Automatic ammonia nitrogen control method for ammonia distillation wastewater

Abstract

The invention discloses a method for automatically controlling ammonia nitrogen in ammonia distillation wastewater. The method comprises the following steps: firstly, collecting volatile ammonia amount and fixed ammonia amount in raw water and wastewater through a flowmeter; then calculating and adjusting the steam amount and the alkali liquor amount according to the ammonia distillation raw water treatment amount; finally, a control signal is sent out according to the adjusted steam amount and the adjusted alkali liquor amount obtained through calculation, a steam adjusting valve and an alkali liquor adjusting valve are adjusted, and the steam adjusting valve and the alkali liquor adjusting valve achieve stable control over the steam flow and the alkali liquor flow through PID parameters of the steam adjusting valve and the alkali liquor adjusting valve. By adopting the method disclosed by the invention, the automation degree of the ammonia distillation system can be effectively improved, the steam quantity and the alkali liquor quantity can be automatically calculated and adjusted according to the quantity of raw water and wastewater, manual participation is not needed, the operation load of staff is reduced, and the problems caused by manual operation are also reduced. Meanwhile, control parameters are more accurate, consumption of steam and alkali liquor can be effectively reduced, and the production cost is saved. The wastewater ammonia nitrogen qualification rate in the ammonia distillation production process is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coking product recovery, and in particular relates to an automatic control method for ammonia nitrogen in ammonia evaporation wastewater. Background Art

[0002] All kinds of wastewater generated during the coking process must be treated with ammonia evaporation, and then treated with biochemical and physicochemical treatments before they can be discharged. Ammonia evaporation mainly treats volatile ammonia and fixed ammonia in the raw water. In the process, NaOH is used to convert the fixed ammonia in the raw water into volatile ammonia. The reaction formula for the decomposition of fixed ammonia is as follows: NH4Cl+NaOH=NH3+H2O+NaCl NH4SCN+NaOH=NH3+H2O+NaSCN At the same time, steam distillation is introduced into the bottom of the ammonia distillation tower to evaporate and recover most of the volatile ammonia in the wastewater. The wastewater after ammonia distillation is cooled by the wastewater cooler and sent to the phenol-cyanide wastewater treatment device. The wastewater after ammonia distillation must meet the water inlet standard for wastewater biological treatment (T-NH3≤200mg / L).

[0003] In the traditional production process, the production operators manually adjust the amount of steam and alkali solution on site according to the test data tested every day. This method is cumbersome to operate, the workload of the operators is large, and it is easy to have control errors caused by human factors, such as excessive use of steam and alkali solution, which leads to waste. At the same time, there is also the problem of low qualified rate of ammonia nitrogen in wastewater. Summary of the invention

[0004] The object of the present invention is to provide a method for automatically controlling ammonia nitrogen in ammonia evaporation wastewater with a high degree of automation. The method is used for production, which saves energy and can ensure the qualified rate of ammonia nitrogen in wastewater.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a method for automatically controlling ammonia nitrogen in ammonia evaporation wastewater, characterized in that it comprises the following steps: S1: Collect the amount of volatile ammonia and fixed ammonia in raw water and wastewater through flow meter; S2: Calculate and adjust the steam volume and alkali solution volume according to the ammonia raw water treatment volume. Adjust steam volume Z = a·X+b·Y1+c·F1+d Adjust the amount of alkali solution J=e·X+f·Y2+g·F2+h Among them, X is the raw water treatment volume, Y1 is the amount of volatile ammonia in raw water, F1 is the amount of volatile ammonia in wastewater, Y2 is the fixed ammonia in raw water, F1 is the fixed ammonia in wastewater, and the correlation coefficients a, b, c, d, e, f, g, and h are determined by the operating conditions of different raw water treatment volume ranges; S3: Send out control signals according to the calculated steam volume and alkali solution volume to adjust the steam regulating valve and alkali solution regulating valve. The steam regulating valve and alkali solution regulating valve can realize stable control of steam and alkali solution flow rates through their own PID parameters.

[0006] Furthermore, the relevant correlation coefficients a, b, c, and d determined by the raw water treatment volume range are as follows:

[0007] Furthermore, the relevant correlation coefficients e, f, g, and h determined by the raw water treatment volume range are as follows:

[0008] Beneficial effects of the present invention: The method of the present invention can effectively improve the automation degree of the ammonia distillation system, and can automatically calculate and adjust the amount of steam and alkali solution according to the amount of raw water and wastewater, without manual participation, reducing the operating load of employees and the problems caused by manual operation. At the same time, the control parameters are more accurate, which can effectively reduce the consumption of steam and alkali solution and save production costs. The qualified rate of ammonia nitrogen in the wastewater of the ammonia distillation production process is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the process of the present invention.

[0010] Figure 2 It is a schematic diagram of a model for automatic regulation of steam and alkali solution amounts in the present invention. DETAILED DESCRIPTION

[0011] The following is merely a further description of the embodiments of the present invention and does not limit the scope of the present invention in any way.

[0012] Before the method of the present invention is implemented, flow meters for detecting steam, alkali liquid and raw water are respectively arranged on the ammonia distillation system, as well as regulating valves for controlling the steam amount and alkali liquid amount respectively; all flow meters and regulating valves are connected to the DCS control system for communication.

[0013] like Figure 1 As shown, the present invention provides an automatic control method for ammonia nitrogen in ammonia evaporation wastewater, characterized in that it comprises the following steps: S1: The volatile ammonia content and fixed ammonia content in raw water and wastewater are collected through flow meters.

[0014] S2: Calculate and adjust the steam volume and alkali solution volume based on the ammonia raw water treatment volume.

[0015] Adjust steam volume Z = a·X+b·Y1+c·F1+d Adjust the amount of alkali solution J=e·X+f·Y2+g·F2+h Among them, X is the raw water treatment volume, Y1 is the amount of volatile ammonia in raw water, F1 is the amount of volatile ammonia in wastewater, Y2 is the fixed ammonia in raw water, F1 is the fixed ammonia in wastewater, and the correlation coefficients a, b, c, d, e, f, g, and h are determined by the operating conditions of different raw water treatment volume ranges.

[0016] Specifically, the relevant correlation coefficients a, b, c, and d determined by the raw water treatment volume range are as follows:

[0017] Specifically, the relevant correlation coefficients e, f, g, and h determined by the raw water treatment volume range are as follows:

[0018] S3: Send out control signals according to the calculated steam volume and alkali solution volume to adjust the steam regulating valve and alkali solution regulating valve. The steam regulating valve and alkali solution regulating valve can realize stable control of steam and alkali solution flow rates through their own PID parameters.

[0019] Preferably, an automatic start button and an automatic stop button may also be provided to switch between the automatic control mode and the manual control mode, so that the automatic control can be stopped when manual intervention is required according to actual needs, facilitating manual operation.

[0020] The present invention has been applied and implemented in the ammonia distillation device of the coking unit of the iron and steel plant. After the scheme of the present invention is applied, the operation times of the ammonia distillation system are significantly reduced, the hit rate of the NH3 content in the ammonia distillation wastewater between 100-200 mg / L is increased by 15%, the steam consumption is reduced by 7.6%, the NaOH consumption is reduced by 6.4%, and the operation cost of the enterprise is reduced.

[0021] The application of this patent can achieve stable control of ammonia nitrogen in ammonia evaporation wastewater, thereby saving steam and NaOH consumption, and therefore has high practical value.

[0022] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for automatically controlling ammonia nitrogen in ammonia evaporation wastewater, characterized in that: The steps include: S1: Collect the amount of volatile ammonia and fixed ammonia in raw water and wastewater through flow meter; S2: Calculate and adjust the steam volume and alkali solution volume according to the ammonia raw water treatment volume. Adjust steam volume Z = a· X+b · Y 1 +c F1+d Adjust the amount of alkali solution J = e· X+f · Y 2 +g ·F2+h Among them, X is the raw water treatment volume, Y1 is the amount of volatile ammonia in raw water, F1 is the amount of volatile ammonia in wastewater, Y2 is the fixed ammonia in raw water, F1 is the fixed ammonia in wastewater, and the correlation coefficients a, b, c, d, e, f, g, and h are determined by the operating conditions of different raw water treatment volume ranges; S3: Send out control signals according to the calculated steam volume and alkali solution volume to adjust the steam regulating valve and alkali solution regulating valve. The steam regulating valve and alkali solution regulating valve can realize stable control of steam and alkali solution flow rates through their own PID parameters.

2. The method for automatic control of ammonia nitrogen in ammonia evaporation wastewater according to claim 1, characterized in that: The relevant correlation coefficients a, b, c, and d determined by the raw water treatment capacity range are as follows:

3. The method for automatic control of ammonia nitrogen in ammonia evaporation wastewater according to claim 1 or 2, characterized in that: The relevant correlation coefficients e, f, g, and h determined by the raw water treatment capacity range are as follows:

Images