Bypass assisted energy saving fly ash pyrolysis system

Abstract

The utility model relates to garbage incineration technical field discloses a kind of bypass auxiliary energy-saving fly ash pyrolysis system, including garbage incinerator, pyrolysis furnace, pyrolysis furnace gas outlet is connected with the incineration hearth of garbage incinerator, fly ash from garbage incinerator is pyrolyzed by pyrolysis furnace, to absorb the flue gas heat gas of garbage incinerator as the heating medium of pyrolysis furnace. The secondary air in the secondary air bypass that shunts into is heat exchanged using the flue gas of garbage incinerator, and it carries out heating to fly ash pyrolysis furnace, greatly improves heat utilization efficiency, improves the heat utilization efficiency of garbage incineration and fly ash pyrolysis by relatively simple system structure setting, saves cost.

Description

Technical Field

[0001] This utility model relates to the field of waste incineration technology, specifically to a fly ash pyrolysis system that utilizes bypass assistance for energy saving. Background Technology

[0002] Waste incineration technology has become one of the main methods for treating municipal solid waste. However, the fly ash produced during incineration contains a large amount of heavy metals and dioxins, which, if not properly handled, will pose a serious threat to the environment and human health. Low-temperature pyrolysis technology for waste incineration fly ash is an emerging technology for the harmless treatment and resource utilization of fly ash produced during waste incineration. By pyrolyzing the fly ash at a certain temperature (usually 350℃~500℃), it can effectively decompose dioxin-like organic pollutants in the fly ash, while stabilizing heavy metals and reducing their leaching toxicity, thus contributing to the harmless treatment and resource utilization of waste incineration fly ash. Existing waste incineration fly ash pyrolysis technologies have the following technical problems: 1. Waste incineration fly ash pyrolysis projects typically operate using electric heating and centralized processing, resulting in high operating costs; 2. The pyrolysis gas produced still contains small amounts of dioxins and heavy metals, making treatment difficult; 3. If high-temperature flue gas or steam is used directly as the pyrolysis heat source, the operating parameters are difficult to control.

[0003] The existing technology, patent application number CN202411380289.4, entitled "A Method and System for Pyrolysis of Dioxins in Waste Incineration Fly Ash," employs a method of preheating fly ash with power plant flue gas and utilizing energy in stages, thereby improving energy efficiency and simultaneously achieving the pyrolysis treatment of dioxins in fly ash within the waste incineration plant. While this technical solution utilizes power plant flue gas to preheat the incineration fly ash, the pyrolysis of the fly ash uses an electromagnetic heating system. Although this ensures energy utilization, it still suffers from high system operating costs and relatively complex procedures. Utility Model Content

[0004] To address the technical problems of high operating costs and complex procedures in existing waste incineration fly ash treatment systems, this invention proposes a bypass-assisted energy-saving fly ash pyrolysis system.

[0005] The bypass-assisted energy-saving fly ash pyrolysis system includes a waste incinerator and a pyrolysis furnace. The pyrolysis gas outlet of the pyrolysis furnace is connected to the incineration furnace of the waste incinerator. The fly ash from the waste incinerator is pyrolyzed by the pyrolysis furnace, and the gas that absorbs the heat of the flue gas from the waste incinerator is used as the heating medium of the pyrolysis furnace.

[0006] The aforementioned bypass-assisted energy-saving fly ash pyrolysis system uses secondary air from the incinerator as the heating medium. It also includes a secondary air fan, a main secondary air path, and a secondary air bypass equipped with a gas-to-gas heat exchanger. The main secondary air path includes a secondary air damper and a warm air fan connected in sequence. The secondary air fan is directly connected to the incineration furnace of the waste incinerator through the main secondary air path. The secondary air fan is connected to the air inlet of the outer shell layer of the pyrolysis furnace through the secondary air bypass. The air outlet of the outer shell layer of the pyrolysis furnace is connected to the incineration furnace of the waste incinerator. The flue gas from the waste incinerator flows through the main flue gas path and exchanges heat with the gas in the secondary air bypass through the gas-to-gas heat exchanger. The main flue gas path includes an induced draft fan. After heat exchange, the flue gas is driven back to the waste incinerator by the induced draft fan.

[0007] The aforementioned bypass-assisted energy-saving fly ash pyrolysis system also includes a high-temperature flue gas bypass. The high-temperature flue gas bypass is a branch flue gas duct set between the incinerator furnace and the gas-to-gas heat exchanger of the waste incinerator. The high-temperature flue gas bypass includes a flue gas cooler and a flue gas damper connected in sequence.

[0008] The above-mentioned bypass-assisted energy-saving fly ash pyrolysis system uses a partitioned water-cooled structure for the flue gas cooler.

[0009] The beneficial effects of this utility model include: by using the original secondary air fan of the power plant to provide a heat source medium for the pyrolysis system, the secondary air is heated through the main secondary air path and enters the waste incinerator. At the same time, the flue gas from the waste incinerator exchanges heat with the secondary air diverted into the secondary air bypass, and then heats the fly ash pyrolysis furnace, which greatly improves the heat utilization efficiency. The heat utilization efficiency of waste incineration and fly ash pyrolysis is improved through a relatively simple system structure, saving costs and solving the technical problems of high operating costs and complex procedures in the existing waste incineration fly ash treatment system. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the bypass-assisted energy-saving fly ash pyrolysis device of this utility model.

[0011] The markings in the diagram are: 1-Secondary air fan, 2-Gas-to-gas heat exchanger, 3-Pyrolysis furnace, 4-Incinerator, 5-Secondary air damper, 6-Warm air fan, 7-Induced draft fan, 8-Flue gas cooler, 9-Flue gas damper. Detailed Implementation

[0012] The present invention will now be described in conjunction with the accompanying drawings.

[0013] like Figure 1The diagram shows the bypass-assisted energy-saving fly ash pyrolysis system of this invention, which includes a waste incinerator 4 and a pyrolysis furnace 3. The pyrolysis furnace 3 is used to pyrolyze fly ash. The pyrolysis gas outlet of the pyrolysis furnace 3 is connected to the incineration furnace of the waste incinerator 4, so that the pyrolysis gas enters the waste incinerator 4 for further processing, deeply decomposes the organic pollutants in the pyrolysis gas, and uses the gas that absorbs the heat of the flue gas from the waste incinerator 4 as the heating medium of the pyrolysis furnace 3 to realize the recovery and utilization of heat energy.

[0014] Furthermore, the heating medium is the secondary air from the waste incinerator 4, and it also includes a secondary air fan 1, a main secondary air line, and a secondary air bypass line equipped with a gas-to-gas heat exchanger 2. In this embodiment, the secondary air fan 1 can utilize the existing equipment of the waste incineration power plant. It is necessary to verify the fan's pressure head and air volume. The main secondary air line includes a secondary air damper 5 and a warm air fan 6 connected in sequence. The secondary air fan 1 is directly connected to the incineration furnace of the waste incinerator 4 through the main secondary air line. The secondary air fan 1 is connected to the air inlet of the outer shell of the pyrolysis furnace 3 through the secondary air bypass line. The pipeline resistance is calculated in advance, and the secondary air fan 1 is controlled to pressurize the cold air to between a few kPa and a dozen kPa. The cold air from the main pipeline is heated to the specified temperature by the warm air fan 6 and then enters the waste incinerator 4. The air outlet of the outer shell of the pyrolysis furnace 3 is connected to the combustion chamber of the waste incinerator 4. The flue gas from the waste incinerator 4 flows through the main flue gas pipeline and exchanges heat with the gas in the secondary air bypass through the gas-to-gas heat exchanger 2. A portion of the cold air exchanges heat with the flue gas in the main flue gas pipeline through the secondary bypass and then heats the pyrolysis furnace 4 before entering the waste incinerator 4.

[0015] Furthermore, it also includes a high-temperature flue gas bypass, which is set as a branch flue of the main flue gas path between the incinerator furnace of the waste incinerator 4 and the gas-to-gas heat exchanger 2. It utilizes the physical characteristics of high-temperature flue gas for diversion treatment. The high-temperature flue gas bypass includes a flue gas cooler 8 and a flue gas damper 9 connected in sequence. The flue gas cooler 8 processes the high-temperature flue gas from the main flue gas path, and the flue gas damper 9 controls the flow rate of the bypass flue gas, thereby controlling the flue gas temperature of the main flue gas path. By controlling the flow rate of a portion of the high-temperature flue gas during the flue gas transfer process, the overall flue gas temperature is regulated.

[0016] Furthermore, in this embodiment, the flue gas cooler 8 adopts a partitioned water-cooled structure, which makes the heat load variable and the flue gas outlet temperature and flow rate more controllable.

[0017] In this embodiment, when put into use, the secondary air fan 1 first pressurizes the cold air to the required pressure. The secondary air damper 5 distributes the flow ratio of the cold air in the secondary air main path and the secondary air bypass. The cold air in the secondary air main path is heated by the warm air fan 6, while the cold air in the secondary air bypass exchanges heat with the flue gas in the flue gas main path in the gas-to-gas heat exchanger 2, thereby increasing its temperature. In the initial stage of system operation, when the flue gas temperature is low, the proportion of cold air entering the secondary air bypass is reduced by controlling the secondary air damper 5. After the flue gas temperature rises, the proportion of cold air entering the secondary air bypass is increased to start heating the pyrolysis furnace 3. At the same time, the fly ash from the waste incineration undergoes low-temperature pyrolysis in the pyrolysis furnace 3. A small amount of pyrolysis gas is generated. The pyrolysis gas is under positive pressure and will flow into the incineration furnace of the waste incinerator 4, where the organic pollutants are decomposed at high temperature. The flue gas discharged from the waste incinerator 4 enters the gas-to-gas heat exchanger 2 through the main flue gas path and exchanges heat with the cold air in the secondary air bypass. During this process, the flue gas temperature needs to be controlled between 800℃ and 900℃. Since it is difficult to control the flow rate of flue gas when the flue gas temperature is too high, a flue gas bypass is set up to divert the flow. This allows some of the high-temperature flue gas to be cooled to 600℃ to 700℃ in the flue gas cooler 8, and the flow rate into the main path is controlled by the flue gas damper 9, thereby achieving temperature regulation of the entire flue gas.

[0018] Compared with existing technologies, this utility model controls the temperature of secondary air and flue gas by setting up secondary air bypass and flue gas bypass, and reuses the heat at the same time. It makes full use of the heat of flue gas, realizes the safe operation of the waste incineration fly ash pyrolysis system, and minimizes the impact on the operation of the waste incinerator. The relatively simple system structure improves the heat utilization efficiency of waste incineration and fly ash pyrolysis, saves costs, and solves the technical problems of high operating costs and complex procedures in existing waste incineration fly ash treatment systems.

Claims

1. A bypass-assisted energy-saving fly ash pyrolysis system, comprising a waste incinerator (4) and a pyrolysis furnace (3), wherein the pyrolysis gas outlet of the pyrolysis furnace (3) is connected to the combustion chamber of the waste incinerator (4), and the fly ash from the waste incinerator (4) is pyrolyzed by the pyrolysis furnace (3), characterized in that: The gas that absorbs the heat of the flue gas from the waste incinerator (4) is used as the heating medium for the pyrolysis furnace (3).

2. The bypass-assisted energy-saving fly ash pyrolysis system according to claim 1, characterized in that: The heating medium is the secondary air of the waste incinerator (4), and also includes a secondary air fan (1), a secondary air main line and a secondary air bypass line equipped with a gas-to-gas heat exchanger (2). The secondary air main line includes a secondary air damper (5) and a warm air fan (6) connected in sequence. The secondary air fan (1) is directly connected to the combustion chamber of the waste incinerator (4) through the secondary air main line. The secondary air fan (1) is connected to the air inlet of the outer shell layer of the pyrolysis furnace (3) through the secondary air bypass line. The air outlet of the outer shell layer of the pyrolysis furnace (3) is connected to the combustion chamber of the waste incinerator (4). The flue gas of the waste incinerator (4) flows through the gas-to-gas heat exchanger (2) through the flue gas main line to exchange heat with the gas in the secondary air bypass line. The flue gas main line includes an induced draft fan (7). After heat exchange, the flue gas is driven back to the waste incinerator (4) by the induced draft fan (7).

3. The bypass-assisted energy-saving fly ash pyrolysis system according to claim 2, characterized in that: It also includes a high-temperature flue gas bypass, which is a branch flue of the main flue gas path set between the incineration furnace of the waste incinerator (4) and the gas-to-gas heat exchanger (2). The high-temperature flue gas bypass includes a flue gas cooler (8) and a flue gas damper (9) connected in sequence.

4. The bypass-assisted energy-saving fly ash pyrolysis system according to claim 3, characterized in that: The flue gas cooler (8) adopts a partitioned water-cooled structure.

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