The petrochemical industry is still greatly affected by the globalization of the world economy.
The increase in energy demand has translated into a decline in supply and soaring costs. In order to adapt to these changes, the petrochemical industry will continue to adjust through divestitures, joint ventures and other forms of cooperation, which will result in fewer and fewer commodity petrochemical producers expanding their scale and expanding their geographic coverage.
Recently, as world leaders debated the role of fossil fuels in global climate and climate change, the petrochemical industry has received some scrutiny. What is often overlooked in this debate is the economic contribution of the petrochemical industry and many different products with petrochemicals as the main component besides oil and natural gas.
First-class petrochemical products are divided into three categories according to their chemical structure:
Olefins include ethylene, propylene and butadiene. Ethylene and propylene are important sources of industrial chemicals and plastic products. Butadiene is used to make synthetic rubber.
Aromatic compounds include benzene, toluene and xylene. Benzene is a raw material for dyes and synthetic detergents. Manufacturers use xylene to produce plastic and synthetic fibers.
Syngas is a mixture of carbon monoxide and hydrogen used to produce ammonia and methanol. Ammonia is used to make fertilizers, and methanol is used as a solvent and chemical intermediate.
How to Choose a Heat Exchanger for Your Petrochemical Plant?
Of all process operations in a refinery or petrochemical plant, heating and cooling streams are probably the most common. A heat exchanger (also called a sample cooler) is used to cool the process flow sample. Each heat exchanger is a uniquely designed small tube inside the shell. The fluid that must be cooled flows through the tube side, and the coolant (usually water) flows through the shell side. A sample can then be taken from the coolant, and/or it can be analyzed or transported to online process instrumentation to continuously monitor the chemical properties.
Heat exchangers can cool and heat water, steam, gas, and hydrocarbons in petrochemical plants. For example, petrochemical plants usually produce samples of volatile hydrocarbons that exceed 500°F (260°C) and need to be cooled, while other fuels (such as diesel) may need to be heated before being sent to diesel for power generation machine. In petrochemical plants, there is usually no need to heat the liquid, and heating may change the physical properties of the liquid. However, many liquids and gases/vapors in petrochemical plants-including various glycols, olefins (such as ethylene, propylene. or butadiene), isomers (such as benzene, toluene, or xylene), and natural gas liquids (NGL) (E.g. ethane, propane. and butane)-requires cooling. Jarda's heat exchanger can cool any liquid or vapor.
High pressure and high temperature are typical requirements for heat exchangers used in the petrochemical industry, whether on land or at sea. The original fossil fuel contains a lot of water, and most of this process is dedicated to removing this water from the finished product. In this process, heating, cooling, and distillation operations are all critical, and energy recovery is also critical to maximize production efficiency. In many cases, especially in offshore and remote areas, space is very precious, and JIAERDA heat exchangers can be configured to provide maximum heat transfer in the smallest footprint
The common corrosion types of heat exchangers are:
1. Surface wear and corrosion
In the normal working process of the heat exchanger of chemical equipment, the relative speed of the metal components and the corrosive medium is relatively large, and the surface of the metal components is easily damaged by corrosion. This type of corrosion is surface wear and corrosion. Gas, liquid, or gas containing bubbling and solid particles are all flowing media that cause corrosion damage. In a sense, wear corrosion is the combined effect of the erosion of the corrosion products produced by the high-speed fluid on the metal surface and the surface corrosion of the exposed area. While the erosion of the surface that has already been corroded, it will also affect the corrosion. The newly exposed metal surface causes new corrosion and further damage to the equipment.
2. Stress corrosion
The corrosion phenomenon caused under the action of applied stress and residual stress is called stress corrosion. Stress corrosion can easily cause the fracture of heat exchanger materials and lead to production failures. At present, common stress corrosion mainly includes anodic solution stress corrosion and hydrogen-induced cracking stress corrosion.
3. Electrochemical corrosion
The high-speed fluid inside the heat exchanger can avoid fluid settlement and compaction, but certain medium deposition will occur during long-term use, especially in the area near the end of the work, the medium flow rate will decrease, and more deposits will be deposited in the heat exchange tube Sediment. The uneven distribution of deposits on the inner surface of the tube easily forms gaps and cracks, resulting in a difference in oxygen content between deposit gaps and gaps, causing electrochemical corrosion in some locations. The fast rate of electrochemical corrosion will further expand the corrosion area and cause greater harm to the heat exchanger.
4. Low temperature corrosion
When the heat exchanger is working normally, the temperature will gradually decrease after the flue gas enters the heat exchanger to start heat exchange. Under normal circumstances, there will be no condensation at the outlet of the air preheater of a coal-fired boiler, but there is often a certain amount of acid gas in the flue gas, which greatly increases the probability of acid condensation. If the temperature of the metal wall of the heat exchanger is lower than the dew point of the flue gas acid, the surface of the metal wall of the heat exchanger will condense flue gas and water vapor containing sulfuric anhydride, which will induce pipeline corrosion. This kind of corrosion is mainly caused by lower flue gas temperature and tube wall temperature, so it is called cryogenic corrosion.
5. Corrosion caused by water flow
Water is the most commonly used heat exchange medium for heat exchangers, and erosion and corrosion caused by water flow in the heat exchange tubes are relatively common types of corrosion. First of all, when the pH value in the water is unstable, especially when the pH value decreases and presents an acidic state and there is dissolved oxygen in the water, it is easy to induce a chemical reaction in the heat exchange tube to cause chemical corrosion. In addition, the harmful anions contained in the water, such as chloride ions and sulfide ions, the presence of these ions will also chemically react with the metal in the tube to cause electrochemical corrosion.