Slide valve
1. Overview
The slide valve is a key control valve used in the refining and chemical catalytic cracking unit. The double acting slide valve is installed on the flue gas pipeline at the top outlet of the first and second regenerators of the heavy oil catalytic cracking unit to control the pressure of the regenerator or the pressure difference between the two regenerators. The single acting slide valve is installed between the two regenerators and on the catalyst circulation pipeline between the regenerator and the settler, riser, external heat exchanger, and scorching, which is used to control the amount of catalyst circulation and cut off the catalyst circulation in case of starting and shutting down or accidents.
According to the size and form of the catalytic cracking unit, each unit adopts one to two double acting slide valves and multiple single acting slide valves. According to the requirements of the device for the control accuracy and cost of the slide valve, the control system of the slide valve can choose electro-hydraulic or pneumatic control. According to the device's requirements for the temperature of the outer wall of the control pipeline, the valve body part of the slide valve can use cold wall (outer wall temperature<350 ℃) or hot wall (outer wall temperature>350 ℃).
2. Product characteristics
·High sensitivity: for regulating signals of 4-20mA, the sensitivity of pneumatic slide valves can reach 1/200, and the sensitivity of electro-hydraulic slide valves can reach 1/1000.
·High accuracy: for regulating signals of 4-20mA, the accuracy of pneumatic slide valves can reach 1/100, and the accuracy of electro-hydraulic slide valves can reach 1/1000.
·High temperature resistance: the internal parts of valve body are all made of high-temperature resistant high alloy steel, which can operate at high temperatures for a long time.
·Erosion resistance: the inner throttle cone flow surface of the valve body, the sealing surface of the valve disc and orifice plate are lined with wear-resistant lining, the sliding surface of the valve disc and guide rail and the contact surface with the medium are surfacing with drill based cemented carbide, and the outer surface of the valve stem is sprayed with dart based cemented carbide.
3. Valve characteristics
The valve body of cold wall single and double acting slide valve is Q245R or Q345R steel plate welded round cylinder with the same diameter three-way and reduced diameter four-way structure. The valve body is internally lined with a double layer of turtle shell mesh lining (insulation lining and wear-resistant lining),
The orifice plate opening of the single acting slide valve is a combination of semi-circular and rectangular shapes, which can avoid severe erosion and wear of the two corners in front of the rectangular valve port and the nearby valve body. The orifice plate opening of the double acting slide valve is rectangular, which can effectively reduce severe erosion of the downstream pipeline lining.
The stuffing box on the valve bonnet is equipped with inner and outer layers of packing, and the liquid packing injection port is facing the oil ring inside the inner packing. Once leakage is found in the packing, liquid packing can be injected inward at the liquid packing injection port to seal the leakage point and maintain the sealing effect of the inner packing. Under the normal adjustment state of the valve, it is convenient to replace the outer packing.
The orifice plate, valve disc, and guide rail are made of high-temperature alloy steel. The guide rail adopts a concave or L-shaped cross-section, which is conducive to resisting erosion. Wear-resistant lining is lined around the valve port of the orifice plate and the head and surface of the valve plate. The two lining surfaces that move relative to the orifice plate and the valve disc are grinded after sintering. The surface is smooth, and the sliding clearance is uniform to prevent the valve disc from jamming and improve its wear-resistant performance.
The surface of the valve stem is sprayed with hard alloy, and the surface hardening layer is thick and uniform, with a smooth surface, which is conducive to improving the sealing performance of the packing.
4. Product performance
Single acting slide valve: inner diameter after lining DN75～DN1960
Double acting slide valve: inner diameter after lining DN400～DN3200
Design temperature: 720℃-900 ℃
Since the 1950s, Bohai Equipment Lanzhou Petrochemical Equipment Company has developed and produced the first domestic IV type catalytic cracking single and double acting slide valves for the first IV type catalytic cracking unit in New China.
In the 1980s, domestic catalytic units transitioned from IV type catalytic cracking units to riser and coaxial catalytic cracking units. Petrochemical Equipment Company also developed single and double acting slide valves for riser and coaxial catalytic cracking units for many domestic refineries.
Since the 1990s, with the rise of domestic heavy oil catalytic cracking, the accompanying cold wall single and double acting slide valves were first born in Petrochemical Equipment Companies. Until the late 1990s, Petrochemical Equipment Company had a 100% market share in the domestic slide valve market.
At present, Petrochemical Equipment Company has a market share of 80% in the domestic slide valve market.
·Single and double acting slide valves won the National Science Congress Award in 1978.
·Single and double acting slide valves won the Science and Technology Achievement Award of Gansu Provincial People's Government in 1978.
·Pneumatic regulation pneumatic riser pipe slide valve won the third prize of Sinopel Science and Technology Progress Award in 1989.
·Cold wall electro-hydraulic control slide valve (in cooperation with LPEC) won the second prize of Sinopec Science and Technology Progress Award in 1991.
·Cold wall electro-hydraulic control slide valve (in cooperation with SEI) won the third prize of Sinopec Science and Technology Progress Award in 1991.
·Pneumatic regulating pneumatic slide valve won second prize of Sinopec New Products in 1991.
·Electro-hydraulic control cold wall slide valve won the National Science and Technology Commission Science and Technology Progress Award in 1992.
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