The manufacturing process of impervious graphite equipm […]
The manufacturing process of impervious graphite equipment and its components varies with the structure of the equipment. Impervious graphite has similar mechanical processing properties as cast iron. It has a lower hardness than cast iron. Generally, it can be processed by metal cutting tools or woodworking tools, such as turning, planing, milling, drilling, sawing, and grinding. Due to the poor strength and brittleness of graphite itself, two dipping and two processing methods are generally used to improve its strength and ensure processing accuracy.
The processing and manufacturing of impervious graphite equipment should implement relevant standards such as "Technical Conditions for Graphite Chemical Equipment" (HG 2370), strictly control all construction links, and ensure the quality of construction.
Graphite materials are hard but brittle and easily cracked. Therefore, graphite material and any of its components and products must be handled lightly during any handling process, and littering is strictly prohibited. During the machining process, when clamping is required, the force should be uniform to avoid excessive local stress. In the process of machining and assembly, it is strictly forbidden to beat with a metal hammer. Where it must be beaten, a rubber mallet should be used to beat.
1. Material selection and splicing
(A) choice of materials
To make impervious graphite equipment, the first step is to select the material. China's current production of impervious graphite equipment is mainly artificial graphite (such as electrode graphite). In the manufacturing process of artificial graphite, volatiles escape due to high-temperature firing, so that many fine pores are formed. Sometimes graphite electrode materials will also generate cracks in the vertical and horizontal directions during the firing process. So pay attention to the following points when selecting materials.
① Do not mistake carbon material as graphite material. Because the thermal conductivity of carbon materials is 10.47W / (m • ºC), and the thermal conductivity of graphite materials is 116.3 ~ 151.19W / (m • ºC), the thermal conductivity of the two materials differs by more than ten times. Therefore, the selection of materials for heat exchange equipment should be strictly controlled. Carbon materials are hard and extremely difficult to process.
② Pay attention to whether there are cracks in the vertical and horizontal directions of the graphite blank material. Crucible materials cannot be selected, especially materials with longitudinal cracks. Materials with cracks in the transverse direction should avoid cracks when cutting, and select useful parts.
③ Graphite materials should not be used when the porosity is greater than 32% or there are too many large trachoma larger than 5mm. Because the porosity is too large, the resin immersion amount is too large during impregnation, so the thermal conductivity of the impermeable material produced is small, and it is inappropriate to use it as a heat transfer element in heat exchange equipment.
④ According to the requirements of different graphite equipment or different parts, choose graphite materials of different varieties and specifications.
(II) Material splicing
When the maximum size of the part exceeds the maximum size of the graphite blank, the graphite parts need to be spliced. When splicing graphite parts, please pay attention to the following points:
(1) During splicing, there must be no debris such as dust, oil, and residual resin on the bonding surface, and the bonded surface must be mechanically processed and removed;
(2) The bonding seam must be tight, the adhesive must be full, and the width of the seam should not be greater than 1mm;
(3) Step-shaped stitching should be used as much as possible when stitching. When multi-layer stitching is used, the stitching seams should cross to avoid sky seams.