Automatic acid and alkali adding neutralization method and device for wastewater neutralization pool

Abstract

The invention relates to the field of wastewater discharge, in particular to an automatic acid and alkali adding neutralization method and device for a wastewater neutralization pool. The method comprises the following steps: S1, putting an accumulated acid adding statistic module and an accumulated alkali adding statistic module, and carrying out zero clearing on the two modules; s2, putting into an automatic neutralization module, and automatically calculating the volume amount of added acid or alkali required by neutralization; s3, an automatic neutralization module performs correction on the basis of the calculated volume of the added acid or alkali to obtain an actual addition value of the acid liquor or the alkali liquor; s4, controlling the liquid outlet amount of the acid liquid or the alkali liquid by an automatic neutralization module, and neutralizing the waste liquid in the neutralization tank; s5, after the neutralization tank continues to circulate for half an hour, if the pH value is not qualified, returning to the step S2, and repeating the operations of the steps S2 to S4 by the automatic neutralization module; if the pH value is qualified, the neutralization operation is completed. Accurate acid adding and alkali adding can be achieved according to the water amount and the pH value of the neutralization pool, the situation of excessive acid adding and alkali adding is effectively avoided, and rapid acid-alkali neutralization of the wastewater neutralization pool is achieved.

Description

Technical Field

[0001] The invention relates to the field of wastewater discharge, and in particular to a method and a device for automatically adding acid and alkali to a wastewater neutralization tank. Background Art

[0002] The main function of acid and alkali neutralization in the wastewater neutralization tank is: the wastewater neutralization tank is used to receive industrial wastewater from the system. Before the received wastewater is discharged, the pH value of the wastewater needs to be adjusted to the range of 6.2-8.8 to meet the relevant regulations before it is allowed to be discharged.

[0003] The neutralization system of the wastewater neutralization tank is mainly divided into an acid-adding device and an alkali-adding device. When the pH is less than 7, the wastewater is acidic and needs to be neutralized by adding alkali solution; when the pH is greater than 7, the wastewater is alkaline and needs to be neutralized by adding acid solution. The discharge water pump needs to be started all the time to recirculate and mix the wastewater during the whole process.

[0004] The neutralization process of the wastewater neutralization tank is affected by the layout of pipelines and sampling pipelines. The pH value during the neutralization process cannot accurately reflect the actual pH value of the current wastewater neutralization tank in real time. Generally, it takes a certain amount of time to stir the pH to reach equilibrium. The stirring time is related to the recirculation flow and the layout of the circulation pipeline, and generally takes more than half an hour. The sampling pipeline is generally arranged in the pump outlet pipeline. When the acid and alkali adding pipeline is far away from the pump inlet pipeline, the acid and alkali neutralizing liquid needs to diffuse to the pump suction port after a certain period of time, resulting in a lag in the pH meter display. If the qualified pH value is added, it will cause excessive acid and alkali addition; when the acid and alkali adding pipeline is close to the pump inlet pipeline, the acid and alkali neutralizing liquid immediately diffuses to the pump suction port, while other places in the neutralization tank have not been neutralized, resulting in an advance in the pH display. If the qualified pH value is added, the dosage is insufficient and multiple additions are required. According to the pipeline layout, the current methods of adding acid and alkali to the wastewater neutralization tank are mainly:

[0005] 1. Stop adding acid or alkali when pH reaches a certain value according to experience. It is difficult to master the experience value and critical point of this method, and automatic dosing cannot be achieved, which is easy to over-dosage or under-dosage.

[0006] Second, add a small amount of acid and alkali each time and stir in a cycle, then add acid and alkali quantitatively according to the pH value and stir in a cycle. Since the pH value changes exponentially with the amount of acid and alkali added, if the amount added each time remains unchanged, multiple additions are required in the early stage, and the pH value does not change significantly. The addition time is too long, and the amount of addition required in the later stage is small. Quantitative addition is prone to excessive addition. In addition, this method does not consider the impact of the total amount of wastewater on the amount of acid and alkali added.

[0007] The above two methods do not count the dosage, which is not conducive to the statistics of acid and alkali losses. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a method and device for automatically adding acid and alkali to a wastewater neutralization tank, with accurate acid and alkali dosage, thus realizing rapid acid and alkali neutralization in the wastewater neutralization tank.

[0009] The present invention provides a method for automatically adding acid and alkali to neutralize wastewater in a neutralization tank, comprising the following steps:

[0010] Step S1: Invest in a cumulative acid addition statistics module and a cumulative alkali addition statistics module, and reset the two modules;

[0011] Step S2: putting the automatic neutralization module into operation to automatically calculate the volume of acid or alkali required for neutralization;

[0012] Step S3: the automatic neutralization module makes corrections based on the calculated volume of acid or alkali to obtain the actual added value of acid or alkali;

[0013] Step S4: the automatic neutralization module controls the output of the acid solution or the alkali solution to neutralize the waste liquid in the neutralization tank;

[0014] Step S5: After the neutralization tank continues to circulate for half an hour, if the pH value is unqualified, it returns to step S2, and the automatic neutralization module repeats the operations of steps S2 to S4; if the pH value is qualified, the neutralization operation is completed.

[0015] In a specific embodiment of the present invention, step S2 specifically includes the following steps:

[0016] Automatically calculate the amount of water in the neutralization tank according to the liquid level in the neutralization tank;

[0017] Automatically start the drainage pump to circulate for half an hour;

[0018] The volume of acid or alkali required for neutralization is automatically calculated based on the calculated water volume and pH value in the pool.

[0019] In a specific embodiment of the present invention, in step S3, the correction method is:

[0020] Multiply the calculated volume of acid or base added by a coefficient between 0 and 1.

[0021] In a specific embodiment of the present invention, the coefficient is 0.5-0.7.

[0022] In a specific embodiment of the present invention, the coefficient is 0.6.

[0023] In a specific embodiment of the present invention, step S4 specifically includes the following steps:

[0024] The automatic neutralization module calculates the descending liquid level of the acid neutralization metering tank or the alkali neutralization metering tank according to the actual addition value of the acid or alkali solution;

[0025] Automatically control the addition of acid or alkali, and stop when the addition reaches the calculated drop level;

[0026] The dosage is accumulated into the corresponding acid addition statistics module or alkali addition statistics module.

[0027] The present invention provides a device for automatically adding acid and alkali to a wastewater neutralization tank, comprising:

[0028] The cumulative acid addition statistics module is used to record the amount of acid added;

[0029] The cumulative alkali addition statistics module is used to record the amount of alkali solution added;

[0030] The automatic neutralization module is used to automatically calculate the amount of acid or alkali required for neutralization and control the addition of acid or alkali into the neutralization tank.

[0031] Compared with the prior art, the method and device for automatically adding acid and alkali to neutralize wastewater in the neutralization tank of the present invention has the following beneficial effects:

[0032] (1) Acid and alkali can be accurately added according to the water volume and pH value of the neutralization pool, effectively avoiding excessive acid and alkali addition and effectively reducing the loss of neutralization acid and alkali;

[0033] (2) Rapid acid-base neutralization in the wastewater neutralization tank is achieved;

[0034] (3) Since the amount of acid and alkali required to be added changes exponentially when the pH value of the wastewater neutralization tank changes, the method for automatically adding acid and alkali to the wastewater neutralization tank of the present invention can achieve the function of adding more acid and alkali at the beginning and less acid and alkali later;

[0035] (4) Because the automatic dosing stop point is when the dosing amount reaches the dosing amount calculated by the system based on the initial pH, it is not affected by pH fluctuations during the dosing process. Therefore, the influence of the layout of the circulation pipeline, acid and alkali dosing pipeline, etc. on neutralization can be reduced;

[0036] (5) The logic of automatic acid and alkali addition for neutralization is simpler, and the amount of acid and alkali added is more convenient to count. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram showing the structure of a neutralization device in a wastewater neutralization tank;

[0038] In the figure, 1-wastewater neutralization tank; 2-wastewater inlet valve; 3-acid addition valve; 4-acid neutralization metering box; 5-acid inlet valve of acid metering box; 6-alkali addition valve; 7-alkali neutralization metering box; 8-alkali inlet valve of alkali metering box; 9-first drainage pump; 10-second drainage pump; 11-circulation valve; 12-discharge valve; 13-pH meter. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0040] An embodiment of the present invention discloses a method for automatically adding acid and alkali to neutralize wastewater in a neutralization tank, comprising the following steps:

[0041] Step S1: Invest in a cumulative acid addition statistics module and a cumulative alkali addition statistics module, and reset the two modules;

[0042] Step S2: putting the automatic neutralization module into operation to automatically calculate the volume of acid or alkali required for neutralization;

[0043] The specific steps include:

[0044] Automatically calculate the amount of water in the neutralization tank according to the liquid level in the neutralization tank;

[0045] Automatically start the drainage pump to circulate for half an hour;

[0046] The volume of acid or alkali required for neutralization is automatically calculated based on the calculated water volume and pH value in the pool.

[0047] Step S3: the automatic neutralization module makes corrections based on the calculated volume of acid or alkali to obtain the actual added value of acid or alkali;

[0048] The correction method is:

[0049] Multiply the calculated volume of acid or base added by a coefficient between 0 and 1.

[0050] The coefficient is preferably 0.5 to 0.7, more preferably 0.6.

[0051] Step S4: the automatic neutralization module controls the output of the acid solution or the alkali solution to neutralize the waste liquid in the neutralization tank;

[0052] The specific steps include:

[0053] The automatic neutralization module calculates the descending liquid level of the acid neutralization metering tank or the alkali neutralization metering tank according to the actual addition value of the acid or alkali solution;

[0054] Automatically control the addition of acid or alkali, and stop when the addition reaches the calculated drop level;

[0055] The dosage is accumulated into the corresponding acid addition statistics module or alkali addition statistics module.

[0056] Step S5: After the neutralization tank continues to circulate for half an hour, if the pH value is unqualified, it returns to step S2, and the automatic neutralization module repeats the operations of steps S2 to S4; if the pH value is qualified, the neutralization operation is completed.

[0057] The embodiment of the present invention also discloses a device for automatically adding acid and alkali to a wastewater neutralization tank, comprising:

[0058] The cumulative acid addition statistics module is used to record the amount of acid added;

[0059] The cumulative alkali addition statistics module is used to record the amount of alkali solution added;

[0060] The automatic neutralization module is used to automatically calculate the amount of acid or alkali required for neutralization and control the addition of acid or alkali into the neutralization tank.

[0061] The device for automatically adding acid and alkali to the wastewater neutralization tank of the present invention also includes the neutralization device of the existing wastewater neutralization tank. Figure 1 As shown. The normal neutralization process of the wastewater neutralization tank is as follows: when the water level in the wastewater neutralization tank 1 reaches a certain level and needs to be discharged, close the wastewater inlet valve 2, confirm that the discharge valve 12 is closed, open the circulation valve 11, and start the first drainage pump 9 or the second drainage pump 10. At this time, the wastewater in the wastewater neutralization tank is mixed, and the pH meter 13 displays the pH value. Acid and alkali are added according to the pH value. When the pH is less than 7, alkali needs to be added. When adding alkali, open the alkali adding valve 6, and the alkali solution in the alkali neutralization metering box 7 enters the wastewater neutralization tank 1. When the alkali level in the alkali neutralization metering box 7 is low, open the alkali inlet valve of the alkali neutralization metering box 8 to supplement alkali. When the pH is greater than 7, acid needs to be added. When adding acid, open the acid adding valve 3, and the acid solution in the acid neutralization metering box 4 enters the wastewater neutralization tank 1. When the acid level in the acid neutralization metering box 4 is low, open the acid inlet valve 5 of the acid neutralization metering box to supplement acid. When the pH is qualified, open the discharge valve 12 and close the circulation valve 11 to discharge the wastewater neutralization tank.

[0062] The method for automatically adding acid and alkali to neutralize a wastewater neutralization tank of the present invention can rely on existing devices and realize fully automatic neutralization of the wastewater neutralization tank through automatic program control without human intervention. Since the pH value and the required dosage are exponentially related, the method sets the dosage according to the pH value after mixing. The pH value deviates more from the neutral point at the beginning, and the amount of acid and alkali added is more, which can realize rapid rough adjustment. The subsequent pH value deviates less from the center, and the amount of acid and alkali added is less, and the pH is finely adjusted by adding less acid and alkali, thereby realizing rapid acid-base neutralization of the wastewater neutralization tank; realizing accurate acid and alkali addition, and effectively reducing the loss of neutralization acid and alkali; determining the dosage is obtained by calculating the pH value and liquid level after mixing, and the fluctuation of the pH value during the dosage process does not affect the dosage, thereby reducing the influence of the layout of the circulation pipeline, the acid and alkali adding pipeline, etc. on the neutralization; the above steps of neutralization of the wastewater neutralization tank are all automatically completed by the DCS system program, and automatic acid and alkali neutralization can be realized, the logic is simpler, and the amount of acid and alkali added is more convenient to count.

[0063] In order to further understand the present invention, the method and device for automatically adding acid and alkali to the wastewater neutralization tank provided by the present invention are described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0064] Example 1

[0065] Step 1: Before starting neutralization, first input the cumulative acid addition statistics module and the cumulative alkali addition statistics module, and clear the cumulative acid addition statistics module and the cumulative alkali addition statistics module to count the acid and alkali addition amounts in this wastewater pool neutralization.

[0066] Step 2: Put the automatic neutralization module into operation. After the automatic module is put into operation, the automatic module automatically calculates the water volume in the wastewater neutralization tank according to the liquid level in the wastewater neutralization tank. The calculation formula is: Vtank = Sbottom * L = 16 * 9 * L. The wastewater neutralization tank is 16m long and 9m wide. H is the liquid level in the wastewater neutralization tank, in m. After the automatic module automatically starts the drainage pump to circulate for half an hour, it automatically calculates the volume of acid and alkali required for neutralization according to the calculated water output and pH value.

[0067] When pH < 7, the wastewater is acidic and needs to be neutralized with alkali. In a certain project, the neutralizing alkali solution is 31% NaOH solution. The automatic neutralization module calculates the volume of alkali required based on the wastewater volume and pH value. The formula is:

[0068] V 碱 =H*16*9*10 (-X) *40÷0.31÷1.34 (unit L)

[0069] Where X is the pH value, 40 is the molar mass of NaOH (40 g / mol), 0.31 is the mass concentration of the added alkali solution (31%), and 1.34 is the density of 31% sodium hydroxide solution (1.34 g / cm3 .

[0070] When pH>7, the wastewater is alkaline and needs to be neutralized with acid. In a certain project, the neutralizing acid is 31% HCl solution. The automatic neutralization module calculates the required acid volume based on the wastewater volume and pH value as follows:

[0071] V 酸 =H*16*9*10 (X-14) *36.5÷0.31÷1.15 (unit L)

[0072] Where X is the pH value, 36.5 is the molar mass of HCl (36.5 g / mol), 0.31 is the mass concentration of the added alkali solution (31%), and 1.15 is the density of the 31% hydrochloric acid solution (1.15 g / cm 3 .

[0073] Step 3: The automatic neutralization module multiplies the calculated neutralization acid and alkali amount by a coefficient less than 1 as the current acid and alkali amount, such as 0.6:

[0074] V 本次酸碱 =V 酸 or V 碱 *0.6, unit L;

[0075] Multiplying by a coefficient less than 1 is mainly due to the large error of the pH meter when it is less than 2 or greater than 12. The relationship between pH value and ion concentration corresponds to an exponential relationship. When the pH value is less than 2 or greater than 12, the amount of acid and alkali added varies greatly when the pH value changes by 0.1. For example, the amount of alkali required for a pH value of 1.4 is 1.26 times the amount of alkali required for a pH value of 1.5. Therefore, in order to avoid excessive dosing, multiply by a coefficient less than 1 as the amount of dosing this time. According to the error of the pH meter, it is safer to choose less than 0.7, but the coefficient is too low, and the amount of dosing each time is small, and multiple dosing is required. Therefore, the coefficient should be above 0.5. When the coefficient is selected as 0.5, 4 dosings can reach more than 93% of the required dosing. Therefore, the coefficient should be selected between 0.5-0.7. If the coefficient is selected as 0.6 this time, it is expected that 4 dosings will complete the neutralization of the wastewater neutralization tank.

[0076] Step 4: The automatic neutralization module automatically calculates the lowering liquid level of the acid and alkali neutralization metering box through the calculated acid and alkali addition amount, stops adding medicine after adding the calculated amount, and closes the acid and alkali addition valves in the wastewater neutralization tank.

[0077] L 酸碱 =V 本次酸碱 / S 酸碱 / 10unitcm

[0078] Where S 酸碱 =π / 4*0.5*0.5 unit m 3.

[0079] If L 酸碱 When the calculated value is less than 2cm, in order to facilitate the calculation of the dosage, automatic control, and because the reversible reaction of weak acid and weak base in wastewater requires more acid and alkali to neutralize, L 酸碱 Mandatory equal to 2cm.

[0080] Step 5: After the wastewater neutralization tank continues to circulate for half an hour, if the pH value is not up to standard, the automatic neutralization module repeats steps 2-4 until the pH value is up to standard.

[0081] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0082] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for automatically adding acid and alkali to neutralize wastewater in a neutralization tank, characterized in that: The following steps are involved: Step S1: Invest in a cumulative acid addition statistics module and a cumulative alkali addition statistics module, and reset the two modules; Step S2: putting the automatic neutralization module into operation to automatically calculate the volume of acid or alkali required for neutralization; Step S3: the automatic neutralization module makes corrections based on the calculated volume of acid or alkali to obtain the actual added value of acid or alkali; Step S4: the automatic neutralization module controls the output of the acid solution or the alkali solution to neutralize the waste liquid in the neutralization tank; Step S5: After the neutralization tank continues to circulate for half an hour, if the pH value is unqualified, it returns to step S2, and the automatic neutralization module repeats the operations of steps S2 to S4; if the pH value is qualified, the neutralization operation is completed.

2. The method for automatic acid and alkali neutralization in a wastewater neutralization tank according to claim 1, characterized in that: The step S2 specifically includes the following steps: Automatically calculate the amount of water in the neutralization tank according to the liquid level in the neutralization tank; Automatically start the drainage pump to circulate for half an hour; The volume of acid or alkali required for neutralization is automatically calculated based on the calculated water volume and pH value in the pool.

3. The method for automatic acid and alkali neutralization in a wastewater neutralization tank according to claim 1, characterized in that: In step S3, the correction method is: Multiply the calculated volume of acid or base added by a coefficient between 0 and 1.

4. The method for automatic acid and alkali neutralization in a wastewater neutralization tank according to claim 3, characterized in that: The coefficient is 0.5 to 0.

7.

5. The method for automatic acid and alkali neutralization in a wastewater neutralization tank according to claim 3, characterized in that: The coefficient is 0.

6.

6. The method for automatic acid and alkali neutralization in a wastewater neutralization tank according to claim 1, characterized in that: The step S4 specifically comprises the following steps: The automatic neutralization module calculates the descending liquid level of the acid neutralization metering tank or the alkali neutralization metering tank according to the actual addition value of the acid or alkali solution; Automatically control the addition of acid or alkali, and stop when the liquid level reaches the calculated drop level. The dosage is accumulated into the corresponding acid addition statistics module or alkali addition statistics module.

7. A device for automatically adding acid and alkali to a wastewater neutralization tank, characterized in that: include: The cumulative acid addition statistics module is used to record the amount of acid added; The cumulative alkali addition statistics module is used to record the amount of alkali solution added; The automatic neutralization module is used to automatically calculate the amount of acid or alkali required for neutralization and control the addition of acid or alkali into the neutralization tank.

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