Waste-heat recovery and utilization unit for a sterilization method

Abstract

The invention relates to a waste-heat recovery and utilization unit (300) for a thermal method of batch sterilization, comprising: a sensible-heat storage module (201) holding a temperature-stratified storage fluid; a first heat exchanger (202), referred to as a recovery unit; a second heat exchanger (203), referred to as a preheater, for restituting the heat stored by the storage fluid and heating the product to be sterilized, fluidically connected to the outlet of the sensible-heat storage module for cooling of the storage fluid; one or more controlled isolation valves (DE-STO-FR, CH-STO-TO, CH-STO-FR, DE-STO-TO) optionally allowing the orientation and supply of the components of the waste-heat recovery and utilization unit (300) depending on the sterilization phases.

Description

[0001] DESCRIPTION

[0002] TITLE: Waste heat recovery and valorization unit for sterilization processes

[0003] TECHNICAL FIELD OF THE INVENTION

[0004]

[0001] The present invention relates to the general field of energy recovery and optimization of the use of thermal energy.

[0005]

[0002] The invention finds application particularly in the field of sterilizers using heat intermittently to implement a sterilization cycle. In particular, it applies to batch sterilization processes, also known as "batch" sterilization processes, enabling the sterilization, decontamination, or neutralization of effluents using suitable reactors with heat recovery and release via indirect heat exchange, i.e., without contact. The invention can be applied to any type of batch sterilization process involving a reactor, particularly in the food processing, pharmaceutical, and cosmetics industries, among others.

[0006]

[0003] The invention thus proposes a unit for recovering and utilizing waste heat for a batch thermal sterilization process, a sterilization device comprising such a unit, as well as an associated thermal energy recovery and utilization process.

[0007] STATE OF THE ART

[0008]

[0004] The ecological optimization of industrial equipment and processes is an approach in which manufacturers are increasingly engaged. In addition to having a positive impact on the environment, ecological optimization contributes to the company's image. Ecological optimization commonly involves energy optimization, leading to cost reductions.

[0009]

[0005] Among the industrial processes that can be optimized, sterilization devices and processes are major consumers of energy and water, a large portion of which is not recycled. One area of ​​research concerns the storage of waste energy generated by these sterilization processes.

[0010]

[0006] In particular, the decontamination of contaminated effluents is an essential step in pharmaceutical processes to ensure that pathogens do not spread outside of laboratories or industrial manufacturing sites. Therefore, many pharmaceutical companies favor effluent decontamination using batch thermal processes designed to ensure compliance with regulatory criteria.

[0011]

[0007] Some known batch processes for effluent decontamination rely on the use of reactors heated and homogenized at temperatures sufficient to ensure the elimination of pathogens contaminating the effluent. In these batch processes, the heat supply is generally provided by steam produced from the combustion of natural gas. Environmental regulations also require that the treated and decontaminated effluent be cooled before discharge or disposal.

[0012]

[0008] French patent application FR 3 015 293 A1 describes an example of a process for decontaminating effluents. The decontamination system consists of three main elements: a contaminated effluent receiving tank, a batch thermal decontamination reactor, and a cooling heat exchanger. The process operates in four phases: gravity filling of the decontamination reactor, or inactivation tank, from the collection tank, which may be assisted by steam injection or a pump; heating of the reactor; heating or maintaining the temperature by direct steam injection from a hot utility network to ensure effluent decontamination; and draining and cooling through a heat exchanger connected to a cold utility network (cooling water).

[0013]

[0009] Specifically, during the first phase of filling the reactor with contaminated effluent, a certain quantity of contaminated (cold) effluent, initially stored in the collection tank, is admitted into the decontamination reactor. During the second phase of heating by steam injection, a steam flow rate, for example 80 kg / h, is injected to raise the temperature of the effluent contained in the reactor: the injection can be made either directly into the volume of effluent contained in the reactor (as in patent application FR 3 015 293 A1), or through the double wall of the reactor, or sometimes both. The steam then releases its heat by condensing into the system formed by the effluent and the reactor.During the third phase of steam injection heating, a minimum steam flow rate, lower than that used during the second heating phase, is injected to maintain the temperature (e.g., around 135°C) and pressure (e.g., around 2.5 bar) of the reactor interior and the effluent it contains. The injection can be made either directly into the effluent volume within the reactor (as described in French patent application FR 3 015 293 A1), or through the reactor's double wall, or sometimes both. The steam then releases its heat by condensing into the system formed by the effluent and the reactor. During the fourth phase of reactor draining and decontaminated effluent cooling, the decontaminated effluent is drained from the reactor by gravity, although steam injection assistance is possible, and directed to a cooling section for further cooling.The cooling section involves a heat exchanger whose second circuit is connected to a cold utility network, for example cooling water.

[0014]

[0010] Decontamination during the second and third phases, particularly as envisaged in patent application FR 3 015 293 A1, is carried out by direct injection of a steam flow into the reactor within the effluent. The heat exchange through direct contact between the injected steam and the effluent results in undesirable condensation of the steam depending on the pressure confined within the reactor. Consequently, when the reactor is drained, the quantity of material extracted corresponds to the mass of effluent admitted during filling, to which is undesirably added the mass of steam condensate resulting from the treatment.

[0015]

[0011] Other solutions for thermal recovery used in batch thermal processes, particularly those operated in reactors or autoclaves, are known from the prior art, for example for preparation, cooking, fermentation, pasteurization, canning, sterilization, decontamination, steaming, etc. Examples include European patent application EP 4 074 662 A1, US patent application US 2007 / 131603 A1, European patent application EP 3 882 555 A1 and US patent US 9,566,365 B2.

[0016]

[0012] However, there is still a need for improvement in the recovery and use of thermal energy.

[0017] DESCRIPTION OF THE INVENTION

[0018]

[0013] The invention aims to remedy at least partially the needs mentioned above and the disadvantages relating to the achievements of the prior art.

[0019]

[0014] The invention aims in particular to offer an optimized solution for the recovery and valorization of waste heat by controlling a natural thermal stratification within a thermal storage module based on the physical effect "thermocline", unlike prior art systems which propose to obtain thermal stratification by physical discretization of the storage volume by temperature level.

[0020]

[0015] In particular, the invention aims to enable the recovery and reuse of waste heat within the same batch thermal process, involving the use of thermal storage to compensate for the intermittency between the waste heat recovery phase and the heat reuse phase.

[0016] The invention thus relates, according to one of its aspects, to a waste heat recovery and reuse unit for a batch-based thermal sterilization process, in particular a batch thermal process for the thermal decontamination of effluent, notably by direct steam injection into the reactor, characterized in that it comprises:

[0021] - a sensible heat storage module receiving a temperature-stratified storage fluid,

[0022] - a first heat exchanger, called a recuperator, fluidly connected to an inlet of the sensible heat storage module to heat the storage fluid after heat recovery and fluidly connected to an outlet of the sensible heat storage module for cooling the sterilized product, in particular a decontaminated effluent,

[0023] - a second heat exchanger, called a preheater, fluidly connected to the inlet of the sensible heat storage module for the release of heat stored by the storage fluid and the heating of the product to be sterilized, in particular a contaminated effluent, and fluidly connected to the outlet of the sensible heat storage module for the cooling of the storage fluid,

[0024] - one or more controlled isolation valves, allowing the orientation and supply or not of the components of the waste heat recovery and valorization unit according to the sterilization phases.

[0025]

[0017] The invention improves the quality of recoverable thermal energy, simplifies the unit design, and maximizes its compactness for application to the same batch thermal process. It preserves the benefits of natural thermal stratification while being controllable and industrially usable.

[0018] The waste heat recovery and utilization unit according to the invention may further include one or more of the following features, taken individually or in any possible technical combination.

[0026]

[0019] The formation and maintenance of the temperature stratification of the stratified storage fluid of the sensible heat storage module can be achieved through the control of a storage fluid injection and withdrawal system, in particular hydraulic.

[0027]

[0020] The waste heat recovery and utilization unit may include a storage fluid circulation pump, located fluidically between the sensible heat storage module and the recuperator, and including a differential pressure regulating valve.

[0021] The waste heat recovery and utilization unit may further include one or more temperature probes, including a first temperature probe located at the outlet of the recuperator and a second temperature probe located at the outlet of the preheater.

[0028]

[0022] In addition, the waste heat recovery and utilization unit may include an expansion vessel on the fluidic circuit of the storage fluid, in particular an expansion vessel located upstream of a circulation pump for the storage fluid.

[0029]

[0023] Advantageously, the waste heat recovery and valorization unit may include additional cooling supply means for cooling the sterilized product, in particular located downstream of the sensible heat storage module.

[0030]

[0024] In particular, the additional cooling supply means may include a cold utility network, the waste heat recovery and utilization unit being connected to the cold utility network.

[0031]

[0025] The additional cooling supply means may also include an additional heat exchanger, in particular located downstream of the recuperator, connected to a cold utility network.

[0032]

[0026] The additional cooling supply means may also include a cooling unit on the fluidic circuit of the storage fluid, in particular located downstream of the sensible heat storage module.

[0033]

[0027] In addition, the means for providing additional cooling may also include a heat pump, comprising in particular successively an evaporator and a condenser or the reverse.

[0034]

[0028] Furthermore, the invention also relates, according to another aspect, to a sterilization device for a batch-controlled thermal sterilization process, in particular a batch thermal process for the thermal decontamination of effluent, in particular by direct injection of steam into the reactor, characterized in that it comprises:

[0035] - a waste heat recovery and utilization unit as defined above,

[0036] - a sterilizer, also called an autoclave or decontamination tank, comprising an inlet fluidly connected to the second heat exchanger, called the preheater, and an outlet fluidly connected to the first heat exchanger, called the recuperator.

[0029] The sterilization device may include a collection tank for the product to be sterilized, in particular contaminated effluent, fluidly connected to the second heat exchanger, called the preheater.

[0037]

[0030] Advantageously, the sterilization device may include at least two sterilizers mounted in parallel.

[0038]

[0031] Furthermore, the invention also relates, according to another aspect, to a method for recovering and utilizing thermal energy by a waste heat recovery and utilization unit as defined above, the method being implemented in a batch-based thermal sterilization process, in particular a batch thermal process for the thermal decontamination of effluent, characterized in that it comprises:

[0039] - a heat recovery step on the sterilized product, in particular the decontaminated effluent, via the heat recovery unit which charges the sensible heat storage module,

[0040] - a heat restitution step on the product to be sterilized, in particular the contaminated effluent, by means of the preheater allowing the discharge of the sensible heat storage module.

[0041]

[0032] During the recovery stage, the flow rate of the storage fluid circulating in the recovery unit can be controlled according to a predefined setpoint temperature to be reached on the temperature of the sterilized product measured at the outlet of the recuperator.

[0042]

[0033] Furthermore, during the restitution stage, the flow rate of the storage fluid circulating in the recovery and valorization unit can be controlled according to a predefined setpoint temperature to be reached on the temperature of the storage fluid measured at the outlet of the preheater.

[0043]

[0034] Furthermore, during the restitution step, the process may include the step of additional cooling depending on the asymmetry between the amount of heat that can be recovered and the amount of heat that can be restored.

[0044] BRIEF DESCRIPTION OF THE FIGURES

[0045]

[0035] Other advantages, purposes and particular features of the invention will become apparent from the following non-limiting description of at least one embodiment of the present invention, with reference to the accompanying figures, in which: Figure 1 represents a simplified Piping and Instrumentation Diagram (or Process and Instrumentation Diagram, abbreviated P&ID) of a sterilization device incorporating a recovery and valorization unit according to the invention, illustrating the cooling of the decontaminated outgoing product; Figure 2 represents the diagram of Figure 1 illustrating the preheating of the incoming contaminated product; Figure 3 represents a Piping and Instrumentation Diagram (P&ID) of an alternative embodiment of the unit of Figure 1.Figure 4 shows a piping and instrumentation diagram (P&ID) of an alternative embodiment of the unit in Figure 1, illustrating the cooling of the decontaminated outgoing product with heat recovery and charging of the thermal storage module with external (or backup) cooling to the recovery and valorization unit. Figure 5 shows a piping and instrumentation diagram (P&ID) of another alternative embodiment of the unit in Figure 1, illustrating the cooling of the decontaminated outgoing product with heat recovery and charging of the thermal storage module with internal (or backup) cooling to the recovery and valorization unit.Figure 6 shows a piping and instrumentation diagram (P&ID) of an alternative embodiment of the unit in Figure 1, illustrating the cooling of the decontaminated outgoing product with heat recovery and charging of the thermal storage module with supplementary (or backup) cooling by a chiller unit internal to the recovery and valorization unit; Figure 7 shows an alternative embodiment of the diagram in Figure 6 with a modification of the chiller unit assembly; Figure 8 shows a piping and instrumentation diagram (P&ID) of an alternative embodiment of the unit in Figure 1.illustrating the cooling of the decontaminated outgoing product with heat recovery and charging of the thermal storage module with additional (or backup) cooling provided by a high-temperature heat pump integrated into the recovery and valorization unit, providing additional cooling to the storage fluid before it enters the recuperator and ensuring a temperature increase of the storage fluid at the outlet of the recuperator before storage, Figure 9 represents a piping and instrumentation diagram (P&ID) of an alternative embodiment of the unit of Figure 1, illustrating the preheating of the incoming contaminated product with heat recovery through the discharge of the thermal storage module and a temperature increase of the storage fluid before it enters the preheater thanks to a heat pump ensuring subcooling of the storage fluid at the outlet of the preheater, Figure 10A, Figure 10B,Figure 10C and Figure 10D represent four piping and instrumentation diagrams (P&IDs) of an alternative embodiment of the unit of Figure 1, illustrating four stages of operation with a shared recovery and valorization unit with two sterilizers, and Figure 11 represents a graph with a succession of six cycles, the energy recovered and then returned by the recovery and valorization unit according to the invention and the supplement provided by the utilities on the left ordinate, and the mass of effluents per phase on the right ordinate.

[0046]

[0036] Throughout these figures, identical references may designate identical or analogous elements.

[0047]

[0037] Furthermore, the different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible.

[0048] DETAILED DESCRIPTION OF THE INVENTION

[0049]

[0038] Throughout this description, given by way of non-limiting example, it is noted that the terms "upstream" and "downstream" at a given point refer to the direction of flow of the fluid in question. Furthermore, the expression "A fluidly connected to B" is synonymous with "A is in fluidic connection with B" and does not necessarily mean that there is no component between A and B. The expressions "arranged on" or "on" are synonymous with "fluidically connected to".

[0050]

[0039] With reference to figures 1 to 10D, examples of the realization of a waste heat recovery and valorization unit 300 in accordance with the invention will be described.

[0051]

[0040] The waste heat recovery and utilization unit 300 is used here, for example, for a batch thermal process for decontaminating pharmaceutical effluents. However, this is by no means a limitation and any other batch process could be involved.

[0052]

[0041] With reference to Figures 1 and 2, the unit 300 first comprises a sensible heat storage module 201 which receives a temperature-stratified storage fluid. The storage fluid is advantageously a heat transfer fluid chosen to operate within the operating temperature range. It is preferably water, in particular pressurized and superheated water, or any other fluid suitable for use as a heat transfer fluid, in particular a single-phase liquid.

[0053]

[0042] Among thermal storage technologies, sensible heat storage of a temperature-stratified liquid offers the advantage of being able to utilize, within the same tank, a hot volume and a cold volume, separated by a layer that concentrates the majority of the temperature gradient, called the "thermocline." To achieve this thermal stratification in the stored liquid volume, control of certain parameters, such as the injection and withdrawal rates of the liquid, is essential. Furthermore, the dimensional characteristics of the tank are also parameters that influence the quality of the thermal stratification.

[0054]

[0043] In addition, unit 300 includes a first heat exchanger called recuperator 202 and a second heat exchanger called preheater 203. The recuperator 202 will allow the recovery of heat and the charging of the thermal storage of module 201 between the chambering and emptying / cooling stages, while the preheater 203 will allow the release of heat and discharge of the thermal storage of module 201 between the filling and heating stages.

[0055]

[0044] To maximize the efficiency of waste heat recovery, it is necessary to limit the temperature degradation of the heat recovered, then stored, and finally released. In short, this implies maximizing the thermal efficiency of all elements in the chain, namely the heat exchanger 202, the sensible heat storage module 201, and the preheater 203.

[0056]

[0045] The main difficulty in recovering waste heat within this type of process is inherent in the imbalance between the amount of heat recoverable from the hot source and the amount of heat that can be transferred / absorbed by the cold source. This imbalance between the amount of heat recoverable from the hot source and the amount of heat transferable to the cold source depends on several factors detailed below.

[0057]

[0046] First, the difference between the quantity of matter composing the hot source and the quantity of matter composing the cold source due to vapor condensation. This characteristic is inherent to this type of process where the heat input is made directly, by direct injection of steam and not via a heat exchanger, and is therefore associated with a material input.

[0058]

[0047] Furthermore, the temperature difference between the sources: for the hot source, the temperature difference depends on the effluent outlet temperature from the reactor and the setpoint temperature to be reached for its cooling; for the cold source, the temperature difference depends on the temperature of the contaminated effluent during the reactor admission phase and the temperature to which it can be heated by the storage fluid, via the preheater, and its thermal efficiency.

[0048] Finally, thermal properties, such as density and specific heat, of the fluids considered: contaminated effluent, decontaminated effluent, and water vapor condensate.

[0059]

[0049] As seen in Figure 1 for example, the recuperator 202 is fluidly connected to an inlet 201e of the sensible heat storage module 201 to heat the storage fluid after heat recovery and fluidly connected to an outlet 201s of the sensible heat storage module 201 for cooling the decontaminated effluent.

[0060]

[0050] In addition, the preheater 203 is fluidly connected to the inlet 201e of the sensible heat storage module 201 for the release of the heat stored by the storage fluid and the heating of the contaminated effluent, and fluidly connected to the outlet 201s of the sensible heat storage module 201 for the cooling of the storage fluid.

[0061]

[0051] The waste heat recovery and valorization unit 300 is integrated within a sterilization device 400 which further comprises a sterilizer 103 including an inlet 103e fluidly connected to the preheater 203 and an outlet 103s fluidly connected to the recuperator 202.

[0062]

[0052] Sterilizer 103 is specifically designed for sterilization by spraying hot water or hot steam. It is also called an autoclave or decontamination tank / reactor. From an energy standpoint, the operation of sterilizer 103 is cyclical, with the following successive stages: heating, temperature maintenance, and cooling.

[0063]

[0053] The sterilization device 400 also includes a contaminated effluent collection tank 102 which is fluidly connected to the preheater 203.

[0064]

[0054] Figure 1 represents the cooling of the product, the effluent, exiting decontaminated, and therefore the heat recovery and the charging of the sensible heat storage module 201. Figure 2 represents the preheating of the product, the contaminated effluent entering, and therefore the heat release through the discharge of the thermal storage module 202.

[0065]

[0055] Specifically, the operating principle of unit 300 according to the invention consists first of all in recovering heat from the hot decontaminated effluent, for example around 130°C, before the cooling stage, allowing, for example, a temperature below 50°C to be reached, and then storing this heat until the next cycle restarts, which is symbolized in Figure 1 by arrow C1 representing the recovery. At the beginning of the next cycle, the heat is returned to preheat the contaminated effluent before it enters the sterilizer 103, which is symbolized in Figure 2 by arrow C2 representing the return.

[0056] The hydraulic network of unit 300 is therefore such that the heat recovery unit 202 is connected downstream of the sterilizer 103 and the preheater 203 is connected upstream of the sterilizer 103.Unit 300 also includes a set of components necessary for the power supply and control of the sensible heat storage module 201.

[0066]

[0057] Thus, unit 300 includes a storage fluid circulation pump 204, fluidically located between the sensible heat storage module 201 and the recuperator 202, which may include a differential pressure regulating valve REG-STO if necessary. Therefore, the flow rate of the storage fluid circulating in unit 300 can be regulated, during the heat recovery and release phases, according to specific setpoints and defined control laws, by this regulating valve REG-STO or by a variable speed drive present in the pump 204.

[0067]

[0058] In addition, unit 300 includes pilot-operated isolation valves DE-STO-FR, CH-STO-TO, CH-STO-FR and DE-STO-TO located on the hydraulic network of unit 300 allowing the orientation and supply or not of the components of unit 300 according to the phases of the sterilization cycle.

[0068]

[0059] In Figure 1, a DE-STO-FR valve is located between the preheater 203 and the storage module 201, another CH-STO-TO valve is located between the storage module 201 and the recuperator 202, another CH-STO-FR valve is located between the storage module 201 and the pump 204 and a final DE-STO-TO valve is located between the pump 204 and the storage module 201.

[0069]

[0060] In addition, the unit 300 includes TTC-H-PO and TTC-B-RO temperature probes, in particular a first TTC-B-RO temperature probe located at the outlet of the recuperator 202, the measurement of which is integrated into the control of the flow of the storage fluid during the heat recovery phase, and a second TTC-H-PO temperature probe located at the outlet of the preheater 203, the measurement of which is integrated into the control of the flow of the storage fluid during the heat release phase.

[0070]

[0061] The use of a dedicated hydraulic network allows for a storage fluid separate from the treated effluent, which never comes into contact with the latter, thus constituting a safety barrier. Heat transfer between the effluent and the storage fluid of the energy recovery network is achieved via two heat exchangers 202 and 203, ensuring that there is no mass transfer and therefore no risk of contamination. The heat recovery unit 202, positioned downstream of the sterilizer 103, cools the decontaminated effluent by circulating a flow of cold water drawn from the sensible heat storage module 201, located in the lower part, and supplying the energy recovery network. At the outlet of the heat recovery unit 202, the heated water returns to the sensible heat storage module 201, located in the upper part, for storage.

[0071]

[0062] At the start of the next cycle, the preheater 203, positioned upstream of the sterilizer 103, preheats the contaminated effluent by circulating a flow of hot water drawn from the sensible heat storage module 201, located in the upper part, which then supplies the recovery network. At the outlet of the preheater 203, the flow of cooled water returns to the sensible heat storage module 201 to be stored in anticipation of the next demand for cold water, i.e., for the second phase of the cycle. To enable this operation, the sensible heat storage module 201 allows for the simultaneous release of hot water and the storage of cold water, and vice versa.

[0072]

[0063] The chronology of the phases carried out in a cycle of a batch sterilization process using unit 300 is as described below. During the step of emptying a quantity of contaminated, cold effluent from the collection tank 102 to fill the sterilizer 103, unit 300 allows the storage of heat and / or cold.

[0073]

[0064] During the preheating, in the masked time of filling, of the quantity of contaminated effluent before its admission into the sterilizer 103, the unit 300 allows the restitution of the stored heat, recovered during the previous cycle, allowing the regeneration of a volume of cold / frigories in the sensible heat storage module 201.

[0074]

[0065] During the heating of the effluent contained in the sterilizer 103 to the set temperature, the unit 300 allows the storage of heat and / or cold.

[0075]

[0066] During the chambering stage, i.e. maintaining the effluent contained in the sterilizer 103 at the set temperature and pressure for a determined period, the unit 300 allows the storage of heat and / or cold.

[0076]

[0067] During the pre-cooling or complete cooling of the decontaminated effluent, emptied from the sterilizer 103, by its passage through the recuperator 202, the unit 300 allows the recovery of heat and then the storage thereof, by regeneration of a volume of hot water and consumption of the volume of cold / frigories in the sensible heat storage module 201.

[0077]

[0068] During the complete cooling or additional cooling of the decontaminated effluent, unit 300 allows the storage of heat and / or cold.

[0078]

[0069] The unit 300 according to the invention operates according to several phases or stages which are interfaced with some of the phases of the batch sterilization process cycle.

[0079]

[0070] First, as illustrated in Figure 1, a heat recovery step is implemented on the decontaminated effluent. This heat recovery phase on the hot decontaminated effluent, for example around 130°C, exiting the sterilizer 103, is carried out via the heat exchanger 202 and corresponds to the load of the sensible heat storage module 201. Heat recovery from the initially hot decontaminated effluent thus allows its cooling. During this phase, the isolation valves of the hydraulic network of unit 300 switch to the following positions: CH-STO-TO open, CH-STO-FR open, DE-STO-TO closed, and DE-STO-FR closed. Here, the sensible heat storage module 201, in conjunction with the heat exchanger 202, alone allows the decontaminated effluent to be completely cooled down to the setpoint temperature, in this case approximately 50°C.

[0080]

[0071] In this configuration, the hydraulic routing thus created allows the storage fluid to circulate in a loop within the recovery and valorization unit 300, initially being drawn cold from the lower part of the sensible heat storage module 201, then being heated in the recuperator 202 by heat extracted from the decontaminated effluent, before being reinjected hot into the upper part of the sensible heat storage module 201. The loop circulation of the storage fluid is ensured by the pump 204, and its flow rate is regulated either by the REG-STO control valve or by a variable speed drive on the pump 204. The pump 204 and the flow control device for the storage fluid are positioned between the withdrawal point and the reinjection point of the sensible heat storage module 201, either upstream or downstream of the recuperator 202.

[0081]

[0072] During this phase, the flow rate of the storage fluid circulating in unit 300 is advantageously controlled according to a setpoint for the temperature of the decontaminated effluent, for example, around 50°C, measured at the outlet of the heat exchanger 202 by the TTC-B-RO sensor. The heat exchanger 202 is advantageously sized so that, at its outlet, the decontaminated effluent can reach this predefined setpoint temperature while allowing the storage fluid to reach the highest possible temperature. This is achieved by considering the flow rate of the decontaminated effluent, imposed by the process, and the optimal flow rate of the storage fluid to achieve the best efficiency on the heat exchanger 202. The optimal flow rate of the storage fluid and its inherent pressure drop during its passage through the heat exchanger 202 can directly determine the sizing of the pump 204 and the flow control valve REG-STO.

[0082]

[0073] This method of dimensioning the components of unit 300 allows advantageous arrangements to maximize the efficiency of the recovery phase allowing the capture of the waste heat of the decontaminated effluent, the efficiency of the thermal storage phase, by minimizing the remixing of temperatures between the cold zone at the top of the storage and the flow of heated storage fluid re-entering the sensible heat storage module 201 from its upper part, which would lead to the thickening of the thermocline separation and therefore to the reduction of the recoverable heat during the release, and by ensuring compliance with the operating conditions of the decontamination process, i.e. compliance with the setpoint temperature for cooling the flow of decontaminated effluent.

[0083]

[0074] Advantageously, the thermal storage is sized to contain all the heat recovered during the first cycle. The first cycle is a sizing case because the thermal storage is considered to be initially entirely cold, between approximately 20°C and 30°C, and the amount of recoverable heat is at its highest, since the process has not yet benefited from heat savings obtained through the recovery of heat from a previous cycle. For example, a sensible heat storage module 201 containing approximately 0.5 m³ can be considered. 3 storage fluid would allow to efficiently store a quantity of heat of about 34 kWh taken from the first quantity of product emptied from sterilizer 103 at the end of the first cycle (for example: 362kg corresponding to 300kg of decontaminated effluent + 62kg of steam condensed during decontamination).

[0084]

[0075] During subsequent cycles, the amount of heat recovered and stored will be lower because the amount of heat required to complete the heating phase of the contaminated effluent will be less, given the heat returned to the effluent before its entry into the sterilizer 103. Consequently, the amount of condensed steam extracted with the decontaminated effluent during subsequent cycles will be lower, for example, on the order of 17 kg. In this case, the amount of recoverable heat would remain around 29.5 kWh during subsequent cycles once the system reaches operating steady state.

[0085]

[0076] In another embodiment, the thermal storage is sized to contain all the heat recovered when the system combining the decontamination process and unit 300 reaches a steady state. In this case, the sensible heat storage module 201 will have a smaller volume, for example, about 0.4 m³ 3and the established regime will require more cycles to stabilize. The drawback of this sizing is that the additional cooling requirements to finalize the cooling of the decontaminated effluent after the heat recovery phase will be greater than in the previous case.

[0086]

[0077] Furthermore, as illustrated in Figure 2, a heat recovery step is implemented on the contaminated effluent. This heat recovery phase on the cold contaminated effluent, for example around 20°C, close to the ambient temperature of the environment in which the collection tank 102 is located, is carried out before the contaminated effluent is admitted into the sterilizer 103 via the preheater 203 and corresponds to the discharge of the sensible heat storage module 201. The heat recovery on the initially cold contaminated effluent thus allows its preheating. During this phase, the isolation valves of the hydraulic network of unit 300 switch to the following positions: CH-STO-TO closed, CH-STO-FR closed, DE-STO-TO open, and DE-STO-FR open.

[0087]

[0078] In this configuration, the hydraulic routing thus created allows the storage fluid to circulate in a loop within the recovery and valorization unit 300, initially being drawn hot from the upper part of the sensible heat storage module 201, then being cooled in the preheater 203 by the heat returned to the contaminated effluent, before being reinjected cold into the lower part of the sensible heat storage module 201. The loop circulation of the storage fluid is ensured by the pump 204, and its flow rate is regulated either by the REG-STO control valve or by the variable speed drive of the pump 204. The pump 204 and the flow control device for the storage fluid are positioned between the point of withdrawal and the point of reinjection of the sensible heat storage module 201, either upstream or downstream of the preheater 203.

[0088]

[0079] During this phase, the flow rate of the storage fluid circulating in unit 300 is advantageously controlled according to a setpoint for the storage fluid temperature, for example around 35 °C, measured at the outlet of the preheater 203 by the TTC-H-PO sensor. The preheater 203 is advantageously sized so that at its outlet, the storage fluid reaches this setpoint temperature while allowing the contaminated effluent to reach the highest possible temperature. This is achieved by considering its flow rate, imposed by the process, and the optimal storage fluid flow rate for achieving the best efficiency on the preheater 203. The optimal storage fluid flow rate and its inherent pressure drop during its passage through the preheater 203 can directly determine the sizing of the pump 204 and the REG-STO flow control valve.

[0089]

[0080] This control strategy allows, during this heat release phase, the entire hot volume of the sensible heat storage module 201 to be discharged so as to reconstitute a completely cold storage volume, for example around 35°C, or even lower, which will be used during the next phase of cooling the decontaminated effluent exiting the sterilizer 103, also corresponding to the heat recovery phase by unit 300.

[0090]

[0081] This method of dimensioning the components of unit 300 allows advantageous arrangements to maximize the efficiency of the phase of recovery of the waste heat on the contaminated effluent and the efficiency of the thermal storage phase, by minimizing the remixing of temperatures between the hot zone at the bottom of the sensible heat storage module 201 and the flow of cooled storage fluid re-entering the sensible heat storage module 201 from its lower part, which would lead to the thickening of the thermocline separation and therefore to the reduction of the heat that can be recovered during recovery, and this by adapting to the operating conditions of the decontamination process, namely the flow of the contaminated effluent when it is admitted into the sterilizer 103 at the outlet of the collection tank 102.

[0091]

[0082] Advantageously, the sensible heat storage module 201 is sized to contain all of the cold, or frigories, regenerated during the phase of releasing the stored heat.

[0092]

[0083] In the case of an effluent decontamination process as described above, the quantity of effluent entering the sterilizer 103 during the filling phase is determined by its dimensions and is therefore constant. It can be, for example, on the order of 300 kg per cycle. Furthermore, if the temperature of the contaminated effluent before its admission to the sterilizer 103 varies little or is constant, for example close to ambient temperature, the cold source constituted by the contaminated effluent is limited and constant.

[0093]

[0084] Under these conditions, the maximum regeneration capacity of the cold volume of the sensible heat storage module 201 of unit 300 will depend on its ability to return to the contaminated effluent the heat contained in the hot volume stored in the sensible heat storage module 201, within the allotted time of the return phase.

[0094]

[0085] Two cases can then arise, detailed below. On the one hand, first case, it may be possible that the quantity of heat recoverable from the hot decontaminated effluent to be cooled is always much greater than the absorption capacity of the source on which the recovered and stored heat is returned, namely the quantity of contaminated effluent filling the sterilizer 103.

[0095]

[0086] In this case, the system will be sized so that the amount of heat recovered is equivalent, up to losses, to the absorption capacity of the cold source on which it will be returned.

[0096]

[0087] In this case, if the cooling temperature setpoint cannot be reached by the unit 300's heat capture capacity alone, a supplementary cooling source will be necessary. This arrangement opens the way to a range of possible variations, examples of which are detailed below with reference to Figures 3 to 9, of the system combining the unit 300 with a supplementary cooling source, either directly integrated into itself or external and connected in series with the decontamination process after the waste heat recovery phase.

[0088] Thus, as shown in Figure 3, external cooling, or backup, can be provided for the unit 300.Here, the sensible heat storage module 201 and the heat recovery unit 202 provide pre-cooling of the decontaminated effluent and are supplemented by an additional heat exchanger 205 connected to a chilled utility network to complete, as a backup, the cooling of the decontaminated effluent down to the setpoint temperature. Unit 300 also includes CH-COOL-TO and CH-COOL-FR pilot-operated isolation valves dedicated to the operation of this additional heat exchanger 205.

[0097]

[0089] In the example of Figure 4, the cooling supplement, or backup, is internal to the unit 300. The storage module 201 and the recuperator 202 are complemented by the additional heat exchanger 205 positioned on the storage fluid network and connected to a cold utility network to lower the temperature of the storage fluid when necessary in order to ensure, or secure, the cooling of the decontaminated effluent to the set temperature.

[0098]

[0090] In the example in Figure 5, the cooling supplement, or backup, is internal to the unit 300. Here, the recuperator 202 can be connected to a cold utility network to ensure, or secure, the cooling of the decontaminated effluent to the set temperature.

[0099]

[0091] In the example in Figure 6, heat recovery and charging of the storage module 201 are carried out with supplementary cooling, or backup, via a chiller unit.

[0100] 206 internal to unit 300. Here, unit 300 integrates the 300 cooling group allowing to complete, supplement or secure the cooling of the decontaminated effluent up to the set temperature via the recuperator 202.

[0101]

[0092] The example in Figure 7 represents a variant of the refrigeration unit mounting

[0102] 207 to limit the passage of the storage fluid during the heat release phases to the contaminated effluent.

[0103]

[0093] In the example of Figure 8, the supplementary cooling, or backup, is provided by a high-temperature heat pump, or heat pump, 206b, comprising successively a condenser 206b2 and an evaporator 206b1, integrated into the unit 300 and providing supplementary cooling to the storage fluid to subcool it before it enters the heat exchanger 202 and also ensuring a temperature increase of the storage fluid at the outlet of the heat exchanger 202 before storage in the storage module 201. Thus, at the outlet of the storage module 201, the storage fluid passes through the evaporator 206b1, lowering its temperature and cooling it, which in turn causes the temperature of the storage fluid to rise again, as it warms up, passing through the condenser 206b2 after its exit from the heat exchanger 202.

[0094] Furthermore, Figure 9 represents an architecture of the unit 300 relating to the preheating of the incoming contaminated product, and thus the recovery of heat through the discharge of the storage module 201 and a raising of the temperature of the storage fluid before its entry into the preheater 203 by means of a heat pump 206b, comprising an evaporator 206b1 and a condenser 206b2, also ensuring the subcooling of the storage fluid at the outlet of the preheater 203. It should be noted that this configuration can also constitute a second means of (pre)heating the contaminated product before its admission into the sterilizer 103, taking over from the storage module 201 when the latter is discharged, i.e. emptied of its heat and recharged with frigories. This allows the 206b heat pump to operate with a more attractive coefficient of performance by also subcooling the stored cooling during discharge from storage.This configuration allows the introduction of an electric (pre)heating method to further limit gas consumption.

[0104]

[0095] On the other hand, second case, there may be a very advantageous context where, depending on the conditions and operating instructions, all the energy recovered from the decontaminated effluent and then stored can be returned to the effluent during the following cycle(s).

[0105]

[0096] In this context, unit 300 will be sufficient to ensure on its own the regeneration of the chilled / cooling volume, during the heat release phase, necessary for the cooling phase of the decontaminated effluent, corresponding to the heat recovery phase from the point of view of unit 300 and sensible heat storage module 201.

[0106]

[0097] In this case, the efficiency of the heat exchangers of unit 300 will be different due to the difference in temperatures across the exchanger terminals, insofar as the energy will be recovered on a larger quantity of matter than the quantity of matter on which this same energy can be restored.

[0107]

[0098] In this case as well, the sensible heat storage module 201 of unit 300 will be sized taking into account an excess volume to absorb the surplus energy recovered during the first cycle that cannot be immediately released. This surplus energy recovered, stored, and not released during the first cycle can then either be released gradually during subsequent cycles in steady state, if the energy available for release is greater than the energy recovered, or be retained during subsequent cycles in steady state, if the energy released is equal to the energy recovered, and will be used to compensate for the system's heat losses or will be exploited during a process restart following a prolonged shutdown.

[0099] Figure 11 is a graph representing an example of evaluation of the energy recovered and then returned by the recovery and valorization unit 300 and of the energy supplied in addition by the utilities, during a succession of cycles (starting with a cold storage module 201) and evaluation of the mass of the effluents per phase of the chained cycles.

[0108]

[0100] Table 1, shown below, details an example of evaluation of the energy recovered and then returned by the recovery and valorization unit 300 and of the energy supplied in addition by the utilities, during a succession of cycles (start-up with a sensible heat storage module 201 cold) and evaluation of the mass of the effluents per phase of chained cycles, in the case of a unit 300 sized and designed to allow independence of the process from the cold utility.

[0109] Table 1

[0110]

[0101] This example clearly illustrates that in the first cycle, during the effluent cooling phase, the energy recovered by the unit is very high, approximately 33.7 kWh, due to the large quantity of material from which the energy is recovered, since it corresponds to the maximum value of condensate produced, i.e., 62.4 kg. However, despite a high quantity of thermal energy recovered and stored, its temperature, for example 95°C, can be limited by the initial storage temperature at start-up, for example 20°C, which is generally lower than the setpoint temperature, for example 30°C, applied to the first TTC-B-RO temperature probe during subsequent discharges, which will recondition the cold storage volume.

[0111]

[0102] In the next cycle (cycle 2), this recovered energy temperature, for example 95°C, limits the recovery capacity, 23.5 kWh, for preheating the contaminated effluent before it enters the sterilizer 103. During the subsequent cooling phase, the recovered energy, 30.3 kWh, is lower than in the first cycle because the quantity of condensate, 26.4 kg, is lower due to the preheating of the effluent, but at a higher temperature, for example 111°C, due to the higher temperature of the cold volume of the tank, for example 30°C. From the 3 èmeOnce the cycle is complete, the recovery regime begins to be established, characterized by a recovered thermal energy of 29.5 kWh during the effluent cooling phase, almost equal to the energy used to preheat the effluent, minus heat losses. Regardless of the cycle, under these operating conditions—namely, contaminated effluent with an initial temperature of 20°C and a maximum cooling temperature of 50°C for the decontaminated effluent—an advantageous sizing and design of Unit 300, and particularly of the sensible heat storage module 201, allows the process to be independent of the cooling utility.It then appears that to achieve this objective, the sensible heat storage module 201 must be significantly oversized to store the higher amount of energy during the transient start-up phase and to contain sufficient cold to ensure the cooling of the first cycle(s) before reaching a steady state. A temperature-stratified sensible heat storage module 201 has a volume of approximately 0.450 m³. 3 For example, it will be recommended to recover the energy from a sterilizer 103 of approximately 300 kg of effluent per cycle.

[0112]

[0103] One of the advantages of the invention is that, with regard to regulating the flow rate of the storage fluid, the same equipment performing this function, namely the REG-STO modulating valve or the pump 204 drive, can be used for both heat recovery and heat release phases. Alternatively, the flow control equipment will receive control commands, for example from a PLC or controllers, specific to whether it is a heat recovery or heat release phase. Similarly, as mentioned above, the temperature measurement equipment involved in regulating the flow rate of the storage fluid is not positioned in the same location depending on whether it is a heat recovery or heat release phase.

[0104] Advantageously, the pump 204 ensuring the circulation of the storage fluid can always be positioned downstream of the cold branches of the circuit, thereby limiting considerations of its temperature resistance.

[0113]

[0105] Furthermore, as shown in Figures 3 to 9, given the significant temperature variations that Unit 300 may experience, an expansion vessel 207 can advantageously be integrated into the storage fluid circuit and in permanent communication with the sensible heat storage module 201, which is the largest volume of Unit 300, so as to compensate for the volume variations inherent in the evolution of the storage fluid's density as a function of its temperature. The expansion vessel 207 compensates for the pressure variations of the storage fluid inherent in the variation of its density as a function of temperature.

[0114]

[0106] The unit 300 can be advantageously designed so that the antagonistic operation of the isolation valves ensures continuous closed-loop communication between the storage module 201, the expansion vessel 207 and the pump 204.

[0115]

[0107] In the very specific case of pharmaceutical effluent decontamination, the risk of cross-contamination is controlled by designing the system so that the more sterile fluid is always more pressurized than the less sterile fluid, particularly during the heat exchange phases between the fluids. Thus, during the heat release phase, which is the most critical in this respect, the storage fluid is maintained at a pressure higher than that of the contaminated effluent. Means of monitoring the pressure of the different fluids can be considered.

[0116]

[0108] In the event that the temperature of the storage fluid exceeds its saturation temperature at atmospheric pressure, particularly at the outlet of the recuperator 202, the unit 300 and the equipment constituting it will advantageously be pressurized so as to keep the storage fluid in a superheated liquid state.

[0117]

[0109] Advantageously, in terms of productivity and energy savings, Figures 10A to 10D further illustrate the possibility for the sterilization device 400 to share a unit 300 with two reactors, i.e., to comprise two sterilizers 103 and 103b that operate in parallel at a synchronized rate. Figure 10A illustrates the cooling of the decontaminated product exiting the unit, i.e., heat recovery and charging of the storage module 201. Figure 10B illustrates the preheating of the contaminated product before its admission to the sterilizer 103, i.e., heat release and discharge of the thermal storage. Figure 10C illustrates the cooling of the decontaminated product exiting the unit, i.e., heat recovery and charging of the storage module 201. Finally, Figure 10D illustrates the preheating of the contaminated product before its admission to the sterilizer 103b, i.e., heat release and discharge of the thermal storage.This configuration allows the recovery and valorization unit 300 to be used more by, for example, operating it on another sterilizer 103b when the first sterilizer 103, on which it has just carried out the heat recovery and restitution phases, begins the heating phase preceding the chambering phase, which are phases during which the unit 300 is not used.

[0118]

[0110] In the example shown in Figures 10A to 10D, the first sterilizer 103, interacting with unit 300, performs the emptying and cooling phases of the decontaminated effluent and then the filling and preheating phases of the contaminated effluent, while the second sterilizer 103b is in the heating and then warming phase. Then, at the beginning of its emptying and cooling phase, sterilizer 103b interacts with unit 300 while sterilizer 103 performs the heating and then warming phases.

[0119]

[0111] Thanks to thermal storage, the energy recovery and valorization solution according to the invention can overcome the constraint of simultaneous heat requirements for heating the contaminated effluent and cooling requirements for cooling the decontaminated effluent. The recovery and valorization unit according to the invention, incorporating controlled thermal storage and an interfaced hydraulic network, can offer a major advantage in terms of primary energy savings. Indeed, by reducing the use of utilities, such as steam or chilled water, essential for batch process operation, the invention can reduce primary energy consumption, namely natural gas for producing steam and electricity for producing chilled water.This reduction in primary energy consumed ultimately presents an economic and environmental gain, by contributing to the reduction of greenhouse gas emissions.

[0120]

[0112] Furthermore, the use of a recovery and energy recovery unit according to the invention can also provide other benefits since, by limiting the use of utilities, it could increase the autonomy of the decontamination process and possibly reduce cycle times, in cases where the duration of certain phases is dependent on utility availability. The decontamination process can typically be subject to this problem since the availability of cooling water and / or, to a lesser extent, steam, can constitute a significant constraint on daily treatment and production capacity at certain industrial sites. Thus, the increased autonomy with respect to utilities, achievable through the integration of the energy recovery and energy recovery unit, can also be a significant advantage for a decontamination process equipped with it.Also, the recovery and valorization unit according to the invention can make it possible to reduce the energy consumption and indirect greenhouse gas emissions of a decontamination process, in particular of pharmaceutical effluent, while increasing its autonomy from the plant's utilities and therefore possibly its effluent treatment rate.

[0121]

[0113] Consequently, the invention can provide numerous benefits: reduced steam consumption, and therefore primary energy to produce it; reduced cold water consumption, and therefore primary energy to produce it; reduced greenhouse gas emissions, resulting from the savings in primary energy consumed to produce steam and cooling water; reduced water consumption, linked to the reduction in injected steam consumption and the reduction in cooling requirements;Increased productivity and process treatment capacity, thanks to the possibility of heating the contaminated effluent during its admission to the reactor in masked time, saving time on heating and also saving time on cooling as soon as the cooling power can be greater than the cooling power of the conventional cooling section of the process and is no longer dependent on the availability of the cold utility; savings since it is possible to reduce the footprint of the reactors for the same service provided, namely the capacity of effluent treated per day and per year, and on the other hand a saving on the reactors already deployed by an increase in their production capacity and a reduction in their consumption without resorting to a new reactor;for the factory on which the unit is installed, an increase in the availability of utilities, for example steam and cold water, insofar as they are less in demand thanks to the reduction in consumption obtained by the unit according to the invention.

[0122]

[0114] Of course, the invention is not limited to the embodiments just described. Various modifications can be made to them by a person skilled in the art.

Claims

DEMANDS 1. A process for recovering and utilizing thermal energy by means of a waste heat recovery and utilization unit (300), comprising: - a sensible heat storage module (201) receiving a temperature-stratified storage fluid, - a first heat exchanger called a recuperator (202), fluidly connected to an inlet (201e) of the sensible heat storage module (201) to heat the storage fluid after heat recovery and fluidly connected to an outlet (201s) of the sensible heat storage module (201) for cooling the sterilized product, - a second heat exchanger called a preheater (203), fluidly connected to the inlet (201e) of the sensible heat storage module (201) for the release of the heat stored by the storage fluid and the heating of the product to be sterilized, and fluidly connected to the outlet (201s) of the sensible heat storage module (201) for the cooling of the storage fluid, - one or more pilot-operated isolation valves (DE-STO-FR, CH-STO-TO, CH-STO-FR, DE-STO-TO, CH-COOL-FR, CH-COOL-TO), allowing the orientation and supply or deactivation of the components of the waste heat recovery and valorization unit (300) according to the sterilization phases, the process being implemented in a batch-controlled thermal sterilization process, comprising: - a heat recovery step on the sterilized product via the heat recovery unit (202) allowing the sensible heat storage module (201) to be charged, - a heat restitution step on the product to be sterilized, in particular the contaminated effluent, by means of the preheater (203) allowing the discharge of the sensible heat storage module (201), in which, during the restitution step, the flow rate of the storage fluid circulating in the recovery and valorization unit (300) is controlled according to a predefined setpoint temperature to be reached on the temperature of the storage fluid measured at the outlet of the preheater (203).

2. Method according to claim 1, wherein the waste heat recovery and valorization unit (300) comprises a storage fluid circulation pump (204), located fluidly between the sensible heat storage module (201) and the recuperator (202), comprising in particular a differential pressure regulating valve (REG-STO).

3. Method according to claim 1 or 2, wherein the waste heat recovery and valorization unit (300) comprises one or more temperature probes (TTC-H-PO, TTC-B-RO), in particular a first temperature probe (TTC-B-RO) located at the outlet of the recuperator (202) and a second temperature probe (TTC-H-PO) located at the outlet of the preheater (203).

4. A method according to any one of the preceding claims, wherein the waste heat recovery and utilization unit (300) includes an expansion vessel (207) on the fluidic circuit of the storage fluid, in particular an expansion vessel (207) located upstream of a circulation pump for the storage fluid (204).

5. A method according to any one of the preceding claims, wherein the waste heat recovery and utilization unit (300) includes additional cooling supply means (205, 206, 206b) for cooling the sterilized product, in particular located downstream of the sensible heat storage module (201).

6. Method according to claim 5, wherein the additional cooling supply means (205, 206, 206b) comprise an additional heat exchanger (205), in particular located downstream of the recuperator (202), connected to a cold utility network.

7. Method according to claim 5 or 6, wherein the additional cooling supply means (205, 206, 206b) comprise a cooling unit (206) on the fluidic circuit of the storage fluid, in particular located downstream of the sensible heat storage module (201).

8. A method according to any one of claims 5 to 7, wherein the additional cooling supply means (205, 206, 206b) comprise a heat pump (206b), including in particular successively an evaporator (206b1) and a condenser (206b2) or the reverse.

9. A method according to any one of the preceding claims, wherein the waste heat recovery and utilization unit (300) is included in a sterilization device (400) comprising: A sterilizer (103) comprising an inlet (103e) fluidly connected to the second heat exchanger, referred to as the preheater (203), and an outlet (103s) fluidly connected to the first heat exchanger, referred to as the recuperator (202).

10. A method according to claim 9, wherein the sterilization device (400) comprises at least two sterilizers (103, 103b) mounted in parallel.

11. A method according to any one of the preceding claims, wherein, during the recovery step, the flow rate of the storage fluid circulating in the recovery unit (300) is controlled as a function of a predefined setpoint temperature to be reached on the temperature of the sterilized product measured at the outlet of the recuperator (202).

12. A method according to any one of the preceding claims, wherein, during the restitution step, the method includes the step of providing additional cooling as a function of the asymmetry between the amount of heat that can be recovered and the amount of heat that can be restored.

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