Chemical equipment is usually divided into which two categories, an inventory of common chemical equipment
Chemical production in order to process raw materials into a certain specification of finished products, often need to go through a series of chemical processes such as raw material pretreatment, chemical reactions and separation and refinement of reaction products, the machinery used to achieve these processes is called chemical equipment.
Chemical equipment is generally divided into two categories: static equipment and dynamic equipment.
Static equipment
Static equipment refers to equipment that is installed in a static state and does not require power transmission during production operations. Static equipment is widely used in the production of mass transfer, heat transfer, media heating, chemical reactions and other processes and storage of materials. Such as various vessels, towers, reactors,
Heat Exchangers, etc.
The investment in the static equipment part accounts for about 50%-60% of the total investment in the plant.
1.1
Distillation Tower Distillation is a chemical unit operation that uses the difference in volatility of the components in a liquid mixture to separate them, according to the distillation method can be divided into simple distillation, balanced distillation, distillation and special distillation and other ways.
If partial gasification or partial condensation is carried out several times, a purer lighter or heavier component can eventually be obtained, which is called distillation. The distillation tower is a tower-type vapour-liquid contact device for distillation, there are two main types of plate tower and
Packed Tower.
Plate tower by the cylindrical tower body and according to a certain spacing in the tower of a number of horizontal installed in the tower plate composition; packed tower is a tower of filler as a gas-liquid contact between the two phases of the mass transfer equipment, the tower is filled with the appropriate height of the filler, in order to increase the contact surface between the two fluids. The main differences between the two are as follows.
(1) packed tower operation range is small, for the liquid load changes are particularly sensitive. When the liquid load is small, the packing surface can not be well wetted, the mass transfer effect drops sharply; when the liquid load is too large, easy to produce liquid flooding. Plate tower has a large operating range.
(2) packing tower is not suitable for handling materials containing solids in suspension, and some types of plate tower (such as large aperture through the flow plate tower) can effectively deal with this material system, plate tower cleaning is also more convenient than the packing tower;.
(3) the pressure drop of the packed tower is smaller than that of the plate tower, thus more suitable for vacuum operation. Plate tower because each plate open rate of 5%-10%, and 25-50 mm clear liquid layer, so the pressure drop is large, each theoretical plate pressure drop of about 1Kpa; pressure drop is the main advantage of the packed tower, the regular packing about 0.15Kpa pressure drop;.
(4) for vacuum distillation and atmospheric distillation, packed tower efficiency is better than the plate tower, the reason is that the packing makes full use of the space in the tower, providing a large mass transfer area, so that the gas-liquid two phases can be fully contact mass transfer.
(5) plate tower than packed tower investment is smaller.
In the actual production process, distillation operations can be divided into intermittent distillation and continuous distillation two. For large production processes such as petrochemicals, continuous distillation is mainly used.
1.2 Heat exchanger
A heat exchanger is a device that transfers some of the heat from a hot fluid to a cold fluid. Petrochemical installations are commonly used shell and tube heat exchangers, U-tube heat exchangers, etc., and fine chemicals are commonly used disc condensers, spiral plate condensers, etc.
Shell And Tube Heat Exchanger is the most adaptable and widely used. In the case of medium pressure (4.0Mpa or less), the shell and tube heat exchanger is the most suitable, and the
U-Tube Heat Exchanger is suitable for operation under high pressure.
1.3 Air cooler
Air cooler is the ambient air as a cooling medium, so that the high-temperature process fluid in the tube to get cooling or condensing equipment, generally arranged in the top layer of the device. Its advantage over water cooling is that it saves a large amount of cooling water and reduces the problem of water pollution in industrial areas; the second advantage is that it saves investment and maintenance costs in the plant. Its disadvantage is the large footprint and high cost.
1.4 Heating Furnaces
Tube heating furnaces are used to heat the material passing through the furnace tube to the required temperature and then into the next process equipment for fractionation, cracking or reaction etc. Commonly used tube heating furnace according to its shape structure type is divided into cylindrical heating furnace, horizontal tube vertical heating furnace, vertical tube heating furnace, etc..
The tube heater is generally composed of a radiation section and a convection section. In the radiation section, the high-temperature flue gas is mainly radiated in the way of heat transfer to the radiation tube. The flue gas rises into the convection section, in which the flue gas mainly transfers heat to the convection tube in a convection manner. In order to improve the thermal efficiency of the heating furnace, waste heat recovery systems are commonly used, and high chimneys with centralised smoke discharge are used to reduce environmental pollution.
1.5
Storage Tanks Storage tanks are used to store liquids or gases in steel sealed containers that are steel storage tanks, according to the structure can be divided into fixed-top tanks, floating-top tanks, spherical tanks, etc. More than 50m3 for large tanks are vertical tanks; 50m 3 below for small tanks are mostly horizontal tanks, usually used for production links or gas stations.
1.5.1 Fixed-top storage tanks
Fixed-top storage tank is a steel container with a dome roof and cylindrical body, simple manufacture and low cost, so it is most widely used in many industries at home and abroad, with the most commonly used volume of 1,000 -10,000m 3 .
The fixed top tank has a certain volume of gas phase space at the top, the gas phase space will make the evaporation loss of the oil stored in the tank become larger, so the fixed top tank is not suitable for the storage of light oil and crude oil, mainly for the storage of flash point > 60 ℃ of various distillates, fuel oil, paraffin, low volatility and heavy oil.
1.5.2 Floating roof tanks
The floating roof tank is composed of a floating roof and vertical cylindrical walls floating on the surface of the medium. The floating roof increases or decreases with the amount of medium stored in the tank and rises and falls, with an annular seal between the outer edge of the floating roof and the tank wall, the medium in the tank is always covered directly by the inner floating roof to reduce medium volatilisation. Floating roof storage tank is divided into two forms of external floating roof and internal floating roof.
1.5.2.1 External floating roof storage tank
External floating roof storage tank is suitable for the construction of large volume storage tank, the construction of large volume storage tank can not only save the steel consumption and construction investment per unit of oil storage volume, and can reduce the area of the tank area, save tank accessories and tank area pipeline network.
However, the floating roof of the tank is directly exposed to the atmosphere, the stored oil is easily tainted by rain, snow and dust, so the external floating roof tank is mostly used to store crude oil, ethylene raw materials, less used to store refined oil.
The maximum volume of external floating roof storage tank is 150,000m.
1.5.2.2 Inner floating roof storage tank
Inside the floating roof storage tank is in the vaulted roof storage tank inside the additional floating roof and become, the tank to add a floating roof can reduce the loss of media volatilization, the external vault and can prevent rain, snow and dust into the tank, to ensure that the tank media clean. These tanks are mainly used for storing light oils such as petrol, aviation paraffin etc.
The maximum volume of the internal floating roof is 30,000m.
1.6 Reactors
The
Reactor is the equipment that realises the reaction process and is the central part of the chemical production process. Reactors can be broadly divided into tubular, kettle, tower, fixed-bed and fluidised-bed types according to their structure, with reactors commonly used in fine chemicals.
A fixed bed is a reactor filled with a solid catalyst or solids to achieve a multi-phase reaction process. The solids are usually granular, with a particle size of about 2 - 15mm, and are stacked into a bed of a certain height (or thickness). The bed is stationary and the fluid passes through the bed for reaction, mainly used to achieve gas-solid phase catalytic reactions, such as ammonia synthesis towers, sulphur dioxide contact oxidisers, hydrocarbon steam reformers, etc.
A fluidised bed is a reactor that uses gas or liquid to pass through a granular solid layer while the solid particles are in suspension and carry out a gas-solid phase reaction process or a liquid-solid phase reaction process. When used in gas-solid systems, it is also known as a boiling bed reactor.
2 Dynamic equipment
Dynamic equipment refers to rotating equipment driven by a driving machine, such as pumps, compressors, fans, motors, as well as forming machines, packaging machines, mixers, etc.
2.1 Pumps
The pump is a machine that conveys liquid or pressurizes liquid, it is the mechanical energy of the motor or other external energy transfer to the liquid, so that the liquid energy increases. Pumps for petrochemical installations are divided into three main categories, namely centrifugal pumps, reciprocating pumps and rotary pumps.
2.1.1 Centrifugal pumps
Petrochemical plants mostly use centrifugal pumps, accounting for about 80%-90% of the total number of pumps used in the process. Centrifugal pumps are the most economical to operate and have a small maintenance workload.
2.1.2 Reciprocating pumps
Reciprocating pumps have a plunger that moves backwards and forwards to displace the liquid and force it to stay out of the outlet nozzle. Reciprocating pumps include piston pumps, plunger pumps (metering pumps) and diaphragm pumps.
2.1.3 Rotary pumps
Rotary pumps are used to transport heavier or more viscous materials, such as grease, asphalt, heavy fuel oil, etc. Rotary pumps include gear pumps, screw pumps, etc.
2.2 Fans
Fans are machines that rely on the input of mechanical energy to increase the pressure of gases and displace them. Commonly referred to as fans include: induced draft fans, blowers, etc.
2.3 Compressors
The compressor raises the low pressure gas to a high pressure gas as a driven fluid machine. Chemical production plants are commonly used in the centrifugal compressor, reciprocating compressor, etc..
In the centrifugal compressor, the gas enters from the axial direction, due to the rotation of the impeller, the gas is centrifugal force tells thrown out of the impeller, and then enters the circulation area gradually expanded expander, the kinetic energy into pressure energy.
Chemical machine. Refers to machinery in which the main acting parts are moving, such as various filters, crushers, centrifugal separators, rotary kilns, mixers, rotary dryers and fluid transfer machinery.
Chemical equipment. Refers to machinery whose main parts are stationary or have only little movement, such as various containers (tanks, jars, kettles, etc.), common kilns, towers, reactors, heat exchangers, common dryers, evaporators, reactors, electrolytic tanks, crystallisation equipment, mass transfer equipment, adsorption equipment, fluidisation equipment, common separation equipment and ion exchange equipment.
The division of chemical machinery is not strict, some fluid transfer machinery (such as pumps, fans and compressors, etc.) in the chemical sector is often called chemical machinery, but at the same time they are a variety of industrial production in general machinery. The characteristics of the chemical machinery itself must be able to adapt to the chemical process often encountered in the high temperature, high pressure, high vacuum, ultra-low pressure, flammable, explosive and strong corrosive and other special conditions.
① with the safety and reliability of continuous operation.
② Sufficient mechanical strength under certain operating conditions (e.g. temperature, pressure, etc.).
③Excellent corrosion resistance.
④Good sealing properties.
⑤High efficiency and low energy consumption.
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Source: sage.com
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