JP2015071989A - Ammonia occlusion and release device and exhaust gas purification system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ammonia occlusion and release device and an exhaust gas purification system which can perform occlusion and release of NHat room temperature or at a temperature of several ten degree lower than room temperature with pressure adjustment, can make occlusion amount of NHper 1 g more than CaCland can make body dimensions in such a state as to occlude the same amount of NHless than CaCl.SOLUTION: An exhaust gas purification system 10 includes an exhaust channel 12 through which exhaust gas exhausted from an internal combustion engine (diesel engine 11) is circulated, a selective reduction catalyst (SCR catalyst 13) which is disposed on the exhaust channel 12, an ammonia occlusion and release device 14 which occludes NHand releases NHto the exhaust passage 12 via a pipe path and a control device 25. The ammonia occlusion and release device 14 includes an ammonia supply tank 16, etc. which stores LiCl as ammonia occlusion and release material 15. The control device 25 controls a release amount of NHto the exhaust channel 12 from the ammonia occlusion and release device 14 in accordance with an NOx amount in the exhaust channel 12.

Description

  The present invention relates to an ammonia storage / release device and an exhaust gas purification system.

NOx (nitrogen oxides) in exhaust gas discharged from an internal combustion engine is purified by a NOx purification device. In particular, the NOx purification device used in a diesel engine uses an SCR (selective reduction catalyst) in its exhaust system. ing. In this NOx purification device, a reducing agent such as urea is supplied to the SCR catalyst, ammonia (NH ₃ ) generated from urea is adsorbed to the SCR catalyst, and the NOx in the exhaust gas is selectively reduced by the adsorbed ammonia. Is going.

In addition, a method of supplying ammonia to the SCR catalyst using an ammonia storage material that stores ammonia has also been proposed (Patent Document 1 and Patent Document 2). Patent Document 1 mentions Mg (NH ₃ ) ₆ Cl ₂ as a preferred ammonia storage material. In Patent Document 2, MgCl ₂ , CaCl ₂ , SrCl ₂ or a mixture thereof is listed as a preferable ammonia storage material.

Special table 2008-508186 Special table 2008-528431 gazette

Among the metal chlorides known as substances that occlude NH ₃ , CaCl ₂ can occlude 8 times the amount of NH ₃ in molar ratio.
CaCl ₂ + 8NH ₃ → Ca (NH ₃ ) ₈ Cl ₂
However, chloride has a large molecular weight, and when the storage amount of NH ₃ per mole is the same, the storage amount per weight is smaller than that of a compound having a small molecular weight.

Further, since the desorption (release) temperature of the occluded NH ₃ is high, the amount of heat necessary for the supply (release) of NH ₃ increases. Patent Document 1 describes that ammonia can be released from a metal ammine salt by heating the metal ammine salt, preferably in a temperature range of 100 ° C to 700 ° C, more preferably 150 ° C to 500 ° C. Yes. Patent Document 2 describes that the metal ammine salt complex is heated to a temperature of preferably 30 ° C to 700 ° C, more preferably to a temperature of 100 ° C to 500 ° C. It is possible to use the heat of the internal combustion engine for heating ammonia, but in that case, the equipment for heating becomes complicated. In addition, if the heater heating method is adopted, the equipment becomes simpler than the case of using the heat of the internal combustion engine, but the power consumption increases.

The present invention has been made in view of the above-mentioned problems, and the object thereof is to perform occlusion and release of NH ₃ by adjusting the pressure at room temperature or a temperature of several tens of degrees or less, and NH ₃ per gram. It is an object to provide an ammonia occlusion / release device using an occlusion / release material that can reduce the physique in a state where the amount of occlusion is greater than CaCl ₂ and occludes the same amount of NH ₃ , and an exhaust gas purification system using the same.

An ammonia storage / release device that solves the above problems includes a tank for storing ammonia storage / release material, an ammonia storage / release material stored in the tank, introduction of NH _{3 in} a pressurized state into the tank, and the inside of the tank. Used for at least one of the release of NH ₃ , a pipe provided with a valve in the middle, an ammonia release pipe for releasing NH ₃ in the tank, and an amount of NH ₃ released from the ammonia release pipe And the ammonia storage / release material is LiCl. Here, “a pipe used for at least one of introduction of NH ₃ under pressure into the tank and release of NH ₃ in the tank, and a valve provided on the way” “ammonia release that releases NH ₃ in the tank” “Piping” may also be used.

According to this configuration, NH ₃ is introduced into the tank in a pressurized state from a pipe provided with a valve in the middle, and the introduced NH ₃ is stored in the ammonia storage / release material stored in the tank. The substance (LiCl) constituting the ammonia storage / release material has a storage amount of NH ₃ per gram larger than that of CaCl ₂ and adjusts the pressure of NH ₃ released from the ammonia release pipe at room temperature or a temperature of several tens of degrees or less. The desired amount of NH ₃ is released by adjusting at. Moreover, since the molecular weight of LiCl is 42.4, which is as small as 2/5 compared to the molecular weight 111 of CaCl ₂ , the physique can be reduced with the same amount of NH ₃ occluded.

The adjusting means includes a reserve tank provided in the middle of the ammonia discharge pipe, a pressure sensor for detecting the pressure in the reserve tank, and provided in the middle of the ammonia discharge pipe and provided downstream of the reserve tank. A first adjustment valve that is provided, a second adjustment valve that is provided closer to the tank than the reserve tank, and a control means that controls the opening of the first adjustment valve and the second adjustment valve. It is preferable to provide. According to this configuration, NH ₃ is not directly released (supplied) from the tank in which the ammonia storage / release material is stored to the target location at the target pressure, but is stored in the reserve tank and then the target location. At the target pressure. Therefore, it becomes easy to accurately adjust the pressure of NH _{3 to be} released.

An exhaust gas purification system that solves the above problems includes an exhaust passage through which exhaust gas discharged from an internal combustion engine circulates, a selective reduction catalyst (SCR) provided in the exhaust passage, and stores the NH ₃ and the exhaust passage. An ammonia storage / release device that releases NH ₃ via a pipe line, and a control device that controls the amount of NH ₃ released from the ammonia storage / release device into the exhaust passage in accordance with the amount of NOx in the exhaust passage; The ammonia storage / release device includes a tank for storing LiCl of the ammonia storage / release material as the ammonia storage / release device.

According to this arrangement, the amount of NH ₃ supplied the exhaust passage provided with the selective reduction catalyst (SCR), i.e. amount of released NH ₃ of ammonia absorbing and releasing device to the exhaust passage, NOx quantity in the exhaust passage Therefore, when the exhaust gas in the exhaust passage passes through the selective reduction catalyst (SCR), NOx is appropriately reduced. For example, the NOx amount in the exhaust passage is detected by detecting the NOx amount in the exhaust pipe with a NOx sensor, or by examining the relationship between the load of the internal combustion engine and the NOx amount in the exhaust passage in advance. It is grasped by calculating the amount of NOx in the inside.

According to the present invention, can be carried out by the pressure regulating occluding and releasing NH ₃ at room temperature or several tens of degrees below the temperature, storage amount of NH ₃ per 1g is more than CaCl _2, and NH ₃ in the same amount Physique can be reduced in the occluded state.

The schematic diagram which shows the structure of an exhaust-gas purification system. The block diagram of the apparatus which measures ammonia occlusion amount. The figure which shows the PCT curve in 0 degreeC of LiCl. The figure which shows the PCT curve in 20 degreeC of LiCl. The figure which shows the PCT curve in 40 degreeC of LiCl. The figure which shows the PCT curve in 50 degreeC of LiCl.

Hereinafter, an embodiment of an exhaust gas purification system will be described with reference to FIGS.
As shown in FIG. 1, an exhaust gas purification system 10 includes an exhaust passage 12 through which exhaust gas discharged from a diesel engine 11 as an internal combustion engine flows, and an SCR catalyst (selective reduction catalyst) 13 provided in the exhaust passage 12. And an ammonia storage / release device 14.

  The ammonia storage / release device 14 includes an ammonia supply tank 16 as a tank storing the ammonia storage / release material 15. The ammonia supply tank 16 is provided with a lid portion (not shown), and is configured to open the lid portion and put the ammonia storage / release material 15 into the ammonia supply tank 16. LiCl is used as the ammonia storage / release material 15.

The ammonia supply tank 16 is connected with an ammonia introduction pipe 17 for introducing pressurized NH ₃ into the ammonia supply tank 16, and the ammonia introduction pipe 17 is provided with a valve 17a. The ammonia introduction pipe 17 is used for at least one of introduction of NH _{3 in} a pressurized state and release of NH _{3 in} the tank (ammonia supply tank 16), and constitutes a pipe provided with a valve in the middle. In this embodiment, the piping is used only for introducing NH ₃ under pressure. The ammonia supply tank 16 is connected to the upstream side of the SCR catalyst 13 in the exhaust passage 12 via a supply pipe 18 as an ammonia discharge pipe. The connection of the supply pipe 18 in the ammonia supply tank 16 is preferably arranged such that the ammonia storage / release material 15 does not enter or flow into the supply pipe 18 such as being arranged at the top of the ammonia supply tank 16. A reserve tank 19 is provided in the middle of the supply pipe 18, and an injection nozzle 20 for injecting NH ₃ into the exhaust passage 12 is provided at the end of the supply pipe 18 on the exhaust passage 12 side. An electromagnetic valve V1 as a first adjustment valve is located on the injection nozzle 20 side, that is, downstream from the reserve tank 19 of the supply pipe 18, and an electromagnetic valve as a second adjustment valve is provided on the ammonia supply tank 16 side from the reserve tank 19. V2 is provided. The reserve tank 19 temporarily stores NH ₃ supplied from the ammonia supply tank 16 and supplies it to the injection nozzle 20 at a desired pressure.

A NOx sensor 21 for detecting the amount of NOx in the exhaust gas is arranged on the upstream side of the connection portion with the supply pipe 18 in the exhaust passage 12. The ammonia supply tank 16 is provided with a pressure sensor 22 that detects the pressure in the ammonia supply tank 16 and a temperature sensor 23 that detects the temperature in the ammonia supply tank 16. Further, the reserve tank 19 is provided with a pressure sensor 24 for detecting the pressure of NH ₃ in the reserve tank 19.

The control device 25 that controls the supply amount of NH ₃ to the exhaust passage 12 is electrically connected to the NOx sensor 21, the pressure sensor 22, the temperature sensor 23, and the pressure sensor 24. The control device 25 outputs a control signal to the electromagnetic valves V1 and V2 to adjust the opening degree of the electromagnetic valves V1 and V2. The control device 25 calculates the supply amount of NH ₃ to the exhaust passage 12 based on the detection signal of the NOx sensor 21. In the control device 25, a map or a relational expression indicating the relationship between the NOx concentration obtained from the detection signal of the NOx sensor 21 and the supply amount of NH ₃ to be supplied to the exhaust passage 12 is stored in the memory. Based on this, the supply amount of NH ₃ is calculated. Further, the control device 25 inputs detection signals of the pressure sensor 22, the temperature sensor 23, and the pressure sensor 24, and based on the detection signals and the supply amount of NH ₃ to be supplied to the exhaust passage 12, the electromagnetic valve V1. , V2 is controlled.

The reserve tank 19, the pressure sensor 24, the electromagnetic valves V 1 and V 2, and the control device 25 constitute adjusting means for adjusting the amount of NH ₃ released from the supply pipe 18 to the exhaust passage 12.

Next, LiCl as an ammonia storage / release material will be described.
LiCl has a molecular weight of less than half compared to CaCl ₂ of molecular weight 111 42.4 (38%). Further, LiCl can release all of the occluded NH ₃ at several tens of degrees or less when the pressure of NH ₃ is increased from vacuum to 0.6 MPa. However, CaCl ₂ is occludes NH ₃ in the structure of CaCl _{2 (NH 3) 8} when the pressure of the NH ₃ increased from 0.1MPa to 0.6MPa, 0.1MPa pressure from 0.6MPa After releasing NH ₃ and releasing NH ₃ , the structure becomes CaCl ₂ (NH ₃ ) ₂ , and a part of the occluded NH ₃ remains occluded.

Hereinafter, the embodiment will be described in detail.
The amount of occlusion of NH ₃ in LiCl was measured using a measuring apparatus shown in FIG.
The measuring device 30 includes a reactor 31 and a buffer 32, and the reactor 31 and the buffer 32 are connected via a pipe 33, and a valve 34 is provided in the middle of the pipe 33. A pipe 36 having a valve 35 is connected to the buffer 32. A pressure gauge 37 is provided in the buffer 32 so that the pressure in the buffer 32 can be detected. The reactor 31 is provided with a lid (not shown) so that the sample 38 can be put into the reactor 31 with the lid opened. The volume of the buffer 32 is about 7.2 cm ³ and the volume of the reactor 31 is 30.2 cm ³ . The sample amount was 1 to 2 mmol.

In the test, after putting the sample into the reactor 31, the valve 35 is opened with the valve 34 closed, and a predetermined amount of NH ₃ is stored in the buffer 32. Thereafter, the valve 35 is closed and the valve 34 is opened, so that the sample 38 in the reactor 31 and NH ₃ come into contact with each other, and NH ₃ can be occluded. After NH ₃ stored in the buffer 32 is 0.3 to 0.8 MPa (7.8 to 20.8 mmol) and the valve 34 is opened, the holding time at each pressure is changed between 2 and 30 minutes. The measurement was performed for 2 minutes when the change was large, and 30 minutes when the change was small, and the amount of storage of NH ₃ was calculated from the pressure difference from the blank. This experiment was repeated to perform PCT measurement, and a PCT curve (pressure-composition isothermal curve) was obtained. Further, the pressure was determined storage amount of reversible NH ₃ from storage amount of NH ₃ of 0.1MPa and 0.6 MPa. For comparison, CaCl ₂ was also measured under the same conditions.

The results are shown in FIGS. In FIGS. 2-6, the horizontal axis represents the amount of NH ₃ to the sample 1mol in a state in which the sample is occludes NH ₃ in mol. The vertical axis represents the atmosphere in which the sample exists, that is, the pressure of NH ₃ in the reactor 31.

From the PCT curve of LiCl at 0 ℃ shown in FIG. 3, at 0 ℃, occlusion is carried out a pressure of NH ₃ from a low state, at a pressure of NH ₃ is 0.063MPa, the NH ₃ with respect LiCl1mol 2.5 mol The pressure of NH ₃ is about 0.08 MPa, and NH ₃ is stored to about 3.5 mol with respect to 1 mol of LiCl. Then, the pressure of NH ₃ is 0.13 MPa, and NH ₃ is occluded to about 3.8 mol with respect to 1 mol of LiCl. Finally, the pressure of NH ₃ is 0.42 MPa, and NH ₃ is 4.0 mol with respect to LiCl 1 mol. Occluded to the extent.

From the LiCl PCT curve at 20 ° C. shown in FIG. 4, at 20 ° C., NH ₃ pressure is low, and from 0.02 MPa to NH ₃ is occluded, NH ₃ pressure is about 0.18 MPa, and LiCl 1 mol. On the other hand, NH ₃ is occluded up to about 3.1 mol. And while the pressure of NH ₃ rises from about 0.18 MPa to 0.27 MPa, NH ₃ is occluded to about 4.5 mol with respect to 1 mol of LiCl. Next, while the pressure of NH ₃ rises to 0.6 MPa, NH ₃ is occluded to about 4.6 mol with respect to 1 mol of LiCl.

From the PCT curve of LiCl at 40 ° C. shown in FIG. 5, at 40 ° C., NH ₃ was hardly occluded until the NH ₃ pressure was 0.32 MPa, and when the NH ₃ pressure was higher than about 0.32 MPa, NH ₃ Is started, NH ₃ pressure is 0.4 MPa, and 2 mol of NH ₃ is occluded with respect to 1 mol of LiCl. Then, while the pressure of NH ₃ is increased from 0.4MPa to 0.48 MPa, NH ₃ relative LiCl1mol is occluded to about 3.8 mol, pressure of NH ₃ is increased from 0.48 MPa to 0.8MPa In the meantime, NH ₃ is occluded to about 4.0 mol with respect to 1 mol of LiCl.

From the PCT curve of LiCl at 50 ° C. shown in FIG. 6, at 50 ° C., 0.2 mol of NH ₃ is occluded with respect to 1 mol of LiCl while the pressure of NH ₃ increases from 0 MPa to 0.64 MPa. Then, after the pressure of the NH ₃ reaches 0.64 MPa, while the pressure of NH ₃ is 0.64 MPa, NH ₃ relative LiCl1mol is occluded to 3.2 mol. Thereafter, when NH ₃ pressure rises to 0.7 MPa, NH ₃ is occluded to 4.2 mol with respect to LiCl 1 mol, and when NH ₃ pressure rises to 0.8 MPa, NH ₃ becomes about ₃ mol with respect to LiCl 1 mol. Occludes up to 4.5 mol.

From the results of Examples, in the case of LiCl, the maximum amount of NH ₃ stored with respect to 1 mol of LiCl varies depending on the temperature, and is stored up to about 4.0 mol at 0 ° C. and 40 ° C., and up to about 4.6 mol at 20 ° C. It was found that up to 4.2 mol was occluded at 50 ° C. For LiCl, the structure of the maximum storage state of NH ₃ is at 20 ℃ LiCl _{(NH 3) 4.6,} and becomes 0 at ° C. and _{40 ℃ LiCl (NH 3) 4} . However, unlike CaCl ₂ , all the occluded NH ₃ can be released, so the structure after release becomes LiCl regardless of the temperature.

Table 1 shows the maximum amount of released NH _{3 of the} occlusion body that occludes NH ₃ with respect to LiCl and CaCl ₂ .

However, the density of each occlusion body was 1 cc = 1 g (1 g = 0,909 cc).

From Table 1, when LiCl occludes 4.6 mol of NH ₃ per mol, the released amount per volume of the occlusion body is 0.71 / 0.45 = 1.58≈1.6 times that of CaCl _2. Thus, the release amount per weight of the occlusion body is also 0.65 / 0.41 = 1.59≈1.6 times. Further, when 4 mol of NH ₃ is occluded per mol, the released amount per occluded volume of the occlusion body is 0.68 / 45 = 1.51≈1.5 times that of CaCl ₂ , and the occlusion body weight per occlusion. The discharge amount is also 0.62 / 0.41 = 1.51≈1.5 times.

Also, instead of comparing the occlusion body as a reference, when compared with releasable occluding NH 3 per 1g metal chloride _[g] and releasable occluding NH 3 per metal chloride 1 cc _[g], the following become.

The density of the metal chloride is 2.1 g / cc for LiCl and 2.15 g / cc for CaCl ₂ . For LiCl and CaCl ₂ using this value releasable occluding _NH 3 per 1 mol [g], releasable occluding _NH 3 per 1 g [g] and storage of _NH 3 per 1 cc [g] is calculated for the following It becomes like this.

The releasable storage NH ₃ [g] in the case of CaCl ₂ (8 mol storage and 6 mol release) is 17.03 × 6 = 102.2 g / mol, and the releasable storage NH ₃ [g] per 1 g. Is 102.2 / 110.5 = 0.92 g / g, and the releasable occluded NH ₃ [g] per cc is 0.92 × 2.15 = 1.98 g / cc.

In the case of LiCl, the releasable occluded NH ₃ [g] when 4.6 mol is occluded per mol is 17.03 × 4.6 = 78.3 g / mol. Thus, releasable absorbing _NH 3 [g] per 1g is, 78.3 / 42.4 = 1.85g / g, and the compared to _{CaCl 2, 1.85 / 0.92 = 2.01} ≒ 2 .0 times. Further, releasable absorbing _NH 3 [g] is per 1cc, 1.85 × 2.1 = 3.89g / cc , and the compared to _{CaCl 2, 3.89 / 1.98 = 1.96} ≒ 2 .0 times.

Further, the releasable occluded NH ₃ [g] when 4 mol is occluded per mol is 17.03 × 4 = 68.1 g / mol. Therefore, the releasable occluded NH ₃ [g] per 1 g is 68.1 / 42.4 = 1.61 g / g, which is 1.61 / 0.92 = 1.75≈1 compared to CaCl _2. .8 times. Moreover, the releasable occluded NH ₃ [g] per 1 cc is 1.61 × 2.1 = 3.38 g / cc, which is 3.38 / 1.98 = 1.71≈1 compared to CaCl _2. .7 times.

Next, the operation of the ammonia storage / release device 14 and the exhaust gas purification system 10 configured as described above will be described. When storing NH ₃ in the ammonia supply tank 16, for example, an ammonia cylinder is connected to the ammonia introduction pipe 17 with the valve 17a and the electromagnetic valve V1 closed. Then, the valve 17 a is opened, and a predetermined amount of NH ₃ is introduced into the ammonia supply tank 16. Next, the valve 17a is closed, and the connection between the ammonia introduction pipe 17 and the ammonia cylinder is released. In this state, the exhaust gas purification system 10 becomes operable.

When the exhaust gas purification system 10 is in an operable state, the control device 25 opens the solenoid valve V2 and supplies NH ₃ until the pressure in the reserve tank 19 reaches a preset upper limit pressure. When the pressure is reached, the solenoid valve V2 is closed. When the diesel engine 11 is driven, the control device 25 inputs the detection signal of the NOx sensor 21 and calculates the supply amount of NH ₃ to the exhaust passage 12 based on the detection signal of the NOx sensor 21. Further, the control device 25 inputs the detection signal of the pressure sensor 24 of the reserve tank 19 and calculates the opening degree of the electromagnetic valve V1 from the value and the value of the supply amount of NH ₃ to the exhaust passage 12. The drive command signal is output to the electromagnetic valve V1 so that the opening degree is obtained. As a result, the electromagnetic valve V1 opens at an appropriate opening, and a necessary amount of NH ₃ is supplied from the injection nozzle 20 to the exhaust passage 12, and exhaust gas is exhausted by the SCR catalyst 13 while the exhaust gas passes through the SCR catalyst 13. NOx in the gas is reduced. That is, an appropriate amount of NH ₃ is released into the exhaust passage 12 in accordance with the load of the diesel engine 11, and NOx reduction processing is performed efficiently.

The control device 25 inputs the detection signal of the pressure sensor 24, and when the pressure in the reserve tank 19 decreases to a predetermined lower limit pressure, the control device 25 opens the electromagnetic valve V2 so that the pressure in the reserve tank 19 becomes a preset upper limit pressure. NH ₃ is supplied until

Further, the control device 25 inputs detection signals of the pressure sensor 22 and the temperature sensor 23, and when the remaining NH ₃ amount in the ammonia supply tank 16 becomes equal to or less than a preset amount based on these signals, the diesel engine 11 And NH ₃ is introduced into the ammonia supply tank 16.

LiCl is used as the ammonia storage / release material 15. As described above, the storage amount of NH ₃ per 1 mol of LiCl is 4 mol at 0 ° C. and an NH ₃ pressure of 0.42 MPa, 4.6 mol at 20 ° C. and an NH ₃ pressure of 0.6 MPa, 40 ° C. and NH ₃ The pressure is 4 mol at 0.6 MPa and 4.5 mol at 50 ° C. and the NH ₃ pressure 0.6 MPa. Therefore, if NH ₃ is filled at 20 ° C. with an NH ₃ pressure of 0.6 MPa, the release amount per volume of the occlusion body is 1.6 times that of CaCl ₂ , and the release amount per weight of the occlusion body is also increased. 1.6 times. Further, when 4 mol of NH ₃ is occluded per mol, the released amount per volume of the occluded body is 1.5 times that of CaCl ₂ and the released amount per weight of the occluded body is also 1.5 times. . That is, as compared with the case where CaCl ₂ is used as the ammonia storage / release material 15, the storage amount and release amount of NH ₃ per weight and per volume can be greatly increased.

According to this embodiment, the following effects can be obtained.
(1) The ammonia storage / release device 14 includes an ammonia supply tank 16, LiCl as the ammonia storage / release material 15 stored in the ammonia supply tank 16, an ammonia introduction pipe 17, and a supply pipe 18 as an ammonia release pipe. And adjusting means for adjusting the amount of NH ₃ released from the supply pipe 18. The ammonia introduction pipe 17 is used for introducing NH _{3 in} a pressurized state into the ammonia supply tank 16 and discharging NH ₃ in the ammonia supply tank 16, and is provided with a valve 17 a in the middle. Therefore, it is possible to perform the pressure regulation occluding and releasing NH ₃ at room temperature or several tens of degrees below the temperature in the state storage amount of the NH ₃ per 1g is more than CaCl _2, occluding and NH ₃ in the same amount The physique can be made smaller.

(2) The adjusting means for adjusting the release amount of NH ₃ includes a reserve tank 19 provided in the middle of the supply pipe 18 and a pressure sensor 24 for detecting the pressure in the reserve tank 19. The adjusting means is provided in the middle of the supply pipe 18 and is provided with a first adjusting valve (solenoid valve V1) provided on the downstream side from the reserve tank 19 and a second adjustment valve provided on the ammonia supply tank 16 side from the reserve tank 19. Adjustment valve (solenoid valve V2) and control means (control device 25) for controlling the opening degree of the solenoid valves V1, V2. Then, NH ₃ is not directly discharged (supplied) from the ammonia supply tank 16 in which the ammonia storage / release material 15 is stored to the target location at the target pressure, but is stored in the reserve tank 19 and then the target. Discharge (supply) at the desired pressure. Therefore, it becomes easy to accurately adjust the pressure of NH _{3 to be} released.

(3) The exhaust gas purification system 10 includes an exhaust passage 12 through which exhaust gas discharged from the internal combustion engine (diesel engine 11) flows, a selective reduction catalyst (SCR catalyst 13) provided in the exhaust passage 12, NH ₃ And an ammonia storage / release device 14 that stores NH ₃ in the exhaust passage 12 via a pipe line, and a control device 25. The ammonia storage / release device 14 includes at least an ammonia storage / release material 15 stored in the ammonia supply tank 16, introduction of NH _{3 in} a pressurized state into the ammonia supply tank 16, and release of NH ₃ in the ammonia supply tank 16. Adjustment that adjusts the amount of NH ₃ released from the ammonia discharge pipe (supply pipe 18) that is used on one side and that is provided with a valve in the middle, ammonia discharge pipe (supply pipe 18) that discharges NH ₃ in the ammonia supply tank 16 Means. The ammonia storage / release material 15 is LiCl. Therefore, the amount of NH ₃ supplied to the SCR catalyst 13 provided in the exhaust passage 12, that is, the amount of released NH ₃ of ammonia absorbing and releasing device 14 to the exhaust passage 12 is controlled by the control unit 25, an exhaust passage When the exhaust gas in 12 passes through the SCR catalyst 13, NOx is appropriately reduced.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The ammonia storage / release device 14 may not include the reserve tank 19 and the electromagnetic valve V2, and may supply NH ₃ in the ammonia supply tank 16 to the exhaust passage 12 by opening / closing control of the electromagnetic valve V1.

○ When controlling the supply amount of NH ₃ to the exhaust passage 12, instead of controlling the opening degree of the solenoid valves V1 and V2, the on / off valve is not an adjustable valve as the solenoid valves V1 and V2. It may be used and the supply amount may be controlled by adjusting the opening time.

As a configuration for controlling the supply amount of NH ₃ to the exhaust passage 12, instead of detecting the NOx amount (concentration) in the exhaust gas by the NOx sensor 21, the load of the diesel engine 11 and the necessary supply of NH ₃ The relationship with the amount may be stored in the memory of the control device as a map or a relational expression, and the supply amount of NH ₃ may be adjusted by the load. For example, an operation amount of an accelerator may be used as a load corresponding to the load of the diesel engine 11.

  The exhaust gas purification system 10 may be applied not only to the diesel engine 11 but also to exhaust gas treatment of an internal combustion engine in which NOx to be removed exists, for example, a lean combustion engine of a gasoline engine.

  ○ The exhaust gas purification system 10 is applied to the purification of exhaust gas containing an amount of NOx to be removed, and is not limited to an internal combustion engine used in a moving body such as a vehicle or a ship, but in a factory or the like. You may use for purification | cleaning of exhaust gas, such as a boiler used.

○ emission of NH ₃ for ammonia absorbing and releasing material 15 has been occluded progresses, if there is a need to absorb NH ₃ ammonia absorbing and releasing material 15 again, remove the ammonia absorbing and releasing material 15 in the ammonia supply tank 16, already NH ₃ may be configured to exchange with the ammonia absorbing and releasing material 15 which is occluded. In this case, depending on the size of the ammonia supply tank 16, the ammonia storage / release device 14 can be used in a shorter time than storing NH ₃ . The extracted ammonia occlusion / release material 15 is reused after NH ₃ is occluded in another place.

O Instead of exchanging the material in the ammonia supply tank 16, the ammonia supply tank 16 itself may be exchangeable. In this case, the ammonia supply tank 16 is not provided with the ammonia introduction pipe 17 dedicated to ammonia introduction, but is used for both the introduction of NH ₃ in a pressurized state and the release of NH ₃ in the ammonia supply tank 16. You may provide piping provided with. And this piping is set as the structure which comprises to the intermediate part of the solenoid valve V2 and the reserve tank 19 of the supply pipe | tube 18 in FIG. Then, this pipe may be connected to a supply pipe 18 protruding from the reserve tank 19 through a pipe joint. In this embodiment, the tank (ammonia supply tank 16) is used for both the introduction of NH _{3 in} a pressurized state and the release of NH ₃ in the tank, and a pipe provided with a valve on the way removes the NH ₃ in the tank. It becomes the structure which serves as the ammonia discharge piping to discharge | release. Then, the ammonia storage / release material 15 in the ammonia supply tank 16 is replaced with the ammonia supply tank 16 to be replaced in a state where a predetermined amount of NH ₃ is stored in advance. Even in a configuration in which the ammonia supply tank 16 itself can be replaced, an ammonia introduction pipe 17 dedicated to the introduction of NH ₃ may be provided.

When the storage of NH ₃ in the ○ ammonia supply tank 16, not through the ammonia introduction dedicated ammonia inlet pipe 17, may be store NH ₃ by using the supply tube 18. In this case, a valve 17a is disposed between the electromagnetic valve V2 and the ammonia supply tank 16, and the supply pipe 18 can be branched between the electromagnetic valve V2 and the valve 17a. Alternatively, a connection port to which an ammonia cylinder can be connected is provided at the same position, and the solenoid valve V2 and the valve 17a are controlled so that NH ₃ can be introduced into the ammonia supply tank 16. In this case, when NH ₃ is supplied from the ammonia supply tank 16 to the reserve tank 19, control is performed so that the electromagnetic valve V2 and the valve 17a have the same behavior.

○ The ammonia supply tank 16 may be heated. When the amount of NH ₃ occluded in the ammonia occlusion / release material 15 decreases, it becomes easier to release by heating, and the occluded NH ₃ can be used without waste. However, when the heating temperature is set to several tens of degrees or less unlike the conventional ammonia occlusion / release material, power consumption is reduced even if an electric heater is used for heating.

○ The upper limit of pressure when the ammonia absorbing and releasing material 15 to absorb NH ₃ is not limited to 0.6 MPa, is modified by the breakdown voltage of the tank. However, NH ₃ liquefies (liquid ammonia) at 0.9 MPa or more. Compared to storing NH ₃ in liquid ammonia, the advantage of the ammonia storage / release material of the present invention is that it has a higher storage capacity at a pressure lower than that of liquid ammonia, and in the unlikely event of tank damage, Ammonia evaporates all at once, but when the occlusion / release material of the present invention is used, it can be said that transpiration is slow and relatively safe.

  The adjusting means is not limited to the configuration including the reserve tank 19, the pressure sensor 24, the electromagnetic valves V 1 and V 2, and the control device 25. For example, the reserve tank 19, the electromagnetic valve V1 (or V2), and the pressure sensor 24 may be omitted, and the opening degree of the electromagnetic valve V2 (or V1) may be controlled by the pressure sensor 22 in the ammonia supply tank 16. .

  DESCRIPTION OF SYMBOLS 12 ... Exhaust passage, 14 ... Ammonia storage-release apparatus, 15 ... Ammonia storage-release material, 17a, 34, 35 ... Valve, 19 ... Reserve tank, 22, 24 ... Pressure sensor, 25 ... Control apparatus, 33, 36 ... Piping.

Claims (3)

A tank for storing ammonia storage / release material;
Ammonia storage / release material stored in the tank;
A pipe which is used for at least one of introduction of NH ₃ in a pressurized state and release of NH ₃ in the tank, and a valve provided in the middle;
An ammonia release pipe for releasing NH ₃ in the tank;
Adjusting means for adjusting the amount of NH ₃ released from the ammonia releasing pipe,
The ammonia storage / release device, wherein the ammonia storage / release material is LiCl.   The adjusting means includes a reserve tank provided in the middle of the ammonia discharge pipe, a pressure sensor for detecting the pressure in the reserve tank, and provided in the middle of the ammonia discharge pipe and provided downstream of the reserve tank. A first adjustment valve that is provided, a second adjustment valve that is provided closer to the tank than the reserve tank, and a control means that controls the opening of the first adjustment valve and the second adjustment valve. The ammonia storage-release apparatus of Claim 1 provided. An exhaust passage through which exhaust gas discharged from the internal combustion engine flows;
A selective reduction catalyst (SCR) provided in the exhaust passage;
And ammonia absorbing and releasing device that releases NH ₃ and NH ₃ via line to the exhaust passage as well as storage,
A control device that controls the amount of NH ₃ released from the ammonia storage / release device into the exhaust passage in response to the amount of NOx in the exhaust passage;
An exhaust gas purification system comprising the ammonia storage / release device according to claim 1 or 2 as the ammonia storage / release device.