• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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  • 优先权
    • 专利摘要:
    A method and system for the treatment of sludge in a chemical pulp mill including a step of hydrothermal carbonization (HTC) of a sludge stream, wherein said sludge stream is fed into a HTC arrangement and subjected to elevated temperature and pressure, producing at least one solids fraction, at least one liquid fraction, and at least one gaseous fraction; wherein said solids fraction is fed to a power boiler of said pulp mill and burned to generate steam; said liquid fraction is combined with weak black liquor from the pulp mill and fed to a black liquor evaporator of said pulp mill, and the resulting concentrated black liquor is burned in a recovery boiler of said pulp mill.
    公开号:SE1651305A1
    申请号:SE1651305
    申请日:2016-10-05
    公开日:2018-04-06
    发明作者:Lundqvist Fredrik；Odén Erik；Öhman Fredrik
    申请人:C Green Tech Ab；
    IPC主号:
    专利说明:

    [1] [0001] The present disclosure relates generally to the treatment of sludgegenerated in chemical pulp mills, and in particular to a method and systeminvolving a step of hydrothermal carbonization of said sludge, feeding the resultingsolids and liquid fractions to the power boiler and recovery boiler respectively, and thus integrating the sludge handling in the steam generation for the pulp mill.
    [2] [0002] Sludge, a slurry of solids and water, including dissolved material, is whatremains after wastewater treatment in municipal and industrial wastewatertreatment plants. Industrial wastewater treatment plants treat water effluents fromdifferent industrial processes, for example pulp and paper mills, industrial foodproduction facilities etc. All wastewater treatment plants in use generate sludgethat needs to be handled in one way or the other. The sludge is either recovereddirectly from the plant after dewatering (aerobic sludge) or first treatedanaerobically for biogas production where part of the sludge is digested and the remainder is recovered as anaerobic sludge, also called biosludge.
    [3] [0003] Large quantities of wastewater are generated in the production of pulpand paper. These must be properly handled in order to avoid severe pollution ofthe environment. Current wastewater treatment in pulp and paper mills combinessedimentation, chemical precipitation, flotation and biological treatment where thespecific combination of techniques is determined by the local conditions.Unavoidably, the wastewater treatment generates large volumes of sludge.
    [4] [0004] The handling of sludge in chemical pulp and paper mills, in particularsurplus sludge from biological treatment of liquid effluent, also known asbiosludge, is a considerable problem and carries significant specific costs per tonsludge treated. There are today three main solutions in use, and all these areassociated with specific disadvantages. 160516SE
    [5] [0005] The sludge can be incinerated in the power boiler of the pulp mi|,contributing to the production of steam necessary for the pulp and paper makingprocess. This has the advantage of avoiding that the inorganic content of thesludge is introduced into the closed pulp mi| cycle. With suitable treatment of fluegases and ashes, harmful chemicals and heavy metals can be neutralized or evenrecovered. Sludge with high concentrations of organic and/or biologicalcomponents is however generally very difficult to dewater. The water content isfrequently so high that the net heating value if incinerated in a power plant is verylow or even negative. Combustion of sludge will therefore increase the load on the power boiler as well as require support fuel.
    [6] [0006] Further, the handling of wet sludge is problematic due to the exposure topathogens, smell and the formation of poisonous hydrogen sulfide gas. Thermaldrying of the sludge consumes about the same amount of heat as the latent heatin the sludge. Thus, this is not an economically attractive alternative. lt is thereforefair to say that sludge is currently viewed as a biofuel of poor quality due to its highwater content, and consequently some pulp mills treat it solely as a disposalproblem.
    [7] [0007] Another alternative is combustion in the recovery boiler. Sludge is firsthydrolysed with heat and alkali and then mixed with black liquor before feeding themixture to the evaporators to increase its dry solids content before combustion inthe recovery boiler. An advantage of this alternative is that a multi-effectevaporation plant can be used to dewater the sludge before combustion in therecovery boiler, and the energy content of the sludge is utilized. This howeveroften requires a pre-hydrolysis treatment where alkali is charged. The ash from thesludge contains inert components such as phosphorus and silica which willaccumulate in the lime cycle and give rise to an increased make-up lime demand.Additionally, the amount of spent lime that has to be handled will increase. ln theend, this alternative is therefore associated with significant specific handling costsper ton sludge treated. 160516SE
    [8] [0008] ln addition, the sludge contains significant amounts of other non-processelements (NPEs) such as aluminum, calcium, iron, potassium and chlorides whichcan cause problems in the pulp mill, such as corrosion, fouling, worse dewateringproperties ofgreen Iiquor dregs and lime mud etc. Each of these is bound tosignificantly increase the operating costs and maintenance requirements of the pulp mill.
    [9] [0009] Finally, the sludge can be designated for external use, for example aslandfill or landfill cover, as fertilizer or as soil replacement products. This howeverrepresents a costly and environmentally less attractive treatment, as it includes thetransport of large volumes of material with high moisture content. Additionally,there will be high emissions of nitrous oxide and methane to the atmosphere asthe sludge decomposes. Methane is a greenhouse gas, and although it doesn'tlinger as long in the atmosphere as carbon dioxide, it is initially far moredevastating to the climate because of how effectively it absorbs heat. lt follows that methane emissions must be minimized.
    [10] [0010] Hydrothermal carbonization (HTC) also known as wet torrefaction is athermochemical process used in the production of charred matter similar incomposition to coal. lt involves subjecting a wet, carbohydrate feedstock, such assludge, to an elevated temperature (180 °C - 350 °C) and pressure (up to 2.- 5MPa) in a closed system. The resulting product is frequently referred to as biochar, a product which is friable, hydrophobic, and has a significantly increasedenergy density compared to the starting material.
    [11] [0011] WO 2015/025076 (Valmet Technologies Oy) relates to the application ofa HTC process in a pulp mill. According to the application, lignin is separated froma lignin containing liquid medium, such as pulp mill black Iiquor, and subjected tofurther treatment. The method comprises at least the following steps: a) aprecipitation stage, wherein a pH lowering agent is added to the lignin containingslurry for precipitating lignin, b) followed by a first separation stage, wherein theprecipitated lignin is separated as a lignin cake from the remaining liquid phase ofthe lignin containing slurry, c) a suspending stage, wherein the lignin cake is 160516SE suspended for obtaining a lignin suspension, d) a hydrothermal carbonizationstage, wherein the lignin suspension is treated for obtaining a slurry of carboncontaining material, and e) a second separation stage, wherein the carboncontaining material is separated from the slurry.
    [12] [0012] lt has been found that hydrothermal carbonization of chemical pulp andpaper mill sludge, in particular biosludge, can be effectively integrated in thechemical pulp and paper mill provided that some non-intuitive adaptations of theprocess are performed. The resulting system is energy efficient, contributesfavorably to the generation of steam for the pulp and paper making process, andeliminates a considerable problem in that the sludge volumes are significantly reduced or even eliminated.
    [13] [0013] A first aspect relates to a method for treatment of sludge in a chemicalpulp mill including a step of hydrothermal carbonization (HTC) of a sludge stream, wherein - said sludge stream is fed into a HTC arrangement comprising a HTC reactorand subjected to elevated temperature and pressure, producing at least one solids fraction, at least one liquid fraction, and at least one gaseous fraction; - said at least one solids fraction is fed to a power boiler of said pulp mill andburned to generate steam; - said at least one liquid fraction is combined with weak black liquor from the pulp mill and fed to a black liquor evaporator of said pulp mill, and - the resulting concentrated black liquor is burned in a recovery boiler of saidpulp mill.
    [14] [0014] According to an embodiment of said first aspect, said at least onegaseous fraction from said HTC arrangement is combined with air and theresulting mixed gas fed into the power boiler. 160516SE
    [15] [0015] According to another embodiment of said first aspect, freelycombinable with the above, the liquid fraction is subjected to oxidation before it is combined with black Iiquor.
    [16] [0016] According to another embodiment of said first aspect, freelycombinable with the above, part of the steam generated by the power boi|er isused to heat one or more of the HTC arrangement, the HTC reactor or the inflow of sludge to said reactor and/or arrangement.
    [17] [0017] ln the above embodiments, the e|evated temperature in said HTC stepis a temperature in the interva| of 180 - 350 °C, preferably 180 - 300 °C, and mostpreferably 180 to 230°C.
    [18] [0018] According to an embodiment, in order to ensure and optimize theenrichment of NPEs in the solid product, the pH in the hydrothermai carbonization reaction is controlled, most preferably to a pH above 5.
    [19] [0019] According to another embodiment, freely combinable with the aboveembodiments, the chemical pulp mill operates according to the kraft process (thesulfate process). Preferably the sludge in question is the biosludge from thetreatment of Wastewater from said pulp mill. The sludge can also be a combinationof sludge from the pulp mill and sludge from other sources, for example from municipal waste water treatment.
    [20] [0020] A second aspect relates to a system for treatment of sludge from achemical pulp mill, comprising a hydrothermai carbonization (HTC) arrangement,comprising a HTC reactor, wherein said system further comprises - an arrangement for introducing said sludge into said reactor;- a heater for heating said sludge; - at least one separation arrangement in or downstream of said HTC reactorfor producing at least one solids fraction, at least one liquid fraction, and at least one gaseous fraction; 160516SE - a feeding arrangement for feeding said at least one solids fraction to a power boiler of said pulp mill; and - a feeding arrangement for feeding said at least one liquid fraction to a black liquor evaporator of said pulp mill.
    [21] [0021] According to an embodiment of said second aspect, the systemcomprises an arrangement for combining said at least one gaseous fraction withair and feeding the resulting mixed gas into said power boiler.
    [22] [0022] According to another embodiment of said second aspect, freelycombinable with the above, the system comprises a heater arranged to receivesteam from said power boiler. Preferably said heater is adapted to heat said HTCreactor or to heat the inflow of sludge to said reactor.
    [23] [0023] According to another embodiment of said second aspect, freelycombinable with the other embodiments, the system comprises a reactor foroxidation of the liquid fraction, as well as auxiliary equipment for feeding anoxidizing agent into said reactor, and equipment for recovering heat generated in said oxidation.
    [24] [0024] According to another embodiment of said second aspect, freelycombinable with the above embodiments, the chemical pulp mill operatesaccording to the kraft process (the sulfate process). Preferably the sludge inquestion is biosludge from the treatment of wastewater from said pulp mill. Thesludge can also be a combination of sludge from the pulp mill and sludge fromother sources, for example from municipal waste water treatment.
    [25] [0025] According to yet another embodiment, freely combinable with theabove embodiments, the system is housed in a mobile unit, preferably a shipping container. 160516SE Brief description of the drawinqs
    [26] [0026] Embodiments of the invention will be described in further detail below, in the description, examples and appended claims, and in the drawings in which Fig. 1 schematically i|ustrates how the HTC process can be integrated in achemical pulp mill; andFig. 2 schematically shows components of the HTC arrangement, the HTC reactor and auxiliary equipment.
    [27] [0027] Before the present invention is described, it is to be understood thatthe terminology employed herein is used for the purpose of describing particularembodiments only and is not intended to be limiting, since the scope of thepresent invention will be limited only by the appended claims and equivalentsthereof.
    [28] [0028] lt must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
    [29] [0029] As described in the background section, the production of pulp andpaper generates large quantities of wastewater. Unavoidably, the wastewatertreatment generates large volumes of sludge.
    [30] [0030] Sludge and in particular biosludge contains comparatively highconcentrations of inorganic compounds that are unwanted in the process (non-process elements, NPEs). Even though the biosludge is a small stream comparedto e.g. the wood intake to the pulp mill, the high concentration of NPEs leads to asignificant total intake to the pulp mill. ln a report published 2003, Johan Dahlbomdiscusses the effects of NPEs in the chemical recovery system of a kraft pulp mill[Dahlbom, J., Effekter av PFG vid indunstning och förbränning av bioslam i ettmassabruks sodapanna (English translation: Effects of Non Process Elements in the chemical recovery system of a kraft pulp mill from the incineration in the 160516SE recovery boiler of biological sludge), Rapport 798, Värmeforsk Service AB, S2-226,2003]
    [31] [0031] Dahlbom investigated the relative contribution of NPEs in biosludge to the overall intake in a Swedish pulp mill. His results are shown in Table 1.
    [33] [0033] Due to the integration possibilities, a system as disclosed herein ispreferably built in close proximity to the power boiler. When refurbishing anexisting pulp mill, or when projecting and building a new mill, the integration of thesystem can be optimized by a person skilled in the art, based on the guidanceobtained herein. For existing pulp mills, it is conceived that a system as disclosedherein is supplied in a mobile unit, to be placed in vicinity of the power burner and connected thereto. 160516SE
    [34] [0034] A first aspect relates to a method for treatment of sludge in a chemicalpulp mill including a step of hydrothermal carbonization (HTC) of a sludge stream, wherein said sludge stream is fed into a HTC arrangement comprising a HTC reactor, and subjected to elevated temperature and pressure, producing atleast one solids fraction, at least one liquid fraction, and at least one gaseous fraction; - said at least one solids fraction is fed to a power boiler of said pulp mill and burned to generate steam; - said at least one liquid fraction is combined with weak black liquor from the pulp mill and fed to a black liquor evaporator of said pulp mill, and - the resulting concentrated black liquor is burned in a recovery boiler of said pulp mill.
    [35] [0035] A general embodiment of the integration of a HTC process in achemical pulp mill is illustrated in Fig. 1 where a sludge stream (A) is fed to a HTCarrangement (HTC) from which the resulting liquid fraction (B) is fed to the blackliquid evaporators of the pulp mill, and mixed with thin black liquor, sometimes alsoreferred to as weak black liquor. The resulting solids fraction is then combusted inthe recovery boiler. The resulting steam can be used to heat the evaporators andalso for other energy needs in the pulp mill. The resulting solids fraction (C) is fedto the power boiler of the pulp mill, preferably together with the HTC off-gas (D). Afraction (E) of the steam generated by the power boiler can be used for heating the HTC arrangement, the HTC reactor or the incoming sludge.
    [36] [0036] The HTC arrangement preferably comprises several components asschematically illustrated in Fig. 2. Here, the dashed line delimits the HTCarrangement shown simply as a “HTC-box” in Fig. 1. A HTC reactor (10) is shownas the central component of the HTC arrangement. Sludge (A) is fed into the HTCarrangement in to equipment (50) for receiving and diluting the sludge, for example a tank with a mixer. The sludge can then be pre-heated in a pre-heater 160516SE (60) which can be any type of suitable heat exchanger, such as a double-tube or atube-and-shell type heat exchanger. The pre-heater (60) is preferably heated bysteam (E) from one or more flash recovery steps (30). A final heater (70) ispreferably provided immediately before the HTC reactor (10). The final heater (70)is preferably heated by steam (F) from the power boiler. The choice of type,configuration and dimension of the pre-heater and final heater can be made by askilled person.
    [37] [0037] According to one embodiment, a solids fraction and a liquid fractionare withdrawn directly from the HTC reactor (not shown). ln the embodimentshown in Fig. 2, a single liquid HTC product is withdrawn from the HTC reactor(10) and subjected to separation in one or more steps. Here, it is first subjected toa step of flash evaporation (30), also referred to as flash steam recovery, followedby another step of solids / liquid separation (40). The flash evaporation stepproduces steam (E) which can be used to pre-heat the incoming sludge. Thesecond step of solids / liquid separation (40) can be chosen from a sedimentationstep, a filtering step, a filter press, a solids / liquid separator screw or compactor,or the like. ln one embodiment, for example when using a filter press, the solidsfraction is concentrated to an interval of 60 - 75 % DS and the liquid fraction will contain less than 10 % DS.
    [38] [0038] Said HTC reactor (10) also produces off-gas which preferably is fed toa condenser (20) supplied with a cooling liquid (G) which can be water. Thecondensate is recirculated to the sludge receiving and dilution step (50) and theoff-gas (D) is preferably fed to the power boiler and combusted. Optionally the off-gas can be mixed with air, preferably compressed air, before feeding to the powerboiler.
    [39] [0039] The HTC arrangement shown within the dashed line in Fig. 2 is onlyan example of how the HTC step can be integrated in a pulp mill.
    [40] [0040] ln the above embodiments, the sludge stream referred to is a sludgestream generated in the chemical pulp mill, or a combination of different sludgestreams, at least some of which are generated in the chemical pulp mill. The 160516SE11 sludge can thus be a combination of sludge from the pulp mill and sludge fromother sources, for example from municipal waste water treatment. ln the presentmethod and system, sludge from the chemical pulp mill is used to produce anenergy-rich solid product with high dry solids content which can be fired efficientlyin the bower boiler of the mill and used to generate steam and power for the mill.lnterestingly, most of the inert components, such as P and Si are contained in thesolid product.
    [41] [0041] According to an embodiment, in order to ensure and optimize theenrichment of NPEs in the solid product, the pH in the hydrothermal carbonizationreaction is controlled, most preferably to a pH above 5, by the addition of suitablealkaline compounds (e.g. black liquor, spent lime mud). Already at pH 5, elementssuch as Ca and P will start to dissolve to a greater degree in the process water.Further pH adjustments, for example increasing the pH to neutral or alkaline pH,are preferably performed to influence the distribution of NPEs between the HTCliquid and HTC solids fraction.
    [42] [0042] According to an embodiment of the first aspect, the liquid from thehydrothermal carbonization, which normally contains about 15-30% of the organicmaterial, is sent to the pulp mill evaporation plant, where it will be evaporated andcombusted together with the black liquor. An advantage is that its energy contentwill generate at least enough steam to drive the evaporation and very likely alsogenerate a surplus for the pulp process. ln the hydrothermal carbonizationprocess, the liquor will be heated up to around 90 °C, thus requiring very little pre-heating when it is introduced into the evaporator train.
    [43] [0043] According to another embodiment, freely combinable with the otheraspects and embodiments, the liquid from the hydrothermal carbonization issubjected to oxidation before being combined with the black liquor. The oxidationstep is performed at a temperature in the interval of 180 - 300 °C, preferably 230to 300°C, by the injection of an oxidizing agent into said first fraction. Said oxidizing agent is preferably chosen from oxygen, hydrogen peroxide, 160516SE12 percarbonate, and percarbonic acids, and preferably an oxygen containing gas,such as air, most preferably compressed air.
    [44] [0044] According to another embodiment of said first aspect, said at leastone gaseous fraction from the HTC reactor is combined with air and fed to thepower boiler. This has the advantages that it adds fuel to the boiler; it ensuresdestruction of possible organic residues in the HTC gas; and minimizes costs forgas treatment in the HTC plant.
    [45] [0045] According to another embodiment, freely combinable with the above,part of the steam generated by the power boiler is used to heat the HTC reactor or the inflow of sludge to said reactor.
    [46] [0046] ln the above embodiments, the elevated temperature in said HTC stepis a temperature in the interval of 180 - 350 °C, preferably 180 - 300 °C, mostpreferably 180 - 230°C.
    [47] [0047] According to another embodiment, freely combinable with the aboveembodiments, the chemical pulp mill operates according to the kraft process (thesulfate process). Preferably said sludge is biosludge from the treatment ofwastewater from said pulp mill. The sludge can also be a combination of sludgefrom the pulp mill and sludge from other sources, for example from municipal waste water treatment.
    [48] [0048] A second aspect relates to a system for treatment of sludge from achemical pulp mill, comprising a hydrothermal carbonization (HTC) reactor,wherein said system further comprises - an arrangement for introducing said sludge into said reactor;- a heater for heating said sludge; - a separation arrangement downstream of said HTC reactor for producing atleast one solids fraction, at least one liquid fraction, and at least one gaseous fraction; 160516SE13 - a feeding arrangement for feeding said at least one solids fraction to a power boiler of said pulp mill; and - a feeding arrangement for feeding said at least one liquid fraction to a black liquor evaporator of said pulp mill.
    [49] [0049] According to an embodiment of said second aspect, the systemcomprises an arrangement for combining said at least one gaseous fraction withair and feeding the resulting mixed gas to said power boiler. As stated above, thishas an advantage in that possible organic residues are destructed, whichminimizes the requirements and costs for gas treatment in the HTC plant.
    [50] [0050] According to another embodiment of said second aspect, freelycombinable with the other embodiments, the system comprises a reactor foroxidation of the liquid fraction, as well as auxiliary equipment for feeding anoxidizing agent into said reactor, and equipment for recovering heat generated insaid oxidation. Such equipment can comprise a compressor for injectingcompressed air into the liquid fraction. A vapor-liquid separator or flashing arrangement for cooling the oxidized liquid can also be included.
    [51] [0051] According to another embodiment, freely combinable with the above,the system comprises a heater arranged to receive steam from said power boiler.Preferably said heater is adapted to heat said HTC reactor or to heat the inflow of sludge to said reactor.
    [52] [0052] According to another embodiment, freely combinable with the aboveembodiments, the chemical pulp mill operates according to the kraft process (thesulfate process). Preferably said sludge is biosludge from the treatment ofwastewater from said pulp mill. The sludge can also be a combination of sludgefrom the pulp mill and sludge from other sources, for example from municipal waste water treatment.
    [53] [0053] The system is preferably integrated in the pulp plant, for example builtinto and fully integrated in new plants, or as an add-on to existing plants.
    [54] [0054] lt is conceived that, in a kraft pulp mill such as that studied byDahlbom, where sludge currently is mixed with black liquor, evaporated andcombusted in the recovery boiler, introduction of this process will have a verypositive impact on the NPE intake to the closed cycle of the mill. Recycling of onlythe HTC liquid instead of the whole sludge stream would reduce the total intake ofAl, Si, P, Ca, Cl and Fe to the closed cycle of the mill by 23, 17, 11, 6, 6 and 10% respectively.
    [55] [0055] This reduces both the need for fresh lime make-up and dischargedlime handling by 0.4-1 t/t DS sludge. Reduction of chlorides will have a positiveimpact on corrosion and fouling of the recovery boiler heat transfer surfaces.Reduction of Al, Si and Ca will positively affect fouling on black liquor evaporatorsurfaces as well as improve the filtration properties of green liquor dregs and lime mud.
    [56] [0056] ln a method or in a system as disclosed herein, the HTC product iscombusted in the mill power boiler at high dry solids content to generate steam todrive the HTC process as well as a steam surplus that can be used in the mill. TheHTC liquid is evaporated together with the black liquor and the dissolved organicsare combusted in the recovery boiler generating enough steam to drive theevaporation. Thus, the energy content of the sludge is efficiently used, while at thesame time avoiding the problems related to NPE intake to the closed cycle of thechemical pulp mill.
    [57] [0057] lncluding a step of oxidation of the liquid fraction makes it possible toextract heat in the form of steam from the liquid fraction, contributing to the heatingrequirements of the pulp mill or to the heating requirements of the HTC process.The oxidation step also makes it possible to reduce the liquid volume beforemixing with the black liquor. Additionally, the oxidation step will result in chemicalreactions in the liquid fraction, for example decomposing various chemicalsubstances. 160516SE
    [58] [0058] Other advantages will be evident to a skilled person upon study of thepresent disclosure, including the examples, claims and drawings.
    [59] [0059] Biosiudge from a Swedish pulp mill was treated with hydrothermalcarbonization at a temperature of 200 °C in a stirred 0.5 l batch reactor. Biosludgewas Ioaded into the reactor and heated to the carbonization temperature. Aftercarbonization, the reactor was rapidly cooled, and the resulting slurry filtered.Separate analyses were made of the solid and liquid product to determine the distribution of NPEs in the respective phase.
    [60] [0060] The results showed a significant enrichment of important NPEs in thesolid HTC product, see Table 2. Thus, recycling of the HTC liquid to the blackliquor evaporators is possible with only a small impact on the NPE amounts in the closed pulp mill cycle.
    [61] [0061] Dewatering properties were tested by pouring samples of the slurry,before and after carbonization, onto a Büchner funnel. Filtering was measured askg DS/m2 filter surface X h. The HTC treated slurry exhibited significantly improved(over 300%) dewatering properties compared to the original biosludge. This will 160516SE16 allow efficient mechanical dewatering to up to 65-75% dry solids content. This inturn allows efficient utilization of the energy content in the sludge by combustion inthe power boiler of the mill, where the main content of NPEs will be found in theash.
    [62] [0062] Without further elaboration, it is believed that a person skilled in the artcan, using the present description, including the examples, utilize the presentinvention to its fullest extent. Also, although the invention has been describedherein with regard to its preferred embodiments, which constitute the best modepresently known to the inventors, it should be understood that various changesand modifications as would be obvious to one having the ordinary skill in this artmay be made without departing from the scope of the invention which is set forthin the claims appended hereto.
    [63] [0063] Thus, while various aspects and embodiments have been disclosedherein, other aspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scope and spirit beingindicated by the following claims.
    权利要求:
    Claims (10)
    [1] 1. A method for treatment of sludge in a chemical pulp mi| including a stepof hydrothermai carbonization (HTC) of a sludge stream, characterized in that - said sludge stream is fed into a HTC arrangement comprising a HTCreactor, and subjected to elevated temperature and pressure, producing atleast one solids fraction, at least one liquid fraction, and at least one gaseousfraction; - said at least one solids fraction is fed to a power boiler of said pulp mi| and burned to generate steam; - said at least one liquid fraction is combined with weak black liquor from the pulp mi| and fed to a black liquor evaporator of said pulp mi|, and - the resulting concentrated black liquor is burned in a recovery boiler of said pulp mi|.
    [2] 2. The method according to claim 1, wherein said at least one gaseousfraction from the HTC arrangement is combined with air and the resulting mixed gas is fed to the power boiler.
    [3] 3. The method according to claim 1 or 2, wherein part of the steamgenerated by the power boiler is used to heat the HTC reactor or the inflow of sludge to said reactor.
    [4] 4. The method according to any one of claims 1 - 3, wherein the elevatedtemperature in said HTC step is a temperature in the interval of 180 - 350 °C,preferably 180 - 300 °C, most preferably 180 - 230°C.
    [5] 5. The method according to any one of claims 1 - 4, wherein the chemicalpulp mi| operates according to the kraft process (sulfate process) and said sludge comprises biosludge from the treatment of wastewater from said pulp mi|. 160516SE18
    [6] 6. A system for treatment of sludge from a chemical pulp mill, comprising ahydrothermal carbonization (HTC) reactor, characterized in that said system further comprises- an arrangement for introducing said sludge into said HTC reactor;- a heater for heating said sludge; - a separation arrangement in or downstream of said HTC reactor forproducing at least one so|ids fraction, at least one liquid fraction, and at least one gaseous fraction; - a feeding arrangement for feeding said at least one so|ids fraction to apower boiler of said pulp mill; and - a feeding arrangement for feeding said at least one liquid fraction to a black liquor evaporator of said pulp mill.
    [7] 7. The system according to claim 6, wherein the system comprises anarrangement for combining said at least one gaseous fraction with air and feedingthe resulting mixed gas into said power boiler.
    [8] 8. The system according to claim 6 or 7, wherein the system comprises aheater arranged to receive steam from said power boiler, said heater adapted toheat said HTC reactor or to heat the inflow of sludge to said reactor.
    [9] 9. The system according to any one of claims 6 - 8, wherein the chemicalpulp mill operates according to the kraft process (sulfate process) and said sludgecomprises biosludge from the treatment of wastewater from said pulp mill.
    [10] 10. The system according to any one of claims 6 - 9, wherein said system orparts thereof is/are housed in a mobile unit, preferably in a shipping container.
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    同族专利:
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    WO2018067055A1|2018-04-12|
    EP3523404A4|2020-06-17|
    CL2019000893A1|2019-08-02|
    BR112019006748A2|2019-06-25|
    JP2019537674A|2019-12-26|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1651305A|SE540135C2|2016-10-05|2016-10-05|Method for hydrothermal carbonization of sludge in chemical pulp mills|SE1651305A| SE540135C2|2016-10-05|2016-10-05|Method for hydrothermal carbonization of sludge in chemical pulp mills|
    JP2019518213A| JP2019537674A|2016-10-05|2017-09-26|A method for hydrothermal carbonization of sludge in a chemical pulp mill.|
    PCT/SE2017/050932| WO2018067055A1|2016-10-05|2017-09-26|Method for hydrothermal carbonization of sludge in chemical pulp mills|
    BR112019006748A| BR112019006748A2|2016-10-05|2017-09-26|Method and system for sludge treatment in a chemical pulp mill|
    EP17858813.3A| EP3523404A4|2016-10-05|2017-09-26|Method for hydrothermal carbonization of sludge in chemical pulp mills|
    CL2019000893A| CL2019000893A1|2016-10-05|2019-04-03|Method for hydrothermal carbonization of sludge in chemical cellulose factories.|
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