Ice Types and How They Are Made - 1
En son güncellendiği tarih: 8 Tem 2020
Block ice was first produced commercially in 1869. It is done by filling the metal cans with water and lowering the water to a cooling saltwater bath (usually sodium or calcium chloride) well below the freezing point. The water in the boxes freezes, and after freezing for a few hours, the ice blocks are removed from the boxes. The boxes are dipped into freshwater to release ice blocks, which are then stored.
Capacities and basic dimensions of various ice-making machines suitable for use in fishing boats
Outputs based on an ambient temperature of 32 ° C (90 ° F).
Outputs based on an ambient temperature of 10 ° C (50 ° F).
According to the outlet 0 to 1 ° C feed water, the pre-mixer unit is recommended.
Block ice production is a batch process and once emptied, the cans are filled with water and replaced in the brine tank for a subsequent freezing period. Regardless of the capacity of the ice maker for block ice production, a continuous workforce is required to manage all operations, especially ice collection and processing. The main advantages of block ice compared to other types of ice are:
simple and easy storage, transport and transportation;
relatively slow melting rate and therefore losses during storage and distribution are minimal;
ice is compact and therefore less storage space is required;
Ice can be reduced to any particle size as required by crushing before use;
the facility is robust engineering and relatively easy to maintain by a qualified mechanical engineer;
ice can be easily handled and sold by the block.
The main disadvantages of block ice production are:
long time required to complete freezing of water in cans (8-36 hours) (block size 12 to 140 kg);
high labor costs and constant attention to operations;
it is not a continuous automated process and it takes a long time to produce ice from the very beginning;
the ice plant itself has more space requirements than modern automatic ice makers;
adequately treated brines are required to minimize equipment corrosion; Ice must be crushed before use.
There are ice block factories, ice storage, and container block ice facilities that contain complete cooling and electrical systems in standard containers. This allows portability, ease of access by sea and land, better reliability, and significantly shorter setup and running-in times than conventional uncoated types. These advantages are especially important in remote areas with limited cooling and maintenance expertise. These units are installed in standard 40 ft containers and are easy to install. They just need a flat foundation and are covered undercover to protect them from the weather and can be built in tropical climates and coastal conditions. There are units that produce blocks of various sizes from 12.5 to 25 kg.
In general, the thicker the ice block, the longer the freezing time. For example, a 136 kg block will require an average of 36 hours of freezing time compared to a 25 kg block that requires an average of 12 hours.
Typical features of container block ice plants
Nominal capacity in continuous harvesting. The ice storage temperature is about -5 ° C; With an eight-hour ice cream cycle.
Fast block ice
The long periods required to produce ice blocks have led to the development of what is known as fast block ice plants. The purpose of these plants is to produce ice blocks within a few hours. Instead of iceboxes immersed in a brine tank, the water in the box is frozen by a cooler that is circulated through the outer jacket of each box and also through a tubing system placed inside the boxes. Ice is formed simultaneously on all cooled surfaces that come into contact with water.
After the completion of the freezing cycle, the blocks are quickly removed from the can by means of hot gas defrost and released by gravity. The main advantages of fast block ice makers are fewer space requirements compared to conventional block ice makers, and relatively easy operations for starting and stopping are short compared to traditional block ice makers. However, the purchase, operation, and maintenance of fast block ice plants are generally more expensive than traditional block ice plants and their use in the fishing industry is limited.