Short-process low-cost CO preparation method by converter gas2And high-value application system and process
Technical Field
The invention belongs to the technical field of steel smelting and CO2The field of preparation chemical industry, and relates to short-process low-cost CO preparation from converter gas2And high-value application systems and processes.
Background
CO2The emission accounts for more than 15% of industrial emission, so the steel industry seeks to reduce CO2CO emission or resource utilization2The new technology of (1) is not very slow. CO currently used in converters2The gas source is mainly recovered by a lime kiln and finished product CO2Supplying by tank car, recovering CO by lime kiln2The process is longer, the planning layout of the iron and steel enterprises is not facilitated, the investment cost and the operation cost are higher, and the finished product CO is2The tank car is not only high in cost but also not suitable for industrial production.
The top-blown gas of the converter is O2The bottom-blown gas is N2And Ar, because of the singleness of gas type selection, the smelting process of the converter can be controlled only by adjusting the oxygen lance operation lance position and the gas supply flow of top-bottom combined blowing, and a great deal of research at home and abroad shows that CO can be used for controlling the smelting process of the converter2The gas is used as the mixed gas of top-bottom combined blowing, so that the smelting cost can be reduced, and the product quality can be improved. Thus, an optimally obtained CO is selected2The scheme is very important for steel mills.
At present, low-calorific-value gas produced by converter smelting is subjected to diffusion treatment, so that not only energy waste but also environmental pollution are caused, and no effective treatment method is available at home and abroad so that the diffused gas can be utilized.
Disclosure of Invention
The invention aims to provide a short-flow low-cost method for preparing CO from converter gas2And a high-valued application process and system, which solve the problems of the prior art and technology.
The invention is realized by the following technical scheme: short-process low-cost CO preparation method by using converter gas2And a system for high-value application, wherein the system comprises a first oxygen pipeline, a converter top-blown gas mixer, an oxygen lance, a converter, a gas purification device, a gas storage tank, a gas boiler, a combustion-supporting gas mixer, a flue gas analyzer, a vent chimney, a steam pipeline, a first flue gas purification device, CO2Recovery and purification system, industrial grade CO2Pipeline, low heat value gas pipeline, second oxygen pipeline, compressed air pipeline and second flue gas purificationThe device comprises a converter bottom blowing gas mixer, an Ar pipeline, a circulating flue gas pipeline, a first oxygen pipeline and the industrial grade CO2The pipelines are all connected with the converter top-blown gas mixer, the converter top-blown gas mixer is connected with the oxygen lance, the oxygen lance is connected with the converter, the converter is connected with the gas purification device, one end of the gas purification device is connected with the gas storage tank, the other end of the gas purification device is connected with the low-calorific-value gas pipeline, the gas purification device and the low-calorific-value gas pipeline are both connected with the gas boiler, the second oxygen pipeline, the compressed air pipeline and the circulating flue gas pipeline are all connected with the combustion-supporting gas mixer, the gas boiler is respectively connected with the flue gas analyzer and the steam pipeline, the flue gas analyzer is respectively connected with the emptying chimney, the first flue gas purification device, the second flue gas purification device and the circulating flue gas pipeline, and the steam pipeline and the first flue gas purification device are both connected with the CO purification device and the CO pipeline2Recovery and purification system connection, said CO2Recovery and purification system and industrial grade CO2Pipe connection, said industrial grade CO2The pipeline, the second flue gas purification device and the Ar pipeline are all connected with the converter bottom blowing mixer, and the converter bottom blowing mixer is connected with the converter.
Further, steam generated from the gas boiler is supplied to the CO2The recovery and purification system is used to realize CO2The recovery and purification system operates at low cost;
furthermore, the type and the proportion of the combustion-supporting gas in the combustion-supporting gas mixer are dynamically adjusted according to the gas heat value of the gas storage tank and the low heat value gas pipeline;
further, the type and the proportion of bottom blowing of the converter bottom blowing mixer are dynamically adjusted according to the smelting stage of the converter and the steel grade;
the process and the system are suitable for recovering and purifying CO by a 60-350 ton converter and a chemical absorption method, a physical absorption method, a PSA method and a membrane separation method2。
The invention also aims to provide a method for preparing CO by using the system to realize short process and low cost of converter gas2And a high-value application process of smelting a converter1000-fold 8000kJ/Nm generated by smelting3Bleeding or recycling of gases and O of different calorific values2、O2+CO2、O2+ AIR or circulation flue gas different combustion-supporting gas mixed burning in gas boiler, after passing through flue gas analyzer, CO2The flue gas with the concentration lower than 40 percent is treated by the purification device and then is mixed with argon, and the mixing proportion is adjusted according to different smelting stages, so that the smelting cost can be reduced and the product quality can be improved; introducing CO2The flue gas with the concentration higher than 40 percent is treated by the purification device to be used as CO2The raw material gas of the purification system is recovered, and the CO can be reduced2Recovering and purifying system cost, and purifying the purified CO2The flue gas with the concentration of more than 40 percent is improved to the industrial grade CO of more than 99.8 percent2Then the mixture is mixed with oxygen evenly by a mixer according to smelting process conditions and then is used for smelting in a converter. CO is provided by low-pressure steam generated by combustion of converter gas and combustion-supporting gas in gas-fired boiler2And recovering the power of devices such as a cooler, a heat exchanger, a condenser and the like in the purification system. Increase of CO2The concentration of the raw material gas and the steam provided for the recovery and purification system reduce CO2The operation cost of the wet recovery and purification system is over 65 percent, and CO is reduced2The running cost of the dry recovery purification system is more than 50%.
Further, the process specifically comprises the following steps:
step 1: after gas generated by smelting in the converter passes through a gas purification device, converter gas with low calorific value enters a low calorific value gas pipeline, and converter gas with high calorific value enters a gas storage tank;
step 2: combusting the coal gas from the step 1 and the combustion-supporting gas from the combustion-supporting gas mixer in the gas boiler, wherein the mixed gas type in the combustion-supporting gas mixer comprises O2、O2+CO2、O2+AIR、O2+ circulating the flue gas;
and step 3: after the flue gas generated by combustion in the step 2 passes through a flue gas analyzer, CO is introduced into the flue gas analyzer2After being treated by a second flue gas purification device, the flue gas with the concentration of less than 40 percent is mixed with argon in a mixer according to different smelting stages to be used as converter bottom blowing gas; introducing CO2At a concentration of more than 40%The flue gas is treated by the first flue gas purification device to be used as CO2And recovering the raw material gas of the purification system. According to the operation of the whole system, the flue gas can be discharged from a flue gas discharge chimney;
and 4, step 4: the flue gas purified by the first flue gas purification device in the step 3 enters CO2The water scrubber in the recovery and purification system removes dust and cools, and then enters the absorption tower to enrich CO2Then enters a regeneration tower through a heat exchanger, the regenerated gas enters a condenser and then enters a gas-liquid separator, and CO is concentrated2The gas is pressurized by a compressor and then enters a dehydration dryer, and the dried industrial grade CO with the concentration of more than 99 percent2The gas enters a gas storage tank;
and 5: steam produced by the gas boiler mainly provides power for a cooler, a heat exchanger, a condenser and a reboiler;
step 6: industrial grade CO in step 32By industrial grade CO2And (4) pipeline conveying, namely conveying the combustion-supporting gas into the combustion-supporting gas mixer as the combustion-supporting gas, entering the converter bottom blowing gas mixer as the converter bottom blowing mixed gas or entering the converter bottom blowing gas mixer to be mixed with oxygen in the first oxygen pipeline as the converter top blowing mixed gas, and adjusting the gas mixing ratio according to different smelting stages or steel types.
Further, the concentration is greater than 40% CO2Flue gas and CO concentration greater than 40%2The flue gas is obtained by burning converter gas with low heat value and high heat value and different combustion-supporting gases in a gas-fired boiler.
Further, the concentration of CO in the low-heating value gas is less than 20 percent, and the CO is2Concentration less than 10%, N2The concentration is more than 60 percent; the CO concentration of the high-calorific-value gas is more than 20 percent, and the CO is2Concentration greater than 10%, N2The concentration is less than 40 percent;
further, the combustion-supporting gas is 100% O2、1%-99%O2+1%-99%CO2、 1%-99%O2+1%-99%AIR、1%-99%O2+ 1% -99% of circulating flue gas.
Further, the CO is2CO in flue gas with concentration less than 40%2Content of 5% -39%, N2The content is 61% -95%; CO 22CO in flue gas with concentration of more than 40%240% -90% of N2The content is 10% -60%;
further, the content of the converter bottom blowing mixed gas is 0-100% of Ar and 0-99.5% of CO2,0%-95%N2;
Further, the content of the converter top-blown mixed gas is 0-100% of O2,0%-50%CO2;
Further, the washing tower reduces the temperature of the flue gas to less than 60 ℃, the heat exchanger heats the rich solution to more than 80 ℃, the condenser cools the regeneration gas to less than 50 ℃, and CO after the gas-liquid separator2The concentration is more than 94%;
further, the steam is low-pressure steam, and the enthalpy value of the steam is 2000-4000 kJ/kg;
further, the process recovers and purifies CO2The running cost of the concentration of more than 99 percent is 0.1-0.7 yuan/Nm3;
The specific operation process of the method and the system is as follows:
before the system is initially operated, N is used2Purging a system pipeline and a storage tank; in the initial operating state, conventional top-blown O is used2Bottom blowing of N2Or Ar mode, low heat value gas generated in the smelting process and flue gas generated by combustion of combustion-supporting gas pass through a flue gas analyzer, and CO2The flue gas with the concentration of more than 40 percent enters CO2Recovery and purification system, CO2Flue gas with the concentration of less than 40 percent enters a purification device and then is mixed with Ar to be blown at the bottom of the converter; the generated high-heat value coal gas enters a coal gas storage tank, the outlet pressure of the coal gas storage tank can be mixed with combustion-supporting gas for combustion after reaching 6KPa, and the generated flue gas passes through a flue gas analyzer and then is subjected to CO2The flue gas with the concentration of more than 40 percent enters CO2Recovery and purification system, CO2Flue gas with the concentration of less than 40 percent enters a purification device and then is mixed with Ar to be blown at the bottom of the converter; CO 22Compressing the gas after the recovery and purification system to CO2In the gas storage tank, CO2The outlet pressure of the gas storage tank exceeds 2MPa, and the gas storage tank can be used as mixed combustion-supporting gas, converter bottom blowing mixed gas and converter top blowing mixed gas; from this point on, the invention is describedThe system of (2) implements a cyclic mode of operation.
The beneficial effects of the invention include:
(1) for preparing industrial grade CO2Provides a short-flow low-cost preparation process and system, effectively utilizes the low-heat value converter gas energy, and not only improves the supply of CO by a method of gas boiler mixed combustion2Recovering and purifying system raw material gas CO2The concentration and the high efficiency use of the steam generated by combustion as CO2The recovery and purification system provides power, thereby greatly reducing CO2The investment cost and the operation cost of the recovery and purification system.
(2) According to the practical situation of top-bottom combined blowing of the converter, industrial grade CO is provided for top blowing of the converter2To provide low concentration or industrial grade CO for bottom blowing2Realization of CO2The utilization of high value is realized.
(3) Dynamically adjusting CO according to different smelting stages and steel types2The top-bottom combined blowing mixing proportion not only reduces the smelting production cost, but also improves the steel quality.
Drawings
FIG. 1 shows that the converter gas short-process low-cost CO preparation method of the invention2And a schematic diagram of a high-valued application system.
FIG. 2 shows CO in the present invention2Schematic diagram of a recovery purification system.
In the figure: 1-a first oxygen pipeline, 2-a converter top-blown gas mixer, 3-an oxygen lance, 4-a converter, 5-a gas purification device, 6-a gas storage tank, 7-a gas boiler, 8-a combustion-supporting gas mixer, 9-a flue gas analyzer, 10-an emptying chimney, 11-a steam pipeline, 12-a first flue gas purification device, 13-CO2A recovery and purification system, 13-1-water washing tower, 13-2-absorption tower, 13-3-cooler, 13-4-heat exchanger, 13-5-regeneration tower, 13-6-condenser, 13-7-reboiler, 13-8-gas-liquid separator, 13-9-compressor, 13-10-dehydration drier, 13-11-gas storage tank, 14-industrial grade CO2The system comprises a pipeline, a 15-low heating value gas pipeline, a 16-second oxygen pipeline, a 17-compressed air pipeline, a 18-second flue gas purification device, a 19-converter bottom blowing gas mixer, a 20-Ar pipeline and a 21-circulating flue gas pipeline.
Detailed Description
For the purpose of making the object, technical solution and advantages of the present invention clearer, the following description will be made with reference to the accompanying drawings and examples.
As shown in figures 1 and 2, the short-flow and low-cost preparation of CO by using converter gas2And a high-value application system, which comprises a first oxygen pipeline 1, a converter top-blown gas mixer 2, an oxygen lance 3, a converter 4, a gas purification device 5, a gas storage tank 6, a gas boiler 7, a combustion-supporting gas mixer 8 for mixing different types of combustion-supporting gas, a flue gas analyzer 9 after combustion of the gas boiler, an emptying chimney 10, a steam pipeline 11, a first flue gas purification device 12, CO2Recovery and purification System 13, Industrial grade CO2A pipeline 14, a low heating value gas pipeline 15, a second oxygen pipeline 16, a compressed air pipeline 17, a second flue gas purification device 18, a converter bottom blowing gas mixer 19, an Ar pipeline 20 and a circulating flue gas pipeline 21;
wherein said CO is2The recovery and purification system 13 includes: 13-1 parts of a water washing tower, 13-2 parts of an absorption tower, 13-3 parts of a cooler, 13-4 parts of a heat exchanger, 13-5 parts of a regeneration tower, 13-6 parts of a condenser, 13-7 parts of a reboiler, 13-8 parts of a gas-liquid separator, 13-9 parts of a compressor, 13-10 parts of a dehydration dryer and 13-11 parts of a gas storage tank;
the first oxygen pipeline 1 and the technical grade CO2The pipelines 14 are all connected with the converter top-blown gas mixer 2, the converter top-blown gas mixer 2 is connected with the oxygen lance 3, the oxygen lance 3 is connected with the converter 4, the converter 4 is connected with the gas purification device 5, one end of the gas purification device 5 is connected with the gas storage tank 6, the other end of the gas purification device 5 is connected with the low-calorific-value gas pipeline 15, the gas purification device 5 and the low-calorific-value gas pipeline 15 are both connected with the gas boiler 7, the second oxygen pipeline 16, the compressed air pipeline 17 and the circulating flue gas pipeline 21 are all connected with the gas boiler 7, the gas boiler 7 is respectively connected with the flue gas analyzer 9 and the steam pipeline 11, the flue gas analyzer 9 is respectively connected with the emptying chimney 10, the first flue gas purification device 12, the second flue gas purification device 18 and the circulating flue gas pipeline 21, and the steam pipeline 11, The first flue gas cleaning device 12 is all in contact with CO2Recovery and purification system 13 is connected withThen, the CO is2Recovery and purification system 13 and industrial grade CO2Pipe 14, the industrial grade CO2The pipeline 14, the second flue gas purification device 18 and the Ar pipeline 20 are all connected to the converter bottom blowing gas mixer 19, and the converter bottom blowing gas mixer 19 is connected to the converter 4.
The CO is2The recovery and purification system 13 comprises a water washing tower 13-1 for washing flue gas and enriching CO213-2 of the absorption tower, 13-4 of the heat exchanger for exchanging heat of the lean and rich liquid, CO2Regenerated regeneration tower 13-5, condenser 13-6, CO2A gas-liquid separator 13-8 for separating gas and liquid, a compressor 13-9, a dehydration dryer 13-10 for storing CO213-11 of the air storage tank.
Short-process low-cost CO preparation method by using converter gas2And a high-valued application process, which comprises the following steps:
step 1: after gas generated by smelting in the converter 4 passes through a gas purification device 5, converter gas with low calorific value enters a low calorific value gas pipeline 15, and converter gas with high calorific value enters a gas storage tank 6;
step 2: combusting the coal gas from step 1 and combustion-supporting gas from combustion-supporting gas mixer (8) in gas boiler 7, wherein the type of gas mixture in combustion-supporting gas mixer 8 comprises O2、O2+CO2、 O2+AIR、O2+ circulating the flue gas;
and step 3: after the flue gas generated by combustion in the step 2 passes through a flue gas analyzer 9, CO is introduced into the flue gas2After being treated by the second flue gas purification device, the flue gas with the concentration of less than 40 percent is mixed with argon in a converter bottom blowing mixer 19 according to different smelting stages to be used as converter bottom blowing gas after being mixed 18; introducing CO2The flue gas with the concentration of more than 40 percent is treated by the first flue gas purification device 12 to be used as CO2The feed gas of the purification system 13 is recovered. According to the operation of the whole system, the flue gas emptying chimney 10 can be emptied;
and 4, step 4: the flue gas purified by the first flue gas purification device 12 in the step 3 enters CO2The water scrubber 13-1 in the recovery and purification system 13 removes dust and cools, and then enters the absorption tower 13-2 to enrich CO2Then passes through the heat exchanger 13-4 enter a regeneration tower 13-5, the regeneration gas enters a condenser 13-6 and then enters a gas-liquid separator 13-8, and the concentrated CO2The gas is pressurized by a compressor 13-9 and then enters a dehydration dryer 13-10, and the dried industrial grade CO with the concentration of more than 99 percent2The gas enters a gas storage tank 13-11;
and 5: the steam generated by the gas boiler 7 mainly provides power for the cooler 13-3, the heat exchanger 13-4, the condenser 13-6 and the reboiler 13-7;
step 6: industrial grade CO in step 32By industrial grade CO2And (3) delivering the mixture as combustion-supporting gas into a combustion-supporting gas mixer 8, entering a converter bottom blowing mixer 19 to be converter bottom blowing gas or entering a converter top blowing gas mixer 2 to be mixed with oxygen in a first oxygen pipeline 1 to be converter top blowing gas, and adjusting the gas mixing ratio according to different smelting stages or steel types.
Example (b):
in the embodiment, the process is applied to a 150-ton converter, and the average calorific value of the coal gas at the early stage and the later stage of the converter smelting is 1644KJ/Nm3For increasing the amount of steam and CO in the flue gas2Concentration of (2), combustion-supporting mixed 90% O2+ 10% AIR as combustion-supporting gas, and obtaining CO from the flue gas after combustion in the gas boiler by a flue gas analyzer2Concentration 33.6%, N2The concentration is 64.7%, the mixture can be directly used as bottom blowing gas in the early stage of converter smelting after being purified by a purifying device, and 50% of Ar is mixed in the later stage of converter smelting to be used as bottom blowing gas; the average heat value of the coal gas in the middle smelting period is 5819KJ/Nm3In order to effectively utilize the circulating flue gas and reduce the emission of NOx, the combustion-supporting device is mixed with 60 percent of O2+ 40% of circulating flue gas is used as combustion-supporting gas, and the flue gas after combustion in the gas-fired boiler is passed through a flue gas analyzer to obtain CO2The concentration is 63.2 percent, and the flue gas enters CO after being treated by a purifying device2The recovery and purification system outputs industrial grade CO2And the pressure is increased to more than 2MPa by a compressor, and the combustion-supporting gas is used for top-bottom combined blowing of the converter and converter gas. The example proves that the converter gas short-process low-cost CO preparation method2And high-valued application process and CO in system2The recovery and purification system recovers and purifies CO compared with the lime kiln tail gas2And CO2Tanker for supplying CO2The operation cost is reduced by more than 70 percent, and the main reasons are that the steam generated by a combustion boiler is efficiently utilized and CO in the raw material gas2The concentration is increased. Selecting reasonable combustion ratio of converter gas and combustion-supporting gas to realize CO2The proper top-bottom combined blown CO is selected according to different smelting stages2The mixed model not only reduces the consumption of steel materials, but also improves the dephosphorization efficiency and reduces the content of N in steel.
Table 1 shows the flue gas composition of the combustion and purification of different types of combustion-supporting gas in the middle stage of combustion smelting.
TABLE 1
The specific cycle operation process of the method and the system provided by the invention is as follows:
before the system is initially operated, N is used2Purging a system pipeline and a storage tank; in the initial operating state, conventional top-blown O is used2Bottom blowing of N2Or Ar mode, low heat value gas generated in the smelting process and flue gas generated by combustion of combustion-supporting gas pass through a flue gas analyzer, and CO in the flue gas2The concentration is less than 40%, and after entering the purification device, the mixture is directly used as bottom blowing gas of the converter in the early smelting period and is mixed with Ar to be used as converter bottom blowing gas in the later smelting period; the high-heat value coal gas generated by smelting in the converter enters a coal gas storage tank, the outlet pressure of the coal gas storage tank can be mixed with combustion-supporting gas for combustion after reaching 6KPa, and the generated flue gas passes through a flue gas analyzer, and CO in the flue gas2Into CO at a concentration of more than 40%2A recovery and purification system, a compressor compressing the gas to CO2In the gas storage tank, CO2The outlet pressure of the gas storage tank exceeds 2MPa, and the gas storage tank can be used as mixed combustion-supporting gas, converter bottom blowing mixed gas and converter top blowing mixed gas; from this point on, the system of the present invention implements the loopLoop operating mode.
The above embodiments are only examples of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.