CN114791240A - Waste heat recycling system and method based on supercritical hydrothermal combustion technology - Google Patents

Abstract

The invention discloses a waste heat recycling system and method based on supercritical water heat combustion technology, comprising a reactor, wherein the reactor comprises a cylinder, an upper end cover and a lower end cover; a multi-stage heat collector and a material preheater are arranged in the barrel, a reaction product outlet is arranged at the upper part, and a salt discharge outlet is arranged at the lower part; the reaction chamber is connected with a softening water tank, an oxidant unit and an alcohol auxiliary agent unit; the material preheater is connected with the softening water tank and the material unit; the outer wall surface of the lower end cover is provided with a water cooling sleeve, the water cooling sleeve is connected with a desalting water tank, an outlet of the water cooling sleeve is connected with an inlet of the multistage heat collector, an outlet of the multistage heat collector is connected with a saturated steam collecting unit, and the saturated steam collecting unit is connected with the desalting water tank. The reactor only needs to be internally provided with the heat exchanger for flowing the single fluid, and meanwhile, the inorganic salt is separated before the reaction product passes through the subsequent heat exchanger, so that the corrosion of the inorganic salt to the heat exchanger material is reduced, and the investment cost of the whole heat exchanger in the system is obviously reduced.

Description

Waste heat recycling system and method based on supercritical water heat combustion technology

Technical Field

The invention belongs to the technical field of chemical industry and environmental protection, and relates to a waste heat recycling system and method based on a supercritical water heat combustion technology.

Background

With the continuous development of industry, organic waste liquid generated in the industrial process is increased year by year, particularly from the industries of pesticide, pharmacy, textile printing and dyeing, coal chemical industry and the like, and the generated waste liquid has the defects of complex organic matter components, high concentration, high content of inorganic salt, strong toxicity and poor biodegradability, and is difficult to degrade by a conventional treatment method. If the waste liquid which does not reach the standard is directly discharged, harmful substances in the waste liquid cause serious pollution to the land and water environment and harm to human health.

At present, the treatment method of the high-concentration high-salt organic waste liquid mainly comprises a biochemical method. However, for the difficult-to-degrade organic wastewater with high difficulty, the COD of the organic wastewater is too high, and the organic wastewater may contain heavy metal substances and high-concentration inorganic salts, which all have biological toxicity, so that the wastewater is difficult to be treated by a biological method, nitrogen-containing organic matters in the wastewater cannot be removed, and the ammonia nitrogen discharge index of the wastewater cannot be reached.

Supercritical hydrothermal combustion (SCHC) technology is a promising technology for treating high-concentration high-salt organic waste liquid. The technology utilizes the special property of water in a supercritical state (the temperature is more than 374.1 ℃, and the pressure is more than 22.1MPa), supercritical water is used as a reaction medium of organic matters and oxygen, certain alcohol auxiliary agents are added to promote the high-concentration high-salt organic waste liquid to directly generate supercritical water heat combustion reaction, refractory organic pollutants are quickly and thoroughly destroyed, C, H and N elements in the organic matters are respectively converted into harmless CO ₂ 、H ₂ O、N ₂ Heterocyclic atoms such as Cl, S and P are respectively converted into corresponding inorganic acid or salt, heavy metals are mineralized into stable solid phase and exist in residues, and high concentration are realizedAnd (4) carrying out harmless treatment on the salt organic waste liquid.

However, when supercritical hydrothermal combustion technology is used for treating high-concentration high-salinity organic waste liquid, some problems exist: when a conventional system for treating high-concentration high-salinity organic waste liquid by supercritical hydrothermal combustion runs, a preheater and a regenerator are required to be arranged in a material pretreatment unit and a product subsequent treatment unit separately. The preheater that sets up alone at present is mostly sleeve pipe heat exchanger with regenerator common form, and the fluid of the interior outer pipe of sleeve pipe heat exchanger of flowing through mostly contains salt fluid for the high pressure, and is stronger to the corrosivity of heat exchanger, and this wall thickness that makes preheater and regenerator increases, leads to heat exchanger investment cost high, and the heat exchanger that sets up alone also has certain heat loss moreover. In addition, the conventional system can generate salt crystallization deposition due to the overhigh temperature inside the reactor during operation, and the safe operation of the equipment and the system is influenced.

Disclosure of Invention

The invention aims to solve the problems that in the prior art, when a supercritical water thermal combustion system is used for treating high-concentration high-salt organic waste liquid, an independent preheater and a heat regenerator are high in investment cost, large in heat loss and prone to salt crystallization and deposition inside a reactor, and provides a waste heat recycling system and a waste heat recycling method based on a supercritical water thermal combustion technology.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a waste heat recycling system based on a supercritical water heat combustion technology comprises a supercritical water heat combustion reactor, wherein the supercritical water heat combustion reactor comprises a cylinder body, an upper end cover is arranged at the upper part of the cylinder body, and a lower end cover is arranged at the lower part of the cylinder body; the interior of the cylinder body is a reaction chamber, and a multi-stage heat collector and a material preheater are arranged; the upper end cover is provided with a reaction product outlet, and the lower part of the lower end cover is provided with a salt discharge outlet; the reaction chamber is connected with a softening water tank, an oxidant unit and an alcohol auxiliary agent unit; the material preheater is connected with the softening water tank and the material unit; the outer wall surface of the lower end cover is provided with a water cooling jacket, a desalting water tank is connected to the water cooling jacket, an outlet of the water cooling jacket is connected with an inlet of the multistage heat collector, an outlet of the multistage heat collector is connected with a saturated steam collecting unit, and the saturated steam collecting unit is connected with the desalting water tank.

The system is further improved in that:

the upper end cover is provided with a supercritical water inlet, an oxidant inlet, an alcohol auxiliary agent inlet and a material inlet; the outlet of the softening water tank is connected with a high-pressure softening water pump, and the outlet of the high-pressure softening water pump is respectively connected with the heating device and the inlet of the material preheater; the oxidant unit is connected with an oxidant inlet; the alcohol auxiliary agent unit is connected with the alcohol auxiliary agent inlet; and the outlet of the material preheater is connected with the material inlet.

And the reaction product outlet is connected with the product pressure reduction and separation module.

The multistage heat collector comprises a first-stage heat collector, a second-stage heat collector, a third-stage heat collector and a fourth-stage heat collector; the inlet of the third-stage heat collector is connected with the outlet of the water cooling jacket, and the outlet is connected with the fourth-stage heat collector; an outlet of the fourth-stage heat collector is connected with an end cover cooler, and the end cover cooler is arranged in an upper end cover; the outlet of the end cover cooler is connected with a secondary heat collector, the outlet of the secondary heat collector is connected with a primary heat collector, and the outlet of the primary heat collector is connected with a saturated steam collecting unit.

The saturated steam collecting unit comprises a gas-liquid separator, a gas outlet of the gas-liquid separator is connected with a steam collecting device, and a liquid outlet of the gas-liquid separator is connected with a desalting water tank.

The outlet of the desalting water tank is connected with the first low-pressure desalting water pump and the second low-pressure desalting water pump, and the outlets of the first low-pressure desalting water pump and the second low-pressure desalting water pump are connected to the inlet of the water cooling jacket.

The reaction chamber is divided into five reaction zones which are sequentially communicated, and an inorganic salt recovery chamber is arranged inside the lower end cover; the supercritical water inlet, the oxidant inlet, the alcohol auxiliary agent inlet and the material inlet are communicated with a first reaction area, and the first reaction area is communicated with the inorganic salt recovery chamber; the first-stage heat collector is arranged in the first reaction zone and the second reaction zone, the second-stage heat collector is arranged in the third reaction zone, the material preheater is arranged in the fourth reaction zone, and the third-stage heat collector and the fourth-stage heat collector are arranged in the fifth reaction zone; the reaction product outlet is communicated with the fifth reaction area, and the salt discharge outlet is communicated with the inorganic salt recovery chamber.

The flow direction of cold fluid in the first-stage heat collector, the second-stage heat collector, the material preheater, the third-stage heat collector and the fourth-stage heat collector is in counter-current arrangement with the flow direction of hot fluid of a reaction product in the supercritical hydrothermal combustion reactor; the first-stage heat collector, the second-stage heat collector, the material preheater, the end cover cooler, the third-stage heat collector and the fourth-stage heat collector adopt a membrane wall heat exchanger, a coil heat exchanger, a serpentine heat exchanger or a spiral heat exchanger.

The first reaction zone is communicated with the second reactor through an inorganic salt filtering device; the salt discharge outlet is connected with an inorganic salt recycling module.

A waste heat recycling method based on a supercritical water heat combustion technology comprises the following steps:

step 1, introducing cold materials into a material preheater from a material unit, and interlocking a material preheating outlet temperature measuring point with a heating device, a first regulating valve, a second regulating valve and a high-pressure softening water pump;

when the temperature of a material preheating outlet temperature measuring point is monitored to be lower than a low-temperature threshold value, starting a high-pressure softening water pump, a first switch valve, a second switch valve and a heating device, injecting supercritical water into the supercritical water thermal combustion reactor, and increasing the frequency of the heating device; after the temperature of the supercritical water is increased to a preset temperature, the opening degree of a second regulating valve is increased until the supercritical water heat combustion reaction is normally carried out;

when the temperature of a material preheating outlet temperature measuring point is monitored to exceed a high-temperature threshold, if supercritical water is injected into the supercritical water thermal combustion reactor at the moment, the opening degree of a second regulating valve is reduced until the flow of the supercritical water is reduced to zero; if the temperature of the material preheating outlet temperature measuring point still exceeds the high-temperature threshold value, increasing the opening degree of a first regulating valve, and injecting cooling water into the material preheater until the temperature of the material preheating outlet temperature measuring point is restored to the normal temperature; meanwhile, if salt crystallization occurs in the material preheater, the opening degree of the first regulating valve and the frequency of the high-pressure softening water pump are increased, and the material preheater is flushed until the supercritical hydrothermal combustion reaction is normally carried out;

step 2, introducing the preheated material, the oxidant and the alcohol auxiliary agent into a supercritical hydrothermal combustion reactor through a material inlet, an oxidant inlet and an alcohol auxiliary agent inlet respectively to perform supercritical hydrothermal combustion reaction, filtering high-temperature and high-pressure reaction products generated by the reaction by an inorganic salt filtering device to obtain inorganic salt and liquid-phase products, allowing the inorganic salt to enter an inorganic salt recovery chamber, allowing the liquid-phase products to sequentially exchange heat with a first-stage heat collector, a second-stage heat collector, a material preheater, a third-stage heat collector and a fourth-stage heat collector, and allowing the liquid-phase products to finally enter a product pressure reduction separation module through a reaction product outlet;

step 3, when the step 2 is carried out, a first low-pressure desalting water pump and a third switch valve are started, cooling water is injected into a water cooling jacket on the outer side of the lower end cover, and then the cooling water sequentially enters a three-stage heat collector, a four-stage heat collector, an end cover cooler, a two-stage heat collector and a one-stage heat collector to exchange heat with a reaction product;

in the process of the step 2 and the step 3, if the temperature of any one of the first temperature measuring point, the second temperature measuring point, the third temperature measuring point, the fourth temperature measuring point, the fifth temperature measuring point, the sixth temperature measuring point or the seventh temperature measuring point is monitored to exceed a high-temperature threshold value, the operating frequency of the first low-pressure desalted water pump is increased until the monitored temperature point is restored to be within a normal range; if the temperature of any temperature measuring point exceeds the high-temperature threshold value when the first low-pressure desalted water pump runs at full load, the second low-pressure desalted water pump is started, the fourth switch valve is opened, the two pumps are connected in parallel and run simultaneously, and the running frequency of the second low-pressure desalted water pump is increased until any temperature measuring point returns to normal;

step 4, steam generated after the low-pressure cooling water and the high-temperature high-pressure reaction product are subjected to step-by-step heat exchange enters a gas-liquid separator; a third pressure regulating valve is arranged on an outlet pipeline of the steam at the top of the gas-liquid separator, the pressure of the steam flowing out is controlled by regulating the opening degree of the third pressure regulating valve, so that the steam finally passing through the third pressure regulating valve is saturated steam, and the finally saturated steam flows out and enters a steam collecting device for next utilization;

when the desalted water in the gas-liquid separator reaches the high liquid level set by the liquid level monitoring point, the fourth regulating valve on the water outlet pipeline at the bottom of the gas-liquid separator is opened, and the desalted water is injected into the desalted water tank until the liquid level monitoring point reaches the normal liquid level range.

Compared with the prior art, the invention has the following beneficial effects:

in the invention, the heat regenerator and the preheater are both concentrated in the reactor, only a heat exchanger for flowing single fluid is needed to be arranged in the reactor, and meanwhile, inorganic salt is separated before reaction products pass through a subsequent heat exchanger, so that the corrosion of the inorganic salt to the heat exchanger material is reduced, and the investment cost of the whole heat exchanger in the system is obviously reduced. The invention directly cools the high-temperature high-pressure reaction product to the low-temperature high-pressure liquid-phase product in the reactor, and simultaneously immediately separates inorganic salt from the reaction product after the reaction is finished, thereby reducing the requirements of the pressure-bearing wall of the reactor on high-temperature-resistant and corrosion-resistant materials and obviously reducing the investment cost of the reactor. According to the invention, the problem of salt crystallization and deposition in the material preheater in the reactor can be avoided on line while the high-concentration high-salt organic waste liquid is ensured to smoothly generate supercritical hydrothermal combustion reaction to degrade organic matters through the interlocking control of the material preheating temperature, and the reliability of system operation is improved. The invention can realize the automatic control of the wall temperature of each heat exchanger in the reactor, the wall temperature of the pressure-bearing wall surface of the reactor and the wall temperature of the end cover of the reactor, ensure that a reaction system does not exceed the temperature and improve the safety and the reliability of the operation of the system.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

FIG. 1 is a schematic view of the reaction system of the present invention.

Wherein, 1-a softened water tank, 2-a high-pressure softened water pump, 3-a heating device, 4-an oxidant unit, 5-an alcohol auxiliary agent unit, 6-a material unit, 7-a supercritical hydrothermal combustion reactor, 8-an upper end cover, 9-a lower end cover, 10-a first-level heat collector, 11-a second-level heat collector, 12-an end cover cooler, 13-a material preheater, 14-a third-level heat collector, 15-a fourth-level heat collector, 16-an inorganic salt filtering device, 17-an inorganic salt recycling chamber, 18-a water cooling jacket, 19-an inorganic salt recycling module, 20-a desalted water tank, 21-a first low-pressure desalted water pump, 22-a second low-pressure desalted water pump, 23-a product depressurization separation module and 24-a gas-liquid separator, 25-steam collecting device, V1-first switch valve, V2-second switch valve, V3-third switch valve, V4-fourth switch valve, V5-first regulating valve, V6-second regulating valve, V7-third regulating valve, V8-fourth regulating valve, N1-supercritical water inlet, N2-oxidant inlet, N3-alcohol auxiliary agent inlet, N4-material inlet, N5-reaction product outlet and N6-salt discharge outlet.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used solely to distinguish one from another, and are not to be construed as indicating or implying relative importance.

Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1, an embodiment of the invention discloses a waste heat recycling system based on a supercritical hydrothermal combustion technology, which comprises a softened water unit, a desalted water unit, an oxidant unit, an alcohol auxiliary agent unit, a material unit, a supercritical hydrothermal combustion reactor and a saturated steam collection unit.

Demineralized water unit, including consecutive softened water tank 1, high-pressure softened water pump 2, the export of high-pressure softened water pump 2 divide into two the tunnel, links to each other with 3 entrys of heating device all the way, and 3 exports of heating device and links to each other with supercritical water entry N1 of supercritical hydrothermal combustion reactor 7, and another way links to each other with material pre-heater 13 inlet line.

The outlet pipeline of the material preheater 13 is provided with a temperature monitoring point TIC101 which is interlocked with the first regulating valve V5, the second regulating valve V6, the high-pressure softening water pump 2 and the heating device 3 respectively. Temperature monitoring points TIC201, TIC202, TIC203, TIC204, TIC205, TIC206 and TIC207 are respectively arranged on the pressure-bearing wall surface of the upper end cover 8, the inner side wall surface of the supercritical water heat combustion reactor 7, the pressure-bearing wall surface of the lower end cover 9, the wall surface of the primary heat remover 10, the wall surface of the secondary heat remover 11, the wall surface of the material preheater 13 and a pipeline N5 of a reaction product outlet, and are respectively linked with the first low-pressure desalted water pump 21 and the second low-pressure desalted water pump 22. The liquid level monitoring point LIC101 of the gas-liquid separator 24 is interlocked with the fourth regulating valve V8, and the pressure monitoring point PIC101 of the gas-liquid separator 24 is interlocked with the third regulating valve V7.

The desalting water unit comprises a desalting water tank 20, a first low-pressure desalting water pump 21 and a second low-pressure desalting water pump 22, wherein the outlet of the desalting water tank 20 is divided into two paths, one path is connected with the inlet of the first low-pressure desalting water pump 21, the outlet of the first low-pressure desalting water pump 21 is connected with the inlet of a water cooling jacket 18 of the supercritical water hot combustion reactor 7, the other path is connected with the inlet of the second low-pressure desalting water pump 22, and the outlet of the second low-pressure desalting water pump 22 is connected with the outlet pipeline of the first low-pressure desalting water pump 21.

And the outlet of the oxidant unit 4 is connected with an oxidant inlet N2 of the supercritical hydrothermal combustion reactor 7.

An outlet of the alcohol auxiliary unit 5 is connected with an alcohol auxiliary inlet N3 of the supercritical water heat combustion reactor 7. The alcohol auxiliary agent includes but is not limited to alcohols such as methanol, ethanol, ethylene glycol, isopropanol and the like.

The outlet of the material unit 6 is connected with the inlet of a material preheater 13.

An end cover cooler 12 is arranged in an upper end cover 8 of the supercritical water heat combustion reactor 7; a first-stage heat collector 10, a second-stage heat collector 11, a material preheater 13, a third-stage heat collector 14, a fourth-stage heat collector 15 and an inorganic salt filtering device 16 are arranged in the reactor; the outer wall surface of the lower end cover 9 is provided with a water cooling jacket 18. The outlet of the water cooling jacket 18 is connected with the inlet and outlet of the third-stage heat collector 14, the fourth-stage heat collector 15, the end cover cooler 12, the second-stage heat collector 11 and the first-stage heat collector 10 in sequence, and the outlet of the first-stage heat collector 10 is connected with the steam inlet of the gas-liquid separator 24.

The upper end cover 8 is provided with a supercritical water inlet N1, an oxidant inlet N2, an alcohol auxiliary agent inlet N3, a material inlet N4 and a reaction product outlet N5. The reaction product outlet N5 of the supercritical hydrothermal combustion reactor 7 is connected with the product depressurization separation module 23. An inorganic salt recovery chamber 17 is arranged in a lower end cover 9 of the supercritical water heating combustion reactor 7, and a salt discharge outlet N6 at the bottom is connected with an inorganic salt recovery and utilization module 19.

The cold fluid flow direction in the first-stage heat remover 10, the second-stage heat remover 11, the material preheater 13, the third-stage heat remover 14 and the fourth-stage heat remover 15 and the hot fluid of the reaction product in the reactor are all arranged in a counter-current mode. The heat exchangers of the first-stage heat collector 10, the second-stage heat collector 11, the material preheater 13, the end cover cooler 12, the third-stage heat collector 14, the fourth-stage heat collector 15 and the like include but are not limited to the forms of membrane walls, coil pipes, coiled pipes, spiral pipes and the like.

And the saturated steam collecting unit comprises a gas-liquid separator 24, a steam outlet of the gas-liquid separator 24 is connected with a steam collecting device 25, and a bottom water outlet of the gas-liquid separator 24 is connected with a desalted water inlet of the desalted water storage tank 20.

The embodiment of the invention also discloses a waste heat recovery method based on the supercritical water heat combustion technology, which comprises the following steps:

step 1: in the normal operation process, firstly, cold materials are led into the material preheater 13 from the material unit 6, and a material preheating outlet temperature measuring point TIC101 is linked with the heating device 3, the first regulating valve V5, the second regulating valve V6 and the high-pressure softening water pump 2.

When the monitored material preheating temperature TIC101 is too low, the high-pressure softening water pump 2, the first switch valve V1, the second switch valve V2 and the heating device 3 are started, supercritical water is injected into the supercritical water thermal combustion reactor 7, and the frequency of the heating device 3 is gradually increased by a certain range. After the temperature of supercritical water improved to certain degree, with certain range gradual increase second governing valve V6's aperture, normally gone on until the supercritical water heat combustion reaction.

When monitoring that material preheating temperature TIC101 is too high, if there is supercritical water to inject into in supercritical water thermal combustion reactor 7 this moment, then reduce the aperture of second governing valve V6 step by step with certain range, fall for zero until the flow of supercritical water. If the material preheating temperature TIC101 is still too high, the opening degree of the first regulating valve V5 is gradually increased by a certain range, and cooling water is injected into the material preheater 13 until the material preheating temperature TIC101 returns to the normal temperature. Meanwhile, if salt crystallization occurs in the material preheater 13 due to overhigh temperature, the opening degree of the first regulating valve V5 and the frequency of the high-pressure softening water pump 2 can be further increased step by step, and the material preheater 13 is flushed until the supercritical hydrothermal combustion reaction is maintained to be normally performed.

Step 2: the preheated material, oxidant and alcohol auxiliary agent are respectively introduced into the reactor through a material inlet N4, an oxidant inlet N2 and an alcohol auxiliary agent inlet N3 to carry out supercritical hydrothermal combustion reaction, high-temperature and high-pressure reaction products generated by the reaction are filtered by an inorganic salt filtering device 16, inorganic salt enters an inorganic salt recovery chamber 17, the liquid-phase products sequentially exchange heat with a first-stage heat collector, a second-stage heat collector, a material preheater, a third-stage heat collector and a fourth-stage heat collector, and finally enter a product pressure reduction separation module 23 through a reaction product outlet N5.

And step 3: and (2) when the step 2 is normally carried out, starting the first low-pressure desalting water pump 21 and the third on-off valve V3, injecting cooling water into the water cooling jacket 18 on the outer side of the lower end cover 9, and then sequentially entering the third-stage heat collector 14, the fourth-stage heat collector 15, the end cover cooler 12, the second-stage heat collector 11 and the first-stage heat collector 10 to exchange heat with reaction products.

In the process of the step 2 and the step 3, if any one of the temperature measuring points TIC201, TIC202, TIC203, TIC204, TIC205, TIC206 and TIC207 is monitored to be over-temperature, the operating frequency of the first low-pressure desalted water pump 21 is gradually increased by a certain amplitude until the monitored temperature point returns to the normal range; if any temperature monitoring point still has overtemperature when the first low-pressure desalted water pump 21 runs at full load, the second low-pressure desalted water pump 22 is started, the fourth switching valve V4 is opened, the two pumps run in parallel and simultaneously, and the running frequency of the second low-pressure desalted water pump 22 is increased gradually by a certain amplitude until any temperature monitoring point returns to normal.

And 4, step 4: based on the step 3, steam generated by the step-by-step heat exchange between the low-pressure cooling water and the high-temperature high-pressure reaction product enters the gas-liquid separator 24. A third pressure regulating valve V7 is arranged on an outlet pipeline of the steam at the top of the gas-liquid separator 24, the pressure of the steam flowing out is controlled by regulating the opening degree of the third pressure regulating valve V7, the steam finally passing through the third pressure regulating valve V7 is ensured to be saturated steam under specific pressure all the time, and the finally saturated steam flows out and enters the steam collecting device 25 for next utilization.

When the desalted water in the gas-liquid separator 24 reaches the high liquid level set by the liquid level monitoring point LIC101, the fourth regulating valve V8 on the water outlet pipeline at the bottom of the gas-liquid separator 24 is gradually opened by a certain amplitude, and the desalted water is injected into the desalted water tank 20 until the liquid level monitoring point LIC101 reaches the normal liquid level range.

The embodiment is as follows:

in this embodiment, a supercritical hydrothermal combustion technology is used to treat a high-concentration high-salt organic waste liquid, and ethanol is used as an alcohol auxiliary agent, and a waste heat recovery system and a method based on the supercritical hydrothermal combustion technology are described in detail:

(1) in the normal operation process of the system, the self-heating of the high-concentration high-salt organic waste liquid system can be completely realized, and no external heat source is required in the normal operation process. The high-concentration high-salinity organic waste liquid firstly enters the material preheater 13 from the material unit 6, the high-temperature high-pressure reaction product preheats the high-concentration high-salinity organic waste liquid to 320 ℃, and meanwhile, a material preheating outlet temperature measuring point TIC101 is interlocked with the electric heater 3, the first regulating valve V5, the second regulating valve V6 and the high-pressure softening water pump 2 in the normal operation process of the system.

(2) When the material preheating temperature TIC101 is monitored to be far lower than 320 ℃, the high-pressure softening water pump 2, the first switch valve V1, the second switch valve V2 and the heating device 3 are started, supercritical water is injected into the reactor through the supercritical water inlet N1 of the upper end cover 8, the frequency of the heating device 3 is increased step by 5% of the amplitude, the temperature of the injected supercritical water is increased, after the temperature of the supercritical water is increased to be more than 600 ℃, the opening degree of the second regulating valve V6 is increased step by 5% of the amplitude, and the amount of the injected supercritical water is increased until the heat combustion reaction is normally carried out.

(3) When the material preheating temperature TIC101 is higher than 320 ℃ and if supercritical water is injected into the supercritical water heat combustion reactor (7), the opening degree of the second regulating valve V6 is gradually reduced by 5%, the amount of the injected supercritical water is reduced, and the flow of the direct supercritical water is reduced to zero. If the material preheating temperature TIC101 is still too high, the opening degree of the first adjusting valve V5 is gradually increased by 5%, cooling water with the temperature of 20 ℃ and the pressure of 25MPa is injected into the inlet pipeline of the material preheater 13, and the high-concentration high-salt organic waste liquid is cooled until the material preheating temperature TIC101 is recovered to 320 ℃. Simultaneously, if in the material preheater 13 because material preheating temperature TIC101 is too high and take place the salt crystallization, can further progressively increase first governing valve V5's aperture and high pressure softening water pump 2's frequency, wash material preheater 13 until maintaining the supercritical water heat combustion reaction and normally going on.

(4) The high-concentration high-salt organic waste with the temperature of 320 ℃ after preheating, an oxidant and ethanol are respectively introduced into the reactor through a material inlet N4, an oxidant inlet N2 and an alcohol auxiliary agent inlet N3 to carry out supercritical hydrothermal combustion reaction, high-temperature high-pressure reaction products generated by the reaction are filtered by an inorganic salt filtering device 16, inorganic salt enters an inorganic salt recovery chamber 17, the liquid-phase products sequentially exchange heat with a first-stage heat collector, a second-stage heat collector, a material preheater, a third-stage heat collector and a fourth-stage heat collector, and are finally cooled to 20 ℃ and enter a product pressure reduction separation module 23 through a reaction product outlet N5.

(5) When the reaction is normally carried out, the first low-pressure desalting water pump 21 and the third on-off valve V3 are required to be started, cooling water with the temperature of 20 ℃ and the pressure of 0.8MPa is injected into the water cooling jacket 18 on the outer side of the lower end cover 9, and then the cooling water enters the three-stage heat collector 14, the four-stage heat collector 15, the end cover cooler 12, the two-stage heat collector 11 and the one-stage heat collector 10 in sequence to exchange heat with reaction products.

(6) In the normal operation process of the system, if any one of the temperature measuring points TIC201, TIC202, TIC203, TIC204, TIC205, TIC206 and TIC207 is monitored to exceed 320 ℃, the operation frequency of the first low-pressure desalted water pump 21 is gradually increased by 5% until the monitored temperature point is restored to be within a normal range; if any temperature monitoring point still has over temperature when the first low-pressure desalted water pump 21 runs at full load, the second low-pressure desalted water pump 22 is started, the fourth switching valve V4 is opened, the two pumps run in parallel and simultaneously, and the running frequency of the second low-pressure desalted water pump 22 is increased gradually by 5% until any temperature monitoring point returns to normal.

(7) After the cooling water and the reaction product are subjected to gradual heat exchange, saturated steam with the pressure of 0.8MPa and the temperature of 170 ℃ is generated and enters a gas-liquid separator 24 from an outlet of a first-stage heat collector 10 to be subjected to steam-water separation. And a third pressure regulating valve V7 is arranged on an outlet pipeline of the steam at the top of the gas-liquid separator 24, the third pressure regulating valve V7 is interlocked with a pressure measuring point PIC101 on the gas-liquid separator 24, and after the steam flows out from the outlet of the gas-liquid separator 24, the pressure of the flowing steam is controlled by regulating the opening degree of the third pressure regulating valve V7, so that the steam finally passing through the third pressure regulating valve V7 is always saturated steam of 0.8MPa and flows into the steam collecting device 34 for next utilization.

(8) When the desalted water in the gas-liquid separator 24 reaches the high liquid level set by the liquid level monitoring point LIC101, the fourth regulating valve V8 on the water outlet pipeline at the bottom of the gas-liquid separator 24 is opened gradually by 5% amplitude, and the desalted water is injected into the desalted water tank 20 until the liquid level monitoring point LIC101 reaches the normal liquid level range.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A waste heat recycling system based on a supercritical hydrothermal combustion technology is characterized by comprising a supercritical hydrothermal combustion reactor (7), wherein the supercritical hydrothermal combustion reactor (7) comprises a cylinder body, the upper part of the cylinder body is provided with an upper end cover (8), and the lower part of the cylinder body is provided with a lower end cover (9); the interior of the cylinder body is a reaction chamber, and a multi-stage heat collector and a material preheater (13) are arranged; the upper end cover (8) is provided with a reaction product outlet (N5), and the lower part of the lower end cover (9) is provided with a salt discharge outlet (N6); the reaction chamber is connected with a softening water tank (1), an oxidant unit (4) and an alcohol auxiliary agent unit (5); the material preheater (13) is connected with the softening water tank (1) and the material unit (6); the outer wall surface of the lower end cover (8) is provided with a water cooling jacket (18), a desalting water tank (20) is connected to the water cooling jacket (19), the outlet of the water cooling jacket (18) is connected with the inlet of the multistage heat collector, the outlet of the multistage heat collector is connected with a saturated steam collecting unit, and the saturated steam collecting unit is connected with the desalting water tank (20).

2. The supercritical water hot combustion technology-based waste heat recovery and utilization system as claimed in claim 1, wherein the upper end cover (8) is provided with a supercritical water inlet (N1), an oxidant inlet (N2), an alcohol auxiliary agent inlet (N3) and a material inlet (N4); the outlet of the softening water tank (1) is connected with a high-pressure softening water pump (2), and the outlet of the high-pressure softening water pump (2) is respectively connected with the heating device (3) and the inlet of the material preheater (13); the oxidant unit (4) is connected with an oxidant inlet (N2); the alcohol auxiliary agent unit (5) is connected with an alcohol auxiliary agent inlet (N3); the outlet of the material preheater (13) is connected with a material inlet (N4).

3. The waste heat recovery system based on supercritical water hot combustion technology of claim 1 or 2, characterized in that the reaction product outlet (N5) is connected with a product depressurization separation module (23).

4. The waste heat recycling system based on supercritical water thermal combustion technology as claimed in claim 1, characterized in that the multi-stage heat collector comprises a first-stage heat collector (10), a second-stage heat collector (11), a third-stage heat collector (14) and a fourth-stage heat collector (15); the inlet of the third-stage heat collector (14) is connected with the outlet of the water cooling jacket (18), and the outlet is connected with the fourth-stage heat collector (15); an outlet of the four-stage heat collector (15) is connected with an end cover cooler (12), and the end cover cooler (12) is arranged in the upper end cover (8); an outlet of the end cover cooler (12) is connected with a secondary heat collector (11), an outlet of the secondary heat collector (11) is connected with a primary heat collector (10), and an outlet of the primary heat collector (10) is connected with a saturated steam collecting unit.

5. The supercritical water thermal combustion technology-based waste heat recovery and utilization system as claimed in claim 1 or 4, characterized in that the saturated steam collection unit comprises a gas-liquid separator (24), the gas outlet of the gas-liquid separator (24) is connected with a steam collection device (25), and the liquid outlet is connected with a desalted water tank (20).

6. The supercritical water thermal combustion technology-based waste heat recovery system as defined in claim 1 wherein the outlet of the desalted water tank (20) is connected to a first low-pressure desalted water pump (21) and a second low-pressure desalted water pump (22), and the outlets of the first low-pressure desalted water pump (21) and the second low-pressure desalted water pump (22) are both connected to the inlet of the water cooling jacket (18).

7. The waste heat recovery system based on supercritical water thermal combustion technology as defined in claim 2, wherein the reaction chamber is divided into five sequentially connected reaction zones, and the inside of the lower end cap (9) is an inorganic salt recovery chamber (17); the supercritical water inlet (N1), the oxidant inlet (N2), the alcohol auxiliary agent inlet (N3) and the material inlet (N4) are communicated with a first reaction area, and the first reaction area is communicated with the inorganic salt recovery chamber (17); the first-stage heat collector (10) is arranged in the first reaction zone and the second reaction zone, the second-stage heat collector (11) is arranged in the third reaction zone, the material preheater (13) is arranged in the fourth reaction zone, and the third-stage heat collector (14) and the fourth-stage heat collector (15) are arranged in the fifth reaction zone; the reaction product outlet (N5) is communicated with the fifth reaction zone, and the salt discharge outlet (N6) is communicated with the inorganic salt recovery chamber (17).

8. The supercritical water thermal combustion technology-based waste heat recovery and utilization system according to claim 7 is characterized in that the cold fluid flow direction in the first-stage heat remover (10), the second-stage heat remover (11), the material preheater (13), the third-stage heat remover (14) and the fourth-stage heat remover (15) is in a countercurrent arrangement with the hot fluid flow direction of the reaction product inside the supercritical water thermal combustion reactor (7); the first-stage heat collector (10), the second-stage heat collector (11), the material preheater (13), the end cover cooler (12), the third-stage heat collector (14) and the fourth-stage heat collector (15) adopt a membrane wall heat exchanger, a coil heat exchanger, a serpentine heat exchanger or a spiral heat exchanger.

9. The waste heat recovery system based on supercritical water thermal combustion technology as claimed in claim 7, characterized in that the first reaction zone is communicated with the second reactor through an inorganic salt filtering device (16); the salt discharge outlet (N6) is connected with an inorganic salt recycling module (19).

10. A waste heat recovery method based on supercritical water thermal combustion technology by using the system of any one of claims 1-9, which is characterized by comprising the following steps:

step 1, introducing cold materials into a material preheater (13) from a material unit (6), and interlocking a material preheating outlet temperature measuring point (TIC101) with a heating device (3), a first regulating valve (V5), a second regulating valve (V6) and a high-pressure softening water pump (2);

when the temperature of a material preheating outlet temperature measuring point (TIC101) is monitored to be lower than a low-temperature threshold value, a high-pressure softening water pump (2), a first switch valve (V1), a second switch valve (V2) and a heating device (3) are started, supercritical water is injected into a supercritical water thermal combustion reactor (7), and the frequency of the heating device (3) is increased; after the temperature of the supercritical water is increased to a preset temperature, increasing the opening degree of a second regulating valve (V6) until the supercritical hydrothermal combustion reaction is normally carried out;

when the temperature of a material preheating outlet temperature measuring point (TIC101) is monitored to exceed a high-temperature threshold, if supercritical water is injected into the supercritical water hot combustion reactor (7), the opening degree of a second regulating valve (V6) is reduced until the flow of the supercritical water is reduced to zero; if the temperature of the material preheating outlet temperature measuring point (TIC101) still exceeds the high-temperature threshold value, increasing the opening degree of a first adjusting valve (V5), and injecting cooling water into the material preheater (13) until the temperature of the material preheating outlet temperature measuring point (TIC101) returns to the normal temperature; meanwhile, if salt crystallization occurs in the material preheater (13), the opening degree of a first regulating valve (V5) and the frequency of the high-pressure softening water pump (2) are increased, and the material preheater (13) is flushed until the supercritical hydrothermal combustion reaction is normally carried out;

step 2, introducing the preheated material, oxidant and alcohol auxiliary agent into a supercritical hydrothermal combustion reactor (7) through a material inlet (N4), an oxidant inlet (N2) and an alcohol auxiliary agent inlet (N3) respectively to perform supercritical hydrothermal combustion reaction, filtering high-temperature and high-pressure reaction products generated by the reaction by an inorganic salt filtering device (16) to obtain inorganic salt and liquid-phase products, allowing the inorganic salt to enter an inorganic salt recovery chamber (17), allowing the liquid-phase products to exchange heat with a primary heat collector (10), a secondary heat collector (11), a material preheater (13), a tertiary heat collector (14) and a quaternary heat collector (15) in sequence, and allowing the liquid-phase products to enter a product pressure reduction separation module (23) through a reaction product outlet (N5);

step 3, when the step 2 is carried out, a first low-pressure desalting water pump (21) and a third on-off valve (V3) are started, cooling water is injected into a water cooling jacket (18) on the outer side of a lower end cover (9), and then the cooling water enters a three-stage heat collector (14), a four-stage heat collector (15), an end cover cooler (12), a two-stage heat collector (11) and a one-stage heat collector (10) in sequence to exchange heat with reaction products;

in the process of the step 2 and the step 3, if the temperature of any one of the first temperature measuring point (TIC201), the second temperature measuring point (TIC202), the third temperature measuring point (TIC203), the fourth temperature measuring point (TIC204), the fifth temperature measuring point (TIC205), the sixth temperature measuring point (TIC206) or the seventh temperature measuring point (TIC207) is monitored to exceed the high-temperature threshold value, the operating frequency of the first low-pressure desalted water pump (21) is increased until the monitored temperature point is recovered to be within the normal range; if the temperature of any temperature measuring point exceeds a high-temperature threshold value when the first low-pressure desalted water pump (21) runs at full load, the second low-pressure desalted water pump (22) is started, a fourth switching valve (V4) is opened, so that the two pumps run in parallel and simultaneously, the running frequency of the second low-pressure desalted water pump (22) is increased until any temperature measuring point returns to normal;

step 4, steam generated after the low-pressure cooling water and the high-temperature high-pressure reaction product are subjected to gradual heat exchange enters a gas-liquid separator (24); a third pressure regulating valve (V7) is arranged on an outlet pipeline of the steam at the top of the gas-liquid separator (24), the pressure of the steam flowing out is controlled by regulating the opening degree of the third pressure regulating valve (V7), so that the steam finally passing through the third pressure regulating valve (V7) is saturated steam, and the saturated steam finally flows out and enters a steam collecting device (25) for next utilization;

when the desalted water in the gas-liquid separator (24) reaches a high liquid level set by a liquid level monitoring point (LIC101), a fourth regulating valve (V8) on a water outlet pipeline at the bottom of the gas-liquid separator (24) is opened, and the desalted water is injected into the desalted water tank (20) until the liquid level monitoring point (LIC101) reaches a normal liquid level range.

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