THERMOLYTIC FRAGMENTATION OF SUGARS

Abstract

A process for large scale and energy efficient production of oxygenates from sugar is disclosed in which a sugar feedstock is introduced into a thermolytic fragmentation reactor including a fluidized stream of heat carrying particles. The heat carrying particles may be separated from the fluidized stream prior to cooling the fragmentation product and may be directed to a reheater to reheat the particles and recirculate the heated particles to the fragmentation reactor.

Claims

1. A process for thermolytic fragmentation of a sugar into C.sub.1-C.sub.3 oxygenates, said process comprising the steps of: a. providing particles carrying heat and suitable for fluidization; b. providing a fluidized bed fragmentation reactor comprising a riser and suitable for conducting thermolytic fragmentation and suitable for fluidizing a stream of particles; c. providing a feedstock solution comprising a sugar; d. introducing the particles into the reactor at a rate sufficient to maintain a temperature of at least 250 C., such as at least 300 350, 400 or 450 C., after the thermolytic fragmentation has taken place, and sufficient to obtain a fluidized stream of particles; e. introducing the feedstock into the fluidized stream of particles to obtain thermolytic fragmentation of the sugar to produce a particle dense fragmentation product; then f. separating a fraction of the particles from the particle dense fragmentation product to produce a particle lean fragmentation product; g. quenching the particle lean fragmentation product at least 50 C. such that from introducing the feedstock into the particle containing fluidization stream to the quench is performed, the mean residence time of the gas is maximum 5, such as maximum 3 seconds, such as maximum 2, 1, 0.8 or 0.6 seconds; h. recovering the crude fragmentation product, i. transferring the particles separated in step f) to a reheater for heating; and j. recirculating the heated particles to the fragmentation reactor.

2. A system for fragmentation of a sugar composition into C.sub.1-C.sub.3 oxygenates comprising a fragmentation reactor, said reactor comprising within the reactor, a riser a first particle separator a fluidization stream inlet a particle inlet a feedstock inlet a particle outlet a product outlet, wherein the riser is arranged within and in the lower part of the fragmentation reactor; and the fluidization stream inlet and the particle inlet is arranged in the lower part of the riser; the feedstock inlet is arranged in the lower part of the riser above the particle inlet; the riser is adapted to fluidize particles in the riser; and the first particle separator is arranged in the upper part of the riser and is adapted to separate at least a part of the particles from a fluidization stream, and wherein the fragmentation reactor further comprises a cooling section arranged downstream the first particle separator in relation to the gas stream, said cooling section being adapted to cool the fluidization stream exiting the first particle separator and the system further comprises a reheater for reheating particles exiting the fragmentation reactor, the reheater comprises a fuel and combustion air inlet, a burner, a reheater particle inlet, a reheater riser, a reheater particle separator, a reheater gas outlet and a reheater particle outlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Embodiments of the present invention are explained, by way of examples and with reference to the accompanying drawings. It is to be noted that the appended drawings illustrate only examples of embodiments of this invention, and they are therefore not to be considered limiting of its scope, as the invention may admit to other alternative embodiments.

[0096] FIG. 1 shows a cross sectional side view of a fragmentation reactor according to an embodiment of the invention,

[0097] FIG. 2 shows a top view of the fragmentation reactor of the embodiment shown in FIG. 1,

[0098] FIG. 3 shows a cross sectional side view of a reheater according to an embodiment of the invention,

[0099] FIG. 4 shows a cross sectional side view of a system comprising a fragmentation reactor in fluid communication with a reheater according to an embodiment of the invention.

REFERENCE NUMBERS

[0100] 1. Fragmentation reactor [0101] 2. Fragmentation riser [0102] 3. First particle separator [0103] 4. Second particle separator [0104] 5. Cooling section [0105] 6. Fluidization inlet [0106] 7. Particle inlet [0107] 8. Feedstock inlet [0108] 9. Product outlet [0109] 10. Particle outlet [0110] 11. Reheater [0111] 12. Fuel and combustion air inlet [0112] 13. Burner chamber [0113] 14. Reheater particle inlet [0114] 15. Reheater riser [0115] 16. Reheater particle separator [0116] 17. Reheater particle outlet [0117] 18. Reheater gas outlet [0118] 19. Second reheater particle separator [0119] 20. Stripper [0120] 21. Reheater fluidization gas inlet [0121] 22. Secondary reheater fluidization and stripping gas inlet

DETAILED DESCRIPTION

[0122] As illustrated in FIG. 1 and FIG. 4, the fragmentation reactor of the invention is oblong in the vertical direction. Within the fragmentation reactor a riser 02 is provided, which is oblong with a small cross sectional area relative to the height. This facilitates the possibility of a low residence time of the particles inside the riser. In the lower section of the riser, a fluidization gas inlet 06 is provided which is adapted to provide a fluidization media to the riser and a particle inlet 07. The fluidization media helps to facilitate the movement of the particles from the particle inlet to the feedstock inlet towards the top of the riser. In addition, the fluidization stream can be used to pre-condition the particles before the particles are contacted with the feedstock. Above the particle and fluidization inlet, a feedstock inlet 08 enables the supply of feedstock to the riser. In the embodiment shown, the feedstock inlet is arranged in the lower section of the riser, but the position may vary according to the process demands.

[0123] When feedstock and particles have interacted in the riser, they are separated when exiting the riser in the first particle separator 03. According to an embodiment of the invention, the first particle separator is adapted to provide a fast separation of particles from the fragmentation product as such a fast separation is highly advantageous to the process. Hence, the particle separator can be of a low residence time type. In the embodiment of FIG. 2 and FIG. 3, the first particle separator comprises exit pipes which change the upwards direction of the exit flow from the riser app. by 180 into a downwards flow direction within the fragmentation reactor and outside the riser, which in the present context is referred to as a change of direction particle separator. In the embodiment of FIG. 4, the first particle separator comprises a gas particle separation forcing a tangential, relatively to the wall of item 1, exit of the riser gas and solid into the vessel of 1 and thereby performing the separation. A part of the particles settles at the bottom part of the fragmentation reactor after exiting the first particle separator. Accordingly, the described features of the riser, the position of feedstock inlet and the low residence time first particle separator provide the possibility of a very low contact time between particles and feedstock depending, of course, also on process parameters such as volume flows and specific dimensions, which all need to be adapted to the process demands.

[0124] A cooling section 05 is arranged within the fragmentation reactor above and adjacent the first particle separator. In the present embodiment, the cooling section comprises a quench, where a cooling media such as water or a recycled stream is injected, which rapidly and effectively cools the product by evaporation of the cooling media. Other embodiments such as quenching by introducing a particle stream or indirect heat exchangers may also be employed in the cooling section, whereby the total energy consumption of the fragmentation reactor system may be decreased. The rapid cooling of the product may be essential for the process, to keep a high yield, since the product may be sensitive to prolonged exposure to elevated temperatures.

[0125] After cooling the product, it is extracted from the fragmentation reactor via the product outlet 09. In the embodiment shown in FIG. 1 and FIG. 4, an optional further second particle separator 04 is provided in the fragmentation reactor to separate a further fraction of the particles from the product stream before it is extracted. In this section of the fragmentation reactor, the product is already cooled, and thus the residence time is less crucial. A second particle separator, such as for instance a cyclone, is provided, said second particle separator presenting a higher separation efficiency than the change of direction separator alone (item 03). The gas outlet of the cyclone is connected to the product outlet, whereas the particles from the particle outlet of the cyclone are carried to the bottom of the fragmentation reactor (01), where they are maintained fluidized by use of fluidization gas inlet (21). The distribution of fluidization gas over the cross section is ensured using, e.g., spargers. At the bottom of the fragmentation reactor, a particle outlet 10 enables the spent particles of the fragmentation reactor to be extracted and carried to e.g. reheating in another reactor.

[0126] FIG. 2 is a top view of the fragmentation reactor of the embodiment of FIG. 1 as described in the embodiment above. As illustrated, the riser is located in the horizontal cross sectional center of the fragmentation reactor. Furthermore, the plurality of exit pipes forming the first particle separator is shown, as well as the second particle separator which is located off center to the fragmentation reactor.

[0127] In FIG. 1 and FIG. 2, the secondary particle separator is placed inside the fragmentation reactor. The secondary particle separator may comprise one or several cyclones. In other embodiments, not shown these cyclones can also be placed outside the fragmentation reactor, e.g. above with diplegs extending through the fragmentation reactor roof or at the side of the fragmentation reactor with inclined diplegs or using e.g. a loop seal or L-valve. By placing the secondary cyclones outside the reactor vessel, the residence time of the oxygenate product in the fragmentation reactor may be decreased. The embodiment of FIG. 4 comprises external cyclones on the fragmentation reactor

[0128] In FIG. 3 and FIG. 4, a reheater 11 for reheating the particles exiting the fragmentation reactor is shown. The reheater particle inlet 14 is in fluid connection with the fragmentation reactor particle outlet 10, and the reheater particle outlet 17 is in fluid connection with the fragmentation reactor particle inlet 7. The reheater also comprises a riser type fluidized bed, a reheater riser 15, with a burner chamber 13 arranged in fluid connection to the lower part of the riser. A fuel and combustion air inlet 12 enables fuel and combustion air to be provided to the burner, which, when in operation provides heat to the reheater riser. The reheater particle inlet is arranged in the lower part of the reheater riser and enables the particles exiting the fragmentation reactor to enter the reheater riser where they are fluidized in an upwards flow by the hot gas provided by the burner while being heated. The connection between the burner and the reheater particle inlet is deliberately designed to reduce/prevent fall through of particles from the riser and into the combustion chamber. This design could take many different embodiments. In FIG. 3 and FIG. 4, this is illustrated by the constriction between 13 and 15 leading to an increased gas velocity preventing/reducing a fall through of particles. After reheating, the particles are separated from the combustion gas and are led back to the fragmentation reactor. In the embodiment of FIG. 3, the reheater particle separator 16 is a cyclone which enables gas to exit the reheater via the reheater gas outlet 18 while the separated particles exits the reheater via the reheater particle outlet connected to the particle outlet of the cyclone of the reheater. It is to be understood that the extent of separation in the particle separators depends on various process parameters, such as pressure loss in the separator, flow velocities, particle size etc. as known in the art.

[0129] In the embodiment of FIG. 4, the first particle separator is similar to the item 03 of the fragmentation reactor. Embodiment 4 is also equipped with a secondary cyclone type particle separator (19). Both particle separators deliver particles to the bottom of item 11. In the lowermost position of item 11 a section (20) for stripping excess O2 from the fluidized particles are placed. Secondary fluidization and stripping gas inlets (22) for item 11 and 20 of the embodiment of FIG. 4 are distributed over the cross section using, e.g., spargers or other methods. Additional fluidization gas inlets may be present in item 11 on FIG. 4, but not shown. A stripping of product gas just before or after position (10) in FIG. 4 is also envisaged.

EXAMPLE

Example 1: Production of a Glycolaldehyde Rich C.SUB.1.-C.SUB.3 .Oxygenate Mixture by Thermolytic Fragmentation of a Sugar Solution

[0130] The fragmentation of an aqueous solution of glucose was demonstrated in a riser type reactor unit. The particle inlet was placed upstream the feed inlet. The superficial gas velocity in the riser was approximately 6 m/s. The riser reactor length was 6.2 m with and inner diameter of 41 mm. Two cyclones followed the riser and the separated solids were admitted to an external reactor for reheating. The residence time of the fragmentation product was approximately 1 second from feed inlet to first particle separator.

[0131] To collect the gaseous product, part of the gas stream exiting the second cyclone was directed to a condensation system. The liquid product was rapidly condensed by indirect cooling at 1 C. and separated from the permanent gases. The flow of permanent gases was measured using a variable area flowmeter.

[0132] The concentration of oxygenates in the liquid product was determined by HPLC analysis, and the yields calculated assuming that 8% of the mass of the feed was lost with the permanent gases due to incomplete condensation of water, i.e. using a mass balance of 92%. This is considered a conservative, but reasonable, assumption based on previous experience.

[0133] With this conservative assumption, about 60% of the carbon fed to the reactor was recovered as glycolaldehyde by thermolytic fragmentation of a 45 wt. % solution of glucose at approx. 500 C. Sodium silicate glass beads were used as bed material.

EMBODIMENTS

Embodiment 1

[0134] A process for thermolytic fragmentation of a sugar into C.sub.1-C.sub.3 oxygenates, said process comprising the steps of: [0135] a. providing particles carrying heat and suitable for fluidization; [0136] b. providing a fluidized bed fragmentation reactor comprising a riser and suitable for conducting thermolytic fragmentation and suitable for fluidizing a stream of particles; [0137] c. providing a feedstock solution comprising a sugar; [0138] d. introducing the particles into the reactor at a rate sufficient to maintain a temperature of at least 250 C., such as at least 300 350, 400 or 450 C., after the thermolytic fragmentation has taken place, and sufficient to obtain a fluidized stream of particles; [0139] e. introducing the feedstock into the fluidized stream of particles to obtain thermolytic fragmentation of the sugar to produce a particle dense fragmentation product; then [0140] f. separating a fraction of the particles from the particle dense fragmentation product to produce a particle lean fragmentation product; [0141] g. quenching the particle lean fragmentation product at least 50 C. such that from introducing the feedstock into the particle containing fluidization stream to the quench is performed, the mean residence time of the gas is maximum 5, such as maximum 3 seconds, such as maximum 2, 1, 0.8 or 0.6 seconds; [0142] h. recovering the crude fragmentation product, [0143] i. transferring the particles separated in step f) to a reheater for heating; and [0144] j. recirculating the heated particles to the fragmentation reactor.

Embodiment 2

[0145] The process according to embodiment 1, wherein the particle lean fragmentation product is subjected to a second particle separation step after step g) of quenching the particle lean fragmentation product and before step h) of recovering the crude fragmentation product.

Embodiment 3

[0146] The process according to any one of embodiments 1 or 2, wherein the reactor in the lower part comprises a particle inlet and a feedstock inlet, wherein the feedstock inlet is provided downstream the particle inlet.

Embodiment 4

[0147] The process according to embodiment 3, wherein the reactor in the lower part further comprises a fluidization stream inlet, and the fluidization inlet is provided upstream the particle inlet.

Embodiment 5

[0148] The process according to any one of embodiments 3 or 4, wherein the particles form a dense phase fluidized bed in the zone between the particle inlet and the feedstock inlet.

Embodiment 6

[0149] The process according to any one of embodiments 3-5, wherein the feedstock inlet is provided in the lower part of the riser.

Embodiment 7

[0150] The process according to any one of embodiments 1-5, wherein the reactor comprises a first particle separator downstream of the riser.

Embodiment 8

[0151] The process according to embodiment 7, wherein the reactor comprises a quench downstream the first particle separator.

Embodiment 9

[0152] The process according to embodiment 8, wherein the reactor comprises a second particle separator downstream the quench.

Embodiment 10

[0153] The process according to any one of embodiments 1-9, wherein the reactor does not comprise other means for heating than the heat carrying particles.

Embodiment 11

[0154] The process according to any one of embodiments 1-10, wherein the sugar is a mono- and/or di-saccharide.

Embodiment 12

[0155] The process according to any one of embodiments 1-11, wherein the feedstock solution comprises an aqueous solution of a sugar selected from the group consisting of sucrose, lactose, xylose, arabinose, ribose, mannose, tagatose, galactose, glucose and fructose; or mixtures thereof.

Embodiment 13

[0156] The process according to any one of embodiments 1-12, wherein the concentration of sugar in the feedstock solution is between 10 and 90% by weight.

Embodiment 14

[0157] The process according to any one of embodiments 1-13 wherein the temperature of the particles at the particle inlet of the fragmentation reactor is preferably at least 300 C., such as at least 400, 450, 500, 550, 600 or 650 C.

Embodiment 15

[0158] The process according to any one of embodiments 1-14 wherein the temperature of the particles at the particle inlet is within the range of from 300-800 C., such as in the range of from 400-800 or 450-650 C.

Embodiment 16

[0159] The process according to any one of embodiments 1-15 wherein the particles are selected from the group consisting of sand, silica, glass, alumina, steel, and silicon carbide.

Embodiment 17

[0160] The process according to any one of embodiments 1-16, wherein the mean particle size of the heat carrying particles is from 20-400 m, such as from 20-300, 20-200 or 20-100 m.

Embodiment 18

[0161] The process according to any one of embodiments 1-17, wherein the particles of step a) are introduced into the fragmentation reactor at a mass flow rate of at least 10 kg/s.

Embodiment 19

[0162] The process according to any one of embodiments 1-18, wherein the velocity inside the fragmentation riser above the feedstock inlet is above 2 m/s, such as from 3-22, or from 5-20 m/s.

Embodiment 20

[0163] The process according to any one of embodiments 1-19, wherein the reheater comprises a fuel and combustion air inlet, a burner, a reheater particle inlet, a reheater riser, a reheater particle separator, a reheater gas outlet for flue gas and a reheater particle outlet.

Embodiment 21

[0164] The process according to any one of embodiments 1 to 20, wherein the temperature of the particles exiting the reheater particle outlet is in the range of from 300-800 C., such as in the range of from 400-800, 400-700 or 500-700 C.

Embodiment 22

[0165] The process according to any one of embodiments 20 or 21, wherein the burner is arranged within a burner chamber, which is separate from the reheater riser, and combustion gas from the burner chamber is led to the reheater riser.

Embodiment 23

[0166] The process according to any one of embodiments 20-22, wherein a part of the flue gas from the reheater after particulate removal is recirculated to the burner chamber.

Embodiment 24

[0167] The process according to any one of embodiments 1-23, wherein excess oxygen is stripped from the particles before they are transferred from the reheater to the fragmentation reactor.

Embodiment 25

[0168] A process for the preparation of a C.sub.1-C.sub.3 hydroxy compound from a sugar comprising the steps of:

carrying out a process according to any one of embodiments 1-24;
and then
subjecting the crude fragmentation product to a hydrogenation to obtain the corresponding C.sub.1-C.sub.3 hydroxy compound.

Embodiment 26

[0169] A system for fragmentation of a sugar composition into C.sub.1-C.sub.3 oxygenates comprising a fragmentation reactor, said reactor comprising within the reactor, [0170] a riser [0171] a first particle separator [0172] a fluidization stream inlet [0173] a particle inlet [0174] a feedstock inlet [0175] a particle outlet [0176] a product outlet, [0177] wherein the riser is arranged within and in the lower part of the fragmentation reactor; and the fluidization stream inlet and the particle inlet is arranged in the lower part of the riser; the feedstock inlet is arranged in the lower part of the riser; above the particle inlet the riser is adapted to fluidize particles in the riser; and the first particle separator is arranged in the upper part of the riser and is adapted to separate at least a part of the particles from a fluidization stream, and wherein the fragmentation reactor further comprises a cooling section arranged downstream the first particle separator in relation to the gas stream, said cooling section being adapted to cool the fluidization stream exiting the first particle separator and the system further comprises a reheater for reheating particles exiting the fragmentation reactor, the reheater comprises a fuel and combustion air inlet, a burner, a reheater particle inlet, a reheater riser, a reheater particle separator, a reheater gas outlet and a reheater particle outlet.

Embodiment 27

[0178] The system according to embodiment 26, wherein the fragmentation reactor further comprises a second particle separator within the fragmentation reactor, said second particle separator being arranged in the upper part of the fragmentation reactor and being adapted to separate a further part of the particles from the fluidization stream.

Embodiment 28

[0179] The system according to any one of embodiments 26 or 27, wherein the cooling section is adapted to quench by injecting a liquid into the fragmentation reactor.

Embodiment 29

[0180] The system according to any one of embodiments 26 or 27, wherein the cooling section is adapted to quench by admitting a colder particle stream into the fragmentation reactor.

Embodiment 30

[0181] The system according to any one of embodiments 26 or 27, wherein the cooling section comprises an indirect heat exchanger.

Embodiment 31

[0182] The system according to any of embodiments 26-30, wherein the first particle separator is a low volume separator.

Embodiment 32

[0183] The system according to any of embodiments 26-31, wherein the first particle separator comprises at least one change of direction separator.

Embodiment 33

[0184] The system according to any of embodiments 26-32, wherein the first particle separator comprises at least one tube arranged with a first end at the upper part of and in fluid connection with the riser, and where the second end of the tube is pointing downwards and in fluid connection with the fragmentation reactor and outside the riser.

Embodiment 34

[0185] The system according to any of embodiments 27-33, wherein the second particle separator is at least one cyclone.

Embodiment 35

[0186] The system according to any of embodiments 26 to 34, wherein the burner and the reheater fuel and combustion air inlet is arranged upstream the reheater riser, and the reheater particle inlet is arranged in the lower part of the reheater riser downstream the burner, and the reheater particle inlet is in fluid connection with the fragmentation reactor particle outlet, the reheater riser being adapted to reheat the particles exiting the fragmentation reactor by means of combustion gas from the burner.

Embodiment 36

[0187] The system according to any of embodiments 26 to 35, wherein the reheater particle separator is arranged downstream the reheater riser, and the reheater particle outlet is in fluid connection with the fragmentation reactor particle inlet.

Embodiment 37

[0188] The system according to any of embodiments 26 to 36, wherein the burner is arranged in a separate burner chamber.

Embodiment 38

[0189] The system according to embodiment 37, wherein the burner chamber is separated from the riser by a constriction.

Embodiment 39

[0190] The system according to any of embodiments 26 to 38, wherein a stripping chamber is arranged downstream the reheater particle separator and upstream the fragmentation reactor particle inlet.