Week 5 Challenge
In this week the above questions are related to heat exchangers, to solve these questions i am using the heat exchanger option from the models and streams menu. These are just preliminary designs with slightly less accuracy and the detailed design of the exchangers will be done using Aspen Exchanger Design and Rating in subsequent challenges. In this week's challenge there are three questions with an exchanger each. The network is shown as below:
Q1. Here in this question it is asked to determine the cooling water quantity required to completely condense a hydrocarbon vapor stream. The hot stream is the hydrocarbon vapor stream with a higher temperature and the cold stream is the cooling water stream with a lower temperature. Since, the hot side is a vapor stream and following TEMA guidelines i have allocated the hot side as Shell side and the cold side as Tube side.
The Tube side and Shell side connections for the first exchanger are as follows:
The parameters of the heat exchanger are as follows:
The sizing details of the heat exchanger are as follows:
The conditions and composition of both the streams are as follows:
The Tube side and Shell side parameters are as follows:
The performance of the exchanger is shown in below image:
As it is seen from the images the cooling water flow required is 23910 Kg/hr.
NOTE: The cooling water inlet and outlet temperatures are not in the range as asked in the question. It is done so to avoid temperature cross error as the cold side outlet temperature was higher than the hot side outlet.
Q2. Here in this question it is asked to determine the saturated steam pressure required to completely vaporise a hydrocarbon liquid stream. The hot stream is the steam with a higher temperature and the cold stream is the hydrocarbon liquid stream with a lower temperature. Since, the hot side is a vapor stream and following TEMA guidelines i have allocated the hot side as Shell side and the cold side as Tube side. Also, with a higher pressure the hydrocarbon liquid stream is chosen as the tube side so that shell side has a lower pressure and ultimately the heat exchanger has a lower design pressure. Since, quantity of any fluid is directly related to the operating costs so to reduce the operating costs i have completely condensed the steam stream to use the latent heat for better heat exchange and less quantity of steam required.
The Tube side and Shell side connections for the first exchanger are as follows:
The parameters of the heat exchanger are as follows:
The sizing details of the heat exchanger are as follows:
The conditions and composition of both the streams are as follows:
The Tube side and Shell side parameters are as follows:
The performance of the exchanger is shown in below image:
As it is seen from the image the saturated steam pressure required is 3.418 bar.
Q3. Here in this question it is asked to determine the saturated steam quantity required to completely vaporise a hydrocarbon liquid stream. The hot stream is the steam with a higher temperature and the cold stream is the hydrocarbon liquid stream with a lower temperature. Since, the hot side is a vapor stream and following TEMA guidelines i have allocated the hot side as Shell side and the cold side as Tube side. Since, quantity of any fluid is directly related to the operating costs so to reduce the operating costs i have completely condensed the steam stream to use the latent heat for better heat exchange and less quantity of steam required.
The Tube side and Shell side connections for the first exchanger are as follows:
The parameters of the heat exchanger are as follows:
The sizing details of the heat exchanger are as follows:
The conditions and composition of both the streams are as follows:
The Tube side and Shell side parameters are as follows:
The performance of the exchanger is shown in below image:
As it is seen from the image the saturated steam quantity is 229.3 Kg/hr.