, thus reducing the cost of oil separation.

[0043] IV. The preferred working medium of this invention is lithium bromide aqueous solution, which is non-toxic, non-flammable and safe. Other absorption refrigerants can also be used as the working medium.

[0044] Fifth, this invention uses only external cold water in the low-temperature condenser, which greatly reduces the load on the cooling capacity and lowers production and operating costs;

[0045] VI. This invention employs an absorption thermodynamic cycle, which has fewer moving parts, lower operating costs, and lower noise.

[0046] VII. The device of the present invention can replace the condensation device of existing pyrolysis equipment, thereby reducing the overall cost of pyrolysis equipment.

[0047] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a structural diagram of the heat recovery device of the present invention;

[0050] Figure 2 This is a schematic diagram illustrating the heat exchange between the present invention and the external environment;

[0051] Figure 3 This is a schematic diagram of the pyrolysis gas process of the present invention;

[0052] Figure 4 This is a schematic diagram of the working medium flow of the present invention. Detailed Implementation

[0053] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0054] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0055] Example 1

[0056] like Figure 1-4 As shown, this embodiment of the invention provides a method for heat recovery in a pyrolysis rotary furnace, comprising:

[0057] Pyrolysis gas flow condensation: High-temperature pyrolysis gas flows out of the pyrolysis furnace, enters the high-temperature condenser 1-01 after slag removal, and is cooled by a dilute working medium. High-boiling-point pyrolysis oil components are condensed out, collected and discharged into the high-boiling-point oil tank 1-05 for storage, while medium-temperature pyrolysis gas is obtained at the same time.

[0058] The medium-temperature pyrolysis gas enters the medium-temperature condenser 1-02 for condensation. The medium-boiling-point oil component in the cooled pyrolysis gas is condensed out, collected and discharged into the medium-boiling-point oil tank 1-06 for storage, while low-temperature pyrolysis gas is obtained at the same time.

[0059] Low-temperature pyrolysis gas is introduced into low-temperature condenser 1-03, where it is finally cooled once by low-temperature water to condense the low-boiling-point oil components in the pyrolysis gas. The condensed components are collected and discharged into low-boiling-point oil tank 1-07 for storage, while non-condensable gas is obtained at the same time.

[0060] Working medium circulation: The dilute working medium absorbs the heat of the high-temperature pyrolysis gas in the high-temperature condenser 1-01, evaporates water vapor and becomes concentrated working medium, and is discharged from the bottom of the condenser and returned to the medium absorber 2-05. During this period, it passes through the concentrated and dilute liquid heat exchanger 2-03 to transfer its own heat to the dilute working medium going to the high-temperature condenser 1-01.

[0061] The evaporated water vapor is discharged from the top of the condenser and enters the medium cooler 2-01. After being cooled to high temperature condensate by the steam water source, it enters the medium storage tank 2-02. The steam water source absorbs heat and is heated up before entering the medium absorber 2-05.

[0062] The condensate in the medium storage tank 2-02 enters the medium temperature condenser 1-02 through the medium pump 2-04 and pipelines. After being heated by the high temperature pyrolysis gas, it enters the medium absorber 2-05.

[0063] Condensate is mixed and dissolved in the medium absorber 2-05 and the high-temperature condenser 1-01 to form a desalted working medium, releasing heat at the same time. The heat generated is carried away by the steam water source in the heat exchange pipeline, and the temperature of the steam water source is heated. The heat of the thermodynamic pyrolysis gas system is transferred to the steam water source. The desalted working medium is extracted by the medium pump 2-04 and sent to the high-temperature condenser 1-01 to start a new heat exchange cycle. The steam water source enters the steam flash tank 2-06.

[0064] In this embodiment, specifically, the non-condensable gas is a combustible gas.

[0065] In this embodiment, specifically: after passing through the non-condensable gas water seal 1-04, the non-condensable gas enters the combustible gas centralized collection section or is returned to the pyrolysis furnace as fuel gas.

[0066] In this embodiment, specifically, the working medium is an aqueous solution of lithium bromide, and the working medium is not limited to an aqueous solution of lithium bromide. Different absorption working media, such as ammonia-water solution, can be selected according to cost.

[0067] In this embodiment, specifically: the steam flash tank 2-06 stores superheated steam water in liquid state. When in use, the steam exhaust valve is opened to flash saturated steam for use by the heating department. After use, the steam is recovered and used as steam water to regenerate steam.

[0068] The present invention also provides a heat recovery device for a pyrolysis rotary furnace, characterized in that it includes a pyrolysis gas flow condensation section and a working medium circulation section;

[0069] The pyrolysis gas flow condensation section includes a condensation section and a storage section;

[0070] in:

[0071] The condenser section is used to condense the pyrolysis gas;

[0072] The storage section is used to store the pyrolysis oil obtained after condensing the pyrolysis gas;

[0073] The working medium circulation section is used to complete condensation and heat release by using the working medium in conjunction with the condenser section.

[0074] In this embodiment, specifically: the condensation section includes a high-temperature condenser 1-01, a medium-temperature condenser 1-02, a low-temperature condenser 1-03, and a non-condensable gas water seal 1-04 connected in sequence.

[0075] In this embodiment, specifically: the storage unit includes a high-boiling-point oil tank 1-05 connected to the high-temperature condenser 1-01, a medium-boiling-point oil tank 1-06 connected to the medium-temperature condenser 1-02, and a low-boiling-point oil tank 1-07 connected to the low-temperature condenser 1-03.

[0076] In this embodiment, specifically: the working medium circulation unit includes:

[0077] Medium cooler 2-01: Used to cool the high-temperature steam discharged from the high-temperature condenser 1-01 into high-temperature condensate through an external steam water source and then discharge it into the medium storage tank 2-02. At the same time, the steam water source after absorbing heat is discharged into the medium absorber 2-05.

[0078] Medium storage tank 2-02: Used to store the working medium condensed by medium cooler 2-01;

[0079] Concentrated / Diluted Liquid Heat Exchanger 2-03: Used for heat exchange between the dilute working medium solution going to the high-temperature condenser 1-01 and the concentrated working medium solution returning to the medium absorber 2-05.

[0080] Medium pump 2-04: Used to pump the dilute working medium solution to the high temperature condenser 1-01 and to send the condensate in the medium storage tank 2-02 to the medium temperature condenser 1-02 for heat exchange;

[0081] Medium absorber 2-05: Used to absorb the condensate after heat exchange in medium-temperature condenser 1-02 and turn it into a dilute working medium solution, and release a large amount of heat to raise the temperature of the dilute working medium solution.

[0082] Steam flash evaporator 2-06: Used to store superheated steam water source. When a steam point needs to use steam, the valve is opened to flash generate steam for the steam point to use.

[0083] In this embodiment, specifically: the medium absorber 2-05 is equipped with a closed heat exchange pipe, which is used to allow the steam water source from the medium cooler 2-01 to flow in the heat exchange pipe and be heated before entering the steam flash tank 2-06. At the same time, the concentrated working medium solution returned from the high-temperature condenser 1-01 replenishes the dilute working medium solution discharged from the absorber.

[0084] In this embodiment: High-temperature condenser 1-01: This device is a steel tubular heat exchange condenser. The tube side contains pyrolysis gas, and the outside of the tube side contains the working medium, which is a dilute lithium bromide solution. A baffle plate is installed in the shell side space outside the tube side. The baffle plate has a water-blocking weir to increase the heat exchange effect between the working medium and the pyrolysis gas. The pyrolysis gas enters from the bottom and transfers heat to the working medium through the heat exchange tubes. It then flows out from the top and enters the medium-temperature condenser 1-02. The condensed high-boiling-point pyrolysis oil enters the high-boiling-point oil tank 1-05. The working medium enters from the top of the heat exchange shell side. After absorbing heat, it evaporates its own water to become a concentrated lithium bromide solution and then exits from the bottom into the concentrated and dilute liquid heat exchanger 2-03. The evaporated water is discharged from the top of the heat exchange shell side into the medium cooler 2-01.

[0085] In this embodiment: Medium-temperature condenser 1-02: This device, like the high-temperature condenser 1-01, is a steel tubular heat exchange condenser. The tube side contains pyrolysis gas, and the outside of the tube side contains the working medium, namely condensate. Baffles are installed in the shell side space outside the tube side to ensure effective heat exchange between the condensate and the pyrolysis gas in the tube side. The pyrolysis gas also enters from the bottom, transfers heat to the condensate through the heat exchange tubes, and then flows out from the top into the low-temperature condenser 1-03. The condensed medium-boiling point pyrolysis oil enters the medium-boiling point oil tank 1-06. The condensate enters the heat exchange shell side from the bottom, absorbs the heat of the pyrolysis gas, and then exits from the top into the medium absorber 2-05.

[0086] In this embodiment 200: Low-temperature condenser 1-03: This device, like the medium-temperature condenser 1-02, is a steel tubular heat exchanger.

[0087] The hot condenser contains pyrolysis gas inside the tubes and cooling water as the working medium outside the tubes. Baffles are installed in the shell-side space outside the tubes to ensure effective heat exchange between the cooling water and the pyrolysis gas inside the tubes. The pyrolysis gas cools down under the action of the cooling water, and the condensed low-boiling-point pyrolysis oil enters the low-boiling-point oil tank 1-07.

[0088] Non-condensable gas enters the non-condensable gas water seal 1-04, pyrolysis gas enters the equipment from the bottom and undergoes heat exchange, non-condensable gas flows out from the top 205, and cooling water also enters from the bottom and flows out from the top after heat exchange.

[0089] In this embodiment: Non-condensable gas water seal 1-04: This device is a standard chemical water seal used in the chemical industry, and its purpose is to cut off the flames that spread along the gas pipeline during a fire.

[0090] In this embodiment: High-boiling-point oil tank 1-05: This equipment is a standard petrochemical industry oil tank, used to store high-boiling-point pyrolysis oil collected in the high-temperature condenser 1-01.

[0091] 210 In this embodiment: Medium-boiling-point oil tank 1-06: This equipment is a standard petrochemical industry oil tank, used for storing...

[0092] The medium-boiling-point pyrolysis oil is collected and condensed in the medium-temperature condenser 1-02.

[0093] In this embodiment: Low-boiling-point oil tank 1-07: This equipment is a standard petrochemical industry oil tank, used to store low-boiling-point pyrolysis oil collected and condensed in the low-temperature condenser 1-03.

[0094] In this embodiment: Medium cooler 2-01: This device is a heat exchanger, either plate or tubular. Its purpose is to cool the high-temperature steam discharged from the high-temperature condenser 1-01 into high-temperature condensate via an externally connected steam / water source.

[0095] After the water is collected, it is discharged into the medium storage tank 2-02, while the steam water that has absorbed heat goes to the medium absorber 2-05.

[0096] In this embodiment: Medium storage tank 2-02: This device is a pressure storage tank used to store the working medium, i.e. condensate, obtained by the medium cooler 2-01. The condensate stored therein will be pumped into the medium temperature condenser 1-02 by the medium pump 2-04.

[0097] 220 In this embodiment: concentrated and dilute liquid heat exchanger 2-03: This device is a heat exchanger, which can be either a plate type or a tube type heat exchanger. It is used for heat exchange between the dilute working medium solution going to the high-temperature condenser 1-01 and the concentrated working medium solution returning to the medium absorber 2-05, so as to improve the overall thermal efficiency of the equipment.

[0098] In this embodiment: Medium pump 2-04: This pump is used to pump the dilute working medium solution to the high-temperature condenser 1-01 and to send the condensate in the medium storage tank 2-02 to the medium-temperature condenser 1-02 for heat exchange. In order to prevent air from entering the working medium system, a canned pump is selected to prevent air from entering the working medium system.

[0099] In this embodiment: Medium absorber 2-05: This device is a pressure vessel containing a certain amount of working medium. The working medium uses its water absorption property to absorb the condensate after heat exchange in the medium-temperature condenser 1-02 and turn it into a dilute working medium solution. It also releases a large amount of heat to raise the temperature of the dilute working medium solution. There is a closed heat exchange pipe inside the absorber. The steam water source from the medium cooler 2-01 flows in the heat exchange pipe and is heated to above 100°C before entering the steam flash tank 2-06. At the same time, the concentrated working medium solution returned from the high-temperature condenser 1-01 replenishes the dilute working medium solution discharged from the absorber.

[0100] In this embodiment: Steam flash tank 2-06: This tank is a pressure vessel used to store superheated steam water. When the steam point needs to use steam, the valve is opened to flash generate steam for the steam point to use.

[0101] Example 2

[0102] This invention also provides an embodiment of heat recovery using the method and apparatus of this invention, taking the most commonly used working medium, lithium bromide aqueous solution, as an example to illustrate the working principle of this invention:

[0103] Regarding the pyrolysis gas, the pyrolysis gas (above 300°C) flows out of the pyrolysis furnace and enters the high-temperature condenser 1-01 after slag removal. Under the cooling effect of the dilute lithium bromide aqueous solution (about 105°C-120°C), the high-boiling-point pyrolysis oil components will be condensed out, collected, and discharged into the high-boiling-point oil tank 1-05 for storage.

[0104] The pyrolysis gas discharged from the high-temperature condenser 1-01 is cooled to about 120℃-150℃ by the dilute lithium bromide aqueous solution and then enters the medium-temperature condenser 1-02 for condensation. The cooling medium in the equipment is condensate pumped from the medium storage tank 2-02. The medium-boiling point oil component in the cooled pyrolysis gas is condensed out, collected and discharged into the medium-boiling point oil tank 1-06 for storage.

[0105] The pyrolysis gas discharged from the medium-temperature condenser 1-02 has been cooled to below 100°C, and most of the condensable oil components have been condensed out. This low-temperature pyrolysis gas is then passed into the low-temperature condenser 1-03, where it is finally cooled once by low-temperature water (about 20°C-30°C) to condense the low-boiling-point oil components in the pyrolysis gas. After collection, the oil is discharged into the low-boiling-point oil tank 1-07 for storage.

[0106] The non-condensable gas discharged from the low-temperature condenser 1-03 is a combustible gas. After passing through the non-condensable gas water seal 1-04, it enters the combustible gas collection section or is returned to the pyrolysis furnace as fuel gas.

[0107] Regarding the working medium, the dilute lithium bromide aqueous solution (approximately 105℃-120℃) absorbs the heat of the pyrolysis gas in the high-temperature condenser 1-01. After evaporating water vapor, it becomes a concentrated lithium bromide aqueous solution and is discharged from the bottom of the condenser back to the medium absorber 2-05. During this process, it passes through the concentrated and dilute liquid heat exchanger 2-03 to transfer its own heat to the dilute lithium bromide aqueous solution going to the condenser to increase thermal efficiency.

[0108] The evaporated water vapor is discharged from the top of the condenser and enters the medium cooler 2-01. After being cooled to high temperature condensate by the steam water source, it enters the medium storage tank 2-02. The steam water source absorbs heat and then enters the medium absorber 2-05 to further absorb heat and increase its temperature.

[0109] The condensate in the medium storage tank 2-02 enters the medium temperature condenser 1-02 through the medium pump 2-04 and pipeline, is heated by the pyrolysis gas, and then enters the medium absorber 2-05.

[0110] The condensate is mixed with the concentrated lithium bromide aqueous solution returned from the medium absorber 2-05 and the high-temperature condenser 1-01. The strong hygroscopic property of lithium bromide is used to dissolve it into a dilute lithium bromide aqueous solution. At the same time, this dissolution process is exothermic. The heat generated is carried away by the steam water source in the heat exchange pipe to maintain the temperature of the working medium system in the absorber not exceeding 130°C and to heat the temperature of the steam water source to 105°C to 120°C. At this time, the working medium has completed the heat transfer, transferring the heat of the pyrolysis gas system to the steam water source. The dilute lithium bromide aqueous solution is pumped out by the medium pump 2-04 and sent to the high-temperature condenser 1-01 to start a new heat exchange cycle. The steam water source enters the steam flash tank 2-06.

[0111] Because the steam flash tank 2-06 is pressurized, the superheated steam water source is stored in a liquid state. When in use, opening the steam exhaust valve will flash out saturated steam (0.1-0.25MPa) for use by the heat-consuming department. It is best to recover the steam after use and use it as a steam water source to regenerate steam.

[0112] This invention relates to a method for recovering and utilizing waste heat from pyrolysis gas;

[0113] This invention utilizes the principle of absorption heat pump to recover heat from pyrolysis gas and generate saturated steam for use in other processes or departments.

[0114] This invention condenses pyrolysis gas at different temperature ranges to obtain oils with different boiling points.

[0115] The working medium used in this invention is not limited to lithium bromide aqueous solution;

[0116] The steam generated by this invention can be converted into condensate and recycled after use;

[0117] All media pumps in this invention are shielded pumps to prevent outside air from entering the working medium system and corroding the device;

[0118] The device of this invention can replace the condensation device of existing pyrolysis equipment.

[0119] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto.

[0120] Therefore, any person skilled in the art, within the scope of the technology disclosed in this invention, can easily conceive of various variations or substitutions, all of which should be included within the protection scope of this invention. Thus, the protection scope of this invention should be determined by the scope of the stated claims.

Claims

1. A method for heat recovery in a pyrolysis rotary furnace, characterized in that, include: Pyrolysis gas flow condensation: High-temperature pyrolysis gas flows out of the pyrolysis furnace, is removed from the slag, and enters the high-temperature condenser. It is cooled by a dilute working medium, and the high-boiling-point pyrolysis oil components are condensed out, collected, and discharged into a high-boiling-point oil tank for storage. At the same time, medium-temperature pyrolysis gas is obtained. The medium-temperature pyrolysis gas enters the medium-temperature condenser for condensation. The medium-boiling-point oil components in the cooled pyrolysis gas are condensed out, collected, and discharged into the medium-boiling-point oil tank for storage, while low-temperature pyrolysis gas is obtained at the same time. Low-temperature pyrolysis gas is introduced into a low-temperature condenser, where it is finally cooled once by low-temperature water. The low-boiling-point oil components in the pyrolysis gas are condensed out, collected, and discharged into a low-boiling-point oil tank for storage, while non-condensable gas is obtained at the same time. Working medium circulation: The desalted working medium absorbs the heat of the high-temperature pyrolysis gas in the high-temperature condenser, evaporates water vapor and becomes concentrated working medium, and is discharged from the bottom of the condenser and returned to the medium absorber. During this process, it passes through the concentrated and desalted liquid heat exchanger to transfer its own heat to the desalted working medium going to the high-temperature condenser. The evaporated water vapor is discharged from the top of the condenser and enters the medium cooler. It is cooled to high temperature condensate by the steam water source and then enters the medium storage tank. The steam water source absorbs heat and then enters the medium absorber. The condensate in the medium storage tank enters the medium-temperature condenser through the medium pump and pipeline, is heated by the high-temperature pyrolysis gas, and then enters the medium absorber. Condensate is mixed and dissolved with the concentrated working medium in the medium absorber and high-temperature condenser to form a desalted working medium, releasing heat at the same time. The heat generated is carried away by the steam water source in the heat exchange pipeline, and the temperature of the steam water source is heated. The heat of the thermodynamic pyrolysis gas system is transferred to the steam water source. The desalted working medium is pumped out by the medium pump and sent to the high-temperature condenser to start a new heat exchange cycle. The steam water source enters the steam flash tank.

2. The heat recovery method for a pyrolysis rotary furnace according to claim 1, characterized in that: The non-condensable gas is a combustible gas.

3. The heat recovery method for a pyrolysis rotary furnace according to claim 2, characterized in that: The non-condensable gas, after passing through a non-condensable gas water seal, enters the combustible gas collection section or is returned to the pyrolysis furnace as fuel gas.

4. The heat recovery method for a pyrolysis rotary furnace according to claim 1, characterized in that: The working medium is an aqueous solution of lithium bromide.

5. The heat recovery method for a pyrolysis rotary furnace according to claim 1, characterized in that: The steam flash tank stores superheated steam water in liquid form. When in use, the exhaust valve is opened to flash saturated steam for use by the heating department. After use, the steam is recovered and used as steam water to generate steam again.

6. A heat recovery device for a pyrolysis rotary furnace, characterized in that, It includes a pyrolysis gas flow and condensation section and a working medium circulation section; The pyrolysis gas flow condensation section includes a condensation section and a storage section; in: The condensation section is used to condense the pyrolysis gas; The storage unit is used to store the pyrolysis oil obtained after condensing the pyrolysis gas. The working medium circulation section is used to complete condensation and heat release by using the working medium in conjunction with the condensation section; The working medium circulation unit includes: Medium cooler: Used to cool the high-temperature steam discharged from the high-temperature condenser into high-temperature condensate through an external steam water source and then discharge it into the medium storage tank. At the same time, the steam water source that has absorbed heat is discharged into the medium absorber. Medium storage tank: Used to store the working medium condensed by the medium cooler; Concentrated-dilute heat exchanger: used for heat exchange between the dilute working medium solution going to the high-temperature condenser and the concentrated working medium solution returning to the medium absorber; Medium pump: Used to pump the dilute working medium solution to the high-temperature condenser and to send the condensate in the medium storage tank to the medium-temperature condenser for heat exchange. Medium absorber: Used to absorb the condensate after heat exchange in the medium-temperature condenser and turn it into a dilute working medium solution, and release a large amount of heat to raise the temperature of the dilute working medium solution. Steam flash tank: Used to store superheated steam water source. When a steam point needs to use steam, the valve is opened to flash generate steam for the steam point to use.

7. The heat recovery device for a pyrolysis rotary furnace according to claim 6, characterized in that: The condensation section includes a high-temperature condenser, a medium-temperature condenser, a low-temperature condenser, and a non-condensable gas water seal connected in sequence.

8. The heat recovery device for a pyrolysis rotary furnace according to claim 7, characterized in that: The storage unit includes a high-boiling-point oil tank connected to a high-temperature condenser, a medium-boiling-point oil tank connected to a medium-temperature condenser, and a low-boiling-point oil tank connected to a low-temperature condenser.

9. The heat recovery device for a pyrolysis rotary furnace according to claim 6, characterized in that: The medium absorber is equipped with a closed heat exchange pipe, which allows the steam water source from the medium cooler to flow in the heat exchange pipe and be heated before entering the steam flash tank. At the same time, the concentrated working medium solution returning from the high-temperature condenser replenishes the dilute working medium solution discharged from the absorber.

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