Horizontal-Tank Type

Horizontal-Tank Type This type (Fig. ll-56a) is used to transfer heat for melting or cooking diy powdered solids, rendering lard from meat-scrap solids, and drying divided solids. Heat-transfer coefficients are 17 to 85 W/(m °C) [3 to 15 Btu/(h fF °F)] for drying and 28 to 140 W/(m °C) [5 to 25 Btu/(h fF °F)] for vacuum and/or solvent recovery. 

FIG. 11-56 Heat-transfer equipment for fusion of solids, a) Horizontal-tank type. (Coutiesy of Sttxithers Wells Corp. ) (h) Agitated kettle. (Cowtesy of Read-Standard Division, Capital Products Co.) (c) Donble-dnim mill. (Coutiesy of FaiTel-Bitmingham Co.)... 

The two types of vessel geometries employed are vertieal and horizontal. In most of the fine ehemieals proeesses the leaves are fitted into vertieal vessels whereas horizontal vessels are used in the heavier process industries sueh as the preparation of sulfur in phosphoric acid plants. The leaves inside horizontal tanks may be positioned either along the tank axis or perpendieular to the axis. In order to utilize the tank volume for maximum filtration area the width of the leaves is graduated so they fit to the eireular eontour of the tank. 

The majority of storage tanks are of the horizontal cylindrical type, as shown in Figure 18.1. Where ground space is a limiting factor, vertical cylindrical tanks may be used. 

Backwashing can be by water alone or by an air scour and water. Usually where high volumes of water are encountered a horizontal type is used because the tank length can be increased proportional to the volume. However, horizontal tanks are restricted to lower levels of suspended solids because of limitations in media bed depth. They are also prone to the risk of the underbed shifting, with a consequential decrease in filtering efficiency. 

For onshore facilities, water may be supplied from local public water mains, storage tanks, lakes and rivers. In these cases a conventional horizontal pump is used. The preferred design for onshore fire water pumps is a horizontal centrifugal type with a relatively flat performance curve (i.e., pressure versus quantity). The discharge pressure is determined by the minimum residual pressure required at the most remote location of the facility flowing its highest practical demand with allowances added for piping friction losses. 

Various filter designs are available to the industry, including plate and frame filter presses, horizontal tank/ vertical leaf pressure filters with retractable bundles or shells, and vertical tank/vertical leaf pressure filters. The latter (Figure 29) has been accepted by the industry as perhaps the best overall choice in terms of price, performance, space requirements, and ease of automation. Filter sizes up to 85-m filter area/filter are available with this model. However, the horizontal tank/vertical leaf model with either retractable bundle or retractable shell also has its proponents. Commonly, a major factor in deciding on this type filter is the fact that these units are available in sizes up to 200-m filter area/filter. 

For more efficient leaf cleaning, horizontal tank-vertical leaf filters are made with various types of movable sluices. 

Plug Flow Digester - A type of anaerobic digester that has a horizontal tank in which a constant volume of material is added and forces material in the tank to move through the tank and be digested. 

The circulation of liciuid through this type of long horizontal tank was found to set up wa cs which interfered with vapor withdrawal. This interference was minimized by the use of baffle plates, as. shown in Fig. 8-12(d). 

Wet Oxidation Reactor Design. Several types of reactor designs have been employed for wet oxidation processes. Zimpro, the largest manufacturer of wet oxidation systems, typically uses a tower reactor system. The reactor is a bubble tower where air is introduced at the bottom to achieve plug flow with controlled back-mixing. Residence time is typically under one hour. A horizontal, stirred tank reactor system, known as the Wetox process, was initially developed by Barber-Cohnan, and is also offered by Zimpro. 

Steep-Angle Conical Bottoms. Tanks often have a conical bottom where the slope exceeds 15—20° from the horizontal. This provides for complete drainage or even soflds removal. Because these types of tanks are more cosdy, they are limited to smaller sizes. Such tanks are often found in the chemical industry or in processing plants. 

Pressure Leaf Filters Sometimes called tank filters, they consist of flat filtering elements (leaves) supported in a pressure shell. The leaves are circ ilar, arc-sided, or rectangular, and they have filtering surfaces on both faces. The shell is a cylindrical or conical tank. Its axis may be horizontal or vertical, and the filter type is described by its shell axis orientation. 

Types of Jigs A jig is essentially an open tank filled with water and provided with a horizontal screen on the top and a hutch compartment fitted with a spigot (Fig. 19-27 ). A layer of coarse, heavy particles, known as ragging, is placed on the top of the screen onto which the feed slurry is introduced. The feed moves over the ragging and the separation takes place as the bed is pulsated by a different mechanical device. The heavy particles are collected into the hutch compartment and removed through the spigot while the hghter particles are made to overflow from the top or the tank. 

Horizontal Blowdown Drum/Catch Tank This type of drum, shown in Fig. 26-16, combines both the vapor-liquid separation and holdup functions in one vessel. Horizontal drums are commonly used where space is plentiful, such as in petroleum refineries and petrochemical plants. The two-phase mixture usually enters at one end and the vapor exits at the other end. For two-phase streams with very high vapor flow rates, inlets may be provided at each end, with the vapor outlet at the center of the drum, thus minimizing vapor velocities at the inlet and aiding vapor-hquid separation. 

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