Spent nuclear fuel and many areas where nuclear reactor materials have been accidentally released to the environment mainly contain quantities of two radioactive isotopes, strontium 90 (⁹⁰Sr) and cesium 137 (¹³⁷Cs). A nuclear underground waste storage tank contains 100 curies of each of these two isotopes. Plot the activity of each as they decay over the next 500 years. How much of each will remain after 300 years? Use half-lives from this web site: http://atom.kaeri.re.kr:81/ton/index.html

The emissivity coefficient of an oxidized iron surface is 0.612 and the same value can be accepted for the absorption coefficient of radiation received from the environment. Calculate the heat lost per square meter of the surface that is at 80 ° C, located vertically in a 20 ° C environment.

A flat furnace wall is constructed of a 4.5 in (114 mm) layer of Silo-cel brick, with a thermal conductivity of 0.08 Btu/ft·h·˚F (0.138 W/m·˚C), backed by a 9-in. (229-mm) layer of common brick, of conductivity 0.8 Btu/ft·h·˚F(1.38 W/m.˚C). The temperature of the inner face of the wall is 1400˚F (760˚C), and that of the outer face is 170˚F(76.6˚C).

(a) What is the heat loss through the wall?

(b) What is the temperature of the interface between the refractory brick and the common brick?

(c) Supposing that the contact between the two brick layers is poor and that a “contact resistance” of 0.50˚F·ft2.h/Btu (0.088˚Cm2/W) is present, what would be the heat loss?

An evaporator-crystallizer process is used to obtain solid potassium sulfate. The fresh feed to the evaporator contains 19.60% K₂SO₄ and is mixed with the recycled mother liquor stream before entering the evaporator. The crystal product of the crystallizer is still wet as it contains 10.00 kg solid K₂SO₄ per kg adhering mother liquor solution. The filtered mother liquor contains 40.00% K₂SO₄ and is recycled to join the fresh feed. Of all the water entering the evaporator, 45.00% is evaporated. The evaporator has a maximum capacity of 175.0 kg/s water evaporated. If the system is kept running at maximum capacity, determine the following:

1. Flow rates of feed, crystal product, recycle, and mixed feed
2. Composition of mixed feed in % by mass
3. If we want to have a higher quality crystal product (meaning, K₂SO₄ crystals with a lesser water content), what unit do you suggest we add to the process? Where do we add the unit?
4. How much water needs to be removed from the crystal product to obtain pure K₂SO₄ crystals?

Using The Degree of Advancement Variable

Methane and oxygen react in the presence of a catalyst to give formaldehyde. In a parallel reaction, methane is oxidized to carbon dioxide and water:

CH4 + O2 = HCHO + H2O

CH4 + O2 = CO2 + H2O

The reactor feed contains equimolar amounts of methane and oxygen. Assume as a base a feed of 100 mol / s.

The methane conversion fraction is 0.90 and the formaldehyde yield fraction is 0.855. Use the reaction advance degree method to determine the molar composition of the reactor outlet stream and the selectivity of formaldehyde production relative to carbon dioxide production.

1200 cm³/sec of water at 420 K is pumped in a 40 mm internal diameter pipe

through a length of 150 m in a horizontal direction and up through a vertical length of 10 m . In the pipe there is a control valve which may be taken as equivalent to 200 pipe diameters and other pipe fittings equivalent to 60 pipe diameter. Also in the line there is a heat exchanger across which there is a loss in head of 1.5 of water. What power must be delivered to the pump if the unit is 60% efficient?

PS: roughness factor not given

A chemical company propose to build a formaldehyde production plant using catalytic oxidation of methanol method. As a group of engineers in the company, you are assigned to write a material balance proposal for the plant. The material balance proposal should consider the following steps; a) Introduce background and reactions involve in the production of formaldehyde through catalytic oxidation of methanol method. Hence, identify the required raw materials for the process. b) Propose a process flow diagram, which consider mixer, reactor and separator as the main equipment. Unreacted reactants should be recycled, however 20% of the unreacted methanol should be send to the product stream of the separator as product stabilizer. 2 c) State basis of calculation and solve the material balance when overall conversion of methanol is within (80-90) %. Ratio on the amount of feed reactants should be fixed accordingly before entering the reactor. d) Present the material balance summary (from part c) in a form of table. The summary should consist of the mole and mass flowrates and compositions of each stream. Material balance of the process should be validated as a conclusion to prove the proposed design. e) You propose to further purify the produced formaldehyde from separator (part c) through reducing the amount of water content by 50%. The purification process should be performed in a condenser and consider only the water that condense. Determine composition of the gas and liquid outlet streams of the condenser. The produced formaldehyde gas mixture from separator enters the condenser at temperature of 120oC and should be cooled at constant pressure in the range of (500-600) mm Hg. In the condenser, vapour is in equilibrium with liquid, and the vapour is ideal. Use the pre-determined composition of water in gas outlet stream to determine the Tdp and set the outlet temperature of the gas mixture. The outlet temperature should not be set below the Tdp of methanol and formaldehyde of the mixture. Justify and prove your choice. f) The produced formaldehyde from condenser (part e) is then pump to a 300 L storage tank. The gas temperature should be set within (20-30)oC. Identify the suitable pressure to be set for the storage when the gas mixture is considered as i) an ideal gas and ii) non-ideal gas. Evaluate and discuss on the determined pressure.

. What are your thoughts on whether a facility should only worry about complying with the OSHA regulations or go beyond compliance and use the stricter requirements of either OSHA regulations or other guidelines? Please include any personal experiences you might have.

Give your own examples of Heating Curve for water. Below I have kay questions.

1. Understand the different segments in the heating curve for H2O that ranges from below the melting point to above the boiling point.

2. Calculate the energy changes associated with heating a substance (like H2O) through a series of temperature changes and phase changes. Please give your own examples of Phase Diagrams. Below I have key questions

3. Know that a phase diagram relates the states of matter for a substance to temperature and pressure.

4. Identify the main regions and significant points in a phase diagram. 5. Understand the effect of changes in temperature and changes in pressure on the phase of a substance as shown by its phase diagram.

Tray dryers operate by passing hot air over the surface of a wet solid that is spread over trays arranged in racks. They are most widely used in the food and pharmaceutical industries. Its main advantage being its simple operation. However, it has the disadvantage of long drying times. From the concepts of drying that you have learned, what will you suggest to lessen drying time for tray dryers?

Coconut oil is to be produced from dry copra in two stages. First, through expellers to squeeze out part of the coconut oil and then through a counter current multi- stage solvent extraction process. After expelling, the dry copra cake contains 25% residual oil. In the solvent extraction operation, 95% of the residual oil in the expeller cake is extracted as a solution containing 50% by weight oil. After the extraction process, the wt of insoluble cake was found to be 50kg. If solvent containing 1% oil is used and one kg of solution with every 2 kg of insoluble cake is removed with underflow. How many stages are required? If 1kg of solvent with every 2 kg of insoluble cake is removed with the underflow, how many stages are required?

An equimolar liquid mixture of Benzene (B) and Toluene (T) at 20^oC is fed continuously to a flash drum in which is heated to 60 ^oC. The liquid product is 40 mole % B and the vapour product is 60 mole % B. How much heat must be transferred to the mixture 100 mol of feed.

A milk sample deteriorates following the first order reaction kinetics.
a) It deteriorates 40 times faster at 250C than when it is stored at 40C. Calculate the activation energy in kJ for the milk breakdown reaction.
a) Find the rate constant if 80% of the milk deteriorates after 12 hours at 250C.

How to determine coefficients for equilibrium constants?

The equilibrium constant built in aspen has the following equation:

ln (Keq) = A + B / T

How to determine these coefficients: A, B

Methane reacts with chlorine to produce methyl chloride and hydrogen chloride. CH4 + Cl2 → CH3Cl + HCl Once formed, methyl chloride can be chlorinated in subsequent reactions to form methylene chloride (CH2Cl2), chloroform (CHCl3) and carbon tetrachloride (CCl4). In a methyl chloride production process a reactor is fed with methane and chlorine in a molar ratio of 5: 1 (methane: chlorine). In the process the chlorine is consumed in its entirety. The selectivity observed in the process is 4 mol of CH3Cl / mol of CH2Cl2 and negligible amounts of chloroform and carbon tetrachloride. The product stream of reactor passes to a condenser where CH3Cl and CH2Cl2 are separated in liquid form, and CH4 it is separated from the HCl to be recirculated to the process (only CH4 is recirculated). The production of CH3Cl is 500 kmol / h. Calculate the flow and molar composition of the fresh feed, the HCl flow that occurs and the flow of methane recirculation.