CN1186840A

CN1186840A - Coal water slurry or pulverized coal gasifying furnace with oppositely arranged nozzles

Info

Publication number: CN1186840A
Application number: CN98110616A
Authority: CN
Inventors: 于遵宏; 龚欣; 吴韬; 王辅臣; 于广锁; 潭群钊
Original assignee: National Engineering Research Center Of Watered Coal Slurry Gasification And Coa; East China University of Science and Technology
Current assignee: National Engineering Research Center Of Watered Coal Slurry Gasification And Coa; East China University of Science and Technology
Priority date: 1998-01-19
Filing date: 1998-01-19
Publication date: 1998-07-08
Anticipated expiration: 2018-01-19
Also published as: CN1062587C

Abstract

The gasifying furnace is one vertical gas flow bed with two or more nozzles arranged symmetrically in one or several horizontal planes around the furnace. Inside the furnace, gas and liquid sludge flow parallelly and downwards and are exhausted from the outlet at the bottom. The said gasifying furnace has carbon converting rate of 98%, vapor decomposing rate of 25% and long service period. It is used in combined circular power generator, and it may be also used in preparing synthetic ammonia, synthetic methyl alcohol,and material gas for acetic acid and acetic anhydride producing hydroxylation process, producing sponge iron, CO and H2, and gasifying treatment of inflammable garbage.

Description

Multi-nozzle opposed coal water slurry or coal powder gasification furnace and application thereof

The invention belongs to the field of coal gasification, and relates to a coal water slurry or coal powder gasification furnace and application thereof.

The clean and efficient utilization of coal is a major technical subject in the field of energy and environmental protection in China at present, and is also one of the key technologies for the sustainable development of national economy in China. Coal gasification is the main way of converting primary energy into clean secondary energy, and the products are fuel gas (coal gas), synthesis gas, reducing gas, hydrogen and carbon monoxide. The coal gasification technology is widely applied in the fields of combined cycle (IGCC) power generation devices, the industry of synthesizing ammonia and methanol, the industry of producing acetic acid and vinegar by a carbonylation method, the production of sponge iron, the preparation of pure carbon monoxide, the preparation of pure hydrogen and the like, and the gasification furnace is key equipment for coal gasification. For this reason, various types of gasification furnaces have been studied and developed by many scientists. Currently, there are two main representative technologies for gasification using an entrained flow bed (spouted bed, entrained bed): a gasification furnace using coal water slurry as a raw material is Texaco (Texaco); the gasification furnaces using dry coal powder as raw material are Shell (Shell), documents U.S. Pat. No. 4,637,823, 4,527,997, 5,281,243 respectively disclose Texaco gasification furnaces, the geometrical characteristics of which are that the axis ofa nozzle is coincident with the axis of the outlet of coal gas and liquid slag, and both are on the axis of the gasification furnace main body. Since the gasifier is an entrained flow, it results in a short circuit of part of the material (stream). Our experimental tests show that if the mean residence time of the material in this type of gasifier is 5 seconds, in practice, some of the material will escape from the furnace less than 1 second, while another part will remain in the furnace for a period well in excess of 5 seconds. That is, the residence time of the material in the gasifier is a broad distribution with 50% to 60% of the material escaping the furnace less than the average residence time. In addition, the mixing effect is not ideal. For the reasons described above. The carbon conversion rate of the Texaco gasifier is generally less than 95%, and the water vapor decomposition rate is less than 20%; U.S.92-960345 discloses a schel gasifier. The gas and the liquid slag flow in opposite directions, namely the gas flows upwards and the liquid slag flows downwards. The liquid slag is easy to solidify to block a slag outlet due to no hot gas; secondly, the fine coal slag suspended in the coal gas flow can only enter downstream equipment for waste heat recovery or gas-solid separation after passing through a longer pipeline and changing the flow direction, the pipeline and the downstream equipment are easy to block, and both can shorten the operation period.

In view of the defects of the above two types of furnaces, the industry sector is eagerly expecting the related technical personnel to develop a gasification furnace with high carbon conversion rate, high gas generation amount and long-period stable production to meet the production requirement.

The invention aims to overcome the defects of the prior art and discloses an entrained flow coal waterslurry or dry coal powder gasification furnace with opposite nozzles, a vertical type, liquid slag discharging, and downward flowing coal gas and liquid slag in parallel flow and an industrial application thereof, so that the carbon conversion rate reaches more than 98 percent and the water vapor decomposition rate reaches more than 25 percent.

The idea of the invention is that: the gasification effect of the coal water slurry and the coal dust is related to the structure and the size of a nozzle, the configuration of the nozzle, the structure and the size of a gasification furnace and the structure of a flow field and the flow behavior of a fluid formed when the three are matched to realize gasification under certain process conditions besides the physical and chemical properties of the coal. That is, the quality of gasification depends mainly on the concentration distribution, temperature distribution and residence time distribution in the furnace when the coal type and process conditions are determined. At the high temperature of the gasifier, the chemical reaction rate is already quite fast, the gasification process is controlled by a heat and mass transfer process, and the transfer process and the residence time distribution mainly depend on the fluid behavior and the flow field structure in the gasifier. Therefore, more than two nozzles are symmetrically arranged on the periphery of the shell of the vertical gasification furnace, raw material coal (coal water slurry or dry coal powder) or other hydrocarbon fuels and gasification agents enter the hearth through the nozzles in a jet flow mode, jet flow streams from different nozzles impact each other in the hearth, and due to inertia, fuel particles generate damping oscillation in the hearth for many times, so that the retention time of the fuel particles in the hearth is increased; meanwhile, the turbulence intensity is obviously increased, so that the heat and mass transfer rate is greatly improved, and the carbon conversionrate of the fuel and the decomposition rate of water vapor are improved.

According to the concept, the inventor carries out large-scale cold die tests, and provides an entrained flow coal water slurry or dry coal powder gasification furnace with opposite nozzles, a vertical type, liquid slag discharging, and downward flowing coal gas and liquid slag in parallel flow, wherein the factors such as working environment, slag discharging, dust removing and the like during industrial application are considered.

The multiple nozzles are opposite, namely two or more nozzles are symmetrically arranged on one or more horizontal planes along the periphery of the gasification furnace shell.

The vertical type means that the axis of the main body of the gasification furnace is vertical to the horizontal plane.

The slag tapping means that the metal oxide in the raw material (fuel) is melted under gasification conditions and discharged as a liquid to the gasification furnace.

The coal gas and the liquid slag flow in parallel and downwards, which means that the coal gas and the liquid slag flow in the same direction in a macroscopic view and flow from top to bottom along the axis of the gasification furnace main body.

The invention will be elucidated in detail below by means of the accompanying drawings. FIG. 1 is a schematic view of a gasification furnace, and FIG. 2 is a view taken along line A-A in FIG. 1.

In the figure:

1- -metal shell

2- -refractory lining

3- -nozzle chamber

4-manhole

5- -manhole flange

6- -nozzle

7- -liquid slag and gas outlet

L- -spacing of two nozzle chambers

H- -distance between the first layer of nozzle chambers and the furnace roof

D- -inner diameter of furnace

The furnace body of the gasification furnace is an assembly which consists of a metal shell 1 and a refractory lining 2. The metal shell 1 can bear the pressure (0.1-12 Mpa) required by the process at the temperature of 0-350 ℃; two or more nozzle chambers 3 are symmetrically arranged on the same horizontal plane or a plurality of horizontal planes on the gasification furnace shell along the periphery of the furnace body, the nozzle chambers 3 are also composed of a metal shell 1 and a refractory lining 2, the middle part is a cavity for placing nozzles 6, and the nozzles are mechanically fixed in the nozzle chambers. The axis of the nozzle chamber is coincident with the axis of the nozzle and is vertical to the axis of the gasification furnace body. If two nozzles on the same horizontal plane are arranged at 180 ℃, the axes of the two nozzles are overlapped, the distance H between the first layer of nozzle chambers 3 and the furnace top is 0.5-2 times of the inner diameter D of the furnace hearth, and the distance between the two layers of nozzle chambers 3 is 0.5-2 times of the inner diameter D of the furnace hearth; the refractory lining 2 can be a combination of refractory bricks with different performances, or a cooling pipe combination covered by a slag layer and a refractory casting material, or the combination of the two modes; the upper part of the gasification furnace is a manhole 4, and the gasification furnace is sealed by a flange 5 provided with a refractory lining 2 when in operation; the lower part of the gasification furnace is provided with an outlet 7,the outlet 7 is connected with downstream equipment by a mechanical method, and the coal gas and the liquid slag are discharged out of the furnace from the outlet 7 and enter a chilling chamber or a waste heat boiler.

The gasification furnace can adopt a conventional nozzle, and if the coal water slurry is taken as a raw material, a three-channel combined coal water slurry gasification nozzle with a swirler, which is disclosed by Chinese patent CN 1125163A, can be preferentially adopted; the gasification furnace shell is also provided with a plurality of thermocouple holes and surface thermometers, and the attached drawings are omitted.

The gasification furnace takes coal water slurry, coal powder or hydrocarbon substances as raw materials, and the solid content of the coal water slurry is 50-70%; when dry coal powder is used as a raw material, water vapor is added, the ratio of the water vapor to fuel carbon is 0.05-0.65 kg/kg, when the raw materials are gasified, pure oxygen with the oxygen content of 93-99.8%, air or oxygen-enriched air is used as an oxidant (also called gasifying agent), and the ratio of the oxygen to the fuel carbon is 0.4-1.6M³(standard state)/kg, the operation pressure is 0.1-12 Mpa, and the operation temperature is 1250-1550 ℃.

The gasification furnace can be used for an integrated cycle (IGCC) power generation device, and also can be used for preparing raw material gas required by synthesis of ammonia, synthesis of methanol, production of acetic acid and dried vinegar by a carbonylation method, production of sponge iron, production of carbon monoxide, production of pure hydrogen or gasification treatment of combustible garbage.

For the above applications, the following chemical reaction equations can be used:if n is 0, combustion of carbon; if m is 0, thenFor the combustion of hydrogen, it is also possible to carry out the combustion of other combustible components, such as the combustion reaction of CO. The heat generated by the combustion reaction creates conditions for the gasification of coal, while also carrying out the reverse shift reaction and methanation reactions, as follows:

(B)

(C)

(D)

(E) and generation of H₂S、COS、NH₃HCN, HCOOH, etc.

The gasification furnace of the invention has the following remarkable advantages:

(1) the multiple nozzles are arranged oppositely, impact flow is formed in the gasification furnace, the fluid behavior and the flow field structure of the multiple nozzles are favorable for atomization and dispersion, mixing is strengthened, the heat mass transfer rate is improved, the average retention time of raw material particles is prolonged, the multiple nozzles can obviously improve the gasification effect, namely, the carbon conversion rate is improved, the content of combustible materials in ash slag is reduced, and the gas forming amount, the effective period components and the decomposition rate of water vapor of the raw material per unit mass are increased. The conversion rate of carbon can reach 98 percent, and the decomposition rate of water vapor can reach 25 percent;

(2) the shaft furnace is adopted, and a premise is created for reasonably arranging the structure of the refractory lining of the gasification furnace, so that the service life of the refractory lining is prolonged, and is prolonged by more than one time compared with the service life of a horizontal gasification furnace;

(3) the coal gas and the liquid slag flow from top to bottom along the axis of the gasification furnace body macroscopically, so that the slag bonding is effectively inhibited, and the dust removal is facilitated;

(4) the invention adopts the gasification bed (spray bed and carrying bed) and liquid slag discharge, creates conditions for the raw materials to be in a powder fog shape and high-temperature gasification, and is easy to improve the gasification pressure, thereby leading the production intensity of the gasification furnace to be obviously higher than that of a fixed (moving) bed and a fluidized bed.

Example (b): a coal gasifier of a combined cycle (IGCC) power generation device has a furnace height of 16 meters, a hearth inner diameter of 3 meters, a layer of 4 nozzles arranged oppositely, 2000 tons of Shenfu coal processed daily, coal water slurry as a raw material, solid content of 63 percent, 98 percent pure oxygen as an oxidant and oxygen-carbon ratio of 0.75M³(Standard)/kg, operating temperature 1380 deg.C, operating pressure 4.0MPa, carbon conversion 98%, and water vapor decomposition 25%.

Claims

1. A multi-nozzle opposed coal water slurry or coal powder gasification furnace mainly comprises a furnace body and nozzles (6), and is characterized in that: two or more than two nozzle chambers (3) are symmetrically arranged on the same horizontal plane or a plurality of horizontal planes on the gasification furnace shell along the periphery of the furnace body, each nozzle chamber (3) consists of a metal shell (1) and a refractory lining (2), a cavity is arranged in the middle of each nozzle chamber for placing a nozzle (6), the nozzles (6) are mechanically fixed in the nozzle chambers (3), the distance (H) between the first layer of nozzle chambers (3) and the furnace top is 0.5-2 times of the inner diameter (D) of the furnace hearth, and the distance (L) between the two layers of nozzle chambers is 0.5-2 times of the inner diameter (D) of the furnace hearth; the manhole (4) is arranged at the upper part of the gasification furnace; the coal gas and liquid slag outlet (7) is arranged at the lower part of the gasification furnace, and the coal gas and liquid slag are discharged out of the furnace from the outlet (7).

2. The gasification furnace according to claim 1, wherein: the axis of the nozzle chamber (3) is coincident with the axis of the nozzle (6) and is vertical to the axis of the gasification furnace main body, and if the two nozzles on the same horizontal plane are arranged at 180 ℃, the axes of the two nozzles are coincident.

3. The gasification furnace according to claim 1 or 2, wherein: the nozzle is a three-channel combined coal water slurry gasification nozzle with a swirler.

4. The utility model provides an application of opposite formula coal slurry of multiinjector or buggy gasifier, characterized by: the method can be used for combined cycle (IGCC) power generation devices, raw material gas for preparing synthetic ammonia, synthesizing methanol, producing acetic acid and vinegar by a carbonylation method, producing sponge iron, producing carbon monoxide, producing pure hydrogen or gasifying combustible garbage.