ANS:A - basket type

Intermittent tube cleaning is possible to be done in the case of a horizontal tube evaporator. Explanation:

1. Horizontal Tube Evaporator: In a horizontal tube evaporator, the tubes are typically arranged horizontally, allowing for easy access to the tube bundle. This design facilitates periodic or intermittent tube cleaning operations.
2. Intermittent Tube Cleaning: Tube fouling is a common issue in evaporators due to the concentration of dissolved solids or other impurities in the liquid being evaporated. Over time, these deposits can accumulate on the inner surfaces of the tubes, reducing heat transfer efficiency.
3. Tube Cleaning Methods: Various methods can be employed to clean the tubes in an evaporator, including mechanical methods such as brushing or scraping, chemical methods using cleaning solutions, or thermal methods involving steam or hot water flushing.
4. Accessibility: The horizontal orientation of the tubes in a horizontal tube evaporator allows for easier access to the tube bundle compared to other configurations such as vertical tube or basket type evaporators. This makes it more feasible to perform intermittent tube cleaning operations as needed.
5. Other Types of Evaporators: While intermittent tube cleaning may still be possible in other types of evaporators such as basket type or calendria evaporators, the accessibility and ease of cleaning may vary depending on the specific design and arrangement of the evaporator components.