WO2020037905A1

WO2020037905A1 - Gasification system and process for efficient heat energy recovery

Info

Publication number: WO2020037905A1
Application number: PCT/CN2018/122283
Authority: WO
Inventors: 赵静一; 黄萍; 毛炜; 张燕
Original assignee: 北京航天迈未科技有限公司
Priority date: 2018-08-21
Filing date: 2018-12-20
Publication date: 2020-02-27
Also published as: CN108795500A

Abstract

A gasification system for efficient heat energy recovery, comprising a gasification furnace (1), a spray apparatus being disposed on a heat exchange surface within a radiation heat exchange chamber (12) of the gasification furnace (1) so as to form a low temperature area close to the heat exchange surface and a core high temperature area located on a side of the low temperature area that is far from the heat exchange surface; a gas-solid separation and ash cooling device (2) that is provided in communication with a syngas outlet of the gasification furnace (1); a convection heat exchange device (3) that is used for recovering sensible heat from a syngas and generating power steam; a gas washing device that comprises a venturi scrubber (41) and a washing tower (42) which are arranged in series; a black water treatment system that comprises a first-stage flash evaporation apparatus (51) and a second-stage flash evaporation apparatus (52) which are arranged in series. Further provided is a gasification process for efficient heat energy recovery, wherein the radiation heat exchange chamber (12) employing side zone temperature-control technology may ensure the safety of heat exchange tubes, and may also ensure that heat energy recovery efficiency is high under high radiation intensity; the present invention has high saturated steam yield and smaller equipment volume.

Description

Gasification system and process for efficient thermal energy recovery

Technical field

The invention belongs to the technical field of synthesis gas, and particularly relates to a gasification system and a process that can efficiently recover heat energy with chemical products, fuel gas and IGCC as targets.

Background technique

Gasification technology that uses coal, petroleum, coal coke and other carbonaceous materials as raw materials to produce syngas (mainly composed of CO and H ₂ ), as an important means for the clean utilization of fossil raw materials, has been widely used in gas, syngas, IGCC, etc. field. During the gasification reaction, most of the chemical energy of the carbon-containing raw material is converted into the chemical energy of the synthesis gas, but about 20% of the chemical energy is still converted into the sensible heat of the synthesis gas and ash, resulting in heat loss. How to improve the recovery and utilization efficiency of this part of the sensible heat is of great significance to the production of chemical equipment and energy saving.

At present, there are mainly two heat recovery processes for the high-temperature synthesis gas produced by the gasification furnace. One is to transfer the sensible heat in the high-temperature synthesis gas to black water through a rapid cooling method, and then heat the lower temperature black water. Recovery and comprehensive utilization, one is to use waste heat boiler to recover high-temperature heat energy in syngas.

The first process is represented by GE's coal water slurry water gasification-water quenching process. In this process, the high-temperature synthesis gas (less than 1400 ° C) produced by the gasifier is cooled by a large amount of water and quickly cooled to 230 ~ 250 ℃. The cooled syngas is sent out after washing and dust removal (the temperature is further reduced to 210 ~ 240 ℃). Cooling water and washing dust removal water have a higher solid content and are called black water. Most of the sensible heat of the synthesis gas enters the black water. The black water enters the flash device for multi-stage flash evaporation. Part of the flash steam is used to directly or indirectly heat the black water, and the remaining steam is recovered after cooling by cooling water. This water-chilling process has the advantage of simple operation, but most of the high-temperature heat energy in the process is converted to low-temperature heat energy, the energy utilization efficiency is low, the cooling water consumption is large, and because all ash and slag enter the water, the water system circulation amount Large, high power consumption.

The second process is mainly as follows: First, it is represented by Shell gasification technology, which mixes synthesis gas with low-temperature circulating gas on the top of the gasification furnace, and enters the waste pot for heat exchange after the temperature drops below 900 ° C. The heat exchange is mainly convective heat exchange, but due to the high content of particles entrained in the gas, the waste pot is prone to blockage and abrasion. After the syngas exits the waste pot, a fly ash filter is used to perform gas-solid separation, and the separated dry ash is separated. High-pressure nitrogen is used for stripping and cooling. This gasification technology has the advantages of simple high-pressure black water treatment and small circulation due to the dry ash removal. However, the fly ash removal system used for dry ash removal is more complicated and difficult to operate. High, high-pressure nitrogen consumption, and low water-to-gas ratio of synthesis gas, it is difficult to meet the production requirements of chemical products. In addition to Shell gasification technology, the existing technology also has the technology represented by the GE waste pot process, which recovers the heat in the synthesis gas by setting up a waste waste pot section and a convection waste pot section, but the convection waste pot is prone to ash accumulation. It is difficult to guarantee long-term stable operation requirements.

Chinese patent document CN104017606B proposes a coal water slurry gasification process system based on the idea of cyclic gas quenching, which aims to solve the problem that a large amount of syngas in the coal water slurry gasification process system cannot be recovered. The gasification furnace has an ascending structure. After the high temperature gas at the outlet of the combustion chamber is mixed with the low temperature circulating gas to cool down, it enters a heat exchanger (superheater) to superheat the saturated steam from the steam drum. Syngas then enters the second cyclone dust collector for the first gas-solid separation. Then, the synthesis gas enters the cooling device (including the superheater and two saturated steam generators), and continues to recover the heat in the synthesis gas. The cooled low-temperature synthesis gas enters the first cyclone dust collector, performs secondary gas-solid separation, and then removes most of the solid particles in the synthesis gas through a ceramic filter. Part of the low-temperature synthesis gas coming out of the ceramic filter is returned to the gasifier as a chilled gas through the compressor, and part is sent out after being washed with water. The dry ash collected by the two-stage cyclone is sent to the ash tank, which is cooled by the ash water and reduced in pressure, and then discharged into the slag-removing machine. A plurality of slag cooling components are arranged inside the aforementioned heat exchanger and cooling device, which can scrape off the ash and slag on the inner surface of the heat exchange cavity to avoid the slag accumulation causing blockage of the heat exchanger. However, in this process, after the secondary cyclone is set in the heat exchanger (superheater), the concentration of particles in the syngas entering the heat exchanger is very high, and there is still the possibility of abrasion and blockage of the heat exchanger. The slag scraping cooling unit is a moving part, the working environment is harsh, and the failure rate is high. In addition, the cooling synthesis gas pressurized circulation chilling method is used, because the coal-water slurry gasifies the synthesis gas in a large amount of CO ₂ and water vapor, the combustion chamber outlet gas volume is about 1.2 times that of the Shell gasification chamber outlet gas volume. The temperature of the chilled cycle synthesis gas is higher than that of Shell process, which results in the compression of the cycle gas compressor is much larger than that of Shell process, the compressor operating temperature is higher, and the energy consumption is higher.

Texaco Development's patent CN1037503C discloses a method for preparing cooling and cleaning synthesis gas to remove entrained particulate matter, which method includes flash evaporation, degassing, gas cooling and energy-saving filtration of wash water. For the cooling of high-temperature gas synthesis gas, a) water-cooled direct contact cooling and b) indirect heat transfer (radiation and / or convection cooling) are mentioned. Among them, a) method is used to cool high-temperature synthesis gas and high-temperature synthesis. Most of the sensible heat of gas enters low-temperature water, and energy waste is serious. The b) method is used to cool the high-temperature synthesis gas. Due to the high content of particles in the synthesis gas, the problems of abrasion and ash accumulation in the convection waste pot will cause serious long-term stable operation of the device. The black water produced by the high-temperature synthesis gas can be degassed by three-stage flash steam. Specifically, the first-stage flash steam heats the grey water indirectly through the grey water heater, and the second-stage flash steam is mixed with the grey water in the deaerator. Direct contact removes dissolved oxygen in grey water, and all three-stage flash steam is cooled with cooling water. In industrial applications, due to the large amount of high temperature sensible heat of the synthesis gas entering the black water and the large amount of black water discharge, the system often uses a 3-4 level flash evaporation system to recover the low temperature heat in the black water, and the system configuration is complicated. At the same time, because the first-level flash steam contains a large amount of acidic gas (H ₂ S, CO ₂ etc.) and the suspended solids concentration, alkalinity and hardness in the gray water are very high, the problem of corrosion and scaling of the gray water heater is prominent, and the cost of equipment and materials It is expensive and difficult to guarantee long-term stable operation, and the running cost is high. The final stage flash steam has a large amount, and all are cooled by cooling water, which consumes a large amount of cooling water.

In addition to the above cooling method, US Patent No. 4,589,213 also discloses a system for preparing and purifying synthesis gas. The high-temperature synthesis gas in the system is first mixed with the low-temperature synthesis gas from the cycle gas compressor. The temperature after mixing should be as low as possible. The molten fly ash particles are solidified. The mixed gas entrained fly ash particles first enter the waste pot for heat recovery, and then enter the dry ash separation equipment (such as a cyclone separator) to separate most of the fine ash particles. Finally, the gas enters the wet washing system to further After washing and cooling, after cooling and heat exchange and acid gas removal, the product gas required by downstream users is obtained. The black water obtained by cooling the slag and wet washing can be recycled after removing the acid gas dissolved therein by a stripping method. This system adopts the method of circulating gas quenching and waste heat recovery, which can convert the high-temperature thermal energy in the synthesis gas into power steam, which has high useful work efficiency, but has the following problems in industrial applications: 1) In order to make high-temperature synthesis gas When the temperature drops to a suitable temperature, a large amount of circulating gas needs to be replenished. The circulating gas compressor has a high failure rate and high power consumption. 2) Syngas needs to be chilled to below 900 ° C and then enters the waste pot. It is mainly convective heat exchange. Due to the high content of particles in the gas, it is easy to cause waste pot clogging and abrasion; 3) Ceramic filters are usually used in solid separation in industrial applications, which are easy to damage and costly. The separated fly ash needs a large amount of high-pressure nitrogen for stripping and cooling. The entire fly ash removal system is complicated, the operation is difficult, and the high-pressure nitrogen consumption is large.

Summary of the Invention

The invention solves the technical problems of low sensible heat recovery and utilization efficiency of the syngas gasification process and system in the prior art, severe waste pot abrasion, leading to short service life, and complex fly ash removal system. This is a synthesis gasification system and process that can significantly reduce the sensible heat entering the black water, improve the use efficiency of the waste pot, and simplify the fly ash removal system.

The technical solutions adopted by the present invention to solve the above technical problems are:

A gasification system for efficient thermal energy recovery, comprising: a gasification furnace for preparing syngas and performing radiation heat exchange, the gasification furnace comprising a gasification chamber and a radiation heat exchange chamber located downstream of the gasification chamber, A spraying device is provided on the heat exchange surface of the radiation heat exchange chamber to form a low temperature region close to the heat exchange surface and a core high temperature region located on the side of the low temperature region away from the heat exchange surface. A chilled slag collecting device is provided downstream of the core high-temperature region, and the chilled slag collecting device contains a chilled liquid, and the chilled slag collecting device is provided with a black water discharge port; a gas-solid separation and cold ash device is connected with all The syngas outlet of the gasification furnace is provided in communication; a convective heat exchange device is in communication with the gas outlet of the gas-solid separation and cooling equipment for recovering the sensible heat of the synthesis gas and generating steam; a gas washing device is connected with the convection The gas outlet of the heat exchange device is connected and includes a Venturi scrubber and a washing tower arranged in series, and the washing tower is provided with a black water discharge port; the black water treatment system includes a first-stage flash evaporation device and a second-stage flash device arranged in series. Steaming device, Said slag quench means and said discharge port black water wash column with a flash device is connected to the set.

The gas-solid separation and cooling equipment includes a cyclone separator.

The convection heat exchange device includes a superheater, and a water-cooled heat exchange device is provided on the heat exchange surfaces of the gasification chamber and the radiation heat exchange chamber. A steam outlet of the water-cooled heat exchange device is provided in communication with the superheater. The syngas enters the superheater to exchange heat with the steam, and heats the steam from the water-cooled heat exchange device to superheated steam.

The convective heat exchange device includes a superheater, a multi-stage saturated steam generator, and a boiler water preheater arranged in series, and the synthesis gas from the superheater enters the multistage saturated steam generator and the boiler water preheating in order. Device.

A condensing and separating device is provided in communication with the gas outlets of the first-level flashing device and the second-level flashing device, and the acid gas outlet of the condensing and separating device is connected to the acid gas processing device; it is in communication with the first-level flashing device The liquid outlet of the condensing and separating device provided is in communication with the deaerator; the liquid exit of the secondary flashing device and the liquid and condensing device provided in communication with the secondary flashing device are in communication with the sedimentation tank. A liquid outlet is in communication with the deaerator, and a filtering device is provided in connection with the solid discharge outlet of the sedimentation tank.

A gasification process for efficient thermal energy recovery includes: (1) gasification to prepare synthesis gas, and sending the synthesis gas to a radiation heat exchange chamber for heat exchange, and a spray is arranged on a heat exchange surface of the radiation heat exchange chamber; The spraying device sprays fluid to form a low-temperature region close to the heat exchange surface and a core high-temperature region located on the side away from the heat exchange surface of the low-temperature region, and the syngas is heat-exchanged by the radiation heat exchange chamber The temperature is lowered to above 700 ° C and discharged, and the high-temperature ash and slag in the synthesis gas are chilled with a chilled liquid to form black water discharge; (2) gas-solid separation is performed on the synthesis gas after heat exchange by the radiation heat exchange chamber , Cooling the separated fine ash; (3) performing convective heat exchange treatment on the synthesis gas separated in step (2) to recover the sensible heat of the synthesis gas and generating steam; (4) in step (3) The syngas after the convective heat exchange treatment is washed, and the washing liquid is discharged as black water; (5) The black water discharged in step (1) and step (4) is subjected to two-stage flash evaporation treatment.

In step (4), the synthesis gas is washed until the particle content is less than or equal to 1 mg / Nm ³ .

In step (1), the temperature in the low temperature region is less than 900 ° C, and the temperature in the core high temperature region is above 900 ° C.

In step (2), the synthesis gas is subjected to gas-solid separation, and the particle size of the particles in the synthesis gas is controlled within a range of less than or equal to 5 μm.

In step (2), the dry ash is cooled by a dry method.

The heat generated in the synthesis gas produced in step (1) and the heat generated in the radiant heat exchange chamber is heated by the heat exchange to face the water cooling medium to generate steam; in step (3), the synthesis gas and the steam are convected. Heat, the steam is heated into superheated steam with a pressure of 4.0-12 MPa and a temperature of 320-540 ° C.

The gas generated during the two-stage flash evaporation process in step (5) is condensed and separated, and the separated acid gas is sent to the downstream acid gas processing device, and the liquid separated and condensed after the first-stage flash evaporation is deoxidized; The liquid separated by condensation after the first-stage flash evaporation and the remaining liquid after the second-stage flash evaporation are subjected to sedimentation treatment, and then subjected to oxygen removal treatment, and the solid produced by the sedimentation treatment is filtered.

The gasification system and technology for high-efficiency heat recovery in the present application have the following advantages:

(1) The gasification furnace in the method of the present application adopts a radiant heat exchange chamber with a side zone temperature control technology, which can ensure the safety of heat exchange tubes, and also ensure higher heat recovery efficiency and high saturated steam output under high radiation intensity. The equipment volume is smaller; compared with the heat recovery device adopting the overall water spray cooling method, the heat recovery rate of the radiant heat exchange chamber using the edge zone temperature control technology in this application can be increased by 10-50%.

This application uses a radiation + convection heat exchange device to recover the high-temperature waste heat in the synthesis gas, which further reduces the sensible heat entering the black water system. Compared with the water quenching process, the sensible heat transferred to the black water is reduced by about 49%. The load of the black water flash system is significantly reduced, and only a two-stage flash system needs to be configured. The first stage flash evaporation removes the dissolved acid gas in the black water, and the second stage flash evaporation reduces the temperature of the black water. This application adopts a dry cold ash process. Because 90% of the fine ash is recovered in the form of dry ash, the total amount of ash entering the black water is only 45% of the water quench process, and the black water circulation is only the water quench process. 50%, the sensible heat taken away by black water is about 51% of the water chilling process, and the amount of circulating cooling water is reduced by about 50%.

(2) The cyclone separation cooling device can be used to achieve the purpose of controlling the particle size of the fly ash in the synthesis gas and reducing the particle concentration. The whirlwind can be first or second level. If a first-level cyclone configuration is adopted, the particle size of fly ash in the syngas can be controlled ≤5μm, which can effectively solve the problems of abrasion and blockage of the convection waste pot in the traditional process, and ensure long-term stable operation of the device. If a second-level cyclone configuration is used, It can control the particle size of fly ash in the synthesis gas ≤1μm, further reduce the particle concentration in the synthesis gas, reduce the ash removal load of the washing tower and the concentration of black water, improve water quality, and reduce waste water discharge. As an alternative embodiment, the gas-solid separation device may be other separation methods such as a ceramic filter, a sintered metal filter, and an electrostatic precipitator.

This application further restricts the use of a dry method for gas-solid separation and cooling, simple system configuration and operation, small equipment investment, and low shared engineering consumption. The inner wall of the cyclone separator is provided with a water cooling coil, which can protect the outer wall of the cyclone from over-temperature, and can also produce saturated steam to recover part of the residual heat in the synthesis gas.

(3) When the convection heat exchange device in this application is only equipped with a superheater, the synthesis gas can have a certain water-to-gas ratio, which can meet the downstream requirements for chemical products; the convection heat exchange device is configured to be superheated. When the generator + multi-stage saturated steam generator + boiler water heater, the waste heat in the high-temperature synthesis gas can be recovered to the maximum, and the produced synthesis gas can meet the downstream requirements for fuel gas or IGCC.

(4) The systems and processes described in this application have high power steam output. When the convection heat exchange device is only equipped with a superheater, 0.5-0.65 tons of superheated steam can be delivered per 1000Nm ³ (CO + H ₂ ); when the convection heat exchange device is configured as a superheater + a multi-stage saturated steam generator + Boiler water heater can deliver 0.7-0.8 tons of superheated steam per 1000Nm ³ (CO + H ₂ ).

In order to make the technical scheme of the highly efficient thermal energy recovery gasification system and process described in the present invention clearer, the present invention will be further described in detail below with reference to specific drawings and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flowchart of a gasification system for preparing downstream chemical products according to the present invention;

FIG. 2 is a schematic structural diagram of a gasification furnace in a gasification system according to the present invention;

FIG. 3 is a schematic structural diagram of a cross section at an inner cylinder of a radiation heat exchange chamber according to the present invention;

FIG. 4 is a schematic structural view of a cross section at a throat passage of the heat exchange device according to the present invention;

FIG. 5 is a schematic flowchart of a gasification system for preparing a downstream fuel gas or an IGCC product according to the present invention.

Among them, the reference numerals are:

1- gasification furnace; 11- gasification chamber; 111- raw material inlet; 112- throat passage; 113- second injection device;

12- Radiation heat exchange chamber;

121-first injection device; 122-third injection device; 124-outer tube; 125-radiation heat exchange chamber outlet; 126-inner tube;

13-slag tank; 14-slag breaker; 15-slag lock bucket;

2-Gas-solid separation and cold ash equipment; 21-Cyclone separator; 3-Convection heat exchange device; 31-Superheater; 32-Multi-stage saturated steam generator; 33-Boiler water preheater; 41- Venturi washing 42-washing tower; 51-first stage flash device; 52-second stage flash device; 61- condensation separation device connected to the first stage flash device; 62- deaerator; 63- connected to the second stage Condensation separation device after flash device; 64-settling tank; 65-ash water tank; 66-filtration device.

detailed description

Example 1

This embodiment provides a gasification system for efficient thermal energy recovery, which can be used to prepare downstream chemical products. As shown in FIG. 1, the gasification system includes a gasification furnace for preparing synthesis gas and performing radiation heat exchange. 1. The gasification furnace 1 includes a gasification chamber 11 and a radiation heat exchange chamber 12. The gasification furnace 1 in this embodiment adopts a structure in which the gasification chamber 11 and the radiation heat exchange chamber 12 are integrated, as shown in FIG. 2 Show.

The radiation heat exchange chamber 12 described in this embodiment is disposed below the gasification chamber 11, and a raw material inlet 111 is provided on the top of the gasification chamber 11. The radiation heat exchange chamber 12 includes an inner portion disposed in a casing. The inner and outer side walls of the inner cylinder 126 and the inner side surface of the outer cylinder 124 are heat exchange surfaces. The heat exchange surfaces of the gasification chamber 11 and the radiation heat exchange chamber 12 are provided. A water-cooled heat exchange device. The water-cooled heat exchange device described in this embodiment is a water-cooled pipe. The heat in the gasification chamber 11 and the radiant heat exchange chamber 12 is exchanged with the water cooling medium in the water-cooled pipe through a heat exchange surface. The water cooling medium in the water cooling pipe is evaporated to form steam, and the water cooling medium is boiler water.

In this embodiment, the inner cylinder 126 and the outer cylinder 124 are both cylindrical cylinders. As an optional implementation manner, the inner cylinder 126 and the outer cylinder 124 may also be provided as cylinders having a square cross-section or other arbitrary shapes. body. An inlet of a radiation heat exchange chamber is provided at the top of the inner tube 126, and the inlet of the radiation heat exchange chamber is in communication with the outlet of the gasification chamber 11; a heat exchange surface upstream of the inner tube 126 is provided with a first An injection device 121 forms a low-temperature area close to the heat exchange surface and a core high-temperature area located on a side of the low-temperature area away from the heat exchange surface, that is, inside. Since the heat exchange surface of the inner cylinder 126 in this embodiment is a cylinder Body, so the core high temperature zone formed is located in the middle of the barrel. The first spraying device 121 is preferably a first nozzle group, and the first nozzle group is arranged around a circle of the heat exchange surface upstream of the inner cylinder 126, and multiple layers or single layers can be provided along the fluid flow direction. The direction of fluid flow in the embodiment is from top to bottom. In this embodiment, the first nozzle group is provided with three layers, and the adjacent two layers of nozzles are arranged in a staggered manner. As shown in FIG. 3, multiple nozzles in each layer of nozzles are evenly arranged, and each nozzle in each layer of sprays sprays. The radius d _{1 is} greater than 0 and smaller than the equivalent radius of the inner cylinder where the nozzle is located. As a preferred embodiment, the spray radius d _{1 of} each nozzle is greater than 0 and less than 60% of the equivalent radius of the inner cylinder 126 where the nozzle is located. Preferably, the spray radius d _{1 of} each nozzle is greater than 0 and less than 30% of the equivalent radius of the inner cylinder 126 where the nozzle is located, thereby helping to increase the volume of the core high-temperature region; each nozzle in each layer of the nozzle ejects The fluid flow converges with the fluid flow ejected from an adjacent nozzle located on the same layer at a first vertical distance d ₁ from the position of the heat transfer surface, and the first vertical distance d _{1 is} greater than 0 and smaller than the spraying radius rs of the nozzle. ₁ . As an alternative embodiment, the nozzles between layers can also be arranged in a non-staggered manner; multiple nozzles in each layer of nozzles can also be arranged non-uniformly, and the nozzles between layers can spray out The fluid streams may or may not converge with each other. In this embodiment, the fluid sprayed by the dispersed nozzle forms an effective isolation, thereby forming a low temperature region near the heat exchange surface. The ash and slag particles entering the low temperature area lose their viscosity after cooling, and hard slag that is difficult to be removed will not be formed on the wall surface. At the same time, the core high temperature area still maintains a high temperature above 900 ° C, thereby maintaining a high radiation heat transfer capacity. Because the radiant heat exchange amount in the core high-temperature region accounts for most of the total heat exchange amount in the radiant heat exchange chamber 12, compared with the overall temperature reduction method of the synthesis gas, the method of cooling the edge region and the core high temperature in the present invention can effectively increase the radiant heat exchange amount. .

As a preferred embodiment, a second injection device 113 is provided at the inlet of the radiation heat exchange chamber 12 or upstream of the inlet, and the second injection device 113 is preferably a second nozzle group. The second nozzle group may be disposed at the entrance of the radiation heat exchange chamber 12 or may be disposed upstream of the entrance, that is, a throat between the gasification chamber 11 and the entrance of the radiation heat exchange chamber 12 Ministry channel 112. The second spraying device 113 is preferably a second nozzle group. As shown in FIG. 4, the spraying radius rs ₂ of the nozzles in the second nozzle group is greater than 50% (ie, 50%) of the radius at the throat passage 112. R ₂ ) is smaller than the radius R ₂ at the throat passage 112, the second nozzle group may be provided with a single layer or multiple layers, and the fluid flow ejected from each nozzle of each layer of nozzles is away from the heat exchange surface where it is located The second vertical distance d ₂ converges with the fluid flow ejected from an adjacent nozzle located on the same layer, and the distance d _{2 is} smaller than the spray radius of the nozzle. Thereby, the overall cross-section is cooled, and the second nozzle group is uniformly disposed along the circumferential direction of the throat passage 112.

In this embodiment, a fluid passage is formed between the inner cylinder 126 and the outer cylinder 124, and the fluid enters the fluid passage downstream from the inner cylinder 126, that is, the bottom of the inner cylinder 126. A third spraying device 122 is further provided on an inner wall surface of the inner cylinder 126 downstream of the first spraying device 121. The third spraying device 122 is a third nozzle group. The spray radius of each nozzle is 50% R to 90% R, where R is the equivalent radius of the inner cylinder 126 at the position where the nozzle is located.

A fourth spraying device is also provided on the fluid passage. The fourth spraying device is preferably a fourth nozzle group, and the fourth nozzle group is distributed on the outer wall surface of the inner cylinder 126 or the corresponding outer cylinder. On the inner wall surface of 124, the fourth nozzle group is disposed near the bottom ends of the inner tube 126 and the outer tube 124; and the outer tube 124 located downstream of the fourth nozzle group is provided with a radiation heat exchange chamber outlet 125.

In this embodiment, the fluid sprayed by the first nozzle group, the second nozzle group, the third nozzle group, and the fourth nozzle group is a cooling liquid, specifically, boiler water. As an alternative embodiment, the fluid is also It can be any one or more of nitrogen, carbon dioxide, cooled syngas, water vapor, and water.

In the gasification furnace 1 in this embodiment, a chilled slag collecting device is provided on the synthesis gas flow path of the radiation heat exchange chamber 12, and the role of the chilled slag collecting device is to water the high temperature ash and slag in the synthesis gas. It is chilled to remove it from the syngas. The chilled slag collecting device is disposed downstream of a low-temperature region and a core high-temperature region formed by the first spraying device 121. In the present embodiment, the chilled slag collection device uses a slag pool 13, which is disposed at the bottom of the radiation heat exchange chamber 12, and the slag pool 13 contains a chilled liquid. The synthesis gas turns from the inner cylinder 126 to the outer cylinder 124. The high-temperature slag enters the slag pool 13 under the action of gravity and is quickly cooled by the chilled liquid. The slag pool 13 is provided with a black water discharge port.

The gasification system described in this embodiment is further provided with:

The gas-solid separation and cold ash equipment 2 is provided in communication with the synthesis gas outlet of the gasification furnace 1. The gas-solid separation and cooling equipment in this embodiment includes a cyclone separator 21 as an alternative embodiment, except for a cyclone The separator 21 and the gas-solid separation device may be other separation devices such as a ceramic filter, a sintered metal filter, and an electrostatic precipitator.

The convective heat exchange device 3 is in communication with the gas outlet of the cyclone separator 21, and is used to recover the sensible heat of the syngas and generate power steam; the convective heat exchange device 3 in this embodiment is a superheater 31, and the gas The steam outlet of the water-cooled heat exchange device of the chemical furnace 1 is arranged in communication with the superheater 31, and the synthesis gas enters the superheater 31 to exchange heat with the steam, and heats the steam from the water-cooled heat exchange device. For superheated steam.

A gas washing device, which is arranged in communication with the gas outlet of the convection heat exchange device 3 and includes a Venturi scrubber 41 and a washing tower 42 arranged in series;

The black water treatment system includes a first-stage flash steaming device 51 and a second-stage flash steaming device 52 arranged in series. The black water discharge ports of the gasification furnace 1 and the washing tower 42 are connected to the first-stage flash steaming device 51. Settings. Condensation and

separation devices

61 and 63 are respectively provided in communication with the gas outlets of the first-stage flash evaporation device 51 and the second-stage flash evaporation device 52. The acid gas outlet of the condensation separation device is connected to the acid gas processing device, and the acid gas The processing device processes the acid gas discharged from the acid gas outlet. As an alternative embodiment, a combustion treatment may be adopted; the liquid outlet and the deaerator 62 of the condensation separation device provided in communication with the first-stage flash evaporation device 51 Communication; the liquid outlet of the secondary flash device 52 and the condensation separation device provided in communication with the secondary flash device 52 are in communication with the sedimentation tank 64, and the liquid outlet of the sedimentation tank 64 and the deaerator 62 is provided in communication. As a preferred embodiment, a gray water tank 65 for buffering is provided between the sedimentation tank 64 and the deaerator 62, and a filter is connected to the solid discharge port of the sedimentation tank 64. Device 66, the liquid outlet of the filtering device 66 is provided in communication with the sedimentation tank 64, and is used for the backflow of part of the liquid.

As a preferred implementation manner, the liquid outlet of the deaerator 62 in this embodiment is provided with two pipelines, one of which is in communication with the washing tower 42 for returning the liquid to the washing tower 42 as the washing liquid; the other is The slag pool 13 is communicated, and after being boosted by a pump, it is sent into the chilled slag collection device for replenishing the chilled liquid in the slag pool 13 and maintaining the chilled liquid in the slag pool 13 to a certain amount.

The gasification process based on the efficient thermal energy recovery of the gasification system described in this embodiment includes the following steps:

(1) The gasification agent and oxidant are sent to the gasification chamber 11 for gasification reaction to generate synthesis gas, wherein the gasification agent is a carbon-containing fuel, and the oxidant is an oxygen-containing gas and steam; the synthesis gas enters through the throat passage 112 The inner cylinder 126 of the radiation heat exchange chamber 12 is pre-cooled by using the second nozzle group spray fluid during the entry process, and the temperature of the fluid entering the inner cylinder 126 of the radiation heat exchange chamber 12 is controlled to be not higher than 1500 ° C. Synthetic gas enters the inner cylinder 126, and the first spraying device 121 is used to spray fluid to keep the temperature in the low-temperature region of the radiation heat exchange chamber 12 lower than 900 ° C and the temperature in the core high-temperature region above 900 ° C. Ensure efficient heat exchange efficiency. Wherein, the equivalent radius of the core high-temperature region occupies 30% to 95% of the equivalent radius of the radiation heat exchange chamber 12 at the position where it is, and more preferably 30 to 60%. The fluid that continues to descend from the low-temperature region and the core high-temperature region is cooled by the further injection of the third injection device 122, so that the overall cross-sectional temperature of the fluid is lowered, thereby reducing the viscosity, and preventing particles from turning into the outer cylinder from the inner cylinder 126. At 1200, it collided with the wall surface. After entering between the inner cylinder and the outer cylinder 124, the fourth nozzle group was further sprayed to reduce the temperature, so that the slag particles that were not sufficiently cooled were further cooled before they hit the wall surface. Reduce or prevent adhesion. In the radiation heat exchange chamber 12, as the gas temperature of the synthesis gas decreases, the liquid slag in the synthesis gas rapidly solidifies, and large ash and slag particles fall into the bottom slag pool 13, and pass through the slag breaker 14, the slag lock bucket 15 3. The slag-fishing machine discharges, and the remaining part forms black water discharge.

(2) The cyclone separator 21 is used to perform gas-solid separation on the synthesis gas that has been heat exchanged by the radiation heat exchange chamber 12, and the particle size of the synthesis gas is controlled within a range of less than or equal to 5 μm; The cooling method is to cool the high-temperature dry ash separated by the cyclone separator 21. The dry cooling refers to the convective heat exchange of high-temperature dry ash by using gas, circulating water, desalinated water, etc. as a cooling medium. The ash separated by the cyclone, which accounts for 90% of the total ash, can be recovered as dry ash. At the same time, the energy in the high-temperature dry ash can be further recovered, and the recovered energy can be further comprehensively used. For example, hot demineralized water can be used as steam Including make-up water, thermal circulating water can be used as hot water in the factory, and hot gas can be used to heat or dry the powder.

(3) The superheater 31 is used to perform convective heat exchange treatment on the synthesis gas separated in step (2). The synthesis gas is used as the heating medium in the superheater 31, and the steam generated by the gasification furnace 1 is subjected to superheat treatment. The steam is heated into high-quality superheated steam with a pressure of 4.0-12MPa and a temperature of 320-540 ° C, so as to recover the sensible heat of the synthesis gas and generate high-quality power steam. In this embodiment, a superheater 31 is provided for heat exchange treatment. The synthesis gas from 31 can be used for downstream preparation of chemical products.

(4) The venturi scrubber 41 and the washing tower 42 are used to sequentially wash the syngas after the convective heat exchange treatment in step (4), and the syngas is washed until the particle content is less than or equal to 1 mg / Nm ³ , and the washing water is formed. Black water discharge

(5) The black water generated in step (1) and step (4) is subjected to two-stage flash evaporation, and a condensation separation device is used to condense and separate the gas generated during the two-stage flash evaporation process, and the separated acid gas Combustion treatment is performed, and the liquid separated and condensed after the first stage flash evaporation is sent to the deaerator 62 for deaeration treatment; the liquid separated and condensed after the second stage flash evaporation and the remaining liquid after the second stage flashed enter the sedimentation tank first. 64. The supernatant liquid after the sedimentation treatment is sent to the deaerator 62 for deoxygenation treatment, and the sedimented solid part generated by the sedimentation treatment is sent to the filtering device 66 for filtration, and the filtrate generated by the filtration is returned to the sedimentation tank 64; In this embodiment, the liquid from the deaerator 62 is returned to the washing tower 42 and the slag tank 13 to realize water recycling; part of the liquid discharged from the sedimentation tank is sent to the deaerator and part of it is returned to the slag lock hopper for promoting Slag discharge, part of the wastewater is formed to balance the dissolved salt in the grey water system.

Example 2

This embodiment provides a high-efficiency thermal energy recovery gasification system that can be used to prepare downstream fuel gas or IGCC products. As shown in FIG. 5, the gasification system includes:

The gasification furnace 1 used for preparing syngas and performing radiative heat exchange, the gasification furnace 1 described in this embodiment is the same as the embodiment 1.

The gas-solid separation and cold ash equipment 2 is provided in communication with the synthesis gas outlet of the gasification furnace 1. The gas-solid separation and cooling equipment in this embodiment includes a cyclone separator 21. This embodiment adopts a two-stage cyclone configuration. Can control fly ash particle size ≤1μm in syngas.

The convective heat exchange device 3 is in communication with the gas outlet of the cyclone separator 21 and is used to recover the sensible heat of the synthesis gas and generate power steam. The convective heat exchange device 3 in this embodiment is a superheater 31, Multi-stage saturated steam generator 32 and boiler water preheater 33. In this embodiment, the steam outlet of the water-cooled heat exchange device of the gasification furnace 1 is provided in communication with the superheater 31, and the synthesis gas enters the superheater 31 to exchange heat with the steam to cool the water. The steam from the heat exchange device is heated to superheated steam. After the synthesis gas comes out of the superheater 31, it enters the multi-stage saturated steam generator 32 and the boiler water preheater 33 in order to generate saturated steam and the boiler water. Preheating to further recover the heat in the synthesis gas, wherein the preheated boiler water is used as the water cooling medium in the gasifier 1 and the cooling liquid sprayed from the injection device; the multi-stage saturated steam generator 32 is suitable Any of two to four-stage saturated steam generators is used.

The gas washing device is arranged in communication with the gas outlet of the convective heat exchange device 3 and includes a Venturi scrubber 41 and a washing tower 42 arranged in series to wash the syngas that has completed convective heat exchange.

The black water treatment system includes a first-stage flash steaming device 51 and a second-stage flash steaming device 52 arranged in series. The black water discharge ports of the gasification furnace 1 and the washing tower 42 are connected to the first-stage flash steaming device 51. Settings. A condensation separation device is provided in communication with the gas outlets of the first-stage flash evaporation device 51 and the second-stage flash evaporation device 52, and the acid gas outlet of the condensation separation device is connected to the acid gas processing device; The liquid outlet of the condensation separation device provided in communication with the device 51 is in communication with the deaerator 62; the liquid outlet of the secondary flash device 52 and the liquid separation in the condensation separation device provided in communication with the secondary flash device 52 are connected to the sedimentation tank 64 The liquid outlet of the sedimentation tank 64 is in communication with the deaerator 62. As a preferred embodiment, a gray water tank for buffering is provided between the sedimentation tank 64 and the deaerator 62. 65. A filtering device 66 is provided in connection with the solid discharge port of the sedimentation tank 64, and a liquid outlet of the filtering device 66 is provided in communication with the sedimentation tank 64 for returning part of the liquid.

(1) The gasification agent and oxidant are sent to the gasification chamber 11 for gasification reaction to generate synthesis gas, wherein the gasification agent is a carbon-containing fuel, and the oxidant is an oxygen-containing gas and steam; the synthesis gas enters through the throat passage 112 The inner cylinder of the radiation heat exchange chamber 12 is pre-cooled by using the second nozzle group spray fluid during the entry process, and the temperature of the fluid entering the inner cylinder of the radiation heat exchange chamber 12 is controlled to be not higher than 1500 ° C; The gas enters the inner cylinder, and the first spraying device 121 is used to spray the fluid to keep the temperature in the low temperature region of the radiation heat exchange chamber 123 lower than 900 ° C and the temperature in the core high temperature region above 900 ° C, thereby ensuring efficient Heat transfer efficiency. Wherein, the equivalent radius of the core high-temperature region occupies 30% to 95% of the equivalent radius of the radiation heat exchange chamber 12 at the position where it is, and more preferably 30 to 60%. The fluid that continues to descend from the low-temperature region and the core high-temperature region is cooled by the further spraying effect of the third spraying device 122, so that the overall cross-sectional temperature of the fluid is lowered, thereby reducing the viscosity, and preventing particles from turning from the inner cylinder into the outer cylinder 124 When it collides with the wall surface, it enters between the inner cylinder and the outer cylinder 124, and then the fourth nozzle group is further sprayed to cool down, so that the slag particles that are not sufficiently cooled are further cooled before hitting the wall surface to reduce Or prevent adhesion. In the radiation heat exchange chamber 12, as the gas temperature of the synthesis gas decreases, the liquid slag in the synthesis gas rapidly solidifies, and large ash and slag particles fall into the bottom slag pool 13, and pass through the slag breaker 14, the slag lock bucket 15 The slag-fishing machine discharges, and the remaining part forms black water.

(2) The cyclone separator 21 is used to perform gas-solid separation on the syngas that has been heat-exchanged by the radiation heat exchange chamber 12, and the particle size of the syngas is controlled to be less than or equal to 1 μm; The separated fine ash is subjected to cooling treatment in a method, and the fine ash, which accounts for 90% of the total fine ash, is recovered in the form of dry ash.

(3) Use the superheater 31 to perform convective heat exchange treatment on the synthesis gas separated in step (2), and send the synthesis gas to the superheater 31, the multi-stage saturated steam generator 32, and the boiler water preheater 33 in this order. As a heating medium in the superheater 31, the steam generator and the boiler water preheater 33, the synthesis gas is used to generate power steam and saturated steam, and further preheat the boiler water, thereby fully recovering the sensible heat of the synthesis gas. The superheater 31 in this embodiment performs a heat treatment on the steam generated by the gasification furnace 1 and the multi-stage saturated steam generator 32, and can heat the steam to a pressure of 4.0-12MPa and a temperature of 320-540 ° C. Superheated steam quality.

(4) The Venturi scrubber 41 and the washing tower 42 are used to sequentially wash the syngas after the convective heat exchange treatment in step (4), and the syngas is washed to a particle content of 1 mg / Nm ³ or less, and the washing water is formed Black water.

(5) The black water generated in steps (1) and (4) is subjected to a two-stage flash evaporation process, and a condensation separation device is used to condense and separate the gas generated during the two-stage flash evaporation process, and the separated acid gas Combustion treatment is performed, and the liquid separated and condensed after the first stage flash evaporation is sent to the deaerator 62 for deaeration treatment; the liquid separated and condensed after the second stage flash evaporation and the remaining liquid after the second stage flashed enter the sedimentation tank 64. The supernatant liquid after the sedimentation treatment is sent to the deaerator 62 for deoxygenation treatment, and the sedimented solid part generated by the sedimentation treatment is sent to the filtering device 66 for filtration, and the filtrate generated by the filtration is returned to the sedimentation tank 64; In this embodiment, the liquid from the deaerator 62 is returned to the washing tower 42 and the slag tank 13 to realize water recycling.

Experimental example

The process system in the present application can effectively recover the high-temperature heat energy in the synthesis gas, with an output of (CO + H ₂ ) of 100,000 Nm ³ / h, an average reaction temperature in the gasification chamber 11 of 1400 ° C., and an annual operating time. The output values in Example 1 and Example 2 were estimated based on 8000 hours. The results are shown in the following table:

Note: The price of 10MPag power steam is calculated at 120 yuan / ton, and the price of circulating cooling water is calculated at 0.1 yuan / ton.

It can be known from the above table that the proportion of high-temperature sensible heat converted into 10.0 MPag grade power steam in the synthesis gas can reach 50-70%. Using this process can produce 10.0MPag grade power steam 50-65 tons / h (non-chemical products scheme is 70-80 tons / h), and the annual output value is increased to 48.62-6302 million yuan (non-chemical products scheme is 67.78-7738 million yuan) At the same time, the circulating cooling water consumption is reduced by about 780 tons / h (720 tons / h for non-chemical products), and annual savings can be 620,000 yuan (580,000 yuan for fuel gas or IGCC product solutions), economic benefits and energy saving The effects are very significant.

The above-mentioned embodiments only express several implementation manners of the present invention, and their descriptions are more specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the claims.

Claims

A gasification system for efficient thermal energy recovery, which is characterized by:

A gasification furnace for preparing syngas and performing radiation heat exchange, the gasification furnace includes a gasification chamber and a radiation heat exchange chamber located downstream of the gasification chamber, and on a heat exchange surface of the radiation heat exchange chamber A spraying device is provided to form a low-temperature area close to the heat exchange surface and a core high-temperature area located on the side of the low-temperature area away from the heat exchange surface, and a chilled slag collecting device is provided downstream of the low-temperature area and the core high-temperature area. A chilled liquid is stored in the chilled slag collection device, and the chilled slag collection device is provided with a black water discharge port;

Gas-solid separation and cold ash equipment is provided in communication with the synthesis gas outlet of the gasifier;

A convection heat exchange device, which is in communication with the gas outlet of the gas-solid separation and cooling device and is used to recover the sensible heat of the synthesis gas and generate steam;

A gas washing device, which is arranged in communication with the gas outlet of the convection heat exchange device and includes a Venturi scrubber and a washing tower arranged in series, and the washing tower is provided with a black water discharge port;

The black water treatment system includes a first-stage flash evaporation device and a second-stage flash evaporation device arranged in series, and the chilled slag collection device and the black water discharge port of the washing tower are connected to the first-stage flash evaporation device.
The gasification system for efficient thermal energy recovery according to claim 1, wherein the gas-solid separation and cooling equipment comprises a cyclone separator.
The gasification system for efficient heat energy recovery according to claim 1 or 2, characterized in that the convection heat exchange device comprises a superheater, and water-cooled heat exchangers are provided on the heat exchange surfaces of the gasification chamber and the radiation heat exchange chamber. A heat device, a steam outlet of the water-cooled heat exchange device is provided in communication with the superheater, the synthesis gas enters the superheater and exchanges heat with the steam, and heats the steam from the water-cooled heat exchange device to superheat steam.
The gasification system for efficient thermal energy recovery according to claim 3, wherein the convection heat exchange device comprises a superheater, a multi-stage saturated steam generator, and a boiler water preheater arranged in series, and the superheater The resultant syngas enters the multi-stage saturated steam generator and the boiler water preheater in sequence.
The gasification system for high-efficiency thermal energy recovery according to claim 1 or 2 or 3 or 4, characterized in that a condensation separation device is provided in communication with the gas outlets of the primary flash device and the secondary flash device, The acid gas outlet of the condensation separation device is connected to the acid gas processing device; the liquid outlet of the condensation separation device provided in communication with the first-stage flash evaporation device is in communication with the deaerator; the second-stage flash evaporation device and The liquid outlets of the condensing and separating devices provided in communication with the two-stage flash evaporation device are all in communication with the sedimentation tank. The liquid outlets of the sedimentation tank are in communication with the deaerator and are connected with the solid discharge ports of the sedimentation tank. A filtering device is provided.
A gasification process for efficient thermal energy recovery, which is characterized by:

(1) Synthesis gas is prepared by gasification, and the synthesis gas is sent to a radiation heat exchange chamber for heat exchange. The heat exchange surface of the radiation heat exchange chamber is provided with an injection device, and the injection device sprays fluid to form a close exchange. The low-temperature area of the hot surface and the core high-temperature area located on the side away from the heat-exchange surface of the low-temperature area. After the heat exchange of the synthesis gas through the radiation heat exchange chamber, the temperature drops to more than 700 ° C and is discharged. Chill the high temperature ash in the synthesis gas to form black water discharge;

(2) performing gas-solid separation on the synthesis gas that has been heat exchanged by the radiation heat exchange chamber, and cooling the separated fine ash;

(3) performing convective heat exchange treatment on the synthesis gas separated in step (2), recovering the sensible heat of the synthesis gas and generating steam;

(4) washing the syngas after the convective heat exchange treatment in step (3), and the washing liquid forms black water to be discharged;

(5) The black water discharged in steps (1) and (4) is subjected to a two-stage flash treatment.
The gasification process for efficient thermal energy recovery according to claim 6, characterized in that in step (4), the synthesis gas is washed until the particle content is less than or equal to 1 mg / Nm 3 ,
The gasification process for efficient thermal energy recovery according to claim 6 or 7, characterized in that the temperature in the low temperature region in step (1) is less than 900 ° C, and the temperature in the core high temperature region is above 900 ° C.
The gasification process for efficient thermal energy recovery according to claim 8, characterized in that the synthesis gas is subjected to gas-solid separation in step (2), and the particle diameter of the synthesis gas is controlled to be less than or equal to 5 μm In the range.
The gasification process for high-efficiency thermal energy recovery according to any one of claims 6 to 9, characterized in that, in step (2), the dry ash cooling process is implemented by a dry method.
The gasification process for efficient thermal energy recovery according to any one of claims 6 to 10, characterized in that the heat generated in the preparation of the syngas in step (1) and the heat of the radiant heat exchange chamber synthesizes the water through the heat exchange surface to cool the water The medium is heated to generate steam; in step (3), the syngas and the steam are subjected to convective heat exchange, and the steam is heated to superheated steam having a pressure of 4.0-12 MPa and a temperature of 320-540 ° C.
The gasification process for high-efficiency thermal energy recovery according to any one of claims 6 to 11, characterized in that the gas generated during the two-stage flash evaporation process in step (5) is condensed and separated, and the separated acid gas is sent downstream Acid gas treatment device, which deoxidizes the liquid condensed and separated after the first stage flash evaporation; the liquid separated by the second stage flashed condensation and the remaining liquid after the second stage flash evaporation are deoxidized Treatment, filtering the solid produced by the sedimentation treatment.