KR0132741B1 - A waste water disposal apparatus - Google Patents

Abstract

The present invention is an incinerator (2) for pyrolyzing waste liquid at a high temperature to treat waste liquid, an exhaust heat recovery device (3) for recovering heat of exhaust gas from the incinerator (2) as steam, and waste liquid in the incinerator (2). A heat exchanger (5) installed in a waste liquid line (4) for supplying water to increase the temperature of the waste liquid by steam from the discharge heat recovery device (3), and the waste liquid whose temperature is increased in the heat exchanger (5). Flash drum 6 for flashing to separate gas and liquid, and a portion of the liquid separated from the flash drum 6 is returned to the waste line 4 upstream of the heat exchanger 5 in the heat exchanger 5 The waste liquid treatment apparatus characterized by comprising a circulation means (7) for preventing the evaporation of the waste liquid in the present invention can effectively utilize the heat of exhaust when the waste liquid is thermally decomposed.

Description

Waste Liquid Treatment Device

1 is a block diagram showing an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

2: incinerator 3: exhaust heat recovery system

4: waste liquid line 5: heat exchanger

6: flash drum 7: circulation means

The present invention relates to a waste liquid treatment apparatus.

In the waste liquid, waste acid below PH2, waste alkali above PH11, sulfonic acid chloride (waste solution in semiconductor factory), waste fluid in chemical factory (waste solution by whitening and alkali injection when mixed with water), boiler washing water, waste in printing factory (PCB), leather manufacturing There are various kinds of waste liquids such as factory waste liquid, medical plant waste liquid, cyan hexavalent chromium 1 Zn plating waste liquid (including Cu), laboratory waste liquid, solvent-containing waste liquid, and the like. There exists a method of using various chemical agents, such as a polymer flocculant. This is a method of injecting various chemicals into the waste liquid to coagulate and precipitate the inorganic substances and polymer compounds in the waste liquid layer, and remove the solids by using a concentration tank to release only the liquid. However, in the case of treating the waste liquid using the above-mentioned chemical agent, since the inorganic substance and the polymer compound, etc. are used as the solid content by the chemical agent and are not separated and removed, a processing apparatus and a device for solid content such as a storage tank are required. And complicated equipment and high equipment cost.

The waste liquid treatment which does not cause such a problem is to evaporate the waste liquid and open it to the atmosphere, but this causes air pollution. Moreover, although it is proposed to thermally decompose (oxidize) the waste liquid by supplying it to an incinerator, in this case, how to utilize the heat of the exhaust gas from the incinerator is a problem. Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a waste liquid treatment apparatus which can effectively use the heat discharged when the waste liquid is pyrolyzed. In order to achieve the above object, the waste liquid treatment apparatus of the present invention is an incinerator in which waste liquid is thermally decomposed at high temperature to perform waste liquid, an exhaust heat recovery apparatus for recovering heat of exhaust gas from the incinerator as steam, and supplying waste liquid to the incinerator. A heat exchanger installed in a waste liquid line to raise the temperature of the waste liquid by steam from the discharge heat recovery device, and a flash drum to separate the gas and the liquid by flashing the waste liquid whose temperature is increased in the heat exchanger. drum and a portion of the liquid separated from the flash drum are returned to the waste liquid line upstream of the heat exchanger to prevent evaporation of the waste liquid in the heat exchanger.

The waste liquid is fed from the waste line to the incinerator and pyrolyzed there. The exhaust gas from the incinerator is recovered as steam by the exhaust heat recovery system. This steam is transmitted to the heat exchanger as a heat medium to raise the waste liquid temperature.

In this heat exchanger, a part of the liquid separated from the flash drum is returned by the circulation means to prevent evaporation of the waste liquid in the heat exchanger, and the vapor from the exhaust heat recovery device is increased due to the high pressure and the circulating amount is extremely high. Even if the temperature of the waste liquid is raised, the waste liquid does not evaporate. For this reason, when the waste liquid evaporates in the heat exchanger, the waste liquid can be raised in temperature without the side effect of the scale adhering to the heat transfer pipe, and the exhaust heat can be effectively used.

EXAMPLE

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a waste liquid treatment apparatus, and the waste liquid treatment apparatus 1 is a waste incinerator 2 for thermally decomposing waste liquid at a high temperature to process waste liquid, and the discharge gas from the incinerator 2. A waste heat recovery device (3) for recovering heat as steam, and a waste liquid line (4) for supplying waste liquid to the incinerator (2) to adjust the temperature of the waste liquid by steam from the exhaust heat recovery device (3). The heat exchanger 5 to raise, the flash drum 6 which flashes the waste liquid which raised the temperature in the heat exchanger 5, and separates it into a gas and a liquid, and a part of the liquid isolate | separated from the flash drum 6 It mainly consists of circulation means 7 which return to the waste liquid line 4 upstream of the heat exchanger 5 and prevent evaporation of the waste liquid in the heat exchanger 5. The waste liquid is stored in the waste liquid tank 8, and most of the waste liquid in this tank 8 is adjusted to PH 7-8 by mixing a plurality of waste liquids. The waste liquid tank 8 is connected with a waste liquid line 4 for supplying waste liquid to the incinerator 2. The waste liquid line 4 is connected with a waste liquid pump 9, a heat exchanger 5, and a flash drum 6 sequentially. It is installed. The flash drum 6 is configured to separate a gas from a liquid by evaporating a part of the waste liquid, and a waste gas line 10 into which the separated gas flows and a liquid line 11 into which the liquid flows are connected.

Incinerator (2) is a long cylindrical type, the fireproof material 12 is coated inside, the center portion is narrowed (slot portion is formed), incinerator (2) inside the incinerator 2 stages (top: liquid incinerator 2a, bottom) : Gas incinerator 2b). On the upper side of the incinerator 2 (upper side of the liquid incinerator 2a), a plurality of (for example, four) first gas burners 13 are provided at predetermined intervals (for example, at 90 ° intervals) around them. In the upper portion of the gas incinerator 26, a plurality of (e.g. four) second gas burners 14 are provided at predetermined intervals (e.g., 90 DEG intervals) around them. The waste gas line 10 is connected to the first and second gas burners 13 and 14, and the vapor evaporated from the flash drum 6 to the liquid incinerator 2a and the gas incinerator 2b is incinerator. (2) It is to be sucked in to cause swirl flow. One or more liquid burners 15 are provided on the upper side of the incinerator 2 (above the liquid incinerator 2a), and the liquid line 11 is connected to the liquid burner 15, and the flash The liquid (waste liquid) from the drum 6 is sucked into the liquid incineration section 2a.

In addition, two fuel burners 16 are provided at the top of the incinerator 2. In the example shown in FIG. The fuel burner 16 is connected to a heavy oil tank 17, a heavy oil line 19 having a heavy oil pump 18 is connected, and an air line 21 having an air fan 20 is connected thereto. Is sucked into the incinerator 2 from the fuel burner 16 and combusts, and the waste liquid is thermally decomposed (oxidized) by the combustion. The incinerator 2 is equipped with a temperature detector 22 for measuring the temperature in the slot portion at the slot portion thereof, and the incinerator is configured from the gas temperature measurement value of the detection value from the detector 22 and the exhaust gas from the incinerator 2. (2) A temperature controller 23 for adjusting the temperature in the liquid incineration portion 2a and the gas incineration portion 2b is provided. The temperature controller 23 mainly adjusts the injection amount of heavy oil or the like from the fuel burner 16 and the injection amount from the second gas burner 14 to adjust the temperatures of the liquid incinerator 2a and the gas incinerator 2b, respectively. It is configured to maintain the predetermined temperature (or temperature range). That is, the temperature controller 23 is capable of adjusting the liquid incineration portion 2a and the gas incineration portion 2b to an arbitrary temperature. For example, the temperature of the liquid incineration portion 2a at a high temperature of about 1200 ° C or higher, The downstream gas incineration section 2b is set to about 800-870 占 폚. This is because when a part of the waste liquid is evaporated in the flash drum 6, it is almost water to evaporate, and the flammables such as glycene and ash remain in the liquid side, so that the liquid incineration part is caused by the combustion of the liquid and the steam. The temperature in (2a) is adjusted to about 1200 degreeC or more, and the temperature in the gas incineration part 2b is adjusted to about 850 degreeC by steam of about 100 degreeC from the 2nd gas burner 14, for example. As a result, the vapor from the second gas burner 14 acts as a coolant.

The lower part of the incinerator 2 is connected with an exhaust gas line 25 for guiding combustion exhaust gas to the chimney 24. In addition, since the combustion exhaust gas flowing into the exhaust gas line is small in quantity but contains ash and the like, the ash may be separated from the incinerator separately. The exhaust gas line 25 is provided with a boiler 3, a cyclone 26, a cooler 27, a blower 28, and a bag filter 29 in order, and the pressure of the exhaust gas is sequentially provided. The damper 30 provided downstream of the air blower 28 is suitably adjusted. In this way, the treatment of the exhaust gas is carried out dry to prevent white smoke and to save water. The boiler 3 is a heat recovery boiler known in the art, and is configured to cool the exhaust gas from, for example, 850 ° C to 300 ° C to generate steam. It is supplied to (5). The circulating line 31 connected to the liquid line 11 is connected to the waste liquid line 4 upstream of the heat exchanger 5. A circulation pump 32 is installed in the circulation line 31 to constitute a circulation means 7, and a part of the liquid separated from the flash drum 6 is returned to the waste liquid line 4 by the circulation pump 32. It is meant to be built. This circulation amount is set so that the temperature rise of the waste liquid in the heat exchanger 5 will be about 5-15 ° C so that the waste liquid does not evaporate in the heat exchanger 5. Next, the operation of the embodiment will be described. The waste liquid from the waste tank 8 enters the heat exchanger 5 at a temperature of about 20 ° C. to 105 ° C., for example, by mixing the waste liquid from the circulation line 31, where steam from the boiler 3 is introduced. The temperature rises to about 120 ° C. After the temperature rises, it enters the flash drum 6 and depressurizes there, and part of it evaporates. The evaporated gaseous fraction (vapor) flows into the waste gas line 10 to reach the incinerator 2 and a part of the liquid fraction reaches the incinerator 2 via the liquid line 11.

Heavy oil is injected from the fuel burner 16 into the liquid incinerator 2a of the incinerator 2 and burned by oxygen in the air, and waste liquid is injected from the liquid burner 15 to be thermally sprayed (oxidized). In the gas incinerator 2b, steam is injected from the second gas burner 14 to be pyrolyzed (oxidized). That is, in the incinerator 2, two-stage combustion occurs in the liquid incineration portion 2a and the gas incineration portion 2b, and the liquid incineration portion 2a in the first stage is maintained at about 1200 ° C or more, where the flash drum The waste liquid which has not evaporated in (6) is burned, and steam from the flash drum is supplied to both the liquid incineration section 2a and the gas incineration section 2b and subjected to heat treatment. In this way, the waste liquid which has not evaporated in the flash drum 6 is burned in the liquid incineration section 2a of about 1200 ° C. or more, thereby treating solids and cyan compounds (containing metals) contained in the waste liquid. Solids in the waste liquid decompose at 1200 ° C. In addition, the cyan compound (heavy metal) burns at 900 ° C or higher. In addition, ash is generated in the liquid incineration portion 2a, and the ash is molten at about 950 ° C or higher, but the ash flows from the liquid incineration portion 2a to the gas incineration portion 2b at about 850 ° C. It becomes unmelted. For this reason, even if this ash flows into the boiler 3, it adheres to the heat transfer surface of the boiler 3, and does not cause fixing of a boiler.

The combustion exhaust gas from the incinerator 2 is cooled in the boiler 3, for example, from 850 ° C to 300 ° C, collected in the cyclone 26, and cooled again to 250 ° C in the cooler 27. After the slaked lime is neutralized through the exhaust fan 28 and neutralized, it is collected again by the bag filter 29 and discharged from the chimney 24 to the atmosphere. That is, the combustion exhaust gas is heat-recovered in the boiler 3, and is cooled to near the heat resistance temperature (about 200 ° C) of the bag filter 29 and discharged to the atmosphere. The ash including heavy metals collected by the cyclone 26 and the bag filter 29 is transferred to a treatment system such as separate regeneration or disposal. In the boiler 3, steam is generated by heat recovery, and the steam is supplied to the heat exchanger 5 as a heating medium for raising the temperature of the waste liquid, and after the temperature of the waste liquid is raised, the flow returns to the boiler 3. In this way, since the heat of the exhaust gas is used to raise the temperature of the waste liquid through the steam, the heat of recovery can be self-consumed 100%. At this time, since the liquid (waste liquid) separated from the flash drum 6 flows into the heat exchanger 5 together with the waste liquid from the waste tank 8, evaporation of the waste liquid in the heat exchanger 5 is prevented. Adhesion of the scale in group 5 can be suppressed. In other words, if the heat amount of steam from the boiler 3 rises only in the waste liquid from the waste tank 8, the heat is evaporated to a part of the waste liquid. Therefore, the steam is added to the temperature rise of only the waste liquid from the waste tank 8. If used, part of the waste liquid evaporates in the heat exchanger (5). This evaporation causes the scale to adhere to the heat transfer tube of the heat exchanger 5, resulting in failure. For this reason, by circulating a part of the liquid separated from the flash drum 6 through the circulation line 31, the heat transfer load in the heat exchanger 5 is increased to increase the amount of circulation, thereby securing the required amount. It becomes possible.

As a result, when the circulation amount is set to suppress the temperature rise to about 5-15 ° C. so that the waste liquid does not evaporate, the pressure is high and the circulation amount becomes extremely large with respect to the evaporation amount, so that the adhesion of the scale in the heat exchanger 5 can be suppressed. . For this reason, descale work becomes easy.

As a result, even if the waste liquid is raised in temperature by the steam from the boiler 3, adhesion of the scale in the heat exchanger 5 is suppressed, so that failure of the scale does not occur, and 100% of the heat of recovery can be consumed. Can be used effectively. According to the above invention, the outstanding effect that the waste heat at the time of thermally decomposing waste liquid can be utilized effectively.

Claims (1)

The incinerator (2) for pyrolyzing the waste liquid at high temperature to treat the waste liquid, the exhaust heat recovery device (3) for recovering the heat of the exhaust gas from the incinerator (2) as steam, and the waste liquid for supplying the waste liquid to the incinerator (2) A heat exchanger (5) installed in the waste liquid line (4) to raise the temperature of the waste liquid by the steam from the discharge heat recovery device (3), and flash the waste liquid whose temperature is raised by the heat exchanger (5). The flash drum 6 separating the liquid and a part of the liquid separated from the flash drum 6 are returned to the waste liquid line 4 upstream of the heat exchanger 5, and the waste liquid in the heat exchanger 5 is returned. Waste liquid treatment apparatus, characterized in that consisting of a circulation means for preventing evaporation (7).