Publish Time: 2021-08-11 Origin: Site
Keywords: Yokogawa Instrument, Coal Chemical Industry, Hydrogen Permeation
Abstract: In the coal chemical industry, Yokogawa pressure transmitters are used in many occasions. However, compared with traditional industries, there are many working conditions where the medium is black water or gray water, the temperature is above 200 ℃, and the pressure is above 4 MPa. Because of the high temperature and high pressure, the medium composition is complex, the pressure transmitter’s wetted metal diaphragm (usually 316L) hydrogen permeation is extremely prone to occur. Hydrogen permeation is hydrogen permeation, which means that hydrogen molecules penetrate through the metal diaphragm under the action of external force and intrude into the sealing liquid cavity, resulting in bubbles (hydrogen accumulation), which will cause the metal isolation diaphragm of the sealing liquid cavity to bulge after a certain period of time. In severe cases, it may even rupture.
Coal chemical industry is a process in which coal is used as a raw material to transform coal into gas, liquid and solid products or semi-products through chemical processing, and then further processed into chemical and energy products. As the world's petroleum resources continue to decrease, coal chemical industry has broad prospects. In recent years, coal chemical industry has also developed rapidly in China.
In the coal chemical industry, there are many occasions where pressure transmitters are used. However, compared with traditional industries, there are many working conditions where the medium is black water or gray water, the temperature is above 200 ℃, and the pressure is above 4 MPa. Because of the high temperature and high pressure, the medium composition is complex, the pressure transmitter’s wetted metal diaphragm (usually 316L) hydrogen permeation is extremely prone to occur. Hydrogen permeation is hydrogen permeation, which means that hydrogen molecules penetrate through the metal diaphragm under the action of external force and intrude into the sealing liquid cavity, resulting in bubbles (hydrogen accumulation), which will cause the metal isolation diaphragm of the sealing liquid cavity to bulge after a certain period of time. In severe cases, it may even rupture.
For the prevention of hydrogen permeation, the industry usually uses the method of gold plating on the 316L diaphragm. Hydrogen does not dissolve in gold, and the gold layer is very dense, so the diaphragm gold plating is used as an effective barrier layer to prevent hydrogen from penetrating the diaphragm. However, in the coal chemical industry, where the medium is black water/grey water, the 316L gold-plated diaphragm of various transmitter manufacturers in the world can only be used for 3 to 6 months, and hydrogen permeation will occur. It has become a headache for the coal chemical industry.
In 2014, the technical department of Chongqing Yokogawa River Instruments developed a 316L full gold-plated product for hydrogen seepage prevention in the coal chemical industry in accordance with the company's requirements. The structure and process were changed on the original gold plating, and the thickness of the gold-plated layer was increased at the same time. This type of product began to be marketed in October 2014. First of all, 21 EJA transmitters were used in the gasification unit of Yantai Wanhua, and the hydrogen seepage prevention effect was very significant.
Gasifier site: The flange part of the EJA transmitter is completely wrapped by the insulation layer.
The negative pressure side of the double flange meter EJA118W.
After one and a half years of trouble-free operation, the customer of Yantai Wanhua specifically issued a description of the operation situation, and made a great affirmation of the application of EJA's 316L fully gold-plated products in the anti-hydrogen seepage application of the coal chemical industry; the normal use time of this batch of meters is all More than 3 years.
The EJA series of 316L fully gold-plated products used in the coal chemical industry to prevent hydrogen seepage have been used in Yantai Wanhua and Nanjing Wison in 2014, and are currently in Ningbo Wanhua, Shaanxi Yanchang Energy, Inner Mongolia Huineng Coal Chemical Industry, Anhui Huayi Chemicals, Yankuang Xinjiang Coal Chemical Industry, Future Energy, Shanxi Coal Dahua, Shandong Hualu Hengsheng and other high-temperature and high-pressure coal chemical plants have been used in high-temperature and high-pressure equipment, and thousands of units have been used. The development and application of the EJA series of 316L fully gold-plated products effectively prevented the hydrogen permeation in the high temperature and high pressure working conditions of the coal chemical industry. It has been used in the field for the longest time for more than three years, exceeding the expectations of the users, and has been affirmed by the users.