JP5753059B2 - Fuel gas purification system and product gas production system - Google Patents

Description

  The present invention relates to a fuel gas purification system and a product gas production system including a fuel gas purification unit that purifies a fuel gas containing impurities obtained by anaerobic fermentation or thermal decomposition of an organic substance.

When fuel gas obtained by anaerobic methane fermentation or pyrolysis of sewage and industrial wastewater is used in gas consuming equipment such as fuel cells, RX gas generation facilities, gas engine generators, etc., or received in city gas conduits When used as city gas, it is necessary to reduce the concentration of impurities in the fuel gas. Examples of impurities include carbon dioxide, nitrogen and siloxane. For carbon dioxide, it is desirable to make it 0.5% or less in order to use fuel cells, RX gas generating facilities and the like without any trouble, and siloxane is 0.1 mg as an example for using gas engines and the like without any trouble. / M ³ N or less is desirable. Furthermore, the nitrogen concentration is suitably 1% or less when used as a raw material for fuel cells and hydrogen generators, and when it is received in a city gas conduit, the pressure of city gas is taken into consideration. The dew point of the fuel gas is suitably -50 ° C or lower.

As a fuel gas refining system capable of removing impurities contained in such fuel gas, for example, Patent Document 1 discloses that impurities contained in fuel gas are liquidized by cooling the fuel gas with liquefied natural gas. A fuel gas refining system including a fuel gas refining unit that is separated by solidification and solidification is disclosed.
The fuel gas purification unit is configured as a heat exchanger provided with a number of heat transfer tubes that perform heat exchange between the fuel gas and liquefied natural gas. This heat exchanger employs a configuration in which a large number of heat transfer tubes have natural gas flow paths through which liquefied natural gas flows, and a large number of heat transfer tubes have fuel gas flow paths through which fuel gas flows. That is, an integral space outside the many heat transfer tubes in the heat exchanger is a fuel gas flow path. Then, the impurities in the fuel gas are separated from the fuel gas by condensing in a state where they adhere to the outside of the heat transfer tube as a solid or liquid material due to the cold heat of the liquefied natural gas flowing inside the heat transfer tube.

  Also, this heat transfer tube has fins on the outer periphery and is made of an aluminum alloy with high thermal conductivity, so the cold heat of liquefied natural gas flowing inside the heat transfer tube is fixed to the outside of the heat transfer tube. Heat is transferred to the fins, and impurities in the fuel gas flowing outside the heat transfer tubes are liquefied and solidified by the cold heat of the liquefied natural gas, and adhere to the fins provided on the outer periphery of the heat transfer tubes. Thus, the fuel gas can be purified.

JP 2011-6617 A

  However, fuel gas such as biogas obtained by anaerobic fermentation or thermal decomposition of organic substances contains carbon dioxide as an impurity in a large amount of 10% to 45%, and this is liquefied natural gas. If the fuel gas has a flow rate distribution in the heat exchanger, a large amount of the solid matter locally accumulates in the part where the flow rate of the fuel gas is large, and the heat exchanger is blocked. It will be in the state.

  In the fuel gas purification unit disclosed in Patent Document 1, an integral space outside a large number of heat transfer tubes in the heat exchanger is used as a fuel gas flow channel, and the fuel gas flow channel direction along the large number of heat transfer tubes is used. Fuel gas is introduced from the orthogonal direction. For this reason, in the fuel gas flow path, the flow of the fuel gas that contacts the fuel gas evenly along the outer periphery of the many heat transfer tubes is not formed, and a large amount of solid matter is locally produced in the portion where the flow rate of the fuel gas is large. There is a problem that the heat exchanger is clogged due to accumulation.

  In addition, since the heat transfer tube disclosed in Patent Document 1 has fins, when trying to maintain the impurity removal performance at a certain level, a large area of the fins is formed and the outer diameter and length are increased. Since it is necessary to accommodate the heat transfer tube in the fuel gas purification section, a large fuel gas purification section is required in the circumferential direction and the length direction.

  The present invention has been made in view of such circumstances, and an object thereof is to purify a fuel gas that can maintain the performance of compacting the apparatus and preventing the partial condensation of impurities to separate the impurities. It is to provide a system and a product gas production system.

In order to achieve the above object, a fuel gas purification apparatus according to the present invention comprises:
A fuel gas purification system comprising a fuel gas purification unit for purifying a fuel gas containing impurities obtained by anaerobic fermentation or pyrolysis of organic matter, the characteristic configuration of which is
The fuel gas purification unit includes a plurality of the heat transfer tubes having a fuel gas flow channel through which the fuel gas flows inside the heat transfer tube and a natural gas flow channel through which liquefied natural gas flows outside the heat transfer tube. A heat exchanging part that exchanges heat between the fuel gas and the liquefied natural gas;
A fuel gas introduction section for introducing the fuel gas into the fuel gas flow path; and a purified gas deriving section for deriving the purified gas from which the impurities are removed from the fuel gas from the fuel gas flow path;
A natural gas introduction pipe for introducing the liquefied natural gas into the natural gas flow path, and a natural gas discharge pipe from which the natural gas after the heat exchange is led out from the natural gas flow path,
The fuel gas introduction part and the heat exchange part are partitioned by a support plate that penetrates and supports the natural gas outlet pipe and the plurality of heat transfer pipes, and the fuel gas introduction part passes through the heat exchange part In addition, a plurality of heat transfer tube end openings of the heat transfer tubes penetrating the support plate are disposed, and the natural gas passes through the fuel gas introduction portion and penetrates the support plate in the heat exchange portion. An outlet pipe end opening of the outlet pipe is disposed,
In the fuel gas introduction unit, a rectifying member that uniformly adjusts the flow rate of the fuel gas in a direction orthogonal to the flow direction of the fuel gas by passing the fuel gas is in a non-contact state with the natural gas outlet pipe. And provided upstream of the heat transfer tube end openings of the plurality of heat transfer tubes,
The impurities contained in the fuel gas are separated in a state where the impurities are attached to the inside of the heat transfer tube as a liquid or solid matter by the cold heat of the liquefied natural gas in the heat exchange unit,
An impurity recovery mechanism is provided for recovering the adhered impurities separately from the purified gas.

According to the above characteristic configuration, the inside of the heat transfer tube provided in the heat exchange section is a fuel gas flow path through which fuel gas flows, and the outside of the heat transfer pipe in the heat exchange section is a natural gas flow path through which liquefied natural gas flows. The fuel gas is introduced into the fuel gas passage from the fuel gas introduction section, and the liquefied natural gas is introduced into the natural gas passage through the natural gas introduction pipe, and the fuel gas is exchanged with the fuel gas through the heat transfer pipe in the heat exchange section. Heat can be exchanged with liquefied natural gas. Compared with the technique disclosed in Patent Document 1, this configuration is such that the type of fluid flowing inside and outside the heat transfer tube is reversed.
Then, the natural gas heated and vaporized by heat exchange can be led out from the natural gas flow path to the natural gas outlet pipe, and the purified gas cooled by heat exchange and condensed by separating impurities in the fuel gas Can be led out from the fuel gas flow path to the purified gas outlet.

  Further, the fuel gas introduction part is provided with heat transfer pipe end openings of a plurality of heat transfer pipes that pass through the heat exchange part and penetrate the support plate, so that the fuel gas supplied to the fuel gas introduction part can be supplied. It can introduce | transduce into the fuel gas flow path inside a heat exchanger tube from the heat exchanger tube edge part opening of a heat exchanger tube, and can let a heat exchange part pass. Therefore, it is not mixed with the liquefied natural gas flowing through the natural gas flow path outside the heat transfer tube in the heat exchange section. And since the fuel gas introduction part and the heat exchange part are partitioned off by a support plate that supports the heat transfer tube, the heat transfer tube is fixedly supported by the support plate and flows through the fuel gas and the heat exchange part that flows through the gas introduction part. It is possible to maintain a state in which the liquefied natural gas is not mixed. Furthermore, since the heat exchange section is provided with an outlet pipe end opening of the natural gas outlet pipe that passes through the fuel gas introduction section and penetrates the support plate, the natural gas heat-exchanged in the heat exchange section is supplied to the fuel exchange section. The state in which the gas and the liquefied natural gas are not mixed can be maintained, and the fuel gas introduction unit can be passed from the heat exchange unit to the outside of the fuel gas purification unit.

Further, in the fuel gas introduction portion, the flow rate of the fuel gas is uniformly adjusted in the direction orthogonal to the flow direction by the rectifying member provided upstream of the heat transfer tube end openings of the plurality of heat transfer tubes. The flow rate of the fuel gas flowing into the heat transfer tube end openings of the plurality of heat transfer tubes provided in the section can be made uniform. As a result, the thickness of the solid or liquid material adhering to the inside of the heat transfer tube is uniformly formed inside each heat transfer tube, thus preventing partial condensation of impurities and removing impurities efficiently for a long time. can do. Further, since the impurities are uniformly formed inside the heat transfer tube, the diameter of the heat transfer tube can be reduced. In this case, it is possible to make the heat exchange part compact while maintaining the performance of separating impurities.
Since the rectifying member is not in contact with the natural gas outlet pipe, the cold heat of the low-temperature natural gas flowing through the natural gas outlet pipe is difficult to be transmitted to the rectifying member, and the fuel gas impurities are separated and adhered. Without this, it is possible to prevent the gas permeability from being lost due to the condensation of impurities in the rectifying member.

  Further, since the impurities contained in the fuel gas are separated in a state where they are adhered to the inside of the heat transfer tube as a liquid or solid matter by the cold heat of the liquefied natural gas in the heat exchanging section, in general, −140 ° C. to −160 ° C. Due to the liquefied natural gas of which the temperature is extremely low, impurities such as carbon dioxide, siloxane, moisture, oil, and hydrocarbons other than methane, which have a liquefaction point or a freezing point in its temperature range, are solid or liquid. The fuel gas can be purified by separation as follows. On the other hand, liquefied natural gas can also be used as a heat source for vaporizing liquefied natural gas by using the sensible heat of fuel gas and the latent heat of condensation of impurities when exchanging heat with fuel gas. Gas can be used effectively as gaseous fuel.

  In addition, since an impurity recovery mechanism that recovers the attached impurities separately from the purified gas is provided, the impurities that adhere to the inside of the heat transfer tube are deposited and the fuel gas flow path is blocked before the fuel gas flow path is blocked. By collecting the impurities adhering to the inside of the heat pipe, it is possible to prevent a decrease in heat transfer efficiency due to a deposited layer of impurities and a decrease in heat exchange efficiency due to a reduction in the cross-sectional area of the fuel gas flow path, and an impurity removal rate is reduced. The fuel gas can be continuously refined while maintaining a high level.

  A further characteristic configuration of the fuel gas purification apparatus according to the present invention is that the rectifying member is formed of a laminate of a porous plate, a nonwoven fabric, or a net-like woven fabric formed of a material having heat insulating properties and gas permeability. is there.

  According to the above characteristic configuration, the flow straightening member is made of a porous plate, a nonwoven fabric, or a net-like woven fabric, and the flow of the fuel gas in the fuel gas inlet is uniformly adjusted in a direction perpendicular to the flow direction with an easy configuration. The flow rate of the gas fuel flowing into the plurality of heat transfer tubes can be made uniform. And since the material is made of a heat insulating material, the cold heat of the liquefied natural gas is not easily transmitted to the rectifying member through which the fuel gas passes, and impurities are condensed in the rectifying member and the gas permeability of the rectifying member is lost. Can be prevented.

  The fuel gas refining device according to the present invention is further characterized in that, in the fuel gas introduction portion, the heat transfer tube end openings of the plurality of heat transfer tubes into which the fuel gas is introduced pass through the rectifying member. In addition to being uniformly distributed in the direction perpendicular to the gas flow direction, the distance from the rectifying member to the heat transfer tube end openings of the plurality of heat transfer tubes is the same.

  According to the above characteristic configuration, the heat transfer tube end openings of the plurality of heat transfer tubes are evenly distributed and arranged in the direction orthogonal to the fuel gas flow direction, so that the fuel gas is provided by the rectifying member provided on the upstream side. The fuel gas can be made to flow evenly into the heat transfer tube end openings of the plurality of heat transfer tubes. In addition, since the distance from the rectifying member to the heat transfer tube end openings of the plurality of heat transfer tubes is a constant distance, the flow rate of the fuel gas flowing into the heat transfer tube end openings of the plurality of heat transfer tubes is reduced. It can be made more uniform.

  A further characteristic configuration of the fuel gas purification apparatus according to the present invention is that the impurity recovery mechanism supplies a regeneration gas having a temperature at which the impurities attached inside the heat transfer tube vaporize the impurities to the heat transfer tube. A regeneration gas circulation passage for supplying the regeneration gas that has passed through the heat transfer tube to the heat transfer tube again, and an impurity mixed gas that is vaporized and mixed with the regeneration gas from the fuel gas purification unit to the outside. And an impurity mixed gas discharge passage for discharging.

  According to the above characteristic configuration, the regeneration gas at a temperature that vaporizes impurities in the solid or liquid state attached to the heat transfer tube is supplied to the heat transfer tube, and further circulated, so that the heat transfer tube can be circulated. It is possible to vaporize and remove the solid matter or liquid matter that is the deposited impurity. Thereby, the purification function of the heat exchanger can be recovered. Further, the impurity mixed gas obtained by vaporizing impurities and mixed with the regeneration gas can be discharged to the outside from the fuel gas purification unit.

  A further characteristic configuration of the fuel gas purification apparatus according to the present invention includes a purified gas temperature measuring unit that measures the temperature of the purified gas, and the temperature of the purified gas measured by the purified gas temperature measuring unit is preset. A fuel gas flow rate adjustment unit that adjusts the flow rate of the fuel gas introduced into the fuel gas purification unit, or a natural gas flow rate adjustment that adjusts the flow rate of the liquefied natural gas so as to be equal to or lower than a predetermined temperature. It is in the point provided with at least any one of a part.

  According to the above characteristic configuration, when the impurities are condensed and removed by heat exchange, the temperature of the purified gas rises as the amount of heat transferred in the heat exchange section increases. Here, in consideration of the fact that the composition of the fuel gas and the composition of the liquefied natural gas are stable, such a rise in temperature is preliminarily planned for the refined amount of the fuel gas and the liquefied natural gas as a cold heat source. This means that the balance with the amount of the gas is lost and the degree of purification (composition) of the recovered purified gas is changed. Therefore, the temperature of the fuel gas processed in the fuel gas purification unit is measured, and at least one of the flow rate of the fuel gas processed in the fuel gas purification unit and the flow rate of the liquefied natural gas is measured so that the temperature is below a certain level. By adjusting, it can manage so that the density | concentration of the specific impurity in fuel gas may not rise more than predetermined. For this purpose, it is preferable to grasp in advance the relationship between the temperature of the fuel gas and the concentration of a specific impurity in the fuel gas. As a preferable temperature condition, for example, when processing a fuel gas at an atmospheric pressure level, and taking the concentration of carbon dioxide as an example, in order to make the concentration of carbon dioxide 1% or less, it is maintained at −125 ° C. or less, To make it 0.5% or less, keep it at -130 ° C or less.

  The product gas production system according to the present invention has a characteristic configuration in which heat exchange between the fuel gas and the purified gas obtained by separating the impurities from the fuel gas obtained from the fuel gas purification system is performed. A gas mixing and adjusting system for obtaining a product gas by mixing with the natural gas after the heat exchange is provided on the downstream side of the fuel gas purification system.

According to the above characteristic configuration, the purified gas obtained by removing the impurity components from the fuel gas derived from the organic matter and the vaporized natural gas are obtained in the same process, and these gases are further mixed and the amount of heat is adjusted. A product gas having a desired property can be easily obtained.
In addition, the amount of heat of the refined gas can be brought close to the amount of heat of natural gas, so that it is possible to use the natural gas consumer device as it is, or other fuel added to adjust the amount of heat so that it can be used as it is. (For example, propane and butane) can be used in a reduced amount. Further, since the concentration of impurities in the natural gas is low, the effect that the impurity concentration of the product gas is smaller than that of the purified gas can be obtained.

It is a block diagram of a fuel gas purification system. It is a block diagram of the fuel gas refinement | purification part which refine | purifies fuel gas. It is a figure which shows the arrangement | sequence state of the heat exchanger tube in a gas introduction part support plate. It is a figure which shows the arrangement | sequence state of the through-hole in a baffle member. It is a block diagram which shows embodiment of the gas mixing adjustment system with which the fuel gas purification system which concerns on FIG. 1 is provided in the downstream. It is a figure which shows the flow of each gas at the time of impurity separation in a fuel gas purification system. It is a figure which shows the flow of each gas at the time of impurity collection | recovery in a fuel gas purification system.

The product gas production system introduced in the present application includes a gas mixing adjustment system 2 shown in FIG. 5 on the downstream side of the fuel gas purification system 1 shown in FIG.
The fuel gas purification system 1 shown in FIG. 1 is a system that purifies organic matter-derived fuel gas BG1 (corresponding to fuel gas) using the cold heat of the liquefied natural gas NG1, and this fuel gas purification system 1 is By operating, purified gas BG2 from which impurities are removed can be obtained, and vaporized natural gas NG2 that has been warmed and vaporized by donating cold for removing impurities can be obtained.
In the gas mixing adjustment system 2 shown in FIG. 5, the purified gas BG2 and the vaporized natural gas NG2 are received from the fuel gas purification system 1 and mixed, and the LPG calorific value adjustment device 710 adds LPG. By controlling the amount, it is possible to obtain a product gas GS whose calorie is within a predetermined calorie range.

Hereinafter, the fuel gas purification system 1 and the gas mixing adjustment system 2 will be described in this order.
[Configuration of fuel gas purification system]
FIG. 1 is a configuration diagram of a fuel gas purification system 1 according to the present invention. FIG. 2 is a diagram of a gas purification unit 10 (corresponding to a fuel gas purification unit) that purifies the fuel gas BG1 in the fuel gas purification system 1. It is a block diagram.
As shown in FIGS. 1 and 2, a fuel gas purification system 1 according to the present invention includes a gas purification unit 10 for purifying a fuel gas BG1 containing impurities obtained by anaerobic fermentation or thermal decomposition of organic matter. The gas purification unit 10 includes a plurality of fuel gas passages 130 through which the fuel gas BG1 flows inside the heat transfer tube 11 and a natural gas passage 230 through which the liquefied natural gas NG1 flows outside the heat transfer tube 11. The heat exchanger tube 12 is provided, and a heat exchanging portion 12 for exchanging heat between the fuel gas BG1 and the liquefied natural gas NG1 is provided.
Here, the heat exchanging unit 12 condenses or solidifies the impurities in the fuel gas BG1 by the cold heat of the liquefied natural gas NG1, and the inside of the heat transfer tube 11 that is the fuel gas flow path 130 as a liquid or solid material. It has the structure which can be isolate | separated in the state made to adhere to. Furthermore, the fuel gas purification system 1 according to the present invention according to the present application is provided with an impurity recovery mechanism 30 that recovers the adhered impurities separately from the purified gas BG2 (FIG. 1).

[Functional structure related to impurity treatment]
As shown in FIG. 1, a fuel gas system and a natural gas system are connected to each gas purification unit 10.
A fuel gas supply pipe 120 is connected to the upstream side of the gas purification unit 10 in the fuel gas system, and the fuel gas supply pipe 120 receives fuel gas BG1 from a fuel gas tank (not shown) into the fuel gas supply pipe 120. A gas supply path on-off valve VB, a humidifier 100 for bubbling the fuel gas BG1 with water, a flow rate adjusting valve V100 for adjusting the flow rate of the fuel gas BG1 to the humidifier 100, and a flow rate for measuring the flow rate of the fuel gas BG1 A meter FM110, a fuel gas flow rate control valve V110 that adjusts the flow rate of the fuel gas BG1, and a dehumidifier 105 that removes moisture in the fuel gas BG1 are provided.
On the other hand, a purified gas discharge pipe 170 is connected to the downstream side of the gas purification unit 10, and a heating device 160 is provided in the purified gas discharge pipe 170. The fuel gas BG1 before purification flows upstream from the gas purification unit 10, and the purified gas BG2 which is purified fuel gas flows downstream.

  On the other hand, a natural gas supply pipe 220 is connected to the upstream side of the gas purification unit 10 in the natural gas system, and the natural gas supply pipe 220 is provided with a liquefied natural gas tank 201, from which the liquefied natural gas tank 201 is The liquefied natural gas NG1 is configured to be introduced into the gas purification unit 10 via the gas introduction valve V210. On the other hand, a natural gas discharge pipe 270 is connected to the downstream side of the gas purification unit 10, and the flow rate measured by the hot water vaporizer 260, the flow meter FM 260 and the flow meter FM 260 is connected to the natural gas discharge pipe 270. Accordingly, a vaporized natural gas flow control valve V270 that opens and closes the flow path to adjust the flow rate is provided. Further, a part of the liquefied natural gas NG1 flowing out from the liquefied natural gas tank 201 is vaporized in the gas purification unit 10 to become vaporized natural gas NG2, and in the hot water vaporizer 260, it becomes completely vaporized natural gas NG2. In the natural gas discharge pipe 270 from the gas purification unit 10 to the hot water vaporizer 260, natural gas NG1 and NG2 in a gas-liquid mixed state circulate.

  As shown in FIGS. 1 and 2, the gas purification unit 10 includes a fuel gas introduction unit 110 that introduces a fuel gas BG1 before purification into a fuel gas channel 130 that is an inner channel of the heat transfer tube 11, and a fuel gas. A purified gas derivation unit 150 from which purified gas BG2 from which impurities have been removed from BG1 is derived from the fuel gas passage 130, a natural gas introduction pipe 240 that introduces the liquefied natural gas NG1 into the natural gas passage 230, and a heat exchange unit 12 and a natural gas outlet pipe 250 for leading out the natural gas NG1 and NG2 in a gas-liquid mixed state after heat exchange from the natural gas flow path 230. Therefore, the fuel gas BG1 and the liquefied natural gas NG1 exchange heat in an indirect form via the heat transfer tube 11. Further, as shown in FIG. 1, a fuel gas introduction unit 110 and a fuel gas supply pipe 120, and a purified gas outlet unit 150 and a purified gas discharge pipe 170 are connected, and a natural gas introduction pipe 240 and a natural gas supply pipe are connected. 220, and the natural gas outlet pipe 250 and the natural gas discharge pipe 270 are connected.

[Configuration related to impurity recovery]
As shown in FIG. 1, the gas purification unit 10 includes a fuel gas BG1 (corresponding to a regeneration gas) at a temperature at which the impurities attached to the inside of the heat transfer tube 11 as the fuel gas flow path 130 are vaporized as the impurity recovery mechanism 30. ) To the heat transfer tube 11 (corresponding to the regeneration gas supply channel) and a fuel gas circulation channel 320 (regeneration gas) for supplying the fuel gas BG1 that has passed through the heat transfer tube 11 to the heat transfer tube 11 again. And an impurity mixed gas discharge flow channel 350 for discharging the impurity mixed gas mixed with the fuel gas BG1 from the gas purification unit 10 to the outside. Here, the fuel gas circulation flow path 320 allows the fuel gas BG1 for impurity recovery derived from the heat transfer pipe 11 in the gas purification unit 10 to be derived from the purified gas deriving unit 150 and heated to introduce the fuel gas again. It is provided to be introduced into the section 110.

  Then, as shown in FIG. 1, the fuel gas BG1 used for collecting the impurities is heated by using the hot water generated by the hot water boiler 303 that uses the purified gas BG2 as a fuel, as shown in FIG. The heat exchanger 304 for heating the fuel gas provided in The hot water generated by the hot water boiler 303 is used for vaporization in the hot water vaporizer 260 provided in the natural gas discharge pipe 270 and for heating in the warmer 160 of the purified gas discharge pipe 170. It is configured to be able to. The fuel gas circulation channel 320 is provided with a circulation pump 302 for circulating the fuel gas BG1 for collecting impurities through the heat exchanger 304 for heating the fuel gas and the heat exchange unit 12. Further, an impurity mixed gas discharge channel 350 for releasing the fuel gas BG1 mixed by vaporization of impurities from the gas purification unit 10 to the outside is a purified gas exhaust pipe 170 and a fuel gas circulation channel in the purified gas deriving unit 150. 320 is provided separately.

The above is the description of the schematic configuration of the fuel gas purification system 1 according to the present application. Hereinafter, the fuel gas purification system 1 will be described in detail along the flow of the fuel gas and the flow of the natural gas. First, the configuration and operation mode will be described along the flow of fuel gas.
As described above, the fuel gas BG1 supplied from the fuel gas cylinder (not shown) to the fuel gas supply pipe 120 is controlled to open and close through the fuel gas supply passage opening / closing valve VB, the humidifier 100, the fuel gas flow control valve V110, and the dehumidifier 105. Is sent to the fuel gas introduction unit 110 of the gas purification unit 10 through a valve V120 capable of

The humidifier 100 is a container containing water for adding moisture to the fuel gas BG1 (for example, a water temperature of 25 ° C.), and is configured to bubble a part of the fuel gas BG1. Humidification is performed as necessary, and the flow rate of the fuel gas BG1 flowing into the humidifier 100 can be adjusted by the flow rate adjusting valve V100.
The dehumidifier 105 removes moisture from the fuel gas BG1. Thus, by combining the humidifying device 100 and the dehumidifying device 105, the humidity of the fuel gas BG1 can be set to a desired humidity. And the quantity of the water adhering to the heat exchanger tube 11 of the heat exchange part 12 can be reduced by removing the water | moisture content in fuel gas BG1 before introduction | transduction to the gas purification part 10. FIG. Thereby, (i) the risk of blockage of the fuel gas on the upstream side of the flow of the fuel gas can be reduced, and (ii) the deterioration of the heat transfer characteristics of the heat transfer tube 11 is suppressed, and ( iii) It is possible to reduce the amount of accumulation when moisture becomes liquid in the impurity recovery step and accumulates at the bottom of the heat exchange unit 12.
As will be described later, the humidifier 100 and the dehumidifier 105 are selectively used according to the state (moisture content, degree of dryness) of the fuel gas BG1 to be processed.

  Further, the fuel gas flow control valve V110 (corresponding to the fuel gas temperature measuring unit) is a purified gas which is a refined fuel gas in the purified gas deriving unit 150 of the gas purification unit 10 as shown in FIGS. A temperature sensor T150 (corresponding to a fuel gas temperature measurement unit) that measures the temperature of BG2 is provided, and the temperature of the purified gas BG2 measured by the temperature sensor T150 is equal to or lower than a predetermined constant temperature. The flow rate of the fuel gas BG1 flowing into the gas purification unit 10 is adjusted. Here, the opening degree of the fuel gas flow rate control valve V110 is controlled by the fuel gas flow rate controller CTR110. Then, the fuel gas flow rate controller CTR110 uses the fuel gas flow rate control valve V110 so that the temperature of the refined gas BG2 derived from the heat transfer tube 11 becomes −130 ° C. to −138 ° C. or lower. The flow rate is controlled.

Next, the configuration of the gas purification unit 10 will be described in detail. As shown in FIG. 2, the gas purification unit 10 is introduced from the fuel gas introduction unit 110, which is an introduction unit to the gas purification unit 10, sequentially from the upstream side of the flow of the fuel gas BG 1. A heat exchange section 12 that is a flow path in the gas purification section 10 of the fuel gas, and a purified gas BG2 that has been subjected to heat exchange in the heat exchange section 12 and separated impurities are derived from the inside of the heat transfer tube 11 that is the fuel gas flow path 130. The refined gas deriving unit 150 is configured.
And the heat exchange part 12 is comprised so that the gas purification part 10 may be covered. That is, the heat exchanging portion outer peripheral portion 12a of the heat exchanging portion 12 is made of, for example, stainless steel, and has an outer diameter of about 165.2 mm (150 A). And the glass wool of thickness 25mm is wound as the heat insulating material 13 in the outer surface of the heat exchange part outer peripheral part 12a, and the heat exchange part 12 with which the heat insulating material 13 was wound is gas refinement of outer diameter 216.3mm (200A). The refinement part outer peripheral part 10a of the part 10 is accommodated. Thereby, in the heat exchange part 12, the heat insulation with the exterior is ensured.
In addition, the upper flange 10b and the lower flange 10c that close the upper and lower openings of the purification unit outer peripheral part 10a and the outer peripheral part 10a of the gas purification unit 10 are made of, for example, stainless steel, and the upper flange 10b includes a glass window 14 for observation. It has been. A temperature sensor T150 provided in the purified gas outlet 150 is a thermocouple, and is, for example, a T type (copper-constantan) suitable for low temperature measurement.

Here, the fuel gas introduction unit 110 and the heat exchange unit 12 are partitioned by a gas introduction unit support plate 15 that penetrates and supports the natural gas outlet tube 250 and the plurality of heat transfer tubes 11. In addition, a heat transfer tube introduction portion side opening 11a (corresponding to a heat transfer tube end portion opening) of the plurality of heat transfer tubes 11 provided through the heat exchange portion 12 and penetrating the gas introduction portion support plate 15 is disposed. The heat exchange section 12 has a natural gas outlet pipe opening 250a (corresponding to the outlet pipe end opening) of the natural gas outlet pipe 250 provided through the fuel gas inlet section 110 and penetrating the gas inlet support plate 15. It is arranged. Here, the term “through support” means that the heat transfer tube 11 is provided in a state of penetrating the gas introduction portion support plate 15, and the fluid flowing in the heat transfer tube 11 exceeds the gas introduction portion support plate 15 and the gas introduction portion support plate 15. This means that the heat transfer tube 11 is supported by the gas introduction unit support plate 15.
Further, in the fuel gas introduction part 110, the rectifying member 17 that uniformly adjusts the flow rate of the fuel gas BG1 in the direction orthogonal to the flow direction of the fuel gas BG1 by passing the fuel gas BG1 is different from that of the natural gas outlet pipe 250. While being in a contact state, the heat transfer tube 11 is provided on the upstream side of the heat transfer tube introduction portion side opening 11 a of the plurality of heat transfer tubes 11.

  On the other hand, the purified gas outlet 150 and the heat exchanger 12 are partitioned by the gas outlet support plate 16 that penetrates and supports the natural gas introduction pipe 240 and the plurality of heat transfer pipes 11. A plurality of heat transfer tube 11 openings 11b passing through the heat exchange unit 12 and penetrating the gas deriving unit support plate 16 are provided, and the heat exchange unit 12 includes a purified gas deriving unit. A gas introduction pipe opening 240 a of a natural gas introduction pipe 240 that passes through 150 and passes through the gas outlet support plate 16 is disposed. Thereby, the heat exchange part 12 is formed as a sealed space partitioned by the gas introduction part support plate 15, the gas outlet part support plate 16, and the heat exchange part outer peripheral part 12a.

  As shown in FIG. 3, in the fuel gas introduction part 110, the flow direction of the fuel gas BG <b> 1 through which the heat transfer pipe introduction part side openings 11 a of the plurality of heat transfer pipes 11 into which the fuel gas BG <b> 1 is introduced has passed through the rectifying member 17. Are uniformly distributed in a direction perpendicular to the direction. That is, the plurality of heat transfer tubes 11 have their heat transfer tube introduction portion side openings 11a arranged in the left and right and front and rear directions (left and right and up and down in FIG. 3) in the direction orthogonal to the flow direction of the fuel gas BG1. The gas introduction unit support plate 15 (corresponding to the support plate) and the gas lead-out unit support plate 16 are provided so as to be arranged at equal intervals of the distance (D2).

  Here, the outer diameter D1 of the heat transfer tube 11 is designed to be 10 mm or more and 16 mm or less, and the thickness of the tube wall 11c is designed to be 1.2 mm or less and 0.4 mm or more. When the outer diameter of the heat transfer tube 11 is less than 10 mm, the adhering solid matter is likely to block, and it is necessary to increase the number of the heat transfer tubes 11 according to the processing amount of the fuel gas BG1 in order to avoid the blockage. The heat exchange part 12 cannot be formed compactly. On the other hand, when the outer diameter of the heat transfer tube 11 exceeds 16 mm, the surface area in the tube of the heat transfer tube 11 to which impurities per certain volume adhere in the heat exchanging portion 12 is reduced, so that the throughput of the fuel gas BG1 is reduced. To do.

  Further, the arrangement interval D2 in the left and right and front and rear directions (left and right and up and down in FIG. 3) in the direction orthogonal to the flow direction of the fuel gas BG1 in the heat transfer tube 11 is 1.1 times or more the outer diameter D1 of the heat transfer tube 11. Designed as 1.5 times or less. When the arrangement interval D2 of the heat transfer tubes 11 is 1.1 times or more the outer diameter of the heat transfer tubes 11, the heat transfer tube introduction portion side openings 11a of the heat transfer tubes 11 that are close to each other are formed in the gas introduction portion support plate 15 and the gas outlet portion. It is possible to perform a strong welding operation without leaking to the support plate 16, and the heat exchange section 12 can be made compact by reducing the arrangement interval D2 of the heat transfer tubes 11 to 1.5 times or less the outer diameter D1 of the heat transfer tubes 11. Can be formed. By realizing the compact heat exchange unit 12, the amount of the liquefied natural gas NG1 filled in the heat exchange unit 12 can be reduced, and the liquefied natural gas NG1 generated by heat input from the outside of the heat exchange unit 12 can be reduced. The cooling loss due to evaporation can be reduced, and the weight of the heat exchange unit 12 can be reduced. The material of the gas inlet support plate 15, the gas outlet support plate 16 and the heat transfer tube 11 is preferably stainless steel (for example, SUS304) which is excellent in weldability.

  Considering the above, in the present embodiment, the outer diameter D1 of the heat transfer tube 11 is 13.8 mm, and the thickness of the tube wall 11c is 0.5 mm. Further, the length from the heat transfer tube introduction portion side opening 11a to the heat transfer tube lead-out portion side opening 11b is 1.0 m. And 52 are accommodated in the heat exchange part 12 (only four are shown in FIG. 2). Furthermore, the arrangement interval D2, which is the distance between the centers in the cross section of the heat transfer tube 11, is 17 mm.

Next, the rectifying member 17 will be described. As shown in FIG. 2, in the fuel gas introduction unit 110, the rectifying member 17 that uniformly adjusts the flow rate of the fuel gas BG 1 in the direction perpendicular to the flow direction of the fuel gas BG 1 by the passage of the fuel gas BG 1 is natural gas. A space 17 a is provided between the outlet pipe 250 and the outer peripheral portion so as to be in a non-contact state, and is provided on the upstream side of the heat transfer tube introduction portion side opening 11 a of the plurality of heat transfer tubes 11. The rectifying member 17 is composed of a porous plate having heat insulating properties and gas permeability.
As shown in FIG. 4, the rectifying member 17 includes, for example, a through hole 17c having a diameter D3 of 2 mm on a resin plate having a thickness of 3 mm, and an arrangement interval (center distance) between the centers of the through holes 17c. It is formed of a porous plate in which through-holes 17c are provided uniformly in the front and rear and left and right directions (up and down and left and right directions in FIG. 4) so that D4 is 6 mm.
The material of the porous plate is specifically formed of polycarbonate, polyethylene, vinyl chloride, Teflon (registered trademark), polypropylene, or the like. Thus, since the rectifying member 17 is formed of a resin-made porous plate, the porous plate is liquefied natural gas NG1 because it has a heat insulating property and is formed of a material that is not easily cooled by the cold heat of the natural gas NG1. Therefore, it is possible to prevent the impurities in the fuel gas BG1 from condensing in the porous plate. Moreover, since it has a moderate pressure loss because it is formed in a porous shape, the flow velocity of the fuel gas BG1 that has passed through the rectifying member 17 is uniformly adjusted in the direction orthogonal to the flow direction, and each heat transfer tube The flow rate of the fuel gas BG1 flowing into the fuel cell 11 can be made equal.
As shown in FIG. 2, for example, support members 17 b having a thickness of 2 mm, a width of 10 mm, and a length L of 30 mm are attached at six locations around the lower surface side of the rectifying member 17. It is placed on the part support plate 15. Thereby, it forms so that the distance from the rectification | straightening member 17 to the introduction part side opening 11a of the some heat exchanger tube 11 may become fixed distance. Here, the length L of the support member 17b is 10 to 20 times the thickness of the rectifying member 17 that maintains a good rectifying state in the flow of the fuel gas BG1 rectified by the rectifying member 17. . Note that the example shown in FIG. 2 is schematically illustrated for easy understanding.

  The gas purification unit 10 is configured as described above, and in the heat exchange unit 12, the liquefied natural gas NG1 that is a cooling medium flows outside the heat transfer tube 11, and the fuel gas BG1 that is a purification target flows inside the heat transfer tube 11. Flowing. The liquefied natural gas NG1 flows outside the heat transfer tube 11, but the cold heat of the liquefied natural gas NG1 is transferred to the heat transfer tube, and impurities in the fuel gas BG1 flowing in the heat transfer tube 11 flow outside the heat transfer tube 11. It is condensed or solidified by the cold heat of the flowing liquefied natural gas NG1, liquefied and solidified, and attached to the inside of the heat transfer tube 11. Thereby, the impurities in the fuel gas BG1 flowing in the heat transfer tube 11 are removed, and the purified gas BG2 is led out from the heat transfer tube 11.

Returning to FIG. 1, the downstream configuration of the gas purification unit 10 will be described.
The purified gas outlet 150 is connected downstream to the heater 160 via a valve V310 that can be controlled to open and close. In addition, an apparatus (not shown) for measuring an impurity concentration and a detection tube can be connected to the branch flow path provided with the sampling valve V280 on the downstream side of the heater 160.

  The warmer 160 brings the purified gas BG2 having a low temperature by heat exchange for removing impurities in the gas refining unit 10 close to room temperature prior to supply to the demand point. An apparatus for measuring the impurity concentration connected downstream of 160, the detector tube is used to check the quality of the purified gas BG2 supplied to the demand point, and to perform control based on the quality, It is to detect.

  That is, in the present embodiment, the purified gas BG2 derived from the purified gas deriving unit 150 can be provided to the consumer after the temperature is brought close to normal temperature by the heater 160 and the quality is then confirmed. It has a configuration.

Next, the configuration of the fuel gas purification system 1 according to the present invention will be described from the upstream side along the flow of natural gas that is a cooling medium.
The cryogenic liquefied natural gas NG1 used as a cooling medium is received from the liquefied natural gas tank 201. The liquefied natural gas NG1 is introduced into the natural gas flow path 230 by the natural gas supply pipe 220 through the natural gas introduction pipe 240 provided in the gas purification unit 10. The natural gas supply pipe 220 is a pipe having an outer diameter of 21.7 mm (15A). In the natural gas introduction pipe 240, from one pipe having an outer diameter of 21.7 mm (15A) to four pipes having an outer diameter of 13.9 mm (8A) (two in each of the front and rear and the left and right, respectively) 2 is shown in FIG. 2, and the liquefied natural gas NG1 is introduced into the natural gas flow path 230 of the heat exchange unit 12. The material of these pipes is made of stainless steel (SUS304).

  Further, as shown in FIG. 1, the gas purification unit 10 can be led out to the outside through a natural gas lead-out pipe 250. A flexible pipe 250b (see FIG. 2) is incorporated in the natural gas outlet pipe 250, and is configured to prevent the occurrence of stress due to thermal contraction / expansion caused by temperature change. Then, a hot water vaporizer 260 provided in a natural gas discharge pipe 270 connected downstream of the natural gas outlet pipe 250, and a flow meter FM260 for vaporized natural gas connected downstream of the hot water vaporizer 260 and It is connected to the outside of the fuel gas purification system 1 according to the present invention via the vaporized natural gas flow control valve V270. The natural gas outlet pipe 250 and the natural gas discharge pipe 270 are pipes having an outer diameter of 21.7 mm (15A). The material of these pipes is made of stainless steel (SUS304).

  In the present embodiment, the natural gas flow path 230 in the gas purification unit 10 corresponds to a portion outside the heat transfer tube 11 in the heat exchange unit 12. That is, the liquefied natural gas NG1 introduced into the heat exchange unit 12 from the natural gas introduction pipe 240 is in contact with the heat transfer pipe 11 in the natural gas flow path 230, so that the fuel gas BG1 passing through the inside of the heat transfer pipe 11 and the stainless steel Heat exchange is performed through the heat transfer tube 11 and the gas is heated and vaporized. Then, a gas mixture of the natural gas NG2 vaporized and the liquefied natural gas NG1 that has not been vaporized is led out to the natural gas outlet pipe 250 from the heat exchange unit 12.

  That is, in the fuel gas purification system 1 according to the present invention, the fuel gas BG1 as the purification target and the liquefied natural gas NG1 as the cooling medium are physically separated from each other in the heat exchange process and the natural gas 130 and the natural gas. It is configured to pass through the gas flow path 230. In order to indirectly perform heat exchange in such a separated configuration, the liquefied natural gas NG1 or liquefied natural gas NG1 generated in the case of direct heat exchange in which the fuel gas BG1 flows in the liquefied natural gas NG1 or the vaporized natural gas NG2 or There is no problem of mixing into the vaporized natural gas NG2.

The hot water vaporizer 260 connected to the natural gas discharge pipe 270 vaporizes all of the liquefied natural gas NG1 that has not been vaporized out of the liquefied natural gas NG1 and the vaporized natural gas NG2 derived from the gas purification unit 10. Is for.
That is, a part of the liquefied natural gas NG1 introduced into the natural gas flow path 230 is vaporized by heat exchange with the fuel gas BG1 in the natural gas flow path 230, and becomes a vaporized natural gas NG2. Without being vaporized, the liquefied natural gas NG1 is discharged from the natural gas outlet pipe 250 to the natural gas discharge pipe 270. Therefore, by connecting the hot water vaporizer 260 to the natural gas discharge pipe 270 downstream of the gas purification unit 10, all of the liquefied natural gas NG1 derived from the gas purification unit 10 is vaporized, and all is made into vaporized natural gas NG2. . The heat source of the hot water vaporizer 260 is a hot water boiler 303, and hot water at 80 ° C. is supplied to the hot water vaporizer 260.

  Then, the vaporized natural gas NG2 vaporized through the hot water vaporizer 260 is controlled in flow rate through the vaporized natural gas flow meter FM260 and the vaporized natural gas flow control valve V270, and the fuel gas purification system according to the present invention. 1 is provided to the outside.

  In the fuel gas purification system 1 according to the present invention, when the amount of impurities in the fuel gas BG1 adhering to the inside of the heat transfer tube 11 increases, for example, the heat conduction performance of carbon dioxide, which is an impurity, is significantly greater than that of the heat transfer tube 11. Therefore, the heat transfer characteristics of the heat exchange unit 12 are deteriorated, and the performance of removing impurities as a solid material is gradually reduced. In this case, the system of the present application collects solid or liquid impurities adhering to the heat transfer tube 11 by the impurity recovery mechanism 30 separately from the vaporized natural gas NG2, so that the heat transfer characteristics of the original heat exchange unit 12 are recovered. Is recovered, and the impurity removal performance of the gas purification unit 10 is regenerated.

[Fuel gas purification operation]
Next, the purification operation of the fuel gas BG1 in the present embodiment will be described based on FIG.
In FIG. 6, which is a conceptual diagram showing the state of gas flow purification as a premise, the fuel gas BG1 is purified, the fuel gas supply pipe 120, the natural gas discharge pipe 270, and the natural gas connected to the gas purification unit 10 are shown. The valves VB, V100, V110, V120, V310, V210, V260, and V270 associated with the gas supply pipe 220 and the natural gas discharge pipe 270 are opened (indicated by hollow white symbols), while the fuel gas of the impurity recovery mechanism 30 Valves V320 and V360 related to the circulation flow path 320 and the impurity mixed gas discharge flow path 350 are closed (indicated by black symbols).

The fuel gas BG1 to be purified in this example is a gas produced by simulating digestion gas obtained by anaerobic fermentation of sewage sludge. For example, methane 60%, carbon dioxide 40%, decamethylcyclopentasiloxane. It is composed of 80 mg / m ³ N, oxygen 0.06%, and nitrogen 1.4%, and is supplied from a fuel gas cylinder (not shown) connected to the fuel gas purification system 1 according to the present invention. Here, for example, the fuel gas cylinder has a capacity of 47 l and a fuel supply pressure of 12 MPa.

In this embodiment, the flow rate of the fuel gas BG1 is controlled by the fuel gas flow rate control valve V110 upstream of the gas purification unit 10. Specifically, the temperature is controlled to 25 ° C. so that the flow rate of the fuel gas BG1 is 0.6 m ³ N / h on average.
This flow rate control is to control the flow rate of the fuel gas BG1 to be purified upstream of the gas purification unit 10 so that the concentration of a specific impurity in the refined gas BG2 does not rise above a predetermined value. is there. As a preferable temperature condition, for example, when processing a fuel gas at an atmospheric pressure level, and taking the concentration of carbon dioxide as an example, in order to reduce the concentration of carbon dioxide to 1% or less, In order to maintain the temperature of the purified gas BG2 measured by the temperature sensor T150 at −125 ° C. or lower and 0.5% or lower, it is necessary to maintain it at −130 ° C. or lower. In the present embodiment, the flow rate of the fuel gas BG1 is adjusted by controlling the opening of the fuel gas flow rate control valve V110 by the flow rate controller CTR110 based on the temperature detected by the temperature sensor T150 of the gas purification unit 10, and purified. The temperature of the gas BG2 is maintained at a desired temperature.

In the present embodiment, the moisture of the fuel gas BG1 is removed by the dehumidifier 105 before being introduced into the gas purification unit 10. Specifically, the temperature of the fuel gas BG1 at the inlet of the dehumidifying device 105 is 25 ° C., which is the same as the room temperature, and the humidity is about 67%, but the fuel gas BG1 is cooled by the dehumidifying device 105, and the moisture in the fuel gas BG1 is removed. Dehumidified to 8 ° C saturation. As a result, the amount of water in the fuel gas BG1 is reduced to about half and introduced into the gas purification unit 10.
When the humidity of the fuel gas BG1 is very low, the humidifier 100 bypasses a part of the fuel gas BG1 and causes it to be bubbled with water for humidification. Thereby, the humidity of the fuel gas BG1 introduced into the gas purification unit 10 can always be maintained at a stable humidity.

On the other hand, the liquefied natural gas NG1 (heat quantity is 45 MJ / m ³ N) supplied to the gas purification unit 10 as a cooling medium in the present embodiment is a gas having a temperature of about −145 ° C. and is supplied from the liquefied natural gas tank 201. Yes. The liquefied natural gas tank 201 uses a commonly used LNG portable container having a volume of 175 L (two units may be connected). The liquefied natural gas NG1 is delivered by increasing the pressure to about 0.25 MPa by the method using the internal pressure of the liquefied natural gas tank 201 and pushing out the liquefied natural gas NG1. The flow rate is, for example, 28 × 10 ⁻³ m ³ / h (about 16 m ³ N / h in terms of natural gas after vaporization) in the state of liquefied natural gas NG1, and is introduced into the gas purification unit 10 (this book Since the embodiment uses a small apparatus and heat loss increases, the ratio of the natural gas equivalent flow rate after vaporization to the flow rate of the fuel gas BG1 is 26.7 (= 16 / 0.6), but the scale is large. For large devices, this ratio is significantly smaller).

  The mechanism of purification of the fuel gas BG1 by heat exchange between the fuel gas BG1 and the liquefied natural gas NG1 in the heat exchange unit 12 after introduction into the gas purification unit 10 is as described above with reference to FIG.

The purified gas BG2 purified by the gas purification unit 10 is led out of the gas purification unit 10 from the purified gas deriving unit 150, and is heated to 25 ° C., which is the same as the room temperature, by the heater 160 installed downstream of the purified gas deriving unit 150. The temperature is raised to the extent. In the present embodiment, the warmer 160 uses hot water supplied by the hot water boiler 303 as a heat source.
The purified gas BG <b> 2 heated by the heater 160 is measured for impurity concentration by an impurity concentration measurement device installed downstream of the heater 160.
In this example, the impurity concentration is (i) for carbon dioxide, oxygen and nitrogen, gas chromatograph using a TCD detector, and (ii) for decamethylcyclopentasiloxane, the sampling gas is absorbed in hexane, Analysis was performed with a gas chromatograph mass spectrometer, and (iii) water was measured by a commonly used measurement method of measurement with a dew point meter. Here, sampling for detecting the impurity concentration of the purified gas BG2 is performed by the sampling valve V280.

As a result, the purified gas BG2 has an impurity concentration of 0.5% or less, decamethylcyclopentasiloxane of 0.1 mg / m ³ N or less, and a moisture dew point of −30 in the present example. The oxygen concentration is 0.1% or less, the average oxygen is 2.3%, and the impurity concentration is problematic even when used in major gas consuming equipment such as gas engines, gas turbines, hot water boilers, steam boilers, etc. There was no low enough level.

Further, in the present embodiment, a hot water vaporizer 260 is installed downstream of the gas purification unit 10 and passed through the mixed gas of the liquefied natural gas NG1 and the vaporized natural gas NG2 derived from the gas purification unit 10. Thus, after the vaporized natural gas NG2 is completely vaporized, the flow rate is controlled and provided outside the fuel gas purification system 1 according to the present invention.
In the present embodiment, a hot water boiler 303 is adopted as a heat source of the hot water vaporizer 260, and hot water at 80 ° C. is supplied. Further, the flow rate of the vaporized natural gas NG2 is measured with a flow meter FM260 for vaporized natural gas installed downstream of the hot water vaporizer 260, and vaporized so that the flow rate of the vaporized natural gas NG2 is about 16 m ³ N / h. It is controlled by a natural gas flow rate control valve V270.

[Mixing of purified gas and vaporized natural gas]
FIG. 5 is a configuration diagram showing a gas mixing adjustment system 2 provided on the downstream side of the fuel gas purification system 1 in the product gas production system in the present embodiment.
The gas mixing and adjusting system 2 includes a refined gas BG2 from which impurities have been separated from the fuel gas BG1, a vaporized natural gas NG2 that has undergone heat exchange with the fuel gas BG1, and a heat quantity adjustment. This is a system for obtaining a product gas GS by mixing propane gas, which is an industrial gas, and is provided downstream of the fuel gas purification system 1. Thereby, the product gas GS in which the heat quantity of the product gas GS is adjusted to a heat quantity within a predetermined heat quantity range can be obtained.

Hereinafter, based on FIG. 5, the apparatus structure of the gas mixing adjustment system 2 is demonstrated.
The gas mixing and adjusting system 2 is a mechanism for mixing the purified gas BG2 after purification by the fuel gas purification system 1 and the vaporized natural gas NG2, and measures the flow rate of the purified gas BG2 in the flow path 610 of the purified gas BG2. The flow meter FM610 for measuring the flow rate of the vaporized natural gas NG2 is installed in the flow path 620 of the vaporized natural gas NG2. Then, the refined gas BG2 and the vaporized natural gas NG2 are mixed downstream of the flow meter FM610 and the flow meter FM620 to obtain a mixed fuel gas. The flow rate measurement results obtained by the flow meters FM610 and FM620 are input to the flow rate controller CTR110 (see FIG. 1), and the flow rate ratio between the purified gas BG2 and the vaporized natural gas NG2 is obtained. . Further, the flow rate ratio between the refined gas BG2 and the vaporized natural gas NG2 is determined by the CTR 110 so that the purified gas is controlled by opening the fuel gas flow control valve V110 and the vaporized natural gas flow control valve V270 (see FIG. 1) in the fuel gas purification system 1. It can be changed by adjusting the flow rate of BG2 and vaporized natural gas NG2.

A first static mixer 630 is installed downstream of the mixing location of the purified gas BG2 and the vaporized natural gas NG2 in order to improve the uniformity of the mixed state. One cushion tank 640 is installed.
A flow meter FM 710 for measuring the flow rate of the mixed fuel gas is set downstream of the first cushion tank 640, an LPG calorific value adjustment device 710 is set downstream thereof, and a second static mixer 730 is set downstream thereof. ing. A calorific value measurement device 720 and a second cushion tank 740 are installed downstream of the second static mixer 730, and an odorizing device 810 is installed downstream of the second cushion tank 740. Odor is given by odorant.
The product gas GS odorized by the odorizing device 810 is connected to the city gas conduit 910 and the usage destination so as to be supplied to the demand point.

Based on FIG. 5, the calorific value adjustment of the mixed fuel gas in the present embodiment will be described.
The gas mixing adjustment system 2 of the present embodiment uses the first static mixer 630 to improve the uniformity of the mixed state of the mixed fuel gas obtained as described above. The static mixer may be a general one. Thereafter, the mixed fuel gas exiting the first static mixer 630 is passed through the first cushion tank 640 to suppress the pressure fluctuation and the calorific value fluctuation range. In the present embodiment, the volume of the first cushion tank 640 is 30L.

The mixed fuel gas exiting the first cushion tank 640 passes through the flow meter FM 710 and is added with propane gas by the LPG calorie adjusting device 710 to become a calorie-adjusted mixed gas whose calorie is adjusted. The amount of heat is adjusted by measuring the flow rate of the mixed fuel gas with the flow meter FM710 and after adjusting the amount of heat, after passing through a second static mixer 730 to be described later, the amount of heat of the heat amount adjusted mixed gas after improving the uniformity of the mixed state Based on the measured value by the calorimeter 720 (that is, the calorimeter 720 measures the calorie of the calorie-adjusted mixed gas downstream of the second static mixer 730) so that the calorie is within a predetermined range. Do. In the present embodiment, as the predetermined range, and ^{44.5MJ / m 3 N~45.5MJ / m 3} N by assuming an injection urban Gasuhe. A general LPG heat quantity adjusting device 710 is used.

Moreover, the calorie-adjusted mixed gas can improve the uniformity of the mixed state by the second static mixer 730 (Note that the calorie-adjusted mixed gas after the second static mixer 730 has improved the uniformity of the mixed state) As described above, the calorific value is measured with the calorimeter 720. And the gas mixing adjustment system 2 in a present Example suppresses a pressure fluctuation and a calorie | heat amount fluctuation range by letting the mixed fuel gas which came out of the 2nd static mixer 730 pass to the 2nd cushion tank 740.
In addition, in this embodiment, for the sake of safety, the calorie-adjusted mixed gas obtained above is odorized with an odorant to obtain a product gas GS. A general-purpose odorant is selected. As the odorant, a general odorizer 810 is used.

  Further, the concentration of oxygen and nitrogen is measured for the product gas GS odorized to the calorie-adjusted mixed gas exiting the second cushion tank 740. As a measuring method, a gas chromatograph method using a commonly used TCD detector is used. The oxygen and nitrogen concentrations of the product gas GS are 0.002% on average for oxygen and 0.05% on average for nitrogen. Further, the dew point of the product gas GS is −50 ° C. or less. Accordingly, as described above, in addition to use in a gas engine, a gas turbine, a hot water boiler, a steam boiler, etc., it is suitable for use as a raw material for a fuel cell and a hydrogen generator.

  Although the concentrations of oxygen and nitrogen in the vaporized natural gas NG2 are very low, the concentrations of oxygen and nitrogen before and after mixing the vaporized natural gas NG2 with the purified gas BG2 are the vaporized natural gas NG2 in this embodiment. Since the flow rate magnification of the purified gas BG2 is 44.4 times, the concentration is reduced to a concentration level of 1 / 45.4. As a result, as described above, the temperatures of oxygen and nitrogen are examples of reference values determined by the gas company when used by being injected into the city gas conduit 910 "Oxygen 0.01% or less, nitrogen 1 % Or less ”and the product gas GS can be injected into the city gas conduit 910.

Thus, it is preferable to measure the gas composition of the product gas GS and the odorant concentration downstream of the second cushion tank 740 before actually injecting into the city gas conduit 910. For example, in the case where the reference values of the gas consumption equipment and the use to the city gas conduit 910 with respect to the concentrations of oxygen and nitrogen are strict, in order to more reliably satisfy the reference values, these concentrations are used. Is input to the flow rate controller CTR110 (see FIG. 1), and based on these measured values, the flow rate ratio between the vaporized natural gas NG2 and the purified gas BG2 is determined by the fuel gas flow rate control valve V110 and the vaporization. What is necessary is just to adjust using the natural gas flow control valve V270 (refer FIG. 1).
Furthermore, with respect to other specific impurities, when the reference value of the use destination such as injection into the gas consuming equipment or the city gas conduit 910 is strict, the vaporized natural gas NG2 and refinement are similarly performed based on the measured value of the impurity concentration. The reference value can be satisfied by adjusting the flow rate ratio of the gas BG2 using the fuel gas flow control valve V110 and the vaporized natural gas flow control valve V270.

[Regeneration treatment of the fuel gas purification unit]
FIG. 7 is a conceptual diagram showing an impurity recovery process (regeneration process) of the gas purification unit 10 by the impurity recovery mechanism 30 in the fuel gas purification system 1 according to the present invention. Hereinafter, the impurity recovery method of the gas purification unit 10 will be described with reference to FIG.

  The impurity recovery process of the gas purification unit 10 is started when it is detected that the amount of impurities attached to the heat transfer tube 11 has increased and the performance of removing impurities has deteriorated. As an index for detecting this, for example, a reduction in the flow rate of the fuel gas BG1 due to the blockage of the fuel gas flow channel 130 of the heat transfer tube 11 or a purification due to thermal conductivity being hindered by impurities adhering to the fuel gas flow channel 130. This is determined by an increase in the temperature of the purified gas BG2 in the gas outlet 150.

  If the removal process of the impurities in the fuel gas BG1 is continued, the amount of solid carbon dioxide adhering to the heat transfer tube 11 increases, and the performance of removing impurities such as carbon dioxide and siloxane decreases. At this time, the flow of the fuel gas BG1 and the liquefied natural gas NG1 is stopped and the gas purification unit 10 is regenerated. The reproduction method is as follows.

  First, the valves V120, V310, and V260 on the fuel gas BG1 introduction side, the derivation side, and the natural gas derivation side of the gas purification unit 10 are closed (indicated by black symbols). Next, after opening the valve V360, hot water (about 80 ° C.) produced by operating the hot water boiler 303 is supplied to the fuel gas heating heat exchanger 304, and the circulation channel valve V320 is opened to circulate. The pump 302 circulates and heats the fuel gas BG1 for impurity recovery, and circulates the heated fuel gas BG1 (corresponding to the regeneration gas) to the gas purification unit 10 to form the inner surface of the heat transfer pipe 11 and the natural gas introduction pipe 240. The impurities adhering to the outer surface of the natural gas outlet pipe 250 are sufficiently vaporized and desorbed. Here, the fuel gas BG1 is maintained at about 50 ° C. Then, the vaporized and desorbed impurities are diffused into the atmosphere from the impurity mixed gas discharge passage 350 together with the fuel gas BG1.

  Through the above steps, the regeneration process of the gas purification unit 10 is completed. After the regeneration process is completed, the fuel gas BG1 and the liquefied natural gas NG1 are flowed again to the gas purification unit 10 to purify the fuel gas.

[Another embodiment]
(A) In the above embodiment, regarding the liquefied natural gas NG1 used as a cold heat source in removing impurities, an ordinary liquefied natural gas NG1 is assumed, and the properties thereof are not particularly described. That is, any liquefied natural gas NG1 was used without regard to its origin and production area.
On the other hand, in the present invention, the purified gas BG2 obtained by the fuel gas purification system 1 and the vaporized natural gas NG2 used as a cold heat source are mixed to obtain the product gas GS after adjusting the amount of heat. If the amount of heat of the vaporized natural gas NG2 is adjusted in advance in the state of the liquefied natural gas NG1, the load for adjusting the amount of heat can be reduced or eliminated.
In this configuration, liquefied natural gas NG1 that is mixed with purified gas BG2 after use for removing impurities and is planned to be used for production of product gas GS is heated in advance to vaporize methane. The amount of heat of the liquefied natural gas NG1 is increased by reducing the methane concentration or adding the liquefied petroleum gas.
Thus, the calorific value of the product gas GS can be increased by increasing the calorific value of the liquefied natural gas NG1. Further, even when the product gas GS is manufactured by adjusting the amount of heat, the amount of liquefied petroleum gas (propane, butane, etc.) required for adjusting the amount of heat locally can be significantly reduced.
The fuel gas refining system 1 or product gas production system of the present invention can be employed in a city gas production plant that imports liquefied natural gas NG1 from overseas to produce city gas, etc., and is generally small and inland. The present invention can also be employed in a fuel gas production facility (for example, a gas station) provided with a fuel gas (biogas) production facility. In the latter case, the liquefied natural gas NG1 and the liquefied petroleum gas are transported to the gas station by the tank lorry and supplied to the gas storage tank of the gas station in the urban area. However, transportation of liquefied gas requires transportation costs, so it would be very expensive to transport both gases to the site. However, if only liquefied natural gas NG1 with high heat as described above is transported to the gas station, there will be a problem. It becomes possible to reduce the transportation cost etc. which become, and to reduce the manufacturing cost of product gas.

(B) In the said embodiment, although the rectifying member 17 was comprised with the porous board, you may comprise not only this but the rectifying member 17 with a nonwoven fabric. In this case, stainless steel long fibers or resin long fibers (nylon, polyester, polyethylene, etc.) having a diameter of 0.05 mm to 0.5 mm are deposited in a scrubbed shape, thickness 5 mm to 50 mm, density 0.1 to 0.3 g. / Cm ³ . Moreover, you may comprise the rectification | straightening member 17 as a laminated body of reticulated textiles, and the diameter of 5 mm-3.0 mm of stainless steel long fibers or resin long fibers (nylon, polyester, polyethylene, etc.) with a diameter of 0.05 mm-0.5 mm. A plurality of woven fabrics are laminated, the thickness is 1 mm to 10 mm, the density is 0.2 to 2.0 g / cm ³ (in the case of stainless steel long fibers), 0.05 to 0.5 g / cm ³ (of the resin long fibers) Case). Further, the rectifying member 17 may be configured as a continuous foam, which is formed by foaming polyurethane or polyolefin so that the internal pores are continuous, and has a thickness of 5 to 30 mm and a density of 0.1 to 0.3 g / cm. ^Configured as ³ .

(C) In the above embodiment, the temperature sensor T150 that measures the temperature of the purified gas BG2 that is the refined fuel gas is provided, and the temperature of the purified gas BG2 measured by the temperature sensor T150 is set in advance. The fuel gas flow rate control valve V110 for adjusting the flow rate of the fuel gas BG1 flowing into the gas purification unit 10 so as to be equal to or lower than the predetermined temperature is provided, but not limited thereto, the vaporized natural gas flow rate control valve V270 is provided. The flow rate of the liquefied natural gas NG1 flowing into the gas purification unit 10 may be adjusted so that the temperature of the purified gas BG2 measured by the temperature sensor T150 is equal to or lower than a predetermined temperature set in advance.

(D) In the above embodiment, the rectifying member 17 is provided with a large number of through holes 17c having a diameter D3 of 2 mm on a resin plate having a thickness of 3 mm at equal intervals in the front-rear and left-right directions when viewed from above. However, the material is not limited to this, and the material may be made of metal (for example, stainless steel). The diameter D3 of the through hole 17c is changed within a range of 1 mm to 3 mm, and the thickness of the porous plate is changed within a range of 1 mm to 3 mm. May be provided.

(E) In the above embodiment, the gas purification unit 10 is provided with the fuel gas supply pipe 120 as the regeneration gas supply flow path and the fuel gas circulation flow path 320 as the regeneration gas circulation flow path separately connected. However, the present invention is not limited to this, and a regeneration gas supply channel may be connected to a fuel gas circulation channel 320 as a regeneration gas circulation channel.

(F) In the above-described embodiment, the heated fuel gas BG1 is used as the regeneration gas in the impurity recovery process. However, the present invention is not limited to this, and heated air or nitrogen may be used as the regeneration gas. .

  According to the present invention, it is possible to provide a fuel gas purification system and a product gas production system capable of maintaining the performance of compacting the apparatus and preventing the partial condensation of impurities to separate the impurities. .

DESCRIPTION OF SYMBOLS 1 Fuel gas purification system 2 Gas mixing adjustment system 10 Fuel gas refinement | purification part 11 Heat exchanger tube 11a Heat exchanger tube introduction part side opening (heat exchanger tube edge part opening)
12 heat exchange part 15 gas introduction part support plate (support plate)
17 Rectifying member 30 Impurity recovery mechanism 110 Fuel gas introduction part 120 Regeneration gas supply pipe (fuel gas supply flow path)
130 Fuel gas passage 150 Refined gas outlet 230 Natural gas passage 240 Natural gas introduction pipe 250 Natural gas outlet pipe 250a Natural gas outlet pipe opening (outlet pipe end opening)
320 Regeneration gas circulation channel (fuel gas circulation channel)
350 Impurity mixed gas discharge flow path BG1 Fuel gas BG2 Refined gas GS Product gas NG1 Liquefied natural gas NG2 Natural gas (vaporized natural gas)
T150 Purified gas temperature measurement unit (temperature sensor)
V110 Fuel gas flow rate adjuster (fuel gas flow rate control valve)

Claims (6)

A fuel gas purification system comprising a fuel gas purification unit for purifying a fuel gas containing impurities obtained by anaerobic fermentation or pyrolysis of organic matter,
The fuel gas purification unit includes a plurality of the heat transfer tubes having a fuel gas flow channel through which the fuel gas flows inside the heat transfer tube and a natural gas flow channel through which liquefied natural gas flows outside the heat transfer tube. A heat exchanging part that exchanges heat between the fuel gas and the liquefied natural gas;
A fuel gas introduction section for introducing the fuel gas into the fuel gas flow path; and a purified gas deriving section for deriving the purified gas from which the impurities are removed from the fuel gas from the fuel gas flow path;
A natural gas introduction pipe for introducing the liquefied natural gas into the natural gas flow path, and a natural gas discharge pipe from which the natural gas after the heat exchange is led out from the natural gas flow path,
The fuel gas introduction part and the heat exchange part are partitioned by a support plate that penetrates and supports the natural gas outlet pipe and the plurality of heat transfer pipes, and the fuel gas introduction part passes through the heat exchange part In addition, a plurality of heat transfer tube end openings of the heat transfer tubes penetrating the support plate are disposed, and the natural gas passes through the fuel gas introduction portion and penetrates the support plate in the heat exchange portion. An outlet pipe end opening of the outlet pipe is disposed,
In the fuel gas introduction unit, a rectifying member that uniformly adjusts the flow rate of the fuel gas in a direction orthogonal to the flow direction of the fuel gas by passing the fuel gas is in a non-contact state with the natural gas outlet pipe. And provided upstream of the heat transfer tube end openings of the plurality of heat transfer tubes,
The impurities contained in the fuel gas are separated in a state where the impurities are attached to the inside of the heat transfer tube as a liquid or solid matter by the cold heat of the liquefied natural gas in the heat exchange unit,
A fuel gas purification system comprising an impurity recovery mechanism for recovering the adhered impurities separately from the purified gas.   2. The fuel gas purification system according to claim 1, wherein the rectifying member is configured by a laminated body of a porous plate, a nonwoven fabric, or a net-like woven fabric formed of a material having heat insulating properties and gas permeability.   In the fuel gas introduction part, the heat transfer tube end openings of the plurality of heat transfer tubes into which the fuel gas is introduced are uniformly distributed in a direction perpendicular to the flow direction of the fuel gas that has passed through the rectifying member. 3. The fuel gas purification system according to claim 1, wherein the fuel gas purification system is provided so as to have the same distance from the rectifying member to the heat transfer tube end openings of the plurality of heat transfer tubes.   The impurity recovery mechanism supplies a regeneration gas supply channel for supplying a regeneration gas having a temperature for vaporizing the impurities adhered to the inside of the heat transfer tube to the heat transfer tube, and the regeneration gas that has passed through the heat transfer tube is again transmitted to the heat transfer tube. A regeneration gas circulation passage for supplying heat pipes, and an impurity mixed gas discharge passage for discharging the impurity mixed gas mixed with the regeneration gas by vaporizing the impurities from the fuel gas purification unit. 4. The fuel gas purification system according to any one of 3 above.   A purification gas temperature measurement unit for measuring the temperature of the purification gas, and the fuel gas purification so that the temperature of the purification gas measured by the purification gas temperature measurement unit is equal to or lower than a predetermined temperature. The fuel gas flow rate adjusting unit for adjusting the flow rate of the fuel gas introduced into the unit, or the natural gas flow rate adjusting unit for adjusting the flow rate of the liquefied natural gas, is provided. The fuel gas purification system as described in any one of Claims.   After the heat exchange in which heat exchange between the refined gas obtained by the fuel gas purification system according to any one of claims 1 to 5 and the refined gas from which the impurities are separated from the fuel gas is performed. A product gas production system provided with a gas mixing adjustment system for mixing a natural gas with a natural gas in the downstream side of the fuel gas purification system.

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