A system for oxygen-enriched combustion of stale garbage and melting of fly ash

Abstract

A system for oxygen-enriched combustion and fly ash melting of stale garbage includes a garbage incineration system, a fly ash melting system and a liquid oxygen gasification system. The garbage incineration system includes a feed hopper, an incinerator, a waste heat boiler, a flue gas purification system, a bag filter, an induced draft fan, a chimney and a fly ash conveying system. The fly ash melting system includes a fly ash melting furnace, a glass collection system, a secondary combustion chamber and a quenching tower. The liquid oxygen gasification system includes a liquid oxygen storage tank and an air-temperature vaporizer. The liquefied oxygen is divided into two routes, one for supplying the grate combustion section of the garbage incineration system and the other for supplying the fly ash melting system. On the one hand, the new type adopts oxygen-enriched combustion technology to effectively increase the furnace temperature of the incinerator; on the other hand, the fly ash generated by garbage incineration enters the fly ash melting furnace, and oxygen-enriched combustion is used to increase the flame temperature. The fly ash does not need to be transported outside, and can be disposed of in an integrated manner in the garbage incineration power plant, which can realize the resource utilization and harmless disposal of stale garbage and fly ash generated by incineration, and has energy saving and consumption reduction.

Description

Technical Field

[0001] The invention belongs to the technical field of garbage treatment, and specifically relates to an oxygen-enriched combustion system for stale garbage and a fly ash melting system. Background Art

[0002] At present, the reconstruction and reuse of landfills have aroused concern, and the huge amount of stale garbage needs to be disposed of urgently. In the existing technology, stale garbage is treated in coordination with domestic waste, that is, the surplus incineration capacity of domestic waste incineration power plants is used to mix and burn a certain proportion of stale garbage, so that the stale garbage can be harmlessly disposed of. Usually, the stale garbage is pre-treated first, and combustibles such as plastics are screened out and enter the waste incinerator for incineration and power generation. Humus soil is used for landscaping, and bricks, tiles and stones are backfilled or made into recycled aggregates. Compared with fresh domestic garbage, stale garbage has a lower calorific value. After entering the furnace for mixing and burning, the furnace temperature will drop and the combustion will be unstable. It is necessary to use diesel to assist combustion, which will lead to increased energy consumption and operating costs. Therefore, the mixing rate of stale garbage should generally not be too high. At the same time, due to the high ash content of stale garbage, the slag rate and fly ash rate are significantly increased, which will cause the load of the slag discharger and ash conveyor to increase, and the power consumption rate of the plant will increase. The fly ash produced by waste incineration is a hazardous waste and needs to be chelated and solidified and transported to a landfill for disposal. An increase in the fly ash rate will also increase the cost of harmless disposal of the fly ash.

[0003] The Chinese utility model patent with publication number CN218936361 U discloses a fly ash coordinated treatment system for a waste incinerator, including: an incinerator, a primary air duct, an oxygen supply device, a fly ash collection device, a fly ash circulation device and other equipment. The patent provides an oxygen-rich environment to promote the combustion process and achieve waste reduction. At the same time, through fly ash recycling, the fly ash is melted and condensed into large particles, reducing the amount of fly ash generated. The patent only reduces the amount of fly ash generated by waste incineration through oxygen-enriched combustion and fly ash circulation in the waste incinerator. In the end, fly ash is still generated and needs to be transported out for harmless disposal.

[0004] The Chinese invention patent application with publication number CN107543172 A discloses a method for oxygen-enriched high-temperature intelligent control and stable incineration of stale garbage, including a grate incinerator and an oxygen-enriched combustion system, the oxygen-enriched combustion system including a burner, an auxiliary fuel supply device, an oxygen supply device, and an ignition fuel supply device. The application is to divide the gaseous oxygen in the oxygen supply device into two paths, one for supplying ignition fuel and the other for supplying auxiliary fuel. It is essentially an oxygen-enriched burner that requires the use of ignition fuel and auxiliary fuel. Utility Model Content

[0005] Technical problems to be solved: In view of the problems in the prior art that stale garbage has a low calorific value, and when it is mixed with domestic garbage into the furnace, the comprehensive calorific value of the solid waste entering the furnace will be reduced, resulting in a decrease in furnace temperature and unstable combustion, and the need to add auxiliary fuel, which leads to increased energy consumption and operating costs. In addition, stale garbage has a high ash content, and when it is mixed with domestic garbage into the furnace, the fly ash rate will be increased, thereby increasing the costs of fly ash chelation, etc., the present invention provides an oxygen-enriched combustion and fly ash melting system for stale garbage, which can realize the resource utilization and harmless disposal of stale garbage and fly ash generated by incineration, and has a good energy-saving and consumption-reducing effect.

[0006] Technical solution: A system for oxygen-enriched combustion of stale garbage and fly ash melting, wherein the stale garbage is pre-treated by screening to separate combustibles from the stale garbage, including a garbage incineration system, a fly ash melting system and a liquid oxygen gasification system.

[0007] The waste incineration system comprises a feed hopper, an incinerator, a waste heat boiler, a flue gas purification system, a bag dust collector, an induced draft fan, a chimney and a fly ash conveying system. The incinerator comprises an incineration furnace and an incineration grate arranged inside the incinerator. The feed hopper is arranged at the inlet of the incinerator and is used to feed stale waste into the incinerator. The incineration grate is used to incinerate the stale waste. The air outlet of the incinerator is connected to the waste heat boiler, the flue gas purification system, the bag dust collector, the induced draft fan and the chimney flue in sequence. The ash outlets of the flue gas purification system and the bag dust collector are respectively connected to the fly ash conveying system. A secondary air inlet pipe is arranged at the throat of the incinerator.

[0008] The fly ash melting system comprises a fly ash melting furnace, a glass body collection system, a secondary combustion chamber, and a quenching tower. The feed port of the fly ash melting furnace is connected to the fly ash conveying system, the slag outlet of the fly ash melting furnace is connected to the glass body collection system, the flue outlet of the fly ash melting furnace is connected to the secondary combustion chamber, the quenching tower and the flue gas purification system in sequence, the fuel of the fly ash melting furnace is natural gas, and a natural gas inlet is provided on one side of the bottom;

[0009] The liquid oxygen gasification system comprises a liquid oxygen storage tank and an air-temperature vaporizer which are connected in sequence. The enriched oxygen coming out of the air-temperature vaporizer is divided into two paths. The first path is mixed with the primary air and connected to the air inlet of the combustion section of the incineration grate. The second path is mixed with the air and connected to the air inlet of the fly ash melting furnace.

[0010] Preferably, the combustibles in the stale garbage are combustibles mainly composed of plastics obtained by removing masonry-like inert substances and humus.

[0011] Preferably, the oxygen-enriched air is oxygen-enriched air with an oxygen content of ≥21%.

[0012] Preferably, the incineration grate is an inclined multi-stage grate furnace, which is divided into five sections. The first / second section is a drying section, the third / fourth section is a combustion section, and the fifth section is a burnout section. An independent wind chamber is provided under each section of the grate, and each wind chamber is connected to primary air respectively. The first oxygen-enriched gas separated from the liquid oxygen gasification system is connected to the wind chamber corresponding to the combustion section.

[0013] Preferably, the liquid oxygen gasification system further comprises a pressure regulating device, which is disposed downstream of the air-temperature vaporizer and is used to regulate the pressure of the gaseous oxygen coming out of the air-temperature vaporizer.

[0014] Preferably, the liquid oxygen gasification system further comprises an oxygen regulating valve b and an oxygen meter b, which are sequentially arranged on the first oxygen-enriched line of the liquid oxygen gasification system to control the oxygen content of the mixed air to be in the range of 21-30%.

[0015] Preferably, the fly ash melting system further comprises an oxygen regulating valve a and an oxygen meter a, which are arranged in sequence on the second oxygen-enriched line of the liquid oxygen gasification system to control the oxygen content of the mixed air to be greater than 40%.

[0016] Beneficial effects: The utility model proposes an oxygen-enriched combustion of stale garbage and a fly ash melting system, which can realize the resource utilization and harmless disposal of stale garbage and fly ash generated by incineration and has a good energy-saving and consumption-reducing effect.

[0017] The combustibles in the stale garbage are screened out through screening pretreatment, thereby increasing the calorific value of the stale garbage entering the furnace. Large pieces of garbage and inert materials such as bricks, tiles and stones in the stale garbage are removed to prevent them from entering the furnace and damaging the grate. The humus in the stale garbage is removed to reduce the ash content of the garbage entering the furnace, reduce the amount of fly ash and slag, avoid coking in the furnace caused by the increase of fly ash, and at the same time reduce the energy consumption and maintenance costs of the fly ash conveyor and slag remover.

[0018] Replacing primary air with oxygen-enriched air (oxygen < 30%) can promote the complete combustion of stale garbage, increase the heat release of garbage, and thus increase the furnace temperature to ensure the 850℃ / 2S requirement. While ensuring stable combustion in the furnace, the use of auxiliary fuel can be reduced, thereby reducing the operating cost increased by burning stale garbage. At the same time, due to the increase in oxygen concentration, the amount of primary air required for combustion and the amount of flue gas generated are reduced accordingly, which is not only conducive to the increase of furnace temperature, but also can reduce the amount of fly ash and flue gas treatment, and reduce the cost of fly ash disposal and flue gas purification.

[0019] The fly ash produced by incineration does not need to be transported for chelation and landfill, but is sent to the fly ash melting furnace by the fly ash conveying system for oxygen-enriched melting. The oxygen content of oxygen-enriched melting is greater than 40%, which can strengthen the combustion process and increase the flame temperature. At the same time, the nitrogen content is reduced, which reduces the heat required to heat the nitrogen, thus saving fuel. The amount of flue gas generated by combustion is reduced (the amount of useless nitrogen and the amount of flue gas generated during the melting process are reduced), the heat loss of flue gas is reduced, and the amount of fuel is saved. Therefore, oxygen-enriched melting has a good energy-saving and consumption-reducing effect. Under oxygen-enriched combustion, the load and atmosphere optimization in the furnace form a more reasonable temperature distribution in the furnace, which can effectively extend the service life of the furnace. After the fly ash is melted, organic pollutants such as dioxins can be effectively digested, and the produced glass can be recycled.

[0020] Compared with CN218936361 U (a waste incinerator fly ash coordinated treatment system), the present application is provided with an independent fly ash melting furnace, which can realize the resource utilization and harmless disposal of fly ash; the patent has the same oxygen enrichment concentration for waste incineration and fly ash melting. Since the present patent has a separate fly ash melting furnace, different oxygen enrichment concentrations can be set in the waste incinerator and the fly ash melting furnace, which makes the disposal of stale waste and fly ash more targeted and can achieve a more efficient and energy-saving effect.

[0021] Compared with CN 107543172 A (a method for intelligently controlling the stable incineration of stale garbage with oxygen-enriched high temperature), the present application increases the oxygen content of the primary air system, and supplies the stale garbage with oxygen-containing gas with a higher oxygen content than the air for incineration, so as to achieve the purpose of efficient combustion and increased furnace temperature, and improve the problem of stale garbage being difficult to burn and difficult to burn out from the source, thereby reducing or replacing the use of auxiliary burners and auxiliary fuels, thereby achieving the effect of energy saving and reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Flow chart for screening combustibles from stale garbage;

[0023] Figure 2 This is a schematic diagram of the structure of a new type of stale garbage oxygen-enriched combustion and fly ash melting system.

[0024] The numbers in the figure represent the following: 1. Waste incineration system; 101. Feed hopper; 102. Incineration furnace; 103. Incineration grate; 104. Waste heat boiler; 105. Flue gas purification system; 106. Bag filter; 107. Induced draft fan; 108. Chimney; 109. Fly ash conveying system; 2. Fly ash melting system; 201. Fly ash melting furnace; 202. Glass collection system; 203. Secondary combustion chamber; 204. Quenching tower; 205. Oxygen regulating valve a; 206. Oxygen meter a; 3. Liquid oxygen gasification system; 301. Liquid oxygen storage tank; 302. Air-temperature vaporizer; 303. Pressure regulating device; 304. Oxygen regulating valve b; 305. Oxygen meter b. DETAILED DESCRIPTION

[0025] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] Glossary:

[0027] Stale garbage: refers to garbage that has been landfilled or piled up for a long time. After a long period of fermentation, organic matter such as kitchen waste, lipids, paper products and plants in the garbage are partially or completely degraded, and the remaining parts are mainly composed of: humus, non-combustible components such as slag, metal, glass and combustible materials mainly composed of difficult-to-degrade plastic products.

[0028] Oxygen-enriched combustion: combustion with oxygen-containing gas whose oxygen content is higher than that of air (21%). By increasing the oxygen concentration in the air, the ignition point temperature and burnout temperature of the fuel can be lowered, and complete combustion can be promoted. It is an efficient and energy-saving combustion technology.

[0029] Fly ash: refers to the capture of the flue gas purification system of domestic waste incineration facilities and the bottom ash settled at the bottom of the flue and chimney, accounting for about 3% to 5% of the amount of incinerated waste.

[0030] Fly ash melting: Under high temperature conditions of about 1300℃~1400℃, the organic matter in the fly ash undergoes decomposition, gasification, combustion and other reactions, and the inorganic matter melts into glassy slag, which forms glass after cooling. After the fly ash is melted, organic pollutants such as dioxins can be effectively eliminated. At the same time, melting greatly increases the density of fly ash, reducing the volume by up to 2 / 3, and the slag can be used as roadbed material, concrete aggregate, etc., to achieve the purpose of resource recycling.

[0031] Unless otherwise specified, the raw materials and equipment used in the examples of this specification are all from common commercially available products. Example 1

[0032] This embodiment provides an oxygen-enriched combustion and fly ash melting system for stale garbage, wherein the stale garbage is pre-screened to screen out combustibles from the stale garbage. The combustibles from the stale garbage are mainly plastic combustibles obtained after removing inert materials such as bricks and humus. Figure 1 As shown in the figure, the stale garbage is first manually sorted to remove large interfering objects and inert materials to avoid damage to subsequent screening equipment. Then it enters the drum screen and vibrating screen for secondary screening, and the screened material is humus soil, which can be used for landscaping. The screened material enters the wind separator to sort out the light materials as combustibles and enter the furnace to be burned with domestic garbage. The heavy materials are inert materials such as bricks, tiles and stones, which are landfilled or made into recycled aggregates.

[0033] See also Figure 2 The stale garbage oxygen-enriched combustion and fly ash melting system comprises a garbage incineration system 1, a fly ash melting system 2 and a liquid oxygen gasification system 3, wherein the garbage incineration system 1 comprises a feed hopper 101, an incinerator, a waste heat boiler 104, a flue gas purification system 105, a bag filter 106, an induced draft fan 107, a chimney 108 and a fly ash conveying system 109, the incinerator comprises an incineration furnace 102 and an incineration grate 103 arranged therein, and the The feed hopper 101 is provided at the inlet of the incinerator, and is used to feed stale garbage into the incinerator. The incineration grate 103 is used to incinerate stale garbage. The gas outlet of the incinerator is connected to the waste heat boiler 104, the flue gas purification system 105, the bag filter 106, the induced draft fan 107 and the chimney 108 flue in sequence. The ash outlets of the flue gas purification system 105 and the bag filter 106 are respectively connected to the fly ash conveying system 109. A secondary air inlet pipe is provided at the throat of the incinerator. (The primary air is introduced from the bottom of the grate, generally at 220°C, to promote the complete combustion of fixed carbon; the secondary air is introduced from the throat of the furnace, generally at 40°C, to play a disturbing role and promote the complete combustion of combustible gas)

[0034] The fly ash melting system 2 includes a fly ash melting furnace 201, a glass collection system 202, a secondary combustion chamber 203, and a quenching tower 204. The feed port of the fly ash melting furnace 201 is connected to the fly ash conveying system 109, the slag outlet of the fly ash melting furnace 201 is connected to the glass collection system 202, the flue outlet of the fly ash melting furnace 201 is connected to the secondary combustion chamber 203, the quenching tower 204 and the flue gas purification system 105 in sequence, the fuel of the fly ash melting furnace 201 is natural gas, and a natural gas inlet is provided on one side of the bottom.

[0035] The liquid oxygen gasification system 3 includes a liquid oxygen storage tank 301 and an air-temperature vaporizer 302 connected in sequence. The rich oxygen coming out of the air-temperature vaporizer 302 is divided into two paths. The first path is mixed with the primary air and connected to the air inlet of the incineration grate combustion section 103. The second path is mixed with the air and connected to the air inlet of the fly ash melting furnace 201. Example 2

[0036] The same as Example 1, except that the incineration grate 103 is an inclined multi-stage grate furnace, which is divided into five sections. The first / second section is a drying section, the third / fourth section is a combustion section, and the fifth section is a burnout section. An independent wind chamber is provided under each section of the grate, and each wind chamber is connected to primary air respectively. The first oxygen-enriched gas separated from the liquid oxygen gasification system 3 is connected to the wind chamber corresponding to the combustion section.

[0037] The liquid oxygen gasification system 3 further includes a pressure regulating device 303 , which is disposed downstream of the air-temperature vaporizer 302 and is used to regulate the pressure of the gaseous oxygen coming out of the air-temperature vaporizer 302 .

[0038] The liquid oxygen gasification system 3 also includes an oxygen regulating valve b304 and an oxygen meter b305, which are sequentially arranged on the first oxygen-enriched line of the liquid oxygen gasification system 3 to control the oxygen content of the mixed air to be in the range of 21-30%.

[0039] The fly ash melting system 2 further comprises an oxygen regulating valve a205 and an oxygen meter a206, which are arranged in sequence on the second oxygen-enriched path of the liquid oxygen gasification system 3 to control the oxygen content of the mixed air to be greater than 40%.

[0040] Based on the above-mentioned method for using the oxygen-enriched combustion and fly ash melting system of stale garbage, the specific method is as follows: the combustibles in the stale garbage screened out enter the garbage incineration system 1 from the feed hopper 101 and burn on the incineration grate 103. The liquid oxygen sent from the liquid oxygen tanker is charged into the liquid oxygen storage tank 301 for storage, and the liquid oxygen is vaporized into gaseous oxygen by the air-temperature vaporizer 302, and is sent to the primary air duct of the combustion section after pressure regulation (0.2-0.3 MPa) by the pressure regulating device 303, and is mixed with the primary air and sent to the grate combustion section through the primary fan to promote the efficient combustion of stale garbage. An oxygen meter b 305 is provided on the primary air duct of the combustion section, which can adjust the opening of the oxygen regulating valve b 304 according to the calorific value of the stale garbage and the combustion condition in the furnace, and control the oxygen content of the mixed air to be no higher than 30%, so that the garbage in the furnace is in low-concentration oxygen-enriched combustion.

[0041] The flue gas generated by the incineration of garbage is purified by the waste heat boiler 104, the flue gas purification system 105 and the bag filter 106, and then extracted by the induced draft fan 107 to the chimney 108 for discharge. The fly ash generated by the flue gas purification system 105 and the bag filter 106 is sent to the fly ash melting furnace 201 for melting and resource disposal through the fly ash conveying system 109. The fuel is natural gas. The oxygen generated by the liquid oxygen gasification system is mixed with air and enters the fly ash melting furnace 201 to assist combustion. According to the reading of the oxygen meter a 206, the opening of the oxygen regulating valve a 305 is adjusted to control the oxygen concentration of the combustion gas to be greater than 40%. After the fly ash is melted by oxygen enrichment, the vitreous body generated can be collected by the vitreous body collection system 202 and can be utilized as a resource. The flue gas generated by the combustion enters the secondary combustion chamber 203 for full combustion. The temperature of the secondary combustion chamber is greater than 1100°C and the residence time is greater than 2 seconds. The flue gas discharged from the secondary combustion chamber 203 enters the quench tower 204 to be cooled to 200°C, and is transported to the inlet of the flue gas purification system 105 of the waste incineration system through the flue gas pipeline. After entering the flue gas purification system 105 for purification, it meets the emission standards.

[0042] This new type uses oxygen-enriched combustion technology to enhance combustion intensity, effectively increase furnace temperature, and stabilize combustion conditions. On the one hand, it can reduce the use of auxiliary fuel, reduce energy consumption and operating costs, and on the other hand, it can increase the blending rate of stale garbage and increase the amount of stale garbage processed. The fly ash produced by garbage incineration enters the fly ash melting furnace, and oxygen-enriched combustion is used to increase the flame temperature and reduce the amount of useless nitrogen and flue gas, thereby improving the thermal efficiency of combustion, reducing heat loss, and reducing fuel consumption. Fly ash does not need to be transported outside, and can be directly disposed of in an integrated manner in the garbage incineration power plant. The glass formed after the fly ash is melted can be used as a resource to achieve the reduction, harmlessness, and resource utilization of fly ash.

Claims

1. A system for oxygen-enriched combustion of stale garbage and melting of fly ash, wherein the stale garbage is pre-treated by screening to screen out combustibles from the stale garbage, characterized in that: It comprises a waste incineration system (1), a fly ash melting system (2) and a liquid oxygen gasification system (3), wherein: The waste incineration system (1) comprises a feed hopper (101), an incinerator, a waste heat boiler (104), a flue gas purification system (105), a bag filter (106), an induced draft fan (107), a chimney (108) and a fly ash conveying system (109); the incinerator comprises an incineration furnace (102) and an incineration grate (103) arranged therein; the feed hopper (101) is arranged at the inlet of the incinerator and is used to feed the fly ash to the incinerator. Aged garbage is fed into the incineration grate (103) for incinerating the aged garbage. The gas outlet of the incinerator is connected to the waste heat boiler (104), the flue gas purification system (105), the bag filter (106), the induced draft fan (107) and the chimney (108) flue in sequence. The ash outlets of the flue gas purification system (105) and the bag filter (106) are respectively connected to the fly ash conveying system (109). A secondary air inlet pipe is provided at the throat of the incinerator. The fly ash melting system (2) comprises a fly ash melting furnace (201), a glass body collection system (202), a secondary combustion chamber (203), and a quenching tower (204); the feed port of the fly ash melting furnace (201) is connected to the fly ash conveying system (109); the slag outlet of the fly ash melting furnace (201) is connected to the glass body collection system (202); the flue outlet of the fly ash melting furnace (201) is connected to the secondary combustion chamber (203), the quenching tower (204), and the flue gas purification system (105) in sequence; the fuel of the fly ash melting furnace (201) is natural gas, and a natural gas inlet is provided on one side of the bottom; The liquid oxygen gasification system (3) comprises a liquid oxygen storage tank (301) and an air-temperature vaporizer (302) connected in sequence. The enriched oxygen from the air-temperature vaporizer (302) is divided into two paths. The first path is mixed with primary air and connected to the air inlet of the combustion section of the incineration grate (103). The second path is mixed with air and connected to the air inlet of the fly ash melting furnace (201).

2. The stale garbage oxygen-enriched combustion and fly ash melting system according to claim 1 is characterized in that: The combustibles in the stale garbage are combustibles mainly composed of plastics obtained by removing masonry-like inert substances and humus.

3. The stale garbage oxygen-enriched combustion and fly ash melting system according to claim 1 is characterized in that: The oxygen-enriched air is oxygen-enriched air with an oxygen content of ≥21%.

4. The stale garbage oxygen-enriched combustion and fly ash melting system according to claim 1 is characterized in that: The incineration grate (103) is an inclined multi-stage grate furnace, which is divided into five sections. The first / second section is a drying section, the third / fourth section is a combustion section, and the fifth section is a burnout section. An independent wind chamber is provided under each section of the grate, and each wind chamber is connected to primary air. The first oxygen-enriched air separated from the liquid oxygen gasification system (3) is connected to the wind chamber corresponding to the combustion section.

5. The stale garbage oxygen-enriched combustion and fly ash melting system according to claim 1 is characterized in that: The liquid oxygen gasification system (3) further comprises a pressure regulating device (303), wherein the pressure regulating device (303) is arranged downstream of the air-temperature vaporizer (302) and is used to regulate the pressure of the gaseous oxygen coming out of the air-temperature vaporizer (302).

6. The stale garbage oxygen-enriched combustion and fly ash melting system according to claim 1 is characterized in that: The liquid oxygen gasification system (3) further comprises an oxygen regulating valve b (304) and an oxygen meter b (305), which are arranged in sequence on the first oxygen-enriched path of the liquid oxygen gasification system (3) and are used to control the oxygen content of the mixed air to be in the range of 21-30%.

7. The stale garbage oxygen-enriched combustion and fly ash melting system according to claim 1 is characterized in that: The fly ash melting system (2) further comprises an oxygen regulating valve a (205) and an oxygen meter a (206), wherein the oxygen regulating valve a (205) and the oxygen meter a (206) are arranged in sequence on the second oxygen-enriched path of the liquid oxygen gasification system (3) and are used to control the oxygen content of the mixed air to be greater than 40%.

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