JPS63168487A - Method and equipment for coal gasification - Google Patents

Abstract

PURPOSE:To recover a gas of high N2 concentration for utilization in conveying coal and in pressurizing a coal-packed container, thereby enabling the realization of smaller equipment for gasification, by installing a unit for holding the gas discharged in the latter period of a desorption stage. CONSTITUTION:The air compressed by a compressor 31 is fed into the top of an adsorption and desorption tower 21, wherein N2, rather than O2, is selectively adsorbed. Air rich in O2 is discharged from the bottom of the tower 21 and blown into a coal burner 25. While the adsorption and desorption tower 21 is in an adsorption stage, desorption is effected in an adsorption and desorption tower 22, and the gas in the tower 22 is discharged into the air from the top. As the discharge of the gas in the tower proceeds, the pressure in the tower decreases so that the desorption of N2 adsorbed by an adsorbent is effected and the N2 concentration of the discharged gas increases. The discharged gas having an N2 concentration of 95% is once stored in a storage tank 23, from which it is sent to a coal-packed container 24, with the feed rate being controlled by a valve 41, to pressurize the container so that the coal is pneumatically conveyed through a coal feeding pipe 28 to a coal burner 25. In a coal gasifier 26, a combustible gas is produced from the coal supplied through the coal burner 25 and a coal gasifying agent.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a gasification device for coal or other hydrocarbons (tar, 1 coal liquefaction residue, etc.), and in particular, the present invention relates to a gasification device for coal or other hydrocarbons (tar, 1 coal liquefaction residue, etc.), and in particular, a gasification device for supplying fuel with gas generated by a pressure fluctuation adsorption method to a gasification furnace in an air stream. The gasification agent produced at the same time is supplied to the gasification furnace to generate high temperature,
The present invention relates to a coal gasification method and apparatus for producing flammable gas by reacting under high pressure. [Conventional technology] Coal is a useful energy source with abundant reserves, but
Because it is solid and contains a large amount of ash, its applications are limited compared to oil and natural gas. However, if this coal is converted into gas or liquid, the fields of use will expand widely and it can become a useful energy source. Therefore, coal fluidization technology is being developed in various countries, and coal gasification technology is the next generation. Research and development is progressing as an important elemental technology for coal gasification combined cycle power generation, which is attracting attention as a power generation method. Coal gasification is the process of crushing coal and supplying it to a high-temperature furnace together with a gasifying agent to cause gasification reactions such as partial oxidation, thereby producing flammable gas whose main components are carbon monoxide and hydrogen. That's what I'm saying. A coal gasification combined cycle power generation system recovers the sensible heat of the high-temperature combustible gas obtained through coal gasification to create steam, which drives a steam turbine, and at the same time, this combustible gas drives a gas turbine. This type of combined power generation system, such as a coal gasification combined cycle system, can improve power generation efficiency by several percentage points compared to conventional coal-fired power generation, which burns coal to drive a steam turbine. Anticipating large-scale demand, the coal gasification equipment will also have a large capacity. Development is progressing with increasing efficiency. When gasifying coal for the purpose of generating electricity,
There are two main types of methods: oxygen gasification, which uses oxygen as a gasification agent, and air gasification, which uses air. A comparison of gasification efficiency, gas and other agent production costs, and power generation costs for different gasification methods is shown below. In the oxygen gasification shown in Table 1, the efficiency of the gasifier is good because all of the gasifying agent is reacted, but the cost of producing oxygen increases, which increases the cost of power generation. On the other hand, in air gasification, nitrogen, which does not react as a gasification agent, is also supplied to the furnace, so the efficiency of the gasification furnace is low, but since there is no production cost for oxygen, the cost of power generation is low. Cold gas efficiency is used as an indicator of coal gasification efficiency. Cold gas efficiency represents the ratio of the calorific value of the gas generated from the coal to the heating lid of the coal supplied to the furnace.As for the ratio of the amount of gas and other agents supplied to the amount of coal supplied, cold gas efficiency is the highest. It is necessary to set the value as follows. Coal gasification is generally based on a partial oxidation reaction, which is expressed by the following formula. Here, for simplicity, coal is expressed as a hydrocarbon, excluding components such as ash. As can be seen from the above equation, the calorific value of the generated gas is highest when all of the carbon in the coal is converted to carbon monoxide. Since this reaction is exothermic, the reaction proceeds without applying external heat. However, when air is used as the gasifying agent, even though there is heat generated due to one reaction, the temperature inside the furnace cannot be raised sufficiently because the temperature of the nitrogen contained in the air supplied as the gasifying agent is also raised. First, there is a drawback that the gasification reaction rate becomes slow, thereby reducing the gasification rate. Particularly when gasifying coal in an air bed, one of the major features of air bed gasification is to melt the ash in the coal. It is necessary to raise the temperature higher than that, and the heat generated by the partial oxidation reaction in the above equation is insufficient. Therefore, the amount of oxygen is generally increased and the following combustion reaction is performed in parallel with the reaction in the above equation. However, if the combustion reactions are performed simultaneously, the amount of carbon monoxide CO in the generated gas decreases, and the calorific value decreases, resulting in a decrease in cold gas efficiency. Therefore, it is conceivable to use oxygen-enriched air as the air used as the gasifying agent, reduce the amount of nitrogen, which is an inert gas, contained in the air, and maintain the gasifier at a high temperature through only the partial oxidation reaction. The amount of oxygen in this oxygen-enriched air does not need to be high-purity oxygen, even in the case of gasification by gaseous bed, as long as the temperature inside the furnace can be maintained above the melting temperature of the ash. In addition to the gasifying agent, the gases required for the gasifier include gas for transporting the coal and gas for pressurizing the coal-filled container. Steam, air, etc. are used to pipe the coal from the coal-filled container. When feeding coal to a gasification furnace by airflow conveying through coal, if there is a difference between the pressure inside the conveying pipe and the pressure inside the coal filling container, the coal will not be smoothly fed from the coal filling container to the conveying pipe. Usually, the inside of the coal-filled container is constantly pressurized to the same level as the pressure inside the conveying pipe using pressurized gas. Various types of coal gasifiers are being developed, and the specification of JP-A No. 56-122891 describes a method in which oxygen is used as a reactant gas, water vapor is used as a gas other agent/carrier gas,
Additionally, devices have been described that partially use nitrogen as carrier gas. Conventionally, in such a case, it is customary to simultaneously produce both oxygen and nitrogen by a cryogenic method, but as a method for producing only nitrogen, a pressure fluctuation adsorption method is disclosed in Japanese Patent Application Laid-open No. 52-152895. Law (PRESSURE 5
IIIING ABSORBTION (hereinafter referred to as PSA method) is described. In this PSA method, a mixed gas containing oxygen and nitrogen is fed from one end (termed A end) to an adsorption tower filled with an adsorbent that selectively adsorbs nitrogen over oxygen until a predetermined pressure is reached. After the adsorption is completed, high-concentration nitrogen gas is fed into the adsorption tower from the other end (termed B end), and this causes the nitrogen gas remaining in the adsorption tower to be absorbed. The oxygen-rich air that is in the air is discharged from the A end, and when the nitrogen concentration of the discharged gas becomes equal to the nitrogen concentration of the high concentration nitrogen sent from the B end, the exhaust from the A end is stopped, and then the B
The gas inside the adsorption tower is extracted from the end. The gas extracted is highly concentrated nitrogen that has been adsorbed on the adsorbent, and by repeating this process, the adsorbed nitrogen can be separated and highly concentrated nitrogen gas can be recovered. The PSA method produces only highly concentrated nitrogen, but if the PSA method is used instead of the deep cooling method conventionally used for oxygen production, oxygen-enriched air that can be used as a gasifying agent can be obtained at a low cost. Since a higher gasification efficiency can be obtained compared to air gasification, power generation costs can be further reduced compared to a system that gasifies coal using only air. [Problems to be Solved by the Invention] Conventionally, steam, air, etc. have been used as the gas for transporting coal. However, when steam is used as the gas for transporting coal, the details of Japanese Patent Application Laid-Open No. 56-122891 As stated in the document, there is a risk of difficulties in transporting coal due to water vapor condensation at the start of transport. In addition, when air is used as a gas for conveyance or pressurizing coal-filled containers, it is necessary to always take precautions against coal dust explosions, as described in the specification of Japanese Patent Publication No. 58-23295, and to prevent spontaneous combustion. From this point of view, it is necessary that the oxygen concentration is at most 5% or less. The conventional cryogenic method used to produce oxygen produces high-purity nitrogen at the same time as oxygen, which can be used as a gas for transporting coal. However, in the PSA method using an adsorbent that selectively adsorbs nitrogen over oxygen, as shown in Table 2, when oxygen-enriched air is generated, the nitrogen-enriched air produced at the same time has less oxygen than air. Although the concentration is low, the oxygen concentration is still too high for coal transportation, and it cannot be used as a transportation gas.Therefore, the nitrogen for transportation gas must be brought in from another plant, or nitrogen production is used for purposes other than gas and other agent production. The power generation plant shown in Table 2 uses a gasifier that uses oxygen-enriched air produced by the PSA method as a gasification agent, which has an impact on the overall cost of the power plant. There was a problem with the cost. The subject of the present invention is to use oxygen-enriched air simultaneously generated by the PSA method as a gasifying agent, and use nitrogen-14 enriched air as a coal conveying S'
The object of the present invention is to provide a method and apparatus for coal gasification that is used for a pressurizing body and a pressurizing body for a coal-filled container. [Means for solving the problem] The above problem is caused by the fact that the exhaust gas from the desorption process is removed from the adsorption/desorption group provided in the adsorption/desorption group of a pressure fluctuation adsorption device that uses an adsorbent that selectively adsorbs nitrogen over oxygen. A device is installed in the pipe from which the gas is taken out to accommodate the gas discharged in the latter half of the desorption process, and the oxygen-enriched air produced by the pressure fluctuation adsorption device is used as a gasification agent to collect the gas discharged in the latter half of the desorption process. This is achieved by using concentrated nitrogen gas for transporting the coal through the device containing the exhaust gas and for pressurizing the coal-filled vessel.

[Effect]

By providing a storage device for the gas discharged in the latter stage of the desorption process in the exhaust pipe of the exhaust gas in the desorption process of the adsorption/desorption group of a pressure fluctuation adsorption device using an adsorbent that selectively adsorbs nitrogen over oxygen. Of the exhaust gases whose nitrogen concentration changes over time, which are discharged in the desorption process, only the gas with a high nitrogen concentration discharged in the latter half of the desorption process can be collected in this storage device. Therefore, by setting the minimum nitrogen concentration of the recovered exhaust gas to the concentration required for the gas used for conveying coal and pressurizing the coal filling container, the recovered exhaust gas can be used for coal conveyance in a coal gasifier. It can also be used to pressurize coal-filled containers without worrying about spontaneous combustion or dust explosions. [Example] The amount of carrier gas for transporting coal does not need to be four times the amount of gasifying agent for gasifying the transported coal, and only a small amount is required. Instead of recovering a large amount of nitrogen-containing gas with a low nitrogen concentration, we simultaneously collect a small amount of gas with a high nitrogen concentration that can be used as it is for conveying coal and pressurizing coal filling containers, and oxygen-enriched air. A removable PSA! Developed l Kasumi. The PSA method is a method in which a specific gas component is adsorbed at high pressure by an adsorbent filled with an adsorption/desorption group, and the previously adsorbed gas component is taken out (desorbed) at low pressure. Therefore, the high-pressure layer (
The gas extracted during the adsorption step (adsorption step) has a low concentration of a specific component, while the gas extracted under low pressure (the desorption step) has a high concentration of the same specific component. Generally, in order to separate oxygen and nitrogen from the air using the PSA method, a zeolite-based adsorbent is used to adsorb nitrogen to generate a gas with a high oxygen concentration. The inventors noticed that the nitrogen concentration in the exhaust gas from the desorption process of a PSA device is not constant, but changes over time during the desorption process. Figure 5 shows the gas that is discharged in the desorption process after air is introduced into an adsorption/desorption group filled with an adsorbent that adsorbs nitrogen more selectively than oxygen, adsorbs nitrogen, and extracts oxygen-enriched air. It shows the change in nitrogen concentration in the water over time. The exhaust gas from the adsorption/desorption group exhibits a nitrogen concentration almost equal to that of air at the beginning of the desorption process, but as the desorption process progresses, the nitrogen adsorbed by the adsorbent in the adsorption process is desorbed and fills the column. Nitrogen concentration in exhaust gas increases. Utilizing this change, we can separate the process of discharging the air filling the voids in the tower at the beginning of the desorption process from the original desorption process at the latter stage of the desorption process, and transport the high-concentration nitrogen gas released in the latter stage to the coal. and invented a process for pressurizing coal-filled containers. The present invention will be explained in detail below. FIG. 1 is a system diagram of a coal gasification apparatus to which the present invention is applied. The discharge side piping of the air compressor 31 that takes in atmospheric air and compresses and discharges it is branched into two parts, one of which is connected to the adsorption/desorption group 21 via the valve 11.
and the other to the top of the adsorption/desorption group 22 via the valve 13, respectively. The adsorption/desorption group is filled with an adsorbent that selectively adsorbs nitrogen over oxygen, and extraction pipes 29 and 30 are provided at the bottom of the adsorption/desorption group, and the two are connected together after passing through valves 15 and 16, respectively. and is connected to the inlet side of the gas and other agent compressor 33. Gas and other agent compressor 33
The outlet side piping of is connected to a coal burner 25 provided in a gasifier 26. Desorption gas discharge pipes 42 and 43 are further provided at the top of the adsorption and desorption furnaces 21 and 22, respectively, which pass through valves 12 and 14 and then join together.
It is connected to an exhaust gas extraction device (not shown) via. After the discharge pipes 42 , 43 come together and before entering the valve 17 , a branch pipe 44 is provided, which is connected via the valve 18 to the inlet side of the carrier gas compressor 32 . Carrier gas compressor 32
The discharge side of is connected to a carrier gas storage tank 23, which is connected to a coal supply pipe 28 via a valve 19.
A feeder 40 is provided at the bottom of each of the six coal filling containers 24 connected to the coal filling container 24 via a valve 41, and a coal gasifier 26 is connected to the feeder 40 via a valve 10.
A coal supply pipe 28 is connected to a coal burner provided in the coal burner. The procedure for supplying coal and gasifying agent to the gasifier 26 using the apparatus shown in FIG. 1 is as follows. The adsorption/desorption groups 21 and 22 perform adsorption and desorption alternately, and in the process in which the adsorption/desorption group 21 performs adsorption, the adsorption/desorption group 22 is in the desorption process, and the valve is operated in the next state. Adsorption/desorption group 21...Adsorption process Adsorption/desorption group 22...Desorption process Valves 11, 14, 15...Open valves 12, 13, 16...Closed air is pressurized by the air compressor 31, and the valve 11 to the top of the adsorption/desorption group 21. In the adsorption/desorption group 21, nitrogen is adsorbed more selectively than oxygen, and oxygen-enriched air having a higher oxygen concentration than air is discharged from the bottom. This oxygen-enriched air passes through the valve 15 and the extraction pipe 29, is sucked into the gas and other agent compressor 33, is increased to the required pressure, and is ejected to the coal burner 25. When the adsorption/desorption group 21 is in the desorption process, the adsorption/desorption group 22 performs the same operation as described above. When the adsorption/desorption group 21 is in the adsorption process, the adsorption/desorption group 22 is in the desorption process. Figure 5 shows the change over time in the nitrogen concentration of the exhaust gas during the desorption process. The tower gas is discharged from the top of the adsorption/desorption group 22 through the discharge pipe 43 and the valve 14 . In this case, since the air is discharged from the top of the adsorption/desorption group, which is the air supply side, nitrogen adsorption has not progressed sufficiently, and at the initial stage of desorption, a gas having approximately the same composition as air is discharged. That is, in region A shown in FIG.
7 and close the valve 18 to take out nitrogen gas with a nitrogen concentration of 95% or less to an exhaust gas extraction device (not shown). As the gas in the tower is further discharged, the pressure inside the tower decreases and the gas is adsorbed by the adsorbent. As a result, the nitrogen concentration of the gas discharged from the top of the adsorption/desorption group 22 increases. That is, in region B of FIG. 5, valve 17 is closed and valve 18 is closed.
Open the carrier gas compressor 32 to drive the nitrogen concentration to 95.
% or more is inhaled and compressed. Since this compressed gas is not produced continuously, the carrier gas storage tank 23
On the one hand, the coal is sent to the coal filling container 24 to pressurize the container while the supply amount is adjusted by the valve 41, and on the other hand, the coal is sent to the coal supply pipe 28 while the supply amount is adjusted by the valve 19. 1 Coal supplied from the coal filling container 23 to the coal supply pipe 28 by the feeder 40 is conveyed by air flow to the coal burner 25. In the coal gasification furnace 26, a gasification reaction is performed using the coal supplied from one coal burner 25 and a coal gasification agent, and combustible gas is generated. During the desorption process of adsorption/desorption groups, the pressure inside the adsorption/desorption column is increased. When the predetermined pressure is reached, the process is stopped, and the valve is opened and closed.The adsorption/desorption group that used to be the adsorption process starts the desorption process, and the adsorption/desorption group that used to be the desorption process starts the adsorption process.
By repeating these steps, the high-concentration nitrogen gas produced by the PSA method can be used for conveying coal and for pressurizing coal-filled containers. Furthermore, in this embodiment, the carrier gas compressor 32 can be used both as a compressor used to pressurize exhaust gas with a high concentration of nitrogen and as a vacuum pump used for the desorption process. It can be simplified and the cost of the entire system can be reduced. The amount of coal conveying gas to be used is 5. Considering the conditions for stable conveyance of coal, when nitrogen gas is used, it is most preferable to set the following: amount of nitrogen used (kg) / amount of coal supplied (kg) = 0.1. FIG. 2 shows an example in which the embodiment shown in FIG. 1 is applied to a coal gasification combined cycle power generation system. In addition to the equipment shown in FIG. 1, in FIG. gas turbine 52. Heat exchanger a53 . connected to gas turbine 52 . A steam turbine 54 . connected to the heat exchanger 53 and interlocked with the gas turbine 52 . Air compressor 55 driven by steam turbine 54 and gas turbine 52
and generator 56. From the discharge port of the air compressor 55 to the valve 62
A pipe 45 is connected to the combustor 51 through the pipe 45, and a pipe 46 is connected from the discharge port to the valves 11 and 13 through the valve 61.
is provided. The air compressor 31 described in the embodiment of FIG. 1 is not provided, but is provided in conjunction with an air compressor 55 driven by a steam turbine 54 and a gas turbine 52, and plays the same role. This device is
The combustible gas generated in the moving coal gasifier 26 as described below is sent to the gas purification tower 27, where sulfur and ash are removed to produce purified gas. The purified gas is then sent to the combustor 51, where it is combusted by air sent from the air compressor 55 with the flow rate adjusted by a valve 62. This combustion drives the gas turbine 52, and the combustion exhaust gas is sent to the heat exchanger 53 where it exchanges heat and produces steam. The steam produced by the heat exchange $53 is sent to a steam turbine 54 to drive the steam turbine. Gas turbine 52, steam turbine 54. Air compressor 55 and generator 56
are interlocked, and part of the energy obtained by the gas turbine 52 and the steam turbine 54 becomes the power for driving the air compressor 55, and the rest is transmitted to the generator 56 and converted into electrical energy. A portion of the air pressurized by the air compressor 55 passes through the valve 62.
The residue is sent to the combustor 51 via the valve 61, the pipe 46, and the adsorption/desorption group 2 via the valve 1] or the valve 13.
1 or adsorption/desorption group 22, and is separated into oxygen-enriched air and high-concentration nitrogen, which are used for gasification. FIG. 3 is a diagram showing a third embodiment. This embodiment has the same basic configuration as the embodiment shown in FIG. is established,
Adsorption/desorption group 21. , 22 can be performed in a vacuum state. Therefore, the adsorbent can be used with excellent properties, and the separation efficiency can be improved. FIG. 4, which shows the fourth embodiment, is a combination of the embodiment shown in FIG. Machine 3
3. Except for the carrier gas compressor 32, the gas and other agent pressure regulating valves 7
In this embodiment, the carrier gas compressor 32
．． Gas and other agent compressors: 33 is not installed, which simplifies the equipment, and since the operating pressure of the adsorption/desorption group can be made high, the adsorption power per volume of the adsorption/desorption group increases, and for a given gas generation capacity, In this case, the size of the adsorption/desorption group can be reduced. [Effects of the Invention] According to the present invention, the exhaust pipe of the desorption process of the PSA device is provided with a device for accommodating the gas discharged in the latter stage of the desorption process, so that high concentration nitrogen gas can be recovered and used for coal transportation or coal transportation. It can be used to pressurize coal-filled containers, and the gasifying agent, carrier gas, and coal-filled container pressurizing gas can be simultaneously produced from air and used for coal gasification, reducing the equipment necessary for gasification. It can be made extremely compact and has the effect of reducing power generation costs through coal gasification combined cycle power generation.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a first embodiment of the present invention, Fig. 2 is a system diagram showing an example in which the first embodiment is combined with a power generation plant, and Fig. 3 is a system diagram showing a third embodiment. 4 are system diagrams showing the fourth embodiment, and FIG. 5 is a diagram showing changes over time in the nitrogen concentration of exhaust gas in the desorption process. 21.22...Adsorption/desorption group, 24...Coal filling container,
26... Coal gasification furnace, 31... Compressor (air compressor), 23.32... Device for storing gas discharged in the latter half of the desorption process (carrier gas storage tank and carrier gas compressor) ).

Claims (1)

[Claims] 1. A coal gasification furnace, a coal filling container connected to the furnace and supplying coal to the furnace by air flow conveyance, and a coal filling container connected to the furnace and selectively adsorbing nitrogen over oxygen. an adsorption/desorption tower filled with an adsorbent to generate oxygen-enriched air by a pressure fluctuation adsorption method and supply the air to the furnace; and an adsorption/desorption tower connected to the adsorption/desorption tower to supply a mixed gas containing oxygen and nitrogen. In a coal gasification method using a device having a compressor that feeds the coal into the gas, high-concentration nitrogen gas discharged from the adsorption/desorption tower in the latter stage of the desorption process of the adsorption/desorption tower is used for airflow conveyance of coal and coal filling. A coal gasification method characterized by use for pressurizing a container. 2. A coal gasification furnace, a coal filling container connected to the furnace and supplying coal to the furnace by pneumatic conveyance, and a coal filling container connected to the furnace and supplying oxygen-enriched air generated by a pressure fluctuation adsorption method to the furnace. an adsorption/desorption column filled with an adsorbent that selectively adsorbs nitrogen over oxygen, and a compressor connected to the adsorption/desorption column and feeding a mixed gas containing oxygen and nitrogen to the adsorption/desorption column. A coal gasification apparatus, characterized in that a pipe for discharging exhaust gas in the desorption process of the adsorption/desorption tower is provided with a device for accommodating gas discharged in the latter half of the desorption process. 3. The device for accommodating the gas discharged in the latter half of the desorption process includes a branch pipe provided in the pipe for discharging the exhaust gas in the desorption process of the adsorption/desorption tower, a stop valve provided in the branch pipe, and the stop valve. The coal gasification apparatus according to claim 1, further comprising a tank connected to a coal gasifier. 4. The coal gasification apparatus according to claim 3, characterized in that a compressor is provided between the tank and the stop valve. 5. The coal gasification apparatus according to claim 4, characterized in that a compressor is provided in a pipe connecting the adsorption/desorption tower and the coal gasification furnace. 6. It is characterized by having a compressor connected with the suction side facing the adsorption/desorption tower to the side to which the tank is not connected of the branch pipe provided in the pipe for discharging exhaust gas in the desorption process of the adsorption/desorption tower. A coal gasification apparatus according to any one of claims 2 to 5. 7. Claims 2 to 3, characterized in that a pressure regulating valve is provided in the piping connecting the adsorption/desorption tower and the coal gasification furnace.
Coal gasification equipment as described in any of the paragraphs.