Cement kiln cluster large-scale oxygen enrichment matching combustion-supporting system

Abstract

The utility model discloses a cement kiln cluster scale oxygen enrichment matching combustion-supporting system, including air filter, air compressor, air precooling system, air purification system, main heat exchanger, high pressure rectifying column, medium pressure rectifying column, low pressure rectifying column, condensation evaporimeter I, condensation evaporimeter II, liquid oxygen self -pressure booster, supercooler, expander and electric heater. The utility model air compressor adopts segmented type booster, adopts three towers double condensation rectification process, and the heat exchange path of creative matching cold and heat source is used for the protection gas of different distance cement kiln coal powder bin in cement kiln cluster from high pressure rectifying column and medium pressure rectifying column respectively and is drawn out nitrogen product of different pressure grades, and the low pressure oxygen and high pressure oxygen are drawn out and are used for the oxygen enrichment combustion-supporting of different distance cement kiln in cement kiln cluster.

Description

Technical Field

[0001] This utility model relates to the field of large-scale oxygen-enriched combustion technology for cement kiln clusters, specifically to a large-scale oxygen-enriched and matched combustion system for cement kiln clusters. Background Technology

[0002] The cement industry contributes approximately 13% of the nation's CO2 emissions and over 17% of its nitrogen oxide emissions, facing dual pressures from "dual carbon" targets and ultra-low emission retrofit policies. Traditional combustion methods suffer from low combustion efficiency and large flue gas emissions due to the high nitrogen content (79%) in the air. Furthermore, incomplete combustion of pulverized coal occurs during the cement clinker calcination process, resulting in heat loss and fluctuations in secondary air temperature, affecting clinker production and hazardous waste disposal capacity. Through the application of oxygen-enriched combustion in cement kiln systems in recent years, it has been found that using oxygen-enriched combustion in cement kiln systems can shorten pulverized coal burnout time, reduce excess air coefficient, increase flame temperature by over 100°C, and reduce flue gas emissions and fuel consumption.

[0003] Many large cement groups have numerous cement kiln clusters, meaning that many factories have multiple (usually 3-6) cement clinker production lines located in the same area. The thermal conditions of each line can vary greatly, and the distances between the lines are also quite far. The key is to achieve large-scale centralized oxygen supply to the cement kiln clusters, optimize the oxygen production process to minimize oxygen production costs, and coordinate oxygen and nitrogen supply from multiple production lines to minimize the marginal cost of oxygen-enriched combustion in the cement kiln clusters. Utility Model Content

[0004] The purpose of this invention is to provide a large-scale oxygen-enriched combustion system for cement kiln clusters to address the shortcomings of existing technologies.

[0005] The present invention adopts the following technical solution:

[0006] A large-scale oxygen-enriched combustion-supporting system for cement kiln clusters includes an air filter, an air compressor, an air precooling system, an air purification system, a main heat exchanger, a high-pressure distillation column, a medium-pressure distillation column, a low-pressure distillation column, a condenser-evaporator I, a condenser-evaporator II, a liquid oxygen self-pressurizer, a subcooler, an expander, and an electric heater.

[0007] The air compressor is a segmented booster air compressor;

[0008] The air filter, air compressor, air precooling system, air purification system, electric heater, expander booster, and expander booster aftercooler are located outside the cold box;

[0009] The main heat exchanger, high-pressure distillation column, medium-pressure distillation column, low-pressure distillation column, condenser-evaporator I, condenser-evaporator II, liquid oxygen self-pressurizer, subcooler, and expander are located inside the cold box;

[0010] The low-pressure distillation column is located above the high-pressure distillation column, the condenser-evaporator I is located at the bottom of the low-pressure distillation column, the condenser-evaporator II is located above the medium-pressure distillation column, and the liquid oxygen self-pressurizer is located below the liquid oxygen outlet of the low-pressure distillation column.

[0011] An air filter, an air compressor front and middle booster section, an air compressor interstage cooler, an air precooling system, and an air purification system are connected in sequence. The air purification system is connected to the first inlet of the main heat exchanger and the rear booster section of the air compressor. The first outlet of the main heat exchanger is connected to the bottom of the medium-pressure distillation column. The rear booster section of the air compressor is connected to the air compressor aftercooler. The air compressor aftercooler is connected to the second inlet, the third inlet, and the expander booster compressor of the main heat exchanger. The second outlet of the main heat exchanger is connected to the bottom of the high-pressure distillation column. The third outlet of the main heat exchanger is connected to the liquid oxygen self-booster. The liquid oxygen self-booster is connected to the bottom of the high-pressure distillation column. The expander booster compressor is connected to the expander booster compressor aftercooler. The expander booster compressor aftercooler is connected to the fourth inlet of the main heat exchanger. The fourth outlet of the main heat exchanger is connected to the expander. The expander is connected to the bottom of the low-pressure distillation column.

[0012] The liquid air outlet of the high-pressure distillation column is connected to the subcooler, which is connected to condenser-evaporator II. A throttling valve is installed on the connecting pipeline between the subcooler and condenser-evaporator II. The oxygen-enriched air outlet of condenser-evaporator II is connected to the upper part of the low-pressure distillation column, and a throttling valve is also installed on the connecting pipeline between the oxygen-enriched air outlet of condenser-evaporator II and the upper part of the low-pressure distillation column. The high-pressure nitrogen outlet of the high-pressure distillation column is connected to the main heat exchanger and condenser-evaporator I, respectively. The main heat exchanger is connected to an external high-pressure nitrogen product supply network for distant users. The liquid nitrogen outlet of condenser-evaporator I is connected to the top of the high-pressure distillation column. The waste nitrogen outlet of the high-pressure distillation column is connected to the subcooler, which is connected to the upper part of the low-pressure distillation column. A throttling valve is installed on the connecting pipeline between the subcooler and the upper part of the low-pressure distillation column. The waste liquid nitrogen outlet of the high-pressure distillation column is connected to the subcooler, which is connected to the top of the low-pressure distillation column. A throttling valve is also installed on the connecting pipeline between the subcooler and the top of the low-pressure distillation column.

[0013] The oxygen-enriched liquid air outlet of the medium-pressure distillation column is connected to the lower part of the low-pressure distillation column. A throttling valve is installed on the connecting pipeline between the oxygen-enriched liquid air outlet of the medium-pressure distillation column and the lower part of the low-pressure distillation column. The medium-pressure nitrogen outlet of the medium-pressure distillation column is connected to the main heat exchanger and the condenser-evaporator II, respectively. The main heat exchanger is connected to the external medium-pressure nitrogen product supply network for nearby users. The liquid nitrogen outlet of the condenser-evaporator II is connected to the top of the medium-pressure distillation column and the top of the low-pressure distillation column, respectively. A throttling valve is installed on the connecting pipeline between the liquid nitrogen outlet of the condenser-evaporator II and the top of the low-pressure distillation column.

[0014] The liquid oxygen outlet of the low-pressure distillation column is connected to the liquid oxygen self-pressurizer. The high-pressure oxygen outlet of the liquid oxygen self-pressurizer is connected to the main heat exchanger, which is connected to an external high-pressure oxygen product supply network for distant users. The low-pressure oxygen outlet of the condenser-evaporator I is connected to the main heat exchanger, which is connected to an external low-pressure oxygen product supply network for nearby users. The low-pressure nitrogen outlet of the low-pressure distillation column is connected in sequence to the subcooler and the main heat exchanger, which is connected to the air precooling system. The waste nitrogen outlet of the low-pressure distillation column is connected in sequence to the subcooler and the main heat exchanger, which is connected to the air precooling system and the electric heater, respectively. The electric heater is connected to the air purification system.

[0015] Furthermore, the air filter is a self-cleaning air filter.

[0016] Furthermore, the air precooling system includes an air-cooled tower, a water-cooled tower, and a water-cooled unit. The circulating water inlet is connected to the cooling water pump and the water-cooled tower, respectively. The cooling water pump outlet is connected to the middle of the air-cooled tower. The water-cooled tower outlet is connected to the chilled water pump and the water-cooled unit in sequence. The water-cooled unit is connected to the upper part of the air-cooled tower.

[0017] Furthermore, the air purification system is an alternating molecular sieve adsorber.

[0018] The beneficial effects of this utility model are:

[0019] 1. The air compressor of this utility model adopts segmented pressurization. The raw material air is pressurized to the set pressure (0.24-0.26 MPaG) in the front and middle pressurization sections, and then pre-cooled and purified by the air pre-cooling system and the air purification system. After that, a stream is drawn back to the rear pressurization section of the air compressor to continue pressurizing to the set pressure (0.4-0.45 MPaG). Since the pressurization medium in the rear pressurization section of the air compressor is dry, clean and low temperature air, the pressurization efficiency of the rear pressurization section of the air compressor can be effectively improved, energy consumption can be reduced, and the cooling process after pressurization does not require drainage, so drainage facilities can be eliminated, reducing costs.

[0020] 2. This utility model adopts a three-tower double-condensation distillation process, which includes a medium-pressure distillation tower. Because the medium-pressure distillation tower has a lower pressure than the high-pressure distillation tower, the air is more efficiently distilled through the medium-pressure distillation tower, and oxygen-enriched liquid air with a higher oxygen content can be separated. Introducing the high-concentration oxygen-enriched liquid air into the low-pressure distillation tower can effectively reduce the distillation load of the low-pressure distillation tower and improve the oxygen product extraction rate of the low-pressure distillation tower.

[0021] 3. This utility model creatively matches the heat exchange path of the cold and heat sources. It uses liquid air from the bottom of the high-pressure distillation column, after being subcooled by a cooler, as the cold source for the condenser-evaporator I at the top of the medium-pressure distillation column. Because the oxygen concentration in the liquid air at the bottom of the high-pressure distillation column is lower than that in the oxygen-rich liquid air at the bottom of the medium-pressure distillation column, for the condenser-evaporator I at the top of the medium-pressure distillation column, under the same pressure and heat exchange temperature difference, the lower the oxygen concentration in the liquid air used as the cold source, the lower the pressure required for the nitrogen used as the heat source. Therefore, using liquid air with a low oxygen concentration as the cold source can reduce the nitrogen pressure at the top of the medium-pressure distillation column, which is used as the heat source, and thus reduce the operating pressure of the medium-pressure distillation column. The processing air source of the medium-pressure distillation column is pressurized after the inlet and outlet pressure section of the air compressor, so the exhaust pressure after the inlet and outlet pressure section of the air compressor can be reduced, thereby effectively reducing the energy consumption of the air compressor.

[0022] 4. This utility model extracts nitrogen products of different pressure levels from high-pressure and medium-pressure distillation columns for use as protective gas for pulverized coal silos in cement kiln clusters. Because cement kiln clusters are large and the production lines of each cement kiln are far apart, medium-pressure nitrogen drawn from the medium-pressure distillation column is used as protective gas for pulverized coal silos for cement kilns that are close to each other, while high-pressure nitrogen drawn from the high-pressure distillation column is used as protective gas for pulverized coal silos for cement kilns that are far apart. By effectively matching the nitrogen pressure and distance, the extraction of high-pressure nitrogen can be effectively reduced, better matching the use of nitrogen as protective gas in cement kiln clusters, and reducing system energy consumption.

[0023] 5. This utility model introduces low-pressure oxygen and high-pressure oxygen. The low-pressure oxygen is directly drawn from the condenser-evaporator I and used for oxygen-enriched combustion in nearby cement kilns within a cement kiln cluster. The high-pressure oxygen adopts a liquid oxygen self-pressurization process. By setting up a liquid oxygen self-pressurizer, the pressure of the liquid oxygen is increased by the gravity of the liquid itself. At the same time, air is used as a heat source because the oxygen content in air is higher than that in nitrogen, and the liquefaction point temperature is higher, which can increase the heat exchange temperature difference of the liquid oxygen self-pressurizer. The effective matching of the two can obtain a higher pressure oxygen product without increasing air pressure and energy consumption. This part of the high-pressure oxygen is used for oxygen-enriched combustion in distant cement kilns within a cement kiln cluster. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the system structure of this utility model. Detailed Implementation

[0025] The present invention will be further explained below with reference to the embodiments and accompanying drawings. The following embodiments are only used to illustrate the present invention, but are not intended to limit the scope of implementation of the present invention.

[0026] A large-scale oxygen-enriched combustion system for cement kiln clusters, such as Figure 1As shown, it includes an air filter 1, an air compressor 2, an air precooling system 3, an air purification system 4, a main heat exchanger 5, a high-pressure distillation column 6, a medium-pressure distillation column 8, a low-pressure distillation column 7, a condenser-evaporator I 9, a condenser-evaporator II 10, a liquid oxygen self-pressurizer 11, a subcooler 12, an expander 13, and an electric heater 14.

[0027] Air filter 1 is preferably a self-cleaning air filter;

[0028] Air compressor 2 is a segmented booster air compressor (separately, a front booster section, a middle booster section, and a rear booster section);

[0029] The air precooling system 3 includes an air-cooled tower 301, a water-cooled tower 304, and a water-cooled unit 305. The circulating water inlet is connected to the cooling water pump 302 and the water-cooled tower 304 respectively. The outlet of the cooling water pump 302 is connected to the middle of the air-cooled tower 301. The outlet of the water-cooled tower 304 is connected to the chilled water pump 303 and the water-cooled unit 305 in sequence. The water-cooled unit 305 is connected to the upper part of the air-cooled tower 301.

[0030] Air purification system 4 is preferably an alternating molecular sieve adsorber;

[0031] Air filter 1, air compressor 2, air precooling system 3, air purification system 4, electric heater 14, expander booster 1301, expander booster aftercooler 1302 are located outside the cold box;

[0032] The main heat exchanger 5, high-pressure distillation column 6, medium-pressure distillation column 8, low-pressure distillation column 7, condenser-evaporator I 9, condenser-evaporator II 10, liquid oxygen self-pressurizer 11, subcooler 12, and expander 13 are located inside the cold box.

[0033] The low-pressure distillation column 7 is located above the high-pressure distillation column 6, the condenser-evaporator I9 is ​​located at the bottom of the low-pressure distillation column 7, the condenser-evaporator II10 is located above the medium-pressure distillation column 8, and the liquid oxygen self-pressurizer 11 is located below the liquid oxygen outlet of the low-pressure distillation column 7.

[0034] Air filter 1, air compressor pre- and mid-stage booster section 201, air compressor interstage cooler, air precooling system 3, and air purification system 4 are connected in sequence. Air purification system 4 is connected to the first inlet 501 of the main heat exchanger and the rear booster section 202 of the air compressor. The first outlet of the main heat exchanger 5 is connected to the bottom of the medium-pressure distillation column 8. The rear booster section 202 of the air compressor is connected to the air compressor aftercooler 203. Air compressor aftercooler 203 is connected to the second inlet 502 of the main heat exchanger and the third outlet 502 of the main heat exchanger. The expansion compressor 1301 is connected to the inlet 503; the second outlet of the main heat exchanger 5 is connected to the bottom of the high-pressure distillation column 6; the third outlet of the main heat exchanger 5 is connected to the liquid oxygen self-pressurizer 11; the liquid oxygen self-pressurizer 11 is connected to the bottom of the high-pressure distillation column 6; the expansion compressor 1301 is connected to the expansion compressor aftercooler 1302; the expansion compressor aftercooler 1302 is connected to the fourth inlet 504 of the main heat exchanger; the fourth outlet of the main heat exchanger 5 is connected to the expansion compressor 13; and the expansion compressor 13 is connected to the bottom of the low-pressure distillation column 7.

[0035] The liquid air outlet of the high-pressure distillation column 6 is connected to the subcooler 12, which is connected to the condenser-evaporator II 10. A throttling valve is installed on the connecting pipeline between the subcooler 12 and the condenser-evaporator II 10. The oxygen-enriched air outlet of the condenser-evaporator II 10 is connected to the upper part of the low-pressure distillation column 7, and a throttling valve is installed on the connecting pipeline between the oxygen-enriched air outlet of the condenser-evaporator II 10 and the upper part of the low-pressure distillation column 7. The high-pressure nitrogen outlet of the high-pressure distillation column 6 is connected to the main heat exchanger 5 and the condenser-evaporator I 9, respectively. The main heat exchanger 5 is connected to an external... The high-pressure nitrogen product is supplied to the pipeline network of remote users. The liquid nitrogen outlet of the condenser evaporator I9 is ​​connected to the top of the high-pressure distillation column 6; the waste nitrogen outlet of the high-pressure distillation column 6 is connected to the subcooler 12, the subcooler 12 is connected to the upper part of the low-pressure distillation column 7, and a throttling valve is installed on the connecting pipeline between the subcooler 12 and the upper part of the low-pressure distillation column 7; the waste liquid nitrogen outlet of the high-pressure distillation column 6 is connected to the subcooler 12, the subcooler 12 is connected to the top of the low-pressure distillation column 7, and a throttling valve is installed on the connecting pipeline between the subcooler 12 and the top of the low-pressure distillation column 7.

[0036] The oxygen-enriched liquid air outlet of the medium-pressure distillation column 8 is connected to the lower part of the low-pressure distillation column 7. A throttling valve is installed on the connecting pipeline between the oxygen-enriched liquid air outlet of the medium-pressure distillation column 8 and the lower part of the low-pressure distillation column 7. The medium-pressure nitrogen outlet of the medium-pressure distillation column 8 is connected to the main heat exchanger 5 and the condenser-evaporator II10 respectively. The main heat exchanger 5 is connected to the external medium-pressure nitrogen product supply network for nearby users. The liquid nitrogen outlet of the condenser-evaporator II10 is connected to the top of the medium-pressure distillation column 8 and the top of the low-pressure distillation column 7 respectively. A throttling valve is installed on the connecting pipeline between the liquid nitrogen outlet of the condenser-evaporator II10 and the top of the low-pressure distillation column 7.

[0037] The liquid oxygen outlet of the low-pressure distillation column 7 is connected to the liquid oxygen self-pressurizer 11. The high-pressure oxygen outlet of the liquid oxygen self-pressurizer 11 is connected to the main heat exchanger 5. The main heat exchanger 5 is connected to the external high-pressure oxygen product supply network for distant users. The low-pressure oxygen outlet of the condenser-evaporator I9 is ​​connected to the main heat exchanger 5. The main heat exchanger 5 is connected to the external low-pressure oxygen product supply network for nearby users. The low-pressure nitrogen outlet of the low-pressure distillation column 7 is connected to the subcooler 12 and the main heat exchanger 5 in sequence. The main heat exchanger 5 is connected to the air precooling system 3. The waste nitrogen outlet of the low-pressure distillation column 7 is connected to the subcooler 12 and the main heat exchanger 5 in sequence. The main heat exchanger 5 is connected to the air precooling system 3 and the electric heater 14 in sequence. The electric heater 14 is connected to the air purification system 4.

[0038] The functions of the above components are as follows:

[0039] Air filter 1 is used to filter out dust and mechanical impurities from the raw material air;

[0040] Air compressor 2 is used to pressurize filtered air to a set pressure; it is also used to pressurize a portion of purified air to a set pressure.

[0041] Air precooling system 3 is used to precool the air that has been filtered and pressurized in sequence;

[0042] Air purification system 4 is used to purify the air that has been filtered, pressurized and pre-cooled in sequence.

[0043] The main heat exchanger 5 is used to cool a portion of the purified air; to cool the air that has been sequentially pressurized by the air compressor's rear pressurization section 202 and cooled by the air compressor's aftercooler 203; to cool the air that has been sequentially pressurized by the expander pressurizer 1301 and cooled by the expander pressurizer aftercooler 1302; to reheat a portion of the high-pressure nitrogen; to reheat a portion of the medium-pressure nitrogen; to reheat the high-pressure oxygen; to reheat the low-pressure oxygen; to reheat the low-pressure nitrogen; and to reheat the waste nitrogen.

[0044] High-pressure distillation column 6 is used to distill the introduced air into liquid air and high-pressure nitrogen.

[0045] Medium-pressure distillation column 8 is used to distill the introduced air into oxygen-enriched liquid air and medium-pressure nitrogen.

[0046] Low-pressure distillation column 7 is used to distill the introduced expanded air, oxygen-enriched liquid air, waste nitrogen, and oxygen-enriched air into liquid oxygen and low-pressure nitrogen.

[0047] The condenser-evaporator I9 is ​​used to exchange heat between liquid oxygen and high-pressure nitrogen. The liquid oxygen is vaporized into low-pressure oxygen, and the high-pressure nitrogen is liquefied into liquid nitrogen.

[0048] The condenser-evaporator II10 is used to exchange heat between liquid air and medium-pressure nitrogen. The liquid air is vaporized into oxygen-enriched air, and the medium-pressure nitrogen is liquefied into liquid nitrogen.

[0049] The liquid oxygen self-pressurizer 11 is used to self-pressurize liquid oxygen and exchange heat between liquid oxygen and air. Liquid oxygen is vaporized and self-pressurized into high-pressure oxygen, and air is cooled to near the liquefaction temperature.

[0050] Subcooler 12 is used to subcool liquid air; to subcool the waste nitrogen gas drawn from high-pressure distillation column 6; to subcool the waste liquid nitrogen drawn from high-pressure distillation column 6; to reheat low-pressure nitrogen gas; and to reheat waste nitrogen gas drawn from low-pressure distillation column 7.

[0051] Expander 13 is used to expand air that has been pressurized by expander 1301, cooled by expander aftercooler 1302, and cooled by main heat exchanger 5 to produce the required cooling capacity for the cold box.

[0052] Electric heater 14 is used to heat the waste nitrogen gas to regenerate the air purification system 4.

[0053] The process of using the above system for large-scale oxygen-enriched combustion matching in cement kiln clusters includes the following steps:

[0054] Step 1: The raw material air enters the air filter 1 to filter out dust and mechanical impurities, and then enters the air compressor pre-compressor section 201 to be pressurized to 0.24-0.26 MPaG. After being cooled to about 40°C by the air compressor interstage cooler, it enters the air precooling system 3 to be precooled to 8-15°C, and then enters the air purification system 4 to remove moisture, CO2, hydrocarbons and other substances.

[0055] Step 2: The purified air is divided into two streams. One stream enters the main heat exchanger 5 and is cooled to near liquefaction temperature before entering the medium-pressure distillation column 8 for distillation. The other stream enters the rear booster section 202 of the air compressor and is boosted to 0.4-0.45 MPaG. After being cooled to approximately 40°C by the air compressor aftercooler 203, it is divided into three streams. One stream enters the main heat exchanger 5 and is cooled to near liquefaction temperature before entering the high-pressure distillation column 6 for distillation. Another stream enters the main heat exchanger 5 and is cooled before entering the liquid oxygen self-booster 11 as a heat source. It is cooled to near liquefaction temperature before entering the high-pressure distillation column 6 for distillation. The third stream enters the expander booster 1301 for boosting and is cooled by the expander booster aftercooler 1302 before entering the main heat exchanger 5 and being cooled to -120°C to -135°C before entering the expander 13 for expansion. After expansion, the air enters the low-pressure distillation column 7 for distillation.

[0056] Step 3: The air entering the high-pressure distillation column 6 is distilled into liquid air and high-pressure nitrogen. The liquid air is subcooled by cooler 12 and throttled by a throttling valve before entering the condenser-evaporator II 10 as a cold source, where it is vaporized into oxygen-enriched air. The oxygen-enriched air is then throttled by a throttling valve before entering the low-pressure distillation column 7 to participate in the distillation process. A portion of the high-pressure nitrogen enters the main heat exchanger 5 for reheating and exits the cold box as a high-pressure nitrogen product (pressure 0.38-0.45 MPaG, purity 3 ppm O2) for long-distance use. The gas supplied to the household pipeline (for the protective gas of the pulverized coal silos of cement kiln clusters at long distances) is used as a heat source. The remaining gas enters the condenser evaporator I9 as a heat source and is liquefied into liquid nitrogen. The liquid nitrogen enters the top of the high-pressure distillation column 6 as reflux liquid. The waste nitrogen gas is drawn from the high-pressure distillation column 6, subcooled by the cooler 12, and throttled by the throttling valve before entering the low-pressure distillation column 7 to participate in distillation. The waste liquid nitrogen is drawn from the high-pressure distillation column 6, subcooled by the cooler 12, and throttled by the throttling valve before entering the top of the low-pressure distillation column 7 as reflux liquid.

[0057] The air entering the medium-pressure distillation column 8 is distilled into oxygen-enriched liquid air and medium-pressure nitrogen. The oxygen-enriched liquid air is throttled by the throttling valve and then enters the low-pressure distillation column 7 to participate in the distillation. Part of the medium-pressure nitrogen enters the main heat exchanger 5 for reheating and then exits the cold box as a medium-pressure nitrogen product (pressure 0.15-0.25 MPaG, purity 3 ppm O2), which is supplied to the pipeline network of nearby users (supplying protective gas for the pulverized coal silos of nearby cement kilns in the cement kiln cluster). The rest enters the condenser evaporator II10 as a heat source and is liquefied into liquid nitrogen. Part of the liquid nitrogen enters the top of the medium-pressure distillation column 8 as reflux liquid, and the rest enters the top of the low-pressure distillation column 7 as reflux liquid after being throttled by the throttling valve.

[0058] After expansion, the air, oxygen-enriched liquid air, and impure nitrogen entering the low-pressure distillation column 7 are distilled into liquid oxygen and low-pressure nitrogen. A portion of the liquid oxygen enters the liquid oxygen self-pressurizer 11 as a cold source, where it is vaporized and self-pressurized (the liquid oxygen self-pressurizer 11 is located below the liquid oxygen outlet of the low-pressure distillation column 7, providing liquid oxygen pressure through the liquid's own gravity) to become high-pressure oxygen. This high-pressure oxygen then enters the main heat exchanger 5 for reheating and exits the cold box as a high-pressure oxygen product (pressure 45-65 kPaG, purity 90-93% O2), supplied to the pipeline network of distant users (supplying the kiln head fans of cement kiln clusters; after mixing with air to a suitable concentration (30-50% O2) via an oxygen-enriched mixer connected to the kiln head fan, it is pressurized by the fan (70-90 kPaG) and introduced into the rotary kiln of the cement kiln to provide oxygen-enriched combustion for pulverized coal). The remaining liquid oxygen is used as a condenser / evaporator in the evaporator I9. The cold source is vaporized into low-pressure oxygen. After being reheated in the main heat exchanger 5, the low-pressure oxygen exits the cold box as a low-pressure oxygen product (pressure 25-35 kPaG, purity 90-93% O2), which is supplied to the pipeline network of nearby users (supplying the kiln head fans of nearby cement kiln clusters, which are mixed with air to a suitable concentration (30-50% O2) through the oxygen-enriched mixer connected to the kiln head fans, and then pressurized by the fans (70-90 kPaG) before being introduced into the rotary kiln of the cement kiln to provide oxygen-enriched combustion for pulverized coal). The low-pressure nitrogen enters the subcooler 12 and the main heat exchanger 5 in sequence, is reheated, and exits the cold box, and is introduced into the air precooling system 3 to cool the water. The waste nitrogen drawn from the low-pressure distillation column 7 enters the subcooler 12 and the main heat exchanger 5 in sequence, is reheated, and exits the cold box. Part of it is introduced into the air precooling system 3 to cool the water, and the rest is introduced into the electric heater 14 to be heated and used as regeneration gas for the air purification system 4.

Claims

1. A large-scale oxygen-enriched combustion system for cement kiln clusters, characterized in that, It includes air filters, air compressors, air precooling systems, air purification systems, main heat exchangers, high-pressure distillation columns, medium-pressure distillation columns, low-pressure distillation columns, condenser-evaporator I, condenser-evaporator II, liquid oxygen self-pressurizer, subcooler, expander, and electric heaters; The air compressor is a segmented booster air compressor; The air filter, air compressor, air precooling system, air purification system, electric heater, expander booster, and expander booster aftercooler are located outside the cold box; The main heat exchanger, high-pressure distillation column, medium-pressure distillation column, low-pressure distillation column, condenser-evaporator I, condenser-evaporator II, liquid oxygen self-pressurizer, subcooler, and expander are located inside the cold box; The low-pressure distillation column is located above the high-pressure distillation column, the condenser-evaporator I is located at the bottom of the low-pressure distillation column, the condenser-evaporator II is located above the medium-pressure distillation column, and the liquid oxygen self-pressurizer is located below the liquid oxygen outlet of the low-pressure distillation column. An air filter, an air compressor front and middle booster section, an air compressor interstage cooler, an air precooling system, and an air purification system are connected in sequence. The air purification system is connected to the first inlet of the main heat exchanger and the rear booster section of the air compressor. The first outlet of the main heat exchanger is connected to the bottom of the medium-pressure distillation column. The rear booster section of the air compressor is connected to the air compressor aftercooler. The air compressor aftercooler is connected to the second inlet, the third inlet, and the expander booster compressor of the main heat exchanger. The second outlet of the main heat exchanger is connected to the bottom of the high-pressure distillation column. The third outlet of the main heat exchanger is connected to the liquid oxygen self-booster. The liquid oxygen self-booster is connected to the bottom of the high-pressure distillation column. The expander booster compressor is connected to the expander booster compressor aftercooler. The expander booster compressor aftercooler is connected to the fourth inlet of the main heat exchanger. The fourth outlet of the main heat exchanger is connected to the expander. The expander is connected to the bottom of the low-pressure distillation column. The liquid air outlet of the high-pressure distillation column is connected to the subcooler, which is connected to condenser-evaporator II. A throttling valve is installed on the connecting pipeline between the subcooler and condenser-evaporator II. The oxygen-enriched air outlet of condenser-evaporator II is connected to the upper part of the low-pressure distillation column, and a throttling valve is also installed on the connecting pipeline between the oxygen-enriched air outlet of condenser-evaporator II and the upper part of the low-pressure distillation column. The high-pressure nitrogen outlet of the high-pressure distillation column is connected to the main heat exchanger and condenser-evaporator I, respectively. The main heat exchanger is connected to an external high-pressure nitrogen product supply network for distant users. The liquid nitrogen outlet of condenser-evaporator I is connected to the top of the high-pressure distillation column. The waste nitrogen outlet of the high-pressure distillation column is connected to the subcooler, which is connected to the upper part of the low-pressure distillation column. A throttling valve is installed on the connecting pipeline between the subcooler and the upper part of the low-pressure distillation column. The waste liquid nitrogen outlet of the high-pressure distillation column is connected to the subcooler, which is connected to the top of the low-pressure distillation column. A throttling valve is also installed on the connecting pipeline between the subcooler and the top of the low-pressure distillation column. The oxygen-enriched liquid air outlet of the medium-pressure distillation column is connected to the lower part of the low-pressure distillation column. A throttling valve is installed on the connecting pipeline between the oxygen-enriched liquid air outlet of the medium-pressure distillation column and the lower part of the low-pressure distillation column. The medium-pressure nitrogen outlet of the medium-pressure distillation column is connected to the main heat exchanger and the condenser-evaporator II, respectively. The main heat exchanger is connected to the external medium-pressure nitrogen product supply network for nearby users. The liquid nitrogen outlet of the condenser-evaporator II is connected to the top of the medium-pressure distillation column and the top of the low-pressure distillation column, respectively. A throttling valve is installed on the connecting pipeline between the liquid nitrogen outlet of the condenser-evaporator II and the top of the low-pressure distillation column. The liquid oxygen outlet of the low-pressure distillation column is connected to the liquid oxygen self-pressurizer. The high-pressure oxygen outlet of the liquid oxygen self-pressurizer is connected to the main heat exchanger, which is connected to an external high-pressure oxygen product supply network for distant users. The low-pressure oxygen outlet of the condenser-evaporator I is connected to the main heat exchanger, which is connected to an external low-pressure oxygen product supply network for nearby users. The low-pressure nitrogen outlet of the low-pressure distillation column is connected in sequence to the subcooler and the main heat exchanger, which is connected to the air precooling system. The waste nitrogen outlet of the low-pressure distillation column is connected in sequence to the subcooler and the main heat exchanger, which is connected to the air precooling system and the electric heater, respectively. The electric heater is connected to the air purification system.

2. The large-scale oxygen-enriched combustion system for cement kiln clusters according to claim 1, characterized in that, The air filter is a self-cleaning air filter.

3. The large-scale oxygen-enriched combustion system for cement kiln clusters according to claim 1, characterized in that, The air precooling system includes an air-cooled tower, a water-cooled tower, and a water-cooled unit. The circulating water inlet is connected to the cooling water pump and the water-cooled tower, respectively. The cooling water pump outlet is connected to the middle of the air-cooled tower. The water-cooled tower outlet is connected to the chilled water pump and the water-cooled unit in sequence. The water-cooled unit is connected to the upper part of the air-cooled tower.

4. The large-scale oxygen-enriched combustion system for cement kiln clusters according to claim 1, characterized in that, The air purification system is an alternating molecular sieve adsorber.

Images