Batch conveying

Figure 4.6 Sketch showing the transient nature of batch conveying.

The size of a filter, in terms of fabric surface area required, is specified approximately in terms of the volumetric flow rate of gas to be handled. Filtration plant is designed for steady state conditions and so if there are likely to be surges and transient effects in performance due to batch conveying or pipeline purging, for example, these effects must be taken into account. Filter fabrics will not last forever, and it is important that maintenance schedules are kept. 

This representation is easily understandable by those knowledgeable about the process technology and is a convenient mechanism for conveying the process requirements to the control engineers responsible for implementing the batch logic. 

Each chapter starts with a description of the topic covered in the chapter. This is followed by a short example highlighting a reported incident involving a batch reaction system. The case study is followed by a listing of key issues and process safety practices unique to the topic. The issues and concerns presented in this book, as well as potential design solutions and sources of additional information are presented in the tables. This format concisely conveys the necessary and relevant information in a familiar and convenient format. The organization of the tables is described below. 

All manufacturing industries produce peculiar wastes from their production processes. The bulk of the wastes is conveyed to the wash waters that end up as wastewaters. The washing operations include washing of raw materials, the intermediate and final products, the plant (before and after production batch), and unsolicited rain storm that washes the exposed plant parts. 

The specific equipment used for each step depends on the incinerator type and the physical and chemical characteristics of the wastes the incinerator is designed to bum. Wastes are fed into the incinerator in batches or in a continuous stream. Liquid wastes are often pumped and atomized into fine droplets that bum more easily. Solid wastes may be fed into the incinerator in bulk or in containers using a conveyer, a gravity system, or a ram feeder.8... 

Pelletisers are designed to convert a Banbury mixer batch into free flowing pellets which can easily be conveyed to the next step in a process. 

It is possible to operate a fluidized bed in either batch or continuous mode. Strictly, most batch applications are in tact operated in semibatch mode where the solids are treated as a batch but the fluidizing medium enters and leaves the bed continuously. In the case ot gas-solid beds used in termentation (see Chapter 6), the fluidizing gas is recirculated although reactants and products flow continuously. In true continuous operation the solids may be ted into a fluidized bed via screw conveyors, weigh teeders or pneumatic conveying lines and can be withdrawn trom the bed via standpipes or by flowing over weirs. 

Therefore, the dispenser control panel should be equipped with a timer-relay device to insure that all admixture has been discharged from the conveying hoses or pipes. If the admixture dispenser system is operated manually, the plant operator should be furnished a valve with a detente discharge side to prolong the discharge cycle until it is ascertained that all admixture is in the concrete batch. 

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