Water demand for

Increasing the number of stages in an extraction process to reduce the water demand for a given separation. 

Figures 12.21a and b represent targeting in the (2-3 h) time interval. This interval constitutes three active processes as shown in the graph and the accompanying block diagram for this time interval. These processes are the B and C reactions, as well as the A wash. The overall water demand for this interval is thus 1560 kg, but 1280 kg is already available from the previous time interval. Therefore, only 280 kg of fresh water is required.

The process area has combustible gas detectors, fireproofing, and a water deluge system. Cable trays are protected with deluge, and portable dry chemical extinguishers are in the process area. Diesel-powered fire water pumps can provide a maximum fire water demand for 4 hr. 

Structures with equipment on two or more levels, not protected by water spray or deluge systems, should be counted as double the grade area beneath the multilevel structure plus the areas as noted above. Where fixed water spray systems are provided, their water requirements should be added to the fire water demand. Water demands for other areas within a plant may include ... 

The water demand for enclosed process structures may depend on the degree of compaitmentalization by solid floors and the number of separate systems used to protect the structure. At a minimum, ground floor systems should be assumed to operate in a spill fire scenario. But, if water spray systems are used, it should be assumed that all systems will operate in order to estimate maximum water demand. 

For open structures protected by water spray systems, it should be assumed that all systems within the structure will operate. The water demand for each system is summed to get the total demand for the unit plus manual firefighting. 

In the production of limestone aggregate, the selection of appropriate crushers (see section 5.2) helps to ensure an acceptable particle shape. Well designed screens help to ensure that the aggregate is of the correct size and that it has a low content of fines and clay, all of which have a marked effect on the water demand for a given workability. The strength and durability of the hardened concrete is generally related to the water demand. 

Most of the industry today has emission limits and concessions that are subject to change. The new limitations will obviously be stricter regarding emissions to air and water. Demands for higher operating time and lower emission levels will increase. 

At higher temperatures in hot weather, additional water demand for mixing water leads to an increased water-cement ratio, thus adversely affecting the strength of the concrete. 

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