Gas generation system for magnesite light burning shaft kiln

Abstract

The utility model belongs to the technical field of metallurgical fuel industry, and particularly relates to a gas generation system for a magnesite light burning shaft kiln, which comprises a feed coal tank, a middle buffer tank, a coaling device, a gasification furnace, a deslagging device and a gas-solid separator, the gasification furnace is of a vertical structure and comprises a cylindrical furnace body and a conical furnace body at the bottom of the cylindrical furnace body, raw material coal enters a coal inlet in the middle section of the conical furnace body through a raw material coal groove, a middle buffer groove and a coal adding device in sequence, and gasifying agent inlets are formed in the upper portion and the lower portion of the coal inlet respectively. A gasifying agent heat exchange outlet is formed in the bottom of the air duct and is communicated with the gasifying agent inlet through a pipeline. The gasification furnace has the beneficial effects that materials are fully cracked, the mass and heat transfer process is enhanced, the gasification reaction temperature is increased, and the gasification reaction condition in the furnace is enhanced, so that the gasification intensity and the productivity are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of metallurgical fuel industry, and particularly relates to a gas generating system for a magnesite calcining vertical kiln. Background Art

[0002] The coal gasifier is a coal gasifier that uses coal gasification technology to produce coal gas with air and superheated steam as gasifiers. The mechanism used is the gasification technology of suspended fluidized bed + circulating fluidized bed, and the whole process realizes intelligent DCS digital remote control. It is safe, stable and reliable in operation, has good environmental performance, and no waste gas and waste residue are discharged. The composition of gasification can meet the fuel used for various needs. my country's coal energy accounts for about 46% of the world's total. The coal-based energy structure will not change for a long time in the future. Especially in terms of the comprehensive utilization of coal energy, it is more scientific and reasonable to expand the industry, form a modern environmentally friendly and clean technology core, and achieve the main direction of high added value of coal. Coal gasification technology is an important way to achieve clean and efficient conversion of coal, and the coal gasifier is the main equipment for coal gasification. The existing coal gasifier includes a furnace body, the inner cavity of the furnace body is formed as a gasification zone, coal powder and gasifier enter the gasification zone, and a gasification reaction occurs in the gasification zone. The raw coal gas produced by the reaction is discharged from the gas outlet on the furnace body, and the ash is discharged from the slag outlet at the bottom of the furnace body.

[0003] Coal gasifiers are also called coal gasifiers. There are many types of gasifiers according to the properties of coal and the requirements for coal gas products, including fixed bed (moving bed), fluidized bed and fluidized bed. The characteristic of fixed bed (moving bed) gasifiers is that the coal remains fixed or moves downward at a lower speed during the gasification process, which is suitable for lump coal or larger particles of coal. The characteristic of fluidized bed gasifiers is that coal particles are suspended and dispersed in the upward flowing airflow, similar to the boiling state, which is suitable for fine coal particles. The characteristic of fluidized bed gasifiers is that coal powder or water-coal slurry is fed into the gasifier at high temperature for gasification reaction, which is suitable for high temperature and rapid gasification occasions.

[0004] The Chinese utility model application number 201710500836.1 discloses a combined circulating gasification system of an entrained bed and a circulating fluidized bed and a two-stage gasification method thereof, including an entrained bed and a circulating fluidized bed that are interconnected, the entrained bed gasification uses the fly ash of the entire system as a raw material, the circulating fluidized bed gasification uses the flue gas of a certain temperature and pressure produced by the entrained bed as the primary air and gasification agent, the recycling of the flue gas makes it unnecessary for the circulating fluidized bed to continuously replenish the primary air and gasification agent, and by adjusting the pressure of the entrained bed and the mass ratio of oxygen to carbon content in the fly ash, the pressure and calorific value of the combustible gas product produced by the circulating fluidized bed can be adjusted. This scheme enables the circulating fluidized bed, the entrained bed and the heat exchange and dust removal system to form a closed loop, the fly ash is recycled, the circulating fluidized bed gasification uses the flue gas of a certain temperature and pressure produced by the entrained bed as the primary air and gasification agent, the flue gas can be reused, and the circulating fluidized bed does not need to continuously replenish the primary air and gasification agent. The disadvantage of this solution is that the fluidized bed and circulating fluidized bed are two separate devices connected in series, the equipment investment is large, and the energy consumption of the flow between materials also leads to high operating costs. In addition, there is no pre-heating process before the gasification agent enters the fluidized bed, which will inevitably cause the temperature in the fluidized bed to be low, affecting the gasification efficiency.

[0005] The Chinese utility model patent with patent announcement number CN1095494C discloses a fluidized bed pulverized coal gasification device and a method for producing coal gas using the device. The characteristics are that a fluidized bed pulverized coal gas generator with upper and lower layers of gasifying agent nozzles and no grate is used, so that the coal powder in the furnace forms a vortex, and the gasification effect is good. The disadvantage is that it uses a cold gasifying agent and the gasification efficiency is low. Utility Model Content

[0006] The utility model aims to provide a coal gas generating system for a calcined vertical kiln of magnesite ore, which overcomes the shortcomings of the prior art, adopts cheap foamed coal as a raw material, forms a gasification structure of a suspended fluidized bed + a circulating fluidized bed in a single gasifier, forms a suspended gasification zone at the bottom of the furnace, and forms a circulating fluidized zone at the top, so that large, medium and small particles of coal powder are completely gasified in different areas of the gasifier in different gasification forms in the furnace, thereby improving the gasification intensity; before the gasifier enters, it passes through the air duct of the furnace body for heat exchange and temperature rise, and can form a certain gas resistance to reduce the dust carried out in the coal gas and improve the gasification reaction temperature.

[0007] To achieve the above purpose, the utility model is implemented through the following technical solutions:

[0008] A coal gas generating system for a calcined vertical kiln for magnesite ore comprises a raw coal trough, an intermediate buffer trough, a coal feeding device, a gasifier, a slag discharging device and a gas-solid separator. The gasifier is a vertical structure, comprising a cylindrical furnace body and a conical furnace body at the bottom of the cylindrical furnace body. The raw coal enters the coal inlet of the middle section of the conical furnace body from the raw coal trough, the intermediate buffer trough and the coal feeding device in sequence. A gasifier inlet is respectively provided above and below the coal inlet. The bottom of the gas-solid separator is connected to the circulation inlet of the gasifier via a fly ash return pipeline. The invention is characterized in that an air duct is provided in the furnace wall of the cylindrical furnace body, a gasifier heat exchange inlet is provided at the top of the air duct, a gasifier heat exchange outlet is provided at the bottom of the air duct, and the gasifier heat exchange outlet is communicated with the gasifier inlet through a pipeline.

[0009] The structure at the gasification agent inlet is an annular air duct, including an outer brick and an inner brick, a circulating air duct is arranged between the outer brick and the inner brick, the outer brick is evenly and radially provided with 6-8 air inlet pipes along the circumferential direction, the air inlet pipes are connected with the circulating air duct, and the inner brick is evenly and radially provided with 8-12 air inlets around the circumferential direction, the air inlets connect the circulating air duct on the outer side of the inner brick with the circular hole on the inner side.

[0010] The gas-solid separator is any one of a multi-tube cyclone separator, a centrifugal gas-solid separator, a cyclone gas-solid separator, a CLP cyclone separator, a filtering gas-solid separator, and a diffusion cyclone separator.

[0011] The gasifying agent used in the gasifier is a mixture of air and water vapor. The air and water vapor are mixed in a mixer and then connected to a primary inlet of the gasifier through a pipeline.

[0012] The coal loading and slag discharging processes of the gasifier are all fully enclosed structures, and no waste slag is discharged.

[0013] The fly ash return pipeline has a fly ash gravity angle.

[0014] Compared with the prior art, the beneficial effects of the utility model are:

[0015] 1) The utility model system adopts a circulating fluidized bed + suspended fluidized bed gasification technology to produce coal gas using cheap pulverized coal as raw material and air and superheated steam as gasifying agents. Compared with the lump coal used in a fixed bed gasifier, the cost of raw material pulverized coal is greatly reduced, and the composition of gas production can meet a variety of needs.

[0016] 2) The gasification intensity is high. The raw coal particle size and the gasifying agent with appropriate proportion are sprayed into the gas duct for gasification in parallel with the foam coal. The reaction velocity of the materials in the furnace is strictly controlled, so that the fluidized bed + circulating fluidized bed is first suspended and dispersed, and then a dense phase section area and a dilute phase section area are formed. The main purpose is to fully crack the materials, strengthen the mass transfer and heat transfer process, and make the gasification reaction tend to be balanced, stable and continuous. The nozzle on the upper part of the gasifier can enlarge the gasification reaction space, thereby forming a certain gas resistance to reduce the dust carried out in the coal gas, increase the gasification reaction temperature, and strengthen the gasification reaction conditions in the furnace, thereby improving the gasification intensity and production capacity, high carbon conversion rate and complete cracking of volatile matter in coal.

[0017] 3) During gasification, tar substances undergo secondary cracking, and no tar substances or phenolic substances are generated. The gasification temperature is increased by injecting gasifying agents through nozzles, and a gas mold is formed, where unburned fine particles of pulverized coal and dust from multi-tube separators undergo secondary gasification to intensify the reduction of carbon dioxide to carbon monoxide, thereby increasing the volatile yield and carbon conversion rate of pulverized coal in the gasifier, obtaining high-quality gas components and reducing coal consumption.

[0018] 4) Energy-saving utilization of heat energy recovery. The hot coal gas produced by the gasifier is directly sent to the combustion system. The high-temperature exhaust gas produced by the combustion system is exchanged with the cold air of the gasifier to recover part of the heat. The gasification agent uses the self-produced steam of the combustion system to reduce the heat consumption of the entire gasification device system.

[0019] 5) The whole system of the gasifier is operated in a closed manner and adopts an advanced, reliable, and highly automated control system, which meets the environmental emission requirements and ensures that the control equipment is advanced and reliable, which can ensure the long-term and safe production and operation of the process unit; the coal conveying system, gas conveying system, dry ash removal system, and the foam coal gasifier can all be automatically controlled and centrally controlled in the central control room, without operators on site. The whole process unit is fully closed and remotely controlled by DCS intelligent digital control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of an embodiment of the utility model;

[0021] Figure 2 It is a schematic diagram of the structure of the gasifier in the embodiment of the utility model;

[0022] Figure 3 yes Figure 2 Section view along line AA.

[0023] In the figure: 1-upper coal chute, 2-upper coal valve group, 3-middle buffer chute, 4-middle chute valve group, 5-lower coal chute, 6-lower coal chute valve group, 7-coal adding device, 8-slag discharging device, 9-first slag discharging valve group, 10-first slag discharging chute, 11-slag discharging middle valve group, 12-second slag discharging chute, 13-second slag discharging valve group, 14-gasifier, 15-gas-solid separator, 16-mixer, 17-fly ash return pipeline, 18-coal inlet, 19-gasifying agent inlet, 20-circulation inlet, 21-air duct, 22-gasifying agent heat exchange inlet, 23-gasifying agent heat exchange outlet, 24-outer brick, 25-inner brick, 27-circulation duct, 28-air inlet. DETAILED DESCRIPTION

[0024] The technical solution of the present utility model will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present utility model, rather than all of the embodiments.

[0025] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the specific embodiments required to be used in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation methods of the utility model. For ordinary technicians in this field, other specific embodiments can be obtained based on these specific embodiments without paying creative work.

[0026] The components of the embodiments of the present invention generally described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the utility model claimed, but only represents the selected embodiments of the utility model.

[0027] See Figure 1-2 , is a schematic diagram of the structure of a gas generating system for a magnesite calcined vertical kiln according to the utility model, including a raw coal trough (including an upper coal trough 1 and a lower coal trough 3), an intermediate buffer trough 3, a coal feeding device 7, a gasifier 14, a slag discharge device 8 and a gas-solid separator 15. An upper coal valve group 2 is provided under the upper coal trough 1, an intermediate trough valve group 4 is provided under the intermediate buffer trough 3, and a lower coal trough valve group 6 is provided under the lower coal trough 5. A nitrogen protection pipeline can be provided for the lower coal trough valve group 6 as required, and a mechanical vibration device is provided for the intermediate buffer trough 3 and the lower coal trough 5. The pulverized coal sent by the coal preparation system enters the upper coal trough 1, the intermediate buffer trough 3, and the lower coal trough 3 through the transmission equipment, and then enters the gasifier 14 through the coal feeding device 7.

[0028] The bottom of the gasifier 14 is connected to the slag discharge device 8, and the first slag discharge valve group 9, the first slag discharge trough 10, the slag discharge intermediate valve group 11, the second slag discharge trough 12, and the second slag discharge valve group 13 are sequentially arranged under the slag discharge device 8 to realize the closed storage and discharge of the slag. The first slag discharge valve group 9 and the slag discharge intermediate valve group 11 are provided with nitrogen protection pipelines. The slag discharge device 8, the first slag discharge trough 10, and the second slag discharge trough 12 are provided with a circulating cooling water device. The lower part of the slag discharge intermediate valve group 11 is connected to a pneumatic conveying device, and the coal slag is pneumatically conveyed to the slag bin without external pollution.

[0029] The gasifier 14 is a vertical structure, including a cylindrical furnace body and a conical furnace body at the bottom of the cylindrical furnace body. The raw coal enters the coal inlet 18 in the middle section of the conical furnace body from (including the upper coal trough 1 and the lower coal trough 3), the middle buffer tank 3, and the coal feeding device 7 in sequence. Gasifier inlets 19 are provided above and below the coal inlet, respectively. The bottom of the gas-solid separator 15 is connected to the circulation inlet 20 of the gasifier through the fly ash return pipeline 17. The fly ash return pipeline 17 has a fly ash self-flow angle. The pulverized coal separated by the gas-solid separator 15 is returned to the gasifier through the fly ash return pipeline 17. The gasifier temperature at the gasifier inlet is 950°C-1100°C.

[0030] The gasifying agent is a mixture of air and water vapor. The air and water vapor are mixed in the mixer 16 and connected to the primary inlet of the gasifier through a pipeline. The volume ratio of air to water vapor is 2:1, and the pressure is 0.04-0.05MPa. The gasifying agent (air) from the blower passes through the heat exchanger of the fuel combustion system and is mixed with the superheated steam from the fuel combustion system in the mixer 16, and then enters the gasifying agent inlet 19 provided above and below the coal inlet, respectively, and enters the gasifier 14.

[0031] An air duct 21 is provided in the furnace wall of the cylindrical furnace body. The air duct 21 is a space between the outer furnace wall and the inner furnace wall. A gasifier heat exchange inlet 22 is provided at the top of the air duct 21. A gasifier heat exchange outlet 23 is provided at the bottom of the air duct 21. The gasifier heat exchange outlet 23 is connected to the gasifier inlet 19 through a pipeline. The gasifier (a mixture of air and water vapor) enters from the upper part of the air duct and flows out from the lower part. The gasifier exchanges heat with the inner furnace wall and the temperature rises to 650°C. The gasifier 14 is A mixed gasification structure of suspended fluidized bed + circulating fluidized bed is formed, the pressure in the furnace is 10-15kPa, and the DCS control system is used to control the formation of a suspended gasification zone at the bottom of the furnace and a circulating fluidized zone at the top, so that coal powder with different particle sizes below 8mm can be completely gasified in different gasification forms in different areas of the gasifier; the calorific value of the coal powder is not less than 3500Kcal / kg; the temperature of the coal gas discharged from the gas-solid separator 15 is 900℃, and the calorific value is not less than 1300Kcal / Nm 3The generated coal gas is directly sent to the users of magnesite light burning vertical kiln, tunnel kiln or suspension kiln after passing through the gas-solid separator 15, without the need for additional heat exchange and cooling. Under the above conditions, the pulverized coal and gasifying agent in the gasifier undergo complex chemical reactions such as decomposition, oxidation, and reduction to generate coal gas. The generated coal gas and dust enter the gas-solid separator 15 from the top of the gasifier 14 for gas-solid separation, and the separated fly ash returns to the gasifier 14 for cyclic gasification.

[0032] See Figure 3 The structure at the gasifying agent inlet 19 is a ring-shaped air duct, including an outer brick 24 and an inner brick 25. A circulating air duct 27 is arranged between the outer brick 24 and the inner brick 25. The outer brick 24 is provided with a plurality of air inlet pipes uniformly and radially along the circumferential direction. The air inlet pipes are connected to the circulating air duct. The inner brick 25 is provided with a plurality of air inlets 28 uniformly and radially around the circumferential direction. The air inlets 28 connect the circulating air duct on the outer side of the inner brick 25 with the circular hole on the inner side.

[0033] In the embodiment, the gas-solid separator 15 is a multi-tube cyclone separator, and may also be any one of a centrifugal gas-solid separator, a cyclone gas-solid separator, a CLP cyclone separator, a filtering gas-solid separator, and a diffusion cyclone separator.

[0034] The embodiment of the utility model is characterized in that the coal loading and slag discharging processes of the gasifier are all fully enclosed structures, and no waste slag is discharged. The raw coal can be any one of low-priced coals such as lignite, long flame coal, weakly sticky coal, non-sticky coal, or any combination of two or more; the particle size is less than 8mm. The weight percentage of the particle size distribution of the raw coal is: 25% below 0.5mm, 25% between 0.5-6mm, and 50% between 6-8mm.

[0035] The technical and economic performance of the gasifier in the embodiment of the utility model is shown in Table 1.

[0036] Table 1

[0037]

[0038]

[0039] The composition of the coal gas produced by the embodiment of the utility model is shown in Table 2.

[0040] Table 2

[0041] composition CO <![CDATA[H2]]> <![CDATA[CO2]]> <![CDATA[CH4]]> <![CDATA[O2]]> <![CDATA[N2]]> V(％) 18-21 17-20 10-12 3 0.2 45-48

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A coal gas generation system for a calcined vertical kiln of magnesite ore, comprising a raw coal trough, an intermediate buffer trough, a coal feeding device, a gasifier, a slag discharge device and a gas-solid separator, wherein the gasifier is a vertical structure, comprising a cylindrical furnace body and a conical furnace body at the bottom of the cylindrical furnace body, the raw coal sequentially enters the coal inlet of the middle section of the conical furnace body from the raw coal trough, the intermediate buffer trough and the coal feeding device, a gasifying agent inlet is respectively provided above and below the coal inlet, the bottom of the gas-solid separator is connected to the circulation inlet of the gasifier via a fly ash return pipeline, and is characterized in that: An air duct is arranged in the furnace wall of the cylindrical furnace body, a gasifying agent heat exchange inlet is arranged at the top of the air duct, a gasifying agent heat exchange outlet is arranged at the bottom of the air duct, and the gasifying agent heat exchange outlet is connected with the gasifying agent inlet through a pipeline.

2. A gas generating system for a magnesite calcining shaft kiln according to claim 1, characterized in that: The structure at the gasification agent inlet is an annular air duct, including an outer brick and an inner brick, a circulating air duct is arranged between the outer brick and the inner brick, the outer brick is evenly and radially provided with 6-8 air inlet pipes along the circumferential direction, the air inlet pipes are connected with the circulating air duct, and the inner brick is evenly and radially provided with 8-12 air inlets around the circumferential direction, the air inlets connect the circulating air duct on the outer side of the inner brick with the circular hole on the inner side.

3. A gas generating system for a magnesite calcining shaft kiln according to claim 1, characterized in that: The gas-solid separator is any one of a multi-tube cyclone separator, a centrifugal gas-solid separator, a cyclone gas-solid separator, a CLP cyclone separator, a filtering gas-solid separator, and a diffusion cyclone separator.

4. A gas generating system for a magnesite calcining shaft kiln according to claim 1, characterized in that: The gasifying agent used in the gasifier is a mixture of air and water vapor. The air and water vapor are mixed in a mixer and then connected to a primary inlet of the gasifier through a pipeline.

5. The gas generating system for a magnesite calcining shaft kiln according to claim 1, characterized in that: The coal loading and slag discharging processes of the gasifier are all fully enclosed structures, and no waste slag is discharged.

6. The gas generating system for a magnesite calcining shaft kiln according to claim 1, characterized in that: The fly ash return pipeline has a fly ash gravity angle.

Images