Rosemount integrated flowmeter DMAC solution measurement solution in acrylic fiber plant

　　Results
　　Good measurement repeatability
　　Low installation cost
　　Eliminate leakage hazards

Application DMAC solution flow measurement problem
　　in the acrylic fiber plant of Jilin Chemical Fiber Group 　　The measurement of DMAC solution flow in the acrylic fiber plant of Jilin Chemical Fiber Group is used to adjust the DMAC concentration in spinning production and the amount of spinning oil added, so an accurate flow meter is required. Solution 　　By providing higher and more stable differential pressure output and adopting the best pressure sensing technology, the Rosemount 3051SF flowmeter can meet the accuracy level and overall performance required by the owner. Challenges 　　The production process of the acrylic fiber plant adopts the world's advanced DMAC wet two-step method to produce acrylic fiber. The spinning solution passes through the spinneret and the coagulation bath to form filaments. The DMAC concentration in the coagulation bath directly affects the product quality. The company uses Rosemount integrated intelligent flowmeter to measure the flow of circulating DMAC in the spinning coagulation bath. Its signal enters YOKOGAWA's Centum CS DCS system to adjust the liquid concentration in the system in a timely manner. The flow of the added oil is measured in the solvent tank. The control of the oil directly affects the softness of the acrylic fiber. In the early stage of the project, the split installation was used as shown in Figure 1. It was divided into several parts such as the transmitter, the measuring orifice plate, and the three-valve group. The parts were purchased separately and connected in sections, which resulted in many faults such as product quality differences, complex connections, and multiple leakage points. What is more serious is that the measurement accuracy is low, affecting the adjustment and control accuracy of the system. The application of ROSEMOUNT integrated flowmeter as shown in Figure 2 fundamentally solves the above problems. Thus, the process requirements are met. 　　Figures 3 and 4 show the flowmeter for measuring oil. The measurement range is about 50KG/H, the viscosity is relatively large, and the measurement is difficult. The process requirements are relatively strict. The accuracy is relatively high. In the early stage, the integrated flowmeter with a straight pipe section of other companies was used. As can be seen from Figure 5, the distance between the pressure tapping hole and the measuring element is large, which is easy to cause blockage and affect the process production. Rosemount's integrated flowmeter solves this problem and meets the process requirements. The maintenance and repair volume is relatively small, and it has also been well received by the on-site maintenance personnel. 　　In addition, Jilin Chemical Fiber Group is extremely concerned about cost. Installing traditional orifice plates on pipelines will make the cost quite high. Initially it was decided to bid the flowmeters separately in individual components, such as primary elements, valve blocks and transmitters. However, this could easily lead to the following problems: if an installed device did not meet the specification requirements, it would be difficult to determine which part of the flowmeter had failed, which would lead to suppliers shirking responsibility.















Jilin Chemical Fiber Group[page]

Solution
　　Emerson engineers provided Jilin Chemical Fiber Group with a measurement solution that offered lower installation costs, lower pressure loss and better overall performance. In stark contrast to the traditional orifice plate combination solution that requires installation of flanges, valve blocks, pressure pipes, isolation valves and connectors, they recommended the Rosemount 3051SFA integrated flowmeter - a set of devices consisting of an orifice plate, an integrated valve block and a direct-mount transmitter, which is factory assembled and tested and can be installed out of the box.

　　The 3051SF is an integrated flowmeter that does not require installation accessories, piping, valves, joints, valve blocks and mounting brackets. With only one pipe opening, installation time and cost can be minimized. And, with no pressure pipes and connectors, many potential leak points are eliminated.


Figure 2 ROSEMOUNT flowmeter at the same location in a later project

Figure 3 DMAC solution flow rate in the early stage project

Figure 4 ROSEMOUNT flowmeter at the same location in the later project

Figure 5 Comparison between ROSEMOUNT flowmeter and flowmeters from other companies