INTRODUCTION

In petrochemical industry, the purpose of refining unit is to process crude oil, produces different types of gasoline, diesel, kerosene and other fuel oils, lubricants and chemical raw materials. The device mainly includes atmospheric pressure reduction device, catalytic cracking device, catalytic reforming device, delayed coking device, hydrocracking device and hydrorefining device.

The basic requirements of the oil refining device on the valve: meet the technological requirements, ensure the service life of the valve, facilitate operation and maintenance, compact structure and light weight.

1. Requirements for sealing

Stem seal: The packing used in the valve must meet the requirements of the process medium and adapt to the temperature and pressure of the medium. During the operation of many installations, the valve packing box often leaks, so many refineries replace all packing before they go into production. Flexible graphite ring is suitable for various process medium and is not easy to be aged. It has been prescribed in sh3064-1994.

2. Requirements for Material

The valve materials used in the refinery are mainly carbon steel, alloy steel and stainless steel. For refining process development, changes in crude oil properties, further processing of crude oil, temperature and pressure increase in operating conditions. Therefore, there are new requirements for valve materials, such as corrosion resistant material 316L polymer lining.

Type specification requirements

The oil refining industry plays an important role in the national economy, and the economic benefits of the refinery are closely related to their scale. Therefore, the large-scale refinery is the future development trend. The advantages are to save investment, reduce land occupation, reduce costs, and reduce energy consumption. The large-scale refinery is mainly to expand the production capacity of a single device, so as to reflect the advantages of large-scale. The large-scale of the device will inevitably require the expansion of valve specifications, and the valve type and structure should be suitable for the requirements of multiple specifications. For example, gate valves are long in structure length and heavy in weight, and are not suitable for large diameters. Therefore, butterfly valves and other forms of valves will inevitably replace some gate valves. In addition, the specification of nominal pressure of 4.0Mpa and above should be expanded.