Device and method for inhibiting carbon precipitation of mixed hydrogen-rich coal gas heated by heating furnace

Abstract

The invention belongs to the technical field of heating furnaces, and particularly discloses a device and method for restraining carbon precipitation of mixed hydrogen-rich coal gas heated by a heating furnace, and the device comprises a coke oven, a tubular heat exchanger, a mixer, a hydrogen-rich carbon circulating oxygen blast furnace, the heating furnace, a PLC and a steam pipe. The decarburized gas and water vapor are mixed and then fed into the heating furnace to be heated, and the heated decarburized gas and coke oven gas are mixed in the mixer, so that the phenomenon that methane in the coke oven gas mixed with the hydrogen-rich gas is self-generated to form graphite or carbon nanotubes when the temperature is higher than 1000 DEG C in the heating process of the heating furnace is avoided; the problems that when mixed hydrogen-rich coal gas is heated in a heating furnace, carbon is separated out, granular carbon is accumulated, a furnace body cracks, equipment is blocked, and safe and stable operation of a system is affected are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of heating furnaces, and in particular to a device and method for suppressing carbon deposition during heating of mixed hydrogen-rich coal gas in a heating furnace. Background Art

[0002] The media injected into the tuyere of hydrogen-rich carbon cycle oxygen blast furnace are mainly: room temperature oxygen, decarbonized coal gas, pulverized coal, and hydrogen-rich coal gas. After mixing, they are heated by a heating furnace. The main components of decarbonized coal gas are: 0.5%-20% H2, 0%-1% CH4, 50%-65% CO, 5%-15% N2, and 1.0%-3% CO2. Hydrogen-rich coal gas refers to coke oven gas and natural gas. Coke oven gas mainly contains about 55%-60% H2, 23%-27% CH4, 5%-8% CO, 0.3%-0.8% O2, 3%-7% N2, 1.5%-3% CO2, and more than 2%-4% unsaturated hydrocarbons; natural gas is mainly composed of 85% CH4, 9% C2H6, 3% C3H8, 2% N2, 1% C4H 10 From this, we can know that hydrogen-rich coal gas contains a high content of methane. The low-temperature carbon precipitation of methane is the generation of amorphous carbon under the catalysis of iron, cobalt and other alloys at 500-800℃. The low-temperature carbon precipitation of methane is the spontaneous generation of graphite or carbon nanotubes at a temperature >1000℃.

[0003] The original hydrogen-rich carbon circulating oxygen blast furnace hydrogen enrichment method is to mix hydrogen-rich coal gas into decarbonized coal gas, so that the proportion of hydrogen-rich coal gas in the mixed hydrogen-rich coal gas reaches 5%-25% of the total gas volume, and the temperature after mixing is 30-45°C. The mixed hydrogen-rich coal gas is then passed into the heating furnace for heating to a temperature of 1200-1400°C, and finally blown into the blast furnace through the tuyere. When the mixed hydrogen-rich coal gas is heated in the heating furnace, when the temperature is >1000℃, methane decomposition will occur spontaneously. Methane decomposition is the carbon deposition process: CH4→C+2H2(ΔH°≈+75kJ / mol), which is easy to generate graphite or carbon nanotubes. In addition, since the CO content in the decarbonized coal gas is above 65%, the presence of Fe ions or Fe2O3 in the heating furnace provides a catalyst for the carbon deposition process of CO, and amorphous carbon or carbon fibers are generated in the temperature range of 200-600℃. In the process of these granular carbons being blown into the blast furnace through the tuyere, the volume of the accumulated carbon in the refractory material increases, causing cracks in the kiln masonry, and the accumulated carbon in the heat exchange refractory pipes blocks the heat exchange structure, which poses a great threat to the safe and stable operation of the system. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for inhibiting carbon deposition when mixed hydrogen-rich coal gas is heated in a heating furnace, so as to solve the problem that carbon deposition of mixed hydrogen-rich coal gas during heating in a heating furnace causes accumulation of granular carbon, resulting in cracking of the furnace body and clogging of equipment, thereby affecting the safe and stable operation of the system.

[0005] In order to achieve the above-mentioned purpose, the basic scheme provided by the present invention is: a device for suppressing carbon deposition of mixed hydrogen-rich coal gas heated by a heating furnace, comprising a coke oven, a tubular heat exchanger, a mixer, a hydrogen-rich carbon circulating oxygen blast furnace, a heating furnace, a PLC controller and a steam pipe, the gas outlet of the coke oven is connected to a coke oven gas pipe 1, the coke oven gas pipe 1 is connected to the tubular heat exchanger, the tubular heat exchanger is connected to a flue gas pipe, the tubular heat exchanger is connected to a coke oven gas pipe 2, the coke oven gas pipe 2 is connected to the mixer, the mixer is connected to a mixed gas pipe, and the mixing The combined gas pipe is connected to the hydrogen-rich carbon circulating oxygen blast furnace, the hydrogen-rich carbon circulating oxygen blast furnace is connected to the decarbonization unit, the decarbonization unit is connected to decarbonization gas pipe 1, the steam pipe is connected to decarbonization gas pipe 1, decarbonization gas pipe 1 is connected to the heating furnace, the heating furnace is connected to decarbonization gas pipe 2, decarbonization gas pipe 2 is connected to the mixer, the heating furnace is connected to the flue gas pipe, flow regulating valves are provided on the coke oven gas pipe 1, the flue gas pipe and the steam pipe, and a flow meter is provided on the decarbonization gas pipe 1. Each flow regulating valve is electrically connected to the PLC controller.

[0006] The principle and beneficial effects of the present invention are as follows: when in use, the coke oven gas and the flue gas are exchanged in a heat exchanger to increase the temperature of the coke oven gas, and then the decarbonized gas and water vapor are mixed, and then sent to the heating furnace for heating. The heated decarbonized gas and coke oven gas are mixed in the mixer, which avoids the methane in the coke oven gas mixed with hydrogen-rich gas from spontaneously generating graphite or carbon nanotubes when the temperature is higher than 1000°C during the heating process in the heating furnace. The mixer is a sleeve Lava tube type mixing structure with excellent sealing performance. The precise matching of the sleeve and the Lava tube and the multiple sealing design can effectively prevent medium leakage and is suitable for harsh working conditions such as high pressure and high corrosion, and the Lava tube can be disassembled and replaced separately; the flow regulating valve is a water-cooled high-temperature gate valve, which effectively prevents high-temperature creep deformation, material annealing softening, sealing surface burning and thermal stress cracking, thereby greatly improving the sealing reliability, operational flexibility and overall service life of the valve in ultra-high temperature environment.

[0007] Solution 2: The basic solution provided by the present invention is: a method for suppressing carbon deposition when a heating furnace heats mixed hydrogen-rich coal gas, comprising the following steps:

[0008] S1. The coke oven gas coming out of the coke oven is introduced into a tubular heat exchanger through a coke oven gas pipe. The flue gas coming out of the heating furnace is introduced into a tubular heat exchanger through a flue gas pipe, so that the coke oven gas and the flue gas are heat exchanged;

[0009] S2. The gas from the hydrogen-rich carbon cycle oxygen blast furnace passes through the decarbonization unit to form decarbonized gas. The PLC controller controls the flow control valve to pass water vapor through the steam pipe into the decarbonized gas pipe one;

[0010] S3. The decarbonized gas mixed with water vapor is sent to the heating furnace through a decarbonized gas pipe for heating;

[0011] S4. The coke oven gas in S1 and the decarbonized gas in S3 are fed into the mixer through the coke oven gas pipe 2 and the decarbonized gas pipe 2, respectively. The PLC controller controls the flow regulating valve to mix the coke oven gas and decarbonized gas in proportion to form a mixed hydrogen-rich gas.

[0012] S5. The mixed hydrogen-rich coal gas is fed into the hydrogen-rich carbon circulating oxygen blast furnace through the mixed coal gas pipe. The coke oven gas and flue gas are exchanged through a heat exchanger to prevent the methane in the coke oven gas from entering the heating furnace and causing high-temperature and low-temperature carbon deposition. Water vapor is introduced into the decarbonized coal gas. When carbon dioxide in the decarbonized coal gas deposits carbon at high temperatures, the water vapor oxidizes the deposited carbon into carbon monoxide, thereby reducing the carbon deposition of carbon dioxide in the decarbonized coal gas.

[0013] Option 3 is the preferred option of Option 2. In step S1, the coke oven gas temperature before heat exchange is 25-35°C, and the coke oven gas temperature after heat exchange is 140-160°C. During heat exchange, the flue gas at 200-300°C raises the coke oven gas temperature to 140-160°C, reducing carbon deposition of CO during transportation and recycling the heat energy of the waste flue gas.

[0014] Option 4: This is the preferred option of Option 2. In step S2, when the decarbonized coal gas flow rate is 10,000m 3 / h increased to 45,000 m 3 / h, the decarbonized coal gas flow rate increases at a rate of 200-300m 3 / h, when the steam flow rate increases from 100kg / h to 500kg / h, the steam flow rate increases at a rate of 2-3kg / h; when the decarbonized coal gas flow rate increases from 60,000m 3 / h increased to 200,000 m 3 / h, the decarbonized coal gas flow rate increases at a rate of 500-800m 3 / h, the steam flow rate increases from 100kg / h to 500kg / h, with a steam flow rate increase rate of 1.5-2kg / h. Water vapor is mixed into the decarbonized coal gas, which can oxidize the precipitated carbon particles into carbon monoxide, thereby reducing the accumulation of carbon particles that can cause furnace cracking and equipment blockage.

[0015] Option 5 is a preferred option of Option 2. In step S3, the temperature of the decarbonized coal gas before heating is 40-60°C, and the temperature of the decarbonized coal gas after heating is 1200-1450°C.

[0016] Option 6 is a preferred option of Option 2. In step S4, the ratio of coke oven gas to decarbonized gas is 1:6, and the temperature of the mixed hydrogen-rich gas is 1000-1200°C. The coke oven gas and decarbonized gas are mixed in a mixer at a ratio of 1:6 to form high-temperature hydrogen-rich gas. The high-temperature hydrogen-rich gas directly adds huge sensible heat to the furnace, alleviating the problem of insufficient temperature in the furnace bosh area caused by full oxygen operation, maintaining a high-temperature reaction environment, and a temperature greater than 1000°C to avoid cracking side reactions (such as 2CO→C+CO or CH4→C+2H), prevent carbon black deposition from clogging the pipeline, and ensure stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a device and method for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas according to the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below through specific embodiments:

[0019] The figure marks in the drawings of the specification include: 1. coke oven, 2. tubular heat exchanger, 3. mixer, 4. hydrogen-rich carbon circulating oxygen blast furnace, 5. heating furnace, 6. coke oven gas pipe 1, 7. coke oven gas pipe 2, 8. decarbonization gas pipe 1, 9. decarbonization gas pipe 2, 10. steam pipe, 11. mixed gas pipe, 12. decarbonization unit, 13. flue gas pipe, 14. flow regulating valve, 15. flow meter.

[0020] Example 1

[0021] like Figure 1 As shown: A device for suppressing carbon deposition of mixed hydrogen-rich coal gas heated in a heating furnace, comprising a coke oven 1, a tubular heat exchanger 2, a mixer 3, a hydrogen-rich carbon circulating oxygen blast furnace 4, a heating furnace 5, a PLC controller and a steam pipe 10. The gas outlet of the coke oven 1 is connected to a coke oven gas pipe 16, which is connected to the tubular heat exchanger 2, which is connected to a flue gas pipe 13, which is connected to a coke oven gas pipe 27, which is connected to the mixer 3. The mixer 3 is a sleeve-type lava tube mixing structure. The mixer 3 is connected to a mixed gas pipe 11, which is connected to the hydrogen-rich carbon circulating oxygen blast furnace 4. The blast furnace 4 is connected, the hydrogen-rich carbon circulating oxygen blast furnace 4 is connected to the decarbonization unit 12, the decarbonization unit 12 is connected to the decarbonization gas pipe 8, the steam pipe 10 is connected to the decarbonization gas pipe 8, the decarbonization gas pipe 8 is connected to the heating furnace 5, the heating furnace 5 is connected to the decarbonization gas pipe 29, the decarbonization gas pipe 29 is connected to the mixer 3, the heating furnace 5 is connected to the flue gas pipe 13, the coke oven gas pipe 6, the flue gas pipe 13 and the steam pipe 10 are all provided with a flow regulating valve 14, the flow regulating valve 14 is a water-cooled high-temperature gate valve, the decarbonization gas pipe 8 is provided with a flow meter 15, and each flow regulating valve 14 is electrically connected to the PLC controller.

[0022] The implementation method of this embodiment is as follows: when in use, the coke oven gas is first introduced into the tubular heat exchanger 2 through the coke oven gas pipe 16, the flue gas is sent into the tubular heat exchanger 2 through the flue gas pipe 13 for heat exchange with the coke oven gas to increase the temperature of the coke oven gas, and then the water vapor is mixed into the decarbonization gas pipe 18 through the steam pipe 10. After mixing, the water vapor is sent into the heating furnace 5 through the decarbonization gas pipe 8 for heating. The heated decarbonization gas and coke oven gas are respectively sent into the mixer 3 through the decarbonization gas pipe 29 and the coke oven gas pipe 27 for mixing to form a mixed hydrogen-rich gas. Finally, the mixed hydrogen-rich gas is sent to the hydrogen-rich carbon circulating oxygen blast furnace 4.

[0023] Example 2

[0024] A method for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas comprises the following steps:

[0025] S1. The coke oven gas from the coke oven 1 is introduced into the tubular heat exchanger 2 through the coke oven gas pipe 6, and the flue gas from the heating furnace 5 is introduced into the tubular heat exchanger 2 through the flue gas pipe 13, so that the coke oven gas and the flue gas are heat exchanged. The coke oven gas temperature before heat exchange is 25-35 ° C, and the coke oven gas temperature after heat exchange is 140-160 ° C;

[0026] S2. The gas from the hydrogen-rich carbon cycle oxygen blast furnace 4 passes through the decarbonization unit 12 to form decarbonized gas. The PLC controller controls the flow regulating valve 14 to pass water vapor through the steam pipe 10 into the decarbonized gas pipe 8. When the decarbonized gas flow rate is 10,000 m 3 / h increased to 45,000 m 3 / h, the decarbonized coal gas flow rate increases at a rate of 200-300m 3 / h, when the steam flow rate increases from 100kg / h to 500kg / h, the steam flow rate increases at a rate of 2-3kg / h; when the decarbonized coal gas flow rate increases from 60,000m 3 / h increased to 200,000 m 3 / h, the decarbonized coal gas flow rate increases at a rate of 500-800m 3 / h, the steam flow rate increases from 100kg / h to 500kg / h, and the steam flow rate increase rate is 1.5-2kg / h;

[0027] S3 decarbonized gas mixed with water vapor is sent to the heating furnace 5 through a decarbonized gas pipe 8 for heating. The decarbonized gas temperature before heating is 40-60 ℃, and the decarbonized gas temperature after heating is 1200-1450 ℃;

[0028] S4. The coke oven gas in S1 and the decarbonized gas in S3 are fed into the mixer 3 through the coke oven gas pipe 7 and the decarbonized gas pipe 9. The PLC controller controls the flow regulating valve 14 to mix the coke oven gas and the decarbonized gas in proportion, coke oven gas: decarbonized gas = 1:6, to form a mixed hydrogen-rich gas, the mixed hydrogen-rich gas temperature is 1000-1200 ℃;

[0029] S5. Send the mixed hydrogen-rich coal gas into the hydrogen-rich carbon circulating oxygen blast furnace 4 through the mixed coal gas pipe 11.

[0030] The implementation method of this embodiment is as follows: first, coke oven gas is introduced into the tubular heat exchanger 2, and the flue gas from the heating furnace 5 is introduced into the tubular heat exchanger 2, so that the coke oven gas and the flue gas are exchanged with each other, and the temperature of the coke oven gas before heating is increased from 25-35°C to 140-160°C. Then, water vapor is introduced into the decarbonized gas pipe 8 to mix the water vapor and the decarbonized gas. The mixed decarbonized gas is then sent to the heating furnace 5 for heating, and the temperature of the decarbonized gas is heated from 40-60°C to 1200-1450°C. The heated decarbonized gas is introduced into the mixer 3, and then the coke oven gas at 140-160°C is introduced into the mixer 3. The mixer 3 mixes the decarbonized gas and the coke oven gas to form a mixed hydrogen-rich gas, and then the mixed hydrogen-rich gas is introduced into the hydrogen-rich carbon circulating oxygen blast furnace 4.

[0031] Before the improvement, the decarbonized coal gas and the coke oven gas were mixed first, and then passed into the heating furnace 5 for heating. The probability of carbon deposition was more than 95%, and the maintenance cycle of the heating furnace pipeline was about 1 month. After the improvement, the coke oven gas and the decarbonized coal gas were heated separately, and then mixed after heating. The probability of carbon deposition was about 10%, and the maintenance cycle of the heating furnace pipeline was about 3 months.

[0032] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A device for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas, characterized in that: The invention comprises a coke oven (1), a tubular heat exchanger (2), a mixer (3), a hydrogen-rich carbon circulating oxygen blast furnace (4), a heating furnace (5), a PLC controller and a steam pipe (10), wherein the gas outlet of the coke oven (1) is connected to a coke oven gas pipe 1 (6), the coke oven gas pipe 1 (6) is connected to the shell-side inlet of the tubular heat exchanger (2), the tube-side inlet of the tubular heat exchanger (2) is connected to a flue gas pipe (13), the shell-side outlet of the tubular heat exchanger (2) is connected to a coke oven gas pipe 2 (7), the coke oven gas pipe 2 (7) is connected to the low-speed inlet of the mixer (3), the mixer (3) is connected to a mixed gas pipe (11), the mixed gas pipe (11) is connected to the outlet of the hydrogen-rich carbon circulating oxygen blast furnace (4), and the The hydrogen-rich carbon circulating oxygen blast furnace (4) is connected to a decarbonization unit (12), the decarbonization unit (12) is connected to a decarbonization gas pipe (8), the steam pipe (10) is connected to the decarbonization gas pipe (8), the decarbonization gas pipe (8) is connected to the heating furnace (5), the heating furnace (5) is connected to a decarbonization gas pipe (9), the decarbonization gas pipe (9) is connected to the high-speed inlet of the mixer (3), the heating furnace (5) is connected to the flue gas pipe (13), the coke oven gas pipe (6), the flue gas pipe (13) and the steam pipe (10) are all provided with flow regulating valves (14), the decarbonization gas pipe (8) is provided with a flow meter (15), and each flow regulating valve (14) is electrically connected to a PLC controller.

2. A method for inhibiting carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas, characterized in that: The following steps are involved: S1. The coke oven gas from the coke oven (1) is introduced into the tubular heat exchanger (2) through a coke oven gas pipe (6), and the flue gas from the heating furnace (5) is introduced into the tubular heat exchanger (2) through a flue gas pipe (13), so that the coke oven gas and the flue gas are heat exchanged; S2. The gas from the hydrogen-rich carbon cycle oxygen blast furnace (4) passes through the decarbonization unit (12) to form decarbonized gas. The PLC controller controls the flow regulating valve (14) to send water vapor through the steam pipe (10) into the decarbonized gas pipe (8); S3. The decarbonized gas mixed with water vapor is sent to the heating furnace (5) through a decarbonized gas pipe (8) for heating; S4. The coke oven gas in S1 and the decarbonized gas in S3 are respectively fed into the mixer (3) through the coke oven gas pipe 2 (7) and the decarbonized gas pipe 2 (9). The PLC controller controls the flow regulating valve (14) to mix the coke oven gas and the decarbonized gas in proportion to form a mixed hydrogen-rich gas; S5. Send the mixed hydrogen-rich coal gas into the hydrogen-rich carbon circulating oxygen blast furnace (4) through the mixed coal gas pipe (11).

3. A method for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas according to claim 2, characterized in that: In step S1, the temperature of the coke oven gas before heat exchange is 25-35°C, and the temperature of the coke oven gas after heat exchange is 140-160°C.

4. The method for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas according to claim 2, characterized in that: In step S2, when the decarbonized coal gas flow rate is 10,000m 3 / h increased to 45,000 m 3 / h, the decarbonized coal gas flow rate increases at a rate of 200-300m 3 / h, when the steam flow rate increases from 100kg / h to 500kg / h, the steam flow rate increases at a rate of 2-3kg / h; when the decarbonized coal gas flow rate increases from 60,000m 3 / h increased to 200,000 m 3 / h, the decarbonized gas flow rate increases at a rate of 500-800m 3 / h, the water vapor flow rate increases from 100kg / h to 500kg / h, and the water vapor flow rate increase rate is 1.5-2kg / h.

5. The method for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas according to claim 2, characterized in that: In step S3, the temperature of the decarbonized coal gas before heating is 40-60°C, and the temperature of the decarbonized coal gas after heating is 1200-1450°C.

6. The method for suppressing carbon deposition in a heating furnace when heating mixed hydrogen-rich coal gas according to claim 2, characterized in that: In step S4, the ratio of coke oven gas to decarbonized gas is 1:6, and the temperature of the mixed hydrogen-rich gas is 1000-1200°C.

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