WO2020258636A1

WO2020258636A1 - Sleeve kiln using natural gas as fuel

Info

Publication number: WO2020258636A1
Application number: PCT/CN2019/115501
Authority: WO
Inventors: 唐丹; 张林进; 黄黾; 薛建军; 满毅
Original assignee: 江苏中圣园科技股份有限公司
Priority date: 2019-06-28
Filing date: 2019-11-05
Publication date: 2020-12-30
Also published as: CN210367457U

Abstract

A sleeve kiln using natural gas as a fuel, comprising: a kiln body (1), an upper inner sleeve (2), a lower inner sleeve (3), an upper combustion chamber (4) and a lower combustion chamber (5), the lower inner sleeve (3) is provided with a cooling air outlet (301), the upper combustion chamber (4) and the lower combustion chamber (5) are respectively provided with burners (10), an upper part of the kiln body (1) is provided with a flue gas outlet, and the flue gas outlet is in communication with a flue of a chimney (9) by means of a flue gas treatment system, an outer side of the kiln body (1) is surrounded by a cooling air ring pipe (6), a mixing ring pipe (7) and a distribution ring pipe (8), a cooling ring pipe inlet is in communication with the cooling air outlet (301), a cooling ring pipe outlet is in communication with the mixing ring pipe (7), and the mixing ring pipe (7) is in communication with the flue of the chimney (9). Flue gas is mixed with cooling air in the mixing ring pipe (7), and is then distributed into the burners (10) by means of the distribution ring pipe (8). The described structure implements flue gas reflux and increases the concentration of CO₂ in the flue gas. A mixed gas having low oxygen content replaces an original cooling air. More gas is added into the upper combustion chamber during a low-oxygen combustion process. Under a condition of the same air coefficient, the temperature of the upper combustion chamber is effectively reduced and the generation of NO_x is reduced.

Description

Sleeve kiln using natural gas as fuel

Technical field

The invention relates to a sleeve kiln, in particular to a sleeve kiln using natural gas as fuel.

Background technique

Sleeve kiln usually uses carbon-containing energy such as coal gas and coal as fuel, and its flue gas contains a large amount of CO ₂ , and the emission of CO ₂ will bring about the greenhouse effect and other problems, which has attracted widespread attention. But the high cost flue gas CO ₂ recovering CO _2, particularly when low CO ₂ concentration in the flue gas, CO2 capture and recovery is difficult for an expand, further increasing the difficulty and cost of CO ₂ capture recovery. Among them, the sleeve kiln using natural gas as fuel contains hydrogen in natural gas, which makes the CO _{2 in} the flue gas relatively low, which increases the difficulty of CO ₂ capture and the cost of CO ₂ recovery. With the improvement of environmental protection standards, the pollutant emission standards have also been correspondingly improved, and the emission standards will be further improved with the environmental protection situation. In addition, the recovered CO _{2 has} a wide range of uses, such as soda production, smelting, oil displacement, food and other fields, and has certain economic value.

Therefore, further increasing the CO ₂ concentration in the exhaust flue gas of a sleeve kiln using natural gas as fuel is of great significance to facilitate CO ₂ capture and reduce recovery costs, as well as to bring economic, social and environmental benefits.

Chinese invention patent CN208320222U discloses a lime kiln flue gas recirculation system, which includes a sleeve kiln, an exhaust gas discharge system and a flue gas treatment device. The sleeve kiln is provided with a flue gas outlet and a recirculation flue gas inlet, the flue gas outlet is located at the upper part of the sleeve kiln, and the recirculation flue gas inlet is located at the recirculation flue gas inlet pipe at the lower part of the cooling zone. The above-mentioned patent realizes the recycling of flue gas and can increase the CO ₂ concentration in the flue gas. But taking a 500t sleeve kiln with a gas calorific value of 1300kCal/Nm ³ as an example, the combustion air for fuel combustion mainly comes from lime cooling air, primary combustion air (inner sleeve cooling air) and driving air, of which lime cooling air is about 5000～7000Nm ³ /h, the primary combustion air is about 2000-2500Nm ³ /h, the driving wind is about 6000-7000Nm ³ /h, and the lime cooling air accounts for about 40%. In the patent, the flue gas is completely replaced by air as the lime cooling air. When the air volume (meeting the need for lime cooling) is basically the same, the amount of oxygen entering the kiln is greatly reduced, and it is difficult to meet the oxygen demand for fuel combustion. At the same time, the above-mentioned patents need to cool the flue gas to ambient temperature to meet the demand for cooling, which increases the equipment investment cost.

Summary of the invention

The purpose of the present invention is to provide a sleeve kiln that uses natural gas as fuel, optimizes the structure of the sleeve kiln, and solves how to increase the CO ₂ concentration in the exhaust gas of the sleeve kiln fueled by natural gas, thereby realizing efficient recovery and utilization of CO ₂ questions.

The technical solutions adopted by the present invention to achieve the above-mentioned objectives are:

A sleeve kiln using natural gas as fuel, comprising a kiln body, an upper inner sleeve, a lower inner sleeve, an upper combustion chamber and a lower combustion chamber, the lower inner sleeve is provided with a cooling air outlet, and the upper combustion chamber And the lower combustion chamber are respectively provided with burners, the upper part of the kiln body is provided with a flue gas outlet, the flue gas outlet is communicated with the flue of the chimney through the flue gas treatment system, and the outside of the kiln body is respectively surrounded by cooling air The cooling air ring is provided with a plurality of first cooling air inlets corresponding to the cooling air outlets, and the first cooling air inlets are in one-to-one correspondence with the cooling air outlets, so The cooling air loop is provided with a first cooling air outlet; the mixing loop is provided with a first mixed air inlet and a first mixed air outlet, and the first mixed air inlet includes a second cooling air inlet and A flue gas inlet, the second cooling air inlet is in communication with the first cooling air outlet, the flue gas inlet is in communication with the flue of the chimney; a second mixed gas inlet is provided on the distribution ring, and the first mixed gas The outlet is in communication with the second mixed gas inlet; a plurality of second mixed gas outlets are provided on the distribution ring corresponding to the burner, and the second mixed gas outlets are connected with the burner in a one-to-one correspondence.

On the outside of the sleeve kiln, a mixing ring and a distribution ring are added to the original cooling air ring, which realizes the flue gas recirculation process, increases the CO ₂ concentration in the flue gas, and facilitates the capture and reduction of CO ₂ Cost recovery. Among them, the mixing loop is used to uniformly mix the flue gas and the cooling air to form a mixed gas with a lower oxygen content. The mixed gas is introduced into the distribution loop through the pipeline, and the outlet of the distribution loop is introduced into the burner through the pipeline.

In addition, the mixed gas with low oxygen content replaces the original cooling air, which reduces the oxygen content in the combustion process from the perspective of low-nitrogen combustion in the upper combustion chamber, which is beneficial to slow the heat release of combustion and inhibit the formation of nitrogen oxides.

The upper combustion chamber is under-oxygen combustion. In order to ensure the working environment of refractory materials, the temperature of the combustion chamber must be strictly controlled. When the air coefficient of the upper combustion chamber is 0.5, compared with the original process, when the same amount of oxygen is supplied, The amount of mixed flue gas introduced increases, thereby lowering the temperature of the combustion chamber. On the contrary, under the same temperature condition, more oxygen is given to increase the burning degree of the sleeve kiln fuel.

Preferably, the center line of the first mixed gas inlet and the center line of the first mixed gas outlet are on the same straight line. It further ensures that the cooling air and flue gas are evenly mixed in the mixing ring.

Preferably, the first cooling air inlet is evenly arranged along the circumferential direction of the cooling air ring pipe.

Preferably, the second mixed gas outlet is evenly arranged along the circumferential direction of the distribution ring.

The even distribution in the circumferential direction ensures a balanced airflow in the sleeve kiln.

Preferably, the flue gas inlet is in communication with the outlet of the flue gas circulation fan, the inlet of the flue gas circulation fan is in communication with the chimney, and the inlet of the flue gas circulation fan is provided with a flow orifice and a butterfly valve in sequence, and the flue gas At the outlet of the circulating fan, a pressure gauge, a one-way valve and a fast pneumatic shut-off valve are arranged in sequence.

The flue gas circulation fan introduces the flue gas into the mixing loop, the flow orifice is used to monitor the flue gas flow, and the pressure gauge monitors the pressure of the pipe to ensure that the flue gas flow and pressure are adapted to the calcination process requirements of the sleeve kiln.

The beneficial effects of the present invention:

The present invention provides a sleeve kiln using natural gas as fuel. The outer side of the sleeve kiln is originally provided with a cooling air loop, and now a mixing loop and a distribution loop are added to realize the flue gas recirculation process. The mixing loop is used for The flue gas and cooling air are uniformly mixed to form a mixture with lower oxygen content. The mixture is introduced into the distribution ring, and then the outlet of the distribution ring is introduced into the burner through the pipeline, which increases the CO ₂ in the flue gas of the sleeve kiln. Concentration to facilitate CO ₂ capture and reduce recycling costs. In addition, the use of a mixture with low oxygen content to replace the original cooling air reduces the oxygen content in the combustion process from the perspective of low-nitrogen combustion in the upper combustion chamber, which is beneficial to slow the heat release of combustion and inhibit the formation of nitrogen oxides; The combustion chamber is for under-oxygen combustion. In order to ensure the working environment of refractory materials, the temperature of the combustion chamber must be strictly controlled. When the air coefficient of the upper combustion chamber is 0.5, compared with the original process, under the same oxygen supply condition, The amount of mixed gas fed needs to be increased to lower the temperature of the combustion chamber; under the same temperature conditions, more oxygen needs to be fed to increase the burning degree of the sleeve kiln fuel. The center line of the mixed gas inlet on the mixing ring is on the same straight line as the center line of the first mixed gas outlet, which ensures that the cooling air and the flue gas are evenly mixed in the mixing ring. The second mixed gas outlet is evenly arranged along the circumferential direction of the distribution ring pipe to ensure the air flow balance in the sleeve kiln.

Description of the drawings

In order to explain the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the specific embodiments or the description of the prior art. Obviously, the appendix in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

Figure 1 is a schematic diagram of the structure of the sleeve kiln in the present invention;

Figure 2 is a schematic diagram of the cooling air loop structure of the present invention;

Figure 3 is a schematic diagram of the structure of the mixing loop in the present invention;

Figure 4 is a schematic diagram of the structure of the distribution loop in the present invention;

Figure 5 is a schematic diagram of the connection between the cooling air loop, the mixing loop and the distribution loop in the present invention;

Figure 6 is a schematic diagram of the structure of the pipeline between the flue gas inlet and the chimney in the present invention;

In the picture: 1- kiln body; 2- upper inner sleeve; 3- lower inner sleeve; 4- upper combustion chamber, 5- lower combustion chamber, 6-cooling air ring pipe, 7-mixing ring pipe; 8-distribution Ring tube; 9-chimney; 10-burner;

301- cooling air outlet;

601-first cooling air inlet; 602 first cooling air outlet;

701-first mixed gas inlet; 702-first mixed gas outlet;

7011-second cooling air inlet; 7012-flue gas inlet;

801-the second mixed gas inlet; 802-the second mixed gas outlet;

901-butterfly valve; 902-flow orifice; 903-flue gas circulation fan; 904-pressure gauge; 905-single valve; 906-fast pneumatic valve.

Detailed ways

The embodiments of the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and therefore are only used as examples, and cannot be used to limit the protection scope of the present invention.

In the description of this application, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "circumferential", etc. are based on the directions or positions shown in the drawings. The relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the pointed device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , Or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in the present invention can be understood according to specific circumstances.

The present invention is a sleeve kiln using natural gas as fuel. On the basis of the existing sleeve kiln, a cooling air ring 6, a mixing ring 7 and a distribution ring 8 are arranged on the outside of the kiln body 1 to achieve flue gas The cyclic process increases the CO ₂ concentration of the flue gas and facilitates the capture and recovery of CO ₂ in the flue gas.

Referring to Figure 1, the sleeve kiln in the present invention includes a kiln body 1, an upper inner sleeve 2, a lower inner sleeve 3, an upper combustion chamber 4 and a lower combustion chamber 5. The lower inner sleeve 3 is provided with a cooling air outlet 301. The upper combustion chamber 4 and the lower combustion chamber 5 are respectively provided with burners 10, the upper part of the kiln body 1 is provided with a flue gas outlet, and the flue gas outlet is connected to the flue of the chimney 9 through the flue gas treatment system , The outer side of the kiln body 1 is surrounded by a cooling air ring 6, a mixing ring 7 and a distribution ring 8 respectively.

The sleeve kiln in the present invention uses natural gas as fuel, and the outside of the kiln body 1 is also provided with a gas ring pipe. The cold natural gas is transported from the gas platform to the gas ring pipe, and then enters the upper combustion chamber through the upper and lower gas branch pipes. 4 and the lower combustion chamber 5.

In the technical field, the flue gas treatment system usually includes a flue gas heat exchanger, an induced draft fan, a dust collector, and a dust removal fan. Specifically, the flue gas outlet of the upper inner sleeve 2 of the sleeve kiln is connected to the flue gas heat exchanger through the flue gas heat exchanger. Fan, the flue gas outlet of the outer sleeve of the sleeve kiln is directly connected to the induced draft fan, and then connected to the flue of the chimney 9 after dust removal by the dust collector. The flue gas temperature after dust removal is about 200°C.

Referring to Figures 1-2, the cooling air loop 6 is provided with a plurality of first cooling air inlets 601 corresponding to the cooling air outlet 301, and the first cooling air inlet 601 and the cooling air outlet 301 are in one-to-one correspondence, so The cooling air ring pipe 6 is provided with a first cooling air outlet 602;

Referring to Figures 1, 3, and 5, the mixing loop 7 is provided with a first mixed gas inlet 701 and a first mixed gas outlet 702, and the first mixed gas inlet 701 includes a second cooling air inlet 7011 and flue gas An inlet 7012, the second cooling air inlet 7011 is in communication with the first cooling air outlet 602, and the flue gas inlet 7012 is in communication with the flue of the chimney 9;

1, 4 and 5, the distribution ring 8 is provided with a second mixed gas inlet 801, and the first mixed gas outlet 702 is in communication with the second mixed gas inlet 801; the distribution ring 8 A plurality of second mixed gas outlets 802 are provided corresponding to the burner 10 above, and the second mixed gas outlets 802 are connected to the burner 10 in a one-to-one correspondence.

Path of flue gas and cooling air:

The cooling air enters the first cooling air inlet 601 from the cooling air outlet 301 of the lower inner sleeve 3, the cooling air is collected into the cooling air ring pipe 6, and then flows into the mixing ring through the first cooling air outlet 602 to the second cooling air inlet 7011 In the pipe; part of the flue gas after dust removal is directly discharged by the chimney 9, and part of the flue gas is led from the flue of the chimney 9 to the flue gas inlet 7012 and flows into the mixing ring pipe 7, and the flue gas and cooling air are collected and uniformly mixed in the mixing ring pipe to form The mixed gas with lower oxygen content flows into the second mixed gas inlet 801 through the first mixed gas outlet 702 and enters the distribution ring 8, and the mixed gas is distributed to each burner 10 from the second mixed gas outlet 802.

The above structure realizes the flue gas recirculation process, increases the CO ₂ concentration in the sleeve kiln flue gas, facilitates CO ₂ capture and reduces recovery costs. In addition, the use of low-oxygen mixed gas instead of the original cooling air as the combustion-supporting air, for the upper combustion chamber 4 from the perspective of low-nitrogen combustion, reduces the oxygen content in the combustion process, which is beneficial to alleviate the combustion heat release and suppress nitrogen oxides The generation.

The upper combustion chamber 4 is under oxygen combustion. In order to ensure the refractory working environment, the combustion temperature must be strictly controlled. The above structure realizes that a partial flue gas in the chimney 9 is mixed with the cooling air of the lower inner sleeve 3 in full proportion, and the air coefficient in the sleeve kiln can be adjusted according to the degree of fuel burnt to adapt to the calcination process of the sleeve kiln Claim. When the air coefficient fed into the upper combustion chamber 4 is 0.5, compared with the original process, under the condition of feeding the same amount of oxygen, the amount of mixed gas fed needs to be increased to lower the temperature of the combustion chamber; under the same temperature conditions, More oxygen is needed to increase the burning degree of the sleeve kiln fuel.

Taking a 500tpd natural gas sleeve kiln as an example, the upper inner sleeve 2, the lower inner sleeve 3, the upper combustion chamber 4 and the lower combustion chamber 5 are six respectively, so the cooling air outlet 301 is six, and the burner 10 is twelve. Therefore, six first cooling air inlets 601 are provided on the cooling air ring 6 corresponding to the cooling air outlet 301, and twelve second mixed air outlets 802 are provided on the distribution ring corresponding to the burner 10.

The first cooling air inlet 601 is connected to the cooling air outlet 301 in a one-to-one correspondence through a pipeline, so that the cooling air of each cooling air outlet 301 is collected in the cooling air loop 6; the first cooling air outlet 602 passes the cooling air through the pipeline Lead to the second cooling air inlet 7011, a part of the flue gas in the flue of the chimney 9 is introduced into the flue gas inlet 7012 through the pipeline, the cooling air and the flue gas are collected in the mixing loop 7 and uniformly mixed to form a mixed gas with lower oxygen content , The mixed gas is introduced from the first mixed gas outlet 702 through the pipeline into the second mixed gas inlet 801 into the distribution ring 8, and then the twelve second mixed gas outlets 802 are respectively connected to each burner 10 through the pipeline one by one, The mixed gas is delivered to each burner 10.

The connection of pipeline valves between the cooling air outlet 301, the cooling air loop 6, the mixing loop 7, the distribution loop 8, and the chimney 9 can be designed according to actual requirements to meet the calcination process requirements of the sleeve kiln.

In a preferred embodiment, referring to Fig. 3, the center lines of the mixed gas inlet 701 and the first mixed gas outlet 702 are on the same straight line. It is ensured that the cooling air and the flue gas are evenly mixed in the mixing ring 7.

In a preferred embodiment, referring to Fig. 3, the second cooling air inlet 7011 and the flue gas inlet 7012 are arranged in close proximity. It is also to ensure uniform mixing of flue gas and cooling air.

In a preferred embodiment, referring to FIG. 2, the first cooling air inlet 601 is evenly arranged along the circumference of the cooling air ring pipe 6.

In a preferred embodiment, referring to FIG. 4, the second mixed gas outlet 802 is uniformly arranged along the circumferential direction of the distribution ring 8.

The first cooling air inlet and the second mixed air outlet are evenly distributed along the circumferential direction, which basically guarantees the balance of airflow in the sleeve kiln.

In a preferred embodiment, referring to Figure 6, the flue gas inlet 7012 is in communication with the outlet of the flue gas circulation fan 90, the inlet of the flue gas circulation fan 903 is in communication with the flue of the chimney 9, and the flue gas The inlet of the circulating fan 903 is provided with a flow orifice 902 and a butterfly valve 901 in sequence, and the outlet of the flue gas circulating fan 903 is provided with a pressure gauge 904, a one-way valve 905 and a fast pneumatic shut-off valve 906 in sequence. Specifically, the flue gas after dust removal is led from the flue of the chimney 9 to flow through the butterfly valve 901, the flow orifice 902, the flue gas circulation fan 903, the pressure gauge 904, the one-way valve 905 and the fast pneumatic shut-off valve 906. Among them, the flow orifice 902 is used to measure the flow of flue gas, the function of the flue gas circulation fan 903 is to provide power for the flue gas, which is sent to the mixing loop 7, and the outlet of the flue gas circulation fan 903 is provided with a pressure gauge 904 for use To control the flue gas pressure. It is also possible to install valves, flow, pressure, temperature and other instruments or devices between the flue gas inlet 7012 and the chimney 9 according to the actual process conditions.

The sequence of the above embodiments is only for ease of description, and does not represent the advantages and disadvantages of the embodiments.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: It is still possible to modify the technical solutions described in the foregoing embodiments, or equivalently replace some or all of the technical features; these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention range.

Claims

A sleeve kiln using natural gas as fuel, comprising a kiln body, an upper inner sleeve, a lower inner sleeve, an upper combustion chamber and a lower combustion chamber, the lower inner sleeve is provided with a cooling air outlet, and the upper combustion chamber And the lower combustion chamber are respectively provided with burners, the upper part of the kiln body is provided with a flue gas outlet, and the flue gas outlet is communicated with the flue of the chimney through the flue gas treatment system, characterized in that the outer sides of the kiln body are respectively Surrounded by a cooling air ring, a mixing ring, and a distribution ring, the cooling air ring is provided with a plurality of first cooling air inlets corresponding to the cooling air outlet, and the first cooling air inlet and the cooling air outlet are one by one Corresponding to the communication, a first cooling air outlet is also provided on the cooling air ring pipe;

The mixing loop is provided with a first mixed gas inlet and a first mixed gas outlet. The first mixed gas inlet includes a second cooling air inlet and a flue gas inlet that are adjacently arranged. The second cooling air inlet and the first A cooling air outlet is connected, and the flue gas inlet is connected with the flue of the chimney; a second mixed gas inlet is provided on the distribution ring pipe, and the first mixed gas outlet is connected with the second mixed gas inlet; A plurality of second mixed gas outlets are provided on the distribution ring corresponding to the burner, and the second mixed gas outlets are connected to the burner in a one-to-one correspondence.
The sleeve kiln using natural gas as fuel according to claim 1, wherein the center line of the first mixed gas inlet and the center line of the first mixed gas outlet are on the same straight line.
The sleeve kiln using natural gas as fuel according to claim 1, wherein the first cooling air inlet is evenly arranged along the circumferential direction of the cooling air ring pipe.
The sleeve kiln using natural gas as fuel according to claim 1, wherein the second mixed gas outlet is evenly arranged along the circumferential direction of the distribution ring.
The sleeve kiln using natural gas as fuel according to any one of claims 1 to 4, wherein the flue gas inlet is in communication with the outlet of the flue gas circulation fan, and the inlet of the flue gas circulation fan is in communication with the chimney, The inlet of the flue gas circulation fan is provided with a flow orifice and a butterfly valve in sequence, and the outlet of the flue gas circulation fan is provided with a pressure gauge, a one-way valve and a fast pneumatic shut-off valve in sequence.