JPS6034900Y2 - Equipment that simultaneously processes wastewater and waste gas - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for incinerating waste gas and waste water containing harmful substances.

Conventionally, wastewater with a low content of organic compounds has been discharged after its COD value is reduced by an activated sludge method.

Furthermore, it is often difficult to apply this method when an inorganic compound is contained.

However, organic or inorganic compounds can
When treating wastewater containing several hundred thousand ppm of M, the activated sludge method can be applied because the concentration is too high, and incineration is considered to be one of the most effective methods.

The present invention relates to a device for that purpose.

Generally, in this type of wastewater incineration treatment, it is desirable to concentrate the wastewater as much as possible before incineration in order to reduce the consumption of auxiliary fuel required for incineration as much as possible.

Many methods are used for concentration, such as distillation, normal pressure or reduced pressure evaporation, but if the wastewater contains organic or inorganic volatile hazardous substances, the distilled concentrate or evaporated vapor may contain organic or inorganic volatile hazardous substances. If these volatile hazardous substances are mixed in and discharged or released into the atmosphere, there is a risk of secondary pollution, and therefore separate treatment will be required.

On the other hand, in industry, especially in the chemical industry, there are many processes that generate not only wastewater as mentioned above, but also waste gas or polluted air containing harmful substances such as bad odors and toxic substances. Pollution prevention equipment is required to prevent pollution, such as absorption using chemical solutions or adsorption using adsorbents such as activated carbon.

However, there are many cases where it is not economical to recover and use pollution-causing substances, or where there is a risk of secondary pollution occurring due to treatment, and there are many cases where there is no effective device other than incineration.

The present invention provides an apparatus for completely disposing of waste water and waste gas to be incinerated as described above in an extremely efficient and energy-saving manner when they exist at the same time.

That is, the present invention is an apparatus that simultaneously treats waste gas containing hazardous substances and waste water containing volatile hazardous substances, in which the waste gas containing hazardous substances is introduced from the bottom of the column, and the heated A gas-liquid countercurrent contact method that allows direct contact with wastewater to dissipate volatile harmful substances contained in the wastewater into the waste gas, and also evaporates water into the gas at the same time to concentrate the waste water. A heat exchanger 4 for heating the waste gas for heating the waste gas containing the emitted volatile harmful substances and evaporated water with its combustion waste heat and then incinerating it, and an indirect exchanger described later. 105 and a passageway for heated wastewater are connected to the incinerator 3 and the pump 9 from the concentration tower 6 and the incinerator 3, which is provided with a heat exchanger 5 for heating wastewater, which communicates with the passageway for the wastewater heated there.
and the waste liquid spray nozzle 1 on the upper part of the incinerator 3 via the valve 32
02, and a cooling recovery canister 12 installed at the bottom of the combustion device 103 to rapidly cool the combustion waste gas generated here.
1, and the indirect heat exchanger 105, which is installed in the path of the high-moisture-containing twisted combustion waste gas to be discharged from this and is used to heat the waste water sent from the concentrating column 6 via the pump 8 and the valve 34 using this gas as a heat source. This is a device that simultaneously processes wastewater and waste gas consisting of

At this time, it is preferable from a thermoeconomic point of view to use the amount of heat generated during incineration as a heat source for concentration.

In addition, the predetermined conditions for incineration include a temperature of 800 to 120
This refers to incineration conditions of 0°C and an oxidizing atmosphere with an excess air ratio of 15 to 45%.

For the purpose of concentration, the temperature of the waste gas containing saturated water vapor after contact with waste water or waste gas + air should be higher if there is little oxygen in the waste gas, but saturated water vapor of 80℃ or higher is better. It has been confirmed that it is difficult to achieve the objective of incineration, which is to maintain stable combustion and completely remove harmful substances such as bad odors and COD sources, if the fuel is left untouched.

However, even in this case, combustion can be promoted by preheating these mixed gases with combustion exhaust gas, and incineration can be carried out in a non-polluting and energy-saving manner.

The present invention will be explained below with reference to drawings showing one embodiment.

First of all, if the wastewater contains substances such as alkali salts that produce inorganic salts with a relatively low melting point by incineration, it is impossible to avoid dust troubles in heat exchangers 4, 5, etc. due to fused fly ash generated under specified incineration conditions. It is extremely difficult.

In addition, when a large amount of ash is contained, it is necessary to use the heat of the combustion waste gas after separately removing the incinerated ash, but this is generally considered difficult.

One of the embodiments of the present application for dealing with the above-mentioned cases, that is, the embodiment when the wastewater contains components such as raw ash such as inorganic salts that are likely to cause dust problems when incinerated. .

In this case, valves 31 and 33 are closed and the others are left open.

The wastewater 10 containing volatile harmful substances and substances such as alkali metal components that generate combustion gas including molten ash, which is difficult to utilize waste heat by normal incineration methods, is concentrated using a countercurrent gas-liquid direct contact method. The incineration waste gas is sent to the bottom of the tower 6, passed through the valve 34 by the circulation pump 8 together with the concentrated water, and is discharged from the cooling recovery can 121 of the submerged combustion type incinerator, which is approximately saturated with water vapor at around 90°C. Heat exchange device 105
heat exchange and heating.

The preheated wastewater is then further heated by the heat exchanger 5 on the combustion gas outlet side of the incinerator 3, and introduced into the top of the concentration tower 6 through the heated wastewater pipe 13.

On the other hand, waste gas (or waste air) 11 containing harmful substances is introduced into the bottom of the concentrating tower 6, and while rising in the tower, it comes into contact with the descending heated wastewater, and volatile harmful substances and water vapor in the wastewater are combined. The wastewater is concentrated by moving into the waste gas.

Note that air 19 is used to compensate for oxygen shortage in the waste gas 11 or when the amount of gas is insufficient, and is introduced into the lower part of the concentrating column 6 as necessary.

The waste gas 14, which has been substantially saturated with water vapor, is sent from the top of the concentrating tower 6 to the gas heating heat exchanger 4 installed behind the incinerator 3 and before the waste water heating heat exchanger. There, the temperature is raised by the heat of combustion in the incinerator 3, and it becomes heated gas.

A portion of this gas is sent from a duct 15 to the auxiliary fuel incineration burner 1 through a duct 16, and when the amount of gas is large, it is sent to the incinerator 3 through a duct 17 to incinerate the harmful substances contained therein.

On the other hand, the remaining heated gas is sent from the duct 115 to the incinerator 103 of the submerged combustion device via the valve 36 and is used as an oxygen-containing gas for incinerating the auxiliary fuel 12 and concentrated wastewater sent via the valve 35.

If there is insufficient combustion air considering the balance of the entire system, it is naturally necessary to supply it separately from the outside.

Further, the waste water may be incinerated with ordinary air 126, and the valve 36 may be closed to send all the water vapor saturated gas to the incinerator 3.

In this case, from the viewpoint of effective use of heat, it is better to use the steam-saturated waste gas as much as possible in the incinerator 3 and use the waste heat as high-temperature combustion gas.

By doing this, the temperature of the water vapor saturated waste gas can be made higher, so that even if the water vapor saturation temperature is increased, the combustion state can be maintained stably, and the concentration of the waste water can also be increased.

Now, the wastewater concentrated in the concentration tower 6 is sent from the bottom of the tower by a pump 9 through a valve 32 to a concentrated wastewater spray nozzle 102 of a submerged combustion type incinerator 103, where it is atomized by a spraying medium 120 to remove almost all the water vapor. Incinerated by saturated oxygen-containing waste gas.

At this time, in order to maintain the furnace temperature at a predetermined temperature (usually 800 to 1200 degrees Celsius) or maintain combustion stability, the auxiliary fuel 12 is passed through a valve 35 to an auxiliary burner 101 installed at the top of the incinerator 103. and is atomized by the atomizing medium 120 and combusted.

It goes without saying that in the case of gas fuel, this atomizing medium is not necessary.

Now, some of the molten ash, which is made up of inorganic salts obtained by incineration of concentrated wastewater, flows down the wall of the incinerator 103, and some of it is carried along with the combustion gas and is sent to the cooling recovery can 121.
It is collected as an aqueous solution or slurry and discharged as bottoms 122 to the outside of the system.

Note that 123 is makeup water for the liquid in the cooling recovery can 121.

The incineration waste gas, which is approximately saturated with water vapor at around 90'C and discharged from the cooling recovery can, passes through the duct 125 to the heat exchanger 10.
At step 5, heat is exchanged with the circulating waste liquid as described above, and then alkaline fumes, if any, are removed by a venturi scrubber or the like (not shown), and then released from the stack 7.

The condensed water in the heat exchanger 105 may be returned to the cooling recovery can 121 through the pipe 124 and reused.

As explained above, in this invention, wastewater containing volatile hazardous substances is concentrated and dehydrated using gas containing hazardous substances.
Since both of them are organically and effectively used as heat and completely incinerated, volatile harmful substances and harmful gases are not discharged outside the system, and at the same time it is possible to save on auxiliary fuel, thus preventing pollution. This is extremely effective and advantageous in terms of energy efficiency and energy saving.

Example 1 When wastewater containing sodium salts in addition to volatile organic substances is treated with waste gas containing harmful gases, the flow rate per unit time and properties of substances flowing through the main part of the drawing are as follows. Ta.

Incidentally, in order to treat the entire amount of waste gas in the incinerator 3 (that is, the valve 36 is closed), the combustion temperature is 800°C. Air for half-combustion is supplied to the incinerator 103 so that the air ratio is 1.2, and the incineration temperature is The temperature was 950°C.

Furthermore, if wastewater and waste gas are directly incinerated separately without concentrating wastewater with waste gas as in the present invention, approximately 782 kg/H for waste water and approximately 25 to 80 kg/H for waste gas.
/H (depending on preheating temperature) total 800-860k
A/H kerosene is required as auxiliary fuel.

Next, as an example where the wastewater does not contain ash, the valves 32, 34, 35, and 36 in the figure are closed.

Wastewater 10 containing volatile harmful substances is sent to the bottom of a countercurrent gas-liquid direct contact type concentrating tower 6, and is passed through a circulation pump 8 together with the concentrated liquid.
passes through valve 33 (valve 34 is closed)
After being heated by the heat exchanger 5 on the combustion gas outlet side of the incinerator 3, it becomes heated wastewater and flows from the heated wastewater pipe 13 to the concentration tower 6.
is introduced at the top of the tower.

On the other hand, waste gas (or contaminated air) 11 containing harmful substances is introduced into the bottom of the concentrating tower 6, and while rising in the tower, it comes into contact with the descending waste water, and volatile harmful substances and water vapor in the waste water are mixed into the waste gas. The wastewater is concentrated.

Note that 19 is auxiliary air to compensate for the lack of gas or oxygen if there is a shortage, and is sent to the lower part of the concentrating column 6 as necessary.

Water vapor saturated waste gas 14 containing sufficient oxygen necessary for combustion
is sent from the top of the concentration tower 6 to the gas heating heat exchanger 4 located behind the incinerator 3 and in front of the wastewater heating heat exchanger 5, where it is heated by combustion heat. , becomes heated gas and passes through duct 15 (valve 36 is closed).
Auxiliary fuel is sent to the burner 1 for incineration through a duct 16, and to the incinerator 3 for waste water incineration through a duct 17.

On the other hand, the concentrated wastewater is sent from the bottom of the concentration tower 6 by a pump 9 through a valve 31 (valve 32 is closed) to a wastewater spray nozzle 2, and is then sprayed by a spraying medium 20 such as steam or compressed air. and incinerated with the oxygen-containing gas.

At this time, auxiliary fuel 12 is sent to burner 1 and is sprayed and burned by spray medium 20 in order to maintain the furnace temperature at a predetermined temperature or maintain combustion stability.

It goes without saying that this atomizing medium is unnecessary in the case of gas fuel.

In this way, the concentrated waste water, volatile hazardous substances, gaseous hazardous substances, etc. are incinerated and become harmless combustion gas, and after the waste heat is effectively utilized, it is released from the stack 7 as harmless exhaust gas 18.

Example 2 When wastewater containing volatile organic matter and contaminated air containing trace amounts of aldehydes are treated by the above method, the flow rate per unit time and properties of the substances flowing through the main part are as follows. Ta.

The air ratio in the incinerator 3 was adjusted to 1.2,
The incineration temperature was 800°C.

If the above wastewater is directly incinerated without being concentrated, the fuel consumption will be approximately 130 kg/h, which is more than twice as much.

The above description and examples were conducted in the case where the wastewater does not contain inorganic substances such as alkali salts or organometallic compounds, and does not produce ash that is difficult to handle when incinerated.

In this case, the valves 32, 34, 35, 36, etc. in the figure are naturally closed for operation.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention. 1... Burner 2... Waste water spray nozzle, 3... Incinerator, 4, 5... Heat exchanger, 6... Concentration Tower, 7...Stack,
8...Circulation pump, 9...Pump, 1
0... Waste water, 11... Waste gas (or contaminated air), 12... Auxiliary fuel, 13...
・Heating waste water pipe, 14... Steam saturated waste gas, 1
5, 16, 17... Duct, 18...
Exhaust gas, 19... Auxiliary air, 20...
Spraying medium, 31-36...Valve, 1゜1...
... Auxiliary burner, 102 ... Concentrated waste water spray nozzle, 103 ... Submerged combustion incinerator, 10
5... Heat exchanger, 120... Spraying medium, 121... Each cooling recovery, 122...
Bottom liquid, 123...Supplementary water, 124...
・Pipe, 125...Duct.

Claims (1)

[Scope of utility model registration request] In equipment that simultaneously processes waste gas containing hazardous substances and waste water containing volatile hazardous substances, the waste gas containing hazardous substances is introduced from the bottom of the tower and comes into direct contact with heated waste water introduced from the top of the tower. A gas-liquid countercurrent contact concentration tower 6 for concentrating the wastewater by dissipating volatile harmful substances contained in the wastewater into the waste gas and also evaporating moisture into the coexisting gas. , a heat exchanger 4 for heating the waste gas for heating the waste gas containing the released volatile harmful substances and evaporated water with the combustion waste heat and then incinerating it.
and an incinerator 3 in which a heat exchanger 5 for heating waste water is placed in communication with an indirect exchanger 105 (described later) and a passage for waste water heated there, and a pump 9 and a valve 32 from the concentration tower 6.
A submerged combustion device 103 for incinerating the concentrated waste liquid sent to the waste liquid spray nozzle 102 in the upper part of the incinerator 3 through the incinerator 3, and a combustion device 1 for rapidly cooling the combustion waste gas generated here.
The cooling recovery canister 121 installed at the bottom of the 03 and the passage for the high-moisture-containing twisted combustion waste gas to be discharged from the tank are installed, and the wastewater is sent from the concentrating tower 6 via the pump 8 and the valve 34 using this gas as a heat source. A device for simultaneously treating waste water and waste gas, which includes the indirect heat exchanger 105 for heating.