Sulfur recycle system

Abstract

Provided is a sulfur recycle system employing biomass and constructed industrially applicably. The sulfur recycle system, which employs biomass, is characterized by comprising: a desulfurization step in which biomass or treated biomass is desulfurized to remove sulfur-containing substances from the biomass or treated biomass; a recovery step in which sulfur is recovered from the desulfurization residue yielded in the desulfurization step; a processing step in which the recovered sulfur is processed into sulfur for vulcanization; a kneading step in which the sulfur for vulcanization is kneaded together with a polymer having double bonds; and a vulcanization step in which the polymer having double bonds is vulcanized.

Description

Sulfur Recycling System

[0001] The present invention relates to a sulfur recycling system.

[0002] Biomass fuels are a new energy source that can replace fossil fuels. Biomass fuels are typically fuels that are made from biomass such as plants or animals, or are produced via biomass such as plants or animals. ２ Among biomass fuels, gaseous fuel, i.e. biogas, is a gas obtained through fermentation (methane fermentation) and anaerobic digestion. Biogas is a non-exhaustible renewable resource, and the fuel components in the gas (methane, etc.) can be used as is or burned to convert into electricity, making it a highly versatile energy source.

[0003] Furthermore, microalgae, including Euglena, can produce oils and fats within their bodies through photosynthesis. By extracting and refining these oils and fats, biomass fuel can be produced, reducing CO ２ This is expected to have a reduction effect.

[0004] Typically, the biomass fuel contains sulfur compounds, particularly hydrogen sulfide, due to the raw materials and production process. Because this hydrogen sulfide has adverse effects such as corrosion of peripheral devices, it is common to remove it before using it as energy (see, for example, Patent Document 1). Meanwhile, technologies for suppressing the generation of hydrogen sulfide itself have also been studied. For example, Patent Document 2 discloses a technology using yeast with reduced hydrogen sulfide production ability.

[0005] JP 2012-101139 A JP 2010-246440 A

[0006] It is known that sulfur undergoes a vulcanization reaction with double-bond-containing polymers. This vulcanization technology has been widely used, particularly in the rubber field, and has supported industrial development. Sulfur used in industrial applications is mainly produced from hydrogen sulfide, a by-product of the hydrodesulfurization of crude oil, i.e., derived from fossil resources. From the perspective of preserving the global environment and realizing a sustainable society, it is essential to establish a recycling system for such sulfur as well.

[0007] In this regard, hydrogen sulfide contained in biogas is currently removed as described above, but recycling of sulfur from such hydrogen sulfide has not been reported so far, likely due to difficulties such as high costs, low recovery amounts, and unstable yields of recycled raw materials.

[0008] Therefore, an object of the present invention is to provide a sulfur recycling system using biomass that is constructed so as to be applicable industrially.

[0009] The gist and configuration of the present invention to solve the above problems is as follows.

[0010] [1] A sulfur recycling system using biomass, comprising: a desulfurization process for desulfurizing biomass or a biomass treatment product to remove sulfur-containing substances from the biomass or the biomass treatment product; a recovery process for recovering sulfur from a desulfurization residue generated in the desulfurization process; a processing process for processing the recovered sulfur into sulfur for vulcanization; a kneading process for kneading the sulfur for vulcanization with a double bond-containing polymer; and a vulcanization process for vulcanizing the double bond-containing polymer.

[0011] [2] The sulfur recycling system according to [1], wherein the sulfur-containing substance is selected from hydrogen sulfide and sulfur dioxide.

[0012] [3] The sulfur recycling system according to [1] or [2], wherein the biomass is selected from animal feces, sewage, food waste, and microalgae.

[0013] [4] The sulfur recycling system according to any one of [1] to [3], wherein the desulfurization in the desulfurization step is carried out by contacting the biomass or the biomass treatment product with a contact medium selected from an adsorbent, a solvent, and bacteria.

[0014] According to the present invention, it is possible to provide a sulfur recycling system using biomass that is constructed so as to be applicable industrially.

[0015] The present invention will be described in detail below by way of example based on embodiments thereof. The compounds described in this specification may be derived in part or entirely from fossil resources, from biological resources such as plant resources, or from recycled resources such as used tires. They may also be derived from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0016] <Sulfur Recycling System> The sulfur recycling system of the present invention (hereinafter sometimes simply referred to as the "recycling system") is a sulfur recycling system that uses biomass. The recycling system of the present invention is characterized by including a step of desulfurizing biomass or a biomass treatment product and removing sulfur-containing substances from the biomass or biomass treatment product (desulfurization step), a step of recovering sulfur from the desulfurization residue generated in the desulfurization step (recovery step), a step of processing the recovered sulfur into sulfur for vulcanization (processing step), a step of kneading the sulfur for vulcanization with a double-bond-containing polymer (kneading step), and a step of vulcanizing the double-bond-containing polymer (vulcanization step). The recycling system of the present invention is a system that can be applied to the rubber field, including tires, which requires vulcanization using sulfur.

[0017] Although the present invention relates to the recycling of sulfur, the biomass used in the present invention often generates nitrogen-containing substances such as ammonia. Therefore, the recycling system of the present invention can also recycle nitrogen.

[0018] (Regarding recycled raw materials) In this specification, "biomass" typically refers to organic resources derived from plants and animals, and refers to materials other than fossil resources (oil, coal, natural gas, etc.). Furthermore, although there are no particular limitations on biomass, a wide range of materials can be used, including, for example, animal excreta, sewage, food waste, microalgae, black liquor, paper, sawmill residues, construction waste wood, inedible parts of agricultural crops, and forest residues.

[0019] Furthermore, the raw material for recycling provided to the recycling system of the present invention may be biomass itself, or a product obtained by subjecting the biomass to some kind of processing (defined as a "processed biomass product" in this specification), or a combination of these. Here, the processing is preferably a process for converting the biomass into a more usable form.

[0020] For example, the biomass processed product can be biogas obtained by methane fermentation of biomass such as animal manure, sewage, and food waste. The methane fermentation can be carried out by a known method. The biogas obtained by the methane fermentation typically contains sulfur-containing substances, mainly hydrogen sulfide, in addition to methane, which is a fuel component. Another example of the biomass processed product can be oils and fats produced by microalgae such as Euglena. The oils and fats produced by the microalgae typically contain sulfur-containing substances, mainly hydrogen sulfide, in addition to oils and fats such as wax esters.

[0021] In the recycling system of the present invention, the biomass or biomass treatment product as the recycling raw material (subject to treatment) may be one type alone or a combination of two or more types.

[0022] (Desulfurization process and recovery process) In the recycling system of the present invention, the desulfurization process is a process of desulfurizing biomass or a biomass treatment product to remove sulfur-containing substances from the biomass or the biomass treatment product. In the desulfurization process, a desulfurization treatment residue is usually generated. In addition, the recovery process is a process of recovering sulfur from the desulfurization treatment residue generated in the desulfurization process. That is, in the recovery process, sulfur is recovered as elemental sulfur.

[0023] The recycling system of the present invention is premised on the use of biomass or a biomass treatment product containing sulfur-containing substances as the recycling raw material. The sulfur-containing substances contained in the biomass or the biomass treatment product, or the sulfur-containing substances removed in the desulfurization step, are not particularly limited as long as they contain sulfur as a constituent element, and examples thereof include hydrogen sulfide and sulfur dioxide. The sulfur-containing substances removed in the desulfurization step may be one type alone or a combination of two or more types.

[0024] The desulfurization method in the desulfurization step is not particularly limited as long as it can remove sulfur-containing substances from the recycled raw material (biomass or treated biomass). As an example, desulfurization can be carried out by contacting the recycled raw material (biomass or treated biomass) with a contact medium selected from an adsorbent, a solvent, and bacteria. These contact media may be used alone or in combination of two or more. Below, embodiments of the desulfurization step and the recovery step are described in detail for each contact medium used.

[0025] [Adsorbent] The adsorbent used in the contact medium may be any adsorbent capable of selectively treating (adsorbing) sulfur-containing substances, and specific examples thereof include iron oxide, zinc ferrite, zeolite, etc. The adsorbent may be used alone or in combination of two or more.

[0026] As an example, when iron oxide is used as an adsorbent, hydrogen sulfide can be converted to iron sulfide by contact with the adsorbent during the desulfurization process. In this case, the desulfurization residue corresponds to an adsorbent containing iron sulfide. Then, in the recovery process, the iron sulfide in the desulfurization residue is reacted with a strong acid to convert it back to hydrogen sulfide, and sulfur can be recovered from the hydrogen sulfide by a known method. Furthermore, in the desulfurization residue (adsorbent containing iron sulfide) in the above case, sulfur may be contained in the form of elemental sulfur in addition to iron sulfide. Sulfur can also be recovered from such an adsorbent containing elemental sulfur by a known method.

[0027] For example, when zeolite is used as an adsorbent, hydrogen sulfide can be brought into contact with the zeolite during the desulfurization step, allowing the hydrogen sulfide to be directly physically adsorbed onto the zeolite. In this case, the desulfurization residue corresponds to the adsorbent containing hydrogen sulfide. In the subsequent recovery step, the desulfurization residue is exposed to reduced pressure and high temperature conditions to recover hydrogen sulfide, and then sulfur can be recovered from the hydrogen sulfide by a known method.

[0028] Adsorbents such as iron oxide are advantageous in that they have a relatively high sulfur recovery efficiency.

[0029] As a method for recovering sulfur from hydrogen sulfide, for example, the Claus process can be mentioned. The Claus process is a method for recovering sulfur from hydrogen sulfide (H ２ S) is partially burned to produce one-third of the sulfur dioxide (SO ２ In order to increase the reaction efficiency, unreacted hydrogen sulfide and sulfur dioxide undergo a Claus reaction using an alumina catalyst, which allows for the production of more elemental sulfur.

[0030] [Solvent] The solvent used in the contact medium may be any solvent capable of selectively treating (absorbing or extracting) sulfur-containing substances, and specific examples thereof include monoethanolamine, diethanolamine, methyldiethanolamine, etc. The solvent may be used alone or in combination of two or more. The solvent may also be diluted with water to be used as an aqueous solution.

[0031] For example, when monoethanolamine is used as the solvent, hydrogen sulfide can be absorbed by contacting the solvent during the desulfurization step. In this case, the desulfurization residue corresponds to the solvent that has absorbed hydrogen sulfide. Then, in the recovery step, the desulfurization residue is heated to separate the hydrogen sulfide, and sulfur can be recovered from the hydrogen sulfide by a known method (for example, the Claus process described above). The same applies when diethanolamine or methyldiethanolamine is used as the solvent.

[0032] The solvent such as monoethanolamine is advantageous in that it can be reused as a contact medium as it is after being heated in the recovery step.

[0033] [Bacteria] The bacteria used in the contact medium may be any bacteria capable of selectively treating sulfur-containing substances, and specific examples thereof include sulfur-oxidizing bacteria. More specific examples of bacteria include the sulfur-oxidizing bacteria described in "Biogas desulfurization in a microaerobic environment in a methane fermentation tank using sulfur-oxidizing bacteria" by Takuro Kobayashi et al. (Journal of the Japan Society of Civil Engineers, Vol. 65, No. 2, pp. 104-113, June 2009). One type of bacteria may be used alone, or two or more types may be used in combination.

[0034] For example, if sulfur-oxidizing bacteria are used as bacteria, they can oxidize hydrogen sulfide during the desulfurization process to produce sulfur. In this case, the desulfurization residue corresponds to the sulfur-containing bacteria. Then, in the recovery process, a cell lysis solution containing a surfactant or the like is used to lyse the desulfurization residue, and the sulfur can be extracted with a solvent to recover the sulfur. Examples of solvents used for the extraction include carbon disulfide and toluene.

[0035] Bacteria are advantageous in that they are relatively inexpensive to maintain.

[0036] (Processing Step) The processing step is a step of processing the recovered sulfur into sulfur for vulcanization. A known method can be used for the processing step. For example, in the processing step, the recovered sulfur (elemental sulfur) is dissolved in carbon disulfide, followed by heating, rapid cooling, separation, drying, and, if necessary, oil treatment to obtain insoluble sulfur (sulfur for vulcanization).

[0037] (Kneading Step) The kneading step is a step of kneading the above-mentioned sulfur for vulcanization with the double bond-containing polymer.

[0038] Examples of double bond-containing polymers include polymers that are widely used in the rubber field, including tires. Specific examples of double bond-containing polymers include natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), halogenated butyl rubber, and ethylene-propylene-diene rubber (EPDM). The double bond-containing polymers may be used alone or in combination of two or more.

[0039] In the kneading step, in addition to the above-mentioned sulfur for vulcanization and double bond-containing polymer, various compounding agents such as a vulcanization aid such as stearic acid, a vulcanization accelerator, a vulcanization acceleration aid such as zinc oxide, an antioxidant, oil, a softener, a plasticizer, and a processability improver may be appropriately compounded and kneaded depending on the purpose.

[0040] The kneading method is not particularly limited, and kneading can be carried out using a kneading machine such as a roll, an internal mixer, or a Banbury rotor.

[0041] (Vulcanization Step) The vulcanization step is a step of vulcanizing the double bond-containing polymer kneaded with vulcanizing sulfur. In this step, the vulcanizing sulfur functions as a vulcanizing agent.

[0042] The vulcanization temperature is not particularly limited, and can usually be set to 130° C. or higher and 180° C. or lower. The vulcanization time is not particularly limited, and can usually be set to 5 minutes or higher and 120 minutes or lower.

[0043] The recycling system of the present invention has been described above. Next, several systems related to the present invention will be described below.

[0044] <System for Predicting Hydrogen Sulfide Yield> In industrial application of the recycling system of the present invention, it is assumed that desulfurization is performed using a contact medium selected from an adsorbent, a solvent, and bacteria. The amount of sulfur-containing substances generated from biomass is relatively difficult to predict because it is affected by various factors. Incidentally, until now, sulfur-containing substances generated from biomass have not been recycled, or the generated sulfur-containing substances (such as hydrogen sulfide) have been removed, so there has been no need to accurately predict the amount generated.

[0045] Therefore, this specification provides a system for predicting the yield of hydrogen sulfide generated from biomass (hereinafter, sometimes referred to as a "yield prediction system").

[0046] The yield prediction system of this embodiment includes the steps of: constantly or periodically monitoring data on one or more yield indices that affect the yield of hydrogen sulfide; calculating a predicted yield of hydrogen sulfide from the monitored yield index data; determining a time to collect a contact medium from the calculated predicted yield of hydrogen sulfide; and collecting the contact medium at the determined time.

[0047] Examples of the yield index include raw material, temperature, humidity, etc. In particular, when biogas obtained by methane fermentation is used as the recycled raw material (biomass or biomass treatment product), further examples of the yield index include the amount of animal manure, the type of animal that produces the manure (pig, cow, chicken, sheep, etc.), the temperature of the fermenter, the size of the fermenter, the oxygen concentration of the fermenter, etc. Furthermore, when oils and fats produced by microalgae are used as the recycled raw material (biomass or biomass treatment product), further examples of the yield index include the size of the fermenter, the amount of sunlight, the oxygen concentration, etc.

[0048] In addition, in the yield prediction system, the accuracy of calculation of the predicted yield of hydrogen sulfide can be improved by using the accumulated yield index data.

[0049] Furthermore, when two or more types of contact media are used, the yield prediction system may further include a step of determining a collection route for the contact media.

[0050] <System for Predicting Adsorbent Activity> When applying the recycling system of the present invention industrially, it is assumed that desulfurization is performed using an adsorbent as a contact medium. The adsorbent's adsorption capacity may deteriorate over time, so it must be replaced at the appropriate time. Otherwise, uncaptured (adsorbed) sulfur-containing substances (e.g., hydrogen sulfide) may corrode peripheral equipment such as gas tanks. In the present invention, it is further assumed that the amount of sulfur-containing substances that can be recovered and the efficient use of the adsorbent may be affected.

[0051] Therefore, this specification provides a system for predicting the activity of an adsorbent (hereinafter, sometimes referred to as an "activity prediction system").

[0052] The activity prediction system of this embodiment includes the steps of: constantly or periodically monitoring data on one or more yield indices that affect the yield of hydrogen sulfide; determining a predicted activity (which can also be stated as a degree of deterioration) of the adsorbent from the monitored yield index data; determining a time to collect the adsorbent as a contact medium from the determined predicted activity; and collecting the adsorbent at the determined time.

[0053] Examples of the yield index include raw material, temperature, humidity, etc. In particular, when biogas obtained by methane fermentation is used as the recycled raw material (biomass or biomass treatment product), further examples of the yield index include the amount of animal manure, the type of animal that produces the manure (pig, cow, chicken, sheep, etc.), the temperature of the fermenter, the size of the fermenter, the oxygen concentration of the fermenter, etc. Furthermore, when oils and fats produced by microalgae are used as the recycled raw material (biomass or biomass treatment product), further examples of the yield index include the size of the fermenter, the amount of sunlight, the oxygen concentration, etc.

[0054] In the activity prediction system, the accuracy of determining the predicted activity of the adsorbent can be improved by using the accumulated yield index data.

[0055] Furthermore, when two or more types of contact media (adsorbents) are used, the activity prediction system may further include a step of determining a collection route for the contact media.

[0056] <Adsorbent Collection and Transportation System> When the recycling system of the present invention is applied industrially, it is assumed that desulfurization is performed using an adsorbent as a contact medium. The absolute amount of sulfur-containing substances (sulfur) produced from biomass or biomass processing products, particularly biogas, as recycled raw materials is expected to be smaller in some cases than in processes for obtaining sulfur-containing substances (sulfur) from fossil resources. Therefore, it is necessary to collect sulfur-containing substances obtained at multiple locations or to aggregate them in one location.

[0057] Therefore, the present specification provides a system for collecting and transporting an adsorbent, particularly a consumed adsorbent (hereinafter, sometimes referred to as a "collection and transport system").

[0058] The collection and transportation system of this embodiment includes the steps of: constantly or periodically monitoring data on the consumption of the adsorbent actually used as a contact medium; determining the time to collect the adsorbent based on the monitored consumption data and data on the location where the adsorbent is installed; and collecting and transporting the adsorbent as a consumed adsorbent at the determined time.

[0059] The degree of consumption may include the duration of use (actual operation) of the adsorbent, the activity of the adsorbent, and the like.

[0060] Furthermore, when two or more types of contact media (adsorbents) are used, the collection and transportation system may further include a step of determining a collection route for the contact media.

[0061] <System for certifying that sulfur-based substances are derived from biomass> When the recycling system of the present invention is applied industrially, there may be a need to certify whether or not the sulfur-containing substances removed in the desulfurization process, the sulfur-containing substances, and the recovered sulfur (hereinafter, collectively referred to as "sulfur-based substances") are derived from biomass.

[0062] Therefore, this specification provides a system for certifying that a sulfur-based substance is derived from biomass (hereinafter, sometimes referred to as a "certification system").

[0063] The certification system of this embodiment includes means configured to manage traceability of sulfur in the sulfur recycling system of the present invention and to be able to certify that the substance (raw material) used is biomass.

[0064] The management of sulfur traceability can be performed, for example, on the sulfur-containing substances removed in the desulfurization process, the desulfurization residue after the desulfurization process, or the recovered sulfur. In addition, the management of sulfur traceability can be performed, for example, based on the sulfur isotope composition ratio.

[0065] The certification system is preferably configured so that the history of managed traceability can be viewed.

[0066] According to the present invention, it is possible to provide a sulfur recycling system using biomass that is constructed so as to be applicable industrially.

Claims

1. A sulfur recycling system using biomass, A desulfurization step involves desulfurizing biomass or biomass-treated material to remove sulfur-containing substances from the biomass or biomass-treated material, A recovery step for recovering sulfur from the desulfurization residue generated in the aforementioned desulfurization step, The processing step involves converting the recovered sulfur into sulfur for vulcanization, A kneading step in which the sulfur for vulcanization is kneaded with a polymer containing double bonds, A vulcanization step of vulcanizing the double bond-containing polymer, A sulfur recycling system characterized by including [the following].

2. The sulfur recycling system according to claim 1, wherein the sulfur-containing substance is selected from hydrogen sulfide and sulfur dioxide.

3. The sulfur recycling system according to claim 1 or 2, wherein the biomass is selected from animal manure, sewage, food waste, and microalgae.

4. The sulfur recycling system according to claim 1 or 2, wherein the desulfurization in the desulfurization step is carried out by contacting the biomass or biomass treated material with a contact medium selected from an adsorbent, a solvent, and bacteria.