A system and method for regulating heat of an ammonia stripping process supplemented with heat transfer oil

Abstract

The present application relates to a kind of system and method for adjusting the heat of supplemental heat conducting oil ammonia evaporation process, belong to evaporative treatment sewage wastewater field.This scheme increases a branch pipeline at steam main pipeline, steam valve, steam regulating valve are set on branch line and form a complete device with steam regulating function, steam regulating valve signal is connected to ammonia evaporation system DCS control cabinet, and steam regulating valve control parameter can be set according to different application scenarios by DCS control cabinet.This scheme stabilizes ammonia evaporation tower throughput and processing index, and can be applied to automatic regulation under different production conditions, and the situation that ammonia evaporation tower processing index exceeds standard due to the change of external production environment does not appear.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of evaporation treatment of sewage and wastewater, and relates to a system and method for treating ammonia wastewater by using heat-conducting oil evaporation, in particular to a method for adjusting and supplementing heat of a heat-conducting oil ammonia evaporation process. BACKGROUND

[0002] A large amount of ammonia water is formed in the initial cooling process of coke oven gas, most of which is used as circulating ammonia water for spraying and cooling the gas in the gas collecting pipe, and the excess part is called residual ammonia water. The residual ammonia water contains various compounds such as ammonia, sulfides, cyanides, and oils. Ammonia evaporation is to evaporate ammonia in the residual ammonia water by distillation to obtain high-concentration ammonia gas. The wastewater after ammonia evaporation is transported to a chemical treatment device for subsequent treatment.

[0003] Heat-conducting oil is a good organic heat carrier, which has many advantages as a heat transfer medium (hot coal), such as large heat enthalpy, high temperature resistance, oxidation resistance, no corrosion, and good heat conduction performance. Heat-conducting oil ammonia evaporation is to use heat-conducting oil at about 250℃ to directly heat the ammonia evaporation wastewater, so that it becomes saturated steam. The steam enters the ammonia evaporation tower for ammonia evaporation, and the separated part of high-temperature wastewater is heated and vaporized again, so as to achieve the purpose of ammonia evaporation in a closed loop. Compared with directly introducing saturated steam into the bottom of the ammonia evaporation tower for ammonia evaporation, using heat-conducting oil for ammonia evaporation will not increase the amount of wastewater combined with steam, and will not reduce the amount of wastewater. Compared with using a steam reboiler for ammonia evaporation, the steam is only used as a heat source, which saves a large amount of steam and reduces the operating cost.

[0004] However, due to the limitations of the heat-conducting oil ammonia evaporation process itself, its treatment capacity and treatment efficiency are difficult to improve after construction. If the external production environment changes, the task of the plant will increase, thereby increasing the amount of residual ammonia water that needs to be treated. When the ammonia evaporation treatment capacity exceeds the limit of the ammonia evaporation tower treatment, the ammonia evaporation tower treatment index will exceed the standard, resulting in a decrease in the treatment quality of ammonia wastewater. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a system and method for adjusting and supplementing the heat of a heat-conducting oil ammonia evaporation process, to improve the heat-conducting oil ammonia evaporation process, to improve the treatment capacity and treatment efficiency of the ammonia evaporation system, and to improve the adaptability to changes in the external production environment, thereby preventing the ammonia evaporation tower treatment index from exceeding the standard.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A system for adjusting and supplementing the heat of a heat-conducting oil ammonia evaporation process, comprising an ammonia evaporation tower and a heat-conducting oil reboiler, the bottom of the ammonia evaporation tower is connected with the ammonia water inlet of the heat-conducting oil reboiler, and the ammonia water outlet of the heat-conducting oil reboiler is connected with the top of the ammonia evaporation tower.

[0008] The steam branch pipe is connected with the ammonia water outlet of the reboiler, and is provided with a first one-way stop valve, a steam regulating valve and a second one-way stop valve in the steam flow direction, the steam regulating valve is connected with the ammonia steam distributed control system control cabinet through a signal line, and the ammonia steam distributed control system control cabinet is used to modify the steam pressure parameter of the steam regulating valve, adjust the opening of the steam regulating valve, and control the actual steam pressure to meet the steam supplement demand.

[0009] Further, a third stop valve is connected in parallel between the inlet of the first one-way stop valve and the outlet of the second one-way stop valve.

[0010] A method for adjusting and supplementing the heat of the ammonia steam process, comprising the following steps:

[0011] S1, judging whether the required processing capacity of the ammonia steam column is greater than the upper limit of the ammonia steam system processing capacity, if yes, establishing the corresponding relationship between the upper limit of the ammonia steam system processing capacity and the steam supplement demand in the steam regulating valve according to the column bottom temperature;

[0012] S2, calculating the steam supplement flow rate according to the steam supplement demand and the processing time, and determining the steam pressure parameter according to the steam supplement flow rate;

[0013] S3, modifying the steam pressure parameter of the steam regulating valve through the ammonia steam distributed control system control cabinet;

[0014] S4, the steam regulating valve adjusts its opening according to the steam pressure parameter, controls the actual steam pressure to maintain a balanced state, and meets the steam supplement demand.

[0015] Further, in the S1, if the required processing capacity of the ammonia steam column is less than the upper limit of the ammonia steam system processing capacity, the steam regulating valve is directly controlled to be completely closed through the ammonia steam distributed control system.

[0016] Further, in the S1, when the column bottom temperature is 108℃, the corresponding relationship between the upper limit of the ammonia steam system processing capacity and the steam supplement demand includes: if the upper limit of the ammonia steam system processing capacity is 70m 3 / h, the steam supplement amount is controlled to be 2m 3 / h; if the upper limit of the ammonia steam system processing capacity is 45m 3 / h, the steam supplement amount is controlled to be 0.8m 3 / h; if the upper limit of the ammonia steam system processing capacity is 55m 3 / h, the steam supplement amount is controlled to be 1.2m 3 / h.

[0017] Further, in the S4, the balance state includes gradually reducing the actual steam pressure, slowly increasing the opening degree of the steam regulating valve; gradually increasing the actual steam pressure, slowly reducing the opening degree of the steam regulating valve.

[0018] The principle of the present scheme is:

[0019] In the prior art, the advantages of ordinary heat conducting oil ammonia distillation over steam ammonia distillation are mainly that steam is not used, and steam ammonia distillation consumes a large amount of steam, thereby greatly saving costs. However, using steam as a supplementary heat source in heat conducting oil ammonia distillation is tantamount to putting the cart before the horse, so there is usually a technical bias against using steam in the ammonia distillation process. Moreover, directly introducing steam into the top of the tower will cause the steam to be wasted, and excessive steam will increase the total amount of waste water, thereby increasing the subsequent treatment cost, so it is almost impossible to directly introduce steam as a heat source into the top of the tower.

[0020] However, the present scheme is seemingly simple in structure, but is actually ingenious in design, breaking the conventional thinking and directly introducing steam into the top of the ammonia distillation tower. Not only can it provide more sufficient heat, but according to the distillation partial pressure principle, it can also reduce the ammonia gas partial pressure and act as a gas stripping agent in the ammonia distillation tower, thereby having a positive effect on controlling the ammonia nitrogen and cyanide indicators in the ammonia water after ammonia distillation, thereby improving the upper limit of the heat conducting oil ammonia distillation technology. When facing a large number of temporary processing tasks that exceed the upper limit of the processing, the processing quality of the ammonia waste water can be guaranteed to meet the standards, and the amount of supplementary steam can be accurately controlled by the steam regulating valve, achieving the above-mentioned purposes without causing excessive increases in subsequent processing costs.

[0021] The present application has the following advantages:

[0022] The present method realizes an additional stable heat supply channel for the ammonia distillation tower, and realizes the functions of stabilizing the processing capacity and processing indicators of the ammonia distillation tower. Moreover, the method can be applied to automatic adjustment under different production conditions, and will not cause the processing indicators of the ammonia distillation tower to exceed the standards due to changes in the external production environment.

[0023] Other advantages, objects, and features of the present application will be set forth in part in the following specification, and in part will become apparent to those skilled in the art from the following specification, or can be learned from the practice of the present application. The objects and other advantages of the present application can be realized and obtained by the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to make the objects, technical solutions, and advantages of the present application more clear, the preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, in which:

[0025] Figure 1The system principle diagram for adjusting and supplementing heat of the heat conducting oil ammonia distillation process of the present application;

[0026] The figure mark: 1-ammonia distillation tower, 2-heat conducting oil reboiler, 21-ammonia water outlet, 22-ammonia water inlet, 23-heat conducting oil inlet, 24-heat conducting oil outlet, 3-first one-way stop valve, 4-steam regulating valve, 5-second one-way stop valve, 6-third stop valve, 7-steam supplement inlet. DETAILED DESCRIPTION

[0027] The following embodiments of the present application will be described in greater detail by way of specific examples. The other advantages and effects of the present application can be easily understood by those skilled in the art from the contents disclosed in this specification. The present application can also be implemented or applied by means of other different embodiments, and various modifications or changes can be made to the details in this specification based on different views and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0028] The drawings are only used for illustrative explanation, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation on the present application; in order to better illustrate the embodiments of the present application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual product size; it can be understood by those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0029] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative explanation, and cannot be understood as a limitation on the present application, and for those skilled in the art, the specific meaning of the above terms can be understood according to the specific situation.

[0030] Please refer to Figure 1 The system for adjusting and supplementing heat of the heat conducting oil ammonia distillation process, comprising an ammonia distillation tower 1 and a heat conducting oil reboiler 2, the bottom of the ammonia distillation tower 1 is connected with the ammonia water inlet 22 of the heat conducting oil reboiler 2, and the ammonia water outlet 21 of the heat conducting oil reboiler 2 is connected with the top of the ammonia distillation tower 1;

[0031] The steam branch pipe is connected with the ammonia water outlet 21 of the heat conducting oil reboiler 2, and is provided with a first one-way stop valve 3, a steam regulating valve 4 and a second one-way stop valve 5 in the steam flowing direction, so that the steam enters the ammonia stripping tower 1 through the steam supplement inlet 7, the first one-way stop valve 3, the steam regulating valve 4, the second one-way stop valve 5 and the ammonia water outlet 21 in sequence; the steam regulating valve 4 is connected with the ammonia stripping distributed control system control cabinet through a signal line; the ammonia stripping distributed control system control cabinet is used to modify the steam pressure parameter of the steam regulating valve, adjust the opening degree of the steam regulating valve and control the steam supplement amount; the third stop valve 6 is connected in parallel between the inlet of the first one-way stop valve 3 and the outlet of the second one-way stop valve 5. In the embodiment, the steam regulating valve 4 is a PID regulating valve.

[0032] A method for adjusting the heat of the steam ammonia stripping process supplemented by heat conducting oil, comprising the following steps:

[0033] S1, judging whether the required processing capacity of the ammonia stripping tower is greater than the upper limit of processing capacity, if yes, modifying the steam pressure parameter of the steam regulating valve through the ammonia stripping distributed control system control cabinet.

[0034] S2, establishing the corresponding relationship between the steam pressure parameter in the steam regulating valve and the actual steam pressure according to the required processing capacity and the upper limit of processing capacity; for example, when the processing capacity of the ammonia stripping system is 70 m 3 / h, the steam pressure is greater than or equal to 0.5 Mpa through parameter adjustment of the steam regulating valve, and the steam supplement amount is controlled to be 2 m 3 / h; when the processing capacity of the ammonia stripping system is 45 m 3 / h, the steam supplement amount is controlled to be 0.8 m 3 / h; when the processing capacity of the ammonia stripping system is 55 m 3 / h, the steam supplement amount is controlled to be 1.2 m 3 / h.

[0035] S3, the steam regulating valve adjusts the opening degree of itself according to the steam pressure parameter, and controls the actual steam pressure; when the actual steam pressure gradually decreases, the opening degree of the steam regulating valve is slowly increased; when the actual steam pressure gradually increases, the opening degree of the steam regulating valve is slowly decreased.

[0036] A specific control example: when the ammonia water processing capacity of the ammonia stripping tower is 60 m 3 / h, the valve opening degree is controlled according to the bottom temperature of the ammonia stripping tower in the DCS system and the steam valve position, and the opening degree of the steam bypass manual valve is controlled to be 1 / 3; when the ammonia water processing capacity gradually increases to 70 m 3When t = 6h, under the temperature cascade control, the steam regulating valve is gradually opened to 60% of the valve position to maintain the fluctuation of the ammonia distillation tower bottom temperature within ±1℃, at this time, the ammonia water treated by the ammonia distillation tower reaches the index of ammonia nitrogen ≤100mg / L and cyanide ≤10mg / L, which completely meets the water inlet index requirement of the phenol cyanide wastewater treatment system.

[0037] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should be covered in the scope of the claims of the present application.

Claims

1. A system for regulating heat in an ammonia stripping process with supplemental heat transfer oil, characterized by: The ammonia distillation tower is connected with the ammonia water inlet of the heat conducting oil reboiler, and the ammonia water outlet of the heat conducting oil reboiler is connected with the top of the ammonia distillation tower. The steam branch pipe is connected with the ammonia water outlet of the reboiler, so that steam is directly introduced into the top of the ammonia distillation tower.

2. The system for regulating heat of the ammonia evaporation process supplemented by heat-conducting oil according to claim 1, characterized in that: The third stop valve is connected in parallel between the inlet of the first one-way stop valve and the outlet of the second one-way stop valve.

3. A method for regulating the heat of an ammonia stripping process with supplemental heat transfer oil based on the system of regulating the heat of an ammonia stripping process with supplemental heat transfer oil according to the preceding claim 1 or 2, characterized in that: The method comprises the following steps: S1, judging whether the required processing capacity of the ammonia distillation tower is greater than the upper limit of the ammonia distillation system processing capacity, if yes, establishing the corresponding relationship between the upper limit of the ammonia distillation system processing capacity and the steam supplement demand in the steam regulating valve according to the tower bottom temperature; S2, calculating the steam supplement flow rate according to the steam supplement demand and processing time, and determining the steam pressure parameter according to the steam supplement flow rate; S3, modifying the steam pressure parameter of the steam regulating valve through the ammonia distillation distributed control system control cabinet; S4, adjusting the opening of the steam regulating valve according to the steam pressure parameter, controlling the actual steam pressure to maintain a balance state, and meeting the steam supplement demand.

4. The method of claim 3, wherein the heat of the ammonia stripping process is adjusted by supplementing the heat transfer oil. In the S1, if the required processing capacity of the ammonia distillation tower is less than the upper limit of the ammonia distillation system processing capacity, the steam regulating valve is completely closed through the ammonia distillation distributed control system.

5. The method of claim 3, wherein the heat of the ammonia stripping process is adjusted by supplementing the heat transfer oil. In the S1, when the tower bottom temperature is 108℃, the corresponding relationship between the upper limit of the ammonia distillation system processing capacity and the steam supplement demand comprises: if the upper limit of the ammonia distillation system processing capacity is 70m³ / h, the steam supplement amount is controlled to be 2m³ / h; if the upper limit of the ammonia distillation system processing capacity is 45m³ / h, the steam supplement amount is controlled to be 0.8m³ / h; if the upper limit of the ammonia distillation system processing capacity is 55m³ / h, the steam supplement amount is controlled to be 1.2m³ / h.

6. The method of claim 3, wherein the heat of the ammonia stripping process is adjusted by supplementing the heat transfer oil. In the S4, the balance state comprises gradually reducing the opening of the steam regulating valve when the actual steam pressure gradually decreases, and gradually increasing the opening of the steam regulating valve when the actual steam pressure gradually increases.

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