Fluid Mechanics, Heat Transfer, and Thermodynamics Design Project
Production of Acrylic Acid
We are investigating the feasibility of constructing a new, grass-roots, 50,000 metric tons/year, acrylic acid production facility. As part of the feasibility study, we would like you to investigate some of the details of the feed and reaction sections of the proposed plant.
Acrylic Acid Production Reactions
The reactions are given below. The primary reaction is:
C H O C H O H O3 6 2 3 4 2 215+ ® +. acrylicacid
The secondary reactions are:
C H O C H O CO H O3 6 2 2 4 2 2 225+ ® + +. acetic acid
C H O CO H O3 6 2 2 245 3 3+ ® +. (3)
For the purposes of this preliminary evaluation, ...view middle of the document...
3 bar and 190°C. Heat generated in the reactor is removed by Dowtherm AÔ, which is thermally regenerated in E-301. If the Dowtherm pressure is maintained above 10 bar, it is not volatile up to 400°C. The reactor exit temperature is 290°C. Following the reactor, the reaction products are quenched with sufficient deionized water to bring the temperature of the stream to 200°C. The crude acrylic acid product is obtained by flashing the quenched reactor effluent. It may be assumed that all light gases (N2, O2, CO2) leave in the vapor phase. All other components distribute between the vapor and liquid phases. The temperature of any liquid stream containing acrylic acid may never exceed 90°C to avoid spontaneous polymerization.
Your assignment consists of three "mini-designs."
1. Optimization of the Feed Section. (ChE 110(fluids) and 142(thermo)) Refer to Figure 1. You are to determine the optimum pipe sizes for Streams 1-4. Equivalent pipe lengths can be determined from the attached plot plan (Figure 2). Pipe runs are at 4 m elevation off the ground, and you should add 90° elbows as necessary. The objective function is the Equivalent Annual Operating Cost (EAOC) of the feed section ($/y). The EAOC is defined as:
EAOC CAP A P
i n= æ èç
+, , operatingcostsfor feed section loop (4)
where CAP = the installed cost of equipment in the feed section and
( ) ( )[ ]
i n i i
n , ,æ
èç ö ø÷
1 1 (5)
where i = 0.15 (15% rate of return) and n = 10 (ten year plant life).
For the feed section, do not include tank costs, so CAP includes the cost of pipes, pumps (if needed), and compressors and operating costs include the electricity to run the pumps and/or compressors. You are also to size and cost the feed tanks (1 day of
liquid storage needed - 2 tanks required, one for filling and one for feeding - assume 70% full with liquid) and determine the conditions for propylene storage. Propylene is to be stored as vapor/liquid mixture. Specify the elevation of the tank. We have a supply of centrifugal compressors used in other plants. The compressor curves are also attached (Figure 3). We would like the flexibility for 35% scale-up in the future.
2. Optimization of the Dowtherm AÔÔ Loop. (ChE 110 (fluids) and 111(heat)) The heat exchanger, E-301, must be designed in detail. The heat exchanger, pipes, and pump should be optimized together. CAP should include the costs of the pump, of the pipes, and of the heat exchanger. Operating costs should include the cost of pumping and the cost or credit for the heat removal medium in the heat exchanger. We also have a supply pumps used in our other plants which we would like to use in this plant. The pump curve is attached (Figure 4). This curve is for the pump having a 4 in impeller diameter. A 4.75 in impeller diameter can also be used. The pump efficiency is 80%, and is assumed...