Use and specification requirements of regulating valve

Use and specification requirements of regulating valve

Advanced modern industry is marked by production automation. From the development history and progress of automation system, the change of technical tools plays a very important role. Various advanced control methods continue to appear, but the basic control law has not changed, while the improvement of technical tools is changing with each passing day. The development and use of intelligent instruments have created a better future for industrial automation. A typical automatic control system mainly has three links: detection, control and execution. In recent years, it is obvious that the detection instruments and control instruments have changed under the influence of digital technology and microprocessor technology, and the actuator, especially the regulating valve as the main product, has also made great progress. The traditional regulating valve basically meets the needs of many industrial systems, but with the large-scale development of modern industry. How to produce more and better advanced products, how to improve product quality standards, how to operate more effectively and safely, how to make full use of resources, save energy and protect the ecological environment, people recall that higher requirements are put forward for the regulating valve. These requirements can be summarized as follows: the quality is more stable, the work is more reliable, and the operation is safer. In the process control, once the regulating valve is in direct contact with the fluid and fails, The consequences are unimaginable.

In the petroleum industry, from oil fields to refineries, all kinds of production devices are monitored and controlled on a large scale. Most of the operating conditions are carried out under high temperature and low pressure or high temperature and high pressure. The medium is all kinds of flammable and explosive oil and all kinds of oil products. Therefore, the reliability and fire resistance of control valves are mentioned in the first place. In the chemical industry, the diversity of processes and the changes of process conditions, as well as the control and implementation of the four thermal variables of temperature, pressure, flow and liquid level, have very special problems, which require that the regulating valve can be applied.

In the power industry, the thermal power plant should control the boiler. It is very important to maintain the normal water level in the boiler regulation system, so as to avoid the wrong opening and closing of the regulation valve. In order to ensure the working performance and reliability of the regulating valve, the following requirements must be met:

1. To ensure the quality of the regulating valve, the selection of the regulating valve should be strictly calculated; The type, caliber and various performances shall meet the requirements; The materials of various parts of the regulating valve should be strictly selected, with sufficient strength and stiffness, and should pass the pressure test, air tightness test and other tests in accordance with national standards. The manufacturing technology and testing methods of the manufacturer must meet the standards and be signed and approved by the competent department. It is strictly forbidden to carry out production in small factories that do not have production conditions.

2. Ensuring reliable operability here refers to the manufacturing quality of the regulating valve itself, including the training and quality improvement of operators. In order to prevent misoperation, process personnel must pay attention to the precautions marked on the nameplate. According to China's new pneumatic control valve standard (gb/t4213-92), the nameplate of pneumatic actuator shall at least indicate the manufacturer's name, product model, rated flow coefficient, design tag number, product number, manufacturing month and year, etc. The arrow indicating the direction of medium flow, DN value and PN words and values shall be cast or punched on the valve body. Important valves should have enough accessories, such as positioners, limit switches, etc. There should be enough installation space and operation space, enough installation space and operation, enough lighting, and strict operating procedures.