Waste-Disposal Flow Diagram

The waste-disposal flow diagram illustrates the waste streams for which there is no further economic use in the plant (see Section 1.3) and indicate their flow numbers from the process flow diagram. Precise information should be given on the toxicity, degradability, water danger, flash point, ignition temperature, MAK, odor threshold, etc. of the individual components, their mass flows, and the state of aggregation of the flow (viscosity, sediment content, etc.). This information makes it possible to specify the type of waste disposal required with consideration of site-specific and economic factors, for example  

Special attention must be paid to the available capacity of existing sewage treatment plants and landfill sites. The construction of new capacities has often delayed or prevented the erection of a new production plant, since the resulting additional costs increased the production costs of the new product to too great an extent or even made it uneconomical. Here a network of production sites has major advantages. 

An important reason for preparing study reports is to determine the capital expenditure (investment) of a project [Muthmann, 1984, Prinzing 1985, DAdda 1997]. This is made up of the location-independent ISBL (inside battery limits) process plant costs such as investment in the production plant and the associated control rooms, laboratories, employee facilities, tank farms, and loading and unloading stations, as well as the location-dependent OSBL (outside battery limits) costs of all the service facilities. 

The accuracy of the investment cost estimate depends critically on the level of maturity the process has reached [Jung 1983]. 

Since direct plant costs are always estimated for some date in the future, it is necessary to determine the effect of increases in price. Use is therefore made of price indexes which are published for chemical plants in the individual countries (Table 6.1-2). The price index i determined by extrapolation is divided by the index Iq at the date of the cost determination. The ratio i/io is then a measure of the increase in investment costs to be expected. 

---

Propylene oxide is purified by steam stripping and then distillation. Byproduct propylene dichloride may be purified for use as a solvent or as a feed to the perchloroethylene process. The main disadvantage of the chlorohydrination process is the waste disposal of CaCl2. Figure 8-3 is a flow diagram of a typical chlorohydrin process. 

Figure 12.1 I This flow diagram shows some of the considerations that enter into the thinking of a process engineer involved with the industrial production of HCN. Issues of product formation and waste disposal need to be examined in terms of both chemistry and economics.

---