System for stably producing xylose liquid by using hemicellulose alkali liquid

Abstract

The invention discloses a system for stably producing xylose liquid by utilizing hemicellulose alkali liquid. The system comprises an acid adjusting subsystem, a salt filtering subsystem, a hydrolysis subsystem and a flash evaporation subsystem, the acid adjusting subsystem comprises a primary acid adjusting unit and a secondary acid adjusting unit, the hydrolysis subsystem comprises an ejector and a hydrolysis reaction kettle, the flash evaporation subsystem comprises a transfer tank, a flash evaporation tank and a plate heat exchanger, and the salt filtering subsystem comprises ceramic membrane filtering equipment. A secondary acid regulation mode is adopted, the heating link of the plate heat exchanger is placed between primary acid regulation and secondary acid regulation, the service life of the heat exchanger is prolonged, a certain temperature can be ensured by carrying out secondary acid regulation after heating, and the subsequent process is not affected; before hydrolysis, the ceramic membrane filtering equipment is used for filtering salt components in the hemicellulose alkali liquor raw material, so that the aim of concentrating the materials is fulfilled, and the hydrolysis effect is improved by a mode of reducing the salt components and concentrating the materials.

Description

Technical Field

[0001] The invention relates to the field of xylose liquid production, in particular to a system for stably producing xylose liquid by utilizing hemicellulose alkali liquid. Background Art

[0002] In the production process of viscose fiber using chemical pulp (wood pulp, cotton pulp, straw pulp, reed pulp and other plant cellulose) as raw materials, alkali treatment is a key step, which helps to convert cellulose into viscose suitable for spinning. However, the hemicellulose alkali produced in this process often only recovers the alkali, while the remaining hemicellulose liquid is not fully utilized, which indeed causes a waste of resources.

[0003] The prior art (Chinese invention patent with publication number CN109355443A) discloses a system and method for preparing xylose solution by continuous hydrolysis of hemicellulose, that is, making full use of the remaining hemicellulose solution to produce xylose solution. The system includes a neutralization unit, an acid adjustment unit, a feeding unit, a liquefaction injection unit, an inlet and outlet heat exchange unit, and a discharge control unit. The neutralization unit includes a raw material tank, a neutralization concentrated sulfuric acid pump, and a neutralization pipeline mixer. The acid adjustment unit includes an acid adjustment concentrated sulfuric acid pump, an acid adjustment pipeline mixer, and an acid adjustment tank. The feeding unit includes a feeding tank. The liquefaction injection unit includes a liquefaction injector and a liquefaction maintainer. The inlet and outlet heat exchange unit includes an inlet and outlet plate heat exchanger and a first discharge temperature sensor. The discharge control unit includes a discharge valve and a reflux valve. The raw material tank is used to store hemicellulose alkali solution. The neutralization pipeline mixer is used to neutralize the hemicellulose alkali solution with the concentrated sulfuric acid from the neutralization concentrated sulfuric acid pump to obtain a hemicellulose liquid raw material. The acid adjustment pipeline mixer The combiner is used to mix the hemicellulose liquid raw material with the concentrated sulfuric acid from the acid-adjusting concentrated sulfuric acid pump to obtain the hemicellulose liquid, the acid-adjusting tank collects the mixed hemicellulose liquid, the feed tank receives the hemicellulose liquid overflowing from the acid-adjusting tank, the inlet and outlet plate heat exchanger is used to exchange heat between the hemicellulose liquid feed after acid adjustment and the xylose liquid obtained by hydrolysis, the liquefaction injector is used to fully mix the hemicellulose liquid after heat exchange with the external high-pressure steam and inject them together into the liquefaction maintainer, the liquefaction maintainer is used to hydrolyze the hemicellulose liquid and water vapor at high temperature to obtain xylose liquid, the first discharge temperature sensor is used to sense the temperature of the xylose liquid obtained by hydrolysis, and the first discharge temperature sensor is interlocked with the discharge valve and the reflux valve to control the flow direction of the xylose liquid obtained by hydrolysis.

[0004] However, this prior art has the following problems:

[0005] (1) The acid adjustment unit of the prior art is a one-time acid adjustment method. The acidity of the hemicellulose liquid after acid adjustment meets the set requirements: 1% to 4%; then the hemicellulose liquid after acid adjustment enters the heat exchanger for heat exchange and hydrolysis. However, not only does the one-time acid adjustment method make the acid adjustment stability poor, but the hemicellulose liquid with an acidity of 1% to 4% is directly heated by the plate heat exchanger. The plate heat exchanger usually uses Hastelloy alloy. Although it has a certain degree of corrosion resistance, it is still easily damaged when facing the hemicellulose liquid with an acidity of 1% to 4%.

[0006] (2) The prior art directly performs steps such as neutralization, acid adjustment, heat exchange, and hydrolysis on the alkali liquor raw material. However, some salt components in the alkali liquor raw material will affect the hydrolysis step.

[0007] (3) The prior art directly uses a plate heat exchanger to heat and cool the hydrolyzed xylose solution. The acidity of the hydrolyzed xylose solution is still around 2%, which not only corrodes the plate heat exchanger to a certain extent, but also causes a certain clogging effect, affecting the operation of the overall system. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a system for stably producing xylose solution by utilizing hemicellulose alkali solution.

[0009] The objective of the present invention is achieved through the following technical solutions:

[0010] In a first aspect of the present invention, a system for stabilizing xylose liquor production by using hemicellulose alkali liquor is provided, comprising an acid adjustment subsystem, a salt filtration subsystem, a hydrolysis subsystem and a flash evaporation subsystem;

[0011] The acid conditioning subsystem includes a primary acid conditioning unit and a secondary acid conditioning unit, the hydrolysis subsystem includes an ejector and a hydrolysis reactor, the flash evaporation subsystem includes a transfer tank, a flash evaporation tank and a plate heat exchanger, and the salt filtration subsystem includes a ceramic membrane filtration device;

[0012] The primary acid adjustment unit performs primary acid adjustment on the hemicellulose alkali liquor to obtain a first acid adjustment liquid with a pH value of 4-6. The first acid adjustment liquid enters the secondary acid adjustment unit for secondary acid adjustment after being filtered by a ceramic membrane filter device and heated by a plate heat exchanger to obtain a second acid adjustment liquid with an acid concentration of 1% to 3%. The ejector injects the second acid adjustment liquid into a hydrolysis reactor for hydrolysis reaction to obtain a hydrolyzed liquid which enters a transfer tank. The flash tank flashes the hydrolyzed liquid in the transfer tank, collects the xylose liquid obtained by the flash evaporation, and the steam obtained by the flash evaporation enters the plate heat exchanger as a heating heat source.

[0013] Furthermore, the primary acid adjustment unit includes a first concentrated sulfuric acid tank, a first concentrated sulfuric acid metering pump, a first acid adjustment mixer, a first acid adjustment tank, a first acid adjustment discharge pump and a pH sensor; the first concentrated sulfuric acid tank is connected to the first acid adjustment feed end of the first acid adjustment mixer through the first concentrated sulfuric acid metering pump, and the second acid adjustment feed end of the first acid adjustment mixer is connected to the hemicellulose alkali solution; the first acid adjustment mixer mixes the hemicellulose alkali solution and the concentrated sulfuric acid, and detects the pH value in the first acid adjustment mixer in real time through the pH sensor, and after mixing, the first acid adjustment liquid enters the first acid adjustment tank to be stored; the first acid adjustment discharge pump transports the first acid adjustment liquid in the first acid adjustment tank.

[0014] Furthermore, the secondary acid adjustment unit includes a second concentrated sulfuric acid tank, a second concentrated sulfuric acid metering pump, a second acid adjustment mixer, and a second acid adjustment discharge pump for the second acid adjustment tank; the second concentrated sulfuric acid tank is connected to the first acid adjustment feed end of the second acid adjustment mixer through the second concentrated sulfuric acid metering pump, and the second acid adjustment feed end of the second acid adjustment mixer is connected to the filtered first acid adjustment liquid; the second acid adjustment mixer mixes the filtered first acid adjustment liquid and concentrated sulfuric acid, and the mixed acid enters the second acid adjustment tank to store the second acid adjustment liquid; the second acid adjustment discharge pump transports the second acid adjustment liquid in the second acid adjustment tank.

[0015] Furthermore, the hydrolysis reactor conveys the hydrolyzate to the transfer tank via the reactor discharge pump, the transfer tank conveys the hydrolyzate to the flash tank via the flash transfer pump, and the flash tank conveys the xylose solution obtained by flash evaporation via the flash discharge pump.

[0016] Furthermore, the heating material feed end of the plate heat exchanger is connected to the discharge end of the ceramic membrane filtration equipment, and the heating material discharge end of the plate heat exchanger is connected to the feed end of the secondary acid adjustment unit; the heat source air inlet end of the plate heat exchanger is connected to the steam air outlet end of the flash tank, and the heat source air outlet end of the plate heat exchanger is connected to the gas-water separator; the gas-water separator separates gas and water and collects them.

[0017] Furthermore, the material pipeline and steam pipeline of the plate heat exchanger are made of Hastelloy.

[0018] Further, the plate heat exchangers include three, namely, a first plate heat exchanger, a second plate heat exchanger and a third plate heat exchanger, and the flash tanks include three, namely, a first flash tank, a second flash tank and a third flash tank;

[0019] The heating material feed end of the first plate heat exchanger is connected to the discharge end of the ceramic membrane filtration device, the heating material discharge end of the first plate heat exchanger is connected to the heating material feed end of the second plate heat exchanger, and the heating material discharge end of the second plate heat exchanger is connected to the feed end of the secondary acid adjustment unit; the heating material feed end of the third plate heat exchanger is connected to external materials;

[0020] The feed end of the first flash tank is connected to the discharge end in the transfer tank, the discharge end of the first flash tank is connected to the feed end of the second flash tank, the discharge end of the second flash tank is connected to the feed end of the third flash tank, and the discharge end of the third flash tank transports the xylose solution obtained by flash evaporation; the steam outlet end of the first flash tank is connected to the heat source inlet end of the second plate heat exchanger, the steam outlet end of the second flash tank is connected to the heat source inlet end of the first plate heat exchanger, and the steam outlet end of the third flash tank is connected to the heat source inlet end of the third plate heat exchanger;

[0021] The temperature and pressure of the first flash tank, the second flash tank and the third flash tank are gradually reduced.

[0022] Furthermore, the temperature of the first flash tank is 90-100°C and the pressure is -7kPa; the temperature of the second flash tank is 85-90°C and the pressure is -30kPa; the temperature of the third flash tank is 80-850°C and the pressure is -50kPa.

[0023] Furthermore, a reactor agitator is provided in the hydrolysis reactor, and the reactor agitator operates according to the hydrolysis time interval.

[0024] Furthermore, the hydrolysis reactor is provided with a compressed air pipe, which is used to release pressure during the feeding process and to replenish pressure during the discharging process, thereby ensuring the pressure in the reactor.

[0025] The beneficial effects of the present invention are:

[0026] In an exemplary embodiment of the present invention, a secondary acid adjustment method is adopted to make the acid adjustment more stable; and the heating link of the plate heat exchanger is placed between the primary acid adjustment and the secondary acid adjustment to improve the life of the heat exchanger, and the secondary acid adjustment after heating can also ensure a certain temperature, so that the subsequent processes are not affected.

[0027] Before hydrolysis, the ceramic membrane filtration equipment is used to filter the salt components in the hemicellulose alkali liquid raw material, and the purpose of material concentration is achieved by the way of reducing the salt components + material concentration, thereby improving the hydrolysis effect. At the same time, the ceramic membrane filtration equipment filters the salt components of the first acid adjustment liquid after the first acid adjustment, which can achieve the effect of twice acid adjustment stability and also achieve the purpose of not damaging the ceramic membrane filtration equipment.

[0028] Using a flash tank to cool the hydrolyzed liquid (i.e., xylose liquid) after hydrolysis and using the steam from the flash tank to supply heat to the plate heat exchanger not only reduces the degree of damage to the plate heat exchanger but also avoids the clogging effect that may be caused by the finished xylose liquid passing through the plate heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A schematic diagram of the structure of a system for stably producing xylose solution by using hemicellulose alkali solution provided in an exemplary embodiment of the present invention;

[0030] Figure 2 It is a structural schematic diagram of a primary acid conditioning unit provided in an exemplary embodiment of the present invention;

[0031] Figure 3 It is a structural schematic diagram of a secondary acid adjustment unit provided in an exemplary embodiment of the present invention;

[0032] Figure 4 A schematic diagram of the structure of a hydrolysis subsystem provided in an exemplary embodiment of the present invention;

[0033] Figure 5 A schematic diagram of multi-stage heat exchange provided in an exemplary embodiment of the present invention;

[0034] In the figure, 101-primary acid adjustment unit, 10101-first concentrated sulfuric acid tank, 10102-first concentrated sulfuric acid metering pump, 10103-first acid adjustment mixer, 10104-first acid adjustment tank, 10105-first acid adjustment discharge pump, 102-secondary acid adjustment unit, 10201-second concentrated sulfuric acid tank, 10202-second concentrated sulfuric acid metering pump, 10203-second acid adjustment mixer, 10204-second acid adjustment tank, 1020401-second acid adjustment tank front tank, 1020402-second acid adjustment tank rear tank, 1020403-circulation pump, 10205-second acid adjustment discharge pump, 201-spray Ejector, 202-hydrolysis reactor, 20201-reactor discharge pump, 301-transfer tank, 30101-flash transfer pump, 302-flash tank, 30201-first flash tank, 30202-second flash tank, 30203-third flash tank, 30204-flash discharge pump, 303-plate heat exchanger, 30301-first plate heat exchanger, 30302-second plate heat exchanger, 30303-third plate heat exchanger, 304-gas-water separator, 30401-condensate pump, 30402-gas vacuum pump, 30403-pneumatic regulating valve, 401-ceramic membrane filtration equipment. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] See also Figure 1 , Figure 1 A system for stably producing xylose liquor by using hemicellulose alkali liquor provided in an exemplary embodiment of the present invention is shown, comprising an acid adjustment subsystem, a salt filtration subsystem, a hydrolysis subsystem and a flash evaporation subsystem;

[0040] The acid conditioning subsystem includes a primary acid conditioning unit 101 and a secondary acid conditioning unit 102, the hydrolysis subsystem includes an ejector 201 and a hydrolysis reactor 202, the flash evaporation subsystem includes a transfer tank 301, a flash evaporation tank 302 and a plate heat exchanger 303, and the salt filtration subsystem includes a ceramic membrane filtration device 401;

[0041] The primary acid adjustment unit 101 performs primary acid adjustment on the hemicellulose alkali liquor to obtain a first acid adjustment liquid with a pH value of 4-6. The first acid adjustment liquid enters the secondary acid adjustment unit 102 for secondary acid adjustment after being filtered by the ceramic membrane filtration device 401 and heated by the plate heat exchanger 303 to obtain a second acid adjustment liquid with an acid concentration of 1% to 3%; the ejector 201 injects the second acid adjustment liquid into the hydrolysis reactor 202 for hydrolysis reaction to obtain a hydrolyzed liquid and enters the transfer tank 301; the flash tank 302 flashes the hydrolyzed liquid in the transfer tank 301, collects the xylose liquid obtained by the flash evaporation, and the steam obtained by the flash evaporation enters the plate heat exchanger 303 as a heating heat source.

[0042] Specifically, in this exemplary embodiment, the hemicellulose alkali liquor is firstly acidified by the primary acidification unit 101 to obtain a first acidification liquid with a pH value of 4-6. The first acidification liquid passes through the ceramic membrane filtration device 401 to filter out part of the salt components in the liquid, and then is heated by the plate heat exchanger 303. Then, it enters the secondary acidification unit 102 for secondary acidification to obtain a second acidification liquid with an acid concentration of 1% to 3%. Next, the second acidification liquid is sprayed into the hydrolysis reactor 202 by the ejector 201 for hydrolysis reaction, and the obtained hydrolyzed liquid enters the transfer tank 301 for storage; finally, the hydrolyzed liquid in the transfer tank 301 is flash evaporated by the flash tank 302, and the obtained liquid is the final product xylose liquid, and the gas with a certain temperature obtained by the flash evaporation enters the plate heat exchanger 303 as a heat source to heat the raw material.

[0043] Among them, acid adjustment is to add acid to the material, which is used to adjust the alkaline raw materials to acidic so that the hydrolysis reaction can proceed; heat exchange is used to heat, so that less steam is used in the subsequent hydrolysis process; and the role of hydrolysis is to convert hemicellulose into xylose, and the role of flash evaporation is to evaporate the water in the material to adjust the product concentration and reduce the temperature. The role of the ejector is to eject the material after the secondary acid adjustment for heating.

[0044] Compared with the prior art, this exemplary embodiment has the following advantages:

[0045] (1) Compared with the prior art, the acid adjustment unit is a single acid adjustment method. However, not only does the single acid adjustment method make the acid adjustment stability poor, but the hemicellulose liquid with an acidity of 1% to 4% is directly heated by the plate heat exchanger 303. The plate heat exchanger 303 is usually made of Hastelloy. Although it has a certain corrosion resistance, it is still easily damaged by the hemicellulose liquid with an acidity of 1% to 4%. In this exemplary embodiment, a secondary acid adjustment method is adopted to make the acid adjustment stability better; and the heating link of the plate heat exchanger 303 is placed between the primary acid adjustment and the secondary acid adjustment. The pH value of the first acid adjustment liquid of the primary acid adjustment is 4-6, which has little effect on the Hastelloy, thereby improving the life of the heat exchanger. After heating, the secondary acid adjustment can also ensure a certain temperature, so that the subsequent process is not affected.

[0046] (2) Compared with the prior art which directly processes the hemicellulose alkali liquor raw material by neutralization, acid adjustment, heat exchange, hydrolysis, etc., this exemplary embodiment uses a ceramic membrane filtration device 401 to filter the salt component in the hemicellulose alkali liquor raw material before hydrolysis, thereby achieving the purpose of material concentration, thereby improving the hydrolysis effect by reducing the salt component + material concentration.

[0047] At the same time, if the ceramic membrane filtration device 401 is directly used to filter the hemicellulose alkaline liquid raw material, the alkaline material will damage the membrane equipment; therefore, in this exemplary embodiment, the ceramic membrane filtration device 401 filters the salt component of the first acid adjustment liquid after the first acid adjustment, which can achieve the effect of twice acid adjustment stability and achieve the purpose of not damaging the ceramic membrane filtration device 401.

[0048] (3) Compared with the prior art that directly uses the plate heat exchanger 303 to heat and cool the hydrolyzed xylose liquid, the acidity of the hydrolyzed xylose liquid is still around 2%, which will not only cause a certain corrosion effect on the plate heat exchanger 303, but also cause a certain clogging effect, affecting the operation of the entire system. In this exemplary embodiment, the flash tank 302 is used to cool the hydrolyzed liquid (i.e., xylose liquid) after hydrolysis, and the steam of the flash tank 302 is used to supply the heat source to the plate heat exchanger 303, which not only reduces the degree of damage to the plate heat exchanger 303, but also avoids the clogging effect that may be caused by the finished xylose liquid passing through the plate heat exchanger 303.

[0049] The following content will describe the preferred exemplary embodiments of each structure:

[0050] More preferably, in an exemplary embodiment, if Figure 2 As shown, the primary acid adjustment unit 101 includes a first concentrated sulfuric acid tank 10101, a first concentrated sulfuric acid metering pump 10102, a first acid adjustment mixer 10103, a first acid adjustment tank 10104, a first acid adjustment discharge pump 10105 and a pH sensor; the first concentrated sulfuric acid tank 10101 is connected to the first acid adjustment feed end of the first acid adjustment mixer 10103 through the first concentrated sulfuric acid metering pump 10102, and the second acid adjustment feed end of the first acid adjustment mixer 10103 is connected to the hemicellulose alkali solution; the first acid adjustment mixer 10103 mixes the hemicellulose alkali solution and the concentrated sulfuric acid, and detects the pH value in the first acid adjustment mixer 10103 in real time through the pH sensor, and after mixing, the first acid adjustment liquid enters the first acid adjustment tank 10104 to store the first acid adjustment liquid; the first acid adjustment discharge pump 10105 transports the first acid adjustment liquid in the first acid adjustment tank 10104.

[0051] Specifically, in this exemplary embodiment, the concentrated sulfuric acid in the first concentrated sulfuric acid tank 10101 passes through the first concentrated sulfuric acid metering pump 10102, and is automatically mixed with the hemicellulose alkali solution raw material according to a certain flow ratio by automatic control to complete the first acid adjustment, wherein the first acid adjustment mixer 10103 is used for mixing, and the first acid adjustment tank 10104 is used for storage (and an agitator can be added in the first acid adjustment tank 10104 to make the acid adjustment more uniform), and after mixing, it is transported by the first acid adjustment discharge pump 10105 (system automatic control, constant flow). Among them, the pH sensor detects the pH value in the first acid adjustment mixer 10103 in real time, so that the pH value reaches 4-6.

[0052] More preferably, in an exemplary embodiment, if Figure 3 As shown, the secondary acid adjustment unit 102 includes a second concentrated sulfuric acid tank 10201, a second concentrated sulfuric acid metering pump 10202, a second acid adjustment mixer 10203, and a second acid adjustment discharge pump 10205 of the second acid adjustment tank 10204; the second concentrated sulfuric acid tank 10201 is connected to the first acid adjustment feed end of the second acid adjustment mixer 10203 through the second concentrated sulfuric acid metering pump 10202, and the second acid adjustment feed end of the second acid adjustment mixer 10203 is connected to the filtered first acid adjustment liquid; the second acid adjustment mixer 10203 mixes the filtered first acid adjustment liquid and concentrated sulfuric acid, and the mixed acid enters the second acid adjustment tank 10204 to store the second acid adjustment liquid; the second acid adjustment discharge pump 10205 transports the second acid adjustment liquid in the second acid adjustment tank 10204.

[0053] Specifically, in this exemplary embodiment, the concentrated sulfuric acid in the second concentrated sulfuric acid tank 10201 passes through the second concentrated sulfuric acid metering pump 10202, and is automatically mixed with the hemicellulose alkali solution raw material in a certain flow ratio by automatic control to complete the second acid adjustment, wherein the second acid adjustment mixer 10203 is used for mixing, and the second acid adjustment tank 10204 is used for storage (and an agitator can be added in the second acid adjustment tank 10204 to make the primary acid adjustment more uniform), and after mixing, it is transported by the second acid adjustment discharge pump 10205 (system automatic control, constant flow).

[0054] In addition, it should be noted that the second acid adjustment tank 10204 can be divided into a second acid adjustment tank front tank 1020401 and a second acid adjustment tank rear tank 1020402, that is, two acid adjustment methods are used in the process of secondary acid adjustment, and a circulation pump 1020403 is added between the second acid adjustment tank front tank 1020401 and the second acid adjustment tank rear tank 1020402. The purpose of adopting this method is mainly that the acidity achieved by the secondary acid adjustment is very strong, and the overall material needs to be uniform at this time, so two acid adjustment tanks are used to make the subsequent process more stable.

[0055] In addition, since the acid concentration of the second acid conditioning solution is 1% to 3%, the acidity is too high to be detected by the pH sensor, and the corresponding purpose can only be achieved by flow control of the metering pump. A material taking port can be added here so that the acid concentration of the second acid conditioning solution can be detected manually.

[0056] More preferably, in an exemplary embodiment, if Figure 4 As shown, the hydrolysis reactor 202 transports the hydrolyzate to the transfer tank 301 through the reactor discharge pump 20201. Figure 5As shown, the transfer tank 301 transports the hydrolyzate to the flash tank 302 via the flash transfer pump 30101 , and the flash tank 302 transports the xylose solution obtained by flash evaporation via the flash discharge pump 30204 .

[0057] Specifically, in this exemplary embodiment, after the hydrolysis reaction kettle 202 carries out the hydrolysis reaction, the material (hydrolyzate) is sent to the transfer tank 301 through the reactor discharge pump 20201. The transfer tank 301 allows the reacted material to settle and then sends it to the flash tank 302 through the flash transfer pump 30101. The flash tank 302 cools the material and sends the xylose solution obtained by flash evaporation through the flash discharge pump 30204 to the next stage or for storage.

[0058] More preferably, in an exemplary embodiment, the heating material feed end of the plate heat exchanger 303 is connected to the discharge end of the ceramic membrane filtration equipment 401, and the heating material discharge end of the plate heat exchanger 303 is connected to the feed end of the secondary acid adjustment unit 102; the heat source air inlet end of the plate heat exchanger 303 is connected to the steam air outlet end of the flash tank 302, and the heat source air outlet end of the plate heat exchanger 303 is connected to the gas-water separator; the gas-water separator 304 separates the gas and water and collects them.

[0059] Specifically, in this exemplary embodiment, the plate heat exchanger 303 has four ports, two of which are the inlet and outlet ports for the heating material, namely, the heating material feed end and the heating material discharge end, which are respectively connected to the discharge end of the ceramic membrane filtration equipment 401 and the feed end of the secondary acid adjustment unit 102; the other two are the heat source inlet and outlet ports, namely, the heat source air inlet end and the heat source air outlet end, which are respectively connected to the steam outlet end of the flash tank 302 and the gas-water separator 304.

[0060] Among them, the gas-water separator 304 realizes steam liquefaction separation, and the separated secondary gas condensate is collected in the collection tank through the condensate pump 30401. The separated gas can be extracted by the gas vacuum pump 30402, and can also be returned to the corresponding flash tank 302 for pressure regulation control through the pneumatic regulating valve 30403. In addition, the pressure regulation control of the flash tank 302 also needs to be realized by external compressed air (the transfer tank 301 is also connected to compressed air).

[0061] More preferably, in an exemplary embodiment, the material pipe and the steam pipe of the plate heat exchanger 303 are made of Hastelloy.

[0062] More preferably, in an exemplary embodiment, if Figure 5 As shown, the plate heat exchanger 303 includes three, namely, a first plate heat exchanger 30301, a second plate heat exchanger 30302 and a third plate heat exchanger 30303, and the flash tank 302 includes three, namely, a first flash tank 30201, a second flash tank 30202 and a third flash tank 30203;

[0063] The heating material feed end of the first plate heat exchanger 30301 is connected to the discharge end of the ceramic membrane filtration device 401, the heating material discharge end of the first plate heat exchanger 30301 is connected to the heating material feed end of the second plate heat exchanger 30302, and the heating material discharge end of the second plate heat exchanger 30302 is connected to the feed end of the secondary acid adjustment unit 102; the heating material feed end of the third plate heat exchanger 30303 is connected to external materials;

[0064] The feed end of the first flash tank 30201 is connected to the discharge end in the transfer tank 301, the discharge end of the first flash tank 30201 is connected to the feed end of the second flash tank 30202, the discharge end of the second flash tank 30202 is connected to the feed end of the third flash tank 30203, and the discharge end of the third flash tank 30203 transports the xylose solution obtained by flash evaporation; the steam outlet end of the first flash tank 30201 is connected to the heat source inlet end of the second plate heat exchanger 30302, the steam outlet end of the second flash tank 30202 is connected to the heat source inlet end of the first plate heat exchanger 30301, and the steam outlet end of the third flash tank 30203 is connected to the heat source inlet end of the third plate heat exchanger 30301;

[0065] The temperature and pressure of the first flash tank 30201, the second flash tank 30202 and the third flash tank 30203 are gradually reduced.

[0066] Compared with the prior art in which there is only one heat exchange process for heating the raw materials, the temperature range is large and the heat exchange effect is poor, and corresponding to the problem that the prior art uses the heat exchanger to pass the product and easily damages the heat exchanger and clogs the pipeline, in this exemplary embodiment, three flash tanks 302 are used (a first flash tank 30201, a second flash tank 30202 and a third flash tank 30203), and three plate heat exchangers 303 are used (a first plate heat exchanger 30301, a second plate heat exchanger 30302 and a third plate heat exchanger 30303).

[0067] Specifically, in this exemplary embodiment, the first acid adjustment liquid after salt filtration by the ceramic membrane filtration device 401 passes through the first heat exchange of the first plate heat exchanger 30301 and the first heat exchange of the second plate heat exchanger 30302 in sequence, and then enters the secondary acid adjustment unit 102 for acid adjustment; at the same time, the first flash tank 30201, the second flash tank 30202 and the third flash tank 30203 flash the hydrolyzate in sequence, and the corresponding temperature and pressure decrease in sequence, and the steam temperature provided by the first flash tank 30201, the second flash tank 30202 and the third flash tank 30203 also decreases in sequence, so the second temperature steam generated by the second flash tank 30202 is used to heat the first plate heat exchanger 30301 to complete the heat exchange at a lower temperature, and then the first temperature steam generated by the first flash tank 30202 is used to heat the second plate heat exchanger 30302 to complete the heat exchange at a higher temperature, so that the heat exchange of the raw material has a certain span and the heat exchange effect is better. As for the steam of the third temperature generated by the third flash tank 30203, since the temperature drops to a relatively low level, it is not suitable for heating the material, so other external materials can be heated.

[0068] In a specific exemplary embodiment, the temperature of the first flash tank 30201 is 90-100°C and the pressure is -7kPa; the temperature of the second flash tank 30202 is 85-90°C and the pressure is -30kPa; the temperature of the third flash tank 30203 is 80-850°C and the pressure is -50kPa. Pressure also corresponds to vacuum degree.

[0069] More preferably, in an exemplary embodiment, a reactor agitator is provided in the hydrolysis reactor 202, and the reactor agitator operates according to the hydrolysis time interval.

[0070] Specifically, in this exemplary embodiment, the hydrolysis reactor 202 uses steam (through a steam pipe) to heat the material for hydrolysis reaction, and is provided with a reactor agitator to make the material reaction more complete. However, each hydrolysis reaction is about 3-5 hours, and if the reactor agitator is stirred all the time, it will waste power resources. Therefore, in this exemplary embodiment, the reactor agitator is operated according to the hydrolysis time interval, which not only meets the power requirement, but also achieves energy saving effect.

[0071] More preferably, in an exemplary embodiment, the hydrolysis reactor 202 is provided with a compressed air pipe, and the compressed air pipe is used to release pressure during the feeding process and to replenish pressure during the discharging process, so as to ensure the pressure in the reactor.

[0072] Specifically, in this exemplary embodiment, the hydrolysis reactor 202 is operated as a closed pressure vessel. In order to ensure the pressure in the reactor, the compressed air pipe will be interlocked with the valve to release pressure during the feeding process and replenish pressure during the discharging process.

[0073] More preferably, in an exemplary embodiment, a hydrolysis discharge filter is provided in the hydrolysis reactor 202 for filtering the material residue generated during the hydrolysis process; and a flash evaporation discharge filter is provided in the flash tank 302 for filtering the material residue generated during the flash evaporation process.

[0074] More preferably, in an exemplary embodiment, both the hydrolysis reactor 202 and the plate heat exchanger 303 can be connected to an alkali tank via an alkali pump to clean the carbides inside.

[0075] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A system for stabilizing xylose solution by using hemicellulose alkali solution, characterized in that: It includes acid adjustment subsystem, salt filtration subsystem, hydrolysis subsystem and flash evaporation subsystem; The acid conditioning subsystem includes a primary acid conditioning unit and a secondary acid conditioning unit, the hydrolysis subsystem includes an ejector and a hydrolysis reactor, the flash evaporation subsystem includes a transfer tank, a flash evaporation tank and a plate heat exchanger, and the salt filtration subsystem includes a ceramic membrane filtration device; The primary acid adjustment unit performs primary acid adjustment on the hemicellulose alkali liquor to obtain a first acid adjustment liquid with a pH value of 4-6. The first acid adjustment liquid enters the secondary acid adjustment unit for secondary acid adjustment after being filtered by a ceramic membrane filter device and heated by a plate heat exchanger to obtain a second acid adjustment liquid with an acid concentration of 1% to 3%. The ejector injects the second acid adjustment liquid into a hydrolysis reactor for hydrolysis reaction to obtain a hydrolyzed liquid which enters a transfer tank. The flash tank flashes the hydrolyzed liquid in the transfer tank, collects the xylose liquid obtained by the flash evaporation, and the steam obtained by the flash evaporation enters the plate heat exchanger as a heating heat source.

2. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1, characterized in that: The primary acid adjustment unit comprises a first concentrated sulfuric acid tank, a first concentrated sulfuric acid metering pump, a first acid adjustment mixer, a first acid adjustment tank, a first acid adjustment discharge pump and a pH sensor; the first concentrated sulfuric acid tank is connected to a first acid adjustment feed end of the first acid adjustment mixer through a first concentrated sulfuric acid metering pump, and a second acid adjustment feed end of the first acid adjustment mixer is connected to a hemicellulose alkali solution; the first acid adjustment mixer mixes the hemicellulose alkali solution and the concentrated sulfuric acid, and detects the pH value in the first acid adjustment mixer in real time through a pH sensor, and after mixing, the first acid adjustment liquid enters the first acid adjustment tank to be stored; the first acid adjustment discharge pump transports the first acid adjustment liquid in the first acid adjustment tank.

3. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1, characterized in that: The secondary acid adjustment unit comprises a second concentrated sulfuric acid tank, a second concentrated sulfuric acid metering pump, a second acid adjustment mixer, and a second acid adjustment discharge pump for the second acid adjustment tank; the second concentrated sulfuric acid tank is connected to the first acid adjustment feed end of the second acid adjustment mixer through the second concentrated sulfuric acid metering pump, and the second acid adjustment feed end of the second acid adjustment mixer is connected to the filtered first acid adjustment liquid; the second acid adjustment mixer mixes the filtered first acid adjustment liquid and concentrated sulfuric acid, and the mixed acid enters the second acid adjustment tank to store the second acid adjustment liquid; the second acid adjustment discharge pump transports the second acid adjustment liquid in the second acid adjustment tank.

4. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1, characterized in that: The hydrolysis reactor conveys the hydrolyzate to the transfer tank via the reactor discharge pump, the transfer tank conveys the hydrolyzate to the flash tank via the flash transfer pump, and the flash tank conveys the xylose solution obtained by flash evaporation via the flash discharge pump.

5. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1, characterized in that: The heating material feed end of the plate heat exchanger is connected to the discharge end of the ceramic membrane filtration equipment, and the heating material discharge end of the plate heat exchanger is connected to the feed end of the secondary acid adjustment unit; the heat source air inlet end of the plate heat exchanger is connected to the steam air outlet end of the flash tank, and the heat source air outlet end of the plate heat exchanger is connected to the gas-water separator; the gas-water separator separates gas and water and collects them.

6. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1 or 5, characterized in that: The material pipeline and steam pipeline of the plate heat exchanger are made of Hastelloy.

7. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1 or 5, characterized in that: The plate heat exchangers include three, namely, a first plate heat exchanger, a second plate heat exchanger and a third plate heat exchanger, and the flash tanks include three, namely, a first flash tank, a second flash tank and a third flash tank; The heating material feed end of the first plate heat exchanger is connected to the discharge end of the ceramic membrane filtration device, the heating material discharge end of the first plate heat exchanger is connected to the heating material feed end of the second plate heat exchanger, and the heating material discharge end of the second plate heat exchanger is connected to the feed end of the secondary acid adjustment unit; the heating material feed end of the third plate heat exchanger is connected to external materials; The feed end of the first flash tank is connected to the discharge end in the transfer tank, the discharge end of the first flash tank is connected to the feed end of the second flash tank, the discharge end of the second flash tank is connected to the feed end of the third flash tank, and the discharge end of the third flash tank transports the xylose solution obtained by flash evaporation; the steam outlet end of the first flash tank is connected to the heat source inlet end of the second plate heat exchanger, the steam outlet end of the second flash tank is connected to the heat source inlet end of the first plate heat exchanger, and the steam outlet end of the third flash tank is connected to the heat source inlet end of the third plate heat exchanger; The temperature and pressure of the first flash tank, the second flash tank and the third flash tank are gradually reduced.

8. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 7, characterized in that: The temperature of the first flash tank is 90-100°C and the pressure is -7kPa; the temperature of the second flash tank is 85-90°C and the pressure is -30kPa; the temperature of the third flash tank is 80-850°C and the pressure is -50kPa.

9. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1, characterized in that: A reactor stirrer is arranged in the hydrolysis reactor, and the reactor stirrer operates according to the hydrolysis time interval.

10. The system for stably producing xylose solution by using hemicellulose alkali solution according to claim 1, characterized in that: The hydrolysis reactor is provided with a compressed air pipe, which is used to release pressure during the feeding process and to replenish pressure during the discharging process, thereby ensuring the pressure in the reactor.

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