Papers by Keyword: Descaling

Abstract: Wool is a special material with the shape memory capability, so it can be used not only for apparel but also for functional applications such as protecting clothes and thermo-regulating clothes. However, wool fibers have a surface structure of overlapping cuticle cells known as scales which significantly affect fiber properties. This research investigated the appearance, strength, extension and the shape memory behavior of the wool yarn and also the wool knitted fabric before and after descaling its cuticle cells using calcium carbonate (CaCO₃) powder with the concentration of 5 g/l, 10 g/l, 15g/l, and 20g/l in ultrasonic bath. The results showed that ultrasonic wave and abrasive calcium carbonate powder could reduce the size and the sharpness of wool scale. Wool yarn breaking strength and elongation tended to increase due to the increase of CaCO₃ concentration, while the value of CV (%) decreased. The shape memory behavior was evaluated according to the change in length for the wool yarn, and the change in loop dimensions for the knitted fabric in different environmental humidity and temperature. Wool yarn descaled with CaCO₃ powder showed more change in length in comparison to original yarn, but the change was a little bit of less than 3%. For the wool rib knitted fabric, the change in vertical direction was negligible, while the change in horizontal direction was significant, especially in the case of rib knitted fabric made of wool yarn descaled with CaCO₃ powder. Wool yarn descaled showed a little change in length while the wool knitted fabric showed the more stable in shape by the course direction in comparison to those before descaling treatment.

Abstract: In order to improve the energy efficiency of shot blasting impact descaling, a three-dimensional finite element impact descaling model was established. Based on the finite element model, the cracking behavior of the scale layer on hot rolled strip from different impacts angles was simulated. The results of finite element calculation and theoretical analysis show that: (1)Under the premise of constant velocity, the descaling area increases with the increase of impact angle, but the increasing rate tends to be moderate. (2)The depth of the impact tunnel and the residual compressive stress surface (-200 MPa) increase as the impact angle goes bigger. The ideal range of impact angle for shot blasting descaling should be 60°-75°.

Abstract: One of the most effective methods for descaling hot-rolled steel products is performed using highpressure flat jet nozzles. These descaling nozzles are arranged in rows in hot rolling mills and areset in such a way that each adjoining pair of nozzles creates an overlapping area of water jet streams.Good homogeneity of the pressure distribution over the width of the hot-rolled plate is often used as anindicator of quality of the homogeneity of descaling. The presented laboratory measurements examineone pair of adjoining nozzles with a particular focus on the pressure distribution in the overlappingarea. This paper deals with one particular setting of a pair of descaling nozzles with zero offset anglesfor the jet streams. A measured pressure distribution and an outcome of an erosion test on an aluminumplate are presented and discussed. The erosion test shows that spots with higher pressures do notnecessarily result in a higher amount of removed material during an erosion test. The erosion test differs from the expected outcome in such a way that a detailed discussion of this phenomenon is outlined with possible explanations.

Abstract: Copper is accumulated in recycled steels and is difficult to be removed during steelmaking processes when steel scrap is used as steel sources. Meanwhile, copper characteristics are of importance both to human beings and to animals and plants. In this paper, integrated copper coating was observed on the surface of copper-containing steels when the steels were heated at around 1150°C. However, the copper was separately scattered in and under the surface rust after heating at 1000°C. The forming mechanisms of copper coating are discussed in detail. By choosing a proper descaling reagent, self-generated oxidation-induced copper coating appeared on the steel surface. The method proposed in this work is environmentally friendly for nontoxic chemicals being used. In addition, this provides a new concept for producing protective composite by oxidizing from the substrate directly and there is no bonding problem.

Abstract: Hydraulic descaling system is the key device to ensure the surface quality of billet. However, traditional control methods lead to the stability problem in hydraulic descaling system. To solve the problem, the construction of the hydraulic descaling computer control system is studied, the working principle of the system is analyzed, and the high pressure water bench of hydraulic descaling is designed. Based on it, the corresponding computer control software is developed. The application shows that the designed system is stable in practice, which is helpful for enterprise production.

Abstract: In the northern cold areas, the circulating cooling water contains a large number of low temperature waste heat.Cold and heat sources can be used as a heat pump heating to the building. The experiment shows that the system has significant economic, energy conservation and environmental value. This article describes the plant circulating cooling water source heat pump system, water quality, corrosion and fouling problems, and solve these problems need to pay attention.

Abstract: Some surface defects on hot rolled steels arise due to poor descaling. Generally reheated slabs are efficiently descaled but, now and then, residual scale remains on the slab after primary descaling. Commonly it is difficult to trace the few poorly descaled slabs since there often is no scale monitoring system. In the work presented here an image based primary scale monitoring-and evaluation system is presented. It is a stand-alone online vision system consisting of a camera connected to a computer. The camera is located directly after the descaling unit and the computer in the control room. The program automatically locates the boundaries of the top surface of a slab and calculates the quantity of residual scale on the top surface. The quantity of residual scale is logged and can afterwards be evaluated together with process parameters and downstream surface defects to identify problem areas. The system has been tested in industrial scale in the Ruukki plate mill. This work is a cooperation between Swerea MEFOS and Ruukki. The result of the test demonstrated the feasibility of using vision system for detection of residual scale. Some problems were identified and suggestions for solving them are reported. If the suggested modifications are carried out, it is believed that the vision system can be an on-line tool for the operator and also be an off-line resource for the ongoing quality work at the hot rolling mill.

Abstract: This paper expatiated on principles of high pressure abrasive water jet descaling; used GAMBIT and some experience parameters to create the geometry model of the nozzles and the outflow field; used Fluent to simulate the high pressure abrasive water jet under the condition of different jet standoff distance, different impact angle, different mix angle, different abrasive particle size, different abrasive concentration and different abrasive material. Through the analysis of the simulation results, this paper put forward the optimal selection of these parameters.

Abstract: Silicon is an effective element to improve steel hardness by solid solution hardening. However, it is difficult to remove the scale formed on high Si contained steels. In the present study, descaling tests were carried out with three heat patterns of oxidation treatments to make clear the effect of oxidation temperature on descaling properties of the scale formed on Si containing steel. Two-step heating at 1210 °C-1140 °C shows the best descaling results. Descaling properties should be influenced by scale morphology and structure at the scale / steel interface. Furthermore, the results of present study suggest that fracture behavior of the scale, which is controlled by voids and cracks, is also important factor for descaling properties.

Abstract: Through analyzing the causes and damage of the fouling in water channel of water cooling engine, this paper develops a new kind of compound cleaning and descaling agent and conducting polyaniline corrosion agent of the water tank. This new cleaning agent is stable and harmless, and can be added to the cooling system directly without the special equipment. With the circulation of the coolant, the agent can remove the scale, and then the removed scale flows out of the auto with the coolant. Except for this new cleaning agent, the antiseptic, whose major agent is the conducting polyaniline, can decrease and even stop the corrosion of the water tank and cooling system’s parts, and at the same time, the formation of the scale can also be restrained notably. When the agent is in use, it can be added(press 1% ratio to join) wholly into the water port, or complemented at any time, so that the quick cleaning and the anticorrosion are realized without disassembling and corroding the engine. By using these agents the cleaning efficiency of the engine cooling system is improved, the favorable engine’s technology situation is kept, and the engine’s life-span is also increased efficiently.