JPH0810550A - Method for recovering latent heat from waste gas and device therefor - Google Patents

Abstract

PURPOSE:To efficiently recover the latent heat and sensible heat of steam from a waste combustion gas by using the steam absorptivity of the adsorbent and moisture absorbent and the heat of reaction in absorption. CONSTITUTION:This device consists of a waste gas branching means 2 to introduce a waste gas into a heat recovery system 3 from a flue 1, a means 6 in which the adsorption tower 52 and moisture absorbing tower 52 for recovering steam from the waste gas on the downstream side of the system 3 and discharging the steam on the upstream side are provided in a waste gas passage, generating a waste gas having a high content of steam and condensing the waste gas to recover latent heat, a means for recovering the sensible heat of the waste gas increased in temp. by the heat generated in adsorption and absorption reactions. The latent heat recovering means 6 and the sensible heat recovering means 7 are continuously operated to obtain a utilizable heat recovered from the waste gas contg. steam which has been discarded so far, and energy is effectively utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering latent heat of exhaust gas containing water vapor and an apparatus used for the method, and particularly to combustion of liquefied natural gas (LNG), coal or petroleum as a fuel for thermal power plants or factories. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a latent heat recovery method and apparatus for off-gas discharged in gas, chemical process, and the like.

[0002]

2. Description of the Related Art Exhaust heat that can be effectively used in factories and power plants is recovered by using heat recovery devices such as heat exchangers and reheat boilers, and used for preheating of raw materials. These exhaust heats were generally used by recovering the exhaust heat of 300 ° C or higher.

However, recently, against the background of exhaustion of energy resources and environmental problems, various uses of exhaust heat at 300 ° C. or lower, which have not been used conventionally in terms of cost and technology, have been studied. Among these, there is an example in which hot wastewater at 30 to 40 ° C is used as it is for purposes such as aquaculture, and is also used as a heat source for a heat pump for hot water supply.

However, the latent heat of condensation contained in the steam contained in the combustion exhaust gas at a temperature of 150 ° C. causes a problem such as corrosion of the heat exchanger, so that it is discharged from an exhaust facility such as a chimney in an almost unused state. Is the current situation.
However, it is disclosed in Utility Model Publication No. 2-25471 that the water produced by the condensation of water vapor in the exhaust gas is used as a supplementary water source for a wet flue gas desulfurization device provided in a flue.

This is because the water vapor in the exhaust gas provided in the latter stage of the desulfurization device is absorbed and removed by using an adsorbent, and the water absorbed by the adsorbent is discharged upstream of the desulfurization device to desulfurize the exhaust gas with a high water vapor concentration. By sending the water to the device, it is possible to suppress the generation of water vapor from the absorbing liquid of the desulfurization device and to collect the water by absorbing the excess water vapor contained in the exhaust gas into the absorbing liquid.

[0006]

As described above, the temperature is 150 ° C.
No latent heat recovery from exhaust gas containing a level of water vapor has been carried out, and there is only an idea of recovering and using water when a wet desulfurization device is installed in a flue which is a flow path of exhaust gas.

The present invention was not used as a latent heat recovery source 15
The objective is to efficiently condense steam from exhaust gas containing 0 ° C steam to recover latent heat and at the same time obtain recovered heat at a temperature level that can be used as a heat source for hot water supply or an absorption refrigerator.

[0008]

In order to solve the above-mentioned problems, in the present invention, a branching means for branching an amount of exhaust gas necessary for recovering latent heat from exhaust gas to a flue of an exhaust gas exhaust facility and guiding it to a latent heat recovery system. And a heat recovery system is installed in the branched exhaust gas flow path. In the exhaust gas flow path of this heat recovery system, means for guiding the steam in the downstream exhaust gas to the upstream exhaust gas is provided, and the latent heat is recovered by condensing steam from the exhaust gas having an increased steam concentration in the upstream portion.

In the present invention, as a concrete means for introducing the water vapor in the downstream exhaust gas to the upstream exhaust gas, a water vapor adsorbing section and a desorbing section by an adsorbent are provided in the branched exhaust gas flow path,
There is a method in which a means for circulating the adsorbent by a moving layer is provided between the adsorbing section and the desorbing section, and the adsorbent that adsorbs water vapor is moved to the upstream section to be desorbed in the exhaust gas flow channel downstream.

Further, an adsorption / desorption tower for adsorbing / desorbing water vapor is provided in the branched exhaust gas passage, the branched exhaust gas is guided to the desorption process of the adsorption / desorption tower, and latent heat recovery means is provided in the exhaust gas passage after the desorption process. , An adsorption step after the latent heat recovery means,
By providing sensible heat recovery means in the latter stage of the adsorption step, by means of introducing the branched exhaust gas by alternately switching to the adsorption tower and the desorption tower,
There is a method of performing a thermal swing utilizing the temperature difference between the inlet temperature and the outlet temperature of the exhaust gas introduced into the heat recovery system.

In these methods, the latent heat recovery means and the sensible heat recovery means are continuously used in order to further raise the temperature of the recovered heat. Here, as the adsorbent, zeolite, alumina, or the like, which is suitable for adsorption / desorption of water vapor, is used.

Further, as another specific means, a reaction tower is provided in which a hygroscopic agent such as an aqueous solution of lithium bromide and exhaust gas are brought into contact with a branched exhaust gas flow path to absorb and dehumidify (regenerate) water vapor in the exhaust gas, The branched exhaust gas is guided to the dehumidification tower, and a latent heat recovery unit is installed in the exhaust gas flow path after the dehumidification process of the water vapor from the hygroscopic agent. Sensible heat recovery means is provided to absorb and
Utilizing the temperature difference between the inlet temperature and the outlet temperature of the exhaust gas introduced into the heat recovery system while circulating the hygroscopic agent between the dehumidifying towers,
By changing moisture absorption / dehumidification.

[0013]

As described above, the adsorbent filled in the adsorption / desorption tower provided in the branched exhaust gas passage and the hygroscopic agent in the reaction tower are
By contacting with the exhaust gas, depending on the temperature level of the contacting exhaust gas, it acts to adsorb or absorb the water vapor content in the exhaust gas, or conversely release the water vapor adsorbed or absorbed by the adsorbent or hygroscopic agent into the exhaust gas. . This action is carried out by using the temperature difference between the exhaust gas temperature level of 150 ° C at the inlet of the heat recovery system and the temperature level of 50 ° C at which the water vapor in the exhaust gas is saturated and condensed, to cause adsorption or desorption change. Less than,
The operation will be described along the flow of the exhaust gas, taking the case of using an adsorbent as an example.

Regarding the water vapor adsorption characteristics of the adsorbent, generally, the lower the temperature, the more water is adsorbed per unit mass of the adsorbent, and the higher the temperature, the lower the adsorption amount. Further, the adsorption heat is transferred when the adsorption / desorption changes. That is, when water vapor is adsorbed, heat is generated, and conversely, when water vapor is desorbed (released), ambient heat is absorbed.

Therefore, when the exhaust gas at the 150 ° C. level branched from the exhaust equipment is brought into contact with the adsorbent that has adsorbed water vapor at a lower temperature, the adsorbent is heated by the exhaust gas passing through the tower and the temperature rises. Therefore, the adsorption property is lowered, and the adsorbed water content is released into the exhaust gas.

In this case, the exhaust gas entering the tower at 150 ° C.
The temperature decreases due to the heating of the adsorbent and the heat absorption due to desorption, and the outlet temperature decreases to about 80 ° C. At this time, at the outlet of the tower, the water concentration in the exhaust gas increases from the inlet. For this reason, the saturation temperature of the exhaust gas becomes higher than that of the normal exhaust gas, and the latent heat recovery means provided in the latter stage of the column that performs this desorption action acts to cool the exhaust gas and easily condense the water vapor contained therein.

The exhaust gas discharged from the latent heat recovery means becomes saturated at about 50 ° C. because water vapor is condensed and removed to some extent, and at this temperature, it is led to a column for adsorbing water vapor, which is provided in the subsequent stage of the flow path. Here, water vapor is adsorbed at the 50 ° C. level from the exhaust gas having a reduced water content to generate heat. As a result, the temperature of the adsorption tower rises as the adsorption of water vapor progresses, and the exhaust gas passing therethrough is heated while being dehumidified.

Therefore, at the outlet of the adsorption tower, the exhaust gas is about 12
The dry gas is heated to 0 ° C. In addition, this 120
Approximately 70 due to the latent heat of exhaust gas and steam condensation reheated to ℃
By exchanging heat with the hot water that reached ℃, the heat can be recovered as hot water close to 100 ℃ due to the sensible heat of the exhaust gas. These processes absorb and absorb the adsorbent while moving between the adsorption and desorption parts.
By the method of desorption or the method of switching the exhaust gas passage within the adsorption capacity of the adsorption tower, continuous heat recovery can be performed by utilizing the characteristics of the adsorbent. These actions are
The same operation can be performed by using a hygroscopic agent instead of the adsorbent.

In the above operation, when a heat recovery temperature of 120 ° C. is not required, water vapor is adsorbed by providing a cooling means such as a heat exchanger in a portion for carrying out the adsorption or moisture absorption step where reaction heat is generated. You can increase the amount,
Water vapor can be moved more efficiently.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 shows a system configuration showing an embodiment of the present invention along the flow of exhaust gas. The flue 1 of the exhaust facility is provided with a branching means 2 for the exhaust gas 9, for example, a damper, and branches and introduces the amount of exhaust gas required for latent heat recovery into the heat recovery system 3.

The heat recovery system 3 comprises a particulate adsorbent 4
Two adsorption towers 51, A and B, respectively filled with 1, 42,
52 between the exhaust gas 9 and the cooling liquid flowing through the pipe 61, and the latent heat recovery means 6 which is a heat exchanger for exchanging heat between the exhaust gas 9 and the cooling liquid flowing through the pipe 71. The sensible heat recovery means 7 is a heat exchanger for exchanging heat. The coagulated water generated when the exhaust gas is cooled in the latent heat recovery means 6 is recovered from the pipe 10 as recovered water. These devices are connected by a flow path indicated by an arrow as shown by a solid line and a broken line in the figure.

The flow path shown by the solid line is the adsorption tower (A).
51 shows the flow of the exhaust gas when the desorption process is used and the adsorption tower (B) 52 is used as the adsorption process, and the broken line indicates the reverse when the adsorption tower B52 is used as the desorption process and the adsorption tower A51 is used as the adsorption process. The process and the part where the flow path is changed are shown.

Switching valves 81, 82, 83, 84, 85, 86, 87, 8 for switching the exhaust gas passages are provided at the respective branch points.
Although not shown in the figure, the switching timing can be arbitrarily set by using a sequencer, and the adsorption of water vapor can be controlled by the characteristics of the adsorbent filling the adsorption towers 51 and 52 and the flowing gas flow rate. -Switching is done at the optimum timing for attachment / detachment.

The operation of this embodiment will be described below in accordance with the flow of exhaust gas. In the figure, the lowercase alphabet a-
j is for explaining the flow of the exhaust gas. The present embodiment is intended for the recovery of latent heat from combustion exhaust gas discharged from a thermal power plant that uses liquefied natural gas containing water vapor of about 10 to 15% as the exhaust gas.

As shown in the drawing, when the flue 1 is closed by the damper 2, the total amount of the exhaust gas 9 becomes the target of latent heat recovery. The exhaust gas 9 of about 150 ° C. branched from the flue 1 contains moisture of 0.086 in terms of wetness, and is guided to the heat recovery system 3 from the point a. The exhaust gas 9 introduced into the heat recovery system 3 from the point a is an adsorption tower (A) 51 that performs a desorption process via the flow path switching valve 81 located at the point b.
Be led to.

A flow path switching valve 82 for changing the flow of the exhaust gas 9 when the adsorption tower 51 is used as an adsorption step after the desorption step is provided at the entrance and exit of the adsorption tower (A) 51. Exhaust gas 9 entering the adsorption tower A51 from point c
Heats the adsorption tower A51 at a temperature of 150 ° C. to release the water vapor adsorbed by the adsorbent 41 filled in the tower.

Therefore, the water concentration (water vapor concentration) in the exhaust gas gradually increases at the outlet d of the adsorption tower (A) 51, and the wetness reaches 0.116 at the maximum point. The exhaust gas temperature at this time becomes 80 ° C. and comes out from d. The exhaust gas 9 is then guided to the inlet point e of the latent heat recovery means 6, and internally exchanges heat with the cooling water of 45 ° C. that enters from the point k through the pipe line 61 to condense excess water in the exhaust gas. Then, the recovered water 10 is taken out.

As a result, the temperature of the cooling water rises due to the latent heat of condensation of the exhaust gas 9 and is raised to 75 ° C. at the outlet. On the other hand, the exhaust gas which has lost a part of the water content as condensed water is exhaust gas temperature 50 at the exit point f of the latent heat recovery means 6.
C, wetness becomes 0.086. This exhaust gas is further guided to the inlet point g of the adsorption tower B52 and enters the adsorption step.

In the adsorption tower 52, the water remaining in the exhaust gas is adsorbed by the adsorbent 42 filled in the tower to generate heat, and the exhaust gas passing through the adsorbent 42 is simultaneously removed from the adsorbent 42. It reacts and is heated. As a result, at the exit point h of the adsorption tower 52, the temperature is 120 ° C. and the wetness is 0.00
It becomes the exhaust gas of 56.

In this process, the exhaust gas 9 is in a state where moisture is removed to some extent, and since it has a high temperature close to the state before removing moisture, it is guided to the inlet point i of the sensible heat recovery means 7 and its sensible heat is removed. To use. On the other hand, the latent heat recovery means 6
The sensible heat recovery means 7 for the cooling water heated to ℃ from the point m
By bringing the temperature to 1 and exchanging heat with the exhaust gas 9 having a high temperature again, hot water of about 100 ° C. is obtained.

As a result, the flue gas 9 is deprived of sensible heat up to 80 ° C. and its temperature is lowered, but since it contains a small amount of water, it is discharged to the position j downstream of the damper of the flue 1 without producing white smoke. Diffuse exhaust from the chimney as usual. Through the above steps, the exhaust gas 9 can be made to flow until the water vapor adsorption capacity of the adsorption tower 52 is saturated, but at the stage when the adsorption capacity is saturated, the introduction path of the exhaust gas 9 is reversed from the previous adsorption step and desorption step. The flow path switching valves 81 to 88 are operated so that the flow of the exhaust gas is switched.

As a result, the exhaust gas 9 flowing from the point a to the points b and c in the heat recovery system 3 is discharged from the points a to b,
The flow changes in the direction indicated by h and the broken line, and first the adsorption tower B5
Guided to 2. In this adsorption tower 52, 5
The temperature distribution is between 0 ° C and 120 ° C, and it contains water vapor adsorbed according to the adsorption characteristics in this temperature range. Adsorbed water is released similarly to the desorption process in the tower A51.

The latent heat of the exhaust gas having the increased water content is recovered along the route of points g, e, f. Point d,
In the routes c and i, the water content in the exhaust gas is newly absorbed by the adsorbent because the water content in the adsorbent has been removed by the previous desorption process. For this reason, the water content of the exhaust gas decreases, but at the same time, the temperature rises due to the heat of adsorption.

By exchanging heat between the heated exhaust gas and the cooling water that has previously passed through the latent heat recovery means 6, the point n
Recovery heat that can be effectively used is obtained from the exhaust gas 9 at the point j.
Returned to the flue. Latent heat and sensible heat recovery means 71, 6
The hot water of 100 ° C produced by No. 1 is reused as a hot water supply and a heat source for the absorption refrigerator.

As described above, by repeating the adsorption and desorption steps while switching the flow path of the exhaust gas to be introduced into the heat recovery system 3, the latent heat and sensible heat of the exhaust gas can be recovered at the same time, and hot water supply and hot water supply can be performed. It is possible to obtain heat of 100 ° C. level suitable for driving the absorption refrigerator.

FIG. 2 shows another embodiment of the latent heat recovery system adopting the adsorption tower system. The difference from the first embodiment is that it has a function of exchanging the adsorption towers A, B 51, 52. The heat of adsorption generated during the adsorption process to the heat exchangers 111, 1
This is what is excluded by 12. In this embodiment, as the cooling source at this time, the recovered water 1 obtained by the latent heat recovery means 6 is used.
Although 0 is used, other cooling sources may be used. In this embodiment, the operation principle of latent heat recovery is the same as that of the first embodiment, and therefore only the parts peculiar to this embodiment will be described below.

In this embodiment, attention was paid to the temperature characteristics of the adsorbents 41 and 42 in order to increase the amount of water vapor recovery and increase the recovery latent heat. That is, as the temperature dependence of the adsorbents 41 and 42, the higher the operating temperature is, the smaller the adsorption capacity is. Therefore, in order to increase the water adsorption capacity by using the same amount of the adsorbent, the adsorbent is used at a low temperature. Is effective.

Therefore, the adsorption tower 5 in the state of the adsorption step
Cooling water to 1 or 52, p, q, r paths or p, s,
Supply and cool through the route of t. As a result, a larger amount of water can be adsorbed and released in the desorption process as compared with the case without a cooling function, so that the latent heat recovery amount can be increased.

However, since the temperature of the exhaust gas returned to the flue after the adsorption step becomes low, it cannot be used to sufficiently raise the temperature of the cooling water whose latent heat is recovered in the latent heat recovery step by the sensible heat recovery means. For this reason, in this embodiment, the sensible heat recovery means 7 is arranged at the subsequent stage (downstream) of the exhaust gas branching means 2 of the flue 1, and the sensible heat of the exhaust gas discharged without passing through the branching means 2 is used. However, it is configured to obtain high-temperature recovery heat.
In this embodiment, the amount of exhaust gas branched for recovering latent heat is limited, but there is an effect that the adsorption tower can be downsized.

In the examples using the adsorbents described above, the adsorption tower filled with the particulate adsorbent was described as an example, but in order to reduce the pressure loss of the adsorption tower and increase the reaction surface area of the adsorbent, a honeycomb type or the like is used. The adsorbent formed can be used.

FIG. 3 shows a water vapor adsorption section 20 and a desorption section 21.
FIG. 3 is a flow chart showing an example in which the adsorbent is circulated in the moving bed. The numbers enclosed by circles in the figure are those in which the exhaust gas inlet is set to 0 and the outlet 4 is sequentially attached along the flow path in order to show the state of the exhaust gas at each part. Here, T is the exhaust gas temperature (° C), and x is the wetness (kg / kg-
drygas), i represents the enthalpy (kcal / kg), and W represents the water content (t / h) in the exhaust gas.

The system flow of this embodiment is 600 MW.
This is the case where the exhaust gas of a power station of the class is used as the target, and the balance is shown when the adsorption capacity of the adsorbent is 10 g / 100 g-the zeolite of the agent is used. Moisture initially contained in the exhaust gas branched from the flue at 187 t / h increased to 252 t / h when passing through the desorption section 21, which was the same as that at the inlet after water recovery.
It becomes 87 t / h, which absorbs water in the adsorbing part 20 and moves to the desorbing part. Therefore, after passing through the adsorbing part, it is reduced to 121 t / h and returned to the flue.

During this time, the latent heat recovery means 6 uses cooling water of 45 ° C., recovers water of 65 t / h and 56 Gcal / h.
The latent heat of 24 Gcal / h is recovered by guiding the cooling water to the sensible heat recovery means. At this time, the moving amount v of the adsorbent is 1200 t / h, and the column volume of the reaction section requires 2000 m ³ / h. As a result,
In this embodiment, the latent heat and the sensible heat are combined to 80 Gcal / h.
Is recovered, which makes up 34% of the heat retained by the exhaust gas. Also,
As an incidental effect, 41% of water is recovered at the same time.

FIG. 4 shows a method of using a hygroscopic agent such as lithium bromide as a means for guiding the water vapor in the exhaust gas of the adsorption tower located downstream in the exhaust gas passage in the heat recovery system 3 to the exhaust gas located upstream. Is shown. By using this means, as in the case of using the previous adsorbent,
The latent heat can be efficiently recovered by condensing the water vapor from the exhaust gas having the increased water concentration in the upstream portion of the latent heat recovery means.

The configuration and operation of this embodiment will be described below with reference to the drawings. The present embodiment is characterized in that the exhaust gas passages need not be switched as in the above-described embodiment, and continuous treatment is possible. The system is a moisture absorbent 19
Centering on the reaction tower 12 for moisture absorption for contacting the exhaust gas 9 with the exhaust gas 9, and the circulation means 14 for the hygroscopic agent for moving the hygroscopic agent between these reaction towers. The latent heat recovery means 6 is provided in the exhaust gas flow path between the moisture absorption reaction tower 12 and the sensible heat recovery means 7 at the subsequent stage of the moisture absorption reaction tower 12.

The exhaust gas 9 is led from the flue 1 to the regeneration reaction tower 13 of the heat recovery system 3 in the order of points a and b. At the same time, the hygroscopic agent 19 collected in the hygroscopic reaction column 12 is supplied to the reaction tower 13 by the pumps 141 and 142 at the points q and r, and the hygroscopic agent 19 directly transfers heat by the gas-liquid contact with the exhaust gas. Be done. As a result, the hygroscopic agent is heated by the exhaust gas at 150 ° C., the contained moisture is evaporated, and the concentrated hygroscopic agent 19 is returned to the moisture absorption reaction tower 12 through the route of points s and p.

On the other hand, the exhaust gas 9 contains the water vaporized from the hygroscopic agent 19 to increase the water concentration and is guided to the latent heat recovery means 6 through the route of points c and d, as in the embodiment using the adsorbent shown in FIG. The latent heat is recovered and the recovered water 10 is obtained. The exhaust gas, the water content of which has been reduced by the latent heat recovery means 6, is guided to the moisture absorption reaction tower 12 through the paths of points e and f, and comes into contact with the concentrated hygroscopic agent in the regeneration reaction tower 13 to absorb the water content in the exhaust gas.

In this case, absorption heat is generated as in the adsorption reaction step, is transferred to the exhaust gas, and the exhaust gas is guided from the moisture absorption tower 12 to the sensible heat recovery means 7 in a state of being heated. In the sensible heat recovery means 7, since the cooling water from which the latent heat has been recovered is guided through the route of the points k, l and m, high temperature recovered heat can be obtained as in the embodiment using the adsorbent.

In the present embodiment, since the liquid hygroscopic agent is used to move the water vapor and raise the temperature of the exhaust gas due to the heat of reaction, a simple conveying means such as a pump is used to form the hygroscopic agent circulation system. Since the object of the invention can be achieved, the system configuration becomes very simple. However, since the method of contacting the hygroscopic agent and the exhaust gas affects the efficiency of heat recovery, it is necessary to spray the hygroscopic agent into contact with the exhaust gas, or to place a large number of current-changing plates in the reaction tower and to flow down the hygroscopic agent. It is necessary to improve the contact of exhaust gas.

FIG. 5 shows an example of a system configuration for circulating and using the adsorbent without switching the exhaust gas passage. This is a structure in which the adsorbent 4 is installed on the outer peripheral portion of the double cylindrical container 16 and the adsorbent is rotationally moved between the desorption reaction tower 17 and the adsorption reaction tower 18 by a drive source 15 such as a motor. System. With such a structure, the adsorbent can be handled as in the previous embodiment in which the hygroscopic agent is circulated, so that the exhaust gas 9 introduced from the flue 1 recovers latent heat and sensible heat without switching the flow path. It can be returned to the flue 1.

In the above embodiments, the case where only one adsorption tower or hygroscopic tower is installed in the exhaust gas passage branched from the flue has been described. It is also possible to provide. For example, FIG. 6 shows a configuration when the embodiment shown in FIG. 5 is configured in two stages. In this case, the temperature level of the recovered heat can be increased by sensible heat recovery in two stages.

FIG. 7 shows an embodiment in which the generated 0 ° C. level cold heat is applied to a refrigerated warehouse in combination with absorption refrigeration using recovered heat as a heat source. This embodiment has 25
This is an example for an exhaust heat recovery system of a MW thermal power plant. The means for moving water vapor in the exhaust gas is configured to rotate and move the adsorbent as in the embodiment of FIG.
Only water is collected, and the collected water is used as water supply for the boiler. The sensible heat is collected in two stages in the flow path of the adsorption part.
Recovered as steam at ℃ and used directly as a heat source for cold heat generation system. As a result, the heat recovery rate becomes 30%, which is lower than that in the example shown in FIG. 3, but cold heat with a high utility value can be directly produced from waste heat.

[0053]

According to the present invention, exhaust gas containing water vapor discharged from a factory or a power plant, which has been conventionally discharged without being used, is heated to 100 ° C. which serves as a drive source for hot water supply or an absorption refrigerator.
A level of recovered heat can be efficiently obtained, and energy can be effectively used.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a latent heat recovery system using an adsorbent.

FIG. 2 is also a system configuration diagram of a latent heat recovery system in which an adsorption tower is provided with a cooling function.

FIG. 3 is a flow chart of a moving bed type latent heat recovery system.

FIG. 4 is a system configuration diagram of a latent heat recovery system using a hygroscopic agent.

FIG. 5 is a system configuration diagram of an adsorbent transfer type latent heat recovery system.

FIG. 6 is a system configuration diagram of a latent heat recovery system using a two-stage adsorbent.

FIG. 7 is a configuration diagram of a cold heat generation type latent heat recovery system.

[Explanation of symbols]

1 ... Flue, 2 ... Exhaust gas branching means, 3 ... Heat recovery system,
4 ... Adsorbent, 5 ... Adsorption tower, 6 ... Latent heat recovery means, 7 ... Sensible heat recovery means, 8 ... Exhaust gas flow path switching means, 111 ... Heat exchanger, 112 ... Heat exchanger, 12 ... Moisture absorption reaction tower, 13 ...
Regeneration reaction tower, 19 ... Hygroscopic agent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryokichi Yamada 7-1-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Yasuo Ozeki 7-chome, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Incorporated company Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Norio Arashi 7-1-1, Omika-cho, Hitachi City, Hitachi, Ibaraki Prefecture Incorporated Hitachi Ltd. Hitachi Research Institute (72) Hiroshi Miyadera Mika Oita, Ibaraki Prefecture 7-1-1, Machi, Hitachi Co., Ltd. Hitachi Research Laboratory

Claims (17)

[Claims] 1. A desorption step for increasing the water vapor concentration of the exhaust gas by contacting an exhaust gas containing water vapor with an adsorbent that adsorbs water to release the water content in the adsorbent, and an increase in the water vapor concentration through the desorption step. The obtained exhaust gas is cooled by a refrigerant, a condensation step of condensing and removing water vapor in the exhaust gas to extract latent heat, and an adsorption step of adsorbing residual moisture of the exhaust gas that has undergone the condensation step with an adsorbent, in the adsorption step. Using an adsorbent that has adsorbed water in the desorption process,
A method for recovering latent heat from exhaust gas, characterized in that the refrigerant used in the condensation step is used as a heat source for another device. 2. The method according to claim 1, wherein in the adsorption step, the exhaust gas is heated by the heat of reaction between moisture in the exhaust gas and the adsorbent, and the exhaust gas heats the refrigerant used in the condensation step. A method of recovering latent heat from exhaust gas. 3. The method for recovering latent heat from exhaust gas according to claim 1, wherein the adsorbent that has released water in the desorption step is used in the adsorption step. 4. The exhaust gas according to claim 1, wherein the adsorbent used in the adsorption step is a mixture of zeolite, alumina, activated alumina and silica gel, singly or in combination of plural kinds. Of recovering latent heat from water. 5. A first reaction tower for increasing the water vapor concentration of the exhaust gas by bringing the exhaust gas containing water vapor into contact with the adsorbent to release water in the adsorbent, and cooling the exhaust gas with a refrigerant to cool the exhaust gas. A latent heat recovery tower for condensing and removing water vapor to extract latent heat; and a second reaction tower for adsorbing residual water of the exhaust gas passing through the latent heat recovery tower with an adsorbent, and adsorbing water in the second reaction tower. The first adsorbent
A device for recovering latent heat from exhaust gas, comprising a device which is used in the reaction tower of 1) and uses the refrigerant used in the latent heat recovery tower as a heat source of another device. 6. The heat exchanger according to claim 5, wherein the exhaust gas is heated in the second reaction tower by the heat of reaction between the water in the exhaust gas and the adsorbent, and the refrigerant used in the latent heat recovery tower is heated by the exhaust gas. A device for recovering latent heat from exhaust gas. 7. The apparatus for recovering latent heat from exhaust gas according to claim 5, wherein the adsorbent used in the first reaction tower and releasing water is used in the second reaction tower. 8. The latent heat is recovered from the exhaust gas according to claim 5, wherein the adsorbent used in the second reaction tower is one or a mixture of zeolite, alumina, activated alumina and silica gel. Device to do. 9. A branching device for branching part or all of exhaust gas containing water vapor from a flue, contacting the exhaust gas with an adsorbent to release water in the adsorbent, and increasing the water vapor concentration of the exhaust gas. A first reaction tower, a latent heat recovery tower that cools the exhaust gas that has passed through the first reaction tower with a refrigerant, condenses and removes water vapor in the exhaust gas to extract latent heat, and a residual water content of the exhaust gas that has passed through the latent heat recovery tower. Between the second reaction tower adsorbed by an adsorbent, the inlet side of the first or second reaction tower and the flue, the outlet side of the first and second reaction towers, the inlet of the latent heat recovery tower And a plurality of switching valves respectively arranged on the outlet side, and used in the second reaction tower,
An adsorbent that adsorbs water is used in the first reaction tower, and a device that uses the refrigerant used in the latent heat recovery tower as a heat source of another device is provided. In the first step, the exhaust gas branched from the flue is used. The first reaction tower, the latent heat recovery device, and the second reaction tower are circulated in this order, and in the second step, the exhaust gas branched from the flue is the second reaction tower, the latent heat recovery device, and the first reaction tower in that order. An apparatus for recovering latent heat from exhaust gas, characterized in that the switching valve is controlled so as to circulate, and the first and second steps are alternately executed. 10. The sensible heat for heating the refrigerant used in the latent heat recovery device by the exhaust gas heated by the heat of reaction between the water in the exhaust gas and the adsorbent in the second reaction tower according to claim 9. An apparatus for recovering latent heat from exhaust gas, characterized by comprising recovery means. 11. The heat exchanger according to claim 10, wherein a heat exchanger is provided in each of the first and second reaction towers.
The apparatus for recovering latent heat from exhaust gas, characterized in that the reaction tower in the adsorption step of the reaction tower is cooled. 12. First and second reaction towers that dehumidify or absorb water vapor in the exhaust gas by bringing the exhaust gas containing water vapor into contact with a liquid hygroscopic agent, and the water vapor concentration via the first reaction tower. Of the exhaust gas whose temperature has been increased by a refrigerant to condense and remove water vapor contained in the exhaust gas to extract latent heat, and a circulation device for circulating the liquid hygroscopic agent to the first and second reaction towers And a device that uses the refrigerant used in the latent heat recovery tower as a heat source for another device, the liquid hygroscopic agent adsorbs the residual water content of the exhaust gas in the second reaction tower and adsorbs it in the first reaction tower. A device for recovering latent heat from exhaust gas, which is characterized by releasing water. 13. A first reaction tower for increasing the water vapor concentration of the exhaust gas by contacting an exhaust gas containing water vapor with an adsorbent to release the water content in the adsorbent, and a water vapor concentration via the first reaction tower. Of the exhaust gas whose temperature has been increased by a refrigerant to remove latent water by condensing and removing water vapor in the exhaust gas, and a second reaction tower for adsorbing residual water in the exhaust gas passing through the latent heat recovery tower with an adsorbent And a plurality of packed towers filled with an adsorbent, and a rotary moving device that supports the plurality of packed towers so as to be rotatably movable between the first and second reaction towers. When the amount of adsorbed water reaches a predetermined amount, the packed column is rotated, and the adsorbent that has adsorbed the water in the second reaction tower is used in the first reaction tower and the water in the first reaction tower is used. When the discharge amount reaches a predetermined amount, the packed tower is rotated, The adsorbent desorbed water used in the first reaction tower is used in the second reaction tower, and a device using the refrigerant used in the latent heat recovery tower as a heat source of another device is provided. A device to recover latent heat from exhaust gas. 14. The apparatus for recovering latent heat from exhaust gas according to claim 12 or 13, wherein zeolite, alumina, activated alumina, or silica gel is used alone or as a mixture of plural kinds thereof as the adsorbent. 15. The hygroscopic agent concentration according to claim 12,
A device for recovering latent heat from exhaust gas, characterized by being used between wt% and 70 wt%. 16. The method according to claim 9 or 13,
A method for recovering latent heat from exhaust gas, which comprises using an adsorbent in a temperature range of 50 ° C to 150 ° C. 17. The device for recovering latent heat from exhaust gas as claimed in claim 5, wherein the recovered heat is used as a driving heat source for a cold heat generator of 7 ° C. or less.