EA044578B1 - METHOD (OPTIONS) AND INSTALLATION (OPTIONS) FOR THERMAL HYDROLYSIS OF LIQUID SUBSTRATE, AND ALSO METHOD (OPTIONS) FOR MODERNIZING AN EXISTING INSTALLATION FOR HYDROLYSIS OF LIQUID SUBSTRATE - Google Patents

Description

Field of technology to which the invention relates

The present invention relates to methods and apparatus that utilize thermal hydrolysis (TH) processes that utilize pulpers and flash tanks for preheating and pressure reduction, respectively. The present invention also relates to methods for upgrading existing plants that use thermal hydrolysis processes (THP).

State of the art

Thermal hydrolysis process (THP) is a process in which wet or moist material is treated at elevated temperatures, typically 140 to 220°C, which may be followed by a steam explosion as the partial pressure of the steam is rapidly reduced.

PTG followed by steam explosion is mainly used for pre-treatment of biosolids prior to anaerobic digestion. However, other materials can be pre-treated in the same way, after which they can be further processed through a wide range of other downstream processes.

Thermal hydrolysis processes can be designed for both batch and continuous operation. The methods and installations of the present invention are relevant both for PTG intended for periodic action and for PTG intended for continuous operation. In addition, the methods of the present invention can be used either in new installations or introduced into existing installations through modernization, including the installation of appropriate additional equipment and making appropriate changes.

The material that is processed in the PTG can be called a substrate. The substrate is treated with the required partial steam pressure. In a batch process, the time during which the substrate is maintained at the required conditions in the reactor is called retention time. For a continuous process, the average residence time in the reactor is a value that can be calculated based on the overall progress of the entire process.

The substrate will undergo rapid depressurization and undergo a steam explosion as it is discharged from the PTG reactor through the nozzle into the flash tank. This opens cell walls, destroys organic matter, reduces particle size and substrate viscosity. The flash steam produced by the steam explosion can be used to preheat the substrate in a pressure vessel, which may be called a pulper. The use of flash steam to preheat the substrate prior to reactor processing is important to achieve high energy efficiency and low steam consumption.

WO 1996/009882 (US 5888307) describes methods and means for hydrolyzing organic substances. The processes described do not involve the use of vacuum, nor flash evaporation, nor the use of steam resulting from any such process for direct steam injection to preheat incoming feedstock.

WO 2011/006854 describes methods and means for the hydrolysis of organic substances, including PTH and steam explosion, where the steam generated as a result of a sudden decrease in pressure is returned to a preheat tank. The process described in WO 2011/006854 uses liquid or steam at high pressure to create a driving stream in an ejector to mix the steam coming from the suction side with the main stream discharged into the vessel at atmospheric or higher pressure.

The method described in the present invention differs in that the system used to create a vacuum does not operate on steam, but only on non-condensable gases. This allows the system used to create a vacuum in the present invention to operate at lower pressures, temperatures, volume flow and mass flow compared to the method described in WO 2011/006854. This makes the system described in the present invention more energy efficient, more reliable and easier to operate compared to the method described in WO 2011/006854.

WO 2014/123426 describes additional methods and means for the hydrolysis of organic substances using PTH and steam explosion. Similar to WO 1996/009882 (US 5888307), this method does not involve the use of a vacuum, flashing steam below ambient pressure, nor the use of steam resulting from any such process for direct steam injection to preheat the incoming feed.

US 2003121851 describes methods and means for hydrolyzing organic matter, including the addition of KOH and a dehydration step after PTH. Flash steam utilization is similar to that described in WO 1996/009882 and therefore involves neither the use of a vacuum flashing below ambient pressure nor the use of the resulting flash steam from any such process for direct steam injection for preheating incoming raw materials.

US 6,281,300 describes methods and means for hydrolyzing organic matter. The described processes do not involve the use of vacuum. Moreover, the process is specifically designed for the production of polymers, which is not the purpose of this innovation. Polymers may form part of the substrates treated in the present invention, and some polymerization may also occur. However, the main purpose of this innovation is hydrolysis and steam explosion before subsequent processing. Examples of post-processing include, but are not limited to, dehydration, enzymatic treatment, anaerobic digestion, and fermentation.

US 2014120594 describes methods and means for hydrolyzing organic matter and focuses on the pre-treatment of wood raw materials to produce sugars that are fermented into alcohols. It is described that processes can have up to 8 washing stages and that flash steam can be used for preheating. Even if vacuum and sub-ambient pressure are mentioned, this is associated with evaporators in an attempt to concentrate the processed material and thus not for direct steam injection to preheat the raw material.

US 2018201517 describes methods and means for hydrolyzing organic matter and mentions that the hydrolyzed substrate can be passed through a recovery boiler to produce steam. The use of vacuum is not mentioned, and the processes described would require large heating surfaces due to poor heat transfer, scaling, and contamination from viscous hydrolyzed substrates. In addition, the processes described would not allow the production of steam at pressures below ambient pressure. In comparison, the present invention eliminates (or rather avoids) the problem of heat transfer and the risk of scale and fouling by using direct steam injection, and also allows the use of steam at pressures below ambient pressure to preheat the substrate.

US 2009032464 describes methods and means for hydrolyzing organic matter and mentions that flash vaporization can occur under vacuum conditions. However, in the processes described, hot steam enters a heat exchanger, which can possibly act as a condenser cooler. It also describes closed loops with a circulating cooling/heating medium for heat recovery for substrate preheating and drying purposes. In contrast, the present invention provides for the use of flash steam to preheat the feed by direct steam injection.

CA 2992657 describes a method for thermal hydrolysis of a substrate using at least three PTH reactors in parallel. The use of vacuum is not mentioned, and the processes described do not involve the use of the flash steam generated from any such process for direct steam injection to preheat the incoming feedstock in the pulper.

WO 2013/163998 A1 describes a method for continuously treating biological material at elevated pressure prior to anaerobic digestion, in which the biological material is transferred from a feeder to a reactor by pressure differential or gravity. The use of vacuum is not mentioned, and the processes described do not involve the use of the flash steam generated from any such process for direct injection to preheat the incoming feedstock into the pulper.

As can be seen from the above, the corresponding methods and installations known in the art are generally described as having one preheating stage and one flashing stage, and the substrate fed to the process is about 10-30°C, and most often about 15°C. Moreover, even if the prior art mentions multiple flash tanks as well as vacuum and sub-ambient pressure, this is due to condenser coolers or evaporators used in an attempt to concentrate the processed material, and thus rather than direct steam injection for pre heating the feed material into a preheating vessel maintained below ambient pressure. Thus, the prior art does not cover a method involving washing at a pressure below ambient pressure and using the resulting flash steam to directly inject steam to preheat the incoming feedstock into a preheat vessel maintained below ambient pressure to facilitate transfer of the flash steam. vaporization.

Unlike the prior art, the present invention is based on maintaining parts of the system below ambient pressure by removing non-condensable gases using a vacuum system and at least two successive pulpers and two flash tanks for staged preheating and pressure reduction, respectively, by flash vaporization below the liquid level in both pulpers. Alternatively, the system may have one fewer flash tanks than the number of slurries, but a minimum of two slurries and one flash tank if the reactors are allowed to depressurize by transferring hot steam from the top of the reactor to the slurry operating at the highest temperature until until these containers are in equilibrium before discharging the liquid contents into the evaporation tank. Thus, the present invention addresses the growing need to optimize energy consumption by achieving lower steam consumption compared to prior art processes, for example, as exemplified by the processes described in WO 2011/006854.

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Disclosure of the invention

As stated above, PTG units known from the prior art generally have one preheating tank and one flash tank, and the substrate supplied to the PTG is about 5-30°C, most often about 15°C. unless the preheating system is used to preheat the feed to temperatures exceeding 50°C. Thus, the instantly generated (hot) steam from the steam explosion in the evaporation tank usually heats the pulp to about 85-100°C, most often around 90°C.

In addition, the pulper is usually maintained at ambient pressure, so the feed temperature above approximately 23-25°C, a specific temperature dependent on the specific heat loss of the particular process, will result in boiling in the pulper and loss of thermal energy. Alternatively, both the pulper and flash tank are maintained at a pressure higher than ambient pressure to prevent boiling in the pulper, but this will also result in a loss of thermal energy due to higher temperatures in the treated substrate discharged from the PTG. In rare cases where large amounts of low-temperature heat are available that would otherwise be wasted, it may be advisable to use hot water to dilute biological wastes such as food waste before processing in the PTH. To prevent the pulper from boiling, a cooler can be installed on the evaporation tank to reduce the amount of steam returned to the pulper. This takes advantage of the lower substrate viscosity resulting from the higher substrate temperature prior to PTH treatment, while preventing pulp boiling.

In contrast, the present invention uses at least two preheat vessels in series and two flash vessels in series to stage preheat and depressurize, respectively. The optimal temperature and pressure in these vessels depend on the supply temperature to the steam generator. Thus, at feed temperatures below about 50 and 165°C in the reactor, a certain holding pressure and immersion of the steam evaporation tubes at about 3 m in the pulpers, the pressure in both the second evaporation vessel and the first pulper will be maintained below ambient with using a vacuum system connected to the first pulper. However, the present invention also contemplates processes in which the pressure in the first preheat vessels is below ambient pressure, while the pressure in the second preheat vessel is above ambient pressure. Thus, for example, the pressure in the second preheating vessel may be 1.1 bar abs, while the first preheating vessel may be 0.8 bar abs. Such a scenario would allow for feed temperatures slightly above 50° C. while maintaining proper use of the processes of the present invention. The vacuum system of the methods and apparatus of the present invention is therefore necessary to achieve a reduction in steam consumption through the sequential use of two preheat vessels and two flash vessels. When the substrate is within the normal temperature range (10-30° C.), the first preheating vessel is maintained at a pressure that is well below ambient pressure to allow low temperature steam to be transferred from the second flash vessels to the first preheating vessel. This is done by simultaneously adjusting the pressure in both preheat vessels to prevent boiling.

The flash steam generated is usually injected below the liquid level in both preheat vessels. This ensures that the vapor condenses into the liquid while other non-condensable gases pass through the liquid and enter the void space. Injection of hot steam through carefully designed injection points helps agitate the substrate during preheating. However, other methods of steam injection are possible, such as mechanical stirring. Such methods, for example, rely on the injection of steam into a pipeline followed by the use of mechanical mixers to ensure complete condensation of all steam. However, since the latter systems are known to be susceptible to leakage and wear, and given the presence of H ₂ S and thiols, the first method, based on the injection of flash steam below the liquid level in the pulpers, is preferred. Temperature and pressure sensors are used to calculate the partial pressure of steam and other non-condensable gases in the void space of preheat vessels. Input signals from these devices are used to control a valve that releases gases from the vessels. Gases from the second (hot) preheat vessel are diverted to a level below the liquid level in the first (cold) preheat vessel. This ensures that the steam carried with the process gas is used for preheating in the first vessel. The partial pressure of the non-condensable gases in the first preheat vessel will be maintained at the desired level. The desired partial pressure of non-condensable gases in the void space of the first heating vessel will depend on the specific substrate used and the feed temperature. At a lower total pressure in the preheating vessel, more instantaneous gas is released from the connected evaporation tank

- 3 044578 but steam is produced, while more heat is lost in the vacuum system as the ratio between steam and non-condensable gases increases. Measurements of the amount of non-condensable gases released from various feedstocks during PTG processing indicate that the optimal volume percentage of non-condensable gases will be between 10 and 35% in most cases. At this optimum, the derivative is zero for the function describing the heat loss in the vacuum system and the energy extracted from the connected evaporation tank. Models that simulate the process and operate with real-time data from the associated plant can be used to continuously adjust process setpoints to ensure optimal plant performance.

It is therefore an object of the present invention to provide processes and installations which, in the context of processes involving STG and steam explosion, allow optimization of steam consumption by achieving lower steam consumption compared to prior art processes.

Another object of the present invention is to provide methods and installations which, in the context of processes involving STG and steam explosion, allow optimization of steam consumption by achieving lower steam consumption compared to prior art methods and which are simple and easily integrated into existing wastewater treatment plants. water through modernization.

Finally, this is the purpose of the present invention by using the methods of the present invention as a complement by retrofitting any thermal hydrolysis process with cold feed and warm exhaust liquid. Thus, the methods of the present invention can be combined with processes described, for example, in WO 2011/006854 and WO 2014/123426, and other similar thermal hydrolysis processes to improve heat recovery and reduce overall energy consumption.

These and other problems are solved by the present invention.

Accordingly, the first aspect of the invention provides a method for hydrolyzing a liquid substrate having a solids content of from 2 to 30%, preferably from 14 to 20% and a temperature of from 10 to 30°C, intended for use in anaerobic fermentation, digestion or other process aimed at for the production or extraction of methane and other valuable substances, characterized in that:

a) said liquid substrate is transferred, preheated and mixed in a first pulper, which operates at a temperature of 40 to 90° C. and a pressure of 0.2 to 0.9 bar abs., by injecting flash steam from a downstream evaporator reservoir;

b) said pressure of 0.2 to 0.9 bar abs., at which said first pulper operates, is maintained by a vacuum system operating to maximize the condensation of any condensable vapors that do not condense when passing through said liquid substrate in said first pulper;

c) said vacuum system is also capable of maximizing the compression of any remaining non-condensable vapors and is connected to an injection unit that is capable of injecting said non-condensable vapors into a downstream anaerobic bioreactor, fermenter or any other process gas treatment system;

d) said preheated liquid substrate is transferred from said first pulper to a second pulper which is operated at a temperature of from 90 to 135° C. and a pressure of from 0.7 to 3.3 bar abs., wherein said liquid substrate is subjected to further mixing and preheating by injecting flash steam from a downstream evaporation tank;

e) said further preheated liquid substrate is transferred from said second pulper to one or more reactors, operating in parallel or in series, in which said liquid substrate is heated to temperatures ranging from 140 to 180° C. and at a pressure from 3.6 to 10 bar abs.;

f) said liquid substrate is transferred from said one or more reactors, operating in series or parallel, to a first flash tank operating at a temperature of 100 to 140° C. and a pressure of 1 to 3.6 bar abs., resulting in a pressure reduction , and from where the hot steam obtained as a result of the said pressure reduction is transferred to a second pulper operating at a temperature from 90 to 135 ° C and a pressure from 0.7 to 3.3 bar abs.;

g) said liquid material is transferred from said first flash tank to a second flash tank operating at a temperature of from 70 to 100° C. and a pressure of from 0.35 to 1 bar abs., resulting in a further reduction in pressure, and from where steam is instantly generated , obtained as a result of said further reduction in pressure in the second evaporation tank, is transferred to said first pulper, operating at a temperature of 40 to 90°C and at a pressure of 0.2 to 0.9 bar abs. through said vacuum system.

This method improves and/or optimizes steam consumption by achieving lower steam consumption compared to processes described in the prior art. What ka

- 4 044578 given the temperatures and pressures specified in points a), b), d), e) and f) above, one skilled in the art will readily understand that in an ideal scenario the partial pressure of steam at, for example, 40, 90 and 140°C will be be 0.07, 0.7 and 3.6 bar abs. respectively. Likewise, in an ideal scenario, the steam partial pressure is 3.3 bar abs. at a temperature of 137, not 135°C. In other words, the indicated temperatures and pressures do not correspond to the steam saturation line. However, since the processes and methods of the present invention in many embodiments will also involve the presence of other non-condensable gases, the pressures and temperatures specified in paragraphs a), b), d), e) and f) above are rounded to a certain extent to also take into account the possible presence of any such other non-condensable gases.

In an embodiment of the first aspect of the invention, said method is further characterized in that the connected desuperheater operates to remove any vapors that condense below the operating temperature of said first pulper, and that said vacuum system operates to maximize the condensation of any condensable vapors that do not condense when passing through said liquid. the substrate in said first pulper or in said connected desuperheater.

This embodiment further increases and/or optimizes steam consumption by achieving lower steam consumption compared to prior art processes

In a second aspect of the invention, there is provided an apparatus for hydrolyzing a liquid substrate having a solids content in the range of 2 to 30%, preferably 14 to 20%, and a temperature of 10 to 30° C., intended for use in anaerobic fermentation, digestion or other a process aimed at producing or extracting methane or other valuable substances, wherein said installation includes:

a) a first pulper for mixing and preheating said liquid substrate, into which said liquid substrate is transferred and which operates at a temperature of 40°C to 90°C and a pressure of 0.2 to 0.9 bar abs. by injecting flash vapor from a downstream evaporation tank;

b) a vacuum system for maintaining said pressure of 0.2 to 0.9 bar abs. at which said first pulper is operated, the vacuum system of which is operated to maximize the condensation of any condensable vapors that do not condense when passing through said liquid substrate in said first pulper, and to maximize compression of any remaining non-condensable vapors and remaining condensable vapors;

c) an injection unit that is capable of injecting said non-condensable vapors into a downstream anaerobic bioreactor or process gas treatment device connected to said vacuum system;

d) a second pulper, which operates at a temperature of from 90 to 135°C and a pressure of from 0.7 to 3.3 bar abs., into which said preheated liquid substrate is transferred from said first pulper and in which said liquid substrate is subjected to further mixing and preheating by injecting flash steam from a downstream flash tank;

e) one or more reactors, operating in parallel or in series, into which said additional preheated liquid substrate is transferred from said second pulper and in which said liquid substrate is heated to temperatures ranging from 140 to 180°C and at a pressure from 3.6 to 10 bar abs.;

f) a first flash tank into which said liquid substrate is transferred from said one or more reactors operating in series or parallel, said first flash tank operating at a temperature of from 100 to 140° C. and a pressure from 1 to 3.6 bar abs., whereby a reduction in pressure occurs, and from which the instantly generated steam resulting from said reduction in pressure is transferred to said second pulper operating at a temperature of from 90 to 135° C. and a pressure from 0.7 to 3.3 bar abs.;

g) a second flash tank into which said liquid material is transferred from said first flash tank, wherein said second flash tank is operated at a temperature of from 70 to 100° C. and a pressure of from 0.3 to 1 bar abs., whereby further pressure reduction, and from which the instantly generated steam resulting from said further reduction in pressure in the second evaporation tank is transferred to said first pulper operating at a temperature of from 40 to 90° C. and a pressure of from 0.2 to 0.9 bar abs. through said vacuum system.

This installation increases and/or optimizes steam consumption by achieving lower steam consumption compared to processes described in the prior art. Regarding the temperatures and pressures specified in points a), b), d), e) and f) above, one skilled in the art will readily understand that in an ideal scenario the partial pressure of steam at, for example, 40, 90 and 140°C will be 0 .07, 0.7 and 3.6 bar abs. respectively. Likewise, in an ideal scenario, the steam partial pressure is 3.3 bar abs. at a temperature of 137, not 135°C. In other words, the indicated temperatures and pressures do not correspond to the steam saturation line. However, since the processes and methods of the present invention in many embodiments will also involve the presence of other non-condensable gases, the pressures and temperatures specified in paragraphs a), b), d), e) and f) above are rounded to a certain extent to also take into account the possible presence of any such other non-condensable gases.

In an embodiment of the second aspect of the invention, the installation further comprises a connected vapor cooler operative to remove any vapors condensing below the operating temperature of said first pulper, said vacuum system having the following functions:

maximizing the condensation of any condensable vapors that do not condense upon passage through said liquid substrate in said first pulper or in said connected desuperheater operating to remove any vapors condensing below the operating temperature of said first pulper; and maximum compression of any remaining non-condensable vapors.

This embodiment further increases and/or optimizes steam consumption by achieving lower steam consumption compared to prior art processes.

Any of the embodiments of the first aspect of the invention may be combined with any of the embodiments of the second aspect.

In a third aspect of the invention, a method is provided for upgrading an existing thermal hydrolysis plant for a liquid substrate, with a solids content in the range of 2 to 30%, preferably 14 to 20% and a temperature of 10 to 30°C, intended for use in anaerobic fermentation, digestion or other process designed to create or extract methane and other valuable substances, whereby the upgrade ensures that the said plant includes at a minimum the following components:

a) a first pulper for mixing and preheating said liquid substrate, into which said liquid substrate is transferred and which operates at a temperature of 40 to 90° C. and a pressure of 0.2 to 0.9 bar abs. by injecting flash vapor from a downstream evaporation tank;

b) a vacuum system for maintaining said pressure of 0.2 to 0.9 bar abs at which said first pulper is operated, the vacuum system being operated to maximize the condensation of any condensable vapors that do not condense when passing through said liquid substrate in said the first pulper, and to maximize the compression of any remaining non-condensable vapors;

c) an injection unit that is capable of injecting said non-condensable vapors into a downstream anaerobic bioreactor or process gas treatment device connected to said vacuum system;

d) a second pulper, which operates at a temperature of from 90 to 135°C and a pressure of from 0.7 to 3.3 bar abs., into which said preheated liquid substrate is transferred from said first pulper and in which said liquid substrate is subjected to further mixing and preheating by injecting flash steam from a downstream flash tank;

e) one or more reactors, operating in parallel or in series, into which said additional preheated liquid substrate is transferred from said second pulper, and in which said liquid substrate is heated to temperatures ranging from 140 to 180° C. and at a pressure from 3.6 up to 10 bar abs.;

f) a first flash tank into which said liquid substrate is transferred from said one or more reactors operating in series or parallel, said first flash tank operating at a temperature of from 100 to 140° C. and a pressure from 1 to 3.6 bar abs., whereby a reduction in pressure occurs, and from which the instantly generated steam resulting from said reduction in pressure is transferred to said second pulper operating at a temperature of from 90 to 135° C. and a pressure from 0.7 to 3.3 bar abs.;

g) a second flash tank into which said liquid material is transferred from said first flash tank, wherein said second flash tank is operated at a temperature of from 70 to 100° C. and a pressure of from 0.3 to 1 bar abs., whereby further pressure reduction, and from which the instantly generated steam resulting from said further reduction in pressure in the second evaporation tank is transferred to said first pulper operating at a temperature of from 40 to 90° C. and a pressure of from 0.2 to 0.9 bar abs. through said vacuum system.

This retrofit method increases and/or optimizes steam consumption by achieving lower steam consumption compared to prior art processes. Regarding the temperatures and pressures specified in points a), b), d), e) and f) above, one skilled in the art will readily understand that in an ideal scenario the partial pressure of steam at, for example, 40, 90 and 140°C will be 0 .07, 0.7 and 3.6 bar abs. respectively. Likewise, in an ideal scenario, the steam partial pressure is 3.3 bar abs.

- 6 044578 at a temperature of 137, not 135°C. In other words, the indicated temperatures and pressures do not correspond to the steam saturation line. However, since the processes and methods of the present invention in many embodiments will also involve the presence of other non-condensable gases, the pressures and temperatures specified in paragraphs a), b), d), e) and f) above are rounded to a certain extent to also take into account the possible presence of any such other non-condensable gases.

In an embodiment of the third aspect of the invention, the retrofit method further includes ensuring that said installation includes a connected vapor cooler operative to remove any vapors condensing below the operating temperature of said first pulper, and that said vacuum system performs the following functions:

to maximize the condensation of any condensable vapors that do not condense upon passage through said liquid substrate in said first pulper or in said connected desuperheater operating to remove any vapors that condense below the operating temperature of said first pulper; and maximize compression of any remaining non-condensable vapors.

This upgrade method further increases and/or optimizes steam consumption by achieving lower steam consumption compared to prior art processes.

Any of the embodiments of the first aspect and the second aspect of the invention may be combined with any of the embodiments of the third aspect.

Brief description of drawings

In fig. 1 and 2 show two different embodiments of an installation in accordance with the present invention for carrying out the method in accordance with the present invention.

In fig. 3 and 4 show two different, particularly preferred embodiments of the installation in accordance with the present invention for carrying out the method in accordance with the present invention, which uses barometric pumping.

Detailed Description of the Invention

The present invention will be described in more detail below with reference to the nomenclature also used in the accompanying FIGS. 1-4.

The present invention relates to methods and installations that use thermal hydrolysis (TTH) processes in combination with steam explosion, in which pulpers and flash tanks are used for preheating and pressure reduction, respectively. The present invention also relates to methods for upgrading existing plants that use thermal hydrolysis processes.

As noted above, the present invention uses a vacuum in combination with at least two pulpers and two flash tanks in series to stage preheat and depressurize, respectively.

The optimal temperature and pressure in the individual vessels in the method or installation in accordance with the present invention will depend on the temperature at the supply to the PTG. When the supply temperature is below about 50°C, the pressure in the second flash tank and first pulper will be maintained below ambient temperature by a vacuum system connected to the first pulper. Typically, the PTG supply temperature is approximately 15°C, and the normal range is 10 to 30°C, such as 15 to 25°C. This makes a vacuum system necessary to reduce steam consumption by using two pulpers and two evaporation tanks. If the substrate is within the normal temperature range, the first pulper is maintained at a pressure that is well below ambient pressure to allow low temperature steam to be transferred from the second flash tank to the first pulper. This is done by simultaneously adjusting the pressure in both pulpers to prevent boiling.

The instantaneously generated steam is preferably injected below the liquid level into both pulpers. This ensures that the vapor condenses into the liquid while other non-condensable gases pass through the liquid and enter the void space. Temperature and pressure sensors are used to calculate the partial pressure of steam and other non-condensable gases in the empty space of the pulpers. Input signals from these devices are used to control a valve that releases gases from the containers. Gases from the second (relatively hot) pulper are released to a level below the liquid level in the first (relatively cold) pulper. This ensures that the steam carried with the process gas is used for preheating in the first pulper. The partial pressure of non-condensable gases in the first pulper will be maintained at the desired level. The optimal partial pressure of non-condensable gases in the void space of the first pulper will depend on the specific substrate used.

Typically, the temperature of the liquid substrate supplied to the first pulper in the method or installation according to the present invention will be in the range from 10 to 30°C, for example 15-25°C, for example 20-25°C, and the hydrolysis temperature used in one or more reactors operating in parallel or in series downstream of the second pulper will be in the range of 140 to 180°C, for example 155-165°C, approximately 160°C depending on the temperature and feedstock.

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As can be seen from the above, a particularly preferred embodiment of the present invention is to provide methods and installations (new or modified) based on a two-pulper, two-evaporation tank system in which the first pulper is connected to a vacuum system. One skilled in the art will, however, readily appreciate that certain other embodiments having the same technical features can be easily achieved by minor changes in the preferred methods and apparatus (new or modified) of the present invention, i.e. those based on a system with two pulpers and two evaporation tanks, in which the first pulper is connected to a vacuum system. Some of these additional embodiments, also related to the present invention, will be explained in some detail below.

The first additional embodiment is a system using two pulpers, but only one flash tank to achieve equally low steam flow, as described in the preferred embodiment above, using a two pulper and two flash tank system, in which the first pulper is connected to a vacuum system. This requires that the first pulper be connected to the vacuum system and that a line connecting the headspace of the reactor(s) to the second pulper be used to depressurize the reactor(s) until the reactor(s) and the second pulper are in equilibrium before transferring the liquid substrate from the reactor(s) to the evaporation tank. In such a system it is possible to operate with one less number of flash tanks than the number of pulpers, since the reactor will play a similar role as the first flash tank in a system with an even number of pulpers and flash tanks, where the liquid substrate is transferred from the reactor(s) at maximum pressure. In such a system, the liquid substrate in the reactor(s) will boil as steam is transferred from the reactor to the preheated substrate in the pulper. Thus, to prevent liquid from entering a flash steam system, it is important that the ullage volume of the reactor(s) in such a system is large and that the steam transfer rate is low. The large ullage volume required results in less efficient use of the available reactor(s) volume, and low steam transfer rates increase the cycle time for each reactor. Both of these effects reduce system throughput. Because of this, it is more efficient to use an even number of pulpers and evaporation tanks and to unload the substrate from the reactors at maximum pressure.

Increasing the number of flash stages will reduce the overall steam consumption. In a process based on a) a feed with a solids content of 15°C and 16.5%, b) all injection points of flash steam immersed 2 m below the liquid level, c) a reactor temperature of 165°C, d) non-condensable gases 0.1 bar in the first pulper, and c) no heat loss to the environment, the total steam consumption will be approximately 530 kg of steam per tonne of solids processed if three flash stages are used. In comparison, processes with two flash stages or one flash stage consume 640 and 900 kg of saturated steam at 14 bar abs. per ton of solids processed, respectively. For a process under conditions similar to those described above, the temperature in the first pulper will be approximately 43°C if three flash stages are used, and 64°C if two flash stages are used.

The viscosity of most liquid substrates decreases with increasing temperature and increases with increasing substance content. For example, for substrates such as sewage treatment sludge, viscosity typically decreases significantly when the material is heated from ambient temperature to approximately 60°C. Viscosity continues to decrease when heated to higher temperatures, but to a slightly lesser extent. When the first pulper temperature is low, it may be necessary to run the process with a lower feed content to maintain viscosity at a controlled level. Under similar process conditions described above, processes with two or three flash stages will have the same steam consumption per ton of solids processed if the feed solids content is 13.8 and 16.5%, respectively. Because of this, the benefit of using three flash stages may be lost if it becomes necessary to reduce the solids content of the feedstock to maintain viscosity at a manageable level.

Additionally, as is known to those skilled in the art, it is possible to preheat the incoming liquid substrate using hot dilution water, heat exchangers, or the like. In such situations, i.e. If both the temperature of the liquid substrate feed to the first pulper and the hydrolysis temperature employed in one or more reactors operating in parallel or in series downstream of the second pulper are sufficiently high, the operating pressure of the first pulper will typically be greater than 1 bar abs. One example of this would be a process in which a liquid substrate is preheated to a temperature of 40°C with a small amount of non-condensable gases and where hydrolysis is carried out at a temperature of 220°C (and 23.2 bar abs.). In this case, the first pulper will usually operate at

- 8 044578 temperature 115°C and pressure about 1.8 bar abs. Also in an embodiment based on such operating conditions, it will be immediately apparent to one skilled in the art that at least some of the benefits of the present invention will still be obtained. Thus, the present invention will also relate to methods and/or installations using two pulpers and two flash tanks and feedstocks in series, with temperatures high enough to cause the first pulper to operate at a pressure above ambient pressure. Another example of such a process and/or plant would be a process/plant based on a feed having a temperature of about 65-70° C. and a reactor holding pressure of about 7 bar. Additionally, in such a scenario, it may be beneficial to use three pulpers and three flash tanks in series rather than two pulpers and flash tanks each, since this would also allow the use of steam below ambient pressure to preheat any incoming liquid substrate in such a situation. The present invention will also relate to any such methods and/or installations.

However, in most situations, it will not be appropriate to use more than two pulpers and two flash tanks in series in a process or plant according to the present invention, since the temperature of the liquid substrate and the hydrolysis temperature will be below 40 and 180° C., respectively.

In prior art processes, a conventional vacuum cooler would use a vacuum compressor to create a vacuum after the condensing cooler. The condenser cooler then removes the condensable vapors to allow the vacuum compressor to operate on the remaining gases, often called non-condensable gases. In the method or installation according to the present invention, the vacuum compressor does not have to handle all the vapors, but only deals with non-condensable gases and therefore has to do a minimum of work. The condensation cooler for use in the method or installation according to the present invention can be implemented in various ways, for example as a plate heat exchanger, a vertical or horizontal tubular heat exchanger, a film type reactor or other solutions well known in condenser technology, such as vacuum evaporators. What these solutions have in common is that the refrigerant must cool the heating surfaces in order to indirectly cool and condense the vapors. Thus, the present invention largely eliminates the need for a condensation cooler by using one or more additional pulpers to provide direct contact between the cold substrate and the condensed vapor. Thanks to this condensation, direct contact within the pulper preheats the cold substrate without any heating surfaces, which are known to be susceptible to scale formation. In addition, the present invention avoids problems with heat transfer degradation due to scale formation in heat exchangers. In addition, heat transfer problems are minimized since there are no thermal surfaces. In addition, the present invention minimizes the need for traditional coolers on warm hydrolyzed substrates prior to a fermentation process, such as anaerobic digestion, to produce methane.

An important aspect of the present invention is heat recovery at temperatures that are lower than the conditions under which existing steam generator installations operate. It is essential that all steam returned to the preheat vessels condenses into the substrate, which must be preheated. This becomes especially difficult in the first pulper, operating at the lowest temperature, since viscosity increases with decreasing temperature. However, so-called steam tunneling, which is characterized by steam passing from the injection point through the surface of the liquid, can be avoided by ensuring that the substrate is effectively mixed in the preheating vessel. Vapor density decreases with decreasing pressure. As a result, the volume of steam supplied to the first preheat vessel will be large in most scenarios. This effect can be engineered and used to agitate the substrate in a preheat vessel by injecting steam at carefully designed injection points. This makes it possible to process highly viscous substrates with high solids content, for example above 10%, despite lower temperatures compared to existing thermal hydrolysis processes. Effective mixing is important not only to ensure condensation of all steam returned to the preheat vessels, but also to homogenize the substrate before further processing. Thus, homogenization of the substrate before processing in reactors also ensures more complete hydrolysis. Condensation of H2O vapor in a cold substrate can cause strong vibrations due to explosions. The strength of the explosions depends on the pressure and temperature in the vapor phase, as well as the size of the vapor bubbles and the temperature of the substrate. Large temperature differences and pressure differences cause the strongest vibrations. A common way to reduce the temperature and pressure difference between steam and liquid would be to reduce the pressure in the vapor using a pressure reducing mechanism such as a pressure reducing valve, control valve, or any other type of restriction that causes a pressure drop in the steam line. Vapors that have been discharged in the evaporation tank(s) will not be pure water vapor and contain components known to cause scaling and plugging under such restrictions. Instead, in the method or installation according to

- 9 044578 The present invention uses a vacuum compressor to reduce pressure and create a vacuum after removing H2O vapors and contaminants by condensation and injection through a pulper in direct contact with a cold substrate with a pH in the range of 3.5-8.5. The method or installation according to the present invention thus reduces the steam pressure without reducing the pressure in the system of mechanisms occurring in the vapor phase and to such an extent that the pulper(s) can operate at relatively low temperatures, typically 40-85°C, more typically 50-70°C, and even typically in the range of 58-68°C, with a minimum of vibrations and providing a greater degree of heat recovery. One example of a particular useful embodiment of a method or installation according to the present invention may be the treatment of an alkaline substrate with a pH in the range of 7.0-8.5. Another example of a particular useful embodiment of the method or installation according to the present invention would be the treatment of a substrate with a pH in the range of 3.5-7.0.

For most suitable substrates, viscosity increases with increasing solids concentration, while viscosity decreases with increasing temperature. The viscosity of untreated substrates, such as sludge, typically decreases significantly when heated from ambient temperature to approximately 60-65°C. Heating to even higher temperatures will further reduce the viscosity. The present invention allows operation at high solids concentrations. As those skilled in the art know, high solids concentrations alone will reduce steam consumption by approximately 10-30% depending on substrate characteristics. In addition, the method or installation in accordance with the present invention with two pulpers and two evaporation tanks reduces the total steam consumption compared to prior art STG by 25-40% depending on the temperature at the supply to the STG.

Another preferred embodiment of the present invention is for the pulper(s) to include a steam injection system that provides high intensity mixing by using bulk vapor under vacuum conditions. This provides an additional advantage of the present invention in that the second pulper(s) will receive preheated feedstock at a temperature of approximately 50-80°C, more specifically 60-70°C, this will reduce mixing requirements and result in a reduced design volume compared to pulpers in conventional PTG systems. In addition, the need for mechanical mixing as such would be reduced. Regardless of which mixing means are used in a particular embodiment, improved mixing can be achieved through optimized nozzle orientation and additional pumping. In a typical scenario, the first pulper typically receives raw material at a temperature of about 15°C, which is heated to approximately 65°C. Then the second pulper receives raw materials at a temperature of about 65°C, which is then further heated to a temperature above 100°C

Another particularly preferred embodiment of the method or installation in accordance with the present invention involves the use of pressure differences to move liquid substrates both into the first pulper and between various downstream vessels, i.e. so-called barometric pumping. In some embodiments, barometric pumping will be used during all steps involving the transfer of liquid substrate into the first pulper and between various downstream vessels. In other embodiments, barometric pumping will be used only during certain steps involving the transfer of liquid substrate into the first pulper and/or between various downstream vessels. In the latter case, the transfer of the liquid substrate can thus also be partially carried out by conventional pumps (centrifugal or cavity pumps with progressive speed).

In fig. 3 and 4 show two such different, particularly preferred embodiments of the system in accordance with the present invention, which use barometric pumping.

In the context of the method or installation according to the present invention, barometric pumping is understood to mean a first pressurized container used for pumping a substrate by means of a pressure difference. The first vessel is filled with the substrate to be pumped and then pressurized with gas. This will cause the substrate to be forced out of the first vessel through a conduit at the bottom of the vessel if the conduit is connected to a second vessel having a pressure lower than the pressure of the first vessel. In the method or apparatus of the present invention, such a design will provide certain advantages over mechanical pumping.

The general benefits of barometric pumping are as follows:

a) there is no need for mechanical energy;

b) no moving parts come into contact with the substrate, resulting in less wear and reduced risk of leakage through seals, etc.;

c) Relatively high pressures (above 5 bar abs.) can be easily achieved, allowing higher flow rates.

Additional benefits of barometric pumping regardless of PTH configuration will include:

a) In periodic PTG, the substrate moves intermittently between vessels under pressure. By-

- 10 044578 There is no disadvantage to this in that barometric pumping usually cannot provide a constant flow;

b) The volume of the pressure vessel used for barometric pumping can be equal to the desired reactor fill volume, and thus a known volume is dosed into the reactor. This replaces PTG instrumentation to ensure correct reactor fill volume;

c) The steam used to pressurize the pressure vessel used for barometric pumping replaces the steam in the downstream reactor(s). The consequence of this is that barometric pumping upstream of the downstream reactor(s) does not affect the overall steam consumption of the STG process;

d) this is beneficial for large pulp volumes to even out temperature fluctuations. The volume of the pressure vessel used for barometric pumping can be considered as part of the volume of the pulper. The advantage of larger pulpers is more stable temperature and increased residence time in the pulper. The viscosity of substrates such as sludge decreases with increasing pulse residence time;

e) the productivity of STG plants is increased because the reactor can be filled faster than is possible with mechanical pumps used in existing STG processes;

f) higher flow rates that can be achieved with barometric pumping, which allows better mixing of the contents of the pulpers. With the help of barometric monteju it is possible to achieve powerful pulsating mixing, which ensures effective mixing and equalization of temperature in the pulper;

g) PTG processes are performed with liquids whose temperature is close to the boiling point. Thus, the formation of voids on the suction side of pumps is a complex problem. Barometric pumping does not have the same voiding problems associated with mechanical pumps;

h) When a pressure vessel used for barometric pumping is briefly connected to a vacuum system, the pressure vessel will fill more quickly.

The benefits of barometric pumping specifically for dual-pulp, dual-evaporation tank PTG processes include:

a) It is difficult to find gaskets around the rotation axes for pumps operating alternately at both lower and higher ambient pressures at the center of the boiling point. For operation with a barometric pump, the seal quality requirements are less stringent, so difficult operating conditions do not affect the overall cost of the system to the same extent as in the case of a mechanical pump;

b) when using two pulpers, the temperature in the first pulper is low. At low temperature (first pulper) the viscosity is higher and a barometric pumping solution is better suited for pumping highly viscous substrates such as sludge;

c) in a system with two pulpers the temperature is higher than in a conventional system. It is difficult to find elastomers (used in positive displacement pumps) that can withstand the high temperatures in the second pulper (110 to 130°C). With barometric pumping this is not a problem. This would have the added benefit of reducing the need for reactor feed pumps.

Thus, the present invention provides a method for continuously or batch hydrolyzing a material by using staged preheating and cooling using flash steam injection and facilitating flash steam generation, respectively. In addition, at least one preheating vessel and at least one temperature reduction vessel are maintained below ambient pressure by means of connecting piping. This allows hot steam to be transferred at temperatures below 100°C to preheat the incoming material into the preheating tank. In a particularly preferred embodiment of the method or installation according to the present invention, the transfer of the liquid substrate is achieved by barometric pumping.

Briefly, the method according to the present invention can be characterized as follows:

a) the liquid substrate is transferred and preheated by injecting flash steam into a pulper maintained below ambient pressure by a vacuum system;

b) the vacuum system consists of any type of vacuum compressor or vacuum pump operating on vapors that do not condense when passing through the liquids in the preheat pulpers, and a vapor cooler designed to remove vapors below the temperature of the pulper;

c) The vacuum system also compresses non-condensable vapors and is connected to a device that injects non-condensable gases into downstream anaerobic digestion units.

- 11 044578 fermentation or other biological treatment;

d) transferring the substrate to a second preheated pulper, which is maintained at a pressure above ambient pressure;

e) one or more reactors in which the substrate is processed at temperatures ranging from

140 to 220°C.

In batch plants, the reactors may be periodically placed under vacuum by a line connecting the reactors to a preheat slurry, which is maintained below ambient pressure. The second preheated pulper operates at a higher pressure than ambient pressure. Higher pressure provides higher temperature inside the pulper, which leads to lower viscosity. The resulting pressure difference at an acceptable viscosity can be used to transfer liquid material into reactors without the use of pumps. However, it may be advisable to use pumps to eliminate friction losses in pipelines if the viscosity of the substrate is too high. Instead of mechanical pumps, it is preferable to use barometric pumping to circulate the pulper and transfer the substrate to the reactor;

f) After processing in the reactor, the substrate is transferred to the first of two evaporation tanks to reduce the pressure. The flash steam resulting from the reduction in pressure is transferred to the second of two preheated pulpers, which are maintained at atmospheric or higher pressure;

g) the substrate from the first pressure reduction flash tank is transferred to the second pressure reduction flash tank, which is maintained at sub-atmospheric pressure. The flash steam resulting from the depressurization of the second flash tank is introduced into the first preheated pulper, which is maintained at subatmospheric pressure by vacuum equipment.

Conventional equipment can be used to apply a vacuum to non-condensable gases and vapors to facilitate the transfer of flash steam at sub-atmospheric pressure to the preheater during the thermal hydrolysis process.

A low pressure preheat pulper vacuum system can be connected to a device that injects non-condensable gases into an anaerobic digestion or other process gas treatment unit.

In another preferred embodiment of the method or installation according to the present invention, the low pressure volumetric vapor bubbles are at sub-atmospheric pressure and are reduced in size in the range of 1-50 mm, preferably less than 25 mm, more preferably less than 10 mm, to minimize vibrations and maximize heat recovery and stirring.

In another preferred embodiment of the method or installation according to the present invention, both preheating pulpers can be equipped with pumps or agitators for further mixing in case of extremely high viscosity.

In yet another preferred embodiment of the method or installation according to the present invention, both heating pulpers are provided with a substrate outlet at a level above the injection point of the recirculated flash hot steam from the first or second flash tank to reduce the pressure.

In yet another preferred embodiment of the method or installation in accordance with the present invention, the feed into the preheated pulper is carried out either at the bottom of the preheated pulper or above the liquid level in the preheated pulper in combination with a substrate size reduction and distribution system, which increases the specific surface area of the cold substrate, or below the liquid level in the preheating pulper in combination with a substrate size reduction and distribution system that increases the specific surface area of the cold substrate.

In another preferred embodiment of the method or installation in accordance with the present invention, the content of inert gases inside the pulpers is controlled by a control system by monitoring temperature, pressure and opening of valves while calculating a false pressure, which means deviation from the steam saturation line.

In yet another preferred embodiment of the method or apparatus according to the present invention, a thermal mixing and transfer unit is used to transfer the substrate between two pulpers, pulper a and pulper e, and may also be used to transfer from pulper e to the downstream reactor(s). ).

In a particularly preferred embodiment of the method or installation in accordance with the present invention, such a thermal mixing and transfer unit may include:

A) a vessel having a filling volume used to transfer the substrate into the reactor and fill it;

B) steam added to the top of the vessel to increase pressure;

C) valves to shut off the supply from the pulper;

- 12 044578

D) valves for distributing the discharged material to the next vessel;

E) valves for distributing the discharged material along the bottom of the pulper for mixing in the pulper;

F) means for transferring the warm substrate from a high level of the pulper above the 50% fill level and more preferably above the 60% fill level and even more preferably above the 70% fill level to the cooler substrate at the bottom of the pulper to mix the substrate without the use of pumps.

The reactors of the method or installation in accordance with the present invention can be arranged in series or in parallel.

In a particularly preferred embodiment of the present invention, a vacuum is created on the non-condensable gases after all condensable gases are first condensed in a high temperature pulper to preheat the substrate, then in a low temperature pulper to preheat the lower temperature substrate, and (optionally) in a vapor-gas cooler to minimizing volume to create a vacuum and compress non-condensable gases.

Example 1.

An apparatus in accordance with a preferred embodiment of the present invention comprises at least two vacuum vessels, one upstream in the PTG (pulp 1 (a)) and one located downstream in the PTG (evaporator tank 2 (b)). The two vessels are connected by a pipe from the top of the evaporation tank 2 (b) through tubes distributed in the pulper 1 (a). A vacuum compressor (c), such as a hydraulic piston compressor, connected to the void space of the pulper 1 (a) will create a vacuum in the void space of the pulper. The work done by the vacuum compressor will be done on gases that do not condense in the pulper 1 (a) and the subsequent condenser cooler (d). Flash vapor from flash tank 2 (b) will pass through pulper 1 (a) and condense as it enters the liquid phase in pulper 1 (a) through flash tubes. The partial pressure of steam in pulper 1 will be about 0.2 bar abs., which means a boiling point of about 60°C, while the total pressure may be slightly higher due to the presence of other non-condensable gases. Some steam will follow the non-condensable gases out of pulper 1 (a) and will condense in a small condenser cooler before the vacuum compressor (c). This minimizes the required work of the vacuum compressor (c), since it only needs to handle non-condensable gases.

Two vessels (pulper 1 and evaporation tank 2) can be built on top of each other to achieve a compact and economical solution, although this is not absolutely necessary. In addition, due to the stacking, important process advantages are provided, such as:

the raised evaporation tank 2 provides increased pressure at the inlet to the hydrolysis reactor feed pumps (o), located at floor level;

alternatively, the raised pulper 1 provides increased pressure at the inlet of the pumping system designed to transfer the substrate from the pulper 1 to the pulper 2;

short distances and lower pressure drop in connecting pipelines.

In fig. 1 and 2 show two different technical solutions with different degrees of integration with the thermal hydrolysis process. Fig. 2 allows the use of vacuum to move the substrate between vessels and thus eliminate pumps. If pumps are excluded, careful monitoring of pressure drop will be required. In addition, steam tubes must be optimized to create high-mixing pulpers. This applies to both pulper 1 (a) and pulper 2 (e). The reactor feed pumps (n) can also be eliminated. Filling of the reactors can also be avoided by connecting the reactor void space to a vacuum compressor (c) via a valve (t) to minimize the pressure in the reactors during substrate filling.

The rheology of the substrate is affected by the temperature of the substrate. In general, viscosity decreases with increasing temperature. A consequence of the operation of the installation in accordance with the present invention is that high-temperature material is supplied to the pulper 2 (e). The result of increasing the feed temperature in pulper 2 will be an increase in the temperature inside pulper 2 (e) during operation. At a higher temperature, the liquid will move more easily between vessels and the feed time into the reactor (g) may be reduced. Since the feed time to the reactor is a significant part of the total cycle time of the PTG, the overall productivity of the PTG will increase equivalently. Another advantage of operating at elevated temperatures is easier mixing in pulper 2 (e).

Pulper 2 (e) is a continuous feed tank with intermittent unloading when fed into reactors (g). Intermittent discharge makes it necessary to take into account some level changes in pulper 2 (e) during the cycle.

Flash tank 1 (j) will operate at a slightly higher pressure than pulper 2 (e). The pressure difference will mainly be determined by the height of the evaporation tubes

- 13 044578 steam (q) in pulper 2 (e) and the pressure drop in the flash steam line (ac) and tubes for flash steam (q).

Flash tank 2 (b) will operate at a slightly higher pressure than pulper 1 (a). The pressure difference will mainly be determined by the height of the flash tubes (s) in pulper 1 (a) and the pressure drop in the flash line (ab) and the flash tubes (s).

Example 2.

In the present example, the additional pulper and flash tank required in the method or installation according to the present invention will be referred to as pulper (a) and flash tank (b), respectively. The PTG installation of the invention will also include a pulper (e) and an evaporation tank (j), which are similar to the vessels in existing PTG installations. The main process flows are shown below.

In fig. 1 and 2 show two different embodiments of a system in accordance with the present invention.

Pulper (a).

All lines for venting non-condensable gases from pulper e will be below the liquid level in pulper (a). The pulper(s) will be equipped with a vacuum pump and will have the lowest pressure in the system. The temperature and pressure in the void space of the pulper (a) will be measured to calculate the partial pressure of steam and other gases. The purpose is to control the overall pressure in the pulper (a) to prevent boiling of the substrate while keeping the concentration of non-condensable gases low. There will be a line from the flash tank void (b) to below the liquid level in the pulper (a). This is done to transfer the instantly generated steam to preheat the substrate in the pulper (a). During normal operation and when the pulper supply temperature is below about 50°C, both the pulper (a) and the flash tank (b) are at subatmospheric pressure. The preheated substrate will be transferred from pulper (a) to pulper (e). For low viscosity materials, pumps can be used. However, the risk of cavitation is significant, and the lifting height of the pumps is critical. The problem becomes significant for substrates with high viscosity. The invention includes a heat transfer and mixing unit that will replace pumps. However, any means for transferring the substrate from pulper (a) to pulper (e) can be used without any negative impact on the entire process.

The heat transfer and mixing unit will be a container into which the hot substrate flows from the pulper (a). Since cold substrate has a higher specific gravity than warm substrate, the warmest substrate will be at the top of the pulpers. For this reason, the outlet from the pulper (a) to the heat transfer and mixing unit is at a high level in the pulper just below the maximum liquid level. The warm substrate flows into the heat transfer and mixing unit. Once the stirring block is full, the container can be closed and steam added to the top to increase the pressure. Once pressurized, the warm substrate can be transferred to the selected reactor. The warm substrate can also be returned back to the pulper(s) for mixing.

The heat transfer and mixing unit may have a second input from a lower level of the pulper to provide filling even if the pulper is not full, and to provide mixing at a lower level without filling the heat transfer and mixing unit to the maximum level.

The heat transfer and mixing unit has a known volume that will be used to control the flow when filling the reactors by dosing into the reactor.

Pulper (e).

All lines for venting non-condensable gases from the reactors will pass below the liquid level in the pulper (e). In the pulper (e), the substrate comes from the pulper (a), and the instantly formed steam comes from the evaporation tank (j). The substrate, preheated in the pulper (e), will be fed into the reactors. The temperature and pressure in the pulp void (e) will be measured to calculate the partial pressure of steam and other gases. A line is installed to vent gases from the empty space of the pulper e to a level below the liquid level in the pulper (a). The goal is to control the overall pressure in the pulper (e) to prevent boiling while keeping the concentration of other gases low. The temperature and pressure in the pulper (e) will depend on the temperature of the supply to the pulper (a) and the selected reactor temperature. However, during normal operation the temperature will be well above 100°C and the overall pressure will be above atmospheric.

In a batch process, the total pressure in the reactors can be reduced to below ambient pressure before the substrate is supplied from the pulper (e). This is done by using vent lines from the reactor headspace to a level below the liquid level in the pulper (a). The resulting pressure difference between the pulper (e) and the reactors can be used to transfer liquid substrate to the reactors without the use of pumps. If necessary, and the reactor cycle time allows it, steam can be injected into the empty space of the pulper (e) to increase

- 14 044578 read the pressure difference between the pulper (e) and the reactor receiving the liquid substrate to facilitate filling the reactor. If desired, pumps can be used to fill the reactor without negatively affecting the rest of the process. Instead of conventional pumps, a barometric monteju can also be used to circulate the pulper and feed into the reactor, for example with one barometric monteju mounted on each pulper. In such a scenario, valves will control whether the substrate is fed into the reactors through the monteju or fed back into the pulper for mixing. During filling of the barometric monteju, the space above the barometric monteju can be connected to a vacuum system to increase the filling rate. Steam will be injected into the empty space in the barometric plant to discharge the contents into the reactors or to circulate them back to the pulper for mixing. The sequence of filling the barometric monteju, mixing in the pulper and feeding into the reactor(s) will be a sequential step-by-step process.

During startup or other unusual situations, it may be necessary to either preheat the liquid substrate in the pulper(s) or pressurize the void space of the vessel to transfer the substrate to the reactors. For this reason, it may be useful to prepare the pulper e for real-time steam injection below and above the liquid level.

Reactors (f, g, h, i).

The reactors are equipped with steam tubes to inject hot steam into the liquid substrate. In addition, they are equipped with a valve and line to supply gas from the ullage to the pulper (a). The same line can be used to install reactors at subambient pressure before filling the reactor.

Overall performance.

Actual steam flow, temperature and pressure depend on several factors. Some of these include the temperature and composition of the feedstock, the selected temperature and pressure in the reactor, the liquid level above the steam tubes of the pulper, the pressure loss in the piping, the loss of heat to the environment and dynamic effects. However, the overall performance can be calculated with reasonable accuracy.

The table below shows typical vessel temperatures and pressures as approximate values. As a basis for the calculation, a feed solids content of 16.5%, feed temperatures of 5, 15 and 40°C and reactor temperatures of 140, 165 and 220°C are assumed.

Calculations include typical pressure losses in pipelines, the influence of non-condensable gases and hydraulic pressures at steam injection points. With smaller losses, the temperatures and pressures in pulpers 1 and 2 will be slightly higher, while the temperatures and pressures in tanks 1 and 2 will be lower. With higher losses, the temperatures and pressures in pulpers 1 and 2 will be slightly lower, while the temperatures and pressures in tanks 1 and 2 will be slightly higher. In addition, steam can be released from pulper 2 into pulper 1 to heat pulper 1 to higher temperatures if desired. This will affect the temperature and pressure in other vessels. The figures below are examples of actual average temperatures and pressures during plant operation at steady state. Please note that pressures stated include the presence of non-condensable gases and that temperatures are rounded to the nearest whole number while pressures are rounded to one decimal place.____________________________________________

Vessel Supply temperature [C] Hydrolysis temperature [C] Vessel temperature [C] Pressure in the vessel [bar abs.]

- 15 044578

Pulper a (1) 5 140 40 0.2 Pulper e (2) 90 0.7 Reactors f, g, h, i 140 3.7 Evaporation tank j (1) 100 1.0 Evaporation tank b (2) 72 0.4 Pulper a (1) 15 140 49 0.2 Pulper e (2) 94 0.8 Reactors f, g, h, i 140 3.7 Evaporation tank] (1) 103 1.1 Evaporation tank b (2) 75 0.4 Pulper a (1) 40 140 69 0.4 Pulper e (2) 103 1.1 Reactors f, g, h, i 140 3.7 Evaporation tank] (1) 111 1.5 Evaporation tank b (2) 86 0.6 Pulper a (1) 5 165 57 0.3 Pulper e (2) 113 1.6 Reactors f, g, h, i 165 7.0 Evaporation tank j (1) 119 1.9 Evaporation tank b (2) 78 0.5 Pulper a (1) 15 165 64 0.3 Pulper e (2) 116 1.8 Reactors f, g, h, i 165 7.0 Evaporation tank] (1) 122 2.1 Evaporation tank b (2) 83 0.5 Pulper a (1) 40 165 82 0.6 Pulper e (2) 125 2.3 Reactors f, g, h, i 165 7.0 Evaporation tank] (1) 129 2.6 Evaporation tank b (2) 94 0.8

- 16 044578

Pulper a (1) 5 180 66 0.4 Pulper e (2) 127 2.5 Reactors f, g, h, i 180 10 Evaporation tank j (1) 131 2.8 Evaporation tank b (2) 84 0.6 Pulper a (1) 15 180 74 0.5 Pulper e (2) 131 2.8 Reactors f, g, h, i 180 10 Evaporation tank] (1) 134 3 Evaporation tank b (2) 88 0.7 Pulper a (1) 40 180 89 0.8 Pulper e (2) 137 3.3 Reactors f, g, h, i 180 10 Evaporation tank j (1) 140 3.6 Evaporation tank b (2) 100 1 Pulper a (1) 5 220 95 1 Pulper e (2) 167 7.3 Reactors f, g, h, i 220 23.2 Evaporation tank] (1) 168 7.6 Evaporation tank b (2) 103 1.1 Pulper a (1) 15 220 100 1.1 Pulper e (2) 168 7.6 Reactors f, g, h, i 220 23.2 Evaporation tank j (1) 170 7.9 Evaporation tank b (2) 108 1.3 Pulper a (1) 40 220 115 1.8 Pulper e (2) 174 8.7 Reactors f, g, h, i 220 23.2 Evaporation tank j (1) 9 176 Evaporative 119 2.0 tank b (2)

Under the most typical conditions, in which the feed temperature is 15°C and the reactor temperature is 165°C, the total steam consumption will be approximately 640 or 100 kg/t or kg/m ³ feed, respectively. This is lower than any other existing steam explosion thermal hydrolysis processes that use hot steam injection to transfer heat. Low steam consumption is made possible by using flash steam below ambient pressure for preheating. Additionally, using differential pressure or barometric montage instead of pumps to fill the reactor makes it easier to reduce filling time. In addition, preheating to higher temperatures reduces the steam injection time into the reactors. These two factors contribute to an increase in productivity per reactor volume compared to existing PTG installations.

Example 3.

In most jurisdictions around the world, an installation or system containing pressure vessels must be inspected on a regular basis, for example, on an annual basis, as part of the certification of industrial facilities (for example, an installation or system in accordance with the present invention) in which pressure vessels are used. pressure. National or regional regulations may regulate the specific frequency of inspections required. Due to the time required for such checks, when operating a plant in accordance with the present invention as described in Examples 1 and 2, there will be periods of downtime that reduce the processing capacity of liquid substrates. In such situations, stable operation of the installation or system according to one of the examples 1

-

Claims (13)

or 2 above can be achieved by a) introducing additional features/functions to safely isolate each of one or more pulper and/or flash tank units, thereby providing a reduced operating mode allowing individual inspection of each pulper and/or flash tank unit in a safe environment; and b) introducing additional workarounds, such as piping, to eliminate each individual pulper and/or flash tank unit from operation. Possible implementation of such additional features/functions and associated workarounds, for example through piping, to allow continued operation of the plant in accordance with one or Examples 1 or 2 above in the event of failures or planned shutdowns of one or more pulpers and or evaporation tanks, may include: A pipeline capable of transferring said liquid substrate containing from 2 to 30% solids at a temperature below about 50° C. directly to either of said at least two pulpers (P1(a) and P2(e)), wherein said pipeline equipped with one or more closing valve(s) allowing selection of which of said at least two pulpers (P1(a) and P2(e)) should receive said liquid substrate containing from 2 to 30% solids at a temperature below approximately 50°C. Connections by a pipeline providing transfer of said liquid substrate from any of said at least two pulpers (P1(a) and P2(e)) into any of said one or more reactors (R(f-i)). Connections by a pipeline providing ventilation from any of the specified one or more reactors (R(f-i)) to any of the specified at least two pulpers (P1(a) and P2(e)). Connections via piping that provide transfer of said liquid substrate from any of said one or more reactors (R(f-i)) to any of said one or more flash tanks. Connections through a pipeline that bypasses said vacuum system (V(c)). When the plant or system in accordance with the present invention is operated at such a reduced operating mode, the productivity of the plant can (for a system or plant with two pulpers) be identical to that of a conventional system with one pulper and one flash tank. Another option with this reduced operation is that any individual reactor can be taken out of service, allowing the plant to remain productive at reduced power. Despite this, the operating principles remain similar to those described in examples 1 and 2. CLAIM 1. A process for the thermal hydrolysis of a liquid substrate with a solids content of 2 to 30% and a temperature below about 50°C, intended for subsequent use in anaerobic fermentation, digestion or other process aimed at the production or extraction of methane or other valuable substances in one or more reactors (R (f-i)), and this method is characterized by the fact that the same number of evaporation tanks and pulpers is used; wherein at least first and second series-connected pulpers (P1 (a) and P2 (e)) and at least first and second series-connected evaporation tanks (F1 (j) and F2 (b)) are used for stepwise preheating and pressure reduction accordingly, as well as the fact that: a) the specified liquid substrate is transferred to the first pulper (P1 (a)) and is preheated and mixed in the first pulper (P1 (a)), which operates at a temperature from 40 to 90 ° C and a pressure from 0.2 to 0.9 bar abs., by injecting flash vapor below the liquid level from a downstream flash tank, for example said second flash tank (F2(b)), which operates at a higher pressure than said first pulper (P1(a)); b) the specified pressure of 0.2 to 0.9 bar abs., at which said first pulper (P1(a)) operates, is maintained by a vacuum system (V(c)) operating to maximize the condensation of any condensable vapors that do not condense when passing through said liquid substrate in said first pulper; c) said preheated liquid substrate is transferred from said first pulper (P1 (a)) to a second pulper (P2 (e)), which operates at a temperature of from 90 C to 135 C and at a pressure of from 0.7 to 3.3 bar abs., and wherein said liquid substrate is subjected to further mixing and preheating by injecting flash vapor below the liquid level from a downstream flash tank (F1(j)), for example said first flash tank, which operates at a higher pressure, than said second pulper (P2(e)); d) said additionally preheated liquid substrate is transferred from said second pulper (P2(e)) into one or more reactors (R(f-i)) operating in parallel or in series; - 18 044578 specifically, wherein said liquid substrate is heated to a temperature in the range from 140 C to 220 C and at a pressure from 3.6 to 10 bar abs.; e) said liquid substrate is transferred from said one or more reactors (R (f-i)), operating in series or parallel, to said first flash tank (F1 (j)), operating at a temperature of from 100 to 140° C. and at a pressure of from 1 to 3.6 bar abs., whereby the pressure is reduced, and from where the instantly generated steam resulting from this pressure reduction is transferred to said second pulper (P2 (e)), operating at a temperature of 90 to 135°C and pressure from 0.7 to 3.3 bar abs; f) said liquid substance is transferred from said first flash tank (F1 (j)) to said second flash tank (F2 (b)), operating at a temperature of from 70 to 100° C. and at a pressure of from 0.35 to 1 bar abs. , whereby a further reduction in pressure occurs, and from where the instantly generated steam resulting from such further reduction in pressure in said second evaporation tank (F2 (b)) is transferred to the first pulper (P1 (a)), operating at a temperature of from 40 to 90°C and at a pressure of 0.2 to 0.9 bar abs., through the specified vacuum system. 2. A process for the thermal hydrolysis of a liquid substrate with a solids content of from 2 to 30% and a temperature below about 50°C, intended for subsequent use in anaerobic fermentation, digestion or other process aimed at the production or extraction of methane or other valuable substances, in one or more reactors (R (f-i)), and this method is characterized by the fact that the number of evaporation tanks used is one less than the number of pulpers used; at least first and second series-connected pulpers (P1 (a) and P2 (e)) and at least one evaporation tank F are used for staged preheating and pressure reduction, respectively; wherein: a) said liquid substrate is transferred to the first pulper (P1(a)) and preheated and mixed in the first pulper (P1(a)), which operates at a temperature of 40 to 90°C and a pressure of 0.2 to 0.9 bar abs., by injecting instantly generated steam below the liquid level from a downstream evaporation tank (F) which operates at a higher pressure than said first pulper (P1(a)); b) the specified pressure of 0.2 to 0.9 bar abs., at which said first pulper (P1(a)) operates, is maintained by a vacuum system (V(c)) operating to maximize the condensation of any condensable vapors that do not condense when passing through said liquid substrate in said first pulper; c) said preheated liquid substrate is transferred from said first pulper (P1(a)) to a second pulper (P2(e)), which operates at a temperature of from 90 to 135°C and at a pressure from 0.7 to 3.3 bar abs., and wherein said liquid substrate is subjected to further mixing and preheating by injection of flash steam below the liquid level from one or more downstream reactors (R(f-i)) which operate at a higher pressure than said second pulper (P2(e)); d) said further preheated liquid substrate is transferred from said second pulper (P2(e)) into said one or more reactors (R(f-i)), operating in parallel or in series, wherein said liquid substrate is heated to a temperature in the range of 140 to 220°C and pressure from 3.6 to 10 bar abs.; e) in one or more reactors (R (f-i)), operating in parallel or in series, depressurize by transferring steam from the empty space of the reactor to the specified second pulper (P2 (e)) until the pressure in one or more in parallel or sequentially operating reactors (R (f-i)) and the second pulper (P2 (e)) will not become equilibrium, after which the specified liquid substrate is transferred from the specified one or more parallel or sequential operating reactors (R (f-i)) to the specified downstream flow evaporation tank (F). 3. The method according to any one of claims 1 or 2, further characterized in that the steam cooler (VC (d)), which is connected between said first pulper (P1 (a)) and said vacuum system (V (c)), operates for condensing and removing any vapors condensing below the temperature at which said first pulper operates (P1(a)). 4. The method according to any one of claims 1-3, further characterized in that it includes stages aimed at compressing the remaining non-condensable vapors from the empty space of the specified first pulper (P1 (a)), which do not condense in the specified first pulper (P1 (a)), nor in said connected vapor cooler (VC (d)), and steps for injecting said compressed non-condensable vapors into an anaerobic reactor or any other gas treatment means. 5. The method according to any one of claims 1-4, in which the movement of the specified liquid substrate between pulpers, reactors, evaporation tanks, etc. carried out, at least in part, by barometric pumping. 6. Installation for thermal hydrolysis of a liquid substrate with a solid content of 2 - 19 044578 up to 30% and a temperature below about 50°C, intended for subsequent use in anaerobic fermentation, digestion or other process aimed at producing or extracting methane or other valuable substances, said installation comprising: the same number of evaporation tanks and pulpers and at least the first and second pulpers (P1 (a) and P2 (e)), sequentially connected to each other directly or indirectly; a vacuum system (V (c)) connected by a pipeline to one of the at least two pulpers (P1 (a)); one or more reactors (R (f-i)), operating in parallel or in series and connected by a pipeline to one of said at least two pulpers (P2 (e)), which is not connected to said vacuum system (V (c)); at least first and second evaporation tanks (F1 (j) and F2 (b)) connected in series directly or indirectly: one of which (F1 (j)) is connected by pipeline to said one or more reactors (R (f-i)), operating in parallel or in series, each of which is individually connected by pipeline to one of at least two pulpers (P1 (a) and P2 (e)), and each of which individually can operate at a higher pressure than one of at least two pulpers (P1 (a) and P2 (e)), to which it is individually connected by a pipeline, while: a) said first pulper (P1(a)) can operate at a temperature of 40 to 90°C at a pressure of 0.2 to 0.9 bar abs. by injecting instantly generated steam below the liquid level from one of said at least two downstream evaporation tanks to which it is individually connected, for example from said second evaporation tank (F2 (b)); b) said vacuum system can maintain a specified pressure of 0.2 to 0.9 bar abs. at which the first pulper (P1(a)) is to be operated, and can be operated to maximize the condensation of any condensable vapors that do not condense when passing through said liquid substrate in said first pulper; c) said second pulper (P2 (e)) can operate at a temperature of 90 to 135° C. and a pressure of 0.7 to 3.3 bar abs. by injecting instantly generated steam below the liquid level from one of said at least two downstream evaporation tanks to which it is individually connected, for example from said first evaporation tank (F1 (j)); d) said one or more reactors (R (f-i)), operating in parallel or in series, can operate at a temperature in the range from 140 to 180°C and at a pressure from 3.6 to 10 bar abs.; e) said liquid substrate may be transferred from said one or more reactors (R (f-i)), operating in series or parallel, to said first flash tank (F1 (j)), operating at a temperature of 100 to 140° C. and pressure from 1 to 3.6 bar abs., whereby a reduction in pressure occurs, and from where the instantaneously generated steam resulting from such a reduction in pressure can be transferred to said second pulper (F2 (b)), operating at a temperature of from 90 to 135 °C and at a pressure from 0.7 to 3.3 bar abs.; f) said liquid substance may be transferred from said first flash tank (F1 (j)) to said second flash tank (F2 (b)), operating at a temperature of 70 to 100°C and a pressure of 0.35 to 1 bar abs., whereby a further reduction in pressure occurs, and from where the instantly generated steam resulting from said further reduction in pressure in said second evaporation tank (F2 (b)) can be transferred to said first pulper operating at a temperature of from 40 to 90 °C and at a pressure of 0.2 to 0.9 bar abs., using the specified vacuum system. 7. An installation for the thermal hydrolysis of a liquid substrate with a solids content of from 2 to 30% and a temperature below about 50°C, intended for use in anaerobic fermentation, digestion or other process aimed at the production or extraction of methane or other valuable substances, wherein said the installation contains one more pulper than evaporation tanks: at least the first and second pulpers (P1 (a) and P2 (e)), connected in series directly or indirectly, a vacuum system (V (c)), connected by a pipeline to one of the said at least two pulpers (P1 ( a)), one or more reactors (R (f-i)), operating in parallel or in series and connected by a pipeline to one of said at least two pulpers (P2 (e)), which is not connected to said vacuum system (V (c) ), at least one evaporation tank (F): connected by pipeline to one or more reactors (R(f-i)) operating in parallel - 20 044578 or sequentially; connected by a pipeline to one of at least two pulpers (P1(a)) and capable of operating at a higher pressure than one of at least two pulpers (P1(a)) to which it is separately connected via a pipeline, wherein: a) said first pulper (P1(a)) can operate at a temperature of 40 to 90°C and a pressure of 0.2 to 0.9 bar abs. by injecting flash vapor below the liquid level from said downstream evaporation tank to which it is connected (F); b) said vacuum system can maintain a specified pressure of 0.2 to 0.9 bar abs. at which said first pulper (P1(a)) is to be operated, and can be operated to maximize the condensation of any condensable vapors that do not condense as they pass through through said liquid substrate in said first pulper; c) said second pulper (P2 (e)) can operate at a temperature of 90 to 135° C. and a pressure of 0.7 to 3.3 bar abs.; d) said one or more reactors (R (f-i)), operating in parallel or in series, can operate at temperatures ranging from 140 to 220° C. and pressures from 3.6 to 10 bar abs.; e) said liquid substrate may be transferred from said one or more reactors (R(f-i)) operating in series or parallel to said flash tank (F) by depressurizing said one or more reactors (R(f-i)) operating in parallel or in series, by transferring steam from the void space of the reactor to said second pulper (P2(e)) until the pressure in said one or more reactors (R(f-i)), operating in parallel or in series, and said second pulper ( P2 (e)) will not reach equilibrium, after which the specified liquid substrate can be transferred from the specified one or more reactors (R (f-i)), operating in parallel or in series, to the specified evaporation tank (F). 8. The installation according to any one of claims 6 or 7, further comprising a vapor cooler (VC (d)) connected between said first pulper (P1 (a)) and said vacuum system (V (c)), which can operate at a temperature below the operating temperature of said first pulper (P1(a)), which makes it possible to remove condensable vapors that do not condense in said first pulper (P1(a)). 9. Installation according to any one of claims 6 to 8, further characterized in that it includes means for compressing the remaining non-condensable vapors from the empty space of the specified first pulper (P1 (a)), which do not condense in the specified first pulper (P1 (a) )), nor in said connected vapor cooler (VC(d)), and means for injecting said compressed non-condensable vapors into an anaerobic digester or any other gas treatment means. 10. Installation according to any one of claims 6 to 9, further comprising containers used for at least partial movement of said liquid substrates by barometric pumping. 11. Installation according to any one of paragraphs 6-10, additionally including: a pipeline capable of transferring said liquid substrate with a solids content of from 2 to 30% and a temperature below about 50° C. directly into any of the at least two pulpers (P1 (a) and P2 (e)), wherein said pipeline is equipped one or more shut-off valves allowing selection of which of said at least two pulpers (P1 (a) and P2 (e)) is to transfer said liquid substrate with a solids content of from 2 to 30% and a temperature below about 50° WITH; connection through a pipeline providing transfer of the specified liquid substrate from any of the specified at least two pulpers (P1 (a) and P2 (e)) into any of the specified one or more reactors (R (f-i)); connection by means of a pipeline providing ventilation from any of the specified one or more reactors (R (f-i)) to any of the specified at least two pulpers (P1 (a) and P2 (e)); connecting via a pipeline allowing said liquid substrate to be transferred from any of said one or more reactors (R(f-i)) to any of said one or more flash tanks; connection through a pipeline that allows you to bypass the specified vacuum system (V (c)). 12. A method of upgrading an existing plant for the hydrolysis of a liquid substrate with a solids content of 2 to 30% and a temperature below about 50°C, intended for use in anaerobic fermentation, digestion or other process aimed at the production or extraction of methane or other valuable substances, wherein said upgrade ensures that said installation includes at least the features of the installation of claim 6. 13. A method for upgrading an existing installation for the hydrolysis of a liquid substrate with a solids content of 2 to 30% and a temperature below about 50 ° C, intended for use -