DO port multipath shared circuit structure

Abstract

The invention provides a DO port multipath shared circuit structure which comprises a PLC and at least two wind pressure measuring devices, and each wind pressure measuring device comprises a pressure guide pipe and a normally open solenoid valve connected in series on the pressure guide pipe, and further comprises a J relay connected between the normally open solenoid valve and the PLC; each wind pressure measuring device corresponds to a blowing device, each blowing device comprises a blowing branch pipe used for blowing gas to the corresponding pressure guide pipe, each blowing branch pipe is provided with a normally closed solenoid valve connected with the PLC, and the at least two normally closed solenoid valves are connected with the same DO switching value port of the PLC through normally open contacts of the J relays in the corresponding wind pressure measuring devices. According to the scheme, the usage amount of DO can be saved, on the premise of the same-scale purging system, the PLC with fewer DO points can be used, the system cost is reduced, meanwhile, the size of the controller is reduced, and the miniaturization requirement of instrument type equipment is met.

Description

technical field [0001] The invention belongs to the technical field of automatic control of a boiler dust removal system, and in particular relates to a circuit structure in which DO ports are shared by multiple channels. Background technique [0002] In industries such as electric power, coal chemical industry, iron and steel metallurgy, cement, papermaking, petrochemical oil refining, biofuel boilers, etc., the air volume and air pressure are measured, and the pressure pipe is widely used with an outer diameter of 10mm and a through hole of 6mm or an outer diameter of 14mm and a through hole of 10mm. 304 stainless steel pipe, long-distance pressure introduction, various bends in the middle, connecting welding joints, and then connecting to sensors or transmitters with isolation shut-off valves, and conversion joints at the instrument connections. After running for a certain period of time, the instrument must Disassemble to verify the accuracy, and the instrument should be...

AI Technical Summary

Problems solved by technology

[0003] With the passage of time, there will be small leaks that are not easy to find in the entire instrument pipeline. Due to the on-site environment, it is difficult to test the leaks of the pressure induction pipe, and it is difficult to find and find them manually; In the case of leaks, it is more likely to cause blockage of the instrument pipeline, requiring maintenance and repair personnel to spend a lot of time on the purge approval procedures and manual purge of the instrument tube, and often manual disassembly and manual purge, so that the pipeline leaks Increase, and then greatly increase the frequency of purging, thus forming a vicious circle, resulting in a large number of artificial and economic loss

[0004] In order to solve a series of problems caused by manual purging, people have carried out long-term exploration and proposed an automatic timing purging system based on the PLC control system. However, during the purging process, the signal needs to be forcibly blocked to avoid During the process, the upper computer or DCS is disturbed, so it is necessary to switch the normally open solenoid valves on multiple pressure introduction pipes and the normally closed solenoid valves on the purge branch pipes. In the scene with current channel switching, it is also necessary to perform analog For channel switching, in the prior art, in order to meet the point-to-point control principle, one DO end controls one position. It is easy to meet the scene of a few pressure induction pipes and a few measurement points, but for multiple pressure induction pipes , the scenario of multiple measurement points requires a large number of DO ports to be consumed, resulting in an increase in the cost of the PLC controller and an increase in the size of the device, and in some scenarios, it will be the next best thing, violating the one-to-one control principle and adopting multi-point sharing The control method, which will violate the independence of the hardware and increase the possibility of failure

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