Recover of inorganic chemicals of the pulp and paper making processes using microwaves and related techniques

Abstract

There is described a process for the recovering of inorganic chemicals of pulp and paper making processes (IC) and the production of biochemicals from black liquor (BL) using microwaves (MW) comprising: (a) filtration of BL to produce filtered BL, in a media, (b) drying of said filtered BL with MW in said media to produce dried BL, (c) pyrolysis of said dried BL with MW in said media to produce bio-oil, biogas, and solid residue, (d) recovering of said bio-oil, and (e) recovering of IC and biocarbon from said solid residue. The disclosed process does not require chemical additives compared to processes rely on precipitation of lignin to recover said IC. The disclosed process supports efficient, direct, and long-lasting reductions in greenhouse gas emissions and local air pollutants resulting from the current processes rely on burning BL in recovery boilers to recover said IC.

Claims

1. A process for the recovering of inorganic chemicals of pulp and paper making processes (IC) and the production of biochemicals from black liquor (BL) using microwaves (MW) comprising: (a) filtration of BL to produce filtered BL, in a media, (b) drying of said filtered BL with MW in said media to produce dried BL, (c) pyrolysis of said dried BL with MW in said media to produce bio-oil, biogas, and solid residue, (d) recovering of said bio-oil, in a condensation system operating at a temperature about dew point of compounds to be recovered, and (e) recovering of IC and biocarbon from said solid residue.

2. A process according to claim 1, wherein said drying is performed for a time sufficient to allow generation of heat, providing thermal drying at a temperature of about 105° C.

3. A process according to claim 2, wherein said drying is performed through absorption of MW by said filtered BL, water content in said filtered BL, and/or said media; wherein said filtered BL and water are efficient to absorb MW and generate heat to initiate said drying.

4. A process according to claim 1, wherein said pyrolysis is performed for a time sufficient to allow generation of heat, providing thermal decomposition at a temperature higher than that of said drying and enough to decompose most of the chemical bonds of said dried BL, leading to separating volatiles from fixed carbon bonds and said IC.

5. A process according to claim 4, wherein said pyrolysis is performed at a temperature from about 200° C. to about 800° C.

6. A process according to claim 4, wherein said pyrolysis is performed through absorption of MW by said dried BL, water content in said dried BL (if any), and/or said media; wherein high dielectric properties of said dried BL at a frequency of MW dielectric constant: 7.1±0.2 and dielectric loss factor: 2.5±0.1 at 2.45 GHz) makes BL highly efficient to absorb MW and generate heat to initiate said pyrolysis.

7. A process according to claim 6, wherein said pyrolysis is initiated after oxygen content within said media is purged and reached at a suitable residual content for said pyrolysis to be proceed (about 4% volume basis).

8. A process according to claim 1, wherein said condensation system composing of a single condenser operating at a temperature about 5° C., which is sufficient to condense vapor produced from said pyrolysis as a mixture of chemical compounds.

9. A process according to claim 1, wherein said condensation system composing of multiple condensers operating at temperatures sufficient to condense vapor produced from said pyrolysis of said dried BL in different stages, based on dew point of compounds to be recovered as individual chemical families.

10. A process according to claim 1, wherein said solid residue is processed to recover said IC and said biocarbon using aqueous phase collected from said filtration of BL, and/or condensed steam from said drying of said filtered BL.

11. A process according to claim 10, wherein said IC and biocarbon are obtained at an average yield of 22 wt. % and 18 wt. %, respectively, of said dried BL.

12. A process according to any one of claims 10 and 11, wherein said IC is dissolved in aqueous phase collected from said filtration of BL, and/or condensed steam from said drying of filtered BL, and sent to digester of pulp and paper making process for aquatic and said IC recycling.

13. A process according to claim 10, wherein said solid residue is burned to recover said IC directly and its thermal value.

14. A process according to claim 1, wherein said process is batch operated, semi-batch operated, or continuous-flow operated.

15. A process according to claim 1, wherein inner wall temperature of said media is increased to about 150° C. to avoid condensation and/or solidification of materials thereon, and at the same time it does not negatively impact the yield and quality of said bio-oil, said biocarbon said biogas, and said IC.

16. A process according to claim 14, wherein said process is directly integrated into existing pulp and paper making processes for on-site application, separated from existing pulp and paper making processes for central application, or combinations of thereof.

17. A process according to claim 1, wherein said process further comprising a MW generator system to provide the needed electromagnetic waves for said drying of said filtered BL, said pyrolysis of said dried BL, and/or any other purposes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combinations with the appended drawings, in which:

(2) FIG. 1 illustrates a flowchart of the disclosed process for the recovering of inorganic chemicals of the pulp and paper making processes (IC) and the production of biochemicals from black liquor (BL) using microwaves (MW);

(3) FIG. 2 illustrates the effect of pyrolysis temperature on the yield of the pyrolysis products after said pyrolysis of said dried BL;

(4) FIG. 3 illustrates the effect of pyrolysis temperature on the yield of the separated IC from said solid residue after said pyrolysis of said dried BL;

(5) It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION OF THE DISCLOSURE

(6) In embodiments, there is disclosed a microwave recovery process for the recovering of inorganic chemicals of pulp and paper making processes (IC) and the production of biochemicals from black liquor (BL) using microwaves (MW) comprising: (a) filtration of BL to produce filtered BL, in a media, (b) drying of said filtered BL with MW in said media to produce dried BL, (c) pyrolysis of said dried BL with MW in said media to produce bio-oil, biogas, and solid residue, (d) recovering of said bio-oil, in a condensation system operating at a temperature about dew point of compounds to be recovered, and (e) recovering of IC and biocarbon from said solid residue.

(7) In embodiments, said process may be batch operated, semi-batch operated, or continuous-flow operated.

(8) In embodiments, said process may be directly integrated into existing pulp and paper making processes for on-site application, or separated from existing pulp and paper making processes for central application.

(9) In some embodiments, said filtration of BL 1, said drying of said filtered BL 2, said pyrolysis of said dried BL 3 may be repeated once or more.

(10) In embodiments, said process further comprising a MW generator system to provide the needed electromagnetic waves for said drying of said filtered BL and said pyrolysis of said dried BL, and/or for, any other purposes.

(11) In some embodiments, said MW may be applied at a frequency range from about 915 MHz to about 2450 GHz, or higher, or lower.

(12) In embodiments, the firm interaction between MW and BL is a crucial factor behind employing of MW in said drying of said filtered BL and said pyrolysis of said dried BL.

(13) In embodiments, the measured dielectric properties of said dried BL at 2.45 GHz are tabulated in Table 1.

(14) TABLE-US-00001 TABLE 1 Dielectric properties of dried black liquor and carbon at 2.45 GHz Material Dielectric constant (F/m) Dielectric loss factor (F/m) Black Liquor 7.1 ± 0.2 2.5 ± 0.1 Carbon 7.0 ± 0.1 2.0 ± 0.2

(15) In embodiments, said dielectric properties demonstrate the strong ability of said dried BL to convert MW energy to heat energy. It is well known that carbon is one of the most active MW receptors and, consequently, used as a MW thermal catalyst in several reactions. Since the dielectric properties of said dried BL are higher than carbon, said dried BL is stronger to absorb MW and generate heat than carbon.

(16) In embodiments, the experimental measurements show that at the same MW power, exposure time, and other conditions, said dried BL reaches a temperature of 20% higher than that of carbon.

(17) In embodiments, said filtration of BL may be performed at ambient temperature, ambient pressure, any temperature and pressure conditions, or combinations of thereof.

(18) In some embodiments, said filtered BL have a higher solid concentration than the non-filtered BL, for example from about 30% to about 80%.

(19) In some embodiments, said filtration of BL may be performed in said media or in a separate media.

(20) In embodiments, said drying of said filtered BL and said pyrolysis of said dried BL may be performed at ambient pressure or any pressure conditions.

(21) In embodiments, said filtered BL is heated up to a temperature sufficient to evaporate water content in BL.

(22) In embodiments, said drying of said filtered BL may be performed for a time sufficient to allow generation of heat, providing thermal drying at a temperature depends on characteristics of said filtered BL, and/or any other aspects.

(23) In some embodiments, said drying of said filtered BL is performed at a temperature about 105° C., or higher, or lower.

(24) In some embodiments, said drying of said filtered BL may be performed through absorption of MW by said filtered BL, water content in said filtered BL, and/or said media.

(25) In embodiments, said filtered BL and water are efficient to absorb MW and generate heat to initiate said drying.

(26) In some embodiments, said drying of said filtered BL may be performed through hybrid drying such that heat is provided through (1) absorption of MW by said filtered BL, water content in said filtered BL, and/or said media; and (2) conventional heating.

(27) In embodiments, steam and/or water vapor produced from said drying of said filtered BL may be used to purge said media.

(28) In embodiments, said pyrolysis of said dried BL may be performed for a time sufficient to allow generation of heat, providing thermal decomposition at a temperature higher than that of said drying of said filtered BL and enough to decompose most of the chemical bonds of said dried BL, leading to separating volatiles from fixed carbon bonds and said IC.

(29) In some embodiments, said temperature of said pyrolysis of said dried BL depends on the characteristics of said dried BL, and/or any other aspects.

(30) In some embodiments, said temperature of said pyrolysis of said dried BL is performed at a temperature less than the melting point of the IC to be recovered.

(31) In some embodiments, said pyrolysis of said dried BL may be performed at a temperature from about 200° C. to about 800° C.

(32) In embodiments, said pyrolysis of said dried BL may be performed through absorption of MW by said dried BL, water content in said dried BL (if any), and/or said media.

(33) In some embodiments, said dried BL may be exposed to a MW power higher than that of said drying of filtered BL.

(34) In embodiments, said dried BL is efficient to absorb MW and generate heat to initiate said pyrolysis reaction, for the high dielectric properties of said dried BL at a frequency of MW, refer to Table 1.

(35) In embodiments, said pyrolysis of said dried BL may be performed through hybrid pyrolysis such that heat is provided through (1) absorption of MW by said dried BL, water content in said dried BL (if any), and/or said media, and (2) conventional heating.

(36) In embodiments, said pyrolysis of said dried BL may be initiated after oxygen content within said media is purged and reached at a suitable residual content for said pyrolysis to be proceed (about 4% volume basis).

(37) In some embodiments, said conventionnel heating may be provided through electric heaters, burning the biogas produced from said pyrolysis of said dried BL, burning said solid residue, any other heating mechanism, or combinations of thereof.

(38) In embodiments, said condensation system may be performed at a temperature sufficient to maintain the vapor produced from said pyrolysis of said dried BL liquid.

(39) In embodiments, said condensation system 5 may be performed at a temperature around the dew point of the chemicals to be recovered.

(40) In some embodiments, said condensation system may be composed of a single condenser operating at a temperature sufficient to condense the vapor produced from said pyrolysis of said dried BL as a mixture of chemical compounds.

(41) In some embodiments, said condensation system may be composed of a set of condensers operating at a temperature sufficient to condense the vapor produced from said pyrolysis of said dried BL as a mixture of chemical compounds.

(42) In some embodiments, said temperature sufficient to condense the vapor produced from said pyrolysis of said dried BL as a mixture of chemical compounds is about 5° C., or higher, or lower, depending on the dew point of the compounds to be recovered, and or any other aspects.

(43) In some embodiments, said condensation system may be composed of multiple condensers operating at different temperatures sufficient to condense the vapor produced from said pyrolysis of said dried BL in different stages based on the dew point of the compounds to be recovered as individual chemicals or individual chemical families, and/or any other aspects.

(44) In some embodiments, said condensation system may be composed of multiple condensers operating at different temperatures sufficient to separate the organic chemicals from the aqueous phase produced from said pyrolysis of said dried BL.

(45) In some embodiments, the first condenser—or the first set of condensers—of said multiple condensers may be operating at a temperature or temperatures sufficient to condense the heavy molecular weight compounds produced from said pyrolysis of said dried BL, for example from about 120° C. to about 150° C., depending on the compounds to be recovered.

(46) In some embodiments, the second condenser—or the second set of condensers—of said multiple condensers may be operating at a temperature or temperatures sufficient to condense the medium molecular weight compounds produced from said pyrolysis of said dried BL, for example from about 80° C. to about 110° C., depending on the compounds to be recovered.

(47) In some embodiments, the third condenser—or the third set of condensers—of said multiple condensers may be operating at a temperature or temperatures sufficient to condense the low molecular weight compounds produced from said pyrolysis of said dried BL, for example from about 50° C. to about 70° C., depending on the compounds to be recovered.

(48) In some embodiments, the fourth condenser—or the fourth set of condensers—of said multiple condensers may be operating at a temperature or temperatures sufficient to condense the aqueous phase and other compounds that are not condensed in the aforementioned three condenses and produced from said pyrolysis of said dried BL, for example at about 5° C., or higher, or lower, depending on the compounds to be recovered.

(49) According to some embodiments, said aqueous phase collected from said filtration of BL may be used to recover IC from said solid residue after said pyrolysis of said dried BL.

(50) According to some embodiments, said aqueous phase collected from said filtration of BL may be returned to the digester of the pulp and paper making processes to digest more wood, and/or for any other purposes.

(51) According to some embodiments, said aqueous phase collected from said filtration of BL may be pumped into a container for further uses.

(52) According to some embodiments, said steam produced from said drying of said filtered BL may be condensed after purging said media and used to recover IC from said solid residue after said pyrolysis of said dried BL.

(53) According to some embodiments, said steam produced from said drying of said filtered BL may be condensed after purging said media and returned to the digester of the pulp and paper making processes to digest more wood, and/or any other purposes.

(54) According to some embodiments, said steam produced from said drying of said filtered BL may be condensed after purging said media and pumped into a container for further uses.

(55) According to some embodiments, said mixture of chemical compounds recovered from said condensation system may be pumped into a container.

(56) According to some embodiments, said mixture of chemical compounds recovered from said condensation system may be sent to said media for further decomposition, separation, upgrading, and/or any other purposes.

(57) According to some embodiments, said individual chemicals or said individual chemical families recovered from said multiple condensers may be pumped into different containers based on their characteristics.

(58) According to some embodiments, said individual chemicals or said individual chemical families recovered from said multiple condensers may be sent to said media for further decomposition, separation, upgrading, and/or any other purposes.

(59) According to some embodiments, said heavy molecular weight compounds recovered from the first condenser—or the first set of condensers—may be pumped into a container.

(60) According to some embodiments, said heavy molecular weight compounds recovered from the first condenser—or the first set of condensers—may be sent to said media for further decomposition, separation, upgrading, and/or any other purposes.

(61) According to some embodiments, said medium molecular weight compounds recovered from the second condenser—or the second set of condensers—may be pumped into a container.

(62) According to some embodiments, said medium molecular weight compounds recovered from the second condenser—or the second set of condensers—may be sent to said media for further decomposition, separation, upgrading, and/or any other purposes.

(63) According to some embodiments, said low molecular weight compounds recovered from the third condenser—or the third set of condensers—may be pumped into a container.

(64) According to some embodiments, said low molecular weight compounds recovered from the third condenser—or the third set of condensers—may be sent to said media for further decomposition, separation, upgrading, and/or any other purposes.

(65) According to some embodiments, said low molecular weight compounds recovered from the fourth condenser—or the fourth set of condensers—may be pumped into a container.

(66) According to some embodiments, said low molecular weight compounds recovered from the fourth condenser—or the fourth set of condensers—may be sent to said media for further decomposition, separation, upgrading, and or any other purposes.

(67) According to some embodiments, said aqueous phase recovered from the fourth condenser—or the fourth set of condensers—may be pumped into a container.

(68) According to some embodiments, said aqueous phase recovered from the fourth condenser—or the fourth set of condensers—may be sent to said media for further decomposition, separation, upgrading, and or any other purposes.

(69) In some embodiments, said solid residue after said pyrolysis of said dried BL may furtherly be processed to separate said IC and said biocarbon using said aqueous phase collected from said filtration of BL and/or the condensed steam from said drying of said filtered BL4.

(70) In some embodiments, said solid residue after said pyrolysis of said dried BL may be burned at special conditions to recover said IC directly and its thermal value.

(71) In some embodiments, said IC dissolved in said aqueous phase may be sent to the digestion process for the aquatic and recovered IC recycling.

(72) In embodiments, the relatively weak dielectric properties of said IC compared to that of said dried BL makes said recovered IC from this disclosure may not thermally be affected during said drying of said filtered BL and said pyrolysis of said dried BL.

(73) In some embodiments, said biogas produced from said pyrolysis of said dried BL may be compressed in a vessel for further uses.

(74) In some embodiments, said biogas may be used to provide bio-energy for the site, which could furthermore be employed to generate electricity at almost net-zero carbon footprint.

(75) In embodiments, said media is any control volume in which said filtration of BL, said drying of said filtered BL, said pyrolysis of said dried BL, and/or any other reaction or process is carried out.

(76) In some embodiments, said media may be agitated under mixing conditions for minimizing the heat and mass transfer limitations, and for any other purposes.

(77) In some embodiments, said media may be centered relative to a vertical or horizontal axis, or combinations of thereof.

(78) In some embodiments, said media may be linearly moving, oscillating, or rotating relative to a fixed point or axis, or combinations of thereof.

(79) In some embodiments, said media may be centered relative to one or more directions or axis.

(80) In some embodiments, the temperature of the inner walls of said media may be increased to a value sufficient to avoid condensation and/or solidification of materials thereon.

(81) In some embodiments, the temperature of the inner walls of said media depends on the dew point of said chemicals produced from said pyrolysis of said dried BL, and/or any other aspects.

(82) In some embodiments, the temperature of the inner walls of said media may be increased to a value that does not negatively impact the yield and quality of the products produced from said pyrolysis of said dried BL and said recovered IC.

(83) In some embodiments, the temperature of the inner walls of said media may be increased to between about 100° C. to about 400° C.

(84) In some embodiments, the inner wall of said media may be heated using electric heaters, strong MW-receptor fixed thereon, directly or indirectly burning of said biogas produced from said pyrolysis of said dried BL, steam produced from said drying of said filtered BL, and/or combinations of thereof.

(85) In some embodiments, it has been found that varying the temperature of said pyrolysis of said dried BL will have a profound effect on the yield of said solid residue, said biogas, and said bio-oil. Now referring to FIG. 2, for example, it is demonstrated that said pyrolysis products may be dependent on said pyrolysis temperature from 500° C. to 800° C. FIG. 2 shows that increasing of pyrolysis temperature decreases the yield of said solid residue after said pyrolysis reaction. FIG. 2 shows that increasing of pyrolysis temperature increases the yield of said bio-oil after said pyrolysis reaction. FIG. 2 shows that increasing of pyrolysis temperature does not have significant impacts on the yield of said biogas produced from said pyrolysis reaction.

(86) In some embodiments, it has been found that varying of temperature of said pyrolysis of said dried BL will not have a profound effect on the yield of said recovered IC. Now referring to FIG. 3, for example, it is demonstrated that the yield of said recovered IC may be dependent on said pyrolysis temperature from 500° C. to 750° C. FIG. 3 shows that increasing of pyrolysis temperature from 750° C. to 800° C. does not noticeably impact the yield of said recovered IC.

(87) In some embodiments, the average yield (from 750° C. to 800° C.) obtained from the disclosed process is, for example, (1) said solid residue: 40 wt. %, which contains 55 wt. % said IC and 45 wt. % said biocarbon; (2) said bio-oil, 42 wt. %, which is mostly hydrocarbons, in particularly bio-aromatics; and (3) said biogas, 18 wt. %. The 55 wt. % of said solid residue—in other words, 22 wt. % of dried BL—is the typical percentage of IC used in the pulp and paper making processes. This result proves that the disclosed process able to recovers about 100% of said IC that are present in BL.

(88) In some embodiments, Table 2, for example, shows the identified chemical families in the condensed vapor produced from said pyrolysis of said dried BL.

(89) TABLE-US-00002 TABLE 2 Identified chemical families in the condensed vapor produced from said pyrolysis of said dried BL Concentration Identification [mg/g] Aromatics such as phenols, benzenes, 540 guaiacols, catechols, etc. Heavy molecular weight compounds 435 Others compounds 25 Total 1000

(90) In embodiments, said process supports efficient, direct, and long-lasting reductions in greenhouse gas emissions and local air pollutants resulting from the current process of recovering IC.

(91) In embodiments, said process provides a cost-effective and clean alternative methodology to those rely on burning BL in recovery boilers.

(92) In embodiments, said process would prevent the production of many millions of tonnes of sulfur oxide, nitrogen oxide, greenhouse gases, volatile organic compounds, carbon monoxide, fugitive dust emissions (e.g., soot and fly ash, metal fumes, and various aerosols), and other pollutants produced every year around the world from burning BL in recovery boilers.

(93) In embodiments, said process relies on the thermal decomposition of BL through the exposure to MW. The unique advantage of the MW heating mechanism, compared to the drawbacks of the superficial heat transfer of conventional heating, is that it produces the products of unparalleled quality and yield, such as bio-aromatics and biocarbon. Those products can be used in the production of plenty of multiple products including intermediates in the synthesis of pharmaceuticals, phenol formaldehyde resins, antioxidants, gasoline additives, polymerization initiators, pesticides, rubber reinforcing, block copolymers, composites, carbon fibers, and carbon sieves.

(94) In some embodiments, said bio-oil and said biocarbon, which have high-quality and are commercially viable materials, may be employed to replace petrochemicals and, thus, allow the forest industry to produce green, highly functional, and competitively priced end-products with significant novel properties.

(95) In some embodiments, production of said bio-oil and said biocarbon will diversify the commodities of the forestry industry and, in turn, enhances world bio-economy while decreasing our dependency on petrochemicals and negative environmental impact of oil extraction and petrochemical production.

(96) In some embodiments, applying of said MW in said pyrolysis of said dried BL can avert most of the problems associated with conventional heating pyrolysis, most importantly, char layer formation during conventional pyrolysis. This aspect can significantly enhance product selectivity because of reducing undesirable intermediate thermal steps.

(97) In some embodiments, said process employs MW for aquatic recycling, which will reduce water use in the pulp and paper manufacturing industry, one of the largest industrial water users in Canada.

(98) In some embodiments, the cost of recovering said IC would be decreased since said process does not consume any chemical additives compared to the precipitation of lignin.

(99) In some embodiments, said process does not have any issues to meet the requirements of growth pulp and paper production since the recovery boiler is not included in said process.

(100) In some embodiments, there may be no need to build a central conversion plant required for the precipitation of lignin because said process can easily be integrated into existing pulp and paper mills.