JPS5898121A - Gas washing apparatus - Google Patents

Abstract

PURPOSE:To provide the titled apparatus carrying out the renewal of a washing liquid easily and properly, by detecting that the specific gravity of a tower bottom liquid reaches a predetermined value or more by a densitometer for monitoring the specific gravity of the tower bottom liquid attached to a scrubbing tower to operate a washing liquid renewing apparatus. CONSTITUTION:When the specific gravity of a tower bottom liquid 3 reaches a set value or more, a densitometer 22 transmits the detected value to a scrubbing liquid renewing apparatus 16 through a line 23 and the apparatus 16 performs the renewal operation of the tower bottom liquid 3 by the input signal therefrom. That is, a solenoid valve 20 is closed through a power line 19 and a solenoid valve 18 is opened through a power line 17 to carry out the discharge of the tower bottom liquid 3. In this case, a level gauge 14 detects such a state that the level of the tower bottom liquid 3 is lowered to a definite level through a signal line 15 to close the valve 18. At this time, a valve 20 is opened to supply a replenishing water 12 through a liquid level controller 19 to return the liquid amount of the tower bottom liquid 3 to the original amount. The tower bottom liquid 3 is diluted by this operation and NaClO (purifying chemical agent) is injected corresponding to the diluted position of said chemical agent by operating a concn. controller 8 to raise the concn. of the chemical agent to set concn. and the renewal operation of the tower bottom liquid 3 is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas cleaning device that circulates and cleans a solution containing a drug G as a cleaning liquid, and particularly to a gas cleaning device that renews the cleaning liquid by a batch method.

A conventional device of this type is shown in FIG. FIG. 1 is a flow diagram showing a conventional gas cleaning device. In the figure, (1) is a cleaning tower, and (2) is a gas-liquid-liquid 8! installed in this cleaning tower. l! A filling layer for carrying out (3
+ indicates the bottom liquid stored at the bottom of this packed layer, +41 and (5) indicate arrows indicating the inflow direction of the gas to be treated and the outflow direction of the process gas, (6) indicates the demister-1 (7). A circulation pump that circulates the bottom liquid t3+ over the horizontal layer (21), (8) a concentration controller that adjusts the total concentration of sodium hypochlorite in the bottom liquid (3), and (9) a circulation pump. A chemical dosing pump that injects a chemical into the liquid, 001 is a chemical tank, 01) is a power line for the chemical dosing pump (9), (121 is make-up water supplied to the washing tower (II), 03 is a bottom liquid (Adjust the amount of replenishment water 02+ on the liquid level adjustment side to maintain a constant g amount of 31.

(141 is the tower bottom liquid (level gauge of 31), (country is the signal line, (IQ is the cleaning liquid renewal device, aη is the power line for controlling the opening and closing of the t magnetic valve QS, and the output of the cleaning liquid renewal device (as a rule) do.

C9 is a power line for controlling the opening and closing of the solenoid valve (20) for make-up water (121), which also outputs more than the cleaning fluid renewal unit # (IQ). It's a drain.

Next, the operation will be explained. The NFC gas to be treated is pumped or sucked into the cleaning tower (11) while passing through the inner layer of the packing layer (2) in the direction of arrow +41, while being sent to the circulation pump (71) and sprayed into the packing layer. (2) comes into gas-liquid contact with the flowing cleaning liquid, and harmful components in the gas to be treated are absorbed and removed by the cleaning liquid.

Here, part of the moisture in the tower bottom liquid (3) evaporates during the process of cleaning the gas to be treated, and the liquid volume gradually decreases. make-up water (12
1 was injected, and the g amount was always kept constant.

In addition, the chemicals in the bottom Q (3+) also disappear during the process of absorbing and removing harmful components, so the circulation pump (7) pumps the chemicals into the T
A part of the washed washing liquid is led to the concentration controller (8), and the concentration of sodium hypochlorite in the tower bottom liquid (3+) is monitored.
The injection amount of the sodium hypochlorite stock solution in the chemical tank QOI is controlled by starting and stopping the chemical injection pump (9), and the sodium hypochlorite in the tower bottom liquid (3) is maintained at a constant concentration.

Now, the case of cleaning and removing odor components discharged from each treatment process of a human waste treatment plant or a sewage treatment plant will be explained.

In this case, each odor component in the gas to be treated, that is, ammonia, hydrogen sulfide, methyl mercaptan, methyl sulfide, methyl disulfide, etc., is absorbed by hypochlorous acid while passing through the packed layer (2). ) It is absorbed and removed by contacting with a cleaning solution containing all IJium, and the chemical reaction at this time is shown by the following equation.

2NH3+3NaC40-+ N2+3NaCl+3H
203H2S +6N a CI O+, 2N aOH
−+Na 2 Sot + 6Na C1l +2 S
+4H20CH3SH+3Na(JO+NaOH-+
CH35o3Na +3NaCA! 10H20 (CH
s ) S + NaC, d O → (CHs ) So
10NaCl(CH3)2S2 +5NaClO+ 2N
aOH-+ 2CH3S O3N a+5Nacl+H20 In this way, the odor in the gas to be treated is removed from the packing layer (
2+, and further passes through a demister (61) to remove the accompanying cleaning liquid mist, and then is discharged as a process gas through a cleaning tower (11) as shown by an arrow (51).

On the other hand, sodium sulfate produced by absorption and removal by the cleaning solution,
Sodium methanesulfonate, dimethyl sulfoxide, and hypochlorous acid that acts to remove the above-mentioned odor components)
Sodium chloride and the like, which are waste products of IJ, remain in the cleaning solution and gradually accumulate. Here, if the cleaning liquid is alkaline, carbon dioxide gas in the gas to be treated is also absorbed according to the following formula, and is accumulated as carbonates during n1 cleanings n
Ru.

CO2+ NaOH-+ NaHCO3CO2+2Na
OH-+ Na2CO3+H20 Figure 2 shows this type of washing 1
The fk' of the '41 column shows the solubility curve of typical reaction products found in the purified liquid. Although it is difficult to generalize that the solubility differs depending on each substance, from Figure 2, the concentration of the component of 'CNZON is around room temperature, Fi8~20 (Wt), 0.
If the concentration exceeds 4 to 7 (wt%) near ℃, the solute will precipitate and problems such as clogging will occur in various parts, according to the predicted formula n.
Ru. For this reason, it is necessary to periodically renew the cleaning liquid.

Conventionally, a cleaning liquid renewal device (16
) was activated periodically to execute fL. In other words, when the preset time is reached, the cleaning fluid renewal device (1
6) The power output from the tower opens the solenoid valve (fi (31) through the power line 0'7) and is discharged through the drain Qυ.Then, this fL is simultaneously connected to the power line a9 by the The power that was flowing stopped, the solenoid valve (20) was closed, and the makeup water (
One case of +21 water supply at the bottom of the tower* (facilitates the discharge of 3+.

At the point where the level of the tower bottom W (31 has dropped to a certain depth 1), the level gauge 04 detects the bottom f'L,
Signal line (depending on the country?\Ig update/device α)
The power that opened the solenoid valve a barrel stops, and the solenoid valve (20)
is re-energized and unfolds. Then, water is supplied again via the liquid level controller Q31ffi, and the supply of water stops when the water level rises at the original level box. In this way,
Conventionally, the washing liquid was renewed by diluting the column bottom liquid (3+) with make-up water (121).

Conventional gas cleaning equipment is configured as described above, so the update interval for the tower bottom liquid (3+) can be predicted in advance through theoretical calculations, confirmed through trial runs, and set to be on the safe side. Therefore, it was necessary to shorten the update interval.As a result, it took time to set the update interval, and in order to set the update interval on the safer side, the chemical solution was discharged unnecessarily, resulting in wasted chemical solution. there were.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional ones.The washing tower is equipped with a hydrometer that monitors the total specific gravity of the bottom liquid, and this hydrometer measures the specific gravity of the bottom liquid. It is an object of the present invention to provide a gas cleaning device that can easily and continuously renew the cleaning fluid by operating the cleaning fluid renewal device when the gas exceeds a set value.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a flowchart showing the entire gas cleaning apparatus according to an embodiment of the present invention. In the figure, (1) or sail indicates a portion corresponding to the same size as that in FIG. 1. (221 is the bottom i + 3
The hydrometer (c) is used to monitor all changes in the specific gravity of 1. (c) is sent to the bottom of the column g (when it detects that the specific gravity of 3+ has exceeded the preset r value, it is sent to the washing liquid renewal device 06). This is a signal line for transmission.

FIG. 4 shows the relationship between the aqueous solubility of typical reaction products produced in the cleaning solution and the specific gravity of the solution. Fourth
As is clear from the figure, when the odor discharged from human waste treatment plants and sewage treatment plants is absorbed and removed by sodium hypochlorite cleaning, the solution specific gravity of the typical reaction products generated in the cleaning solution. is so f' in the concentration range of 1 to 10.
It can be seen that the concentration of the aqueous solution, which has a linear relationship with L and shows the same specific gravity of each component, falls within ±20 degrees of the intermediate value. For example, the minimum aqueous solution concentration exhibiting a solution specific gravity of 1.04 is 4.2% of sodium carbonate, and the maximum aqueous solution concentration exhibiting a solution specific gravity of 1.04 is 6% of sodium chloride. Therefore, the intermediate value is 5.1, and the aqueous solution concentration of each n is ±0 with respect to the intermediate value of 5.1.
This results in a concentration range of 9%.

In this way, the concentration of each aqueous solution exhibiting the same specific gravity falls within a range of ±20% with respect to the median value of 5.1%. Therefore, if this is utilized, it is possible to know the average concentration of each component in the bath liquid by measuring the specific gravity after cleaning, and it is thereby possible to accurately know when to renew the cleaning liquid.

In Fig. 3, a hydrometer (221) indicates the specific gravity of the solution at the bottom of the tower (m). The cleaning liquid renewal device 06) executes the renewal operation of tower bottom ff (31), that is, the solenoid valve C is connected via the power line (1ω).
Close a and connect the power line (1η to solenoid valve 08)
Open the column bottom liquid (3,
The level gauge (14) detects via the signal line Q51 that the 3+ surface has dropped to a certain level 1, closes the solenoid valve [+8] and opens the solenoid valve (20e) to control the supply of makeup water to the liquid level controller. 03) and the bottom liquid (3
The + liquid level will return to its original level. Then, the tower bottom g (3J is diluted), the diluted amount of sodium hypochlorite is calculated by the action of the concentration controller (8), and the sodium hypochlorite concentration is adjusted to the set rate. The update operation of tower bottom wL (3i is completed.

The cleaning liquid renewal device 0ω is the ratio m# (2 way signal line f23)
Once the input has been obtained through full valve operation, a protection circuit must be installed to prevent the signal from the angular hydrometer (221) from being input until the time for completing the update operation has elapsed. It is desirable to have a circuit configuration that allows smooth supply of water.

In addition, in the above embodiment, a cleaning device using sodium hypochlorite as the cleaning liquid was explained, but this is limited to nK.
gas cleaning equipment that uses other chemical solutions, such as sulfuric acid, hydrochloric acid, sodium hydroxide, hydrogen peroxide, potassium permanganate, sodium chlorite, sodium hypobromite, and sodium thiosulfate. The present invention may be applied to a gas cleaning device that uses a water bath liquid containing one or more types of water bath liquid as a cleaning liquid, and the same effects as those of the above embodiments can be obtained.

Further, in the above embodiment, the method of automatically measuring the specific gravity of the bath liquid at the bottom of the column M (31) was explained, but the specific gravity of the solution may be measured manually, and based on the results, the washing liquid renewal device α0 may be operated manually. The same effect as above is achieved.

As described above, according to the present invention, since the specific gravity of the cleaning liquid is measured and the cleaning liquid is renewed, the cleaning liquid is not discharged unnecessarily as in the conventional device, and the cleaning liquid is removed by cleaning. This prevents the components from becoming more concentrated than expected, resulting in reaction products accumulating and causing trouble due to crystal precipitation.

Additionally, the amount of supplementary water can be kept to a minimum, which helps save energy.

[Brief explanation of the drawing]

Figure 1 is a flow diagram showing a conventional gas cleaning device, Figure 2 is a solubility curve diagram of the reaction products that accumulate in the cleaning solution when sodium hypochlorite is used to clean sewage equipment, and Figure 3 is FIG. 4 is a flowchart showing a gas cleaning apparatus according to an embodiment of the present invention, and is a relationship curve diagram between the water bath g concentration of the reaction product accumulated in the cleaning liquid and the solution specific gravity. In the figure, (I) is a cleaning tower, (2+ is a packed layer, +31 is a bottom liquid, (4) is an arrow indicating the inflow direction of the gas to be treated, (5)
J is an arrow indicating the outflow direction of the processing gas, (6) is demister-1 (711W is a circulation pump, (8) is a concentration controller, (
9) is the chemical injection pump, is the signal line, (16) is the cleaning fluid renewal device, (18) and (20) are the solenoid valves, CD is the drain,
(22) is a hydrometer. In the drawings, the same reference numerals indicate parts corresponding to the same straddle. Agent Shin Tameno - (1 other person) (Ill Figure 2)

Claims (2)

[Claims] (1) A gas cleaning device that circulates and cleans a solution containing a chemical solution for removing harmful components from a gas to be treated as a cleaning liquid, including a cleaning liquid renewal device that detects a change in the specific gravity of the cleaning liquid and updates the cleaning liquid. A gas cleaning device featuring: (2) The gas according to claim 1, which is equipped with a hydrometer that detects a change in the specific gravity of the cleaning liquid, and a cleaning liquid renewal device that automatically updates the cleaning liquid by detecting the change in the specific gravity. cleaning equipment. (3+ cleaning solutions include sodium hypochlorite, sulfuric acid, hydrochloric acid, sodium hydroxide, hydrogen peroxide, potassium permanganate,
3. The gas cleaning device according to claim 1 or 2, which is an aqueous solution containing one or more agents selected from sodium chlorite, sodium hypobromite, and sodium thiosulfate.