Method and device for efficiently combusting low-calorific-value head and tail gas of converter

Abstract

The invention discloses a method and a device for efficiently combusting low-calorific-value head and tail coal gas of a converter, which can recycle the low-calorific-value head and tail coal gas of the converter on one hand, and can perform periodic switching co-combustion by means of an efficient phase of porous medium combustion and high-calorific-value gas on the other hand so as to improve the combustion condition of the low-calorific-value gas. And the influence on the combustion heat efficiency is reduced as much as possible.

Description

Technical Field

[0001] The invention relates to the technical field of converter gas recovery, and in particular to a method and device for efficiently burning converter low calorific value head and tail gas. Background Art

[0002] The recycling of low calorific value converter head and tail gas has always been a difficult problem in the industry due to its low calorific value and poor combustion stability. Among them, the low calorific value converter head and tail gas with a concentration below 25% is currently mostly discharged after being burned in the form of sky lanterns; however, this treatment method is not only simple and crude, but also causes a huge waste of energy, and also brings certain environmental pollution problems. How to recycle converter gas with a carbon monoxide concentration below 25% has now become a key difficulty to overcome in the current converter process energy efficiency benchmark.

[0003] For low calorific value gas, the combustion flame is extremely unstable due to its low calorific value. In addition, there are problems such as low combustion temperature and slow combustion heat transfer. Therefore, in order to enhance the stability of low calorific value gas combustion, the low calorific value gas is generally recycled by preheating or mixing the low calorific value gas with the high calorific value gas.

[0004] Porous media combustion technology is a high-efficiency combustion technology that utilizes the good heat transfer characteristics of porous ceramic heat storage bodies to improve combustion stability. Using porous media burners to recycle low calorific value gases is a better way, but it is always limited by the low calorific value characteristics of the fuel. After using porous media combustion, its combustion temperature is lower, which is not conducive to heat transfer between the furnace and the heated object. Mixing low calorific value gases and high calorific value gases will affect the combustion characteristics of the high calorific value gas, and there is a problem of affecting the thermal efficiency of combustion.

[0005] In view of the above situation, it is urgent to develop a method for efficiently recycling and utilizing low calorific value coal gas, reduce coal gas emission and waste, and avoid environmental pollution. Summary of the invention

[0006] In view of the problem of solving the combustion of low calorific value converter gas in the prior art, the purpose of the present invention is to provide a method and device for efficiently burning low calorific value converter head and tail gases. On the one hand, it can realize the recovery and utilization of low calorific value converter head and tail gases, and on the other hand, it can improve the combustion conditions of the low calorific value gas by periodically switching the high-efficiency phase of porous medium combustion and high calorific value gas and minimize the impact on the thermal efficiency of combustion.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a high-efficiency converter low calorific value head and tail gas device, comprising:

[0009] a first gas-air mixer for premixing converter gas containing high concentration of carbon monoxide with air;

[0010] a second gas-air mixer for premixing converter gas containing low concentration of carbon monoxide with air;

[0011] The secondary heat exchanger is connected to the first gas-air mixer and the second gas-air mixer respectively, and is used to preheat the premixed gas after being premixed by the first gas-air mixer and the second gas-air mixer;

[0012] A first program-controlled switch, provided on the first pipeline between the first gas-air mixer and the secondary heat exchanger, controls the opening and closing of the first pipeline;

[0013] A second program-controlled switch is provided on the second pipeline between the second gas-air mixer and the secondary heat exchanger to control the opening and closing of the second pipeline; the second program-controlled switch and the first program-controlled switch are controlled by a NOT gate program, and the two are connected to form a NOT gate;

[0014] A double-layer porous medium burner connected to the secondary heat exchanger for burning the preheated fuel gas;

[0015] The primary heat exchanger is connected to the double-layer porous medium burner to recycle the combustion heat of the double-layer porous medium burner. The flue gas outlet of the primary heat exchanger is connected to the flue gas inlet of the secondary heat exchanger.

[0016] Preferably, the double-layer porous medium burner comprises a preheating zone connected to the secondary heat exchanger and a combustion zone connected to the preheating zone.

[0017] Preferably, the preheating zone is filled with alumina balls with a diameter of 3 to 8 mm; and the combustion zone is filled with silicon carbide foam ceramics with a porosity of 0.6 to 0.9.

[0018] The second aspect of the present invention provides a method for efficiently burning converter low calorific value head and tail gas, using the efficient converter low calorific value head and tail gas burning device as described in the first aspect of the present invention to perform the following steps:

[0019] S1, collecting the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide into different converter gas holders respectively;

[0020] S2, premixing the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide with air to obtain a first premixed gas and a second premixed gas;

[0021] S3, the first premixed gas enters the secondary heat exchanger for preheating through the first program control switch, and the second premixed gas enters the secondary heat exchanger for preheating through the second program control switch. When the first program control switch is turned on, the second program control switch is closed;

[0022] S4, the preheated gas enters the double-layer porous medium burner for combustion. At the beginning of combustion, the first program control switch is turned on. After the combustion is stable, the NOT gate program is started and the switching cycle is set. The first program control switch and the second program control switch are switched periodically.

[0023] S5, after the gas is burned in the double-layer porous medium burner, the combustion heat is recovered and utilized through the primary heat exchanger, and the flue gas after heat exchange in the primary heat exchanger enters the secondary heat exchanger to preheat the first premixed gas / second premixed gas, and then is introduced into the flue gas treatment device for treatment and discharge.

[0024] Preferably, in step S1, the volume fraction of carbon monoxide in the converter gas containing high concentration of carbon monoxide is greater than 25%, and the volume fraction of carbon monoxide in the converter gas containing low concentration of carbon monoxide is 15-25%.

[0025] Preferably, when the volume fraction of carbon monoxide in the converter gas is less than 15%, the converter gas containing a high concentration of carbon monoxide is mixed with the converter gas containing a volume fraction of carbon monoxide less than 15% so that the volume fraction of carbon monoxide in the converter gas reaches 15-25%, thereby preparing the converter gas containing a low concentration of carbon monoxide.

[0026] Preferably, in step S2, the converter gas containing high concentration of carbon monoxide, the converter gas containing low concentration of carbon monoxide and air are premixed according to an excess air coefficient, and the excess air coefficient is 1.05 to 1.1.

[0027] Preferably, in step S3, the preheating temperature of the secondary heat exchanger is ≥ 300°C.

[0028] Preferably, in step S4, the combustion of the fuel gas is stabilized by controlling the inlet gas flow rate of the double-layer porous medium burner; the inlet gas flow rate is 0.2-0.6 m / s.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The method for efficiently burning low calorific value head and tail gas of the converter of the present invention recycles the low concentration head and tail gas of the converter, reduces gas emission and waste, and avoids environmental pollution;

[0031] 2. The high-efficiency method for burning low-calorific-value head and tail gas of the converter of the present invention recycles the waste heat of the flue gas in stages to preheat the fuel and improve the combustion stability;

[0032] 3. The high-efficiency method for burning low-calorific-value head and tail gas of the converter of the present invention uses a porous medium burner to periodically switch and burn the fuel to recover the fuel;

[0033] 4. The high-efficiency combustion method of the converter low calorific value head and tail gas of the present invention has a simple combustion method and can be used for switching combustion of high calorific value gas and low calorific value gas;

[0034] 5. The present invention utilizes the heat storage characteristics of porous medium ceramics. In the process of periodic switching combustion, due to the high heat storage characteristics of the porous medium, when switching combustion, the low calorific value gas reacts quickly under the high temperature heat storage conditions of the porous medium. As the combustion proceeds, although the low calorific value gas does not produce enough heat, the combustion tends to be unstable. However, as the switching combustion proceeds, the entry of high calorific value fuel can timely supplement heat to maintain the stability of combustion. Therefore, this can achieve periodic mixed combustion of fuels of different calorific values ​​in the same burner, while maintaining the stability of combustion.

[0035] 6. Compared with direct mixed combustion, the present invention can save fuel by periodically switching combustion without reducing combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0037] Figure 1 It is a schematic flow diagram of a method for efficiently burning converter low calorific value head and tail gas according to the present invention. DETAILED DESCRIPTION

[0038] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form.

[0039] Combination Figure 1 As shown, the present invention provides a high-efficiency combustion converter low calorific value head and tail gas device, comprising

[0040] The first gas-air mixer 1 is used to premix the converter gas containing high concentration of carbon monoxide with air;

[0041] The second gas-air mixer 2 is used to premix the converter gas containing low concentration of carbon monoxide with air;

[0042] The secondary heat exchanger 3 is connected to the first gas-air mixer 1 and the second gas-air mixer 2 respectively, and is used to preheat the premixed gas premixed by the first gas-air mixer 1 and the second gas-air mixer 2;

[0043] A first program-controlled switch 6 is provided on the first pipeline between the first gas-air mixer 1 and the secondary heat exchanger 3 to control the opening and closing of the first pipeline;

[0044] The second program control switch 7 is arranged on the second pipeline between the second gas-air mixer 2 and the secondary heat exchanger 3 to control the opening and closing of the second pipeline; the second program control switch 7 and the first program control switch 6 are controlled by a NOT gate, and the two are connected to form a NOT gate. The first program control switch 6 and the second program control switch 7 are not turned on at the same time; when the first program control switch 6 is turned on, the second program control switch 7 is closed, and the converter gas with high concentration of carbon monoxide enters the double-layer porous medium burner 4 for combustion; when the second program control switch 7 is turned on, the first program control switch 6 is closed, and the converter gas with low concentration of carbon monoxide enters the double-layer porous medium burner 4 for combustion.

[0045] The double-layer porous medium burner 4 is connected to the secondary heat exchanger 3 to burn the preheated fuel gas; wherein the double-layer porous medium burner 4 includes a preheating zone connected to the secondary heat exchanger 3 (the preheating zone is set to small pores) and a combustion zone connected to the preheating zone (the combustion zone is set to large pores); wherein the preheating zone of the double-layer porous medium burner 4 is filled with alumina balls with a diameter of 3 to 8 mm and a pore size of 0.4, and the combustion zone is filled with silicon carbide foam ceramics with a porosity of 0.6 to 0.9.

[0046] The primary heat exchanger 5 is connected to the double-layer porous medium burner 4 to recycle the combustion heat of the double-layer porous medium burner 4 . The flue gas outlet of the primary heat exchanger 5 is connected to the flue gas inlet of the secondary heat exchanger 3 .

[0047] The method for efficiently burning low calorific value head and tail gas of the converter of the present invention preheats the low calorific value gas and utilizes the heat storage characteristics of the double-layer porous medium burner to periodically switch the low calorific value converter gas with a carbon monoxide volume fraction between 15% and 25% so that it is periodically mixed with the converter gas with a higher calorific value and a carbon monoxide concentration higher than 25% in the double-layer porous medium burner.

[0048] Combination Figure 1 As shown, a method for efficiently burning converter low calorific value head and tail gas is provided, and the following steps are performed using the above-mentioned device for efficiently burning converter low calorific value head and tail gas:

[0049] S1, collecting the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide into different converter gas holders respectively;

[0050] Specifically, the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide are stored in different converter gas tanks for collection;

[0051] In one embodiment, the volume fraction of carbon monoxide in the converter gas containing high carbon monoxide concentration is greater than 25%, and the volume fraction of carbon monoxide in the converter gas containing low carbon monoxide concentration is between 15% and 25%. For the converter gas with a very low volume fraction of carbon monoxide, the converter gas with high carbon monoxide concentration and the converter gas with a volume fraction of carbon monoxide less than 15% can be mixed to make the carbon monoxide concentration of the mixed converter gas between 15% and 25%, thereby preparing the converter gas with low calorific value.

[0052] The above volume fraction of carbon monoxide in the converter gas is only an example and may vary according to actual conditions.

[0053] S2, premixing the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide with air to obtain a first premixed gas and a second premixed gas;

[0054] The high-concentration converter gas and air are premixed in the first gas-air mixer 1 according to a certain excess air coefficient, so that the converter gas and air are fully mixed to obtain the first premixed gas; wherein the excess air coefficient is generally 1.05 to 1.1.

[0055] The low-concentration converter gas and air are premixed in a second gas-air mixer 2 in another pipeline according to a certain excess air coefficient, so that the converter gas and air are fully mixed to obtain a second premixed gas; wherein the excess air coefficient is generally 1.05 to 1.1.

[0056] S3, the first premixed gas enters the secondary heat exchanger 3 through the first program control switch 6 for preheating, and the second premixed gas enters the secondary heat exchanger 3 through the second program control switch 7 for preheating. When the first program control switch 6 is turned on, the second program control switch 7 is closed;

[0057] Specifically, the first premixed gas enters the secondary heat exchanger 3 for preheating through the first program control switch 6, and the second premixed gas enters the secondary heat exchanger 3 for preheating through the second program control switch 7. Preheating the gas can further improve the stability of combustion. When the first program control switch 6 is turned on, the second program control switch 7 is closed; the heat exchange medium used in the secondary heat exchanger 3 comes from the waste heat of the flue gas during the combustion process of the double-layer porous medium burner 4; in a specific embodiment, the preheating temperature of the secondary heat exchanger 3 is ≥300°C, which can be specifically determined according to the flue gas temperature, such as 300-500°C.

[0058] Since the first program-controlled switch 6 and the second program-controlled switch 7 are both controlled by the NOT gate program, the two are connected to form a NOT gate relationship. When the first program-controlled switch 6 is opened, the second program-controlled switch 7 is closed, and the gas passes through the first program-controlled switch 6; conversely, when the first program-controlled switch 6 is closed, the second program-controlled switch 7 is opened, and the gas passes through the second program-controlled switch 7; wherein the opening and closing of the first program-controlled switch 6 and the second program-controlled switch 7 are controlled by a manually set time, and the time is measured by a timer, for example, in a period T (for example, T is 30s), the first program-controlled switch 6 is opened and the second program-controlled switch 7 is closed; in the next period T (for example, T is 30s), the second program-controlled switch 7 is opened and the first program-controlled switch 6 is closed; the two program-controlled switches are opened and closed once under the condition of T (for example, T is 30s) as a period, thereby realizing the periodic switching of different gases flowing into the double-layer porous medium burner 4 for combustion;

[0059] S4, the preheated gas enters the double-layer porous medium burner 4 for combustion. At the beginning of combustion, the first program control switch 6 is turned on. After the combustion is stable, the NOT gate program is started and the switching cycle is set. The first program control switch 6 and the second program control switch 7 are periodically switched;

[0060] Specifically, the preheated fuel is preheated by the secondary heat exchanger 3 and then introduced into the double-layer porous medium burner 4 for combustion, wherein the double-layer porous medium burner 4 includes an upstream small pore preheating zone and a downstream large pore combustion zone, and the main function of the preheating zone is to prevent backfire and improve the safety of combustion. At the beginning of combustion, the first program control switch 6 is turned on, and the air / gas premixed gas (first premixed gas) of the high calorific value gas is burned in the double-layer porous medium burner 4, and the gas combustion is stabilized by controlling the inlet gas flow rate of the double-layer porous medium burner, wherein the inlet gas flow rate is 0.2-0.6 m / s; for example, when the inlet flow rate of the high calorific value gas is v=0.3 m / s, the combustion flame is flat and stable. After the combustion is stabilized, the NOT gate program is started and the switching cycle T is set, so that the low calorific value gas (second premixed gas) and the high calorific value gas (first premixed gas) are periodically switched and burned in the double-layer porous medium burner 4. In addition, with the help of the high heat storage characteristics of porous dielectric ceramics, although low calorific value gas is difficult to ignite at room temperature, when the temperature in the porous medium combustion area is as high as 1300°C or above, it is sufficient to make the low calorific value gas burn quickly in the combustion area, and periodically switch and mix with the high calorific value gas within the period T. In the actual combustion process, the switching period T can be set artificially according to the specific actual situation to achieve the switching combustion of converter gas with low carbon monoxide concentration and converter gas with high carbon monoxide concentration. In a specific embodiment, the switching period T can be set to 30 to 60s, which can be determined according to the actual situation. In a certain embodiment, the relevant numerical simulation results show that the high and low calorific value gases can achieve stable switching combustion when the flow rate of the two inlets is 0.3m / s and T=30s.

[0061] S5, after the gas is burned in the double-layer porous medium burner 4, the combustion heat is recovered and utilized through the primary heat exchanger 5, and the flue gas after heat exchange in the primary heat exchanger 5 enters the secondary heat exchanger 3 to preheat the first premixed gas / second premixed gas, and then is introduced into the flue gas treatment device for treatment and discharge.

[0062] Specifically, after the gas is burned in the double-layer porous medium burner 4, the combustion heat is recycled through the primary heat exchanger 5 to heat different materials or working fluids, where the materials or working fluids can be scrap steel or working fluid water to generate steam.

[0063] The flue gas after heat exchange in the primary heat exchanger 5 is introduced into the secondary heat exchanger 3 to further recover the waste heat of the flue gas and use it to preheat the fuel gas.

[0064] After passing through the secondary heat exchanger 3, the flue gas is introduced into the flue gas treatment device for treatment and discharge.

[0065] The following is a further introduction to a method and device for efficiently burning low calorific value head and tail gas of a converter with reference to specific examples.

[0066] Example 1

[0067] The method for efficiently burning converter low calorific value head and tail gas in this embodiment is as follows:

[0068] (1) The converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide are stored in different converter gas tanks for collection.

[0069] The volume fraction of carbon monoxide in the converter gas with high carbon monoxide concentration is 50%, and the volume fraction of carbon monoxide in the converter gas with low carbon monoxide concentration is 15%.

[0070] (2) Premixing the converter gas with high carbon monoxide concentration and air in the first gas-air mixer according to a certain excess air coefficient, so that the fuel and air are fully mixed to obtain the first premixed gas. The excess air coefficient is generally 1.1.

[0071] (3) Premixing converter gas with a carbon monoxide concentration of 15% by volume and air in a second gas-air mixer in another pipeline according to a certain excess air coefficient, so that the fuel and air are fully mixed to obtain a second premixed gas. The excess air coefficient is 1.1.

[0072] (4) The first premixed gas enters the secondary heat exchanger for preheating through the first program control switch, and the second premixed gas enters the secondary heat exchanger for preheating through the second program control switch. When the first program control switch is turned on, the second program control switch is closed; wherein the switching cycle in the NOT gate program is set to T=30s, the heat exchange medium in the secondary heat exchanger comes from the flue gas waste heat in the combustion process, and the preheating temperature of the flue gas used in the secondary heat exchanger is set to 300°C.

[0073] (5) The double-layer porous medium burner structure is that the upper preheating zone is filled with alumina balls with a porosity of 0.4 and a diameter of 5 mm, and the downstream combustion zone is filled with silicon carbide foam ceramics with a porosity of 0.77.

[0074] (6) The converter gas with a carbon monoxide volume fraction of 50% is premixed and preheated and then flows into the porous medium burner for combustion. After the combustion is stable, the non-gate program is turned on to allow the high and low calorific value premixed gases to be periodically switched and burned in the porous medium burner.

[0075] Relevant numerical simulation studies have shown that under the condition of a switching cycle of 30s, stable combustion of high and low calorific values ​​can be achieved in the porous medium area and a stable combustion flame can be formed.

[0076] The switching cycle is only the calculation result of numerical simulation. In the actual combustion process, the switching cycle can be set artificially according to the specific actual situation to achieve switching combustion between the two.

[0077] (7) After the fuel gas is burned in the double-layer porous medium burner, the heat generated by the combustion is recovered and utilized through the primary heat exchanger. The flue gas after heat exchange in the primary heat exchanger enters the secondary heat exchanger to preheat the first premixed fuel gas / second premixed fuel gas, and then is introduced into the flue gas treatment device for treatment and discharge.

[0078] Example 2

[0079] The method for efficiently burning converter low calorific value head and tail gas in this embodiment is as follows:

[0080] (1) The converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide are stored in different converter gas tanks for collection.

[0081] The volume fraction of carbon monoxide in the converter gas with high carbon monoxide concentration is 50%, and the volume fraction of carbon monoxide in the converter gas with low carbon monoxide concentration is 25%.

[0082] (2) Premixing the converter gas with high carbon monoxide concentration and air in the first gas-air mixer according to a certain excess air coefficient, so that the fuel and air are fully mixed to obtain the first premixed gas. The excess air coefficient is generally 1.1.

[0083] (3) Premixing converter gas with a carbon monoxide concentration of 25% by volume and air in a second gas-air mixer in another pipeline according to a certain excess air coefficient, so that the fuel and air are fully mixed to obtain a second premixed gas. The excess air coefficient is 1.1.

[0084] (4) The first premixed gas enters the secondary heat exchanger for preheating through the first program control switch, and the second premixed gas enters the secondary heat exchanger for preheating through the second program control switch. When the first program control switch is turned on, the second program control switch is closed; wherein the switching cycle in the NOT gate program is set to T=60s, the heat exchange medium in the secondary heat exchanger comes from the flue gas waste heat in the combustion process, and the preheating temperature of the flue gas used in the secondary heat exchanger is set to 300°C.

[0085] (5) The double-layer porous medium burner structure is that the upper preheating zone is filled with alumina balls with a porosity of 0.4 and a diameter of 5 mm, and the downstream combustion zone is filled with silicon carbide foam ceramics with a porosity of 0.77.

[0086] (6) The converter gas with a carbon monoxide volume fraction of 50% is premixed and preheated and then flows into the porous medium burner for combustion. After the combustion is stable, the non-gate program is turned on to allow the high and low calorific value premixed gases to be periodically switched and burned in the porous medium burner.

[0087] Relevant numerical simulation studies have shown that under the condition of a switching cycle of 60s, stable combustion of high and low calorific values ​​can be achieved in the porous medium area and a stable combustion flame can be formed.

[0088] The switching cycle is only the calculation result of numerical simulation. In the actual combustion process, the switching cycle can be set artificially according to the specific actual situation, so as to realize the switching combustion between the two.

[0089] (7) After the fuel gas is burned in the double-layer porous medium burner, the heat generated by the combustion is recovered and utilized through the primary heat exchanger. The flue gas after heat exchange in the primary heat exchanger enters the secondary heat exchanger to preheat the first premixed fuel gas / second premixed fuel gas, and then is introduced into the flue gas treatment device for treatment and discharge.

[0090] Example 3

[0091] The method for efficiently burning converter low calorific value head and tail gas in this embodiment is as follows:

[0092] (1) The converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide are stored in different converter gas tanks for collection.

[0093] The volume fraction of carbon monoxide in the converter gas with high carbon monoxide concentration is 35%, and the volume fraction of carbon monoxide in the converter gas with low carbon monoxide concentration is 15%.

[0094] (2) Premixing the converter gas with high carbon monoxide concentration and air in the first gas-air mixer according to a certain excess air coefficient, so that the fuel and air are fully mixed to obtain the first premixed gas. The excess air coefficient is generally 1.1.

[0095] (3) Premixing converter gas with a carbon monoxide concentration of 15% by volume and air in a second gas-air mixer in another pipeline according to a certain excess air coefficient, so that the fuel and air are fully mixed to obtain a second premixed gas. The excess air coefficient is 1.1.

[0096] (4) The first premixed gas enters the secondary heat exchanger for preheating through the first program control switch, and the second premixed gas enters the secondary heat exchanger for preheating through the second program control switch. When the first program control switch is turned on, the second program control switch is closed; wherein the switching cycle in the NOT gate program is set to T=30s, the heat exchange medium in the secondary heat exchanger comes from the flue gas waste heat in the combustion process, and the preheating temperature of the flue gas used in the secondary heat exchanger is set to 500°C.

[0097] (5) The double-layer porous medium burner structure is that the upper preheating zone is filled with alumina balls with a porosity of 0.4 and a diameter of 5 mm, and the downstream combustion zone is filled with silicon carbide foam ceramics with a porosity of 0.77.

[0098] (6) The converter gas with a carbon monoxide volume fraction of 35% flows into the porous medium burner for combustion after being premixed and preheated. After the combustion is stable, the non-gate program is turned on to allow the high and low calorific value premixed gases to be periodically switched and burned in the porous medium burner.

[0099] Relevant numerical simulation studies have shown that under the condition of a switching cycle of 30s, stable combustion of high and low calorific values ​​can be achieved in the porous medium area and a stable combustion flame can be formed.

[0100] The switching cycle is only the calculation result of numerical simulation. In the actual combustion process, the switching cycle can be set artificially according to the specific actual situation, so as to realize the switching combustion between the two.

[0101] (7) After the fuel gas is burned in the double-layer porous medium burner, the heat generated by the combustion is recovered and utilized through the primary heat exchanger. The flue gas after heat exchange in the primary heat exchanger enters the secondary heat exchanger to preheat the first premixed fuel gas / second premixed fuel gas, and then is introduced into the flue gas treatment device for treatment and discharge.

[0102] In summary, the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A high-efficiency combustion converter low calorific value head and tail gas device, characterized in that: include a first gas-air mixer for premixing converter gas containing high concentration of carbon monoxide with air; a second gas-air mixer for premixing converter gas containing low concentration of carbon monoxide with air; The secondary heat exchanger is connected to the first gas-air mixer and the second gas-air mixer respectively, and is used to preheat the premixed gas after being premixed by the first gas-air mixer and the second gas-air mixer; A first program-controlled switch, provided on the first pipeline between the first gas-air mixer and the secondary heat exchanger, controls the opening and closing of the first pipeline; A second program-controlled switch, provided on the second pipeline between the second gas-air mixer and the secondary heat exchanger, controls the opening and closing of the second pipeline; The second program-controlled switch and the first program-controlled switch are controlled by a NOT gate program, and the two are connected to form a NOT gate; A double-layer porous medium burner connected to the secondary heat exchanger for burning the preheated fuel gas; The primary heat exchanger is connected to the double-layer porous medium burner to recycle the combustion heat of the double-layer porous medium burner. The flue gas outlet of the primary heat exchanger is connected to the flue gas inlet of the secondary heat exchanger.

2. The high-efficiency combustion converter low calorific value head and tail gas device according to claim 1, characterized in that: The double-layer porous medium burner includes a preheating zone connected to the secondary heat exchanger and a combustion zone connected to the preheating zone.

3. The high-efficiency combustion converter low calorific value head and tail gas device according to claim 2, characterized in that: The preheating zone is filled with alumina balls with a diameter of 3 to 8 mm; the combustion zone is filled with silicon carbide foam ceramics with a porosity of 0.6 to 0.

9.

4. A method for efficiently burning converter low calorific value head and tail gas, characterized in that: The following steps are performed using the high-efficiency combustion converter low calorific value head and tail gas device as described in claims 1-3: S1, collecting the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide into different converter gas holders respectively; S2, premixing the converter gas containing high concentration of carbon monoxide and the converter gas containing low concentration of carbon monoxide with air to obtain a first premixed gas and a second premixed gas; S3, the first premixed gas enters the secondary heat exchanger for preheating through the first program control switch, and the second premixed gas enters the secondary heat exchanger for preheating through the second program control switch. When the first program control switch is turned on, the second program control switch is closed; S4, the preheated gas enters the double-layer porous medium burner for combustion. At the beginning of combustion, the first program control switch is turned on. After the combustion is stable, the NOT gate program is started and the switching cycle is set. The first program control switch and the second program control switch are switched periodically. S5, after the gas is burned in the double-layer porous medium burner, the combustion heat is recovered and utilized through the primary heat exchanger, and the flue gas after heat exchange in the primary heat exchanger enters the secondary heat exchanger to preheat the first premixed gas / second premixed gas, and then is introduced into the flue gas treatment device for treatment and discharge.

5. The method for efficiently burning converter low calorific value head and tail gas as claimed in claim 4, characterized in that: In the step S1, the volume fraction of carbon monoxide in the converter gas containing high-concentration carbon monoxide is greater than 25%, and the volume fraction of carbon monoxide in the converter gas containing low-concentration carbon monoxide is 15-25%.

6. The method for efficiently burning converter low calorific value head and tail gas as claimed in claim 5, characterized in that: When the volume fraction of carbon monoxide in the converter gas is less than 15%, the converter gas containing high concentration of carbon monoxide is mixed with the converter gas with a volume fraction of carbon monoxide less than 15% to make the volume fraction of carbon monoxide in the converter gas reach 15-25%, thereby preparing the converter gas containing low concentration of carbon monoxide.

7. The method for efficiently burning converter low calorific value head and tail gas as claimed in claim 4, characterized in that: In the step S2, the converter gas containing high concentration of carbon monoxide, the converter gas containing low concentration of carbon monoxide and air are premixed according to an excess air coefficient, and the excess air coefficient is 1.05 to 1.

1.

8. The method for efficiently burning converter low calorific value head and tail gas as claimed in claim 4, characterized in that: In step S3, the preheating temperature of the secondary heat exchanger is ≥300°C.

9. The method for efficiently burning converter low calorific value head and tail gas as claimed in claim 4, characterized in that: In the step S4, the combustion of the fuel gas is stabilized by controlling the inlet gas flow rate of the double-layer porous medium burner; the inlet gas flow rate is 0.2-0.6 m / s.

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