KR101777919B1 - Method for producing bio-heavy oil from sewage sludge and bio-heavy oil produced by the method - Google Patents

Abstract

The present invention relates to a method for producing bio-heavy oil derived from sewage sludge and to a bio-heavy oil produced therefrom, wherein supercritical alcohols are used as a solvent and a reaction medium to simultaneously perform low molecular weight and oxygen removal of organic substances contained in sewage sludge , It is possible to provide a method for producing biofuel having low oxygen content and high energy content.

Description

METHOD FOR PRODUCING BIO-HEAVY OIL FROM SEWAGE SLUDGE AND BIO-HEAVY OIL PRODUCED BY THE METHOD <br> <br> <br> Patents - stay tuned to the technology METHOD FOR PRODUCING BIO-

The present invention relates to a method for producing bio-heavy oil derived from sewage sludge and a bio-heavy oil produced therefrom, and more particularly, to a method for producing bio-heavy oil from sewage sludge using sewage sludge as a raw material and using a supercritical alcohol as a solvent and a reaction medium, By simultaneously carrying out the low molecular weight and organic oxygen elimination reaction of the organic substances present, the produced liquid heavy biofuel has low oxygen content, increases the energy content, and becomes a liquid fuel for power generation and a liquid fuel for transportation through upgraduation The present invention relates to a method for producing biofuel, and to a biofuel produced therefrom.

Recently, concerns about environmental pollution such as depletion of petroleum resources and generation of CO ₂ due to excessive use of fossil fuels have increased, and interest in renewable, sustainable and environmentally friendly fuels based on non-fossil fuels is increasing rapidly . Sewage sludge is an organic by-product that necessarily occurs in the sewage treatment process. The sludge generated in the sewage treatment process by the standard activated sludge process, which is one of the sewage treatment methods adopted mainly at domestic and overseas sewage treatment plants, is the sludge generated in the initial sedimentation basin, and the raw sludge having a solid concentration of 4-10% , Surplus sludge having a solid concentration of 0.8-2.5 wt% excluding sludge recovered from the final sedimentation tank, concentrated sludge having a solid concentration of 2-8 wt% concentrated in a concentration tank, solid matter concentration in a digestion tank of 2.5-7 % By weight of digested sludge, and dehydrated sludge having a solid concentration of 20 wt% by reducing water through a dehydrator. Sewage sludge contains a large amount of various organic materials, and energy can be recovered by using appropriate technology for such organic materials.

On the other hand, the amount of sewage sludge generated at the sewage treatment plant is continuously increasing due to the increase in the population of the big cities in the world and the rapid improvement of living standards. For example, domestic sewage sludge production has increased steadily by about 4% over the past 10 years from 7,446 tons / day in 2006 to 10,179 tons / day in 2015. However, due to the limitations of conventional sewage sludge landfills and the difficulty of securing additional landfill sites, and since the recent conclusion of the London Convention has banned all marine dumping of sewage sludge, do.

In addition, various kinds of technologies such as incineration, solidification, carbonization and composting are being developed, but secondary environmental pollution, low energy efficiency, soil pollution, High processing cost, and the like.

Meanwhile, domestic and overseas power generation companies are using biofuel to mix with Bunker C oil used as fuel for power generation in order to cope with the mandatory system of new and renewable energy supply in each country. As a byproduct of biodiesel and biodiesel process, As well as a number of other technologies. However, in Korea, most of the oil used for raw materials for biodiesel is imported from abroad, and its amount is not so large. Therefore, it is necessary to diversify raw materials for bio-fuel oil for power generation.

In addition, among biofuels for transportation, bioethanol using sugar-based raw materials and bio-diesel using vegetable oil are commercially produced, but these first-generation biofuels have a fundamental limit of competition with food resources, It has a disadvantage in that it has a low energy content when compared with gasoline, jet fuel, and diesel starting from conventional fossil raw materials. As a result, much attention has been focused on the production of biofuels ("drop-in" biofuels), which do not compete with food resources and which contain little or no oxygen in the molecular structure.

Therefore, it is necessary to develop a technology capable of expanding the enormous amount of sewage sludge inevitably generated at home and abroad through suitable conversion processes and expanding it to bio-heavy fuel oil for power generation and liquid fuel for future transportation.

Korean Patent No. 10-0839363 Korean Patent Publication No. 10-2015-0005123

The present invention relates to a method for producing bio-heavy oil having a low oxygen content and a high energy content from sewage sludge at a high yield using an alcohol in a supercritical state as a solvent and a reaction medium, And to provide biofuel produced by the method.

It is another object of the present invention to provide a fuel for power generation or a fuel for transportation comprising the produced bio-heavy oil.

In order to accomplish the above object, a method for producing biofuel feedstock according to the present invention may include the step of producing biofuel feedstock by reacting sewage sludge in a supercritical state of an alcohol solvent.

The method may further include a step of drying the sewage sludge to dry the sewage sludge before the step of preparing the biofuel feedstock, and a step of separating and recovering the reaction product after the step of preparing the biofuel feedstock, .

The sewage sludge may comprise at least one of raw sludge, excess sludge, concentrated sludge, digested sludge, and dehydrated sludge, and the moisture content of the sewage sludge may be 5 to 90 wt%.

The alcohol solvent may be at least one selected from the group consisting of methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutanol, 2-butanol, tert-butanol, n- pentanol, isopentyl alcohol, Methyl-1-pentanol, 3-methyl-1-pentanol, 2-methyl-1-pentanol, Methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3- Dimethyl-1-butanol, 2,3-dimethyl-1-butanol, 2-ethyl 1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, and 4-heptanol.

The sewage sludge may be contained in an amount of 1 to 80% by weight based on the total 100% by weight of the sewage sludge and the alcohol solvent.

Further, the sewage sludge and the alcohol solvent may be reacted at a temperature of 250 to 600 ° C and a pressure of 30 to 700 bar for 10 seconds to 5 hours to produce biofuel.

The alcohol solvent may include a mixed solvent which is mixed with water at a weight ratio of 7: 3 to 3: 7.

Further manufacturing steps of the bio-oil-in-water is, can be reacted by adding the additive, the additive, LiOH, NaOH, KOH, RbOH , Li 2 CO 3, Na 2 CO 3, K 2 CO 3, Mg (OH) 2 _{, Ca (OH) 2, Sr} (OH) 2, MgCO 3, CaCO 3, SrCO 3, hydrochloric acid (HCl), nitric acid (HNO _3), phosphoric acid (H ₃ PO _4), sulfuric acid (H ₂ SO _4), boric acid (H ₃ BO _3), hydrofluoric acid (HF), carbonic acid (H ₂ CO _3), formic acid (HCOOH), acetic acid (CH ₃ COOH), propionic acid (CH ₃ CH ₂ COOH), butyl acid (CH ₃ CH ₂ CH ₂ COOH), lactic acid (C ₂ H ₄ OHCOOH), and benzoic acid (C ₆ H ₅ COOH).

The present invention can provide the biofuel of the present invention.

The oxygen heavy oil may have an oxygen content of 5 to 20% by weight and the O / C (oxygen / carbon) molar ratio may be 0.05 to 0.25.

The high calorific value (HHV) of the prepared biofuel may be 25 to 45 MJ / kg according to the following equation (3).

&Quot; (3) &quot;

(Where C, H, N, S, and O in Equation (3) are the respective weight ratios of carbon, hydrogen, nitrogen, sulfur, and oxygen to all elements present in the biofuel)

The present invention can provide a fuel for power generation or transportation fuel containing bio-heavy oil.

The method for producing bio-heavy oil using the supercritical alcohol from the sewage sludge according to the present invention can effectively convert the solid-state sewage sludge into the liquid-state heavy oil material without using expensive hydrogen and heterogeneous catalyst provided from the outside And the energy content can be increased by removing a certain amount of oxygen present in sewage sludge.

FIG. 1 shows a result of analysis of biofuel heavy oil produced using methanol in a supercritical state by a gas chromatography-mass spectrometer according to Example 1 of the present invention.
FIG. 2 shows the result of analyzing biofuel heavy oil produced using supercritical ethanol according to the second embodiment of the present invention by a gas chromatography-mass spectrometer. FIG.
FIG. 3 shows a result of analyzing bio-heavy oil produced by using a mixed solvent having a weight ratio of ethanol: water of 3: 7 as a supercritical fluid by a gas chromatography-mass spectrometer according to Example 13 of the present invention.
FIG. 4 is a graph showing the combustion characteristics of the biofuel heavy oil produced in Example 10 of the present invention for a heavy oil boiler. The results of computational fluid dynamics (CFD) analysis of the temperature distribution in the boiler are shown in FIG. .
FIG. 5 shows the average gas temperature according to the height of the boiler by analyzing the combustion characteristics of the biofuel heavy oil manufactured in the tenth embodiment of the present invention with respect to the heavy oil boiler.
6 is a graph showing the results of CFD computation performed on the heat transfer characteristics in the boiler by analyzing the combustion characteristics of the biofuel heavy oil produced in Example 10 of the present invention with respect to the heavy oil boilers.
FIG. 7 is a graph showing the results of analysis of the combustion characteristics of the biofuel heavy oil produced in Example 10 of the present invention with respect to the boiler wall surface and the heat transfer pipe group.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing bio-heavy oil from sewage sludge and a method for producing bio-heavy oil using sewage sludge as a raw material and using a supercritical alcohol as a solvent and a reaction medium, The present invention relates to a method for producing bio-heavy oil having a high yield and a high energy content from sewage sludge by converting a solid organic matter into a liquid organic matter by a low-molecular reaction on an organic matter, removing oxygen existing in a molecular structure of the organic matter contained in the sewage sludge, will be.

The method for producing bio-heavy oil from sewage sludge according to the present invention may include a step of producing bio-heavy oil in which sewage sludge is reacted in a supercritical state of an alcohol solvent to produce bio-heavy oil.

The method for producing bio-heavy oil may further include a step of drying the sewage sludge to dry the sewage sludge before the bio-heavy oil production step.

In addition, the method for producing bio-heavy oil may further include a step of separating and recovering a reaction product for separating and recovering the reaction product produced after the bio-heavy oil production step.

Each step of the manufacturing method according to an embodiment of the present invention will be described in detail.

First, the sewage sludge used in the production of bio-heavy oil according to the present invention is not particularly limited and may include organic by-products generated in a sewage treatment process by the standard activated sludge process, and preferably includes raw sludge, surplus sludge, At least one of sludge, digested sludge, and dehydrated sludge may be included. The water content in the sewage sludge may be 5 to 90% by weight, preferably 10 to 80% by weight, more preferably 20 to 60% by weight. When the moisture content is out of the range of 5 to 90% by weight, there is a problem that biofuel having high energy content can not be produced in high yield.

The process for producing biofuel feedstock according to the present invention is a process for producing biofuel feedstock using sewage sludge as a supercritical alcohol. Specifically, the step of introducing the sewage sludge and the alcohol solvent into the reactor, raising the temperature and pressure of the reactor to the critical temperature and the critical pressure of the alcohol, and reacting the sewage sludge in the supercritical alcohol state. Since the process using the supercritical alcohol according to the present invention is excellent in the ability to stabilize the radicals generated in the low-molecular-weight reaction of the sewage sludge due to the hydrogen generated by itself without supplying hydrogen from the outside, it is possible to suppress condensation or repolymerization reactions that produce solid residues such as char / tar. In addition, since oxygen present in sewage sludge can be effectively removed by a reaction for removing oxygen such as decarboxylation, decarbonylation, and hydrodeoxygenation reaction, The oxygen / carbon (O / C) molar ratio of the heavy oil can be lowered, and the energy content of the bio fuel oil can be increased. In addition to this, unstable intermolecules that occur when the organic matter present in the sewage sludge is decomposed by esterification, alkylation, alkoxylation, etc., unique chemical reactivity of supercritical alcohols Can be stabilized to increase the yield of biofuel.

The alcohol solvent used in the production of the biofuel feedstock may be one for alcohol containing at least one hydroxyl group in the main chain having 1 to 10 carbon atoms. An alcohol in which at least one hydroxyl group is bonded to the main chain having 1 to 7 carbon atoms can be used, but the present invention is not limited thereto. The alcohol solvent can be selected from the group consisting of methanol (critical temperature = 239 DEG C, critical pressure = 81 bar), ethanol (critical temperature = 241 DEG C, critical pressure = 63 bar), propanol (critical temperature = 264 DEG C, critical pressure = 52 bar) (Critical temperature = 307 DEG C, critical pressure = 41 bar), butanol (critical temperature = 289 DEG C; critical pressure = 45 bar), isobutanol (critical temperature = 275 DEG C, critical pressure = 45 bar) (Critical pressure = 42 bar), tert-butanol (critical temperature = 233 캜, critical pressure = 40 bar), n-pentanol (critical temperature = 307 캜, critical pressure = 39 bar), isopentyl alcohol (Critical pressure = 39 bar), 2-methyl-1-butanol (critical temperature = 302 캜, critical pressure = 39 bar), neopentyl alcohol (critical temperature = 276 캜, critical pressure = 40 bar) = Critical temperature = 283 [deg.] C, Critical pressure = 39 bar), Methylpropyl Kinetin (Critical temperature = 287 [ (Critical pressure = 39 bar), dimethylethylquinol (critical temperature = 271 캜, critical pressure = 37 bar), 1-hexanol (critical temperature = 337 캜, critical pressure = 34 bar), 2-hexanol (Critical pressure = 33 bar), 3-methyl-1-pentanol (critical temperature = Pentanol (critical temperature = 387 占 폚, critical pressure = 30 bar), 4-methyl-1-pentanol (critical temperature = 330 占 폚, critical pressure = 30 bar) (Critical pressure = 36 bar), 3-methyl-2-pentanol (critical temperature = 333 캜, critical pressure = 36 bar) (Critical temperature = 303 DEG C, critical pressure = 35 bar), 3-methyl-3-pentanol (critical temperature = 302 DEG C; (Critical pressure = 35 bar), 2,3-dimethyl-1-butanol (critical temperature = 331 캜, critical pressure = 35 bar), 2,2- Dimethyl-1-butanol (critical temperature = 331 캜, critical pressure = 35 bar), 2-ethyl-1- Heptanol (critical temperature = 335 DEG C, critical pressure = 30 bar), 3-heptanol (critical temperature = 307 DEG C, critical pressure = 34 bar) Heptanol (critical temperature = 332 DEG C, critical pressure = 30 bar), and 4-heptanol (critical temperature = 329 DEG C; critical pressure = 30 bar).

The alcohol solvent may include a mixed solvent which is mixed with water at a weight ratio of 7: 3 to 3: 7.

The constitution of the reactor used in the production step of the biofuel feedstock is not particularly limited, but batch type or continuous type reactors can be used.

In addition, the concentration of the sewage sludge introduced into the reactor may be 1 to 80% by weight, preferably 1 to 60% by weight, of the total 100% by weight of the sewage sludge and the alcohol solvent. have. If the concentration of sewage sludge is less than 1% by weight, the concentration is too lean and the amount of bio-heavy oil produced per unit time is too small to be economical. If the amount of sewage sludge exceeds 80% by weight, There is a possibility that an effective low-molecular-weight and oxygen-removing reaction can not be performed from the city sewage sludge, and the uniformity is deteriorated and the quality is deteriorated.

The reaction temperature of the sewage sludge and the alcohol in the bio-heavy oil production step may be 250 to 600 ° C, preferably 300 to 500 ° C. When the reaction temperature is less than 250 ° C., the effective low molecular weight reaction, the hydrogen generation reaction and the oxygen removal reaction of the supercritical alcohol hardly occur, the yield of the biofuel can be lowered, the oxygen content can be increased, There is a problem that the cracking reaction occurs actively, and the raw sewage sludge is gasified, which lowers the yield of biofuel feedstock and reduces the economical efficiency of the conversion process of biofuel feedstock sludge.

The reaction pressure of the sewage sludge and the alcohol in the bio-heavy oil production step may be 30 to 700 bar, preferably 100 to 500 bar. When the reaction pressure is less than 30 bar, the hydrolysis of the supercritical alcohol, the hydrogen generation reaction, and the oxygen elimination reaction capability may be lowered and the yield of the biofuel may be lowered and the oxygen content may be increased. If the reaction pressure exceeds 700 bar, There is a problem in that the process cost for maintaining is increased.

In addition, the reaction time of the sewage sludge and the supercritical alcohol in the production of the biofuel feedstock is not particularly limited, but may be 10 seconds to 5 hours, preferably 1 minute to 2 hours. When the reaction time is less than 10 seconds, the production time of the biofuel is lowered due to the low molecular weight of the supercritical alcohol, the hydrogen generation reaction, and the oxygen removal reaction. Therefore, the yield of the biofuel may be lowered and the oxygen content may be increased. If it exceeds 5 hours, the high temperature and high pressure must be maintained for a long time, so that the process cost is increased.

In the step of preparing the biofuel of the present invention, additives may be further mixed. The additive may include a substance that promotes the generation of hydrogen from the supercritical alcohol or promotes the reaction to remove oxygen present in the biofuel. Examples of the additive include a substance in which an alkali metal such as LiOH, NaOH, KOH, or RbOH is bonded to a hydroxyl group; A substance in which an alkali metal such as Li ₂ CO ₃ , Na ₂ CO ₃ or K ₂ CO ₃ is combined with a carbonate group; A substance in which an alkaline earth metal such as Mg (OH) ₂ , Ca (OH) ₂ , or Sr (OH) ₂ is combined with a hydroxyl group; A substance in which an alkaline earth metal such as MgCO ₃ , CaCO ₃ or SrCO ₃ is bonded to a carbonate group; Inorganic acids such as hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), sulfuric acid (H ₂ SO ₄ ), boric acid (H ₃ BO ₃ ), hydrofluoric acid (HF) and carbonic acid (H ₂ CO ₃ ); Formic acid (HCOOH), acetic acid (CH ₃ COOH), propionic acid (CH ₃ CH ₂ COOH), butyl acid _{(CH 3 CH 2 CH 2 COOH} ), lactic acid (C ₂ H ₄ OHCOOH), and benzoin acid (C ₆ H ₅ COOH), and the like.

The usable concentration of the additive is not particularly limited, but may be 0.1 to 20 wt%, preferably 0.5 to 10 wt%, of the total reactants. If the content of the additive is less than 0.1% by weight, it may be difficult to expect an effective additive effect in the production of biofuel from the sewage sludge. If the content of the additive exceeds 20% by weight, the additive in the supercritical alcohol There is a problem that the use of excessive additives and the cost of separating additive after processing are increased.

The present invention may further comprise a step of drying the sewage sludge to dry the sewage sludge before the step of producing the biofuel.

The drying step of the sewage sludge is a step of removing a certain amount of moisture present after recovering the sewage sludge at a sewage treatment plant. The drying method is not particularly limited, and natural drying and the like can be used. The content of water present in the sewage sludge after drying may be 5 to 90% by weight. Preferably 10 to 80% by weight, and more preferably 20 to 60% by weight. When the moisture content is less than 5% by weight, the energy required for drying is excessively consumed, and the cost of the entire process is excessively increased. When the moisture content exceeds 90% by weight, the energy content There is a problem that a high biofuel can not be produced.

In addition, the present invention may further include a step of separating and recovering the reaction products, which are separated and recovered, after the production step of the biofuel feedstock.

The step of separating and recovering the reaction product is a step of separating and recovering the reaction product by lowering the temperature and pressure after the production step of biofuel. The reaction product may be discharged through a decompression device located at the outlet of the reactor. The reaction product may be in the form of gaseous carbon dioxide, carbon monoxide, methane, ethane, ethylene, propylene, propane, butane, etc. The liquid state material may include the produced heavy fuel oil, the alcohol as a solvent, Organic compounds, reaction byproducts, and the solid state residues may include tungsten, tar, and inorganic materials. At this time, the separation of the gaseous products can be performed by separating the gas and liquid by lowering the temperature and the pressure, and the solid residue can be separated through the solid-liquid separation using a filter, a cyclone or the like. As a method for separating the liquid heavy biofuel from other liquid product or liquid by-product, a general distillation process such as fractional distillation, reduced pressure distillation, and distillation column can be used.

The present invention can provide the biofuel produced by the above method.

The yield of the produced biofuel can be 40 to 90% by weight, preferably 50 to 85% by weight, according to the following formula (1).

[Equation 1]

The bio-heavy oil yield refers to the weight ratio of the reactant to the product (liquid phase) when the solid-state sewage sludge is converted into the liquid phase.

The yield of the solid residue produced according to the production method of bio-heavy oil may be 10 to 45% by weight, preferably 20 to 40% by weight, according to the following formula (2).

&Quot; (2) &quot;

The oxygen content of the bio-heavy oil produced according to the bio-heavy oil production method may be 5 to 20 wt%, and preferably 5 to 15 wt%.

The O / C (oxygen / carbon) molar ratio of the biofuel may be 0.05 to 0.25, preferably 0.05 to 0.19.

The high calorific value (HHV) of the biofuel can be 25 to 45 MJ / kg, preferably 30 to 45 MJ / kg, more preferably 35 to 40 MJ / kg according to the following equation (3).

&Quot; (3) &quot;

(Wherein C, H, N, S, and O are weight ratios (wt%) of carbon, hydrogen, nitrogen, sulfur, and oxygen to all elements present in the biofuel,

Next, the present invention can provide the fuel for power generation or transportation fuel containing the bio-fuel oil produced as described above.

The power generation fuel can utilize the bio fuel oil as a fuel for use as a whole or a mixture thereof, and it can be used for electric power for making full use of bio fuel oil according to the characteristics of the boiler or for making use of bio fuel.

The transportation fuel may be produced by fractionally distilling the biofuel heavy oil at a boiling point and mixing it with a petroleum transportation fuel, and the petroleum transportation fuel may include at least one of gasoline, jet oil, and diesel .

Hereinafter, the present invention will be described in detail with reference to the following examples and comparative examples. However, the present invention is not intended to limit the scope of protection defined by the appended claims.

Example  - Supercritical  Manufacture of biofuel using alcohol

Example  One

The sewage sludge used in this embodiment is dehydrated sludge having a water content of 80% collected at a sewage end treatment plant. A 10 wt% water content sludge was used as a raw material using a centrifugal separator and hot air drying. The sewage sludge used in the present invention has an ash content of 28% by weight, an organic matter content of 72% by weight, a carbohydrate / aliphatic compound content of 30% by weight and an aromatic compound content of 42% by weight. After introducing the dried sewage sludge and methanol at a concentration of 10% by weight into a batch type reactor having a volume of 140 ml, the reactor was pressurized with 10 bar of nitrogen, and the temperature was raised at a rate of about 20 ° C / min. Bio - heavy oil was prepared from supercritical methanol. When the temperature of the reactor reached 400 ° C., the reaction pressure was 365 bar. After 30 minutes, the reaction pressure increased to 397 bar, indicating that the gasification reaction including the reaction of removing oxygen in the reaction of producing biofuel was proceeded . When the temperature of the reactor was lowered to normal pressure after 30 minutes of reaction, the pressure of the gas phase was 25 bar. The gaseous products were collected by Tedlar bag, and the solid and liquid products were separated using a filter. The separation of bio-heavy oil and methanol in the liquid phase was evaluated by evaluating the characteristics of bio-heavy oil produced by fractional distillation and the results are shown in Tables 1 to 3. Further, the result of analysis of the produced biofuel heavy oil by a gas chromatography-mass spectrometer is shown in FIG.

Example  2

The bio-heavy oil was prepared in the same manner as in Example 1 except that ethanol was used as the supercritical fluid. The produced bio-heavy oil was analyzed and the results are shown in Tables 1 to 3. FIG. 2 shows the result of analysis of the bio-heavy oil by the gas chromatography-mass spectrometer.

Example  3

The bio-heavy oil was prepared in the same manner as in Example 1 except that isopropanol was used as the supercritical fluid. The produced bio-heavy oil was analyzed and the results are shown in Tables 1 to 3.

Example  4

The bio-heavy oil was prepared in the same manner as in Example 1 except that butanol was used as the supercritical fluid. The produced bio-heavy oil was analyzed and the results are shown in Tables 1 to 3.

Example  5

Except that the reaction temperature was 350 ° C. The results of the analysis are shown in Tables 1 to 3.

Example  6

The reaction was carried out in the same manner as in Example 1, except that the reaction temperature was 300 ° C. The biofuel heavy oil was analyzed and the results are shown in Tables 1 to 3.

Example  7

And the reaction time was 120 minutes. The results of the analysis are shown in Tables 1 to 3.

Example  8

The bio-heavy oil was prepared in the same manner as in Example 1 except that a mixed solvent having a weight ratio of methanol: water of 7: 3 was used as a supercritical fluid. The produced bio-heavy oil was analyzed, Respectively.

Example  9

The bio-heavy oil was prepared in the same manner as in Example 1 except that a mixed solvent having a weight ratio of methanol: water of 5: 5 was used as a supercritical fluid. The produced bio-heavy oil was analyzed, Respectively.

Example  10

The bio-heavy oil was prepared in the same manner as in Example 1 except that a mixed solvent having a weight ratio of methanol: water of 3: 7 was used as a supercritical fluid. The produced bio-heavy oil was analyzed, Respectively.

Example  11

The bio-heavy oil was prepared in the same manner as in Example 1 except that a mixed solvent having a weight ratio of ethanol: water of 7: 3 was used as a supercritical fluid. The produced bio-heavy oil was analyzed, Respectively.

Example  12

Was prepared in the same manner as in Example 1 except that a mixed solvent of ethanol and water in a weight ratio of 5: 5 was used as a supercritical fluid. The bio-heavy oil was analyzed, Respectively.

Example  13

The bio-heavy oil was prepared in the same manner as in Example 1 except that a mixed solvent having a weight ratio of ethanol: water of 3: 7 was used as a supercritical fluid. The produced bio-heavy oil was analyzed, Respectively. FIG. 3 shows the result of analysis of the bio-heavy oil by the gas chromatography-mass spectrometer.

Example  14

The bio-heavy oil was prepared in the same manner as in Example 1 except that 5% by weight of Na ₂ CO ₃ was used as an additive. The produced bio-heavy oil was analyzed and the results are shown in Tables 1 to 3.

Example  15

The bio-heavy oil was prepared in the same manner as in Example 1 except that 5% by weight of HCOOH was used as an additive. The produced bio-heavy oil was analyzed and the results are shown in Tables 1 to 3.

Example  16

The bio-heavy oil was prepared in the same manner as in Example 1 except that 5 wt% of KOH was used as an additive. The produced bio-heavy oil was analyzed and the results are shown in Tables 1 to 3.

<Characteristic analysis of biofuel>

The final yield of biofuel was obtained from the weight of each component in accordance with the following formulas (1) to (3).

[Equation 1]

&Quot; (2) &quot;

&Quot; (3) &quot;

(Where C, H, N, S, and O in Equation (3) are the respective weight ratios of carbon, hydrogen, nitrogen, sulfur, and oxygen to all elements present in the biofuel)

The yields of liquid, solid and gaseous materials in the production of biofuel using supercritical alcohols calculated according to the above equations are shown in Table 1 below.

Supercritical fluid reaction
Temperature
(° C) reaction
pressure
(bar) reaction
time
(minute) additive Bio fuel oil
yield
(wt%) solid
Residue
yield
(wt%) weather
yield
(wt%) Example 1 Supercritical methanol 400 365-397 30 - 50.8 32.7 4.4 Example 2 Supercritical ethanol 400 285-322 30 - 88.9 32.4 3.9 Example 3 Supercritical isopropanol 400 239-320 30 - 53.2 34.8 3.2 Example 4 Supercritical butanol 400 164-197 30 - 83.6 31.3 4.2 Example 5 Supercritical methanol 350 265-277 30 - 55.4 36.0 0.3 Example 6 Supercritical methanol 300 165-186 30 - 62.3 40.2 0.2 Example 7 Supercritical methanol 400 337-406 120 - 52.9 34.0 4.4 Example 8 Supercritical
Methanol: water = 7: 3 400 372-402 30 - 51.4 31.3 3.7 Example 9 Supercritical
Methanol: water = 5: 5 400 368-393 30 - 53.9 29.9 1.2 Example 10 Supercritical
Methanol: water = 3: 7 400 349-363 30 - 57.5 30.1 3.0 Example 11 Supercritical
Ethanol: water = 7: 3 400 336-362 30 - 60.8 31.4 1.0 Example 12 Supercritical
Ethanol: water = 5: 5 400 348-371 30 - 72.3 31.1 14.3 Example 13 Supercritical
Ethanol: water = 3: 7 400 336-359 30 - 51.3 29.1 1.2 Example 14 Supercritical methanol 400 360-395 30 Na ₂ CO ₃ 82.4 29.5 2.2 Example 15 Supercritical methanol 400 380-420 30 HCOOH 75.9 29.4 5.5 Example 16 Supercritical methanol 400 355-401 30 KOH 79.2 29.8 2.7

As shown in Table 1, when the bio-heavy oil was prepared from sewage sludge using methanol, ethanol, isopropanol, and butanol in the supercritical state in Examples 1 to 4, the liquid phase yield of the produced bio-heavy oil was 50 To 89% by weight, a solid residue yield of 31 to 35% by weight, and a vapor phase yield of less than about 5% by weight. Considering that 28 wt% of the component contained in the raw sewage sludge can not be converted into vapor or liquid phase, 31 to 35 wt% of the solid residue contains 3 to 7 wt% of organic matter , It can be seen that most of the organic matter has been converted into gas phase and liquid phase, and that the vapor yield is as low as 5 wt%, indicating that most of the organic matter present in the sewage sludge has been converted into the liquid phase. This is because supercritical alcohols can effectively provide hydrogen to inhibit the condensation or the repolymerization reaction that produces solid residues and can be used for esterification, The alkylation and the alkoxylation were effectively promoted to stabilize unstable intermediates which are generated when the organic substances present in the biofuel feedstock are decomposed, thereby increasing the liquid yield.

On the other hand, when the reaction temperatures of supercritical methanol were lowered to 350 ° C. and 300 ° C. in Examples 5 to 6, respectively, the yield of solid residue was increased to 36% by weight and 40% by weight respectively, It can be seen that the conversion rate of organic substances existing therein is somewhat lowered, but the liquid phase yield is maintained as high as 55 to 62 wt%.

 On the other hand, even when the reaction time was increased to 120 minutes in Example 7, the yield of the solid residue was maintained as low as 34% by weight, indicating that most of the organic matter present in the sewage sludge was converted into a liquid phase and a gas phase. On the other hand, it can be seen that the liquid phase yield was maintained at a very high level of 53% by weight, and the gas phase yield was 4 wt%, which was very similar to the gas phase yield of Example 1, and the gasification reaction that could occur due to the long reaction was suppressed.

On the other hand, in Examples 8 to 10, when a mixture of methanol and water having various weight ratios was used as a supercritical solvent, the yield of the solid residue was 30 to 31 wt%, and the inorganic matter content of the sewage sludge was 28 wt% , It can be seen that most organic matter present in the sewage sludge has been converted into liquid and vapor phase. In addition, the liquid yield was maintained at 51 to 58 wt%, which was very high, and the vapor yield was 3 to 4 wt%, indicating that most of the organic materials were converted to the liquid phase.

Further, even when a mixture of ethanol and water having various weight ratios in Examples 11 to 13 was used as a supercritical solvent, most of the organic substances present in the sewage sludge were in a liquid state It can be seen that the conversion has been made.

On the other hand, when Na ₂ CO ₃ , HCOOH and KOH were used as additives in Examples 14 to 16, the yield of solid residue was 30% by weight, which was very similar to the inorganic content of sewage sludge of 28% It can be seen that most of the organic matter present in sewage sludge has been converted into liquid and vapor phase. Also, the liquid yield was 75 to 83 wt%, which was higher than that of Example 1, and it was found that most of the organic matter was converted into a liquid phase at a vapor yield of 2 to 6 wt%.

Next, the characteristics of the sewage sludge before the reaction and the characteristics of the biofuel produced after the reaction were analyzed, and the components of the gas reaction products were analyzed in Table 2 below.

Elemental analysis of the reactants was performed using an elemental analyzer (EA, Vario EL cube, Elementar Analysensystem GmbH) equipped with a thermal conductivity detector (TCD).

Meanwhile, the qualitative and quantitative analysis of gas reaction products was carried out by gas chromatography (GC) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID), Clarus 600 GC-Model Arnel 1115PPC Refinery Gas Analyzer (RGA), PerkineElmer).

C
(wt%) O
(wt%) H
(wt%) N
(wt%) S
(wt%) O / C
ratio HHV
(MJ / kg) Sewage sludge 38.9 23.2 3.6 6.4 1.1 0.45 16.3 Example 1 71.8 13.2 6.6 6.2 0.8 0.14 32.0 Example 2 71.5 8.2 7.2 5.0 1.2 0.09 33.1 Example 3 70.3 10.5 8.3 7.0 2.2 0.11 34.2 Example 4 71.5 10.8 9.2 6.5 2.1 0.11 35.6 Example 5 66.5 14.8 8.1 7.2 0.9 0.17 32.0 Example 6 58.8 15.1 7.8 7.7 0.7 0.19 29.0 Example 7 73.3 9.6 8.2 5.2 0.5 0.10 34.7 Example 8 72.1 11.4 9.0 5.4 0.7 0.12 35.2 Example 9 74.3 9.0 9.0 4.9 0.9 0.09 36.1 Example 10 76.0 9.1 9.1 5.1 0.9 0.09 36.8 Example 11 71.0 10.2 9.2 5.7 1.1 0.11 35.2 Example 12 71.8 10.9 8.9 5.5 1.3 0.11 35.1 Example 13 75.5 8.0 9.4 5.3 1.8 0.08 37.3 Example 14 68.0 9.2 8.8 6.8 0.9 0.10 33.8 Example 15 71.2 9.5 8.2 5.4 1.0 0.10 34.1 Example 16 70.8 9.3 9.1 5.1 0.9 0.10 35.1

CO ₂
(mol%) CO
(mol%) H ₂
(mol%) CH ₄
(mol%) C ₂ H ₄ +
C ₂ H ₆
(mol%) C ₃ H ₆ +
C ₃ H ₈
(mol%) C4 +
(mol%) Meteor yield
(wt%) Example 1 31.6 10.9 23.6 7.7 21.2 3.7 1.1 4.4 Example 2 23.3 6.8 3.6 48.9 4.9 2.2 0.7 3.9 Example 3 33.0 3.8 0.2 49.0 6.8 4.0 2.2 3.2 Example 4 15.0 19.2 19.0 6.5 19.6 19.7 0.8 10.4 Example 5 14.8 15.2 20.2 4.2 15.8 8.9 0.5 0.3 Example 6 0.8 2.2 95.3 0.4 21.2 0.1 0.0 0.2 Example 7 30.0 28.3 1.8 7.1 29.1 3.2 0.4 4.4 Example 8 37.3 7.0 10.0 30.9 9.7 3.2 1.7 3.7 Example 9 51.0 12.1 7.4 10.3 16.7 2.4 0.0 1.2 Example 10 20.0 13.5 33.0 6.1 23.3 3.1 0.9 3.0 Example 11 21.4 24.5 0.5 7.2 42.1 3.5 1.3 1.0 Example 12 13.7 54.6 4.3 5.9 19.8 1.1 0.5 14.3 Example 13 69.0 8.0 0.5 5.8 14.3 1.5 0.4 1.2 Example 14 35.2 15.2 12.2 7.8 15.3 3.4 4.2 2.2 Example 15 33.4 17.8 13.2 7.2 17.4 4.5 4.6 5.5 Example 16 25.8 25.2 11.0 8.9 19.9 3.1 2.8 2.7

As shown in Table 2, the carbon content of sewage sludge was as low as 38.9% by weight, the oxygen content was as high as 23.2% by weight, the oxygen / carbon molar ratio was as high as 0.45 and the high calorific value (HHV) 16.3MJ / kg.

When the bio-heavy oil was prepared using supercritical alcohols in Examples 1 to 4, the carbon content of the liquid phase increased and the oxygen content decreased to decrease the O / C molar ratio from 0.09 to 0.14, And the HHV was greatly increased from 32.0 to 35.6 MJ / kg, indicating that the energy content was increased.

As shown in the above Table 3, the components of the gaseous products of Example 1 were analyzed to find that CO (10.9 mol%) and CO ₂ (31.6 mol%) were detected in an excessive amount, and decarbonylation and decarboxylation It was found that the oxygen contained in the sewage sludge was removed by the reaction, and excessive amount of H ₂ (23.6 mol%) was detected. Supercritical methanol generated hydrogen, It was found that the produced liquid phase yield was high due to inhibition of recombination or condensation reaction that could occur. It was also found that a small amount of C ₃ H ₆ + C ₃ H ₈ (3.7 mol%) and C 4 + (1.1 mol%) were detected and the cracking reaction of the organic substances contained in the sewage sludge was inhibited.

On the other hand, when the reaction temperatures were maintained at 350 ° C and 300 ° C in Examples 5 to 6, the O / C molar ratios were reduced to 0.17 and 0.19, respectively, and the HHV values were 32.0 and 29.0 MJ / , But it is very high when compared with the HHV of sewage sludge.

On the other hand, when the reaction time was increased to 120 minutes in Example 7, the O / C molar ratio was greatly reduced to 0.1 and the HHV was greatly increased to 34.7 MJ / kg. Most of the produced gases were CO mol%) and CO ₂ (30.0 mol%), indicating that decarbonylation and decarboxylation reaction were actively performed and oxygen was effectively removed.

On the other hand, when the mixture of methanol and water having various weight ratios was used as a supercritical solvent in Examples 8 to 10, the O / C molar ratio was greatly reduced to 0.09 to 0.12 and the HHV was 35.2 to 36.8 MJ / kg And most of the generated gas was CO and CO ₂ , indicating that de-carbonylation and decarboxylation reactions were actively performed to effectively remove oxygen, and that the hydrogen content was 7.4 to 33.0 mol% And it was found that hydrogen generation was actively occurred in the mixed solvent.

Also, when the mixture of ethanol and water having various weight ratios was used as a supercritical solvent in Examples 11 to 13, the O / C molar ratio was greatly reduced to 0.08 to 0.11, and the HHV was 35.1 to 37.3 MJ / kg And most of the generated gas is CO and CO ₂ , which shows that de-carbonylation and decarboxylation reaction actively occurred, and oxygen was effectively removed, and a small amount of C3 + and C4 + was produced. The cracking reaction Is effectively suppressed.

On the other hand, when Na ₂ CO ₃ , HCOOH and KOH were used as additives in Examples 14 to 16, the O / C molar ratio was further reduced to 0.1 and the HHV was 33.8 to 35.1 MJ / kg And it was found that the deoxygenation reaction was more actively occurred. In addition, when the additive is used, most of the generated gases are CO and CO ₂ , indicating that de-carbonylation and decarboxylation reactions are actively performed to effectively remove oxygen, and a small amount of C3 + and C4 + It can be seen that the reaction was effectively inhibited.

Experimental Example

Computational Fluid Dynamics (CFD) was performed on heavy oil boilers of Ulsan power to investigate the feasibility of applying the biofuel heavy oil produced in the examples to thermal power plants. The size of the heavy oil boiler of Ulsan Thermal Power Plant is 10m x 12.6m x 56m, the heat input is 1025MW _th , and the turbine power is 405MW _e . The combustion characteristics of the biofuel produced in Example 10 were analyzed for a heavy oil boiler of Ulsan Thermal Power.

The computational flow analysis for the boiler of Ulsan heavy oil boiler was analyzed and analyzed for the emulsion condition of heavy oil produced in petrochemical refinery, the mixed condition of 80 wt% of petrochemical heavy oil emulsion and 20 wt% of bio-heavy oil derived from sewage sludge .

In the case of Ulsan thermal power boiler, the heat input of the turbine is 405MW _{e and} the heat input is about 1025MW _th . The Ulsan thermal power heavy oil boiler uses a swirl burner and the flow rates are all divided equally. In addition, the swirl direction was set by the gear train method and the analysis was carried out. The burner swirl was assumed to have an axial: tangential ratio of 1: 0.8. The analysis conditions of the Ulsan thermal power oil boiler are shown in Table 4 below.

Operating condition Heavy oil Heavy oil 80% + Bio heavy oil 20% Heat input (MW _th ) 1025.1 1025.0 Turbine output (MW _e ) 405.1 405.0




Fuel Throughput 24.697 19.75 (heavy oil) / 5.93 (bio heavy oil) Temperature (℃) 107 107 Heavy oil Bio fuel oil Water content (%) 0.5 5.39 Volatile matter (%) 94.342 94.38 Fixed carbon (%) 5 0 Ashes (%) 0.158 0.23 C (%) 86.5 73.26 H (%) 10.8 8.198 O (%) 0.202 9.558 N (%) 0.458 5.19 S (%) 2.04 0.453 HHV (MJ / kg) 41.51 34.59 Emulsion Flow rate (kg / s) 2.57 2.06 Spray steam Temperature (℃) 346 346 Flow rate (kg / s) 1.611 1.611
air Excess air (%) 1.19 4.6 Flow rate (kg / s) 344.25 361 Temperature (℃) 312 312

Fig. 4 shows the CFD computation results of the temperature distribution in each boiler. When 20% of biofuel oil was mixed, the temperature inside the boiler was higher than that of heavy oil. It is considered that the gas temperature in the boiler has risen due to the rapid ignition of biofuel in comparison with the emulsion type heavy oil containing water. Since the gear train system is used like the heavy oil boiler and the internal structure of the boiler is symmetrical, most characteristics such as flow rate, chemical species, and heat flux distribution as well as temperature distribution are symmetrical in the front and rear direction, .

On the other hand, the average gas temperature according to the height of the boiler is shown in Fig. It can be seen that the average gas temperature of bio-heavy oil 20% condition is high as a whole.

In addition, CFD computational analysis was performed to analyze the heat transfer characteristics in the boiler, and the results are shown in FIG. As in the case of the heavy oil burning condition, the symmetrical tendency was shown even under the condition of 20% bio fuel oil, and the heat flux was the highest in front of the burner of the third stage. The maximum heat flux of 364 kW / m ² for 20% heavy fuel oil compost was reduced to a maximum of 480 kW / m ² for the heavy oil fired power plant, but the tendency was similar to that of the heavy fuel oil fired power plant. It was confirmed that biofertile oil produced from boa sewage sludge could be mixed. It is considered that the difference in the distribution of the wall surface heat flux is due to the difference in the radiation characteristics depending on the amount of soot. Since soot is produced more fuel oil with more heavy fuel, the heavy oil burning condition is the largest with 3 wt%, and the concentration of soot is decreased when the fuel is added.

Fig. 7 shows the amounts of heat transferred from the boiler wall surface and each heat transfer pipe group. In the case of heavy fuel oil burned around the walls are higher in calories 473MW _th, the case of 20% bio-fuel oil dual fuel showed a slight decrease in calories wall around 425MW _th. In the case of 20% biofuel heavy oil, the amount of heat in the rear heat pipe group increased by 3 ~ 9MW _{th in} each heat pipe group as the wall heat transfer decreased.

As a result of computer analysis of heavy oil and bio fuel oil contamination, it was verified that bio fuel oil produced from sewage sludge could be used as a compost.

The configuration of the present invention has been proved to be superior through the above-described embodiments, but is not necessarily limited to the above configuration, and various permutations, modifications and variations are possible without departing from the technical idea of the present invention. Therefore, the above description does not limit the scope of the present invention, which is defined by the limitations of the following claims.

Claims (17)

A method for producing biofuel from sewage sludge,
A method for producing bio-heavy oil, comprising the step of producing bio-heavy oil by reacting sewage sludge in a supercritical state of an alcohol solvent at a pressure of 164 bar or more with sewage sludge and alcohol. The method according to claim 1,
Further comprising a step of drying the sewage sludge to dry the sewage sludge before the step of preparing the biofuel feedstock. The method according to claim 1,
Further comprising the step of separating and recovering the reaction product for separating and recovering the produced reaction product after the step of producing the biofuel feedstock. The method according to claim 1,
Wherein the sewage sludge comprises at least one of raw sludge, excess sludge, concentrated sludge, digested sludge, and dehydrated sludge. 5. The method of claim 4,
Wherein the sewage sludge has a moisture content of 5 to 90% by weight. The method according to claim 1,
The alcohol solvent may be at least one selected from the group consisting of methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutanol, 2-butanol, tert-butanol, n- pentanol, isopentyl alcohol, Methyl-1-pentanol, 3-methyl-1-pentanol, 2-methyl-1-pentanol, Methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3- Dimethyl-1-butanol, 2,3-dimethyl-1-butanol, 2-ethyl 1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, and 4-heptanol. The method according to claim 1,
Wherein the sewage sludge comprises 1 to 80% by weight of a total of 100% by weight of sewage sludge and an alcohol solvent. The method according to claim 1,
Wherein the sewage sludge and the alcohol solvent are reacted at a temperature of 250 to 600 ° C. delete The method according to claim 1,
Wherein the reaction is carried out in a supercritical state of the alcohol solvent for 10 seconds to 5 hours. The method according to claim 1,
Wherein the alcohol solvent comprises a mixed solvent which is mixed with water at a weight ratio of 7: 3 to 3: 7. The method according to claim 1,
Wherein the step of preparing the biofuel feedstock comprises adding an additive and reacting the biofuel feedstock. 13. The method of claim 12,
The additive, LiOH, NaOH, KOH, RbOH , Li 2 CO 3, Na 2 CO 3, K 2 CO 3, Mg (OH) 2, Ca (OH) 2, Sr (OH) 2, MgCO 3, CaCO 3 , SrCO _3, hydrochloric acid (HCl), nitric acid (HNO _3), phosphoric acid (H ₃ PO _4), sulfuric acid (H ₂ SO _4), boric acid (H ₃ BO _3), hydrofluoric acid (HF), carbonic acid (H ₂ CO ₃ ), formic acid (HCOOH), acetic acid (CH ₃ COOH), propionic acid (CH ₃ CH ₂ COOH), butyl acid (CH ₃ CH ₂ CH ₂ COOH), lactic acid (C ₂ H ₄ OHCOOH), and benzoin acid ( C ₆ H ₅ COOH). &Lt; / RTI &gt; A biofuel feed produced by the method of any one of claims 1 to 8 and 10 to 13. 15. The method of claim 14,
Wherein the biofuel has an oxygen content of 5 to 20 wt% and an O / C (oxygen / carbon) molar ratio of 0.05 to 0.25. 15. The method of claim 14,
Wherein the high calorific value (HHV) of the biofuel is 25 to 45 MJ / kg according to the following formula (3).
&Quot; (3) &quot;

(Where C, H, N, S, and O in Equation (3) are the respective weight ratios of carbon, hydrogen, nitrogen, sulfur, and oxygen to all elements present in the biofuel) A fuel for power generation or transportation fuel containing the biofuel of claim 14.

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