An energy-saving rotary kiln oxygen-enriched combustion system

Abstract

The present invention provides an energy-saving rotary kiln oxygen-enriched combustion system, including: an original factory heat source for generating high-pressure steam; a steam turbine, using the high-pressure steam to drive a centrifuge to generate hot air from the centrifuge, the generated hot air is used to provide sample gas for a high-pressure oxygen production module after being dried and filtered, the heat in the hot air from the centrifuge and the waste heat dryer is used to generate high-pressure steam after waste heat recovery and to generate electricity for power generation components; the high-pressure oxygen production module is used to separate the sample gas into oxygen-enriched gas and obtain oxygen-enriched gas and nitrogen-enriched gas respectively; the nitrogen-enriched gas is used to provide a driving gas source for gas-using equipment; the oxygen-enriched gas is used to provide oxygen for combustion for the rotary kiln. The present invention can recycle the original factory heat source for power generation, and at the same time, the membrane tube can generate high-pressure nitrogen-enriched gas to replace the compressed air in the original workshop, and the oxygen-enriched gas is used to provide the gas required for combustion for the rotary kiln.

Description

Technical Field

[0001] The invention relates to the technical field of air separation, in particular to an energy-saving rotary kiln oxygen-enriched combustion system. Background Art

[0002] The use of oxygen-enriched combustion has the advantages of increasing flame temperature, lowering the ignition point of fuel, accelerating combustion speed, increasing heat utilization, reducing excess air coefficient, reducing flue gas emissions after combustion, and improving cement quality. As we all know, the key to the success of oxygen-enriched combustion in the rotary kiln of a cement plant lies in how to supply oxygen at a low cost and effectively reduce the operating cost, maintenance cost and device cost of the oxygen-enriched device. With the research and development of membrane separation materials and breakthroughs in process technology, the α (alpha) value of oxygen-nitrogen separation of organic membrane separation materials used in air separation is mostly between 2 and 7. Under a certain pressure ratio, oxygen with a purity of about 30% to 60% can be directly obtained from the air. The cost control requirements such as improving the separation coefficient of membrane separation materials, further reducing the separation pressure ratio, and increasing the permeability have reached their limits. The challenges are becoming increasingly difficult to sustain. Especially in many occasions such as cement production processes where compressed air resources are already available, how to organically combine compressed air supply with oxygen-enriched separation, and make full use of these compressed air facilities such as those used for dust cleaning and blockage clearing in the original cement process, and what separation technology can be used to use these compressed air to obtain oxygen-enriched nitrogen at a low cost without affecting the original gas demand for dust cleaning and blockage clearing. The oxygen-enriched oxygen obtained at a low cost can provide additional oxidants for cement rotary kilns to implement oxygen-enriched combustion technology transformation and generate additional economic benefits. An efficient solution is urgently needed.

[0003] In view of this, application number CN202110222362.5 proposes a method and device for oxygen supply for oxygen-enriched combustion in a cement rotary kiln (hereinafter referred to as the "scheme and device"), which adopts membrane separation oxygen production technology to be organically coupled to the original compressed air supply facility, and separates the original compressed air into two gases: nitrogen-rich and oxygen-rich; the generated nitrogen-rich directly replaces the compressed air demand of the original factory and recovers the compression energy; the generated oxygen-rich can be sent to the furnace to directly completely or partially replace the original clean air and coal air for oxygen-enriched combustion, recover the compression energy of the fan, and obtain additional economic benefits due to oxygen-enriched combustion; it also fully considers the extreme conditions of compressed air use, and adopts a spare compressed air compensation circuit for flow compensation, which generally realizes the oxygen supply scheme of exchanging compressed air for oxygen, greatly reducing the energy consumption of oxygen extraction.

[0004] This "scheme and device" utilizes the original air compressor to compress the air and then provides it to the membrane separator. Since the original air compressor not only consumes energy during operation, but also cannot directly utilize the heat source generated by the original factory equipment; nor can it adjust the intake concentration of the membrane separator based on the concentration feedback of the oxygen-enriched air output to the burner.

[0005] Further searching revealed that application number CN201620642311.2 discloses an energy-saving device for a vertical gas heat medium furnace (hereinafter referred to as the "energy-saving device"). The main equipment includes a W-type vacuum pump, a blower, an oxygen-enriched membrane assembly, an air preheating coil, an electric butterfly valve, a waste heat recovery coil, a finned heat exchange tube, a waste heat recovery induced draft fan, and a centrifugal fan. The device adopts secondary flue gas waste heat recovery and utilization technology and air oxygenation technology. On the one hand, the waste heat of the preheated flue gas is used to preheat the air, fuel, and materials. On the other hand, oxygen-enriched air is added to increase the temperature and oxygen content of the combustion-supporting air, which not only shortens the flame height, but also increases the combustion intensity, accelerates the combustion speed, and obtains better heat conduction. At the same time, the increase in flame temperature will be conducive to the complete combustion reaction and reduce the volume of flue gas exhaust, which has the effects of saving energy, improving thermal efficiency, and reducing pollutant emissions.

[0006] Since the “energy-saving device” discloses that the flue gas waste heat recovery equipment can be used to recover the flue gas heat and a large amount of water vapor latent heat to reduce the sulfur content of the exhaust flue gas, but the flue gas waste heat recovery equipment of the “energy-saving device” is connected to the burner and is used to recover the flue gas burned by the gas furnace. Even if the recovery of latent heat is disclosed, since the latent heat is not reprocessed, it cannot directly or indirectly provide a reference for the above-mentioned “cement rotary kiln oxygen-enriched combustion oxygen supply method and device” to utilize the heat source generated by the original factory equipment. Summary of the invention

[0007] The object of the present invention is to provide an energy-saving rotary kiln oxygen-enriched combustion system to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An energy-saving rotary kiln oxygen-enriched combustion system, comprising:

[0010] The original factory heat source is used to generate high-pressure steam;

[0011] The high-pressure steam is used to drive the steam turbine, thereby driving the centrifuge, so that the centrifuge generates hot air, and the generated hot air is used to provide sample gas for the high-pressure oxygen generation module after filtering, absorbing the residual heat and filtering again, and the heat in the hot air after filtering and absorbing the residual heat is recovered and used to generate high-pressure steam and to generate electricity for the power generation component;

[0012] The high-pressure oxygenation module is used to separate the sample gas into oxygen-rich gas and obtain oxygen-rich gas and nitrogen-rich gas respectively;

[0013] The nitrogen-rich gas is used to provide a driving gas source for gas-using equipment;

[0014] The oxygen-rich gas is used to provide combustion oxygen for the rotary kiln.

[0015] Preferably, the original factory heat source generates high-pressure steam through a waste heat boiler.

[0016] Preferably, the waste heat recovery includes: the heat in the hot air generated by the first two stages of the centrifuge is recovered to the waste heat boiler for power generation by the power generation component, and at the same time, the excess heat energy generated by the waste heat dryer is recovered and transported to the waste heat boiler for generating high-pressure steam to drive the steam turbine;

[0017] The hot air generated by the third stage of the centrifuge will be transported to the waste heat dryer to provide sample gas for the high-pressure oxygen injection module.

[0018] Preferably, the hot air generated by the first two stages of the centrifuge and the hot air generated by the third stage of the waste heat absorption dryer are both sent to the waste heat boiler through a heat exchanger.

[0019] Preferably, the hot air generated by the third stage of the centrifuge is filtered through filter group I and then enters the waste heat dryer. The hot air that has passed through the waste heat dryer is filtered again through filter group II and then used as sample gas.

[0020] Preferably, the power generation component is based on a steam turbine generator, which is connected to the waste heat boiler and the electrical equipment respectively.

[0021] Preferably, the high-pressure oxygen injection module will obtain oxygen-rich gas for Roots blower to absorb, a part of the oxygen-rich gas is sent to the tail of the rotary kiln through the kiln tail coal supply fan, and the remaining part is sent to the oxygen-enriched burner through the kiln head coal supply fan and the kiln head internal and external fans, and finally enters the kiln head of the rotary kiln.

[0022] Preferably, the air inlet end of the high-pressure oxygenation module is connected to a servo valve for adjusting the purity of the sample gas, and the servo valve adjusts the purity of the oxygen-rich gas output by the Roots blower through a pressure regulating valve. An adjustable vent valve II for exhausting excess oxygen-rich gas is connected to the pipeline between the high-pressure oxygenation module and the Roots blower.

[0023] Preferably, the Roots blower is connected to an oxygen-enriched pipeline.

[0024] Preferably, a flow meter II and an oxygen detector are installed on the oxygen-enriched pipeline, wherein the oxygen detector is used for detection feedback, and the servo valve is controlled to adjust the purity of the sample gas according to the detection feedback.

[0025] Preferably, the oxygen-enriched pipeline is used to transport oxygen-enriched gas, and is respectively connected to the kiln head coal supply fan, the kiln head internal and external fans, and the kiln tail coal supply fan. The oxygen-enriched burner has three channels, one channel is connected to the kiln head coal supply fan to transport combustion coal powder to the rotary kiln, and two channels are connected to the kiln head internal and external fans to transport pure gas to the rotary kiln. The gas and coal powder in each channel are mixed through the oxygen-enriched burner, sprayed into the rotary kiln and burned. The oxygen-enriched burner is installed at the kiln head of the rotary kiln, and the kiln tail coal supply fan is used to supply mixed oxygen-enriched gas and coal wind to the kiln tail of the rotary kiln.

[0026] Preferably, a flow meter and an adjustable vent valve I are installed on the pipeline between the nitrogen-rich gas and the gas-using equipment.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The steam turbine uses the high-pressure steam generated by the cement plant's original heat source as power to drive the centrifuge, which can replace the original centrifuge's electric motor. The energy conversion rate of the steam turbine directly driving the centrifuge is much higher than that of driving the generator to generate electricity and then drive the motor, thereby achieving the purpose of energy saving and consumption reduction.

[0029] The heat in the hot air generated by the first and second stages of the centrifuge is recovered by the waste heat recovery device and then input into the waste heat boiler. The hot air generated by the third stage of the centrifuge will be filtered through filter group I and then enter the waste heat dryer. The excess heat energy generated by the waste heat dryer will be transported to the waste heat boiler, and the waste heat boiler will then drive the steam turbine. In this way, the purpose of a cycle will be achieved, thereby saving energy and reducing consumption.

[0030] The main heat source of the waste heat boiler comes from the rotary kiln, grate cooler, decomposition furnace, etc. of the cement plant, which solves the problem that the original waste heat boiler is mainly used for power generation, but the power generation conversion rate is low, so the existing process cannot achieve a good energy-saving effect.

[0031] The high-pressure oxygen deoxidation membrane group produces nitrogen-rich and oxygen-rich gases. The nitrogen-rich gas is a high-pressure gas, which can be used for compressed air in the original workshop. This can better utilize the useful value generated by the energy consumption of this system and further save energy and reduce consumption.

[0032] The oxygen-rich gas is sprayed into the rotary kiln through the oxygen-rich burner, which can increase the oxygen content in the rotary kiln, so that the coal powder can be burned more fully in the kiln head of the rotary kiln, and the heat output can be higher, thus achieving the purpose of energy saving and consumption reduction; the oxygen-rich gas is mixed with the kiln tail coal supply air generated by the kiln tail coal supply fan, which can increase the oxygen content in the coal powder, so that the coal powder can be burned more fully in the kiln tail of the rotary kiln, and the heat output can be higher, thus achieving the purpose of energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a three-dimensional schematic diagram of the overall structure of the present invention;

[0034] In the figure: 1 steam turbine, 2 centrifuge, 3 filter group I, 4 waste heat dryer, 5 filter group II, 6 servo valve, 7 high-pressure oxygen production module, 8 high-pressure nitrogen-rich gas, 9 flow meter I, 10 regulating vent valve I, 11 gas-using equipment, 12 regulating vent valve II, 13 pressure regulating valve, 14 Roots blower, 15 flow meter II, 16 oxygen detector, 17 oxygen-enriched pipeline, 18 kiln head coal supply fan, 19 oxygen-enriched burner, 20 rotary kiln, kiln head internal and external fans 21, 22 kiln tail coal supply fan, 24 heat exchanger, 25 waste heat boiler, 26 steam turbine generator, 27 electrical equipment, 28 original factory heat source, 29 high-pressure steam. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example:

[0037] See also Figure 1 , the present invention provides a technical solution:

[0038] An energy-saving rotary kiln oxygen-enriched combustion system includes a steam turbine 1, a high-pressure oxygenation membrane group 7, and a rotary kiln 20. The original factory heat source 28 is sent to the waste heat boiler 25, and then high-pressure steam 29 is generated to drive the steam turbine 1. The steam turbine 1 is connected to the centrifuge 2, and the gas between the centrifuge 2 and the waste heat absorption dryer 4 is filtered through the filter group I3. The waste heat of the centrifuge 2 and the waste heat absorption dryer 4 is recovered and then sent to the heat exchanger 24, the heat exchanger 24 is connected to the waste heat boiler 25, and the waste heat boiler 25 is connected to the steam turbine generator 26 and the electrical equipment 27 in turn.

[0039] The gas between the waste heat absorption dryer 4 and the high-pressure oxygenation membrane group 7 is filtered through the filter group II 5. The high-pressure oxygenation membrane group 7 is connected to the Roots blower 14, and the Roots blower 14 is connected to the oxygen enrichment pipeline 17. The oxygen-enriched burner 19 is connected to the kiln head of the rotary kiln 20, and the kiln tail coal supply fan 22 is connected to the kiln tail of the rotary kiln 20.

[0040] The air inlet of the high-pressure oxygenation membrane group 7 is connected to a servo valve 6 which is an air suction regulating valve. The servo valve 6 is connected to the air outlet of the Roots blower 14 through a pressure regulating valve 13. The air outlet of the Roots blower 14 is sequentially installed with a flow meter II 15 and an oxygen detector 16 (i.e., the oxygen-enriched pipeline 17 near the Roots blower 14 is installed with a flow meter II 15 and an oxygen detector 16). The servo valve 6 and the oxygen detector 16 are controlled by a control system such as a PLC.

[0041] The nitrogen-rich gas 8 produced by the high-pressure oxygenation membrane group 7 is used to supply gas to the gas-using equipment 11, and a flow meter Ⅰ9 and a regulating vent valve Ⅰ10 are arranged on the pipeline between the nitrogen-rich gas 8 and the gas-using equipment 11.

[0042] 1. The steam turbine 1 uses the high-pressure steam generated by the original heat source of the cement plant as power to drive the centrifuge 2, which can replace the original motor of the centrifuge 2. The energy conversion rate of the steam turbine 1 directly driving the centrifuge 2 is much higher than that of driving the generator to generate electricity and then drive the motor, thereby achieving the purpose of energy saving and consumption reduction;

[0043] 2. The heat of the hot air generated by the first and second stages of centrifuge 2 is recovered by the waste heat recovery device and then input into the waste heat boiler 25. The hot air generated by the third stage of centrifuge 2 will be filtered through filter group Ⅰ3 and then sent to the waste heat dryer 4. The excess heat energy generated by the waste heat dryer 4 will be transported to the waste heat boiler 25, and the waste heat boiler 25 will then drive the steam turbine 1. In this way, the capacity will achieve the purpose of a cycle, thereby saving energy and reducing consumption. The waste heat dryer 4 changes the gas outlet temperature by changing the cooling water flow rate through the manual valve. The larger the opening of the manual valve, the larger the cooling water volume, and the lower the gas outlet temperature, which controls the inlet gas temperature of the membrane tube (i.e., the high-pressure oxygenation membrane group 7 described below). This can improve the working efficiency of the membrane tube, improve the oxygen enrichment purity, and extend the life of the membrane tube;

[0044] 3. The main heat source of the waste heat boiler 25 comes from the rotary kiln, grate cooler, decomposition furnace, etc. of the cement plant. The original waste heat boiler is mainly used for power generation. Due to the low power conversion rate, the existing process cannot achieve a good energy-saving effect;

[0045] 4. The high-pressure gas generated by the centrifuge 2 passes through the filter group I3, the waste heat absorption dryer 4 and the filter group II5 for water removal and filtration, and then enters the high-pressure oxygenation membrane group 7 for oxygen-enriched separation. The high-pressure oxygenation membrane group 7 is divided into an oxygen-enriched outlet and a nitrogen-enriched outlet. The gas discharged from the nitrogen-enriched outlet is a high-pressure nitrogen-enriched gas 8, which is a high-pressure gas. This gas can replace the compressed air of the original workshop (the air compressor that originally supplied the compressed air to the original workshop can be shut down accordingly). This can better utilize the useful value generated by the energy consumption of this system and further save energy and reduce consumption;

[0046] 5. The oxygen-enriched gas at normal pressure is directly sucked by the Roots blower 14, which can effectively avoid the pressure build-up at the oxygen-enriched outlet, thereby preventing the high-pressure oxygenation membrane group 7 from being damaged. If the system generates excess oxygen-enriched gas, it can be emptied through the adjustable vent valve II 12, and the venting volume can be adjusted;

[0047] 6. Roots blower 15 is used to absorb oxygen-enriched gas and then send it into oxygen-enriched pipeline 17. Flow meter II 15 and oxygen detector 16 are installed on the pipeline. If the oxygen-enriched gas terminal needs to use oxygen-enriched gas of different purities, the oxygen analyzer 16 can be used to detect and control the servo valve 6 to adjust the purity. The gas inhaled by the servo valve 6 is the gas produced by the centrifuge 2 and filtered after water removal. This gas (which is high-pressure gas, so a pressure regulating valve 13 is added to adjust the pressure of this gas so as to better mix it with the oxygen-enriched gas) is used to achieve the purpose of oxygen purity adjustment;

[0048] 7. The oxygen-enriched gas output in the oxygen-enriched pipeline 17 has two parts and is specifically divided into three routes. One route is sent to the oxygen-enriched burner 19 through the kiln head internal and external fans 21 (also called the kiln head clean air fan), which can increase the oxygen content in the oxygen-enriched burner 19 (entering the rotary kiln 20), so that the coal powder will burn more fully in the rotary kiln 20, and the heat production will be higher, which will achieve the purpose of energy saving and consumption reduction. One route is sent to the kiln head coal supply fan 18 and mixed with the kiln head coal supply air of the kiln head coal supply fan 18, which can increase the oxygen content in the coal powder, so that the coal powder will burn more fully in the kiln head of the rotary kiln 20, and the heat production will be higher, which will achieve the purpose of energy saving and consumption reduction. There is also one route that is mixed with the kiln tail coal supply air generated by the kiln tail coal supply fan 22, which can increase the oxygen content in the coal powder, so that the coal powder will burn more fully in the kiln tail of the rotary kiln 20, and the heat production will be higher, which will achieve the purpose of energy saving and consumption reduction.

[0049] The air generated by the kiln head internal and external fans 21 (or kiln head clean air fans) is mixed with the oxygen-enriched gas and mixed to the target controlled oxygen concentration to supply gas to the oxygen-enriched burner 19, thereby improving oxygen-enriched combustion efficiency and reducing the load of the oxygen-enriched pipeline 17 for gas supply.

[0050] The remaining parts of the present invention that are not described may be the same as the prior art, or are well-known technologies, or may be implemented by using the prior art, and will not be described in detail here.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An energy-saving rotary kiln oxygen-enriched combustion system, characterized in that: include: The original factory heat source (28) is used to generate high-pressure steam (29); The high-pressure steam (29) is used to drive the steam turbine (1), thereby driving the centrifuge (2), so that the centrifuge (2) generates hot air. The generated hot air is filtered, the residual heat is absorbed, and the generated hot air is filtered again to provide sample gas for the high-pressure oxygen production module (7). The heat in the generated hot air after filtering and the residual heat is absorbed is then recovered and used to generate high-pressure steam (29) and used for power generation by the power generation component; The high-pressure oxygen production module (7) is used to separate the sample gas into oxygen-rich gas and obtain oxygen-rich gas and nitrogen-rich gas (8) respectively; The nitrogen-rich gas (8) is used to provide a driving gas source for the gas-using equipment (11); The oxygen-rich gas is used to provide combustion oxygen for the rotary kiln (20); The original factory heat source (28) is passed through the waste heat boiler (25) to generate high-pressure steam (29), and the waste heat recovery includes: the heat in the hot air generated by the first two stages of the centrifuge (2) is recovered to the waste heat boiler (25) for use in the power generation component to generate electricity, and at the same time, the excess heat energy generated by the waste heat dryer (4) is recovered and transported to the waste heat boiler (25) for generating high-pressure steam (29) to drive the steam turbine (1); The hot air generated by the third stage of the centrifuge (2) is transported to the waste heat absorption dryer (4) to provide sample gas for the high-pressure oxygen production module (7); The high-pressure oxygenation module (7) obtains oxygen-enriched gas for absorption by the Roots blower (14), a portion of the oxygen-enriched gas is delivered to the kiln tail of the rotary kiln (20) through the kiln tail coal delivery blower (22), and the remaining portion is delivered to the oxygen-enriched burner (19) through the kiln head coal delivery blower (18) and the kiln head internal and external blowers (21), and finally enters the kiln head of the rotary kiln (20); The air inlet end of the high-pressure oxygenation module (7) is connected to a servo valve (6) for adjusting the purity of the sample gas. The servo valve (6) adjusts the purity of the oxygen-rich gas output by the Roots blower (14) through a pressure regulating valve (13). The pipeline between the high-pressure oxygenation module (7) and the Roots blower (14) is connected to an adjustable vent valve II (12) for exhausting excess oxygen-rich gas.

2. The energy-saving rotary kiln oxygen-enriched combustion system according to claim 1, characterized in that: The hot air generated by the first two stages of the centrifuge (2) and the hot air generated by the third stage of the waste heat absorption dryer (4) are both sent to the waste heat boiler (25) through the heat exchanger (24).

3. The energy-saving rotary kiln oxygen-enriched combustion system according to claim 1, characterized in that: The hot air generated by the third stage of the centrifuge (2) is filtered by the filter group I (3) and then enters the waste heat absorption dryer (4). The hot air that has passed through the waste heat absorption dryer (4) is filtered again by the filter group II (5) and then serves as the sample gas.

4. The energy-saving rotary kiln oxygen-enriched combustion system according to claim 1, characterized in that: The power generation component is based on a steam turbine generator (26), and the steam turbine generator (26) is respectively connected to a waste heat boiler (25) and an electrical device (27).

5. The energy-saving rotary kiln oxygen-enriched combustion system according to claim 1, characterized in that: The Roots blower (14) is connected to an oxygen-enriched pipeline (17). The oxygen-enriched pipeline (17) is used to transport oxygen-enriched gas and is respectively connected to a kiln head coal supply fan (18), a kiln head internal and external fans (21), and a kiln tail coal supply fan (22). The oxygen-enriched burner (19) has three channels, one channel is connected to the kiln head coal supply fan (18) to transport combustion pulverized coal to the rotary kiln (20), and two channels are connected to the kiln head internal and external fans (21) to transport pure gas to the rotary kiln (20). The gas and pulverized coal in each channel are mixed and sprayed into the rotary kiln (20) through the oxygen-enriched burner (19) and burned. The oxygen-enriched burner (19) is installed at the kiln head of the rotary kiln (20). The kiln tail coal supply fan (22) is used to supply the mixed oxygen-enriched gas and coal air to the kiln tail of the rotary kiln (20).

6. The energy-saving rotary kiln oxygen-enriched combustion system according to claim 5, characterized in that: The oxygen-enriched pipeline (17) is provided with a flow meter II (15) and an oxygen detector (16), wherein the oxygen detector (16) is used for detection feedback, and the servo valve (6) is controlled according to the detection feedback to adjust the purity of the sample gas.

7. The energy-saving rotary kiln oxygen-enriched combustion system according to claim 1, characterized in that: A flow meter (9) and a regulating vent valve I (10) are installed on the pipeline between the nitrogen-rich gas (8) and the gas-using equipment (11).

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