JP2008192423A - Treatment method of glycerin, and treatment device of glycerin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method of glycerin and its treatment device wherein this has an energetic advantage and this is effective in environmental aspect. <P>SOLUTION: This is the treatment device of glycerin which is equipped with a blending part 8 in which glycerin 1a is blended with a discharge gas which contains carbon dioxide and steam formed in a molten carbonate type fuel cell 5, a reaction container 2 to which molten carbonate 2a is supplied, in which glycerin mixture from this blending part 8 is housed, and in which a fuel gas is generated that contains hydrogen and carbon monoxide, and the molten carbonate type fuel cell 5 which generates electric power while supplying the fuel gas generated in this reaction container 2 to the negative electrode side 5a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glycerin treatment method and a glycerin treatment apparatus for gasifying and reusing glycerin, and more specifically, for use in power generation by gasifying glycerin using molten carbonate to form a fuel gas for a fuel cell. The present invention relates to a glycerin treatment method and a glycerin treatment apparatus.

  Fatty acid esters produced by a transesterification reaction between vegetable oils such as rapeseed and sunflower or waste edible oils and short-chain alcohols such as methanol and ethanol have been put into practical use as light oil alternative fuels. In this reaction, fatty acid ester is generated by transesterification and glycerin is by-produced.

  In the transesterification reaction, an alkali catalyst such as sodium hydroxide or potassium hydroxide is generally used as a catalyst and remains in the byproduct glycerin. Regarding the treatment of by-product glycerin containing this alkali catalyst, alcohol removal, neutralization treatment, salt removal, and further purification and recovery as glycerin, as described in Non-Patent Document 1, There is a process of converting to potassium dihydrogen phosphate or the like by neutralization treatment with acid addition and using alkali as a fertilizer.

  However, these methods are not very useful in terms of environment and economy because of high processing costs and generation of a large amount of waste water.

For this reason, most of the by-product glycerin is incinerated as industrial waste. Patent Document 1 proposes a method of gasifying by-product glycerin with water vapor, performing a methanol synthesis reaction based on the generated synthesis gas of H ₂ and CO, and recovering it as methanol.

  However, in the incineration process and the gasification method, the mixed alkali catalyst becomes fine ash and a large amount of dust needs to be removed. As described above, regarding the treatment of by-product glycerin in the production of fatty acid ester, there is a problem that there is no effective method from the viewpoint of energy and environment.

Naomi Kitagawa et al. “Biodiesel Fuel Production Technology-Current Status and Prospects”, Chemical Engineering Vol. 70, No. 8 (issued on August 5, 2006) JP 2005-154647 A

  Accordingly, an object of the present invention is to provide a method for treating glycerin and an apparatus for treating glycerin that are advantageous in terms of energy and effective from the viewpoint of the environment.

The above object can be achieved by the present invention as described below.
That is, the method for treating glycerin according to the present invention comprises a step of mixing an exhaust gas containing carbon dioxide and water vapor generated in a molten carbonate fuel cell with glycerin to obtain a glycerin mixture, and converting the glycerin mixture into molten carbonate. Supplying a fuel gas containing hydrogen and carbon monoxide, and supplying a gas containing oxygen and carbon dioxide to the anode side while supplying the fuel gas to the cathode side of the molten carbonate fuel cell. And generating the exhaust gas on the cathode side by performing power generation.

  According to the glycerin treatment method of the present invention, since the glycerin mixture contains water vapor, hydrogen and carbon monoxide can be efficiently generated by supplying the molten carbonate to the molten carbonate fuel cell. It can be used for power generation (electric energy generation) by using gas. In addition, the high-temperature carbon dioxide and water vapor generated in the molten carbonate fuel cell can be mixed with glycerin and used, so the exhaust gas can be reduced and the exhaust heat can be used, which is advantageous in terms of energy. Become. Furthermore, even when an alkali metal is contained in glycerin, it can be efficiently removed with molten carbonate, so that no special treatment of alkali metal is required. As a result, it is possible to provide a method for treating glycerin that is energetically advantageous and effective from the environmental viewpoint.

  Since the alkali metal can be efficiently removed with molten carbonate, the present invention is particularly effective when the glycerin to be mixed contains an alkali metal.

  Moreover, it is preferable that the said molten carbonate is a molten carbonate containing 2 or more types of lithium carbonate, sodium carbonate, or potassium carbonate. By using such mixed molten carbonate, it is possible to approach the electrolyte composition of a molten carbonate fuel cell (generally eutectic mixture is used), and even when molten carbonate is scattered, its effect should be reduced. Can do. It is also possible to lower the melting point of the molten carbonate used. From this viewpoint, the molten carbonate used is preferably a eutectic carbonate.

  On the other hand, the processing apparatus for glycerin according to the present invention includes a mixing unit for mixing exhaust gas containing carbon dioxide and water vapor generated in a molten carbonate fuel cell with glycerin, and a molten carbonate containing a glycerin mixture from the mixing unit. A reaction vessel for generating a fuel gas containing hydrogen and carbon monoxide, and supplying a gas containing oxygen and carbon dioxide to the anode side while supplying the fuel gas generated in the reaction vessel to the cathode side. And a molten carbonate fuel cell for generating electric power.

  According to the glycerin processing apparatus of the present invention, since the glycerin mixture from the mixing section contains water vapor, hydrogen and carbon monoxide can be efficiently generated by supplying the molten carbonate contained in the reaction vessel. By using this as the fuel gas of the molten carbonate fuel cell, it can be used for power generation (electric energy generation). In addition, the high-temperature carbon dioxide and water vapor generated in the carbonate fuel cell can be mixed with glycerin, so that the exhaust gas can be reduced and the exhaust heat can be used, which is advantageous in terms of energy. . Furthermore, even when an alkali metal is contained in glycerin, it can be efficiently removed with molten carbonate, so that no special treatment of alkali metal is required. As a result, it is possible to provide an apparatus for treating glycerin that is advantageous in terms of energy and effective from the viewpoint of the environment.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1: shows the schematic block diagram of an example of the processing apparatus of the glycerol of this invention. First, the outline | summary of the processing apparatus of the glycerol of this invention is demonstrated.

  As shown in FIG. 1, the glycerin treatment apparatus of the present invention includes a molten carbonate fuel cell 5, a mixing unit 8 for mixing the exhaust gas with glycerin 1a, and a reaction vessel 2 containing molten carbonate 2a. Is provided.

  The mixing unit 8 is a part that mixes exhaust gas containing carbon dioxide and water vapor generated in the molten carbonate fuel cell 5 with glycerin 1a. In this embodiment, an example provided with the glycerol supply means which supplies glycerol 1a using the glycerol supply pump 3 from the glycerol tank 1 is shown.

  The exhaust gas supply pipe is provided with a flow rate adjusting valve 7 to adjust the flow rate of the exhaust gas to be supplied. Further, the exhaust gas supply pipe merges with the supply pipe from the glycerin supply means in the mixing section 8.

  The reaction vessel 2 contains the molten carbonate 2a, and the glycerin mixture from the mixing unit 8 is supplied to the molten carbonate 2a through the supply pipe to generate fuel gas containing hydrogen and carbon monoxide. The reaction vessel 2 is provided with a lead-out pipe 2c having an on-off valve 2b so that the molten carbonate 2a can be led out.

  The reaction vessel 2 is provided with a fuel gas supply pipe 2d connected to the cathode side 5a of the molten carbonate fuel cell 5, through which fuel gas generated is supplied to the cathode side 5a.

  The molten carbonate fuel cell 5 performs power generation by supplying a gas containing oxygen and carbon dioxide to the anode side 5c while supplying fuel gas to the cathode side 5a. As the molten carbonate fuel cell 5, any known one can be used. For example, the molten carbonate fuel cell 5 includes a molten carbonate 5m, the anode side 5c is connected to the gas supply pipe and the discharge pipe, and the cathode side 5a. The fuel gas supply pipe 2d and the discharge pipe are connected to each other. Examples of the molten carbonate 5 m include those exemplified as the molten carbonate 2 a of the reaction vessel 2.

  In the present embodiment, as means for supplying gas containing oxygen and carbon dioxide to the anode side 5c, air from the air blower 6 as air supply means and a part of the exhaust gas discharged from the cathode side 5a are mixed. An example provided with the combustor 5b to be burned is shown. Thus, by burning the exhaust gas from the cathode side 5a, carbon dioxide required for the reaction on the anode side 5c of the molten carbonate fuel cell 5 can be generated.

  A check valve 9 is provided in a supply pipe for supplying a part of the exhaust gas to the combustor 5b. Thereby, the backflow of the gas from the combustor 5b is prevented.

  Next, although the processing method of glycerol of this invention is demonstrated, the processing method of glycerol of this invention can be implemented suitably with the processing apparatus of glycerol of this invention.

  The method for treating glycerin according to the present invention includes a step of mixing the exhaust gas containing carbon dioxide and water vapor generated in the molten carbonate fuel cell 5 with glycerin 1a to obtain a glycerin mixture.

  The glycerin to be treated may not contain an alkali metal, but in the present invention, since the alkali metal can be efficiently removed with a molten carbonate, the present invention is used when the glycerin to be mixed contains an alkali metal. Is particularly effective.

  Examples of the glycerin containing an alkali metal include glycerin produced as a by-product by a transesterification reaction between a vegetable oil such as rapeseed or sunflower or waste edible oil and a short-chain alcohol such as methanol or ethanol.

  The exhaust gas generated by the cathode side reaction of the molten carbonate fuel cell 5 is a mixed gas of carbon dioxide and water vapor (partially containing hydrogen and carbon monoxide). A part of the supply amount of the exhaust gas is supplied to the mixing unit 8 while being adjusted by the flow rate control valve 7 in conjunction with the supply amount of glycerin 1a.

  The exhaust gas temperature when exiting the cathode side 5a of the molten carbonate fuel cell 5 is, for example, 600 to 700 ° C., and can be used as a heat source for gasification reaction, leading to effective use of exhaust heat. improves. Such high-temperature exhaust gas can cause decomposition and vaporization of the mixed glycerin 1a.

  The mixing ratio when mixing the glycerin 1a and the exhaust gas is glycerin from the viewpoint of promoting the reaction formula (2) in the gasification of the glycerin 1a and suppressing the carbon deposition in the gasifier. The water vapor is preferably 50 to 500 parts by weight, more preferably 100 to 200 parts by weight with respect to 100 parts by weight.

  The processing method of glycerol of this invention has the process of supplying this glycerol mixture to molten carbonate 2a, and generating the fuel gas containing hydrogen and carbon monoxide. It was confirmed by experiments that the molten carbonate 2a has activity as a gasification catalyst for a glycerin mixture.

  In the present invention, glycerin is gasified in a molten bed. For example, regarding gasification by a molten bed, a method of gasifying sodium hydroxide as a reaction medium is conceivable. However, alkali hydroxides are too high in activity and therefore poor in handling, and change to carbonates during use, so there is a concern that the melting point will rise. On the other hand, in the present invention, carbonate is used as the molten salt, and carbon dioxide is supplied as needed, so that it is stable as carbonate, and such a problem does not occur.

  The molten carbonate 2a is preferably a carbonate containing an alkali metal such as lithium, sodium, or potassium, and more preferably a molten carbonate containing two or more of lithium carbonate, sodium carbonate, or potassium carbonate.

  When carbonate is used alone, it has a high melting point (724 ° C. for lithium carbonate, 855 ° C. for sodium carbonate, 900 ° C. for potassium carbonate), and is susceptible to material limitations. Therefore, it is preferable to mix eutectic carbonates by mixing two or more of these salts because the melting point is lowered.

By using the molten carbonate 2a, the alkali catalyst mixed in glycerin can be trapped in the molten salt. Eutectic carbonate is also an electrolyte for molten carbonate fuel cells (MCFC) (for example, 62% Li ₂ CO ₃ -38% K ₂ CO ₃ ), so in the unlikely event that molten salt scatters, Since it is not affected at all, it is possible to generate power with high efficiency using fuel gas (H ₂ , CO) generated by molten salt gasification.

  The temperature of the molten carbonate 2a is preferably 600 to 900 ° C, more preferably 700 to 800 ° C. Therefore, the reaction vessel 2 is preferably provided with a heating means capable of adjusting the temperature in this way. When the temperature exceeds 900 ° C., the molten carbonate 2a is significantly scattered, and heat dissipation tends to be large, resulting in a large energy loss.

For example, when KOH that is a transesterification reaction catalyst is contained in glycerin 1a, if K is accumulated, the ratio of Li and K in molten carbonate 2a changes and the melting point changes, so that Li ₂ CO ₃ is appropriately replenished. Then, the Li / K ratio may be adjusted. Excess molten carbonate 2a may be extracted from the outlet tube 2c.

  The glycerin treatment method of the present invention performs power generation by supplying a gas containing oxygen and carbon dioxide to the anode side 5c while supplying this fuel gas to the cathode side 5a of the molten carbonate fuel cell 5. Generating the exhaust gas on the cathode side 5a.

  The fuel gas containing hydrogen and carbon monoxide generated in the reaction vessel 2 is supplied to the cathode side 5a of the molten carbonate fuel cell 5, and the reaction of hydrogen proceeds according to the reaction formula (1). Further, with respect to carbon monoxide, hydrogen is generated by the shift reaction of reaction formula (2) using water vapor contained in the fuel gas and water vapor generated in reaction formula (1), and reaction formula (1) The reaction proceeds at. Some carbon monoxide proceeds in the reaction formula (3). Since the gas after the reaction formulas (1), (2) and (3) becomes an exhaust gas containing carbon dioxide and water vapor as described above, a part of this gas is used as a gasifying agent.

Reaction formula (1): H ₂ + CO ₃ ²⁻ → H ₂ O + CO ₂ + 2e ⁻
Reaction formula (2): CO + H ₂ O → H ₂ + CO ₂
Reaction formula (3): CO + CO ₃ ²⁻ → 2CO ₂ + 2e ⁻
On the other hand, on the anode side 5b, the reaction proceeds according to the reaction formula (4). The electrons generated by the reaction formulas (1) and (3) pass through a load or resistance connected to the outside, and the electrons are consumed in the reaction formula (4) to supply power to the outside.

Reaction formula (4): CO ₂ + 1 / 2O ₂ + 2e ⁻ → CO ₃ ²⁻
For this reason, a gas containing oxygen and carbon dioxide is supplied to the anode side 5 b of the molten carbonate fuel cell 5. This gas is obtained by mixing a part of the exhaust gas from the cathode side 5a with the air supplied by the air blower 6, burning unreacted hydrogen and carbon monoxide, and containing oxygen and carbon dioxide. It is a thing.

  As described above, according to the present invention, the by-product glycerin containing an alkali catalyst in the methyl esterification reaction of vegetable oil does not require an extra step such as neutralization or purification, and does not generate alkaline ash, thereby achieving high efficiency power generation. It can be disposed of as fuel and energy can be used effectively. Further, by combining the gas generated by gasification with a molten carbonate fuel cell, it is possible to absorb the scattering of the molten salt during gasification and contribute to the reduction in the number of equipment required for purification and the reduction in running costs. In addition, by taking measures to prevent molten salt scattering (filters, scrubbers, etc.) in molten carbonate fuel cells, by-product glycerin molten carbonate gasification gas can be used as gas engine fuel and methanol synthesis raw material. .

[Another embodiment]
(1) In the above-described embodiment, an example of a glycerin supply unit using a pump has been described. However, glycerin is supplied, such as a supply unit that supplies glycerin using a liquid level difference or a supply unit that uses an ejector. Any can be used.

  (2) In the above-described embodiment, an example in which the glycerin mixture that has passed through the mixing unit is bubbled into the molten carbonate has been shown, but any supply method may be used as long as the glycerin mixture and the molten carbonate can be contacted. .

  (3) In the above-described embodiment, as shown in FIG. 1, as the means for supplying gas to the anode side 5c, air from the air blower 6 as air supply means and exhaust gas discharged from the cathode side 5a are used. Although the example provided with the combustor 5b which mixes and burns with the part was shown, the gas containing the oxygen and carbon dioxide supplied to the anode side 5c may be supplied without using the exhaust gas from the cathode side 5a Good. In that case, there is a method of supplying carbon dioxide from a gas cylinder or supplying carbon dioxide generated by combustion using another fuel.

Hereinafter, an experimental example for confirming the effect of the present invention will be described. Experimental Example As an experimental example, an example of a gasification reaction using a molten carbonate as a gasification catalyst is shown. FIG. 2 shows a schematic configuration diagram of the experimental apparatus in the example.

Using this experimental apparatus, 300 g of a molten carbonate obtained by mixing Li ₂ CO ₃ and K ₂ CO ₃ at a molar ratio of 62:38 was prepared and placed in an alumina crucible. The mixed carbonate was melted by heating to a predetermined temperature. The alkali-containing waste glycerin used in the experiment is rapeseed white oil (made by Showa Sangyo Co., Ltd.) and methanol (purity 99% or more, manufactured by Kishida Chemical Co., Ltd.) potassium hydroxide (purity 85% or more, manufactured by Kishida Chemical Co., Ltd.) ) Was used as a catalyst for the transesterification reaction at 60 ° C. for 1 hour, and then the glycerin layer recovered by stationary separation was used. The property analysis results of the waste glycerin are shown in Table 1 together with the analysis method.

This waste glycerin was added at 1 mL / min. , CO ₂ at 1 L / min. The molten carbonate was mixed and supplied, and the outlet gas concentration was measured with various analyzers. Experiment temperature was 600 degreeC, 750 degreeC, and 800 degreeC. The reaction was carried out rapidly immediately after the waste glycerin was fed at all experimental temperatures. Table 2 shows the main gas component concentrations measured when the steady state was reached. The content of these gas components is a result of measurement with a Gachsromatograph GC-8A (manufactured by Shimadzu Corporation) and an automobile exhaust gas measuring device MEXA-554J (manufactured by Horiba, Ltd.).

  Although the gasification rate was low at 600 ° C., almost the same result was obtained at 750 ° C. or higher, and gas having sufficient properties as a fuel for the molten carbonate fuel cell was generated using the generated gas component. Moreover, alkali content is not confirmed in generated gas, but it is thought that KOH contained in glycerol was trapped in the molten carbonate. Therefore, molten carbonate has high activity as a gasification catalyst, absorbs alkali contained in waste glycerin, and can eliminate the adverse effects of alkali ash.

The schematic block diagram of an example of the processing apparatus of the glycerol of this invention Schematic configuration diagram of experimental apparatus in Examples

Explanation of symbols

1a Glycerin 2 Reaction vessel 2a Molten carbonate 5 Molten carbonate fuel cell 5a Cathode side 8 of molten carbonate fuel cell Mixing section

Claims (4)

Mixing an exhaust gas containing carbon dioxide and water vapor generated in a molten carbonate fuel cell with glycerin to obtain a glycerin mixture;
Supplying the glycerin mixture to molten carbonate to generate a fuel gas containing hydrogen and carbon monoxide;
Supplying the gas containing oxygen and carbon dioxide to the anode side while supplying the fuel gas to the cathode side of the molten carbonate fuel cell, and generating the exhaust gas on the cathode side; ,
Of treating glycerin.   The method for treating glycerin according to claim 1, wherein the glycerin to be mixed contains an alkali metal.   The method for treating glycerin according to claim 1 or 2, wherein the molten carbonate is a molten carbonate containing two or more of lithium carbonate, sodium carbonate, or potassium carbonate. A mixing unit for mixing exhaust gas containing carbon dioxide and water vapor generated in a molten carbonate fuel cell with glycerin;
A reaction vessel that is supplied to molten carbonate containing the glycerin mixture from the mixing section and generates a fuel gas containing hydrogen and carbon monoxide;
A molten carbonate fuel cell for generating electricity by supplying a gas containing oxygen and carbon dioxide to the anode side while supplying the fuel gas generated in the reaction vessel to the cathode side;
An apparatus for treating glycerin.

Images