Gasification furnace and steam system

Abstract

The embodiment of the invention provides a gasification furnace and a steam system, and solves the problem that in the running process of a radiation waste heat boiler, ash deposition and slag bonding can occur on a radiation screen and an outer cylinder water cooling wall, so that the heat recovery capacity is attenuated. On one hand, the gasification furnace and the steam system provided by the embodiment of the invention comprise a combustion chamber, a radiation waste boiler and a chilling chamber, the radiation waste boiler is arranged between the combustion chamber and the chilling chamber; the radiation waste heat boiler comprises an evaporation section and an overheating section; the evaporation section is arranged on one side close to the combustion chamber; and the overheating section is arranged on one side close to the chilling chamber.

Description

Technical Field

[0001] The present invention relates to the technical field of coal chemical industry, and in particular to a gasifier and a steam system. Background Art

[0002] Modern coal chemical technology is an effective way to promote the clean and efficient use of coal. According to the process flow, there are three main types of entrained-bed coal gasification: quenching process, full waste boiler process, and semi-waste boiler process. Among them, the gasification technology of the full waste boiler process and the semi-waste boiler process requires the installation of a radiation waste boiler. The main purpose of the radiation waste boiler is to recover the sensible heat of the high-temperature synthesis gas and further improve the utilization efficiency of coal, which is of great significance to promoting energy conservation and emission reduction and promoting the realization of dual carbon goals. In the gasification device of the full waste boiler and semi-waste boiler process, the radiation waste boiler can produce saturated steam or superheated steam as a by-product. During the operation of the radiation waste boiler, the radiation screen and the outer tube water-cooled wall will have the problem of ash accumulation and slagging. As the operation time of the gasifier increases, this phenomenon will become more and more serious, and the heat recovery capacity of the radiation waste boiler will also decline accordingly.

[0003] The decline of heat recovery capacity is mainly reflected in the decline of steam production and the fluctuation of steam superheat. The decline of steam production is caused by the decline of the heat-taking capacity of the outer tube water-cooled wall and the evaporation section radiation screen, and the fluctuation of steam superheat is caused by the inconsistent decay rate of the heat-taking capacity of the evaporation section and the superheat section. The decline of steam production will cause the amount of circulating boiler water entering the radiation waste boiler to decrease, making the heat transfer conditions in the outer tube water-cooled wall and the evaporation section radiation screen tube worse. If the steam superheat is too low, the saturated steam generated in the evaporation section will not be able to obtain enough heat in the superheat section to become superheated steam that meets the temperature requirements; if the superheat is too high, the heat provided by the superheat section is surplus for the saturated steam generated. If no measures are taken, the outlet steam temperature will be overheated, triggering the shutdown interlock, affecting the smooth operation of the device. Therefore, studying the control scheme of the steam superheat at the outlet of the radiation waste boiler is of great significance to the economic and stable operation of the carbon-containing gasification technology in the waste boiler process. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a gasifier and a steam system, which solves the problem that during the operation of the radiation waste boiler, dust and slagging will occur on the radiation screen and the outer tube water-cooled wall, thereby attenuating the heat recovery capacity.

[0005] In a first aspect, a gasifier and a steam system provided by an embodiment of the present invention include:

[0006] A combustion chamber, a radiation waste pot and a quenching chamber; the radiation waste pot is arranged between the combustion chamber and the quenching chamber; the radiation waste pot includes an evaporation section and a superheating section; the evaporation section is arranged on a side close to the combustion chamber; the superheating section is arranged on a side close to the quenching chamber.

[0007] In one embodiment, the radiation waste boiler includes an outer shell, a water-cooled wall and a radiation screen; the water-cooled wall and the radiation screen are arranged in the outer shell; the water-cooled wall encloses a cylindrical space, and the radiation screen is arranged in the cylindrical space.

[0008] In one embodiment, an annular space is formed between the water-cooled wall and the shell, and a protective gas flows through the annular space.

[0009] In one embodiment, the quenching chamber includes a straight downcomer and a quenching ring 14; the downcomer is arranged in the extension direction of the quenching chamber; the quenching ring 14 is arranged on one side of the downcomer close to the superheating section of the radiation waste boiler.

[0010] In one embodiment, it also includes: a steam drum 6, a first pipeline 105, a second pipeline and a third pipeline 104; the steam drum 6 is connected to the inlet header of the radiation screen of the evaporation section of the radiation waste boiler and the inlet header of the water-cooled wall through the first pipeline 105; the steam drum 6 is connected to the outlet header 7 of the radiation screen of the evaporation section of the radiation waste boiler and the outlet header of the water-cooled wall through the second pipeline; the steam drum 6 is connected to the inlet header of the superheating section of the radiation waste boiler through the third pipeline 104.

[0011] In one embodiment, the system further includes: a fourth pipeline 106 ; the fourth pipeline 106 is connected to the third pipeline 104 ; and a temperature regulating valve is disposed on the fourth pipeline 106 .

[0012] In one embodiment, it further includes: a desuperheater, which is arranged in the superheating section of the radiation waste pot.

[0013] In one embodiment, it further includes: a sewage discharge line connected to the steam drum 6.

[0014] In one embodiment, it further includes: at least one burner disposed on a side of the combustion chamber away from the radiation waste pot; the burner is a tapered channel.

[0015] In a second aspect, an embodiment of the present invention provides a steam system, comprising the gasifier described above.

[0016] A gasifier and a steam system are provided in an embodiment of the present invention. The gasifier is provided with an integrated radiation waste boiler. The gasifier is composed of a combustion chamber, a radiation waste boiler and a quenching chamber. The integrated radiation waste boiler comprises an evaporation section and a superheating section. The gasifier can effectively utilize the energy of synthesis gas to produce superheated steam. At the same time, in order to solve the problem of attenuation of heat recovery capacity caused by ash and slagging in the radiation waste boiler, a reasonable, reliable, stable and safe control method is proposed to ensure that the process indicators are met and the device can be operated flexibly and stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Shown is a schematic structural diagram of a gasifier provided in one embodiment of the present invention.

[0018] Figure 2 Shown is a schematic structural diagram of a gasifier provided by another embodiment of the present invention.

[0019] Figure 3 Shown is a schematic diagram of a process flow of a gasifier provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] To solve the above problems, the methods commonly used in the prior art include:

[0022] 1. The radiation waste boiler is configured to include: a cylindrical water-cooled wall, which is circumferentially arranged along the inner wall surface of the radiation waste boiler to form a circumferentially sealed radiation waste boiler cavity; a plurality of heat exchange units, which are arranged in the radiation waste boiler cavity and distributed circumferentially; each group of heat exchange units includes a convection section and a first radiation screen, which are located on the same straight line and are arranged in sequence along the central axis direction from the cylindrical water-cooled wall to the radiation waste boiler cavity; the first radiation screen and the convection section of each heat exchange unit form a long radiation screen; the width of the first radiation screen is greater than the width of the convection section; the width refers to the maximum size in the circumferential direction. Although this method can produce superheated steam as a by-product and reduce the height of the radiation waste boiler, it has the following problems: First, in order to reduce the height of the radiation waste boiler, it is achieved by integrating the heat exchange pipes of the by-product saturated steam and superheated steam in one section. This structure is relatively complex and has the disadvantages of easy dust accumulation and difficulty in inspection and maintenance; Second, the maximum temperature of the superheated steam that can be produced as a by-product by the device can only reach 460°C, which is not suitable for processes with higher temperature requirements, and this temperature can only be reached when the radiation waste boiler is not dusty. If dust accumulation and slagging occur, the temperature of the superheated steam produced will be lower, and the heat of the synthesis gas cannot be effectively utilized; Third, the problem of reduced heat exchange efficiency of the radiation waste boiler is not considered, and no solution is proposed to the problems of unqualified steam parameters and unstable operation of the gasifier caused by the reduced heat exchange efficiency of the radiation waste boiler.

[0023] 2. A waste boiler ash removal integrated coal gasifier is used, including a shell, a gasification chamber, a radiation waste boiler, a quenching chamber, a sealing plate, and a three-in-one ash removal device. The gasification chamber, the radiation waste boiler, and the quenching chamber are all located inside the shell, and are arranged in sequence from top to bottom along the axis of the shell, so as to recover the sensible heat in the high-temperature synthesis gas / slag in sections, produce high-pressure superheated steam and high-pressure saturated steam, with better steam quality and higher energy recovery efficiency. Although this method solves the limitation of not being able to produce superheated steam as a by-product, its superheating section is directly exposed to the high heat flux density of the high-temperature synthesis gas of about 1300°C, and the temperature difference on both sides of the pipeline is large, which is easy to cause dry burning and damage, and has the disadvantages of complex design and poor reliability. At the same time, the problem of the decrease in the heat exchange efficiency of the radiation waste boiler is not considered, and no solution is proposed for the problems of unqualified steam parameters and unstable operation of the gasifier caused by the decrease in the heat exchange efficiency of the radiation waste boiler.

[0024] 3. A radiation waste boiler system is adopted, including a shell, a radiation waste boiler and a purge assembly. Synthesis gas / fuel gas and slag enter the radiation waste boiler from the upper inlet of the radiation waste boiler. After heat exchange through the radiation waste boiler, the synthesis gas / fuel gas is discharged through the synthesis gas / fuel gas outlet, and the slag is discharged from the lower outlet of the radiation waste boiler; the purge assembly is used to purge the radial water-cooled wall inside the radiation waste boiler to remove the ash accumulated on the surface of the water-cooled wall, thereby improving the heat exchange efficiency of the radiation waste boiler. However, there are two problems with this system. First, the radiation waste boiler system is only equipped with an evaporation section without a superheating section, and can only produce saturated steam by-product, and the scope of transportation and use is limited; second, although the patent proposes a means of purge, the purge setting provided by it is itself in the working environment of the radiation waste boiler. During long-term operation, the purge head will have the problem of ash accumulation and slagging, and the reliability is not high.

[0025] 4. A waste heat boiler main steam temperature control device is adopted. The temperature control device adds a waste heat boiler main steam temperature control loop dominated by the gas turbine flue gas temperature to the existing superheated steam temperature control system; the waste heat boiler main steam temperature control loop dominated by the gas turbine flue gas temperature includes a plurality of groups of flue gas temperature measuring devices respectively arranged at different positions in the gas turbine exhaust flue and the waste heat boiler inlet, as well as a gas turbine combustion state observation device, a data processing module and an adder. The plurality of groups of flue gas temperature measuring devices at different positions in the gas turbine exhaust flue and the waste heat boiler inlet are respectively connected to the gas turbine combustion state observation device, the gas turbine combustion state observation device is connected to the input end of the data processing module, the output end of the data processing module is connected to the input end of the adder, the input end of the adder is also connected to the output end of the superheated main steam temperature control system, and the output end of the adder is connected to the cooling water valve. However, there are two problems with this system. First, the influencing factors of the temperature fluctuation of superheated steam in this patent are mainly the gas turbine exhaust temperature and the flue gas temperature fluctuation of the waste heat boiler inlet; second, this patent only proposes control measures when the superheat degree of the outlet superheated steam is high.

[0026] In view of all the above-mentioned problems, the present invention proposes a gasifier and steam system, the gasifier is composed of a combustion chamber 1, a radiation waste boiler and a quenching chamber 5, the radiation waste boiler is composed of an evaporation section and an upper and lower superheating section, which can effectively utilize the synthesis gas energy to produce high-pressure superheated steam, and at the same time, in view of the problem of heat recovery capacity attenuation caused by ash accumulation and slagging in the radiation waste boiler, a reasonable, reliable, stable and safe control method is proposed to ensure that the process indicators meet the standards and the device is flexible and stable. See the following embodiment for details.

[0027] In one embodiment of the present invention, the gasifier includes a combustion chamber 1, a radiation waste pot and a quenching chamber 5; the radiation waste pot is arranged between the combustion chamber 1 and the quenching chamber 5; the radiation waste pot includes an evaporation section and an overheating section; the evaporation section is arranged on a side close to the combustion chamber 1; the overheating section is arranged on a side close to the quenching chamber 5. After the carbon-containing raw material 100 undergoes a gasification reaction in the combustion chamber 1 of the gasifier, the generated synthesis gas and slag materials flow downward into the radiation waste pot for heat recovery; optionally, the radiation waste pot is circulated in a natural circulation mode or a forced circulation mode. After the synthesis gas and slag materials are heat recovered from the radiation waste pot, they are further washed and cooled in a water bath in the quenching chamber 5, the slag falls into the water bath of the washing and cooling chamber, and the synthesis gas is sent from the quenching chamber 5 to downstream processing.

[0028] The gasifier is a place where carbon-containing substances, high-pressure oxygen and protective agents react to produce synthesis gas. Optionally, the gasification pressure is normal pressure ~ 6.5MPaG, and the gasification temperature is 1200 ~ 1500 ℃. Optionally, the gasifying agent is pure oxygen, high-pressure steam. Optionally, the carbon-containing substances include heavy oil, refinery dry gas, natural gas, coal slurry, dry coal powder, biomass, etc. Among them, the heavy oil is the heavy oil produced by various units of the refinery, such as: atmospheric residue oil, vacuum residue oil, hydrogenation tail oil, coking tail oil, ethylene tar, one or more of the waste oil. Optionally, the gasifier is a cold wall type or a hot wall type. The cold wall type is a water-cooled wall type (such as Figure 2 As shown), the hot wall type is refractory material type (as shown Figure 1 As shown in e).

[0029] Optionally, the gasifier of the integrated radiation waste boiler of the gasifier is a place to recover the high-level sensible heat by-product steam of the crude synthesis gas of the gasifier. Optionally, the by-product specification is superheated steam of 4 to 16.7 MPaG, and the superheat degree of the superheated steam is 5°C to 300°C.

[0030] The radiation waste boiler consists of an evaporation section and a superheating section, the evaporation section is above the superheating section, and the internal structure of the radiation waste boiler consists of an outer tube membrane water-cooled wall 13, a radial fin heat exchange surface and a radiation screen; the diameters of the evaporation section and the superheating section are the same, and the radiation screens of the evaporation section and the superheating section have the same or different structures and quantities, but the radiation screens include wide screens and narrow screens. Optionally, the radiation screen is composed of 4 to 10 tubes or U-shaped tubes, and the spacing between the wide screen and the narrow screen is 150 to 400 mm; the outer diameters of the water-cooled wall 13 and the radiation screen are 38 to 76 mm; the heat exchange area ratio of the evaporation section (including the outer tube water-cooled wall 13) to the superheating section is 1:1 to 5:1; the heat load (heat flux density) of the evaporation section and the superheating section is generally 25 to 500 kW / m2, and the heat load (heat flux density) of the evaporation section is greater than that of the superheating section; the temperature of the synthetic gas at the outlet of the radiation waste boiler is generally 600 to 1000°C.

[0031] In one embodiment of the present invention, Figure 1 and Figure 2 As shown, the radiation waste boiler includes an outer shell, a water-cooled wall 13 and a radiation screen; the water-cooled wall 13 and the radiation screen are arranged in the outer shell; the water-cooled wall 13 encloses a cylindrical space, and the radiation screen is arranged in the cylindrical space. An annular space is formed between the water-cooled wall 13 and the outer shell, and a protective gas flows through the annular space, so that the pressure in the annular space is slightly higher than that in the radiation waste boiler, so as to ensure that the annular space and the process gas side of the radiation waste boiler maintain a slight positive pressure, generally not more than 10kPa, and the designed pressure difference is 20 to 200kPa, thereby achieving the purpose of the outer tube water-cooled wall 13 bearing temperature but not pressure, and the gasification furnace shell 2 bearing pressure but not temperature, thereby reducing the requirements for equipment materials under harsh working conditions of high temperature and high pressure. Optionally, the protective gas is CO 2 、N 2 Inert gases or crude synthesis gas, etc.

[0032] In one embodiment of the present invention, the quenching chamber 5 includes a straight downcomer 12 and a quenching ring 14; the downcomer 12 is arranged in the extension direction of the quenching chamber 5; the quenching ring 14 is arranged on the side of the downcomer 12 close to the superheating section of the radiation waste boiler. The quenching chamber 5 is arranged at the lower part of the radiation waste boiler section, and the synthesis gas and slag after radiation heat extraction first enter the downcomer 12. The quenching ring 14 is arranged at the upper part of the downcomer 12. The washing water is filtered through a filter to remove large particles that may block the washing water distribution ring, and is sent to the quenching ring 14. The quenching ring 14 forms a water film on the downcomer 12 to protect the downcomer 12. After the synthesis gas enters the quenching chamber 5 through the downcomer 12 for water bath washing, the slag falls into the water bath of the washing and cooling chamber, and the synthesis gas is sent from the quenching chamber 5 to the downstream for treatment.

[0033] The quenching chamber 5 is a place where the syngas after radiation heat extraction and cooling is quenched, cooled and washed, and includes a straight downcomer 12, a quenching ring 14, a combined bubble separator and a slag breaker. The diameter of the downcomer 12 is equivalent to the inner diameter of the water-cooled wall 13 of the outer tube of the radiation waste boiler. The setting of the quenching ring 14 can make the quenching water form a relatively uniform water film in the downcomer 12. Optionally, the average thickness of the water film is 3 to 8 mm, and the flow ratio of the quenching water to the high-temperature syngas entering the downcomer 12 is 0.7:1 to 4:1.

[0034] In one embodiment of the present invention, Figure 3 As shown, the gasifier also includes a drum 6, a first pipeline 105, a first pipeline 103 and a third pipeline 104; the drum 6 is a device connecting the evaporation section and the superheating section, and is a device with water holding, steam holding, steam-water separation and sewage discharge functions, and is provided with primary separation elements such as baffles and cyclone separators, as well as secondary separation elements such as air equalizing plates and shutters to ensure that the humidity of the outlet saturated steam is not more than 0.05%, preferably not more than 0.02%; the inlet flow rate of the steam-water mixture of the drum 6 is not more than 2.5m / s, and the preferred range is 2m / s to 2.5m / s; the flow rate of the circulating boiler water at the inlet of the downcomer 12 is not more than 3m / s, and the preferred range is 2m / s to 2.5m / s.

[0035] The drum 6 is connected to the inlet of the radiation screen 3 of the evaporation section of the radiation waste boiler and the inlet of the water-cooled wall 13 through the first pipeline 105; the drum 6 is connected to the outlet of the radiation screen 33 and the water-cooled wall 13 of the evaporation section of the radiation waste boiler through the first pipeline 103; the drum 6 is connected to the inlet of the superheating section of the radiation waste boiler through the third pipeline 104. Among them, the evaporation section of the radiation waste boiler is provided with an evaporation section radiation screen inlet header 8 and an evaporation section radiation screen outlet header 7; the superheating section of the radiation waste boiler is provided with an overheating section radiation screen 4 inlet header and an overheating section radiation screen 4 outlet header; the water-cooled wall 13 is provided with a water-cooled wall inlet header and a water-cooled wall outlet header; the inner tube water-cooled wall inlet header and the evaporation section radiation screen inlet header 8 connect the first pipeline 105 of the drum 6 with the inner tube water-cooled wall 13 and the evaporation section radiation screen 3, and the function is to send circulating boiler water into the radiation waste boiler; the inner tube water-cooled wall outlet header and the evaporation section radiation screen outlet header 7 are connected to the inner tube water-cooled wall 13, the evaporation section radiation screen 3 and the second pipeline of the drum 6, and their function is to send the saturated steam-water mixture into the drum 6; the superheat section inlet header is connected to the drum saturated steam pipeline 104 and the superheat section radiation screen 4, and its function is to send the saturated steam into the superheat section; the superheat section outlet header 9 is connected to the superheat section radiation screen 4 and the fifth pipeline 109, and its function is to collect and send out the superheated steam.

[0036] The circulating boiler water in the drum 6 enters the evaporation section radiation screen inlet header 8 and the outer tube water-cooled wall inlet header 13 from the bottom of the drum 6 through the first pipeline 105, and then is naturally distributed to the heat exchange tubes of the radiation waste boiler outer tube water-cooled wall 13 and the radiation waste boiler evaporation section radiation screen 3. The supplementary boiler water 101 is continuously replenished by the pump, and the steam-water mixture after taking heat in the radiation waste boiler enters the evaporation section radiation screen outlet header 7, and then returns to the drum 6 through the first pipeline 103. Thereafter, the saturated steam after steam-liquid separation in the drum 6 enters the superheating section inlet header 10, and after natural distribution, enters the superheating section radiation screen 4 for superheating. The superheated steam enters the superheating section outlet header 9 and is sent out of the boundary area through the pipeline.

[0037] Optionally, the circulation ratio of the radiation waste boiler is 4 to 30; the circulating boiler water under-enthalpy entering the outer tube water-cooled wall 13 and the radiation screen is 10 to 300 kJ / kg; the circulation flow rate of the boiler water in the tube of the outer tube water-cooled wall 13 and the evaporation section radiation screen 3 is 0.5 m / s to 2 m / s; the upper part of the radiation waste boiler is connected to the combustion chamber 1 through a cone structure, and is connected to the quenching chamber 5 as a straight-through structure or a cone structure, preferably a straight-tube structure; the superheating section can be single-stage or multi-stage, and the number of stages is usually between 2 and 6, and the cooling facilities of the superheating section can be at the inlet, outlet and between stages of the superheating section; the cooling facilities of the multi-stage superheating section are usually 1 to 3 sets, and usually a set of cooling facilities is arranged before the last superheating section, and the steam enthalpy increment of this stage is 100 to 300 kJ / kg, which is the best.

[0038] The technical means provided in this embodiment is a regulation scheme for coping with the fluctuation of superheat degree of superheated steam caused by inconsistent decay rates in the evaporation section and the superheating section, which includes two means: external steam and injection of cooling water 108, which is essentially a step-by-step control of steam temperature; the external steam can be used to adjust the water-gas ratio of the crude synthesis gas, can replace low-grade steam, and can be sent to other superheatable equipment (such as boilers), etc.

[0039] In one embodiment of the present invention, it further comprises: a blowdown line 102 connected to the drum 6. During operation, the salt content of boiler water in the drum 6 is controlled by continuous blowdown and intermittent blowdown.

[0040] In one embodiment of the present invention, it further includes: a fourth pipeline 106; the fourth pipeline 106 is connected to the third pipeline 104; and a temperature regulating valve is arranged on the fourth pipeline 106. During the operation of the gasifier, there is a problem that the superheating section attenuates too quickly and the product steam is not superheated enough. The fourth pipeline 106 (external steam connection line 106) is arranged on the third pipeline 104 (saturated steam pipeline 104) at the outlet of the drum 6, and a temperature regulating valve is arranged on the fourth pipeline 106. The flow rate of the external saturated steam is controlled by the temperature signal of the superheated steam outlet. By adjusting the flow rate of the steam entering the superheated section, the heat extraction capacity of the superheated section is matched to control the temperature of the superheated steam and overcome the problem of insufficient superheat.

[0041] In one embodiment of the present invention, it further comprises: a desuperheater, which is arranged in the superheating section of the radiation waste boiler. In view of the problem that the attenuation capacity of the evaporation section is too fast during operation, which may cause the product steam to be too superheated, a desuperheater is arranged, and the temperature of the superheated steam is used as a regulating signal to control the injection amount of the desuperheating water 108 to achieve the purpose of temperature control.

[0042] In one embodiment of the present invention, it also includes: at least one burner, which is arranged on the side of the combustion chamber 1 away from the radiation waste pot; the burner is a conical channel. A burner is arranged on the top of the combustion chamber 1, and the burner is a nozzle of a conical channel, which is a device for feeding raw materials for gasification reaction. Optionally, the carbon-containing raw material and the protective agent can share the burner channel, or they can be set up separately; a variety of carbon-containing raw materials can enter the burner separately, or they can be mixed and then enter the same burner channel; high-pressure oxygen can be divided into a single channel or two channels to enter the burner. Optionally, the burner can be a double-channel, three-channel or multi-channel structure according to different feeding requirements. There is a cooling water system on the outside of the burner to cool the burner for protection, and the system is a jacket type or a coil type.

[0043] In one embodiment of the present invention, a steam system is provided, comprising the gasifier described in the above embodiment.

[0044] In one embodiment of the present invention, the pressure of the steam system is achieved by using a split-range control method for the pressure regulating valve of the main line and the pressure regulating valve of the vent line 107 .

[0045] The integrated radiation waste boiler proposed in this patent separates the evaporation section from the superheating section. By setting the evaporation section and the superheating section area reasonably matched, it can produce steam with higher superheat degree as a by-product, with higher heat recovery capacity and a wider range of steam use. The proposed radiation waste boiler superheating section is located below the evaporation section, which can better protect the superheating section with a smaller heat transfer coefficient and reduce the material requirements of the superheating section. In response to the problem of ash accumulation and slagging during operation, the proposed steam superheating step-by-step control scheme can deal with the problem of inconsistent attenuation rates of the evaporation section and the superheating section within a relatively wide fluctuation range, so that the superheat degree of the by-product steam can better meet the requirements and extend the single operation cycle of the gasifier.

[0046] In one embodiment of the present invention, water-coal slurry gasification is adopted, the raw material properties are shown in Table 1, the daily coal input of a single furnace is 2200t / d, the coal slurry concentration is 62wt%, the oxygen feed amount is 75t / h, the burner is a four-channel structure, which includes outer and inner coal slurry channels and central oxygen and annular oxygen channels, the effective gas output of a single furnace is 153,000 Nm3 / h, the gasification pressure is 6.5MPaG, the reaction temperature is 1220℃, an integrated radiation waste boiler gasifier is adopted, the gasifier combustion chamber 1 is a hot wall structure, the radiation waste boiler adopts a natural circulation mode, and produces 8.0MPaG, 450℃ (superheat is 154℃) steam as a byproduct. The radiation waste boiler is composed of an outer tube water-cooled wall 13, an evaporation section radiation screen 3 and an overheating section radiation screen 4. The outer tube water-cooled wall 13 is composed of 148 tubes with a specification of 48×8mm. The radiation screen is composed of 14 wide screens and 14 narrow screens. The wide screen is equipped with 8 tubes and the narrow screen is equipped with 6 tubes. The tube specification is 48×8mm. The spacing between the wide screen and the narrow screen is 220mm. The area of ​​the evaporation section (including the outer tube water-cooled wall 13) is ~676m2, and the area of ​​the superheating section is ~243m2. The area ratio of the two is ~2.8. The temperatures of the synthesis gas entering the quenching chamber 5 in the early and late stages of the operation of the radiation waste boiler are 600℃ and 910℃ respectively. N2 is used as the protective gas in the annular space, and the protective gas volume is ~1500Nm3 / h. The pressure difference between the annular space and the process gas side of the radiation waste boiler is ~5.5kPa. In the early stage of operation of the radiation waste boiler, the circulation ratio is ~10, the under enthalpy of the boiler water entering the outer tube water-cooled wall 13 and the radiation screen is 92kJ / kg, the diameter of the downcomer 12 is DN500, the flow rate is ~2m / s, the average flow rate of the outer tube water-cooled wall 13 and the evaporation section radiation screen 3 is 1.2m / s, and the steam-water mixture inlet entering the drum 6 is divided into two pipelines, both with a diameter of DN500 and a flow rate of 2.2m / s. The superheating section is set as a single stage, and a desuperheater is set at the outlet to control the superheating temperature to maintain at 450℃. The quenching water volume is ~625t / h, which is 2.8 times the high-temperature synthesis gas flow entering the quenching chamber 5.

[0047] During operation, when the evaporation section capacity decays to 90% of the initial capacity and the superheating section decays to 80% of the initial capacity, there is a problem of insufficient superheat of the superheated steam. At this time, the superheating section capacity is matched by sending saturated steam. At this time, the flow rate of the sent steam is 14.7 t / h, and this steam is sent to other processes as stripping steam. When the evaporation section capacity decays to 70% of the initial capacity and the superheating section decays to 90% of the initial capacity, there is a problem of excessive superheat of the superheated steam. At this time, the desuperheater set at the outlet of the superheating section is sprayed with cooling water 108 to adjust it. At this time, the flow rate of the boiler water sprayed is 2.4 t / h.

[0048] Table 1 Specifications of raw coal in Example 1

[0049]

[0050]

[0051] In one embodiment of the present invention, heavy oil and water-coal slurry co-gasification technology is adopted, the raw coal properties are shown in Table 1, the heavy oil properties are shown in Table 2, the daily coal equivalent of a single furnace is 2500t / d, the coal slurry concentration is 60wt%, of which the dry basis coal feed amount is 87t / h, the heavy oil feed amount is 12t / h, and the oxygen feed amount is 92t / h. The burner is a five-channel structure, which includes an outer heavy oil plus steam channel and an inner coal slurry channel and a central oxygen and annular oxygen channel, and an ignition channel is set in the center of the burner. The effective gas output of a single furnace is 175,000 Nm3 / h, the gasification pressure is 6.5MPaG, the reaction temperature is 1270℃, and an integrated radiation waste boiler gasifier is adopted. The combustion chamber 1 of the gasifier is a hot wall structure. The radiation waste boiler adopts a natural circulation method, and produces 12.5MPaG, 520℃ (superheat is 192℃) steam as a byproduct. The radiation waste boiler is composed of an outer tube water-cooled wall 13, an evaporation section radiation screen 3 and an overheating section radiation screen 4. The outer tube water-cooled wall 13 is composed of 160 tubes with a specification of 57×7mm. The radiation screen is composed of 16 wide screens and 16 narrow screens. The wide screens of the evaporation section and the overheating section are provided with 8 tubes, and the narrow screens of the evaporation section are provided with 6 tubes. The narrow screens of the overheating section adopt U-shaped tubes and adopt a 3U structure. The tube specifications are 57×7mm, and the spacing between the wide screen and the narrow screen is 190mm. The area of ​​the evaporation section (including the outer tube water-cooled wall 13) is 590m2, and the area of ​​the overheating section is 248m2. The area ratio between the two is 2.4. The temperature of the synthetic gas entering the quenching chamber 5 in the early and late stages of the operation of the radiation waste boiler is 653℃ and 968℃ respectively. CO2 is used as the protective gas in the annular space, and the protective gas volume is 2500Nm3 / h. The pressure difference between the annular space and the process gas side of the radiation waste boiler is 7.6kPa. In the early stage of operation of the radiation waste boiler, the circulation ratio is ~8, the under enthalpy of the boiler water entering the outer tube water-cooled wall 13 and the radiation screen is 165kJ / kg, the diameter of the downcomer 12 is DN550, the flow rate is ~1.7m / s, the average flow rate of the outer tube water-cooled wall 13 and the evaporation section radiation screen 3 is 0.6m / s, and the steam-water mixture inlet entering the drum 6 is divided into two pipelines, both with a diameter of DN550 and a flow rate of 1.7m / s. The superheating section is set as a single stage, and a desuperheater is set at the outlet to control the superheating temperature to maintain at 520℃. The quenching water volume is ~848t / h, which is 3.2 times the high-temperature synthesis gas flow entering the quenching chamber 5.

[0052] During operation, when the evaporation section capacity decays to 90% of the initial capacity and the superheating section decays to 70% of the initial capacity, there is a problem of insufficient superheat of the superheated steam. At this time, the superheating section capacity is matched by sending saturated steam. At this time, the external steam flow rate is 20 t / h. This steam is sent to the top of the water scrubber to increase the water-gas ratio of the synthesis gas from the original 0.62 to 0.74. When the evaporation section capacity decays to 70% of the initial capacity and the superheating section decays to 90% of the initial capacity, there is a problem of excessive superheat of the superheated steam. At this time, the desuperheater set at the outlet of the superheating section is sprayed with cooling water 108 to adjust it. At this time, the boiler water flow rate sprayed is 1.7 t / h.

[0053] Table 2 Heavy oil specifications of Example 2

[0054]

[0055]

[0056] In one embodiment of the present invention, pulverized coal gasification technology is adopted, and the properties of raw coal are shown in Table 3. The daily coal input of a single furnace is 1500t / d, the coal input is 52.5t / h, the oxygen feed is 29268Nm3 / h, and the burner is a four-channel structure, which includes a pulverized coal channel, an oxygen channel and a steam channel, and an ignition channel is arranged at the center of the burner. The effective gas output of a single furnace is 95,000 Nm3 / h, the gasification pressure is 4.0MPaG, the reaction temperature is 1400℃, and an integrated radiation waste boiler gasifier is adopted. The combustion chamber 1 of the gasifier is a water-cooled wall structure, the water-cooled wall 13 of the combustion chamber 1 adopts a forced circulation method, and the radiation waste boiler adopts a natural circulation method. The furnace water-cooled wall 13 and the radiation waste boiler evaporation section produce saturated steam with a specification of 9.8MPaG, which is sent to the radiation waste boiler superheating section through the steam drum 6 and superheated to 530℃ (superheat 220℃). The radiation waste boiler is composed of an outer tube water-cooled wall 13, an evaporation section radiation screen 3 and an overheating section radiation screen 4. The outer tube water-cooled wall 13 is composed of 140 tubes with a specification of 48×8mm. The radiation screen is composed of 10 wide screens and 10 narrow screens. The evaporation section and overheating section wide screens are provided with 6 tubes, and the evaporation section narrow screen is provided with 4 tubes. The tube specification is 48×8mm. The spacing between the wide screen and the narrow screen is 200mm. The evaporation section area (including the outer tube water-cooled wall 13) is 276m2, and the overheating section area is 140m2. The area ratio between the two is 2.0. The temperature of the synthetic gas entering the quenching chamber 5 in the early and late stages of the operation of the radiation waste boiler is 660℃ and 956℃ respectively. CO2 is used as the protective gas in the annular space, and the protective gas volume is 800Nm3 / h. The pressure difference between the annular space and the process gas side of the radiation waste boiler is 3.7kPa. In the early stage of operation of the radiation waste boiler, the circulation ratio is ~7, the under enthalpy of the boiler water entering the outer tube water-cooled wall 13 and the radiation screen is 78kJ / kg, the diameter of the downcomer 12 is DN400, the flow rate is ~1.2m / s, the average flow rate of the outer tube water-cooled wall 13 and the evaporation section radiation screen 3 is 1.6m / s, and the steam-water mixture inlet entering the drum 6 is a single pipeline with a diameter of DN500 and a flow rate of 2.0m / s. The superheating section is set as a single stage, and a desuperheater is set at the outlet to control the superheating temperature to maintain at 530℃. The quenching water volume is ~332t / h, which is 2.9 times the high-temperature synthesis gas flow entering the quenching chamber 5.

[0057] Table 3 Specifications of raw coal in Example 3

[0058] Serial number project Raw coal 1 Elemental analysis (dry basis) Composition (wt%) (1) Cd 71.72 (2) Hd 4.09 (3) Od 12.78 (4) Nd 0.86 (5) Sd 0.54 (6) Ash content 9.97 2 Industrial Analysis (1) Water content (Mt) 14.25 (2) Water content (Mad) 4.78 (3) Higher calorific value (Qgr,d) 28.34MJ / kg (4) Volatile matter Var 31.36 (5) Fixed Carbon 57.09 3 Ash fusion flow temperature (FT) 1300

[0059] During operation, when the evaporation section capacity decays to 90% of the initial capacity and the superheating section decays to 70% of the initial capacity, there is a problem of insufficient superheat of the superheated steam. At this time, the superheating section capacity is matched by sending out saturated steam. At this time, the flow rate of the sent out steam is 11.6 t / h. This steam is sent to the boiler superheating section for superheating. In this way, both the self-superheating and the sent out steam can meet the superheating requirements. When the evaporation section capacity decays to 70% of the initial capacity and the superheating section decays to 90% of the initial capacity, there is a problem of excessive superheat of the superheated steam. At this time, the desuperheater set at the outlet of the superheating section is sprayed with cooling water 108 to adjust it. At this time, the flow rate of the sprayed boiler water is 2.6 t / h.

[0060] The gasifier and steam system provided by the present invention have no restrictions on the type of gasification raw materials, processing scale, equipment size, shape, and internal parts. Any change to one or more of the above configurations cannot circumvent the constraints of this patent.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A gasifier, It is characterized in that include: Combustion chamber, radiation waste pot and quench chamber; The radiation waste pot is arranged between the combustion chamber and the quenching chamber; the radiation waste pot includes an evaporation section and a superheating section; the evaporation section is arranged on a side close to the combustion chamber; the superheating section is arranged on a side close to the quenching chamber.

2. The gasifier according to claim 1, It is characterized in that The radiation waste boiler comprises a shell, a water-cooled wall and a radiation screen; the water-cooled wall and the radiation screen are arranged in the shell; The water-cooled wall encloses a cylindrical space, and the radiation screen is arranged in the cylindrical space.

3. The gasifier according to claim 1, It is characterized in that An annular space is formed between the water-cooled wall and the shell, and a protective gas flows through the annular space.

4. The gasifier according to claim 1, It is characterized in that The quenching chamber comprises a straight downcomer and a quenching ring; the downcomer is arranged in the extension direction of the quenching chamber; the quenching ring is arranged on one side of the downcomer close to the superheating section of the radiation waste boiler.

5. The gasifier according to claim 2, It is characterized in that Also includes: a steam drum, a first pipeline, a second pipeline, and a third pipeline; The steam drum is connected to the inlet header of the radiation screen of the evaporation section of the radiation waste boiler and the inlet header of the water-cooled wall through the first pipeline; the steam drum is connected to the outlet header of the radiation screen and the water-cooled wall of the evaporation section of the radiation waste boiler through the second pipeline; the steam drum is connected to the inlet header of the superheating section of the radiation waste boiler through the third pipeline.

6. The gasifier according to claim 1, It is characterized in that Also includes: The fourth pipeline is connected to the third pipeline; the fourth pipeline is provided with a temperature regulating valve.

7. The gasifier according to claim 1, It is characterized in that Also includes: A desuperheater is arranged in the superheating section of the radiation waste boiler.

8. The gasifier according to claim 1, It is characterized in that Also includes: A blowdown line is connected to the steam drum.

9. The gasifier according to claim 1, It is characterized in that Also includes: At least one burner is arranged on a side of the combustion chamber away from the radiation waste pot; The burner is a tapered channel.

10. A steam system, It is characterized in that It comprises the gasifier as described in any one of claims 1 to 9.

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