KR20200033728A - Heat exchanger and using method thereof - Google Patents

Abstract

The present invention is configured to heat a fluid to be heated by effectively utilizing water vapor latent heat of superheated water vapor, and comprises: a heat exchange pipe (2) through which the fluid to be heated flows; a downstream side container (3) configured to accommodate a downstream side portion (2a) of the heat exchange pipe (2), and further, supplied with superheated water vapor; and an upstream side container (4) configured to accommodate an upstream side portion (2b) of the heat exchange pipe (2), and further, supplied with water vapor passing through the downstream side container (3). Moreover, a fluid to be heated flowing through the downstream side portion (2a) of the heat exchange pipe (2) is heated by sensible heat of superheated water vapor supplied to the downstream side container (3), and a fluid to be heated flowing through the upstream side portion (2b) of the heat exchange pipe (2) is heated by latent heat of water vapor supplied to the upstream side container (4).

Description

Heat exchanger and its use method {Heat exchanger and using method thereof}

The present invention relates to a heat exchanger using superheated water vapor and a method of using the heat exchanger.

In many paper and textile and chemical manufacturing plants, there are many heat treatment processes, so large steam boilers are often used as heat sources. In addition, even in fluid heating such as hot air used for drying, fluid heating is usually performed through a heat exchanger (Patent Document 1).

In the case of hot air, it is often used to heat the air to about 150 °, but even when high-pressure steam is flowed to a plant at a distance from the boiler, there is often a pressure drop in the piping and the temperature is often reduced to about 130 ° C. For this reason, many cases cannot be used as heat sources despite the presence of excess steam.

Patent Document 1: Japanese Patent Publication No. 2013-224810

In order to effectively use this excess steam as a heat source, there is a method of reheating the steam with reduced pressure and temperature to a desired temperature to make it superheated steam, but in a heat exchanger using superheated steam, the fluid such as air is heated to a desired temperature. In this case, in order to obtain a temperature above the boiling point of water at a saturated vapor pressure, basically, the inlet and outlet temperatures of superheated steam must be at a temperature above the boiling point of water.

However, in this method, the superheated water vapor having a temperature equal to or higher than the boiling point of water is discharged, and the latent heat of water vapor contained in the superheated water is discarded.

Therefore, the present invention has been made to solve the above problems, and its main task is to heat the fluid to be heated by effectively utilizing latent heat of water vapor contained in superheated water vapor.

That is, the heat exchanger according to the present invention is a heat exchanger for performing fluid heating by superheated steam, which accommodates a heat exchange pipe through which a heated fluid flows and a downstream portion of the heat exchange pipe, and supplies superheated steam. And a downstream container to be received, and an upstream container to receive water vapor passing through the downstream container while receiving an upstream part of the heat exchange pipe, and heating the blood flowing through the downstream part of the heat exchange pipe. The fluid is heated by the sensible heat of the superheated steam supplied to the downstream container, and the fluid to be heated flowing through the upstream portion of the heat exchange pipe is a latent heat of water vapor supplied to the upstream container (潛 熱) is characterized by being heated.

If this is the case, the superheated steam is supplied to the downstream container to heat the fluid to be heated to a desired temperature by the sensible heat of the superheated steam, and the steam is supplied from the downstream container to the upstream container to be heated by the latent heat of the steam. Since the fluid is configured to heat (preheat), the fluid to be heated can be heated by effectively utilizing the latent heat of water vapor of the superheated steam. In addition, although water vapor supplied to the upstream container loses latent heat and is liquefied and discharged as water vapor without being liquefied, latent heat as much as liquefied is effectively used.

Specifically, the temperature and amount of superheated water vapor supplied to the downstream vessel are set such that the fluid to be heated flowing through the downstream portion of the heat exchange pipe is at a desired temperature of 100 ° C or higher, and from the downstream vessel It is preferable that the temperature of the water vapor supplied to the upstream container is set to be 100 ° C or higher.

Here, when the fluid to be heated is air, it can be heated up to 100 ° C by latent heat of water vapor, and heated by water vapor sensible heat to heat to a temperature higher than that. The energy of the superheated water vapor has a large proportion of latent heat, but the calculated value of the ratio of the latent heat that can be used by the present invention is shown in FIG. 2. 2 is a latent heat utilization rate (%) when heating air at 20 ° C with superheated water vapor.

In FIG. 2, the place exceeding 100% indicates that it is unreasonable to increase the temperature to 100 ° C due to latent heat of water vapor, and that control such as increasing the amount of superheated water vapor to be supplied and adjusting the temperature is necessary.

It can be said from the above calculation results that the utilization rate of latent heat increases as the superheated water vapor of the heat source becomes higher. In addition, since the temperature of the superheated steam supplied to the upstream container is 100 ° C or higher and close to 100 ° C as much as possible, the utilization rate of latent heat is increased, so that the heat exchanger so that the temperature of the superheated steam supplied to the upstream container is 100 to 110 ° C Do the design of.

The inlet temperature detection mechanism for detecting the temperature of the fluid to be heated flowing into the heat exchange pipe, the inflow detection mechanism for detecting the amount of fluid to be heated flowing into the heat exchange pipe, or the temperature of the fluid to be heated flowing out from the heat exchange pipe At least one of the outflow temperature detecting mechanism to detect, and at least one of a superheated steam temperature adjusting mechanism that adjusts the superheated steam temperature supplied to the downstream vessel, or a superheated steam amount adjusting mechanism that adjusts the amount of superheated steam supplied to the downstream vessel. It is preferable that a dog and a calculation mechanism for calculating the adjustment amount in at least one of the adjustment mechanisms are provided based on the detected values of the at least one detection mechanism.

In addition, the method of using the heat exchanger according to the present invention includes a heat exchange pipe through which the fluid to be heated flows, a downstream container receiving the downstream portion of the heat exchange pipe and supplying superheated steam, and the heat exchange pipe A method of using a heat exchanger having an upstream container to receive water vapor passing through the downstream container while receiving an upstream portion of the, wherein the temperature and amount of superheated water vapor supplied to the downstream container, the heat exchange In addition to setting the fluid to be heated flowing through the downstream portion of the pipe to a desired temperature of 100 ° C or higher, setting the temperature of water vapor supplied from the downstream container to the upstream container to be 100 ° C or higher It is characterized by.

According to the present invention configured as described above, the fluid to be heated can be heated by effectively utilizing latent heat of water vapor contained in the superheated water vapor.

1 is a diagram schematically showing a configuration of a heat exchanger according to an embodiment of the present invention.
2 is a view showing the latent heat utilization rate when heating the air at 20 ° with superheated steam.

One embodiment of the heat exchanger according to the present invention will be described below with reference to the drawings.

<1. Device configuration>

The heat exchanger 100 according to the present embodiment heats a fluid such as air using superheated steam as a heat source. Further, as the superheated steam used in the heat exchanger 100, it is assumed that the excess steam of a factory with a large boiler is reheated by a superheated steam generating device, but passes through a treatment furnace of the superheated steam device. One used superheated steam may be used, or the used superheated steam may be heated again.

Specifically, as shown in FIG. 1, the heat exchanger 100 accommodates the heat exchange pipe 2 through which the fluid to be heated flows, and the downstream portion 2a of the heat exchange pipe 2, and superheated steam It is provided with a downstream container (3) to be supplied, and an upstream container (4) to receive water vapor passing through the downstream container (3) while accommodating the upstream side portion (2b) of the heat exchange pipe (2). have.

The heat exchange pipe 2 has an introduction port P1 through which the fluid to be heated is introduced, and a discharge port P2 through which the fluid to be heated is drawn. Moreover, the heat exchange piping 2 forms meandering flow paths in each container 3 and 4 in order to increase the heat exchange area. Further, as the material of the heat exchange pipe, austenite stainless steel, Inconel alloy, or the like can be used.

The downstream container 3 has one space 3S for accommodating the downstream portion 2a of the heat exchange pipe 2, a supply port P3 through which superheated steam is supplied, and a drain to be discharged. It has a drain port (P4). In addition, although the drain port P4 is not required in the downstream container 3 ideally, it is provided because the drain may actually come out.

The upstream container 4 has one space 4S for accommodating the upstream portion 2b of the heat exchange pipe 2, and a supply port through which water vapor passing through the downstream container 3 is supplied ( P5) and a discharge port P6 through which water vapor or drain is discharged.

In the present embodiment, the downstream container 3 and the upstream container 4 are configured by dividing one container by a partition wall 5. Then, the partition wall 5 is provided with a connection path 51 for connecting the downstream side container 3 and the upstream side container 4, and the connection path 51 is an upstream side container 4 ) To the supply port (P5). Further, as the material of the downstream container 3 and the upstream container 4, austenitic stainless steel, Inconel alloy, or the like can be used.

In this heat exchanger (100), the heated fluid flowing through the downstream portion (2a) of the heat exchange pipe (2) is heated by the sensible heat of the superheated steam supplied to the downstream container (3), and the heat exchange pipe ( The fluid to be heated flowing through the upstream side portion 2b of 2) is configured to be heated by latent heat of water vapor supplied to the upstream side container 4.

Specifically, the temperature (Θs) and the amount (Qs) of the superheated water vapor supplied to the downstream container 3 is that the fluid to be heated flowing through the downstream portion 2a of the heat exchange pipe 2 is 100 ° C or higher. In addition to being set to a temperature of, the temperature (Θsc) of water vapor supplied from the downstream container 3 to the upstream container 4 is set to be 100 ° C or higher.

<2. Design method ＞

Here, the design method of the heat exchanger 100 of this embodiment is demonstrated.

First, the maximum temperature (Θsm) of the superheated steam supplied to the heat exchanger 100 from the superheated steam processing apparatus or the superheated steam supply apparatus (not shown) is determined from the viewpoint of durability or manufacturing cost.

Next, when the superheated steam to be supplied is the highest temperature (Θsm) and the air (heated fluid) of about 90 ° C is the maximum inflow (Qam), heating the heated fluid to the desired maximum outflow temperature (Θm) The required amount of superheated water vapor (Qsm) is set.

Subsequently, the heat exchange area of the heat exchange pipe 2 of the downstream vessel 3 is such that the temperature Θsc of the water vapor flowing into the upstream vessel 4 from the downstream vessel 3 is about 100 to 110 ° C. S1).

The pipe 2 for heat exchange of the upstream side container 4 is a heat exchange area required for heating the fluid to be heated at an inlet temperature Θa (for example, 20 ° C) to 95 to 100 ° C by water vapor at 100 ° C. Set (S2).

The heat exchanger 100 designed as described above has the highest latent heat utilization rate when the superheated water vapor (Qsm) is the maximum temperature (Θsm) in the superheated water vapor amount (Qsm) when the rated maximum inflow amount (Qam) and the maximum outflow temperature (Θm). do. Incidentally, the control of the outflow temperature Θ flowing out from the heat exchange pipe 2 is, first, the maximum amount of output air (Qam), and the maximum temperature (Θsm) of the supply superheated steam required to make the maximum temperature (Θm) and It is considered that precise control is performed by setting the amount Qsm and then adjusting the temperature Θs of the superheated water vapor.

In addition, the heat exchanger 100 of the present embodiment is the best of superheated steam from the outflow temperature (control set value) Θ, the inflow temperature Θa of the fluid to be heated, and the inflow amount Qa of the fluid to be heated. It has a calculation mechanism 6 for calculating the required amount of superheated water vapor Qs at the temperature Θsm. With this arithmetic function, it is possible to set the required amount of superheated water vapor Qs under the operation condition even when the operation condition is changed, and control to maximize the latent heat utilization rate in the heat exchanger 100 can be performed.

For this reason, the heat exchanger 100 includes an inflow temperature detection mechanism 7 that detects the inflow temperature Θa, an inflow amount detection mechanism 8 that detects the inflow amount Qa, and an outflow temperature Θ of the fluid to be heated. ) Is provided. Moreover, the heat exchanger 100 is equipped with the superheated steam amount adjustment mechanism 10 which adjusts the superheated steam amount Qs supplied to the downstream side container 3. And the calculation mechanism 6 calculates the adjustment amount in the superheated water vapor amount adjustment mechanism 10 based on the detection value of each detection mechanism 7-9, and controls the required superheated water vapor amount Qs. In addition, the heat exchanger 100 has a superheated steam temperature adjustment mechanism that adjusts the superheated water vapor temperature Θs supplied to the downstream container 3, and the calculation mechanism 6 includes each detection mechanism 7 to Based on the detected value of 9), the adjustment amount in the superheated water vapor temperature adjusting mechanism may be calculated to control the required superheated water vapor temperature Θs.

<3. Specific example>

If a specific example is shown, it will be as follows.

In the heat exchanger 100, when operating at the inflow amount Qa, the inflow temperature 20 ° C, the outflow temperature 300 ° C, the superheated water vapor amount Qsm, and the superheated water vapor temperature 600 ° C, the latent heat utilization rate is 22.8% at the maximum (see FIG. 2). ).

Here, considering the case of operating by changing the outflow temperature to 150 °, first, in the superheated water vapor at 600 ° C and the heat exchange area (S1), the amount of superheated water vapor at which air at 90 ° C of the inflow amount Qa can be 150 ° C ( Qsn). At this time, the latent heat utilization rate is a maximum of 91.1%. In addition, fine adjustment of the outflow temperature Θ is performed by controlling the superheated water vapor temperature Θs. In addition, if a part of the operating conditions is fixed or step-setting, a detection mechanism for that part may be unnecessary.

<4. Heat calculation of the heat exchanger 100>

The air specific heat (A) and superheated steam specific heat (S) in the following calculations are actually slightly changed in value by temperature, but are simplified and the same here.

1. Heat calculation in the downstream vessel (3)

(1) Outflow temperature (Θ): 150 ℃

Inflow temperature (Θa): 90 ℃

Air heating calories: (150-90) × A × Qa ₁₅₀ ≒ 60 × A × Qa ₁₅₀

A ： Specific heat of air, Qa ₁₅₀ ： Air volume

(2) Outflow temperature (Θ): 300 ℃

Inflow temperature (Θa): 90 ℃

Air heating calories: (300-90) × A × Qa ₃₀₀ ≒ 210 × A × Qa ₃₀₀

A: Specific heat of air, Qa ₃₀₀ : Air volume

(3) If the superheated steam temperature is 600 ° C, the outlet temperature from the downstream container 3 to the upstream container 4 is 110 ° C, and the superheated steam amount Qs is constant, the heating amount of the superheated steam is about (600-110). It becomes × S × Qs. Here, S is the specific heat of superheated water vapor.

At this time, the relationship between the amount of air heated to 150 ° C and 300 ° C is about Qa ₃₀₀ = (60/210) Qa ₁₅₀ .

Therefore, when the superheated steam having the same amount and the same temperature of 600 ° C is input to the heat exchanger 100 designed with Qa ₁₅₀ , and the air amount is 60/210, 300 ° C of output air can be obtained, and the outlet temperature Can be 110 ° C. Since the heat exchange amount is the same, if the heat exchange area S1 at 150 ° C with a small temperature difference is secured, it is sufficiently satisfied at 300 ° C.

(4) For the operation of the above-mentioned outflow temperature 150 ° C and air quantity Qa ₁₅₀ , when the air quantity is changed to 0.5 Qa ₁₅₀ , the superheated water vapor temperature is 600 ° C and the required superheated water vapor amount to make the outlet temperature 110 ° C is about 0.5Qs. .

Since the amount of heat exchange is halved, the heat exchange area (S1) is satisfactorily met, but when the effluent air is controlled at the set values of 0.5Qa ₁₅₀ and 150 ° C, heat exchange is not performed more than necessary, so the outlet temperature of the superheated steam is 110 ° C. .

(5) If the air quantity is constant (Qa ₁₅₀ = Qa ₃₀₀ ), the superheated water vapor temperature is 600 ° C, and the outlet temperature is 110 ° C, the superheated water vapor quantity Qs ₁₅₀ ≒ (60/210) Qs ₃₀₀ is obtained.

Therefore, when the superheated water vapor of 600 ° C is input to the heat exchanger 100 designed with Qa ₃₀₀ at the same temperature and at the same temperature, and the amount of superheated water vapor is 60/210, 150 ° C of output air can be obtained. The outlet temperature can be 110 ° C. Since the output air of 300 ° C is larger than the output air of 150 ° C, if the heat exchange area S1 in the output air of 300 ° C is secured, it is sufficiently satisfied at 150 ° C.

2. Calculation of heat in the upstream vessel 4

As shown in the latent heat utilization rate of FIG. 2, since the utilization temperature of 150 ° C is also 91.1% at the superheated steam temperature of 600 ° C, and 22.8% at the exit temperature of 300 ° C, air at 20 ° C is 90 ° C (calculated phase is 100 ° C). It is clear that it can be heated to.

3. Overall heat flow

In the upstream side container 4, since the temperature of the heat exchanger near the air inlet side is lowered, first, the latent heat of a lot of saturated water vapor starts from the vicinity of the inlet side. When the heat exchange area is sufficiently satisfied, heat exchange is performed in the entire heat exchanger of the upstream side container 4, and the temperature of the air rises to around 100 ° C (90 ° C in the calculated phase).

On the other hand, since the heat exchange area is sufficient even in the downstream container 3, the outlet temperature of the superheated steam is supplied by supplying the amount of superheated steam that can obtain heat at a temperature from 600 ° C to 110 ° C to increase the temperature to the set outlet temperature. 110 ° C can be ensured.

<5. Effects of this embodiment>

According to the heat exchanger 100 configured as described above, superheated steam is supplied to the downstream container 3 to heat the fluid to be heated to a desired temperature by sensible heat of the superheated steam, and from the downstream container 3 to the upstream side Since the water is supplied to the container 4 and configured to heat (preheat) the fluid to be heated by the latent heat of the water vapor, the fluid to be heated can be heated by effectively utilizing the latent heat of water vapor of the superheated water vapor.

<6. Modified embodiment of the present invention>

Moreover, this invention is not limited to the said embodiment.

For example, in the above-described embodiment, the downstream container 3 and the upstream container 4 are integrally configured, but may be configured from different containers.

In addition, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit.

100-Heat exchanger 2-Piping for heat exchange
2a-downstream part 2b-upstream part
3-downstream vessel 4-upstream vessel
6-computational mechanism 7-inflow temperature detection mechanism
8-Inflow amount detection mechanism 9-Outflow temperature detection mechanism
10-Superheated water vapor adjustment mechanism

Claims (4)

A heat exchanger for fluid heating by superheated steam,
A pipe for heat exchange through which the heating fluid flows,
A downstream container for receiving the downstream portion of the heat exchange pipe and supplying superheated steam,
The upstream side portion of the heat exchange pipe is accommodated, and the upstream side container is supplied with water vapor that has passed through the downstream side vessel.
The fluid to be heated flowing through the downstream portion of the heat exchange pipe is heated by sensible heat of superheated steam supplied to the downstream vessel,
The heat-exchanging fluid flowing through the upstream portion of the heat exchange pipe is heated by latent heat of water vapor supplied to the upstream side container. The method according to claim 1,
The temperature and amount of superheated water vapor supplied to the downstream vessel are set such that the fluid to be heated flowing through the downstream portion of the heat exchange pipe is at a desired temperature of 100 ° C or higher, and the upstream vessel from the downstream vessel. The heat exchanger is set so that the temperature of the water vapor supplied to it is 100 ° C or higher. The method according to claim 1,
The inlet temperature detection mechanism for detecting the temperature of the fluid to be heated flowing into the heat exchange pipe, the inflow detection mechanism for detecting the amount of fluid to be heated flowing into the heat exchange pipe, or the temperature of the fluid to be heated flowing out from the heat exchange pipe At least one of the outflow temperature detection mechanism to detect,
At least one of a superheated steam temperature adjusting mechanism for adjusting the superheated steam temperature supplied to the downstream vessel, or a superheated steam amount adjusting mechanism for adjusting the amount of superheated steam supplied to the downstream vessel,
A heat exchanger comprising a calculation mechanism that calculates an adjustment amount in at least one of the adjustment mechanisms based on the detected values of the at least one detection mechanism. The heat exchange pipe through which the fluid to be heated flows, the downstream side container receiving the downstream portion of the heat exchange pipe, and the downstream side container to which superheated steam is supplied, and the upstream side portion of the heat exchange pipe and receiving the downstream side container As a method of using a heat exchanger having an upstream side container through which water vapor passing through is supplied,
The temperature and amount of the superheated water vapor supplied to the downstream vessel are set such that the fluid to be heated flowing through the downstream portion of the heat exchange pipe becomes a desired temperature of 100 ° C or higher, and the upstream from the downstream vessel. A method of using a heat exchanger to set the temperature of the water vapor supplied to the side container to be 100 ° C or higher.

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