JP6246473B2 - Carbonaceous fuel gasifier - Google Patents

Description

  The present invention relates to a carbonaceous fuel gasifier, and more specifically to a carbonaceous fuel gasifier that removes a heat transfer tube bank during operation.

  Carbonaceous fuel gasifiers are used for, for example, integrated coal gasification combined cycle (IGCC). In the coal gasification combined power generation facility, it is obtained by recovering the driving power of the gas turbine by the combustible gas obtained by gasifying carbonaceous fuel such as pulverized coal (coal) with the gasifier and the exhaust heat of the gas turbine. Power is generated by the driving force of the steam turbine. The carbonaceous fuel referred to here includes biomass fuel such as agricultural products or by-products, organisms such as wood and plants, in addition to pulverized coal (coal).

  Examples of the carbonaceous fuel gasifier used in the coal gasification combined power generation facility as described above include pulverized coal, char (powder containing unburned carbon and ash in pulverized coal, as shown in FIG. A gasification unit 110 that generates a combustible gas by reacting an oxidant and the like, and a heat exchange unit 120 that communicates with the gasification unit 110 is known. The heat exchange unit 120 is provided with a plurality of heat transfer tube banks 121 to 124 that perform heat exchange with the generated gas generated in the gasification unit 110, and the combustible gas generated in the gasification unit is It is used for driving a gas turbine.

  Here, as shown in FIG. 2, each of the heat transfer tube banks 121 to 124 has the heat transfer tubes arranged in parallel in the direction of the product gas flow in the heat exchanging unit 120 by folding the heat transfer tubes a plurality of times. It is. In addition, a heat medium such as water or steam circulates in the heat transfer tubes of the heat transfer tube banks 121 to 124, and heat exchange is performed between the heat medium and the combustible gas via the heat transfer tubes. As a result, the temperature of the combustible gas decreases.

  On the other hand, each heat exchanger tube bank 121-124 has functions other than cooling of combustible gas. For example, the apparatus of Patent Document 1 is provided with four heat transfer tube banks, and each heat transfer tube bank superheats steam flowing through the heat transfer tubes to generate superheated steam used to drive a steam turbine. It functions as a superheater, an evaporator that evaporates the water circulating in the heat transfer tube, and a economizer that heats the water supplied to the evaporator.

  As described above, each of the heat transfer tube banks 121 to 124 has a function of lowering the temperature of the combustible gas, a function of supplying the heat medium exchanged with the combustible gas to other devices, and each heat transfer tube. Since the banks 121 to 124 often function in cooperation with each other as described above, it is desirable that the heat transfer tube banks 121 to 124 always perform the required functions.

  However, the combustible gas generated in the gasification furnace unit 110 and sent to the heat exchanging unit 120 includes a powdery material such as char, and this powdery material is transferred to each of the heat transfer tube banks 121 to 124. The heat exchange efficiency between the combustible gas and the heat medium deposited on the heat pipe and the heat transfer pipe decreases. And, the heat exchange efficiency is lowered, so that the function of other equipment to which the heat medium is supplied is lowered, and the temperature of the combustible gas on the downstream side of the heat exchange unit 120 becomes the design value or more downstream of the heat exchange unit. This will cause damage to the equipment on the side.

  For this reason, in order to maintain the function of each heat exchanger tube bank 121-124, the removal device is provided, and the removal of the powdery body deposited on each heat exchanger tube bank during the operation of the carbonaceous fuel gasifier is periodically performed. (For example, refer to Patent Document 2).

JP 2011-241781 A JP-A-8-189630

  However, in order to maintain the function of each heat transfer tube bank, it is possible to remove some heat transfer tube bank deposits even if the removal device is periodically operated during operation of the carbonaceous fuel gasifier. For this reason, there was a tendency that the function of the heat transfer tube bank in which deposits tend to accumulate gradually deteriorates. Moreover, there existed a tendency for the said deposition to generate | occur | produce easily in the heat exchanger tube bank arrange | positioned in the upstream among each heat exchanger tube bank.

  For this reason, the heat exchange efficiency of the heat transfer tube bank arranged on the upstream side is gradually lowered, and the flow rate of the steam is reduced. In addition, the temperature of the combustible gas flowing downstream of the heat exchanging unit rises and exceeds the design value, which may cause damage to equipment disposed on the downstream side of the heat exchanging unit. .

  This invention is made in view of such a situation, Comprising: The carbonaceous fuel gasification apparatus which can prevent or suppress the functional fall of the heat exchanger tube bank by adhesion of deposit, solidification, and growth is provided. For the purpose.

The inventors pay attention to the relationship between the temperature of the gas at the position where the heat transfer tube bank is disposed and the solidification / growth of the deposited deposit, and adopt the following means in order to solve the above problems.
That is, a carbonaceous fuel gasifier according to an aspect of the present invention is provided in the downstream of the product gas in the flow direction, and a plurality of heat transfer tube banks that exchange heat with the product gas, and removing soot apparatus for removing soot, a carbonaceous fuel gasifier having a temperature of the product gas Chi contact touch caries said plurality of heat transfer tubes bank above the glass transition point of the carbonaceous fuel The heat transfer tube bank is a high-temperature side heat transfer tube bank, and the high-temperature side heat transfer tube bank is formed so that the bank height in the product gas flow direction is lower than the bank height of other heat transfer tube banks. The high-temperature side heat transfer tube bank is formed so that the bank height is 2 m or less, the removal device has a plurality of soot-blowing tubes, and each soot-blowing tube is upstream of the corresponding heat-transfer tube bank. Placed on the side and downstream In addition, the steam is sprayed to the heat transfer tube bank to remove the debris, and the range of the steam sprayed from each of the soot blow tubes to the heat transfer tube bank has almost no solidification / growth of char. The effective removal range of the steam blown from the soot blower pipe disposed on the upstream side over the effective removal range, and the effective removal of the steam blown from the soot blow tube disposed on the downstream side The sum with the range is 2 m or more.

According to this aspect, the high temperature side heat transfer tube bank is formed so that the bank height is lower than the bank heights of the other heat transfer tube banks. For this reason, for example, when arranging the removal device immediately upstream of the high temperature side heat transfer tube bank, the distance from the removal device to the central portion or the downstream end of the heat transfer tube bank is larger than that of other heat transfer tube banks. short. Therefore, the removal fluid sprayed from the removal device easily reaches the entire heat transfer tube, and the deposits adhering to the high temperature side heat transfer tube bank can be effectively removed.
The inventors have found that solidification of deposits occurs early in an atmosphere above the glass transition point of the carbonaceous fuel, and that the solidification and growth of the deposits makes it difficult to remove with a scrubber. The above-mentioned means is adopted so that the removal fluid can easily reach the entire heat transfer tube by the dredging device.

  The said aspect WHEREIN: It is preferable that the bank height of the said high temperature side heat exchanger tube bank is formed so that it may become 2 m or less. Since other heat transfer tube banks do not come into contact with the product gas above the glass transition point, it is unlikely to cause deterioration of the heat transfer tube function due to char solidification and growth at an early stage. The functions of other heat transfer tube banks and their connected devices can be maintained without reducing the height.

  Moreover, in the said aspect, each soot blower pipe is arrange | positioned in the upstream of a corresponding heat exchanger tube bank, respectively, and sprays steam to this heat exchanger tube bank, and removes. In addition, at least one soot-blowing pipe is arranged between each heat transfer pipe bank and the adjacent heat transfer pipe bank. That is, the boundary between adjacent heat transfer tube banks is clarified by the soot tube. For this reason, a heat transfer tube bank is formed by a bundle of heat transfer tubes between adjacent soot blow tubes, and the bank height is determined by the heat transfer tube at one end of the generated gas flow direction of the heat transfer tube bank and the heat transfer tube at the other end.

According to the present invention, the removal fluid sprayed from the removal device easily reaches the entire heat transfer tube bank in contact with the product gas above the glass transition point, so that the high temperature side heat transfer tube by char solidification / growth Deterioration of bank functions can be prevented or suppressed.
On the other hand, for other heat transfer tube banks that do not come into contact with the product gas above the glass transition point, there is no need to reduce the bank height unnecessarily, so the number of removal devices can be reduced, and in terms of economy It is advantageous.

It is a longitudinal cross-sectional view of the coal gasification furnace which concerns on one Embodiment of this invention. It is a principal part enlarged view of the coal gasification furnace which shows the structure of a heat exchanger tube bank. It is a principal part enlarged view of the coal gasification furnace which shows the structure of a removal apparatus. It is operation | movement explanatory drawing of a removal apparatus. It is operation | movement explanatory drawing of a removal apparatus. It is a figure which shows the effective removal range of a high temperature side heat exchanger tube bank. It is a longitudinal cross-sectional view of the conventional coal gasifier.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view showing an example of a coal gasification furnace as a carbonaceous fuel gasification furnace to which the present invention can be applied. This coal gasification furnace includes a gasification unit 10 that generates flammable gas by reacting pulverized coal, char (powder containing unburned carbon and ash in pulverized coal), an oxidizer, and the like, and gasification The heat exchanger 20 is communicated with the unit 10 at the upper end, and the generated gas flows from the top to the bottom.

  In the heat exchanging unit 20, a plurality of heat transfer tube banks 21 to 24 that perform heat exchange with the generated gas generated in the gasification unit 10, and removal for maintaining the functions of the heat transfer tube banks 21 to 24. The apparatus 30 is provided, and the generated gas whose temperature has decreased in the heat transfer tube banks 21 to 24 is supplied from the lower end of the heat exchange unit 20 to a gas turbine or the like.

  The gasification unit 10 has a general configuration, and can be configured as disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 2012-172131 and 2011-68812.

  The generated gas passes through the gasification furnace outlet 10 a that is the upper part of the gasification furnace section 10 and flows into the heat exchange section 20. In this embodiment, the temperature of the gasifier outlet 10a is about 1000 ° C to 1200 ° C.

  As shown in FIG. 2, each of the heat transfer tube banks 21 to 24 is configured such that the heat transfer tubes are installed in the vertical direction, which is the generated gas flow direction in the heat exchanging unit 20, by folding the heat transfer tubes a plurality of times. is there. Further, in each of the heat transfer tube banks 21 to 24 in the present embodiment, a plurality of the heat transfer tubes folded and juxtaposed are juxtaposed in the horizontal direction (the depth direction in the drawing in FIG. 2). For this reason, each heat exchanger tube bank 21-24 has the structure by which the heat exchanger tube was arranged in parallel by the up-down direction and the horizontal direction. In this embodiment, as shown in FIG. 3, the diameter D of each heat transfer tube is about 25 to 60 mm, and the arrangement distance L1 in the vertical direction between adjacent heat transfer tubes is about 2 to 5 times the diameter D. Further, the horizontal arrangement distance L2 between the adjacent heat transfer tubes is about 2 to 5 times the diameter D. Each of the heat transfer tube banks 21 to 24 is connected with an inlet pipe 21a, 22a, 23a, 24a and an outlet pipe 21b, 22b, 23b, 24b, respectively, from the inlet pipe 21a, 22a, 23a, 24a such as water, steam, etc. The heat medium flows into each of the heat transfer tube banks 21 to 24, heat exchange is performed between the heat medium and the generated gas via the heat transfer tubes, and the heat medium subjected to the heat exchange is the outlet tubes 21b, 22b, and 23b. , 24b.

  Each of the heat transfer tube banks 21 to 24 superheats the steam flowing through the heat transfer tube to generate superheated steam, the evaporator that vaporizes the water flowing through the heat transfer tube, and the evaporator It functions as a economizer that heats the water to be supplied. Moreover, each heat exchanger tube bank 21-24 is connected to various apparatuses, such as a steam drum and a steam turbine, via each inlet pipe 21a, 22a, 23a, 24a and outlet pipe 21b, 22b, 23b, 24b.

  As shown in FIG. 2, each of the heat transfer tube banks 21 to 24 has a bank height h in the product gas flow direction, that is, in the vertical direction in this embodiment. The bank height h of the heat transfer tube bank is the heat transfer tube constituting the central axis and the other end (lower end in the present embodiment) of one end (upper end in the present embodiment) of the heat transfer tube bank in the product gas flow direction. It is the distance from the center axis. In this embodiment, the bank height of the heat transfer tube banks 21 and 22 is 2 m or less, and the bank height of the heat transfer tube banks 23 and 24 is 3 to 4 m. Similarly, the width of the heat transfer tube banks 21 to 24 in the width direction (depth direction in FIG. 2) is about 2 to 4 m, and the heat transfer tube extending direction of the heat transfer tube banks 21 to 24 (left and right direction in FIG. 2). The bank width is about 2 to 4 m.

  In the heat exchange unit 20, the generated gas flows from upstream to downstream, and in the process of flowing, the generated gas contacts the heat transfer tube banks 21 to 24 and performs heat exchange. The temperature of the product gas decreases from the bottom to the bottom. In the present embodiment, as shown in FIG. 1, the heat transfer tube banks 21 and 22 are arranged in a range AR1 in which the generated gas is equal to or higher than the glass transition point of the carbonaceous fuel, and contact with the generated gas equal to or higher than the glass transition point. Heat exchange.

  On the other hand, as shown in FIGS. 3 to 5, the heat exchanging unit 20 is provided with a hair removal device 30 in order to maintain the functions of the heat transfer tube banks 21 to 24. The removal device 30 is arranged on the upstream side and the downstream side in the product gas flow direction with respect to the heat transfer tube banks 21 to 24.

  In this embodiment, the hair removal device 30 is a so-called suit blower, and for example, those disclosed in Japanese Patent Application Laid-Open Nos. 1-223411 and 2010-1117067 can be used. In the present embodiment, the dehuller 30 includes a soot blower pipe 31 provided with nozzle holes 31a and 31b at the tip, and a pipe support that supports the soot blow pipe 31 so as to be movable in the axial direction and rotate around the axis. A mechanism 32, an axial position sensor 33 for detecting the axial position of the soot blow pipe 31, a rotational direction position sensor 34 for detecting the rotational position of the soot blow pipe 31 around the axis, the soot blow pipe 31 and the steam supply A steam supply pipe 35 that is connected to a device (not shown) and supplies steam into the soot blow pipe 31; an on-off valve 36 that opens and closes the steam supply pipe 35; a pipe support mechanism 32; an axial position sensor 33; And a control device 37 connected to the position sensor 34 and the on-off valve 36. In addition, the nozzle hole 31b is not provided in the uppermost removal pipe 31 of FIG. 1, and the nozzle hole 31a is not provided in the lowermost removal pipe 31 of FIG. Further, the soot blow pipe 31 is supported by the pipe support mechanism 32 in a state where the tip side is inserted into the hole 20b provided in the wall 20a of the heat exchange section 20, and enters the heat exchange section 20 by the pipe support mechanism 32. It is supposed to be.

  Each removal device 30 removes each heat transfer tube bank 21-24 every predetermined time based on a program stored in the control device 37, for example. The operations of the tube support mechanism 32 and the on-off valve 36 controlled by the control device 37 during removal will be briefly described below.

  When the predetermined time has elapsed, the tube support mechanism 32 starts to move the soot blower tube 31 toward the center of the heat exchange unit 20. Subsequently, before the nozzle holes 31a and 31b of the soot blow pipe 31 reach the upper or lower side of the heat transfer pipe as viewed from the soot blow pipe 31, the on-off valve 36 is released so that the soot blow pipe 31 has the nozzle holes 31a and 31b. The pipe support mechanism 32 starts to reciprocate within a predetermined rotation range of the soot blow pipe 31 as well. Although the rotation range is not particularly limited, as an example, as shown in FIG. 5, steam sprayed from the nozzle holes 31 a and 31 b around the position where the nozzle hole 31 a faces directly below and the nozzle hole 31 b faces directly above. Can be set as a rotation range in which the heat transfer tube is sprayed evenly.

  Next, when the nozzle holes 31a and 31b of the soot blow pipe 31 pass above or below the heat transfer pipe farthest from the soot blow pipe 31, the pipe support mechanism 32 is maintained while maintaining the above-described rotation operation and the above-described injection. The soot blower tube 31 starts to move toward the outside of the heat exchange unit 20. Subsequently, when the nozzle holes 31a and 31b of the soot blow pipe 31 pass above or below the foremost heat transfer pipe when viewed from the soot blow pipe 31, the pipe support mechanism 32 and the on-off valve 36 perform the above-described rotation operation and the above-described injection. When the soot blowing pipe 31 is moved to a predetermined standby position, the pipe support mechanism 32 stops the axial movement of the soot blowing pipe 31. When this series of soot blowing operations is performed, the powders such as char attached to or accumulated on the heat transfer tubes are removed by the steam sprayed from the nozzle holes 31a and 31b of the soot blowing tube 31. In this embodiment, the nozzle hole 31a injects steam downward and the nozzle hole 31b injects steam upward. However, only the nozzle hole 31a is provided in the soot blowing pipe 31, and the rotation range of the soot blowing pipe 31 is shown. It is possible to inject steam upward and downward through the nozzle hole 31a.

  The coal gasification furnace configured as described above is operated so that the generated gas generated in the gasification unit 10 passes through the heat transfer tube banks 21 to 24 and is supplied to a gas turbine or the like. In the state where this operation is performed, the heat transfer tube banks 21 to 24 are removed every predetermined time as described above.

  Here, in the present embodiment, the bank heights of the high-temperature side heat transfer tube banks 21 and 22 that contact the product gas above the glass transition point of the carbonaceous fuel and exchange heat are the same as the bank heights of the other heat transfer tube banks 23 and 24. It is formed to be lower than this. This is because the inventors focused on the relationship between the gas temperature at the position where the heat transfer tube bank is placed and the solidification / growth of char on the heat transfer tube, and devised to reduce or eliminate char solidification / growth. It is a result. Specifically, by repeatedly inspecting the inventor's close gasification furnace, particularly the heat transfer tube bank, the removal effect by the removal device is obtained in the region where the product gas temperature is lower than the glass transition point. As a result, there was almost no solidification or growth of the deposited char on the heat transfer pipe surface. On the other hand, in the region where the product gas temperature is equal to or higher than the glass transition point, char solidification / growth was confirmed at the center of the heat transfer tube bank. That is, the removal effect of the removal device 30 varies greatly depending on whether the generated gas temperature is lower or higher than the glass transition point, and it is possible to prevent the char deposited on the surface of the heat transfer pipe from solidifying and growing. It was discovered that there exists an environmental condition branch temperature point. On the other hand, when the bank height is high, the distance from the nozzle hole 31a of the soot blower 31 of the degassing device 30 to the center of the heat transfer tube bank becomes long, and the heat transfer tube bank is generated by the steam injected from the nozzle holes 31a and 31b. We also paid attention to the fact that deposits (mainly powders) adhering to the central part of the material cannot be removed efficiently. Specifically, as shown in FIG. 6, in the region where the product gas temperature is not lower than the glass transition point, the surface of the heat transfer pipe is not more than 1 m from the upper end of the heat transfer tube bank and within 1 m from the lower end of the bank. Char solidification / growth is almost absent, whereas char solidification / growth was confirmed in the range of 1 m or more from the upper end of the heat transfer tube bank and in the range of 1 m or more from the lower end of the bank. Therefore, a study was made to reduce the bank height of the high-temperature side heat transfer tube banks 21 and 22 that contact the product gas above the glass transition point and exchange heat, and the bank height of the high-temperature side heat transfer tube banks 21 and 22 is 2 m or less. If so, the removal device 30 makes it easy for the steam to reach the entire heat transfer tube banks 21 and 22, and it is possible to prevent or suppress the deterioration of the function of the high temperature side heat transfer tube bank due to the solidification and growth of char. It was.

  As described above, according to the present embodiment, the bank heights of the high-temperature side heat transfer tube banks 21 and 22 that contact the product gas above the glass transition point and exchange heat are the same as the banks of the other heat transfer tube banks 23 and 24. Since it is formed so as to be lower than the height, the distance from the nozzle holes 31a, 31b of the soot blower tube 31 of the degassing device 30 to the center portion of the heat transfer tube bank is smaller than that of the other heat transfer tube banks 23, 24. short. Therefore, the steam sprayed from the nozzle holes 31a, 31b of the soot blower tube 31 is easy to spread over the entire heat transfer tube, and char deposits adhering to the high temperature side heat transfer tube banks 21, 22 can be effectively removed, It is possible to prevent or suppress the functional deterioration of the high-temperature side heat transfer tube bank due to the solidification / growth of char.

  On the other hand, the other heat transfer tube banks 23 and 24 that do not come into contact with the product gas above the glass transition point do not need to reduce the height of the bank unnecessarily, so the number of the removal devices 30 can be reduced. It is advantageous in terms of sex.

  Moreover, in this embodiment, it forms so that the bank height of the other heat exchanger tube banks 23 and 24 which do not contact the product gas more than a glass transition point may become higher than 2 m. Since it does not come into contact with the product gas at a temperature higher than the glass transition point, it is unlikely to cause a functional deterioration due to char solidification / growth. Therefore, other heat transfer tube banks 23, 24 and the function of the connected device can be maintained.

  It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and can be appropriately modified or improved without departing from the gist of the present invention. The form is also included in the scope of the right of the present invention.

  For example, in the above-described embodiment, the above-described spraying is performed by spraying the above from the nozzles 31a and 31b of the soot blowing pipe 31, but other decontamination fluid and granular materials are sprayed toward the heat transfer tube bank. Even in the case of removal, the distance from the injection port to the center of the high-temperature side heat transfer tube bank can be shortened by configuring the bank height of the high-temperature side heat transfer tube bank as described above. Therefore, the same effect as above can be expected.

DESCRIPTION OF SYMBOLS 10 Gasification part 20 Heat exchange part 21 Heat transfer tube bank 22 Heat transfer tube bank 23 Heat transfer tube bank 24 Heat transfer tube bank

Claims (1)

A gasification furnace section for reacting a carbonaceous fuel and an oxidant, and a plurality of heat transfer tube banks arranged in parallel in the flow direction of the product gas generated in the gasification furnace section and in contact with the product gas to exchange heat A carbonaceous fuel gasifier comprising: a heat removal tube bank for removing heat from the heat transfer tube bank;
Said plurality of said heat transfer tube bank is higher than the glass transition point temperature is the carbonaceous fuel of the product gas Chi contact touch sac heat transfer tube bank, is the hot side heat transfer tube bank,
The high temperature side heat transfer tube bank is formed such that the bank height in the product gas flow direction is lower than the bank height of other heat transfer tube banks,
The high temperature side heat transfer tube bank is formed so that the bank height is 2 m or less,
The depigmenting device has a plurality of soot blow tubes,
Each of the soot blow pipes is disposed on the upstream side and the downstream side of the corresponding heat transfer pipe bank, and performs steam removal by injecting steam or the like into the heat transfer pipe bank,
The range of the steam sprayed from each soot tube to the heat transfer tube bank spans an effective removal range in which there is almost no solidification / growth of char,
The sum of the effective removal range of the steam blown from the soot blowing pipe arranged on the upstream side and the effective removal range of the steam blown from the soot blowing pipe arranged on the downstream side is 2 m or more A carbonaceous fuel gasifier characterized by the above.

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