A high-temperature garbage pyrolysis oil and gas water washing purification system and method

Abstract

This invention belongs to the technical field of solid waste pyrolysis and its energy-based applications, specifically relating to a water-washing purification system and method for high-temperature garbage pyrolysis oil and gas. This invention provides a system and method for purifying garbage pyrolysis oil and gas. These systems separate fly ash, tar, and acidic substances such as HCl and H2S from the garbage pyrolysis oil and gas, producing clean pyrolysis gas. This improves the calorific value of the pyrolysis gas, reduces corrosion of tar and acidic substances on pipelines and equipment, and ensures the stability and safety of system operation. Furthermore, through rapid cooling and removal of Cl ions, the formation of dioxins is eliminated.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste pyrolysis and its energy application, and specifically relates to a high-temperature garbage pyrolysis oil and gas water washing purification system and method. Background Art

[0002] As China's urbanization accelerates, the rate of household waste generation is also increasing. Many cities around the world are now surrounded by garbage, and domestic waste was once considered a burden on urban development. However, with a deeper understanding of waste, it is now being recognized as an inexhaustible "urban mineral resource" with the greatest potential for development, a "misplaced resource."

[0003] Countries around the world are pursuing resource utilization for domestic waste. Currently, commonly used waste treatment methods include incineration, sanitary landfill, composting, and comprehensive utilization. Each method has its own scope of application, advantages, and disadvantages. In my country, where waste management is just beginning in most cities, sanitary landfill has become the primary treatment method in these initial stages due to its mature technology, low operating investment, and ease of management and maintenance. However, landfills occupy significant land, posing a threat to surrounding crops and water sources. Incineration-based power generation, on the other hand, presents challenges such as low safe disposal rates for fly ash, which is enriched with heavy metals and dioxins, and greenhouse gas emissions. Pyrolysis technology is an effective way to harmlessly treat waste, protecting the environment, saving energy, and innovating energy utilization. This method eliminates the production of dioxins, and the resulting pyrolysis oil, pyrolysis gas, and pyrolysis carbon residue can all be used as fuel. The pyrolysis oil can also be further separated and purified to yield additional chemical raw materials.

[0004] During the pyrolysis process of municipal solid waste, the pyrolysis products are complex, including three-phase substances: gas, solid, and liquid, such as pyrolysis tar, pyrolysis gas, and pyrolysis carbon. Due to the high temperature at the end of the pyrolysis reactor, both pyrolysis tar and pyrolysis gas are discharged in a gaseous form. Due to the complex composition of the waste, the pyrolysis gas differs from that of biomass pyrolysis gas, containing acidic substances such as HCl and H2S. In existing waste pyrolysis processes, the pyrolysis gas is typically burned directly, or the tar is removed similarly to biomass pyrolysis gas, and then fed into an incinerator for combustion as fuel. However, the acidic substances present in the pyrolysis gas can corrode system piping and equipment, reducing their service life and significantly impacting the stable and safe operation of the system. Furthermore, the presence of Cl ions creates conditions for the secondary formation of dioxins. Therefore, during the waste pyrolysis process, the pyrolysis gas requires purification, such as de-coking and de-acidification, to reduce the corrosion and operational safety risks caused by acidic substances and tar on equipment and piping. Furthermore, the de-acidification process removes Cl ions, eliminating the potential for dioxin formation. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of clogging and corrosion of equipment by acidic substances in the existing garbage pyrolysis gas process, which is direct combustion or combustion after oil removal, and to eliminate the possibility of secondary generation of dioxins due to the presence of Cl ions.

[0006] The present invention provides a high-temperature garbage pyrolysis oil and gas water-washing purification system and method. This system separates fly ash, tar, and acidic substances such as HCl and H2S from the garbage pyrolysis oil and gas to produce clean pyrolysis gas, increasing the calorific value of the pyrolysis gas and reducing corrosion of tar and acidic substances on pipelines and equipment, thereby ensuring the stability and safety of system operation. Furthermore, through rapid cooling and removal of Cl ions, the possibility of dioxin formation is eliminated.

[0007] The technical solutions of the present invention are as follows:

[0008] A high-temperature garbage pyrolysis oil and gas water washing purification system, including a tar recovery system and a deacidification system;

[0009] The tar recovery system includes a cyclone dust collector, a quenching tower, a heat exchanger, a tar separation tank, a three-phase centrifuge, an electric tar collector and a tar storage tank;

[0010] The left end of the cyclone dust collector is connected to the pyrolysis reactor, the upper end is connected to the upper end of the quenching tower, the lower end of the quenching tower is connected to the upper part of the tar separation tank, the middle right side of the tar separation tank is connected to the upper end of the heat exchanger, and the lower end of the heat exchanger is connected to the upper end of the quenching tower; the right bottom of the tar separation tank is connected to the left end of the three-phase centrifuge, and the right end of the three-phase centrifuge is connected to the tar storage tank;

[0011] The deacidification system includes a water scrubber, a desulfurization tower and an alkali scrubber; wherein the bottom of the quenching tower is connected to the bottom of the water scrubber, the top of the water scrubber is connected to the bottom of the electric precipitator, the upper part of the electric precipitator is connected to the lower part of the desulfurization tower, and the upper part of the desulfurization tower is connected to the lower part of the alkali scrubber; the bottom of the electric precipitator is connected to the tar storage tank; the top of the alkali scrubber is the outlet for purified pyrolysis gas, which can be connected to a pyrolysis gas user or a gas storage device.

[0012] In the high-temperature garbage pyrolysis oil and gas water washing purification system as described above, the quenching tower, tar separation tank and heat exchanger form a spray cycle.

[0013] In the high-temperature garbage pyrolysis oil and gas water washing purification system as described above, the water washing tower and the alkali washing tower are generally structured in the form of a packed tower or an empty tower.

[0014] In the high-temperature garbage pyrolysis oil and gas water washing purification system as described above, the upper ends of the water washing tower and the alkali washing tower are both provided with wire mesh demister devices.

[0015] In the above-mentioned high-temperature garbage pyrolysis oil and gas water washing purification system, the desulfurization tower is filled with a desulfurizer.

[0016] As described above, in a high-temperature garbage pyrolysis oil and gas water washing purification system, the tar separation tank is divided into four cavities by a baffle, and the baffle is tightly connected to the tank body at the upper and lower parts, leaving a gap in the upper middle part.

[0017] In the above-described high-temperature garbage pyrolysis oil and gas water washing and purification system, the tar-containing quenching spray liquid enters the first cavity through the water inlet and overflows into the second cavity through the gap between the baffles. To prevent the liquid from short-circuiting, a baffle is provided in front of the baffle.

[0018] The second cavity is provided with an air flotation device for separating light oil;

[0019] In the first three cavities, a conical tar and heavy oil outlet is provided at the bottom;

[0020] There are light oil scrapers on the upper part of the baffle to collect the floating oil and then enter the external oil collection tank through the light oil outlet;

[0021] The spray liquid after tar separation is pumped out from the outlet and enters the circulation.

[0022] In the high-temperature garbage pyrolysis oil and gas water washing purification system as described above, the tar separation tank is provided with a temperature control device for heating the liquid in the tar separation tank to prevent the tar from solidifying due to low temperature.

[0023] The purification method based on the high-temperature garbage pyrolysis oil and gas water washing purification system as described above includes the following steps:

[0024] In step 1, the mixture of oil and gas from high-temperature garbage pyrolysis enters the cyclone dust collector, where more than 90% of the fly ash is separated;

[0025] In step 2, the pyrolysis oil and gas that has passed through the cyclone dust collector enters the quench tower for quench spray cooling. The pyrolysis oil and gas come into contact with the atomized quench liquid, which lowers the temperature and prevents the re-generation of dioxins. At the same time, the tar and some fly ash in the pyrolysis oil and gas also enter the quench spray liquid.

[0026] The quenching spray liquid containing fly ash and tar in the quenching tower enters the tar separation tank below, where the tar is separated from the spray liquid through sedimentation and flotation in three cavities.

[0027] Step 3: collecting the tar separated in step 2, and separating the tar, water, and tar residue through a three-phase centrifuge, wherein the tar is transported to a tar storage tank;

[0028] Step 4: After rapid cooling and decoking, the pyrolysis gas enters a water scrubber for further decoking and removal of some acidic substances in the pyrolysis gas;

[0029] Step 5: After water washing, the pyrolysis gas enters the electric tar collector to capture the tar droplets remaining in the pyrolysis oil and gas. The tar collected at the bottom of the electric tar collector is transported to the tar storage tank.

[0030] Step 6: After the pyrolysis gas passes through the electrostatic precipitator, it enters the desulfurization tower to remove sulfur-containing gases such as H2S;

[0031] Step seven: In order to ensure that the acidic gas in the pyrolysis gas is completely removed, the pyrolysis gas passes through the desulfurization tower and then enters the alkali washing tower. The pyrolysis gas after alkali washing can be stored in the gas cabinet or directly connected to the user for use.

[0032] The remarkable effects of the present invention are:

[0033] 90% of the fly ash is separated by the cyclone dust collector; in the quenching tower, the pyrolysis oil and gas are rapidly cooled, eliminating the possibility of dioxin synthesis in the low-temperature section. At the same time, tar and fly ash are also separated from the pyrolysis gas by the spray liquid.

[0034] The spray liquid enters the tar separation tank, where heavy oil and light oil are separated. After the three-phase separation of heavy oil and light oil, the tar is stored in the storage tank. The tar droplets remaining in the pyrolysis gas are collected by the subsequent electric tar collector to achieve tar recovery.

[0035] After rapid cooling, the pyrolysis gas is washed with water, desulfurized and then washed with alkali to remove HCl and H2S gases. After passing through the gas-liquid separation tank, the purified pyrolysis gas is stored in a gas cabinet.

[0036] The entire system realizes the separation of tar from pyrolysis gas and tar recovery. Through rapid cooling and Cl removal measures, the process of dioxin generation in the low-temperature section of pyrolysis gas is eliminated. In addition, the deacidification and desulfurization processes reduce the corrosion of pyrolysis gas to equipment, improve the purity of pyrolysis gas, increase the calorific value of pyrolysis gas, and reduce equipment investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a structural schematic diagram of a high-temperature domestic waste pyrolysis oil and gas purification system according to the present invention;

[0038] Figure 2 This is a schematic diagram of the internal structure of the tar separation tank in the high-temperature domestic waste pyrolysis oil and gas purification system described in the present invention.

[0039] In the figure: 1-cyclone dust collector; 2-quenching tower; 3-heat exchanger; 4-water scrubber; 5-electrostatic precipitator; 6-desulfurization tower; 7-alkali scrubber; 8-tar separation tank; 9-three-phase centrifuge; 10-tar storage tank; 8-1-spray liquid inlet; 8-2-light oil scraper; 8-3-light oil outlet; 8-4-baffle; 8-5-deflector; 8-6-temperature control device; 8-7-flotation device; 8-8-tar and heavy oil outlet; 8-9-spray liquid outlet. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 As shown, the present invention provides a high-temperature garbage pyrolysis oil and gas water washing purification system, which includes two parts: a tar recovery system and a deacidification system;

[0042] The tar recovery system includes a cyclone dust collector 1, a quenching tower 2, a heat exchanger 3, a tar separation tank 8, a three-phase centrifuge 9, an electric tar collector 5 and a tar storage tank 10;

[0043] The left end of the cyclone dust collector 1 is connected to the pyrolysis reactor, and the upper end is connected to the upper end of the quenching tower 2. The lower end of the quenching tower 2 is connected to the upper part of the tar separation tank 8. The middle part of the right side of the tar separation tank 8 is connected to the upper end of the heat exchanger 3, and the lower end of the heat exchanger 3 is connected to the upper end of the quenching tower 2. The right bottom of the tar separation tank 8 is connected to the left end of the three-phase centrifuge 9, and the right end of the three-phase centrifuge 9 is connected to the tar storage tank 10.

[0044] The deacidification system includes a water washing tower 4, a desulfurization tower 6 and an alkali washing tower 7; wherein, the bottom of the quenching tower 2 is connected to the bottom of the water washing tower 4, the top of the water washing tower 4 is connected to the bottom of the electric tar collector 5, the upper part of the electric tar collector 5 is connected to the lower part of the desulfurization tower 6, and the upper part of the desulfurization tower 6 is connected to the lower part of the alkali washing tower 7; the bottom of the electric tar collector 5 is connected to the tar storage tank 10; the top of the alkali washing tower 7 is the outlet for purified pyrolysis gas, which can be connected to a pyrolysis gas user or a gas storage device.

[0045] In this embodiment, the quenching tower 2, the tar separation tank 8 and the heat exchanger 3 form a spray cycle;

[0046] The structure of the water washing tower 4 and the alkali washing tower 7 is generally a packed tower or an empty tower;

[0047] The upper ends of the water washing tower 4 and the alkali washing tower 7 are both equipped with a wire mesh demister device;

[0048] The desulfurization tower 6 is filled with a desulfurizer;

[0049] like Figure 2The tar separation tank 8 is divided into four cavities by the baffle 8-4. The baffle 8-4 is tightly connected to the tank body at the top and bottom, leaving a gap in the middle and upper part.

[0050] The tar-containing quenching spray liquid enters the first cavity through the water inlet 8-1 and overflows into the second cavity through the gap in the middle of the baffle 8-4. In order to prevent the liquid from short-circuiting, a baffle 8-5 is set in front of the baffle 8-4.

[0051] In the second cavity, an air flotation device 8-7 is provided for separating light oil;

[0052] In the first three cavities, a conical tar and heavy oil outlet 8-8 is provided at the bottom;

[0053] There are light oil scrapers 8-2 on the upper part of the baffle 8-5 to collect the floating oil and then enter the external oil collection tank through the light oil outlet 8-3;

[0054] After the tar is separated, the spray liquid is pumped out from the outlet 8-9 and enters the circulation;

[0055] The tar separation tank 8 is provided with a temperature control device 8-6 for heating the liquid in the tar separation tank 8 to prevent the tar from solidifying due to low temperature.

[0056] A method for purifying garbage pyrolysis oil and gas in the system described above comprises the following steps:

[0057] In step 1, the mixture of high-temperature garbage pyrolysis oil and gas enters the cyclone dust collector 1, and more than 90% of the fly ash is separated;

[0058] Step 2: The pyrolysis oil and gas after passing through the cyclone dust collector 1 enters the quench tower 2 for quenching spray cooling. The pyrolysis oil and gas come into contact with the atomized quench liquid, which lowers the temperature and prevents the re-generation of dioxins. At the same time, the tar and some fly ash in the pyrolysis oil and gas also enter the quench spray liquid.

[0059] The quenching spray liquid containing fly ash and tar in the quenching tower 2 enters the tar separation tank 8 below, where the tar is separated from the spray liquid through sedimentation and flotation in three cavities.

[0060] Step 3: collecting the tar separated in step 2 and separating the tar, water and tar residue through a three-phase centrifuge 9, wherein the tar is transported to a tar storage tank 10;

[0061] Step 4: The pyrolysis gas after rapid cooling and decoking enters the water scrubber 4 for further decoking and removal of some acidic substances in the pyrolysis gas;

[0062] Step 5: The pyrolysis gas after water washing enters the electric tar collector 5 to capture the tar droplets remaining in the pyrolysis oil and gas. The tar collected at the bottom of the electric tar collector 5 is transported to the tar storage tank 10;

[0063] Step 6: After the pyrolysis gas passes through the electric tar collector 5, it enters the desulfurization tower 6 to remove sulfur-containing gases such as H2S;

[0064] Step seven: In order to ensure that the acid gas in the pyrolysis gas is completely removed, the pyrolysis gas passes through the desulfurization tower 6 and then enters the alkali washing tower 7. The pyrolysis gas after alkali washing can be stored in the gas cabinet or directly connected to the user for use.

[0065] Working Principle: The high-temperature pyrolysis oil and gas mixture discharged from the pyrolysis reactor enters the cyclone dust collector 1, where more than 90% of the fly ash is separated. The pyrolysis oil and gas then enter the quench tower 2 for rapid cooling, causing the temperature to drop rapidly, eliminating the possibility of dioxin regeneration. At the same time, tar and some fly ash are also sprayed down. The quench tower spray liquid enters the tar separation tank 8, where the tar heavy oil and light oil are separated through the dual effects of sedimentation and flotation. The separated tar is collected and separated into tar, water, and tar residue by a three-phase separator 9. The tar is transported to the tar storage tank 10. The tar recovery system also includes an electric precipitator 5. The pyrolysis gas passing through the water scrubber 4 enters the electric precipitator 5 to replenish the tar droplets remaining in the pyrolysis gas. The tar collected at the bottom is also transported to the tar storage tank 10.

[0066] After rapid cooling, the pyrolysis gas enters the water washing tower 4 from the bottom, and spray water is sprayed from the top of the tower to further cool the pyrolysis gas. During the water washing process, most of the HCl gas in the pyrolysis gas is absorbed by water, and the pyrolysis gas is preliminarily deacidified. The pyrolysis gas then enters the electric precipitator 5 and then enters the desulfurization tower 6 for pyrolysis gas desulfurization. H2S gas is removed in the desulfurization tower. The pyrolysis gas coming out of the top of the desulfurization tower 6 enters the bottom of the alkali washing tower 7. The gas and liquid phases are in reverse contact in the alkali washing tower 7. The alkaline spray liquid absorbs the residual acid gas in the pyrolysis gas. There is a wire mesh demister on the upper part of the alkali washing tower to intercept droplets in the air flow. The pyrolysis gas after alkali washing is stored in the gas cabinet.

Claims

1. A high-temperature garbage pyrolysis oil and gas water washing purification system, characterized by: It consists of two parts: tar recovery system and deacidification system; The tar recovery system comprises a cyclone dust collector (1), a quenching tower (2), a heat exchanger (3), a tar separation tank (8), a three-phase centrifuge (9), an electric tar collector (5) and a tar storage tank (10); The left end of the cyclone dust collector (1) is connected to the pyrolysis reactor, the upper end is connected to the upper end of the quenching tower (2), the lower end of the quenching tower (2) is connected to the upper part of the tar separation tank (8), the middle part of the right side of the tar separation tank (8) is connected to the upper end of the heat exchanger (3), and the lower end of the heat exchanger (3) is connected to the upper end of the quenching tower (2); the bottom of the right side of the tar separation tank (8) is connected to the left end of the three-phase centrifuge (9), and the right end of the three-phase centrifuge (9) is connected to the tar storage tank (10); The deacidification system comprises a water washing tower (4), a desulfurization tower (6) and an alkali washing tower (7); wherein the bottom of the quenching tower (2) is connected to the bottom of the water washing tower (4), the top of the water washing tower (4) is connected to the bottom of the electric tar collector (5), the upper part of the electric tar collector (5) is connected to the lower part of the desulfurization tower (6), and the upper part of the desulfurization tower (6) is connected to the lower part of the alkali washing tower (7); the bottom of the electric tar collector (5) is connected to the tar storage tank (10); the top of the alkali washing tower (7) is the outlet of the purified pyrolysis gas, which is connected to the pyrolysis gas user or the gas storage device; The tar separation tank (8) is internally divided into four cavities by a baffle (8-4), and the baffle (8-4) is tightly connected to the tank body at both the top and the bottom, with a gap left in the middle and upper parts. The tar-containing quenching spray liquid enters the first cavity through the water inlet (8-1) and overflows into the second cavity through the gap in the middle of the baffle (8-4); in order to prevent the liquid from forming a short circuit, a baffle (8-5) is provided in front of the baffle (8-4); An air flotation device (8-7) is provided in the second cavity for separating light oil; In the first three chambers, a conical tar heavy oil outlet (8-8) is provided at the bottom; There is a light oil scraper (8-2) on the upper part of the baffle (8-4), and the light oil scraper (8-2) collects the floating oil and then enters the external oil collection tank through the light oil outlet (8-3); After the tar is separated, the spray liquid is pumped out from the outlet (8-9) and enters the circulation; The tar separation tank (8) is provided with a temperature control device (8-6) for heating the liquid in the tar separation tank (8) to prevent the tar from solidifying due to low temperature.

2. The high-temperature garbage pyrolysis oil and gas water washing purification system according to claim 1, characterized in that: The quenching tower (2), the tar separation tank (8) and the heat exchanger (3) form a spray cycle.

3. The high-temperature garbage pyrolysis oil and gas water washing purification system according to claim 1, characterized in that: The water washing tower (4) and the alkali washing tower (7) are structurally either a packed tower or an empty tower.

4. The high-temperature garbage pyrolysis oil and gas water washing purification system according to claim 1, characterized in that: The upper ends of the water washing tower (4) and the alkali washing tower (7) are both provided with a wire mesh demister device.

5. The high-temperature garbage pyrolysis oil and gas water washing purification system according to claim 1, characterized in that: The desulfurization tower (6) is filled with a desulfurizer.

6. The high-temperature garbage pyrolysis oil and gas water washing purification system according to claim 1, characterized in that: The quenching tower (2), the tar separation tank (8) and the heat exchanger (3) form a spray cycle; The water washing tower (4) and the alkali washing tower (7) are structurally either a packed tower or an empty tower; The upper ends of the water washing tower (4) and the alkali washing tower (7) are both provided with a wire mesh demister device; The desulfurization tower (6) is filled with a desulfurizer; The inside of the tar separation tank (8) is divided into four cavities by a baffle (8-4), and the baffle (8-4) is tightly connected to the tank body at the top and bottom, with a gap left at the middle and upper part; The tar-containing quenching spray liquid enters the first cavity through the water inlet (8-1) and overflows into the second cavity through the gap in the middle of the baffle (8-4); in order to prevent the liquid from forming a short circuit, a baffle (8-5) is provided in front of the baffle (8-4); An air flotation device (8-7) is provided in the second cavity for separating light oil; In the first three chambers, a conical tar heavy oil outlet (8-8) is provided at the bottom; There is a light oil scraper (8-2) on the upper part of the baffle (8-4), and the light oil scraper (8-2) collects the floating oil and then enters the external oil collection tank through the light oil outlet (8-3); After the tar is separated, the spray liquid is pumped out from the outlet (8-9) and enters the circulation; The tar separation tank (8) is provided with a temperature control device (8-6) for heating the liquid in the tar separation tank (8) to prevent the tar from solidifying due to low temperature.

7. A high-temperature garbage pyrolysis oil and gas water washing purification method, characterized in that: The high-temperature garbage pyrolysis oil and gas water washing purification system according to any one of claims 1 to 6 comprises the following steps: In step 1, the mixture of high-temperature garbage pyrolysis oil and gas enters the cyclone dust collector (1), and more than 90% of the fly ash is separated; Step 2: The pyrolysis oil and gas passing through the cyclone dust collector (1) enters the quenching tower (2) for quenching spray cooling. The pyrolysis oil and gas come into contact with the atomized quenching liquid, and the temperature drops, thereby preventing the regeneration of dioxins. At the same time, the tar and part of the fly ash in the pyrolysis oil and gas also enter the quenching spray liquid. The quenching spray liquid containing fly ash and tar in the quenching tower (2) enters the tar separation tank (8) below, and the tar is separated from the spray liquid through sedimentation and flotation in three cavities in the tar separation tank (8); Step 3: collecting the tar separated in step 2, and separating the tar, water, and tar residue through a three-phase centrifuge (9), wherein the tar is transported to a tar storage tank (10); Step 4: The pyrolysis gas after rapid cooling and decoking enters the water scrubber (4) for further decoking and removal of some acidic substances in the pyrolysis gas; Step 5: The pyrolysis gas after water washing enters the electric tar collector (5) to capture the tar droplets remaining in the pyrolysis oil gas, and the tar collected at the bottom of the electric tar collector (5) is transported to the tar storage tank (10); Step 6: After the pyrolysis gas passes through the electric tar collector (5), it enters the desulfurization tower (6) to remove the H2S sulfur gas therein; Step seven: To ensure that the acidic gas in the pyrolysis gas is completely removed, the pyrolysis gas passes through the desulfurization tower (6) and then enters the alkali washing tower (7). The pyrolysis gas after alkali washing can be stored in a gas cabinet or directly connected to the user for use.

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