Integrated heat exchanger and acidic water stripping tower

Abstract

A combined vessel includes a stripping section for removing acidic gases from an acidic water stream and a direct-contact heat exchanger section for heating an ash water stream, to improve heat and mass transfer in water stream treatment and recirculation for gasification processes.

Description

Background Technology

[0001] The following invention relates to a process for downstream treatment of water and / or condensate streams from a partial combustion or gasification process. The upstream gasification process can be any process that produces an acidic water stream (typically a condensate stream) and an ash water stream (typically from an aerator). The most common gasification processes that achieve both are slurry-feed gasifiers that feed an aqueous slurry of solid carbonaceous fuels, and bottom-quench gasifiers that use water to quench the hot syngas product.

[0002] As used herein, the term "solid carbonaceous fuel" is intended to encompass a variety of combustible materials carrying gases and mixtures thereof, and may be selected from the group consisting of coal, coal coke, coal liquefaction residues, petroleum coke, coal dust, biomass, and particulate solids derived from oil shale, tar sands, and bituminous pitch. Coal can be of any type, including lignite, sub-bituminous coal, bituminous coal, and anthracite. Solid carbonaceous fuels may be fed to the burner as a suspension in a fluid such as a carrier gas, also known as dry feed or liquid slurry.

[0003] Solid carbonaceous fuels, such as coal, produce gases through partial combustion or gasification. These gases have long been recognized and practiced worldwide as residential and industrial fuels, as starting materials for synthetic chemicals and fuels, and as energy sources for power generation.

[0004] Acid water stripping towers are needed when impurities such as hydrogen sulfide, carbon dioxide, and ammonia accumulate in the liquid stream (typically condensate). To recycle acid water, one or more impurities must be removed in the acid water stripping tower. Of these impurities, ammonia is typically the most difficult to remove. Ash water refers to low-solids water streams from aerators, sedimentation tanks, or other chemical treatments, and typically has a fine solids concentration of less than 100 mg / m³. This contrasts with black water streams from gasifier quenching or any system that removes ash, slag, and / or soot from syngas, which typically have a fine solids concentration far exceeding 1 g / m³. The overall efficiency of the gasification process is improved when ash water is heated before recirculation, which can be achieved through indirect heat exchange with the process stream and / or steam, or through direct heat exchange, such as direct heat exchange with a high-pressure steam stream.

[0005] Bao et al. (CN 205948388U) taught an integrated high-pressure flash evaporator and direct contact heat exchanger for use in a blackwater and greywater treatment system on a gasification island. Blackwater enters the high-pressure flash section, and steam flows upward through the direct contact heat exchanger section to heat the downward-flowing greywater.

[0006] Wang et al. (CN 106587233A) taught a water and / or condensate treatment system having separate containers for an acid water stripping tower and a direct contact heat exchanger. Black water is flash-evaporated under high pressure, and the high-pressure steam heats the ash water stream in the direct contact heat exchanger. The high-pressure steam is then washed with clean water, further cooled in one or more heat exchangers, and then used as stripping gas in an acid water stripping tower where steam is used as a heat source.

[0007] Historically, the sour water stripper and ash water heater were located in different blocks or islands within a gasification plant, which may have been designed by different licensors and operated by different operators. The independent design and operation of the two islands resulted in a lack of consideration for integrating the sour water stripper and ash water heater. A streamlined water and / or condensate handling system is needed to reduce costs, save energy, and improve reliability. Summary of the Invention

[0008] This invention relates to integrating an acid water stripping tower and a direct contact heat exchanger into a combined vessel. The stripping section at the top of the vessel can use internals different from those of the direct contact heat exchanger section below. Condensate enters from the top of the vessel. Ash water may enter from the top of the vessel or above the direct contact heat exchanger section. Steam from high-pressure black water flash distillation enters the bottom of the direct contact heat exchanger section to heat the ash water stream and provide stripping gas to the stripping section. In some embodiments, high-pressure flash distillation can be integrated into a single vessel. The steam stream exits the top of the stripping section and can be condensed using internal or external condensers. The treated water stream exits the bottom of the direct contact heat exchanger section and can be recycled to the vaporizer.

[0009] Aspect 1: An apparatus for improving mass and heat transfer between multiple streams, the apparatus comprising a combined vessel including a stripping section and a direct contact heat exchanger section; wherein the stripping section is configured to contact a first acidic water stream with a stripping gas stream to generate an acid-gas-rich overhead stream and an acid-gas-depleted bottom stream; and wherein the heat exchanger section is configured to contact a high-pressure steam stream with an ash water stream and the acid-gas-depleted bottom stream to generate the stripping gas stream and the treated ash water stream.

[0010] Aspect 2: The apparatus according to aspect 1, wherein the combined container further comprises a flash section; wherein the flash section is configured to separate the black water flow to generate the high-pressure steam flow and the black water bottom flow.

[0011] Aspect 3: The apparatus according to aspect 1 or aspect 2 further comprises a condenser configured to partially condense the acid-rich overhead stream into a second acidic water stream via indirect heat exchange to produce a partially condensed overhead stream and a first acidic water stream; and a condenser separator configured to separate the partially condensed overhead stream to produce an acidic gas stream and an overhead condensate stream.

[0012] Aspect 4: The apparatus according to aspect 3, wherein the combined container comprises the condenser and the condenser separator.

[0013] Aspect 5: An apparatus for improving mass and heat transfer between multiple streams, the apparatus comprising a combined vessel including a stripping section, a direct-contact heat exchanger section, and a vertical partition wall; wherein the stripping section is configured to contact an acidic water stream with a stripping gas stream to generate a first acid-gas-rich overhead stream and an acid-gas-depleted bottom stream; wherein the heat exchanger section is configured to contact a high-pressure steam stream with an ash water stream to generate a second acid-gas-rich overhead stream and a treated ash water stream; and wherein the stripping section and the heat exchanger section are separated by the partition wall.

[0014] Aspect 6: A process for improving mass and heat transfer between multiple streams, the process comprising contacting a first acidic water stream with a stripping gas stream to generate an acid-gas-rich overhead stream and an acid-gas-depleted bottom stream; and contacting a high-pressure steam stream with an ash water stream and the acid-gas-depleted bottom stream to generate the stripping gas stream and the treated ash water stream; wherein the stripping gas stream is not cooled before contacting the first acidic water stream.

[0015] Aspect 7: The process according to aspect 6 further includes separating the black water stream to generate the high-pressure steam stream and the black water bottom stream; wherein contacting the first acidic water stream with the stripping gas stream to generate the acid-rich overhead stream and the acid-depleted bottom stream, contacting the high-pressure steam stream with the ash water stream and the acid-depleted bottom stream to generate the stripping gas stream and the treated ash water stream, and separating the black water stream to generate the high-pressure steam stream and the black water bottom stream are all carried out in a combined container.

[0016] Aspect 8: The process according to aspect 6 or aspect 7 further comprises condensing the acid-rich overhead stream by indirect heat exchange with a second acidic water stream to produce a partially condensed overhead stream and the first acidic water stream; and separating the partially condensed overhead stream to produce an acidic gas stream and an overhead condensate stream.

[0017] Aspect 9: According to the process described in Aspect 8, the acid-rich overhead stream is condensed in the combined container; and the partially condensed overhead stream is separated in the combined container.

[0018] Aspect 10: The process according to any one of aspects 6 to 9, wherein the temperature of the treated ash water stream is 0.1 to 10°C lower than the saturation temperature.

[0019] Aspect 11: A process for improving mass and heat transfer between multiple streams, the process comprising contacting a first acidic water stream with a first stripping gas stream to generate a first acid-gas-rich overhead stream and a first acid-gas-depleted bottom stream; and contacting an ash water stream with a second stripping gas stream to generate a second acid-gas-rich overhead stream and a second acid-gas-depleted bottom stream; wherein contacting the first acidic water stream with the first stripping gas stream to generate the first acid-gas-rich overhead stream and the first acid-gas-depleted bottom stream, and contacting the ash water stream with the second stripping gas stream to generate the second acid-gas-rich overhead stream and the second acid-gas-depleted bottom stream, are both carried out in a combined container.

[0020] Aspect 12: The process according to aspect 11 further includes separating the blackwater stream to generate a high-pressure steam stream and a blackwater bottom stream; wherein the second stripping gas includes at least a portion of the high-pressure steam stream.

[0021] Aspect 13: According to the process described in aspect 12, the first stripping gas comprises at least a portion of the high-pressure steam stream.

[0022] Aspect 14: The process according to any one of aspects 11 to 13, wherein the first stripping gas comprises steam.

[0023] Aspect 15: The process according to any one of aspects 11 to 14, wherein, by mass, the solid content of the bottom stream after the first acid gas depletion is lower than the solid content of the bottom stream after the second acid gas depletion. Attached Figure Description

[0024] The invention will now be described in conjunction with the following figures, wherein similar numbers denote similar elements:

[0025] Figure 1 This is a flowchart depicting the combined acidic water stripping tower and direct contact heat exchanger according to the present invention.

[0026] Figure 2 It is a description Figure 1 An improved flowchart of the embodiment is shown, in which the top condenser is integrated with the combined container.

[0027] Figure 3 It is a description Figure 1 An improved flowchart of an embodiment, in which the high-pressure separator is integrated with the combined container.

[0028] Figure 4 It is a description Figure 1 An improved flowchart of an embodiment, wherein the combined container is a partition wall tower. Detailed Implementation

[0029] The following detailed description provides only preferred exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the subsequent detailed description of preferred exemplary embodiments will provide those skilled in the art with an enabling description for implementing the preferred exemplary embodiments of the invention. Various changes may be made to the function and arrangement of the elements without departing from the spirit and scope of the invention as set forth in the appended claims.

[0030] When applied to any feature of the embodiments of the invention described in the specification and claims, the article “a” as used herein means one or more features. The use of “a” does not limit the meaning to a single feature unless such limitation is specifically stated. The article “the” preceding a singular or plural noun or noun phrase indicates a particular one or more designated features and may have a singular or plural meaning depending on the context in which it is used.

[0031] The term "and / or" between the first entity and the second entity includes any of the following meanings: (1) only the first entity, (2) only the second entity, or (3) both the first entity and the second entity. The term "and / or" between the last two entities in a list of three or more entities means that at least one entity in the list includes the list.

[0032] Any specific combination of entities. For example, "A, B and / or C" has the same...

[0033] Meaning, and including the following combinations of A, B, and C: (1) A only, (2) B only, (3) C only, (4) A and

[0034] (5) B but not C, (6) A and C but not B, and (7) A, B and C but not A.

[0035] The term "multiple" means "two or more".

[0036] The adjective "any" means any number of any one, some, or all of them.

[0037] The phrase "at least a part" means "a part or all". "At least a part of the flow" has the same composition as the flow from which it is derived, with the same concentration of each substance.

[0038] As used herein, “first,” “second,” “third,” etc., are used to distinguish multiple steps and / or features and do not indicate a total number or relative position in time and / or space, unless explicitly stated otherwise.

[0039] The terms “depleted” or “poor” mean that the molar percentage concentration of the referred component is lower than the molar percentage concentration of the original stream from which the component was formed. “Depleted” and “poor” do not mean that the stream is completely lacking in the specified component.

[0040] The terms “rich” or “abundant” mean that the molar percentage concentration of the component referred to is higher than the molar percentage concentration of the original stream that forms the component.

[0041] Figure 1 A process 1 for treating water and / or condensate in a gasification process is illustrated. An acidic water stream 102 containing one or more impurities selected from the group consisting of hydrogen sulfide, carbon dioxide, and ammonia may be heated in a condenser 140 before entering the combined vessel 100 as an acidic water stream 104. Alternatively, the acidic water stream 102 may enter directly into the top of the combined vessel 100, and the cooling load of the condenser 140 may be supplied by a heat transfer medium such as cooling water. The acidic water stream 102 may be formed from condensate leaving the acid shift zone and / or liquid discharge from an ammonia scrubber. The acid shift zone is the area where CO is converted to H2 using a water-gas shift reaction in the presence of sulfur-containing compounds (such as H2S), therefore the condensate leaving the acid shift zone will contain H2S. The ammonia scrubber uses water to wash ammonia from the syngas, producing a water stream containing ammonia and acidic gases (such as H2S and CO2).

[0042] The combined vessel 100 includes a stripping section 110 located above a direct-contact heat exchanger section 120. Both the stripping section 110 and the direct-contact heat exchanger section 120 may include column internals, such as packing and / or trays, to improve mass transfer and heat transfer, respectively. Due to the different liquid flow rates in the two sections, the column diameters may also differ, typically with a larger diameter in the direct-contact heat exchanger section 120. Compared to indirect heat exchangers, the direct-contact heat exchanger section reduces the risk of fouling and clogging.

[0043] The solids content of the grey water stream 118 imposes limitations on the tray design of the direct contact heat exchanger section 120. Because the only liquid exposed to the trays in the stripping section 110 is the solids-free acidic water stream 104, the stripping section can contain any tower internals that promote gas-liquid contact, such as floating valve trays, fixed valve trays, random packing, or structured packing. However, the solids in the grey water stream 118 pose a risk of scaling in the direct contact heat exchanger section 120, thus requiring tower internals capable of handling suspended solids in the liquid, such as fixed valve trays, strip valve trays, grid trays, and dual-flow trays.

[0044] High-pressure steam stream 106 strips the acidic gas from acidic water stream 104 and enters a combined vessel near the bottom of direct contact heat exchanger section 120, flowing upward through combined vessel 100 into stripping section 110. The bottom stream, depleted of acidic gas, exits stripping section 110 and enters direct contact heat exchanger section 120. High-pressure steam stream 106 is generated by separating black water stream 108 from the gasifier process in high-pressure separator 130, and also generates high-pressure liquid stream 112, which is then sent for further processing to further separate solids from the liquid, such as one or more flash separation stages in low-pressure and / or vacuum, and / or settling tanks (not shown). High-pressure separator 130 can be any gas-liquid separator, including multi-stage separation in flash vessels or towers. Blackwater stream 108 refers to any high-solids-content water stream (above 1 g / m³) that can be produced by a gasification process, such as a quenching process or other systems that remove solids (such as ash, slag, and / or soot) from syngas. If additional heat input is required to remove acidic gases from acidic water stream 104, this heat can be provided by steam 114 via indirect heat exchange. Steam 114 can also be mixed with high-pressure steam stream 106 before entering combined vessel 100. The resulting condensate stream 116 can be sent to a wet scrubber.

[0045] Ash water stream 118 can be fed into combined vessel 100 from the direct contact heat exchanger section 120 or the stripping section 110, or it can be mixed with acidic water stream 102. Ash water stream 118 refers to any low-solids water stream that can be produced by a gasification process (e.g., an aerator). The feeding location of ash water stream 118 can be determined based on the composition of ash water stream 118 and acidic water stream 102. For example, if the ammonia content of acidic water stream 102 is low, the risk of scaling from mixing acidic water stream 102 and ash water stream 118 is lower, and they can be mixed and fed into stripping section 110. Figure 1 In the illustrated embodiment, the greywater stream 118 enters a direct contact heat exchanger section 120, where it is heated through direct heat exchange with a high-pressure steam stream 106. The steam stream exiting the top of the direct contact heat exchanger section 120 enters a stripping section 110 without any heat exchange or other changes in pressure or composition, where it serves as a stripping gas to remove impurities from the acidic water stream 104. Using high-quality heat from the high-pressure steam stream 106 to strip the acidic water stream 104 allows for the removal of ammonia with minimal or potentially zero demand for steam 114. In contrast to prior art, which typically removes ammonia by heating with steam in a dedicated container, this invention eliminates the need for a dedicated container and performs the function within a combined container.

[0046] The treated ash water stream 122, heated to 0.1 to 10°C or 1 to 5°C below saturation temperature, exits from the bottom of the combined vessel 100. Since the typical pressure range of the treated ash water stream 122 is between 5 and 11 bara, its typical temperature will be between 150 and 185°C. The sulfur content of the treated ash water stream is typically below 100 ppm by weight. The treated ash water stream 122 can then be recycled to supply process water required in gasification processes (e.g., wet scrubbers and / or quenching vessels (not shown)). Maximizing the temperature of the treated ash water stream 122 used in the wet scrubber by increasing the temperature of the syngas exiting the wet scrubber improves the overall heat recovery of the gasification process, resulting in the recovery of a larger volume and higher quality of heat in the acid shift zone. The single treated ash water stream, which must be recycled, also eliminates the need for redundant pumps compared to separately treated ash water and treated acid water streams in the prior art.

[0047] A sour gas-rich overhead stream 124, containing stripped sour gases, exits from the top of the combined vessel 100 and is partially condensed relative to the sour water stream 102 in condenser 140. The resulting partially condensed overhead stream 126 is separated in condenser separator 150 into a sour gas stream 128 and an overhead condensate stream 132. The sour gas stream can be sent to a sulfur recovery unit, and the overhead condensate stream can be recycled to supply process water required in gasification processes (e.g., wet scrubbers and / or quenching vessels). The overhead condensate stream 132 can also be returned to the stripping section 110. Cooling water can be used to partially condense the sour gas-rich overhead stream 124, in addition to or replacing the cooling load from the sour water stream 102.

[0048] Figure 2 An embodiment of process 2 for treating water and / or condensate from a gasification process is shown, which integrates a condenser and a condenser separator into a combined vessel, and also illustrates several control features. Figure 1 Conversely, condenser 140 and condenser separator 150 are separated from combined container 100, in Figure 2 In this container, the combined vessel 200 includes a condenser 260 that performs both indirect heat exchange and vapor-liquid separation. The combined vessel 200 also includes a stripping section 210 below the condenser 260 and a direct contact heat exchanger section 220 below the stripping section 210. Figure 1 As shown, both the stripping section 210 and the direct contact heat exchanger section 220 may include packing and / or trays to improve mass transfer and heat transfer, respectively. When one or more feed streams from the combined vessel contain high solids content, trays, such as fixed valve trays, may be used.

[0049] Acidic water stream 102 containing sulfur-containing gases (such as hydrogen sulfide) is heated in condenser 260 before entering combined container 200 as acidic water stream 204. Figure 1As shown, a heat transfer medium (such as cooling water) can provide a cooling load for condenser 260, and acidic water stream 202 can directly enter combined vessel 200. Acidic water stream 202 can be formed from condensate leaving the gasification process conversion zone. Acidic water stream 204 enters combined vessel 200 above stripping section 210.

[0050] High-pressure steam stream 206 strips the acidic gas from acidic water stream 204 and enters a combined container near the bottom of direct contact heat exchanger section 220, flowing upward through combined container 200 into stripping section 210. Steam 214 can be mixed with high-pressure steam stream 206 before entering heat exchanger section 220, or it can be added directly to heat exchanger section 220. The bottom stream, depleted of acidic gas, exits stripping section 210 and enters direct contact heat exchanger section 220.

[0051] The grey water stream 118 can be fed into the combined vessel 200 from the direct contact heat exchanger section 220 or the stripping section 210, or mixed with the acidic water stream 202. Figure 2 In the illustrated embodiment, the grey water stream 118 enters the direct contact heat exchanger section 220, where it is heated through direct heat exchange with the high-pressure steam stream 206. The grey water stream 118 refers to any low-solids water stream that can be produced by a gasification process (e.g., an aerator).

[0052] The treated greywater stream 222, heated to 0.1 to 10°C or 1 to 5°C below saturation temperature, exits from the bottom of the combined vessel 200. Since the typical pressure range of the treated greywater stream 222 is between 5 and 11 bara, the typical temperature of the treated greywater stream 222 will be between 150 and 185°C. The sulfur content of the treated greywater stream is typically less than 100 ppm by weight. The treated greywater stream 222 can optionally be pumped in pump 225 for recirculation as pumped treated greywater stream 234, or can be recirculated as treated greywater stream 222 if higher pressure is not required. The level controller shown is connected to control valve 235 to maintain the liquid level at the bottom of the direct contact heat exchanger section 220 at a constant height.

[0053] The acidic gas-rich overhead stream exits the top of the stripping section 210 and is partially condensed and separated relative to the acidic water stream 202 in the condenser 260, producing an acidic gas stream 228 and an overhead condensate stream. This acidic gas stream can be sent to the sulfur recovery unit, and the overhead condensate stream re-enters the stripping section 210. A pressure controller at the top of the combined vessel 200 controls valve 215 to maintain a constant pressure in the combined vessel.

[0054] like Figure 3As shown, the combined vessel may further include a high-pressure separator. Here, process 3 is essentially similar to process 1. The combined vessel 300 includes a stripping section 310 that receives acidic water stream 104, a direct contact heat exchanger section that receives ash water stream 118, and a high-pressure separator section 330 that receives black water stream 108. The high-pressure steam stream exits the high-pressure separator section 330 and enters the direct contact heat exchanger system, contacting the ash water stream 118 and the acidic water stream 104.

[0055] The overhead stream 124, rich in acidic gases, exits the top of the combined container and partially condenses, as... Figure 1 As described. Figure 1 As shown, the high-pressure liquid stream 312 exits the bottom of the high-pressure separator section 330 and is then sent for further processing to further separate solids from the liquid, such as in one or more flash separation stages in a low-pressure and / or vacuum, and / or settling tank. The treated ash water stream 322 exits the bottom of the direct contact heat exchanger section 320, having been heated to 0.1 to 10°C or 1 to 5°C below the saturation temperature. Figure 3 An optional side outlet exiting the combined vessel 300 is shown, where condensate stream 316 is extracted and used as a low-solids process water stream to quench the hot stream and wash away impurities and / or solids from the gas stream, and / or rinsing equipment. The condensate stream 316 can be increased by adding shift condensate 342 from the syngas cooled at a higher temperature, which is expected to contain a lower concentration of impurities.

[0056] In addition to dividing the composite container into vertically stacked segments, you can also use, for example... Figure 4 The process 4 is implemented using a partitioned-wall tower, wherein a combined vessel 400 is used, with partition walls 460 dividing it into a stripping section 410 and a direct-contact heat exchanger section 420. Acidic water stream 104 enters the top of the stripping section 410 and contacts steam 414 and / or a portion of high-pressure steam stream 106A entering near the bottom of the stripping section 410. Treated condensate stream 416 exits the bottom of the stripping section 410 and can be used as a low-solids process water stream to quench the hot flow and wash impurities and / or solids from the gas stream and / or flushing equipment. Ash water stream 118 enters the direct-contact heat exchanger section 420 and contacts high-pressure steam stream 106. Treated ash water stream 422 exits the bottom of the direct-contact heat exchanger section 420 and can be used in a wet scrubber. High-pressure steam stream 106 and steam 414 mix at the top of the combined vessel and exit as an acid-rich overhead stream 124. This arrangement allows for the removal of impurities from the acidic water stream 104 without increasing solids from the ash water stream 118, and provides two process water streams: a treated ash water stream 422 with low solids content by mass, and a treated condensate stream 416 with substantially zero solids content by mass. Figure 1 Compared to vertical integration, horizontal integration of two segments saves height.

[0057] Example

[0058] Computer simulations of a dry-feed gasification process consuming 3,000 tons of coal per day were performed using Aspen Plus, a commercial process simulation software package available from Aspen Technology, Inc. For use... Figure 1 A comparison of low-pressure steam consumption rates for recirculating black water, grey water, and acid water was made between a combined container system and a system using separate containers for acid water stripping and grey water heating. The combined container system reduced low-pressure steam consumption by 400 tons per day compared to a baseline consumption rate of 3,000 tons per day for separate containers. Significant savings in utility costs were also achieved, in addition to eliminating redundant equipment (such as pumps for two separate circulating water systems).

[0059] Similar steam savings were observed under other conditions, such as when using slurry feed in combined vessels, the baseline low-pressure steam consumption rate of 3,000 tons per day was reduced by 300 tons per day.

[0060] Although the principles of the invention have been described above in conjunction with preferred embodiments, it should be clearly understood that this description is merely exemplary and not intended to limit the scope of the invention.

Claims

1. An apparatus for improving mass and heat transfer between multiple streams, the apparatus comprising: A combined container, the combined container comprising a stripping section, a direct contact heat exchanger section, a condenser, and a condenser separator; The stripping section is configured to contact the first acidic water flow with the stripping gas flow to generate an overhead flow rich in acidic gas and a bottom flow where the acidic gas is depleted. The heat exchanger section is configured to contact the high-pressure steam stream with the ash water stream and the bottom stream after the acid gas has been depleted, in order to generate the stripping gas stream and the treated ash water stream. The condenser is configured to partially condense the acid-rich overhead stream through indirect heat exchange with a second acidic water stream, thereby producing a partially condensed overhead stream and the first acidic water stream; and The condenser separator is configured to separate the partially condensed overhead stream to produce an acidic gas stream and an overhead condensate stream.

2. The apparatus of claim 1, wherein the combined container further comprises a flash evaporation section; The flash section is configured to separate the black water flow to generate the high-pressure steam flow and the black water bottom flow.

3. A process for improving mass and heat transfer between multiple streams, characterized in that... The process is carried out using the equipment according to claim 1 or 2, and includes: In the stripping section of the combined vessel, the first acidic water flow is brought into contact with the stripping gas flow to produce an overhead flow rich in acidic gas and a bottom flow where the acidic gas is depleted. In the direct contact heat exchanger section of the combined container, a high-pressure steam stream is contacted with an ash water stream and a bottom stream from which the acidic gas has been depleted to generate the stripping gas stream and the treated ash water stream, wherein the stripping gas stream is not cooled before contacting the first acidic water stream. In the condenser of the combined container, the acid-rich overhead stream is partially condensed through indirect heat exchange with a second acidic water stream, resulting in a partially condensed overhead stream and the first acidic water stream; and In the condenser separator of the combined container, the partially condensed overhead stream is separated to produce an acidic gas stream and an overhead condensate stream.

4. The process according to claim 3, further comprising: The black water stream is separated to generate the high-pressure steam stream and the black water bottom stream; The process of contacting the first acidic water stream with the stripping gas stream to generate the acid-rich overhead stream and the acid-depleted bottom stream, contacting the high-pressure steam stream with the ash water stream and the acid-depleted bottom stream to generate the stripping gas stream and the treated ash water stream, and separating the black water stream to generate the high-pressure steam stream and the black water bottom stream are all carried out in the combined container.

5. The process according to claim 3, wherein the temperature of the treated greywater stream is between 0.1°C and 10°C below the saturation temperature.

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