JP2007009068A - System and method using reformed gas - Google Patents

Abstract

To effectively use carbon monoxide gas and hydrogen gas in reformed gas as chemical raw materials and to release carbon dioxide in the reformed gas to the atmosphere using a gas reforming furnace separately from the converter So that it can be used effectively without any problems.
In a gas reforming furnace 1, a combustible waste and / or its dry distillation by-product 8 and coal 10 are reacted with oxygen 9 to produce CO gas, H ₂ gas, CO ₂ gas, and N ₂ gas. A reformed gas containing is generated. The CO ₂ gas, CO gas, and H ₂ gas in the reformed gas are separated and recovered sequentially through the separation devices 2, 3, and 4. At least one of the recovered CO gas and H ₂ gas is sent as a chemical raw material to chemical substance synthesis facilities 6 and 7. The CO ₂ gas 14 is separated and recovered from the reformed gas in the previous step of the CO gas separation step, and is returned to the gas reforming furnace 1. The refluxed CO ₂ gas is used as an alternative to N ₂ gas for transporting coal and sealing the furnace transported to the gas reforming furnace.
[Selection] Figure 1

Description

  The present invention relates to a reformed gas utilization system for effectively using a reformed gas generated in a separate gas reforming furnace facility and a converter gas at an ironworks as a raw material for producing a chemical product (for example, acetic acid). The present invention relates to a system in which this reformed gas utilization system is combined with a converter gas system.

Inter-industrial energy system that sends carbon monoxide (CO) gas, which is by-produced in the steelworks converter, to a chemical manufacturing plant (chemical synthesis facility) and can be used as a raw material for chemicals such as acetic acid As an alternative to the converter, energy is used as a raw material for chemical products by installing a gas reformer facility separate from the converter at the ironworks to generate carbon monoxide gas and hydrogen (H ₂ ) gas. A system has been proposed.

Here, the conventional effective use of gas by-produced in the converter (sometimes referred to as “converter gas”) and the effective use of the reformed gas generated in the separate gas reforming furnace will be described. .
(Effective use of converter gas)
(1) About the effective use of the converter gas energy byproduced from the converter of a steelworks, it is known that it is utilized as the steam recovery by a recovery boiler and the fuel gas of a combustion facility. The gas temperature generated in the converter is higher than 1000 ° C., and the flue gas temperature may reach several thousand degrees. The hot gas sensible heat is usually exchanged by gas cooling using a water cooling jacket. The heat brought out by the circulating cooling water is dissipated into the atmosphere in the cooling tower. In addition, some sensible heat recovery equipment is installed at the top of the furnace to recover steam for effective use.

The converter gas inevitably contains carbon dioxide (CO ₂ ) and nitrogen (N ₂ ) in addition to useful gases such as carbon monoxide gas and hydrogen gas. Furthermore, iron dust accompanying oxygen blowing is included.

  Dusts and water-soluble gas are removed by a wet dust collector and the cleaned converter gas is sent to the gas holder as the gas to be recovered. Since the converter is a batch system that repeats insertion, melting, blowing, and tapping water in sequence, it is usually leveled slightly by operation of multiple units. However, since the generated gas is accompanied by a large flow rate variation, a gas holder is installed as a buffer for the generated gas amount variation.

  Since the recovered converter gas contains 50% or more of combustible components such as carbon monoxide and hydrogen, it can be used as an auxiliary fuel for heating furnaces and power generation facilities in steelworks. Corresponding to the case of converter gas generation exceeding the gas holder capacity, it is also an option to provide a buffer function by using it as auxiliary fuel for multiple facilities. For example, in a steelworks without blast furnace facilities, there is no generation of blast furnace gas or coke oven gas, so it is necessary to rely on converter gas as a by-product gas, and the necessity and required scale of the buffer function are large. Become.

  Moreover, paying attention to the fact that the carbon monoxide component occupies a majority in the converter gas, Patent Document 1 also discloses a method of supplying the recovered converter gas as a raw material gas to an adjacent chemical substance synthesis facility. Yes. As this effective utilization method, a method of producing acetic acid by arranging a facility for synthesizing acetic acid downstream of the converter gas recovery system and reacting carbon monoxide gas with methanol is shown.

As a method for separating the carbon monoxide gas from the converter gas, a two-stage pressure swing adsorption (PSA) method is known. In this method, carbon dioxide is first adsorbed and removed by first-stage pressure swing adsorption (PSA), and carbon monoxide is adsorbed by second-stage pressure swing adsorption (PSA). According to this method, the desorption recovery of the adsorbed carbon monoxide is performed under reduced pressure, so that high-purity carbon monoxide gas can be recovered (Non-Patent Document 1). The adsorption characteristics of the gas molecules constituting the converter gas are generally in descending order of molecular weight, and the adsorption characteristics of carbon monoxide and nitrogen are similar. Under such circumstances, in order to obtain high-purity carbon monoxide economically, it is known that it is effective to increase the carbon monoxide partial pressure at the front stage of the carbon monoxide separator ( Non-patent document 2). The molar molecular weights of carbon dioxide, carbon monoxide, nitrogen and hydrogen are 44, 28, 28 and 2, respectively.
(2) Gas amount fluctuation per hour when converter gas is generated becomes enormous. The reasons are as follows: (b) The furnace behavior within the converter cycle time is melting, decarburizing, blowing, etc., and the furnace is stopped and started intermittently. Even in this case, it is mentioned that each furnace operates independently. In addition, regarding the gas composition, it is difficult to maintain a constant carbon monoxide concentration from the above-described gas combustion control at the start / stop of melting / blowing. From the furnace, a mixed gas such as carbon monoxide and carbon dioxide produced by combustion and nitrogen used for bottom blowing is generated. In addition, when coal is input, hydrogen is also generated by thermal decomposition. In converters that use scraps and molds as raw materials, pulverized coal and waste tires and chips may be included in the auxiliary materials. Steel cords in waste tires can be used as iron raw materials, and rubber and other combustible components can be used as a substitute for bottom-blown pulverized coal, but sulfur (S) is also included in the gas.

It is known to provide a buffer function such as a gas storage tank for fluctuations in gas generation caused by batch operation which is the fate of converter gas. In response to the increasing demand for carbon monoxide and hydrogen as chemical raw materials, it is required to make the gas amount fluctuations associated with batch operations uniform. Moreover, the operation of the converter adopting the cold iron source melting method may be accompanied by calorie fluctuation of the generated gas. Therefore, it can be easily guessed that the capacity of the gas storage tank becomes enormous if the above-described uniform gas amount fluctuation is included in the uniform calorie fluctuation.
(Effective use of reformed gas)
A gas reforming furnace uses raw materials such as waste (carbon-containing products such as waste tires and plastics) and / or by-products (carbonized carbon, gas, oil) and coal accumulated in steelworks. It reacts with oxygen (partial combustion) to generate carbon monoxide gas and hydrogen gas, and these gases can be used as auxiliary fuel and chemical raw material.

  The reformed gas system is a waste gas or its by-products (carbonized, carbonized, oil, and gas) existing in the steelworks by installing a gas reforming furnace installed separately from the converter gas system. Is a system that can be used as a chemical raw material with higher added value. According to this system, it is possible to generate an energy surplus and to equip a buffer function with respect to a flow rate fluctuation caused by intermittent operation of the converter.

  In the gas reforming furnace, oxygen is reacted with energy-generating raw materials held in the steelworks, for example, by-products (carbonized carbon, oil, gas) after waste treatment such as waste tires and plastics, and coal. Nitrogen is used for the transfer of coal and dry distillation char to the gas reforming furnace and the seal gas in the gasification furnace.

The reformed gas generated in the gas reforming furnace is cooled by a heat exchanger. Thereafter, dusts in the reformed gas are removed by a gas purification facility, and impurities such as sulfur compounds such as hydrogen sulfide (H ₂ S) and carbonyl sulfide (COS) are removed. The refined reformed gas is used, for example, as an auxiliary fuel for a heating furnace and an auxiliary fuel for a power generation facility in a hot rolling mill as an application on the steel side. The reformed gas can be used as a raw material supply gas via a carbon monoxide separator and a hydrogen separator for chemical use.
(Other carbon monoxide production methods)
In order to produce carbon monoxide for a chemical raw material, a method using a gasifier using heavy oil as a raw material has been conventionally known. Heavy oil such as asphalt is supplied from oil refining plants and is not included in the category of raw materials used in steelworks, and it is necessary to secure dedicated raw materials. Therefore, it cannot be said that it is preferable from the energy supply and demand conditions in the steelworks. In this case, it is common for a chemical company that requires carbon monoxide to install a heavy oil gasifier.
JP 2000-283658 A Susumu Koizumi "Outline of CO gas recovery and purification equipment and operation results" Kawasaki Steel Technical Report 1986 Vol.18 No.3. Toshikazu Sakuratani “Development of High Purity CO Gas Generation and Separation System from Converter Gas” Kawasaki Steel Technical Report 1985 Vol.17 No.2

According to the method of generating reformed gas mainly composed of carbon monoxide with the converter gas recovery system and the separate gas reforming furnace equipment, the carbon monoxide flow rate, which has been a problem in the converter gas recovery system Enables the provision of buffer functions against fluctuations. In addition, problems such as escape from the shortage of converter gas energy as a chemical raw material and generation of energy surplus by utilizing unused energy can be solved. However, even in this method, the carbon dioxide separated in the pre-treatment of carbon monoxide separation and recovery cannot be effectively used, and there is a restriction on the purity of the carbon monoxide gas component due to the remaining nitrogen component in the reformed gas. Yes, there are still issues for economic improvement.
That is, in the case of a method for sequentially separating and recovering carbon dioxide, carbon monoxide, and hydrogen in the supply of chemical raw material gas by a gas reforming furnace system that is separate from the converter gas recovery system, the following technical problems There is.

  The first problem is that the separated carbon dioxide must be released into the atmosphere as off-gas or taken out of the office. From the viewpoint of measures for global environmental problems to reduce carbon dioxide emissions, it is desirable that carbon dioxide can be effectively used in steelworks.

  The second problem is that the nitrogen component still remains in the recovered gas from which carbon dioxide has been removed, and it is desired to reduce nitrogen from the viewpoint of increasing the carbon monoxide partial pressure. A third problem may be that a backup function is required for stable supply of chemical source gas.

  The present invention is basically configured as follows in order to solve the problems of the reformed gas utilization system.

  The reformed gas utilization system of the present invention reacts oxygen with combustible waste (for example, waste tires, waste plastics, etc.) and / or by-products (carbonized carbon, gas) and coal by a gas reforming furnace. Thus, it is assumed that a reformed gas composed of carbon monoxide, hydrogen, carbon dioxide, and nitrogen components similar to the converter gas is generated. And the system which isolate | separates and collect | recovers carbon dioxide gas in the front | former stage of carbon monoxide separation, and recirculates the carbon dioxide gas to a reforming furnace is provided.

  In this case, the carbon dioxide gas recirculated to the gas reforming furnace can be used as an alternative to nitrogen gas for coal transportation and furnace sealing. When carbon dioxide is refluxed to the gas reforming furnace, a part of it reacts with hydrogen in the gas reforming furnace, and carbon monoxide is purified by the following chemical formula, so the concentration of carbon dioxide in the reformed gas increases. On the other hand, a decrease in the concentration of carbon monoxide can be suppressed.

[Chemical 1]
CO ₂ + H ₂ → CO + H ₂ O
In addition, if the refined gas supply system recovered by the converter is connected to the reformed refined gas (CO or H ₂ ) supply system of the chemical substance synthesis facility (chemical product production facility), a reliable backup function for chemical raw materials can be provided. It becomes possible.

  According to the present invention, in the gas reforming furnace, carbon dioxide separated and recovered can be used as a substitute gas for nitrogen gas for coal transportation and furnace sealing. As a result, in addition to the effective use of recovered carbon dioxide in steelworks, the use of nitrogen gas for transportation and sealing is reduced, the carbon monoxide concentration in the carbon monoxide separator is increased, and the carbon monoxide recovery rate by PSA is increased. Can be increased.

  In a chemical substance synthesis facility, a backup function for a stable supply of chemical raw material gas can be exhibited by connecting a purified gas supply system of reformed gas and a converter recovery gas supply system.

Example 1
FIG. 1 is a configuration diagram of a reformed gas utilization system according to a first embodiment of the present invention.

  This system includes a gas reforming furnace facility 1, a gas purifier 2, a carbon dioxide separator 3, a carbon monoxide separator 4, and a hydrogen separator 5 from the upstream side toward the downstream side. These components are located in the steelworks. The carbon monoxide separator 4 is connected to an acetic acid production facility 6 at a chemical substance production plant via a carbon monoxide supply line 16. The hydrogen separator 5 is connected to the cyclohexane production facility 7 through a hydrogen supply line.

  The gas reforming furnace facility 1 is supplied with a waste by-product 8 from a waste treatment device (for example, a carbonization gasification device) 30 connected upstream thereof, and is supplied with an oxygen gas 9 from an oxygen gas supply system. The coal 10 is supplied from the coal supply system, and the nitrogen gas 11 is supplied from the nitrogen gas supply system.

  The waste by-product 8 is, for example, carbonized carbon, oil, gas, etc. generated by carbonizing a waste tire, and its use is expanded as a highly convenient gas by reforming. Coal 10 is a raw material that can be procured in a steel mill as a raw material for in-house power generation equipment such as coke raw material, converter raw material, and pulverized coal thermal power. The oxygen gas 9 has a production facility in a normal place as a blowing agent for the converter. Nitrogen gas 11 is used for conveying pulverized coal and for sealing inside the pressure vessel of the gas reforming furnace. However, in this embodiment, as will be described later, when the reformed gas 12 is generated and the carbon dioxide gas 14 therein is refluxed to the gas reforming furnace 1, this refluxed carbon dioxide is replaced with nitrogen gas ( For pulverized coal transportation and for sealing inside the furnace).

  The raw materials supplied to the gas reforming furnace facility 1 have a manufacturing facility or a storage facility in the steel mill, and are the same as the raw materials supplied to the converter.

  The gas reforming furnace equipment 1 reacts oxygen with waste by-products 8 (carbon, oil, gas) and coal 10 to produce a reformed gas 12 containing carbon, hydrogen, carbon dioxide, and nitrogen. Since it is a facility to be generated and the facility itself is a known structure, a detailed structure is omitted. Nitrogen is used for conveying fine coal to the gas reforming furnace and for shielding gas in the gasification furnace.

  The reformed gas 12 contains carbon monoxide as a main component and, as already described, contains hydrogen, carbon dioxide, and nitrogen as components, similar to the converter gas. Sulfur (S) content and impurities in the coal are removed by a dust removal process and a desulfurization process of the gas purification device 2.

  The operating pressure of the gas reforming furnace 1 is generally a pressurizing system in consideration of the operating pressure of the gas usage destination, and is usually selected to be about 1.5 to 3 MPa.

  The gas purification apparatus 2 is also a pressurization system, and is different from the purification equipment for by-product gas in the steelworks in terms of operating pressure. Further, since it is affected by the material, properties, and impurities contained in the gas reforming furnace raw material, it is necessary to plan the specifications of the gas purification apparatus 2 together with the gas reforming furnace equipment 1.

  It is generally said that the desulfurization process is economical at a reaction temperature below room temperature, and a gas sensible heat recovery boiler is installed in the gas reforming furnace 1 to cool the sensible heat and recover steam normally. It is done. The purified gas 13 is a pressurized gas. Carbon dioxide 14 is separated and recovered by the carbon dioxide separator 3 for the purpose of increasing the partial pressure of carbon monoxide and hydrogen, which are effective components as chemical raw material gases contained in the purified gas 13.

  For the separation of carbon dioxide, for example, a known chemical absorption method, physical absorption method, membrane separation method, pressure swing method or the like is employed.

  Carbon monoxide contained in the feed gas 15 after carbon dioxide separation is separated as high-purity carbon monoxide gas 16 by a carbon monoxide separation device 4 such as pressure swing adsorption (PSA), and used as a raw material for synthesizing acetic acid. The acetic acid production facility 6 is supplied via a line. The process for synthesizing acetic acid is also described in (Publication 1), and detailed description thereof is omitted here.

  The off-gas 17 after carbon monoxide separation separates most of carbon monoxide and carbon dioxide, resulting in a high hydrogen partial pressure, and the hydrogen gas 18 can be economically separated by the hydrogen separation device 5. Become. The separated hydrogen gas 18 is supplied to, for example, the cyclohexane production apparatus 7 and used as a chemical raw material. The purified gas 13 is separated and recovered in sequence from the carbon dioxide gas 14, the carbon monoxide gas 16, and the hydrogen gas 18, so that after the carbon monoxide is recovered, the hydrogen partial pressure of the feed gas is high, and the economy of the hydrogen separator 5 is economical. Can be recovered automatically.

  In the present embodiment shown in FIG. 1, a system in which both the carbon monoxide gas recovered by the carbon monoxide separator 4 and the hydrogen gas recovered by the hydrogen separator 5 are used as chemical raw materials is illustrated. However, the system may be configured so that at least one of the separated and recovered gases is used as a chemical raw material.

  In the above-described separate gas reforming furnace system, the recovered carbon dioxide gas 14 is refluxed to the gas reforming furnace equipment 1 and used as a substitute for the nitrogen 11 for transporting the coal (powder) 10. Carbon dioxide 14 is used as an in-furnace shield gas instead of nitrogen.

  Table 1 shows the results of trial calculation of effects when the recovered carbon dioxide 14 is used as a raw material transport or seal gas in the reforming furnace in place of the nitrogen 11 in the gas reforming furnace.

In the trial calculation example when nitrogen is used for conveyance and sealing as in the past, the component ratio of CO: N ₂ was 65: 9, but when the conveyance / seal nitrogen was replaced with carbon dioxide, The ratio was 67: 6, and the nitrogen partial pressure was reduced to 2/3, and the partial pressure ratio of nitrogen and carbon monoxide was greatly reduced from 1/7 to 1/11.

  As described above, according to the reformed gas utilization system according to the present embodiment, carbon for the feed of raw materials such as coal and nitrogen for sealing is replaced with carbon dioxide. There is an advantage that the carbon oxide concentration is increased by 2% or more and the ratio of nitrogen to carbon monoxide having the same molecular weight is 2/3 or less. This contributes to the carbon monoxide recovery rate 20 in the pressure swing adsorption (PSA) (see the relationship between the feed CO concentration and the CO recovery rate in FIG. 2), and enables an economical recovery purity increase. When carbon dioxide is refluxed to the gas reforming furnace, a part thereof reacts with hydrogen in the gas reforming furnace, and carbon monoxide is purified by the chemical formula 1 described above. The increase in concentration is suppressed, while the decrease in carbon monoxide concentration can be suppressed.

In the gas reforming furnace 1, combustible wastes such as waste tires and plastics may be directly input and reacted with oxygen to generate a reformed gas.
(Example 2)
FIG. 3 shows a reformed gas utilization system according to the second embodiment of the present invention. In this embodiment, a converter gas utilization system is further coupled to the reformed gas utilization system of the first embodiment described above. The raw material supply system of the acetic acid production facility 6 is connected to each of the carbon monoxide gas 16 recovered from the feed gas 15 from the gas reforming furnace installed separately from the converter and the carbon monoxide gas 26 recovered from the recovered converter gas 24. In addition, a method for providing a carbon monoxide raw material to the acetic acid production facility 6 from any gas by using a switching device is shown.
The converter gas generated in the converter (not shown) is stored in the gas storage holder 21 after purification. The converter gas 24 sent from the storage holder is sent to the carbon monoxide separator 23 as a feed gas 25 in which the carbon dioxide gas 28 is separated by the carbon dioxide separator 22 and the carbon monoxide partial pressure is increased. Here, the carbon monoxide gas 26 is separated and recovered, and the carbon monoxide is connected to a supply system of the carbon monoxide gas 16 of the acetic acid production facility 6 as a chemical raw material. The carbon monoxide gas of both the reformed gas and the converter gas has a switching device that can be switched and used. The carbon monoxide separator 23 contains a combustible component as an off-gas 27, and a part thereof can be used for combustion.

  Energy cooperation between the steel industry and the chemical industry adjacent to each other can increase the use of energy in the steelworks while supplying unused and surplus energy from the steel industry as raw materials for the chemical industry. In the future, it can be extended to supply energy to surrounding areas.

It is a system configuration diagram of one embodiment of the present invention. Example 1 Explanatory drawing which shows the effect of this invention It is a system configuration | structure figure which shows the other Example of this invention. (Example 2)

Explanation of symbols

1: Gas reforming furnace equipment, 2: Gas purification equipment, 3: Carbon dioxide separation equipment, 4: Carbon monoxide separation equipment, 5: Hydrogen separation equipment, 6: Acetic acid production equipment, 7: Cyclohexane production equipment, 8: Disposal Product by-products, 9: oxygen gas, 10: coal supply, 11: nitrogen gas, 12: reformed gas.

Claims (7)

A gas reforming furnace facility that is supplied with waste tires, waste plastics and / or waste and / or carbonization by-products, coal, oxygen, etc., and reforms some or all of these feedstocks to gasification materials ,
A gas purification device for removing impurities contained in the reformed gas generated in the gas reforming furnace facility;
A carbon dioxide separator that separates and recovers carbon dioxide in the reformed gas;
A carbon monoxide separator for separating and recovering carbon monoxide in the reformed gas after carbon dioxide separation;
A reforming gas utilization system including a hydrogen separation device that separates and recovers hydrogen in the reformed gas after carbon monoxide separation;
A system for using at least one of the carbon monoxide gas recovered by the carbon monoxide separator and the hydrogen gas recovered by the hydrogen separator as a chemical raw material gas;
And a system for recirculating the carbon dioxide gas removed by the carbon dioxide separator to the gas reforming furnace equipment.   In Claim 1, the system of carbon dioxide gas recirculated to the gas reforming furnace is used as an alternative to at least one nitrogen gas for transporting coal and for sealing a furnace transported to the gas reforming furnace. A reformed gas utilization system configured as described above. In Claim 1, it has the 1st carbon monoxide gas supply line for supplying the carbon monoxide gas recovered from the reformed gas with the carbon monoxide separation device to the chemical substance synthesis equipment,
Further, as a carbon monoxide supply system separate from the gas reforming furnace, a converter-type carbon monoxide separation device that separates and recovers carbon monoxide in the converter gas generated by the converter, and this recovered one Use of a reformed gas comprising a second carbon monoxide gas supply line connected to the chemical substance synthesis facility or the first carbon monoxide gas line to send the carbon oxide gas to the chemical substance synthesis facility system.   5. The chemical substance synthesis facility according to claim 3, wherein carbon monoxide gas separated and recovered from the reformed gas and carbon monoxide gas separated and recovered from the converter gas can be supplied in a switchable manner. Quality gas utilization system. Producing a reformed gas containing carbon monoxide gas, hydrogen gas, carbon dioxide gas and nitrogen gas by reacting combustible waste and / or its carbonization by-product and coal with oxygen in a gas reforming furnace; ,
A step of sequentially separating and recovering the carbon dioxide gas, carbon monoxide gas, and hydrogen gas;
A method of using a reformed gas comprising a step of sending at least one of the recovered carbon monoxide gas and hydrogen gas to a chemical synthesis facility as a chemical raw material,
A method of using a reformed gas, comprising a step of separating and recovering the carbon dioxide gas from the reformed gas in a step prior to the carbon monoxide gas separation step and refluxing it to the gas reforming furnace.   6. The step of refluxing carbon dioxide gas to the gas reforming furnace equipment according to claim 5, wherein the refluxing carbon dioxide gas is at least one nitrogen gas for transporting coal and for sealing a furnace transported to the gas reforming furnace. Reformed gas utilization method used as an alternative to   6. The process of separating and recovering carbon monoxide in the converter gas generated by the converter and the transport line of the recovered carbon monoxide gas directly connected to a chemical substance synthesis facility according to claim 5, or Connecting to a supply line of carbon monoxide gas separated and recovered from the quality gas and sending it to the chemical substance synthesis facility.

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