Method for enhancing heat transfer and energy conservation of waste tire pyrolysis furnace

Abstract

The present invention discloses a method for enhancing heat transfer and saving energy in a waste tire pyrolysis furnace, which comprises the following steps: crushing waste tires into tire coarse rubber blocks with a diameter of 60-80 mm by a primary double-shaft shredder, and storing them in a storage hopper; adding waste steel wires accounting for 10-30% of the total weight of the tire coarse rubber blocks to the storage hopper; feeding the tire coarse rubber blocks mixed with waste steel wires into a pyrolysis furnace to carry out an atmospheric pressure low-temperature cracking reaction to generate oil gas and solid products. By adopting this method, the treatment cost can be greatly reduced without affecting the pyrolysis process.

Description

Technical Field

[0001] The present invention relates to a method for continuous thermal cracking of waste tires, and specifically to a method for enhancing heat transfer and energy conservation in a waste tire pyrolysis furnace. Background Art

[0002] Traditional methods for treating waste tires include: producing rubber powder, reclaiming rubber, and retreading, etc. Due to the defects of their process equipment and the limitations of their products, they are restricted by the market.

[0003] The continuous thermal cracking process of waste tires mainly includes: tire recycling and pretreatment - removing steel wires from waste tires by crushing - cracking of waste tires - deep processing of carbon black - purification of oil products, etc. Among them, waste tires enter the first-stage double-shaft shredder through a first-stage metal conveyor belt and are cut into coarse rubber blocks with a width of 60 - 80 mm. The process of removing steel wires from waste tires by crushing requires secondary crushing and magnetic separation screening. Rubber blocks with an outer dimension > 80 mm are returned to the second-stage double-shaft shredder by a rubber conveyor belt and are crushed again into fine rubber blocks with a size of 50 - 60 mm, which are stored in a storage hopper and conveyed into the pyrolysis furnace through a rubber conveyor belt, and most of the steel wires are separated out. Since the existing process requires crushing the tires into smaller particle sizes and separating out the steel wires as much as possible, tire crushing is the most power-consuming link in the entire thermal cracking process, accounting for about 40% of the total power consumption; the main energy consumption in the thermal cracking link is pyrolysis gas. Due to the small thermal conductivity of waste tires and poor heat transfer performance with the inner wall of the pyrolysis furnace, the thermal cracking speed is slow and the energy consumption is high. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for enhancing heat transfer and energy conservation in a waste tire pyrolysis furnace that is safe and can significantly improve the heat transfer efficiency and thermal cracking speed, and reduce the consumption of pyrolysis gas.

[0005] A method for enhancing heat transfer and energy conservation in a waste tire pyrolysis furnace of the present invention includes the following steps:

[0006] Step 1: Perform primary crushing on waste tires. The specific process is: After crushing waste tires into tire coarse rubber blocks with a diameter of 60 - 80 mm through a first-stage double-shaft shredder, store them in a storage hopper;

[0007] Step 2: Add waste steel wires accounting for 10 - 30% of the total weight of the tire coarse rubber blocks to the storage hopper;

[0008] Step 3: Feed the tire coarse rubber blocks mixed with waste steel wires into the pyrolysis furnace and carry out an atmospheric pressure low-temperature cracking reaction to generate oil gas and solid products; among them:

[0009] After the pyrolysis oil gas is fractionated and cooled by an oil separator, fuel oil and combustible gas are obtained;

[0010] The solid product obtained after pyrolysis is separated by magnetic separation to obtain crude carbon black and waste steel wires;

[0011] The flue gas generated by the production line is passed through a flue gas purification system to remove the organic compounds and solid particles therein, and after the emission index reaches the set standard, it is discharged up to the standard.

[0012] The beneficial effects of the present invention are as follows:

[0013] 1) By optimizing the waste tire crushing process, without affecting the normal pyrolysis function, the second-stage double-shaft shredder and the return rubber conveyor belt for the coarse rubber blocks are removed. In this way, the crushing link of the waste tire is reduced from two stages to one stage. And the power consumption of the crushing link accounts for the highest proportion, about 40% of the total power consumption. Through this optimization method, the power consumption of the crushing process can be reduced by about 50%, and the total power consumption of the continuous pyrolysis process of waste tires can be reduced by 20%, and the subsequent pyrolysis process is not affected.

[0014] 2) Compared with the existing pyrolysis process, after removing the second-stage double-shaft shredder, the size of the tire rubber blocks will increase, and the length and weight of the remaining steel wires will also increase. In addition, in order to strengthen the heat transfer performance between the heated material in the pyrolysis furnace and the inner wall of the pyrolysis furnace, waste steel wires accounting for about 10-30% of the total weight of the waste tires are additionally added to the storage hopper as required, so that the number of steel wires in the pyrolysis furnace is greatly increased. Since the thermal conductivity of the steel wire is much better than that of the waste tire, the heat can be quickly transferred to the waste tire rubber blocks through the collision of the steel wire with the inner wall of the pyrolysis furnace, which can significantly improve the heat transfer efficiency and pyrolysis speed, and reduce the consumption of pyrolysis gas, solving the problems of poor heat transfer performance and low pyrolysis efficiency of waste tires, and achieving the purpose of improving the pyrolysis yield and saving energy. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

[0016] Figure 1 is the process flow chart of the existing continuous pyrolysis system for waste tires;

[0017] Figure 2 is the schematic diagram of the existing waste tire pyrolysis furnace and the distribution of materials in the furnace;

[0018] Figure 3 is the process flow chart of a method for enhancing heat transfer and saving energy in a waste tire pyrolysis furnace of the present invention;

[0019] Figure 4 Schematic diagram of the waste tire pyrolysis furnace and the distribution of materials in the furnace after the improved process. DETAILED DESCRIPTION

[0020] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the technical solution of the present disclosure, but the technical solution of the present disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only part of the embodiments of the technical solution of the present disclosure, rather than all of the embodiments.

[0022] As shown in the accompanying drawings, a method for enhancing heat transfer and energy saving in a waste tire pyrolysis furnace of the present invention comprises the following steps:

[0023] Step 1: The waste tires are crushed in the first stage. The specific process is as follows: the waste tires are crushed into tire coarse rubber blocks with a diameter of 60-80mm by a first-stage double-shaft shredder and directly stored in the storage hopper;

[0024] The diameter of the tire rough rubber block can be 60-65mm, 65mm-70mm, 70mm-80mm, etc.

[0025] Step 2: according to the need of enhancing heat transfer, adding waste steel wire with a weight accounting for 10-30% of the total weight of the tire rough rubber block into the storage hopper;

[0026] Step 3: feeding the tire rubber block mixed with waste steel wire into a thermal cracking furnace to undergo a normal pressure and low temperature cracking reaction to generate oil gas and solid products; wherein:

[0027] After the cracked oil and gas are fractionated and cooled in the oil separator, fuel oil and combustible gas are obtained. The combustible gas is preferably returned to the thermal cracking furnace after purification. The combustible gas is purified by the purification system and used as fuel for the heating system, which greatly saves energy consumption and reduces equipment operating costs.

[0028] The solid products obtained after cracking include crude carbon black and scrap steel wire. After magnetic separation, the crude carbon black is automatically transported to the existing carbon black production system, and then through a series of processing steps such as crushing to obtain industrial carbon black or other high value-added chemical products. The separated scrap steel wire is treated as scrap steel.

[0029] The flue gas generated by the production line can be purified by the flue gas purification system to remove organic compounds such as SOx and NOx and solid particles, so that the emission indicators meet the standards of Europe, the United States and other countries.

[0030] The pressure of the pyrolysis furnace can usually be set to normal pressure, the temperature at the feed end of the pyrolysis furnace can be set to 180°C, and the temperature at the discharge end can be set to 450°C.

[0031] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific functions and working processes. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A method for enhancing heat transfer and energy saving in a waste tire pyrolysis furnace, characterized in that The following steps are involved: Step 1: The waste tires are crushed in the first stage. The specific process is as follows: the waste tires are crushed into tire coarse rubber blocks with a diameter of 60-80mm by a first-stage double-shaft shredder and then directly stored in the storage hopper; Step 2: Adding waste steel wire with a weight of 10-30% of the total weight of the tire rough rubber block into the storage hopper to enhance the heat transfer performance between the heated material in the pyrolysis furnace and the inner wall of the pyrolysis furnace; Step 3: The tire rubber block mixed with waste steel wire is fed into a pyrolysis furnace, and the heat is quickly transferred to the waste tire rubber block through the collision between the steel wire and the inner wall of the pyrolysis furnace, and a normal pressure and low temperature pyrolysis cracking reaction is performed to generate oil gas and solid products; wherein: After the cracked oil and gas are fractionated and cooled in an oil separator, fuel oil and combustible gas are obtained; The solid product obtained after cracking is separated by magnetic separation to obtain crude carbon black and waste steel wire; The flue gas generated by the production line is removed of organic compounds and solid particles through the flue gas purification system, so that the emission indicators meet the set standards and then meet the emission standards.

2. The method for enhancing heat transfer and energy saving in a waste tire pyrolysis furnace according to claim 1, characterized in that: The temperature at the feed end of the thermal cracking furnace for low-temperature cracking reaction is set at 180°C, and the temperature at the discharge end is set at 450°C.

3. The method for enhancing heat transfer and energy saving in a waste tire pyrolysis furnace according to claim 1 or 2, characterized in that: The combustible gas is purified and sent back to the thermal cracking furnace.

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