JPS5837483A - Waste heat recovery device for preventing corrosion due to sulfur oxide - Google Patents

Abstract

PURPOSE:To prevent the occurrence of corrosion, by utilizing a variable conductance heat pipe, and keeping the surface temperature on the heat absorbing side of the heat pipe at a dew point temperature or higher of the sulfur oxide SOx at all times. CONSTITUTION:A continuous wick is provided from a heat absorbing part 32 to a gas reservoir 31 in the vaiable conductance heat pipe 3. Even though a burned exhaust gas temperature Tg is decreased less than the dew point temperature of the sulfur oxide SOx, the surface temperature of the heat absorbing part 32 is kept at the dew point temperature or more of the sulfur oxide SOx by a high temperature water in a water supplying and heating part 1. Therefore, the corrosion at the starting of the operation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waste heat recovery device using a heat pipe, more specifically, a heat transfer surface on the heat absorption side of the heat pipe, which is corroded by sulfur oxides SOx K in the combustion exhaust gas.・In recent years, heat pipes have come to be widely used in waste heat recovery devices, focusing on the excellent thermal conductivity and constant temperature characteristics of heat pipes. However, boilers that are subject to load fluctuations,
Alternatively, if a heat pipe is used to recover exhaust heat from an incinerator, etc., the surface temperature of the heat transfer coil on the heat absorption side of the heat pipe will also change depending on the fluctuation of the combustion exhaust gas temperature, so depending on the combustion exhaust gas temperature, the heat pipe When the surface temperature falls below the dew point temperature of sulfur oxide 80x, the sulfur oxide 80x contained in the gas condenses on the surface of the heat transfer coil and becomes sulfuric acid, resulting in corrosion of the surface of the heat pipe and damage to the coil. This causes problems such as clogging and the like, which significantly reduces its durability. In addition, if the temperature of the combustion exhaust gas drops too much due to the excessive heat absorption effect of this exhaust heat recovery device, the inside of the rear flue or chimney will rot in the same way as described above, causing problems such as these. In order to solve this problem, the temperature of the gas at the outlet of the exhaust heat recovery device or the surface temperature of the heat pipe on the heat absorption side is detected, and the amount of water supplied to the feed water heating section is controlled by this detection power, increasing the amount of water according to the temperature of the combustion exhaust gas. There have been proposals for devices that attempt to perform the self-heating effect, but this requires a control device, which causes other problems such as unnecessarily complicating the device. In view of this problem, by using a variable conductance heat pipe that can keep the temperature of the heat absorption part constant regardless of temperature fluctuations of the heat receiving source, the surface temperature of the heat absorption side of the heat pipe is always kept at the dew point of sulfur oxide 80x. A simple waste heat recovery method that prevents corrosion by maintaining the temperature above K, and protects the flue etc. from corrosion caused by sulfur oxides by performing an endothermic action at the combustion exhaust gas temperature KE. Therefore, the details of the present invention will be explained below based on illustrated embodiments. Figure 1 shows an outline of a feed water heating equipment to which the present invention is applied. In this figure, nine waste heat recovery devices are installed in the path of the flue gas duct 42 from the boiler 41 to the chimney, and the heat receiving part 2 that receives the thermal energy of the flue gas and the boiler 41 are installed.
A water supply heating section 1, which is a pressurized liquid container provided in a water supply system, is provided on the water supply side of the water supply heating section 1, and a water supply pipe 6 extending from a water supply tank 5 via a water supply pump P1. is connected to the water supply side, and a water supply pipe 7 extending to the boiler 41 via a pump horse for boiler water supply is connected to this water supply side. This is a partition wall made of a highly corrosion-resistant metal such as, for example, a large number of variable conductance beat pipes 3, which will be described later, with heat radiating parts and heat absorbing parts visible in the feed water heating part 1 and the heat receiving part 2, respectively. ! I... is firmly fixed.

Additionally, if necessary, a drain inlet is provided at the lower part of the water supply tank 5 to introduce condensed steam from the boiler 41 through the load side circuit, and the high temperature drain is also used to preheat the supply water.

FIG. 2(a) is a principle diagram of the variable conductance heat pipe 5 used in the above-mentioned device, and as is well known, this heat pipe 3 has a gas reservoir 51 at its heat dissipation end. Inside, there is a heat pipe necessary to maintain the heat pipe 3 always above the dew point temperature of @yellow oxide 80x (this varies depending on the amount of sulfur oxide 5OxO contained in the combustion exhaust gas, but generally above 140°C). In other words, in general, the heat absorption part 52 of this type of variable conductance heat pipe 3 is sealed with an electrostrictive active non-condensable gas G such as argon gas at a certain amount (pressure) together with the working fluid.
When the K heat flow occurs, the steam rltI/c of the working fluid flowing from the heat absorption part S2 toward the heat radiation $55 is pushed and the exhaust condensable gas G is blown towards the heat radiation part 55, but the steam Lv at that time The theoretical interface B8 formed between the
) A non-condensable gas G is sealed in this variable conductance heat pipe S so that it is located near the partition wall 21 that partitions the heat receiving part 2 and the feed water heating part 1 in a temperature range of around 140°C. be.

Next, to explain the operation of the above-mentioned embodiment, under normal usage conditions in which the boiler 41 is operated at a state close to its rated output, the temperature Tg of the combustion exhaust gas flowing inside the heat receiving section 2 is sufficient. As a result, the vapor pressure within the variable conductance heat pipe 3 becomes sufficiently high and pushes it to the heat radiation section 33 to a position where the pressure of the enclosed non-condensable gas G is balanced. As a result, Figure 2 (a)
As shown in Figure 1, the theoretical interface BS between the two goes deep into the water absorption heating section 1, where a condensation section of the working fluid is formed, and the water flowing inside the water absorption heating section 1 is combusted. When exhaust gas heat is supplied, it becomes K. In other words, the part from the partition wall 21 to this theoretical interface Bat is effective for heat dissipation and is long (see Fig. 2).
)), and as this length increases, the amount of heat dissipation increases,
Also, the shorter the length, the less heat dissipated.
Therefore, the heat absorption part 320 of the heat pipe 5
The surface temperature is always maintained near the dew point temperature of sulfur oxide 80x, and the water in the water absorption heating unit 1 is continued to be heated.When the load on the boiler 41 is lowered at night, etc., the combustion exhaust gas temperature Tg also decreases. descend. Particularly in the heat receiving section 2, as a result of being exposed to the heat absorption action, the temperature decreases further, and at the outlet side of the heat receiving section 2, the temperature decreases to a temperature Kt close to the dew point temperature of the sulfur oxide 80x. In this state, the vapor pressure inside the heat pipe 5 decreases, so the pressure of the non-condensable gas G increases relatively, and the theoretical boundary surface B8 is shown in Fig. 2 (←)
As shown in Fig. 1, the heat dissipation temperature drops to near the bottom of the feed water heating section 1, and the effective heat radiation length becomes 0, stopping further feed water heating action. However, even in this case, the heat pipe 5
Since the fuel itself receives heat from the combustion exhaust gas and maintains the temperature at 140° C., no sulfur oxide 80x condenses on its surface.

On the other hand, if water with a temperature exceeding 70°C is supplied into the feedwater heating unit 1, the temperature will exceed 100°C on the feedwater outlet side, but the temperature inside this feedwater heating unit 1, which forms a pressurized liquid container, will exceed 100°C. There is a water pump P.

The collected heat can be used to raise the temperature of boiler feed water without being released into the atmosphere as steam, and there is no need for a balance tank. In addition, if a continuous wick is provided in the variable conductance heat pipe 3 from the heat absorption part 52 to the gas reservoir/31, even if the combustion exhaust gas temperature Tg falls below the dew point temperature of sulfur oxide SOx. , due to the high temperature water in the feed water heating section 1, the heat absorption section 32
By maintaining the surface temperature of the sulfur oxide 80x above the dew point temperature of the sulfur oxide 80x, corrosion during startup can be avoided.

In the embodiment shown in FIG. 5, the feed water heating unit 1 is provided with a drum 11 for generating high pressure steam, which is equipped with a steam separator 12 and a safety valve 16, and the generated steam is used to heat C heavy oil, etc. It is constructed so that it can be used as an auxiliary device for the boiler 41, and in the figure, reference numeral 14 indicates a water inlet, and 15 indicates a liquid level needle.

The present invention has been explained above using an example of a general variable conductance heat pipe having a gas reservoir SL, but as shown in FIG. This makes it possible to reduce axial fluctuations in the bed-layer boundary surface BS and to exert a heat dissipation effect as stable as possible against fluctuations in combustion exhaust gas temperature.・Ninth, in order to maintain the surface temperature of the heat absorption part 320 above the dew point temperature of the sulfur oxide 80 Even if air is enclosed,
According to the present invention, it is possible to ignore pressure increases and decreases due to chemical effects, etc., and it is possible to simultaneously reduce the manufacturing cost of heat pipes and prevent deterioration. A variable conductance heat pipe or a tube-controlled heat pipe is used for the heat pipe used in the recovery device, and the internal temperature is maintained within a temperature range based on the surface temperature of the heat pipe and the dew point temperature of the sulfur oxide. Since the amount of non-condensable gas is sealed together with the working fluid, the heat receiving source of the heat pipe is not subject to large temperature fluctuations, such as flue gas from a boiler or incinerator with large load fluctuations. Even if the heat pipe is heat-absorbing, the surface temperature on the heat-absorbing side is always kept close to the reference temperature regardless of this, and the heat-absorbing fins on the surface are corroded by 80x K of sulfur oxide in the combustion exhaust gas. can be prevented and its semi-permanent use established. In addition, it is possible to turn on and off the heat transfer from the combustion exhaust gas side to the water supply side based on this reference temperature, which prevents the combustion exhaust gas temperature from lowering too much due to excessive heat absorption, and reduces heat reception. This makes it possible to protect the flue or chimney behind the unit from the corrosive effects of 80x K sulfur oxide.Moreover, since a pressurized liquid container is used on the waste heat recovery side, the recovered heat is released into the atmosphere as steam. Not only can the combustion exhaust gas be effectively recovered without causing damage, but even if the combustion exhaust gas temperature drops below the standard temperature, the surface of the heat receiving part of the heat pipe can be maintained at a high temperature to prevent corrosion at the start-up stage. becomes possible.

4. Additional relations The present invention is based on the patent application filed in 1986-400 by the applicant.
The invention of No. 04 is applied to a nuclear power plant, and the invention is an invention in which the main part of the matter that is essential to the configuration for the nuclear power plant is the main part of the matter that is not available due to the busy schedule, and achieves the same purpose as the one for the nuclear power plant. It is something to do.

[Brief explanation of the drawing]

1st! Figure 2(a) is a diagram illustrating the principle of the variable conductance heat pipe applied to the present invention. ) is a diagram showing the pressure relationship inside the heat pipe,
FIG. 6 is a schematic diagram of an apparatus showing another embodiment of the present invention. 1. Water supply heating section, 11. Drum, 2. Heat receiving section, S. Variable conductance heat pipe. ,! S1
... Gas reservoir, 52 ... Heat absorption part, 53 ... Heat radiation part, 41 ... Boiler, L ... Working fluid, G ... Non-condensable gas, B8 ... Boundary in general theory Face〇 Applicant: Snow Brand Milk Products Co., Ltd. Suzuki Metal Industry Co., Ltd. Representative Patent Attorney Keiji Torikawa Tsuyoshi Tsukuyoshi 3rd [-111111]

Claims (1)

[Scope of Claims] A plurality of heat pipes each having a working fluid and a non-condensable gas sealed in an amount such that the heat pipe operates at a temperature equal to or higher than the dew point temperature of sulfur oxide. Waste heat recovery for preventing corrosion caused by sulfur oxides, characterized in that the heat absorption part and the heat radiation part of the top pipe are located in the combustion exhaust gas flow path and in the pressurized liquid container, respectively. 2. A waste heat plate device for preventing corrosion caused by sulfur oxides according to claim 1, wherein the pressurized liquid container is a pressurized liquid container that is incorporated into a boiler water supply system. The waste heat recovery device for preventing corrosion caused by saponified sulfur as claimed in claim 1, wherein the liquid container is a steam drum for generating high-pressure steam.