Tieng anh nganh hoa

B. Answer the following questions
1. What are the various processes for water treatment?
2. What is the method for removing the suspended solids from surface waters?
3. What are the principal sediments from water of streams?
4. What are the methods for trapping the microorganisms from various kinds of water?
5. What is the purpose of chlorination of water?
6. What is the substitute for chlorination of water?
7. What is the kind of physical agent for water treatment of microorganisms in Vietnam?
8. Say a few words about the water treatment in Vietnam.
C. Translate into English
1. Hu ht các thành ph u s dng ngun nc b ô nhim khá cao.
2. Quá trình x lý nc bao gm các quá trình khác nhau nh: lc, ông t, lng, kh trùng.
3. Các cn lng trong nc bao gm các ht t sét hoc các cht hu c, vô c hòa tan và c các vi
sinh vt na.
4. kh trùng nc có th dùng nhiu ng pháp: clo hóa, ozon hóa, hoc dùng èn t ngoi.
UNIT 12 : TYPES OF REACTORS
Batch Reactors - The batch reactor is, in essence, a kettle or tank. It should have a number of
accessories in order to operate satisfactorily.
First of all it generally must be closed, except for a vent, in order to prevent loss of material and
danger to the operating personnel. For reactions carried out under pressure the vent is replaced by a safety
valve.
High-pressure conditions frequently introduce complications in the design and greatly increase the
initial cost. For example, the top closure must be able to withstand the same maximum pressure as the rest
of the autoclave. At medium pressures a satisfactory closure can be assembled. It is usually necessary to
agitate the reaction mixture in batch systems. This can be done mechanically with stirrers operated by a
shaft extending through the reactor wall.
Provision for heating or cooling the reaction contents is often required. This may be accomplished
by circulating a fluid through a jacket surrounding the reactor. Where heat effects are large enough to
require the most rapid heat transfer, the jacket may be augmented by heating or cooling coils immersed in
the reaction mixture.
Flow reactors. Flow reactors may be constructed in a number of ways. The conventional thermalcracking
units in the petroleum industry are examples of a noncatalytic type. The gas oil or other
petroleum fraction is passed through a number of alloy-steel tubes placed in a series on the walls and roof
of the furnace. Heat is transferred by convection and radiation to the tube surface in order to raise the
temperature of the gas oil to the reaction level/ 600 to 1000 0 F/ and to supply the endothermic heat of
reaction. On the other hand, flow reactors may consist of a tank or kettle, much like a batch reactor, with
provision for continuously adding reactants and withdraw product. From a design viewpoint the essential
difference between tubular and tank reactors lies in the degree of mixing obtained. In the tubular type,
where the length is generally large with respect to the tube diameter, the forced velocity in the direction of
flow is sufficient to retard mixing in the axial direction. On the other hand, in tank reactors, it is possible
to obtain essentially complete mixing by mechanical agitation. Under these conditions the composition,
temperature and pressure are uniform through the vessel.
EXERCISES
A. Read and translate into Vietnamese
kettle, tank, accessories, autoclave, agitate, mixture, stirrers, circulating, jacket, coils, petroleum, roof,
furnace, endothermic, batch reactor, tubular, velocity
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