阅读说明：本技术 一种水泥回转窑富氧燃烧供氧方法及装置 (Oxygen supply method and device for oxygen-enriched combustion of rotary cement kiln ) 是由 陈奕璇 申广浩 王晨 顾修筑 谢东红 贾吉来 于 2021-02-28 设计创作，主要内容包括：本发明属于空气分离技术领域,具体为一种水泥回转窑富氧燃烧供氧方法及装置。本发明采用膜分离制氧技术有机耦合至原压缩空气供气设施上,将原压缩空气分离为两种气体：富氮和富氧；产生的富氮,直接替代原工厂的压缩空气需求,回收压缩能；产生的富氧,可送炉窑直接完全或部分替代原净风、煤风而进行富氧燃烧,回收风机的压缩能,并且因富氧燃烧取得额外的经济效益；还充分考虑到压缩空气使用的极端情况,采用备用压缩空气补偿回路进行流量补偿,总体上实现以压缩空气换氧气的供氧方案,极大的降低了氧气提取的能耗；本发明设备管理、维护成本低,没有安全隐患,是水泥厂富氧燃烧节能改造的首选方案。(The invention belongs to the technical field of air separation, and particularly relates to an oxygen supply method and device for oxygen-enriched combustion of a rotary cement kiln. The invention adopts the membrane separation oxygen production technology to organically couple to the original compressed air supply facility, and separates the original compressed air into two gases: rich in nitrogen and oxygen; the generated nitrogen-rich directly replaces the compressed air requirement of the original factory and recovers the compression energy; the generated oxygen enrichment can be sent to a furnace kiln to directly completely or partially replace the original clean air and coal air to carry out oxygen enrichment combustion, the compression energy of a fan is recovered, and additional economic benefit is obtained due to the oxygen enrichment combustion; the extreme condition of the use of the compressed air is fully considered, the standby compressed air compensation loop is adopted for flow compensation, the oxygen supply scheme of exchanging oxygen by the compressed air is realized on the whole, and the energy consumption of oxygen extraction is greatly reduced; the invention has low equipment management and maintenance cost and no potential safety hazard, and is a preferred scheme for oxygen-enriched combustion energy-saving reconstruction in cement plants.)

1. The utility model provides a rotary cement kiln oxygen boosting burning apparatus of oxygen supply which characterized in that specifically includes:

(1) at least one group of cut-off valves capable of cutting off the original compressed air circuit; at least a manual cut-off valve V01 and/or an automatic cut-off valve QDV02A are arranged in an air supply pipe network between access points A and B; when oxygen supply is carried out on site by adopting the Zhuang Zhi, compressed air is forced to flow from the air supply branch of A-C-B by cutting off the air supply pipe network;

(2) at least one group of cut-off valves capable of cutting off the gas supply branch circuits A-C-B; a manual cut-off valve V02 and/or an automatic cut-off valve QDV02B are arranged, when oxygen supply is needed on site by adopting the device, the manual cut-off valve V02 or the automatic cut-off valve QDV02B is opened to generate oxygen by cutting off the manual cut-off valve V01 or the automatic cut-off valve QDV02A, or when the original compressed air guarantee mode needs to be recovered to generate no oxygen, the manual cut-off valve V01 or the automatic cut-off valve QDV02A is opened by cutting off the manual cut-off valve V02 or the automatic cut-off valve QDV 02B;

(3) a raw material air pretreatment facility is arranged in an air supply branch of the A-C-B, and is used for intercepting dust, large liquid drops such as water/oil and the like and other particulate impurities contained in the air, then the air enters a rear-stage separation system, and the air is not matched when the cleanliness of compressed air matched on site is confirmed to meet the separation requirement;

(4) at least one membrane separator M01 is arranged in the air supply branch of A-C-B, after the gas is separated by the membrane, part of the gas is enriched with oxygen-poor and nitrogen-rich gas which is difficult to permeate, and then the gas is discharged out of the membrane separator from an outlet A1 at the detention side, and is sent to a node B through QDV03 and DXF01 which are arranged, nodes C, QDV04 and a cut-off valve V03, and is used for supplying original compressed air to a gas point, and the other part of the gas is permeated to the low pressure side, is enriched into oxygen-rich gas at the permeation side, is output from A2 and is sent to a:

the branch is at least provided with an automatic cut-off valve which is used for directly emptying the oxygen-enriched air when the system is tested and the like;

(5) a set of compressed air compensation system is also arranged at a nitrogen-rich gas output node C of the membrane separator, and comprises a compressed air machine AB02, an air pretreatment facility and a check valve DXF02 which are connected to the node C and can supply air to the original compressed air gas point compensation air supply by opening QDV04 and V03;

(6) the system comprises necessary control components to enable the system power equipment to operate, and control valves can be switched according to requirements;

wherein, A is a compressed air facility or an access point with a compressed air pretreatment device to an air supply pipe network; b is a port from a compressed air supply pipe network to a compressed air using point; c is a gathering point of a nitrogen-rich outlet of the membrane separation part and a compressed air compensation facility, and D is a gathering point of an oxygen-rich main pipe of an oxygen-rich outlet of the membrane separation part for emergency evacuation and respectively feeding into a kiln head combustion-supporting fan and a kiln tail combustion-supporting fan;

AB01, AB02 are compressed air facilities; a01, A02 and A03 are blowers, wherein A01 is a kiln head air purifying blower, A02 is a kiln head coal air blower, and A03 is a kiln tail coal air blower; v01, V02, Vn1, Vn2 are valves; DXF01, DXF02 are check valves; representative automatic regulating valves of QTV, including QTV01, QTV02, …, are automatic regulating valves; QDV denotes automatic control valves, including QDV01A, QDV01B, QDV02A, QDV02B, …, all automatic control valves; M01-M0N are membrane separators, wherein A0 is a raw material side inlet, namely an air inlet, of the membrane separator, A1 is a retentate gas outlet, namely an exhaust gas outlet, A2 is a negative pressure side outlet, namely a permeate side outlet, of the membrane separator, and an oxygen-enriched air outlet.

2. The oxygen-enriched combustion oxygen supply method for the rotary cement kiln based on the device of claim 1 is characterized in that nitrogen-enriched generated by a membrane separator is sent to an original compressed air pipe network through an air supply branch of A-C-B to replace original compressed air, and simultaneously:

after the flow is adjusted by the automatic adjusting valve, the flow is directly substituted for a clean air fan to provide oxygen-enriched clean air for the combustor, the original clean air fan is stopped, or a parallel air supply loop is formed with the clean air fan, the oxygen-enriched air and the air are mixed to a target control oxygen concentration and then provide oxygen-enriched air with lower oxygen concentration relative to the outlet oxygen concentration of the oxygen-enriched system for the combustor to carry out oxygen-enriched combustion supporting, wherein the oxygen concentration is 25% or less than 45% of the target control oxygen concentration;

after the flow is adjusted by an automatic adjusting valve, a parallel air supply loop is formed by the automatic adjusting valve and a kiln head coal air fan, the oxygen enrichment and the air are mixed to the target control oxygen concentration and then are replaced by coal conveying air, so that higher safety is ensured, and the target control oxygen concentration is less than or equal to 30%;

after the flow is adjusted by an automatic adjusting valve, a parallel air supply loop is formed by the automatic adjusting valve and a kiln tail coal air fan, the oxygen enrichment and the air are mixed to the target control oxygen concentration and then are replaced by coal conveying air, so that higher safety is ensured, and the target control oxygen concentration is less than or equal to 30%;

the oxygen enrichment formed in the process of large oxygen enrichment or discharge in the process of testing and the like is sent to the wind chamber of the rotary kiln grate cooler 1/2.

3. The oxycombustion oxygen supply method for rotary cement kiln as claimed in claim 2, wherein the nitrogen rich produced by the M01 membrane separator is sent to the original compressed air pipe network through the A-C-B air supply branch to replace the original compressed air, and the shortage part is compensated by AB02 arranged on the compressed air compensation loop received from the C point.

4. The rotary cement kiln oxygen-enriched combustion oxygen supply method as claimed in claim 2, wherein when the membrane separator is used for preparing oxygen-enriched and nitrogen-enriched air, compressed air is heated by a heater and then enters the membrane separator, and the heating temperature is 25-65 ℃.

5. The rotary cement kiln oxygen-enriched combustion oxygen supply method as claimed in claim 2, wherein the oxygen-enriched air produced by the membrane separator replaces the kiln head net air.

6. The rotary cement kiln oxygen-enriched combustion oxygen supply method as claimed in claim 2, wherein the oxygen-enriched air produced by the membrane separator replaces kiln head coal air, and the oxygen-enriched concentration of the entering coal air is not more than 30%.

7. The rotary cement kiln oxygen-enriched combustion oxygen supply method as claimed in claim 2, wherein the oxygen-enriched air produced by the membrane separator replaces the kiln tail coal air, and the oxygen-enriched concentration of the entering coal air is not more than 30%.

8. The rotary cement kiln oxygen-enriched combustion oxygen supply method as claimed in claim 2, wherein the pressure of a kiln combustion facility clean air fan and a coal air fan is combined, and the separation pressure ratio of the membrane separator is adjusted according to the actual required use pressure of a field matched compressed air device to meet the output required oxygen-enriched pressure.

9. An oxygen-enriched combustion oxygen supply method for a rotary cement kiln as claimed in claim 3, wherein when the membrane separation material of the membrane separator is a membrane separation material having an alpha value of 5-7, the separation pressure ratio established at both sides of the membrane is 4 or more.

Technical Field

The invention belongs to the technical field of air separation, and particularly relates to an oxygen supply method and device for oxygen-enriched combustion of a rotary cement kiln.

Background

Oxygen enrichment, and is widely applied to combustion supporting, energy saving and environmental protection of various fuel oil, fuel gas, coal-fired kilns (glass, cement and ceramics), various boilers, heating furnaces, incinerators, heat medium furnaces, hot blast furnaces, smelting furnaces, aircraft engines, ship engines and the like; the oxygen enrichment technology is applied to the fields of catalytic cracking, desulfurization, wastewater treatment, engine synergism, oxygen enrichment gas generation (coal) and various oxidation reactions, fermentation and the like to obtain better economic benefit; in addition, the oxygen enrichment is also widely applied to the aspects of medical care, large-scale oxygen enrichment ventilation, plateau oxygenation, aquaculture and the like, and relates to the fields of petrifaction, chemical engineering, medicine, light industry, electric power, building materials, metallurgy, coal, transportation, aquaculture, national defense military and the like.

The air contains about 21 percent of oxygen and 78 percent of nitrogen, and the method which is most widely adopted in industry in the method for extracting the oxygen-enriched air by taking the air as the raw material is a cryogenic rectification method and a pressure swing adsorption method, but the oxygen-enriched systems constructed by the two methods have the disadvantages of large investment, high energy consumption, complex technology, requirement of special personnel for operation and higher operation cost; further, there are also oxygen separation methods such as electrolytic methods and chemical methods, but since oxygen separation is achieved by consuming water and chemical raw materials, there are disadvantages in that raw material acquisition is not easy, energy consumption is high, manufacturing cost is high, and use cost is high, and the methods are unacceptable to industrial customers and are only used in some special cases.

The membrane oxygen-enriching technique is a new separation method developed gradually from the end of 70 years, and is characterized by that it utilizes the selective permeability difference of organic high-molecular dense film to nitrogen and oxygen, and when the pressure difference or pressure ratio is existed between two sides of said film, the gas with high permeation rate in the mixed gas, such as water vapour, hydrogen gas, helium gas, oxygen gas and carbon dioxide, can be permeated through the film and enriched into oxygen-enriched air at low-pressure side of said film (depending on the difference of oxygen-nitrogen separation coefficient of film material, single-stage separation can obtain oxygen-enriched gas with purity of about 23-60%), and the gas with relatively low permeation rate, such as nitrogen gas, argon gas, methane and carbon monoxide, etc. can be retained in the film and enriched into oxygen-poor (or nitrogen-rich) air The membrane separation method has a series of advantages, so that the membrane separation method can provide a relatively cheap and flexible on-site gas supply method for various energy consumption units, and is widely adopted.

Typically, as the oxygen-enriched combustion of a rotary kiln in a cement plant, it is known that the key to success or failure lies in how to supply oxygen at low cost, and effectively reduce the operation cost, maintenance cost and device manufacturing cost of an oxygen-enriched device, while with the research and development of membrane separation materials and the breakthrough of process technologies, the alpha (alpha) value of oxygen-nitrogen separation of organic membrane separation materials applied to air separation is mostly between 2 and 7, and oxygen with a purity of about 30 to 60% can be directly obtained from air under a certain pressure ratio, and the limit of cost control required above is reached by improving the separation coefficient of the membrane separation materials, further reducing the separation pressure ratio, improving the permeation amount, etc., and the challenge is difficult to continue, and especially in many occasions where compressed air resources are already available in the cement process production process, how to organically combine the compressed air supply with oxygen-enriched separation, the compressed air facilities matched with the raw cement process for deashing and clearing are fully utilized, the separation technology is utilized, the compressed air is utilized to obtain the rich oxygen at low cost, and simultaneously the generated rich nitrogen basically does not influence the gas demand of the original deashing and clearing, and the like, and the rich oxygen obtained at low cost can provide an additional oxidant for a rotary cement kiln to implement the technical improvement of the oxygen-enriched combustion to generate additional economic benefits, so that an efficient solution is urgently needed.

Disclosure of Invention

In view of the above circumstances, the present invention aims to provide an oxygen supply method and an oxygen supply device for the oxygen enrichment combustion of a rotary cement kiln, which are efficient, safe and low in cost.

The invention fully utilizes the on-site compressed air resources, obtains the oxygen-enriched air at low cost without influencing the specific guarantee purpose of the original compressed air and the requirements of oxygen-enriched purity and pressure required by the oxygen-enriched combustion process.

The oxygen-enriched combustion oxygen supply device of the rotary cement kiln, as shown in the attached figure 2, specifically comprises:

(1) at least one group of cut-off valves capable of cutting off the original compressed air circuit. At least one air supply pipe network from the access points A to B is provided with a manual cut-off valve V01 or an automatic cut-off valve QDV02A, preferably but not necessarily both; when the invention is needed to be adopted to implement on-site oxygen supply, the invention is used for cutting off the air supply pipe network to force compressed air to flow from the air supply branch of A-C-B;

(2) at least one group of cut-off valves capable of cutting off the gas supply branch circuits A-C-B. At least, for example, a manual cut-off valve V02 or an automatic cut-off valve QDV02B is arranged, preferably, but not necessarily, both of them are arranged, when oxygen supply on site needs to be implemented by adopting the invention, oxygen is generated by cutting off the manual cut-off valve V01 or the automatic cut-off valve QDV02A and opening the manual cut-off valve V02 or the automatic cut-off valve QDV02B, or the original compressed air guarantee mode needs to be recovered without generating oxygen, the manual cut-off valve V02 or the automatic cut-off valve QDV02B is cut off and the manual cut-off valve V01 or the automatic cut-off valve QDV02A is;

(3) preferably, but not necessarily, a raw air pre-treatment facility (not shown in the figure) is arranged in the branch of the air supply of the A-C-B, and is used for intercepting dust, large liquid drops such as water/oil and the like contained in the air, and the like, and then the liquid drops enter a rear-stage separation system, and the raw air pre-treatment facility can be not matched when the cleanness of the matched compressed air on site is confirmed to meet the separation requirement;

(4) at least one membrane separator M01 is arranged in the air supply branch of A-C-B, after the gas is separated by the membrane, part of the gas is enriched with oxygen-poor and nitrogen-rich gas which is difficult to permeate, and then the gas is discharged out of the membrane separator from an outlet A1 at the detention side, and is sent to a node B through QDV03 and DXF01 which are arranged, nodes C, QDV04 and a cut-off valve V03, and is used for supplying original compressed air to a gas point, and the other part of the gas is permeated to the low pressure side, is enriched into oxygen-rich gas at the permeation side, is output from A2 and is sent to a:

preferably, at least an automatic shut-off valve is arranged in the branch, so that the oxygen enrichment can be directly emptied to the atmosphere in the case of system test and the like;

(5) at a nitrogen-rich gas output node C of the membrane separator, the invention is also provided with a set of compressed air compensation system, and a compressed air machine AB02 determines whether necessary air pretreatment facilities (not marked in the figure) are matched or not according to the requirements of customers, a preferred but not necessary check valve DXF02 is connected to the node C, and the original compressed air gas point can be compensated and supplied with air by opening QDV04 and V03;

(6) as is known in the art, the system also includes the necessary control components to enable the operation of the system power plant, control valves to be switched as required, etc.

The oxygen-enriched combustion oxygen supply method of the rotary cement kiln based on the device sends the nitrogen-enriched generated by the membrane separator into the original compressed air pipe network through the air supply branch of A-C-B, replaces the original compressed air and simultaneously:

after the flow is adjusted by the automatic adjusting valve, the flow is preferably directly substituted for a clean air fan to provide oxygen-enriched clean air for the combustor, the original clean air fan is stopped, or a parallel air supply loop is formed with the clean air fan, the oxygen-enriched air and the air are mixed to a target control oxygen concentration and then provide oxygen-enriched air with lower oxygen concentration relative to the oxygen concentration at the outlet of the oxygen-enriched system for the combustor to carry out oxygen-enriched combustion supporting, wherein the oxygen concentration is less than or equal to 25% and less than or equal to 45% of the target control oxygen concentration, and meanwhile, energy is recovered due to the fact that the fan is stopped;

after the flow is adjusted by an automatic adjusting valve, a parallel air supply loop is preferably formed by the automatic adjusting valve and a kiln head coal air fan, the oxygen enrichment and the air are mixed to the target control oxygen concentration and then are replaced by coal conveying air, so that higher safety is ensured, the target control oxygen concentration is less than or equal to 30%, meanwhile, the operation load of the coal air fan is reduced, and energy is recovered;

after the flow is adjusted by an automatic adjusting valve, a parallel air supply loop is preferably formed by the automatic adjusting valve and a kiln tail coal air fan, the oxygen enrichment and the air are mixed to the target control oxygen concentration and then are replaced by coal conveying air, so that higher safety is ensured, the target control oxygen concentration is less than or equal to 30%, meanwhile, the operation load of the coal air fan is reduced, and energy is recovered;

the oxygen enrichment formed when the oxygen enrichment is large or during the discharge of the test process is sent to the wind chamber of the rotary kiln grate cooler 1/2.

In addition, nitrogen enrichment generated by the M01 membrane separator is sent to the original compressed air pipe network through the air supply branch A-C-B to replace the original compressed air, and the insufficient part compensates AB02 arranged on a compressed air compensation loop received from a point C.

In the process of preparing oxygen-rich and nitrogen-rich by using the membrane separator, compressed air is preferably heated by a heater (not shown in the figure) and then enters the membrane separator, typically, the air can be heated to 25-65 ℃, and although the oxygen-rich purity is slightly reduced at a higher temperature, the investment of the membrane separator can be greatly reduced;

the oxygen enrichment produced by the membrane separator preferably replaces the kiln head net air, so that higher energy-saving rate can be achieved, and typically, the oxygen enrichment is completely replaced according to the total amount of the net air.

Further, the kiln head coal air is preferably replaced, typically, the total amount of the residual oxygen enrichment is used for replacing the coal air, but the oxygen enrichment concentration of the coal air is not more than 30 percent, so that the oxygen supply safety is ensured, and the higher energy saving rate can be obtained.

And further, the kiln tail coal air is preferably replaced, the residual oxygen enrichment further replaces the kiln tail coal air, but the oxygen enrichment concentration of the coal air is not more than 30 percent, so that the oxygen supply safety is ensured, and the higher energy saving rate can be obtained.

And furthermore, the surplus oxygen and the oxygen enriched in the test process enter an air chamber of the grate cooler 1/2, so that waste is avoided, and higher energy saving rate can be obtained.

The oxygen enrichment is adjusted according to the known technology, the pressure loss of a conveying pipe network is overcome around the conveying pressure of the backpressure to the minimum requirement, the pressure requirement required by the original fan air supply is met, the material and the diameter of the required oxygen enrichment pipeline can be designed according to the known technology, the pressure bearing requirement of the conveying pressure is typically met, and the conveying flow speed is designed according to 4-16 m/s so as to calculate the pressure drop.

In the device, A is a compressed air facility (or a compressed air pretreatment device) to an air supply pipe network access point; b is a port from a compressed air supply pipe network to a compressed air using point; c is a summary point of a nitrogen-rich outlet of the membrane separation part and a compressed air compensation facility; d is an oxygen enrichment header collecting point for emergency evacuation of an oxygen enrichment outlet end of the membrane separation part and respectively feeding the oxygen enrichment outlet end into a kiln head combustion-supporting fan and a kiln tail combustion-supporting fan.

AB01, AB02, which is a compressed air facility, can be various types of compression devices, such as piston type, centrifugal type, screw rod, vortex type, roots type, liquid ring type, etc., and can boost the pressure of the gas to a proper pressure, wherein AB01 is an original compressed air facility for boosting the pressure of the gas to a certain pressure, and is provided with an air pre-treatment facility (not shown in the figure), AB02 is a compressed air compensation facility, and is provided with an air pre-treatment facility (not shown in the figure) for compensating for insufficient pressure at the air end;

a01, a02, a03, which is a blower, and can be various blower devices, such as centrifugal type, screw rod, vortex, roots, liquid ring, gas suspension and other compression types, and can boost the gas to a proper pressure, in the figure, a01 is a kiln head air purification blower for boosting the air to a certain pressure to provide air purification (including external air and internal air, or called axial flow air and rotational flow air, and also can be divided into separate external air and internal air blowers) for the burner, a02 is a kiln head coal air blower for boosting the air to a certain pressure to provide coal conveying air for the fuel supply of the kiln head burner, and a03 is a kiln tail coal air blower for boosting the air to a certain pressure to provide coal conveying air for the kiln tail fuel supply;

v01, V02, Vn1 and Vn2 are valves, which can be various manual valves, such as various ball valves, stop valves, butterfly valves, gate valves, etc., used for cutting off and adjusting fluid, and of course, can be modified into automatic valves, such as pneumatic, electric and hydraulic control automatic valves;

DXF01, DXF02, are check valves that may be of various forms for fluid backflow shutoff;

the representative automatic regulating valves marked with automatic regulating valve or QTV, such as QTV01, QTV02, and the like, are automatic regulating valves which can be opened or closed from 0% to 100% according to preset logic, and the valves can be pneumatically controlled or electric or hydraulic controlled automatic valves;

the automatic shut-off valve or marker QDV represents an automatic control valve, such as QDV01A, QDV01B, QDV02A, QDV02B, etc., which are all automatic control valves that can be opened or closed according to a preset logic, and these valves can be pneumatic controlled or electric or hydraulic controlled automatic valves;

M01-M0N are membrane separators which can be plate membranes, spiral membranes and hollow fiber membranes, wherein A0 is a raw material side inlet of the membrane separator, namely an air inlet, A1 is a retentate gas outlet, namely an exhaust gas discharge port, A2 is a negative pressure side of the membrane separator, namely a permeate side outlet, and an oxygen-enriched air outlet.

The separation coefficient referred to herein, such as the oxygen-nitrogen separation coefficient, is generally defined as:

alpha (alpha) value, oxygen-nitrogen separation coefficient ═ Q_N2/Q_O2)

In the formula Q_N2And Q_O2The permeation quantities of pure components nitrogen and oxygen through a specific membrane material per unit time and pressure, respectively.

The invention is different from the prior art, such as the independent membrane separation process or the separation process of other technologies (such as pressure swing adsorption and cryogenic air separation technology) for supplying oxygen on site (the technologies can only supply oxygen enrichment to the kiln), but adopts the membrane separation oxygen production technology to be organically coupled to the original compressed air supply facility to separate the original compressed air (usually 0.6-1.3 MPa) into two gases, wherein, the generated nitrogen-rich can directly replace the compressed air requirement (usually only 0.5MPa) of the original factory due to higher pressure, and the compression energy is recovered, the generated rich oxygen can be sent to a furnace kiln to directly completely or partially replace the original clean air and coal air for oxygen-enriched combustion due to higher pressure (generally, 20-100 kpa), thereby not only recovering the compression energy of a fan, and additional economic benefit can be obtained due to oxygen-enriched combustion, so that the deep energy-saving excavation potential scheme is combined with the process of a cement plant.

The invention fully utilizes compressed air resources, particularly utilizes the nitrogen as a byproduct after the compressed air is used for preparing oxygen, and the nitrogen-rich gas is returned to a compressed air pipe network for use at a gas using point, generally, the nitrogen-rich gas as the byproduct only contains the nitrogen-rich gas (generally, 90-99 percent of nitrogen) and does not influence the purposes of original compressed air such as purging and the like, and in addition, the pressure loss after membrane separation is only-0.05 MPa, and generally does not influence the use at the gas using point.

The invention also fully considers the extreme condition of the use of the compressed air, typically, when the coupling process is adopted for supplying oxygen, if the extracted oxygen-enriched quantity is large, and the supply flow of the compressed air is insufficient, a spare compressed air compensation loop can be adopted for flow compensation, the nitrogen-enriched air generated by the oxygen supply of the membrane separation process and the compressed air sent into a pipe network by the compressed air flow compensation loop can jointly meet the original compressed air requirement until the specific guarantee task of the original compressed air is not influenced, and the oxygen-enriched air generated by the membrane separation oxygen supply loop can be supplied to occasions such as oxygen-enriched combustion, oxygen-enriched vaporization, oxygen-enriched ventilation and the like at low cost, so that the oxygen supply scheme of exchanging the oxygen by the compressed air is realized on the whole, and the energy consumption of oxygen extraction is greatly reduced.

In addition, the invention also fully combines the cement clinker calcining process, and particularly, a clean air fan and a coal air fan with air pressure of 20-100 kpa are matched in a clinker calcining thermal facility of a cement plant, the oxygen-enriched residual pressure prepared by compressed air can completely or partially replace the original clean air and coal air, the operation is stopped or the operation frequency of the original air fan is reduced, and the compression energy of the air fan can be recovered.

Moreover, the scheme of the invention adopts the oxygen-enriched combustion solution that the membrane separation oxygen generation technology is organically coupled to the original compressed air supply facility and the clinker calcining facility of the factory, so that the oxygen generation cost can be reduced to the maximum extent, and simultaneously, the oxygen-enriched combustion can be carried out:

(1) the burnout rate of the fuel is improved;

(2) the heating rate is increased, the heat transfer efficiency of flame in the furnace is improved, and the heat utilization rate is increased;

(3) the heat loss of fuel is reduced, the coefficient of excess air is reduced, and the heat efficiency is improved;

(4) the ignition temperature of the fuel is reduced, and a wider fuel selection range is obtained;

the method has the advantages of obtaining energy-saving benefits, along with short construction period and low equipment management and maintenance cost, and also has no potential safety hazard caused by high-purity oxygen-enriched mixing, and particularly has low operation energy consumption of oxygen production, thus being a preferred scheme for oxygen-enriched combustion energy-saving reconstruction in cement plants.

Drawings

FIG. 1 is a schematic view of an original compressed air supply system.

FIG. 2 is a schematic diagram of the oxygen supply device for the oxygen-enriched combustion of the rotary cement kiln.

Detailed Description

The invention is further described below with reference to the accompanying drawings and examples.

FIG. 2 is a schematic structural view of an oxygen supply device for oxyfuel combustion in a rotary cement kiln according to the present invention.

Generally, in the membrane separation process for separating oxygen from air, the purity of oxygen obtained by membrane separation is related to the oxygen-nitrogen separation coefficient (called alpha value) of membrane separation material, the absolute pressure ratio of the positive pressure side and the negative pressure side of the membrane separator (called separation pressure ratio) of gas passing through the membrane separator and the ratio of raw gas and oxygen-enriched product gas (called air-oxygen ratio), and the higher oxygen-nitrogen separation coefficient is related to the separation of oxygen-enriched gas at lower separation pressure ratio and smaller air-oxygen ratio On the other hand, the flow rate of the rich oxygen obtained by membrane separation, namely the permeation quantity of the membrane separation material, is mainly related to the temperature and the pressure of the raw material gas, and the higher the separation temperature is, the larger the permeation quantity is, the higher the separation pressure is, the larger the permeation quantity is.

In the present invention, it is preferable to perform oxygen-nitrogen separation using, for example, a hollow fiber membrane, and in order to improve the separation efficiency, reduce the cost, and improve the separation pressure on both sides of the membrane than the pressure obviously limited by the pressure of the compressed air set in the field, and to reduce the pressure loss as much as possible, typically, when the hollow fiber membrane separator made of the membrane separation material with the alpha value of the separation material of 5-7 is used for separation, when the required oxygen-enriched purity is 30-60%, the separation pressure ratio of two sides of the membrane is about to be established to be more than 4, that is, if the positive pressure side pressure of the film is 300 to 1300KPa, the absolute pressure is the atmospheric pressure (101.325KPa) + (400 to 1300KPa), the negative pressure side or the permeation side only needs to keep atmospheric pressure discharge (equivalent to a vacuum degree of 0KPa gauge pressure), so that the separation pressure ratio is (101.325 + (300-1300 KPa))/101.325 ≡ 4-14 times, and about 30-60% of oxygen-enriched purity can be obtained. Obviously, in the process, the pressure of the clean air fan and the coal air fan of the kiln combustion facility is combined, and the separation pressure ratio can be adjusted according to the actually required use pressure of the field matched compressed air equipment so as to meet the oxygen-enriched pressure required by output.

During air supply, compressed air is cut off due to the circulation of A-B by means of an arranged means or an automatic valve, the compressed air ensures that air is supplied from A-C-B, and oxygen is output from a point D to be required target oxygen-enriched air:

(1) after the original matched compressed air facility on site, at least a manual cut-off valve V01 or an automatic cut-off valve QDV02A, preferably but not necessarily both, are arranged in the air supply pipe network between the access points A and B, and when oxygen supply on site needs to be implemented by adopting the invention, the requirement of the compressed air use point is ensured by cutting off the air supply pipe network, so that the compressed air forcibly flows from the air supply branch of the A-C-B (generally, the compressed air becomes nitrogen-rich gas only after passing through a membrane separator, the pressure is slightly reduced due to the pressure loss of a front-section conveying pipeline and equipment, and the original purpose of the compressed air is not influenced), and the oxygen is output from the D point to be the required target oxygen-rich air through the outlet of the membrane separator.

(2) At least one of a manual cut-off valve V02 and an automatic cut-off valve QDV02B, preferably but not necessarily both, is arranged in the air supply branch of A-C-B, and is used for opening the manual cut-off valve V02 or the automatic cut-off valve QDV02B for oxygen generation by cutting off the manual cut-off valve V01 or the automatic cut-off valve QDV02A when oxygen supply is required on site by adopting the invention, or opening the manual cut-off valve V01 or the automatic cut-off valve QDV02A by cutting off the manual cut-off valve V02 or the automatic cut-off valve QDV02B for oxygen generation when the original compressed air guarantee mode is required to be recovered;

when the valve is switched to oxygen production, compressed air is forced to flow from the air supply branch of A-C-B, preferably but not necessarily, an air pretreatment facility is arranged, dust, large liquid drops such as water/oil and the like contained in the air are intercepted and then enter a rear-stage separation system, and the compressed air cannot be matched when the cleanness of matched compressed air on site is confirmed to meet the separation requirement.

(3) At least a membrane separator M01 is arranged in the air supply branch of A-C-B, when the valve is switched to oxygen production, the gas is separated by the membrane:

part of the oxygen-poor nitrogen-rich gas which is enriched with difficult permeation is discharged out of the membrane separator from an outlet A1 at the detention side, and QDV03 and DXF01 are arranged and sent to a node B through nodes C and QDV04 and a shut-off valve V03 to supply a gas point for the original compressed air;

part of the oxygen permeates to the low-pressure side, the permeation side is enriched into oxygen rich and the oxygen rich oxygen is output from A2, and after passing through a node D:

an automatic cut-off valve can be arranged to directly exhaust the rich oxygen to the atmosphere under the conditions of system test and the like;

after the flow is adjusted by the automatic adjusting valve, the flow is preferably directly substituted for a clean air fan to provide oxygen-enriched clean air for the combustor, the original clean air fan stops running, but a parallel air supply loop can also be formed with the clean air fan, the oxygen-enriched air and the air are mixed to the target oxygen control concentration and then provide oxygen-enriched air with lower oxygen concentration relative to the outlet oxygen concentration of the oxygen-enriched system for oxygen-enriched combustion supporting, the preferred oxygen-enriched air concentration is more than or equal to 25% and less than or equal to 45% of the target oxygen control concentration, and meanwhile, the energy is recovered due to the fact that the fan is stopped running or the running load of;

after the flow is adjusted by the automatic adjusting valve, a parallel air supply loop is preferably formed by the automatic adjusting valve and the kiln head coal air fan, the oxygen enrichment and the air are mixed to the target control oxygen concentration and then are replaced by coal conveying air, so that higher safety is ensured, the preferred target control oxygen concentration is less than or equal to 30%, meanwhile, the operation load of the coal air fan is reduced, and energy is recovered;

after the flow is adjusted by the automatic adjusting valve, a parallel air supply loop is preferably formed by the automatic adjusting valve and the kiln tail coal air fan, the oxygen enrichment and the air are mixed to the target control oxygen concentration and then are replaced by coal conveying air, so that higher safety is ensured, the preferred target control oxygen concentration is less than or equal to 30%, meanwhile, the operation load of the coal air fan is reduced, and energy is recovered;

the oxygen enrichment formed in the process of discharging when the oxygen enrichment amount is large or in the process of testing and the like can be sent to the wind chamber of the grate cooler 1/2 of the rotary kiln.

(4) When the oxygen enrichment output from the D through the membrane separator reaches a certain flow rate, such as the guarantee supply of the compressed air is influenced, the invention is also provided with a set of compressed air compensation system, the compressed air machine AB02 determines whether to be matched with a necessary air pretreatment facility (not shown in the figure), preferably but not necessary check valve DXF02 to be connected to the C point according to the requirements of customers, and the original compressed air use point can be compensated and supplied with the air through opening QDV04 and V03;

by the above transformation of the original compressed air supply facility through the coupling membrane separator, the method can continuously and stably obtain the oxygen-enriched air and simultaneously ensure the supply of the field compressed air and oxygen. Moreover, by fully recovering the on-site compressed air and combining with the membrane separation process, the nitrogen-rich gas in oxygen generation is recovered, the requirements of on-site compressed air and oxygen enrichment are met at relatively low running cost, the stability of the system is enhanced, the cost is reduced, and the total efficiency of the system is improved.

In the invention, the air component membrane separation process provides oxidant for oxygen-enriched combustion supporting of the kiln, but the basic principle of the invention can be used in many other separation occasions. Typical examples of separations that can be achieved by the present invention include oxygen/nitrogen separations, gas drying, carbon dioxide/methane separations, carbon dioxide/nitrogen separations, hydrogen/nitrogen separations, and olefin/alkane separations, among others.

Example 1

In a certain cement plant, the local altitude is 1008m, the clinker yield is 4050TPD, the high-quality fire coal with the combustion heat value of about 5800-6000 kcal/kg is about 21.5T/h, the average electricity price is 0.48 yuan/KWH, the average coal price is 780 yuan/ton, the coal powder processing cost is 30 yuan/ton, the benefit of increasing 1 ton of clinker is 70 yuan each time, and the annual running time is 310 days.

The factory is matched with 3 units of 355KW and 62m of exhaust gas volume³Min, outlet pressure 1.0MPa, total displacement 3 x 62 ═ 186m³Min, compressed air is mainly supplied for the requirements of ash removal, blockage removal and the like, the normal use pressure of an air point is about 0.6MPa, and the actual use air quantity is about 136m³/min。

According to the method, the membrane separation oxygen production technology is organically coupled to the original compressed air supply facility, the compressed air and the oxygen are supplied on site at the same time, the compressed air meets the use pressure requirement of 0.6MPa, the components are not required, and the oxygen is used for oxygen-enriched combustion in the cement plant, so that the coal saving benefit of about 5-10% is obtained compared with the original technology.

Produced by Shanghai Hui fir actual industry GmbHThe membrane separator, which constructs a separation system according to the flow shown in figure 2 of the invention, has a design working pressure of 0.9MPa, a pressure loss of about 0.06MPa in the membrane separation process and a design working temperature of normal temperature, which is knownThe air-oxygen ratio of 38-40% oxygen-enriched air prepared by the membrane separator is about 2.55, and the air-oxygen ratio is 186m by process simulation calculation³The practical extraction concentration of the compressed air per minute is about 73m of oxygen-enriched air with 38-40 percent³Min, at the same time, will yield 113m³Nitrogen-enriched air/min (pressure reduced by only 0.05 MPa).

(1) The prepared nitrogen-rich can completely replace the requirement of the original compressed air station, and the energy can be recycled

Generally, oxygen generation all needs to consume the air that is many times the oxygen volume, and oxygen generation energy resource consumption is high, and the rich nitrogen of preparing when this scheme make full use of system preparation oxygen can be used to replace the gas demands such as deashing, clear stifled of general former compressed air station, can reduce the oxygen generation cost, and in the present case, supporting 3 compressed air equipment can extract about 4380m altogether³H oxygen enrichment of about 38% oxygen concentration while producing 0.85MPa of about 113m³The nitrogen-enriched air is produced by 0.85MPa, the total assembly power of 3 compressed air equipment is about 1065KW and the generated power is about 113m³The nitrogen-rich air is measured by factory, and the actual use of the original compressed air is about 136m³Min, actual use pressure of only 0.6MPa (600kpa gauge), about 113m of nitrogen will be enriched³The air supply system is used for replacing the original compressed air station and only needs to be additionally matched with air supply flow of about 23m³The equivalent power can be recovered by a compressor of/min, which can be calculated according to the common air compression to the use pressure of 0.60MPa, about 641.14KW, and the table is calculated as follows:

(2) the total amount of the prepared rich oxygen is about 73m³Min, purity of 38-40%, returning to rotary kiln for oxygen enrichmentCombustion, partially replacing net wind (replacing the finished oxygen-enriched concentration overall control target by 35%), partially replacing kiln head coal wind (replacing the finished oxygen-enriched concentration overall control target by 29%), and partially replacing kiln tail coal wind (replacing the finished oxygen-enriched concentration overall control target by 23%), wherein:

1) the prepared oxygen enrichment forms a parallel air supply loop with the original air purifying fan due to the pressure of not less than 80kpa, and is mixed and then fed into 35% of oxygen enrichment air for oxygen enrichment combustion supporting, so that energy is saved;

the original pure air is replaced by the oxygen-enriched part, the oxygen-enriched part is connected with the original pure air fan in parallel for supplying air, the target oxygen-enriched concentration is controlled to be 35% after the air is mixed, and the original pure air fan reduces the load and recovers the energy because the oxygen-enriched part is replaced by the oxygen-enriched part at least, so that the installed power can be saved by about 52.53 KW;

installed power of fan	75	75		KW
						Alternative air volume	1928.27	1928.27		m3/hr.	82.4％
Total wind rate of original fan	2340	2340		m3/hr.
						Folding back to harvest energy	52.53	52.53		KW	Push-type flowmeter

。

2) The prepared oxygen enrichment forms a parallel air supply loop with an original kiln head fan due to the pressure of not less than 80kpa, and 29% of oxygen enrichment air is fed to perform oxygen enrichment combustion supporting after mixing, so that energy is saved.

The oxygen-enriched air is used for replacing the raw coal air, the target oxygen-enriched concentration of the coal conveying air is limited not to exceed 30% in order to ensure safety, the oxygen-enriched air and the raw coal air fan are designed to be connected in parallel for supplying air and blended to the oxygen concentration not exceeding 29%, and the raw coal air fan reduces the load due to the fact that the oxygen-enriched air is at least partially replaced, and the installed power can be saved by 28.45KW

Installed power of fan	75	75		KW
						Alternative air volume	1660	1660		m3/hr.	44.6％
Total wind rate of original fan	3720	3720		m3/hr.
						Folding back to harvest energy	28.45	28.45		KW	Push-type flowmeter

。

3) The prepared oxygen enrichment forms a parallel air supply loop with an original kiln tail air blower due to the pressure of not less than 80kpa, and 23% of oxygen enrichment air is fed to perform oxygen enrichment combustion supporting after mixing, so that energy is saved.

The oxygen-enriched part replaces the raw coal air, the target oxygen-enriched concentration of the coal conveying air is limited not to exceed 30% in order to ensure safety, the oxygen-enriched air and the raw coal air fan are designed to be connected in parallel for supplying air and mixed to the oxygen concentration not exceeding 23%, and the raw coal air fan reduces the load due to the fact that the oxygen-enriched air is at least partially replaced, and the installed power can be saved by 7.27KW approximately

To sum up, through this scheme, the summary of measuring and calculating of total power consumption and the energy recovery condition of compressed air system is as follows:

as above, the actual net energy consumption is only 205.57KW, namely 4380m is prepared³/hr(73m³Min) oxygen-enriched air, the unit consumption of oxygen-enriched air is only 0.047KW/m³The electric power required for preparing the oxygen-enriched air with the same scale by adopting a pressure swing adsorption and cryogenic air separation method is usually far more than 500 KW;

moreover, based on the oxygen-enriched combustion improvement of the scheme, the economic benefits of the following measuring and calculating list can be generated

The investment recovery period is short, and the economic benefit is remarkable.

The above-described embodiments illustrate only some of the essential features of the invention, and it will be appreciated by those skilled in the art that although the invention has been described in part in connection with the accompanying drawings, this is merely an example of an application or method of the invention, and that all other variations which do not depart from the essence of this patent are intended to be within the scope of this patent, which is limited only by the scope of the appended claims.

The above-mentioned contents of the present invention are further described in detail by the embodiments, but it should not be understood that the scope of the above-mentioned subject matter of the present invention is limited to the above-mentioned coupled examples, and the technologies realized based on the above-mentioned contents of the present invention are within the scope of the present invention.