JPS5840421A - Reheating method for desulphurized waste gas - Google Patents

Abstract

PURPOSE:To miniaturize a reheating system for treated gas, by a method wherein two liquid thermal mediums are applied as a heat accumulating body and the two liquid thermal mediums each are made to exchange their heat indirectly after heat has been exchanged directly between untreated gas and treated gas. CONSTITUTION:High temperature untreated gas 1 touches directly a No.1 low temperature thermal medium 31 in a No.1 thermal medium contactor 11, the high temperature untreated gas 1 is turned into a low temperature untreated gas 1' through a temperature decrease and the No.1 low temperature medium 31 is turned into a No.1 high temperature medium 31' through a temperature rise. The No.1 high temperature thermal medium 31' led to an indirect heat exchanger 20 is exchanged its heat with that of a No.2 low temperature thermal medium 32 and No.1 high temperature medium 31' is turned into the No.1 low temperature medium 31 through the temperature decrease. On the other hand, the No.2 low temperature thermal medium 32 is turned into a No.2 high tem perature thermal medium 32' through the temperature rise. With this, it is possible to obtain a heat recovery and reheating method which is compact and free of gas leak.

Description

[Detailed Description of the Invention] The present invention is an improvement of a method for reheating wet flue gas desulfurization treatment gas.
Regarding K.

A gas containing corrosive components and saturated moisture, such as desulfurization gas #1801, is discharged after reheating to prevent corrosion of downstream equipment, prevent white smoke from chimneys, and increase dispersion.

As a means of reheating the treated gas, heating with afterburner steam was once used, but recently, from the viewpoint of energy saving, a method of reheating using heat recovered from the pre-treated gas has been adopted. It has been put into practical use as a heat recovery method.
This is a book about a heat storage rotation system, but because the rotating part cannot be completely sealed, untreated gas leaks to the treated gas side, and dust may be present in the untreated gas, especially in the case of coal-fired combustion. #'i is not an appropriate device if there are many. An indirect heat exchanger method may also be considered as a means to prevent the above-mentioned leakage, but this method has the disadvantage that the device is large because the heat transfer coefficient between the gas and the solid wall is small.

Therefore, the inventors of the present invention decided to make it small and prevent gas leakage.
As a result of intensive research into the development of the recovery reheating method, we found that two liquid heat carriers are used as heat storage bodies, and the liquid heat carriers are directly heat exchanged with untreated gas and/or treated gas, and each liquid heat carrier is It has been confirmed that the above object can be achieved by performing heat exchange upwardly and indirectly, and the present invention has been completed.

That is, the present invention provides a method for reheating flue gas desulfurization treatment gas, in which a first liquid heat medium circulates between an untreated gas cooling section and an indirect heat exchange section, and a first liquid heat medium that circulates between a treatment gas heating section and the indirect heat exchanger. The indirect heat exchanger exchanges heat with the second liquid heat medium that circulates between the exchanger and the second liquid heat carrier, and the untreated liquid heat carrier is heated in the untreated gas cooling section and the treated gas heating section. This book provides a summary of a method for reheating flue gas desulfurization processing gas, which is characterized by direct contact with either gas or processing gas beforehand.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a flowchart in which two liquid heat carriers are directly heat exchanged with an untreated gas and a treated gas.

In FIG. 1, the high temperature untreated gas 1Fi, the first low temperature heat medium 3 in the first heat medium contactor 11! The temperature of the high-temperature untreated gas 1 decreases by direct contact with the low-temperature untreated gas 1',
The temperature of the first low-temperature heat medium s1 increases and becomes the first high-temperature heat medium. The first high-temperature heat medium 3ζ is guided to the indirect heat exchanger 20 and exchanges heat with the second low-temperature heat medium 3ζ at The temperature of the power cylinder 2 low-temperature heat medium rises and becomes the second high-temperature heat medium 6.

Next, the second high-temperature heat carrier is brought into direct contact with the low-temperature processing gas 2 in the second heat-medium contacting device 13, and the second high-temperature heat carrier is circulated through the above-mentioned system by the temperature lowering pump 21, and is then heated to a low temperature. The temperature of the processing gas 2 increases to become a high temperature processing gas 2'.

The first low-temperature heat medium 31 exiting the indirect heat exchanger 20 is in the settling tank 1
4$1C is introduced and left to stand still, and at the same time the high temperature untreated gas 1 is cooled, the same gas 1) is removed and large dust is precipitated.

The first low-temperature heat transfer pump 1 is the supernatant liquid of the settling tank 14.
5, it is integrated into the first heat medium contacting device 11.

The sedimentation liquid 4 in the sedimentation tank 14 is separated from the separated dust 5 by a solid-liquid separator 14 such as a centrifuge, and then the separated liquid 6 is returned to the sedimentation tank 14 by a return pump 17. .

The first and second heat medium contactors may be of any type as long as they have a large contact area between liquid and gas, such as spray towers, venturi-packed towers, tray towers, etc. In either device, mist is entrained on the main gas side, so the gist separator 18.1? It is preferable to collect the mist at the auxiliary liquid pipe 7.8 and return it to the heat medium contactor 11.15 through the sub-liquid pipe 7.8.

As a heat medium, a high temperature untreated gas inlet temperature f (120 to 1
60°C), and it is preferable to boil at this temperature and have a low vapor pressure. Examples include organic heat carriers.

As explained above, heat exchange between the untreated gas and the treated gas is performed using two liquid heat carriers as an intermediate medium, and since the two gases do not come into direct contact with each other, the treated gas leakage (leaking of the untreated gas is completely prevented). can be prevented.

As a modification of the flow shown in FIG. 1, the flow shown in FIG. 2 may be used.

That is, in order to avoid dust from entering the first liquid heat medium from the untreated gas, the contact between the high temperature untreated gas 1 and the first low temperature heat medium is performed using an indirect heat exchange method using the indirect heat exchange device 22. The contact between the low-temperature @11 gas 2 and the first high-temperature heat transfer medium can be done by a direct heat exchange method similar to the flow shown in Figure 1.
This has the advantage that 4 tons of equipment can be omitted.

Note that in FIG. 2, the same reference numerals as in FIG. 1 represent the same parts as in FIG. 1.

According to 70- in FIG. 2 of the embodiment, 1! $2'e high temperature untreated moth x 5! $1500 Myl/b and 65℃ water18
What is the temperature of the untreated l gas when 5500 and - are brought into indirect contact with 9 and ζ? O'eK has dropped and water is 10! 't becomes nine, convert this 105℃ water into 56℃ 2-isoprobylnaphthalene)/! I? When indirect heat exchange was performed with + at 44110 ktv/, the water temperature was 65°C, and the temperature of 2-inpropylnaphthalene was 96°C. When 2-isopropylnaphthalene (394,680k7) at 96°C was brought into direct contact with 548,300 Mrl/h of low temperature processing gas at 51.8°C, 2-isopropylnaphthalene (394,680k7) at 96°C was brought into contact with 2-isopropylnaphthalene at 56°C, and the processing gas was heated to 92.9°C. heated.

As described above, according to the present invention, (1) the heat medium is directly exchanged with the gas, so that the processing gas reheating system becomes compact and low cost.

(2) The present invention has the effect that there is no leakage of the 16 process gas to the process gas side, and the present invention is an industrially extremely significant method, especially as a means for reheating coal-fired flue gas desulfurization process gas.

[Brief explanation of the drawing]

FIG. 1.2 shows a diagram of an embodiment of the present invention. Sub-agents 1) Myoki agent Ryo Hara -

Claims (1)

[Claims] (1) In a method for reheating flue gas desulfurization treatment gas, the first liquid heat medium circulates between the untreated gas cooling section and the indirect heat exchange section, and the treatment gas heating section and the indirect heat exchange section. In the indirect heat exchanger section, the liquid heat medium is exchanged with the second liquid heat medium circulating between the untreated gas cooling section and the treated gas heating section. A method for reheating flue gas desulfurization processing gas, the method comprising direct contact with the processing gas, one or both of the processing gases.