Method for producing organic substance and organic substance production apparatus

Abstract

The present invention provides a method for producing an organic substance and an apparatus for producing an organic substance, said method and apparatus being capable of efficiently cooling a synthesis gas and converting the synthesis gas into an organic substance with high conversion efficiency by utilizing a microbial catalyst.　This method for producing an organic substance comprises: a step wherein a synthesis gas G1 discharged from a gasification device 2 is cooled by being passed through a heat exchanger 20; a step wherein the synthesis gas G1 cooled by the heat exchanger 20 is passed through a gas cooling tower 21, thereby being cooled by water sprayed within the gas cooling tower 21; and a step wherein the synthesis gas G1, which has been passed through at least the heat exchanger 20 and the gas cooling tower 21, is brought into contact with a microbial catalyst, thereby producing an organic substance.

Description

Technical Field

[0001] The present invention relates to a method for producing an organic substance using synthesis gas as a raw material, and an apparatus for producing an organic substance using synthesis gas as a raw material.

Background Art

[0002] Regarding various wastes such as industrial wastes and general wastes, a technique is widely known in which after generating gas by pyrolysis in a gasification furnace, the gas generated in a reforming furnace is reformed to obtain synthesis gas. The obtained synthesis gas is either burned as it is and used for power generation or the like, or heat is recovered by a boiler or the like as necessary and then used for power generation or the like. In recent years, attempts have also been made to use synthesis gas as a chemical synthesis raw material. For example, attempts have been made to convert it into an organic substance such as ethanol using a microbial catalyst (see, for example, Patent Document 1).

[0003] The synthesis gas obtained in the gasification furnace and the reforming furnace contains a large amount of impurities such as tar components and is difficult to use directly for power generation and chemical synthesis. Therefore, gas purification is generally performed. In gas purification, it is known that the synthesis gas is appropriately cooled. As a means for cooling the synthesis gas, a means of spraying water into the gas stream and using the latent heat of vaporization of water to cool the synthesis gas is generally used. However, the temperature of the synthesis gas obtained in the gasification furnace and the reforming furnace is high, and a large amount of water is required to cool the synthesis gas by spraying water, resulting in a large amount of wastewater generation. Therefore, as a method for cooling the synthesis gas, a method including means other than spraying water has been proposed (see, for example, Patent Documents 2 to 4). Patent Document 2 discloses that biomass is gasified at high temperature and normal pressure, and the gasified synthesis gas is introduced from a gas furnace through a water cooling pipe into a quench tower, where the crude synthesis gas is cooled by spray water in the quench tower. Patent Document 3 discloses a method including a cooling step using an indirect heat exchanger for the synthesis gas produced by gasification, a tar removal step, a cooling step using a tar removal device, and a cooling step using water spray in a spray tower. Patent Document 4 discloses a method including a cooling step of cooling a synthesis gas in a first heat exchanger and spraying cooling water in a spray tower onto the synthesis gas cooled by the first heat exchanger. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 037710 [Patent Document 2] Special Publication No. 2015-510522 [Patent Document 3] JP 2009-298825 A [Patent Document 4] JP 2014-227450 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the synthesis gas is used as a raw material for organic synthesis, the temperature may need to be strictly controlled. For example, when converting the synthesis gas into organic substances such as ethanol using a microbial catalyst, the synthesis gas needs to be cooled to a temperature of 40° C. or less to prevent the microbial catalyst from dying.

[0006] However, when the synthesis gas is used for power generation, etc., strict temperature control is not required. Therefore, even if the conventional synthesis gas purification methods described in Patent Documents 2 to 4 are directly applied to the case where a microbial catalyst is used, it is difficult to synthesize organic substances with high conversion efficiency. In addition, conventional methods for cooling synthesis gas generally involve blowing in nitrogen or air, but when using a microbial catalyst, contamination of the synthesis gas with nitrogen or air reduces the conversion efficiency of organic matter.

[0007] Therefore, an object of the present invention is to provide a method for producing an organic substance and an apparatus for producing an organic substance that can efficiently cool synthesis gas and convert the synthesis gas into an organic substance with high conversion efficiency using a microbial catalyst.

Means for Solving the Problems

[0008] As a result of intensive studies, the present inventors have found that the above problems can be solved by cooling synthesis gas with a heat exchanger, cooling the synthesis gas cooled by the heat exchanger with water sprayed inside a gas cooling tower, and bringing the cooled synthesis gas into contact with a microbial catalyst to produce an organic substance, and have completed the following present invention. That is, the present invention provides the following [1] to

[18] . [1] A step of cooling the synthesis gas discharged from a gasifier by passing it through a heat exchanger; a step of cooling the synthesis gas cooled by the heat exchanger by passing it through a gas cooling tower and cooling it with water sprayed inside the gas cooling tower; and a step of bringing the synthesis gas that has passed through at least the heat exchanger and the gas cooling tower into contact with a microbial catalyst to produce an organic substance. A method for producing an organic substance. [2] The method for producing an organic substance according to [1], wherein the temperature of the synthesis gas discharged from the gasifier is 900°C or higher. [3] The method for producing an organic substance according to [1] or [2], wherein the synthesis gas is cooled to a temperature of 200°C or higher and 300°C or lower by the heat exchanger. [4] Further including a step of passing the synthesis gas cooled by the gas cooling tower through a filter-type dust collector, and bringing the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, and the filter-type dust collector into contact with a microbial catalyst to produce an organic substance. The method for producing an organic substance according to any one of [1] to [3]. [5] Further including a step of passing the synthesis gas cooled by the gas cooling tower through a water scrubber, and bringing the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, and the water scrubber into contact with a microbial catalyst to produce an organic substance. The method for producing an organic substance according to any one of [1] to [4]. [6] The method for producing an organic substance according to [5], wherein the synthesis gas that has passed through the heat exchanger, the gas cooling tower, the filtration type dust collector, and the water scrubber in this order is brought into contact with a microbial catalyst to produce an organic substance. [7] The method for producing an organic substance according to [5] or [6], wherein the synthesis gas is cooled to 40°C or lower by the water scrubber. [8] The method for producing an organic substance according to any one of [1] to [7], further including a step of distilling the organic substance, and using the thermal energy obtained from the synthesis gas by the heat exchanger for distillation. [9] The method for producing an organic substance according to any one of [1] to [8], wherein the organic substance contains ethanol.

[10] An organic substance production apparatus including a gasification device that generates synthesis gas, a heat exchanger that cools the synthesis gas discharged from the gasification device by passing it through, a gas cooling tower that cools the synthesis gas cooled by the heat exchanger by passing it through and performing water spraying, and an organic substance generation unit that brings the synthesis gas that has passed through at least the heat exchanger and the gas cooling tower into contact with a microbial catalyst to produce an organic substance.

[11] The organic substance production apparatus according to

[10] , wherein the temperature of the synthesis gas discharged from the gasification device is 900°C or higher.

[12] The organic substance production apparatus according to

[10] or

[11] , wherein the synthesis gas is cooled to a temperature of 200°C or higher and 300°C or lower by the heat exchanger.

[13] Further including a filtration type dust collector that is disposed downstream of the gas cooling tower and through which the synthesis gas cooled by the gas cooling tower passes, and the organic substance generation unit brings the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, and the filtration type dust collector into contact with the microbial catalyst to produce an organic substance. The organic substance production apparatus according to any one of

[10] to

[12] .

[14] Further including a water scrubber that is disposed downstream of the gas cooling tower and through which the synthesis gas cooled by the gas cooling tower passes, and the organic substance generation unit brings the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, and the water scrubber into contact with the microbial catalyst to produce an organic substance. The organic substance production apparatus according to any one of

[10] to

[13] .

[15] The organic substance production unit of the organic substance manufacturing apparatus according to

[14] , which generates an organic substance by bringing the synthesis gas that has passed through the heat exchanger, the gas cooling tower, the filtration type dust collector, and the water scrubber in this order into contact with the microbial catalyst.

[16] The organic substance manufacturing apparatus according to

[14] or

[15] , which cools the synthesis gas to 40°C or lower with the water scrubber.

[17] The organic substance manufacturing apparatus according to any one of

[10] to

[16] , further comprising a distillation apparatus for distilling the organic substance, wherein the distillation apparatus utilizes the thermal energy obtained from the synthesis gas by the heat exchanger for distillation.

[18] The organic substance manufacturing apparatus according to any one of

[10] to

[17] , wherein the organic substance contains ethanol.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a method for manufacturing an organic substance and an organic substance manufacturing apparatus that can efficiently cool synthesis gas and convert the synthesis gas into an organic substance with high conversion efficiency using a microbial catalyst.

Brief Description of the Drawings

[0010]

Figure 1

Embodiments for Carrying Out the Invention

[0011] The present invention will be described using embodiments with reference to the drawings. FIG. 1 shows an organic substance manufacturing apparatus according to an embodiment of the present invention. Hereinafter, with reference to the embodiments, the organic substance manufacturing apparatus and the method for manufacturing an organic substance according to the embodiments of the present invention will be described in detail.

[0012] The organic substance manufacturing apparatus 1 includes a gasification apparatus 2 that gasifies waste to generate synthesis gas G1, a processing unit 3 that performs a process including at least a purification process on the synthesis gas G1 discharged from the gasification apparatus 2, and an organic substance generation unit 30 that generates an organic substance by bringing the synthesis gas (hereinafter also referred to as "purified synthesis gas G2") obtained by being processed by the processing unit 3 into contact with a microbial catalyst.

[0013] (Gasification apparatus) As the waste gasified in the gasification apparatus 2, industrial waste such as industrial solid waste may be used, or general waste such as municipal solid waste (MSW) may be used, and combustible substances such as plastic waste, food waste, waste tires, biomass waste, food waste, building materials, wood, wood chips, fibers, and paper can be mentioned. Among these, municipal solid waste (MSW) is preferred.

[0014] The gasification apparatus 2 includes a gasification furnace 10 and a reforming furnace 11. The gasification furnace 10 is not particularly limited, and examples thereof include a kiln gasification furnace, a fixed bed gasification furnace, and a fluidized bed gasification furnace. In addition to waste, oxygen or air, and further steam as required are introduced into the gasification furnace 10. The gasification furnace 10 heats the waste at, for example, 500 to 700 °C to pyrolyze it, and appropriately performs partial oxidation to gasify it. The pyrolysis gas contains not only carbon monoxide and hydrogen but also gaseous tar, powdered char, and the like. The pyrolysis gas is supplied to the reforming furnace 11. In addition, solids generated as incombustibles in the gasification furnace 10 are appropriately recovered.

[0015] In the reforming furnace 11, the pyrolysis gas obtained in the gasification apparatus 2 is reformed to obtain synthesis gas G1. In the reforming furnace 11, the content of at least one of hydrogen and carbon monoxide in the pyrolysis gas increases and is discharged as synthesis gas G1. In the reforming furnace 11, for example, tar, char, and the like contained in the pyrolysis gas are reformed into hydrogen, carbon monoxide, and the like. The temperature of the synthesis gas G1 in the reforming furnace 11 is not particularly limited, but for example, it is 900°C or higher, preferably 900°C or higher and 1,300°C or lower, more preferably 1,000°C or higher and 1,200°C or lower. By setting the temperature in the reforming furnace 11 within the above range, it becomes easier to obtain the synthesis gas G1 with a high content of carbon monoxide and hydrogen.

[0016] The temperature of the synthesis gas G1 discharged from the reforming furnace 11 (i.e., the gasification device 2) is the same as the temperature of the above synthesis gas G1, and for example, it is 900°C or higher, preferably 900°C or higher and 1,300°C or lower, more preferably 1,000°C or higher and 1,200°C or lower. The synthesis gas G1 discharged from the reforming furnace 11 (i.e., the gasification device 2) contains carbon monoxide and hydrogen. Further, the synthesis gas G1 contains, for example, 0.1% by volume or more and 80% by volume or less of carbon monoxide and 0.1% by volume or more and 80% by volume or less of hydrogen. The carbon monoxide concentration in the synthesis gas G1 is preferably 10% by volume or more and 70% by volume or less, more preferably 20% by volume or more and 55% by volume or less. Also, the hydrogen concentration in the synthesis gas G1 is preferably 10% by volume or more and 70% by volume or less, more preferably 20% by volume or more and 55% by volume or less.

[0017] In addition to hydrogen and carbon monoxide, the synthesis gas G1 may contain carbon dioxide, nitrogen, oxygen, etc. The carbon dioxide concentration in the synthesis gas G1 is not particularly limited, but preferably it is 0.1% by volume or more and 40% by volume or less, more preferably 0.3% by volume or more and 30% by volume or less. It is particularly preferable to lower the carbon dioxide concentration when ethanol is produced by a microbial catalyst, and from such a viewpoint, it is more preferably 0.5% by volume or more and 25% by volume or less. The nitrogen concentration in the synthesis gas G1 is usually 40% by volume or less, preferably 1% by volume or more and 20% by volume or less. Also, the oxygen concentration in the synthesis gas G1 is usually 5% by volume or less, preferably 1% by volume or less. Also, the lower the oxygen concentration, the better, and it may be 0% by volume or more. However, generally, oxygen is often unavoidably contained, and the oxygen concentration is practically 0.01% by volume or more.

[0018] The concentrations of carbon monoxide, carbon dioxide, hydrogen, nitrogen, and oxygen in the synthesis gas G1 can be set within a predetermined range by appropriately changing combustion conditions such as the type of waste, the temperatures of the gasifier 10 and the reformer 11, and the oxygen concentration of the feed gas supplied to the gasifier 11. For example, when it is desired to change the carbon monoxide or hydrogen concentration, the waste is changed to a waste with a high ratio of hydrocarbons (carbon and hydrogen) such as waste plastic, and when it is desired to reduce the nitrogen concentration, there is a method of supplying a gas with a high oxygen concentration to the gasifier 10. Furthermore, the synthesis gas G1 may be appropriately adjusted in terms of the concentration of each component of carbon monoxide, carbon dioxide, hydrogen, and nitrogen. The concentration adjustment may be performed by adding at least one of these components to the synthesis gas G1. Note that the volume percentages of the respective substances in the synthesis gas G1 described above mean the volume percentages of the respective substances in the synthesis gas G1 discharged from the gasification apparatus 2.

[0019] In the above description, the gasification apparatus 2 has been described in a mode including the gasifier 10 and the reformer 11. However, the configuration of the gasification apparatus 2 is not limited to these, and it may be an apparatus in which the gasifier and the reformer are integrated, or any type of gasification apparatus as long as it can generate the synthesis gas G1.

[0020] (Processing unit) As shown in FIG. 1, the processing unit 3 in the present embodiment includes at least a heat exchanger 20 and a gas cooling tower 21. The processing unit 3 further includes a filter type dust collector 22 downstream of the gas cooling tower 21. The processing unit 3 further includes a water scrubber 23 downstream of the gas cooling tower 21. In this specification, "downstream" means the downstream along the gas supply flow of the synthesis gas G1. Also, "upstream" means the upstream along the supply flow of the synthesis gas G1. The supply flow of the synthesis gas G1 means the flow of the synthesis gas G1 from when it is discharged from the gasification apparatus 2 until it is introduced into the organic substance generation unit 30.

[0021] <Heat exchanger> The synthesis gas G1 discharged from the gasifier 2 passes through the heat exchanger 20. The heat exchanger 20 is a device that cools the synthesis gas G1 using a heat medium. The heat exchanger 20 cools the synthesis gas G1 by transferring the thermal energy of the synthesis gas G1 to the heat medium. Preferably, a boiler is used as the heat exchanger 20. A boiler is a device that circulates water as a heat medium inside and heats the circulated water with the thermal energy of the synthesis gas G1 to generate steam. When a boiler is used as the heat exchanger 20, it becomes possible to easily heat other devices with the steam generated in the boiler, and the thermal energy of the synthesis gas G1 can be easily reused.

[0022] However, the heat exchanger 20 can also use other than a boiler and may have any configuration as long as it transfers thermal energy from the synthesis gas G1 to the heat medium, but a partition method in which the synthesis gas G1 and the heat medium do not come into direct contact is preferred. The heat medium may be either a gas or a liquid, or may involve a phase change between a gas and a liquid. Further, the heat medium may have thermal energy transferred from the synthesis gas G1 while passing through a flow path having any shape such as a tubular shape or a plate shape.

[0023] As described above, the synthesis gas G1 discharged from the gasifier 2 reaches a high temperature of, for example, 900 °C or higher. Therefore, the synthesis gas G1 is cooled by the heat exchanger 20 and supplied to the gas cooling tower 21 at a relatively low temperature, preventing excessive cooling in the gas cooling tower 21. Therefore, the amount of water sprayed onto the synthesis gas G1 in the gas cooling tower 21 can be reduced, and it is no longer necessary to supply the synthesis gas G1 with a high water content to the filter type dust collector 22 and the water scrubber 23. Therefore, the amount of water transferred from the gas cooling tower 21 to the water scrubber 23 can be suppressed, and it is also possible to prevent excessive water aggregation in the filter type dust collector 22.

[0024] As described above, the heat exchanger 20 cools the synthesis gas supplied at a high temperature of, for example, 900°C or higher to a temperature of, for example, 200°C or higher and 300°C or lower, preferably 240°C or higher and 280°C or lower, and supplies it to the gas cooling tower 21. By cooling to 200°C or higher, precipitation of impurities in the synthesis gas G1 can be prevented, and by setting the temperature to 240°C or higher, precipitation of tar components can be effectively prevented. When waste is gasified, the synthesis gas G1 contains a large amount of tar components, but by preventing precipitation of tar components, clogging due to tar components in the heat exchanger 20 can be prevented. Further, by setting the temperature to 300°C or lower, it becomes unnecessary to excessively cool the synthesis gas G1 in the gas cooling tower 21.

[0025] <Gas cooling tower> The gas cooling tower 21 is a facility for cooling the gas (synthesis gas G1) passing through its interior by water spraying. The gas cooling tower 21 is provided with one or more water spray nozzles 24 for spraying water onto the synthesis gas G1 on its inner peripheral surface. Preferably, two or more water spray nozzles 24 are provided, and more preferably, the two or more water spray nozzles 24 are provided at different height positions in the cooling tower 21. By providing a plurality of water spray nozzles 24 and having different height positions thereof, the synthesis gas G1 can be cooled sufficiently and efficiently by water spraying.

[0026] Preferably, the synthesis gas G1 is introduced into the gas cooling tower 21 from its upper side, and the synthesis gas G1 is passed through the interior of the gas cooling tower 21 so as to form a downward airflow, and is cooled by the water sprayed from the water spray nozzle 24 while passing through the interior of the gas cooling tower 21. In this case, the synthesis gas G1 is preferably discharged from the lower side of the gas cooling tower 21.

[0027] The synthesis gas G1 introduced into the gas cooling tower 21 is at a temperature sufficiently higher than 100°C, while the water sprayed from the water spray port 24 is lower than 100°C. Therefore, the synthesis gas G1 is cooled by the temperature difference, and is also cooled by the heat of vaporization when the water sprayed from the water spray port 24 vaporizes. A part of the vaporized water may be mixed into the synthesis gas G1 as water vapor. Note that the water sprayed from the water spray port 24 may be partially or entirely vaporized when it is sprayed.

[0028] In the gas cooling tower 21, the synthesis gas G1 is preferably cooled to a temperature of 100°C or higher and 200°C or lower, and may be discharged to the outside of the gas cooling tower 21 within the above temperature range. By cooling the synthesis gas G1 to 200°C or lower, the synthesis gas G1 can be purified by the filter type dust collector 22 without damaging the filter type dust collector 22 described later or reducing the dust collection performance. Also, by setting it to 100°C or higher, most of the sprayed water will vaporize and be mixed into the synthesis gas G1. Therefore, in the gas cooling tower 21, since a large amount of the sprayed water is not drained, it is not necessary to introduce large-scale drainage equipment into the gas cooling tower 21.

[0029] However, a part of the water sprayed into the gas cooling tower 21 may fall below the gas cooling tower 21 as a liquid and be recovered. Also, impurities such as char and tar in the synthesis gas G1 may collide with the sprayed water and fall downward and be recovered.

[0030] In the gas cooling tower 21, the synthesis gas G1 is more preferably cooled to a temperature of 120°C or higher and 180°C or lower, and even more preferably 130°C or higher and 170°C or lower, and is discharged to the outside after being cooled to these temperatures. By cooling the synthesis gas G1 to 120°C or higher, it is possible to prevent a large amount of the water mixed into the synthesis gas G1 from liquefying in the gas cooling tower 21 and further in the filter type dust collector 22 described later. Also, by setting it to 180°C or lower, it becomes easier to further avoid damage and functional degradation of the filter type dust collector 22.

[0031] <Filter type dust collector> The synthesis gas G1 cooled in the gas cooling tower 21 passes through the filter type dust collector 22. As the filter type dust collector 22, what is called a bag filter can be used, and it includes a casing and a filter medium housed inside the casing. The filter medium is not particularly limited, but for example, woven fabrics or felts such as glass fibers and PTFE fibers are used. The synthesis gas G1 contains a large amount of solid impurities such as tar and char, but by passing through the filter type dust collector 22, the solid impurities are removed. By removing the solid impurities, it is possible to prevent the solid impurities from clogging each device in the subsequent stage of the filter type dust collector 22. For example, in the organic substance generation unit 30, it is common for gas to be blown into the reactor via a sparger, but clogging of the solid impurities in the sparger can be prevented. Furthermore, by removing the solid impurities, it is easy to enhance the activity of the microbial catalyst in the organic substance generation unit 30, and it is also possible to prevent the microbial catalyst from dying due to the influence of impurities, and organic substances can be synthesized with high conversion efficiency. In addition, in this specification, "removal" means reducing the concentration of the target substance in the gas by removing at least a part of the substance to be removed from the synthesis gas, and is not limited to completely removing the substance to be removed.

[0032] As described above, the synthesis gas G1 is cooled in the gas cooling tower 21, so that the temperature of the synthesis gas G1 when passing through the filter type dust collector 22 is preferably 100°C or higher and 200°C or lower, more preferably 120°C or higher and 180°C or lower, and even more preferably 130°C or higher and 170°C or lower. Therefore, the filter type dust collector 22 can be prevented from being damaged by the high-temperature synthesis gas G1 or the filtering performance from being deteriorated. Also, it is possible to prevent a large amount of the synthesis gas G1 contained in the synthesis gas G1 from liquefying in the filter type dust collector 22.

[0033] <Water scrubber> The synthesis gas G1 cooled in the gas cooling tower 21 passes through the water scrubber 23. In the present embodiment, the synthesis gas G1 cooled in the gas cooling tower 21 and discharged from the filter dust collector 22 passes through the water scrubber 23 disposed downstream of the filter dust collector 22. The synthesis gas G1 contains various impurities in addition to the solid impurities described above, for example, water-soluble impurities. Examples of the water-soluble impurities include acidic gases such as hydrogen sulfide, hydrogen chloride, and hydrocyanic acid, basic gases such as ammonia, and oxides such as NOx and SOx. These water-soluble impurities are removed by passing through the water scrubber 23. In addition, the synthesis gas G1 also contains oily impurities such as BTEX (benzene, toluene, ethylbenzene, xylene), naphthalene, 1-naphthol, and 2-naphthol. These may also be appropriately removed in the water scrubber 23, or solid impurities that could not be recovered by the filter dust collector 22 may also be appropriately removed.

[0034] The water scrubber 23 is not particularly limited as long as it has a configuration for bringing the synthesis gas G1 into contact with water. For example, as shown in FIG. 1, it preferably has a configuration for bringing water (conveniently also referred to as "washing water") sprayed from a nozzle 25 provided at the upper part into contact with the synthesis gas G1. In this case, the water scrubber 23 may be provided with an introduction path 27, a supply path 28, a discharge path 29, and the like. Further, a storage part 26 for storing the washing water is provided at the lower part of the water scrubber 23. The washing water stored in the storage part 26 may be appropriately stirred by a stirring device (not shown).

[0035] The introduction path 27 is a path for introducing the synthesis gas G1 into the water scrubber 23, and the inlet 27A of the introduction path 27 is provided, for example, above the liquid level of the washing water stored in the storage part 26 inside the scrubber 12. The supply path 28 supplies the washing water to circulate water in the water scrubber 23 and bring it into contact with the synthesis gas G1. Specifically, the supply path 28 sprays the washing water stored in the storage section 26 downward inside the water scrubber 23 from the nozzle 25 to bring it into contact with the synthesis gas G1. Here, for example, a pump (not shown) is provided in the supply path 28, and the washing water is pumped to the nozzle 25 by the pump. Then, the washing water is sprayed downward from the nozzle 25 inside the scrubber 12. The discharge path 29 is provided at the upper part of the scrubber 12 and discharges the synthesis gas G1 after contacting the washing water sprayed from the nozzle 25 to the outside. Note that the washing water used in the scrubber 23 may be water alone, or a chemical agent may be appropriately added.

[0036] Furthermore, a removal device 19 may be provided in the water scrubber 23. The removal device 19 is, for example, a device for removing impurities (such as oily impurities, solid impurities, water-soluble impurities, etc.) contained in the washing water. The removal device 19 may be provided, for example, by providing a circulation path for circulating the water in the storage section 26 and being provided in the middle of the path. As the removal device 19, for example, it is preferable to remove oily impurities contained in the washing water, solid impurities not dissolved in the washing water, water-soluble impurities dissolved in the washing water, etc. Therefore, the removal device 19 may be an oil-water separator or the like, a filter for removing solid impurities, or a combination of two or more of these, as long as it can remove the impurities contained in the washing water, it may have any configuration. By providing the removal device 19 in the water scrubber 23, the accumulation of impurities in the washing water is prevented.

[0037] The synthesis gas G1 may be cooled by contacting water in the water scrubber 23. As described above, the synthesis gas G1 is cooled in the gas cooling tower 21 and introduced into the water scrubber 23 in a state cooled to a predetermined temperature (preferably a temperature of 100 °C or higher and 200 °C or lower, more preferably 120 °C or higher and 180 °C or lower, still more preferably 130 °C or higher and 170 °C or lower). On the other hand, the temperature of the water that contacts the synthesis gas G1 in the water scrubber 23 is less than 100°C, preferably 0°C or more and 40°C or less, more preferably 5°C or more and 30°C or less. In addition, in this specification, the "temperature of the water that contacts the synthesis gas G1" means that when the washing water is circulated and contacted with the synthesis gas G1 as described above, the temperature of the water immediately before it contacts the synthesis gas G1, that is, the temperature of the water (washing water) sprayed from the nozzle 15, may be measured. Also, when the synthesis gas G1 is introduced into the stored water (washing water) as described later, the temperature of the washing water stored in the storage section 26 may be measured.

[0038] The synthesis gas G1 contacts the water at the above temperature in the scrubber 23, and thus is cooled to a temperature of, for example, less than 100°C, preferably 40°C or less, more preferably 38°C or less in the water scrubber 23. In this way, when the synthesis gas G1 is cooled to a predetermined temperature below the boiling point of water in the water scrubber 23, at least a part of the water (water vapor) mixed into the synthesis gas G1 in the gas cooling tower 22 is condensed and removed. Therefore, it is possible to appropriately remove water without separately providing a large-scale device for removing the water mixed by the gas cooling tower 22. Also, by cooling to 40°C or less, it is possible to supply the synthesis gas G1 at an appropriate temperature to the organic substance generation section without separately providing a cooling device. Further, when the processing device provided downstream of the water scrubber 23 includes a cooling device, the load on the cooling device can be reduced. Note that the synthesis gas G1 is preferably cooled to a temperature of, for example, 0°C or more, more preferably 5°C or more, by contacting with water.

[0039] The water scrubber 23 is preferably provided with a temperature control device (not shown), and the temperature of the washing water is controlled by the temperature control device. The temperature control device may be attached to the supply passage 28, for example, to adjust the temperature of the washing water passing through the inside of the supply passage 28, or may be provided on the outer periphery of the water scrubber to adjust the temperature of the washing liquid stored in the storage portion 26 of the water scrubber. The temperature control device may cool the washing water passing through the supply passage 28 or the washing water stored in the storage portion 26 to a temperature within the above-described range. Further, the water stored in the storage portion 26 may be appropriately replaced to maintain the temperature of the water in contact with the synthesis gas G1 within a certain temperature range.

[0040] In the above description, in the water scrubber 23, the mode in which the synthesis gas G1 contacts the washing water sprayed from the nozzle 25 has been described. However, the synthesis gas G1 may be introduced into the washing water stored in the storage portion 26. In this case, the supply passage 28 and the nozzle 25 are omitted, and the washing water is not sprayed from the nozzle. Further, the inlet 27A of the introduction passage 27 is disposed below the liquid level of the washing water stored in the storage portion 26. The synthesis gas G1 comes into contact with the washing water stored in the storage portion 26, whereby the synthesis gas G1 is washed and cooled. Even when the synthesis gas G1 is introduced into the washing water stored in the storage portion 26, the temperature of the water in contact with the synthesis gas G1 and the temperature of the synthesis gas G1 (that is, the temperature of the synthesis gas G1 introduced into the water scrubber 23, the temperature of the synthesis gas G1 after cooling) are as described above.

[0041] (Other processing devices) The processing unit 3 may have a processing device other than the heat exchanger 20, the gas cooling tower 21, the filter type dust collector 22, and the water scrubber 23 described above. As such a processing device, a processing device (also referred to as a “post-stage processing device”) may be provided at the subsequent stage of the water scrubber 23, and the purified synthesis gas G2 that has passed through the water scrubber 23 may be appropriately processed by the post-stage processing device and then supplied to the organic substance generation unit 30. Examples of the post-treatment device include a moisture separation device such as a gas chiller, a separation device using a cryogenic separation method (cryogenic method), a particulate separation device composed of various filters, a desulfurization device (sulfide separation device), a separation device using a membrane separation method, a deoxygenation device, a separation device using a pressure swing adsorption method (PSA), a separation device using a temperature swing adsorption method (TSA), a separation device using a pressure and temperature swing adsorption method (PTSA), a separation device using activated carbon, a deoxygenation catalyst, specifically, a separation device using a copper catalyst or a palladium catalyst, etc. These may be used alone or in combination of two or more. The purified synthesis gas G2 discharged from the water scrubber 23 may be further purified by these post-treatment devices.

[0042] (Organic substance generation section) As described above, the synthesis gas G1 that has passed through at least the heat exchanger 20 and the gas cooling tower 21 is supplied to the organic substance generation section 30 as the purified synthesis gas G2. The purified synthesis gas G2 supplied to the organic substance generation section 30 is preferably the purified synthesis gas G2 that has passed through the heat exchanger 20, the gas cooling tower 21, the filter type dust collector 22, and the water scrubber 23 in this order. The organic substance generation section 30 generates organic substances by bringing the purified synthesis gas G2 into contact with a microbial catalyst. Preferably, a gas-utilizing microorganism is used as the microbial catalyst. The organic substance generation section 30 includes a fermentation tank (reactor) filled with a culture solution containing water and a microbial catalyst. The purified synthesis gas G2 is supplied into the fermentation tank, and the purified synthesis gas G2 is converted into organic substances inside the fermentation tank. The organic substances preferably include ethanol.

[0043] The fermentation tank is preferably a continuous fermentation device, and may be any of a stirring type, an air-lift type, a bubble column type, a loop type, an open bond type, and a photobioreactor type. The purified synthesis gas G2 and the culture solution may be continuously supplied to the fermentation tank, but it is not necessary to supply the purified synthesis gas G2 and the culture solution at the same time. The purified synthesis gas G2 may be supplied to a fermentation tank that has been supplied with the culture solution in advance. The synthesis gas G2 is generally blown into the fermentation tank through a sparger or the like. The medium used for culturing the microbial catalyst is not particularly limited as long as it has an appropriate composition according to the bacteria, but it is a liquid containing water as the main component and nutrients (such as vitamins, phosphoric acid, etc.) dissolved or dispersed in this water. In the organic substance production unit 30, organic substances are produced by the microbial fermentation of the microbial catalyst, and a liquid containing organic substances is obtained.

[0044] The temperature of the fermentation tank is preferably controlled to 40 °C or lower. By controlling it to 40 °C or lower, the microbial catalyst in the fermentation tank does not die, and when the purified synthesis gas G2 contacts the microbial catalyst, organic substances such as ethanol are efficiently produced. The temperature of the fermentation tank is more preferably 38 °C or lower. Also, in order to enhance the catalyst activity, it is preferably 10 °C or higher, more preferably 20 °C or higher, and even more preferably 30 °C or higher.

[0045] (Separation device) The organic substance production apparatus 1 includes a separation device 31 that separates at least water from the liquid containing organic substances. As the separation device 31, it is preferable to include a distillation device 33, and it is more preferable to include a solid-liquid separation device 32 in the front stage of the distillation device 33. It is preferable to use the separation device 31 by combining the solid-liquid separation device 32 and the distillation device 33. Hereinafter, the separation process performed by combining the solid-liquid separation device 32 and the distillation device 33 will be specifically described.

[0046] <Solid-liquid separation device> The organic substance-containing liquid obtained in the organic substance generation unit 30 may be separated in the solid-liquid separation device 32 into a solid component mainly composed of microorganisms and a liquid component containing organic substances. Since the organic substance-containing liquid obtained in the organic substance generation unit 30 contains, as solid components, microorganisms contained in the fermentation tank, their dead bodies, etc. in addition to the target organic substances, solid-liquid separation is performed to remove these. Examples of the solid-liquid separation device 32 include a filter, a centrifuge, and a device using a solution precipitation method. Further, the solid-liquid separation device 32 may be a device (for example, a heat drying device) that evaporates the liquid component containing organic substances from the organic substance-containing liquid and separates it from the solid component. At this time, all of the liquid component containing the target organic substance may be evaporated, or the liquid component may be partially evaporated so that the target organic substance evaporates preferentially.

[0047] <Distillation device> The distillation device 33 performs distillation for separating the target organic substances. The distillation device 33 can purify a large amount of organic substances with high purity by a simple operation through separation by distillation. In the separation step performed by combining the distillation device 33 with the solid-liquid separation device 32, in the distillation device 33, by performing distillation for further separating the target organic substances from the liquid component separated by the solid-liquid separation device 32, a large amount of organic substances can be purified with even higher purity. As the distillation device 33, a known distillation column or the like can be used. Further, in distillation, for example, the operation may be performed such that the distillate contains the target organic substance (for example, ethanol) with high purity, while the bottoms (that is, the distillation residue) contains water as the main component (for example, 70% by mass or more, preferably 90% by mass or more). By operating in this way, the target organic substance and water can be generally separated.

[0048] The temperature inside the distillation device 33 during the distillation of organic substances (for example, ethanol) is not particularly limited, but is preferably 100°C or lower, and more preferably about 70 to 95°C. By setting the temperature inside the distillation device 33 within the above range, the separation of the necessary organic substances from other components such as water can be surely performed. During the distillation of the organic substance, the pressure in the distillation apparatus 33 may be normal pressure, but is preferably less than atmospheric pressure, more preferably about 60 to 150 kPa (gauge pressure). By setting the pressure in the distillation apparatus 33 within the above range, the separation efficiency of the organic substance can be improved, and the yield of the organic substance can be improved.

[0049] The distillation apparatus 33 preferably utilizes the thermal energy obtained from the synthesis gas G1 by the heat exchanger 20 described above for distillation. The distillation apparatus 33 can increase the temperature in the distillation apparatus 33 during the distillation of the organic substance by reusing the thermal energy obtained from the synthesis gas G1 in the heat exchanger 20. In this way, by the distillation apparatus 33 reusing the thermal energy obtained from the synthesis gas G1 in the heat exchanger 20, the energy consumption of the entire manufacturing process of the organic substance can be reduced. The thermal energy obtained from the synthesis gas G1 in the heat exchanger 20 can be transmitted via a thermal energy path 33a connected to the heat exchanger 20 and the distillation apparatus 33. The thermal energy path 33a is not particularly limited and may have any configuration that moves the thermal energy of the synthesis gas G1 from the heat exchanger 20 to the distillation apparatus 33 by a heat medium. The heat medium may be either a gas or a liquid, or may involve a phase change between a gas and a liquid. Also, as described above, the heat exchanger 20 is preferably a boiler, and therefore, steam is preferably used as the heat medium. By using steam as the heat medium, it is easy to reuse the thermal energy of the synthesis gas G1. Note that when steam is used as the heat medium, a part of the steam may be liquefied.

[0050] The water separated in the separation device 31 is preferably reused, more preferably supplied to the gas cooling tower 21, and used for water spraying in the gas cooling tower 21. In this way, when the water is reused, the water that has become unnecessary in the organic substance generation unit 30 does not become wastewater, which is preferable from the viewpoints of environmental protection and economy. Further, the organic substance production apparatus 1 may be connected to the separation device 31 and the gas cooling tower 21, and may have a supply path 31a for supplying the water obtained in the separation device 31 to the gas cooling tower 21. The supply path 31a is not particularly limited, but is preferably constituted by a pipe or the like. Further, the water separated in the separation device 31 may be further purified and its purity increased, and then supplied to the gas cooling tower 21.

[0051] As described above, according to the present embodiment, the synthesis gas G1 is cooled by the heat exchanger 20 and then cooled by the water spraying in the gas cooling tower 21, so that the synthesis gas G1 can be cooled without blowing nitrogen gas or air. Therefore, the temperature of the synthesis gas G1 can be lowered without changing the composition of the synthesis gas G1, and organic substances can be synthesized without killing the microbial catalyst. Further, according to the present embodiment, after the synthesis gas G1 is cooled by the heat exchanger 20, the synthesis gas G1 is cooled by the water spraying in the gas cooling tower 21. Therefore, the heat exchanger 20 partially undertakes the role of cooling the synthesis gas G1, and the role of cooling in the gas cooling tower 21 is reduced. As a result, it is possible to reduce the amount of water sprayed for cooling the synthesis gas in the gas cooling tower 21, and at the same time, it is also possible to reduce the amount of wastewater discharged from the gas cooling tower 21.

[0052] Further, according to the present embodiment, the thermal energy obtained from the synthesis gas G1 by the heat exchanger 20 can be used to increase the temperature in the distillation apparatus 33 during the distillation of the organic substance. Therefore, the amount of energy procured from the outside in the distillation of the distillation apparatus 33 can be reduced, and the energy consumption of the entire production process of the organic substance can be reduced.

[0053] In the above embodiments, a configuration in which the water scrubber 23 is provided is shown, but the water scrubber 23 may be omitted. When the water scrubber 23 is omitted, the synthesis gas G1 that has passed through at least the gas cooling tower 21 and the filter type dust collector 22 is brought into contact with the microbial catalyst in the organic substance generation unit 30 and converted into an organic substance. The synthesis gas G1 discharged from the filter type dust collector 22 in this embodiment is typically at a relatively high temperature (for example, 100 °C or higher). However, when the water scrubber 23 is omitted, a cooling device other than the water scrubber 23 is provided downstream of the filter type dust collector 22, and the synthesis gas G1 discharged from the filter type dust collector 22 may be cooled by the cooling device other than the water scrubber 23. Also, when the water scrubber 23 is omitted, one or more processing devices selected from the above-described downstream processing devices are provided downstream of the filter type dust collector 22 in addition to the cooling device, and the synthesis gas G1 discharged from the filter type dust collector 22 may be appropriately processed by the downstream processing device. Also, when it is not necessary to purify the organic substance produced in the organic substance generation unit 30 or when it is not necessary to separate water from the organic substance-containing liquid, etc., the separation device 31 may be omitted.

[0054] Also, in the above embodiments, a configuration in which the filter type dust collector 22 is provided is shown, but the filter type dust collector 22 may be omitted. When the filter type dust collector 22 is omitted, the synthesis gas G1 cooled in the gas cooling tower 21 is supplied to the water scrubber 23 without passing through the filter type dust collector 22. For example, the filter type dust collector 22 may be omitted when the waste has few solid impurities or when a synthesis gas is generated using a raw material other than waste as described later. Of course, both the water scrubber 23 and the filter type dust collector 22 may be omitted.

[0055] As described above, the processing unit 3 in the purified synthesis gas production apparatus includes at least the heat exchanger 20 and the gas cooling tower 21, but it is preferable to further include the filter type dust collector 22 and the water scrubber 23. Also, the processing unit 3 may appropriately have other downstream processing devices and the like in addition to these. Since the details of these are as described above, the description thereof is omitted.

[0056] Furthermore, in the above-described embodiment, the mode in which the synthesis gas G1 is obtained from the waste in the gasification apparatus 2 has been described. However, in the gasification apparatus 2, the synthesis gas G1 may be generated from sources other than the waste. For example, the synthesis gas G1 may be generated from fossil resources such as natural gas, coal, heavy oil, petroleum exhaust gas, oil shale, or biomass other than the waste. Also, the synthesis gas may be a by-product gas in various manufacturing processes such as the steel manufacturing process. For example, the gasification apparatus 2 may be a component of a steel manufacturing facility or the like.

Explanation of Reference Numerals

[0057] 1 Organic substance manufacturing apparatus 2 Gasification apparatus 3 Processing unit 10 Gasification furnace 11 Reforming furnace 20 Heat exchanger 21 Gas cooling tower 22 Filter type dust collector 23 Water scrubber 24 Water spray port 25 Nozzle 26 Storage section 27 Introduction path 28 Supply path 29 Discharge path 30 Organic substance generation section 31 Separation device 31a Supply path 32 Solid-liquid separation device 33 Distillation device 33a Thermal energy path G1 Synthesis gas G2 Purified synthesis gas

Claims

1. A step of cooling the synthesis gas discharged from the gasification device by passing it through a heat exchanger; A step of passing the synthesis gas cooled by the heat exchanger through a gas cooling tower and cooling it with water sprayed inside the gas cooling tower; A step of passing the synthesis gas cooled by the gas cooling tower through a bag filter and a water scrubber; A step of contacting the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, the bag filter, and the water scrubber with a microbial catalyst to produce an organic substance; A method for producing an organic substance, wherein the synthesis gas is cooled by the water scrubber.

2. A step of cooling the synthesis gas discharged from the gasification device by passing it through a heat exchanger; A step of passing the synthesis gas cooled by the heat exchanger through a gas cooling tower and cooling it with water sprayed inside the gas cooling tower; A step of passing the synthesis gas cooled by the gas cooling tower through a bag filter and a water scrubber; A step of contacting the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, the bag filter, and the water scrubber with a microbial catalyst to produce an organic substance; A step of distilling the organic substance; The step of distilling the organic substance utilizes the thermal energy obtained from the synthesis gas by the heat exchanger for distillation. A method for producing an organic substance.

3. The method for producing an organic substance according to claim 1 or 2, wherein the temperature of the synthesis gas discharged from the gasification device is 900°C or higher.

4. The method for producing an organic substance according to any one of claims 1 to 3, wherein the synthesis gas is cooled to a temperature of 200°C or higher and 300°C or lower by the heat exchanger.

5. The method for producing an organic substance according to any one of claims 1 to 4, wherein the synthesis gas that has passed through the heat exchanger, the gas cooling tower, the bag filter, and the water scrubber in this order is contacted with a microbial catalyst to produce an organic substance.

6. The method for producing an organic substance according to any one of claims 1 to 5, wherein the synthesis gas is cooled to less than 100°C by the water scrubber.

7. The method for producing an organic substance according to any one of claims 1 to 6, wherein the synthesis gas is cooled to 40°C or lower by the water scrubber.

8. The method for producing an organic substance according to any one of claims 1 to 7, wherein the organic substance contains ethanol.

9. A gasification device for generating synthesis gas; A heat exchanger that allows the synthesis gas discharged from the gasifier to pass through and be cooled; A gas cooling tower that allows the synthesis gas cooled by the heat exchanger to pass through and be cooled by water spraying; A filter type dust collector and a water scrubber that are arranged in the subsequent stage of the gas cooling tower and allow the synthesis gas cooled by the gas cooling tower to pass through; An organic substance generation unit that contacts the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, the filter type dust collector, and the water scrubber with a microbial catalyst to generate an organic substance; An organic substance production apparatus that cools the synthesis gas with the water scrubber.

10. A gasifier that generates synthesis gas; A heat exchanger that allows the synthesis gas discharged from the gasifier to pass through and be cooled; A gas cooling tower that allows the synthesis gas cooled by the heat exchanger to pass through and be cooled by water spraying; A filter type dust collector and a water scrubber that are arranged in the subsequent stage of the gas cooling tower and allow the synthesis gas cooled by the gas cooling tower to pass through; An organic substance generation unit that contacts the synthesis gas that has passed through at least the heat exchanger, the gas cooling tower, the filter type dust collector, and the water scrubber with a microbial catalyst to generate an organic substance; A distillation apparatus that distills the organic substance; The distillation apparatus is an organic substance production apparatus that uses the thermal energy obtained from the synthesis gas by the heat exchanger for distillation.

11. The organic substance production apparatus according to claim 9 or 10, wherein the temperature of the synthesis gas discharged from the gasifier is 900°C or higher.

12. The organic substance production apparatus according to any one of claims 9 to 11, wherein the synthesis gas is cooled by the heat exchanger to a temperature of 200°C or higher and 300°C or lower.

13. The organic substance production apparatus according to any one of claims 9 to 12, wherein the organic substance generation unit contacts the synthesis gas that has passed through the heat exchanger, the gas cooling tower, the filter type dust collector, and the water scrubber in this order with the microbial catalyst to generate an organic substance.

14. The organic substance production apparatus according to any one of claims 9 to 13, wherein the synthesis gas is cooled to less than 100°C by the water scrubber.

15. The organic substance production apparatus according to any one of claims 9 to 14, wherein the synthesis gas is cooled to 40°C or lower by the water scrubber.

16. The organic substance production apparatus according to any one of claims 9 to 15, wherein the organic substance contains ethanol.

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