10+ Docterz Interview Questions and Answers

The flowsheet of a methanol plant involves several steps including synthesis gas production, purification, methanol synthesis, and distillation.

• The first step in the methanol plant flowsheet is the production of synthesis gas, which is a mixture of carbon monoxide and hydrogen.

• The synthesis gas is then purified to remove impurities such as sulfur compounds and carbon dioxide.

• Next, the purified synthesis gas is fed into a methanol synthesis reactor, where it reacts over a cata...read more

Increasing reflux ratio reduces condenser duty.

• Higher reflux ratio means more liquid is returned to the column.

• This increases the liquid flow rate in the column.

• As a result, less vapor needs to be condensed in the condenser.

• Reduced condenser duty leads to lower energy consumption.

• Example: If the reflux ratio is doubled, the condenser duty may be halved.

Discharge pressure increases at the outlet of a reciprocating compressor due to compression of the gas.

• During the compression process, the gas molecules are forced into a smaller volume, resulting in an increase in pressure.

• The reciprocating motion of the compressor piston compresses the gas in the cylinder, leading to an increase in pressure.

• The discharge valve of the compressor prevents the compressed gas from flowing back into the cylinder, causing the pressure to build up...read more

Shell and tube heat exchangers are used for heat transfer between two fluids, while condensers in ACs are specifically designed to convert vapor into liquid.

• Shell and tube heat exchangers have a shell (outer vessel) and tubes (inner vessels) for fluid flow.

• They are used in various industries for applications such as cooling, heating, and condensing.

• Condensers in ACs are a type of heat exchanger that specifically convert vapor into liquid.

• They are designed to remove heat from ...read more

Water cannot be used instead of air cooled condensers due to several reasons.

• Water is a poor conductor of heat compared to air, resulting in less efficient heat transfer.

• Using water as a coolant requires a constant supply of water, which may not be feasible in all locations.

• Water cooling systems are more complex and expensive to install and maintain compared to air cooling systems.

• Water cooling systems pose a higher risk of leaks and potential damage to equipment.

• Air cooled c...read more

Heat is transferred in a cooling tower through a combination of evaporation, convection, and radiation.

• Evaporation: Water is sprayed into the cooling tower, and as it evaporates, it absorbs heat from the surrounding air.

• Convection: The warm water from industrial processes is circulated through the cooling tower, and as it comes into contact with the air, heat is transferred through convection.

• Radiation: Heat is also transferred through radiation, where the warm water and the ...read more

Volumetric efficiency of a compressor is the ratio of actual volume of air delivered to the theoretical volume it should deliver.

• Volumetric efficiency is expressed as a percentage.

• It measures how well a compressor is able to deliver the desired volume of air.

• Factors affecting volumetric efficiency include compressor design, speed, temperature, and pressure.

• Volumetric efficiency can be improved by optimizing compressor design and reducing losses.

• For example, if a compressor ha...read more

The wet bulb temperature should be more in an air conditioned room than in ambient temperature.

• The wet bulb temperature is a measure of the lowest temperature that can be achieved by evaporative cooling.

• In an air conditioned room, the air is typically drier and the evaporation rate is higher, leading to a lower wet bulb temperature.

• In ambient temperature, the air is usually more humid, resulting in a higher wet bulb temperature.

Bernoulli's principle explains the relationship between fluid speed and pressure, while Archimedes' principle explains buoyancy.

• Bernoulli's principle states that as the speed of a fluid increases, its pressure decreases.

• This principle is commonly observed in the lift generated by an airplane wing or the flow of water through a pipe.

• Archimedes' principle states that an object immersed in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid.

• Thi...read more

Wet and dry bulb temperature are used to measure humidity and determine the level of moisture in the air.

• Wet bulb temperature is the lowest temperature that can be reached by evaporating water into the air.

• Dry bulb temperature is the temperature of the air measured by a regular thermometer.

• The difference between wet and dry bulb temperatures can be used to calculate relative humidity.

• Wet bulb temperature is lower than dry bulb temperature in humid conditions.

• Dry bulb temperat...read more