Simple Solutions That Work! Issue 8

The successful start-up and operation of a pneumatic sand conveying system is not only based on the functional design features of the system but also on following specific system based installation instructions from the vendor and applying proven work procedures. When contracting for the installation of a pneumatic conveying system the owner depends on the installing contractor to not only install the components properly but also perform the start-up function of the entire system and turn it over to the owner as a fully and properly functional system. Since the preferred method of pneumatic conveying of sand is by a pressure or dense phase system, rather than a vacuum or dilute phase system, we will concentrate in this article on a dense phase type pneumatic sand conveying system. The basic difference between a dense phase system and a vacuum or dilute phase system is the velocity of the sand travelling thru the piping system whereby in a vacuum or dilute phase system the sand travels in a fluidized state at around 4000 feet per minute while in a well designed dense phase system the sand travels in plugs or slugs at design velocities of only 400 to 1500 feet per minute. Naturally, the lower velocities in a dense phase system minimize pipe wear and sand degradation and the generation of dust from the impingement of the sand grains on the pipe walls. It is most helpful if the installing contractor’s personnel are familiar with the basic operating principles of the conveying system so that they, in addition to the installation instructions of the vendor, can use their own intuition to provide the necessary work procedures for a successful project completion. Each vendor of pneumatic sand conveying systems probably has their own installation instructions, however, in addition to or the absence of such directions the following main topics should be considered for a successful installation; 1. Location and positioning of transporter blow tank Always consider the location of the transporter blow tank and the optimum routing of the piping system to the receiving bin(s). Normally the transporter blow tank is being fed with sand by gravity from an overhead silo or bin. Two shut-off valves are needed in the feed pipe connection, one (hand operated) to isolate the blow tank from the sand feed (for maintenance purposes) and one (automatically controlled from the transporter controls) functioning as part of the fill cycle. No external loads should be transferred to the transporter. Transporter should not be lagged to the floor until the entire installation is complete and the required pressure test of the piping system has been completed satisfactorily. 2. Number of receiving bins for sand and isolation/fill valves Determine and consider the actual number and relative location of receiving bins to the transporter blow tank and for multiple receiving bins evaluate proper diverter piping with an isolation/fill valve for each receiving bin. To operate properly the transporter system should deliver sand to only one receiving bin at a time and all fill/isolation valves for the remaining bins should be closed except the fill valve for the receiving bin to be filled with sand. If a transport system has only one receiving bin/silo then only one end discharge fitting is required, without the need of an isolation/ fill valve. CHRIS DOERSCHLAG Consultant PALMER MANUFACTURING & SUPPLY, INC. – KLEIN DIVISION ARTICLE TAKEAWAYS: • Dense phase vs. dilute phsae systems • Location–blow tank, bins, and pipe run GUIDELINES FOR THE SUCCESSFUL INSTALLATION AND OPERATION OF A PNEUMATIC SAND CONVEYING SYSTEM 18