BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a general flow diagram showing a method of manufacturing cellulose acetate according to the present invention.
FIG. 2 is a flow sheet of the specific processes.
FIG. 3 is a schematic diagram of the structure of a superheated steam generator.
FIG. 4 is a schematic explanatory view of the superheated steam generator.
FIG. 5 is an explanatory view showing an example of a row of line parts in the line viewed from a point taken by the arrows V-V in FIG. 4.
FIG. 6 is an explanatory view showing another example of the rowing of line parts in the line.
FIG. 7 is a diagram of properties (substituting for drawings) showing results of experiments proving functions of the superheated steam generator.
FIG. 8 is a schematic longitudinal side view of a high temperature steam reactor vessel.
FIG. 9 is a front view schematically showing an appearance of the high temperature steam reactor vessel.
FIG. 10 is a front view schematically showing an appearance of an acetylating reactor vessel.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a flow diagram showing a method of manufacturing cellulose acetate according to the present invention. As seen, the manufacturing method involves the steaming process, purifying process, and acetylating process. These processes will be explained hereunder with referring to the flow sheet expressed in FIG. 2.
FIG. 2 shows the steaming process referred to in FIG. 1 with a surrounding chain line denoted by the reference numeral 1, the purifying process with that denoted by 2, and the acetylating process with that denoted by 3.
(Steaming Process)
The steaming process 1 involves and performs such process that corncob powder (“corncob meal”) which an example of collective chips of wooden material is subjected to addition of solid catalyst and placed in a pressure vessel the inside of which is applied superheated steam having ultra high temperature.
Solid catalyst to be added to the collective chips of a wooden material may selectively employ one kind of substance or plural kinds of substances among platinum, titanium oxide, cerium oxide, yttrium oxide, thorium oxide, tin oxide, zinc oxide, manganese oxide, aluminum oxide, silicon oxide, and vanadium oxide. In this embodiment each of titanium oxide, yttrium oxide, cerium oxide and thorium oxide, as solid alkaline catalyst, among those was solo used.
Corncob powder was attempted to be used in the form of collective of chip's simple substances having particle size dispersion of 0.01 to 5 mm in length conversion, of 0.05 to 2 mm, or of 0.1 to 1 mm. As a result, it was found that when the collective of chip's simple substances having particle size dispersion of 0.01 to 5 mm is employed, each chip simple substance is sufficiently applied with action of steaming by superheated steam, so that the entire collective of chips are uniformly steamed, thereby increasing collection rate of cellulose content. It was moreover found that in case of the particle size dispersion of 0.05 to 2 mm, and of 0.1 to 1 mm, there is obtainable such action that sizes of chip simple substances contained in the collective chips are averaged up or equalized to enable steaming action by superheated steam to be efficiently carried out, whereby readily shortening time for steaming process and also readily controlling temperatures and pressure of superheated steam, the condition for steaming process.
Loadings of the solid catalyst was attempted in such manner of being 1 to 20 wt %, 3 to 15 wt %, and 5 to 10 wt % with respect to dried corncob powder. Found in the extent 1 to 20 wt % was that the quantity of solid catalyst was appropriate and sufficient action of catalyst was expressed. Further found was that such results also notably appear in the cases of loadings of 3 to 15 wt % and 5 to 10 wt %.
Temperatures of superheated steam were set to be 400 to 800° C., and pressure inside the pressure vessel was kept to be 0.1 to 5 MPa. Also attempted were temperatures of superheated steam of 500 to 700° C., and 550 to 600° C., and modified pressure inside the pressure vessel of 0.2 to 3 MPa and 0.5 to 1 MPa.
From hydrolysis in the steaming process 1, hemicellulose (soluble xylan) was obtained as well in addition to cellulose content. Thus, the cellulose content was subjected to purifying process 2 after the steaming process. The purifying process 2 is carried out for separating or taking out the cellulose content from or of products and residues from the hydrolysis reaction in the steaming process 1. As seen in FIG. 2, the steps of filtration, washing, and drying were performed to collect the cellulose content. Additionally, the above-mentioned hemicellulose was separated, and solid catalyst was also collected for re-use.
Time selected for the steaming process was 15 to 240 min, 30 to 180 min and 45 to 120 min.
(Purifying Process)
Under every foregoing specific conditions (temperatures of superheated steam, pressure, and kinds of solid catalyst) cellulose content separated through the purifying process 2 was not inferior in whiteness degree to cellulose content obtainable by use of cotton as material.
(Acetylating Process)
Acetylating process 3 includes such step that cellulose content and glacial acetic acid are caused to react with each other in order to produce cellulose acetate and acetic acid. In detail, the cellulose content together with solid acid and glacial acetic acid are placed in a pressure vessel to have dehydration and displacement (oxidation) under conditions of high temperatures and high pressure. Purified matter and residue through the acetylating process 3 were subjected to the steps of filtration and washing to separate cellulose acetate while collecting filtrate and catalyst, catalyst being applied to re-use.
Although the acetylating process 3 did not make use of sulfuric acid which is used in the acetylating in the conventional manufacturing method referred to at the beginning of this specification, cellulose acetate suitably applicable to usage for a material of biodegradation plastic was obtained. In detail, acetylation rate of cellulose acetate was 55.2%-57.0%, and whiteness degree was 92%.
It was confirmed that solid acid to be usable in the acetylating process 3 are mordenite, clinoptilolite, and synthetic zeolite. Also confirmed was that loadings of solid acid may be 1 to 20 wt % with respect to the dried cellulose content, preferably 3 to 15 wt % and more preferably 5 to 10 wt %.
It was confirmed that loadings of glacial acetic acid to be used in the acetylating process 3 may be 300 to 700 wt % with respect to the dried cellulose content, preferably 400 to 600 wt % and more preferably 450 to 500 wt %.
It was confirmed that temperatures for acetylation reaction in the acetylating process 3 may be suitably 70 to 130° C. preferably 80 to 120° C., and more preferably 90 to 110° C.
It was confirmed that conditions of pressure in the acetylating process 3 may be 0.1 to 5 MPa, preferably 0.2 to 3 MPa, more preferably 0.5 to 1 MPa.
Time for acetylation reaction may be suitably 30 to 300 min, preferably 80 to 240 min, more preferably 120 to 180 min.
Next, a superheated steam generator to be used in the steaming process 1, a high temperature steam reactor vessel as a pressure vessel to be used in the steaming process 1, and an acetylating reactor vessel to be used in the acetylating process will be explained.
(Superheated Steam Generator)
FIG. 3 is a schematic diagram of the structure of a superheated steam generator. FIG. 4 is a schematic explanatory view of the superheated steam generator. FIG. 5 is an explanatory view showing an example of a row of line parts in the line viewed from a point taken by the arrows V-V in FIG. 4. FIG. 6 is an explanatory view showing another example of the rowing of line parts in the line. And FIG. 7 is a diagram of properties (substituting for drawings) showing results of experiments proving functions of the superheated steam generator.
In FIG. 3, reference numeral 10 denotes a superheated steam generator, and 10A a steam boiler. The steam boiler 10A may employ those which is able to generate steam, preferably has capability of generating steam of 110 to 130° C.
A basic structure of the superheated steam generator 10 comprises a heating region Z which is realized by operation of a burner 20 and a heat-exchange line 30 comprising piping. The heating region Z has heating with a heating function of the burner 20 arranged below the heat-exchange line 30. The heat-exchange line 30 is provided with a steam introduction port 31 through which introduced into the generator is steam produced in the foregoing steam boiler 10A, and a steam taking out port 32 for taking out superheated steam.
In the superheated steam generator, the heat-exchange line 30 schematically illustrated in FIG. 4 is sectioned into plural stages of line parts extending from the steam introduction port 31 to the steam taking out port 32. A sectional area of the line part on a stage at a downstream side is larger than that of the line part on a stage at an upstream side. Next, an example of its concrete structure will be explained.
In the superheated steam generator 10 in the example shown in FIG. 4, the heat-exchange line 30 arranged in the heating region Z is sectioned into line parts P1, P2, P3 on three stages extending from the steam introduction port 31 to the steam taking out port 32. The line part P1 on the first stage and the line part P2 on the second stage extend to connect with each other as being rowed up in parallel, so that steam flowing through the line part P1 and the line part P2 flows in the direction of counter-current as shown. Similarly, the line part on the second stage P2 and the line part on the third stage P3 extend to connect with each other as being rowed up in parallel, so that steam flowing through the line parts P2 and P3 flows in the direction of counter-current. In FIG. 4, the direction of flow of steam is indicated by arrows. As seen also in FIG. 5, line parts P1, P2 and P3 on three stages employ line part bodies having the same sectional area (diameter). And each line part P1, P2, P3 on respective stage may employ different number of line part bodies so that the second stage line part P2 has a larger sectional area than the first stage line part P1, and the third stage line part than the second stage line part. In more detail, the number of line part bodies used for the second stage line part P2 (the shown example using two line part bodies) is set to be twice that used for the first stage line part P1 (the shown example using one line part body), whereby the second stage line part P2 is provided with twice the sectional area of the first stage line part P1. Similarly, the number of line part bodies used for the third stage line part P3 (the shown example using four line part bodies) is set to be twice that used for the second stage line part P2 (the shown example using two line part bodies), whereby the third stage line part P3 is provided with twice the sectional area of the second stage line part P2. Hence, regarding sectional area of each of the line parts P1, P2, P3 sectioned into three stages, there is seen the sectional area becomes twice each time the number of stage rises one by one. That is, sectional area of the line parts P1, P2, P3 sectioned into three stages is proportional to the number of stages.
In the superheated steam generator 10 explained with referring to FIGS. 4 and 5, the line parts P1, P2, P3 on the respective stages are adapted to communicate with each other in a manner of turning back and winding, so that the whole of the heat-exchange line 30 can be made compact in comparison with the case that the line parts P1, P2, P3 are communicated with each other linearly or in a manner of being a straight line.
FIG. 6 shows another example of a superheated steam generator 10 having line parts of the line rowed up in a different manner from FIG. 4.
In FIG. 6, 10 denotes a superheated steam generator, and 20 a burner. In this example, a heat-exchange line 30 arranged in the heating region Z is sectioned into line parts P1, P2, P3, and P4 on four stages extending from a steam introduction port (not shown) to a steam taking out port (not shown). And the line part P1 on the first stage and the line part P2 on the second stage extend to connect with each other as being rowed up in parallel, so that steam flowing through the line part P1 and the line part P2 flows in the direction of counter-current as shown. Similarly, the line part P2 on the second stage and the line part P3 on the third stage extend to connect with each other as being rowed up in parallel, so that steam flowing through the line parts P2 and P3 flows in the direction of counter-current. Further, the line part P3 on the third stage and the line part P4 on the fourth stage extend to connect with each other as being rowed up in parallel, so that steam flowing through the line parts P3 and P4 flows in the direction of counter-current.
Also, as seen in FIG. 6, in this example, the line parts P1, P2, P3, P4 in four stages of the heat-exchange line 30 employ line part bodies having the same sectional area (diameter). And each line part P1, P2, P3, P4 on respective stage may employ different number of line part bodies so that the second stage line part P2 has a larger sectional area than the first stage line part P1, and the third stage line part P3 than the second stage line part P2, and the fourth stage line part P4 than the third stage line part P3. In more detail, the number of line part bodies used for the second stage line part P2 (the shown example using two line part bodies) is set to be twice that used for the first stage line part P1 (the shown example using one line part body), whereby the second stage line part P2 is provided with twice the sectional area of the first stage line part P1. Similarly, the number of line part bodies used for the third stage line part P3 (the shown example using four line part bodies) is set to be twice that used for the second stage line part P2 (the shown example using two line part bodies), whereby the third stage line part P3 is provided with twice the sectional area of the second stage line part P2. Furthermore, the number of line part bodies used for the fourth stage line part P4 (the shown example using eight line part bodies) is set to be twice that used for the third stage line part P3 (the shown example using four line part bodies), whereby the fourth stage line part P4 is provided with twice the sectional area of the third stage line part P3. Hence, regarding sectional area of each of the line parts P1, P2, P3, P4 sectioned into four stages, there is seen the sectional area becomes twice each time the number of stage increases one by one. That is, similarly to the examples explained with referring to FIGS. 2 and 3, sectional area of the line parts P1, P2, P3, P4 sectioned into four stages is proportional to the number of stages.
In this example, the heating region Z has heating with a heating function of a burner 20 arranged below a heat-exchange line 30. Among line parts P1, P2, P3, P4 formed by sectioning the heat-exchange line 30 into four stages, any line part on a stage at a downstream side is arranged below a line part on a stage at an upstream side, such two line parts being on stages occurring one after another and adjoining to each other. Thus, the fourth stage line part P4 corresponding to a line part on a final stage is arranged below the line parts P1, P2 and P3 on the first to third stages.
In the superheated steam generator 10 in this example, the line parts P1, P2, P3, P4 on the respective stages are adapted to communicate with each other in a manner of turning back and winding and also adapted to be rowed up vertically, so that the whole of the heat-exchange line 30 can be made compact, although having a relatively large number of line part stages, in comparison with the case that the line parts P1, P2, P3, P4 are communicated with each other linearly or in a manner of being a straight line, and that explained with referring to FIG. 4.
FIG. 7 shows Test results carried out for proving function of the superheated steam generator explained with referring to FIG. 6. A steam boiler 10A shown in FIG. 3 was used and the test result was obtained. In detail, steam of 110° C. generated by the steam boiler 10A was introduced into a steam introduction port 31 of the superheated steam generator 10 shown in FIG. 6. The number of stages of the line parts was five, and arrangement of the line parts had the “turn back” structure based on and according to the feature explained with referring to FIG. 6. Line part bodies employ stainless steel pipe of 15 mm diameter and 450 mm length. And line part bodies on any stages adjoining to each other are connected to each other by use of a stainless steel header. The number of line part bodies to form specific line parts on respective stages is one for a first stage, two for a second stage, four for a third stage, eight for a fourth stage, and sixteen for a fifth stage. A burner to be operated for forming the heating region employs a propane gas burner for a water heater (50000 Kcal). For the burner, those using kerosene or fuel oil as fuel may be usable in place of the propane gas burner for a water heater.
As seen in FIG. 7, steam which has 110° C. of steam introduction port temperature becomes 185° C. in the first stage line part, 272° C. in the second, 405° C. in the third, 580° C. in the fourth, and 775° C. in the fifth. Temperature of steam rises almost proportionally to and following rise of the number of stage as above, and steam of nearly 800° C. was able to be taken out of the steam taking out port. Meanwhile, steam injection pressure into the steam introduction port was determined to be 0.2 MPa. With the steam taking out port being kept open, pressure in the line parts on the first to fifth stages was kept constant near 0.3 MPa. There was not found that pressure extremely rises at the steam taking out port in comparison with the steam introduction port.
From this, it was found that pressure proof efficiency of the line part bodies to form the specific stage line parts may be a feature covering a level of about 0.3 MPa irrespective of the number of stages. Further, ultra high temperature steam of 775% taken out of the steam taking out port was supplied at pressure of 0.1 to 5 MPa to a pressure vessel for steaming process so as to be applied to steaming in a manufacturing process of cellulose acetate using corncob meal as a material. It was confirmed that the superheated steam generator is usable as an efficient source of supply of superheated steam for the purpose of the steaming process.
(High Temperature Steam Reactor Vessel)
FIG. 8 is a schematic longitudinally sectional side view of a high temperature steam reactor vessel. The high temperature steam reactor vessel comprises a reactor vessel body 40 and a cartridge 50 in the form of a bucket in which collective chips T is filled. The reactor vessel body 40 is hollow and comprises a longitudinally elongated trunk 41 having at an upper part a steam introducing port 42 and at a lower part a drain outlet 43 and an air discharge port 44. In the example, the reactor vessel is provided at the top with a pressure gauge 45. The cartridge 50 comprises a cylindrical body in the form of a bucket being opened at the upper end and having a bottom and provided with a bottom plate 51 having a lot of apertures 52 for allowing steam to flow through the same, and a tubular trunk plate 53 rising from the bottom plate 51 on its periphery. The cartridge 50 is mounted in a space between the steam introducing port 42, drain outlet 43 and air discharge port 44 inside the reactor vessel body 40. On the inner surface of the bottom plate 51 of the bottomed cylindrical body by which the cartridge 50 is formed, there is attached a net body 55 (mesh) which has air holes smaller in size than the apertures 52 of the bottom plate 51 for steam flowing through and is made of stainless steel or rustless steel.
FIG. 9 is a front view schematically showing an appearance of a high temperature steam reactor vessel. As shown, the reactor vessel body 40 is provided at the upper part with a lid 46. The lid 46 is detachable through a tightening means 47. The lid 46 is removed to enable the cartridge 50 housed inside to be detachable.
In the high temperature steam reactor vessel constructed as above, the cartridge 50 filled with the collective chips T to be subjected to be processed with steam is housed in the reactor vessel body 40 as shown in FIG. 8, and high temperature superheated steam from the steam introducing port 42 is supplied. The superheated steam passes through the layer of collective chips T and goes out through the steam-flow apertures 52 of the bottom plate 51 of the bottomed cylindrical body to form the cartridge 50. And steam and liquid residue and gas from hydrolysis reaction flowing out of the steam-flow apertures 52 are collected through the drain outlet 43 and air discharge port 44.
The high temperature steam reactor vessel may be usually plurally usable and installed in parallel so that when one of the high temperature steam reactor vessels is in operation, the remaining ones may be subjected to collecting and replacing cartridges and filling and taking collective chips in and out of the cartridge. By this, such convenience is provided to enable continuous operation of hydrolysis reaction process by use of plurality of high temperature steam reactor vessels.
In the shown example, the cartridge 50 is applied with the net member 55 for the purpose of processing collective chips of smaller particle size. In case that there is no fear of flow-out of chips from the apertures 52 of the bottom plate 51 thanks to a larger particle size of chips of the collective chips T, the net member 55 may be omitted. The high temperature steam reactor vessel when used enables that collective chips T after the steaming process may be removed together with the cartridge from the reactor vessel body 40 and be subjected to after-treatment.
(Acetylating Reactor Vessel)
FIG. 10 is a front view schematically showing appearance of an acetylating reactor vessel. The acetylating reactor vessel comprises a superheat jacket 60 having an inlet 61 for cellulose content, an inlet 62 for solid catalyst and solid acid, an inlet 63 for superheated steam serving as a heat source, an inlet 64 for glacial acetic acid, a drain outlet 65, cellulose acetate outlet 66, and an inlet 67 for additive, and an agitating blade 68 inside the vessel. The acetylating reactor vessel may properly employ a material such as stainless steel and titanium applied with anti-corrosion treatment in response to requirement of being excellent in acid proof and having high rigidity.
Patent Application
20070249824
