CN216815171U - System for improving control precision of heat exchanger - Google Patents

Abstract

The utility model discloses a system for improving the control precision of a heat exchanger, and particularly relates to the technical field of heat exchangers. The utility model can not only make the control accurate and the system operate stably, but also save a large amount of energy, reduce the discharge, increase the control of the auxiliary flow path, carry out the bypass fine adjustment to the temperature control and improve the accuracy of the heat exchanger control system through the arrangement of the main control flow path and the auxiliary flow path.

Description

System for improving control precision of heat exchanger

Technical Field

The utility model relates to the technical field of heat exchangers, in particular to a system for improving the control precision of a heat exchanger.

Background

In the chemical production process, some reactions need to release heat, some reactions need to absorb heat, some materials need to be transported at high temperature, some materials need to be stored at normal temperature, and in order to reduce emission, the residual heat is fully utilized, and the heat exchanger is required to collect and transfer the heat. The most common heating heat exchanger is to heat the material with steam, the cooling heat exchanger is to cool the material with circulating water, and water is used as a medium to realize transportation and storage of heat.

When the materials are subjected to heat exchange in the heat exchanger, the general control method is to control the inlet flow of one material by using the outlet temperature of the other material, i.e. to control the valve switch to adjust the pressure or flow, so that the target material temperature after the heat exchange of the materials reaches the required requirement. The simple control loop has low precision, waste and low efficiency.

As shown in fig. 1, the conventional heat control scheme is that a thermometer is installed on a heated or cooled material outlet pipeline, an adjusting valve is installed at an inlet of a steam pipeline or a circulating water pipeline, the thermometer and the adjusting valve form a single control loop to adjust pressure and flow at any time, so that the temperature of a material after heat exchange is kept stable.

The main defects of the existing heat exchange system are that the adjustment of a steam valve or a circulating water valve is not flexible enough, the fluctuation of the outlet temperature is too large, and the heat waste is caused, and the heat exchange system is mainly embodied in the following aspects:

(1) when the heat exchange is carried out on the material at the outlet of a large device, a large amount of water or steam is needed, when the pipeline is above DN250, the valve slightly acts, the heat exchange medium flowing through the valve is large, and even the valve surging phenomenon occurs.

(2) In places sensitive to temperature regulation, the temperature of materials changes by 1 ℃, reaction byproducts can grow exponentially, the temperature needs to be controlled without fluctuation, and most of the existing heat exchanger valve control loops cannot achieve high precision.

(3) When material fluctuation occurs in the production device system, the conventional heat exchanger control system cannot realize rapid and sensitive temperature adjustment, possibly generates lag relative to fluctuation amplitude, and cannot adapt to production.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects in the prior art, the utility model provides a system for improving the control precision of a heat exchanger, which can more accurately and finely adjust the flow, keep the temperature of a controlled heat exchange material constant, save the cost, save the energy, reduce the emission and ensure the stable operation of a production system.

In order to achieve the purpose, the utility model provides the following technical scheme:

the system for improving the control precision of the heat exchanger comprises the heat exchanger, a temperature detection device used for measuring the temperature of a material outlet of the heat exchanger, a PID (proportion integration differentiation) controller, a main control flow path arranged at a medium inlet of the heat exchanger and an auxiliary flow path arranged on the main control flow path, wherein the main control flow path controls the heat exchanger to accelerate temperature rise or temperature reduction, and when the system runs stably or needs fine control of the temperature, the auxiliary flow path controls the medium to flow into the heat exchanger for temperature regulation.

The utility model has the technical effects and advantages that:

1. the arrangement of the main control flow path and the auxiliary flow path not only can ensure accurate control and stable system operation, but also can save a large amount of energy and reduce emission.

2. The control of the auxiliary flow path is added, the bypass fine adjustment can be carried out on the temperature control, and the precision of the heat exchanger control system is improved.

3. The control mode of the heat exchanger control precision system is improved, and the proportion controller is arranged, so that the control proportion can be adjusted according to the actual production running condition.

Drawings

Fig. 1 is a schematic diagram of a prior art temperature controller.

Fig. 2 is a heat exchanger control system of the present invention.

FIG. 3 is a control loop diagram of the proportional distribution controller.

The reference signs are:

1. a heat exchanger; 2. a temperature detection device; 3. a PID controller; 4. a master control flow path; 41. adjusting a valve I; 5. an auxiliary flow path; 51. a second regulating valve; 6. and a controller.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The utility model provides a system for improving the control precision of a heat exchanger.

The system for controlling the precision of the heat exchanger can be used for a steam heat exchanger or a cooling water heat exchanger, and the steam heat exchanger is explained below.

As shown in fig. 2, the system includes a heat exchanger 1, a temperature detection device 2 for measuring the material outlet temperature of the heat exchanger 1, the temperature detection device 2 can use a thermometer and other devices for measuring temperature, and further includes a PID controller 3, a main control flow path 4 installed at the steam inlet of the heat exchanger 1, and further an auxiliary flow path 5 installed on the main control flow path 4, a first regulating valve 41 is installed on the main control flow path 4, a second regulating valve 51 is installed on the auxiliary flow path 5, both ends of the auxiliary flow path 5 are respectively connected to both ends of the first regulating valve 41, the auxiliary flow path 5 can use a steam bypass or a circulating water bypass, the first regulating valve 41 and the second regulating valve 51 can regulate pressure and flow at any time, by setting the main control flow path 4 and the auxiliary flow path 5, when the system is debugged or produced, the heat exchanger 1 is controlled by the main control flow path 4 to accelerate temperature rise or when the system is operated stably or needs to control temperature finely, the auxiliary flow path 5 is used for controlling the temperature of the steam flowing into the heat exchanger 1, and in order to ensure the control precision, the pipeline size of the auxiliary flow path 5 is DN32, DN40, DN50, DN65, preferably DN 50.

The system also comprises a controller 6, wherein the controller 6 is a proportional distribution controller and is used for controlling the regulation of the main control flow path 4 and the auxiliary flow path 5, the material outlet temperature of the heat exchanger 1 is used as a controlled variable, the controlled variable is compared with the required temperature input into the PID controller 3 in the PID controller 3, and the output value enters the controller 6, so that the steam control limit of the main control flow path 4 and the auxiliary flow path 5 is distributed through the controller 6;

the temperature control amount of the controller 6 is defined as f (x), the distribution amount of the main flow path 4 is defined as f (x1), the distribution amount of the auxiliary flow path 5 is defined as f (x2), and the control formula is as follows:

f(x1)＝f(x)*R；

f(x2)＝f(x)*(1-R)；

wherein: r is a proportionality coefficient, a numerical value can be manually input, and R is more than or equal to 0 and less than or equal to 1.

The controller and the calculation formula are edited in a DCS or a PLC system.

The regulation and control proportion of the main control flow path 4 and the auxiliary flow path 5 is adjusted according to the situation, so that the flexibility of the control system is improved, and a control loop diagram of a proportion distribution controller is shown in fig. 3. According to the control loop diagram, the control proportion is set, and in the initial operation stage of the device, the proportion coefficient R can be increased, the steam flow is roughly adjusted, and the system preheating is accelerated. In the process of stable operation of the device, the proportionality coefficient R is reduced, the steam flow is finely adjusted, the temperature change is slow, the system is stabilized, and the steam is saved.

The points to be finally explained are: first, in the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounted," "connected," and "connected" should be understood broadly, and may be a mechanical connection or an electrical connection, or a communication between two elements, and may be a direct connection, and "upper," "lower," "left," and "right" are only used to indicate a relative positional relationship, and when the absolute position of the object to be described is changed, the relative positional relationship may be changed;

secondly, the method comprises the following steps: in the drawings of the disclosed embodiments of the utility model, only the structures related to the disclosed embodiments are referred to, other structures can refer to common designs, and the same embodiment and different embodiments of the utility model can be combined with each other without conflict;

and finally: the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included in the scope of the present invention.

Claims (5)

1. The utility model provides a system for improve heat exchanger control accuracy, includes heat exchanger (1), is used for measuring temperature-detecting device (2) of the material outlet temperature of heat exchanger (1), PID controller (3) and installs master control flow path (4) at the medium entrance of heat exchanger (1), its characterized in that: the system is characterized by further comprising an auxiliary flow path (5) installed on the main control flow path (4), wherein the main control flow path (4) controls the heat exchanger (1) to accelerate temperature rise or temperature reduction, and when the system runs stably or the temperature needs to be controlled finely, the auxiliary flow path (5) controls a medium to flow into the heat exchanger (1) for temperature regulation.

2. The system for improving the control accuracy of the heat exchanger according to claim 1, wherein: the main control flow path (4) is provided with a first adjusting valve (41), the auxiliary flow path (5) is provided with a second adjusting valve (51), and two ends of the auxiliary flow path (5) are connected to two ends of the first adjusting valve (41) respectively.

3. A system for improving the control accuracy of a heat exchanger according to claim 1 or 2, wherein: the device is characterized by further comprising a controller (6), wherein the controller (6) is a proportional distribution controller and is used for controlling the adjustment of the main control flow path (4) and the auxiliary flow path (5).

4. A system for improving the control accuracy of a heat exchanger according to claim 3, wherein: the material outlet temperature of the heat exchanger (1) is used as a controlled variable, the controlled variable is compared with the required temperature input into the PID controller (3) in the PID controller (3), and the output value enters the controller (6), so that the steam control limit of the main control flow path (4) and the auxiliary flow path (5) is distributed through the controller (6);

the temperature control amount of the controller (6) is defined as f (x), the distribution amount of the main control flow path (4) is defined as f (x1), the distribution amount of the auxiliary flow path (5) is defined as f (x2), and the control formula is as follows:

f(x1)＝f(x)*R；

f(x2)＝f(x)*(1-R)；

wherein: r is a proportionality coefficient, a numerical value can be manually input, and R is more than or equal to 0 and less than or equal to 1.

5. The system for improving the control accuracy of the heat exchanger according to claim 4, wherein: the auxiliary flow path (5) is a steam bypass or a circulating water bypass, and the pipeline size of the auxiliary flow path (5) is DN32, DN40, DN50 and DN 65.

Images